US2098802A

US2098802A - Telepicture synchronizing system

Info

Publication number: US2098802A
Application number: US72991A
Authority: US
Inventors: William G H Finch
Original assignee: Individual
Current assignee: Individual
Priority date: 1936-02-26
Filing date: 1936-04-06
Publication date: 1937-11-09
Anticipated expiration: 1954-11-09
Also published as: US2071227A; US2133811A; US2089846A; US2145717A; US2069061A; US2048604A

Description

Nov. 9, 1937. w. G. H. FINCH 2,093,802

TELEPICTURE SYNCHRONIZING SYSTEM Original Filed Feb. 26, 1936 4 Sheets-Sheet 1 INVENTOR.

William Q xm'mh ATTORNEY.

Nov. 9, 1937. w. a. H. FINCH 2,098,802

TELEPICTURE SYNCHRONIZING SYSTEM Original Filed Feb. 26, 1936 4 Sheeis-Sheet 3 g Fig25 INVENTOR. unuian q. 71:41am B ATTORNEY.

Nov. 9, 1937.

W. G. H. FINCH TELEPICTURE SYNCHRONI Z ING SYS TEM 4 Sheets-Sheet 4 Original Filed Feb. 26, 1936 INVENTOR.

William 9. 14am};

i hvemi ATTORNEY.

Patented Nov. 9,- 1937 UNITED STATES PATENT OFFICE Original application February 2c, 1936, Serial No. 65,869, now Patent No. 2,047,863, dated July 14,

1936. Divided and this 1936, Serial No. 72,991

8 Claims.

This invention relates to synchronization of the rotating drum of a. telepicture receiver with synchronizing signals cyclically transmitted during the picture reception and is a; division of my co- 5 pending application Serial No. 65,869, filed February 26, 1936, which matured into Patent No. 2,047,863on'July 14 1936. In thetra'nsmission of pictures to remote points, it is essential that the receiver picture drum be-' vl in phase synchronism with the transmitter drum.

Many attempts hav'i been made to attain such phase synchronization. I It is extremely desirable to provide a positive driving connection between the motor and the revolving drum to avoid any deleterious effects due to friction coupling. In my Reissue Patent No. 19,575, I have disclosed a system for'connecting and disconnecting the positivedrivlng connection between the driving motor and the drum in response to synchronizing signals to maintain phase synchronization. In my present invention I utilize an over-running or positive clutch with means responsive to the synchronizing signals for maintaining the drum in phase synchronism. In oneembodiment I revolve the receiving drum at a slightly higher rate than the transmitter drum, in the ratio of 101 to 100, so as to establish the synchronizing pulse at a predetermined portion of the receiving drum, which portion will accordingly always be in position due to the increased speed ratio, to receive the synchronizing impulse.

To overcome the efiects of rotational inertia present in a large telepicture system having a large revolving drum, I provide a flexible mechanical coupling between the positive clutch and the receiving drum which permits momentary phase displacement due to accelerating or decelerating inertial forces and prompty automatically compensates for momentary phase dis- 40 placements.

It is accordingly an object of my present invention to provide a novel telepicture synchronizing system utilizing an overrunning or positive clutch at the receiving station.

Another object of my invention is to provide a mechanical flexiblecoupling in the positive drive for a revolving drum, which automatically compensates for any momentary phase displacement due to acceleration or deceleration forces.

A further object of my invention is to provide novel electromechanical clutch engaging and disengaging means, operative in response to synchronizing signals for maintaining the revolving drum in phase synchronization.

Other objects of my invention together with Figure l.

'for non-portable use.

application April 6,

the foregoing will become apparent in the following description in connection with the drawings in which: 7

Figure l is a plan view of a preferred embodiment of the telepicture receiver. 7 I Figure 2 is an enlarged broken cross-sectional view through the receiver drum and drive 01' Figure 3 is a cross-sectional view through Figure 2 showing a partially enlarged plan view of the drive mechanism and clutch trip levers. Figure 4 is aperspective disassembled view of the clutch mechanisms Figure 5 is a. cross-sectional view illustrating a fragmentary detail of the internal clutch roller assembly.

