US1933392A - Television transmitting system - Google Patents

Description

1933- G. T. SCHMIDLING 1,933,392

TELEVISION TRANSMITTING SYSTEM Filed Oct. 25, 1930 3 Sheets-Sheet l AMPLIFIER MODULATOR 3 22 OSCILLATOR 'ba /tfsd/ Oct. 31, 1933.

G. T. SCHMIDLING TELEVISION TRANSMITTING SYSTEM Filed Oct. 25, 1930 3 Sheets-Sheet 2 F T"? I I J? I i4 25 L- 32 A m I :4

o i. 27 6.1 do 26 1933- G. T. SCHMIDLING TELEVISION TRANSMITTING SYSTEM Filed Oct. 25, 1930 3 Sheets-Sheet 3 Patented ocesl, 1932;

1,933,392 TELEVISION.TRANSMITTING SYSTEM 1 Gilbert-'1". SchmidlingChicago, In; Application-OctoberZS, 193 0. Serial No. 491,108 3 Claims. (c1; its-fe This invention relates totransmission or images by radio or wire, that is to say,-atelevision transmission system; Incarrying out by 'inventionI utilize the principles of a double disc television transmission system disclosedbroadly in my-prior application bearing Seria1"No.-'392,887, filed September 16,1929,- In the pricrapplioation referred to I provide means'for directly scanning the subject by directing light rays from different lim-' ited portions of the" subject upon a successively photo electric celland at the same'time pro- 'viding increased illumination'to that limited portion of the subject that is being scanned;

In the present invention I provide means for scanning a wider area-than'is nowpossible either with ordinary'scanningdevices or with my double disc transmitting system, providing'increased illumination of limited areas, as above mentioned.

In accomplishing this purpose I-provi'de means for using two or mores'eparate scanning units so spaced apart that each will scan a part of a given area and thereby I cover the entire area to be scanned. For exampla' if the original system is' capable of televising'a stage thirty feet wide, I provide means for connecting two scanning devices in duplicate, at a distance of thirty feet apart, together with a switching arrangement 'for-consecutively" connecting these transmitters to the final amplifier so as to scan a stage sixty feet long. If'three suchtransmitters are utilized, a stage ninety feet long will be covered. V The invention may bestbe understood by reference to the accompanying drawings, in which Figure 1 is a diagrammatic sketchrepresenting a single scanning unit; '1 Figure 2 is a top view partly in section ofthe scanning unit shown inFigurefl; I Figures 3 to 6 are details of control mechanismof the scanning-disc;

" Figure '7 is a diagrammatic sketch showing the arrangement for utilizing a plurality of scanning units to cover an increasedarea;

Figure 8 is a wiring diagram showing one means that maybe used for securing synchronismbetween the rotated discs of the several scanning unit's. 1 ,7 "In-television apparatuses and" systems, it is a well known law thatthe intensity of light decreases with the square of the distance from the source of light. This law'presents an obstacle which appears to be very diflicult to overcome in a transmission ofsubjects which are any appreciable distance from the'light sensitiveapparatus. Owing to this-fact, more than to any other in all probability the transmission of images by tele ring a damage'or' discomfort to the subject.

vision has heretofore been-'limitedto the transmissionof very small scenes and-the intense light necessary to obtain a fairly brilliant picture at the receiving apparatus makes it uncomfortable for the subject if'a living one is beingtransmitted. r I However, it is possible 'to intensely illuminate a small portion of asubject-at relatively distant intervals and for very short periods without caus- Ihave devised means whereby such an intermittent illumination of the subject maybe accomplishedand have inaddition thereto Iprovided n eanswhereby thesubject may be scanned in suchiashion as to affect anexpcsure of the light sensitivemeans only to that portion of the subject being illuminated and only during the time ofsuch illumination; r l

' In Fig; 1 the subject is illustrated at 10 and I at 11 I illustrate a source of light which for the purpose of illustration'is shown as an electric are receiving current from agenerator 12. ,The light from this :source ispassed through a condenser lens construction at- 13 .so' as to obtain an'area "of illumination of-constant intensity throughout its surface which: area is projected against a scanningdisc 14, which disc is rotated from a suitable source'of powerat the desired speed.

