US2615148A - Electrical control means for driving mechanisms - Google Patents

Description

Oct. 21, 1952 c H A 2 ,6.1 5,148

ELECTRICAL CONTROL MEANS FOR DRIVING MECHANISMS Filed Feb. 18, 1950 INVENTOR DAVID J. CR/T PH LZL R) Z I BY I M *7 Patented Oct. 21, 1952 UNITED STATES:

RATENT OFFICE ELECTRICAL CONTROL MEANS FOR DRIVING MECHANISMS David I. Critoph, Lancaster, N. Y assignor to American Optical Company,

Southhridge,

6 Claims. 1

This invention relates to film winding mechanisms and the like, and more particularly to such a winding mechanism including an electric motor, a speed-changing device and an electrical con trol system constructed andarranged to control sameduring the transportation of strip film and the like, at high speed in either direction across the film gate aperture of a projector or the like for rapid winding r rewinding purposes and also to move the film in either direction across said aperture at any desired and readily selectable slow speed Within a predetermined slow speed range. This invention is an improvement over that disclosed by copending application Serial l lo. 63A17, filed December 1948 and which issued September 16, 1952, as Patent No. 2,6105%.

In said copending application is shown and described a film driving mechanism employing an electric motor and an electrical system for controlling both the high and slow speed operations of said motor and driving mechanism. While this film driving mechanism has proved to be highly successful and. extremely versatile in its ability to transport strip film at high speeds in either direction for Winding and rewinding purposes and also at various readily selectable slow speeds in either direction for scanning, centering and the like, it has not been completely satisfactory.

For example, While the motor thereof has been required, on the one hand, to operate at any selected slow speed, even as slow as thirty to forty armature revolutions per minute for slow speed scanning at high image magnifications, on the other hand this armature has also been re quired to operate during rewinding and the like at speeds as high as or even higher than twelve thousand revolutions per minute. Obviously, the bearings, commutator and other parts of the motor and driving mechanism operating under such vastly different operating conditions must be of the very finest and sturdiest construction. The clearances and such in the operating parts must be kept at a minimum for high speed operation, While for very slow speed operation the friction and drag must be as little as possible in order to avoid any noticeable influence thereof, such as jumpiness 0r hesitancy of movement of the projected image upon the viewing screen, particularly at high image magnifications. The mere use of a higher gear-ratio in the driving mechanism, while useful in reducing the very high armature speeds, would not alone improve the mechanism since it Would likewise increase the slowest slow speed of film travel, makin it 2 travel much too fast. Also it is impractical to attempt to use a motor havin a higher armature speed. Furthermore, it has now become desirable to move the strip 'film across the projection aperture at even greater winding and rewinding speeds.

It has been found, however, that the objec tionable conditions referred to above may be overcome, while still retaining the several advantages mentioned in said earlier copending application, by the use of a series type electric motor and electrical control system therefor employing a similar thermionic phase-shift power supply system, and by using therewith electrically controlled speed-changin means incorporated therein and arranged to operate in proper timed relation with the operation of said motor. A's high or even higher film speeds may be had by this improved apparatus at lower armature speeds in the high speed range, and also higher armature speeds may be obtained at the slowest film speeds in the slow speed range of operation of the apparatus, thus obtaining in this slow speed range of operation a smoother or more even movement of the image upon the viewin screen.

The change-speed means of the present invention includes two sets of constantly meshed change-speed gears for delivering power from the motor at diiierent gear-ratios to the film driving mechanism and suitable positive clutch and clutch shifting means energized by an electrical solenoidor the like. The system for controlling the solencid is constructed and arranged to transfer from one set of gears to the other during operation in such a manner or timed sequence that regardless of whether a change from low to high speed operation or from high to low is being effected an equalizing action will occur before the elements of the clutch means attempt to engage. This prevents any appreciable noise or clashing, as Well as wear, or strain, from occurring in parts of the film drivin mechanism. At the same time, the construction and arrangement or parts are such that a positive clutching action is always assured without any appreciable lag occurring in the changing from 1 low to high, high to low, or even during the reversing of directions of film'travel.