Figures 6, 7 and 8 are cross-sectional views taken respectively along 6 6, land 81-8 of Figure 2 showing details of the synchronizing clutch control mechanism.

Figure 9 is a modification of the synchronizing clutch control mechanism corresponding to Figure 7.

Figure 101s a cross-sectional view along l0- -l0 of Figure 9. 6

Referring to Figure 1, the telepicture receiver is mounted on a cast iron base ll if it is designed Synchronous motor l2 drives the receiver drum I3 through the overrunning clutch I4 and suitable gearing contained in housing l5. Synchronous motor I2 is connected by leads It to electrical supply lines H for electrical energization thereof. Reduction gearing I8 connects worm or feed screw l9 to spindle end 28 rotating with drum l3. If drum I3 rotates 100 revolutions per minute and 100 scanning lines per inch are used, the pitch of worml 9 and its rate of revolution will be designed to advance receiver carriage 2| at the rate of one inch per minute so that the scanning of the film 22 mounted on drum l3 will progress in a continuous helical path. The light beam 23 emanating from focusing system 24 inthis example is designed to be .01 of an inch in width to prevent translation overlapping. Carriage 2| houses the receiver electro-optical system and rides on 'V-tracks 25 and 26 with V-rollers 21 and 28.

The record sheet 22 is clamped upon drum I3 by clamping members 30. A scale is marked upon the drum in the underlap portion to indicate the length of the record sheet being used. The plurality of roller sections 3| are shown out of position and are used to aid in smoothly mounting record sheet 22 on drum I! in a. manner described in the parent application already referred to. Drum I6 is rotatably supported by pointed spindle 62 supported in tail stock 66.

Figure 2 is the broken cross-sectional view of Figure 1 through the axis of drum l6, illustrating in detail the mechanism for driving and mounting drum |6. The shaft 66 driven by the motor through the flexible coupling 66 rotates worm 66 which drives worm gear 61. The hub 66 of worm gear 61 is connected to the clutch driver 66 by projections 6| of the hub 66 into corresponding grooves in the clutch driver 66. The worm gear 61 and the clutch driver 66 are free to rotate upon the spindle 62. vThe housing |6 encloses the worm and pinion drive and contains bearing 66 which supports one end of the spindle 62. The opposite end 66 of spindle 62 is conical and coacts with the metallic insert 66 pinned to end plate 66 of drum i6 by pin 61, and supports drum |6. Metallic insert 61 attached to opposite end plate 66 coacts with the conical end 66 of the spindle 62 supported in tail stock 66. Hollow shaft 66 rigidly connects the

metallic inserts

66 and 61. Drum I6 is accordingly rotatably supported by the conical ends 66 and 66.

Figure 6 is a perspective illustration of the overrunning clutch'l6 disassembled to more clearly explain its operation. The clutch cam plate II is rotatably mounted within the clutch driver 66 upon spindle 62 (shown in dotted). There are four openings 62 on the surface of the cam plate which contain metal cylindrical rollers 66. The clutch stop plate 66 is fitted adjacent to the cam plate 6| and contains four pins 66 which eoact' with the cylindrical rollers 66.

Figure 6 is a sectional view through-the overrunning clutch |6 taken along 66 of Figure 2 illustrating the character of the recesses 62 in the cam plate 6|. The principle of the overrunning clutch is well known in the art. The rollers 66 are wedged between the inner surface 66 of the clutch driver 66 and the inclined surfaces 61 of the recesses 62. Plungers 66 set in cam plate 6| are forced against each roller 66 by springs 66 set within the camplate 6|. The

wedging action of the rollers 66 between surface 66 and inclined surfaces 61 serves as a positive connection between the clutch driver 66 and the cam plate or clutch driven member 6|.

