US2891443A

US2891443A - Photographic color printer

Info

Publication number: US2891443A
Application number: US636045A
Authority: US
Inventors: John S Pollock
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1957-01-24
Filing date: 1957-01-24
Publication date: 1959-06-23
Anticipated expiration: 1976-06-23

Description

June 23, 1959 Filed Jan. 24, 1957 J. s. POLLOCK 'PHOTOGRAPHIC COLOR PRINTER 2 Sheets-Sheet 1 John SPollock INVENTOR.

ATTORNEYS June 1959 J. s. POLLOCK 2,891,443

- PHOTOGRAPHIC COLOR PRINTER JohnSJollock F g. 5 jVVBNTOR.

' 'ATTORNEYS United States Patent PHOTOGRAPHIC COLOR PRINTER John S. Pollock, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Application January 24, 1957, Serial No. 636,045

7 Claims. (CI. 88-24) The present invention relates to photographic printers, and particularly to an automatic color printer for successively making a series of prints on a continuous strip of color print material and equipped with a border flashing means for printing white borders on the prints which is adjustable so that no change of border masks is required to provide borders for any print length.

In the making of color prints on reversal type color print material, it is necessary to flash the border areas of a print with white light during printing in order to obtain a white border on the finished print. This adds one printing step to that of making black-and-white prints in that it requires exposing the border areas of a print to light while masking oil the picture area. This added border printing step has necessitated combining with automatic printers adapted to make a series of color prints in succession on a continuous strip of color print material a border flashing unit which flashes the white borders on the print material before or after the picture area has been printed and which picture area must be masked off during the border flashing. This has been done in known strip printers by combining with the main printers a contact printer having a rectangular border mask of a size corresponding to the print to be made which would flash the border area and mask oil the picture area either before or after the picture was printed. This arrangement proved unsatisfactory because most automatic strip printers are adapted for printing a number of different size prints, which differ in length but not width, i.e., 3V2" x 3%", 3 /2" x 3 /2, 3 /2" 2; 5", etc., and this meant that when the printer was adjusted for making prints of a different size the operator must remember to change the border masks to correspond to the chosen print size. Since most strip printers have the sensitive paper entirely enclosed in a light-tight casing so that the printer can be operated in the light, such a change in border masks necessitated going dark to make the change in border masks.

The primary object of the present invention is to provide an automatic strip type color printer adapted to make prints of constant width but of varying length having a border flashing unit which can be adjusted to provide the proper border for a chosen size of print without having to change border masks or going dark to make such adjustment.

Another object of the invention is to provide a border flashing mask which is so designed that it can be used with a color strip printer to flash the borders on a range of different print sizes which the printer is capable of producing.

And another object is to provide a color strip printer of the type described with a border flashing unit comprising a contact printer adjustably mounted relative to the printing aperture of the printer along the path of the print material and having on its top surface a border flashing mask in the form of a U or an H. The parallel arms of the border flashing mask are longer than the longest print the printer is capable of making and serve a to flash the longitudinal borders on the prints while the cross arm of the mask is double the width of the borders desired on the end of the prints and prints the end borders of two adjacent prints simultaneously. The contact printer is adjusted relative to the printing aperture of the printer in correspondence with the intermittent feed of the print material so that the areas of the strip exposed at the printing aperture and by the cross arm of the border flashing mask will abut each other and not overlap.

And still another object is to provide a color strip printer of the type described in which means are provided for adjusting the border flashing unit in accordance with the size of print to which the printer is ad justed, either automatically or selectively.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its methods of operation, together with additional objects and advantages thereof, will best be understood from the following description when read in connection with the accompanying drawings, in which:

Fig. 1 is a partial front elevational view, partly in section and with the doors of the paper compartment open, of a photographic strip printer for making color printers constructed in accordance with one embodiment of the present invention;

Fig. 2 is an enlarged detail plan view of that portion of the paper path of the printer including the border flashing means and the printing aperture with the paper platens above the flashing unit and the printing aperture removed and part of the top of the channel support for the border flashing unit broken away to show the mounting for the flashing unit;

Fig. 3 is a side elevational view corresponding to Fig. 2, but with the printing mask shown in section to show the size of the printing aperture;

Fig. 4 is an enlarged detail taken substantially on line 44 of Fig. 3 and showing the manner of mounting the border flashing unit so that its alignment with the printing aperture and paper path can be accurately adjusted; and

Fig. 5 is a schematic plan view of the paper path in the printer and showing another form of border flashing mask which might be used in place of the one shown in Fig. 2.

