DE102008022881A1 - Two-dimensional, individually controllable vertical cavity surface emitting laser-emitter arrangement for use in e.g. direct imaging printing machine, is rotated around one axis, where positions of emitters lie on hexagonal grid - Google Patents

Abstract

The arrangement (1) is rotated around an axis about an angle of rotation relative to a projection line running parallel to a lateral direction of printing plates to be imaged by an imaging device e.g. direct imaging printing machine, where the axis is perpendicular to a plane of the arrangement. Positions of individually controllable vertical cavity surface emitting laser (VCSEL)-emitters (2) lie on a hexagonal grid. A distance (R) of one adjacent emitter is about 378 micrometers, and the angle of rotation is about 12.2 degree.

Description

The The present invention relates to a two-dimensional array of individually controllable VCSEL emitters with the characteristics of the generic term of claim 1 Furthermore, the present invention relates to a An imaging device having the features of the preamble of claim 5th

In For example, in the graphics industry, the use of lasers in the imaging and therefore in imaging devices such. B. so-called DI printing machines (direct imaging) or Plattenbelichtem known.

The EP 1 241 013 B1 discloses a device for imaging a printing form with a Cartesian arrangement of lasers, which are designed as individually controllable VCSEL emitters (Vertical Cavity Surface Emitting Lasers).

From the DE 103 38 015 A1 a printing method is known, wherein also a Cartesian arrangement of individually controllable VCSEL emitters is used. The assembly is rotated through an angle α such that the exposure points projected on a line allow the creation of a continuous exposure line.

The JP 2007-293016 A also describes a Cartesian VCSEL arrangement.

at the manufacture and use of high power VCSEL devices On the one hand, it is necessary to know the distance of a VCSEL emitter to make his neighbor as big as possible the influence of so-called "crosstalk effects" low to keep. On the other hand, however, it is also necessary that To make optimum use of existing space to get out of one as many as possible VCSEL arrangements to be able to produce. It is therefore an object of the present invention Invention to provide an emitter assembly which meets both requirements enough.

These Object is achieved by an arrangement solved with the features of claim 1. Advantageous developments The invention will become apparent from the accompanying dependent claims as well as from the description and the accompanying drawings.

A Inventive two-dimensional arrangement of individually controllable VCSEL emitters, which the illustration of Serve printing forms, the arrangement around a - vertical to the plane of the arrangement standing - axis by a rotation angle relative to a - parallel to the lateral direction of Printing forms running - projection line is turned, is characterized by the fact that the positions of each VCSEL emitter lie on a substantially hexagonal grid. The inventive Arrangement satisfies both put in an advantageous manner Requirements: both the increase of the emitter distance, as well as the optimal utilization of the area.

A advantageous due to the achievable resolution of about 600 dpi and therefore preferred embodiment of the invention Arrangement may be characterized in that the distance between adjacent emitters and the angle of rotation are chosen such that the distance on the projection line of projected adjacent exposure points, d. H. the distance whose centers is about 40 microns.

A another due to the achievable resolution of about 600 dpi advantageous and therefore preferred development of the invention Arrangement may be characterized in that the distance of adjacent Emitter is about 378 microns.

A another due to the achievable resolution of about 600 dpi advantageous and therefore preferred development of the invention Arrangement may be characterized in that the rotation angle is about 12.2 °.

A Inventive imaging device for illustrations of printing forms is characterized by at least one - how in this application with respect to the invention described or shown - arrangement out.

The invention as such as well as structurally and / or functionally advantageous developments of the invention will be described below with reference to the accompanying drawings with reference to at least one preferred embodiment. In the drawings, corresponding elements with each provided the same reference numerals.

The Drawings show:

1 Schematic representation of an arrangement according to the invention (before rotation);

2a . 2 B Schematic detail of an inventive arrangement (after a rotation;

3a . 3b Schematic representation of another arrangement according to the invention.

1 shows a schematic representation of the inventive two-dimensional, non-Cartesian, preferably substantially hexagonal arrangement 1 individually controllable VCSEL emitter 2 (before rotation) or such a device. Such an arrangement is used, for example, for the imaging of printing forms (printing plates, films or cylinder surfaces). The printing form to be imaged is z. B. spanned on a cylinder and rotated. The emitter arrangement is arranged adjacent to the rotating printing form and either moved parallel to the axis of rotation or executed sideways, so that no lateral movement is necessary for page-wide images. The X and Y directions used hereinafter correspond to the lateral direction and the circumferential direction of the rotary printing form.

In 1 In addition, the distances R are drawn. The respective distance R between two adjacent emitters 2 is about 378 microns. The order 1 includes a preferred number of 256 emitters in 32 columns (X direction) and 8 lines (Y direction). By way of example, mention may be made of the emitters (1,1), (1,8), (32,1) and (32,8).

