US2200342A - Film-advancing device - Google Patents

Description

May 14, 1940- H. J. REARDN 2,200,342

l FILM-ADVANGING DEVICE Filed Aug. 25, 193s UNITED STATE sf lalrlI-:NTv ori-rica 2,200,342 v FmM-ADVANGING DEVICE Harvey J. Reardon, Chicago,A lll., assignor to Classroom Laboratories, Inc., Chicago, Ill'., a corporation of Delaware Application August 25, 1938, Serial No. 225,702

1 Claim.

'I'his invention relates to a nlm-advancing device forv motion picture projectors.

An object of the present invention is to im-A prove upon and simplify the construction of prior art nlm-advancing devices.

Another-object of the present inventionis to reduce the number of operating parts required to move the film-advancing claw or member during or throughout its operative cyc1e, and hence -to reduce correspondingly the wear andl friction on the working parts o f the film-advancing device.

An additional object of the present invention is to eliminate one of the two rear or back cams w which have heretofore customarily been used in' film-advancing mechanism for imparting the back and forth or longitudinal movement to the film-advancing claw, and to operate the filmadvancing claw by means of a single front cam 90 and a single back cam, as distinguished from the two rear or back cams and the one front cam which have customarily been used heretofore in film-advancing devices of a somewhat similar or analogous type. 1

Fig. 1 is a view of the new film-advancing device, partly in section and partly in top plan, and showing the same applied to a motion picture projector;

Fig. 2 is a vertical sectional view on line 2-2 in Fig. 1 and showing the film-advancingv member or claw in operative, that is, in effective or film-feeding y position;

Fig. 3 is a horizontal sectional view on line '3 3 in Fig. 2; 85 Fig.' 4 is a side elevational view, partly in section, showing the operating parts ofthe new filmadvancing device, partly in section, and as seen from the side opposite which is shown in Figs. 2, 5 and 6;.v v

Fig. 5 is a view partly in side elevation and partly in section and showing the parts of the new film-advancing device in the position which they assume when they are about to engagelthe film and initiate the film-advancing operation;

Fig. 6 is a view similar to Fig. 5 but showing the parts of the new film-feeding device in the position which they assume at the end of each film-advancing operation; Fig. '1 is a perspective view of the n ew film- 50 advancing member or claw; and

Fig. 8 is a fragmentary detail View illustrating a slightly modified form of the film-advancing claw which is embodied in the new lm-advancing device.

A preferred form of the new nlm-advancing device 'is shown in Figs. 1 to 7, inclusive, of the drawing, is therein generally indicated at I0, and comprises a driving member or shaft II and a driven member or shaft I2, both of vwhich are rotatably mounted or journaled in bearing surfaces I3 and I4, respectively, which are provided in a supporting frame I5; the driving shaft II vbeing operated by any conventional power-driving means which is known to or used in the art,

the same being generally indicated at 42.

Carried by and fast upon the driving member orv shaft I I is a power transmitting element 'in the form of a gear I6 and this gear I6 meshes with another power-transmitting element in the form of a gear I'l which is carried by Yand is fast upon 315 the driven shaft I2; the speed ratio between the driving gear I6 and the driven gear I'I being preferably two to one, that is, the drivingl gear I6 is shown as being only one-half as large in diameter as the driven gear I'l, and hence the driving shaft II and gear I6 will make two revo,-

lutions `for each revolution of the driven shaft I2 I and-gear I1.

Carried by and fast upon the driven shaft I2, at the opposite end thereof from the driven gear I'l, is a cam I8 which as is shown in the drawing, is eccentrically mounted upon and relative to the driven shaft I2. Likewise carried by but floating upon the driven shaft I2,- outwardly of the cam I8, is a guide member I9, which, as best shown in Fig. 6, hasa flattened upper edge or face 20 and a flattened lower edge or face 2I, for reasons to be. explained hereafter; this guide member I9 being retained upon the driven shaft I2, and against axial movement thereon, by a nut 22 which is mounted on a threaded outer j end portion 23 of the driven shaft I2.

The new film-advancing device also includes a film-engaging and advancing claw or member, which is generally indicated at 24 (Fig. 7), and this claw or member 24 has a transversely extending fiange or cam surface 25 which projects substantially right-angularly from the body thereof at the rear end of the same, and this flange or cam surface 25 is adapted to be engaged by the peripheral edge or surface of the back or rear cam I8 at one stage in the operative cycleof the latter.

