US1758700A - Photographic-printing machine - Google Patents

Description

May 13, 1930. A. s. HOWELL 1,758,700

PHOTOGRAPHIC PRINTING MACHINE f1/glad A. S. HOWELL May 13, 1930.

PHOTOGRAPHI C PRINTING MACHINE Filed Aug. 17, 1927 4 Sheets-Sheet 2 wex Ex May 13, 1930. A. s. HOWELL 1,758,700

PHOTOGRAPHIC PRINTING MACHINE Filed Aug. 17 1927 4 Sheets-Sheet 3 mmm Y gg@ UUUUUD UUU m RMS May 13, 1930A. A. s. HOWELL 1,758,700

PHOTOGRAPHIC PRINTING MACHINE Filed Aug. 17, 1927 4 SheetS-Sheet 4 ll i?? 'jf/W mllls/ i l" Kfer/@a Patented May 13, 1930 UNITED STATES PATENT OFFICE ALBERT S. HOWELL, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE BELL & HOWELL COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOISv PHOTOGRAPI-IIC-PRINTING MACHINE Application filed August 17, 1927.

My invention relates particularly to machinos for printing motion picture film although not limited to'this use alone.

One of the objects of the invention resides in the provision of means whereby a plurality ot' longitudinal sections of a photographically sensitized strip, such as an unexposed positive motion picture film, may be exposed to or printed from different photographic printing or negative strips so that a plud fected, all as fully described with-reference to the accompanying drawings and more particularly pointed out in the appended claims.

In the said drawings A Figure l is a front elevation of a motion picture film printing machine embodying my invention Figure 2 isan enlarged partial section on the line 2 2 of Figure l;

Figure 3 is a section on the line 3 3 of Figure 2;

Figure 4 is a partial section on the line 4 4.of Figure 5, hereinafter described;

Figure 5 is an enlarged partial section on the line 5 5 of Figure l;

Figure 6 is a face view of a portion of a positive film printed on the machine;

Figures 7 and 8 are face vie-ws of portions of the negative films used in printing the positive' film; a n 4 Figure 9 is a partial section on the line 9 9 of Figure l0, hereinafter described;

Figure ll) an enlarged front elevation of I a portion of the machine with a part thereof removed Serial No. 213,549.

Figure 11 is an enlarged face View of the exposure aperture 'face guide member and related parts of one of the exposure devices, hereinafter described;

Figure l2 is a section on the line 1.2 12 of Figure ll;

Figure 13 is an enlarged partial interior view somewhat similar to Figure 3 with parts broken away and in section, on the line 13 13 of Figure l1.

Like characters of reference indicate like parts in the several views.

In the said draufings, l designates a pedestal which supports the machine, and arranged at the top of this pedestal is a lamp chamber 2 in which is mounted a source of photographic light in the form 0f an incandescent electric lamp 3. See Figures l and 5. A portion of the frame of the machine in front of the vlamp is bored horizontally in aforwardly and rearwardly extending direction, as designated at 4, and communicates radially with the lamp chamber through a light passage 5. See Figures 4 and 5. The front end of thebore 4 is closed by a cover member 6 secured therewith, and the rear end of this bore is closed in a manner unnecessary to be described. Disposed in the bore 4 in coaxial relation therewith is a revolubly mount-ed film feed sprocket comprising two axially spaced peripherally toothed wheels 7 and an axial spindle 8 extending therebetween. The light passage 5 is alined with the plane of the space between the wheels 7, and the frame is provided with an opening communicating with the bore 4 between the wheels' and disposed in substantially diametri'cally opposite relation with respect to the light passage 5. A motion picture film guide is associated with this opening and consists as follows. A pair of statlonary film face guide plates 9 are mounted on the frame and extend in said opening in tangential relation with the wheels 7 and have their adjacent ends spaced to provide an .exposure opening. An opposing film face guide member 11 is mounted on a pivoted arm 12 for movement into and out of film guiding relation with the guide plates 9, this guide member being so mounted to open the guide for the lacing and unlacing of film therein and to form with the plates 9, when it is in film guiding relation therewith,a film guide for retaining film therein in engagement with the sprocket comprising the wheels 7 for the feeding of the film. Accordingly the intermediate portion' of the film guide face of the guide member 11 is of concave form corresponding with the peripher of the sprocket comprising the wheels and the end port-ions of this face are tangent thereto, lthe plates 9 being parallel with these end portions when the guide member 11 is in film guiding relation therewith. The guide member 11 is releasably secured in film guiding position in a manner unnecessary to be described. v