While the present invention may be applied to any known type of strip type photographic printer adapted for making reversal type color prints, in Fig. 1 I have shown it in combination with a projection printer of a known type in which the color print material 10 in strip form is contained within a housing 11 which can be rendered light-tight by closing hinged doors 12. The color print material is adapted to be intermittently advanced across an image plane defined by a printing mask 13 having an exposure aperture 14 at which point the light-sensitive surface of the print material is exposed to the image of a color negative N illuminated by and projected by a projection system including lamp 15, condenser lenses 16 and projection lens 17. The print material 10 is held flat on the printing mask 13 by a floating platen 18 which, by virtue of its loose mounting, permits the paper material to be fed across the exposure aperture Without need for raising the platen.

As a customary in stripprinters of this type, a succession of prints are adapted to be made on a continuous strip of print material and chopped into individual .print being made and the exposures being made during" the dwell periods in the feed. While any known intermittent' feed might be used for the print material, I have chosen to show one of the forms disclosed in US. Patent 2,541,013, Clutz, for purposes of the present disclosure, and to which patent reference can be had for a complete disclosure of the same. So far as the present invention is concerned, it will suffice to say that the print material is led from a supply roll over a guide roll 21 which is so positioned as to provide a substantial wrap of the same about the flanged measuring feed roll 22, thence across the exposure plane and over guide roll 23 and to the take-up roll 24. Supply roll 20 has a frictional drag to prevent the same from overrunning as the measuring feed roll 22 pulls the strip therefrom and take-up roll 24 has a constantly operating friction clutch which tends to take up the material as the measuring roll feeds it forward and thus place the desired length of material across the exposure plane under tension to hold it flat without breaking the strip. As fully disclosed in the above-noted Clutz patent, the measuring roll 22 is driven through a friction clutch including a pawl and ratchet which, when engaged, holds the roll still and which, when disengaged, allows the roll to rotate. The pawl is momentarily disengaged from the ratchet by a solenoid to start a paper advance and is prevented from re-engaging the ratchet to stop the drive until a given length of paper has been advanced by a cam which rotates with the roll and which engages the pawl and holds it out of engagement with the ratchet for a given percentage of rotation of the measuring roll. By adjusting the knob 25 with the aid of scale 26 the effective length of this hold-out cam, and the degree of rotation of the measuring roll 22 per cycle can be varied to correspond with different print lengths which the printer can accommodate. The reference numeral 27 designates a spring-loaded bracket carrying a roller which presses the strip of print material tightly against the rubber surface of the measuring feed roll 22 to insure there is no slip of the material relative thereto.

It is customary in strip printers of this type to make different sized prints from different sizes of negatives, but the size of the print varies only in length, not width, because the print material 10 is of fixed width. For example, the following sizes of prints are commonly made on such printers using a 3 /2" wide print material, 3%" x 3%; 3 /2" x 3 /2, 3 /2" x 5", etc. and these sizes can be readily accommodated by merely changing the size of the printing mask 13 to one having an exposure aperture 14 of the proper length and correspondingly changing the length of feed of the print material at each advance by appropriate adjustment of knob 25. To permit easy changing of the printing masks 13, each mask regardless of size, is provided along its rear edge 30 with a plurality of slots 31 which are adapted to engage corresponding lugs 32 extending upward from the top of a channel-shaped support 33 which extends lengthwise of the housing 11 and forms the support for the printing masks and the border flashing unit.

Adjustably mounted on the support 33 between the printing station and the measuring feed roll 22 is a border flashing unit designated generally as 35. This flashing unit is a contact photographic printer comprising a light-tight casing 36 of the form best shown in Fig. 3 having a transparent or translucent top wall 37 which extends through an opening in the top of the channelshaped support 33 and lies substantially in the same plane as the top of the printing mask 13. Contained within the casing 36 is one or more lamps 38, the light from which is reflected by a mirror 39 on the inclined wall 40 of the casing to illuminate the transparent top wall 37. A border flashing mask 41 of the form shown in Fig. 2 is positioned on the top wall 37 of the contact printer by having spaced holes 42 in one edge thereof engaging lugs 43 extending upward from the printer top wall. This border mask comprises an opaque sheet having a transparent area in the form of an H and while it can be a stamped-out sheet of opaque material, it is preferable to make it photographically from a sheet of lightsensitive film because a mask so made has no sharp edges across which the color print material must be drawn and is not destructable by tearing.

