US1725710A - System and method obi television - Google Patents

Description

Aug. 20, 1929. J. H. HAMMOND, JR

SYSTEM AND METHOD OF TELEVISION Filed Aug. 15. 1923 10 Sheets-Sheet l INVENTOR ATTORNEY Aug. 20, 17929. J. H. HAMMOND, JR 71,725,710

SYSTEM AND METHOD OF TELEVISION Filed Aug. 15

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SYSTEM AND METHOD OF TELEVISION Filed Aug. 15 1923 10 Sheets-Sheet 4 mNN n3 RE @3 MQN INVENTOR Aug. 26 1929 .1. H. HAMMOND, JR

SYSTEM AND METHOD OF TELEVISION Filed Aug. 15, 1923 10 Sheets-Sheet 5 INVENTOR 1 I. BY

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SYSTEM AND METHOD OF TELEVISION Filed Aug. 15-, 1925 10 Sheets-Sheet 6 RM RM Cr Aug. 20, 1929. J. H. HAMMOND. JR

SYSTEM AND METHOD OF TELEVISION Filed Aug. 15, 1923 10 Sheets-Sheet 7 INVENTOR is PTTORNEY Aug. 20, 1929- J. H. HAMMOND, JR

SYSTEM AND METHOD OF TELEVISION Filed Aug. 15 1923 10 Sheets-Sheet 8 INVENTOR g- 1929- J. H. HAMMOND, JR 1,725,710

SYSTEM AND METHOD OF TELEVISION Filed Aug. 15, 1923 1o Sheets-Sheet 9 INVENTOR H15 ATTORNEY Aug. 20, 1929. J. H. HAMMOND, JR

SYSTEM AND METHOD OF TELEVISION Fil A gl5, 1923 10 Sheets-Sheet 10 a NQ ATTORNEY Patented Aug. 20, 1929.

JOHN HAYS HAMMOND, JR, OF GLOUCESTER, MASSACHUSETTS.

SYSTEM AND METHOD OF TELEVISION.

Application filed August 15, 1923. Serial No. 657,502.

This invention relates to systems and methods for the transmission and reception by means of electricity, magnetism or electromagnetic waves, variations or impulses of pictures, photographs, mages, reflectlons, shadows, patterns or the like, either in black and white or in natural colors. For convenience in nomenclature these systems and methods. may be referred to here1nafter as systems and methods of televlslon. The energy transmitted from the sending station to the receiving station may be conveyed or guided by wires, or may be transmltted through the other radiantly Some of theobjects of th1s inventlon are to provide an improved system of televlsion; to provide an improved method of television; to provide in a system of'television an improved transmitting system and a corresponding receiving system; to PIOVIdG a svstem of television including a transmlssion system and a receiving system controlled thereby through the natural medium as, for instance, by radiant energy; to provide a system and method of televislon whereby an image of a movlng ob ect at the transmitting station may be produced at the receiving station in the form of a moving picture; to provide a system and method of television whereby an image of an object at the transmitting station may be produced at the receiving station in the natural colors of the object; to provide a system and method of television whereby a plurality of overlapping images of an object; as viewed from different points at the transmitting statlon may be produced at the receiving station in the natural colors of the object, and may be viewed by an observer at the receiving station to produce a stereoptic image of: the object in the natural colors of the 0131601); and to provide other improvements, as will appear hereafter.

In the accompanying drawings all of the figures are diagrammatic representations of systems or parts of systems constructed in accordance with this invention or are diagrams explanatory of the operation thereof.

Figure 1 shows a sending station; Flg. 2 a receiving station arranged to co-operate with the sending station of Fig. 1; Fig. 3 a modified wave form emitted by the sending station of Fig. 1; Fig. 4 a path of a beam of light during the operationof the sending station of Fig. 1; Fig. 5 a modified form of operation of the sending station of .Fig. 1, arranged to control the path of the beam of lightin a manner different from that of Fig. 1; Fig. 6 the wave form emitted by the modified transmitter shown in Fig. 5; Fig. 7 the path of the beam of light during operation of the system of Fig. 5; Fig. 8 a modified form of operation of the sending station of Fig. 1 arranged to control the path of the beam of light byrotating mirrors or the like; Fig. 9 the path of the beam of light in operation of the modified form shown in Fig. 8; Fig. l0 a modified form of the sending station of Fig. 1 arranged to limit the amount of light effective to control the emitted energy; Fig. 11 another modifiedfliorm of the sendingstation arranged to control the emitted energy according to the light reflected from the parts of the image suecessively; Fig. 12 a modified form of receiving apparatus employing cathode rays; Fig. 13 a modified form of sending station for use in transmitting pictures in colors and for reproducing stereoscopic images; Fig. 14 an enlarged front elevation of a detail of Fig. 13; Fig. 15 1is a modification of Fig. 13; Fig. 15 a receiving station arranged to co-operate with either the sending station of Fig. 13 or 15 Figs. 16 and 17 represent respectively a radio transmitting system and a corresponding radio receiving system *which may be substituted for the wire connections between the transmitting system of Fig. 1 and the receiving-system of Fig. 2; Fig. 18 shows a modification of the transmitting system of Fig. 1; Fig. 19

a front elevation of a detail of Fig. 18; Fig. 20 a diagram partly broken away of a modified form of light producing and varying system; and Fig. 21 a diagram of a system for increasing the visibility of an object.

