US3679308A

US3679308A - Equilibrated copyboard

Info

Publication number: US3679308A
Application number: US68118A
Authority: US
Inventors: Gerhard A Nothmann
Original assignee: Robertson Photo-Mechanix Inc
Current assignee: AFP ACQUISITION Corp; Robertson Photo-Mechanix Inc
Priority date: 1970-08-31
Filing date: 1970-08-31
Publication date: 1972-07-25
Anticipated expiration: 1989-07-25

Abstract

A pivoted holder for flat material such as a copyboard or similar device for use in a light exposure system is mounted on a support for tiltable movement selectively between an expose or process position and a loading position and includes elastic means interconnecting the copyboard and the support in a manner to urge the holder toward an equilibrium position approximately mid-way between the two extreme positions, thereby implementing actuation of the copyboard by an operator between selected positions.

Description

[451 July 25,1972

ABSTRACT FOREIGN PATENTS OR APPLICATIONS 8/1960 GreatBritain........................

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United States Patent Nothmann [54] EQUILIBRATED COPYBOARD [72] Inventor: Gerhard A. Nothmann, Wilmette, lll.

Robertson Photo-Mechanix, Plaines,lll.

Inc., Des

[73] AsSgnee: Primary Examiner-Samuel S. Matthews Assistant Examiner-Russell B. Adams, Jr. [22] Filed: Aug. 31, 1970 Attorney-Hill, Sherman, Meroni, Gross & Simpson [21] Appl. No.: 68,118

A pivoted holder for flat material such as a copyboard or similar device for use in a light exposure system is mounted on 40/341 a support for tiltable movement selectively between an expose 40 I3 1 267 50 or process position and a loading position and includes elastic [51] Int. [58] Field ol'Search....

means interconnecting the copyboard and the support in a manner to urge the holder toward an equilibrium position ap- Relerences Cited proximately mid-way between the two extreme positions, thereby implementing actuation of the copyboard by an .267/150 X Shepard...............................355/75 X h g m .m o w a -m m 0 D. 3 d m m c m e l l m w a M u m r .5 "v e I w a h e b m m r e D- O SHEET 1 [IF 2 PATENTEDJUL 25 I972 EQUILIBRATED COPYBOARD BACKGROUND OF THE INVENTION 1. Field of the Invention This invention generally relates to the graphic arts and more specifically to a copyboard, vacuum frame or similar device in which flat material is retained for processing or exposure in a process camera or other light exposure system, and more particularly refers to a pivoted copyboard having means for urging the same toward an equilibrium position disposed approximately mid-way between an operating position and a loadingunloading position.

2. Description of the Prior Art Light exposure systems, for use in graphic arts, printing, photofabrication and similar applications, generally include a copyboard or similar device for holding original, flat material to be copied, processed and/or exposed. For convenience in loading and unloading, and in order to provide an optimum physical arrangement of the machine, the copyboards are usually journalled in the machine frame for pivotal or tiltable movement between a loading-unloading position and a working or exposing position. When the copyboard is in the loading-unloading position, an operator inserts or otherwise constrains the material to be copied or exposed in or on the copyboard and then moves the copyboard to the working position, wherein the material is arranged for optimum photographic exposure or other working conditions. Most commonly, the loading-unloading position is approximately a horizontal position, whereas the working or exposing position may be a vertical position or possibly a horizontal position wherein the copyboard is rotated approximately one-half revolution from the loading-unloading position, as is the case in a plate exposure apparatus.

Since the copyboard normally contains glass or similar fragile material, and since its location in the working or exposing position must be precise to obtain optimum results, considerable care must be exercised by the operator in pivoting or otherwise moving the copyboard from the loading-unloading position to the working position. In large process cameras and other graphic arts devices, the copyboards may be relatively large and heavy, thereby requiring considerable effort on the part of the operator to move the copyboard in a controlled manner and, in particular, to guide the copyboard to its working position without damage thereto or to the material contained therein.

Heretofore, provisions have been made for reducing the manual effort and skill required in the operation of copyboards. Completely automatic copyboards, normally operated by electrical motors or electrohydraulic control systems, have been used. Semi-automatic means utilizing dash-pots or similar shock absorbers, have been used to facilitate the copyboard movement and, in particular, to insure that the copyboard arrives at its working position with a sufficiently low terminal speed to avoid damage or excessive overtravel.

