US 1776298 A
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Description (OCR text may contain errors)
Sept 23, 1930- R. w. STRANGE 1,776,298
ART OF TELEVISION Filed Jan. l2, 1929 2 Sheets-Sheet l Sept. 23, 1930. R. w.-sTRANG|-:
ART OF TELEVISION 43 Sheets-Sheet 2 .Fled Jan. l2, 1929 Patented Sept. 23, 1930 UNITED STATES PATENT OFFICE ART F TELEVISION Application led January 12, 1929, SerialilNo. 832,222, and in Australia Ianuary 25, 1928.
This invention relates to television and particularly to methods and apparatus whereby visions of a number of subjects may be simultaneously transmitted and reproduced, and
the process of synchronizing the transmitting and receiving devices is slmplified.
According to a known method of television which has proved successful, a beam of light from. an arc lamp or other light source is projected through a spirally arranged series of .perforations in a disc rotating about avhorizontal axis, onto the subject a vision ofwhich is to be transmitted. The subject is thus scanned or swept by rapidly movin rays of light and the reflections thereof in uence one or more conveniently placed photo-electric cells which transform the light impulses into minute electric currents or what may be termed image currents.
lines to a receiving station where the transmitted impulses may be picked up by a receiving instrument and, after amplification,
passed to a neon glow tube placed behind a second perforated disc which is identical in proportions with the disc at the transmitting station and requires to be driven in erfect synchronism with the first disc. observer at the receiving station, by looking through an apertured mask or lens disposed in front of the second rotating disc sees the rapidly moving jets or rays of light from the neon tube as they Hash through the perforations of the second rotating disc, whereby the image or vision of the subject is reconstructed.
Vhere fsuch an arrangement as the -foregoing is used there are certain disabilities and limitations which are a. hindrance to the commercial employment of the' apparatus. For instance, perfect synchronization between the two discs at the transmitting and reeeiving stations is essential.` This means not only that the discs must rotate at exactly the same speed but also that the perforatlons in the respective discs must be in the same relative positions at any given instant throughout operations. Such synchronization has been obtained, for instance, by em# These image currents are then am-` plified and transmitted by radio or by landploying one or more synchronous motors at the transmitting and receiving stations, the motors being maintained in step by currents or impulses controlled by apparatus at the i transmitting station. Whilst synchronization of rotating discs is obtainable by this and other methods, complete tuning in may prove a lengthy and a diicult operation because of the necessity of bringing the perforations of the discs into the same relative positions. In practice this latter process is usually achieved by mere guess-work, the motor or motors operating the receiver being started or stopped or varied in speed until the reproduced image or vision is correctly formed.
Another limitation of such apparatus is that, owing tothe vertical attitude of the discs, if the subject is disposed at any position other than in alignment with the perforations at the top portion or arc of the transmitting disc, the image received by the receiving disc may be either askew, lying on'one side, or upside down. Moreover, such apparatus is limited to the transmission of a single 5 image or vision at any particular period and such image may be conveniently viewed -by only one person.
One of the objects of the present invention is to provide improvements in television systems and apparatus of the eneral nature indicated whereby synchronization of perforated scanning bands or rings at the transmitting and receiving stations may be accomplished with greater ease than at present.
Further obj ects of the invention are to provide improved television apparatus which permits of a plurality of different images or visions to be transmitted simultaneously from a single transmitter, to enable a single receiver to receive simultaneously a plurality of different images which may emanate from one and the same transmitting station or from several stations operating on different Wave lengths, and to provide a simple and effective television apparatus which may be of comparatively large scale or capacity and which is capable of being satisfactorily used upon a commercial basis.
Irl-accordance with my invention I prefer 0* to employ perforated endless bands adapted to travel in a horizontal'plane, or perforated annular members which are rotated about vertical axes, although, in some instances, such bands or annular members may travel or be rotated in other attitudes. My invention may, however, also be applied to television means employing discs or the like.
Referring to the drawings which form part of this specicationz- Figure 1 is a plan view of one form of scanning mechanism suitable for simultaneously transmitting a plurality of Visions, wherein the scanning member is of annular' form and adapted to be rotated about a vertical axis.
Figure 2 is a part sectional side view of Figure 1.
