US2235907A - Contact printer - Google Patents

Description

March 25, 1941.

A. W. TONDREAU CONTACT PRINTER Filed Sept. 17, 1938 4 Sheets-Sheet 2 w m w w && wmm 7 3 W, F 7 w v Z w /E A i w n L w Al N g 8 9 7 M: m mw H 5 Q My M w 5 a M 4 w 0 {W WV ATTORNEY.

INVENTOR. AL BEPT W. TONYDQEAU ATTORNEY.

4 Sheets-Sheet 3 March 25, 1941.

Patented Mar. 25, 1941 UNITED STATES CONTACT PRINTER Albert W. Tondreau,

Glendale, Calii'., assignor to Warner Bros. Pictures, Inc., New York, N. Y., a corporation of Delaware Application September 17, 1938, Serial No. 230,523

12 Claims.

This invention relates to photographic printing apparatus and has particular reference to printing apparatus wherein a developed printing film and a sensitized film being printed are continu- 5 ously run in contact with each other across a printing light beam.

In contact printing, it is essential that intimate contact with minimum relative slippage, be maintained at the printing point between the printing film and the sensitized film being printed. This is especially true when printing sound tracks, in which case even. a slight separation or relative movement between the films, i. e. .0005 inch causes distortion of the graphically 15 produced sound modulations of the sound track.

Furthermore, it is essential, especially when printing sound tracks, to maintain an even printing illumination throughout the area being printed while preventing any reflection of the printing beam either internally of the films themselves or therebehind onto the sensitized film during the printing operations. Heretofore, when printing sound tracks from one film to another wherein, according to present day standards where the 25 sound tracks are positioned directly adjacent one row of sprocket perforations, it has frequently been found that an unwanted 96 cycle modulation has been introduced into the sound track being printed. I have discovered that this 96 cycle modulation has been due largely to the printing light beam striking the edges of the sprocket perforations directly adjacent the sound track and thereafter reflecting back onto the sensitized film. This reflection, of course, oc- 35 curred only at points opposite the sprocket perforations vand thus caused fogging of the sound track on the sensitized films at regularly spaced areas. When the sound track film thus printed was subsequently reproduced, these regularly spaced, fogged areas of the sound track passed the reproducing point at the same frequency as the sprocket perforations, namely 96 times per second and thus produced a 96 cycle hum. I have discovered that this effect is especially no- 45 ticeable where the printer light beam is flooded onto the film without the use of an optical system instead of being projected thereon. In this case, a large amount of the rays of printing light strike the film at an angle, and consequently strike the edges of the sprocket perforations in both the printing film and the sensitized film at an angle, causing an unwanted reflection of such light onto the sensitive film to fog the same.

I Furthermore, I have discovered that when the 55 films being printed were wrapped or guided around an arcuate surface, they were minutely separated at the points where the sprocket perforations occur and that since the sound track is in immediate proximity to the perforations, the film along this track was also minutely separated at spaced intervals. This, of course, gave rise to distortion in printing. This minute separation between the films at the sprocket perforations was probably due to the slight burrs or raised edges formed around such perforations either during the perforating operation or by later warping of the films. Also, inasmuch as a film is stiffer across the lands" intermediate the sprocket perforations than across the perforations themselves, the film, when wrapped around an arcuate or cylindrical surface will assume a polygonal shape instead of a perfect arc. The superposition of two of such polygonally shaped films over an arcuate surface tends to cause the films to separate slightly along the sprocket hole 2 perforations and parts adjacent thereto, including the sound track, thus tending to separate the films.

Furthermore, due to the fact that the films assume a polygonal shape along the sprocket perforations as they are wrapped around an arcuate surface, the printing light beam, as it passes through the portion of the printing film directly adjacent the sprocket perforations, i. e. the sound track, on its way to the sensitized film is refracted in an irregular manner by such film due to the fact that the sound track portions of the films continually assume minutely different an gular positions relative to the axis of the printing light beam as the films pass thereacross, thereby tending to distort the sound track printed on the sensitized film.