SUMMARY OF THE INVENTION In accordance with the present invention, a copyboard mounted on a support for tiltable movement selectively between a loading position and an expose or process position includes elastic means interconnecting the copyboard and the support so that it is urged toward an equilibrium position selected to be approximately mid-way between the extreme operating or working positions.

Since the copyboard is constrained to rotate about a fixed pivot axis, the elastic means, which may be an elastic member, such as a mechanical spring, causes the copyboard to oscillate about the equilibrium position in a manner similar to an elastic pendulum. The frequency of those oscillations, and therefore the speed of movement, is dependent upon the rotational inertia of the copyboard and upon the parameters of the elastic member or other elastic means. The amplitude or excursion of the oscillations depends on the initial position of the copyboard relative to its equilibrium position. At each of the two copyboard,

extreme positions, the rotational speed of the copyboard is zero and reaches a maximum value at the mid-point of the oscillation, alternately in either direction. If allowed to oscillate freely, the excursion of the oscillation will remain nearly constant and decrease from cycle to cycle, only by an amount determined by friction and air resistance. Since the copyboard comes to rest at each of the extreme positions, it is possible to hold the copyboard at rest for a finite period of time, at either of those positions, and then release the copyboard for continuation of the oscillatory motion or to permit movement to the alternate position.

Spring loaded detents, which may be actuated by the operator at an appropriate time, constrain the copyboard selectively at the loading position or at the expose or process position. Each detent holds the copyboard in the corresponding position and, upon release by the operator, releases the copyboard for movement to the alternate position.

If desired, the location of the loading position and the expose or process position, and thus of the appropriate detents, relative to the equilibrium position, may be selected so that the copyboard will move from the loading position, after appropriate release of the detent, to the expose position without requiring manual assistance by the operator. Thus, the copyboard will arrive at the expose position at a very low speed only sufficient to insure action of the detent, thereby to allow the detent to hold the copyboard in the expose position. Conversely, when the copyboard is released from the expose position, by operation of the appropriate detent, the copyboard moves from that position to and past the equilibrium position and continues toward the loading position. However, a small additional effort, by the operator, is required to complete the travel of the copyboard to the loading position and to insure actuation of the detent for holding.

With the copyboard of the present invention, the effort required by the operator is limited to the force necessary for actuating the detents as well as the small effort necessary to bring the copyboard, during the final portion of its motion, into the loading position. Those forces, as well as the care and attentionrequired, are significantly smaller than those which would normally be required to move the copyboard through its total excursion in the absence of the elastic pendulum means of the present invention. Furthermore, additional convenience is provided, since the efforts which the operator needs to exert for this operation occur at a time when he is normally in the vicinity of the copyboard. Typically, after loading copy material into the copyboard, and then actuating the appropriate detent, the operator prefers to attend to other duties or operations on the equipment and not to return to the copyboard until the machine cycle has advanced to a point where material in the copyboard is to be removed and replaced by material for the next cycle. At that time, the operator would again approach the copyboard, actuate the appropriate detent, and remain at the copyboard to assist in the motion which beings the copyboard into the loading position, at which time he would proceed with unloading of the material previously exposed or processed and the loading of the material required for the next cycle or operation.

It should be understood that the friction and air resistance encountered by the copyboard in its movement between extreme positions should be minimized, by the use of low friction pivot bearing materials and avoidance of attachments to the to provide greatest effectiveness of the mechanism. However, even when this has been accomplished, the mechanism still requires some manual assistance during the final portion of one of the alternate movements, specifically the movement into the loading position; this assistance compensates for the unavoidable friction air resistance and detent forces described.

Accordingly, it is an object of the present invention to provide a copyboard having means which minimize the manual effort, skill, and attention involved in operating the copyboard, reduces the speed with which the copyboard arrives at each of its extreme, tenninal positions and therefore the potential damage or disturbance, and provides a mechanism of minimum complexity and cost.