The film-advancing claw or member 24 also includes a pair of spaced upper and lower and longitudinally extending flanges or guide elements 26 and 21,'respectively, which project substantially right-angularly from the body of the said claw member 24, at the opposite side of the same from the flange 25 and, like the latter, at

or in the rear end portion of the claw or lm-advancing member 24, and these flanges are disposed in engagement with the flattened upper and lower surfaces 20 and 2|, respectively, of the guide member I9, which is to say, that the guide member I9 lies between the flanges 26 and 21; the outer end portion 23 of the driven shaft I2 projecting through an opening 28 which is formed in the body of the film-advancing member or claw 24 (Fig. 7).

Carried by and fast upon the front or driving upon the driving shaft I I is a guide member 3l, which is arranged atthe opposite side of the film-advancing member or claw 24 from the side thereof on which the front cam I9 is arranged, as shown, for example, in Fig. 3.

The guide member 3I is retained upon the driving shaft II by means of a nut 32 which is attached to the threaded outer end portionl 33 of the driving shaft II, and the driving shaft II projects Vthrough an opening or hole 34 which is formed in the body'of the film-advancing claw 24 (Fig. 7).

The film-advancing member 24 includes a cam or block 30 which is mounted thereon between the ends thereof and this cam or block 30 has a rear cam surface 4I which, at one stage in the operation of the new film-advancing device, is adapted to be engaged by the rear or back cam I8.

The film-advancing member 24 also includes a second pair of spaced upper and lower and longitudinally extending flanges' or cam surfaces 35 and 36, respectively, and the front cam 29 lies between and alternately engages these flanges or cam surfaces 35 and 36, which project rightangularly from the body of the film-advancing member 24 but on the opposite side thereof. from the side on which the flanges 26 and 21 are arranged, which is -to say that the flanges 35 and 36 arelarranged upon the same side of the lmadvancing member 24 as the flange or cam surface 25.

The film-advancing member or claw 24 likewise includes a plurality of film-engaging teeth 31 which are engageable in the apertures 38 of the film 39 as the latter passes through the film guideway 40.

Operation 'I'he operation of the new film-advancing device is as follows: When the driving shaft II is rotated, by a suitable source of power and powertransmitting means, (not shown in detail but generally indicated at 42), motion is transmitted by Way of the intermeshing gears I8 and I1, from the drive shaft II to the driven shaft I2 and to the rear or back cam I8 which is carried thereby; the driven shaft I2 and the rear cam I8 which is carried thereby make only one revolution for two revolutions of the driving shaft III and the front cam 29 carried thereby, due to the two to one speed ratio between the driving and driven gears I.6 and I1, respectively.

Accordingly, as the driven shaft I2 and the eccentrically mounted rear cam I8 carried thereby are rotated (counterclockwise,' Figs. '2 and 6), the peripheral edge or surface of the rear or back cam I8 alternately engages and disengages the rear face or cam surface 4I of. the cam or block 30, and in so doing moves the filmadvancing member or claw 24 forwardly, that is, toward the film 39 and the film guideway 4I).

Simultaneously with the forward movement of the film-advancing member or claw 24 which, as stated above, is caused by the engagement of the peripheral edge of the rear or back cam I8 with the rear face 4I of the cam block 38, the peripheral edge of the eccentrically mounted front cam 29 engages the upper and front flange 35 and in so doing moves, that is, raises the front end portion of the film-advancing member or claw 24 into the position in which it is shown n Fig. 5, whereupon a slightly further rotary movement of the rear or back cam I8, which is at this time still in engagement with the rear face or surface 4I of the cam 38, moves the teeth 31 on the filmadvancing member or claw 24 into the openings or apertures 38 in the film 39.

During this operation, that is, during the interval of time in which the teeth 31 of the filmadvancing member 24 are being moved into engagement with the openings 38 in the film 39, the peripheral, edge of the front cam 29 moves out of engagement with the upper front flange or cam surface 35, and subsequently moves into engagement with the lower front flange or cam surface 36, and in so doing rocks or pivots the front, end portion, including the teeth 21, of the film-advancing member or claw 24 downwardly, about the rear or driven `shaft I2 as a pivot, and

in so doing moves or advances the film 39 onev frame downwardly in the film trackway or guideway 4U'.

