CA1279091C - Single connection gas discharge display and driver - Google Patents
Single connection gas discharge display and driverInfo
- Publication number
- CA1279091C CA1279091C CA000562986A CA562986A CA1279091C CA 1279091 C CA1279091 C CA 1279091C CA 000562986 A CA000562986 A CA 000562986A CA 562986 A CA562986 A CA 562986A CA 1279091 C CA1279091 C CA 1279091C
- Authority
- CA
- Canada
- Prior art keywords
- gas
- tube
- voltage
- ionization
- cathode element
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
- G09F13/00—Illuminated signs; Luminous advertising
- G09F13/26—Signs formed by electric discharge tubes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J17/00—Gas-filled discharge tubes with solid cathode
- H01J17/38—Cold-cathode tubes
Abstract
ABSTRACT OF THE DISCLOSURE
An elongate cold cathode gas discharge tube comprises a gas discharge tube containing an ionizable gas having a cathode element disposed to cause ionization of the gas and a power source connected to provide an alternating voltage, referenced to ground potential, to the cathode element and of sufficient magnitude and frequency to cause the gas to ionize through the natural surrounding capacitance between the ionized gas and ground potential, the power source being adjustable to provide a variable voltage thereby to vary the extent of ionization of the gas, along the tube in a direction away from the cathode element.
An improved method of causing illumination of an elongated cold cathode gas discharge tube containing an ionizable gas and having a cathode element disposed to cause ionization of the gas comprises the steps of:
(a) connecting an alternating voltage referenced to ground potential and of sufficient frequency to cause the gas to ionize through the natural surrounding capacitance between the ionized gas and ground potential to the cathode element; and (b) varying the voltage between first and second levels whereby the extent of ionization of the gas along the tube in a direction away from the cathode element will vary with and be determined by the voltage.
An elongate cold cathode gas discharge tube comprises a gas discharge tube containing an ionizable gas having a cathode element disposed to cause ionization of the gas and a power source connected to provide an alternating voltage, referenced to ground potential, to the cathode element and of sufficient magnitude and frequency to cause the gas to ionize through the natural surrounding capacitance between the ionized gas and ground potential, the power source being adjustable to provide a variable voltage thereby to vary the extent of ionization of the gas, along the tube in a direction away from the cathode element.
An improved method of causing illumination of an elongated cold cathode gas discharge tube containing an ionizable gas and having a cathode element disposed to cause ionization of the gas comprises the steps of:
(a) connecting an alternating voltage referenced to ground potential and of sufficient frequency to cause the gas to ionize through the natural surrounding capacitance between the ionized gas and ground potential to the cathode element; and (b) varying the voltage between first and second levels whereby the extent of ionization of the gas along the tube in a direction away from the cathode element will vary with and be determined by the voltage.
Description
7~()'31 sack~round of the Invention:
The present invention relates to displays and, more particularly to an illuminated display comprising, an elongated cold cathode gas discharge tube containing an ionizable gas, the tube having a single cathode element at one end in contact with the gas: and, a power source connected to ionize the gas and cause illumination thereof, the power source being connected to the single cathode element and producing alternating voltage referenced to ground potential and of sufficient frequency to cause the gas to ionize through the natural surrounding capacitance between the ionized gas and ground potential.
Cold cathode gas discharge displays are old and well known in the art. The most familiar is the "neon sign"
which has remained virtually unchanged from time immemorial. In neon signs, an elongated glass tube is filled with an ionizable gas, such as neon. The tube has a pair of cathode elements passing through the glass at the ènds of the tube into contact with the gas. The secondary of a high voltage, current limited transformer is connected across the cathode elements. The primary of the transformer is connected via a plug to a standard 110 volt, 60 Hz wall socket, or the like, which results in a 60 Hz, high voltage being applied across the gas by the cathode elements. The high voltage causes the gas to ionize and glow, thus causing the desired illumination. Particularly as the signs get older, the use of high voltage causes buzzing, and the like, which is annoying and disruptive.
Neon signs are typically used in two ways. They can be disposed behind a display panel having indicia thereon and used to illuminate the panel. More commonly, the tubes are formed into the letters, or the like, to convey the desi~ed message. In either case, however, the entire length of the tube must be energized simultaneously. For "movement" of the display, individual tubes comprising the . , , .
.~
'30'31 various segments must be employed with each connected to an individual source of power. Moreover, timing and power control circuits must typically be utilized in this approach.
The present invention seeks to provide a new approach to the manner of operation of gas discharge tubes which provides for ionization of the gas with a single cathode element for low voltage operation, for selective ionization and illumina-tion of portions of the tube, and, for moving illumination of the tube in an illuminated handwriting style.
According to one aspect of the present invention there is provided a cathode gas discharge tube device which includes an elongated cold cathode gas discharge tube containing an ionizable gas, the tube having a cathode element disposed to cause ionization of the gas along a length of the tube forming the display portion thereof. The device further includes a power source connected to ionize the gas and cause illumination thereof, the power source being connected to the cathode element and producing changing voltage reference to ground potential and of sufficient frequency to cause the gas to ionize through only the natural surrounding capacitants along the display portion of the tube between the ionized gas and the ground potential. The power source produces a variable voltage output so that the extent of ionization of the gas, along the tube in a direction away from the cathode element, will vary with and be determined by the voltage output.
Another aspect of the invention resides in a method of causing illumination of an elongat~d cold cathode gas discharge tube containing an ionizable gas and having a cathode element disposed to cause ionization of the gas along the length of a tube forming a display portion thereof. The method includes the step of connecting to the cathode element a power source of a changing voltage reference to ground potential, the power source being a sufficient frequency to cause the gas to ionize through the natural surrounding capacitants along the display portion of the tube between the ., ' .'':- :'' '-.. . .
1i~'79(~
ionized gas and ground potential. The method ~urtherincludes the step of varying the voltage between first and second levels so that the extent of ionization of the gas along the tube in a direction away from the cathode element will vary with and be determined by the voltage.
Description of the Drawinqs-.
Other objects and benefits of the present invention will become apparent fro~ the description contained hereinafter in combination with the illustrative drawing figures.
Figure 1 is a simplified drawing of a prior art gas dis-charge tube display of the "neon sign" variety.
Figure 2 is a simplified drawing showing the manner of operation of the present invention.
Figure 3 is a graph of the voltage ramp applied to the single cathode element in the present invention.
Figures 4a, 4b, 4c, and 4d show the progress of ioniza-tion of the gas in the tube according to a first manner of operating the present invention.
Figures 5a, 5b, 5c, and 5d show the progress of ioniza-tion of the gas in the tube according to a second manner of operating the present invention.
Figures 6a, 6b, 6c, and 6d show the progress of ioniza-tion of the gas in the tube according to the third manner of operating the present invention.
Figure 7 is a block diagram showing how the present invention can be employed to selectively illuminate the display tube according to various possible external func-tions.