Further, it is an object of the present invention to provide a pivoted copyboard having an elastic member or other elastic means operatively attached thereto in a manner to form an elastic pendulum having an equilibrium position located between the extreme positions of the copyboard, thereby implementing movement from either one of the extreme positions to the alternate position.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a copyboard embodying the features of the present invention;

FIG. 2 is an elevational view, with portions broken away to show additional details, of a side support for the copyboard of FIG. 1 and illustrates the mechanism of the present invention housed within the support;

FIG. 3 is a sectional view taken substantially along the line III-III of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, a copyboard mechanism, constructed in accordance with the present invention and generally indicated at 10, is joumalled between a pair of

upright supports

11, 11, which in turn are supported for sliding movement on rails 12 forming a bed for a graphic arts camera. Such a process camera also includes a rear case, for supporting film or similar material, which may be supported on the rails 12 of the camera bed at an end thereof opposite the copyboard 10. It generally includes a front lens case carried on the rails 12 for sliding movement toward and away from the copyboard in a manner to focus the camera. The camera construction also includes illumination means such as the lights 14 for suitably illuminating the copyboard 10.

Although the present invention is described in reference to a copyboard for a graphic arts camera, it should be understood that the principles of the present invention are equally applicable to other copy-boards or similar devices generally utilized in the graphic arts field. One such other device may include a plate exposure apparatus having a pivoted copyboard or vacuum frame adapted for holding flat material in a position suitable to provide a latent image on an offset or similar printing plate.

The copyboardincludes a cover or front section 16 hingedly connected to a base or back section 17 for pivotal movement relative thereto. The base or back section 17 provides a support surface which may include a resiliently mounted pad against which a piece of copy is disposed, and the cover 16 has a transparent window covering and restraining the piece of copy, thereby to clamp the piece of copy between the copyboard sections.

Each of the upright supports 11 includes a casting, or similar structure, having a generally U-shaped configuration in transverse cross-section and characterized by an outer wall 21 and a pair of

parallel side walls

22, 22. An upper wall 23 and a base 24 respectively close upper and lower ends of the side supports 11, thereby forming a cavity 26 in each of the supports.

A pair of

pivot pins

27, 27 are joumalled in the copyboard at opposite sides thereof and in appropriate bearing means. An embossment 28 formed in an upper corner of each of the supports 11 has an aperture 29 formed therein for receiving the pivot pins 27, thereby to mount the copyboard 10 for tiltable or pivotable movement about a generally horizontally extending pivot axis. The copyboard 10 may be tilted selectively between a vertical, working or expose position, as illustrated in FIG. 1, and a horizontal loading-unloading or process position. It may be seen that, for other applications or configurations, the expose position and the loading position may be selected to be at positions other than the vertical and the horizontal, for example the loading position may be horizontal and the working or expose position may be substantially horizontal but rotated approximately one-half revolution from the loading-unloading or process position.

In order to constrain the copyboard 10 in the selected one of the alternate positions, a pair of

detent means

31 and 32 are provided in one of the side supports 1 1 for cooperation with a pair of appropriately disposed detent blocks as at 33. Each of the detent means 31 and 32 has a handle 34 enabling manual movement of the detent against a spring force in a manner to release the detent, thereby permitting movement of the copyboard 10 to the alternate position. Each of the detent blocks 33 has a base 36 attached to the back section 17 of the copyboard 10 by suitable fasteners, such as screws as at 37. An outwardly ofiset abutment 38 on the detent block base 36 is engaged by the associated one of the detent means 31 or 32 in a manner to lock or constrain the copyboard in the selected position until the operator releases the detent to move the copyboard to the alternate position.

In accordance with the present invention, elastic means are attached to the copyboard 10 at a location radially offset from the pivot axis in a manner to cooperate with the copyboard for forming an elastic pendulum having an equilibrium position between the loading-unloading position and the exposing or working position, thereby to assist an operator in moving the copyboard from one of the positions to the alternate position with a minimum amount of effort being required.

As illustrated in the drawings, the elastic means include a spring 41 having one end portion as at 42 attached to one of the side supports 11. An L-shaped bracket 43 has one leg portion 44 secured to the support base 24 by suitable fasteners, such as screws as at 46. An aperture 47 formed in the other leg portion 48 receives a loop 49 formed on the end portion 42 of the spring 41, thereby anchoring the spring to the side support 1 l.