The mask is so disposed relative to the path of the color print material that the parallel side arms of the H expose the opposite longitudinal edges of the material as it is moved across the mask and form the longitudinal borders of the prints, which borders are generally wide. The cross bar of the H forms the end borders on the prints and is twice as Wide as the desired print border because it forms the end borders on two adjacent prints at each printing. The longitudinal clear areas of the H are somewhat longer than the longest print to be made on the primary printer so that the longitudinal borders flashed at each printing cycle, i.e., when the print material is stationary, will overlap (the amount of overlap depending upon print length) the edge-flashed area of the succeeding print while the cross bar of the H is exposing the adjacent end borders of two prints. In Fig. 2 the borders on the strip of material outlined in dotted lines represent border areas flashed on the strip during previous exposures as the strip moves stepwise from the border flashing unit to, and into alignment with, the exposure aperture 14 in the printing mask 13 of the primary printer where the picture on the negative N is printed within the flashed border areas.

It will be appreciated that the border flashing mask 41 must be so positioned in the path of the print material relative to the exposure aperture 13 of the printing mask 14 that when the material is stopped at the end of each advance the leading edge 45 and trailing edge 46 of an area previously flashed by the cross bar of the H will be aligned with the opposite transverse edges of the exposure aperture 14 in the printing mask 13 when the intermittent advance of the print material is equal to the overall print length, as shown clearly in Fig. 2.

The ends 47 of the longitudinal areas of the H mask may be feathered or tapered as shown to blend any small offset in the print border where the overlap stops, and which oifset might occur due to imperfect tracking of the print material from print to print.

In Fig. 5 I have shown another form of border flashing mask which might be used, instead of the H mask described. Here the openended border flashing mask 41' takes the form of a U, the parallel longitudinal arms of which are longer than the longest print to be made and the cross bar of which is twice as wide as the end borders desired on the prints. As in the case of the H mask the cross bar of the U must be spaced from the exposure aperture 14 of the printing mask by a multiple of a print length so that the flashed borders will properly align with the edges of the exposure aperture to border the picture printed therethrough. Here again the ends 47' of the longitudinal areas of the U may be feathered or tapered, as shown, to blend any small offset in the print border which might occur due to imperfect tracking of the print material from print to print.

When the length of print to be made is changed, this means putting in a new printing mask 13 having the desired size of exposure aperture 14 and changing the length of advance of the intermittent feed for the print material to correspond thereto. For example, if the print size is changed from a 3% x 3 /2" to a 3 /2" x 5", then the paper advance must be increased from 3 /2" per cycle to 5" per cycle. At the same time the distance between the border flashing unit 35 and the exposure aperture 14 of the printing mask 13 must be increased so that the cross bar of the

border flashing mask

41 or 41 will be spaced from the exposure aperture 14 by a multiple of the new print length.

This adjustment of the border flashing unit 35 is made possible in the present combination by mounting the cas ing 36 on the channel-shaped support 33 so that it can be moved toward and from the exposure aperture 14 of the printing mask 13. To this end the rear side of the casing 36 carries a grooved roller 50 which rides on a rod 51 fixed to and extending from the rear vertical wall 52 of the support channel 33. Two ball bearings 53 fixed to the front wall of the casing 36 engage a guide rod 54 spaced from, and extending parallel to, the front wall 55 of the channel support 33. So that the travel of the casing 36 can be accurately adjusted relative to the path of the print material, the opposite ends of guide rod 54 are mounted in supports 56 fixed to the front wall 55 of channel support 33, said supports having an elongated slot 57 by means of which the rod 54 can be shifted fore and aft by adjustment of set

screws

58 and 59.

One way of automatically adjusting the border flashing unit to the proper position for a given length of print is to connect a tension spring 60 at one end to the casing 36 and at the other end to the channel-shaped support 33, see Fig. 3, so that the casing is normally urged into abutment with the end wall 61 of the printing mask 13, see Figs. 2 and 3. Now if each printing mask 13 has a different width, and one which will position the cross bar of the border flashing mask 41 on the casing 36 the proper distance from its exposure aperture 14, then each time a printing mask is put in position, its edge 61 will properly position the border flashing unit.