Accordingly, one object of the present invention is to obtain at the printing point an intimate contact between the pair of films being printed.

According to another phase of the invention, the films are passed over an arcuate surface at the printing point and are tensioned on either side thereof to maintain an intimate contact between the two films on such surface at the printing point. A rotatable toothed drum, forming a part of such arcuate surface, is provided to drive the films past the printing point. According to the present invention, the tension on the films on one side of the arcuate surface is maintained less than that on the other side to permit the drum to drive the films thereover while reducing the driving load on the teeth'thereof.

Another object is to facilitate adjustment of an optical system for printing films.

Another object is to permit individual adjustment of the elements of an optical system for a printing apparatus while permitting adjustment of the optical system as a whole.

Another object is to photographically form identification marks on a film being printed simultaneously with the printing thereof from another film.

Another object is to regulate the color characteristics of a printing light.

Another object is to ventilate a printer lamp housing while preventing light leakage therefrom.

The manner in which the above and other objects of the present invention are accomplished will be readily understood on reference to the following specification read in conjunction with the accompanying drawings in which:

Fig. 1 is a side elevational view of a printing apparatus, with parts broken away, embodying the present invention.

' Fig. 2 is a sectional plan view through the printing mechanism and is taken along the line 2 2 of Fig. 1.

Fig. 3 is a sectional view taken along the line 3-3 of Fig. 2.

Fig. 4 is a sectional, elevational view through the film driving mechanism of the printer and is take along the line 4'-4 of Fig. 3.

Fig. 5 is a sectional view through the edge number printing attachment and is taken along line 5-5 of Fig. 4.

Fig. 6 is an enlarged sectional view through the optical system for the printer and is taken along the line 66 of Fig. 3.

Fig. 7 is a front view of the pad roller and.

mount therefor and is taken in the direction of the arrow I of Fig. 4.

Fig. 8 is-a sectional view showing the construction of the filter slide and is taken through the lens tube along the lines 8-8 of Fig. 6.

Referring particularly to Fig. 1 the printing machine comprises a casting I0 supported at the top of a standard I I forming the support for the printing machine. A printer head casting, generally indicated at I2, is secured to one side of the casting ID by bolts I3 and carries the various film driving and printing elements.

The printer head casting|2 comprises a bored semicylindrical protuberance I4 forming a printing compartment housing. A vertical wall section I5 integrally formed at one end of the housing l4 forms a bearing support for the various film driving elements.

The negative or printing film I5 is supplied by a supply reel l1 rotatably mounted in a manner not shown upon a standard l8 supported from the printer head casting I2. The printing film l6 after passing through the various film driving and printing elements is reeled upon a takeup reel I9 below the casting l2 androtatably mounted in a suitable manner on a bracket 20 extending from the printer standard II. The

positive or sensitized film 2|, on which images from film l6 are to be printed, is supplied by a supply reel 22 rotatably mounted above the printing mechanism by a suitable bracket (not shown) extending from the standard l8. Film 2 I, after passing through the various film driving and printing mechanisms is stored upon a takeup reel 23 also rotatably mounted upon bracket 20. These take-up reels I9 and 23 are driven through suitable slip clutches (not shown) by a continuously driven belt 24.

Referring now particularly to Fig. 4 the printer film l6 after passing from the supply reel I1 is guided into contact with the sensitized film 2|, led-from its respective supply reel. These films are then led around a guide roller 25, around a feed or pull down sprocket 28, being maintained roller-33, around a guide roller 34 and is thence led into contact with the film I6 while passing over the drum 30. It will be noted that the film 2|, on passing into engagement with the film it over the drum 3|) converges therewith at an angle of approximately 5. The provision of these converging paths of films I5 and 2| as they are led onto drum 30 permit the air therebetween to be continuously squeezed or wrung rearwardly instead of being trapped therebetween to cause a separation of the films. This squeezing or wringing action is caused both by the tensioning of the films I6 and 2| over the drum 30 and by the pressure of a pad roller I35 against the two weighted roller 36, over a hold back sprocket 31 being held in engagement therewith by a pad roller 38, thence over a guide roller 20 and there-' after onto their respective take-up reels.

