US1648127A - Transmission of pictures by electricity - Google Patents

Description

Nov. 8, 1927.

" H. E. IVES TRANSMISSION OF PICTURES BY ELECTRIGITY 2 Sheets-Sheet 1 Filed May 6, 1924 RVSA-D RPF RSF

Nov. 8, 1927.

H. E. IVES TRANSMISSION OF PICTURES BY ELECTRICITY Filed May 6, 1924 2 Sheets-Sheet 2 Patented Nov. 8, 927.

, 5 UNITED STATES. PATENT oFF aEi HERBERT E. IVEsYoE MoNToLAIR, NEW JERSEY, ASSIGNOR To WESTERN E'LEcTRIcooMrA Y, INCORPORATED, or NEW YORK, N. Y., A CORPORATION or NEW YORK.

TRANSMISSION OF PICTURES BY ELECTRICITY.

Application filed May c.1924. Serial Nb. 711,333.

This invention relates to means for transmitting pictures by electricity and more particularly to an arrangement. for operating the scanning mechanism.

In systems heretofore known employin revolving drums for helical scanning,'some mechanism has always been provided to return the drum to a given position after the transmission of each picture and before starting the transmission of another picture. Various devices have been employed. All have had their characteristic defects. Some were too complicated or delicate tobe practicable. Others required too much operat ing time. All were therefore expensive and uneconomical. 1

-An object of the present invention is to economize operating time in such a system without sacrificing simplicity and reliability.

In one embodiment of the present invention, the equipment of a picture transmission system employing transmitting and reproducing drums is so arranged that a picture maybe transmitted while the drums are moving in eitherdirection. The drums are driven by reversible La- Cour motors. As the drums rotate they also move axially with respect to the optical portions of the system. The entire picture surface is thus traversed while the drums move axially" from one end to the other in either direction. Each motor is coupled to its respective drum through a friction drive, the movement 'of the drum being controlled by a magnetically operated detentwhich prev vents rotation in either direction. The motors are synchronized over one voice frequency carrier current channel while the picture characteristics are transmitted as modulations of another voice frequency'carrier current channel of difierent frequency.

The novel features which areconsidcred characteristic of this inventionare set forth with particularity in the appended claims. The invention, both as to its organization and method of operation together with other olg'ects and advantages thereof,- will be further explained in the following descri tion having reference to thev accompan ing rawin s consisting of the following gures:

ig. 1 is a schematic circuit arrangement of the transmitting terminal equipment.

Fig. 2 is a schematic. circuit arrangement of the reproducing terminal equipment.

' Fig. 3 shows the mechanical arrangement of the magnetic detent.

Fig. 4 is a cross sectional view of the arrangement of Fig. 3. I

The general arrangement of the system is similar to that shown in a copending application of M. B. Long, Serial'No. 681,347,

filed December 18, 1923 and reference may be had thereto for a. more detailed description of the system than is'gi'ven hereinafter. The same'referencecharacters are used in the several figures to designate the same. elements;

The terminal equipments of Figs. 1 and 2 are each shownconnected to a line'L. The complete system is accordingly shown by connecting line L of Fig. 1 to line L of Fig. 2 through any circuit-suitable for transmitting ordinary telephonecurrents such, forexample, as an ordinary telephone line, a

carrier current telephone channel or a radio telephone channel.

Referring now to Fig. 1, a sending drum 5 is driven by a phonic wheel or La Cour motor 6 by means of a shaft shown diagram matically by dotted lines. The coupling between drum 5 andthe, phonic wheel 6 is through a friction clutch 7. The phonic wheel 6 'isitse1f driven by tuning fork SF in. well known manner. An oscillator-amplifier SQ-A. supplies. carrier waves to the line L through a circuit 8 and low-passjfilter SSF. A contact9 on the tuning fork SF short-circuits circuit 8 periodically at the frequencycf vibration ofithe tuning fork SF. At the reproducing terminal of Fig. 2,

these synchronizing waves are transmitted through low-pass filter "RSF to an amplifier-detector RSA-D, detected current from which drives the reproducing tuning fork RF by means of a driving magnet 10. The

receiving fork RF drives phonic wheel 11 in well known manner which in turn drlves reproducing drum 12 through friction clutch '13 and shaft 14.. The shaft is shown diagrammatically by dotted lines.

At the transmitting ,terminal of Fig. l, th'e photo-electric cell 15' inside of sending drum is connected to the input circuit of picture current amplifier PCA. Light from'a lamp.

