US3771870A

US3771870A - Register pin for vacuum frame

Info

Publication number: US3771870A
Application number: US00322569A
Authority: US
Inventors: P Taylor
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-01-10
Filing date: 1973-01-10
Publication date: 1973-11-13
Anticipated expiration: 1990-11-13

Abstract

A register pin for use in a vacuum frame. The register pin comprises a vertically extending pin and a horizontally extending support therefor. The support comprises a plurality of radially extending spaced flat fingers which are secured to the pin. The fingers are adapted to maintain the pin in its vertical orientation during use.

Description

I United States Patent [191 Taylor Nov. 13, 1973 [54] REGISTER PIN FOR VACUUM FRAME 3,463,586 8/1969 Carlson et al 355/92 X 3,572,228 3/1971 Ternes 355/73 X [76] lnvemor- 2:25 5 2 g g g g r g 3,634,009 1/1972 Van Dusen 355/93 Primary Examiner-Richard M. Sheer [22] Filed; Jan. 10, 1973 Attorney-Barry A. Stein et al.

[211 App]. No.1 322,569

[57] ABSTRACT [52] U S Cl 355/91 33/184 5 355/92 A register pin for use in a vacuum frame. The register 355/94 355/76 pin comprises a vertically extending pin and a horizon- [51] Int Cl G03b 27/20 tally extending support therefor. The support com- [58] Fieid 92 93 94 prises a plurality of radially extending spaced flat fin- '5 gers which are secured to the pin. The fingers are adapted to maintain the pin in its vertical orientation [56] References Cited durmg UNITED STATES PATENTS 8 Claims, 11 Drawing Figures 2,825,976 3/1958 Radencic 33/1845 2,871,572 2/1959 Gutzmermu 33/1845 PMENIEU NOV 13 I975 SHEET 10F 2 REGISTER PIN FOR VACUUM FRAME This invention relates to a register pin for a vacuum frame, and more particularly, to a novel supporting plate forming part of the pin.

Vacuum frames have long been used in the photolithography and photography arts. These vacuum frames are used for the registration of various overlays in order to make a composite photoplate or lithographic plate. Since on many occasions two or more overlays are used in order to make the final exposed plate or film, it is necessary to insure that there is proper registration of each overlay. In order to accomplish this, register pins are placed in the vacuum frame, and these register pins are used for aligning overlays on the unexposed or partially exposed film or plate.

All of the register pins presently in use have basically the same structure. These pins comprise a substantially rectangular plate with a vertically extending pin spotwelded adjacent one corner of the plate. The pin is extremely smooth in order to permit easy insertion in the register holes of the film and overlays and in order to prevent scratching of the glass top of the vacuum frame. The pins are available in various heights, which normally range from 0.040 inch to 0.160 inch, or larger or smaller as the need might be. They are also available in oblong shapes for special uses. The diameters are generally 0.125 inch or 0.250 inch, but this too can vary.

The rectangular bases for the pins are formed from a somewhat flexible steel. The thickness of the bases or supports is generally 0.010 inch. The lengths and widths of the bases can vary, with a base being inch wide and 1% inches long being a common size.

The foregoing description applies to all of the register pins currently in use which are known to the applicant. One of the bases for the invention of this application is the realization that there is an inherent problem in all of the register pins currently in use. Thus, these pins are used by placing two or more pins on the flexible blanket of a vacuum frame and then placing the unexposed film and overlays on the vacuum frame, with proper registration being obtained through the use of the pins in holes in the filmand overlays. When a vacuum is applied to the vacuum table, the flexible blanket holding the pins, film and overlays will distort, thereby raising the blanket to bring the film and overlay into contact with the glass plate of the vacuum frame. Applicant has found that when this distortion occurs, the rectangular base of the register pins currently in use has a tendency to bend or twist on continuous vacuum. This in turn causes a small distortion in the vertical position of the pin which is welded to the base. This results in a slight misalignment between the film and the overlay. In certain types of photographic and photolithographic work, this misalignment can be critical, and can render the fully exposed film unuseable.

Having recognized the problem utilizing the register pins of the prior art, the register pin of this invention has been designed to overcome this problem. Thus, on continuous vacuum, the pin will move only vertically but will not twist or tilt. Accordingly, proper registration is always maintained.

It is therefore an object of this invention to provide a novel register pin.

It is another object of this invention to provide a vacuum frame that incorporates a novel register pin.

These and other objects of this invention are accomplished by providing a register pin for a vacuum frame comprising a pin and a support therefor, said pin extending perpendicularly to said support and being secured thereto, said support comprising a plurality of radially extending, spaced fingers, said fingers extending in a plane that is perpendicular to said pin.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a perspective view of a vacuum frame utilizing the register pin of this invention;

FIG. 2 is an exploded perspective view of an unexposed piece of film and a first overlay used in connection with the film;

FIG. 3 is an exploded perspective view of a partially exposed piece of film and a second overlay used with the film, along with three register pins of this invention;

FIG. 4 is a perspective view' of the fully exposed film, which film is formed by the utilization of the register pin of this invention;

FIG. 5 is an enlarged sectional view taken along the line 5-5 of FIG. 1;

FIG. 6 is an exploded perspective view of a first embodiment of the register pin of this invention;

FIG. 7 is a perspective view of the register pin of FIG. 6 in its completed form;

FIG. 8 is a perspective view of a second embodiment of the register pin of this invention;

FIG. 9 is an exploded sectional view taken along the line 99 of FIG. 8;

FIG. 10 is a perspective view, partially broken away, of a third embodiment of the register pin of this invention; and

FIG. 11 is an enlarged sectional view taken along the line 1111 of FIG. 10.

