US1790898A - Method and apparatus for transmitting pictures - Google Patents

Description

Feb. 3, 1931. T. w. CASE 1,790,898

METHOD AND APPARATUS FOR TRANSMITTING PICTURES Filed Aug. 25, 1925' I5 Sheets-Sheet l 72 flmplifler IOCycZe Genera-or fludwn oscillaiz'ny sa siem 7 I ,5

5' Hm I JEL 5 I zvrs/vroR TTOR E YS Feb. 3, 1931. 'r. w. CASE 1,790,898

METHOD AND APPARATUS FOR TRANSMITTING PICTURES Filed Aug. 25, 1925 5 Sheets-Sheet 2 I 0 Eye 1e Generafor iilllhLlE} fludion osczllaizng Sysiem I VE/VTOR J60 M Feb. 3, 1931. T. w. CASE 1,790,898

METHOD AND APPARATUS FOR TRANSMITTING PICTURES Filed Aug. 25, 1925 5 Sheets- Sheet s & 5i Fa flmplifz'er IX/ 55 ii-"20 30 Cy cZe Generazon a fludion oscillaizng sys zem 1- z z/ve gwozzu J7 dR/VEVS Patented I Feb. 3, 1931 UNITED STATES PATENT OFFICE THEODORE WILLARD CASE, OF AUBURN, NEW YORK, ASSIGNOR TO CASE RESEARCH LABORATORY INCORPORATED, OF AUBURN, NEW YORK, A CORPORATION OF NEW 7 YORK Application filed August 25, 1925. Serial No. 52,381.

This invention relates to a method and apparatus for transmitting pictures, motion pictures, or direct vision over either radio or wire.

The main object of the invention is the production of a method and apparatus by means of which pictures, motion-pictures or direct vision can be transmitted in an efficient and satisfactory manner by either radio or wire.

Other objects and advantages relate to the details of the method and apparatus, all as will more fully appear from the following description taken in connection with the accompanying drawings, in which Figures 1, 2 and 3 are diagrammatic illustrations of embodiments of this invention.

The transmitting apparatus of Figure 1 includes a bulb -1 of glass or similar material, preferably having a substantially fiat end 2. The bulb 1 encloses a filament 3 adapted to be heated in any suitable manner. as by a source of potential 4 and the filament is connected in circuit with a metal cylinder 5 located within the bulb 1 and adjacent the filament, but as here shown, separated from it by a disk 6 having a relatively small opening aligned with the apex of the filament and with the conduit through the cylinder 5, such circuit including a source of potential.

Within the bulb 1 and above the cylinder 5 are two plates 7 parallel to each other so that electrons emitted by the filament and passing thru the cylinder 5will also pass 4 between the plates 7. Above the plates 7 there is placed another pair of plates 8 parallel to each other and disposed at substantially right angles to the plates 7 and so positioned that the stream of electrons emitted by the filament and passing through the cylinder 5 and between plates -7 will also pass between the plates 8. y

As shown, one plate of each pair is electrically connected to the cylinder 5. The end 2 of the bulb or bottle 1 has a coating 9 in the form of a semi-transparent or opaque layer of some conducting photo-electric material, such as potassium or any material which emits electrons under the influence of light. A substantial vacuum is maintained within the bulb 1 altho it should be understood that the vacuum may not be the highest obtainable as a small quantity of gas is preferred to prevent the electron stream emitted by the filament from spreading, and to keep it as a small pointer This transmitting apparatus is primarily based on the effect of photo-electric 'emission upon .a stream or quanta of electrons, preferably thermo-electrons, and makes use of a stream or pointer of such thermo-electrons emitted from a heated filament. The stream of electrons is pro- METHOD AND APPARATUS FOR TRANSMITTING PICTURES W fi duced by the filament cathode 3, which may be oxide-coated and is heatedas described. After leaving the filament the electrons may pass through the small aperture of the metal shield 6 which concentrates them into a thin stream so that they may pass through the tubular anode 5.

