|Publication number||WO1991017634 A1|
|Publication date||14 Nov 1991|
|Filing date||2 May 1991|
|Priority date||4 May 1990|
|Publication number||PCT/1991/3019, PCT/US/1991/003019, PCT/US/1991/03019, PCT/US/91/003019, PCT/US/91/03019, PCT/US1991/003019, PCT/US1991/03019, PCT/US1991003019, PCT/US199103019, PCT/US91/003019, PCT/US91/03019, PCT/US91003019, PCT/US9103019, WO 1991/017634 A1, WO 1991017634 A1, WO 1991017634A1, WO 9117634 A1, WO 9117634A1, WO-A1-1991017634, WO-A1-9117634, WO1991/017634A1, WO1991017634 A1, WO1991017634A1, WO9117634 A1, WO9117634A1|
|Inventors||Seabourn Livingstone, Robert S. Patti, Michael K. Pedigo|
|Applicant||Seabourn Livingstone, Patti Robert S, Pedigo Michael K|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (8), Referenced by (3), Classifications (5), Legal Events (3)|
|External Links: Patentscope, Espacenet|
Title: TRANSMITTER/RECEIVER SYSTEM FOR LOCATING MISPLACED OBJECTS
This invention relates to a transmitter/receiver system for locating a misplaced object such as eyeglasses.
Background and Summary of the Invention
Devices for locating misplaced objects are known, and commonly include a transmitter which emits a first tone which is responded to by a receiver on the object. The receiver unit commonly includes a tone generator which emits a second tone. The second tone attracts the attention of the user who then follows the tone to locate the object.
An object of the instant invention is to provide a receiver unit, for use in a system of the subject character, which conserves power by means of an electronic oscillator which functions as an electronic switch, intermittently applying power to the receiver unit; and which has a miniaturized receiver which is able to be attached conveniently to the frame of eyeglasses.
The advantages are that power is conserved at the receiver so that the battery which powers the receiver unit has an extended life; and the receiver unit may be very small with no moving parts as would be required in a mechanical switch. Brief Description of the Drawings
Fig. 1 is a block diagram of a transmitter unit. Fig. 2 is a block diagram of a receiver unit. Fig.3 is a schematic of the transmitter of Fig.1. Fig. 4 is a schematic of the receiver unit of
Fig.5a shows a perspective view of a transmitter unit in a flashlight.
Fig. 5b shows a perspective view of a receiver unit in the eyeglasses frame.
Detailed Description of the Preferred Embodiments
Referring to Figs. 1 and 3, there is shown a transmitter unit 10 which includes RF oscillator 12 and audio oscillator 14 which generate a signal at a first audio frequency. A modulator 16 combines the signals from oscillators 12, 14 to form an amplitude modulated RF signal that is fed to a first antenna 18. A first battery 20 energizes RF oscillator 12, audio oscillator 14 and modulator 16. Preferably, transmitter unit 10 is disposed between the light 22 and the battery 20 of a flashlight 26, as shown in Fig. 5. Transmitter unit 10 is thus energized by battery 20 when switch 28 of flashlight 26 is closed.
Receiver unit 30 (Figs. 2, 4 and 5) is disposed on a substrate 32 which is adapted to be attached to or disposed in an object such as eyeglasses frames 34. The receiver unit 30 has a second antenna 36 responsive to the RF carrier frequency, and a detector 38 coupled to second antenna 36. An electronic switch 40 is coupled to detector 38 through a filter 41. Switch 40 changes state, that is, changes between an on and an off status, upon detection of the modulation frequency at detector 38. A signal device 42, coupled to the electronic switch 40, is responsive to the change of state, and is energized by an alarm oscillator 43 when such change occurs. Signal device 42 attracts the attention of the user and may be audible or visual. Preferably, signal device 42 is an audio buzzer, and an audible signal is generated at about 3 khz.
Receiver unit 30 has a second battery 44 and a voltage regulator 45 which energizes detector 38, electronic switch 40, signal device 42 and alarm oscillator 43. Preferably, the RF portion of receiver unit 30 - i.e., detector 38, switch 40 and filter 41, - has an input power bus 47 operated by a low frequency oscillator 46 which intermittently applies power to the receiver unit 30. Preferably, low frequency oscillator 46 has a period in the range of one to one and one half seconds, and a duty cycle of about 2 to 3 percent. Low frequency oscillator 46 is an electronic oscillator which acts as a switch. The output waveform 46a of oscillator 46 is of a sawtooth configuration, as shown in Fig. 4. That is, the leading edge 46b of each pulse is sloped, so as to apply power gradually to the remainder of the receiver circuitry. On the other hand, the trailing edge 46c of each pulse is abrupt or steep, for quickly removing power from the circuit. The gradual power application provided by edges 46b prevent generation of noise and spikes in the detector circuitry, which could have an amplitude greater than the amplitude of the signal being detected at detector 38. The leading edges 46b generate a small spectrum of harmonics ringing in the receiver, and prevent false triggering of audio buzzer 42. Thus, the slow power-up prevents circuit instabilities and also has a very small spectrum of harmonics generated by the rising edge slope.