Referring to the accompanying drawings, and particularly to Figure 1, one embodiment of this invention comprisesa light producing system 10 for producing'a beam of light; a vibrating system 11 for causing the beam of light produced by the system 10 to travel in certain predetermined paths; an electric generating system 12 for producing suitable electrical harmonics to operate the vibrating system 11; a photo electric system 13 for receiving the light reflected from an object 14; an electrical amplifyingsystom 15 controlled by the photo electric systom 13; and a carrier wave generating system 16 arranged to: be controlledby the amplifying system 15.

The light producing system consists of a. suitable source of light such as: a projector lamp 20 which receives its current from a local battery 21. The light from the lamp 20' and also that reflected from a concave mirror 22 passes: through a suitable optical system such as: a series of lenses 23, 24 which concentrate the beam of light: and project it as a parallel beam 25. The central portion of this beam passes through a small opening in a diaphragm 26 thus producing a very small pencil or beam of intense light 27.

The vibrating system 11 consists: of two small mirrors 36 and 31 mounted for rotation in a vertical and horizontal axis respectively. These mirrors are secured to the vibrating elements of suitable galvanometers, the coils of which are. shownat 32 and 33'respectively. The coils: 32 and 33 oscillate between poles of permanent magnets 34 and 35. The current to the: coil 32 is lead in by suitable conductors and 41 which are connected to terminals 42; and 43. The current to the coil is lead in by conductors 44 and 45 which are connected to terminals 46 and 47. The mirrors 30 and 31 and all hereinafter mentioned mirrors are very small in area and very light in weight and are preferably made of very thin sheet metal having one side highly polished to form an efiicient reflecting surface. These mirrors may be circular in outline or of any other suitable shape.

The beam of light is reflected from the mirror 30 to the mirror 31 and thence on to the object 14 a picture or image of which is to be transmitted to the distant receiving station.

The electric generating system 12 consists of a high frequency alternator 50 of approximately 3200 cycles per second. The field 51 of this alternator is energized from a. low frequency alternator 52 of about 16 cycles per second. The alternator 50' is connected by means of transformer 54 to a circuit 55 which is: connected. to the terminals 42, 43, 46 and 47 and also: to conductors 56 and 57 which are in turn connected to a filter 58. This filter 58 is constructed and arranged to let pass only currents having frequencies within the band of frequencies produced in v the circuit 55 of the alternator 50 as acted upon by the alternator 52. This filter 58 prevents short circuiting of the amplifier 15 and generator 16 through the circuit of the vibrating system 11. This filter 5'8 and all other filters hereinafter described should be aperiodic with no difference of time lag for different frequencies.

The photo electric system 13 comprises a lens system 60, 61, a photo-electric cell 62 of any suitable construction, and a battery 63 in circuit in series with the cell 62. The

photo-electric system 13 may be of any suitable construction, and in the form shown is of the multiple stage resistance coupled type employing several three element thermionic amplifiers 64. The output circuit of this amplifier 15 is connected to the central terminals of a double pole, double throw switch 65 one side of which is connected to the carrier wave generating system 16 and, the other side of which is connected to the input side of an electrical filter 66. This filter 66 is constructed and arranged to let pass only currents having frequencies within the band of frequencies produced by the amplifying system 15 under the control of the photoelectric cell 62 while acted upon by the light received from the object 14 through the lens system 13. 1

The carrier Wave generating system 16 may be of any suitable type and in the form shown employs a three elementg thermionicoscillator 67, and a three terminal thermionic modulator 68 controlled thereby and which is provided with an output circuit.

leading into the input side of a suitable filter 69. The filter 69 is constructed and arranged to let pass only currents having frequencies within the band of frequencies produced by the carrier wave generating system as modulated by the output of the amplifier system 15 under the control of the photoelectric cell 62.

The output sides of the filters 66 and 69 are connected respectively to the two opposite sides of a double pole, double throw switch 70, the central terminals of which are connected to the transmission line 71 by means of conductors 72 and 7 3. The transmission line 71 consists of two conductors 7 4 and 75 which are connected at their inner ends to the output side of the filter 58, and at their outer ends to a suitable receiver such for instance as is shown in Fig. 2, either directly as for Wire transmission, or indirectly as through suitable radio transmitting and receiving apparatus, as shown for instance in Figs. 16 and 17.

Referring to Fig. 2, one form of receiving apparatus which may be employed to cooperate with the form of transmitter shown in Fig. 1, comprises an amplifier detector system 81 for receiving, detecting and amplifying the modulated current from the transmitter; an amplifying system 82 for screen 86 for receiving the images sent from the transmitter.

At the receiving station the transmission line 71 from the sending station is connected by conductors90 and 91 to the centre of a double pole, double throw switch 92, one side of which is connected to a filter 93 and the other side of which is connected to another filter 94. The filter 93 is constructed and arranged to let pass only currents of frequencies which are permitted to through the filter 69 of Fig. '1 and the filter 94 is constructed and arranged tolet pass only currents of frequencies which are per mitted to pass through the filter 66 of Fig. 1. The output sideof the filter 93 is connected to the input side of the amplifier detector system 81, .and the output side of the filter 94 is connected to the input side of the amplifying system 82. The output side of the amplifier detector system 81 is connected to one side of a double pole double throw switch 95, and the output side of the amplifying system 82 is connected to the other side of the same switch 95. The am.- plifier detector system 81 may be of any well known or suitable construction, and as shown comprises several three element thermionic bulbs 96 of well known construction, resistance coupled and arranged in series. The first bulb 96 on the left is adjusted to act as a detector and also as an amplifier and the next two bulbs 96, 96 are adjusted to act as amplifiers of the current which results from the detection by the first bulb.

