JP2009212549A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus for picking up the image of an object continuously moving at high speed and forming it into an image by using an area type imaging device which can be easily and inexpensively obtained. <P>SOLUTION: A CMOS area sensor 11 is a CMOS area sensor of a global shutter type, and a plurality of linear imaging areas for imaging a prescribed area in a main scanning direction are set continuously in a sub scanning direction. The driver (control part) 12 of the imaging apparatus causes the area sensor 11 to image the image of the object every time the non-imaged area of the object faces the specified continuous M lines (4 lines) of the CMOS area sensor 11, and reads the image picked up by the M lines of all the lines for each line. Thus, the image in the main scanning direction of the object is surely picked up, and the area type imaging device is used as a line sensor. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an imaging apparatus that captures an image of an object that moves continuously at high speed using a global shutter type area imaging device.

  A line camera equipped with a CCD line sensor as an image pickup device has been conventionally used for inspecting an object that flows continuously through a production line at high speed, such as an offset printed material such as a book, a film, and a resin plate. The line camera scans (images) an image of an object moving at high speed in the main scanning direction with a CCD line sensor, reads out the image scanned by the CCD line sensor every time the object moves a certain distance, The entire image is formed and output by arranging them in order.

As an inspection apparatus using a CCD line sensor, for example, a color image printed on a web (rolling paper for rotary printing) running at high speed is split into R, G, and B images by a prism. There has been proposed a stain inspection apparatus for printed matter that accurately detects print stains by capturing images of each color with a high-speed monochrome CCD (see, for example, Patent Document 1).
JP 2000-241357 A

  In the CCD line sensor, the charge generated in the light receiving element is moved to the transfer element at a predetermined timing, and the charge moved to the transfer element is sequentially moved to the adjacent transfer element like a bucket relay. One line of image data is taken out pixel by pixel from the end transfer element. Therefore, the next data cannot be read unless all the data (accumulated charge) for one line is read out, and a certain amount of time is required to capture an image with the CCD line sensor. In addition, a CCD line sensor having a larger number of pixels per line requires more time to read data.

  On the other hand, in the production line for offset printed matter, film, resin plate, etc., the moving speed of the object has recently been further increased, but the moving speed of the object is faster than the operating time of the CCD line sensor. In some cases, an image cannot be inspected by a line camera equipped with a CCD line sensor, and the object cannot be inspected.

  In order to solve this problem, it is necessary to use a plurality of CCD line sensors having a small number of pixels and capable of reading data in a short time. However, CCD line sensors are mainly used for products with strong needs for multi-pixels such as copying, faxing, and scanners, and because there are fewer products that use CCD line sensors with a small number of pixels, a CCD with a small number of pixels. The production volume of line sensors is decreasing. In addition, since the CCD line sensor with a small number of pixels is mainly manufactured for a special purpose, there is a problem that it is very expensive as compared with a consumer type.

  Accordingly, an object of the present invention is to provide an imaging apparatus that can reliably image an object that moves continuously at high speed at low cost.

  The present invention has the following configuration as means for solving the above problems.

(1) An imaging device that continuously images an object moving in the sub-scanning direction,
A global shutter type area-type image sensor in which a plurality of line-shaped imaging areas for imaging a predetermined area in the main scanning direction are set continuously in the sub-scanning direction;
Each time the unimaged area of the object is opposed to one or more specific lines of the area-type image sensor, the area-type image sensor images the object, and the image is captured by the specific line. Control means for reading out line by line;
It is provided with.

  In this configuration, the imaging apparatus captures an object every time an unimaged area of the object is opposed to one or more specific lines of the area-type image sensor, and the specific line of the area-type image sensor is Read the captured image line by line. Therefore, since the area-type image sensor continuously captures images of a specific line, the image of the object in the main scanning direction can be reliably captured in the line-shaped image area, and the area-type image sensor can be used as a line sensor. Can be used as

  Here, in the global shutter type area-type image sensor, a plurality of line-shaped imaging areas for imaging a predetermined area in the main scanning direction are set in succession in the sub-scanning direction, and the shutter operation is performed at the same time for all pixels (all lines). In addition to an image pickup device that picks up an image and reads out all the pixels (all lines) picked up at once, there is a device that can read only one or more specific lines out of all the picked up images. In the present invention, one that can read only this specific line is used.

(2) comprising a signal output means for outputting a signal each time the object moves by a certain amount and an unimaged area of the object is opposed to a specific line of the area-type image sensor;
The control means causes the area-type image sensor to pick up an image of the object every time the signal output means outputs a signal.