It is accordingly an object of the present invention to provide for use with a film winding mechanism or the like, readily controllable driving means including a series type electric motor, a speed-changing device and an electrical system including thermionic power supply means, a phase-shifting circuit therefor and electrical means for actuating said speed-changing device for effecting high and low speed operations in either direction.

Other objects and advantages of the invention will become apparent from the detailed description which follows when taken in conjunction with the:ac'companyingdrawing in which:

Fig. '1 is "a-side view, partly in section, of a gear-changing mechanism, motor drive means therefor and electrical means for changing the gear ratios thereof, as well as .a diagrammatic showing of an electrical system for controlling the operation of said motor; and

Fig. 2 is a diagrammatic showing of amodification of a part of the electrical system of .Fig'l.

Referring to the drawingin detail the numeral 10 indicates generally a mainsupporting bracket for the driving mechanism which may have its base l2 attached by suitable means such-'asibolts I2 to a structural part .14 of a microfilm projecitor1or the like. .This bracket l isarranged .to support an electric motor l5 and power .transmission gearing associated therewith in :position so thatja suitable film winding mechanism,-such as the'mechanism shown bythe vcopending application mentioned above or by the Gradisar Patent No. 2,482,666, issued September 20, 1949, in engagement with a drivinggear [6 may be operated thereby. The bracket ID has a-portion H extending downwardly from the base portion l2 and provided with outwardly extending bracket arms 18,20 and 22 for carrying parts .of the mechanism. The arm i22 is.of.suitab1e size and arranged to receive a pluralityof attaching bolts 24 :whichserve through .the medium of .resilient -vibration .dampening means .26 .andspacing .bush .ings .28 to attach .a motorsupport plate .30 .in .a suspended position .and .to this plate .is attached the-motor IS. The motor hasareduction gear- .ing.32 incorporated therewith, .said gearingpref- -.erably being of a fairly high gear ratio, in the neighborhoodbf approximately 36 to 1.

The-motor 15 :has a power shaft38 connected by a resilient coupling 40 to an intermediate .power shaft 42 carriedin bearing in the bracket arm 18 and .upon this intermediate shaft 42 are pinned or otherwise secured a .high speed gear 44 and a low speedrgear 46. .Also carried by the bracket arm 18 in suitable ball bearings or the like 48 and .50 .are apair .oflpositive clutch elements .52 .and 54, .resp.ectively,-of a type having radially extending teeth and upon the former is secured .a relatively small gear 55 and .upon thelatter is secured a relatively large gear 5.8. These gears 56 and 58 are retained against axial displacement by their supporting ballbearings so that they are at all times in mesh with gears 44 and 46 respectively.

The .clutch members 52 and 54 are each of a hollow construction so that a drive shaft 60 having one end portion j ournalled in bracket arm 20 may extend through .these clutch elements. Upon this shaft .80 are pinned or otherwise secured a pair of complementary clutch elements 62 and 64 so spaced thereon that when shaft 60 is moved downwardly axially from its .upper position as shown in the drawings to its lower position, in a manner to be presently described, clutch element 62 will be disengaged from element 52 slightly before clutch element 64 engages clutch element v54. Supported upon an extension 22 of the lower bracket arm 22 is an electric solenoid 66 having a movable core '61 carrying a pin 68 in an end thereof so that a lever which is pivotally mounted at '12 on the upper end of extension 22 may have a slotted end thereof 10 in engagement with said pin 68 and its opposite free end positioned so as to engage at 14 the lower spherically shaped end of the shaft 60. A suitable thrust bearing may be employed at 14 if desired.

The opposite end of shaft 60 is :arranged to drive the driving gear 16 which has an intermediate portion I6 rotatably supported by ball bearings 18 carried in the base portion I2 of the bracket [0, and this gear is retained against axial displacement by said ball bearings 18. There is provided, however, between a lower end portion rTGofthis gear 16 and shaft 60 a splined connection :or equivalent connecting means, as

indicated 'at.80,..for allowing shaft 60 to be shifted axially .in an upward direction by solenoid 68 or in the opposite direction by a coil spring 82 encircling the lower portion 16 of this gear.