In 2a are the first four odd columns of the emitter arrangement according to the invention 1 (after a turn) shown. Neighboring emitter 2 a rotated column in turn have a distance R. The order 1 is rotated by an angle α such that the emitters projected onto the line L emit 2 have a distance A. The line L corresponds to a line to be imaged, laterally (in the X direction) on the printing form, which is located in front of the emitter arrangement 1 moved in the circumferential direction or Y-direction along.

In 2 B the columns 1 to 14 are shown. By superposing the projections of even and odd columns, the distance A 'of adjacent projected emitters becomes 2 opposite the distance A in 2a halved.

With the emitter arrangement according to the invention 1 is it possible to write 250 lines per centimeter. This corresponds approximately to the resolution of 600 dpi usual in digital printing. For this purpose, the emitter 2 However, not as usual in the art on a Cartesian, but arranged on a non-Cartesian and preferably substantially hexagonal grid. For this purpose, the grid is rotated by a certain angle α (clockwise or alternatively counterclockwise) so that the projections of adjacent emitters 2 on a line L have a distance of 40 microns to each other (to achieve exactly 600 dpi, a grid of 42.3 microns would be required). To deal with the emitter 2 to be able to write or image a continuous line L produce the emitters 2 in turn, a respective Bebilderungspunkt of about 40 microns in diameter on the line L.

One can the arrangement according to the invention 1 see also two interleaved arrangements, the first arrangement (columns 1, 3, 5, etc.) having the X-positions 0, 80 μm, 160 μm, 240 μm, etc. and the second arrangement (columns 2, 4, 6, etc.) describes the X positions 40 μm, 120 μm, 200 μm, etc.

In the arrangement according to the invention, the last emitter 2 the first column (1,8) an X-position at a distance of 80 microns next to the first emitter 2 occupy the third column (3,1), or the non-existent emitter (1,9) is located at the same X position as the emitter (3-1) (see. 2a ). The missing 40 μm position in between is filled in by the emitter (2, 5) of the second column (cf. 2 B ).

With R as distance between the emitter of a column and α as The angle of rotation of the emitter arrangement around the emitter (1,1) is: 8 * R * sin (α) [2 * R * sin (60 °)] * sin (90 ° + α). With sin (90 ° + α) cos (α) and conversion the equation for α yields sin (α) / cos (α) = (2 · R · sin (60 °)) / (8 · R) also tan (α) = (1/4) · sin (600) or α = 12.2163 °, thus about 12.2 °. With R · sin (α) = 80 μm one obtains R = 378.067 microns, thus about 378 microns. In comparison: In a Cartesian arrangement and given 40 micron grid would be a lower emitter distance of only about 320 microns and thus expected stronger so-called "crosstalk effects" result.

V-Position vor dem Drehen

X-Position nach dem Drehen

V-Position nach dem Drehen

The positions (X, Y) of each emitter 2 the arrangement 1 after rotation at a given angle of rotation α of about 12.2 ° are thus calculable and given below by way of example for columns 1-4 and 29-32 (unit: μm): X-position before rotation

V position before turning

X-position after turning

V position after turning

The X positions of the emitters calculated in this way 2 after the turns are listed in the following table sorted from the smallest to the largest X value (unit: μm) and listed by way of example for the first and last 15 values. Example: The emitter (1,1) at the unchanged X position 0 occupies eleventh place in the list and serves to generate the seventh line point, since the first four emitters of the list are not used for generating line points. Sort the X position of the emitter after turning X position column line line point 1 -560 1 8th x 2 -480 1 7 x 3 -400 1 6 x 4 -320 1 5 x 5 -240 1 4 1 6 -200 2 8th 2 7 -160 1 3 3 8th -120 2 7 4 9 -80 1 2 5 10 -40 2 6 6 11 0 1 1 7 12 40 2 5 8th 13 80 3 8th 9 14 120 2 4 10 15 160 3 7 11 242 9240 30 2 238 243 9280 31 5 239 244 9320 30 1 240 245 9360 31 4 241 246 9400 32 8th 242 247 9440 31 3 243 248 9480 32 7 244 249 9520 31 2 245 250 9560 32 6 246 251 9600 31 1 247 252 9640 32 5 248 253 9720 32 4 x 254 9800 32 3 x 255 9880 32 2 x 256 9960 32 1 x