Figure 3 is a plan View of another form of scanning mechanism wherein the scanning member consists of a flexible endless band adapted to travel horizontally around guide pulleys.
Figure Il is a front view of the band and certain associated parts of Figure'3.
Figure 5 is a flat or developed view of a scanning member of a transmitter showing the perforations in accordance with the invention.
Figure 6 is a fiat or developed view of a scanning member of a receiver showing a double row of perforations.
Figure 7 is a part sectional elevation of a receiver, in accordance with the invention, particularly suitable for use in conjunction with a transmitter as in Figures 1 and 2.
Figure 8 is a fragmentary elevation of the device seen in Figure 7 indicating the manner of masking the Visions reconstructed by the receiver.
Figure 9 is a plan of Figure 7, a cover of the receiver beine removed.
Figure 10 is a fi'agmentary elevation showing an adjustable mask suitable for use with a receiver according to this invention.
Figure 11 is a vertical section of the mask and associated parts in a plane at right angles to that of Figure 10.
Figure 12 is a fragmentary section illustrating a modified form of receiver according to the invention.
The scanning members, which are preferably of annular or endless formation, may be composed of metal, Celluloid, fabric, paper,
or other suitable material and the scanning member 2 of the transmitter is provided with a line or row of equally spaced holes 3 which are arranged spirally or inclined in relation to the circumference or the length of the ring or endless band.
The circumferential or longitudinal distance between adjacent perforations 3 represents the width of the vision to be transmitted, and/the height of the vision conforms approximately to the vertical distance between the around pulleys or wheels 13, 13a.
first and last holes of the series. The number and size of the perforations is' governed by the amount of detail required in the resultant vision. A large number of perforations provides the greatest amount of detail while a smaller number of perforations provides a relatively greater light intensity but less detail. The perforations 3 may be of any suitable shape but square or rectangular holes are preferred.
According to Figures 1 and 2 the scanning member of the transmitter comprises a circular band or ring 2 which pstands from the periph-ery of a disc 4 adapted to be rotated about a vertical spindle o-r axis 6. An electric motor 7 may be provided to rotate the disc and the band at a suitable speed, for instance upwards of ten revolutions per second if the band 2 has a single line of perforations 3 as shown, orpropo-rtionally slower if the band has a plurality of lines of perforations. The motor may be equipped with suitable speed controlling means.
Arc lamps, electric lamps 8 or other sources of light may be disposed within the confines of the band 2, as indicated in Figures 1 and 2 and in the left hand portion of Figure 3, and adapted to project their beams either directly, or by the aid of suitable lenses 9 or the like, onto the inner surface of the band, whereby the light passes through the perforations 3 as the band rotates and onto the subjects indicated at 10. Suitable masks l1, may be fitted between the lamps 8 and the band 2, or outside of the band, to ensure that light from one lamp can pass through only one perforation 3 onto the subject of any one time. Additional lenses 9a, prisms, or reflectors may -be disposed outside the band as indicated in Figure 1 in order to change the direction of the light rays passing therethrough. It will be understoodthat further lamps 8 and associated components may be placed around and within the band 2 (Figures 1 and 2) and that light proof screens 12 may be provided to isolate light rays in the various compartments formed by the screens. If desired a stationary' cover or casing may extend over the band and serve as a mounting for the lamps 8, lenses 9, masks 11 and screens 12.
Another form of transmitter in which the perforated scanning member consists of a flexible band 2a is shown in Figures 3 and 4 wherein the band, with perforations 3 as hereinbefore described, passes horizontally Motion may be imparted to the band from an electric motor through the vertical spindle 14 and the wheel 13a which may drive the band either by friction or by the aid of teeth 16 adapted to engage in apertures 17 formed along one or both edges of the band in a manner similar to those of a cinematograph film. The. band 2n may be protected from conveniently arranged relatively to each subject 10 so as to be infiuenced by the reiections of the rays of light projected through the band 2, 2, and onto the'subject. rihe minute impulses or image currents generated by the photo-electrical cells or the like are amplified, for instance by vacuum tubes, and may then be broadcast by a radio transmitting instrument or passed along land lines or otherl communication channels.