On the other hand, if it is not desired or convenient to alter the overall physical dimensions of the printing masks according to the size of their exposure aperture, or it is desired to adjust the border flashing unit 35 from outside the housing 11 without requiring the doors 12 to be opened, then an alternative adjusting system can be used. As shown in Fig. 3, such an adjusting system might comprise a headed stud 65, fixed to and extending vertically downward from the bottom of the casing, which is engaged by the forked arm 66 fixed to the end of a shaft 67 extending through the bottom wall 68 of the housing 11. A crank 69 fixed to shaft 67 when oscillated will adjust the border flashing unit 35 along the path of its print material toward and from the printing mask. To facilitate the proper adjustment of the border flashing unit through its three or four different positions, a disk 70 fixed to the bottom wall of the housing is provided with a plurality of arcuately spaced detents 71 into and out of which a spring-pressed ball 72 on the crank might snap as the crank is oscillated so as to inform the operator, by sense of feel, of the position of adjustment of the border flashing unit. If this form of crank adjustment is used for the border flashing unit, there is no need for the biasing spring 60 shown in Fig. 3.

As is well known in the art, for best results in a contact printer the light-sensitive paper should be held in firm contact with the negative or mask during printing and that to this end a platen is usually used. Such a platen is provided in the present border flashing unit and is one of the type which presses the print material into contact with the border flashing mask 41 during the time the print material is stationary and lifts to allow the material to be advanced. While any suitable platen arrangement could be used on the present border flashing unit within the scope of the present invention so long as it can be automatically operated in timed relation with the intermittent feeding movement of the print material, I have shown one in which the platen is normally raised and solenoid operated to a holding position. As shown in Fig. 1, this platen comprises a rubber-faced pressure plate 75 having a pair of spaced pins 76 extending vertically upward from the top thereof which have their shanks provided with a tapered groove leaving enlarged heads on the pins. Mounted on the back wall of the housing, or to some other stationary surface, is a U-shaped bracket 77 with the open side thereof facing the front of the printer. A pair of tension springs 78 fixed at one end to a rod 79 extending across the arms of this bracket are through which the pins 76 extend. The diameter of these holes is smaller than the largest diameter and head on the pins but larger than the grooved portion thereof to provide a form of lost motion connection between plate 80 and pressure plate 75 which permits the pressure plate to maintain a horizontal position when moved up and down by pivotal action of plate 80. Accordingly, springs 78 acting through plate 80 and its lost motion connection with pins 76 normally move the pressure plate 75 upwardly and out of contact with the print material 10. To move the pressure plate 75 into pressure contact with the print material for printing purposes, I have shown a rotary solenoid 82 on whose shaft there is mounted a cam 83 which engages the top of plate 80 and pushes it down against springs 78 when the solenoid is actuated; This solenoid can be automatically energized at the time the paper advance stops and de-energized just before the paper advance begins by a suitable microswitch arrangement such as that which would normally be used to turn, on the lights of the contact printer and the primary printer when the paper stops to make an exposure and turn them oif before the paper starts to move, as is well known in the art.

Applicant would point out that while for purposes of illustration he has shown his border flashing unit combined with a strip printer in such a way that the borders are flashed on the print material prior to printing the negative image, the order could just as well be reversed, i.e., the borders could be flashed on the strip after the negative image was printed thereon. This change would merely involve reversing the direction of feed of the strip of print material in the disclosed arrangement of border flashing unit and primary printer, or placing the border flashing unit on the other side of the primary printer if the same direction of feed of print material as shown is to be retained. In any case, it will be appreciated that the direction of feed of the print material and/or the relative location of the border flashing unit and primary printer exposure aperture are optional with in the scope of the present invention.

While I have shown and described certain specific embodiments of my invention, I am fully aware that many modifications thereof are possible. fore, is not to be limited to the specific structural details shown and described, but is intended to cover all modifications coming within the scope of the appended claims.