As soon as and when the film-advancing member or claw 24 completes its downward or filmadvancing strole, the peripheral edge of, the rear orback cam I8, which at this time has moved out of engagement with the rear face or cam surface 4i of the cam or block 30, engages the substantially vertically extending rear flange or cam surface 25 and in so doing moves the film-advancing member 24 rearwardly, thus moving the teeth 31 of the film-advancing member or claw 31 out of the apertures or openings 38 inthe film 39 and into a. position rearwardly of the film 39, as shown in Fig. 6, whereupon the foregoing cycle of. operations of the film-advancing member or claw 24 commences over again.

It will be noted, in connection with the operation of the new film-advancing device, that the guide member I9, which is carried by the rear or driven shaft I2, floats on the latter, and at no time rotates, since it is held against rotative movement by the engagement of its flattened upper and lower surfaces 20 and 2| with the upper and lower rear flanges 26 and 21, respectively, of the film-advancing member 24.

It will likewise be noted that all of the movements of the'lm-advancing member or claw 24 which take place during the operative cycle of -the latter are accomplished by the use of only two cams, that is, by 'the use of the single'front cam 29 and a single rear or back cam I8, as distinguished from'the customary three cam arrangement of the prior art film-advancing devices, in which it has been the usual practice to employ a single front cam and two rear or back cams, one rear or back cam for effecting the forward longitudinal movement of the filmadvancing member and the other rear or back cam effecting the rearward longitudinal movement of. the same.

It will further be noted, in this connection, that ln the new 'film-advancing device the entire vlongitudinal movement, that is, both the forward and rearward movement of the film-advancing member or claw 24 are caused by the single rear or back cam I8, in cooperation with the flange or cam surface 25 and the rear or cam surface 4I of the cam 30, and other associated parts of Athe new film-advancing device, as distinguished from the customary prior art practice of emdue to the two to one speed ratio between the front or driving shaft ll and the rear or driven shaft l2, the film-advancing member or claw 24 makes one idle transverse or lost up and down movement; under the action of the front cam 3|, during each of its operative cycles, although this feature. in itself is not new. in the art and no claim to novelty therein is herein made.

The slightly modified form of the film-advancing claw which is embodied in the new filmadvancing member is shown inFig. 8, is therein generally indicated as 42, and this form of filmadvancing claw is substantially the same as that which is shown in Figs. 1 to 7, inclusive, except that instead of forming the cam surface 4I upon a separate cam block 30 which is attached to the body'of the film-advancing claw 24, as at 43, this cam surface in the modified form of the filmadvancing claw which is shown in Fig. 8, is formed as a flange 44 which is integral with but struck out from the body of the film-advancing claw 42. Otherwise, however, the modified form of the film-advancing claw 42 which is shown in Fig. 8 is the same in construction and operation as the film-advancing claw 24 which is shown in Figs. 1 to 7, inclusive.

While I have illustrated and described a preferred form ofconstruction for carrying my invention intg effect, this is capable of variation and modification, without departing from the spirit of the invention. I, therefore, do not wish to be limited to the precise details of construction set forth, but desire to avail myself of such variations and modifications as come within the scope of the appended claim.

Y I claim:

A film-advancing device comprising, in combination, a film-advancing member or claw having a portion at the front thereof adapted to engage a fi1m,yand means for operating said filmadvancing member, said operating means including arotary front shaft and a rotary rear shaft,

said lmadvancing member including a pair of spaced cam surfaces extending transversely relative to the longitudinal axis of the said filmadvancing member, and a single rear cam on the said rear shaft coacting at different times with `each of the said cam surfaces to e'ect the longitudinal or inv and out movement of the said filmadvancing member, said film-advancing member having a pair of guide fianges thereon at the opposite side thereof from the side of the same on which said cam surfaces are arranged, and a guide member having' an aperture mounted to float upon the said near shaft and having a pair of flattened guide surfaces thereon engaging with the said guide iianges to guide the-said lm-advancing member, said film-advancing member having a pair of longitudinally extending cam surfaces thereon on the same side thereof as the side thereof on which the said first-named cam surfaces are located but forwardly of the latter, and a single front cam on the said front shaft alternately engageable with the said second-hand cam surfaces for imparting the transverse or up and down movement to the said film-advancing member.

HARVEY J'. REARDON.

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