US2237704A - Vacuum holder for negative plates - Google Patents

Description

VACCUUM HOLDER FOR NEGATIVE PLATES Filed March 29, 1959 4 Sheets-sheet 1 Lf@ RTTUHNEY April 8, 1941. w, Q HUEBNER 2,237,704

vAccuUM HOLDER FOR NEGATIVE PLATES Filed March 29, 1939 4 Sheets-Sheet 2 EY Tmmw April@ @4L w. c. HUEBNER VACCUUM HOLDER FOR NEGATIVE PLATES 4 Sheets-Sheet Filed March 29, 1939 lfm/ENTIER' pri 8p B943., W. C. HUEBNER 2237,7@4

VAGCUUM HOLDER FOR NEGATIVE PLATES ATTDRNEY Patented Apr. 8, 1941 YUNITED STATES "PATENT OFFICE VACUUM noLnEa Fon NEGATIVE PLATES William C. Huebner, New York, N. Y. Application March 2s, 1939, serial No. 264,803

v 11 Claims.

This invention relates to improvments in vacuum holders, and more especially, vacuum holders for glass plate negatives and positives such as used in connection with photocomposing or photographic printing machines. For conciseness, the term negative and derivatives are used in the title of the invention and throughout the description and claims as comprehending both what are commonly known as negatives and positives, unless the context otherwise specifically requires.

As well known in the art of photographic printing machines and apparatus where the press plates are prepared from negatives, extreme accuracy is required in locating and positioning the images on the negatives in their respective holders in order to obtain the requisite register. The glass negatives used in this art, both dry and wet plates, vary in size from so-called standard sizes, due to inaccuracies in cutting the plates. Such variations, in commercial practice, generally do not exceed one-eighth of an inch. It also Irequently happens that such glass plates are not cut truly square. Because of the variations reierred to, it is obvious that some degree of adjustability must be allowed for in the holders for the negatives when clamping or securing the negatives thereto in order to allow for necessary register.

Because of the necessity of allowing for the ad- `justability of the negatives in the planes of the latter as indicated in the preceding paragraph, there necessarily results a gap between the edges of the negative plate and the vacuum sealing edge or surface of the holder disposed outside of the periphery of the negative. I'he presence of this air gap in vacuum type negative holders which are now practically universally used, has been a source of much dliiiculty due to the fact that, when the vacuum is applied, embossing or indentation of the press plate, particularly if the press plates are relatively thin,

Amay occur in those portions of the press plate plate under vacuum during exposure. In this connection, reference is had to the location ot the images on the negative plates themselves. It is, of course, the intention to locate the images on the negatives in the centers of the latter when the negatives are prepared in the camera. In many plants, however, due to imperfections in the large process cameras used, the images are projected onto the negative ofi center and cannot be accurately centered on the negatives. Such oil-set locations of the images may obviously be in any direction, and frequently may be oil centered as much as three-eighths of an inch. Obviously, where the images themselves are off-center on the negative and the negative plate itself may vary from standard size as much as one-eighth of an inch, the total necessary shift, in the plane of the negative plate, in order to bring the center of the image in the exact center of the holder to obtain register, may amount to over a half an inch. Under such conditions, it is impossible to provide any type of gap bridging means Aon the holder which will have such a permissible degree of adjustment and at the same time prevent embossing or indentation of the press plate under the vacuum pressure necessary for exposure purposes. Such a permissible degree of adjustment of the plate. locking clamps and/or gap bridging means would necessarily leave an unbridged gap at some places on the holder of such width as to allow the press plates to become injured, since the unbridged air gaps must, in actual practice, be kept down to approximately one-eighth of an inch or less.

One object of my invention, therefore, is to provide a vacuum glass plate negative holder for photo-composing machines within which holder the negative may be air sealed and accurately registered with all air gaps which are presented to the press plate, maintained Within such predetermined limits as will prevent embossing or indentation of the press plate, regardless of all tolerated commercial variations in size and contour of the plates themselves and with all necessary allowances for olf center location of images on the plate.

