Vacuum holddown device for flexographic printing plates

Claim 2

A platen for supporting any one of a predetermined number of sizes of flexographic plates during wet development, the platen having: an orifice; an annular suction channel surrounding the orifice means for connecting the orifice and the suction channel; and an array of grooves emanating from the channel at angular spacings in the range from two degrees to fifteen degrees, each groove being substantially V-shaped in cross-section and having a depth in the range from 0.002 to 0.025 inches, the cross-sectional area of each groove being selected such that when a printing plate is placed over the suction channel and some portion of the grooves, a developer liquid applied to the plate, and suction applied at the orifice the flow of developer liquid from the wet plate through each groove is impeded by the frictional effects in the grooves thereby forming a seal to permit the suction to hold the plate to the platen even though the plate does not cover the full length of all of the grooves.

Claim 3

The platen of claim 1 wherein the angular spacings of the grooves lie within the range from five degrees to ten degrees.

Claim 4

The platen of claim 2 wherein the angular spacings of the grooves is seven degrees.

Claim 5

The platen of claim 1 wherein the depth of the grooves lies within the range from 0.005 to 0.015 inches.

Claim 6

The platen of claim 2 wherein the depth of each of the grooves lies within the range from 0.005 to 0.015 inches.

Claim 7

The platen of claim 1 wherein the cross-sectional area of the suction channel equal to or greater than the sum of the cross-sectional areas of each of the grooves.

Claim 8

The platen of claim 2 wherein the cross-sectional area of the suction channel is equal to or greater than the sum of the cross-sectional areas of each of the grooves.

Claim 9

The platen of claim 4 wherein the cross-sectional area of the suction channel is equal to or greater than the sum of the cross-sectional areas of each of the grooves.

Claim 10

The platen of claim 5 wherein the cross-sectional area of the suction channel is equal to or greater than the sum of the cross-sectional areas of each of the grooves.

Claim 11

The platen of claim 1 wherein the grooves emanate from the suction channel and extend to the peripheral borders of the platen.

Claim 12

The platen of claim 1 wherein the orifice is located at the upper mid-portion of the platen.

Claim 13

The platen of claim 1 wherein the means for connecting the orifice and the suction channel comprises an array of furrows disposed on the surface of the platen.

Claim 14

The platen of claim 1 wherein the means for connecting the orifice and the suction channel comprises an array of passages disposed through the material of the platen.

Claim 15

In a flexographic printing plate processing apparatus of the type having a support for flexographic printing plate, a brush for scrubbing the surface of a flexographic printing plate held on the support, means to advance the flexographic printing plate into contact with the brush, and means to apply a developer liquid to the surface of the flexographic printing plate, wherein the improvement comprises a platen for supporting any one of a predetermined number of sizes of flexographic printing plates during wet development, the platen having; an orifice: an annular suction channel surrounding the orifice; means for connecting the orifice and the suction channel; and an array of grooves emanating from the channel at angular spacings in the range from two degrees to fifteen degrees, each groove being substantially V-shaped in cross-section and having a depth in the range from 0.002 to 0.025 inches, the cross-sectional area of each groove being selected such that when a printing plate is placed over the suction channel and some portion of the grooves, a developer liquid applied to the plate, and suction applied at the orifice the flow of developer liquid from the wet plate through each groove is impeded by frictional effects in the grooves thereby forming a seal to permit the suction to hold the plate to the platen even though the plate does not cover the full length of all of the grooves.

Claim 16

In a flexographic printing plate processing apparatus of the type having a support for flexographic printing plate, a brush for scrubbing the surface of a flexographic printing plate held on the support, means to advance the flexographic printing plate into contact with the brush, and means to apply a developer liquid to the surface of the flexographic printing plate, wherein the improvement comprises a platen for supporting any one of a predetermined number of sizes of flexographic printing plates during wet development, the platen having; an orifice: an annular suction channel surrounding the orifice; means for connecting the orifice and the suction channel; and an array of grooves emanating from the channel at angular spacings in the range from two degrees to fifteen degrees, each groove being substantially V-shaped in cross-section and having a depth in the range from 0.002 to 0.025 inches, the cross-sectional area of each groove being selected such that when a printing plate is placed over the suction channel and some portion of the grooves, a developer liquid applied to the plate, and suction applied at the orifice the flow of developer liquid from the wet plate through each groove is impeded by frictional effects in the grooves thereby forming a seal to permit the suction to hold the plate to the platen even though the plate does not cover the full length of all of the grooves.

Claim 17

The printing plate processing apparatus of claim 14 wherein the depth of the grooves lies in the range from 0.005 to 0.015 inches.

Claim 18

The printing plate processing apparatus of claim 15 wherein the angular spacings of the grooves lie in the range from five degrees to ten degrees.

Claim 19

The printing plate processing apparatus of claim 14 wherein the cross-sectional area of the suction channel is equal to or greater than the sum of the cross-sectional areas of each of the grooves.

Claim 20

The printing plate processing apparatus of claim 16 wherein the cross-sectional area of the suction channel is equal to or greater than the sum of the cross-sectional areas of each of the grooves.

Claim 21

The printing plate processing apparatus of claim 17 wherein the cross-sectional area of the suction channel is equal to or greater than the sum of the cross-sectional areas of each of the grooves.