The amplifying system 82 may be of any wellknown or suitable construction and in the form shown is of the multiple stage resistance coupled type emplo ing three element thermionic amplifiers 9 The light producing system-83 is essentially similar to that shown in Fig. 1 at 10, and consists of a source of illumination 100, a lens system 101, 101 and a diaphragm 102, which produces a pencil of intense light 103.

' The light varying system 84 comprises a Nicol prism 105, a polarization cell 106, a Nicol prism 107 and a lens system 108. The polarization cell 106 is surrounded by a coil 109 which .is connected by conductors 110 and 111 to the central terminals respectively of the switch 95. These parts are so arranged that the pencil of intense light 103 passes from this diaphragm 102 through the Nicol prism 105 and then through the polarization cell 106. The light beam 103 after emerging from the polarization cell 106 passes through the second Nicol prism 107 which is crossed with respect ,to the first Nicol prism 105. The lens system 108 is pass provided for concentrating the beam 103 in case the same has been somewhat difi'used in passing through the prisms and polarization cell.

two mirrors 115 and 116. These are mounted respectively upon the movable elements or coils of two suitable galvanometcrs comprising respectively permanent magnets 117 and 118, the first mirror 115 is mounted for rotation about a vertical axis so as to receive the beam of light 103 from the lenses 108, and the second mirror 116 is mounted for rotation about a horizontal axis so as to receive the beam of light as reflected from the first mirror 115 and to reflect the same against a suitable screen 86 provided therefor. The vibrating system 85 is similar to that shown at 11 in Figure 1. The current is led into the movable element of the gal- 8 vanometcr 117 by means of conductors 120 and 121 which are connected respectively to terminals 122 and 123, and the current is led into the movable element of galvahometer 118 by means of conductors 125 and 126 which are connected respectively to terminals 127 and 128. The conductor 74 of the transmission line 71 is connected to the terminal '127 and the conductor is connected to the terminal 123. The terminals 122 and 128 are connected together by a conductor 130. A filter 131, similar to filter 58, is inserted in the transmission line 71 and is arranged to let pass only currents of frequencies passed by filter 58.

In the form of the invention shown in Figures 1 and 2, the freqeuncy of the alter- The light vibrating system comprises nator 50 is approximately 3200 cycles per second, and the amplitude of the current generated will depend upon the intensity of the field 51.

In Fig. 1 the vibrating element 32 is tuned so that its natural period is above that of the current produced by the alternator 50 and this vibrating element is thereby caused to vibrate 45 degrees out of phase with the current; and the vibrating element 33 is tuned-s0 that its natural period is below that of the current produced by alternator 50 and this vibrating element 33 is thereby caused to vibrate 45 degrees out of phase with the current'in the other direction, with the result that the two mirrors 30 and 31 will vibrate at the frequency of the alternator 50 but with a 90 degree phase relation to each other.

When the beam of light 27 is reflected from the mirror 30 it will be given a vibratory motion ina horizontal plane and when it is reflected from the mirror 31 there will be a vibratory motion in a vertical plane superimposed upon the former vibration. If the amplitude of the purrent produced by the generator 50 were constant the amplitude of vibration of the two mirrors 80 and 31 would also be constant and the beam of light 27 as it leaves the mirror 31 would have a circular motion. Butthe field 51 of the alternator 50 is energized. by the second alternator 52 so that the amplitude of the current produced by the alternator 50 is varied in a manner shown in Figure 3, Where the curve of this current is indicated by the line 135 and the envelope of these curves by the line 136. This will cause the amplitude of vibration of the mirrors to vary so that the beam of light 27 when it leaves the mirror 31 will describe a spiral path as shown in Figure 4. This spiral will always be made in the same direction, for example, as indicated by the arrows in Figure 4:, and will start from a central point moving outward in a left hand spiral and will return to the central point over a similar right hand spiral. This spiral will not be reentrant but will always be formed by the point of light moving over the object with the same direction of rotation.

As the frequency of vibration of the mirrors 30 and 31 is constant the rate of rotas tion of the point of light forming the spiral will also be constant andin order'to have the intensity of illumination of the object uniform the spacing of the spiral must decrease at a rate proportional to the increase of radius, as the linear speed of the point oflight increases directly as the radius. This can be accomplished by making the wave form of the current produced by the generator 50 and shown by the current line 135 (Fig. 3) of such a shape that its envelope 136 will have a parabolic form.

The point of light traversing the spiral path will pass consecutively over substantially every point of an object'whose dimensions do not exceed those of the limits of the spiral, the time taken in passing over each complete spiral out and back being 1/16 of a second when the speed of the alternator 52 is sixteen cycles per second.

The light reflected from each point of the object as the point of light strikes it will be focused by the lens system 13 on the photo electric cell 62, thereby varying the resistance of this cell accordingly thus producing corresponding variations in the current sup- .plied by the battery 63 to the amplifying system 15 which, depending upon the position of the switches 65 and 70, cithera sends these amplified variations of current through the filter 66 to the line 71, or else causes them to modulate the highfrequency waves produced by the carrier wave generating system 16 which are then sent through the filter 69 to the line 71. The alternating current produced by the generating system 12 passes through the filter 58 and then on to the line 71- v.