The guide so formed is adapted to guide superposed printing or negative and photographically sensitized or positive films, respectively designated at 13 and 14, engaged onthe aforementioned sprocket, comprising the wheels 7, for the feeding of these films in printing relation through the guide and past the exposure aperture between the wheels 7 provided by the spacing of the plates 9, where they are subjected to the printing light provided by the lamp 3 in the lamp chamber 2. y The lower edge of this exposure4 apertre is formed by a stationary member 15 secured to the frame and-extending angularly corresponding with the wheels i7 and between the same and forming with its upper edge the lower edge of this exposure aperture. The upper edge of this exposure aperture is formed by a movable shutting member 16' extending angularly corre-I sponding with the wheels 7 and between the same and forming with its lower edge the upper edge of this exposure aperture. This shutter member 16 is mounted for angular adjustment coaxially of the wheels 7 to vary thev aforementioned exposure aperture longitudinally of the aforementioned guide whereby to vary the exposure of the films in the guide as they are fed therethrough at a uniform rate by uniform rotation of the. sprocket comprising the wheels 7. Accordingly a shaft 17 is journaled in the bore of a coaxially bored sleeve 18 which in turn is j ournaled in coaxial relation with the wheels 7 in an extended bore through the cover member 6, and an arm 19 is secured on the inner end of the shaft 17 and extends overthe periphery of the adjacent wheel 7 and is secured with the shutter member 16 Whereby the shutter member is vcarried for' angular movement coaxially with the wheels, 7. An arm 20 is secured on the outer end of the shaft 17 for adjusting the shutter member 16, and this shutter member is adjustably secured in position by a suitable releasable securing device 2l.

The light passage 5ispartially blocked by a shield 22 which is provided with a lightl aperture 23 between the wheels 7 across which is disposed a ground glass 24 for diffusing the light from the lamp 3. Another shutter 25 is angularly movable coaxially with the wheels 7 for varying the light pass- '70 ing from the aperture 23 to the aforementioned guide, and is mounted for such angular movement by means of an arm 26 secured on the inner en'd of the sleeve 18 and fast at its outer end with the shutter 25. vAn arm 27 is secured on the outer end of the sleeve y18 for the adjustment of the shutter 25. Thus is provided another means for varying the exposure of the films as they are fed through the Aaforementioned guide for purposes hereinafter described.

The frame of the machine extends upwardly from the rear of the portion thereof having the bore 4 therein in the form of a gear casing 28 at the upper end of which isdisposed another exposure device which will now be described. See Figures 1, 2, 3, and 9 to 13 inclusive.

A shaft 29 is revolubly mounted on the gear casing adjacent its upper end and is disposed on a forwardly and rearwardly extendingaxis. See Figures 2 and 3. The shaft 29 projects from the gear casing 28 forwardly and is provided at its projecting front end with a film feed sprocket comprising two axially spaced peripherally toothed wheels 31 and a portion of the shaft 29 extending axially therebetween and fast there-` with. The wheels 31 have the peripheral portions thereof projected toward each other, as designated at 32, and a stationary closure member 33 of generally circular form is disposed between the wheels 31 in coaxial relation therewith and underlies the projected portions 32 of the wheels 31 and forms 105 alight tight lamp enclosure therewith. The closure member 33 is secured with the frame of the machine by means of a generally semicircular extension 34 thereof projecting from the closure member between the wheels 31 110 and outwardly thereof and secured outwardly of these wheels to a corresponding semicircular portion 35 of the gear casing 28 disposed outwardly of the inner wheel 31. lThus is provided a compact and simple construction providing a lamp chamber or enclosure between the revoluble wheels 31.