As shown in Fig. 4, switch 40 comprises a transistor 50 having a base connected to filters 41 and emitters connected to ground, and a collector connected to the enable input of oscillator 43. A capacitor 51 is connected across the collector and emitters of transistor 50, and a resistor 52 connects the collector of transistor 50 to the output of voltage regulator 45. Resistor 52 has high resistance, such as one megohm, and capacitor 51 has high capacitance, such as 0.33 microfarad. Thus, capacitor 51 is charged relatively slowly through resistor 52. When transistor 50 turns on, upon detection of the modulating signal at filter 41, capacitor 51 rapidly discharges, and the enable input of oscillator 43 is brought low. Oscillator operation is thereby enabled. When power is thereafter removed from detector 36 and filters 41, transistor switch 50 opens, and capacitor 51 begins to charge. However, the charge time of capacitor 51 through resistor 52 is such that oscillator 43 will continue operation - i.e., not be disabled - before oscillator 46 again applies power to bus 47. Thus capacitor 51 and resistor 52 are selected so that capacitor 51 does not interfere with the oscillation of alarm oscillator 43 during the time the modulating signal is being received. In accordance with another feature of the invention, the buzzer 42 is energized as a function of distance from the transmitter to the receiver. That is, when the transmitter is relatively far from the receiver, the amplitude of the modulating signal at detector 38 and filter 41 is relatively weak. Capacitor 51 does not fully discharge when transistor so is turned on. Capacitor 51 has an opportunity to charge fully before the next pulse of waveform 46a. Oscillator 43 is therefore intermittently enabled, and buzzer 42 is intermittently energized. On the other hand, when the transmitter is close to the receiver, and the detected audio modulating signal is strong, capacitor 51 is fully discharged upon occurrence of each pulse in waveform 46a, and does not fully discharge between pulses. Buzzer 42 is thusly continuously energized.
In the preferred embodiment the instant invention comprising elements set forth immediately below, is used to locate misplaced eyeglasses 34. The invention comprises a transmitter unit 10 which generates a first signal in the range of 2 to 3 khz. Transmitter unit 10 is disposed between a light 22 and a battery 20 in a flashlight 26. The transmitter unit 10 is energized when the switch 28 of the flashlight 26 is closed.
A receiver unit 30 is made small enough so as to be able to be disposed on a substrate 32 with an area of about .5 to 1.5 square inches (about 3 square centimeters to about 10 square centimeters), and preferably with an area of less than one square inch (about 6.5 square centimeters). The receiver unit 30 is attached to eyeglasses frame 34 or disposed in a recess 60 of eyeglasses frame 34 and has a second antenna 36 responsive to the RF signal, a detector 38 coupled to said second antenna 36, an electronic switch 40 coupled to the detector 38 which changes state between an on status and an off status, and signal device 42 which emits an audible tone which is about 3 khz. Therefore, in the preferred embodiment, the 3 khz tone is emitted from the eyeglasses 34 when the change occurs, thereby attracting the attention of a user. The receiver unit 30 has a second battery 44, voltage regulator 45 and a low frequency oscillator 46 which is continuously oscillating to intermittently power the receiver unit 30. The low frequency oscillator 46 has a period in the range of one to one and one half seconds and a duty cycle of about 2 to 3 percent.
Obviously, many modifications and variations of the present invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|JPH01141498A *||Title not available|
|JPH01183298A *||Title not available|
|JPS63172985A *||Title not available|
|JPS63314994A *||Title not available|
|US4101873 *||26 Jan 1976||18 Jul 1978||Benjamin Ernest Anderson||Device to locate commonly misplaced objects|
|US4476469 *||13 Nov 1981||9 Oct 1984||Lander David R||Means for assisting in locating an object|
|US4507653 *||28 Jun 1984||26 Mar 1985||Bayer Edward B||Electronic sound detecting unit for locating missing articles|
|US4523332 *||11 Apr 1983||11 Jun 1985||Nec Corporation||Battery saver circuit for use with paging receiver|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US5506717 *||28 Feb 1994||9 Apr 1996||Goldstar Co., Ltd.||Apparatus for locating a remote control transmitter|
|US5945918 *||21 Dec 1994||31 Aug 1999||Mark G. McGonigal||Apparatus and method for locating a remote control unit|
|US5952918 *||20 Nov 1997||14 Sep 1999||Ohayon; Shalom||Recovery mode feature for remote units|
|Cooperative Classification||G08B21/24, G08B21/023|
|European Classification||G08B21/02A7, G08B21/24|
|14 Nov 1991||AK||Designated states|
Kind code of ref document: A1
Designated state(s): CA JP US
|14 Nov 1991||AL||Designated countries for regional patents|
Kind code of ref document: A1
Designated state(s): AT BE CH DE DK ES FR GB GR IT LU NL SE
|4 Jan 1994||NENP||Non-entry into the national phase in:|
Ref country code: CA