JP2007327953A - Sensor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To lower cost for a sensor device having a belt-like detection area suitable for spectrum concentration measurement or color adjustment based on a control strip (1.K), concerning the sensor device comprising a plane camera 3 and a matrix sensor 4 incorporated into a printed matter passage, for detecting optically a belt-like printed surface 1 of the printed matter 2 moving along the printed matter passage. <P>SOLUTION: Each part 6 of the printed surface 1 continuing successively in the fundamental size direction of the printed surface 1 is projected onto the matrix sensor 4 mutually adjacently by an optical means, for example, a plurality of mirrors (5.S), arranged in the front of the plane camera 3. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sensor device according to the superordinate concept of claim 1 for optical detection of a strip-like printed surface on a printed material moving along a printed material path.

  In a rotary printing press, a line or flat camera has been used for checking printed images of moving printed materials. In that case, the geometric resolution of the camera was set to 0.1 mm / pixel. If there is a problem of detecting an area that is relatively short when viewed in the transport direction but is considerably longer in the axial direction (width of printed matter), for example, a control strip, the following problem arises.

  (1) Since the row camera has about 10,000 pixels per sensor and its number is large, the required geometrical resolving power of 0.1 mm per pixel in the axial direction can be obtained, but the resolving power in the transporting direction has a high transport speed of 5 m / s. However, it is limited to 0.5 mm depending on the linear frequency of the sensor of 10 kHz at maximum.

  (2) Industrial plane cameras currently have a resolution of about 2000 × 1500 pixels, and RGB (red-green-blue) cameras are allocated to three color channels. To detect the total print width with the required geometric resolution of 0.1 mm / pixel, a camera is mounted on the crosshead so that it can move across the transport direction, and a lateral displacement movement, for example, in a small part of 200 mm width. For successive differences, the printed image had to be traversed each time it was scanned. This requires considerable equipment costs, for example at least 10 successive print images need to be scanned to detect the entire measurement group with a print width of 2 m, already between these print images. Differences may appear and limit comparability.

It may also be possible to parallelize the measurement with multiple cameras distributed across the print width to increase the resolution. A method for synchronizing the operation of a large number of electronic cameras is known from German patent publication DE 102004033495A1. In this case, each camera captures one image at a time with one activation signal, and the image data of each camera is collected into one whole image. The first number of image lines are first read from each camera after the photographing is finished and discarded. Subsequently, a second predetermined number of image lines are read from each camera in a predetermined camera order sequentially in time, and processed into an entire image. Finally, after reading the second number of image lines, the remaining image lines are read regardless of other cameras, and the read image lines are discarded. The disadvantages of this solution are the cost of multiple cameras, the cost of camera synchronization and the low image data processing speed due to cumbersome data handling.
German Patent Application Publication DE102004033495A1

  Thus, the basis of the present invention is the problem of reducing the costs for a sensor device with a strip detection area, suitable for spectral density measurement or color adjustment based on a control strip.

  This problem is solved according to the invention by a sensor device having the features of the first claim.

  Combining an inexpensive RGB (red-green-blue) or SW (black and white) plane camera with a matrix sensor and an array of mirrors or prisms, this is a partial surface that continues in the direction of the basic size of the striped printed surface (in the control strip this It is proposed to provide a sensor device for projecting, as a group of rows, onto a matrix sensor, adjacent to each other by optical means (generally print width).

  The present invention optically divides the strip print surface into partial strips, so that the intrinsic resolution of the sensor matrix is fully utilized, and at the same time the matrix sensor cannot be addressed with respect to the rows and the entire sensor matrix must be read out serially. There is an advantage that the disadvantages of a CCD (Charge Coupled Device) camera are overcome.

  The invention will be described in detail by way of an example in which the strip-shaped printing surface is formed as a control strip.

  As apparent from FIG. 1, the flat camera 3 is disposed beside the printed material passage of the rotary printing press, and the printed material 2 has a roll shape or a sheet shape. The printed material 2 conveyed in the direction of the arrow is a conventional control strip 1. K. Control strip K extends across the conveying direction as a belt-like printing surface 1 in the printed image edge area, and is applied for color adjustment or print quality check.

  4. Mirror at almost regular intervals from the printed surface The optical means 5 consisting of S is distributed over the print width at regular intervals according to the resolving power of the matrix sensor 4, thereby avoiding some shadows perpendicular to the optical axis 8 of the planar camera 3. In order to do this, mirror 5. S is different from each other by its width, and a substantially parallel beam is directed to the matrix sensor 4. In order to redirect the beam towards the matrix sensor 4, a mirror 5. A prism may be used instead of S.

  4. Each mirror S to control strip One part 6 of K is assigned and its image is mirror 5. Reflected from S toward the plane camera 3. Mirror 5 S is the control strip. The images of the parallel portions K of K are aligned so as to be projected on the row group 7 of the matrix sensor 4 in an overlapping manner (FIG. 2).

