Facsimile and static presentation processing – Static presentation processing – Plotter
Reexamination Certificate
1998-04-17
2001-01-23
Rogers, Scott (Department: 2724)
Facsimile and static presentation processing
Static presentation processing
Plotter
C358S001800, C347S239000, C347S244000, C347S243000
Reexamination Certificate
active
06178006
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority under 35 U.S.C. §119 of German Patent Application No. 197 16 240.1, filed on Apr. 18, 1997, the disclosure of which is expressly incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a photoplotting method and an arrangement for plotting a computer-stored raster image on a plane, photosensitive record carrier, i.e., for plotting picture elements (pixels) on a record carrier. The picture elements to be plotted may be arranged, at raster (grid pattern or matrix) positions, according to a raster, which may be defined by points of intersection of equidistant X/Y lines.
The photoplotting method and arrangements serve, e.g., to produce photographic artwork for printed circuit boards.
2. Discussion of Background Information
Photoplotters plotting a computer-stored raster image on a plane, photosensitive record carrier are known in the prior art (information sheet “Xenon Plotter” by the company MIVATEC, Hard- und Software GmbH, Benzstr. 17, D-71171 Schönaich, of Oct. 15, 1996).
During said plotting, an exposure head (with a plotting area of about 5×7.5 mm) is guided over a record carrier, which has a large area (up to about 720×600 mm) in relation to it, for the purpose of plotting picture elements, which make up the raster image of the record carrier.
The exposure head is provided with an LCD (liquid crystal device) matrix (or liquid crystal array) of light modulation elements. This LCD matrix comprises multiple liquid crystal elements arranged in form of a matrix, each of which can be selectively controlled by electrical means in order to open or block it for transmitted light.
If transmitted light is projected onto this LCD matrix, it can only pass as a “light beam” through the matrix at the those element points that are controlled to admit passage. Each of the light beams admitted forms a corresponding picture element on the photosensitive record carrier. Missing light beams—equivalent to blocked elements—form “missing picture elements”.
The raster image of the record carrier comprises a multiplicity of picture elements, including plotted or non-plotted (missing) ones.
In the aforesaid arrangement, light from a Xenon flash lamp is projected onto the LCD matrix. Since the exposure head containing the LCD matrix has a much smaller area (to be compared with the square of a chessboard) than the record carrier (to be compared with a chessboard with an enormous number of squares), said exposure head must successively be guided to all the positions of the chessboard squares so that picture elements can be plotted there.
In view of the desired high resolution (in the range of >10 micrometers) of the raster image of the record carrier, the movement of the exposure head over the entire area of the record carrier imposes the highest tolerance requirements with regard to the precision of the movement mechanism for the movement of the head.
The greater the movement distances, the more difficult it is to fulfil the highest tolerance requirements. The movement of the exposure head over the entire area of the record carrier is therefore problematic and limits the accuracy of plotting, quite apart from the enormous equipment and cost expenditure for such a movement mechanism. Additionally, the aforesaid photoplotters involve long plotting times (6 minutes to 1 hour, depending on resolution).
SUMMARY OF THE INVENTION
In order to avoid these disadvantages (movement mechanism operating over a large area, long plotting times), it is the aim of the invention to disclose a photoplotting method and an arrangement for its realization with a movement mechanism for a smaller movement area and for shorter plotting times.
Furthermore it is the aim of the invention to disclose a photoplotting method and an arrangement for its realization that permit plotting a raster image of the record carrier with a variable image scale so as to achieve, for example, a higher resolution in the case of reduced-scale images.
These aims of the invention are attained in an advantageous manner by the features stated in the characterizing part of claims
1
and
15
.
Advantageous embodiments of the invention are characterized in the subclaims.
The invention relates to a method of plotting a raster image on a plane record carrier wherein a computer-stored raster image comprising raster points is converted into controllable, raster-point related light beams by means of which picture elements corresponding to the raster points are plotted on the record carrier.
Said method according to the invention comprises the following inventive steps:
the computer raster image is matrix-like divided into imaginary computer raster image subareas (A
1
, B
1
, C
1
, . . . );
the raster image of the record carrier is matrix-like divided into imaginary raster image subareas (A
1
′, B
1
′, C
1
′, . . . ) of the record carrier;
the subareas of the computer raster image and the subareas of the raster image of the record carrier are associated with each other;
the computer raster image subareas (A
1
, B
1
, C
1
, . . . ) are matrix-like divided into imaginary n raster point positions (r
1
-r
9
) and the raster image subareas (A
1
′, B
1
′, C
1
′, . . . ) of the record carrier are matrix-like divided into imaginary n picture element positions (p
1
-p
9
);
the picture element positions (p
1
-p
9
) are associated with the raster point positions (r
1
-r
9
);
the plotting of the picture elements corresponding to the raster points takes place in q (q=1−n) successive time intervals Tq (q=1−n) in such a way that during the q
th
time interval (q=1−n) all the picture elements in the q
th
picture element position of the raster image subareas (A
1
′, B
1
′, C
1
′, . . . ) of the record carrier are plotted simultaneously;
during the q
th
time interval, an aperture matrix (2) with matrix-like arranged aperture matrix fields (HA
1
, HB
1
, HC
1
, . . . ), each having an aperture (a
1
, b
1
, c
1
, . . . ) for the passage of a light beam in order to plot a picture element, is moved in such a way that the light beam is aligned with the respective q
th
picture element position.
Advantageously, this method according to the invention is further developed in such a way that
I. the computer raster image subareas (A
1
, B
1
, C
1
, . . . ) and the raster image subareas (A
1
′, B
1
′, C
1
′, . . . ) of the record carrier are associated with each other, while the plotting of all the picture elements of a raster image subarea (A
1
′) of the record carrier takes place successively by means of the light beam (la
1
) that passes through the aperture (a
1
) of the aperture matrix field (HA
1
) associated with said subarea (A
1
′);
II. the computer raster image subareas (A
1
*, B
1
*, C
1
*, . . . ) and raster image subareas (A
1
′*, B
1
′*, C
1
′*, . . .) of the record carrier are varyingly associated with the aperture matrix fields (HA
1
*, HB
1
*, HC
1
*, . . . ), while the plotting of all the picture elements of a raster image subarea (A
1
′*) of the record carrier takes place successively by means of light beams that pass through the apertures (a
1
*, b
2
*, c
3
*) of different aperture matrix fields (HA
1
*, HB
2
*, HC
3
*) the order of which is freely determined;
III. the conversion of the computer raster image into controllable light beams takes place by means of a light-irradiated LCD (liquid crystal device) matrix with matrix-like arranged light modulation elements (LA
1
, LB
1
, LC
1
, . . . ), each of which is associated with a computer raster image subarea (A
1
, B
1
, C
1
, . . . );
during the q
th
time interval, each light modulation element (LA
1
, LB
1
, LC
1
, . . . ) is controlled to block or admit the passage of light according to the status of the q
th
raster point of the computer raster image subarea (A
1
, B
1
, C
1
, . . . ) associated with s
Greenblum & Bernstein P.L.C.
MIVATEC Hard-und Software GmbH
Rogers Scott
LandOfFree
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