Other variations also occur in the use of glass plates for negatives in the photo-composing art, and that is with reference to the thickness of the plates used which may vary from the relatively very thin dry plates to plates oi one-quarter of an inch thickness. As understood by those skilled in the art, regardless of the thickness of the negative plates used in the vacuum holders,

their printing surfaces must always be brought to the same contact plane. Heretofore, this result has been accomplished, as illustrated in said Patent No. 1,978,493, by means of adjusting and set screws for raising and lowering a supporting frame on which the glass negative is positioned. Such construction requires not only extreme care on the part of the operator in adjusting and setting the several sets of screws at the usual four corners of the negative plate, but also involves considerable time as well as skill and experience in determining when all four corners of the plate have been brought to the .proper level or contact plane. Any slight elevation of the negative above its proper contact plane with reference to the holder may cause indentation of the press' plate when under vacuum pressure, or if any portion of the negative is left slightly below the contact plane, the press plate may be embossed.

.Another object of my invention, therefore, is to provide a vacuum glass plate negative holder for photo-composing machines such thatglass negative plates of dierent or variable thicknesses may be always brought to the correct contact plane throughout their entire area, rapidly, with a minimum of eiort and skill on the part of the operator and in a manner that may be considered substantially automatically.

In some plants using photo-composing apparatus, certain types of equipment are employed which necessitate registering the negatives in their holders with the negatives face down. 1n other plants, the equipment is such that registering is done with the negatives face up. As a result, some operators being accustomed to one method of registering, object to negativeeither with the negative "face up or face down" at the option of theoperator.

Still another object of my invention is to provide a vacuum negative plate holder so constructed that registration of the negative therein may optionally be made either in a prereglsterin'g apparatus or directly in the holder itself by means of temporarily attachable registering devices, the latter being also usable, when desired and under proper conditions, while the vacuum holder is on certain types of photo-composing machines and when there is to be a change of negatives of the same size.

Other objects of the invention will more clearly appear from the description and claims hereinafter following.

Zin the drawings forming a part of this specification, Figure 1 is a top plan view of the improved vacuum negative holder showing a negative in position thereon, the holder having also applied thereto attachments for effecting registration of the negatives` directly in the holder. Figure 2 is an edge elevation of the holder shown in Figure 1. Figure 3 is a vertical transverse sectional view, corresponding substantially to the section line 3 3. of Figure l. Figure d is a view similar to Figure 3, of the left hand portion of the latter, but upon an enlarged scale, in order to better show details of construction. Figure 5 is a top plan view of the combination register supporting frame, detached. Figure 6 is a bottom plan view of a portion of the frame shown in Figure 5. Figure 7 is a top plan view of the negative holder frame proper, shown detached from the register supporting frame of Figures 1 and 5. In Figure 7, the negative plate is shown omitted on one-half of the view and other portions of the negative holder frame proper being broken away., and partially in section to illustrate certain details. Figures 8 and 9 are vertical detail sectional views, upon enlarged scales, corresponding to the section lines @-3 and 9 9, respectively, of Figure l. And Figure 10 is a horizontal sectional view, upon an. enlarged scale, of one corner portion of the vacuum holder, showing more particularly certain ldetails of construction of the gap bridging bars and means for adjusting the same.

In carrying out the invention in the preferred form illustrated in the drawings, the complete vacuum holder comprises, broadly, three main members consisting of the registering supporting frarneA; the negative holding frame proper B; and a leveling and supporting frame C. 1n addition, register attachments D and E are employed, as hereinafter described.

Referring iirst to the register supporting fram A, best shown in detail in Figures 4, 5 and 6, the same is preferably of rectangular outline with a large central opening 2t for the passage of light therethrough. On what may be considered a bottom edge and one side edge, on the under side of the frame A, the latter is provided with two plates 2i2i, suitably rigidly secured to the frame A, each of said plates 2l being provided with two dowel pins 22-22, which dowel pin formations are accurately located and adapted to cooperate with correspondingly located dowel holes or dowel bushings on the photo-composing machine itself so that the frame A, as will be understood by those skilled in the art, will always occupy'a predetermined position and location `with respect to the travel lines of the photocomposing machine. As will be evident, the frame A may be attached to the photo-composing machine either by its bottom edge or side edge so as to permit of either head up, head down, head right or head left positioning of the effecting registration of the negative in such apparatus in a well known manner.

