Plate cassette for platesetter

Abstract

A plate cassette for a platesetter comprises a tray that receives and stores stacks of plates. Side frame members are located on opposed sides of the tray. These side frame members have tracks that engage with wheels of another plate cassette and wheels that engage with tracks of still another plate cassette. In this way, cassettes may be stacked and stored, one on top of each other. The wheel engagement strategy, between cassettes, however, allows individual cassettes to be rolled out, enabling access to the plate stack in the selected cassette's tray. A suction leak groove is formed in a surface of the tray. This provides for a suction leakage path for a picker, when the picker must grab typically the last plate in the stack and the plate is not full-sized. The suction grabbers that do not directly grab the plate do not adhere to the tray, allowing the picker to separate the plate from the tray. A slip sheet removal groove is also provided.

Description

BACKGROUND OF THE INVENTION

[0001] Plates are typically large substrates that have been coated with photosensitive or thermally-sensitive material layers. Depending on the type of plate, they can be sensitive or insensitive to ambient light. The plates are usually used in commercial printing operations. For large run applications, the substrates are fabricated from aluminum, although organic substrates, such as polyester or paper, are also available for smaller runs. Because of the composition, the plates can be somewhat heavy, especially in the context of a stack of relatively large plates.

[0002] Computer-to-plate printing systems are used to render digitally stored print content onto these printing plates. Typically, a computer system is used to drive an imaging engine of a platesetter. The engine selectively exposes the surfaces of the plates. In a common implementation, the plate is fixed to the outside or inside of a drum and then scanned with a modulated laser source in a raster fashion.

[0003] Typically, one of two different strategies is used to feed the plates to the imaging engine. In the simplest case, an operator manually places individual plates into a feeder that then conveys the plates through a feed port to the drum scanner. This approach, however, has some obvious drawbacks, since an operator must be dedicated to feeding the plates. Moreover, the printing system must be housed within a light-safe environment, if the plates being used have any sensitivity to ambient light. The alternative approach is to use a plate manager.

[0004] Plate managers typically house multiple cassettes. Each cassette holds tens of plates in a stack. For example, in one common implementation, each cassette holds about thirty to fifty plates. The plate manager selects plates from one of its cassettes and then feeds the plates, automatically, into the imaging engine.

[0005] In these designs, cassettes are loaded into the plate manager on separate tables. The tables are then raised and lowered inside the manager to bring the plates of a selected cassette into cooperation with a plate picker that grabs individual plates and feeds them to the imaging engine.

[0006] In some applications, the plates can be shipped and stored in these cassettes. In other cases, the plates are shipped to the end user in a crate and then transferred to the cassettes by an operator.

SUMMARY OF THE INVENTION

[0007] The present invention is directed to plate cassettes and specifically improvements concerning functionality, usability, and form factor of these cassettes.

[0008] In general, according to one aspect, the invention features plate cassettes for platesetters. The cassettes comprise trays that receive and store stacks of plates. Side frame members are located on opposed sides of these trays. These side frame members have tracks that engage with wheels of another plate cassette and wheels that engage with tracks of still another plate cassette. In this way, the cassettes may be stacked and stored, one on top of each other. The wheel engagement strategy between cassettes, however, allows individual cassettes to be rolled out, enabling access to the plate stack in the selected cassette's tray.

[0009] According to the present embodiment, a suction leak groove is formed in a surface of the tray. This provides for a suction leakage path for a picker, when the picker is grabbing typically the last plate in the stack and the plate is not full-sized. The suction grabbers that do not directly grab the plate do not adhere to the tray, allowing the picker to separate the plate from the tray.

[0010] In specific implementations, edge guides may be provided in the tray. These may be slid along the guides in order to adjust to different sized plate stacks.

[0011] In order to protect the stack of plates held in the tray, in the present embodiment, cover frame members are further provided on opposed sides of the trays. A cover then cooperates with these cover members to protect plates in the tray.

[0012] In the preferred embodiment, the wheels are located on the bottom of each side frame member. This allows the cassette to be rolled by an operator, in one example. This feature can be especially useful when the plate cassette holds a full stack of full-size plates, which can weigh over 100 pounds or about 50 kilograms.

[0013] In this configuration, the tracks are located on the top of each side frame member. Specifically, groove-shaped tracks are used in one example.

[0014] To align multiple cassettes, one on top of each other, registration features are preferably incorporated into the tracks. These can be stops and/or bumps that are used to allow the operator to “feel” when the cassettes are properly stacked.

[0015] According to still further aspects of the present invention, support ledges can be provided on the cassette. These are used to cooperate with docking station arms that are used to engage and support the cassette, for example, in a plate manager.

[0016] In general, according to still another aspect, the invention features a plate cassette for a platesetter. It has a tray for receiving a stack of plates and a suction leak groove formed in a surface of the tray for providing a suction leak path for a picker, especially when grabbing undersized plates that are held in the tray.