In the operation of the sending' stationv line .wire 71 and filter 94, amplifier system I '82, and coil 109 of Fig. 2. a

But it it shouldbe desired to transmit from the sending station the comparatively high frequency current generated by the carricr wave producing system 16 and modulated by the output current of the amplifier system 15, then the switches 65 and 70 of Fig. 1 and 92 of Fig. 2 should be so set as to place in series the amplifier system 15, the carrier wave generator 16, and the filter- 69 of Fig. 1, the line Wire 71, and the filter 93, amplifier detector system 81, and 'coil 109 of Fig. 2. When it is-desired to transmit energy by wire from the sending station of Fig. 1 to the receiving station of Fig. 2 either of the sets of connections just described may be made.

After the current has been received and amplified by either system 81 or 82 of the receiving station, as the case may be, it passes to the switch 95 and thence by means of conductors 110 and 111 to the coil 109, which acts upon the polarization cell 106 so as to cause a rotation of the plane of polarization through an angle depending upon the intensity of thecurrent in the coil 109. This in turn causes a variation of the amount of light passed through the second Nicol prism 107, so that the intensity of the beam 103 after it leaves the prism 107 will be proportional to the intensity of the light received by the photo electrical cell 62.

The beam of light 1031s then reflected by the vibratin mirrors 115 and 116 which are .caused to vibrate in synchronism with the mirrors 30 and 31 at the transmitter, as the coils of the galvanometers 117 and 118 are traversed by the same alternating current which traverses the coils 32 and 33 at the transmitter and which is conducted to the receiver over the conductors 74 and 75. This will cause the point of light produced by the beam 103 on the screen 86 to move over a spiral path similar to that traversed by the beam of light 27 on the object-14.

As the two beams of light 27 and 103 thus move in synchronism and as the beam of light 103 has an intensity proportional to the light reflected fromthe object 14, at any given instant, the screen 86 will be covered by a point of light making a complete spiral 16 times per second, whose intensity at each point will be the intensity of the light refiected from the object 14 at a 'correspond mg point so that-there will be produced 5n the screen 86 an image which will correspond to the object 14; and which will be produced 16 times per second so that thepersistency of vision will cause it to appear as a continuous image depicting the ob ect 14 and which will follow closely all the movements of this object.

In Figure is shown a modified form of the means shown in Fig. 1 for causing the mirrors 30 and 31 to vibrate. In this form of the invention a battery 140 is placed in the circuit with the field 51 and the generator 52. A condenser 141 may also be necessary. forming with the adjacent coil a tuned circuit to take up the irregularities of the 3200 cycle. The wave form of the current generated under these conditions is shown by the line 145 in Figure 6. The envelope of this waveform is shown by the line 146 which is parabolic in shape. With this type of current the pattern formed by the beam of light 27 on the object 14 will be a re-entrant spiral as shown in Figure 7. The spiral will be first formed in one direction as indicated by the arrows 147 and then will retracethis path as indicated by the arrows. 148. A similar spiral will be formed on the screen 86 by the beam of light 103 as the coils of the galva- nometers 117 and 118 will be traversed by the same ourrent that passes through the coils of the galvanometers at the transmitter.

Another form of this invention is shown in Figure 8 in which the pattern is produced by rotating mirrors or similar means instead of by vibrating elements. In this form of the invention the optical system 10 is identical with that described for Figure 1 but in this case the beam 27 is reflected from a plurality of small mirrors 151 secured to the circumference of a circular disk 152 which is mounted upon a shaft 153 which is rotated by an induction motor 154. Secured to the shaft 153 is a worm 155 which meshes with a worm gear 156 which in turn is mounted upon a shaft 157. Secured to the shaft 157 is a second worm 158,.meshing with a worm wheel 159 secured to a shaft 160 which carries a plurality of mirror surfaces 161, which reflect the beam of light 27 receivedfrom the mirrors 151 to the object 14. When the motor 154 is rotated at a high speed the beam of light 27 will be reflected from each of the small mirrors 151 and each time a mirror passes in front of the incident beam the reflected beam will be rotated through a small angle. This beam is then reflected from the surface of the mirrors 1131 which are rotated at a much slower j sfiibed than the mirrors 151 due to the worm rgfduction used. As each vibrating beam strikes the mirror 161 it will be reflected at angle slightly different from the previous one due to the rotation of these mirrors, thus producing a pattern similar to that shown in Figure 9.

The induction motor 154 is connected by three conductors 165, 166 and 167 to a similar induction motor 170 located at the receiver. This motor drives a disk 171 provided with a plurality of small mirrors 172, similar to the disk 152, which in turn, by

means of a worm reduction gearing, drives source of three phase current 180 which drives the two induction motors at the same speed. The two rotating discs 152 and 171 are thereby rotated in synchronism, as are also the mirrors 161 and 175. The pattern formed on the screen 86 is therefore similar to the pattern formed on the object 14, and the beam of light in each case moves over the two patterns synchronously.

The light reflected from the object 14 of Fig. 8 may be received or picked up by a sending system exactly the same in construction and operation as that part of the sending station shown in Fig. 1, which receives the light reflected from the object 14 of Fig. 1, and which includes the lens system 13, cell 62, amplifier system 15, carrier wave generator 16, filters 66, 69, and line wire 71. This part of the sending apparatus of Fig. 1 forms an unshown part of the sending apparatus of Fig. 8 and the. energy transmitted from this unshown part of Fig. 8 may be received upon a receiving system, the same in construction and operation as' that portion of the receiving system of Fig. 2 which controls the coil 109 of Fig. 2, to control the coil 109 of Fig. 8. The image produced on the screen 86 of Fig. 8 will therefore be an image of the object 14 of Fig. 8. a

In order to keep the two motors 154 and 170 in practically absolute synchronism, these motors should be of the induction motor type in order to avoid the hunting characteristic of other types. Any suitable means for synchronizing these motors may be employed.