  In this configuration, each time the object moves by a certain amount and the non-imaging area of the object is opposed to a specific line of the area-type image sensor and the signal output means outputs a signal, the control means is an area type The imaging element is caused to image the object. Therefore, even when the moving speed of the object is variable, it is possible to reliably capture an image of the object continuously with the area-type image sensor.

  The imaging apparatus according to the present invention uses an area-type imaging device such as a global shutter type CMOS area sensor to target an object that moves continuously with respect to one or more specific lines of the area-type imaging device. Each time an unimaged area of an object is opposed, the area-type image sensor is made to image the object, and an image captured by the specific line is read out line by line. For this reason, an image pickup apparatus capable of reliably and continuously picking up an image of an object using a global shutter type area-type image pickup device and capable of high-speed scanning at a lower cost than a conventional apparatus is provided. be able to.

  In the following description, an example in which the imaging apparatus of the present invention is applied to a printing defect inspection apparatus that inspects a defect on a printing paper surface in an offset rotary press will be described, but the application field of the present invention is not limited thereto, The present invention can be applied to a field in which an object moving continuously at a constant speed is continuously imaged and a field in which a conventional line area sensor is used. For example, the present invention can be applied to an apparatus that captures an image of an object with a quality inspection apparatus for printed matter, a quality inspection apparatus for paper and film, and the like.

  A conventional print defect inspection apparatus reads a printed matter with a CCD line sensor to form an image, and compares it with image data of a reference paper. Detects various printing defects such as density changes due to volume fluctuations, white spots due to ink fading and plate wear.

  In the following description, the main scanning direction is the width direction of the object, and the sub-scanning direction is the object feeding direction.

  FIG. 1 is a schematic view of an offset rotary press. The offset rotary press 101 supplies the continuous paper P from the roll paper R set in the paper feeder 102, performs printing in the order of black, cyan, magenta, and yellow by the printing unit 103, and heats the continuous paper P by the dryer 104. And let it dry. Then, the continuous paper P is cooled by the cooling drum 105, the cut-off adjustment is performed by the adjusting roller 106, the meandering correction of the continuous paper P is performed by the web guide device 107, and both sides of the printing paper surface are corrected by the imaging devices 2a and 2b. When the defect inspection is performed, the continuous paper P is bent to a predetermined size by the triangular plate 108.

  FIG. 2 is a block diagram illustrating a schematic configuration of a print defect inspection apparatus including an imaging apparatus according to an embodiment of the present invention. The print defect inspection apparatus 1 includes an imaging device 2, a reference image memory 3, a difference circuit 4, an edge image generation circuit 5, an edge mask circuit 6, a comparison circuit 7, and a defect notification circuit 8. The imaging device 2 scans the image on the printing paper and outputs the read image. The reference image memory 3 stores an image of a non-defective printing paper surface scanned by the imaging device 2 as a reference image. The difference circuit 4 calculates the difference between the image on the printing paper surface scanned by the imaging device 2 and the reference image stored in the reference image memory 3. The edge image generation circuit 5 creates an edge image on the printing paper. The edge mask circuit 6 uses the edge image created by the edge image generation circuit 5 to mask a portion that tends to fluctuate with respect to the spatial movement of the printing paper surface and cancel the fluctuation. The comparison circuit 7 determines an image defect based on the output from the edge mask circuit 6. When the comparison circuit 7 detects a defect in the image, the defect notification circuit 8 notifies the user that there is a defect. The printing defect inspection apparatus 1 determines various defects on the printing paper surface such as dirt, density change, and white spotting by the above-described configuration.

  Next, a schematic configuration of the imaging device 2 will be described. FIG. 3 is a block diagram illustrating a schematic configuration of the imaging apparatus. As shown in FIG. 3, the imaging device 2 includes a lens 10, a CMOS area sensor 11, a driver 12, an image processing circuit 13, a memory 14, and an output circuit 15. The lens 10 forms an image of the object on the CMOS area sensor 11.

  The CMOS area sensor 11 is a global shutter type area-type image sensor having an m-row and n-column configuration in which light-receiving elements are arranged in a matrix, and an object (or an object and its surroundings) for all pixels at a certain time T. Are read (taken) and converted into electrical signals to output image data.

  The driver 12 is a control unit that controls the operation of each unit of the imaging apparatus 2 such as the CMOS area sensor 11 and the image processing circuit 13.

  The image processing circuit 13 performs processing such as A / D conversion and compression on the object image output from the CMOS area sensor 11 and stores the image data in the memory 14. Further, when a certain amount of image data is accumulated in the memory 14, the image processing circuit 13 reads out the image data from the memory 14, synthesizes each image data, and outputs continuous image data.

