JP4382016B2 - Image forming apparatus and image forming method - Google Patents

Description

  The present invention relates to an image forming apparatus such as a color copying machine and an image forming method.

  In recent years, digitalization of office automation (OA) devices such as copying machines has progressed, and in particular, the demand for color images has increased, so that devices capable of processing color images, such as scanners for capturing color images, can be used. 2. Description of the Related Art Image forming apparatuses having an apparatus and an output apparatus such as an ink jet type or thermal transfer type color printer have been widely used. This image forming apparatus has a plurality of processing units for processing image data between a CCD (Charge Coupled Device) sensor for capturing an image and a printing unit for outputting the image, and between these processing units. A transmission path for transmitting image data, for example, a data bus is provided.

  One pixel of the digitized image data is composed of a plurality of bits, and the data of each bit is transmitted through a transmission path corresponding to each bit. The transmission line is, for example, a conductor wiring pattern wired on the substrate. If there is a failure in a transmission line of one bit among a plurality of transmission lines, for example, the data of the faulty transmission line is invalid. For this reason, a correct image cannot be output. In particular, an unnatural image is output when there is a failure in a bit having a high weight.

  When storing image data composed of a plurality of bits converted into digital quantities in the image memory in the conventional technique of an image memory for storing image data, the bit having the most weight among the bits of the image data (hereinafter, If there is a problem with the input / output system for inputting / outputting MSB (Most Significant Bit) data to / from the image memory, the MSB data input / output system is converted to the least weighted bit (hereinafter referred to as Least Significant Bit). There is an image memory having a circuit for replacing the data input / output system. Since MSB data is replaced with LSB data and stored, an image with improved unnaturalness can be reproduced, and an image memory that is practically acceptable can be provided (for example, Patent Document 1). reference).

Japanese Patent Laid-Open No. 3-201288

  However, the above-described conventional technique replaces the input / output system of the MSB with the input / output system of the LSB and replaces the input / output system of the MSB when the failed part is the input / output system of the MSB after the faulty part of the image memory is specified. The image memory for storing the data is disclosed in Japanese Patent Application Laid-Open No. 2004-26853, and the technique for specifying the faulty part is not disclosed. In an image forming apparatus according to a conventional technique, if there is an abnormality in an output image, it is only possible to recognize that there is a problem somewhere in the image forming apparatus, and a faulty part, for example, image data is transmitted. There is a problem that the faulty part of the transmission path cannot be specified.

  An object of the present invention is to provide an image forming apparatus and an image forming method capable of specifying a faulty part of a transmission path for transmitting image data.

The present invention relates to an image including transmission means including a plurality of transmission paths provided for each bit for transmitting image data bit by bit, and output means for outputting an image based on the image data transmitted by the transmission means. A forming device,
Test data which generates test data consisting only of image data transmitted through one transmission path for all transmission paths included in the transmission means, and sets a plurality of test data consisting only of the generated test data as a set of test data Generating means;
The image forming apparatus further includes control means for transmitting the set of test data to the transmission means and causing the output means to output a set of output images.

According to the present invention, image data is transmitted by transmission means including a plurality of transmission paths provided for each bit in order to transmit image data bit by bit, and an image based on the image data transmitted by the transmission means by output means. Is generated for all the transmission paths included in the transmission means by the test data generation means, and the test data generation means includes only the generated test data. The test data is a set of test data, the control means transmits the set of test data by the transmission means, and the output means outputs a set of output images.

  In this way, test data for outputting an output image formed only from image data transmitted through one transmission path is generated for all transmission paths included in the transmission means to form a set of test data, A set of generated test data is transmitted to the transmission means, and a print confirmation pattern, which is a set of output images formed from the set of test data, is output to the output means, so printing corresponding to the transmission path is performed. A confirmation pattern can be output.

The present invention further includes reading means for reading an image and generating image data,
The control means causes the reading means to read the set of output images, generates confirmation image data, and identifies a defective transmission path based on the generated confirmation image data.

  According to the present invention, the control means determines whether the transmission means is defective based on the confirmation image data generated by causing the reading means to read the print confirmation pattern that is a set of output images output by the output means. Therefore, the image forming apparatus can identify a defective transmission path.

Further, in the present invention, when the output means outputs the one set of output images, a non-printing output image that becomes white when no image data is transmitted to any of the plurality of transmission paths, Output together with the set of output images,
The control means, when there is a white output image in the set of output images indicated by the confirmation image data, identifies a transmission path for transmitting the image data that has become the white output image as a defective transmission path If an output image of a color different from white is output to the non-printing output image, the transmission path for transmitting the image data of the output image output to the non-printing output image is specified as a defective transmission path. It is characterized by.

According to the present invention, when outputting the set of output images by the output means, a non-printing output image that becomes white when no image data is transmitted to any of the plurality of transmission paths, It is output together with the set of output images. Then, when there is a white output image in the set of output images indicated by the confirmation image data by the control means, the transmission path for transmitting the image data that has become the white output image is a defective transmission path. identified, if the output image of a color different from the white non-printing output image is output, but should transmit image data of the output image is output to the non-print the output image, Ru is identified as transmission line failure Therefore, a defective transmission path can be specified based on a set of output images and non-printed output images .

The present invention further includes switching means for switching the transmission line to another transmission line,
The switching means switches the defective transmission path controlled and specified by the control means to another transmission path.

  According to the present invention, since the defective transmission line is switched to another transmission line by the switching means, the image data of the bit of the defective transmission line can be transmitted via the detour.

According to the present invention, the image data is represented by a predetermined number of bits for each pixel, and each bit representing the one pixel has a weight frequency representing the density of the pixel in binary number,
The switching means switches the defective transmission path to a transmission path for transmitting image data of bits having a weight frequency smaller than the weight frequency of bits of image data transmitted through the defective transmission path.

  According to the present invention, the defective transmission path is switched by the switching means to the transmission path corresponding to the bit with the lowest weighting frequency among the bits of the image data, so that only the information of the image data of the bit with the lowest density is obtained. Can be output.