The extensions 34 and 35 are disposed at the upper` portion of the closure member 33, and secured to a downwardly facing hori- 12'0 zontal surfacevat the lower portion of this closure member is a film face guide plate 36 disposed between the wheels 31. vThis plate has a downwardly facing film face guide surface which is composed lof an intermediate longitudinally extending convex portion 37 corresponding with the periphery of the sprocket comprising tlie wheels 3l and end p ortions 38 tangent to said intermediate portion. An opposing film-face guide member 39 is pivotally mounted, as designated at 41, for movement into and out of film guiding relation with the guide plate 36, this guide member being so mounted to open the guide for the lacing and unlacing of film therein, and to form with the guide plate 36, when it is in film gu'iding relation therewith, a film guide for retaining film therein in engagement with the sprocket comprising the wheels 31 for the feeding of the film. The film face guide surface of the guide member 39 corresponds with the film face guide surface of the guide plate 36, and the inter'- mediate portion of the film face guide surface of the guide member 39 is formed of a separate part 42 which is spring pressed against film in this guide by a spring 43 to insure proper printing relation of superposed films therein at the exposure opening of this guide hereinafter described. The guide member 39 is releasably secured in V film guiding postion in a manner unnecessary to be described.

The guide formed by the guide plate 36 and the guide member 39 is adapted to guide superposed negative and positive films, comprising the aforementioned positive film 14 and another negative film 44, engaged on the sprocket, comprising the wheels 31, for the feeding of these films in printing relation through this guide and past the exposure aperture thereof, hereinafter described, bet een the wheels 31 for printing upon the positive film 14 from the negative film 44. See Figure 13.

This last mentioned exposure aperture is formed as follows. See Figures 11, 12, and 13. The guide plate 36 is provided with a stepped concave formation 45 facing oppositely from the film in the corresponding guide, and the deep part of this formation is disposed immediately adjacent the inner wheel 31 and continues the arc of the convex surface 37 of the plate 36 and forms the exposure opening for the last mentioned guide. See particuarly Figures 11 and 13. A pair of shutter membersy 46 are provided with stepped convex surfaces 47 corresponding with the concave formation 45 of the plate 36 and are engaged therewith at opposite ends of the exposure opening of the plate 36 for angular movement to vary said exposure opening longitudinally of the guide whereby to vary the exposure of the films in this guide as they are fed therethrough at a uniform rate by uniform rotation of the sprocket comprising the wheels 31. Headed'screws 48 are engaged in slots 49, through the plate 36 at the shallower portions of the concave formation 45v and extending longitudinally of the plate, and are screwthreaded into the shutter members 46, whereby these shutter members are adjustably positioned in their said angular movement with respect to the plate 36.

The closure member 33 is provided with an aperture' 51 communicating the exposure aperture of the guide plate 36 with the enclosure formed by this closure member and the wheels 31 as hereinbefore described. See Figures 2, 3, and 13. An incandescentelectric lamp 52 is disposedwithin this enclosure between the exposure aperture of the plate 36 and the portion of the shaft 29 between the wheels 31 and alined with said exposure aperture to provide the printing light at this exposure aperture, and this lamp is mounted in the following manner. See Figures 2, 3, 9, and 10.

The closure member 33 is provided with an internal vertically projecting support 53 which extends in parallelism with the plane of the closure member at theoutside thereof. This support member is provided with a large bore 54 therethrough normal to the plane of the wheels 31 and provided with an outwardly facing shoulder 55 adjacent its inner end. Engaged in the bore 54 and against the shoulder 55 for removal outwardly therefrom is an annular socket block 56 of insulating material. Screwthreaded for longitudinal adn j ustment in the bore of the block 56 is a metal bushing 57 which is bayonet slotted, as designated at 53 in Figure 2, for engagement with radial pins 59 on the usual single contact base 61 of the lamp 52. The bushing 57 is fianged at its outer end, and an annularplate 62 is secured against the fianged end of the bushing for angular adjustment with respect thereto by means of headed screws 63 passing through angular slots 64 in the plate 62 and screwthreaded into the flange of the bushing 57. Secured to the plate 62 on the outside thereof, is a handle 65 of insulating material and anelectrical spring contact 66 which is insulated from the plate 62 in a usual manner. The handle 65-.extends over the center of the plate 62 and the contact 66 underlies the same and contacts the usual center contact 67 of the lamp base 61. The handle 65 provides for the convenient manipulation of the socket just described with the lamp 52 therein through openings 68 formed in the web of the outer wheel 31, and through which openings the socket and lamp 52 thereon may be inserted in or removed from the enclosure formed by the wheels 31 and the closure member 33, the bore 54 of the support 53 permitting passage of the lamp 52 therethrough. The openings 68 are closed by cover members 69 which are releasably secured on the outer wheel 31 by headed screws 70 to permitaccess through these openings.