An electrical system ifor controlling the operation of the driving and change-speed mechanism just .described .is diagrammatically shown also in Fig.1. This system'is provided with a temperature responsive switch .84 which closes within a veryfewsecondsafter a connector 86 on an electricallead V8!; is connected with a suitable source of alternating current since thermo-switch .84 has a filament connected to the secondary of .a filament transformer 88, the primary of which is connected to said lead. The secondary of transformer .88 is also connected to the'filament of a gas filled thermionicpower transmitting tube preferably of .the well-known thyratron type. Accordinglvby the time switch 84 has become heated sufficiently to close, the thyratron tube will'be.sufiiciently'heated and .ready'to operate. The device may then be operated at either high or slow speeds in either direction dependingzupon the position of a control switch 89 .without'further delay. For Iliigh speed operation it is not necessary to wait'for .tube 85 and switch 84 to warm up. The motor will operate immediately after control switch 89 hasbeen moved into its high speed position.

In the drawing, acontrol arm 89 of the switch 89 is :shown in a neutral position. If this control arm, pivoting aboutflxed axis 90, is moved to a first position "to the left asindicated by the dotted line L1 a circuit "will be completed and a rectified D. 0. current will flow through conductor 9!,thyratron tube, thermo-switch 8'4 and conductors 92 and SZ'to and through the control switch 84, and a conductor 93 connected'to one lead of the armature of themotor l5. The currentwill then flow from the opposite armature lead through conductor 94, switch '83, through the conductor 9.6 'to the field coil of the motor and from the opposite field coil lead thereof to the conductor 98. Accordingly, the motor will be operated in a first direction by D. C. current at slow speeds in accordance with the particular setting to which a variable resistance I00 is adjusted, controlling a phase-shift network embodying resistance [02 and capacitor I04 coupled to the control grid 106 of the tube 34 and to the opposite side of the transformer secondary from that to which the cathode of the thyratron is connected.

Likewise, if the control lever 89 is shifted to a first position R1 to the right half wave rectified D. C. current will flow through conductor '92, to and through the switch 89, through conductor 94 connected to the motor armature, through the armature in the opposite direction than that previously described and from the from its opposite side to conductor 98.

it will be seen that while the motor will again operating speed.

other lead of the armature through the conductor 93, through switch 89 to the conductor 96 connected to the field coil'of the motor and Thus,

be operated on D. C. current at slow speed, it

will be rotated in the opposite direction.

Also provided on switch 89 are a pair of contacts I08 and III] which are so built or adjusted as to be out of contact with the intermediate contact [I2 of the switch at the times the switch 89 is in the R1 and L1 positions and thus no current will flow from conductor H2 to either contact I08 or III]. However, should this control arm 89' be shifted further to the right to a second position R2 for high speed operation in said second direction, conductor II2 will engage contact I08 somewhat before the R2 position is reached. Accordingly, current in the conductor H4 for actuating solenoid 66 may flow through contacts H2 and I08 and through conductor [IE to the solenoid 66 and then back to conductor 98 to complete a circuit for energizing the solenoid.

Thereafter, when position R2 is reached current from conductor H4 may flow directly through the switch 89 and the conductor 94 to the armature of the motor and from the armature through conductor 93, again through the switch 89 and through conductor 96 to the field coil of the motor and from the field coil to conductor 98, thus completing a circuit so that alelements 52 and 62 to be engaged before the motor changes from its slow speed D. C. operation to its high speed A. C. operation. Likewise, when the switch. 89 is returned from position Re to R1 the motor will return to its slow speed D. C.

operation (which return is almost instantaneously because of the'inherent braking action of this type of electric motor) before the conductor H2 breaks with contact I08 to energize solenoid 66., Thus the solenoid will not allow spring 82 to shift the shaft 60 and the movable clutch elements 62 and 64 until after the motor has ceased to operate on A. C. current and has slowed down materially, or even completely to its slow In similar manner, when the lever 89' is moved from position L1 to L2 the con.

ductor Iii! will engage with contact III) before position L2 is reached, thus first energizing solenoid 65. When the lever 89 is in position L2 current may flow from conductorIM through conductor Us to the switch 89, then through conductor 92 and back through the switch again to conductor 93 connected to a lead of the motor armature and from the other lead of the armature, through conductor 9a, through the switch to conductor 95 connectedto a lead of the motor field and. from the other field lead to conductor 98 for high speed operation directly up from the alternating current supply.