The present invention further includes at least one processing means for processing image data between the reading means and the output means,
The transmission means includes a first inter-part transmission means for connecting the reading means and one of the processing means.
The control unit causes the reading unit to read a white image and a black image before transmitting the set of test data to the transmission unit, and generates confirmation image data. The generated confirmation image data Is received from the processing means connected to the reading means via the first inter-part transmission means, and a defective transmission path included in the first inter-part transmission means is specified based on the received confirmation image data. It is characterized by.

  According to the present invention, the confirmation image data generated by causing the reading means to read the white image and the black image is sent from the processing means connected to the reading means via the first inter-part transmission means. Based on the received confirmation image data, the defective transmission path included in the first inter-part transmission means is identified. Therefore, the defective transmission path on the input side of the image is identified, and the defective transmission path is identified. You can switch to a detour.

According to the present invention, the processing means includes a plurality of processing means,
The transmission means connects one of the processing means excluding the processing means connected to the reading means and the output means, and the plurality of the reading means as the upstream side and the output means as the downstream side. A plurality of second inter-part transmission means for connecting the processing means in series,
The control means transmits the set of test data to the transmission means to identify a defective transmission path from the second inter-part transmission means on the output side of the processing means connected to the output means. After transmitting one set of test data, the one set of test data is transmitted from the second inter-unit transmission means on the output side of the processing means upstream of the processing means connected to the output means. A defective transmission path included in the second inter-part transmission means is specified.

  According to the present invention, when transmitting a set of test data to the transmission means, after transmitting the set of test data from the second inter-part transmission means on the output side of the processing means connected to the output means Since one set of test data is sequentially transmitted from the second inter-unit transmission unit on the output side of the processing unit upstream of the processing unit connected to the output unit, the transmission unit on the output side includes a plurality of second transmission units. Even if it is composed of inter-part transmission means, it can be specified which second inter-part transmission means is defective.

  Further, in the present invention, when the control means identifies a defective transmission path in the first inter-part transmission means, the switching means switches the defective transmission path to a detour, and further, the one set of test When a defective transmission path is specified by one second inter-unit transmission means when data is transmitted to the transmission means and the defective transmission path is specified, the defective transmission path is made a detour by the switching means. After switching, one of the upstream processing means connected to the second inter-part transmission means in which the defective transmission path is detected is sent to the second inter-part transmission means on the output side of the upstream processing means. A set of test data is transmitted.

  According to the present invention, when a defective transmission line is specified, after the defective transmission line is switched to a detour with respect to the transmission line including the transmission line in which the defect is specified, one set is set for the next transmission line. Therefore, if the bit of the upstream defective transmission line is not a bit having the same weight frequency as the bit corresponding to the downstream detour, the upstream defective A transmission path can be specified.

Further, the present invention generates test data consisting of only image data transmitted by one transmission path for all transmission paths for a plurality of transmission paths provided for each bit in order to transmit image data bit by bit , A test data generation step in which a plurality of test data consisting only of the generated test data is used as a set of test data;
A transmission step of transmitting a set of test data generated in the test data generation step via a transmission line;
A set of output images formed from a set of test data transmitted in the transmission process, and a non-printing output image that becomes white when no image data is transmitted to any of the plurality of transmission paths; An output process for outputting
An image data generation step of reading a set of output images output in the output step and generating confirmation image data;
When there is a white output image in the set of output images indicated by the confirmation image data, the transmission path for transmitting the image data that has become the white output image is specified as a defective transmission path, and non-printing output is performed. When an output image of a color different from white is output to the image, a specific step of specifying a transmission path to which the image data of the output image output to the non-printing output image is to be transmitted as a defective transmission path;
The image forming method further includes a switching step of switching the defective transmission path specified in the specific process to another transmission path.

According to the present invention, first, in the test data generation step, test data consisting only of image data transmitted through one transmission path with respect to a plurality of transmission paths provided for each bit in order to transmit image data bit by bit. Is generated for all transmission lines , and a plurality of test data consisting only of the generated test data is used as one set of test data. In the transmission process, the one set of test data generated in the test data generation process is transmitted through the transmission line. In the output process, a set of output images formed from the set of test data transmitted in the transmission process and white when no image data is transmitted to any of the plurality of transmission paths. A non-printing output image is output.

Next, in the image data generation step, the set of output images output in the output step is read to generate confirmation image data, and in the specific step, the set of output images indicated by the confirmation image data is included. When there is a white output image, the transmission path for transmitting the image data that has become the white output image is specified as a defective transmission path, and an output image of a color different from white is output to the non-printing output image The transmission path to which the image data of the output image output in the non-print output image is to be transmitted is specified as a defective transmission path, and the defective transmission path specified in the specific process is changed to another transmission path in the switching process. Switch.

In this way, test data for outputting an output image formed only from image data transmitted through one transmission path is generated for all transmission paths included in the transmission means to form a set of test data, A set of generated test data is transmitted through a transmission line, a print confirmation pattern which is a set of output images formed from the set of test data is output, and the output set of output images is read and checked. Image data is generated . Then, when there is a white output image in the set of output images indicated by the confirmation image data, the transmission path for transmitting the image data that has become the white output image is specified as a defective transmission path and is not printed. When an output image of a color different from white is output to the output image, the transmission path to which the image data of the output image output to the non-printing output image is to be transmitted is specified as a defective transmission path and further specified. Since the defective transmission line is switched to another transmission line, the image data of the bit of the defective transmission line can be transmitted via the detour.

  According to the present invention, since the print confirmation pattern corresponding to the transmission path can be output, the damaged part of the transmission path transmitting the image data can be specified from the output print confirmation pattern.

  Further, according to the present invention, since the image forming apparatus can identify a defective transmission path, it is possible to automatically identify a defective transmission path without human analysis of the print confirmation pattern.

In addition, according to the present invention, since a defective transmission path can be specified based on a set of output images and non-printed output images , it is possible to automatically detect defects without analyzing the print confirmation pattern. A certain transmission line can be specified.

  In addition, according to the present invention, since the image data of the bit of the defective transmission path can be transmitted via the detour, even if the transmission path for transmitting the image data has a failure, the unnaturalness is further reduced. Can be output.