Having thus described my invention, what -I claim as new and desire to secure by Letters Patent of the United States is:

1. In a photographic printer for making a series of color prints of a single width but of variable length in succession on a continuous strip of color print material the combination with means for projecting a picture to be printed onto an image plane; means for interchangeably supporting diflerent printing masks in said image plane and which masks are equal in width but may vary in length; means for intermittently advancing a continuous strip of color print material in said image plane and across the printing mask from a supply roll thereof and including means for varying the length of advance of said print material to correspond with the size of the printing mask being used; of a border flashing unit spaced from said printing mask in the path of said print material comprising a contact printer across a light-transmitting top of which said strip of print material is adapted to be intermittently moved by said advancing means; means Within said contact printer for illuminating the top thereof each time the strip of material stops; a border flashing mask separate from said printing masks covering the top of said contact printer and into contact with which the strip is pressed each time it stops, comprising an opaque support provided with two like elongated light-transmitin parallel relation to expose the opposite longitudinal My invention, there:

edges of said strip with a border of the width desired on the finished prints and having a length greater than the longest print to be made; said opaque support also pro vided with a transverse light-transmitting area joining, and extending perpendicular to, said elongated light-transmitting areas and having a width equal to twice the width of the border desired on said prints so as to expose the end border on two adjacent prints at one time; and means for adjusting said contact printer relative to said printing mask along the path of movement of said strip of material whereby the distance between the transverse lighttransmitting area of said border flashing mask and said printing mask being used in the printer is equal to a multiple of the length of strip being advanced by said strip advancing means whereby the area of the strip of color print material moved into alignment with said printing mask will be that within the borders flashed onto the strip by said border mask.

2. A photographic printer according to claim 1 characterized by the fact that said printing mask, said contact printer and the intermittent advancing means for said print material are contained within a light-tight housing; and the means for adjusting the position of said contact printer relative to said printing mask includes a part accessible from outside said housing whereby the necessary adjustment can be made without opening said housing.

3. A mask for flashing on a strip of color print material white borders of equal width in surrounding relation with each of a series of color prints of a single width but of variable length adapted to be made on said strip of color print material in succession as the strip is fed intermittently past a printing station comprising a flat opaque support adapted to. be placed in contact with the light-sensitive surface of said print material and provided with two elongated light-transmitting areas of equal width spaced in parallel relation to expose the opposite longitudinal borders of the strip with a border of the width desired on the prints and having a length longer than the longest print to be masked, and provided with a light-transmitting area joining and extending perependicularly to said elongated light-transmitting areas, said lastmentioned light-transmitting area having a width equal to twice the width of said elongated light-transmitting areas so as to expose the end border on two adjacent prints at one time.

4. In a photographic printer for making a series of color prints of a single width but of variable length in succession on a continuous strip of color print material the combination with means for projecting a picture to be printed onto an image plane; means for interchangeably supporting diflerent printing masks in said image plane and which masks are equal in width but may vary in length; means for intermittently advancing a continuous strip of color print material in said image plane and across the printing mask from a supply roll thereof and including means for varying the length of advance of said print material to correspond with the size of the printing mask being used; of a border flashing unit spaced from said printing mask in the path of said print material comprising a contact printer across a light-transmitting top of which said strip of print material is adapted to be intermittently moved by said advancing means; means within said contact printer for illuminating the top thereof each time the strip of material stops; a border flashing mask covering the top of said contact printer and into contact with which the strip is pressed each time it stops, comprising an opaque support provided with two like elongated light-transn'iitting areas extending lengthwise of said strip and spaced in parallel relation to expose the opposite longitudinal edges of said strip with a border of the width desired on the finished prints and having a length greater than the longest print to be made; said opaque support also provided with a transverse light-transmitting area joining, and extending perpendicular to, said elon- 8 gated light-transmitting areas and having a width equal to twice the width of the border desired on said prints so as to expose the end border on two adjacent prints at one time; the unjoined ends of each of the longitudinal lighttransmitting areas of the border mask narrowed down by tapering the innermost edge of each toward the outer edge to blend any small oflset in the longitudinal print borders; and means for adjusting said contact printer relative to said printing mask along the path of movement of said strip of material whereby the distance between the transverse light-transmitting area of said border flashing mask and said printing mask being used in the printer is equal to a multiple of the length of strip being advanced by said strip advancing means whereby the area of the strip of color print material moved into alignment with said printing mask will be that within the borders flashed onto the strip by said border mask.