The Y positions of the emitter 2 after the rotation correspond to the respective time at which an emitter 2 must be turned on to write a closed line L together with its neighbor emitters. The Y values are listed in the following table from the smallest to the largest Y value (unit: um) and are listed as examples for the first and last 15 values. Since some emitters occupy the same V positions, only 176 Y positions are listed in the total. Example: Emitter (4,2) comes to lie at a Y position at about 393 μm and - in order to be able to write a closed line with the other emitters - must be activated as the tenth emitter. Sort the Y position of the emitter after rotation V-Position column line 1 -115 2 1 2 0 1 1 3 23 4 1 4 139 3 1 5 162 6 1 6 254 2 2 7 277 5 1 8th 300 8th 1 9 370 1 2 10 393 4 2 11 416 7 1 12 439 10 1 13 508 3 2 14 531 6 2 15 554 9 1 162 3995 24 8th 163 4018 27 7 164 4041 30 7 165 4111 23 8th 166 4134 26 8th 167 4157 29 7 168 4180 32 7 169 4249 25 8th 170 4272 28 8th 171 4296 31 7 172 4388 27 8th 173 4411 30 8th 174 4526 29 8th 175 4550 32 8th 176 4665 31 8th

The data for controlling the emitter 2 must be prepared so that each emitter 2 get the right data at the right time. Since the differences in the V position are smaller than a 40 μm pixel, there must be an imaging clock that is smaller than the pixel clock. The minimum necessary clock results from the differences of the V positions of the emitter 2 after the turn.

To describe a closed area with 32 × 8 according to the invention and preferably substantially hexagonal VCSEL emitters 2 an angle of α is about 12.2 ° necessary. To achieve a different resolution, the distance of the emitter must be 2 be recalculated according to the formula R · sin (α) = 2 * raster. It is also a different number of emitters 2 possible, wherein the number of lines determine the angle of rotation α: α = arctan ((2 / Z) · sin (60)) with Z = number of lines.

The 3a and 3b show a further embodiment of the arrangement according to the invention. The emitter arrangement 1 is already rotated during production on the so-called "wafer", so that a mechanical rotation of the produced so-called "chips" can be advantageously avoided. Around while the existing surface of the wafer or the resulting chip to use optimally, the emitter 2 rearranged on the wafer during production: all emitters 2 , which after rotation are below the emitter (1,1) and thus below the zero line, are shifted to a so-called "sister position" above the zero line. So z. B. the emitter (3,1) to the position (1,9) offset. 3b shows the emitter arrangement according to the invention after such a sorting.

In addition, missing emitters can 2 be filled at the left and right margins, however, which increases the total number of emitters 2 would increase. To avoid this, the emitter can be avoided 2 also remove on one side and be added on the other side.

The arrangement according to 3b is particularly advantageous because the average distance of the individual emitter 2 given given, to bebilderndem grid (in the embodiment: 40 microns) larger than in Cartesian arrangement and thus the disturbing, so-called "Crosstalk" is reduced. In addition, the available surface of the wafer or chip is optimally utilized.

The number of emitters 2 in the exemplary embodiment of 32 × 8 = 256 (= 2 ⁸ ) is a size which is favorable for electronics and software. The area that the inventive arrangement 1 of 32x8 VCSEL emitters 2 is needed with about 10 mm to 3 mm in a similar order of magnitude as today's edge emitters. It can therefore be used in an advantageous manner on such Justage- and gripping tools that are already available for the processing of edge emitters.

By compared to a corresponding Cartesian arrangement enlarged distances between the present invention and preferably substantially hexagonally arranged emitters 2 It is also easier for the individual control between the emitters 2 to carry out necessary interconnects.

In the in 2 B shown embodiment, a total of eight emitters - four on the left and four on the right edge - are not used for the imaging, if only an emitter arrangement according to the invention 1 used for imaging. However, it can -. B. to enable a section width or page width imaging - several inventive emitter assemblies 1 side by side (laterally offset) are arranged. Then, missing edge emitters of one device can be filled in by edge emitters of the adjacent device.

The emitter arrangement 1 can be additionally provided with an optical system to image the imaging points exactly on the surface to be imaged.

1

Emitter arrangement

2

emitter

A

distance

A '

distance

α

angle of rotation

L

Projection line

R

distance the emitter

X

direction

Y

direction

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• EP 1241013 B [0003]
• - DE 10338015 A1 [0004]
• - JP 2007-293016 A [0005]

Claims (5)

Two-dimensional arrangement of individually controllable VCSEL emitters, which are used for the imaging of printing plates, wherein the arrangement ( 1 ) is rotated about an axis perpendicular to the plane of the arrangement by an angle of rotation (α) relative to a projection line (L) running parallel to the lateral direction of the printing plates, characterized in that the positions of the individual VCSEL emitters ( 2 ) lie on a substantially hexagonal grid. Arrangement according to claim 1, characterized in that the distance of adjacent emitters ( 2 ) and the angle of rotation (α) are selected such that the distance (A ') to the projection line (L) projected, adjacent exposure points, ie the distance centers thereof, is about 40 microns. Arrangement according to claim 1, characterized in that the distance (R) of adjacent emitters ( 2 ) is about 378 microns. Arrangement according to claim 1, characterized the angle of rotation (α) is about 12.2 °. Imaging device for the illustration of printing forms with at least one arrangement ( 1 ) according to any one of the preceding claims.