US2059222A - Television apparatus - Google Patents

Description

R. A. FESSENDEN..,

TELEVIS ION APPARATUS Original Filed Jan. 14, 1927 5 Sheets-Sheet l @AMJO/Q fw w a NW. 3, 193%. R. A. FE$SENDEN fi y TELEVISION APPARATUS Original. Filed Jan. 14, 1927 5 Sheets-Sheet 2 aw @2? x Raw. 3 W355. R. A. FESSENDEN TELEVISION APPARATUS Original Filed Jan. 14, l927 5 Sheets-Sheet 3 R A. FESSENDEN TELEVIS ION APPARATUS Original Filed Jan. 14, 1927 5 Sheets-Sheet 4 fl w/ EMA i -l'mr. 3, 3336.

R. FESSENDEN TELEVISION APPARATUS wwzzz Original Filed Jan. 14, 1927 5 Sheets-Sheet 5 Patented Nov. 3, 193.6

Helen M. Fesscnden, executrix of the estate of said Reginald A. Fessenden, deceased @rlginal application January 14, 1927, Serial No. 161,159. Divided and this application April 4,

1928, Serial No. 267,373

12 Claims.

My invention relates to the transmission of energy, and still more particularly of signals and pictures and moving pictures, by high frequency impulses, and more particularly by high froquency currents, and still more particularly by Hertzian waves; and to the elimination of the disturbing effect of atmospheric and other injurious influences; and to the reduction of the cost and uncertainty of transmission.

This application is a division of my application Serial No. 161,159, filed January 14, 1927, which application is a continuation in of my Patent No. 1,617,241, granted February 18, 19.7.

It has for its object the accomplishment of such of the subjects to which it relates which have'not heretofore been accomplished; and increased efficiency and simplicity and reliability and economy in such as have been accomplished.

It is a further development along the lines disclosed by applicant in his article in the Electrical World of Sept. 15th, 1894, (relating to wired wireless and the use of sine waves for wired Wireless, and the method transmitting signals in wired wireless by modulation instead of by opening and closing the circuit). And in the ofiicial experimental records of the U. 8. Weather Bureau for 1960-1901; U. S. Patents 705,737, May 1901; 706,742, June 6th, 1962; 706,747, Sept. 28th, 1901; 1,015,881, Dec. 19th, 1906; U. S. patcut application 222,301, Aug. 26th, 1904; (these relating to the generation and modulation of sustained electrical oscillations of Hertzian fre quencies, and to broadcasting and transmission oi pictures). And in other U. S. patents granted to, and articles Written by applicant.

In the drawings accompanying this specifica tion:

Figs. 1 and 2 show a transmitter and receiver for printed intelligence.

Figures 3 and 1 show, partly diagrammatically, the transmission and reception of intelligence; Figure 1 showing the sending end and Figure 2 the receiving end.

Figures 5 and 6 show a transmitter and receiver for a continuously moving intelligence carrier.

Figure '7 shows a light source and Figure 8 a light valve which may be used at the receiving station.

Figure 9 shows a scanning device for the transmission of colored pictures.

Figure 10 shows various forms of printing devices for printing characters on a tape.

Figure 11 shows a device for eproducing in- .55 visible images.

Figure 12 shows a device utilized in the transmission of colored images.

Figure 1, l5 and :16 are rotating mirrors preferably of stellite though magnalium or silvered glass may be used, the axis of 25 being in 5 the pl ne of the paper and the axis of $3 perper -cular thereto. These mirrors are driven re ectively by the motors 37 and whose spee' be transmitted be taken as perpendicular to the paper, then the rotation of 33 will throw on the light or heat actuated cell to (for the apparatus is capable of transmitting heat pictures as well as light pictures and so detecting battleships, aeroplanes, motors etc. and at night and in fog) a succession of small areas along the line that to be scanned.

In the present arrangement shown in Figure 1 25 the elementto be scanned comprises a band or tape it??? which has preferably a typewritten message impressed upon it by the typewriter 53!), Fig. i. The band may be stationary, as in Fig. l, or continuously moved, as in Fig. 1, by means of 30 the motor d9 shown at the right of the band, which motor carries a roller ii} upon which the band may be wound. Sufficient slack may be provided at the left end of the band before the position of the scanning so that impressing of the 35 typewritten message upon the band may not interfere with the continued slow movement of the band itself. The typewriter, traveling band and motor shown for the purposes or" the drawings in the plane of the paper. For actual opera- 40 tion, however, it would be preferable to have the band traveling in a plane perpendicular to the plane of the paper so that the scanning may be made directly without the use of any converting mirrors. 45

Assuming that the band H35 in Fig. 1 is perpendicular to the plane of the paper and that the mirror 45 is rotated, then strips of areas will be, taken from different heights in the field and successive strips will cover the whole field. If 50 the band I36 were to be moved very rapidly, the mirror it is omitted since under such conditions a single element could be obtained for each movement of the mirror. This is shown in Fig. 1 where the frame 268 on which the message of facsimile is produced is transmitted to the rotating prism 295 from which it may be reflected through a pin-hole opening in the mask to the li ht valve 53 through which the impulses are impressed upon the transmitting circuit. The faces of the reflecting mirror Elli may be so tilted at dii'crent angles with one another that each mirror will consecutively scan the next line in the frame, the frame itself moving and advancing to the position where successive lines are in position for scanning.