The frame A is further provided with One or more (two being shown) air exhaust ports 26-24, either or both of which, as shown in Figure 9, may be connected to a vacuum pump, as by means of a pipe or tube 25. Due to the fact that the negative holder frame B, as hereinafter described, is shiftable on the supporting frame A, the latter preferably has a ush plate insert 2t over each port 26, each plate 2% having an enlarged opening 2l so as to always insure register with the corresponding exhaust port 28 of the frame B, as best illustrated in Figure 9.

Also xedly secured to the frame A on each side thereof and at the center of each side on the top surface, is a register plate 29-29. Each said register plate 29 is provided with dowel register pins 30-30 for the purpose hereinafter described.

1 and 9, the same al Referring next to th hegative holding frame proper B, as best i121 rated in Figures 4, '7, 8 is of rectangular outline with a flat bottom wall 3| and a preferably integral upstanding wall or rib 32 extending continuously therearound, said wall or rib 32 being located near the outer periphery of the frame, as shown. The frame B is' further provided with a rectangular central opening for the passage of light therethrough, which opening is dei'lned by a rectangular frame 33 of angular cross section and rigidly secured to the main member 3l-32 of the frame B, as by the screws 34. At intervals around the frame B, preferably two on each side thereof, retainer clips 35-35 are secured to the frame B, which clips 35 have upper horizontally extending flanges 3B for retaining the combination gap and negative clamping bars 31, of which there are four, one on each side of the holder as shown. The bars 3l, as best shown in Figure 8, are horizontally recessed, as indicated at 3B to receive the corresponding flanges 36 and allow oi horizontal adjustment of the bars 31 as will be obvious. The recesses 3B, as clearly shown in Figure l0, are preferably arcuate and of greater area than the flanges 35 which project thereinto to allow not only of straight line movement ofthe bars 3'5 toward and from the center of the holder, but a certain degree of angular movement to compensate for any off the glass negative plate il@ when locking the latter in position, to thereby prevent chipping or breakage of the glass, as will be apparent. The gap locking bars 3l! are adjusted inwardly and outwardly by means of nger operated screws dl-ti, two such screws for each bar. Said adjusting screws di are journaled in the rib or wall 32 of the frame B, as shown in Figure 4, and have threaded engagement with nuts ft2, which nuts in turn, are swivelled or rotatively mounted in the bars 3l, as shown in Figure l0, to allow of angling of the bars 3l for the purpose previously described.

The third main member C oi the vacuum holder is likewise of rectangular outline with a central opening d3 for the passage of light to the negative, said trarne C being preferably of right angle cross section with a vertical leg M and a top outwardly directed leg or flange t5 extending over the member 33. extending continuously around the leg or vertical flange M of the frame the member 33 forming a part of the negative A vacuum or air seal is provided between the leveling and supporting frame C and the negative plate 40, as by the rubber strip 48 which is extended continuously around the light opening,

as will be understood. A further vacuum or air Referring to the gap and clamping bars 3l, the upper surfaces of the latter are made flush with the contact surface of the rib or wall 32 of the negative holder proper-B. To insure complete and rapid exhaustion of the air from the sealed off area of the press plate during an exposure, said bars 3l are provided with relatively shallow communicating longitudinal and cross grooves 50. In actual practice, the gap bars 3l, beveled at their ends, so as to keep the gap there at a minimum, will be of such width for a given size holder and negative plate, as to allow of a t total movement preferably not in excess oi three-sixteenths of an inch. Hence, it will be obvious that such irregularities in size of the negative plate not exceeding one-eighth of an inch commercially tolerated, can readily be accommodated, while at the same time insuring that there will be no air gap opposite the press plate of sucient width as to permit embossing or indentation.