  The output circuit 15 outputs the image data output from the image processing circuit 13 to the reference image memory 3 or the difference circuit 4.

  Here, a global shutter type area image pickup device will be described.

  Generally, a global shutter type area-type image sensor performs a shutter operation (images) at the same time for all pixels (all lines). In addition, in this type of area-type image pickup device, there is a type that can read only one or more specific lines of all the picked-up lines in addition to one that reads all picked-up pixels (all lines) at once. In the present invention, one that can read only this specific line is used. As a global shutter type area type imaging device, a CMOS area sensor or a CCD area sensor capable of reading only a specific line is suitable.

  As is well known, some area-type image sensors include a rolling shutter type, and this type of area-type image sensor sequentially performs a shutter operation for each scanning line.

  Next, the imaging operation of the printing paper surface of the imaging device 2 will be described. FIG. 4 is a conceptual diagram for explaining the operation of the imaging apparatus according to the embodiment of the present invention. Here, the CMOS area sensor 11 has a configuration in which m × n light receiving elements are arranged in a matrix. In the following description, as shown in FIG. A method of capturing an image every time a non-imaged area of a target object faces this imaging area using a specific continuous line-shaped imaging area by 4 × n light receiving elements as a part will be described. FIG. 4A shows 4 × n light receiving element rows of the CMOS area sensor 11. In the present invention, an example in which four continuous lines of the CMOS area sensor 11 are used will be described. However, the present invention is not limited to this, and a specific line of one or more lines is determined depending on the configuration of the imaging device, the object, and the like. Use a line.

  The CMOS area sensor 11 is a global shutter type area sensor, and receives all lines (m lines) including four lines (four rows) shown in FIG. 4A at the same timing and accumulates electric charges. At this time, the shutter time is set so that one line advances. Then, in the imaging device 2, image data of 4 lines is read from 1 line which is the specific continuous 4 lines (4 rows) shown in FIG. 4A among all the lines of the CMOS area sensor 11.

  4 (2) shows the movement of the object 12, and FIGS. 4 (2) A to 4D show the object moving at a constant speed from the top to the bottom (sub-scanning direction). It shows how they are doing.

  Here, the number of lines of the CMOS area sensor 11 is M (rows) (4 rows in FIG. 4), the pixel width (field height) of each line is d (mm), and the moving speed of the object (printing paper surface) is V (mm / sec), and the readout time for one row is Tr (seconds). The CMOS area sensor 11 has m lines in the sub-scanning direction, and performs imaging on the m lines, but the specific continuous four lines (M lines) are used as the line sensor. Further, the CMOS area sensor 11 is a device having a blank period of B line (row), and the readout time of one line is Tr (seconds). (Seconds).

  In this case, the imaging timing is set so as to satisfy the following formula.

M · d / V = (M + B) · Tr
In many cases, the moving speed V of the paper surface is variable. Therefore, the rotary encoder 16 or the like is installed in the printing machine so that the reading time Tr (second) for one line depends on the moving speed V of the object (printing paper surface). It is preferable to attach a signal output means and adjust the imaging timing by a synchronization signal output from the rotary encoder 16.

  That is, the rotary encoder 16 outputs a signal each time the object (printing paper surface) moves by a certain amount in the sub-scanning direction with respect to the first line to the fourth line of the CMOS area sensor 11 and the non-imaging area faces. Set to The driver 12 causes the CMOS area sensor 11 to pick up an image of the object (printing paper surface) every time the rotary encoder 16 outputs a signal.

  As shown in FIG. 4 (2) A, the CMOS area sensor 11 instantaneously (at the above-mentioned shutter shutter position) captures the image of the N line to N + 3 line of the object (printing paper surface) at the first line to the fourth line at a certain timing. (Time) and charge of this image is accumulated. Then, by sequentially reading out the charges of the image for the four lines of the image sensor for each line, the image data of the N line, N + 1 line, N + 2 line, and N + 3 line on the paper surface can be read. Thereafter, at the next shutter timing (between the time for four rows and the vertical blanking time), as shown in FIG. 4 (2) B, four lines N + 4 to N + 7 are changed to the first line of the CMOS area sensor 11. The relationship among the moving speed of the printing paper surface, the height of the imaging range (imaging area), and the scan time is selected so that the printing paper surface moves to a state where it can be imaged on the fourth line. As a result, as shown in FIG. 4B, at the next shutter timing, the CMOS area sensor 11 accumulates image charges from the N + 4 line to the N + 7 line in the first line to the fourth line. Become. Then, when the charges of the four lines of the image of the CMOS area sensor 11 are sequentially read out line by line, the N + 4 line, N + 5 line, N + 6 line, and N + 7 line images on the printing paper surface can be read out.