The movement of the pointer is controlled by electric fields applied to the plates 7 and 8. An electric field applied to the plates 7 will deflect the electron pointer in one direction and an electric field applied to the plates 8 will deflect the electron pointer in another direction, and as here illustrated, these two deflecting directions are at right angles to each other. The result is that at any instant the recording point forming the end of the stream of electrons occupies a position on the photo-electric layer 9 which both in direction and distance from its normal position at the center is theresult of the deflecting forces due to the differences of potential acting at that instant on the two pairs of plates. i

In addition to its deflection by an electric field, the electron stream can be deflected by a magnetic field by using outside of the tube either a permanent magnet or pair of coils in which the current is flowing.

The picture which is to be transmitted is focused upon the layer 9 of photo-electric material, and if the layer 9 is semi transparcut, the picture or image may be focused right through the coatin (lens 10 illustrated for that purpose). n case the layer 9 is thick enough to be opaque, the picture to be transmitted is focused upon the potassium or coating 9 on the side facing the electron stream,-lens 11 illustrated being for that pur ose.

iththe picture focused through or upon the photo-electric coating 9, the first essential thing is to cover the entire picture with the electron stream in approximately 1/l0th of a second, or reater i. e. a speed productive of direct vision. This may be accomplished by impressing electro-statlc variations from an alternating current on both the pairs of plates 7 and'8. The cycle of' one current need not, be greater than approximately 8 to cycles. For illustrative purposes, I will describe the operation in connection with an alternating current of 10 cycles impressed on the plates 8.

The result 'f this impressed current on the lates 8 is that the electron ointer will go back and forth over the en 2 of the bulb and over the picture ten times per second, but only in a single line. Assuming a picture 6" x 6", and the condition that it is desirable to break-up the picture into 100 different lines to the. inch, that would mean that there would have to be 600 lines across the picture.

If the first electro-static field which is applied to the plate 8 causes the electron stream or pointer to traverse the picture ten tlmes per second,- then the electron pointer crosses the picture in 1/10th of a second. Now, in order to break this up into 600 parts, it is necessary to divide 600 by 1/10th, or in other.

words, an alternating current of 6000 cycles per second must be applied to plate 7 Thls alternating current of the required number x of cycles may be produced in any suit-able and well known manner, as for instance, by an audion oscillating system, whereas the alternating current applied to the plates 8 altho producible in various known ways, may

be-produced by an ordinary 10 cycle gen-' erator.- A

Under the conditions described, the entire picture focused on or through the coating 9 will be covered and broken u into fine lines in the necessary time to pro uce the desired results. Q

There are several circuits which can be used in obtaining modulation in this transmission of the picture focused on the coating 9. Perhaps the simplest form is that connecting the photo-electric coating 9 with the heatedefilament 3 or source of the electron stream. In the first instance, no additional source of potential will be inserted in this circuit, but it may contain the primary 12 of a transformer, the secondary of which may lead to suitable well known amplifying devices, or the coating 9 and the source of the electron stream 3 may be connected in circuit with the filament and grid of a properly biased audion bulb for amplification purposes, the methods of amplification and therequired circuits being well known.

In the circuit just described, the switch.

electric material. The units of this explorijigelectron finger alternately arerushing towards firstan illuminated portion ofthe "photo-electric material, and next an unillu"- minated portion of the photo-electric material, there will as a result obtain difi'erent electrical phenomena in the completed circuit, due to'the negative electrons approaching different potential points on the illuminated photo-electric electrode 9, and minute electric currents will flow in the complete circuit controlled by the illuminated potassium electrode.

It is at present my belief that this action is based on the law that When two dlS-SlnlllflIL charges comein contact in a circuit, a minute current will fiow,-contact electricity. In this manner, the picture is broken up and translated into consecutive electron pulses which are amplified, and may then be turned back into corresponding light fluctuations and when put back on a screen in the proper position at the receiving .end will reproduce the picture focused on or through the photoelectric electrode at the sending end; In

addition, these electron pulses impressed on pressed on the circuit which connects the fila'- ment with the cylinderandas the impulses increase or decrease, the intensity of the electron stream correspondingly increases and decreases, consequently the fluorescence in. creases and decreases in like manner, and the pattern traced in visible lines is photographically active. It is only necessary to put these changes in intensity resulting in changes in fluorescence in their proper position in order to re-form the picture focused on the coating 9 at the sending end. This is done by making the varying intensityelectron pointer cover the fluorescent screen in the same manner and synchronized with the electron pointer at the sending end. This requires impressing 10 cycles on one of the pairs of plates in the repair.

methods may be used that produce the movement of the electron bulb. However, other pointer in the sendin 1n synchronizing and separate fields may be used to produce the movement of the finger other than here de-' scribed.