17 is focused by means of lens 18 upon the parent. On the surface of drum 5, a trans- I surface of the sending drum 5 which is transparency of the picture tube transmitted is secured and lightfrom the source17-passing through this transparency of the picture into the photo-electric cell 15 causes a varying cure rent to flow through the photo-electric cell and to be impressedupon the input circuit of picture current amplifier PCA. The output-circuit of the picture current a'mpllfier .PCA is connected to the input circuit of the .modulator PM. An oscillator PO supplies the carrier waves for the transmission of the picture characteristics. These waves are amplified in an amplifierMCA and; then transmitted to the line L through a high-pass Waves from the oscillator PO maybe impressed upon the amplifier MCA by either one of two paths. One path extends from the 27, and potentiometer 28 to amplifier MCAQ The energizing circuit for the upper winding of relay 27 includes battery 46, switch 47 and relay 48. If this energizing circuit is opened at switch 47, the lower winding of relay 27 is efiective to close contact 26. When switch 47 is closed (as shown) the upper winding of relay 27 is efiective to'close eontact 29. Under this same condition, armature 49 of relay 48 is attracted and locks the sending drum 5 against rotation in either direction.

At the reproducing terminal of-Fig. 2, picture carrier waves from the oscillator P0 are transmitted by high-pass filter RPF, amplified by amplifier EPA and impressed upon reproducing demodulatorfRPD. Connected in the output circuit of demodulator" RPD is a battery 30, movable strin -31 of light valve. V and winding 32 of re ay 33. 'Themovement of the string 31 of light valve V controls the amount of light from lamp 43 which may affect a sensitive light recording blank or film secured to the reproducing drum 12. The light from the lamp 43 is directed first upon the movable spring A, 31 of light valve V. An image of the opening formed by the string 31 is then focused contact 35 by battery 37.

upon the surface of the drum by the lens as shown. I

The armature of relay 33 is held in the position shown with contact 34closed by thecurrent flowing in-the winding 32 when carrler -waves are impressed upon the input circuit of demodulator RPD. When such waves are not being received, the armature.

of relay 33 is moved into a position closing current 1n winding 36 from :The closure of switch 38 completes a circuit for relay 39 through battery 40 The c urrent in relay 39 attracts its aianature 41 to lock drum 12 and prevent its rotation in either direction. Another circuit for relay 39 through battery 40 is closed when contact 34 of relay 33 is closed even though the switch 38 is opened. It is to be noted that the closure of switch 38 forms a' short circuit about the contact 34. A circuit which is completed by the closure of which 42 and contact 35, forms a short-circuit about the winding 32 of relay 33.

The well known three-electrode electron discharge devices are preferably used throughout the system for the oscillators, modulators, demodulators and amplifiers. The filtersare'designed according to the principles set forth in Campbell Patent No. 1,227,113, May 22, 1917.

The detent mechanism will now ,be described with reference to Figs. 3 and 4. The same mechanism may be used at both the transmitting and reproducing terminals. It

will therefore be described by using only the reference characters 'of the transmitting terminal of Fig. l. The magnet 39, armature 41 and drum 12 of .Fig. 2 correspond respectively, to the magnet 48, armature 49 and drum 5 of Fig. 1.

The drum 5- and the detent mechanism in- I eluding magnet 48 and armature 49 are mounted on a carriage 50 which may slide back and forth along guides 51 mounted on a frame 52. The threaded shaft 53 is. geared to shaft 54 so that their speeds of rotation bear a definite relation to each other. Preferably, this speed ratio is unity. The threaded shaft 53 engageswith screw collar 55 attached to the frame 50 so that the rotation of shaft 53 causes the movement of frame 50 along the guides 51. Mounted on the shaft 54in fixed relation thereto is a collar 56 which has a square notch 57 cut in its periphery. The notch 57 is just large enough to receive one end of the armature 49 which drops into the notch when the magnet 48 is energized .and so prevents rotation'of the drum 5 in either direction. When drum 5 is held stationary, shaft 53 is prevented from rotating and movement of the frame 50 with respect to the guides 51 is prevented. The armatu1'e'49 is normally held out of engagement with the collar 56 by a spring 58.

Method of operation.

The method of operation willnow be de-" scribed.

Drums 5 and 12 are set at one end or the other of their axial travel. A transparency of the picture is placed on drum 5 and a sensitive record blank is secured to drum 12. Switch 47 is closed which locks drum '5 through the energization oft relay 48 and closes contact 29 of relay 27. Switch 38 is closed which locks drum 12 by the ehergization of relay 39. Switch is kept open.-

The transmission apparatus, such as the oscillators, amplifiers, etc, are then energized. Synchronizing carrier waves from the oscillator-amplifier SO-A are transmitted lator RPD. Demodulated current flows in string 31 of light valve V and winding 32 of relay 33 to close contact 34. v Tuning fork SF is then set in vibratio and phonic wheel 6 is started in such a direction as to tend to move drum 5 toward its opposite end. The rotation of phonic wheel 6 tends to rotate sending drum 5 through fric tion clutch 7 but drum 5 is locked by armature 49 of relay 48. At contact 9 of fork contact 35 places a short-circuit around winding 32, so that the subsequent receipt of carrier current by demodulator RPD, upon the closure of contact 26, cannot again energize winding 32 to lock drum 12.