In another form of the invention suitable for the transmission of visions of subjects directly illuminated by daylight or by art-ificial light, one or more photo-electric cells '21 may be placedV within the confines of the scanning band` and in close juxtaposition to it as shown in the 'right hand portion of Figure 3. By means of lenses 9b,'prisms, reflectors or the like, an image of the subject to be transmitted is projected through the perforations of the bandonto the active surface of the photo-electric cell 21 or other light responsive means. The varying currents flowing in the cell may be amplified and then tr'ansinittedas beforementioned.
lVith any of the above methods, I may interpose between the source of light and the band 9 a rotary member or disc 23, as shown in Figures 3 and 4, provided with holes or slots 24, for the purpose of interrupting the light passing throughthe perforations 3a of scanning member 2a and thereby producing fluctuating or alternating currents which are particularly suitable for subsequent amplilication and transmission.
It will be evident that owing to the use of an endless or annular scanning member with spirall)v arranged perforations a plurality of different images or visions may be simultaneously sent out from one transmitting station. The various subjects would preferably be situated at convenient positions in screened enclosures into which the light flashes from the respective light sources are projected, or, in the case of subjects illuminated by daylight or artificial light, the apparatus may be enclosed in a light tight casing as indicated at 18 in Figure 3.
Apparatus constructed in with the invention may be used in association with any radio or broadcasting station or land line network in which case the output of the amplifier used in connection with theendless scanning members may be substituted for the out-put of the usual microphone or other sound sensitive device asaccordance sociated with the ordinary modulation ampliier of the radio transmitter or land line network. The modulationcurrents as emitted from such a transmitter may be picked up by any suitable radio receivers, and, after amplification, adapted to control or influence any variable light source such, for instance, as neon tubes 25 disposed lwithin a perforated scanning band or like member of the receiver (Figures 6 to 12). This endless band or ring 2b of the receiver is provided with a pair (or pairs) of rows ,of lines of perforations 3" (Figure 6) spaced similarly to those of the transmitting band l2, 2a, so that in the case of a circular receiving band there will be two (or more) spiral rows of perforations 3b, the distance between the rows being equal to the height of the vision to be reconstructed. The purpose of this duplication of rows of perforations is to aid synchronization as will be hereinafter explained.
As seen in Figures 7 and 8 a scanning band 2b of the receiver may be of circular form and upstand from the periphery of a disc 4b which may be rotated about avertical spindle 6h by an electric'motor 7b. If employed in conjunction with a transmitter having a flexible band, as in Figures 3 and 4, the band 2b may be similarly supported and traversed.
The bands or the like 2" and apparatus associated therewith may be protected from external light b a suitable stationary casing 26 which may e fitted with internal light proof screens 27 as may be necessary to isolate light rays in the various compartments formed by the screens.
In front of each light source 25 of the receiver there may, if desired, be a translucent screen 28 upon which the transmitted image is reconstructed, this screen being located behind a viewing aperture 28a in the caslng 26.
In some forms ofthe invention, the receiver may be provided with viewing apertures in pairs in which cases the light sources 25 are also duplicated. This permits of two reconstructed pictures being concurrently viewed, either directly or stereoscopically as in viewing a subject with binocular field glasses, thereby increasing the intensity of illumination. The reconstructed images may, if desired, be viewed through magnifying lenses.
Upon tuning in to a transmitting station,
and assuming that the endless scanning bands or rings at the transmitting and receiving stations are maintained at the same speed by any suitable means, which means does not form part of this invention, it still becomes necessary to adjust the apparatus so that the relative positions of the perforations in the bands are identical. Otherwise, the components of the transmitted vision allll) fill
though completely reconstructed, would be incorrectly disposed upon the screen, that is to say, the top and bottom, or left and right hand portions of the image may be transposed. According to the invention, this defeet may be speedily and easily overcome by manipulating a viewing mask 31, having an aperture 32, over the band 2". The masking adjustment may be readily understood by reference to Figures 10 and 11, wherein it is assumed that the neon lamp 25 has a plate which becomes illuminated over its whole surface to a greater or lesser intensity with each impulse received from the transmitting station. The neon lamp plate may illuminate an area on the receiving band 2b corresponding to the total area of four complet-e reconstructed images indicated by I, II, IIl and IV, in Figure 10. Providing that the band 2b of the receiver is maintained at the same speed as the band of the transmitter, the correct image synchronizing point may readily be found by adjusting the mask 31, either or both horizontally and vertically, to bring the aperture 32 into any desired position within the compass hereinbe'fore stated. If the top and bottom portions of the received vision are out of place this may be corrected by moving the mask vertically, and if the left and right portions are incorrectly placed in the reproduced vision the latter may be corrected by lateral movement of the mask. The aperture 32 in the mask 31 permits the observation or passage of light from one perforation 3b at any one time.