Figure 8 is a simplified drawing showing how the present invention can be used to progressively illuminate portions of a display having indicia thereon with only a single tube.
Figure 9 is a simplified graph showing how in the preferred driver circuit of the present invention the frequency of the voltage ramp is decreased as the plasma ,~
1;~'7{3(~'31 being formed increases and correspondingly has more available capacitance to ground to automatically compensate for that phenomenon.
Figure 10 is a circuit diagram of a circuit as employed in a tested embodiment of the present invention.
Description of the Preferred Embodiment:
As explained earlier, cold cathode gas discharge displays are old and well known in the art. The most familiar is the "neon sign" 10 of Figure 1, which has remained virtually unchanged from time immemorial. In neon sign 10, an elongated glass tube 12 is filled with an ionizable gas 14, such as neon. The tube 12 has a pair of cathode elements 16 passing through the glass at the ends of the tube 12 into contact with the gas 14. The secondary of a high voltage, current limited transformer 18 is connected across the cathode elements 16. The primary of the trans-former 18 is connected via plug 20 to a standard 110 volt, 60 Hz wall socket, or the like, which results in a 60 Hz, high voltage being applied across the gas 14 by the cathode elements 16. The high voltage causes the gas 14 to ionize and glow, thus causing the desired illumination. Particular-ly as the signs get older, the use of high voltage causes buzzing, and the like, which is annoying and disruptive.
Neon signs such as 10 are typically used in two ways.
They can be disposed behind a display panel having indicia thereon (not shown) and used to illuminate the panel. More commonly, the tubes 12 are formed into the letters, or the like, to convey the desired message. In either case, however, the entire length of the tube 12 must be energized simultaneously. For "movement" of the display, individual tubes comprising the various segments must be employed with each connected to an individual source of power. Moreover, timing and power control circuits must typically be utilized in this approach.
The method o~ operation upon which the present invention ' ' ' .
1;~'7~
is based requires only a single cathode element at one end of the tube. This is possible because the natural capacitance to ground potential between the ionized gas and its surroundings is employed.
A low voltage, high frequency potential is applied to the single cathode element which, in the presence of a low enough reactive impedance to the high frequency energy, causes plasma ignition of the gas. This property and approach allows much more control over the gas within the tube and its manner of ionization than in prior art displays, as will be described shortly. For example, the ignited plasma can be made to travel along the tube creating a defined bright ionization front. This can be a preprogrammable event where the plasma ignites, travels steadily to the end of the tube, and then repeats the process thus creating a unique hand-writing effect in light. The position of ignition and termination can be automatically or manually controlled. Varying voltage levels such as those from the output of an audio amplifier can also be made to vary the plasma lighting discharge effect. Such possibilities and capabilities, of course, greatly enhance the attention gaining ability of signs and similar displays wherein they are incorporated. As will be seen, the present invention also provides the capability of producing multiple segments without the necessity of employing duplicate components as in prior art.
Turning first to Figures 2 and 3, the principle of operation of the present invention will be described briefly. As in the prior art, a display tube 12 of glass, or the like, containing an ionizable gas 14 is employed. A single cathode element 16 is required at one end. As can be appreciated, old prior art tubes can be employed with the present invention by simply ignoring the ca~hode element 16 at the opposite end. The single cathode element 16 is connected to the output of a power source 22 which produces high frequency, low voltage referenced to ground potential and of sufficient frequency to cause the gas to ionize through the natural surrounding capacitance between the -~
. . , .. ' ` ' , : . ., .~ , .
~ ;~790'~31 ionized gas and ground potential as represented by the capacitors generally indicated as 24. The power source 22 is connected to a conventional 110 volt 60 Hz power outlet or a DC outlet by means of plug 20, the only requirement for the power outlet being that it be polarized with one side referenced to earth ground. As shown in Figure 3, one form of output of the power source may be a high frequency voltage ramp that increases over time so as to move the ionization point along the tube 12 from one end to the other. As in a television tube, the voltage output drops to a "zero" state (i.e. no ionization of the gas 14 taking place) in a very short period indicated in the figure as the "retrace time" and then repeats the pattern of Figure 3.
By varying the initial and final voltage levels of the ramp of Figure 3 which represents the output of the power source 22 applied to the single cathode element 16 of the display tube 12, various display features as depicted in Figures 4-6 can be achieved. As will be appreciated, these features cannot be achieved in the prior art and afford many possibilities for the display of the present invention. For example, in the sequence of Figure 4(a), 4(b), 4(c), and 4(d), the front on the ionization portion 26 is seen to move along the tube as a bright band of illumination fully from one end of the tube to the other; that is, from the end of the single cathode element to the other. In the sequence of Figure 5(a), 5(b), 5(c), and 5(d), the front of the ionization portion 26 moves along the tube from an initial point displaced from the cathode element end of the tube fully to the other end. In the sequence of Figure 6(a), 6(b), 6(c), and 6(d), the ionization portion 26 moves along the tube from an initial point displaced from the cathode element end of the tube to a point short of the other end. As this last example illustrates, the present invention allows a segment of any length of the tube between the ~' .. . . .
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~7~3()'31 starting end of the tube and preselected points along the tube to be selectively illuminated. As will be appreciated by those skilled in the art, therefore, by changing the point of illumination termination, the segment of the tube 12 being illuminated can be made to change.
As illustrated in Figure 7, in the preferred embodiment of the present invention, the display driver portion power source 22 of the present invention is made responsive to various external functions as represented by the box 30 connected thereto. Thus, the output of an audio amplifier can be employed to change the voltages of the power source 22 or modulate the frequency thereof so as to create display patterns with the tube 12 which are a function of the audio signal. A function generator can be employed to create particular display patterns and sequences. A transducer can be employed for certain uses. For example, a force transducer could change the position of the illumination of a tube disposed next to a scale so as to create an indicator for force measurement or a scale for weighing. A manual control can be employed for manually setting the position of illumination as, for example, to move the illuminated portion of the tube to selectively light up "VACANCY" or extended to light up '!NO VACANCY" portions of a sign at a business.
A display system according to the present invention which would not have possible in the prior art without elaborate controls sequencing between multiple tubes is shown in Figure 8. A single tube 12 connected to the power source of the present invention (not included in the figure for simplicity) is disposed behind a display panel or sign 32 of translucent material and having indicia 34 thereon conveying a message, such as the message of Figure 8, EAT AT
JOE'S. For larger signs, multiple tubes could be used in parallel. AS shown in Figure 8(a), the initiation and termination point for illumination of the tube(s) 12 is first set in the power source 22 so as to illuminate a first . . ~
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:
.
,' ~ ' '' .
'~'`, ` ':
- ' . -.
~ ~ ' ' : , .
'. ; ' ~'7~0~31 portion behind the word EAT. After a period of time, the termination point for illumination of the tube(s) 12 is next set in the power source ~2 so as to illuminate the additional portion behind the word AT. After a similar period of time, the termination point for illumination of the tube(s) 12 is set to illuminate the additional portion behind the word JOE'S. The word JOE'S remains illuminated for its period of time and then the process repeats. The result is a visually perceptible sequence of illumination of the in-dividual words EAT -- AT -- JOE'S employing only one tubets) and one power source.