  Further, according to the present invention, since an image lacking only the information of the image data of the lightest bit can be output, even if there is a failure in the transmission path for transmitting the image data, the unnaturalness is minimized. The image can be output.

  Further, according to the present invention, since it is possible to identify a defect in the transmission path on the input side of the image and switch the defective transmission path to a detour, the unnaturalness of the image due to the defect in the transmission path on the input side. Can be improved.

  Further, according to the present invention, even if the transmission means on the output side is composed of a plurality of second inter-part transmission means, it is possible to identify which second inter-part transmission means is defective. It is possible to improve the unnaturalness of the image due to the defective transmission path on the output side.

  According to the present invention, if the bit of the upstream bad transmission line is not the bit having the same weight frequency as the bit corresponding to the downstream detour, the upstream bad transmission line is identified. Therefore, if the weighting frequency of the bit of the defective transmission path is not the same as the weighting frequency of the bit of the detour, it is possible to identify the upstream defective transmission path and the downstream defective transmission path. it can.

  In addition, according to the present invention, since the image data of the bit of the defective transmission path can be transmitted via the detour, even if the transmission path for transmitting the image data has a failure, the unnaturalness is further reduced. Can be output.

  FIG. 1 is a block diagram showing a schematic configuration of an image forming apparatus 1 according to an embodiment of the present invention. The image forming apparatus 1 is an image forming apparatus such as a digital color copier, for example, a CPU (Central Processing Unit) 10, a CCD (Charge Coupled Device) sensor 11, a scanner ASIC (Application Specific Integrated Circuit) 12, an input processing ASIC 13, A region separation ASIC 14, a halftone ASIC 15, an image writing device 16, and an image writing unit 17 are included.

  The CPU 10 executes a program stored in a memory (not shown) to thereby connect a CCD sensor 11, a scanner ASIC 12, an input processing ASIC 13, an area separation ASIC 14, a halftone ASIC 15, and an image writing device 16 connected via a control bus 19. And the image writing unit 17 are controlled. The CCD sensor 11 includes an A / D (analog-to-digital) conversion unit 11a that converts analog signals of three colors of RGB (Red-Green-Blue) into digitized image data. The CCD sensor 11 reads a document placed on a document table (not shown), converts an RGB analog signal representing the read image into digitized RGB image data by the A / D conversion unit 11a, and converts it. The processed image data is transmitted to the scanner ASIC 12 via the data bus 20a.

  The scanner ASIC 12 controls a scanner unit (not shown) including the CCD sensor 11, receives RGB image data from the CCD sensor 11 via the data bus 20a, and inputs the received RGB image data via the data bus 20b. The image data is transmitted to the processing ASIC 13 and the image data is transmitted to the CPU 10 via the control bus 19. The input processing ASIC 13 converts RGB image data received from the scanner ASIC 12 via the data bus 20b into CMY (Cyan-Magenta-Yellow) three-color image data, and converts the converted image data to the data bus 20c. To the region separation ASIC 14 via

  The area separation ASIC 14 generates area identification information in which the CMY image data received from the input processing ASIC 13 via the data bus 20c is classified into, for example, a character area or a photo area, and the generated area identification information is used as a control bus. It transmits to CPU10 via 19. Further, the CMY image data received from the input processing ASIC 13 is transmitted as it is to the halftone ASIC 15 via the data bus 20d. The halftone ASIC 15 generates black image data from the CMY image data received from the area separation ASIC 14 via the data bus 20d, and subtracts the generated black image data from the received CMY image data. , CMYK (Cyan-Magenta-Yellow-Black) image data is generated. Further, the generated CMYK image data is transmitted to the image writing device 16 via the data bus 20e.

  The image writing device 16 receives CMYK image data from the halftone ASIC 15 via the data bus 20e. Furthermore, for the received CMYK image data, processing for preventing blurring or graininess degradation that occurs when the received CMYK image data is converted into an output image, and processing related to gradation reproducibility After performing the processing based on the area identification information received from the CPU 10 via the bus 19, the processed CMYK image data is transmitted to the image writing unit 17 via the data bus 20f. The image writing unit 17 outputs an image based on the CMYK image data received from the image writing device 16 via the data bus 20f. The image writing unit 17 is a color image output device such as a printer, for example, and outputs an image based on the image data received from the image writing device 16 to paper or the like.

  The data bus 20 is a data bus for transmitting digitized image data, that is, image data represented by a predetermined number of bits per pixel. The data bus 20a for connecting the CCD sensor 11 and the scanner ASIC 12 and the scanner ASIC 12 A data bus 20b connecting the input processing ASIC 13 and the input processing ASIC 13, a data bus 20c connecting the input processing ASIC 13 and the area separation ASIC 14, a data bus 20d connecting the area separation ASIC 14 and the halftone ASIC 15, and a halftone ASIC 15 and image writing A data bus 20e for connecting the device 16 and a data bus 20f for connecting the image writing device 16 and the image writing unit 17 are included.

  The data bus 20 includes a transmission path for transmitting image data bit by bit. The data bus 20a and the data bus 20b are for transmitting, for example, 8-bit image data for each RGB color, that is, 24-bit image data, and are composed of 24 transmission paths. The data bus 20c and the data bus 20d are, for example, for transmitting image data of 8 bits for each color of CMY, that is, 24 bits, and are configured by 24 transmission paths. The data bus 20e and the data bus 20f are for transmitting image data of, for example, 8 bits for each color of CMYK, that is, 32 bits, and are composed of 32 transmission lines.

8 bits for each color, the density of each color has a weight frequency (hereinafter referred to weight) expressed by binary numbers, the first bit of the bit, i.e. the smallest weight 2 ⁰ having a weight of 8 stages, the weight 2 ¹ 2 bits, the third bit of weight ^{2 2,} the fourth bit, the seventh bit of the 6 bits of the weight ^{2 6} of the fifth bit, the weight ^{2 5} weight ^{2 4} weight ^{2 3,} and composed largest weight 2 ⁷ eighth bit.