Referring now in greater detail to the various figures of the drawings wherein like reference characters refer to like parts, a first embodiment of the register pin embodying the present invention is generally shown at 20 in FIG. 7. A plurality of the register pins 20 are used with a vacuum frame which is generally shown at 22 in FIG. 1.

Vacuum frame 22 basically comprises a base 24 having a cover or lid 26. The lid includes a frame and a glass sheet 28 secured within the frame. The cover 26 is hingedly secured to the base 24, as by hinges 30. A handle 32 is secured on one edge of cover 26, and a locking lever 34 is pivotally secured on base 24. The lever 34 is engaged in handle 32 to lock the cover 26 in place during use of the vacuum frame. The vacuum frame further includes a rubber, flexible blanket 36.

The structure described as to the vacuum frame is the basic structure of the vacuum frame generally known to the art. The specific structure of the vacuum frame forms no part of the invention, and any and all of the vacuum frames known to the art can be used in connection with the register pins of this invention. The vacuum frame shown is shown solely for the purpose of illustration of the use of the register pins of this invention.

An example of the type of work generally done in a vacuum frame through the use of register pins is shown in FIGS. 2 to 4. Referring more particularly to FIG. 2, there is shown therein a unexposed sheet of film 38 and a first overlay sheet 40. The overlay sheet has a photo 42, such as a half tone or tint, thereon. The rest of the overlay sheet is black so that it will protect the unexposed portions of the film 38 when the vacuum frame is used.

In use, three register pins pass through three aligned holes in the unexposed film 38. The overlay sheet 40 is then placed on film 38 and is aligned therewith by passing the pins 20 through holes 44 in the overlay sheet. Thereafter, the composite of the film 38, the overlay sheet 40 and the pins 20 is placed in the vacuum frame 22, the lid 26 is closed and the latch 34 is rotated to lock the lid in place.

Referring to FIG. 5, there is shown therein the use of the pin 20 when a vacuum is applied to the frame 22. Thus, the unexposed film 38 and the overlay 40 are shown as being supported by the flexible blanket 36. The blanket 36 has a plurality of holes 44 passing therethrough. A vacuum is drawn beneath the blanket 36, thereby evacuating the air between the blanket 36 and the glass 28. The air evacuation is indicated by arrows 46 in FIG. 5.

When the air is evacuated, the blanket 36 is drawn against the glass 28, thereby holding the film 38 and the overlay 40 securely against the glass. The register pins 20 maintain the proper alignment between the film 38 and the overlay 40 during this process. After the vacuum has been drawn, the portion of the film 38 underlying the picture 42 on overlay 40 is exposed, thereby placing the picture 42 on the film 38.

After this has been done, the vacuum frame 22 is opened and the composite of the film 38 and overlay 40 is removed. Thereafter, as seen in FIG. 3, a new composite is formed from pins 20, partially exposed film 38 and a new overlay 48. Overlay 48 includes three aligned holes 50, which have the same spacing as holes 52 in film 38 and as holes 44 in overlay 40. Overlay 48 also includes text in the form of linework 54. The balance of overlay 48 is blacked out, so that when the composite is put in the vacuum frame 22, only that portion of the film 38 underlying the text 54 will be exposed.

As seen in FIG. 3, when the composite of overlay 48 and film 38 is formed, the image of the photo 42 has already been formed in the film 38. Thereafter, the composite is placed in the vacuum frame, and a new exposure is made. At this time, linework 54 will be formed on film 38. Accordingly, as seen in FIG. 4, the fully exposed film 38 includes the photo 42, which appears as a half tone or tint, and the linework 54. Thereafter, the film 34 can be used in photography processing or photolithographic processing.

The process described above is one of the processes used in all vacuum frames. This process can be carried out with the register pin of the prior art. However, as explained above, utilizing the broad plates as supports for the register pins in the prior art, when the overlay is placed on the unexposed. film, and the vacuum is formed, the bases of the register pins have a tendency to twist or distort, thereby moving the pins. This in turn results in the lack of proper registration between the film and the overlay. In certain types of work, registration is highly critical, and improper registration when in the vacuum frame can result in the production of a useless film. Accordingly, the process must be repeated.

Utilizing the register pins of this invention, all of the distortion and twisting problems are eliminated. Thus, the pins of the register pin will flex only vertically when the vacuum is applied, and there is no force acting to distort the pins.