Another feature of the present invention as incorporated into the tested circuitry of the power source to be described shortly is illustrated in the simplified graph of Figure 9. As the plasma in the display tube is ionized the available capacitance to ground increases in proportion to the quantity of gas within the tube which is ionized. To compensate for that natural effect, the preferred embodiment of the present invention correspondingly reduces the frequen-cy of the voltage ramp to adjust for the change in available capacitance and thereby retain linear response to the output of the power source.
A circuit for the power source to drive a display tube according to the present invention as employed in tested embodiments by the applicant is shown in Figure 10. While the construction and operation of the circuit should be apparent to those skilled in the art from an inspection thereof, a brief explanation will now be provided to assure complete understanding. More particularly, the circuit of ', :
.
.
.
1~79091 Figure lo operates as follows.
The plug 20 is plugged into a conventional llo volt, 60 Hz power outlet. Note, however, that plug 20 must be of the polarized variety wherein one side is referenced to actual ground potential as where a rod at the power pole or otherwise is driven into the earth. This is to say, since the capacitance to ground of the gas in the tube is to be employed, a so-called "floating ground" approach cannot be employed with the circuit of Figure lO.
The 110 volts AC is rectified by diode Dl and filtered by capacitor C1. Resistors R1 and R2 serve as "fuse" resistors and open up in the event of a catastrophic fault. The rectified voltage across Cl is approximately 160 volts DC. Transistor Ql may be a MJE8501 power tab version and is connected as a Hartly type oscillator where the collector is in series with the primary of transformer Tl and is energized by the rectified DC voltage. A drive signal to the base is obtained by a tertiary feedback winding properly phased to allow oscillation to take place. Base current is limited by resistors R4 and R5 and biased into conduction by resistor R3. The oscillations produced are at a frequency of approximately 20 XHz.
This is generally determined by the resonant frequency of Tl. A
snubbing circuit consisting of C3, R9 and D2 limits the change in voltage with respect to time (i.e. dv/dt) that may occur across Ql along with any extreme peak voltages.
The current of Ql, and hence the circuit output, is controlled via the conductance of pass transistor Q2 by biasin~ its base. In testing embodiments of the applicant, the waveshape at point "A" was a negatively clipped sine wave of 800 volts peak voltage and with a period of 50 microseconds. Resistors R6 and R7 guarantee low level oscillation even when Q2 is in a low or non-conductive state and should be set at 30 to 50 ma of AC line current. Q2 is biased through the "slope" control potentiometer Rl2 by setting its base current. Diode Dh prevents any offset ' ~
.
' ~ - - ` ' :~ , ' : .
~ - , . ,,' : .
,.', 30!31 voltage that may occur before the beginning of the turn-on cycle from turning on Q2. Capacitor C2 bypasses any high frequency signal across Q2.
The output of the circuit is controlled by the ramp voltage occurring at the emitter junction of pin 1 on Q4. This is a ramp function whose period is determined by the setting of R13 and capacitor C4. This charging voltage provides a relatively constant current for capacitor c4 due to its high source potential of 160 volts DC. The actual time is a result of a constant current charge increasing voltage at the emitter of Q4 to a value where breakover occurs. This breakover or discharge happens in a relatively short period of time and is the retrace time of the ramp waveform as indicated in the graph of Figure 3.
This voltage waveform is applied to emitter follower Q3 that is necessary to provide a relatively high impedance to the charging current integrated into C4. This impedance is greater than the beta of Q3 times the parallel combination of Rll and R12. This value remains relatively constant and does not appreciably change the ramp period. A voltage produced across R12 now follows the ramp voltage and turns on Q2 accordingly, providing a relatively linear change in the power output of Ql. Proper biasing of Q2 is to the point of conducting just when the ramp voltage starts to increase. This provides a minimum or zero display at this initial time which steadily increases as the ramp wave builds. R12 now controls the slope of this voltage rise and provides an adjustment for larger or shorter displays. R14 and R_5 are necessary for proper biasing of unijunction Q4 while zener diodes Zl and z2 limit the voltage across Q3 and Q4 to 24 volts DC. The external jack Jl is provided for the attachment of the output signal from an audio amplifier or the like. The periodic waveform of the audio signal from the audio amplifier is demodulated and now controls the current through Q2 and, accordingly the display tube being driven thereby. The modulation is accomplished by varying the emitter bias point of Q1 via the conductance of Q2. The control potentiometer R12 allows presetting the limit of the `
..
79()'~31 ionization energy per volt of input signal.
The plasma arc of the display is Eorm~d by the electrical current flowing through the gas in the tube. The atoms of the gas become energized to a level where electrons and positively charged atoms are produced. These emit light spontaneously upon returning to their initial energy state.
A definite threshold for ioni~ation is required, therefore causing a positive line of demarcation where ignition occurs. As the electrical current is reduced, the display shortens due to insufficient energy to cause further ionization. Increasing ionization energy causes the end of the display to lengthen since conduction can now occur due to more free charges. In simple quantitative terms, the number of charges produced in the tube is directly related to the input energy. A smaller volume tube would theoretically produce a longer discharge for a given ionization energy and vice versa. This, of course, neglects tbe change in dynamic impedance of the system due to a volume change.
In order to achieve a travelling plasma effect or discharge that moves along the display length, it is necessary to periodically control the ionization energy output of the circuit. As was stated above, transistor Q2 controls the output of the oscillator. This is accomplished by controlling its base and, therefore, controlling it conductivity. Proper operation of a system requires ignition just starting to occur and steadily increasing to - the full length of the display being coincidental to the waveform. This requiees a ramp of voltage injected into the base of Q2 steadily increasing to the desired point and thus resetting to repeat again. This produces a writing effect in the display sign eventually resetting to the beginning and then repeating. The circuit of Figure 10 is adapted to produce such a repeating ramp voltage. Capacitor C4 is charged tbrough resistors R13 and R10. R13 is variable to control this charging current and, consequently, the repeat ', 790'~3~
time which, for the handwriting e~fect, should be visually perceptible. ~ince the charging voltage is relatively hi~h, a lineae increase in voltage is produced in the form of a ramp before discharging through the emitter base junction of Q4. This discharge time is short in comparison to the ramp and produces a rapid reset of the display to its initial state. The ramp voltage is fed to Q2 through emitter follower Q3. This combination provides a high impedance allowing a minimal bypassing of the charging current. Zener diodes Zl and Z2 limit the voltage supplied to Q3 and ~4 through resistor R8. A neqative offset to guarantee a zero collector current through Q2 is provided by diode offset Dn biasing its base below conduction.