As an alternative arrangement, there may be placed in'the receiving bulb a grid large enough so that the electron pointer will always pass through it, and then the incoming current pulses may be impressed upon this grid to thereby control the current intensity of the electron pointer which will correspondingly control the fluorescence of the coating corresponding to the coating 9. On the other hand, a small grid may be placed between the filament and the cylinder to control the intensity of the electron pointer.

Altho the apparatus of Figure 1 may be utilized as above described withoutany extra potentiaLinthe circuit between the electrode 9 and the filament 3, it may perhaps be i preferable to place a potential in this circuit making the filament 3 negative and the photoelectric electrode 9 positive. This may be done by closing switch 13 and-opening switch 14. In this case the electrons as they approach an illuminated portion or more negative sphere of influence would, as a result of the tendency negative emission of the photo-electric material due to light, give a decreased current in this circuit and reversely an increased current Where the electrons impressing a direct current on the filament photo-electric electrode circuit to impress an oscillating carrier current on this circuit. This may be eflected in any suitable and well known manner. In this arrangement, the oscillating carrier current will be likewise modulated as the negative electrons approach consecutive and either more or less negative spheres of influence in the photoelectric layer. In such case where an oscillating carrier current is used quanta of electrons will be directed to the different parts of the photoelectric electrode 9, depending on the frequency of the pulsating carrier current, and

this frequency may be determined empirically for best results.

Instead of using a pulsating current, an alternating current maybe Impressed on tlns circuit. altho at present such arrangement seems less preferable. In case of pulsating direct current the photo-electric material should be positive and the'filament negative.

There are various other combinations and circuits which may be used, but all depend on the fundamental idea of obtaining modulation of'a carrier current circuit depending on the charge of the sphere of influence into which the thermo-electron pointer is converging at any one instant of time, which in turn depends upon the focusing of the picture on the photo-electric electrode or coating 9. In addition, there may be amplification of the modulation so obtained and there remains only putting together again at the receiving end in terms of light and at the proper position to re-form the image and at a speed to produce direct vision.

Obviously, a single'picture may be transmitted or a series of pictures in sufficiently rapid succession to produce direct vision. In the latter case where a moving picture is to be transmitted it would be preferable to employ a shutter arrangement at the sending end and possibly also at the receiving end in order to obviate any blurring. -On the other hand, a chopper carrier current might be employed instead of the shutter.

In Figure 2 there is illustrated a large grid 15 interposed between the plate electrode 16 and the filament 3 and in the path of the electron stream or pointer which is indicated in dotted lines in the figures. This grid may be formed of any suitable material. and is full of very small holes and is coated with a photo-electric material. The picture to be transmitted is focused upon the photo-electric material deposited on the grid 15 and the holes of the grid should correspond to the points of the picture to be transmitted. As shown. the grid 15 is disposed in a plane substantially parallel with the end of the plane 2 of the bulb. The plate electrode 16 is connected in circuit with the filament 3, and this circuit may include the secondary of atransformer as described in connection with Fig. 1 or the electrodes may be connected to any amplifying means such 'as the grid filament circuit of an audion. In addition, the circuit connecting the plate 16 with the filament 3 need not include any source of potential or it may include a source-of direct current or a source of oscillating current, or a source of alternating current. all as described in connection with the analogous cirplate filament circuit results. In this case the electron finger may spread on emerging from the grid and make no difference so long as it is point controlled at the grid on which the picture is focused. I

In addition to the connections shown in the drawings, the grid 15 may have an electric connection to the outside of the bulb so as to permit of biasing the grid, if desired.

The structure of Figure 3 differs from Figure 1 in the interposition of a ring electrode 17 between the filament 3 and the photo-electric coating or electrode 9, and as illustrated the ring 17 is connected to the coating 9 by an electric circuit including a source of potential 18 arranged in such a manner that the ring is positive and the photo-electric coating 9 is negative, thereby producing an actual emission of electrons. The introduction ofthe exciting circuit between the coating 9 and the ring electrode 17 makes the spheres of influence of the photo-electric electrode more pronounced. This additional circuit between 'the ring 17 and the photo-electric electrode 9 may also be utilized in connection with the structure of Figure 2 in'that the ring may be inserted between the grid 15 and filament 3 and may be connected in circuit with the photo-electric coating on the grid through a source of potential in such ,a manner as to maintain the rin positive and the photoelectrode negative in the same manner as Figure 3, and for the same purpose of effecting more pronounced results.