According to one arrangement illustrated in Figures 10 and 11 the mask 31 is adjusted vertically by means of a screw 33 which is rotatable within a lug 34 on the mask and passes vertically through a screw threaded aperture in a bloc-k 36 which may be adjusted horizontally (so as to carry the mask 31 and screw 33 with it) along a guide member 37 fixed to a stationary part above the band, such for instance as the top of the casing 26. It will be evident that the mask may be speedily and easily adjusted to bring its aperture 32 into registry with any of the areas marked I, II, III or IV or into any position intermediately thereof as indicated,
If desired, the luminous plate of each neon lamp 25 may have an area equivalent only to the mask aperture 32, but in this case it is necessary that the mask be operatively conlucent screen 41 which may be fitted with a viewing mask. The reflector may be pivotally mounted and have screw or other adjusting means 42 associated therewith.
It will be evident that, in accordance with the invention, a large number of neon lamps or like devices may be arranged at intervals completely around the scanning band of the receiver and have associated masks 31 or the like and other elements so that a plurality of visions emanating from the same or different transmitting stations may be simultaneously reconstructed and viewed at one receiving station.
According to a modification which is applicable to a transmitter or a receiver the perforations 3, 3a, 3b in the endless bands or rings 2, 2a, 2b may be covered by a strip of relatively thin translucent or semi-transparent material, such, for instance, as tissue paper, upon which the images may be projected. In the case of a receiver the translucent or semi-transparent screen so formed will take the place of the screens indicated at 28 in Figures 7 and 9, and at 41 in Figure 12.
Itl is to be understood that the invention as herein described and as illustrated in the drawings is susceptible to various modifications, alterations and/or additions without departing from the nature spirit and scope of the invention defined by the appended claims.
Having now described my invention, what I claim as new and desire to secure by Letters Patent is:
1. A television system including a transmitter comprising a perforated scanning member, a plurality of light responsive devices to be influenced by the reflections of light rays illuminating a subject to thereby create image currents in said light responsive devices, and a receiver comprising a scanning member provided with a plurality of rows of perforations, devices in the receiver for transforming said image currents into light values to be directed through said perforations, and means for blocking out the unwanted images.
2. A television system comprising a transmitter including a perforated scanning member and a plurality of light responsive devices to be influenced by the reflection of light rays controlled by the scanning member, whereby to create image currents in said light responsive devices, and a receiver comprising a scanning member provided with a plurality of rows of perforations, means for transforming the image currents into light values so that a plurality of images will be reconstructed through said rows of perforations at each viewing point of the receiver, and means for masking the unwanted images, said means being adjustable with respect to the perforations of the receiver scanning member.
3. In a television system, a transmitter for transmitting image currents of a subject, a receiver arranged to reproduce a plurality of images or portions of an image of each subject from said image currents, and means for. blocking out the unwanted images or portions o the images reproduced -in the receiver.
4. In a television system, a transmitter comprising a scanning band formed with per forations; means for traversing said band in a horizontal plane, inde endent light responsive devices influenced y the reflections of light rays illuminating a subject, said light responsive devices creating separate image currents for independent transmission, a receiver including a scanning member formed with rows of perforations and adapted for traverse in a horizontal plane, and means cooperating with the band of the receiver for transforming the image currents into light values to reconstruct a lurality of images at each viewing point o the receiver.
5. In a television system, a transmitter comprising a scanning band formed with perforations, means for traversing said band in a horizontal pla-ne, independent light responsive devices influenced by the reflections n of light rays illuminating a subject, said light responsive devices creating separate image currents for independent transmissiom' a receiver including a scanning member formed with rows of perforations and adapted for traverse in a horizontal plane, means cooperating with the band of the receiver for transforming the image currents into light values to reconstruct a plurality of images at each viewing point of the receiver, and a manually controllable mask associated with each light responsive device.
In testimony whereof I aiiX my signature.
ROBERT W. STRANGE.