The weighted roller 28 is rotatably mounted on the end of an arm 4|, the other end of which is pivotally journalled on the stationary shaft 29 of the roller 29. Shaft 29 is rigidly secured to the wall section I5 of casting I2. A weight 42 is provided on the arm 4| to cause the roller 28 to exert a tensioning eifect of approximately one pound on the film I6 intermediate the sprocket 25 and toothed drum 3!). The weighted roller 33 is likewise mounted on an arm 43 which is pivotally mounted on a stationary shaft 34 of the roller 34. Shaft 34' is also rigidly secured to the wall section I5 of casting l2. A weight 44 on the arm 43 is provided to cause the roller 33 to exert a tension of approximately one pound and one-half on the film 2| intermediate the sprocket 26 and drum 30. The weighted roller the tensioning of the films above and below the toothed drum 30 an intimate contact between the films will be maintained while passing thereover. Furthermore, due to the fact that the tensioning effect is greater on the films above the printing drum 30 than below the drum, the sprocket teeth 50 of drum 30 will produce a driving effect on the films but with the tooth load thereon less than the tension applied to the films. That is, the leading edges of the sprocket teeth 50 will engage the leading edges of the sprocket perforations of films l6 and 2| as the films pass over the drum 30. This maintains the films in accurate registration with each other. For this reason, I prefer to so adjust the film tension above and below the drum 30 that a.

minimum tooth load will be maintained to reduce film wear while providing a sufficient amount of such tooth load to maintain accurate registration of the films with the sprocket teeth 50. I have found that by providing a tooth load of approximately one pound for each film, such as results from employing the above mentioned tensioning values, satisfactory film registration is obtained.

Also, since the tension in film l6 governs only the contact between film Hi and drum 30, while the tension in film 2| governs both the contact between the films l6 and 2| as well as the contact between these films and drum 30, I prefer to employ a greater tension in the film 2| than in film IS.

The loop in the two films I6 and 2| intermediate the drum 30 and the sprocket 31 is preferably so adjusted that the roller 36 resting therein assumes such a position that a line passing through the axis of rotation of roller 36 and the axis of pivotal movement of arm 3'! lies perpendicular to the surface of the guide plate 35. -Further, when in this position the guide plate 35 will be tangentially aligned at one end thereof .with the surface of the drum 30 and at the other end thereof with the surface of the roller 36.

The two fiat guide plates 32 and 35 are suitably secured to the housing or protuberance H at the base of an opening 41 formed therein. Opening 4! permits the films l6 and 2| to be led onto the drum 30.

It should be noted at this point that the rollers 29 and 34 are edge guiding rollers having spaced flanges as at 8 and 9, respectively, thereon to engage and guide the opposite edges of the films againstlateral movement as they pass onto the drum 30. Thus each film will be individually edge guided, there being no provision for edge guiding of the films thereafter while in contact with each other.

Referring now to Figs, 2 and 3 the drum 3!! is formed of a sprocket member 48 having a row of sprocket teeth 50 therearound, which member is integrally formed on a shaft 5| rotatably mounted in a bearing member 52. Bearing member 52 is secured within the bore 3|, forming the printing compartment, by screws 53. A cylindrical flange 54 secured to the sprocket member 48 by screws 55 forms a rotatable film support for the picture portion of the films passing over the drum 30 while permitting the sound track portion of these films to overhang. A stationary ring member 55 is fitted within the bore 3| and is secured therein by screws 56. Ring 55 has a reduced cylindrical bearing portion 51 thereon of the same diameter as, and concentric with, film drum 3|] to support the overhanging portion of the films passing over the drum 3!] while being spaced from the open end of the flange 54 of drum 30 by an amount substantially equal to the width of the sound track. Preferably, however, the inner edge of the bearing portion 51 of ring 55 extends approximately .002 over the edges of the sprocket perforations directly adjacent the sound track to prevent the printing light beam from striking such edges. It will be noted that the adjacent edges of the fiange 54 and ring 55 are chamfered as at 58. This provision for laterally supporting the films throughout the entire width thereof except the sound track portions, eliminates any tendency of the film to bow transversely and therefore aids in maintaining an intimate contact between the films themselves and between the films and the drum 30 and bearing portion 51 of ring 55 at the printing point.