In Fig. 2 the receiving end is indicated corresponding to the sending end in 1. Here the beam ZiB-i is reflected by means of a reflecting" surface to the prismatic mirror which rotates in synchronism with the mirror 2 26i and which casts the reflection of the beam on to the moving frame 25? operated through the motor 82' which should be in synchronism with the motor 89.

When both mirrors are rotating simultaneously these strips of areas will be inclined to the horizontal at an angle depending upon the relative speeds of the mirrors and if it is desired to maintain them approximately horizontal, one of the mirrors, for example 35, may be rotated many times faster than th other 16; and preferably an even number of times, which may be accomplished by so designing the gearing or the pole numbers of the driving motors, or to produce slow beats between approximately equal speeds as described below.

In place of using fiat mirrors, as shown in Figs. 1 and 2, prismatic mirrors with six or more sides may be used, as shown in Fig. 3. By using these, when one end of a strip of areas is passing or? from the light actuated cell 56, from one set or pair of mirrors, the beginning 01" another strip of areas can be made to be just beginning on I another pair of mirror surfaces.

.brilliancy or definition, this being reproduced at receiving end.

The mirrors may be ground to spherical or cylindrical faces, but are preferably flat and What focussing etc. is desired is preferably done by the optical system 53 and In addition to the matter of convenience, the lens 53 may be made of substances more or less opaque to heat rays, and may be built up of parts 52 and B l so as to let through-a spectrum distribution corresponding to that of the eye, by using differently tinted glasses. Or it may be made very transparent to heat waves, as when the apparatus is used on board an aeroplane at night time or in a fog, to show the pilot the configuration of the ground by a thermal view, transmitted into a visual one.

The light responsive cell 56, which I call the photocrat, because it governs the transmission of energy in accordance with the light received on it, (from the Greek words meaning light governor) may be of any suitable type, for eX- ample a hot wire barretter, as here indicated, comprising a vacuum tube 55 in which are provided two supporting conducting elements and 5'! which feed current to the small hot wire element 58 or which react through the light thrown on the wire element to produce a curshown in applicants U. S. Patent 766,742, Fig. l,

except that the terminals of the barretter are not connected directly to the antenna, but to an amplifier or transmission circuit, which the bar- -retter modulates, and the telephone 55 is omitted.

The cell may be initially energized by means of the battery 59 through adrop wire it the choke coils ti and $2 being used to provide a high impedance to the variations caused by the radiant energy impressed upon the cell element 58. The cell element 58 is connected through the conductors t6 and 3? and the external wires and J ll to an amplifier 35 which may be connected to a transmission circuit or as indicated in the drawing to a radio transmitter 65 for impressing the impulses in a suitable manner on the antenna bl. The amount of local current from tie battery 59 which may be used to increase the sensitivenes's of the cell element 53 is adjusted by means of a drop wire 6% usually to about one milliampere, the best current for varying conditions must be found by trial and adjustment. As indicated the cell is enclosed in a vacuum by means of a container 55 and this has proved to be preferable under most conditions, but it is not however necessary under all conditions to keep the cell so enclosed as it may be surrounded by other means that are heat opaque or visually transparent to different spectral characteristics.

A multiple barretter, as shown in Fig. l, may

be used in place of a single wire.

When a linear receiver, as a single barretter wire is used, the lens 52 is preferably of the cylindrical or cylindro-spherical type, so as to concentrate the image of the small picture area falling on it into a line which shall fall on the fine wire, and so no picture radiation be Wasted.

When it is desired to transmit the picture in its natural colors, successive faces of the prismatic mirror Fig. 3, may be coated with this film so cnt parts of the lens, thereby successively tranomitting red, blue and yellow light of suitable spectrum composition to the photocrat.

A further modification of this is illustrated in Figure In this figure i shows a screen to be viewed, and it? prismatic mirror having six or more faces wi h surfaces coated properly so as to refiect, red, orange, yellow, green, blue and violet, as indicated by the respective letters, R, O, Y, G, B and V. The prismatic mirror may be rotated.

on the shaft 2 by means of the motor 3 at any de- ,65

sired speed and the image from the prismatic sur faces may be reflected on the lens is which may be cylindrical or any other useful type. The lens ill may be arranged with sections, a, b, c, d, e, f,

for passing or reflecting the corresponding lights .70

from the respective mirrors, R corresponding to ftob/B toc,Gtod.Ytoe,Otof.