Any oi center location of the image on the negative which must be allowed for when effecting registration, is provided for in the improved vacuum holder by adjusting the position of the negative holder proper B (which obviously carries with it the.leveling and supporting frame C) on the register supporting frame For this purpose, the negative holder proper B is detachably slidably mounted on the frame A by any suitable means such as the detachable clips 5l secured at intervals around the sides of the frame A, preferably two on a side. Each of said clips 5i has an upper horizontal flange 52 overhanging the base section 3l of the frame B and the necessary adjustment for register is effected through iinger adjusting screws 5B carried by the respective clips 5l. In actual practice, horizontal adjustment of the frame B on the frame A will preferably be allowed up to approximately nine-sixteenths of an inch, which permissible adjustment plus that provided by the combined gap and clamping bars 3l' will allow a total adjustment of the negative plate it of three quarters of an inch, thus enabling the vacuum holder to take care of any tolerated variations in both the size of the negative plate and oi centering of images thereon, while at the same time keeping any vacuum air gap presented to a press plate during exposure, within limits that will prevent injury to the press plate.

In using the vacuum holder, assuming the registering supporting frame, negative holder proper and leveling frame assembled as shown, the operator rst adjusts the gap clamping bars outwardly to clearance position. Next, he inserts his hands along say the bottom edge of the vacuum holder and by engaging his ngers around and beneath the leveling and .supportingv frame C, forces the same upwardly to a high position. This action may then be repeated on the opposite edge. The glass negative plate is then placed on the frame C and the contact surface of the negative plate will then be above the true contact plane of the vacuum holder. To adjust the negative, regardless of its thickness, to its proper contact plane ush with the upper surface of the rib or wall 32, the operator may then employ a glass plate of suiiicient area to extend over the rib or wall 32 and merely press down on the same, which adjustment is accommodated by the sliding friction t between the levelling and supporting frame C and the negative holding frame proper B. In this manner, the upper surface of the negative plate is brought exactly flush with the upper contact surface of the rib or wall 32 in just a few seconds of time, whereupon the superposed plate may be removed and set aside for subsequent use. The frictional engagement between the frame C and B is made such as to insure the frame C remaining in any such adjusted position. Preferably, the operator next brings the horizontal register marks ell of the negative to proper registered position byadjusting the bottom set of adjusting screws 6l, assuming that the image is centered or so near so, vertically of the negative plate, that this may be done within the limited movement permitted by the top and bottom gap clamping bars. This step of the registering operation may be accomplished either directly in the vacuum holder by the attachments, hereinafter described, or in a preregistering apparatus. The operator then next preferably loosely draws up the upper gap clamping bar by manipulating the upper set of adjusting screws M. Next, the operator adjusts the negative plate transversely so as to bring the vertical register marks @l of the negative to their proper position. Should, however, the image (such as indicated conventionally by the circle 62) be so off-centered in any direction that the necessary registration cannot be eiected merely by manipulating the gap clamping bars 3l, the additional necessary adjustment to bring the center of the image to the center with respect to the register supporting frame A, is accomplished by suitably manipulating the finger screws 53 in a manner which will be apparent, this operation also being eiected either directly on the vacuum holder by means of the attachments D and E or in a preregistering apparatus. 'During any adjustment of the negative holder proper B-C relative to the register supporting frame A, it is evident that there will be no strain Whatever on the negative and assuming the latter previously firmly locked in the frame B, there will be no danger of later displacement of the negative plate relative thereto.

Where it is desirable to effect registration in a separate preregistering apparatus, this obviously is accomplished by placing the complete assembly of the vacuum holder on such apparatus in which it will be registered by the dowel pins 22 cooperating with corresponding register formations on such apparatus. Dependent upon the particular type of such preregistering apparatus, registration may be effected either face up or face down.

