US2192942A - Television modulation system and apparatus - Google Patents

Description

W. SOLLER March 12, 194.0.

TELEVISION MODULATION SYSTEM AND APPARATUS s Sheets-She et 1 Filed 001;. 4, 1937 v INVENTOR.

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March 12, 1940. w. SOLLER TELEVISION MODULATION SYSTEM AND APPARATUS Filed Oct. 4, 1937 3 Sheets-Sheet 2 a INVENTOR. MM 60mm,

ATTORNEY W. SOLl-ER March 12, 1940.

TELEVISION MODULATION SYSTEM AND APPARATUS s Sheets-Sheet s Filed Oct.

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gl f/tem 0506600 I ATTORNEY Patented Mar. 12, 1940 lTENT OFFICE TELEVISION MODULATION SYSTEM AND APPARATUS Walter Soller, Cincinnati, Ohio, assignor of onehalf to William H. Woodin, Jr., Tucson, Ariz.

Application October 4, 1937, Serial No. 167,281 11 Claims. (01. 178-711) My invention relates broadly to television'and more particularly to an improved modulation system and apparatus especially adaptable thereto.

The system and apparatus hereinafter described are improvements in television systems of the type disclosed in my copending applications Serial Number 733,300, filed June 30, 1934, for Television system, and Serial Number 4,393, filed January 31, 1935, for Television system, and employs a plurality of low frequency carrier currents to be simultaneously modulated by light intensities in a corresponding plurality of lines in the object televised.

One of the objects of my invention is to provide a dual photoelectric scanning system simultaneously operable to translate light intensity from the same portion of an object into electric signalling energy.

Another object of my invention is to provide a push-pull type of. modulation system in which light from a single point in an object is effective on dual photoelectric means connected with a carrier current transmission system. A further object of my invention is to provide a single electron tube structure enclosing dual photoelectric means in a modulation system operative to produce a push-pull modulated wave.

Still another object of my invention is to provide a single electron tube device enclosing dual photoelectric means in a scanning system adapted to maintain the device at all times normal to the light rays received from the object scanned.

A still further object of my invention is to provide a pair of single photoelectric devices arranged for movement in synchronism with respect to dual images of an object scanned in order to produce separate signal currents for push-pull modulation of a carrier current.

Still another object of my invention is to provide a system for simultaneously modulating and combining a plurality of low frequency carrier currents, the modulations being effected in pushpull manner and in accordance with light intensity on adjacent sections of a linear portion of an object to be televised.

Other and further objects of my invention will be apparent in the system and apparatus hereinafter described with reference to the accompanying drawings, in which:

Figure l is a side ,elevational view, partly in section, of one form of apparatus, of my invention adapted to the modulation system of myinvention; Fig. 2 is a plan view, partly in section of the apparatus of Fig. 1; Fig. 3 is an enlarged detail view through the dual photoelectric device in the form of my invention shown in Figs. 1 and 2, and illustrates the base mounting therefor; Fig. 4 is a schematic diagram of the connections in the push-pull modulation system of my invention;

view thereof with parts in elevation taken substantially on line 99 in Fig. '10, Fig. 10 a horizontal sectional view thereof on line Ill-I0 in Fig.

9, Fig. 11 a cross-sectional view thereof on' line l l--! I in Fig. 9, and Fig. 12 a detail sectional view on line l2-l2 in Fig. 9; and Fig. 13 is a diagrammatic showing of an arrangement for scanning a moving film by means of the essential elements of the embodiment shown in Figs. 9-12.

The apparatus herein described may be employed'in combination with any type of multiple alternator generating a sufficient plurality of carrier currents for the several photoelectric units employed simultaneously. An alternator such as disclosed in my copending application, Serial Number 733,300, may be employed and connected as shown in Fig. 4, as will hereinafter be more fully defined.

