|Publication number||US1996492 A|
|Publication date||2 Apr 1935|
|Filing date||5 Jan 1932|
|Priority date||6 Jan 1931|
|Publication number||US 1996492 A, US 1996492A, US-A-1996492, US1996492 A, US1996492A|
|Original Assignee||Telefunken Gmbh|
|Export Citation||BiBTeX, EndNote, RefMan|
|Referenced by (6), Classifications (12)|
|External Links: USPTO, USPTO Assignment, Espacenet|
April 93 F. scHRO ER j 1,996,492
TELEVISION APPARATUS Filed Jan. 5, 1932 RECEIVER AMPLIFIER RECEIVER AMPLIFIER INVENTQR FRITZ SCHROT R- ATfNEY constructed at the receiving point Patented Apr. 2, 1935' PATENT OFFICE TELEVISION Fritz Schriiter, Berlin, Telefunken Gesellsch APPARATUS Germany, assignor to aft fiir Drahtlose Telegraphic in. b. H., Berlin, Germany, a corporation of Germany Application January 5,
1932, Serial No. 584,788
In Germany January 6, 1931 1 Claim.
The present invention relates to television receiving apparatus and is directed principally to a method and means by which the effective intensity and brilliance of the electro-optical image may be increased.
It is known in the prior art that the picture screen of a televisor receiver may be provided with a phosphorescent substance for the purpose of converting or shifting the blue, violet and ultraviolet constituents of light radiation, which, while abundant in energy, are not very conspicucus in visual respect, into a physiologically brighter or more luminous spectral range, and further of insuring a lower blending or coalescence frequency caused by the after-glow of the phosphorus. As will be seen upon closer examination, this latter aim is usually unattained in any system of the prior art, for when choosing a sort of phosphorus whose after-glow period covers a period being longer than the building-up period of an individual television picture, blurred contours are produced in the reproduction of animated pictures. Whenever a rapidly decaying phosphorus is used no decrease in the physiologic flicker efiect may be expected because of the impairment of the cinematographic sector relation.
The principal purpose and object of the present invention thus is to utilize effectively the properties of phosphorus for securing a reduction in flicker by the aid of a suitable process.
With this end in view there is used the prop erty of most grades or kinds of phosphorus first to store up energy by the action of primary irradiation or illumination, and then, subsequent ly, such stored-up energy may be released or given off by irradiation through the use of invisible rays. These invisible rays are principally infra-red rays which act in a practically instantaneous manner in the shape of luminous emission, that is, the extinction so-called of phosphorus.
The invention will be understood best by referring to the accompanying drawing which forms a part of this disclosure. In the drawing, Fig, 1 shows one form of the invention using a mirror-wheel as a scanning element; and Fig. 2 shows a modified form wherein a cathode ray image re-creating system is utilized.
To refer now to the form of the invention as set forth by the mirror-wheel type of televisor of Fig. 1, it is seen that the light issuing from a luminous source I of constant intensity is focused by means of a condenser lens system 2 upon a Kerr cell and associated polarizing and analyzing Nicol prisms 3. The Kerr cell electrodes connect with the signal receiver sothat the light from source I is modulated in the cell in accordance with the incoming picture impulses or signals and then is projected by the aid of an objective lens system 4 and a rotary mirror-wheel 5, or equivalent scanning ture re-creation screen 6 upon which it is spread in a surface by virtue of the rotation of the mirror-wheel or scanning element.
The picture projection screen 6 is coated with phosphorous of a sort having the capability of accumulating luminous energy when irradiatphorus of the said sort may be mentioned zinc sulfide comprising a heavy metal.
According to the present invention, after a suitable length of time, preferably after a period equalling in time that required to re-build half a picture a more or less suddenly occurring extinction of the picture points scanned or swept by the light rays re-creating the electro-optical picture by invisible radiation is produced, for instance, infra-red rays. For this purpose another mirror-wheel l is mounted upon the same spindle as the mirror-wheel 5, the former presenting a phase shifting angle 180 degrees with reference to the latter. The supplementary mirror-wheel 1 causes a ray of infra-red radiation issuing from a suitable radiation source 8 which is focused by an the mirror-wheel 1 to scan the picture projection screen 6. In front of the radiation source 8, if desired, a suitable filter l0 could be mounted in the manner indicated.