Describing now the drive for the sprockets 26 and 31 and drum 30, a helical gear 60 (Figs. 2, 3 and 4) is secured to the shaft 5| of drum 3') and is driven by a similar small gear 6| (Fig. 4) r eshing therewith and secured in driving relation to a pulley 62 over which the continuously driven belt 24 is engaged. Gear 6| alsomeshes with a gear 59 aflixed to shaft 31' of sprocket 31. A gear 63 secured to the shaft 26' of sprocket 26 is driven from the gear 50 by an intermediate idler gear 54. The shafts of gears 59, 6|, 63 and 54 are all suitably journalled in bearings formed in wall section I5.

Referring to Figs. 2, 3 and 6, I will now describe the optical system for projecting a printing light beam onto the sound track portions of the films l6 and 2| while passing in contact in an arcuate path over the drum 30 and bearing portion 51 of ring 55 The optical system comprises generally a lamp house 66 containing a printing lamp 61, a lens mount generally indicated at 68 having a prism 69 at the forward end thereof for deflecting the printing beam of light into the sound track portion of the films 6 and 2| intermediate the adjacent edges of the drum 3!] and ring 55.

As shown in Fig. 6, the mount 68 comprises a cylindrical tube I0. A slit member 7| having a horizontally extending slit 12 formed therein is threadably secured in the rear end of the tube 10, Also threadably secured in this end of tube 10 is the mount for a condenser lens 13. The opposite end of tube 10 is securely fitted within the slide block 74, having a vertically extending slide aperture 15 extending therethrough. A tapered objective-tube 16, co-axial with tube 10, is threadably mounted in the opposite end of the block 74 and carries at its forward end a pair of objective lenses 11. The size of the slit l2 and the magnification of the objective lenses ll are such that a horizontal slit of light approximately .009" high and .010" long is focussed upon the films at the point P (Fig. 4) The length of this slit of light is therefore sufiicient to extend entirely across the gap or opening between the adjacentedges of the drum 30 and ring 55. The right angle prism 69 is mounted in a prism block 19 having a bore therein fitted over the forward end of the tube 16. A set screw 79 threadably mounted within the block 70 permits the prism 69 and block 19 to be locked in any adjusted position about the tube 16.

As shown in Figs. 2 and 3 the tube H1 is slidably and rotatably mounted in a bushing ll secured to and extending through an end plate or cover member 18. End plate 18 is secured across the bore 3| provided in the housing l4 by bolts 89 and 8|. Bolts 80 and 8| extend through elongated horizontally extending slots 82 and 83, respectively, formed in the plate 18, permitting transverse adjustment of the plate 18 and mount 68, carried thereby, in a horizontal direction. A set screw 84, threadably mounted in the bushing 11, permits rotatable as well as longitudinal adjustment of the tube 10 and the lamp house 66 carried thereby.

Referring now to Figs. 3, 6 and 8, a filter slide, generally indicated at 85, is slidably mounted within the aperture ii in block 74. Filter slide 85 comprises a channel shaped member 85 having three I spaced apertures 81, and 80 formed therein, any one of which is adapted to be positioned, on movement; of slide 85, in the path of light through the tube I0. The upper aperture 87 is in the form of. a horizontal slit to reduce the amount of light passing therethrough, the other two apertures 88 and 89 being circular. A pair of fiat glass blocks 90 and SI having d fier- SI to retain the same in place.