Referring now to FIGS. 6 and 7, it is seen that the first embodiment 20 of the register pin comprises a pin 56 and a base 58. Pin 56 is identical to the pins of the prior art, in that it is basically cylindrical and formed from a highly polished, smooth metal, such as stainless steel. The base is flat, and, in the embodiment shown, is circular. Three equally spaced slots 60 are cut in the base, thereby leaving three radially extending fingers 62, which project from a circular hub 64. The pin 56 is spot-welded, or otherwise secured, to hub 64.

Register pin 20 is used in the same manner as the register pins of the prior art. This method of use is best shown in FIGS. 1, 2, 3 and 5. The advantage of the pin 20 is that when the vacuum is applied, the fingers 62 freely flex vertically, without distorting the pin 56. Thus, the movement of the pin 56 under vacuum is purely vertical, and there is no angular movement away from the vertical. Accordingly, the fingers 62 serve their function of maintaining the vertical position of the pin 56 during alignment, and insuring that the pin will move only vertically under vacuum pressure.

A second embodiment of the register pin of this invention is generally shown at 66 in FIGS. 8 and 9. Device 66 basically comprises a pin 68 and a base 70 Base 70 is basically square, and includes three equally spaced slots 72, which form fingers 74. A circular slot is formed in the middle of base 70 whereby the fingers 74 terminate in arcuate edges adjacent the central slot. Pin 68 includes an annular groove 76 adjacent its base.

In this embodiment, the pin 68 is secured to the base 70 by snapping the fingers 74 into the groove 76. In use, embodiment 66 functions in an identical manner to that of embodiment 20.

A third embodiment of the register pin of this invention is generally shown at 80 in FIGS. 10 and 11. Regis ter pin 80 comprises a pin 82 and a base 84. Base 84 comprises three equally spaced fingers 86 that emanate from a central circular hub 88. Pin 82 is spot-welded or otherwise secured to hub 88.

Register pin 80 is used in an identical manner to register pin 20. In use, the pin 82 will move only vertically when the base 84 is subjected to the stress of the vacuum.

It is thus seen that in all of the embodiments of this invention, the pin is centrally located on the base. Contrasted to this, in the prior art, the pin is positioned at one corner of a relatively large rectangular base. There is minimum contact between the pin and the fingers in the register pin ofthis invention, and accordingly there is no distortion of the pin during vacuum stress.

As seen in FIGS. 6 to 11, all of the fingers of the bases of the register pins taper toward the center of the base, as they approach the upstanding pin. This gives greater freedom of flexing for the pin, which is located at the locus of the fingers. Thus, the smaller the amount of metal adjacent the upstanding pin, the greater the amount of flexing thatis possible. i

The register pin of this invention can be made in any of the sizes known to the art. The bases can have a thickness ranging from 5 to 20 mils, with a preferred thickness being 10 mils. The pins of the register pins generally have a diameter of 0.125 inch or 0.250 inch,

but this can vary to suit the needs of the user. The pins can also be oblong in shape, as is common in the prior art. In the prior art, the pins generally range in height from 0.040 inch to 0.160 inch. The pins of this invention can also vary through the same range of heights, or greater, if necessary. Generally, the bases and pins are formed from stainless steel, but other materials can be used.

Without further elaboration, the foregoing will so fully illustrate my invention, that others may, by applying current or future knowledge, readily adapt the same for use under various conditions of service.

What is claimed as the invention is:

l. A register pin for a vacuum frame comprising a pin and a support therefor, said pin extending perpendicularly to said support and being secured thereto, said support comprising a plurality of radially extending spaced fingers, said fingers extending in a plane that is perpendicular to said pin.

2. The register pin of claim 1 wherein said pin is located at the locus of said fingers.

3. The register pin of claim 1 wherein said pin is centrally located on said base.

4. The register pin of claim 1 wherein said fingers are contiguous with a hub, said pin being secured to said hub.

5. The register pin of claim 1 wherein said fingers terminate in an opening in said base, said pin having an annular groove formed therein, with said. fingers being received in said groove, thereby securing said pin to said base.

6. The register pin of claim 5 wherein said fingers have an arcuate edge adjacent said opening and said groove having a circular cross section, whereby said pin is free to rotate relative to said fingers.

7. The register pin of claim 1 wherein said fingers are formed in a flat plate.

8. In combination with a vacuum frame comprising a housing and a flexible blanket within said housing, a plurality of register pins adapted to be placed on said blanket and to hold a composite comprising at least one base sheet and at least one overlay in proper registry, each of said register pins comprising a pin and a support therefor, said pin extending perpendicularly to said support and being secured thereto, said support comprising a plurality of radially extending, spaced fingers, said fingers extending in a plane that is perpendicular to said pin.

Claims

1. A register pin for a vacuum frame comprising a pin and a support therefor, said pin extending perpendicularly to said support and being secured thereto, said support comprising a plurality of radially extending spaced fingers, said fingers extending in a plane that is perpendicular to said pin.

5. The register pin of claim 1 wherein saiD fingers terminate in an opening in said base, said pin having an annular groove formed therein, with said fingers being received in said groove, thereby securing said pin to said base.

7. The register pin of claim 1 wherein said fingers are formed in a flat plate.