The varying tone values of the transparency of the picturecause varying currents through the photo-electric cell 15. Carrier waves from oscillator P0 are modulated by these varying currents after amplification in amplifier and PCS andtransmitted to demodulator RPD. Corresponding varying currents in the output circuit of demodulator RPDcauses. movement of the string 31 of ,light valve V so that the image of the aperture formed by string. 31 on the light record blank on drum 12 varies in accordance with the light'transmitted through the SF, the train of carrier waves from oscillator-amplifier SO -A .is periodically interrupted at circuit 8, so that trains, of waves are transmitted to the line L. These waves in amplifier-detector RSA-D cause impulses of current in driving magnet 10 to drive tuning fork RF in synchronism with tuning fork SF. Phonic wheel 11 is started in a transparency of the picture ,at the sending drum 5. g I

Atthe conclusion of the process, switch 47 is closed to lock transmitting drum 5. The

attendant at the reproducing station, observing that the movement of the light valve has direction tending to move cylinder 12 to its opposite end. The rotation of phonic wheel 11 tends to drive drum 12 through friction clutch 13 but is prevented from doing so by armature 41 of relay 39.

Switch .23 is now closed and switch 38.is

opened. Picture carrier; waves fromoscilla tor P0 are impressed upon the input circuit of modulator PM, the output circuit of which is open, however, at contact 26 of relay 27. Drum 12 is held in locked position by the energization of relay 39 through a circuit including contact 34. Everything is now in readiness to start the transmission of the picture. Phonic wheels 6 and 11 are rotating synchronously. Drums 5 and 12 are lockedagainst rotation. Light-valve V is energized by demodulated picture car rier waves.

To start the actual transmission, switch 47 is opened and left open during the transmissionprocess. The opening of switch 47 deenergizes relay 48 which unlocks sending drum 5. The. upper windingpf relay 2? is simultaneously deenergized so that contact 26 is closed and the output circuit 25 of modulator PM is connected to. the inputcircuit of amplifier MCA.

During the time that the armatureof re lay 27 is moving from contact 29 to contact 26, the picture carrier waves are. interrupted.

ceased, can either open switch 42 or close switch 38 o both to lock the reproducing drum 12.

The direction of rotation of phonic wheels- 6 and 11 is now reversed. Another light sensitive record blank is placed on drum 12. If a different picture is to be transmitted, a transparency of such picture is placed on sending drum 5. The same transparency is of course used if it is desired to transmit the same picture. If switch 42 only had been previously opened to lock reproducing drum 12, it may now be closed and the system is in readiness to transmit another picture. If switch 38 had also been closed, it must be opened before the transmitting process can begin. The process of transmitting this second picture is the sameas that of the first except that the axial movement of the drums 5 and 12 is in an opposite direction.

When transmitting pictures, according to the present invention, no. time is lost between pictures in returning the sending andreproducing drums to starting positions. By the arrangement of this invention, the sending and reproducing drums at the finish 'ofone'picture are in position for the start- Such interruption allows the armature of reing of another. No complicated apparatus is required and a large saving in operating time is effected.

Various modifications of the specific embodiment of the invention which has been described may be made without departing from the scope of the invention as defined in the appended claims.

What is claimed is:

' 1. In a system for the transmission of picturesbyelectricity, optical means to scan successive elemental areas of a picture sur-- face in a predetermined sequence for the transmission of a picture and to scan the all I and means to rotate it in either oftwo; di-

disable said prevention means.

motions and simultaneously move it axially with respect to thescanning means.

2. In a system forthe transmission of pictures by electricity, a picture drum, means to illuminate a small area of the surface of said drum, means to rotate said drum in either of two directions and simultaneously move it axially with respect to 'said illuminating means, mean s to prevent motion of said drum in either direction, and means to 31 In a system for the transmission of pictures by electricity, a picture .drum, an optical arrangement to illuminate a small area of the surface of said drum, a friction drive for rotating said drum and moving it axially in either'of two directions with respect to saidoptical arrangement, a 'detent to prevent rotation of said drum in either direction, and Jelectromagnetic means for releasing said detent.

ls-In a system for the transmission of pictures by electricity, sending and reproducing picture drums, means torotate said drums synchronously and to move them' axially in either direction, means to prevent rotation of said drums, and meansto start them synchronously in either direction. v 5. In a system for transmitting pictures i'he pictures to be successively transmitted, means including a rotatableelement for re roducing the picture,.andmeans controlled y carrier waves from said source to control the rotation of said element in'either 40- direction. I .7 4

6; In a system. for the transmission of pictures by electricity, a circuit over which carrierwvaves are received, arep'roducing drum, a light valve, an electron'discha-rge in response to the receipt of carrier waves, means to unlock said-drum due to an interruption in receipt of said carrier waves and means to prevent a subsequent locking of said reproducing drum when carrier waves are again received.-

7. In an electrical system, a movable device capable of moving in either one oftwo directions, means to cause movement'of said device, a source of carrier waves, ,and meansv 7. under the eontrolof carrier'waves' from said source to effect the movement of said movable device in either direction.

In witness whereof, I hereunto subscribe my name this 29th day of April A. .D. 1924.

-HERBERT E. iv'ns.

45 demodulator, means to locksaid reproducing vdrum against motion'ineither direction

Images