In the form of the invention shown in Figure 1 the light received by the photo electric cell 62 is comparable to the total i1-. lumination of the object at any given instant. As long as the beam of light 27 strikes a part of the surface approximately normal to its direction, as in the ease of a photograph or other flat object, the light reflected will be only that amount which is reflected directly from the point where the beam strikes the object. If, however, the image of an object which is not flat but which has depressions and other iregularities of surface is to be transmitted, and the beam should strike the object on a slanting portion of the surface thereof, part of the light will be reflected to other portions of the surface thereof so that the total illumination received by the cell 62 would be not only that reflected directly from the point where the beam 27 strikes the object, but also that reflected from those other portions, thus increasing'the illumination received by the cell over that which would be received if only the light reflected directly from the incident point reached the cell. Therefore the system shown in Fig. 1 might operate more efliciently in transmitting images of objects having flat surfaces than in transmitting images 0R objects having irregular surfaces.

To overcome this difficulty and thereby increase the efiiciency of the system shown in Fig. 1 when used to transmit images of objects having irregular surfaces, the systemson with the hereinbefore described primarymirrors 31 and 30. These secondary mirrors 190 and 191 must each be of very small area, and they are mounted at such angles and in such position with respect to the primary mirrors 31 and 30 respectively, that the light reflected by the secondary mirrors will, always be from the point at which the incident beam 27 strikes the object 14 and will always strike the cell 62, which may be rearranged in a new fixed position for this purpose, if necessary. In this modified 4 form of Fig. 1 the lens system 60, 61 may be omitted.

- Figure 11 shows another modification of Fig. 1, 'which'may be found to have certain In this.

advantages for certain purposes. modified form of sending stationsthe construction and. arrangement may be exactly the same as in Fig. 1 except that the system 10 of Fig. 1 for producing the beam of light 27 is omitted; a lamp 200 and suitable reflectors 201 are arranged to illuminate the object 14; and the cell 62 of Fig. 1 is arranged inv Fig. 11 to receive light rays 202 reflected to it by the vibrating system 11 from the object 14. In Fig. 1' the light proceeds from the lamp 20 to the vibrating sys-' tem ll and is iefiected by the vibrating system 11 to the object 14 and by the ob ect 14 to the cell 62, but in Fig. 11 the light proceeds from the lamp 200 to object 14 and isreflected by the object 14 to the vibrating system 11 which, reflects the, same to the cell 62, the process of operation of the reflecting system in Fig. 11 thus being the reverse of the process in Fig. 1. The vibratory mirrors should be .very small in area and very light in weight in all the herein described systems, and this is. particularly important in'the systems of Figs. 10 and 11.

Instead of producing the image by ordinary light rays thrown uponan ordinary screen as in Fig 2,it is possible to modify Fig. 2 so that the image may be produced on a fluorescent screen by means of cathode rays. In this modification the construction and arrangement are the same as in Fig. 2 except that instead of the means 83 for producing a beam of light, the light modifying system 84 including the coil- 109 and connections ll0, 111 the vibrating system 85 and the screen 86, of Fig. 2, there is substituted the construction and arrangement shown in Fig. 12.

In Fig. 12' is shown an elongated hi hly evacuated glass bulb or container 205 w ich is substantially circular in transverse section throu hout its length and which comprises a cy indrical-neck portion and a substantially cylindrical body portion, the body portion being of greater diameter thanthe neck portion. Within the outer end of the neck of the bulb is located a cathode in the form of a filament 206, and in the outer'end of the body of the bulb and in a plane perpendicular to the longitudinal axis of the bulb is located a fluorescent screens207. The filament 206 is heated by a battery 208 working through a variable resistance 209. Within the neck of the bulb 205 and between the filament 206 and the screen 207 are located in the order named an anode 210, a focusing gride 211 and a secondary diaphragm 212.

The anode 210 is in the form of a circular diaphragm provided with a marginal cylindrical tubular extension 215 and with a central cylindrical tubular extension 216 open at both ends. These two extensions are ar- 1 0 ranged coaxially with the bulb 205 and the central extension 216 is open at bothends to permit electrons from the filament 206 -to pass through the anode 210.' The anode 206 th ough a battery 220 of relativel high voltag ,for\ instance of a Voltage 0 from 200 to 1000 volts.

The focusing grid 211 is in the form of an elongated coil having its longitudinal axis coincident with the lon 'tiudinal axis of the bulb 205. One end of this grid is connected through a condenser 225 with one of the central terminals of the switch 95 of Fig. 2, and the other central terminal of the switch 95 is connected through a battery 226 with the anode 210 of Fig. 12. The opposite sides 210 is Egnnected to the circuit of thefilament 115 of the condenser 225 are connected by high resistances 227, 227 with the connection between'the switch 95 and thebattery 226.

The diaphragm 212 is fiat and is circular in outline provided with a central opening 230. Located outside of and adjacent to the tube 205 and just to the'right of the diaphragm 212 are two coils 231 and 235 which have their axes perpendicular to each other'and to the longitudinal axis of the tube 205. The ends of these coils 231 and 235 are electrically connected respectively to the corresponding terminals 122 and 123 and 127 and 128 of Fig. 2.

In the operation of the sending system shown in Fig. 1 in connection with the receiving system shown in Fig. 2 modified as shown in Fig. 12, the operation of the send ing system and the unmodified portion of the receiving system is as-hereinbefore described to deliver energy to the switch 95 of Figs. 2 and 12 and through this switch the energy acts upon the circuit of the focusing grid 211-of Fig. 12 to varyjthe voltage of they grid in accordance with the variations-in the received energy.