  The CPU 10 generates test data for specifying a defective transmission path. The test data is a set of test data generated by generating test data for outputting an output image formed only from image data transmitted through one transmission path for all transmission paths. . Specifically, for each bit, when the data is “1”, the transmission line signal is at a high level (hereinafter abbreviated as “H”), and when the data is “0”, the transmission line signal is at a low level. (Hereinafter abbreviated as “L”), test data is generated for all the transmission lines with “H” for only one transmission line and “L” for the other transmission lines. Accordingly, a set of test data for 32 transmission lines includes 32 test data. The CPU 10 sequentially transmits the 32 test data included in the set of test data to the data bus, and causes the image writing unit 17 to output a set of output images formed from the set of test data. Similarly, a set of test data for 24 transmission lines includes 24 test data.

For example, among the four colors of CMYK, the test data for testing whether there is a defect in the transmission path of the fourth bit of C color is “H” only for the fourth bit of C, and all other data Test data whose bit is “L” is used. When the CPU 10 transmits this test data to the image writing device 16 via the control bus 19, the image writing device 16 transmits the received test data to the image writing unit 17 via the data bus 20f. The image writing unit 17 outputs an output image based on the test data received from the image writing device 16 via the data bus 20f. When an output image formed from C fourth bit image data is not output, a defect that always becomes “L” in the transmission path of the data bus 20f for transmitting the fourth bit of C Can be identified. Conversely, the transmission path for transmitting the fourth bit C data bus 20f, if there is a defect becomes always "H", the fourth bit of the C, i.e. the concentration of the weights of 2 ³ is outputted at all times , white is displayed the color of C in a concentration in the area to be displayed, since more in the region of the other concentrations the concentration of weight of 2 ³ C is output after being superposed, transmitting a fourth bit C It is possible to specify that there is a defect that is always “H” in the transmission path.

FIG. 2 is a diagram showing a print confirmation pattern based on a set of test data generated by the image forming apparatus 1 shown in FIG. The print confirmation pattern shown in FIG. 2, that is, one set of output images, is a pattern for confirming whether or not the four colors of CMYK are correctly displayed. FIG. 2A shows an image in which the print confirmation pattern is correctly output on A4 size paper. In the upper row, characters “K”, “C”, “M”, and “Y” indicating the color distinction are output, and under the characters indicating each color, there are portions where each color is indicated by eight levels of density. A white part is shown. 8 steps of concentrations, from the top, the concentration of the first bit, i.e. 2 ⁰ is the least significant bit, second bit, i.e. 2 ¹ concentration, the concentration of the third bit, i.e. 2 ^2, the concentration of the fourth bit, i.e. 2 ³ , the concentration of the fifth bit, ie 2 ^4, the concentration of the 6-bit, i.e. 2 ^5, the concentration of the seventh bit, i.e. 2 ^6, and the concentration of the 8-bit, i.e. 2 ⁷ the most significant bit. The white portion is a portion where white printing, that is, printing is not performed.

  FIG. 2B is an example of printing in the case where there is an abnormality that is always “L” in the transmission path for transmitting the C fourth bit image data. In the print confirmation pattern printed on the A4 paper, the C fourth bit portion is white, and the C fourth bit density color is not output. Therefore, it can be seen from this example of the print confirmation pattern that there is an abnormality which is always “L” in the transmission path for transmitting the C fourth bit image data. In other words, by confirming the presence or absence of printing at the position corresponding to each bit of the print confirmation pattern, it is possible to identify the transmission path of the bit corresponding to the position where printing is not performed, that is, the transmission path that is always “L”. it can.

  In the above-described embodiment, the CPU 10 generates one set of test data (hereinafter, one set of test data is also simply referred to as test data). However, a circuit that generates the above-described test data, such as a test data generator, is connected to the scanner ASIC 12. , Input processing ASIC 13, area separation ASIC 14, halftone ASIC 15, and image writing device 16 may be provided respectively. In this case, in response to an instruction from the CPU 10, each test data generator is caused to generate test data, and the generated test data is transmitted to each data bus. The test data generator is composed of, for example, a 32-bit shift register. First, only one of the bits at both ends is set to “1”, the other bits are set to “0”, and then the “1” bit is set. On the other hand, 32 test data can be generated by sequentially shifting one bit in the direction of the other bit.

  In this way, test data for outputting an output image formed only from image data transmitted through one transmission path is generated for all transmission paths included in the data bus 20 as a transmission means, and one set is generated. A set of generated test data is transmitted to the transmission means, and a print confirmation pattern, which is a set of output images formed from the set of test data, is output to the image writing unit 17 as output means. Therefore, it is possible to output a print confirmation pattern corresponding to the transmission path. Therefore, it is possible to specify the damaged part of the transmission path for transmitting the image data from the output print confirmation pattern.

  Further, the CPU 10 causes the image writing unit 17 to output a set of output images formed from the set of test data, and then causes the CCD sensor 11 to read the output set of output images, thereby A / D. The confirmation image data digitized by the conversion unit 11 a, that is, RGB image data is received via the scanner ASIC 12. The CPU 10 analyzes the received RGB image data and identifies a defective transmission path. For example, if there is an unprinted portion in the print confirmation pattern, it can be specified that there is a defect that always becomes “L” in the transmission path for transmitting the bit density image data of that portion. . Further, if there is no white portion and there is a density portion that does not match the correct print confirmation pattern, the “H” is always set on the transmission path for transmitting the bit density image data output to the white print portion. Can be identified.

  The CPU 10 causes the CCD sensor 11 to read and analyze the data based on the RGB three-color image data received via the scanner ASIC 12, but the output print confirmation pattern is displayed in four colors CMYK. , R image data and G image data are added together, Y color is added, G image data and B image data are added together, C color, and B image data and R image data are added together The M color, the R image data, the G image data, and the B image data are added together to be converted into a white color and analyzed.

  As described above, the CPU 10 serving as the control unit causes the CCD sensor 11 serving as the reading unit to generate the print confirmation pattern which is a set of output images output by the image writing unit 17 serving as the output unit. Since the defective transmission path of the data bus 20 as the transmission means is specified based on the confirmation image data, the image forming apparatus 1 can specify the defective transmission path. Therefore, even if a person does not analyze the print confirmation pattern, a defective transmission line can be automatically identified.