There it is desired to eect registration directly on the vacuum holder, the registering attachments D and E are employed. Each of these preferably consists of a block S3 having dowel holes cooperable with the respective dowel pins CFI 30-30 carried by the register` supporting frame A, previously described. Secured to each block 63 is a preferably glass arm 64 so disposed as to extend over the negative and located at such height as to engage the upper surface of the negative. Each glass arm 64 is provided with an accurately inscribed register line, those for-the two attachments E' extending horizontally and being indicated at 65 and those for the other two attachments D extending vertically as indicated at 66. Bysuitably manipulating the negative clamping bars or the negative holder proper with reference to the supporting frame A or both, it is evident that the usual register cross marks 60 and 6I on the negative may be accurately brought in register with the register lines 65 and 66, whereupon the attachments E and D may be removed. In this connection, it will be understood that the register lines 65 and are definitely correlated with the register dowel pins 22 of the register supporting frame A.

In certain types of photocomposing machines, the negative holder may be swung to a horizontal clearance position and in such cases, Where there is to be no change in the size of negative but merely an interchange of negatives of similar size, considerable time and labor may be saved by employing the register attachments E and D While the vacuum holder is still in the photocomposing machine and thereby obviating the necessity of removing the vacuum holder and carrying it to a separate preregistering apparatus.

As will be apparent, other forms of registering attachments may be employed than the specific ones illustrated, provided the same may be readily applied in definite position with reference to the dowel register pins 22 of the supporting frame A. It will further be observed that masks, when necessary, may be applied either on the contact surface of the negative where sharp delineation is required, or on the under side, where the degree of sharpness is not so necessary.

From the preceding description, it will be seen that the improved vacuum holder provides all necessary adjustments and means for any variations encountered commercially With respect to deviations from standard sizes, oi centering of the image, variations in contour of the glass plate, diierences in thickness of the glass plate, registration directly in the vacuum holder or in a separate preregistering apparatus, and registration either face up or face down, thus making the vacuum holder what may be fairly termed a universal holder to meet all conditions.

There has been shown and described what is now considered the preferred manner of carrying out the invention, but the same is merely illustrative, since it is apparent that many changes may be made in details of construction without departing from the spirit of the invention. All such changes and modifications are contemplated that come Within the scope of the claims appended hereto.

What is claimed is:

1. In a vacuum holder for negative plates, the combination with a. supporting member having a central opening for the passage of light and provided with registering formations cooperable with complemental registering formations of a photocomposing machine and also provided with supplemental registering formations and correlated to the first named registering formations, said supplemental registering formations being adapted to cooperate with complemental registering formations of attachable and detachable registering devices; of a negative plate-holding frame having a central opening for the passage of light, said frame being mounted on the supporting member and provided with an upstanding wall extending uninterruptedly around the frame; air sealing means on said wall adapted to engage a press plate duringan exposure; means for adjusting said frame in a plane paralleling the plane of the supporting member and to look said frame in adjusted position; a plate leveling frame disposed within the light opening of the negative holding frame and having also a central opening for the passage of light, said leveling frame being adjustable relative to the negative holding frame in a direction perpendicular to the plane of adjustment of the'holding frame on the supporting member to thereby accommodate negative plates of different thicknesses with their contact surfaces flush with said air sealing means of the negative holding frame; combined air ,sealing and friction holding means between the negative holding frame and leveling frame; air sealing means on the plate supporting surface of the leveling frame; air gap-bridging bars mounted on the negative holding frame between said wall of the latter and the leveling frame, said bars being adapted to engage the edges of a negative plate supported on said leveling frame and to lock the negative plate in position; and means for adjusting the position of said bars, the vacuum holder being provided with an exhaust port communicating with the sealed ofi area and adapted to be connected with a source of suction.