In place of using a hot wire barretter, or applicants thcrmop'none (see appllcants article in the London Electrician. June 24th. 1904) or a sensitive thermocouple, (see same article) a light sensitive vacuum tube may be used, as shown in applicants patent U. S. 1,133,435, Feb. 9th, 1914. Or an alkaline metal amalgam vacuum cell. 01' a selenium cell, suitably shunted to give rapid response. Or a polarizing cell of the Minchin or other suitable type. Or a gas expansion cell, actuating a telephone diaphragm. Amongst other new devices for this purpose, applicant has discovered that substantially all transparent bodies have their specific inductive capacities changed when light of the wave-length which they absorb falls on them. This is especially marked in the case of strongly fluorescent bodies. The effect is small, but is readily amplified, and condensers so made will themselves act as amplifiers if a high frequency current be impressed on them. As a rule the response is rapid enough, but where it is not, the substance may be made to rotate or flow rapidly between the plates of the condenser. Substances of different spectral absorptions may be used, and so chosen as to have any desired spectrum characteristic, and in the case of fluids, may be dissolved in one another. This variation of specific inductive capacity may be used to modulate the transmission circuit, in manners obvious to those skilled in the art, see U. S. Pat ent 706,747 of applicant.

In operation, therefore, as each small picture area is reflected and focussed upon the photocrat, the photocrat generates an electric impulse proportional to the amount of light or heat falling on it, i. e. as emanated from the original small picture area. This minute electric impulse, with or without amplification, actuates the amplifier 65 of the transmission line or the radio transmitter 60, which latter may be any circuit suitable for the transmission.

Where the transmission is by wire lines, or other conductors, the generator of the transmitting station may be omitted, and the modulating impulses, preferably amplified, may be used for the reproduction.

This succession of small picture areas therefore, sweeping over the photo-erat, modulates the transmitted current or radiation in accordance with the luminosity, or temperature, or luminosity and color, of said picture areas.

This modulated current is received at the reproducing station, and there employed to reproduce the picture, or the scene which is going on, at the sending end, for example a photograph, or a baseball game, or a scene from an opera.

Even with the somewhatcrude apparatus, and insufficient amplification employed by applicant, applicant has succeeded in cutting down the time of modulation and reproduction of a transmitted image per single image area. to one fifty-thousandth of a second. Allowing five repetitions per second for persistence of vision, it will be seen that this gives 10,000 (ten thousand) small picture areas for the field of the picture, or, allowing fifty areas per linear inch, at ten inches focus, (the usual process print definition,) this gives a picture ten feet square on the movie screen at the reproducing end, at a distance of fifty feet, which is sufficient for substantially all practical purposes. And applicants tests have shown that with increased amplification and with more carefully constructed apparatus, there is no difiieulty in obtaining 250,000 picture areas per second, with a corresponding increase in reproduced image area.

It will be note-d that the smallest object which can be seen by the human eye subtends an angle of one minute of arc, which at the normal focal distance of ten inches, is 1/300 inch diameter, and that this is in a stationary field and not a moving one, and with erfect contrast. In process prints,

where the field is fixed but the contrast is not perfeet, as it is in a line drawing in black and white, areas as large as 1/50 inch in diameter are found to give very satisfactory results. Where the pic ture is a moving one, even larger areas are found satisfactory.

In addition, with applicants arrangement the definition is very much improved over the process print for the reason that while the invention may be used to transmit and reproduce a succession of discontinuous picture areas, or dots of varying darkness, as described in applicants U. S. Patent 1,015,881, Dec. 19, 1906, but by means of a different invention, yet it may be, and as shown is preferably used to transmit by continuously modulating the transmitting impulses. This continuous modulation of the transmitted impulses in accordance with the varying intensities of successive small picture areas gives much more satisfactory optical effect.

In Fig. 2 the projector 77-8! is preferably a continuous current arc lamp projector or a pointolight projector with a source as indicated by 78 in Fig. 2.

with a tungsten or similar type of incandescent lamp, and at high frequencies of the order of 10,000 per second or more.

The device 10 for modulating the projected light in accordance with the received modulated impulses is shown in detail in Fig. 4. It consists of a form of shutter which applicant has tested up to speeds of 1/200,000 (one two hundred thousandth) of a second, using only a few microamperes of current. This shutter, which I call the cratophote since it governs the light, whereas the photocrat is light governed, is based on applicants filament galvanometer, described before the Indiana Academy of Sciences in 1892, and is related to those forms shown in applicants U. S. Patents 1,172,018, March 14th, 1908, Figs. 2, 3 and 4; 1,045,782, June 16th, 1908; 979,145, Dec. 23rd, 1907; and 706,737, May 29th, 1901.