The filament 206 of Fig. 12 heated by the battery 208, and under the influence of the high voltage battery 220, causes electrons to be discharged towards the anode 210. Part of these electrons pass through the tubular extension 216 and then through the focusing grid 211 which is normally acted upon by the battery 226, causing these electrons to be to a certain extent diffused so that only a small proportion ofthem pass through the opening 230 in the diaphragm \Vhen the intensity of the voltage supplied by the amplifying system to the switch 95 is increased due to the increase of the illumination of the cell 62 of the transmitter, the applied voltage on the grid 211. will be decreased so that the scattering effect will also be decreased and more electrons will pass through the opening in the diaphragm 212-thus increasing the illumination on the fluorescent screen 207. In this way the illumination on this screen will be made roportional to the illumination of the 'cell 62, and therefore, to the light reflected from the object 14 to the cell 62 at any given instant. As the electrons leave the opening 230 in the diaphragm 212 they will be acted upon by the two coils 231 and 235 which will deflect them an amount depending upon the intensity of the current in these coils at any given instant and as this intensity varies in the same manner as the intensity of the current in the galvanometers at the trans- 4 mitter the stream of electrons will be caused image having a stereoscopic effect and inv the natural colors of the object this inventransmitter shown in Fig. 11 and comprises a a source of light 300 arranged to illuminate the object 14, an image of which is to be transmitted; a multiplex light reflecting and vibrator rays re ected from the object 14; a chromatic light disintegrator 310 for receiving and chromatically disintegrating the light rays reflected to it by the reflecting system 305; a multiplex photoelectric system 315 and an energizingsystem 316.

The. source of illumination 300 may be of any suitable kind, and in Fig. Q3 comprises an electric lamp 325 energized by a. battery 326 and provided with a reflector 32.7. The reflector 327 is arranged to throw light rays upon the object 14 and to shield the lamp 325 from the light receiving parts 305, 310

and 315 of the system.

The multiplex light reflecting and vibratory system 305 comprises two pairs of mirsystem 305 for receiving light rors 330,331 and 332, 333, very small and very light in weight secured respectively to two pairs of vibratory coils or elements 336 and 337, 338 forming parts offour siiit- W able galvanometers respectively. These vibrat-cry elements 335 to 338 are connected in series in a circuit 339 including a coil 340 arranged. to be energized as hereinafter described and arranged to deliver its-current through a filter 341 to output conductors 342, 343 and thence to the line as will appear hereinafter. The filter 341 is constructed to let pass only waves of the band of frequencies flowing through the input circuit 339 to vibrate the mirrors 330 to 333. The mirrors 330 and 332 are arranged to be vibrated about fixed vertical axes and the mirrors 331. and are arranged to be vibrated about fixed horizontal axes respectively.

The chromatic light disintegrator 310 comprises a substantially flat circular color separating screen or filter 350 (shown enlarged in Fig. 14) This screen 350 comprises a hub 351 surrounded by a rim 352 concentric therewith and rigidly supported therefrom by a plurality of arms or spokes 353 radiating from the hub 351 to the rim. In the openings between the spokes 353 are secured colored segments 354, 355 of translucent material such for instance as glass, and these segments are in this form of the invention alternately of complementary colors, for instance, one segment 354 of an orange red and the next segment 355 being of a greenish blue, these two colors being well known in color photography, the light of these two colors uniting to produce White I or colorless light. In the screen shown six segments are used and these are of equal size and of the same form and so arran ed that a segment of one color is always diametrically opposite to a segment of the complementary color. The screen 350 is arranged to be rotated by an induction motor 360 upon the shaft 361 to which the screen is centrally and rigidly secured, the rotation of the screen 350 being at such a rate and so synchronized with respect to the vibrations of the vibratory system- 305 including the mirrors 330, 333, that the screen rotates through an arc of 360 degrees divided by the number of equal colored segments 354, 355, while the vibratory system is making one complete cycle of operations.

The photo-electric system 315 of Fig. 13 comprises two photo- electric cells 365, 366, of any suitable material the electricv resistance of which is varied by and in accordance with the action of light rays of varying intensity. These cells are respectively in two circuits 367, 368 which control respectively two electrical current amplifier systems 369, 370, which may each be of the same construction as the amplifier system 15 of Fig. 1. These two amplifier systems 369 and 370 control respectively two systems 371., 372 for the production of two series of carrier waves of different frequencies respectively, for instance, of frequencies of 25,000 and 30,000 respectively. Each of these two carrier wave generating systems may be of the same construction as the carrier wave generating system 16 of Fig. 1, each including a three element thermionic oscillator, and a three element thermionic modulator. These two generators 371 and 372 are connected to deliver their outputs to two aperiodic wave filters 373 and 374 respectively, which are constructed to let pass respectively only waves of the two bands of frequencies produced by the generators 371 and 372 respectively and have no time la g. These two filters avoid among other things short circuiting of the generators 371, 372, and short circuiting of the current flowing through the filter 341. The output of filters 371, 372 are conducted to a line wire 375 comprising two conductors 376, 377, which connect the transmission system of Fig. 13 with a receiving system. for instance, such as is shown in Fig. 15 The outer ends of the output wires 342 and 343. of the filter 341 of the transmission system are also connected respectively to these line wires 376, 377.

For electrically energizing the color separating system of the sending station of .Fig.