What is evidently attained by an arrangement of the kind hereinbefore disclosed is that each picture point or unit during each rotation of the mirror-wheel is rendered active twice or, in other words, the number of picture changes required to prevent the impression of a flicker is diminished or, to be more precise, about halved.
In case it should be found that in the selection of a definite kind of phosphorus the extinction period inherent in the sweeping over the surface of the infra-red spot is too short, this condition may be remedied either by choosing the extinctive infra-red spot substantially larger than the picture re-creating visible spot or else by using a more or less wide infra-red light line or stripe for the purpose of extinction. The infra-red light line trails behind the motion of the picture re-creating luminous spot over the picelement, upon the pic- 9 objective 9 upon ture projection screen as above described. The width of this line, if required, may cover several picture lines.
From what has been above described, it will be seen that the requirements to be made of the precision and the optical qualities of the auxiliary mirror-wheel are very small indeed, so that a relatively crude and cheap form of construction will suffice.
The principle here described by the aid of a mirror-wheel television receiver may be readily applied also to picture scanning devices of different types such as has been suggested by the form of the invention shown by Fig. 2. This embodiment is predicated upon the use of a Braun or cathode ray tube acting as the television receiver element, and the assumption has here been made that the infra-red extinction is insured, as above indicated, by the aid of a line or stripe of infra-red radiation.
Similarly to the construction shown by Fig. 1, the cathode ray or Braun tube l2 may be connected with the receiver so that incoming signals control the ray intensity as shown, for example, by U. S. Patent #1,470,696 through the use of grid control. The cathode ray I5 is suitably deflected by electrostatic or electro-magnetic fields l3 and I4 so as to cause the image points to be traced on the fluorescent end wall l5 of the tube l2.
After the electro-optical image has been formed on the end wall l5 of the tube I2, the infra rays from a source I1 may be caused to sweep over the picture screen by the agency of a tilting or oscillating mirror l8 in a way readily understood from the drawing.
Care must be taken so that the motion of the tilting mirror l8 will be in synchronism with the period of the electron-ray motion inside the Braun tube l2. This is accomplishable in a particularly simple manner if the deflector potenaccesses tials acting upon the cathode ray pencil are obtained from a tone-frequency generator equipped with rotating members as has been disclosed in U. S. patent application of August Karolus, 8erial No. 545,965, flled June 22, 1931. The motion of the tilting mirror need then to be made dependent only upon the speed of rotation of the generator. It will be understood that in lieu of the said oscillatory mirror recourse may be had also to other similarly operating means for the deflection of the radiations, such as a tilting prism or a mirror-studded drum.
Many modifications will suggest themselves and become apparent to those skilled in the art to which the invention relates and it is. therefore, intended that the following claim shall be construed in the broad and generic sense to cover all such forms of the invention as would suggest themselves.
Having now described my invention, what I claim and desire to secure by Letters Patent is the following:
In a television system, a cathode ray tube provided at one end with a phosphorescent screen, means for receiving signals representative 0! fluctuating light intensities on successive elemental areas of a record surface, means tor producing on said screen in accordance with said received signals sustained light spots or varying intensity representative of each elemental area of a received picture, and an oscillatory means synchronized with the said light spot control means for traversing each elemental area of said screen at a time period substantially midway between the time period of recurrence of controlled light illumination of each of said elemental screen areas by invisible light waves for extinguishing the fluorescent eflect produced upon said screen by said initial illumination.
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US2468452 *||29 Mar 1946||26 Apr 1949||Rca Corp||Cathode-ray indicator system|
|US2482814 *||26 Mar 1946||27 Sep 1949||Eastman Kodak Co||Photorecording|
|US2530828 *||29 Mar 1946||21 Nov 1950||Rca Corp||Radar system for indicating moving objects|
|US2612610 *||6 Nov 1948||30 Sep 1952||Westinghouse Electric Corp||Radiation detector|
|US2727183 *||22 Dec 1948||13 Dec 1955||Westinghouse Electric Corp||Radiation detector of the scanning type|
|US4097115 *||18 Nov 1976||27 Jun 1978||International Business Machines Corporation||Optical scanning device for producing a multiple line scan using a linear array of sources and a textured scanned surface|
|U.S. Classification||348/805, 348/205, 313/461, 250/484.2, 250/329, 315/1, 348/203, 250/363.1, 348/E05.133|