As shown in Fig. 4,, and in applicants Patent No. 1,617,241, and in U. S. Patent 1,172,018 in part, two rows of fine wires H and 72 are placed with the spaces between the wires of one row opposite to the wires of the other row, so that when placed in the path of the projector beam no light, or only a predetermined amount, can pass through, the grids or wires ii and 72 being placed in the magnetic field of the coil M, (a permanent magnetic field may be used if desired,) so that when a current is passed through the wires of the grids, the wires of each grid will move in opposite directions and let the light through. If this current is the light modulated current from the transmitting station the amount of light let through will correspond to the illumination of the succession of small picture areas at the transmitting or observing station.

A predetermined amount of light may be allowed to pass through the shutter in the absence of, or independent of, the modulating current, by passing an auxiliary direct current through the battery 15 or alternating current through the wires of the grids; and by adjusting the current as shown in the magnetizing coil 70; and by ti1t ing the grids sideways to each other.

When the light from the projector strikes the grids, the wires expand, and to take the slack out I have found that an alternating current does not give good results except when used of the wires, an additional magnetic field, gener ated by the coils l5, 16 is used, which tightens the wires without disturbing their alignment; in fact making it more stable.

The wires may be of any suitable size. Applicant has used wires as small as 1/10,000 inch and as large as l/l,000 in. They can be left bright or lightly silver plated and dipped in sodium sulphite to blacken them, after mounting. I prefer to draw the wire with the silver sheath half the thicknes of the gold core, wind the wire on two grid frames placed back to back, with the silver sheaths touching, solder the wires, or spot weld them, to the frames, out the two frames apart,

and dissolve the wire sheaths with the apparatus shown in applicants paper on Wireless Telephony, (transactions of the American Institute of Electrical Engineers, July 1908).

The wires ii and 72 may be held by a frame i3 and may be connected to a radio receiver 09 so that the impulses received from the antenna 68 may be impressed through the receiver directly upon the light modulating device. It should also be noted that the projector ll may be provided with suitable lenses '30 and 80 for concentrating the light either in a point or line source depend ent upon the position and shape of the shutter it.

As indicated in Figure 2 a second lens 65 may be used in the system and positioned beyond the shutter "E0 to provide the proper light beam for ultimate reflection upon the projecting screen 82 or moving tape as indicated in Figure 2. by means of the mirror system including the mirrors 33 and 34 operated respectively by means of the motors ii and 50. A further lens may be provided for concentrating the light in a suitable manner just before projection on the screen 82. The motor 82' may cause the tape or screen to travel in corresponding synchronism with themotor is at the sending end.

In order to utilize fully the shutter and to heat all wires uniformly, the projector 11 may be fitted with cylindrical, in addition to spherical, lenses, and a cross cylindrical or other suitable combination of cylindrical and spherical lenses used to reform the image, if desired, after the beam has passed through the shutter.

As the grids act to some extent as a spectroscope and give rise to other diifraction phenomena, they are made adjustable as to distance by means of wedges, the distance being varied till the operation is most satisfactory. It will be found that by proper adjustment the efficiency of the shutter may be made several times greater than that corresponding to the size of the wires used. The usual heat screen may be used between projector and shutter, and the grids may be in hydrogen or vacuum:

While this form of cratophote has been found suitable, other forms may be used, for example the devices shown in applicants U. S. Patents 1,044,637, July l l-th, 1905; and 1,045,781, June 16th, 1908. For example, Fig. 3 of the former may be actuated by the modulating current to move a grid of Wires, or a piece of glass or mica having alternate transparent and opaque portions, or to rotate a mirror and so throw the pro jector light away from or through the opening through which the light passes to the screen; and this opening may itself be fitted with a grid and the mirror may have the silvering or platinizing in strips, like a grid, so that a very small motion of the mirror about its axis will throw the light through the opening to the screen, or shut it oil.

01', as shown in applicants U. S. Patent 915,280

Feb. 8th, 1907, the intensity of the light source itself may be varied by the received current and audion ll'1.COIlI1BCiJiOl1 with the Edison valve,

(Edison U. S. Patent 307,031, Oct. 21st, 1884) instead of outside, as in applicants Patent 915,280. Illumination in thetube may be provided through the potential Other methods will suggest themselves to those skilled in the art.