Light passing through the scanning discis passed through -a projecting lens of any well known type illustrated diagrammatically at 15', and in this manner the subject is scanned by the beam of light issuing from the projecting lens.

which maybe made'the usual speed now used or faster if desired; that is to say, inthe neighbor- .ho'odof 15 to 20 revolutions per second The scanning disc hasa relatively large numberof scanning apertures therein so that "the time that any particular spot of the subject is illuminated is a-very smallportion of the totaltimenecessary to illuminate the subject over theentire surface and yet this total illumination is accomplished 15 to ZO times per second. i v

Associated with the light source is a second scanning device consisting'of a condensing lens at 16 which bringsthe light from the subject to a scanning disc-1'7, and this light is directed through a second lens at 18 where it is condensed and thrown upon a photo-electric cell 19. I

The light passes over the entire subject once for each rotation of the scanning disc 1 The current generated by the illumination of v the photo-electricCell is directed to-an amplifier '20 of any well known construction, and the out put ofthe amplifier isconnected to ar'nodulator 21 in the usual manner, and from this modulator the energy is transmitted to an oscillator 22 of the usual construction, and from there the energy is sent out over an antenna 23 to be picked up by a receiving apparatus at some remote point.

The illuminating device including a scanning disc 14 and the direct scanning device including the scanning disc 17 are so operated with respect to each other that the direct scanning device scans the subject insynchronism with the illuminating device. That is to say, while the spot is being illuminated upon a subject from the light source, this same spot is reflecting its light through the lens 16 and through an aperture of the scanning disc 17 to the photo-electric cell 19. In this way advantage is taken of any natural illumination which may be upon the subject and the additional illumination provided by the intermittent illuminating device described. The photo-electric cell 19 is, of course, cut off from any source of light except that from the spot on the subject that is being illuminated at that particular time.

In order to make it more easy to focus the two devices upon the same spot, I prefer to illuminate a somewhat larger portion of the subject than is covered by the scanning device itself. This may be accomplished by the projector lens 15 projecting the light upon a larger spot of the subject than is covered by the lens of the scanning device and the scanning disc 17 at the same time. I

In Fig. 2 I show more or less diagrammatically the relation of the scanning discs 14 and 1'? and the associated apparatus. It isnecessary, of course, to place the ilhuninatingcleviceand the scanning device at a distance apart which is slightly greater than the radius of the scanning discs. However, to aid in focusing the two devices together, they should be placed as close together as possible, because then there would be less difference in the angle that the two make with the subject and less correction would be resuired by the lens associated therewith. The making of the illuminated spot larger than the scanned spot allows fora certain amount of inaccuracy, so that it is a comparatively easy matter to keep the two devices trained upon the same illuminated portion of the subject.

In Fig. 4 there is illustrated diagrammatically driving means whereby the two discs 14 and 17 may be rotated in synchronism. A suitable constant speed or synchronousmotor 25 is connected as by means of the chain drive 26 to the driving sprockets 27 and 28 of the two discs. In this manner the two discs will be rotated at the same speed. 7

A suitable adjusting screw 29 may be provided on one of the discs for originally adjusting them, so that the scanning apertures therein may be perfectly aligned. That is to say, the first aperture of disc 14 placed vertically above its axis at the same time the first aperture of disc 17 is vertically above its axis. Having once established this relationship, it should remain the same throughout the operation of the two discs.

One of the discs, in this instance-the disc 17, must be made angularly adjustable sothat its angular position relative to the other disc may be changed in order to compensate for difierent distances of the subject from the machine. This is accomplished by'providing a universal joint 30in the drive shaft of disc 17 and then providing a pivot bearing 31 which may be adjustable to rightor left by means of an adjusting screw 32 which is connected to this bearing. In this way the portion 33 of the drive shaft for the disc 17 may be moved to the right or left to change the angle of the disc relative to disc 14.

This apparatus, it will be clearly apparent, is equally effective for indoor and outdoor transmitting, and in case of outdoor transmitting, it is possible to collect by means of a proper lens the light from the sun so as to concentrate the light from such a source and utilize this instead of the artificial light source shown in Fig. 1.

The illuminating device which is preferably fixed upon a portable platform may then be adjusted at the proper distance from the subject, and the scanning device then focused by means of the adjusting screw 32 upon the subject so as to properly align with the illuminating device. With the scanning discs then in synchronism with the disc 14, the machine may be operated and. the result will be to illuminate the subject by the beams of lightpassing horizontallyacross the subject for each aperture in the scanning disc while the next aperture on the scanning disc 14 will illuminate another section of the subject above or below the first line illuminated by passing a beam of light across it. I v V Simultaneously with this, the photo-electric cell Will be exposed to the light reflected from the surface of the subject being illuminated or at least a portion thereof, and this will, of course, cause energies of various intensitiesto be transferredby the photo-electric cell circuit depending upon the light reflected upon the surface.