In order to make use of the push-pull modulation system of my invention, however, it is not necessary that a plurality of photoelectric units be employed, and thesystem employing only one dual unit may be simply considered by regarding only the first dual arrangement shown in Fig. 4. The structure disclosed for scanning in one dimension would have to be replaced by twodimen'sional scanning means if only one dual unit is employed. The same benefits attending pushpull operation, however, will be obtained by using the system of my invention with two-dimensional scanning systems. i

Referring to the drawings in more detail I have shown inFig. 1 a camera casing I having an adjustable lens system 2 mounted in one side thereof and adapted to focus an image of the object to be televised in a plane along which a photoelectric device 3 is movable for scanning the image. The photoelectric device 3 contains a dual multiple cell arrangement in the form shown more clearly in Fig. 3, and consisting of two columns of superimposed, separately insulated, photosensitive elements 4 and 4', separately connected through the wall of the device by conductors 5. Associated with all of the elements 4, 4', is a common anode structure 8, comprising a pair of strip members mounted parallel in the same plane and closely spaced so as to define a narrow slit constituting a scanning aperture. Referring more particularly to Fig, 3, it will be seen that the photosensitive elements 4, 4', are triangular in shape and in combination present the apex of a triangle normal to the scanning slit so that light entering normal to the plane of the anodes 6 and passing therebetween will fall equally on the two sets of photosensitive elements 4, 4'. A covering I i is provided on the exterior of the device 3 to exclude light other than that passing between the anode members 6, through the scanning aperture. The tube 3 is described more fully in my copending application Serial No. 167,282, filed October 4, 1937,'for Photoelectric tube.

The photoelectric device 3 is mounted on a base 1 which is pivotally mounted in a carriage 8. The carriage 8- is mounted on rollers and arranged to oscillate within the casing I, being ac tuated by any suitable reciprocatory drive mechanism from a synchronous motor 9. A Scotch yoke mechanism, comprising a crank member It engaging a slot ii in the carriage 8, is shown in Figs. 1 and 2 and produces simple harmonic motion in the carriage 8 for constant rotation of the motor driven crank lfi. Any other form of mechanism, such as one to produce linear movement in the carriage 8, may be conveniently substituted for the Scotch yoke type shown. Cam

or electromagnetic means may be found useful in this connection. A counter-weight for the crank ii) is shown at 14 in the drawings.

In order to maintain the photoelectric device 3 at all times normal to the light rays forming the image, so that light may fall equally on the photosensitive elements 4, l, the base I is mounted in bearings l5 in the carriage 8, and is biased by mean of a spiral spring l6, secured between the carriage 8 and the base i, to stand normally with the plane of the anode 6 parallel to the plane of the image and slightly forward thereof, as shown more clearly in Fig. 3 where the plane of the image passes through the center of the pivotal mounting of base I. This position is shown in full lines in Fig. 2.

The carriage 8 is adapted to reciprocate between two limiting positions shown in Fig. 2 in dotted lines. Forward of the carriage 8 I provide an upstanding wall member I! having a concave cam edge l8 formed on the rearwardly projecting head portion thereof. The base 1 carries a roller !9 on the forward portion thereof adapted to ride on the cam edge l8. Thus, as the carriage 8 travels towards eitherof the limiting positions the base I and the photoelectric device 3 are pivoted in the plane of the image by the action of the cam edge IS on the base 1 through the roller l9 and against the tension of the spiral spring 16. As the carriage returns to central position from either limiting position the spring it maintains the roller l9 in contact with the cam edge 18 so as to preserve the normal relation of the scanning slit and the incident light rays. It