  Similarly, as shown in FIG. 4 (2) C, the CMOS area sensor 11 captures the N + 8 line to the N + 11 line in the first line to the fourth line of the CMOS area sensor 11, and further performs the next imaging timing. At the imaging timing, as shown in FIG. 4 (2) D, the first to fourth lines capture N + 12 lines to N + 15 lines.

  As described above, the CMOS area sensor 11 can capture an object with all lines (all pixels) and read out images captured with four specific continuous lines, one line at a time. This CMOS area sensor 11 can be used as a line sensor for imaging.

  Here, the CMOS area sensor used in the image pickup apparatus according to the embodiment of the present invention uses a small-sized sensor instead of a small line-type image pickup device such as a linear CCD, so that an image of an object can be obtained at higher speed. Can be imaged. However, in this case, depending on the size of the target object, the entire target object may not be imaged because the imaging range in the main scanning direction (width direction) of the CMOS area sensor is narrow. Therefore, in such a case, the imaging apparatus may be configured as follows. FIG. 5 is an overview diagram illustrating a configuration of an imaging apparatus having an expanded imaging range. As shown in FIG. 5A, the plurality of imaging devices 2 may be arranged at a predetermined interval in the main scanning direction so that a part of the imaging range of each imaging device 2 overlaps. Or you may arrange | position with a predetermined space | interval so that the imaging range of each imaging device 2 may not overlap. And it is good to set so that each imaging device 2 may perform one of said methods simultaneously, and may image a target object. Further, in the case of such a configuration, it is preferable to provide an image synthesis circuit 9 that synthesizes the images output by the imaging devices 2 and outputs the entire image of the object. By adjusting the overlapping portion of the imaging range of each imaging device 2 by the image composition circuit 9, it is possible to acquire an entire image of the target object in which the mounting error of each imaging device 2 is corrected. Moreover, when arrange | positioning so that an imaging range may not overlap, the image of the whole target object can be acquired by arranging the image of each imaging device 2 continuously.

  Further, as shown in FIG. 5B, a plurality of lenses 10 and a CMOS area sensor 11 may be provided inside one image pickup apparatus 2. Also in this case, the lenses 10 and the CMOS area sensor 11 are preferably arranged at a predetermined interval so that a part of the imaging range of each CMOS area sensor 11 overlaps. And it is good to set so that each CMOS area sensor 11 may perform one of said methods simultaneously, and may image an object. Further, each CMOS area sensor 11 may be driven by a single driver 12 according to the driving capability of the driver 12, or each CMOS area sensor 11 may be driven by a plurality of drivers 12. May be. Further, the image data output from each CMOS area sensor 11 may be synthesized by the image processing circuit 13. With this configuration, even when the imaging range of the object is wide, the entire image can be easily captured with an inexpensive configuration.

  As described above, the imaging apparatus of the present invention can reliably capture an image of an object that moves continuously at a high speed with an inexpensive configuration, and therefore the imaging apparatus of the present invention is applied to a print defect inspection apparatus. Thus, it is possible to reliably detect defects even on a printing paper surface printed at high speed by an offset rotary press.

  The present invention can be applied to the field of continuously imaging an object that moves continuously, the field where a conventional line area sensor is used, for example, the quality inspection device for printed matter, the quality inspection device for paper, film, and the like.

It is a general-view figure of an offset rotary press. 1 is a block diagram illustrating a schematic configuration of a print defect inspection apparatus including an imaging apparatus according to an embodiment of the present invention. It is the block diagram which showed schematic structure of the imaging device. It is a conceptual diagram for demonstrating operation | movement of the imaging device which concerns on embodiment of this invention. It is the general-view figure which showed the structure of the imaging device which expanded the imaging range.

Explanation of symbols

  1-printing defect inspection device, 2-imaging device, 10-lens, 11-CMOS area sensor, 12-driver, 13-image processing circuit, 14-memory, 15-output circuit, 16-rotary encoder

Claims (2)

An imaging device that continuously images an object moving in the sub-scanning direction,
A global shutter type area-type image sensor in which a plurality of line-shaped imaging areas for imaging a predetermined area in the main scanning direction are set continuously in the sub-scanning direction;
Each time the unimaged area of the object is opposed to one or more specific lines of the area-type image sensor, the area-type image sensor images the object, and the image is captured by the specific line. Control means for reading out line by line;
An imaging apparatus comprising: A signal output means for outputting a signal each time the object moves by a certain amount and an unimaged area of the object opposes a specific line of the area-type image sensor;
The imaging device according to claim 1, wherein the control unit causes the area-type imaging device to capture an image of the object every time the signal output unit outputs a signal.

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