  Furthermore, image data forming an output image that is not included in the one set of output images indicated by the confirmation image data among the print confirmation patterns that are one set of output images to be formed from one set of test data is transmitted. Since the transmission path is identified as a defective transmission path, the defective transmission path can be identified based on a set of output images. Therefore, even if a person does not analyze the print confirmation pattern, a defective transmission line can be automatically identified.

  FIG. 3 is a block diagram showing a part of a detailed configuration related to switching of a defective transmission path in the image forming apparatus 1 shown in FIG. 2 shows a detailed configuration of the halftone ASIC 15 and the image writing device 16 shown in FIG. 1, and a CPU 10 and an image writing unit 17 related to them. The halftone ASIC 15, the image writing device 16, and the image writing unit 17 are connected to the CPU 10 via the control bus 19.

  The halftone ASIC 15 includes an image processing unit A15a that performs the image processing described above for the halftone ASIC 15, and four bit switching units A30 described later. The 32-bit image data output from the image processing unit A15a is input to the four bit switching unit A30 as 8-bit image data of each color of CMYK. For example, 8 bits of C color, that is, 1st to 8th bit image data of C color is input to the uppermost bit switching unit A30, and 8 bits of M color image data is switched to the second bit. The 8-bit image data of Y color is input to the third bit switching unit A30, and the 8 bits of K color is input to the fourth bit switching unit A30. Image data output from the four bit switching units A30 is transmitted to the image writing device 16 via the data bus 20e.

  The data bus 20e is composed of 32 transmission lines 21, and a bit with a small weight in the transmission line 21 is used as a detour 22 for a defective transmission line. That is, the detour for 8 bits of C color is the first bit of C color, the detour for 8 bits of M color is the first bit of M color, and the detour for 8 bits of Y color Is the first bit of Y color, and the detour for 8 bits of K color is the first bit of K color.

  The image writing device 16 includes four later-described bit switching units B31, an image processing unit B16a that performs the above-described processing on the image writing device 16, and four bit switching units A30. The image data output from the four bit switching units A30 included in the halftone ASIC 15 is transmitted to the four bit switching units B31 included in the image writing device 16 via the data bus 20e. That is, 8-bit image data of C color output from the uppermost bit switching unit A30 included in the halftone ASIC 15 is input to the uppermost bit switching unit B31 included in the image writing device 16. Similarly, 8-bit image data of M color output from the second bit switching unit A30 is input to the second bit switching unit B31, and Y color output from the third bit switching unit A30. 8-bit image data is input to the third bit switching unit B31, and 8-bit image data of K color output from the fourth bit switching unit A30 is input to the fourth bit switching unit B31. Is done.

  The image data output from the four bit switching units B31 is input to the image processing unit B16a, and the image data output from the image processing unit B16a is input to the four bit switching units A30 included in the image writing device 16. The Image data output from the four bit switching units A30 included in the image writing device 16 is transmitted to the image writing unit 17 via the data bus 20f.

  The bit switching unit A30 is a circuit for switching a transmission path for transmitting higher-order bit image data to a detour according to an instruction from the CPU 10. For example, the uppermost bit switching unit A30 shown in FIG. 3 uses the C-color first bit transmission line 21 of the data bus 20e as a detour 22 for the C-color second to eighth bits. This is a switching circuit for use. The other three bit switching units A30 are switching circuits for image data of M, Y, and K colors, respectively. The bit switching unit A30 includes an ON / OFF switch 32 and a circuit for transferring data of any one bit from the second bit to the eighth bit to the first bit.

  The ON / OFF switch 32 is realized by, for example, an analog switch formed of a semiconductor and is provided on the input side of the first bit. The ON / OFF switch 32 is in a conductive state when it is ON and outputs the first bit image data, and when it is OFF, it is in a blocking state and does not output the first bit image data. The ON / OFF switch 32 is turned off when the transmission path 21 of the first bit is used as a bypass.

  A circuit for transferring data of any one bit from the second bit to the eighth bit to the first bit is also realized by using, for example, an analog switch formed of a semiconductor, for example, ON / OFF of the first bit. By providing an analog switch between the output side of the OFF switch 32 and each bit of the second bit to the eighth bit, only the analog switch connected to the bit to be bypassed is turned ON, thereby bypassing The bit image data to be transferred can be transferred to the detour 22.

  The bit switching unit B31 is a switching circuit for returning the image data transferred by the detour 22 to the original bit transmission path according to an instruction from the CPU 10. For example, the uppermost bit switching unit B31 shown in FIG. 3 converts the image data transmitted through the C color bypass 22, that is, the first bit transmission path 21 of C color, from the second bit to the eighth bit. This is a switching circuit for returning to any one of the transmission paths 21. The other three bit switching units B31 are switching circuits for image data of M, Y, and K colors, respectively. The bit switching unit B31 includes seven ON / OFF switches 33, a circuit for transferring the first bit of image data to any one of the second to eighth bits, and an ON / GND switching switch 34.

  The ON / OFF switch 33 is the same as the ON / OFF switch 32 and is provided on the input side of each of the 2nd to 8th bits, and ON / OFF of the original bit of the image data transmitted through the detour 22. Only the OFF switch 33 is turned OFF, and the ON / OFF switches 33 of other bits are turned ON.

  A circuit for transferring the image data of the first bit to any one of the second bit to the eighth bit is realized by using, for example, an analog switch formed of a semiconductor, for example, the first bit, the second bit to By providing an analog switch between the output side of each ON / OFF switch 33 of each 8th bit and turning on only the analog switch to the original bit, the image data transferred by the detour 22 is restored to the original. Can be reverted to a bit.

  The ON / GND changeover switch 34 is realized by an analog switch formed of a semiconductor, for example, and is provided on the output side of the first bit. When the ON / GND changeover switch 34 is ON, the first / bit image data is output. When the ON / GND changeover switch 34 is GND, a low level signal is output. The ON / GND changeover switch 34 is set to GND when the first bit transmission line 21 is used as a bypass.