I find that'wi th this device it is possible toob tain a sufficient degree of illumination without injury to the subject, to transmit clear images of subjects situated a distanceofthirty feet from the scanning device, and of a size commensurate with a size of a group upon an. ordinary theatre stage.

Referring now to the means for utilizing a plurality of scanning units each constructed as above described, this means isillustrated in'Figure 7 of the drawings, in whichA indicates one scanning unit and B represents a duplicate of the same, spaced laterally from the first unit and arranged ,at substantiallythe same distance from the stage or area to be scanned, indicated at 10a. The two units are focused upon the subject so that the limits of their respectivefields coincide at adjacent sides. The units A and B have preamplifiers 20a and 201), respectively, connected in parallel to a common amplifier 200, through conductors 40 and 41 leading to a common con ductor 42, and otherconductors 43 and 44 leading to a switch or commutating device 45. Said commutating device comprises a rotating arm 46 driven by a suitable synchronous motor 46a adapted to consecutively engage arcuate commutating poles 4'7 and 48 which are respectively connected to the scanning units A and B by con- ,vided with a corresponding number of commutating poles. v v Figures 4 and 8 show an arrangement for securing synchronism between all of the discs in- .volved. At the end of each disc shaft is fastened a cam 50 which causes contact to be made with a spring switch 51 every time its respective disc revolves.

The switches and cams are all connected in series with an indicating lamp 52 and a suitable source of potential to operate the lamp. If syn- .chronism is secured, it will be indicated by fiashing of the lamp, but if'any" oneof the discs are f out of step, the lamp .will remain unlighted.

Isochrism is easily securedby using synchronous motors of standard construction to drive the discs. The operation of the multiple scanning device above described is as follows: The pre-amplifiers 20a and 20b of the two scanning units A and B,

will be alternately, or successively, connected to the amplifier 200 as the arm 46 of .commutator 45 revolves. The result is that while the scanning I and illuminating beams of both units are simultaneously scanning the subject, only the output from one of them is impressed upon the amplifier 200 at any instant. r I

It will be understood that in order to give the illusion of motion, the total time required for scanning units in use to sweep the entire stage or scene, should be identical with the time required for the eye to retain the impression. Thus, if sixteen pictures are required to be transmitted each second to give the illusion of motion, then when two scanning units are used, each one must transmit thirty-two pictures a second sothat the time required for both units to scan the scene will be 'of a second. 7

The output of the amplifier 200 is connected to a modulator and thence to an oscillator to be transmitted in the usual manner to a suitable receiving apparatus such as that disclosed inmy co'-pending application bearingSerial No. 489,513 and filed October 18, 1930, which apparatus, of course, will be provided with a suitable commutating device operating synchronously with. the

switch 45 for reconstructing the received image in successive portions. l V 1 It will now be understood thatwith a plurality of scanning units coupled as described, the received composite image will be produced with many more scanning lines, and therefore'witli much greater perfection of detail than is possible when a single scanning unit is employed.

Although I have, shown and described certain embodiments of my invention, it willbe understood that I do not-wish to be limited to the exact construction shown and described, but that various changes and modifications may be made without departing from the spirit and scope of my invention.

of motion throughout thecomposite subject when.

transmitted and received.

2. In a television'transmitting apparatus, a plurality of separate scanning devices eachcomprising a scanning member, driving means there-' for, and a photosensitive element, and arranged to cover a plurality of points in different areas of a subject, an amplifier, and a commutator for successively connecting said scanning devices with said amplifier at speeds sufiicient to give the illusion of motion throughout the composite subject when transmittedand received. p

3. In a television transmitting apparatus, a

plurality of separate scanning devices eachcomprising 'a scanning member, driving means therefor, and a photosensitive element, and arranged side by side-relative to the subject to cover a plurality of points in, different areas thereof, an

amplifier, and means for successively connecting said scanning devices with said amplifier at speeds sufficient to give the illusion of motion throughout the composite subject when transmitted and received.

GILBERT T. SCHMIDLING.

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