Electrical contact with the above described socket is established,when thesocket is mounted as above described, in the following manner. Bushings 72 of insulating material are secured in bores through the support 53 and disposed in parallelism with the bore 54 and on diametrically opposite sides of the same.

Secured on these bushings by' means of head- 'ed screws and nuts 7 3 are electric spring contacts 74 and 75 which are connected to oppositesides of an external source of electrical current in a usual manner. The contact 74 is adapted to overlie and contact the outer face of the -plate 62 which is in electrical communication with the metal shell of the lamp base 61 of the lamp 52, which forms one contact thereof, by means of the metal bushing 57. The contact 75 is adapted to overlie the outwardly extending end of the contact 66 which contacts the center contact 67 of the lamp base. Thus is formed an electrical circuit through the lamp 52 when the socket is in one angular position thereof. When it is desired to remove the socket it is given an angular movement to disengage the contact 75 from the contact 66 in which position the Contact 74 disengages from the plate 62 by reason of the plate having a portion of its circumference cutv away on a chord thereof, as designated at 76 in Figure 10. In this position the socket and lamp 52 thereon may' be removed through an opening 68 in the web of the outer wheel 31. Insertion of the socket with the lamp 52 thereon in the enclosure of the Wheels`v 31 and enclosure member 33 is accomplished by inserting them through an opening 68 and passing thellamp through the bore 54 and inserting the socket in the bore 54 with the cutaway portion 76 of the plate 62 registered with the contact 74 and-then turning the socket until the contacts 74 and 75 engage .respectively the plate 62 and the contact 67.

It will be observed that removal of the lamp 52 from and insertion of the same in the enclosure provided bye/.the wheels 31 and the closure member 33 is effected in a simple and convenient manner. In addition the lamp 52 may be adjusted on the socket on which it is mounted both axially and angularly with respect thereto to properly position the filament of the lamp with respect to the exposure opening of the guide plate 36. The screwthreaded engagement of the bushing 57 with the socket block 56 provides for axial adjustment of the lamp 52 in an obvious man'- ner. The angular adjustment of the plate 62 with respect to the bushing 57, provided by the Screws 63 engaged in the slots 64, permits angular adjustment of the lamp by reason of this adjustment permitting a range of angular adjustment of the bushing 57 with respect to a predetermined angular position of the plate 62 when the socket is mounted on the support 53. The lamp 52 may be adjusted on the socket before mounting of the socket in the aforementioned enclosure by means of a suitable setting jig unnecessary tobe described.

As hereinbefore described the photographically sensitized or positive film 14 is fed through the exposure guide ,formed by the guide plates 9 and the guide member 11 in printing relation with the negative film 13, and the positive film 14 is also fed throng the exposure guide formed by the guide plate 36 and the guide member 39 in printing rela- `tion with another negative film 44. These exposure guides are adapted for exposing the photographically sensitized or positive film 14 in printing relation with the respective negative films 13 and 44 progressively therealong, and, as shown, this progressive printing upon the positive film 14 from the two negative films 13 and 44 is effected simultaneously. See Figure 1.

Accordingly the positive film 14 is fed from a feed spool 77 by means of a driven continuous feed sprocket 78, after which it passes through a tensioning device, generally indicated at 79, to the exposure guide, comprising the guide plate 36 and guide member 39, through which it is fed continuously at a uniform rate in superposed printing relation with the negative film 44 past the exposure:l aperture of this guide by means of the driven continuous feed sprocket comprising the wheels 31 for printing by means of the light provided by the lamp 52. Leaving this exposure guide the positive film is fed' by a driven continuous feed sprocket 81, after which it passes through a tensioning device, generally indicated at 82, to the exposure guide, comprising the guide plates 9 and the guide member, 11, through which it is fed continuously at a uniform rate in superposed printing relation with the negative film 13 past the exposure aperture of this guide by means of the driven continuous feed sprocket comprising the wheels 7 for printing by means of the light provided by the lamp 3. Leaving this last mentioned exposure guide the positive film is fed by a driven continuous feed sprocket 83, after which it is wound upon a driven winding spool 84.

r'I`he negative film 44 is fed from a feed spool 85 by mea-ns of the aforementioned driven sprocket 78, after which it passes through a tensioning device, generally indicated at 86, to the exposure guide, comprising the guide plate 36 and guide member 39, through which it is fed, as aforesaid, by the driven sprocket, comprising the wheels 31. Leaving this exposure guide the negative film 44 is fed by a driven continuous feed sprocket 87, after which it is wound upon a driven winding spool 88.