2. In al vacuum holder for negative plates, the combination with a supporting member having a central opening for the passage of light and provided withA registering formations cooperable with complemental registering forma.. tions or a photocomposing machine; oi a negative plate holding frame having a central opening for the passage of light, said frame being mounted on the supporting member and provided with an upstanding wall extending continuously around the frame; air sealing `means on said wall adapted to engage a press plate during an exposure; means for adjusting said frame in a plane paralleling the plane of the supporting member on the supporting member and. to lock said frame in adjusted position; a plate leveling frame disposed within the light opening of the negative holding frame and having also a central opening for the passage of light, said leveling frame being adjustable relative to the negative holding frame in a direction perpendicular to the plane of adjustment of the negative holding frame on the supporting member to thereby accommodate negative plates ci different thicknesses; air sealing means between the leveling frame and negative plate holding frame extending around the light opening of the latter; air sealing means on the plate supporting surface of the leveling frame; adjustable means on the negative holding frame for locking a negative plate in position when supported on t e leveling frame, said negative holding frame being provided with an exhaust port communicating with the sealed off area of the latter and adapted to be connected with a source of suction. f

3. In a vacuum holder for negative plates, the combination with a supporting member having a central opening for the passage of light and provided with registering formations cooperable with complemental registering formations of a photocomposing machine; of a. negative plate holding frame having a central Iopening for the passage of light, 'said frame being mounted on the supporting member and provided with an upstanding wall extending continuously around the frame; air sealing means on said wall adapted to engage a press plate during an exposure; means for adjusting said frame on the supporting member in a. plane paralleling the plane of the supporting member and locking said frame in adjusted position; a plate leveling frame disposed within the light opening of the negative holding frame and having also a central opening for the passage of light, said leveling frame being adjustable relative to the negative holding frame in a direction perpendicular to the plane of adjustment of the negative holding frame on the supporting member to thereby accommodate negative plates of different thicknesses; air sealing means between the leveling frame and negative plate holding frame extending around the light opening of the latter; air sealing means cn the plate supporting surface of the leveling frame; air gap-bridging bars mounted on the negative holding frame and extending around the inner side of the upstanding wall thereof; means for adjusting the position of said bars inwardly and outwardly with reference to said wall and edges of a negative plate supported on the leveling frame; and means, communicating with the air sealed area of the negative holding frame, adapted to be placed in communication with a source of suction.

4; In a vacuum holder for negative plates, the combination with a supporting member having a central opening for the passage or light and provided with registering formations cooperable with complemental registering formations of a photooomposing machine; of a negative plate holding frame having a central opening for the passage of light, said fra-me being mounted on the supporting member and provided with an upstancling wall extending continuously around the frame; air sealing means on said wall adapted to engage a press plate during an exposure; means for adjusting said frame on the supporting member in a plane 4paralleling the plane of the supporting member and locking said frame in adjusted position; a plate leveling frame disposed with the light opening of the negative holding frame and having also a central opening for the passage of light, said leveling frame being adjustable relative to the negative holding frame in a direction perpendicular Ito the plane of adjustment of the negative holding frame on the supporting member to thereby accommodate negative plates of different thicknesses; air sealing means between the leveling frame and negative plate holding frame extending around the light opening of the latter, air sealing means on the plate supporting surface of the leveling frame; adjustable means on the negative holding frame for locking a negative plate in position when supported on the leveling frame, said negative holding frame being provided with .an exhaust port lcommunicating with the sealed off area of the latter and adapted to be connected with a source of suction, said supporting member being provided also with supplemental registering formations correlated to the first named registering formations thereof, said supplemental registering formations being `adapted to cooperate with complemental registering formations of detachable registering devices.

5. In a vacuum holder for negative plates, the combination with a supporting member having a central opening for the passage of light and provided with registering formations cooperable with complemental registering formations of a photocomposing machine and also with supplemental registering formations correlated to the first named registering formations, said supplemental registering formations being adapted to cooperate with complemental registering formations of detachable register devices; of a negative plate holding frame having a central opening for the passage of light, said frame being mounted on the supporting member and provided with an upstanding wall extending continuously therearound; air sealing means on said wall adapted to engage a press plate; means for adjusting said frame on the supporting member in a direction paralleling a negative plate mounted thereon and for locking the frame in adjusted position; a plate leveling frame disposed Within the light opening of the negative holding frame and having also a central opening for the passage of light, said leveling frame being adjustable in a direction at right angles to the plane of a negative plate supported thereon; friction retaining means interpcsed between the negative holding frame and leveling frame automatically eective to hold the leveling frame in any position relative to the negative holding frame to which it may be adjusted; means to provide an air seal between the leveling frame and a'negative plate when supported thereon; and means on the negative holding frame for locking a negative plate therein while supported on the leveling frame.