The above-described circuit is intended to fully ignite a display, periodically repeating it at an adjustable rate and retracing back to the beginning. Those skilled in the art will appreciate and understand the modifications which could be made thereto to accomplish other features as de~cribed hereinbefoee and other possible features not described but within the scope and spirit of the present invention. For example, installing the jumper across Q3 indicated by the dotted line in the circuit diagram o Figure 10, allows one to steady state position the plasma ignition to any point alonq the display tube by means of R12.
B
,; ,
The present invention relates to displays and, more particularly to an illuminated display comprising, an elongated cold cathode gas discharge tube containing an ionizable gas, the tube having a single cathode element at one end in contact with the gas: and, a power source connected to ionize the gas and cause illumination thereof, the power source being connected to the single cathode element and producing alternating voltage referenced to ground potential and of sufficient frequency to cause the gas to ionize through the natural surrounding capacitance between the ionized gas and ground potential.
Cold cathode gas discharge displays are old and well known in the art. The most familiar is the "neon sign"
which has remained virtually unchanged from time immemorial. In neon signs, an elongated glass tube is filled with an ionizable gas, such as neon. The tube has a pair of cathode elements passing through the glass at the ènds of the tube into contact with the gas. The secondary of a high voltage, current limited transformer is connected across the cathode elements. The primary of the transformer is connected via a plug to a standard 110 volt, 60 Hz wall socket, or the like, which results in a 60 Hz, high voltage being applied across the gas by the cathode elements. The high voltage causes the gas to ionize and glow, thus causing the desired illumination. Particularly as the signs get older, the use of high voltage causes buzzing, and the like, which is annoying and disruptive.
Neon signs are typically used in two ways. They can be disposed behind a display panel having indicia thereon and used to illuminate the panel. More commonly, the tubes are formed into the letters, or the like, to convey the desi~ed message. In either case, however, the entire length of the tube must be energized simultaneously. For "movement" of the display, individual tubes comprising the . , , .
.~
'30'31 various segments must be employed with each connected to an individual source of power. Moreover, timing and power control circuits must typically be utilized in this approach.
The present invention seeks to provide a new approach to the manner of operation of gas discharge tubes which provides for ionization of the gas with a single cathode element for low voltage operation, for selective ionization and illumina-tion of portions of the tube, and, for moving illumination of the tube in an illuminated handwriting style.
According to one aspect of the present invention there is provided a cathode gas discharge tube device which includes an elongated cold cathode gas discharge tube containing an ionizable gas, the tube having a cathode element disposed to cause ionization of the gas along a length of the tube forming the display portion thereof. The device further includes a power source connected to ionize the gas and cause illumination thereof, the power source being connected to the cathode element and producing changing voltage reference to ground potential and of sufficient frequency to cause the gas to ionize through only the natural surrounding capacitants along the display portion of the tube between the ionized gas and the ground potential. The power source produces a variable voltage output so that the extent of ionization of the gas, along the tube in a direction away from the cathode element, will vary with and be determined by the voltage output.
Another aspect of the invention resides in a method of causing illumination of an elongat~d cold cathode gas discharge tube containing an ionizable gas and having a cathode element disposed to cause ionization of the gas along the length of a tube forming a display portion thereof. The method includes the step of connecting to the cathode element a power source of a changing voltage reference to ground potential, the power source being a sufficient frequency to cause the gas to ionize through the natural surrounding capacitants along the display portion of the tube between the ., ' .'':- :'' '-.. . .
1i~'79(~
ionized gas and ground potential. The method ~urtherincludes the step of varying the voltage between first and second levels so that the extent of ionization of the gas along the tube in a direction away from the cathode element will vary with and be determined by the voltage.
Description of the Drawinqs-.
Other objects and benefits of the present invention will become apparent fro~ the description contained hereinafter in combination with the illustrative drawing figures.
Figure 1 is a simplified drawing of a prior art gas dis-charge tube display of the "neon sign" variety.
Figure 2 is a simplified drawing showing the manner of operation of the present invention.
Figure 3 is a graph of the voltage ramp applied to the single cathode element in the present invention.
Figures 4a, 4b, 4c, and 4d show the progress of ioniza-tion of the gas in the tube according to a first manner of operating the present invention.
Figures 5a, 5b, 5c, and 5d show the progress of ioniza-tion of the gas in the tube according to a second manner of operating the present invention.
Figures 6a, 6b, 6c, and 6d show the progress of ioniza-tion of the gas in the tube according to the third manner of operating the present invention.
Figure 7 is a block diagram showing how the present invention can be employed to selectively illuminate the display tube according to various possible external func-tions.
Figure 8 is a simplified drawing showing how the present invention can be used to progressively illuminate portions of a display having indicia thereon with only a single tube.
Figure 9 is a simplified graph showing how in the preferred driver circuit of the present invention the frequency of the voltage ramp is decreased as the plasma ,~
1;~'7{3(~'31 being formed increases and correspondingly has more available capacitance to ground to automatically compensate for that phenomenon.
Figure 10 is a circuit diagram of a circuit as employed in a tested embodiment of the present invention.
Description of the Preferred Embodiment:
As explained earlier, cold cathode gas discharge displays are old and well known in the art. The most familiar is the "neon sign" 10 of Figure 1, which has remained virtually unchanged from time immemorial. In neon sign 10, an elongated glass tube 12 is filled with an ionizable gas 14, such as neon. The tube 12 has a pair of cathode elements 16 passing through the glass at the ends of the tube 12 into contact with the gas 14. The secondary of a high voltage, current limited transformer 18 is connected across the cathode elements 16. The primary of the trans-former 18 is connected via plug 20 to a standard 110 volt, 60 Hz wall socket, or the like, which results in a 60 Hz, high voltage being applied across the gas 14 by the cathode elements 16. The high voltage causes the gas 14 to ionize and glow, thus causing the desired illumination. Particular-ly as the signs get older, the use of high voltage causes buzzing, and the like, which is annoying and disruptive.
Neon signs such as 10 are typically used in two ways.
They can be disposed behind a display panel having indicia thereon (not shown) and used to illuminate the panel. More commonly, the tubes 12 are formed into the letters, or the like, to convey the desired message. In either case, however, the entire length of the tube 12 must be energized simultaneously. For "movement" of the display, individual tubes comprising the various segments must be employed with each connected to an individual source of power. Moreover, timing and power control circuits must typically be utilized in this approach.
The method o~ operation upon which the present invention ' ' ' .
1;~'7~
is based requires only a single cathode element at one end of the tube. This is possible because the natural capacitance to ground potential between the ionized gas and its surroundings is employed.
A low voltage, high frequency potential is applied to the single cathode element which, in the presence of a low enough reactive impedance to the high frequency energy, causes plasma ignition of the gas. This property and approach allows much more control over the gas within the tube and its manner of ionization than in prior art displays, as will be described shortly. For example, the ignited plasma can be made to travel along the tube creating a defined bright ionization front. This can be a preprogrammable event where the plasma ignites, travels steadily to the end of the tube, and then repeats the process thus creating a unique hand-writing effect in light. The position of ignition and termination can be automatically or manually controlled. Varying voltage levels such as those from the output of an audio amplifier can also be made to vary the plasma lighting discharge effect. Such possibilities and capabilities, of course, greatly enhance the attention gaining ability of signs and similar displays wherein they are incorporated. As will be seen, the present invention also provides the capability of producing multiple segments without the necessity of employing duplicate components as in prior art.