The negative film 13 is fed from a feed spool 89 by means of the aforementioned driven sprocket 81, after which it passes through a tensioning device, generally indicated at 91, to the exposure guide, comprising the guide plates 9 and the guide member l1, through which it is fed, as aforesaid, by the driven sprocket, comprising the wheels 7.

Leaving this exposure guide tknegative film' 13 vis fed by the aforementioned driven sprocket'83, after which it is wound upon a driven winding spool 92.

The sprockets 78, 81, 83, 87, the sprocket comprising the wheels 31 and the sprocket comprisingl the wheels 7 are connected to be driven at equal peripheral speeds by means of a gear train 93 enclosed within the gear casing 28.

An electric motor 94, secured on a bracket 0f the pedestal 1, drives the gear train 93 through the medium of a belt and pulley driving device, generally indicated at 95, including a belt 96 which is trainedover pulleys 97 secured with the winding spools 84 and 92 to drive the same. The winding spool 88 is driven from the upper portion of the gear train 93 by means of a belt and pulley driving device 98. spools of the machine are mounted in a suitable manner upon a pipe frame 99 secured with the frame of the machine and with the pedestal.

The exposure apertures of the aforemen- 4tioned exposure guides are adapted to expose different adjoining longitudinal sections of the positive film 14 in printing relation with respective portions of the negative films 13 and 44, and each of the exposure guides are masked to prevent exposure thereby of the longitudinal section ofthe positive film which is exposed by the other exposure guide.

Accordingly, the exposure aperture of the exposure guide, comprising the guide plate 36 and the guide member 39, extends laterally of the guide from the inner wheel 31 outwardly therefrom to define a comparatively narrow longitudinal side section of the picture portion of the film in this guide, the.

exposure aperture of this guide being limited laterally by the inner wheel 31 and the lonfritudinal edge 100 of the deeper portion of t ie concave formation 45. See Figures 2 and 11. Accordingly the remaining and comparatively wide longitudinal section of the picture portion of the films in this guide are masked from exposure in this guide, the gui-de plate 36 having no'light opening therein between the outer edge 100 of the exposure opening thereof and the outer wheel 31,whereby the corresponding longitudinal section of the positive film is not exposed 1n this guide. Likewise the only part of the negativel film V44 which is effective to print upon the positive film 14 in the last mentioned exposure guide is that longitudinal section thereof which corresponds with the exposure aperture of this guide, i. e.,'the portion defined by the'innerwheel 31 and the edge 100 of the plate se.

The exposure aperture of the exposure guide, comprising the guide plates 9 and the guide member 11, extending laterally of this guide from the outer wheel 7 to the outer edge of the flange of the inner wheel 7, which The winding and feed.

flange is extended outwardly, as designated at 101, to mask and thereby prevent exposure in this guide, of the longitudinal side section of the films in this guide correspondingwith the portion of the films exposed in the guide, comprising the guide plate 36 and the guide member 39, between the inner wheel 31 and the edge 100 of the guide plate 36.

Thus are the two longitudinal sections of the positive film 14 printed simultaneously respectively from the negative films 13 and 44 progressively therealong.

The negative film 44, which prints the comparatively narrow longitudinal section of the positive film 14, preferably bears a visual sound record which is printed upon the positive film along said section thereof for translation by suitable means to reproduce from the developed positive film the original sounds recorded on the corresponding longitudinal section of the negative film 44.

The negative film 13, which prints' the comparatively wide longitudinal section of the positive film 14, preferably bears motion pictures which are printed upon the positive film along said section thereof for the projection of motion pictures from the developed positive film by a suitable motion picture projecting machine.

The visual sound record and the motion pictures printed upon the positive film 14 are related for the exhibiting of the so-called talking motion pictures.

Figure 6 shows Va portion of the positive film 14 after printing and development, in which 102 designates the comparatively narrow longitudinal section thereof upon which the sound record is printed, and 103 designates' the comparatively wide longitudinal section thereof upon which the motion pictures are printed.