transmission of light through the blocks 90 and 9I, respectively. The aperture 93 is in the formof a horizontal slot to reduce the amount of light passing therethrough. These filter blocks 90 and 9t may have any desired color absorbing characteristics. For example, block 90 passes only ultra violet light and is inserted in the path ofthe printing light beam through the tube I0 whenever ultra violet printing is to be employed, while the block 9I permits only the blue component of the printing light to pass therethrough and is insert- .ed in the printing light beam whenever fine grain film is to be printed. The slide is manipulated from the exterior of the printer housing Ml by means of a rod 95 loosely mounted on a transversely extending pin 96 secured in the opposite legs of the channel member 86. Rod 95 extends It and thence extends loosely through a block 91 (Fig. 3) secured in a suitable manner on top of the housing It. A series of three circumferential slots 98, 99 and I00 are formed at spaced intervals along the rod 95 and are adapted to be selectively engaged by a plunger member I00 slidable transversely in the block 91 and urged against the rod 95 by a springifiI. When one or the other filter blocks and BI, or the aperture 8! is to be moved into position in the printing light beam, the plunger m0 is retracted from engagement with one of the slots 98, 99 or I00, and the rod is moved vertically until the correct aperture or filter block is positioned in the tube 70. The plunger I00 is then allowed to engage the corresponding slot 98, 99 or I00 to hold the filter slide 85 in its correctly adjusted position. A considerable amount of loose play is provided between the rod 95 and the aperture in the block 97 through which it slides, whereby the tube l0 may be adjusted longitudinally to correctly align the optical system with the sound track portions of the films being printed. Also, a considerable amount of play is provided between the lower end of the rod 05 and the pin 90, on which it is pivotally secured, whereby the tube I0 may be transversely and rotatably adjusted slight amounts to correctly align and focus the optical system on the films IB- and 2t. It will be understood, of course, that transverse adjustment of tube I0 will cause a change in the focus of the projected beam of light passing 'therethrough due to the right angle deflection of the beam by the prism 69.

Aswill be noted in Figs. 1, 2 and 3 the printer lamp'housing 06 comprises a vertically extending cylindrical shell N35 having a crescent shapedsupporting member I05 surrounding the same and secured thereto by screws W6. A bushing I01 extending through both the member I 06 and shell l05 is'adjust'ably fitted over the outer end ofthe tube IIJ-and has a set screw 38 threaded therein whereby the lamp house 66 is supported by tube- I0 and may be adjusted longitudinally and rotatably about the tube I0.

The base of the lamp house 66 comprises a cylindrical end cover member I09 fitted with the shell I05 and secured thereto by screws II'0. A pair of spaced circumferentially extending channels III and H2 are formed around the member I09. A series of spaced vent holes I13 exte'nd between the channel III and the interior ent color filtering values aremounted in the of the housing 66. A second series of vent holes channel member 88 over the apertures 88 and 89, respectively. A cover plate 92 is mounted on the member 86 by screws 92 over the blocks 90 and A'pertures 93 and 94 are provided in the cover plate 92 to permit tures H4. The labyrinth air venting passage I I4 extend between the channels III and H2 and are staggered in relation to the other holes I I3 as shown in Fig. 2. A third series of vent holes II5 are formed in the shell I05 and communicate with the channel I I2 in staggered relation to the aperthus formed permits air to pass into the lamp housing 66 while preventing leakage of printing light therefrom. The upper end of the shell I05 is closed by a cover member I I6 having a tubular extension I I! formed centrally thereof and defining an opening. A flexible hose H8 is fitted over the extension I and is connected to a suitable vacuum pump (not shown) to draw cooling air through the lamp housing 66 from the labyrinth passage at the base thereof to cool lamp 61.

Lamp 61 is mounted in a socket II 8 fitted in an opening I20 formed in a lamp supporting pla-te I2I which is secured to the base member I09 by screws I22. A set screw I23 threadably mounted in the plate I2I permits vertical and rotatable adjustment of the socket II9 to correctly align the filament tiI' of lamp 61 with the optical system in the mount 68. In lieu of a single filament lamp as illustrated, I may employ a multifilament lamp. Lamp 61 is connected to a suitable source of supply by a conductor I10 and has a rheostat generally indicated at Ill (Fig. 1) in circuit therewith. Rheostat lII is suitably secured to the casting lI within easy reach of the operator of the printing machine.