The grating shutter type of cratophote has certain advantages; for example it is so sensitive that it may be used, where the movie screen is small and mounted on the arm of a chair or a desk, without amplification at the receiving end, and also without the use of a carrier current in the transmission line or wireless antenna. A few microamperes of current are sufficient to operate it. It operates very reliably up to frequencies of alternation of 200,000 per second, and without doubt up to 1,000,000 per second, though 200,000 per second is all that applicant has actually used to date. 1t-is easily adjusted electrically, so as to let any predetermined amount of light through in the absence of the modulating current. All natural period of vibration may be eliminated by the method shown in applicants U. S. Patent 1,319,521, June 8th, 1917. The range and overload capacity are much greater than any other known instrument, as with wire of gold and 1/ 10,000 inch diameter an indication is produccd with l/l.,000,000,000 ampere of current, but it will carry 1/1,000 ampere safely, i. e. a ratio of 1 to 100,000 in current or 1 to 10,000,000,000 in energy. It also lends itself readily to mechanical and electrical heterodyning, the advantage of which is more fully explained in another application. I i

A further important advantage of this form of shutter, when used in this connection, is the fact that the light transmitted through the shut ter is a multiple valued function of the current;

for as the current'increases the wires of the two grids are brought in line, one behind the other, and the light passed is then a maximum. If the current be still further increased, the wires begin to pass each other, shutting off the light, more and more, until the wires of one grid are now opposite the spaces of the other grid, and the light is a minimum. If the current be still further increased, the light passed increases again, and reaches a second maximum, and so on. This multiple valued relation of impulse to eifect has the very important and hitherto unsuspected property that it greatly diminishes, in fact practically eliminates, all injurious effects of atmospheric and other disturbing impulses in transmitting pictures, and signals, of all kinds. For if, in projecting a radio-movie of a distant scene, a strong atmospheric impulse occurs, there will be no intensely bright flash of light on the screen to disturb the eye and spoil the rest of the picture by irradiation, after effect and the like. But on the contrary, it will be as apt to reduce the intensity of the luminosity of the small picture area affected as to increase it, i. e., the result will be a grey unit area instead of at worst a white or dark area, and there will be no injurious irradiation or after effect etc. And similarly for other types of signals, for example, telegraphic signals.

Where alternating currents or Hertzian waves are used for carrier currents, a rectifier may be operatively connected to the shutter, as shown in applicants U. 5. application Serial No. 286,914, filed Nov. 11th, 1905; and applicants U. S. Patent 222,229, Aug. 26th, 1904, Fig. 2, divided from U. S. Patent 222,301, filed Aug. 26th, 1904; and Well known in the art.

After passing through the optical element 8i above described, the modulated light is received on the mirrors 80, 83, which are of similar construction, and operated similarly to the mirrors 45, 36. By them the picture elements are distributed on the screen 82. The reproduction process, it will be seen, is substantially a repro duction of what takes place at the sending end, with action reversed.

These pairs of constantly revolving mirrors, on axes, constantly shifting in phase, and inter-refleeting, I call for convenience heliopes, a term used by Homer to express the rapid rolling of eyes in all directions, and somewhat euphemistically translated as quickly glancing. Both heliopes, i. e., the one at the sending station and the one at the reproducing end, are preferably driven at constant but adjustable speed, as stated in describing the set 05, 05. The relative speeds of each mirror of a heliope, say 55 and 36, are so adjusted that each picture area will recur sufficiently often to give the required persistence of vision, for example second apart, This may be varied either by varying the speed of the whole heliope, or by varying the relative speeds, and the definition may be varied similarly. This recurrence may be eiiected by, amongst other ways, making one mirror turn only five times per second, and the other turn 5,000 or 50,000 per second, or in the case of a 25 sided mirror, in 5 seconds and one two thousandth of a second.

But it is preferred to so gear the mirrors together that one makes 5 turns more per second than the other, for example 05 makes five turns more than 06, and similarly for 84, 83.

The regulation of the heliopes need not be automatic. It has been found in practice that if the speed be wrong a distorted blur is seen,

but that by changing the speed of the heliope' 83 it gradually straightens out, becomes intelligible and erect. The mirrors are, however, preferably fitted with fly-wheels or the equivalent.

Pictures or messages may be sent in undecipherable code by tilting successive sides or the rotating mirrors so as to make the picture area strips succeed each other at arbitrarily determined order, both horizontally and vertically. The chances of any one not knowing the exact angle for each mirror side detecting the message would be one in many millions. This method may be used for cypher purposes generally, and the message may be photographed. Even if an operator seeing in managed to strike the right speed of mirror 65, and the right ratio of speed of mirror 46, nevertheless what would appear on his mirror as two adjacent strips of mirror images would really be two non-adjacent complex curve strips of the picture actually sent, and so the reproduction made by the seer-in would be a crazy patch quilt.

The gearing of the two mirrors 45, 05 need not be continuous, i. e. instead of rotating at a constant ratio of speeds they may rotate continuously at the same, or some multiple of each others speed for one-fifth of a second; then by dropping a tooth of the gear, or the equivalent device, one may lose a single or other fixed number of turns to the other.