Figure 5 is a cross-sectional enlarged detailed view illustrating the arrangement of a roller 66 and its stop plate pin 66 within a recess 62 of the cam plate 6| in engaged position where the plunger 66 is pressed against the roller 66 by spring 66 set in the cam plate 6|.

Referring to Figures 2 and 4, the hub 66 of cam plate 6| has a V notch 6| at one end thereof which coacts with a V projection 62 in the coupling member 66. Coupling member 66 has keyways 66 that slidably engage corresponding keys 66 set in the spindle 62. It is to be understood that the coupling member 66 is slidable axially on the spindle 62 and that this coupling member 66 provides the driving connection for the spindle 62 since no relative angular movement therebetween is possible.

Accordingly, when the overrunning clutch I6 is engaged the motor drive I2 is transmitted by the worm and pinion 66-61, the engaged clutch I6, and the coupling member 66 to the spindle 62. The face plate driver 66 is rigidly mounted on the spindle 62 by pin 61. A projection or key 66, on the face 66 of the face plate driver 66 sets into a corresponding groove'in the end plate 66 of the receiver drum l6. A positive driving connection pins 16 against the face 16 of the coupling member 66. A positive driving connection of coupling member 66 with cam plate hub 66 is had for all practical purposes in the operation of the system since the pins 16 maintain the engagement of v projection 62 and V grooves 6| during the driving cycle of the drum.

An important feature of my present invention resides in the automatic connection and disconnection of the positive or overrunning clutch l6 to maintain the revolving receiver drum l6 in phase synchronism with the transmitter drum (not shown). In my Re. Patent No. 19,575, is described one method for connecting and disconnecting the positive drive from between the source of motive power and the revolving drum. My present invention embodies the principle of the overrunning clutch in an instantaneous synchronization mechanism. Synchronization according to Re. PatentNo. 19,575 depends upon the actuation of a pawl engaging a ratchet wheel in the positive driving connection. The limits of phasing positions are accordingly within the pitch or width of one tooth of the ratchet wheel.

By employing an overrunning clutch, the positive drive is had during the rotation of the drum l6 and accurate phase synchronization is feasible at any point in the circumferential movement of the drum. The stop plate 66 contains the pins 66 which coact with the wedging rollers 66. when the cam plate 6| is driven by the clutch driver 66 during the wedging action of the rollers 66, the stop plate 66 is also driven and revolves with the cam plate 6|. However, I provide a notch 16 on the periphery of the stop plate 66 which is engageable with'a projection 16 on trigger lever 16 (Figure 7) which is mechanically biased by spring 11 toward the stop plate 66.

Figure 7 illustrates the engagement of lever projection 16 with the corresponding notch 16 in the stop plate 66. In this podtion the stop plate is prevented from further rotating counterclockwise, as indicated by the arrow. The pins 66 accordingly abut the rollers 66 within the overrunning clutch l6 and force the rollers 66 against the plungers 66 to disengage the clutch l6, as will be understood by those skilled in the art. The rollers 66 are moved along the inclined surfaces 61 releasing the wedging action of the rollers 66 from between the cam plate 6| and the inner clutch driver surface 66. The motor |2 continues to rotate the clutch driver 66 but the driving of the drum l3 therefrom is instantaneously discontinned.

A pawl 66 is mechanically biased toward the stop plate 66 by spring 6|. Pawl 66 projects into a notch 62 on the periphery of stop plate 66 at the instant the projection 16 of the trigger lever 16 engages the notch 16 in the stop plate 66. The pawl 66 accordingly prevents rebound of the stop plate when its notch is arrested, thus insuring a positive disengagement of the overrunning clutch |6.

Figures 3, 'l and 8 illustrate one modification for actuating the clutch M in response to synchronizing signals. For rapid engagement of the overrunning clutch M in response to synchronizing signals, falling weight 66 is caused to impact I the end 84 of the trigger lever I8, removing the projection from the notch 14 in the stop plate 84 and permitting the plungers 88 to wedge the rollers 83 between the cam plate 8| and the clutch driver 48. The movement of weight 83 is guided by post 85 through a hole in the center 01' the weight 83.