Turning first to Figures 2 and 3, the principle of operation of the present invention will be described briefly. As in the prior art, a display tube 12 of glass, or the like, containing an ionizable gas 14 is employed. A single cathode element 16 is required at one end. As can be appreciated, old prior art tubes can be employed with the present invention by simply ignoring the ca~hode element 16 at the opposite end. The single cathode element 16 is connected to the output of a power source 22 which produces high frequency, low voltage referenced to ground potential and of sufficient frequency to cause the gas to ionize through the natural surrounding capacitance between the -~
. . , .. ' ` ' , : . ., .~ , .
~ ;~790'~31 ionized gas and ground potential as represented by the capacitors generally indicated as 24. The power source 22 is connected to a conventional 110 volt 60 Hz power outlet or a DC outlet by means of plug 20, the only requirement for the power outlet being that it be polarized with one side referenced to earth ground. As shown in Figure 3, one form of output of the power source may be a high frequency voltage ramp that increases over time so as to move the ionization point along the tube 12 from one end to the other. As in a television tube, the voltage output drops to a "zero" state (i.e. no ionization of the gas 14 taking place) in a very short period indicated in the figure as the "retrace time" and then repeats the pattern of Figure 3.
By varying the initial and final voltage levels of the ramp of Figure 3 which represents the output of the power source 22 applied to the single cathode element 16 of the display tube 12, various display features as depicted in Figures 4-6 can be achieved. As will be appreciated, these features cannot be achieved in the prior art and afford many possibilities for the display of the present invention. For example, in the sequence of Figure 4(a), 4(b), 4(c), and 4(d), the front on the ionization portion 26 is seen to move along the tube as a bright band of illumination fully from one end of the tube to the other; that is, from the end of the single cathode element to the other. In the sequence of Figure 5(a), 5(b), 5(c), and 5(d), the front of the ionization portion 26 moves along the tube from an initial point displaced from the cathode element end of the tube fully to the other end. In the sequence of Figure 6(a), 6(b), 6(c), and 6(d), the ionization portion 26 moves along the tube from an initial point displaced from the cathode element end of the tube to a point short of the other end. As this last example illustrates, the present invention allows a segment of any length of the tube between the ~' .. . . .
~ -- . ' - . .
,, :' -. - . --, - : ' -` . -..
: - ' :- .
~7~3()'31 starting end of the tube and preselected points along the tube to be selectively illuminated. As will be appreciated by those skilled in the art, therefore, by changing the point of illumination termination, the segment of the tube 12 being illuminated can be made to change.
As illustrated in Figure 7, in the preferred embodiment of the present invention, the display driver portion power source 22 of the present invention is made responsive to various external functions as represented by the box 30 connected thereto. Thus, the output of an audio amplifier can be employed to change the voltages of the power source 22 or modulate the frequency thereof so as to create display patterns with the tube 12 which are a function of the audio signal. A function generator can be employed to create particular display patterns and sequences. A transducer can be employed for certain uses. For example, a force transducer could change the position of the illumination of a tube disposed next to a scale so as to create an indicator for force measurement or a scale for weighing. A manual control can be employed for manually setting the position of illumination as, for example, to move the illuminated portion of the tube to selectively light up "VACANCY" or extended to light up '!NO VACANCY" portions of a sign at a business.
A display system according to the present invention which would not have possible in the prior art without elaborate controls sequencing between multiple tubes is shown in Figure 8. A single tube 12 connected to the power source of the present invention (not included in the figure for simplicity) is disposed behind a display panel or sign 32 of translucent material and having indicia 34 thereon conveying a message, such as the message of Figure 8, EAT AT
JOE'S. For larger signs, multiple tubes could be used in parallel. AS shown in Figure 8(a), the initiation and termination point for illumination of the tube(s) 12 is first set in the power source 22 so as to illuminate a first . . ~
'', ~
.~ ~
:
.
,' ~ ' '' .
'~'`, ` ':
- ' . -.
~ ~ ' ' : , .
'. ; ' ~'7~0~31 portion behind the word EAT. After a period of time, the termination point for illumination of the tube(s) 12 is next set in the power source ~2 so as to illuminate the additional portion behind the word AT. After a similar period of time, the termination point for illumination of the tube(s) 12 is set to illuminate the additional portion behind the word JOE'S. The word JOE'S remains illuminated for its period of time and then the process repeats. The result is a visually perceptible sequence of illumination of the in-dividual words EAT -- AT -- JOE'S employing only one tubets) and one power source.
Another feature of the present invention as incorporated into the tested circuitry of the power source to be described shortly is illustrated in the simplified graph of Figure 9. As the plasma in the display tube is ionized the available capacitance to ground increases in proportion to the quantity of gas within the tube which is ionized. To compensate for that natural effect, the preferred embodiment of the present invention correspondingly reduces the frequen-cy of the voltage ramp to adjust for the change in available capacitance and thereby retain linear response to the output of the power source.
A circuit for the power source to drive a display tube according to the present invention as employed in tested embodiments by the applicant is shown in Figure 10. While the construction and operation of the circuit should be apparent to those skilled in the art from an inspection thereof, a brief explanation will now be provided to assure complete understanding. More particularly, the circuit of ', :
.
.
.
1~79091 Figure lo operates as follows.
The plug 20 is plugged into a conventional llo volt, 60 Hz power outlet. Note, however, that plug 20 must be of the polarized variety wherein one side is referenced to actual ground potential as where a rod at the power pole or otherwise is driven into the earth. This is to say, since the capacitance to ground of the gas in the tube is to be employed, a so-called "floating ground" approach cannot be employed with the circuit of Figure lO.
The 110 volts AC is rectified by diode Dl and filtered by capacitor C1. Resistors R1 and R2 serve as "fuse" resistors and open up in the event of a catastrophic fault. The rectified voltage across Cl is approximately 160 volts DC. Transistor Ql may be a MJE8501 power tab version and is connected as a Hartly type oscillator where the collector is in series with the primary of transformer Tl and is energized by the rectified DC voltage. A drive signal to the base is obtained by a tertiary feedback winding properly phased to allow oscillation to take place. Base current is limited by resistors R4 and R5 and biased into conduction by resistor R3. The oscillations produced are at a frequency of approximately 20 XHz.
This is generally determined by the resonant frequency of Tl. A
snubbing circuit consisting of C3, R9 and D2 limits the change in voltage with respect to time (i.e. dv/dt) that may occur across Ql along with any extreme peak voltages.