In place of mounting the mirrors 05, G6 (or 84, 83) on different shafts greater accuracy of conjoint movement may be obtained by mounting them on the same shaft, one mirror, say 45, being fixed rigidly to the shaft, and the other 46, revolvable about the shaft, and a gearing driving around slowly relatively to 05. For example, if the carrier frequency is 1,000,000, and the picture element area frequency is 200,000, and the picture recurrence frequency is if the mirrors i5, 05 are twenty sided, then the shaft and mirror 5 will revolve 3,000 times per minute; and mirror it, if it were rigidly attached to the shaft, would also rotate 3,000 times per minute, but it is slowly driven by the gear relatively to Z5, and so only rotates 2,700 times per minute.

A fixed mirror system is used in this case to make the necessary change of reflecting angle between the two mirrors d5, 05, and this allows of the construction of a view finder, by taking a small amount of the light which would fall on the photocrat, or the equivalent falling on an other point, and reflecting it back on the heliope. and thence on a ground glass or other screen.

In place oi, or in addition to, the regulator referred to above, as described in applicants paper on wireless telephony, in the transactions of the American Institute of Electrical Engineers for July 1908, the fly-wheel circuit described in applicants U. S. application Serial No. 222,301, filed Aug. 26th, 1904. This should be connected to the A. C. regulating motor, and should be resonant to the motor frequency, and have as large capacity as possible and minimum dielectric losses. The capacity or inductance should have a very fine adjustment, so that the resonant fre quency can be slightly varied. Fig. 5 shows the use of the invention for telegraphing and working multiplex on a single frequency, and elimihating atmospheric disturbances, and thereby reducing the size and cost of stations. Any suitable means or" sending may be used, but it is preferred to use typewriters E30, l3i, 532, which type the messages, thus giving a record at the sending end. To transmit a line or any convenient short portion of the message is exposed to the heliope. The line exposed may be a line of the actually typed message, as. Or the typewriter may be of the standard Morse sender type, which sends a Morse signal each time a key is struck, corresponding to the letter typed on the paper, and this signal may be used to operate trip switches on a travelling band of incandescent lamps, a dot lighting one or two lamps, as indicated at 533, and a dash lighting two or four lamps, as indicated at H33, the trip switches being opened by another trip as the lights on the band pass back of the pulleys, or outside of the field of the heliope; as shown at E35. Or the typewriter may set up the actual letters H30 in incandescent lamps, on the travelling band of incandescent lamps, as with the Mergenthaler type setter, as shown in the band i3 1.

In each case the message is exposed to the heliopc and transmitted as above described in the case of the picture, and reproduced at the receiving end where it is thrown on a screen and a corresponding number of typists take the message down, each typist typing down the words which appear on the line which is allotted to him, If desired the lines may be of different colors, as explained in connection with the transmission of colored pictures. Or, by an optical arrangement of mirrors, each line may be made .visible to the typist concerned, and to no other, each line being reflected to a different position.

This method has the advantage that a considerable number of messages may be sent on the same wave length, and received at different stations. For example, New York may send 12 messages, of which four may be received at London, two at Rome, three at San Francisco, one

at Rio Janiero, and two at Warsaw. Or six messages may be sent out from New York to different stations, and simultaneously six may be received from other stations, or the same stations, New York sending on the 1st, 3d, 5th, 7th, 9th, and 11th lines of the pictured message, and receiving on the other lines; and the same heliopes may be used for both sending and receiving, the reproduction screens being semitransparent and the travelling incandescent lamp belts placed behind them, (or to one side if preferred) and the impulse modulating cell, or photocrat, placed to one side. In telegraphing by this method the receipt of the messages is not interfered with by atmospheric or similar disturbances. The receipt of a strong atmos pheric discharge merely makes a grey dot, lasting for a fifth of a second, on some part of some particular. letter, and does not interfere in any way with the visibility of the whole word or letter. In other words, the efiect of the atmospheric is distributed over the whole message. Or, in other words, there is no one to one correspondence between the signal element and time; the time is a multiple valued function of the signal element, but ultimately a single valued function of space; and as the atmospheric disturbance is a single valued function of time but a multiple valued function of space, its effect is substantially negligible so far as the signal is concerned.

This new method is not limited to optical means. For example a mechanical equivalent to the heliope may be used, by using a Wheatstone tape, and passing it under a succession of brushes, making contact through the holes, or under hole operated relays, transmitting the impulses as a multiple valued function of the time, and co-ordinating, at the receiving end, by a similar set of brushes, them into a single valued function of space; with or without the use of time lag devices at the receiving end, or of synchronous commutators, and actuating the brushes at the receiving end in predetermined order.

Static being eliminated, it is possible to use higher amplifications, and hence smaller antenna at the stations. Applicant prefers to use his loop antenna, or wireless pelorus, as described in German Patent 225,256, Jan. 14th, 1907; British Patents 4,710 and 28,412, 1997; U. S. Patent 754,058, March 8th, 1903 and U. S. Patent 1,020,032, July 27th, 1903; and in the Electrical World, Aug. 12th, 1899; and the London Electrician, Dec. 19th, 1919.