6. In a vacuum holder for negative plates, the combination with a supporting member having a central opening for the passage of light and provided with registering formations cooperable with complemental registering formations of a photocomposing machine; of a negative plate holding frame having a central opening for the passage of light, said frame being mounted on the supporting member and provided with an upstanding wall extending continuously around the frame; air sealing means on said wall adapted to engage a press plate during an exposure; means for adjusting said frame on the supporting member in a plane paralleling the plane of the supporting member and locking said frame in adjusted position; a plate leveling frame disposed within the light opening of the negative holding frame and having also a central opening for the passage of light, said leveling frame being adjustable relative to the negative holding frame in a direction perpendicular to the plane of adjustment of the negative holding frame on the supporting member to thereby accommodate negative plates of diierent thicknesses; air sealing means between the leveling frame and negative plate holding frame extending around the light opening of the latter; air sealing means on the plate supporting surface of the leveling frame; air gap-bridging bars mounted on the negative holding frame and extending around the inner side of the upstanding Wall thereof; means for adjusting the -position of said bars inwardly and outwardly with reference to said Wall and edges of a negative plate supported on the leveling frame; and means, communicating with the air sealed area of the negative holding frame adapted to be placed in communication with a source of suction, said supporting member being provided with supplemental registering formations correlated to the first named registering formations, said supplemental registering formations being adapted to cooperate with complemental registering formations of detachable register devices, the first named registering formations of the supporting member and the supplemental registering formations thereof being on opposite faces thereof.

7. In a vacuum holder for negative plates, the combination with a supporting member having a central opening for the passage of light and provided with registering formatlons cooperable with complemental registering formations of a photocomposing machine; of a negative plate holding frame having a central opening for the passage of light, said frame being mounted on the supporting member; a plate supporting and leveling frame disposed within the light opening of the negative holding frame and having also a central opening for the passage of light; means on the negative plate holding frame for locking a negative plate therein when supported on the leveling frame; means for adjusting the negative plate holding frame together with the leveling frame relative to the supporting member in a plane parallel to .that of a negative plate locked in the negative plate holding frame; means providing an vair seal between the leveling frame and a negative plate supported thereon and between the negative plate holding frame and a press plate; and means providing an air seal between the leveling frame and the negative plate holding frame, said means extending continuously around the ou-ter side of the leveling frame and engageable with the inner edge of the light opening of the negative plate holding frame.

8. In a vacuum holderfor negative plates, a negative plate holding frame having a central opening for the passage of light, said frame having an upstanding continuous wall extending around the light opening and disposed outwardly thereof; means on said wall to provide an air seal with a press plate during an exposure; a combined negative plate supporting and leveling frame disposed within the light opening of the negative plate holding frame and provided also with a central light opening; means on the plate supporting surface of said leveling frame to provide an air seal therebetween and a negative plate resting thereon; combined air-sealing and friction holding means extending around the leveling frame between the latter and surface of the negative plate holding frame which defines the light opening of the latter, said means being adapted to allow of adjustment of the leveling frame relative to the negative plate holding frame in a direction perpendicular to the plane of a negative plate supported on the leveling frame and retain the latter automatically in any such adjusted position to thereby accommodate negative plates of diierent thicknesses with their contact surfaces iiush with the air sealing means of the negative plate holding frame which contact the press plate; and means on the negative plate holding frame, located inwardly of the wall of the latter and outwardly of the leveling frame, to engage and lock a negative plate supported on the leveling frame.