It may beat times more desirable to employ the modified electrical system shown in Fig. 2 for control of the motor speeds and the changespeedgearing of the invention. This modified construction comprises a slightly different switching arrangement, wherein the motor I5 may be operated in either direction at low speeds as before, rectified -D. C. current being supplied for this purpose by the thyratron tube through conductor 92A, and the switch 89A to the motor. However, when the switch 89A is moved fromits slow speed position to its second or high speed position, an A. C. current will then flow directly through conductor IMA to the switch contacts I20 or I22. as the case may be, then through condoctor I IEA to the solenoid 66A and then to conductor 98A completing a circuit for energizing the solenoid. The solenoid will then move downwardly to shift the clutch elements, as previously described, and will actuate a snap action switch I24 near the end of its stroke. This switch I24 is connected by conductors I26 and I28 to the conductors 92A and BIA, respectively, and thus current will not be required to flow through the thyratron tube but may pass directly to the switch 89A and motor for high speed A. C. operation. However, this high speed operation will not occur until" solenoid 65A has moved the shiftable clutch elements into position for high speed operation. Likewise, when switch 89A is returned to its slow speed position and solenoid starts to move upwardly, the snap action switch I24 will interrupt the A. C. current flowing therethrough and the motor will return to its slow speed D. C. operation before the solenoid has moved sufficiently to shift the clutch elements to their slow speed positions.

Having described my invention. I claim:

1. In a projection device having a film gate film winding means for moving strip film across said gate, the combination of a series type electric motor, a power transmission mechanism having a rotatable shaft operatively connected to said motor and a rotatable driving element operatively connected to said film winding means for actuating same, said mechanism comprising shiftable for changing the speed ratio of said driving element relative to said shaft, an electrical system for connecting said motor and said shiftable means to a source of alternating current and for controlling the operation thereof, and comprising an electric circuit including a switch, electric motor and a thermionic p wer transmitting tube, said tube being arranged so that its anode will deliver direct current to said motor when said switch is moved from an inoperative position to a first operative position to close said circuit, phase-shifting means for controlling the amount of direct current passing through said tube during the operation thereof, electrical means for actuating said shiftable for effecting an increase in speed ratio said driving element and said shaft, and econd electric circuit for connecting said electrical means to said source of alternating current including said. switch, said switch being movto a second operative position for closing second circuit and energizing said electrical means to first cause said increase in speed ratio and thereafter connectsaid motor directly to said alternating current source for high speed operation of said motor.

2. In a projection device having a film gate and film winding means for moving strip film across said gate in either direction, the combination of a series type electric motor, a power transmission mechanism having a rotatable shaft operatively connected to said motor and a rotatable driving element operatively connected to said film winding means for actuating same, said mechanism comprising shiftable means for relative to said'zshaft. an electrical. "system :for

. connecting saidmotor and said shiftablei means 'htola source of alternating current and for controllingsthe operation thereof, and comprising an electric-circuit including a switch having an in-.

: ation thereof, electrical means for actuating said :fshiftable'means for effecting an increase in'speed ratio between saiddriving element .andsaid shaft, and a second electric circuit forconnecting-said -.electrical.'means to said sourceof alternating current and including said switch,- 'said switch being movable to a second operative position in either direction for. closing saidsecond circuit and-energizing said electrical means to first cause said increase in speed ratio and thereafter con- .nectsaidmotor' directly-with said alternating current source for high speed operation of'said motor in the selected direction.

3. The combination of aseries 'type electric motor, a power transmission mechanism having a rotatable shaft operatively connected to said motorand a rotatable driving element for actu- "ating driving means or the like, said mechanism comprising shiftable means for changing the qspeed ratio of said driving element relative tov said'shaft, an electrical system for connecting said-motor andsaid shiftable means to a source :Ofr alternating current and for controlling the H 4 operation thereof, and comprising an electric circuit including a switch and a thermionic power transmitting tube, said tube being arranged so l-Jthat-itsanode will deliver direct current to said motor when said switch is moved from an in- -operative position to a first operative position to closesaid circuit, phase-shifting means for controlling the amount of direct current passing through said tube during the operation thereof, electrical .means for actuating said shiftable I means for effecting an increase in speed ratio between said driving element and said shaft, a 7 second circuit connected to said switch and to -said electrical means, and a third circuit for connecting said motor directly to said source of alter- --natingcurrent for high speed operation, said =switch-being arranged when moved from said t first operative position to a second operative positionto close said second circuit and energize said electrical means, and thereafter close said third circuit and cause highspeed operation of said it motor.