Many modifications will suggest themselves to those skilled in the art. For example, the heliope described above, in which both mirrors are mounted on the same shaft, one fixed and the other loosely, and the intermediate mirror system for changing the reflecting angle is fixed, may be modified by fixing both mirrors firmly on the shaft, and mounting the intermediate system loosely on the shaft, and revolving or oscillating slowly with respect thereto. the mirrors themselves may oscillate instead of rotate. Many other uses will suggest themselves to those skilled in the art. The method of telegraphing so that no other station shall be able t receive the messages unless it has the information as to the tilting of the mirrors or sequence of the image areas'has been described above in connection with the transmission of pictures.

The area of the picture may be increased by using higher frequencies of the carrier current,

whichis possible over long distances because the elimination of atmospheric makes greater amplification possible; also relay stations may be used, as shown in applicants U. S. Patent 974,753, Jan. 14, 1907, and acting as centres of news and picture distribution. A plurality of heliopes may be used to take and reproduce a single picture.

It may be used for meteorological purposes, to map out the advance of bodies of air of different temperatures. When used for detecting aeroplanes at night or in fog, a sight consisting of a circle of electrically heated Wire may be used, the image of which is thrown on the screen. Or two cross Wires, heated as indicated in the arrangement shown in Fig. 8, may be used, showing by their rectilinearity the accuracy of the synchronism; and the images of which may be used to automatically regulate the speed of the heliope and keep it in synchronism by actuating heat or light responsive cells when the image of the wires moves from its proper position. See applicants U. S. Patent 979,145, Dec. 23, 1907.

In Figure 7 the View to be scanned is indicated at 2'] and a scanning mirror at 28 driven by the motor 29 at a certain chosen speed. In conjunction with the scanning mirror there is provided a frame 39 through which the rays from the object to be scanned pass to the scanning mirror. The frame is provided with cross wires 3i and 32 which may be heated from an external source 33 by means of the leads 34 and 35. In this way not only may a reference be obtained but it is also possible as mentioned above to use this arrangement in maintaining the synchronism between the sending and the receiving systems.

It may be used in conjunction with applicants wireless telephone, U. S. Patent 706,747, Sept. 28th, 1991, and American Telephone Journal, Jan. 26th and Feb. 2nd, 1907, and Proceedings Amer. Inst. Elect. Eng. July 1998. In this manner talking movie pictures may be transmitted; it being preferred to use in this connection the arrangements shown in applicants U. S. Patents 1,213,176, June 27th, 1917; and 1,277,562, Feb. 28th, 1917, and other U. S. applications of applicant.

Applicant has discovered, and claims the inventions, that both speech and pictures may be simultaneously transmitted on the same carrier frequency; or when a carrier current is not used. the speech can be transmitted on the same transmitting circuit as the pictures, the picture area frequency having been found by applicant to be as a rule so much higher than the speech frequency that there is no substantial interference.

The method may also be used for transmitting speech, with. an acoustic heliope, the time being so made a multiple valued function of the sound element, and in this way the eifect of disturbing noises eliminated.

And

While the grid galvanometer shown in applicants U. S. Patent i,1'l2,018, March 14th, 1908, is not adapted for use as a wireless receiver, by reason of the wires being made resonant to a natural period, and the field being a continuous current one, and other reasons, has not therefore been so used, the grid arrangement shown in Fig. i and heroin cleaned, is well adapted, as applicant has discovered, for this purpose. It is also well adapted for heterodyning, by passing a high frequency current through the magnetizing coil This new type of grid galvanometer receiver has the great advantage that it substantially eliminates the effect of atmospheric, for the rea sons mentioned above in connection with the effect of atmospheric disturbances on picture transmission; in contrad' "notion to the earlier type vibrating at a natural period, which gave the same type of indication on receipt of an atmospheric disturbance as on receipt of a signal, the present type, being dead beat, gives a small and easily distinguishable effect. It is not necessary that both sets of grid wires should move, or move in opposite directions when used for the method herein described.

Speech may also be transmitted by forming the picture screen at the sending end of a number of applicants thermophones, (Electrician, London, June 24th, 1904), each tuned to a short range of voice frequencies as in applicants U. S. application 35,957, Jan. 23rd, 1915, and actuated by the speaking voice as therein described, or by other suitable means, and after transmission reproducing the speech in reverse fashion, or its equivalent. The repetition frequency for this purpose should be much higher, as will be found experimentally.

The grid receiver shown in Fig. 4 is especially suited to transmit speech on account of its freedom from disturbance by atmospheric, when acting as a. wireless receiver. The atmospheric can never reach above a certain intensity, and the speech is always superimposed upon this, and the change of phase or reversal of the speech frequencies, due to the phenomenon referred to in connection with the transmission of pictures, does not affect the speech appreciably.