The current of Ql, and hence the circuit output, is controlled via the conductance of pass transistor Q2 by biasin~ its base. In testing embodiments of the applicant, the waveshape at point "A" was a negatively clipped sine wave of 800 volts peak voltage and with a period of 50 microseconds. Resistors R6 and R7 guarantee low level oscillation even when Q2 is in a low or non-conductive state and should be set at 30 to 50 ma of AC line current. Q2 is biased through the "slope" control potentiometer Rl2 by setting its base current. Diode Dh prevents any offset ' ~
.
' ~ - - ` ' :~ , ' : .
~ - , . ,,' : .
,.', 30!31 voltage that may occur before the beginning of the turn-on cycle from turning on Q2. Capacitor C2 bypasses any high frequency signal across Q2.
The output of the circuit is controlled by the ramp voltage occurring at the emitter junction of pin 1 on Q4. This is a ramp function whose period is determined by the setting of R13 and capacitor C4. This charging voltage provides a relatively constant current for capacitor c4 due to its high source potential of 160 volts DC. The actual time is a result of a constant current charge increasing voltage at the emitter of Q4 to a value where breakover occurs. This breakover or discharge happens in a relatively short period of time and is the retrace time of the ramp waveform as indicated in the graph of Figure 3.
This voltage waveform is applied to emitter follower Q3 that is necessary to provide a relatively high impedance to the charging current integrated into C4. This impedance is greater than the beta of Q3 times the parallel combination of Rll and R12. This value remains relatively constant and does not appreciably change the ramp period. A voltage produced across R12 now follows the ramp voltage and turns on Q2 accordingly, providing a relatively linear change in the power output of Ql. Proper biasing of Q2 is to the point of conducting just when the ramp voltage starts to increase. This provides a minimum or zero display at this initial time which steadily increases as the ramp wave builds. R12 now controls the slope of this voltage rise and provides an adjustment for larger or shorter displays. R14 and R_5 are necessary for proper biasing of unijunction Q4 while zener diodes Zl and z2 limit the voltage across Q3 and Q4 to 24 volts DC. The external jack Jl is provided for the attachment of the output signal from an audio amplifier or the like. The periodic waveform of the audio signal from the audio amplifier is demodulated and now controls the current through Q2 and, accordingly the display tube being driven thereby. The modulation is accomplished by varying the emitter bias point of Q1 via the conductance of Q2. The control potentiometer R12 allows presetting the limit of the `
..
79()'~31 ionization energy per volt of input signal.
The plasma arc of the display is Eorm~d by the electrical current flowing through the gas in the tube. The atoms of the gas become energized to a level where electrons and positively charged atoms are produced. These emit light spontaneously upon returning to their initial energy state.
A definite threshold for ioni~ation is required, therefore causing a positive line of demarcation where ignition occurs. As the electrical current is reduced, the display shortens due to insufficient energy to cause further ionization. Increasing ionization energy causes the end of the display to lengthen since conduction can now occur due to more free charges. In simple quantitative terms, the number of charges produced in the tube is directly related to the input energy. A smaller volume tube would theoretically produce a longer discharge for a given ionization energy and vice versa. This, of course, neglects tbe change in dynamic impedance of the system due to a volume change.
In order to achieve a travelling plasma effect or discharge that moves along the display length, it is necessary to periodically control the ionization energy output of the circuit. As was stated above, transistor Q2 controls the output of the oscillator. This is accomplished by controlling its base and, therefore, controlling it conductivity. Proper operation of a system requires ignition just starting to occur and steadily increasing to - the full length of the display being coincidental to the waveform. This requiees a ramp of voltage injected into the base of Q2 steadily increasing to the desired point and thus resetting to repeat again. This produces a writing effect in the display sign eventually resetting to the beginning and then repeating. The circuit of Figure 10 is adapted to produce such a repeating ramp voltage. Capacitor C4 is charged tbrough resistors R13 and R10. R13 is variable to control this charging current and, consequently, the repeat ', 790'~3~
time which, for the handwriting e~fect, should be visually perceptible. ~ince the charging voltage is relatively hi~h, a lineae increase in voltage is produced in the form of a ramp before discharging through the emitter base junction of Q4. This discharge time is short in comparison to the ramp and produces a rapid reset of the display to its initial state. The ramp voltage is fed to Q2 through emitter follower Q3. This combination provides a high impedance allowing a minimal bypassing of the charging current. Zener diodes Zl and Z2 limit the voltage supplied to Q3 and ~4 through resistor R8. A neqative offset to guarantee a zero collector current through Q2 is provided by diode offset Dn biasing its base below conduction.
The above-described circuit is intended to fully ignite a display, periodically repeating it at an adjustable rate and retracing back to the beginning. Those skilled in the art will appreciate and understand the modifications which could be made thereto to accomplish other features as de~cribed hereinbefoee and other possible features not described but within the scope and spirit of the present invention. For example, installing the jumper across Q3 indicated by the dotted line in the circuit diagram o Figure 10, allows one to steady state position the plasma ignition to any point alonq the display tube by means of R12.
B
,; ,
Claims (32)
1. A cathode gas discharge tube device comprising:
a) an elongated cathode gas discharge tube containing an ionizable gas, said tube having a cathode element disposed to cause ionization of the gas along a length of said tube forming the display portion thereof; and, b) a power source connected to ionize the gas and cause illumination thereof, said power source being connected to said cathode element and producing changing voltage referenced to ground potential and of sufficient frequency to cause the gas to ionize through only the natural surrounding capacitance along said display portion of said tube between the ionized gas and ground potential; and, c) the power source producing a variable voltage output whereby the extent of ionization of the gas, along the tube in a direction away from said cathode element, will vary with and be determined by the voltage output.
a) an elongated cathode gas discharge tube containing an ionizable gas, said tube having a cathode element disposed to cause ionization of the gas along a length of said tube forming the display portion thereof; and, b) a power source connected to ionize the gas and cause illumination thereof, said power source being connected to said cathode element and producing changing voltage referenced to ground potential and of sufficient frequency to cause the gas to ionize through only the natural surrounding capacitance along said display portion of said tube between the ionized gas and ground potential; and, c) the power source producing a variable voltage output whereby the extent of ionization of the gas, along the tube in a direction away from said cathode element, will vary with and be determined by the voltage output.
2. The device of claim 1 wherein:
said voltage output is a voltage ramp.
said voltage output is a voltage ramp.
3. The device of claim 1 wherein:
said voltage magnitude starts at a level to cause initial ionization of the gas adjacent said cathode element.
said voltage magnitude starts at a level to cause initial ionization of the gas adjacent said cathode element.
4. The device of claim 1 wherein:
said voltage magnitude rises to a level to cause final ionization of the gas adjacent the end of the tube opposite said cathode element.
said voltage magnitude rises to a level to cause final ionization of the gas adjacent the end of the tube opposite said cathode element.