13, and for synchronously energizing corresponding parts of the receiving statlon as will appear hereinafter, an alternating cur rent generatorv400 is provided and arranged to deliver its output to three wires 401, 402, 403, which connect the sending station (Fig.

333 of light reflecting system 305 of the :sending station and synchronously vibrating corresponding mirrors of the receiving station, 1

as will appear hereinafter, the coil 340 of Fig. 13 is arranged to form the secondary coil of a transformer 415 having a primary coil 416 in a circuit 417 receiving energy from an alternating current generator 420, the same in construction and operation as the generator 50 of Fig. 1, except that it produces an alternating current of for instance twice the frequency of the current of thegenerator 50, or in other words, a current of 6400 cycles per second. An auxiliary alternating current generator 421 corresponding to the generator 52 of Fig. 1 is securely mounted upon an extended part of the armature shaft of the generator 400 so as to be rotated in unison therewith, and is arranged so as to produce an alternating current of for instance twice the frequency of the current of the generator 52 of Fig. 1, or in other, words,

a current of 32 cycles per second in a circuit 422 including .a coil 423 arranged to act inductively upon the field coil of the generator 420 to vary the amplitude of the output current of the generator 420 accordingly at a constant rate and in synchronism with the rotation of the color separating screen 350. For uniform lighting the generator 420 may be caused to produce a current having a wave form indicated by lines 135 of Fig. 3, the envelope of which 136 may be parabolic in form, as described in connection with Fig; 1.

The construction, arrangement and operation of the transmitting system shown in Figs. 13 and .14 are such that when the object 14 receives light from the source 300 a part of the light will be reflected by the object from a given point or spot 425 on the object along the path 426 to the mirror 330, thence to mirror 331, thence along a path 426' and through one of the segments of disc 350 to the corresponding cell 365; and simultaneously another part of the light will be reflected by the object 14 from the same point 425 along the path 427 to the mirror 3.32, thence to mirror 334, and thence along a path 427' and through a. segment diametrically opposite to the first and of complementary color and to the corresponding cell 366. The mirrors 330 to 333 are so arranged that the two mirrors 330 and 332 will always receive light simultaneously from the same point 425 of the object 14 and this pointwill be caused to describe a spiral path moving outward over a left-hand spiral from a central point and returning to the same point over a right hand spiral as shown in Fig. 4.

To accomplish this, the vibrating element 336 is tuned so that its natural period of frequency of vibration is above that frequency of the current produced by the alternator 420 and this Vibrating element 336 is thereby caused to vibrate degrees out of phase with and in advance of the phase of the current, and the vibrating element is tuned so that its natural period of frequency of vibration is below that of the same current and consequently the vibrating element 335 'is caused to vibrate 45 degrees out of phase with and behind the phase of the current with the result that the corresponding two mirrors 331 and 330 will be vibrated at the frequency of the alternator 420 but with a 90 degree phase relation of vibration between the mirrors. The vibratory elements 338 and 337 are likewise tuned ,so that their natural periods of frequencies of vibration are res )ectively above and below the frequency of the alternator-420 and so that consequently the corresponding mirrors and 332 will be vibrated at the frequency of the alternator 420 but with a 90 degree .phase relation of vibration between these two mirrors. If the amplitude of oscillation of the current produced by the alternator 420 were constant, the amplitude of vibration of the mirrors would be constant, and the path traversed upon the object 14 by the point 425 from which the light is received by the mirrors 426 and 332 would be a circle; but since the field of the alternator 420 is energized by a second alternator 421, the amplitude of the oscillations produced by the alternator 420 is varied, thus causing the amplitude of vibration of the mirrors to be varied accordingly and causing the point 425, from whiclnlight is received bythe mirrors 426 and 332, to described a spiral path extending from a central point outwardly and then returning to the central point, as shown in Fig. 4, and as hereinbet'ore described. The time consumed in making a complete gycleof operation of the vibrator system 305 to thus cause the point 425 to travel through a complete spiral path out and back as in Fig. 4 would be one thirty-second of a second when the alternator 421 is delivering current at 32 cycles per second, as assumed. Also during each one thirty-second of a second the point 425 from which light is received will be rotated about the central point of the spiral two hundred times, one hundred in proceeding from the central point outwardly and one hundred in returning, if as assumed the alternator 420 is delivering current at the rate of 6400 cycles per second. Consequently, if the extreme diameter of the object 14, an image of which is to be transmitted, is comparatively small, as for instance not more than two inches, and the electrical devices and connections are so adjusted and operated that the extreme diameter of the spiral path of the point 425 would slightly exceed that of the object 14 then the pitch of the spiral, or distance between successive convolutions of the spiral would be only about 1/100 of an inch so that if the mirrors 330 and 332 were each substantially circular in shape and of a diameter slightly in excess of 1/100 of an inch every point on the face of the object 14 would be twice covered by the point 425 in its passage out and back over the spiral path. However, it is evident that the extreme diameter of-the spiral path, the number of convolutions in the spiral, the distance between successive convolutions, and the time of producing a complete cycle of the spiral, out and back, all may be varied to suit various requirements, as experience may dietate.

Also in the operation of the transmitter shown in Fig. 13 the Various motors and alternators are constantly operated, and the object 14 (here assumed to be a. picture in colors on a flat plane suitably arranged) is constantly illuminated by the lamp 325, and light is reflected or radiated from the entire surface of the object 14 in various directions. The vibrating mirror systems reflect the light from consecutive parts of a spiral path 425, as hereinbefore described, so as to cover substantially every part of the object cyclically from the central portion of the object outwardly to the marginal portions of the object and then returning to the central portion at a rate, for instance, of 64 cycles per second.