Any suitable and known means may be utilized in the ordinary manner for applying an electric field of proper cycle to the plates 7 and 8, for instance, as described, a generator or an audion oscillating system. Altho I have shown and described in a diagrammatic manner specific structures and arrangement of apparatus and the parts thereof, as instancing embodiments of this invention, I do not desire to restrict myself to the details of the structure or the specific method of operation described, as various changes may be made within the scope of the appended ,claims.

Picture as used in the claims hereof -is deemed to include any picture, direct vision, object or image that canbe produced or be focused on the photo-electric layer, and focusing is deemed to include any suitable means of producing such picture on such coating.

1 claim 1. The method of transmitting pictures, motion-pictures or direct vision comprising causing an electron stream to traverse the picture when the latter is focused upon a photo-electric material having a negative po tential maintained thereon.

2. An apparatus for transmitting pictures, motion-pictures or direct vision, comprising a filamentary cathode, an anode of tubular form, a circuit connecting the cathode and the anode, and including a source of potential,

means for deflecting the stream of electrons emitted by the cathode, a'photo-electric layer over which said electron stream as deflected is adapted to pass and upon which the picture is adapted to be focused, and a circuit connecting the photo-electric layer and the cathode.

3. An apparatus for transmitting pictures, motion-pictures or direct vision, comprising a filamentary cathode, an anode of tubular form, a circuit connecting the cathode and the anode, and including asource of potential, means for deflecting the stream of electrons emitted by the cathode, a photo-electric layer over which said electron stream as deflected isadapted to pass and upon which the picture is adapted to be focused,a circuit connecting the photo-electric layer and the cathode, and means for maintaining the photo-electric layer negative.

4. An apparatus of the class described comprising an elongated bulb having a substantially flat end, a coating of photo-electric material on the interior of theflat end of said bulb, a cathode within the bulb, a tubular anode within the bulb arranged to direct the stream of electrons emitted by the cathode toward the said photo-electric coating, means for deflecting said stream of electrons in'different directions andmeans for focusing a picture upon said photo-electric coating, and a circuit connecting'the photo-electric coating and the cathode.

5. An apparatus of the class described comprising an elongated bulb having a substantially flat end, a coating of photo-electric material on the interior of the flat end of said bulb, a cathode within the bulb, atubular anode within the bulb arranged to direct the stream of electrons emitted by the cathode toward the said photo-electric coating, means for deflecting said stream of electrons in different directions, and means for focusing a picture upon said photo-electric coating, a circuit connecting the photo-electric coating and the cathode, and means for impressing an electric current'on said circuit.

6. An apparatus of the class described, comprising an elongated bulb having a sub stantially flat end, a coating of photo-electric material on the interior of the flat end of said bulb, a cathode within the bulb, a tubular anode within the bulb arranged to direct the stream of electrons emitted by the cathode toward the said photo-electric coating, an opaque disc having a small opening positioned between said anode and cathode, said opening being in line with the opening of the anode and the apex of the cathode, a pair of spaced parallel plates positioned between said anode and said photo-electric coating, a second pair of spaced parallel plates having their plane surfaces at right angles to the plane surfaces of the first-named plates and positioned adjacent the same on the side of the photo-electric coating means for deflectin said electron stream l y energizing said pairs of plates with a high and low frequency alternating current respectively means for focusing a picture upon said photo-electric coating, :1 clrcuit connecting the photo-electric coating and the cathode and means for impressing an electric current on said circuit.

In witness whereof I have hereunto set my 10 hand this 17th day of Au st, 1925.

THEODORE ARD CASE.

DISCLAIM ER 1,790,898.I7re0d0re Willard Case, Auburn N. Y. METHOD AND APPARATUS FOR Tmsm'rrmo Prc'nmns. Patent dated February 3, 1931. Disclaimer filed August 22, 1939, by the inventor; the co, (Jase Research Laboratory, I consenting. Herelg enters a disclaimer to claim 2 of said Letters Patent.

[ final Gazette September 1.9, 1939.]

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