. will be understood-therefore that the photosensi- Referring now to: Fig. 4, the system of my invention comprises a series of alternating current generators producing carrier currents of different frequencies and connected separately with pairs of photosensitive units 51, 4' in the photoelectric device 3. The alternator systemshown is of the inductor type and includes field coils 26, 20a, etc., energized from a direct current source at 2!, and. inductor coils 23 and 23', and 23a and 23a, etc., coupled through a varying magnetic field produced in a core structure, 24, 24a, etc., of varying reluctance. One terminal each of coils 23 and 23, 23a and 23a, etc., is connected respectively to photosensitive elements 4 and 4'; the other terminal of each being connected respectively to resistance elements 25 and 26, in common, the resistance elements being connected together and through a source of potential 27 to the anode structure 6. Thus resistance element 25 carries the currents of coils 23, 23a, etc., as modulated respectively by the action of photosensitive elements 6, da, etc., and resistance element 26 carries the currents of coils 23, 23a, etc., as modulated respectively by the action of photosensitive elements 4', 4a, etc. The potential of source 2'! is such as to provide operable positive potential on the anode structure 6. The instantaneous potentials in coils 23 and 23 are indicated, under which photosensitive element 4' is operative to modulate the carrier current in resistance 26 due to coil 23 in negative relation and the photosensitive element 2 is operative to modulate the carrier current in resistance 25 due to coil 23 in positive relation; the condition upon change of polarity in both coils. 23 and 23' is such as to reverse the sense of the modulation in resistance 25 and 2E. The modulated currents in resistances 25 and 28 flow in the same direction with respect to the source 21 and the potentials supplied to the output terminals, connected as shown, are in push-pull relation with respect to the neutral terminal 28 connected at the juncture of resistances 25 and 28 with source 21. The output of the modulator system is amplified and transmitted by any suitable arrangement to receiving apparatus of cooperative type.

Figs. 5, 6 and 7 show a modified form .of cam arrangement suitable for operation in the structure shown in Figs. 1-3. The upper edge of the upstanding Wall member I? is formed with an overhanging lip portion i8 convex in form and adapted to guide a roller pilot member 30 mounted in a modified base 1' having a slot for accommodating the shank portion 30 of the pilot member, which is slidable with respect to the base The shaft 3!, pivotally mounting the base 7' i. in carriage 8, has a portion thereof, extending through the slot in base i, of rectangular cross section and the shank portion 38' of pilot member 39 has a slot engaging the rectangular portion of shaft 3| so as to control the pivoting of the base i and photoelectric device 3 in accordance with the movement of pilot member 30 on the convex runner id, as shown more clearly in Fig. 5 wherein the limiting positions of the car riage t are shown in dotted lines.

Fig. 8 shows schematically an arrangement for transmitting from film records of light intensity, the arrangement employing a stationary photoelectric device 3 of the type described and a light source 32, the film 34 passing between the source and the device 3 at constant speed. A lens systern 35, 35a is provided to diverge the light rays passing through the film, which is usually of narrow width, to embrace substantially the entire I scanned by each device.

photosensitive assembly 4, 4', in the tube 3. The film record is thus simultaneously scanned in one direction by the series of photosensitive elements in the assembly 4, l, and in the other direction by the constant movement of the film 32, the device 3 being disposed parallel to the width of the film. Intermittently moved film may be scanned in the usual manner, the photoelectric device 3 being moved across the image of each frame, and preferably in synchronism with the movement of the film.

Figs. 9-12 show a modified structure of photoelectric device and an arrangement for employing the device in the push-pull modulation system of my invention. The device 36 contains a single series of photosensitive elements 31 as can be seen i in Fig. .10, and is of a type described in my copending application Serial .No. 167,282, filed October 4, 1937, for'Photoelectric tube. A similar anode structure 38 is provided and likewise a covering 39 to exclude light except as admitted through the anode structure 38. Two such photoelectric devices, 36 and 38', are required for push-pull modulation and the object must be The arrangement shown in Figs. 9-12 comprises a casing l in which is mounted an adjustable lens system 2' having a lock screw 40, as shown in Fig. 11. At the rear of the casing is mounted a dual mirror arrangement M in such a manner as will reflect an image of the object focused at either side of the mirror arrangement, in the planes indicated on the drawing, Fig. 10. A prism .or other suitable refleeting means may be substituted for the mirror arrangement shown.