An inextensible, flexible member such as a segment of a roller chain 51 interconnects the other free end 52 of the spring 41 to an outer end 53 of an attachment arm 54. The attachment arm 54 extends at right angles to the copyboard 10 and has a bearing means 56 formed in one end thereof for receiving the pivot pin 27. A pair of

attachment bolts

57, 57 flank the bearing means 56 and secure the attachment arm 54 to the copyboard base section 17. When the copyboard 10 is disposed in the vertical, working position, the attachment arm 54 projects rearwardly, as illustrated 'by solid lines in FIG. 3. As the copyboard 10 pivots from the working position to the loading-unloading position, the attachment arm 54 swings through an arcuate path and assumes a downwardly projecting position, as shown by dotted lines in FIG. 3, when the copyboard arrives at the loading-unloading position.

In order to apply the tension force to the copyboard in a manner to form an elastic pendulum having an equilibrium position between the alternate extreme positions, i.e. the loading-unloading position and the working position, and to confine the mechanism within the cavity 26 of one or both of the side supports 11, the inextensible, flexible member 51 is partially wrapped around rotary support means, such as a chain sprocket generally indicated at 59, thereby providing a method for changing the direction of force and motion of the elastic means. If the pivot axis passes through the center of gravity of the copyboard 10, the equilibrium position would be a position wherein the upper part of the inextensible, flexible member 51 is disposed along a line segment passing through the copyboard pivot axis and tangent to the rotary support means 59. Since the alternate, extreme positions are angularly spaced apart by an angle of in the case described above, the equilibrium position of the inextensible, flexible member 51 lies along a line disposed at 45 from the horizontal and vertical positions of the attachment arm 54. If desired, the pivot axis of the copyboard 10 may be selected relative to the copyboard center of gravity to slightly bias the copyboard toward the vertical, working position. In that case, the spring 41 exerts a force counterbalancing the biasing force whenever the copyboard 10 is at the equilibrium position. The equilibrium position is then displaced slightly from the 45 degree position described.

As illustrated in the drawings, the inextensible, flexible member is a roller chain having one end portion 61 attached to the free end 52 of the spring 41 and having the other end portion 62 attached to the outer end 53 of the attachment arm 54. A loop 63 at the free end 52 of the spring 41 engages one of the rollers as at 64 of the chain 51 for attaching the same to the spring. A pin 66 having an inner end portion press fit into an appropriate aperture 67 formed in an outer end 53 of the attachment arm 54 has a bearing 68 rotatably carried on the outer end portion in alignment with the chain 51. A strap 69 wrapped around the bearing 68 is secured to the upper end 62 of the chain 51 by appropriate attachment means as at 71, thereby to enable pivotal movement of the chain relative to the arms as the arm travels through its arcuate path with the tiltable or pivotal movement of the copyboard 10.

The rotary support means 59 include a sprocket 72 engaged by the chain 51. An L-shaped bracket 73 supports the sprocket 72 and has one leg 74 attached to the support side wall 22 by a pair of nut and

bolt assemblies

76, 76. In order to enable adjustment or selective positioning of the sprocket 72 relative to the copyboard pivot axis, the other leg portion 77 of the bracket 73 has a vertically extending, elongated slot 78 formed therein. A bolt 79 passes through a cylindrical spacer in the bore 81 of the sprocket 72 and through the slot 78 and has an outer threaded portion receiving a nut 82, thereby to retain the sprocket in a selected position along the slot of the bracket 73.

Thus, when an operator releases the detent 32 to enable the copyboard for movement from the loading-unloading position, the combined forces provided by offsetting the copyboard pivot axis from the center of gravity and by the tension spring 41 pivot the copyboard 10 toward the working position. Since the equilibrium position is offset from a precise midpoint between the two alternate extreme positions and toward the working position, the copyboard l0 arrives at the working position with sufficient force and velocity to actuate the detent 31, which subsequently constrains the copyboard in that position. After the copyboard 10 moves through the equilibrium position, the tension spring 41 applies a decelerating force to the copyboard 10 to insure that the copyboard reaches the working position with a sufficiently low terminal speed to avoid damage to the glass and to avoid accidental displacement of the piece of copy constrained in the copyboard. By adjusting the position of the sprocket 72 along the slot 78, the equilibrium position of the copyboard 10 may be selected in a manner to provide the desired results, eg biasing the copyboard toward either one of the alternate positions and, more specifically, as heretofore described, toward the working positron.