I 4. The combination of a series type electric motor, a power transmission mechanism having a rotatable shaft operatively connected to said motor and a rotatable driving element for actuating driving means or the like,-said mechanism comprising. shiftablemeans for changing the 'speedratioof said driving element relative to sa'id shaft, an electrical system for connecting said motor and said shiftable means to a source of alternating currentand'for controlling the operation thereof, and comprising an electric '=.circuitincluding a switch having an inoperative E position and a thermionic power transmitting -?tube,-said tube being arranged so that its anode :will delivertrdirecti current I to said motor when said switch moved from its inoperative; posi- -'tionto a first operative position to eithervside thereof to close said circuit and-cause rotation of said motorin either direction, phase-shifting means. for controlling the amount of direct current passing through said tube during operation thereof; electricalmeans for actuating: said shiftable means for effecting an increase in speed ratio between, said driving element and-said shaft, a second circuit connected to said'switch and to said electricalmeans, and, a'third :circuit controlled for connecting said motor directly to said source of alternating current: iorhigh speedoperation thereof in the selected direction, said switch being arranged-when movedfrom its first operative position ineitherzdirection to a second operative position inthe same direction to close said-second circuit and energize. said electrical meansaand thereafter closersaidthird circuit, and cause high I speed operation of said motor.

5. In a projectiondevice having. afilm gate and filmwinding meanssfor-moving strip film across said gate, the combination of a series type electric motor, a power transmission mechanism having a rotatable shaft operatively, connected to said motor and a rotatable driving, element operatively connected to said filmiwindingl means for actuating same, said mechanism comprising shiftable means for changing the-speed ratio of said driving element relative to said shaft,- an electrical system for connectingsaid motor and said shiftablemeansto a sourceof alternating current and for controlling the operationthereof, and comprising an electric circuit including a switch and a othermionic power transmitting tube, said tubebeing arranged so that its anode will deliver, direct current to said motor, when said switch is moved from an inoperativeiposition-to a firstoperativeiposition, to close =-said circuit, phase-shifting means for controlling/the amount of direct current passing through said tube during the operation thereon electrical means for actuating said shiftable means'for effecting an increase in speed ratio betweensaid driving element and saidrshaft, a second circuit connected to said switch and to said electrical meansforenergizing the latter whensaid switch is movedinto a second operative position, and a third circuit for connecting-said motor directly to said source of alternating current forhigh -speed operation of said mo,tor,.said last named circuit including a pressure responsive, device actuated by movement of said electrical means mechanism comprising shiftable means for changing the speed ratio ofsaid driving element relative to said shaft, an eiectricalsystem for connecting said'motor and:said shiftable means to a source of alternatingcurrent and for controlling vthe operation thereof, and comprising an electric circuit including a switchhaving an inoperative position and a thermionimpower transmitting tube,-- said ,tube being arranged so that its anode will deliver direct current to said motor when said switch is moved from its inoperative position to a first operative position to either side thereof to close said circuit and cause rotation of saidmotor in either direction, phase shifting means for controlling the amount of direct current passing through said tube during operation thereof, electrical means for actuating said shiftable means for effecting an increase in speed ratio between said driving element and said shaft, a second circuit connected to said switch and to said electrical means for energizing the latter when said switch is moved into a second operative position in either direction, and

a third circuit for connecting said motor directly 15 to said source of alternating current for high speed operation of said motor, said last named 10 circuit including a pressure responsive device actuated by movement of said electrical means and shiftable means into a position to cause said increase in ratio to close said third circuit and cause said high speed operation of said motor.

DAVID I. CRITOPH.

REFERENCES CITED The following references are of record in the

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