Means similar to that employed in the arrangement shown in Figs. 1 and 2 is provided for moving the devices 36 and 36in scanning the image of the object to be televised. This means includes a motor 9 connected with a crank member l0 and with a second crank member l0 opposite thereto. A modified form of carriage is provided at 42 and 42' adapted to operate on rails 43 and 43 mounted within the casing i. The carriage 42 and 42' are provided with slots [2 and I2 engaging the crank members l0 and I0. It will be understood that the images formed in the image planes are in reverse relation, that is, a point in the object appearing at A in the one image will appear at A in the opposite image as indicated in Fig. 10. The photoelectric devices therefore will be moved in reverse relation which is conveniently accomplished by displacement of the-crank members, ill and i0, 180 with respect to the driving shaft of motor 9, as shown in Fig. 9. Counterweights l4 and M are provided as in the structure of Figs. 1 and 2.

The carriage 42 is provided in its upper portion with an adjustable member 45 constituting a'base for mounting the photoelectric device 36. A bolt and wing nut arrangement is provided at 46 to maintain the base in adjusted position. A similar arrangement of parts is provided with respect to carriage 42' and photoelectric device 36', the purpose of this arrangement being to provide separate adjustments of the positions of the two devices 36 and 36' with respect to the focusing means 2' and the image planes defined therefrom. Once adjusted for any particular photoelectric device the adjustment need not be disturbed and subsequent adjustments of the lens system 2' for various objects will equally pertain to the separate photoelectric devices.

Fig. 13 illustrates schematically an arrangement for transmitting from film records of light intensity employing the form of apparatus shown in Figs. 9-12. As set forth in connection with Fig. 8 the photoelectric devices are stationary, and the film 34 is moved in a direction with respect to the photoelectric devices such that the width of the film is scanned by the series of photosensitive elements in the devices and the length by the movement thereof in the determined direction. A source of light 32 and lens system 35 and 35a are employed similarly to the arrangement shown in Fig. 8. Intermittently moved film may be scanned in the usual manner, the photoelectric devices being moved across the images of each frame, and preferably in synchronism with the shifting of the film.

The push-pull modulation system of my invention is adaptable to other scanning systems than those of the type described. Where, for example, a single pair of light sensitive elements are employed, the pair is moved as a single unit in a two-dimensional scanning arrangement, both elements of the pair receiving light simultaneously from the same point in the object. In an electron beam scanning system of the type disclosed in my copending application Serial Numb er 222,897, filed Aug. 3, 1938, for Television system, or in an electron ray two-dimensional scan ning system, both of which operate to discharge elementary condensers charged by the photoelectrio action of one electrode thereof, a pair of elecl1 tron scanning means focused on the one elementary condenser simultaneously and moved in synchronism across the several elementary condensers is required, providing dualsignals for the push-pull modulation of a carrier in accordance with the system of my invention. In such systems, a second cathode source of electrons mounted for emitting electrons to be formed and deflected by the usual means together with the usual electron stream is all the additional structure necessary in order to employ the push-pull modulation system of my invention.

Thus, while I have shown my invention in certain preferred embodiments I intend no limitations thereby upon my invention, and modifications may be made therein within the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. In a television system, a push-pull modulation circuit comprising photoelectric separate sources of the same television signal energy, and means connected separately in circuit with said photoelectric sources for supplying a carrier current in opposite phase to each of said sources for modulation by the energy from said sources in push-pull relation.

2. In a television system, a push-pull modulation circuit comprising separate photoelectric elements each subject to light rays of the same intensities, and means connected separately in circuit with said photoelectric elements for supplying a carrier current in push-pull relation to said photoelectric elements for modulation thereby.

3. In a television system, a push-pull modulation circuit comprising a plurality of pairs of separate photoelectric sources of the same television signal energy, and means including separate sources of carrier current connected in cir-'- cuit with the photoelectric sources in each of said pairs for simultaneously modulating a corresponding plurality of carrier currents respectively by the energy from a pair of said sources in push-pull relation, each said carrier current being of difierent frequency and supplied to the respective sources of signal energy in opposite phase.