These two portions of this reflected light which travel respectively from the con stantly moving point 425 over the constantly changing paths 426 and 427 to the two mirrors 330 and 332 are reflected respectively by the two mirrors 331, 333 through oppositely arranged complementary colored portions of the rotating color disintegrator 350. The screen 350 is so arranged and rotated, and the number of colored segments in the screen is so chosen, that, disregarding the arms 353 of the screen, throughout one entire cycle of vibrations of the mirrors the opposite rays 426, 427 will pass through, for instance, a blue green segment and an oppositely arranged orange red segment respectively, and during the whole of the next cycle will pass through an orange red segment and a blue green segment respectively. Consequently, the rays 4 26 and 427 striking the cells 365 and 366 will be correspondingly colored during one cycle and reversed in color during the next cycleof vibrations of the mirrors and will control the two photoelectric cells 365 and 366 accordingly to produce corresponding variations in the currents flowing therethrough.

I These currents are amplified by the amplitransmitter of Fig.

fiers 369, 370 andthese-amplified currents correspondingly modulate respectively the two series of carrier waves produced by the two carrier wave generators 371, 372 respectively, and these two series of carrier waves thus modulated pass through the filters 373, 374 respectively and over theline 37 5 to the receiving station.

4 In Fig. 15 is shown a modification of the 13. Corresponding parts of this figure are designated by the same reference numerals. In this system a light source 20 with suitable condensing and focusing means 22, 23, 24 and 26 is provided. I The amount of light is regulated by the disc 801 driven by motor 804 which is synchronized in its motion with the motion of the mirrors 330, 331, 332 and 333, as will be more fully explained hereafter in connection with Figs. 18 and 19. The light thus pro; duced and regulated is reflected by the mirrors 380 and 381 and to the object 14 by means of the mirrors 330 331% 332 and 333, to illuminate the object in the same path along which it is being scanned as has been described in connection with Fig. 10.'

Thefunction of the controlling motor 410 and the amplifying, modulating and filtering devices 315, 316 and 373 respectively etc., is the same as that of the corresponding parts in Fig. 13, which has been described above.

Thus there is produced a system which will ive by means of the color disintegratulating system 510, a

ing evice 350 and the dual mirror systems an improved stereoscopic transmisslon in natural colors.

In Fig. l5 is shown one form of receiving system which may be used in combination with the transmission s stem shown in Figs. 13, 14 and Fig. 15. his receiving system comprises a duplex source of light 500, a color disintegrator 505 a duplex light mod.-

duplex light vibratory system 515, a light receiving and reflecting screen 520, an auxiliary 'color disintegrator 525, and a duplex electrical receivingsystem 530.

The duplex source of light 500' comprises two electric lamps 535, 536 of equal intensities and arranged to beenergized by a battery 537. q

The color v'disintegrator' 505 includes a color separating disc or screen 550, the same in construction as the screen 350 of Fig. 13;

-'-and this screen is rotated by a synchronous motor 560 which is arranged to be energized through connections with the three conductors 401, 402, 403 which receive energy from the alternator 400 of Fig. 13. Consequently, the screen 550 of the receiver is synchronized in its rotation with the screen 350 of the sending station, and the former screen is so constructed and arranged that throughout the cycle when the rays 426 and 427 'r ofthe sending station are orange red and blue' receiving station will also be reversed.

' The duplex light modulating system- 510 comprises a Nicol prism 565, a polarizing cell 566 and an analyzer or second Nicol prism 567 crossedwith respect to the first prism 565, all arranged in alinement with the elec-.

tric lamp 535 to receive and modulate a small beam of light 568 therefrom; and a Nicol'prism 570, a polarizing'cell 571 and an analyzer, or second Nicol prism 572 crossed with, respect to the corresponding first prism 570 are arranged in parallelism with the first mentioned prism 565, cell 566 and prism 567, and in alinement with the other lamp 536 to receive and modulate a second small beam of li ht 569 therefrom.

The duplex light vibratory system 515 comprises two vibratory mirrors 575, 576 arranged to receive the two small beams of light 568., 569 from the two prisms 567 and 572 respectively, and two vibratory mirrors 577 and 578 arranged to receive light refiected thereto by the two first mentioned mirrors 575, 576 respectively and. to reflect the same to a point 579 on the screen 520. These four mirrors 5755 7 8 are arranged to be vibrated respectively by the four vibratory coils or elements 580, 581,582 and 583 of four corresponding galvanometers. The

mirrors 575 and 576 are arranged tobe vibrated by the' corresponding coils about fixed horizontal axes respectively, the other two mirrors 577 and 578 are arranged to be vibrated by their corresponding coils about fixed vertical axes respectively, and the tuning of the four coils or vibratory elements 580-583 is similar to the tuning of the corresponding coils or vibratory elements 335-338 of Fig. 13, and is such that the four mirrors 57 557 8 are so vibrated as to cause the point or spot of light 579. to travel over the screen 520 in a spiral path which is a reproduction of the spiral path of movement of the point 425' on the object 14 of Fig. 13. These coils 580-"583 are in series in the circuit 376, 377 which receives the alternating current of 6400 cycles per second from the alternator420 of the sending station modulated at 32 cycles per second by the alternator 421 of the sendingstation and consequently the mirrors of the receiving station are vibrated in synchronism with the mirrors of the sending station. A filter 585 similar to filter "341 is inserted in the cir'cuit 376,

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