9. In a vacuum holder for negative plates, a negative plate holding frame having a central opening for the passage of light, said frame having an upstanding continuous wall extending around the light opening and disposed outwardly thereof; means on said wall to provide an air seal with a press plate during an exposure; a combined negative plate supporting and leveling frame disposed within the light opening of the negative plate holding frame and provided also with a central light opening; means on the plate supporting surface of said leveling frame to provide an air seal therebetween and a negative plate resting thereon; combined air sealing and friction holding means extending around the leveling frame between the latter and surlace of the negative plate holding frame which deilnes the light opening of the latter, said means being adapted to allow of adjustment of the leveling frame relative to the negative plate holding frame in a direction perpendicular to the plane of a negative plate supported on the leveling frame and retain the latter automatically in any such adjusted position to thereby accommodate negative plates of different thicknesses with their contact surfaces flush with the air sealing means of the negative plate holding frame which contact the press plate; air gap-bridging members disposed entirely around the negative plate holding frame inside of -the wall of the latter and outwardly of the edges of a negative plate supported on the leveling frame, the upper surfaces of said members being disposed in the contact plane of a negative plate; and means, operable from the exterior of the negative plate holding frame for adjusting said air gap-bridging members inwardly and outwardly to engaging locking position with the edges of a negative plate, said negative plate holding frame being provided with an exhaust port communicating with the air sealed area of the plate holding frame and adapted to be 'placed in communicationwith a source of suction.

10. In a vacuum holder for negative plates, the combination with a rectangular supporting member having a central opening for the passage of light, said member on two of vits sides on the bottom face thereof being provided with registering formations cooperable with complemental registering formations of a photocomposlng machine, said supporting member being provided on thev upper face thereof on a plurality of sides with 'supplemental registering formations and correlated to the rst named registering formations and adapted for cooperation with complemental registerlng formations of attachable registering devices;v of a rectangular negative plate holding frame mounted on the upper surface of the supporting member and provided also with a rectangular central opening for the passage of light, said frame having an upstanding wall extending continuously around the light opening thereof and disposed outwardly of the opening; means to provide an air seal between said wall and a press plate; means for adiusting the negative plate holding frame universally in a plane parallel to the supporting surface of the supporting member and to lock the plate holding frame in adjusted position; a rectangular nega-- tive plate supporting and leveling frame disposed within the light opening of the negative plate holding frame and having also a central rectangular opening for the passage of light; a compressible air sealing gasket extending continuously around the leveling frame and engageable with the peripheral surface of the negative plate holding frame which defines the light opening of the latter, said gasket being slidable with reference to the negative plate holding frame and frictionally cooperable with the latter to automatically retain the leveling frame in any position to which the latter may-be adjusted with respecty to the negative plate holding frame; means providing an air seal between the leveling frarne and a negative plate supported thereon; air gap-bridging bars on the negative plate holding frame disposed inside of the wall of the latter, there being one such bar for each side of the negative plate holding frame and substantially co-extensive with its corresponding side, the upper surfaces of said bars being disposed flush with the contact surface of a negative; means' for adjusting said bars inwardly and outwardly to engage the edges of and lock a negative plate while supported on the leveling frame, said negative plate holding frame and supporting member being provided with registering exhaust ports communicating with the air sealed area. of the combined negative plate holding frame and leveling frame, which ports are adapted to be placed in communication with a source of suction.

11. In a vacuum holder for negative plates, the combination with a supporting member having a central opening for the passage of light therethrough and provided with registering formations cooperable with complemental registering formations of a photocomposlng machine, said supporting member having mounted thereon means for adjusting a negative plate in the plane of the latter and locking the negative plate in adjusted position over the opening of the supporting member; of a plate leveling and supporting frame having a central opening for the passage of light therethrough, said leveling frame being disposed Within said opening of the supporting member and adjustable in said last named opening relatively to the supporting member in directions perpendicular to the plane of the negative plate; air sealing and friction means around the leveling frame to automatically frictionally hold the leveling frame in adjusted position; means, extending around the edges of the negative plate and carried by the supporting member, to provide an air seal with a press plate during an exposure; and means to provide an air seal between the leveling frame and a negative plate supported thereon, said supporting member being provided with an exhaust port vin communication with the space sealed off by said .several aforementioned air sealing means.

WILLIAM C. HUEBNER.

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