Figure 7 shows a portion of the motion picture bearing negative film 13, in which 104 designates the comparatively wide longitudinal section thereof upon which the motion pictures are disposed and which corresponds with the section 103 of the positive film 14.

Figure '8 shows aportion of the visual sound record bearing negative film 44, in ywhich 105 designates the compara-tively narrow longitudinal section thereof upon which the sound record is disposed and which corresponds with the section 102 of the positive film 14.

It will be observed that means is provided for independently varying the printing light -at the several exposure apertures, with the by the adjustment of the shutter members 46 to vary the associated exposure aperture longitudinally of the movement of the film, it being not necessary to change this adjustment durin the printing operation for the reason that t e sound record is photographed upon the negative film 44 4under manually controlled conditions whereby a uniform intensity of the negative is obtainable. 'y

The adjustment of the printing light for the printing of the motion pictures is variable by adjustment of either the shutter member 16 or the shutter member 25. Preferably adjustment of the shutter member 16 is more or less permanent, say for the printing from an entire negative film while the shutter member 25 is adjusted during the printing operation to vary the printing light to effect the printing of the motion pictures upon the positive film with a uniform density, it being noted that it is usual that different motion picture scenes are photographed upon the corresponding negative film under different light conditions with resulting different densities` of the different scenes on the negative.

It is desirable that the printing operation or the movement of the films, particularly inv the printing of the second record, shall be continuous and uninterrupted.

Accordingly the adjustment of the shutter member 25 is effected during the printing operation and without interrupting the printing operation or the movement of the films. The various means for so adjusting the shutter 25 are well known, and conform basically with that described and claimed in my U. S. Letters Patent Reissue N o. 14,799, reissued February 3, 1920, for improvement in photographic printing apparatus, and as shown enerally herein consists of an electric circuit reaker 106, see Figure 1, under the control of an edge of the motion picture bearing negative film 13, which edge is notched, as designated at 107 in Figure 7, at intervals therealong corresponding with the light changes to be made in printing from this film, an adjusting device 108see Figure 1, conenected with the arm 26 for variably adjusting the shutter 25 and under the control of the circuit breaker 106 to function when the circuit breaker is actuated by a notch 107 of the film 13, and a manually adjusted device 109 for predeterminately setting the adj usting device 108 to effect a desired adjustment of the shutter 25 when the circuit breaker is actuated by a notch 107 of the film 13 to cause the adjusting device 108 to function, the device 109 being reset after each adjustment of the shutter 25 ina predetermined manner.

While I have described and shown one form ofmy invention I do not wish to be limited to the .precise details of construction Shown, as changes may readily be made without departing from the spirit of my invention,

but having thus described my invention, I'

claim as new and desire to secure by Letters Patent the following:

1. In a. photographic printing machine the combination with a revoluble film feed sprocket comprising two axially spaced wheels at least one of which is periplierally toothed and an axial spindle extending therecandescent electric lamp within said en-4 closure between said spindle and exposure aperture and carried by said closure member.

2. In a photographic printing machine the combination with a frame, of a spindle revolubly mounted on said frame and projecting therefrom, a film feed sprocket on the projecting portion of said spindle and comprising axially spaced wheels at least one of which is peripherally toothed, a film guide disposed for guiding superposed films engaged on said sprocket and provided with an exposure aperture between said wheels and facing inwardly of the sprocket, a closure member forming an enclosure between said wheels and communicating with said exposure aperture, a source of photographic light within said enclosure and carried by Said closure member, and means whereby said closure member is carried by said frame and extending from said closure member between said wheels and outwardly thereof.

3. In a. photographic printing machine the combination with a frame, of a spindle revolubly mounted on said frame and projecting therefrom, a film feed sprocket on the projecting portion of said spindle and comprising axially spaced wheels having the peripheral portions thereof projected toward each other and at least one of which is peripherally toothed, a stationary film guide of arcal formation disposed correspondingly with. the periphery of said sprocket for guiding superposed films engaged on said sprocket and provided with an exposure aperture between said wheels and facing inwardly of the sprocket, a stationary-closure member of generally circulaiform disposed between said wheels and underlying said projected peripheral portions of said wheels and forming an enclosure therewith communicating with said exposure aperture, an incandescent electrical lamp within said enclosure between saidspindle and exposure aperture and carried by said closure member, and means whereby sald closure member is carried by said frame and extending from said closure .llil

3 sprocket comprising 1G descent electric lamp is 2o wheels at least one of may be inserted in the same,

cent electric the same,

within said enclosure,

15 and means closing said opening and adapted to permit access through said opening.