5. The device of claim 2 wherein:
a) said voltage ramp starts at a level to cause initial ionization of the gas adjacent said cathode element;
and, b) said voltage ramp rises to a level to cause final ionization of the gas adjacent the end of the tube opposite said cathode element and rises at a rate to produce a visible progression of illumination from one end of the tube to the other whereby an illuminated handwriting effect is created by the progressive illumination of the tube.
a) said voltage ramp starts at a level to cause initial ionization of the gas adjacent said cathode element;
and, b) said voltage ramp rises to a level to cause final ionization of the gas adjacent the end of the tube opposite said cathode element and rises at a rate to produce a visible progression of illumination from one end of the tube to the other whereby an illuminated handwriting effect is created by the progressive illumination of the tube.
6. The device of claim 2 wherein:
a) said voltage ramp starts at a level to cause initial ionization of the gas to a first selected point along the tube;
and, b) said voltage ramp rises to a level to cause final ionization of the gas to a second selected point whereby only a selected portion of the tube between said cathode element and the first or second selected point is illuminated.
a) said voltage ramp starts at a level to cause initial ionization of the gas to a first selected point along the tube;
and, b) said voltage ramp rises to a level to cause final ionization of the gas to a second selected point whereby only a selected portion of the tube between said cathode element and the first or second selected point is illuminated.
7. The device of claim 2 wherein:
said power source includes means for setting beginning and ending voltages of said voltage ramp so that illumination of a selected illuminated portion of the tube is adjustable.
said power source includes means for setting beginning and ending voltages of said voltage ramp so that illumination of a selected illuminated portion of the tube is adjustable.
8. The device of claim 7 wherein:
said voltage setting means is a manually adjustable means for setting the position of said selected illuminated portion of the tube.
said voltage setting means is a manually adjustable means for setting the position of said selected illuminated portion of the tube.
9. The device of claim 7 wherein:
said voltage setting means is connected to an audio source and adjusts said beginning and ending voltages as a function of a demodulated audio signal from said audio source whereby the position of said selected illuminated portion of the tube varies as a function of said audio signal.
said voltage setting means is connected to an audio source and adjusts said beginning and ending voltages as a function of a demodulated audio signal from said audio source whereby the position of said selected illuminated portion of the tube varies as a function of said audio signal.
10. The device of claim 2 wherein:
said power source includes means connected to an audio source for modulating the level of said voltage ramp as a function of an audio signal from said audio source so that a selected illuminated portion of the tube varies as a function of said audio signal.
said power source includes means connected to an audio source for modulating the level of said voltage ramp as a function of an audio signal from said audio source so that a selected illuminated portion of the tube varies as a function of said audio signal.
11. The device of claim 2 wherein:
said power source includes means for reducing the frequency of said voltage ramp as more gas is ionized to offset the effect of an increased available natural capacitance to ground associated with the increased quantity of ionized gas.
said power source includes means for reducing the frequency of said voltage ramp as more gas is ionized to offset the effect of an increased available natural capacitance to ground associated with the increased quantity of ionized gas.
12. The device of claim 2 wherein:
said power source includes means for varying the frequency of oscillation as a function of the natural capacitance to ground of the gas whereby to automatically compensate for variations in said capacitance as more or less gas is ionized,
said power source includes means for varying the frequency of oscillation as a function of the natural capacitance to ground of the gas whereby to automatically compensate for variations in said capacitance as more or less gas is ionized,
13. The device of claim 2 wherein:
said power source includes means for repeatably producing said voltage ramp so as to ionize the gas in the tube repeatedly in a strobing manner.
said power source includes means for repeatably producing said voltage ramp so as to ionize the gas in the tube repeatedly in a strobing manner.
14. The device of claim 13 wherein:
said power source includes means for adjusting the repetition rate of said voltage ramp.
said power source includes means for adjusting the repetition rate of said voltage ramp.
15. The device of claim 6 and additionally comprising:
a) a display panel containing indicia thereon disposed to be illuminated by said tube; and, b) means for repeatably changing said first and second points to cause said display panel to be cyclically illuminated by portions disposed over said tube between said changing first and second points.
a) a display panel containing indicia thereon disposed to be illuminated by said tube; and, b) means for repeatably changing said first and second points to cause said display panel to be cyclically illuminated by portions disposed over said tube between said changing first and second points.
16. The device of claim 15 wherein:
said means for repeatably changing said first and second points includes means for changing said points at a rate to produce a visibly perceptible stepping between said portions of said display panel being illuminated.
said means for repeatably changing said first and second points includes means for changing said points at a rate to produce a visibly perceptible stepping between said portions of said display panel being illuminated.
17. The device of claim 1, 2 or 3, wherein:
said frequency is in the order of 20 KHz
said frequency is in the order of 20 KHz
18. The improved method of causing illumination of an elongated cold cathode gas discharge tube containing an ionizable gas and having a cathode element disposed to cause ionization of the gas along a length of said tube forming a display portion thereof, comprising the steps of:
a) connecting to said cathode element a power source of an changing voltage referenced to ground potential, said power source being of sufficient frequency to cause the gas to ionize through the natural surrounding capacitance along said display portion of said tube between the ionized gas and ground potential; and b) varying the voltage between first and second levels whereby the extent of ionization of the gas along the tube in a direction away from the cathode element will vary with and be determined by the voltage.
a) connecting to said cathode element a power source of an changing voltage referenced to ground potential, said power source being of sufficient frequency to cause the gas to ionize through the natural surrounding capacitance along said display portion of said tube between the ionized gas and ground potential; and b) varying the voltage between first and second levels whereby the extent of ionization of the gas along the tube in a direction away from the cathode element will vary with and be determined by the voltage.
19. The method of claim 18 wherein said steps include using a voltage ramp for varying the voltage.
20. The method of claim 19 wherein said steps include:
starting the voltage ramp at a level to cause initial ionization of the gas adjacent the cathode element.
starting the voltage ramp at a level to cause initial ionization of the gas adjacent the cathode element.
21. The method of claim 19 wherein said steps include:
raising the voltage ramp to a level sufficient to cause final ionization of the gas adjacent the end of the tube opposite the cathode element.
raising the voltage ramp to a level sufficient to cause final ionization of the gas adjacent the end of the tube opposite the cathode element.
22. The method of claim 19 wherein said steps include:
a) starting the voltage ramp at a level to cause initial ionization of the gas adjacent the cathode element;
and, b) raising the voltage ramp to a level sufficient to cause final ionization of the gas adjacent the end of the tube opposite the cathode element and at a rate to produce a visible progression of illumination from one end of the tube to the other whereby an illuminated handwriting effect is created by the progressive illumination of the tube.
a) starting the voltage ramp at a level to cause initial ionization of the gas adjacent the cathode element;
and, b) raising the voltage ramp to a level sufficient to cause final ionization of the gas adjacent the end of the tube opposite the cathode element and at a rate to produce a visible progression of illumination from one end of the tube to the other whereby an illuminated handwriting effect is created by the progressive illumination of the tube.