  The image forming apparatus 1 shown in FIG. 3 has a defect such as an open or short in the C fourth bit transmission line 21 of the data bus 20e, and the C fourth bit image data is converted into the C first bit image data. An example in which the transmission path is transmitted as the detour 22 is shown. The bit switching unit A30 for the C image data turns the ON / OFF switch 32 OFF and transfers the fourth bit image data to the output side of the first bit ON / OFF switch 32. The bit switching unit B31 for the C image data turns off only the fourth bit ON / OFF switch 33, turns on the analog switch that connects the first bit and the fourth bit, and changes the first bit image data to the first bit. Transfer to 4 bits. The ON / GND changeover switch 34 prevents the fourth bit image data transmitted through the detour 22 from being output as the first bit image data as GND.

  As described above, the switching means, for example, the bit switching unit A30 and the bit switching unit B31 switches the defective transmission path to the transmission path corresponding to the bit having the smallest weight among the bits of the image data. It is possible to output an image lacking only information of thin bit image data. Therefore, even if there is a failure in the transmission path for transmitting image data, an image with minimal unnaturalness can be output.

  Since the bit switching unit A30 and the bit switching unit B31 are also provided for each of M, Y, and K colors, it is possible to independently switch a defective transmission path to a detour.

  In the image forming apparatus 1 shown in FIG. 3, the first bit transmission path is used as a bypass, but a bit transmission path with a weight smaller than the bit weight corresponding to the defective transmission path is used as a bypass. May be. Specifically, the second bit transmission line is a detour of any one of the third to eighth bit transmission lines, and the third bit transmission line is the fourth to eighth bit. A detour of any one of the transmission lines, a detour of the fourth bit as a detour of any one of the fifth to eighth bits, and a fifth bit of transmission The path is a detour of any one of the 6th to 8th bit transmission lines, the 6th bit is a 7th or 8th bit, and the 7th bit The transmission line may be used as a bypass for the eighth bit transmission line.

  When the 2nd to 7th bit transmission lines are also used as a detour, the bit switching unit A30 is provided with an ON / OFF switch 32 on each input side of the 2nd to 7th bits, and the 3rd bit. It is necessary to provide an analog switch for transferring the image data of each transmission line of the eighth bit to the target detour. Further, the bit switching unit B31 is provided with an analog switch for returning the image data of the detour to the original bit transmission path, and the ON / GND switching switch 34 is provided on the output side of each of the second to seventh bits. It is necessary to provide it.

  As described above, since the defective transmission path is switched to another transmission path by the switching means, for example, the bit switching unit A30 and the bit switching unit B31, the image data of the bit of the defective transmission path is transmitted via the detour. be able to. Therefore, even if there is a failure in the transmission path for transmitting image data, an image with reduced unnaturalness can be output.

  Furthermore, since a plurality of detours can be used, even if there are a plurality of defective transmission lines in the same color transmission line, a different transmission line is assigned to each of the plurality of defective transmission lines. be able to. Therefore, an image with reduced unnaturalness can be output.

  The image writing unit 17 includes four bit switching units B31 (not shown). That is, the four bit switching units A30 of the image writing device 16 and the four bit switching units B31 of the image writing unit 17 are connected by the data bus 20f so that the colors and bit positions of CMYK correspond to each other. The four bit switching units A30 of the image writing device 16 and the four bit switching units B31 of the image writing unit 17 are the data buses of the four bit switching units A30 of the halftone ASIC 15 and the four bit switching units B31 of the image writing device 16 respectively. Similar to switching the defective transmission path 20e to the detour, the defective transmission path of the data bus 20f is switched to the detour according to an instruction from the CPU 10.

  The CCD sensor 11 includes three bit switching units A30 on the output side of the A / D conversion unit 11a, and the data bus 20a is connected to the three bit switching circuits A30. The scanner ASIC 12 includes three bit switching units B31 on the input side, and the data bus 20a is connected to the three bit switching units B31 so that RGB colors and bit positions correspond to each other.

  Similarly, the scanner ASIC 12, the input processing ASIC 13, and the region separation ASIC 14 each include three bit switching units A30 on the output side, and the input processing ASIC 13, the region separation ASIC 14, and the halftone ASIC 15 each have three bits on the input side. A switching unit B31 is included. The data bus 20b connects the three bit switching units A30 of the scanner ASIC 12 and the three bit switching units B31 of the input processing ASIC 13 so that RGB colors and bit positions correspond to each other. The data bus 20c connects the three bit switching units A30 of the input processing ASIC 13 and the three bit switching units B31 of the region separation ASIC 14 so that the colors and bit positions of CMY correspond to each other. The data bus 20d connects the three bit switching units A30 of the area separation ASIC 14 and the three bit switching units B31 of the halftone ASIC 15 so that the colors and bit positions of CMY correspond to each other.

  The three bit switching units A30 of the CCD sensor 11 and the three bit switching units B31 of the scanner ASIC 12 switch the defective transmission path of the data bus a to a detour according to an instruction from the CPU 10. Similarly, according to the instruction of the CPU 10, the three bit switching units A30 of the scanner ASIC 12 and the three bit switching units B31 of the input processing ASIC 13 switch the defective transmission path of the data bus 20b to the detour and input according to the instruction of the CPU 10. The three bit switching units A30 of the processing ASIC 13 and the three bit switching units B31 of the region separation ASIC 14 switch the defective transmission path of the data bus 20c to a detour according to an instruction from the CPU 10, and further switch the three bits of the region separation ASIC 14 The three bit switching units B31 of the unit A30 and the halftone ASIC 15 switch the defective transmission path of the data bus 20d to a detour according to an instruction from the CPU 10.

  In this way, switching means such as a bit is provided for each processing unit as processing means such as the CCD sensor 11, scanner ASIC 12, input processing ASIC 13, area separation ASIC 14, halftone ASIC 15, image writing device 16, and image writing unit 17. Since the combination of the switching unit A30 and the bit switching unit B31 is provided, a defective transmission path can be switched to a detour for each data bus connecting two adjacent processing units.

  The reading means is, for example, the CCD sensor 11, the output means is, for example, the image writing unit 17, the control means and the test data generating means are, for example, the CPU 10, the transmission means is, for example, the data bus 20, and the processing means. Are, for example, the scanner ASIC 12, the input processing ASIC 13, the area separation ASIC 14, the halftone ASIC 15, and the image writing device 16, and the switching means is, for example, the bit switching unit A30 and the bit switching unit B31 included in each processing unit.