5. In a photographic printer for making a series of color prints of a single width but of variable length in succession on a continuous strip of color print material the combination with means for projecting a picture to be printed onto an image plane; means for interchangeably supporting different printing masks in said image plane and which masks are equal in width but may vary in length; means for intermittently advancing a continuous strip of color print material in said image plane and across the printing mask from a supply roll thereof and including means for varying the length of advance of said print material to correspond with the size of the printing mask being used; of a border flashing unit spaced from said printing mask in the path of said print material comprising a contact printer across a light-transmitting top of which said strip of print material is adapted to be intermittently moved by said advancing means; means within said contact printer for illuminating the top thereof each time the strip of material stops; a border flashing mask separate from said printing masks covering the top of said contact printer and into contact with which the strip is pressed each time it stops, comprising an opaque support provided with light transmitting areas in the forms of a U or H where the upright arms of the U or H are parallel to the edges of the strip of print material to expose the opposite longitudinal edges of said strip with a border of the width desired on the finished prints and having a length greater than the longest print to be made, and the cross bar of either is transverse to the strip of material and has a width equal to twice the width of the border desired on said prints so as to expose the end border on two adjacent prints at one time; and means for adjusting said contact printer relative to said printing mask along the path of movement of said strip of material whereby the distance between the transverse light-transmitting area of said border flashing mask and said printing mask being used in the printer is equal to a multiple of the length of strip being advanced by said strip advancing means whereby the area of the strip of color print material moved into alignment with said printing mask will be that within the borders flashed onto the strip by said border mask.

6. In a photographic printer for making a series of color prints of a single width but of variable length in succession on a continuous strip of color print material the combination with means for projecting a picture to be printed onto an image plane; means for interchangeably supporting different printing masks in said image plane and which masks are equal in width but may vary in length; means for intermittently advancing a continuous strip of color print material in said image plane and across the printing mask from a supply roll thereof and including means for varying the length of advance of said print material to correspond with the size of the printing mask being used; of a border flashing unit spaced from said printing mask in the path of said print material comprising a contact printer across a light-transmitting top of which said strip of print material is adapted to be intermittently moved by said advancing means; means within said contact printer for illuminating the top thereof each time the strip of material stops; a border flashing mask separate from said printing masks covering the top of said contact printer and into contact with which the strip is pressed each time it stops, comprising an opaque support provided with two like elongated light-transmitting areas extending lengthwise of said strip and spaced in parallel relation to expose the opposite longitudinal edges of said strip with a border of the width desired on the finished prints and having a length greater than the longest print to be made; said opaque support also provided with a transverse lighttransmitting area joining, and extending perpendicular to, said elongated light-transmitting areas and having a width equal to twice the width of the border desired on said prints so as to expose the end border on two adjacent prints at one time; and means for adjusting said contact printer relative to said printing mask along the path of movement of said strip of material whereby the distance between the transverse light-transmitting area of said border flashing mask and said printing mask being used in the printer is equal to a multiple of the length of strip being advanced by said strip advancing means whereby the area of the strip of color print material moved into alignment with said printing mask will be that within the borders flashed onto the strip by said border mask, said adjusting means comprising slidably mounting said contact printer to move to and from said printing mask; spring loading said contact printer to move into physical contact with a locating part integral with the print mask in use, said locating part being integral with each printing mask having a dimension peculiar to the aperture size of the mask with which it is associated whereby it will position the contact printer from the printing mask with which it is associated by an amount commensurate with the size of the print to be made.

7. A mask for flashing the white borders on a strip of color print material on which a series of color prints of a single width but of variable length are to be made in succession as the strip is fed intermittently past a printing station comprising a flat opaque support adapted to be placed in contact with the light-sensitive surface of said print material and provided with two like elongated light-transmitting areas spaced in parallel relation to expose the opposite longitudinal borders of the strip with a border as desired on the prints and having a length longer than the longest print to be masked, and provided with a light-transmitting area joining and extending perpendicularly to said elongated light-transmitting areas, said last-mentioned light-transmitting area having a width equal to twice the Width of the border desired on said prints so as to expose the end border on two adjacent prints at one time; and the unjoined ends of the elongated light-transmitting areas being narrowed down by tapering the innermost edge of each toward the outer edge to blend any small offset in the longitudinal print borders.

References Cited in the file of this patent UNITED STATES PATENTS 1,734,780 Simjian Nov. 5, 1929 1,795,050 Simjian Mar. 3, 1931 FOREIGN PATENTS 590,189 Great Britain July 10, 1947