[0017] The above and other features of the invention including various novel details of construction and combinations of parts, and other advantages, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular method and device embodying the invention are shown by way of illustration and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In the accompanying drawings, reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale; emphasis has instead been placed upon illustrating the principles of the invention. Of the drawings:

[0019] FIG. 1 is a perspective view of a plate cassette, according to the present invention, with its cover removed;

[0020] FIG. 2 is a perspective view of a plate cassette with its cover, according to the present invention;

[0021] FIG. 3 is a perspective view showing the bottom of the plate cassette according to the present invention;

[0022] FIG. 4 is a close-up view showing the cassette wheels and support ledges according to the present invention; and

[0023] FIG. 5 is a perspective view of the plate cassette with a stack of plates loaded in it, according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] FIG. 1 shows a plate cassette that has been constructed according to the principles of the present invention.

[0025] Generally, the plate cassette comprises a tray 102, which has an annular outer sidewall 110 to thereby define a recess into which a stack of plates is loaded during operation.

[0026] In more detail, the tray 102 comprises a generally planar top surface for supporting a stack of plates. A registration guide 105 projects upward from the tray's surface; the stack of plates is registered against this guide 105. Adjustable stack registration guides 106 are movable to accommodate different size plates.

[0027] Specifically, movable stack registration guide 106-T engages a top of the plates. It has a thumbscrew, which when loosened allows the registration guide 106-T to slide in its corresponding track 104-T. In a similar vein, left and right stack registration guides 106-L, 106-R are also adjustable by the loosening of a corresponding adjustment screws so that they can slide in respective guide tracks 104-L, 104-R.

[0028] In order to allow the plate stack to be centered on the tray 102, a ruler 108 is provided extending laterally across the tray 102, at the front.

[0029] The annular outer sidewall 110 comprises left and right side frame members 112-L, 112-R. These side frame members project upward from the planar surface of the tray 102. According to the invention, each side frame member comprises a track 114-L, 114-R for guiding the wheels of another plate cassette. In the specific illustrated embodiment, the tracks 114-L, 114-R are located at the tops of the side frame members 112L, 112R and comprise grooves in which the wheels of another cassette ride allowing stacked cassettes 100 to be moved or slide relative to each other.

[0030] The outer sidewall 110 further comprises cover frame members 112-B, 112-F. These similarly project up from the planar surface of the tray 102. The cover frame members 112-B, 112-F extend between the slide frame members 112-L, 112-R at the back and front of the plate cassette 100.

[0031] Relevant to the discussion of the next figure is the fact that the cover frame members 112-B, 112-F have tops that are somewhat lower than the side frame members 112-L, 112-R. This is illustrated by the lips 116 between the higher side frame members 11 2-L, 11 2-R and the cover frame members 112-B, 112-F.

[0032] FIG. 2 shows the plate cassette with an optional cover 120. Specifically, a cover 120 sits on the cover frame members 112-B, 112-F. It specifically sits between the lips 116. In this way, the cover 120 is primarily supported by the cover frame members 112-B, 112-F. It prevents light leakage between the cover 120 and the side frame members 112-L, 112-R.

[0033] Best shown from the view of FIG. 2 are front support ledges 130-LF and 130-RF. Note that a similar pair of support ledges are found on the backside of the cassette 100. These ledges 130-LF, 130-RF comprise cut-out regions that accept docking station arms to enable the automated engagement and support of the plate cassette 100 in a plate manager, for example.

[0034] Further shown are wheels 140-R. These wheels 140-R are designed and positioned to cooperate with a track 114-R on another plate cassette, located under the illustrated plate cassette 100. This configuration allows the plate cassettes to be stacked but still slide relative to each other.

[0035] FIG. 3 shows the bottom of the plate cassette 100. The view shows all four of the support ledges 130-LF, 130-RF, 130-LB, 130-RB. Also shown is a reinforcing member 150. In one embodiment, the tray 102 and the annular outer sidewall 110 are comprised of a plastic, such as a foamed or other molded plastic. As such, it may not be strong enough to support the sometimes heavy stack of plates. In the present implementation, a planar support member 150 is adhered to the bottom side of the tray 102 to increase the rigidity of the plate cassette 100. Presently, a honeycombed aluminum matrix is used.

[0036] FIG. 4 is a close-up view illustrating the support ledge 130-LB. Also shown is one of the wheels 140-L.

[0037] This close-up view further shows some of the features in the tracks 114. Specifically, in the illustrated track 114-L, a bump 160-L is provided. This bump provides sensory feedback to the operator to facilitate detection of when stacked cassettes are registered and aligned, one on top of each other. Specifically, when the wheels of a cassette are riding in the track and that cassette is nearing full insertion, the operator will detect the cassette's wheels riding over the bump 160-L. Further, to maintain the alignment of stacked cassettes 100, a stop 162-L is provided to retain the cassettes in an aligned position by preventing the wheels from continuing to roll in the track 114-L.