  4 to 9 are flowcharts showing the process of switching the defective transmission path to the detour in the image forming apparatus 1 shown in FIG. FIG. 4 is a flowchart showing a process for switching a defective transmission line in the data bus 20a shown in FIG. 1 to a bypass. When the power of the image forming apparatus 1 is turned on, for example, when initial setting at the time of turning on the power is performed, the process proceeds to step S1.

  In step S1, an instruction for placing a blank document on the document table is displayed on the display unit of the image forming apparatus 1, and the operator places the blank document on the document table. When the operator notifies the image forming apparatus 1 by a key operation on an operation unit (not shown), the process proceeds to step S2. In step S2, the CCD sensor 11 reads a blank document, digitizes the read image into RGB image data, and transmits the digitized RGB image data to the scanner ASIC 12 via the data bus 20a. The scanner ASIC 12 transmits the image data received from the CCD sensor 11 to the CPU 10 via the control bus 19.

  In step S3, the CPU 10 determines whether all the bits of the image data received from the scanner ASIC 12 are “1”, that is, whether the signal levels of all the transmission paths of the data bus 20a are “H”. Since the color of the read original is white, if there is no defect that is always “L” in the transmission path, all RGB color bits are “1”, that is, all transmission paths are “H”. When the image data indicates that all the transmission paths are “H”, the process proceeds to step S4, and when any transmission path indicates “L”, the process proceeds to step S7.

  In step S4, an instruction prompting the user to place a black document on the document table is displayed on the display unit or the like of the image forming apparatus 1, and the operator places the black document on the document table. When the operator notifies the image forming apparatus 1 by a key operation on an operation unit (not shown), the process proceeds to step S5. Alternatively, the document table OC (Original Cover) may be opened, that is, the document table cover may be opened. Further, the black original is read by the CCD sensor 11, the read image is digitized into RGB image data, and the digitized RGB image data is transmitted to the scanner ASIC 12 via the data bus 20a. The scanner ASIC 12 transmits the image data received from the CCD sensor 11 to the CPU 10 via the control bus 19.

  In step S5, the CPU 10 determines whether all the bits of the image data received from the scanner ASIC 12 are “0”, that is, whether the signal levels of all the transmission paths of the data bus 20a are “L”. Since the color of the read original is black, if there is no defect that always becomes “H” in the transmission path, the bits of all RGB colors are “0”, that is, all the transmission paths are “L”. When the image data indicates that all transmission paths are “L”, the process proceeds to step S6, and when any transmission path indicates “H”, the process proceeds to step S8. In step S6, the CPU 10 determines that all bits of the data bus 20a, that is, all transmission paths are normal and that a normal printing operation is possible, and proceeds to step S11 shown in FIG.

  In step S <b> 7, the CPU 10 determines that there is an abnormality in the bit that has not been changed to “H”, that is, the transmission path determined to have the signal level “L”, and performs correction processing. The correction process is a process of switching a transmission line that is determined to be abnormal to a detour. Specifically, the CPU 10 includes a bit switching circuit A30 connected to a transmission path determined to be abnormal (hereinafter also referred to as a defective transmission path) among the three bit switching sections A30 of the CCD sensor 11. Instructs to switch the defective transmission path to the detour, and out of the three bit switching sections B31 of the scanner ASIC 12, the bit switching section B31 connected to the defective transmission path is switched to the detour. Instruct to switch. The bit switching unit A30 of the CCD sensor 11 and the bit switching unit B31 of the scanner ASIC 12 instructed by the CPU 10 respectively switch the defective transmission path to a detour and proceed to step S11 shown in FIG.

  In step S8, the CPU 10 determines that there is an abnormality in the bit that has not been set to “L”, that is, the transmission path determined to have the signal level “H”, and performs the same correction as the correction process performed in step S7. Processing is performed, and the process proceeds to step S11 shown in FIG.

  FIG. 5 is a flowchart showing a process of switching the defective transmission path to the detour in the data bus 20f shown in FIG. After any of the processes in steps S6 to S8 shown in FIG. 4 is performed, the process proceeds to step S11.

  In step S <b> 11, the CPU 10 generates test data for the 32 data buses 20 f for transmitting CMYK image data, and transmits the generated test data to the image writing device 16 via the control bus 19. The test data is image data for outputting, for example, a print confirmation pattern (hereinafter also referred to as a test print pattern or a test pattern) shown in FIG. The image writing device 16 transmits the test data received from the CPU 10 to the image writing unit 17 via the data bus 20f. The image writing unit 17 outputs a set of output images formed from the test data received from the image writing device 16, that is, prints a test print pattern on paper or the like.

  In step S12, the scanner, for example, the CCD sensor 11, reads the printed test print pattern to generate RGB image data, and digitizes the generated image data, that is, the read image into RGB image data. The processed RGB image data is transmitted to the CPU 10 via the scanner ASIC 12.

  In step S13, the CPU 10 converts the RGB image data received from the scanner ASIC 12 into CMYK image data for analysis. That is, the R image data and the G image data are added together to add the Y color, the G image data and the B image data are added up to add the C color, and the B image data and the R image data are added together. Each bit of the test print pattern printed by adding M color, R image data, G image data, and B image data to white color, that is, converting it to black color by reversing the shade It is determined whether or not all the bits of the CMYK image data are printed by confirming whether or not the print position is printed. When all the bits are printed, the process proceeds to step S14, and when there is an unprinted bit, the process proceeds to step S15.

  In step S14, it is determined whether or not the white print portion of the printed test print pattern is white. When all the white print portions are white, it is determined that there is no defect in the transmission path of the data bus 20b, and the process proceeds to step S21 shown in FIG. 6, and when the white print portion is not white, the process proceeds to step S15.

  In step S15, the CPU 10 determines that the transmission path of the data bus 20f connecting the image writing device 16 and the image writing unit 17 is defective. If it is determined in step S13 that there is an unprinted bit, the defective transmission path is a defective transmission path for transmitting image data of non-printed bits. When it is determined that the printed portion is not white, the transmission path for transmitting the image data of the color density bits printed on the white printed portion is a defective transmission path.