23. The method of claim 19 wherein said steps include:
a) starting the voltage ramp at a level to cause initial ionization of the gas to a first selected point along the tube; and, b) raising the voltage ramp to a level to cause final ionization of the gas to a second selected point along the tube displaced from the first selected point of initial ionization whereby only a selected portion of the tube between said cathode element and the first or second selected point is illuminated.
a) starting the voltage ramp at a level to cause initial ionization of the gas to a first selected point along the tube; and, b) raising the voltage ramp to a level to cause final ionization of the gas to a second selected point along the tube displaced from the first selected point of initial ionization whereby only a selected portion of the tube between said cathode element and the first or second selected point is illuminated.
24. The method of claim 18 wherein said steps include:
varying the voltage as a function of an audio signal whereby the extent of illumination of the tube varies as a function of the audio signal.
varying the voltage as a function of an audio signal whereby the extent of illumination of the tube varies as a function of the audio signal.
25. The method of claim 19 wherein said steps include:
modulating the level of the voltage ramp as a function of an audio signal so that the illuminated portion of the tube varies as a function of the audio signal.
modulating the level of the voltage ramp as a function of an audio signal so that the illuminated portion of the tube varies as a function of the audio signal.
26. The method of claim 19 wherein said steps include:
reducing the frequency of the voltage ramp as more gas is ionized to offset the effect of an increased available natural capacitance to ground associated with the increased quantity of ionized gas.
reducing the frequency of the voltage ramp as more gas is ionized to offset the effect of an increased available natural capacitance to ground associated with the increased quantity of ionized gas.
27. The method of claim 19 wherein said steps include:
adjusting the frequency of the voltage ramp as a function of the natural capacitance to ground of the gas whereby to automatically compensate for variations in the capacitance to ground as more or less gas is ionized.
adjusting the frequency of the voltage ramp as a function of the natural capacitance to ground of the gas whereby to automatically compensate for variations in the capacitance to ground as more or less gas is ionized.
28. The method of claim 19 wherein said steps include:
repeatedly producing the voltage ramp so as to ionize the gas in the tube in a strobing manner.
repeatedly producing the voltage ramp so as to ionize the gas in the tube in a strobing manner.
29. The method of claim 28 wherein said steps include:
adjusting the repetition rate of the voltage ramp.
adjusting the repetition rate of the voltage ramp.
30. The method of claim 23 and additionally including the steps of:
a) disposing a display panel containing indicia thereon to be illuminated by the tube; and, b) repeatably changing the first and second points to cause the display panel to be cyclically illuminated in portions disposed over the tube between the changing first and second points.
a) disposing a display panel containing indicia thereon to be illuminated by the tube; and, b) repeatably changing the first and second points to cause the display panel to be cyclically illuminated in portions disposed over the tube between the changing first and second points.
31. The method of claim 30 wherein said steps include:
repeatably changing the first and second points at a rate to produce a visibly perceptible stepping between the portions of the display panel being illuminated.
repeatably changing the first and second points at a rate to produce a visibly perceptible stepping between the portions of the display panel being illuminated.
32. The method of claim 18, 19 or 20, wherein:
said frequency is in the order of 20 KHz.
said frequency is in the order of 20 KHz.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US057,617 | 1987-06-03 | ||
| US07057617 US4742278B1 (en) | 1987-06-03 | 1987-06-03 | Single connection gas discharge display and driver |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1279091C true CA1279091C (en) | 1991-01-15 |
Family
ID=22011717
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000562986A Expired - Lifetime CA1279091C (en) | 1987-06-03 | 1988-03-30 | Single connection gas discharge display and driver |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US4742278B1 (en) |
| CA (1) | CA1279091C (en) |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5126632A (en) * | 1988-05-10 | 1992-06-30 | Parker William P | Luminous panel display device |
| US4956577A (en) * | 1988-05-10 | 1990-09-11 | Parker William P | Interactive luminous panel display device |
| US5198723A (en) * | 1988-05-10 | 1993-03-30 | Parker William P | Luminous panel display device |
| US5089745A (en) * | 1988-11-30 | 1992-02-18 | Bertonee Inc. | Amusement device incorporating gas discharge tube |
| GR890100753A (en) * | 1989-11-14 | 1992-04-17 | William P Parker | Presentation arrangement |
| US5041767A (en) * | 1990-03-30 | 1991-08-20 | Bertonee Inc. | Digital controller for gas discharge tube |
| US5386181A (en) * | 1992-01-24 | 1995-01-31 | Neon Dynamics Corporation | Swept frequency switching excitation supply for gas discharge tubes |
| US5383295A (en) * | 1992-12-21 | 1995-01-24 | Strattman; Wayne P. | Luminous display device |
| US5453668A (en) * | 1994-03-23 | 1995-09-26 | Chow; Shing C. | Method and circuitry for producing dynamic illumination of discharge lamp |
| CA2267366C (en) * | 1997-07-22 | 2006-01-10 | Eugen Statnic | Process for generating voltage pulse sequences and circuit assembly therefor |
| US6512331B1 (en) * | 2000-11-09 | 2003-01-28 | Hing Hung Ricky Fu | Luminous display and method of making same |
| US6597128B2 (en) * | 2001-10-03 | 2003-07-22 | Hubbell Incorporated | Remote discharge lamp ignition circuitry |
| US9647162B2 (en) | 2011-01-20 | 2017-05-09 | Colossus EPC Inc. | Electronic power cell memory back-up battery |
| US20120187763A1 (en) | 2011-01-25 | 2012-07-26 | Isoline Component Company, Llc | Electronic power supply |
| US9379777B2 (en) * | 2012-05-07 | 2016-06-28 | Nokia Technologies Oy | Near field communication circuitry used for hearing aid compatibility |
| US10730343B2 (en) | 2016-12-01 | 2020-08-04 | John P. MACHUCA | Vehicle rim plasma display assembly, apparatus and insert |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1819105A (en) * | 1927-07-09 | 1931-08-18 | Rainbow Light Inc | High frequency luminous tube |
| US1854912A (en) * | 1930-01-18 | 1932-04-19 | Ne Arga Corp | Lamp starting device |
| US2629839A (en) * | 1948-05-10 | 1953-02-24 | William B Greenlee | Capacitive lighting system |
| US3085189A (en) * | 1951-08-10 | 1963-04-09 | Thonemann Peter Clive | Energy-transfer systems |
| US2984765A (en) * | 1956-11-28 | 1961-05-16 | Digital Tech Inc | Electric controlled informationbearing device |
| US4245178A (en) * | 1979-02-21 | 1981-01-13 | Westinghouse Electric Corp. | High-frequency electrodeless discharge device energized by compact RF oscillator operating in class E mode |
-
1987
- 1987-06-03 US US07057617 patent/US4742278B1/en not_active Expired - Lifetime
-
1988
- 1988-03-30 CA CA000562986A patent/CA1279091C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| US4742278B1 (en) | 1996-11-05 |
| US4742278A (en) | 1988-05-03 |
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