The degree to which the equilibrium position should be offset from the geometric mid-point or mid-position is a function of the friction in the copyboard journals, air resistance, and the force necessary to cock the detents. In most practical situations these should be small factors so that the equilibrium position will be very close to the mid-point, thereby affording the advantages of the present invention.

Although various modifications might be suggested by those versed in the art,-it should be understood that I wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art.

I claim as my invention:

1. in a light exposure system, a copyboard mechanism having means for constraining a piece of copy; support means mounting said copyboard for movement about a pivot axis selectively between two alternate positions including a first position for loading and unloading and a second working position angularly disposed from the first position; means for releasably constraining said copyboard in a selected one of the alternate positions; means for assisting movement of said copyboard between said alternate positions, said means inclu ng means for applyrng an elastrc force to sard copyboard at a location radially offset from the copyboard pivot axis; said means for assisting movement of said copyboard between the alternate positions including an inextensible, flexible member; attachment means securing one end portion of said flexible member to said copyboard at a location radially offset from said copyboard pivot axis; elastic means for applying tension to said inextensible, flexible member and being attached to the other end portion thereof; rotary support means having said flexible member partially wrapped therearound and said rotary support means being disposed relative to said copyboard pivot axis and to the point where said flexible member is attached to the copyboard to thereby cause said tension means to urge said copyboard toward an equilibrium position disposed between the alternate positions; said rotary support means having an axis of rotation, said rotary support means being mounted for selective adjustment of its axis of rotation along a path disposed to adjust the equilibrium position upon adjustment of said rotary support means.

2. In a light exposure system a copyboard mechanism having means for constraining a piece of copy; support means mounting said copyboard for tiltable movement about a pivot axis selectively between two alternate positions including a first position for loading and unloading and a second working position angularly related to said first position; means for releasably constraining said copyboard in a selected one of the alternate positions; means for assisting movement of said copyboard between the alternate positions through application of an elastic force to said copyboard at a location radially offset from the copyboard pivot axis; said means for assisting movement of said copyboard between the alternate positions including an inextensible, flexible member having an attachment means securing one end portion of said flexible member to said copyboard at a location radially offset from the copyboard pivot axis, elastic means for applying tension to said inextensible, flexible member and being attached to the other end portion thereof; said copyboard being mounted on said support means so that said copyboard pivot axis is offset from the center of gravity of said copyboard in a direction to bias said copyboard toward one of the alternate positions and relative to said rotary support means; means constraining said copyboard in a selected one of the alternate positions and being releasable to enable movement of said copyboard to the other one of the alternate positions; and said rotary support means being selectively disposed so that said copyboard arrives at the working position with a sufficiently low velocity to prevent damage of the copyboard, its components, and its contents.

3. The invention according to claim 1 wherein said inextensible, flexible member includes a length of roller chain; said rotary support means including a sprocket having said chain engaged therewith.

4. The invention according to claim 2 and further characterized by detent means engageable with portions of said copyboard for constraining the copyboard in a selected one of the two alternate extreme positions and being releasable to permit movement to the alternate one of said positions under the urging of said elastic means.

Claims

1. In a light exposure system, a copyboard mechanism having means for constraining a piece of copy; support means mounting said copyboard for movement about a pivot axis selectively between two alternate positions including a first position for loading and unloading and a second working position angularly disposed from the first position; means for releasably constraining said copyboard in a selected one of the alternate positions; means for assisting movement of said copyboard between said alternate positions, said means including means for applying an elastic force to said copyboard at a location radially offset from the copyboard pivot axis; said means for assisting movement of said copyboard between the alternate positions including an inextensible, flexible member; attachment means securing one end portion of said flexible member to said copyboard at a location radially offset from said copyboard pivot axis; elastic means for applying tension to said inextensible, flexible member and being attached to the other end portion thereof; rotary support means having said flexible member partially wrapped therearound and said rotary support means being disposed relative to said copyboard pivot axis and to the point where said flexible member is attached to the copyboard to thereby cause said tension means to urge said copyboard toward an equilibrium position disposed between the alternate positions; said rotary support means having an axis of rotation, said rotary support means being mounted for selective adjustment of its axis of rotation along a path disposed to adjust the equilibrium position upon adjustment of said rotary support means.