5. In a photographic film printing machine the combination with a revoluble film feed sprocket comprising two axially spaced which is peripherally toothed, of a. stationary closuremember forming an enclosure with said wheels between the same, an incandescent electric lamp socket, a mounting on said closure 25 member within said enclosure for the detachablev mounting thereon of said socket, one of said wheels having an opening through the web thereof through which said socket with an incandescent electric lamp thereon or removed from said enclosure, and means closing said opening and adapted topermit access through said opening.

6.' In a photographic film printing machine 35 the combination with a revoluble film feed sprocket comprising ytwo axially spaced wheels at least one of which is peripherally toothed, of a stationary closure member forming an enclosure with said wheels` between an incandescent electric lamp socket provided with circuit contacts, a mounting on said closure member within said enclosure for the detachable mounting thereon of said socket, circuit contacts on said closure mem- 45 bei' adapted to releasably engage said circuit contacts of the socket when the socket is engaged on said mounting, one of said wheels having an opening through the web thereof through which said socket with an incandeslamp thereon may be inserted in or removed from said enclosure, and means closing said opening and adapted to permit access through said opening.

7. In a photographic sprocket comprising two axially spaced wheels at least one of which is peripherally toothed, of a stationary closure member forming an enclosure with said wheels between an incandescent electric lamp socket, means" for adjustably mounting an incandescent electric lamp on said socket, means whereby said socket is mounted in a predetermined position on said closure member one of said wheels -film printing ma-l 55 chine the combination with a revoluble feed respect to said guide having an opening in the web thereof through which the socket and the lamp thereon may' be inserted in or removed from said enclosure, and means closing said opening and adapted to permit access through said opening.

S. In a photographic iilm printing machine the combination with a revoluble feedA sprocket comprising two axially spaced wheels at least one of which is peripherally toothed, of a stationaryT closure member formingl an enclosure with said wheels between the same and provided with a sliouldered bore within said enclosure, an incandescent eleciic lamp socket removably engaged in said bore and against said shoulder for angular movement therein, means on said socket for adjustably positioning an incandescent electric lamp mounted'thereon, circuit contacts carried with saidv closure member and said socket adapted for Contact in a predetermined angular position of said socket in said bore and disengaging in another angular position of said socket for removal of the socket from said bore, one of said wheels having an opening in the web thereof through which the socket and the lamp mounted thereon may be inserted in or removed from said enclosure, and means closing said opening and adapted to permit access through said opening.

9. Ina photographic printing machine the combination with a constant feed lilm exposure guide including a film face guide member provided with an exposure opening and with a concave surface facing oppositely from film in the guide and extending longitudinally of the guide and longitudinally alined with said exposure openinga shutter member provided with a corresponding convex surface engaged with said concave surface for angular movement to vary said exposure opening, and means for adjustably positioning said shutter member in said angular movement tosaid guide member.

10. In a photographic printing machine the combination with a constant feed film guide includinga film face guide member having a concave formation facingoppositely from film in the guide and extending longitudinally of the guide member and forming an intermediate exposure opening therethrough, a pair of shutter members provided with coiresponding convex/surfaces engaged with said concave formation at opposite ends of said exposure opening for angular movement to vary said exposure opening, and

means for adjustably positioning said shutter members in said angular movement with member.

11. In a photographic printing machine` the combination with aconstant feed film guide includingv a film face uide member having 'its film face 'guide sur ace composed of an intermediate longitudinally extending convex portion and end portions tangent thereto and provided with e; concave formation facing oppositelyfrom film in the guide and continuing the are o said intermediate portion and forming an exposure opening at said intermediate portion, a pair of shutter members provided with corresponding convex 'surfaces engaged with said concave formation at opposite ends of said exposure opening for angular movement to vary said exposure opening, and means for adjustably positioning said shutter members in said anguiar movement with respect to said guide member. In Witness whereof I hereunto ax my sig nature this 13th day of August, 1927-? ALBERT S. HQWELL.'

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