Figure 7 fllustrates the weight in its upper position. A projection 88 on the armature 81 of the synchronizing magnet 88 holds the weight 83 in its upper position in readiness for release. When a synchronizing impulse is impressed upon magnet 88 through its leads 89-98 in a manner well known in the art and described in detail in a the parent application, the armature is attracted toward the magnet 88 against the spring 9| permitting the weight 83 to drop and impact the end 84 of trigger lever 18 to drivingly engage the clutch l4 as illustrated in Figure 8.

The weight 83 is replaced to its upper position by means of the lever 92. A pin 94 projects from the surface of the stop plate 54 and once per revolution of the stop plate, the pin 94 presses the end 93 of lever 92 downward so that the opposite end 95 automatically raises the weight 83 to its upper position shown in dotted in Figure 8. Spring 9| moves the armature 81 away from the magnet 88 permitting the projection 88 to engage the bottom corner of the weight 83 to hold it in its upper position in readiness for its cyclical release. Figure 3 is a sectional view through Figure 2 showing the driving connections from the motor coupling 35 and is a plan view of the synchronizing levers 18 and 92, weight 83 and magnet 88.

The receiver drum I3 is maintained in phase synchronism by means of cyclically transmitted synchronizing signals during the underlap period of the transmitter drum (not shown). The receiver synchronizing cam I88 is mounted at the end 28 of the spindle 42 outside the housing l5 clearly illustrated in Figure 2. The subtended angle of the cam nib |8| may be made equal to the corresponding subtended angle of the underlap portion of the receiver drum 3 so that the receiver synchronizing switch I82 will be maintained open during this interval to cause synchronizing magnet 88 to be connected in the circuit of the receiver amplifier output as described in the parent application.

As there described, the amplifier is a class B amplifier and the tubes are biased to cut off, so that when no signal is impressed in the input circuit, zero plate current will flow and the synchronizing magnet 88 connected therein will not be energized until the synchronizing impulse is impressed. In my preferred embodiment, the synchronizing impulse is of a magnitude greater than the largest telepicture signal so that the synchronizing magnet will respond only to the synchronizing signals. 4

The parts of the receiver drum I3 are preferably made of aluminum to reduce its rotational inertia. The coupling member 83 coacting with the driven cam plate 5| of the overrunning clutch 4 acts as a shock absorber to resist the inertial resistance of the drum l3 during its starting from rest to synchronous speed, or of any inertial forces it may present during the synchronizing action.

When there is a tendency for the cam plate 5| to advance in phase with. respect to the coupling member 83, the coupling member will slide axially along the spindle 42 away from the clutch cam plate 5| and against the pressure of the pins 18 mechanically biased by springs 12. The V notches 8| of them hub 88, coacting with the v projections 82 of the coupling member 83, ei'- the V projections 82 into normal engagement with the V notches 8|. A spring I85 connects an eyelet pin I88 secured in the coupling member 83 and another eyelet pin |8| secured in the hub 88 of the cam plate 5|, as illustrated in Figures '7 and 8. Spring |85 facilitates the automatic return engagement of the V projection 82 in the V notches 8| of the corresponding members.

Since the coupling member 83 is slidably keyed or splined to the spindle 42 and the face plate driver 88 is rigidly keyed to the spindle 42, the receiver drum I3 is driven positively from the coupling member 83. The source of motive power I2 is connected positively to the clutch driver 48 as already described. When the clutch I4 is engaged, a further positive connection is had between the clutch driver 48 and the cam plate 5|, by the wedging action of the rollers 53. The V connection between the hub 88 of cam plate 5| and the coupling member 83 is in effect a flexible positive coupling.

When the projections 82 normally engage notches 8|, the source of motive power |2 drives the receiver drum 3 through a positive driving connection. The relation of the hub 88 and coupling member 83 as already described is a flexible positive connection since it permits momentary changes in phase, but automatically returns to the normal phase relation. The synchronizing apparatus operating on the clutch stop plate 54 disconnects the positive driving connection between the source of motive power l2 and the receiving drum l3 at the positive or overrunning clutch 4 if the receiver drum 3 is not in phase synchronism with the transmitter drum (not shown).