From the foregoing it will be seen that the entire optical system, including the printing lamp 5?, for printing the sound tracks of the films I6 and 2! is supported by the tube I0, carried by the end plate i8. Thus, the provision for lateral adjustment of the endplate I8 as well as the provision for longitudinal and rotatable adjustment of the tube 10 permits an adjustment of the entire optical system as a whole. Also, the provision of the set screw I9 in the prism mount I9 as well as the set screws I23 in the lamp housing plate iii and the set screw I08 in the lamp supporting bushing I07, and movable filter slide 85, permits adjustment of the various elements of the optical .or light projecting system individually.

Referring now to Figs. 2, 4 and 6, I will now describe the means for exposing identification marks on a sensitized film whereby to identify the particular printer in which such film was printed. Agroove or notch I25 (Fig. 6) is formed at one point within the printing drum 30. A small passage E25 communicates this groove I25 with a point on the circumference of the drum 30 intermediate two of the sprocket teeth 50. This passage E26 is adapted to transmit light from a small lamp i2? to the films I6 and 2| at each revolution of the drum 30. Lamp I2! is mounted in a housing I28 secured on a bracket I29 supported on the filter slide block it by screws Hill. A light passage I3l is formed at the 'front of the housing I128 to direct a pencil or beam of light from the lamp in toward the circular path of movement of the passage I26. An arcuately shaped light shield I 62 (Figs. 4 and 6) is secured .to the lamp housing I26 to prevent refiection of light from the lamp I21 onto the sound track portion of the films being printed. The edge I32 of shield I32 lies closely adjacent the inner surface of the drum so that any light passing therebetween is not in line with the films being printed. Current is supplied to the lamp I21 through a conductor I 34 passing through an aperture in the cover plate 16 and connected to a suitable source of current supply. It will be seen, therefore, that when the passage I26 passes beneath the line of light from the lamp I21, on each revolution of the drum 30, light will be transmitted to the films I6 and 2I. Since, according to present practice, the space intermediate the sprocket perforations is generally left transparent, the light will pass through the negative or printing film I6 and thus fog or expose an identification mark on the film 2| at a point intermediate two of the sprocket teeth 60. By arranging any number of passages I26 or by varying the shape of such passages, diflerent identification marks may be provided for different printer machines.

To further obtain an intimate contact between the two films I6 and 2I at the printing point, a pad roller I36 (Figs. 2, 4, 6 and 7) is provided. Roller I36 engages the films at a point directly opposite the printing point P and straddles both the drum 30 and the bearing portion 61 of stationary ring 55. A self-aligning mount, generally indicated at I 31, i provided to resiliently urge the roller I36 against the films in contact. Mount I 31 comprises a stirrup I36 in which the shaft of roller I36 i rotatably mounted. Stirrup I38 has a vertically extending bearing formed therein which is pivotally fitted'over a bearing portion I40 formed at the bottom of a rod I H. Rod I4I extends through an aperture formed in a swivel block I42 and 1s adjustably secured therein by a set screw I43 permitting vertical adjustment of the roller I 36. Block I42 has a horizontally extending bearing stud I44 thereon journalled in a bearing block I45 which is secured as by screws I46 to a gate member I46. Gate member I46 is pivotally mounted upon a stationary bearing stud I41 projecting from the wall I5 permitting movement of the roller mount I31 toward and away from the drum 30 for film threading purposes. Roller I36 is resiliently urged against the films I6 and 2i by a tension spring, I48 extending between the upper end of rod HI and a piece I49 secured to the pad member I46. A stop pin I50 is threadably mounted in the piece I49 for longitudinal adjustment thereof. The head of pin I50 is adapted to engage the rod Hi to limit the inward movement of the roller I36. Pad member I46 is limited in its inward movement by a set screw I5I (Fig. 2) and is adapted to be held in that position by a spring I63 (Fig. 4). Spring I53 surrounds a plunger rod mounted at the upper end thereof to a dependent lug I55 integrally formed on the pad member I46 below the stud I41. Spring I54 engages at one end thereof a flange I56 formed on the rod I 54, and at the other end thereof a sleeve I 51 through which the rod I54 is s'lidable. Sleeve I 51 is seated upon a semi-cylindrical projection I66 forming a bearing for a shaft I59. Projection I56 also has an aperture I62 in which the rod I64 is loosely mounted to slide therethrough. Shaft I56 has a radially extending hole I60 therein which, when aligned with the rod I54, permits the same to 'various metallic surfaces behind the films.