When the grids l l '52 are used with an electromagnetic field, especially a heterodyne field, it is preferred to divide each grid into two or more sections and cross connect them and balance them by shunts or otherwise. For example, if the Wires of the left hand half of grid ll move to the right, those of the right hand half should move to the left. Or both it and "22 should be wound together on a threaded support. If this is not done, fluctuations in the field will move the wires the absence of signals. In use the field is adjusted until when the desired signals are being received the wires or" the grid move approximately [/0 the centre of the spaces obtaining when no signals are being received. In this position, the wires of the two grids are in line with each other, and the maximum amount of light or heat, approximately, passes through the grids and falls on the selenium .cell or thermophone or equivalent device or screen. When adjusted for working the wires need not have the same positions they have when no current or field is on, but may be at any desired distance therefrom, preferably an even number of spacings, or wire diameters.

The effect of atmospheric or disturbing signals is, whether rectifier, or heterodyne, or plain recelver without either is used, (see applicants U. S. application Ser. No. 461,752) to change the phase of the received signal, and in some cases, to introduce a higher harmonic. charge will make the wires of one grid pass by five or ten wires of the other grid, but no matter what their position they will operate to modulate the light or heat from the projector at the frequency of the signals, or a multiple thereof.

The light or heat projector may project several horse power, or even several hundred horsepower, and the grid arrangement acts as an amplifier, and also, by inserting a tuning circuit or its equivalent in he suit, (or mechanical regulator,) as a generator of oscillations of desired frequency, i. e. 1,0003% or more, though 50,000 is the most applicant has had any object in generating by this means to date; the possible ireduency being obviously much greater, especially when light or heat absorbing insulators are used as photocrats, as described above.

I claim:

1. In a transmitting system for transmitting intelligence, a. device for mechanically printing characters on a tape member; means for feeding the tape from said device to a scanning member, means for scanning the tape member, means for converting the scanning results into electric cur rents and means for reproducing the record.

2. In a transmission system for transmitting intelligence, a device for mechanically printing characters on a tape member, means for feeding the tape from said device to a scanning member, means for scanning the tape member, means for converting the scanning results into electric currents, and means for modulating therewith a radio transmission circuit.

3. In a transmission system for transmitting intelligence, a device for mechanically printing characters on a tape member, means for feeding the tape from said device to a scanning member, means for scanning the tape member, means for converting the scanning results into electric currents, a radio transmission circuit and means for impressing said electric impulses thereon to vary the transmission thereof.

4. In a transmission system for transmitting intelligence, a typewriter, a tape for receiving printed characters from the typewriter thereon A strong static disfrom the typewriter, means for feeding the tape from said device to a scanning member, means for scanning the tape member, means for converting the results into electric currents and means for impressing the same on a transmission circuit.

5. In a transmission system for transmitting intelligence, a typewriter, a tape for receiving printed characters from the typewriter thereon from the typewriter, means for feeding the tape from said device to a scanning member, means for scanning the tape member, and means for converting the scanning results into electric current.

6. In a transmission system for transmitting intelligence, a typewriter, a tape for receiving printed characters from the typewriter thereon from the typewriter, means for feeding the tape from said device to a scanning member, means for scanning the tape member, means for converting the results into electric currents, means for impressing the same on a transmission circuit, and means for reproducing the record.

7. A unitary system comprising a travelling tape, means for mechanically printing characters on the tape, means for feeding the tape from said device to a scanning member, means for causing a light beam to scan said tape after the record has been made, means for converting the scanning results into electriccurrent and means for reproducing the record.

8. The method of transmitting Wir ess messages which comprises forming printed characters on a tape by the action of a typewriter scanning the tape, by causing a light beam to scan the same, converting the scanning results into electric impulses and reproducing the record.

9. In the art of detecting bodies by means of heat Waves emanating therefrom, means for scanning an object to be observed, means responsive to the scanned heat Waves for producing a picture of the object and local heat emanating means cooperating with the scanning means for fixing the position of the body.

10. In the art of detecting bodies by means of heat waves emanating therefrom, means for scanning an object to be observed, means responsive to the scanned heat Waves for producing a picture of the object and local heat emanating means comprising a reference wire adapted to be heated cooperating with the scanning means for fixing the position of the body. Y

11. In combination with a television transmitter in the art of transmitting color images 5 or vision by electric impulses, a lens system having transverse sections of difierent absorbent material and a prismatic reflecting mirror of varied colored faces adapted to reflect successive faces on different sections of the lens.

' 12. In combination With a television transmitter in the art of transmitting color images or vision by electric impulses, a lens system hav- 'ing transverse sections of different absorbent ma-

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