It is to be understood that the receiver drum l3 rotates in synchronism and in phase with the corresponding transmitter drum, and that the carriage 2| simultaneously advances the impinging signal light beam 23 axially along the film 22 mounted on the drum |3 to record the picture being transmitted. The intensity of the light beam 23 sharply focused upon the film 22 varies in accordance with the shading of the picture being transmitted as is evident to those skilled in the art.

A modification of the synchronizing magnetclutch trigger arrangement is illustrated in Fig. 9 corresponding to Fig. 7. The synchronizing magnet I I8 corresponding to magnet 88 is mounted on abracket below the surface I I2 of the base The poles 3 ofthe synchronizing magnet ||8 project through the surface 2 to coact with the armature plate 4 attached to the trigger lever 18.

Figure 10 is a cross-sectional view throughthe magnet 8 illustratin how the armature plate H4 is arranged above the two poles ||3| l3 of the electromagnet H8 and how the trigger end 5 is positioned between the poles |3| l3. The trigger I8 is accordingly directly actuatedby the synchronizing magnet 8 without the use of a the end 5 of falling weight 83 as in the hereinabove described modification. While the clutch I4 and stop-plate 54 are rotating, the lever 18 will be held in the dotted position of Fig. 9 so that the armature plate ill will be close to the poles ill of the magnet III. The peripheral surface oi the stop-plate 54 will abutthe trigger projection I5 and press the lever 18 toward the poles 3 against the action of the biasing spring 11. The armature plate ill will accordingly be close to the poles 3 of the magnet Ill during the major portion of the revoluflon oi the stop-plate H, but will tend to be moved away under the action of spring 11 when the notch ll comes in engaging position with the projection I5 oi the trigger 16.

It the drum i3 is in phase synchronism, the synchronizing impulses will arrive at the synchroniaing magnet ill thru leads iii-i II in time to hold the trigger 16 away from engagement with the stop-plate notch 14 and permit the drum II to continue in phase synchronism. It is to-be understood that if the drum I8 is out of phase synchronism, the notch 14 will engage the trigger projection 15 to disengage the positive or overrunning clutch l4. When the synchronizing signal is received by the magnet iili the stop-plate 54 is released and the clutch reengages to rotate the drum in proper phase synchronism.

I claim: v

1. In a signalling system, a source of motive power; a driven member; a driving connection between said source oi motive power and said driven member including means carried by said driving connection for disengaging said driving connection when said means is held against rotation; mechanism for arresting the rotation of said jmeans when said driven member approaches a predetermined angular position 9. synchronizing magnet responsive to received cyclic synchronizing signals; and a weight positioned above said mechanism, releasable by said magnet against said mechanism for rendering said arresting mechanism ineffectual during synchronous condition.

2. In a signalling system, a motor; a rotatable member; a clutch connecting said motor and said rotatable member including a disc carried by said clutch for disengaging said clutch when said disc is held against rotation; mechanism for arresting the rotation of said disc when said rotatable member approaches a predetermined angular position comprising a lever containing a projection mechanically biased against the periphery of said disc for engaging a notch on said periphery to disengage said clutch; a synchronizing magnet responsive to received cyclic synchronizing signals; and a weight positioned above said lever, releasable by said magnet against said lever for moving said lever projection away from said periphery to permit rotation of said rotatable member in synchronous condition.

3.- In a telepicture system, a motor; a scanner; a positive driving connection between said motor and said scanner including means carried by said driving connectionior disengaging said driving connection when said means is held against rotation; mechanism for arresting the rotation of said means when said scanner approaches a predetermined angular position comprising a member containing a projection mechanically biased against said means for engaging with'said means to disengage said driving connection; a synchronizlng magnet responsive to received cyclic synchronizing signals; and a weight positioned above said member, releasable by said magnet against said member for cyclically rendering said arresting mechanism ineflectual in response to the synchronizing signals; and means for cyclically restoring said element above said member between synchronizing signal conditions.