4. In a television system, a push-pull modulation circuit comprising a plurality of pairs of separate photoelectric elements, each element of a pair being subject to light rays of the same intensities, and means connected separately in circuit with the photoelectric elements in each of said pairs for simultaneously supplying a corresponding plurality of carrier currents respectively to said pairs of elements in push-pull relation, each said carrier current being of different frequency and modulated by the energy in the respective pair of photoelectric elements.

5. In a television system, a plurality of sources of carrier currents of difierent frequencies, a separate corresponding plurality of multiple photoelectric units each connected with one of said sources of carrier current, each of said multiple units comprising a plurality of light sensitive elements subject to rays of the same light intensity and operative in push-pull relation with the carrier current from the respective source for modulating the said carrier current.

6. In a television system, a push-pull modulation circuit comprising a source of carrier current having dual output circuits, a pair of load resistors connected in series with said dual output circuits between terminals of opposite polarity, the junction of said resistors constituting a neutral point in said source of carrier current; a pair of photoelectric devices having anode and light sensitive cathode elements subject to rays of the same intensities, a source of potential connected with said anode elements in common and With said neutral point in said source of carrier current, separate connectionsfrom said cathode elements to the remaining terminals of opposite polarity in said dual output circuits; and pushpull output connections from said neutral point and each of said load resistors.

'7. In a television system, in combination, linear scanning apparatus for simultaneously deriving a plurality of dual signals comprising dual light sensitive means having a plurality of pairs of photoelectric elements arranged in parallel linear relation, means for receiving signal light rays equally on paired elements of said dual means, means for relatively moving said dual means in scanning relation to an object whereby signal light rays from various lines in said object are received by said dual light sensitive means and means connected separately in cir cuit with the photoelectric elements in each of said pairs for simultaneously supplying a corresponding plurality of carrier currents respectively to said pairs of elements in push-pull relation, each said carrier current being of different frequency and modulated by'the energy in the respective pair of photoelectric elements.

8. In a television system, scanning apparatus for deriving dual signals comprising a photoelectric device containing dual light sensitive means so constructed and arranged as to receive signal light rays from one direction only equally on each element of said dual means, means for moving said device in scanning relation with respect to an object, signal light rays being directed to said device from said object in varying directions, and means cooperative with the aforesaid means for orienting said device to the direction of the signal light rays fromthe various points scanned in the object so that substantially equal light intensity is received at each element of said dual light sensitive means.

9. In a television system, in combination, photoelectric means having dual light sensitive cathode connections and single anode connections, scanning means for, directing signal light rays from an object to be televised simultaneously on said photoelectric means, dual signals being emanated at said dual cathode connections with respect to said single anode connection in accordance with the light intensity in a particular portion of said object, and meansconnected separately in circuit with said photoelectric means between said dual cathode connections and said single anode connection for supplying a carrier current in push-pull relation to said photoelectric means for modulation thereby.

10. In a television system, in combination, scanning apparatus for deriving dual signalsineluding a single photoelectric device having dual light sensitive means, a pivotally mounted base member for supporting said device, a roller mounted in a projecting portion of said base member, a cam surf-ace, spring means connected with said pivotally mounted base member and adapted to maintain. said roller in contact with said cam surface, and means for moving said base member with respect to said cam in a scanning motion, said spring means maintaining said roller in cooperation with said cam for orienting said photoelectric device to receive light rays from varying directions equally on said dual light sensitive means.

11. In a television system, in combination, scanning apparatus for deriving dual signals including a single photoelectric device having dual light sensitive means, a pivotally mounted base member for supporting said device, a cam runner, a pilot member slidably connected with said base member andhaving roller means engaged with said cam runner for orienting said photoelectric device to receive light rays from varying directions equally on said dual light sensitive means, and means for moving said base member in a scanning motion, said pilot member being moved therewith for operation with respect there- WALTER SOLLERQ

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