I54 pivotally project therethrough. Shaft I56 is adapted to be rotated by a handle I6I (Fig. 1) to align the hole I60 with the rod I64, thus permitting the rod I64 to extend into the hole I66 for the purpose of moving the gate member I46 into threading position. Spring I63 acts as a snapover spring to hold the gate member I46 in an open position away from the opening 41 in housing I4 when the gate member I46 is moved counterclockwise approximately A switch (not shown) in circuit with the printing lamp I61 is actuated by the shaft I69. When the shaft I66 is rotated to align the hole I60 with the plunger rod I64, this switch will be opened to extinguish the printer lamp. Thus, this switch forms a safety feature, preventing the lamp from being illuminated until the gate member I 46 is closed.

The edge printing device comprises a small box shaped lamp compartment I63 (Figs. 4 and 5) secured to the rear of the lower guide plate 35 by screws I64. A printing lamp I66 supported in a socket I66 within the compartment I63 is adapted to project a beam of light through a small printing aperture I66 formed co-extensively through the forward wall of the compartment I63 and the guide plate 36. This passage I66 is directly in hers along the film I6 to permit such numbers to be printed on the sensitive film 2i. A suitable switch (not shown) is provided in the circuit of lamp I66 to open such circuit when it is not desired to print edge numbers. A mask I61 is integrally mounted on a pin I66 journalled in a bearing lug I66 projecting from the wall of compartment I63 and, when moved into one position, intercepts the line of light passing through the passage I66 and the films I6 and 2I to prevent the same from fogging the sensitized film 2I after passing therethrough due to reflection from Mask I61 is rotatable into an out-of-the-way position to permit threading the films in the machine,

Certain features disclosed herein are disclosed and claimed in my co-pending application 249,956, filed January 9, 1939, for Film printing apparatus and in my U, S. Patent 2,199,764, granted May 7, 1940, for Film marking apparatus."

I claim: 1. In a film printing apparatus, a rotaiable film supporting member having a cylindrical flange thereon, said flange being adapted to support a film with a portion of said film overhanging said flange and said flange having an aperture extending therethrough, a light source. an opt cal system for projecting a beam of light from said light source onto said overhanging portion of said film on said flange, a mount for said optical system, a second light source, means on sad mount for supporting said second llQhi source within said flange. said light source being d rected toward the path of movement of said aperture, and a shielding member intermediate said second light source and the overhanging portion'of said film.

2. Printing apparatus comprising the combination of a hollow drum adapted to support films in printing relation, said drum having a closed end and an open end and means for rotatably supporting said drum, a set of sprocket teeth around said drum adjacent the closed end thereof, an exposure aperture comprising a light passage extending from the interior to the exterior of said drum between adjacent ones of said sprocket teeth, means providing a light beam therefor, means'providing a light beam for print ing sound track from one to the other of the films overhanging the edge of said drum and means for shielding one of said light beams from the other.

3. Printing apparatus comprising a hollow drum having a flange adapted to support a light sensitive film and another film in contact in printing relation beyond said flange, means associated with said drum for printing said light sensitive film, an aperture through said drum, and means inside of said flange and associated with said aperture for exposing an identification mark on said light sensitive "film outside the printing area beyond said flange.