4. In a telepicture system. a motor; a scanner; a clutch connecting said motor and said scanner including a disc carried by said clutch for disengaging said clutch when said disc is held against rotation; mechanism for arresting the rotation of said disc when said scanner approaches a predetermined angular position comprising a member containing a projection mechanically biased against the periphery of said disc for engaging a notch on said periphery to disengage said. disc; a synchronizing magnet responsive to received cyclic synchronizing signals; and means controlled by said magnet for moving said member projection away from said periphery including a weight movable against said member, and an armature for said magnet containing a projection for supporting said weight above said member.

5. In a signalling system, a source of motive power; a rotatable member; a driving connection between said source of motive power and said rotatable member including a disc carried by said driving connection for disengaging said driving connection when said disc is held against rotation; mechanism for arresting the rotation of said disc when said rotatable member approaches a predetermined angular position comprising a member containing a projection mechanically biased against said means for engaging with said means to disengage said driving connection; a synchronizing magnet responsive to received cyclic synchronizing signals; and means controlled by said magnet for rendering said arresting mechanism ineiiectual including a mass for impacting against said member, and an armature for said magnet for supporting said mass above said member; and apparatus for cyclically raising said mass into engagement with said armature.

6. In a, telepicture system, a motor; a scanner; a clutch connecting said motor and said scanner including a disc carried by said clutch for disengaging said clutch when said disc is held against rotation; mechanism for arresting the rotation of said disc when said scanner approaches a predetermined angular position comprising a lever containing a projection mechanically biased against the periphery of said disc for engaging a notch on said periphery to disengage said clutch; a synchronizing magnet responsive to received cyclic synchronizing signals; means controlled by said magnet for moving said lever projection away from said periphery including a mass for impacting against said lever, and an armature for said magnet containing a projection for supporting said mass above said lever; and apparatus for cyclically raising said mass into engagement wit the projection of said armature.

'1. In a telepicture system, a motor; a scanner; a clutch connecting said motor and said scanner including a disc carried by said clutch for disenaging said clutch when said disc is held against rotation; mechanism for arresting the rotation of said disc when said scanner approaches a predetermined angular position comprising a member containing a projection mechanically biased against the periphery of said'disc for engaging a notch on said periphery to disengage said disc; a synchronizing magnet responsive to received cyclic synchronizing signals; means controlled by said magnet for moving said member projection away from said periphery including a weight movable against said member, and an armature for said magnet containing a projection for supporting said weight above said member; and apparatus for cyclically raising said weight into engagement with said armature comprising a member, and a pin projectingfrom said disc, one end of said member coacting with said weight and the other end of said member being moved by said pin once per revolution of said pin.

8. In a telepicture system, a motor; a scanner; a clutch connecting said motor and said scanner including a disc carried by said clutch for disengaging said clutch when said disc is held against rotation; mechanism for arresting the rotation of said disc when said scanner approaches a predetermined angular position comprising a lever containing a projection mechanically biased against the periphery of said disc for engaging a notch on said periphery to disengage said clutch; a synchronizing magnet responsive to received cyclic synchronizing signals; means controlled by said magnet for moving said lever pro jection away from said periphery including a weight movable against said lever, and an armture for said magnet containing a projection for supporting said weight above said'lever; and apparatus for cyclically raising said weight into engagement with the projection of said armature comprising a pivoted member, and a pin secured to said clutch, one end of said member coacting with said weight and the other end of the said member being moved by said pin once per revolution of said pin, a rod for guiding the movement of said weight, said weight being raised on said rod by said member above said armature projection, a spring for biasing said armature towards said weight for retaining said weight in its upperposition until released in response to a cyclic synchronizing signal whereby said scanner is connected to said motor in synchronous relation with said signals.

WILLIAM G. H. FINCH.