  In order to avoid blurring when the printed product is moved rapidly, a lighting device 9 is arranged in the printed product path and in synchronization with the plane camera 3, the control strip 1. The parallel parallel portions 6 of K are illuminated linearly by a pulse method. The linear illumination can be realized by a cylindrical lens, for example.

  The illuminator 9 has a short flash time and can be composed of light sources having various monochromatic spectra, for example red, blue and green light emitting diode groups. By flushing with various illumination spectra, the planar camera 3 can be used as a spectrum, tristimulus color or density sensor.

  Various emission characteristics and control strips of the light source In order to compensate for the various projection distances (object distances) between the K portion 6 and the planar camera 3 as well as the various light intensities of the image projected onto the matrix sensor 4, the intensity of the light source flash Is preferably adjusted part by part. In order to minimize reflections, the illuminator 9 is mirrored. It is preferable to arrange at an apex angle of 0 ° or 45 ° with respect to S.

  In order to obtain a flat arrangement as much as possible and a rectangular projection of the strip on the matrix sensor 4, the plane camera 3 is preferably slightly inclined with respect to the surface of the printed material 2.

  In order to compensate for the different magnification depending on the object distance, the mirror 5. S is formed with different radii of curvature. It is preferable to use a special objective lens for the planar camera 3 that passes in parallel without expanding the optical path. This always produces an equal image size regardless of the object distance, and mirror 5. S can be designed easily.

  The function and operation of the device according to the present invention are as follows.

  Control strip When K enters the detection zone of the sensor device, the sensor device is activated, the lighting device 9 is activated, and the control strip 1. K images are detected by the planar camera 3 and stored as is well known or reprocessed for printing press control. Control strip K has a dimension of, for example, width × height = 1000 mm × 20 mm. 4. For example five mirrors arranged above the print 2 and distributed across the width of the print across the transport direction Control strip by S 1. Five portions 6.1... 6.5 of 200 mm.times.20 mm of K are imaged on a matrix sensor 4 of, for example, 2000.times.1500 pixels. -A 200 mm x 100 mm surface is projected onto the matrix sensor 4, and each portion 6.1... 6.5 is projected onto one row group 7.1. Thus, a theoretical resolving power of 0.1 mm per pixel in the horizontal direction and 0.07 mm per pixel in the vertical direction is generated under the optimum geometric conditions. With this resolution, the control strip can be digitized, visualized or measured sufficiently accurately.

  The data array search method can then be applied to image detection by detecting diffuse reflection, density or spectral measurements in an array format to subsequently separate desired image data from non-critical image data. This is the control strip K is narrow and the control strip 1. It is particularly advantageous if a printed image area surrounding K is also detected. This image area is the control strip 1. Does not belong to K and must therefore be screened from the image data array prior to reprocessing for print quality checks, color adjustments or press control.

  The proposed sensor device is a control strip. The present invention is not limited to image analysis of K, and can be similarly used for all other image detection functions of the strip-shaped printing surface 1 having a basic size direction that crosses the transport direction or is along the transport direction.

The schematic diagram seen from the upper part of the sensor device which has a mirror system is shown. The front view of a sensor apparatus is shown.

Explanation of symbols

1 Printing surface K control strip 2 printed material 3 planar camera 4 matrix sensor 5 optical means 5 S Mirror 6, 6.1, ..., 6.5 Printed surface portion 7, 7.1, ..., 7.5 Row group 8 Optical axis of plane camera 9 Illumination device

Claims (8)

In a sensor device for optical detection of a strip-like printed surface (1) of a printed matter (2) moving along a printed matter path, comprising a planar camera (3) and a matrix sensor (4) incorporated in the printed matter path,
Portions (6) of the printing surface (1) that successively follow the basic size direction of the printing surface (1) are projected onto the matrix sensor (4) adjacent to each other by optical means placed in front of the plane camera (3). A sensor device. Optical means (5) are distributed along the optical axis (8) of the planar camera (3) at regular intervals over the width of the print and are assigned to each one part (6) of the printing surface (1);
Are offset with respect to the optical axis (8) of the planar camera (3),
The image of the relevant part (6) of the printing surface (1) is projected onto the adjacent row group (7) of the matrix sensor (4), and the order of the part (6) corresponds to the order of the row group (7). The sensor device according to claim 1.   Sensor device according to claim 1 or 2, characterized in that the strip-shaped printing surface (1) is a control strip (1.K) extending across the conveying direction.   Sensor device according to claim 1 or 2, characterized in that the optical means (5) is a mirror (5.S) or a prism.   Sensor device according to claim 4, characterized in that the mirror (5.S) is shaped so that the magnification of the part (6) depending on the object distance is compensated.   6. The sensor device according to claim 1, wherein the illuminating device (9) illuminates the strip-shaped printing surface (1) in a linear manner by a pulse method.   7. Sensor device according to claim 6, characterized in that various illumination spectra can be activated by the illumination device (9).   8. Sensor device according to claim 6 or 7, characterized in that the illumination intensity of the illumination device (9) can be adapted to the object distance of the part (6).

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