[0038] Preferably, a similar bump 160-R and stop 162-R are provided in the other track 114-R, which is not shown in this view.

[0039] FIG. 5 shows the plate cassette 100 loaded with a stack of plates 10. The registration brackets 106-L, 106-R, 106-T are adjusted in their respective tracks 104-L, 104-R, 104-T to hold and maintain the plates 10 in a stack configuration.

[0040] Another feature of the invention is appreciated with reference to the location of suction ports 50, shown in phantom. This shows where the suction ports of a picker would be located relative to the cassette 100 and specifically, the plates 10 and the tray 102. As shown, some of these suction port locations are located over the plates 10. This allows the suction ports to engage and pick up the top plate in the stack 10. When less than full-sized plates are used as shown, some of the ports 50 will miss the plates. In some cases, these suction ports would grab the tray 102, especially when picking the last plates in the stack 10. It could lead to unintended operation as the cassette 100 was picked up by the plate picker.

[0041] According to the present invention, a suction leak groove 170 is provided in the tray 102. This suction leak groove extends laterally across the tray 102. This groove 170 is a depressed portion in the otherwise planar surface of the tray 102. As a result, this will prevent the creation of a vacuum between the tray 102 and the plate picker, which will prevent the plate picker from unintentionally picking-up the cassette 100, allowing only the top plate in the stack 10 to be picked.

[0042] A second, slightly wider slip-sheet removal groove 172 also extends laterally across the tray 102 between the leak groove 170 and the registration guide 105. This groove is also a depressed portion or recess in the otherwise planar surface of the tray 102. It is provided to facilitate the removal of slip sheets for small plates.

[0043] Slip sheets are sometimes used to separate the plates in the stack 50. They can be removed using a set of rollers that engages the sheet and then is driven to pull the sheet off the stack of plates. Sometimes one slip sheet remains after the last plate has been removed from the cassette. The slip-sheet removal groove 172 prevents engagement between the rollers and the tray 102, especially for smaller plate slip sheets, thereby preventing tray movement when the rollers are driven and also prevent wear to the rollers and tray.

[0044] While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.

Claims

1. A plate cassette for a platesetter, comprising:

a tray for receiving a stack of plates;

side frame members on opposed sides of the tray;

tracks on the side frame members that engage with wheels of another plate cassette; and

wheels on the side frame members that engage with tracks of another plate cassette.

2. A plate cassette as claimed in claim 1, further comprising a suction leak groove formed in a surface of the tray for providing a suction leakage path for a picker.

3. A plate cassette as claimed in claim 1, further comprising guides that slide on the tray for aligning the stack of plates.

4. A plate cassette as claimed in claim 1, further comprising:

cover frame members on opposed sides of the tray; and

a cover cooperating with the cover frame members to protect plates in the tray.

5. A plate cassette as claimed in claim 4, wherein the cover engages side frame members upon closure.

6. A plate cassette as claimed in claim 1, wherein the wheels are located on a bottom of each side frame member.

7. A plate cassette as claimed in claim 1, wherein the tracks are located on a top of each side frame member.

8. A plate cassette as claimed in claim 7, wherein the wheels are located on a bottom of each side frame member.

9. A plate cassette as claimed in claim 1, wherein the tracks comprise grooves for guiding the wheels, the tracks being formed into each side frame member.

10. A plate cassette as claimed in claim 1, further comprising cassette registration features formed into at least one of the tracks for aligning the cassette to another plate cassette.

11. A plate cassette as claimed in claim 10, wherein the registration features comprise at least one bump in one of the tracks that cooperates with the wheels of the other cassette.

12. A plate cassette as claimed in claim 1, further comprising a reinforcing member attached to a bottom of the tray for increasing the rigidity of the cassette.

13. A plate cassette as claimed in claim 1, further comprising support ledges that cooperate with docking station arms that engage and support the cassette.

14. A plate cassette as claimed in claim 13, wherein the ledges comprise cut-out regions for accepting the docking station arms.

15. A plate cassette as claimed in claim 1, further comprising a suction leak groove formed on in a surface of the tray for providing a suction leakage path for a picker.

16. A plate cassette as claimed in claim 1, further comprising a slip-sheet removal groove formed in a surface of the tray for providing clearance between slip sheet rollers and the tray during removal of a slip sheet on the tray.

17. A plate cassette for a platesetter, comprising:

a tray for receiving a stack of plates; and

a suction leak groove formed on in a surface of the tray for providing a suction leakage path for a picker.

18. A plate cassette as claimed in claim 15, further comprising edge guides that slide on the tray for aligning the stack of plates.

19. A plate cassette for a platesetter, comprising:

a tray for receiving a stack of plates; and

a slip-sheet removal groove formed in a surface of the tray for providing clearance between slip sheet rollers and the tray during removal of a slip sheet on the tray.

20. A plate cassette as claimed in claim 15, further comprising edge guides that slide on the tray for aligning the stack of plates.