4. A film printing apparatus comprising a rotatable open drum defining one side of the printing area and adapted to guide a pair of films in contact thereover with the printing area and one edge of said films overhanging said drum, a hollow film guiding member concentric with and spaced from said drum for defining the other side of the printing area and for guiding the overhanging edges of said films, means projecting through said hollow film guiding member for projecting a beam of light substantially radially onto said films intermediate said drum and said hollow film guiding member at a printing point, and a pad member engaging said films on said drum and on said film guiding member at said printing point.

5. Film printing apparatus comprising the combination of a printer housing having a cylindrical bore therethrough, a rotatable film drum adapted to support a pair of superposed films thereover with one edge of said films overhanging said drum, means in said bore for rotatably supporting said drum, a supporting member concentric with said film drum for supporting the overhanging edge of said films, means for supporting said supporting member in said bore, a cover member for one end of said bore, an optical system at least partly within said bore and adapted to project a beam of light onto said films intermediate said drum and said supporting member, means on said cover member for supporting said optical system, and means whereby said cover member may be adjusted transversely of said bore to focus said optical system.

6. A film printing apparatus comprising 9. casing, a rotatable film drum in said casing adapted to support a pair of superposed films thereover in printing relation, means in said casing for rotatably supporting said drum, said casing having an opening therein, a cover member for said opening, an optical system for projecting a beam of light onto said films on said drum, a mount for said optical system, means on said cover member for supporting said mount, said mount having an opening therethrouglna filterslide in said opening, and actuating means extending through said casing for manipulating said filter slide.

'7. A printing apparatus comprising a casing having a cylindrical bore therein, a film drum in said bore adapted to support a pair of films in contact thereover with a portion of said films overhanging said drum, bearing means in said bore at one end thereof for rotatably supporting said drum, a stationary cylindrical member in said bore adapted,- to support the overhanging portions of said films, said stationary supporting member being spaced from said drum to define a sound track printing opening, a cover member for the other end of said bore,-an optical system adapted to project a slit of light and arranged substantially co-asial with said drum, a light defiector for deflecting a beam of light from said optical system onto the sound track portion or said films, a mount for saidoptical system and said deflector, said mount extending through said cover member, means on said cover member for securing said mount thereto, a lamp house, means for securing said lamp house on said mount, and a lamp in said lamp house for projecting light through said optical system.

8. Printing apparatus according to claim '7 comprising means whereby said mount may be adjusted longitudinally through said cover memher.

9. Film printing apparatus comprising a film drum having sprocket teeth thereon, feed sprocket means for leading films in printing relation onto said drum, means for printing from one of said films to the other at said drum, takeup sprocket means for leading said films oil of said drum, a synchronous power drive coupled to said drum, said feed sprocket means and said take-up sprocket means, means for guiding said films over said drum in an arc, means for tensioning the portion of said films intermediate said drum and said feed sprocket means, and simultaneously operative means for tensioning the portion of said films intermediate said drum and said take-up sprocket means to a lesser degree than said first mentioned tensioning means.

10. Film printing apparatus according to claim 9 wherein the tension in the outer of said filins at said drum is greater than the tension in the inner of said films at said drum.

11. Printing apparatus comprising a printing drum having sprocket teeth, means for traversing a pair of films in printing relation over said drum, a synchronous power drive coupled to said drum and to said traversing means, means for printing from one of said films to the other at said drum, and film tensioning means at opposite sides of said drum and intermediate said traversing means and said drum for simultaneously tensioning said films, said film tensioning means at one side 01 said drum being more eifective than the film tensioning means at the other side thereof whereby one side oi the sprocket holes of said films is caused to drag against the sprocket teeth on said drum.

12. Film printing apparatus comprising a printing drum having sprocket teeth, a feed sprocket and take-up sprocket at opposite sides of said drum for traversing a pair of films in printing relation over said drum, means for printing from one of said films to the other at said drum, means for synchronously driving said sprockets and said drum at the same peripheral speed, film tensioning means for both of said films intermediate said feed sprocket and said drum and intermediate said take-up sprocket and said drum for simultaneously tensioning said films wherein said film tensioning means comprises means for tensioning said films a greater amount at one side of said drum than at the other.

ALBERT W. TONDREAU.

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