  In step S <b> 16, the CPU 10 performs a correction process for the data bus 20 f that connects the image writing device 16 and the image writing unit 17. That is, the CPU 10 instructs the bit switching unit A30 connected to the defective transmission path among the four bit switching sections A30 of the image writing device 16 to switch the defective transmission path to the detour, and the image. Of the four bit switching units B31 of the writing unit 17, the bit switching unit B31 connected to the defective transmission path is instructed to switch the defective transmission path to the detour. The bit switching unit A30 of the image writing device 16 and the bit switching unit B31 of the image writing unit 17 instructed by the CPU 10 respectively switch the defective transmission path to the detour and proceed to step S21 shown in FIG.

  FIG. 6 is a flowchart showing a process for switching the defective transmission path to the detour in the data bus 20e shown in FIG. After the process of step S14 or step S16 shown in FIG. 5, the process proceeds to step S21.

  In step S21, the CPU 10 generates test data for the 32 data buses 20e for transmitting CMYK image data, and transmits the generated test data to the halftone ASIC 15 via the control bus 19. The test data is, for example, image data for outputting the test print pattern shown in FIG. The halftone ASIC 15 transmits the test data received from the CPU 10 to the image writing device 16 via the data bus 20e. The test data transmitted to the image writing device 16 is transferred to the image writing unit 17 and printed as a test print pattern by the image writing unit 17.

  In step S22, the CCD sensor 11 reads the printed test print pattern to generate RGB image data, and transmits the generated RGB image data to the CPU 10 via the scanner ASIC 12. In step S23, the CPU 10 converts the RGB image data received from the scanner ASIC 12 into CMYK image data, and confirms the presence or absence of printing at a position corresponding to each bit of the printed test print pattern. It is determined whether all bits of CMYK image data are printed. When all the bits are printed, the process proceeds to step S24, and when there is an unprinted bit, the process proceeds to step S25.

  In step S24, it is determined whether or not the white print portion of the printed test print pattern is white. When the white print portion is all white, the process proceeds to step S31 shown in FIG. 7, and when the white print portion is not white, the process proceeds to step S25.

  In step S25, the CPU 10 determines that the transmission path of the data bus 20e that connects the halftone ASIC 15 and the image writing device 16 is defective. If it is determined in step S23 that there is an unprinted bit, the defective transmission path is a defective transmission path for transmitting image data of non-printed bits. When it is determined that the printed portion is not white, the transmission path for transmitting the image data of the color density bits printed on the white printed portion is a defective transmission path.

  In step S <b> 26, the CPU 10 performs correction processing on the data bus 20 e that connects the halftone ASIC 15 and the image writing device 16. That is, the CPU 10 instructs the bit switching unit A30 connected to the defective transmission path among the four bit switching sections A30 of the halftone ASIC 15 to switch the defective transmission path to the detour and write the image. Of the four bit switching units B31 of the device 16, the bit switching unit B31 connected to the defective transmission path is instructed to switch the defective transmission path to the detour. The bit switching unit A30 of the halftone ASIC 15 and the bit switching unit B31 of the image writing device 16 instructed by the CPU 10 respectively switch the defective transmission path to the detour and proceed to step S31 shown in FIG.

  FIG. 7 is a flowchart showing a process for switching the defective transmission path to the detour in the data bus 20d shown in FIG. After step S24 or step S26 shown in FIG. 6, the process proceeds to step S31.

  In step S31, the CPU 10 generates test data for the 24 data buses 20d for transmitting CMY image data, and transmits the generated test data to the region separation ASIC 14 via the control bus 19. The test data is CMY 24-bit image data obtained by removing 8-bit image data of K color from the 32-bit image data of CMYK generated in step S11. The area separation ASIC 14 transmits the test data received from the CPU 10 to the halftone ASIC 15 via the data bus 20d. The test data transmitted to the halftone ASIC 15 is transferred to the image writing unit 17 via the image writing device 16 and printed as a test print pattern by the image writing unit 17. The test data input from the area separation ASIC 14 is CMY 24-bit test data. If there is no abnormality in the transmission path or the like, the test print pattern at each bit position of K color in the position of each bit. Is not printed.

  In step S32, the CCD sensor 11 reads the printed test print pattern to generate RGB image data, and transmits the generated RGB image data to the CPU 10 via the scanner ASIC 12. In step S33, the CPU 10 converts the RGB image data received from the scanner ASIC 12 into CMY image data, and corresponds to each K bit among the positions corresponding to each bit of the printed test print pattern. It is determined whether or not all the bits of the CMY image data are printed by confirming whether or not the positions other than the positions are printed. When all the CMY bits are printed, the process proceeds to step S34, and when there are unprinted bits among the CMY bits, the process proceeds to step S35.

  In step S34, it is determined whether or not the CMY white print portion of the printed test print pattern is white. When all the white print portions of CMY are white, the process proceeds to step S41 shown in FIG. 8, and when the white print portion is not white, the process proceeds to step S35.

  In step S35, the CPU 10 determines that the transmission path of the data bus 20d connecting the area separation ASIC 14 and the halftone ASIC 15 is defective. If it is determined in step S33 that there is an unprinted bit, the defective transmission path is a defective transmission path for transmitting image data of non-printed bits. When it is determined that the printed portion is not white, the transmission path for transmitting the image data of the color density bits printed on the white printed portion is a defective transmission path.

  In step S36, the CPU 10 performs a correction process for the data bus 20d that connects the region separation ASIC 14 and the halftone ASIC 15. That is, the CPU 10 instructs the bit switching unit A30, to which the defective transmission path is connected, of the three bit switching units A30 of the area separation ASIC 14 to switch the defective transmission path to the detour, and performs the intermediate adjustment. Of the three bit switching units B31 of the ASIC 15, the bit switching unit B31 connected to the defective transmission path is instructed to switch the defective transmission path to the detour. The bit switching unit A30 of the area separation ASIC 14 and the bit switching unit B31 of the halftone ASIC 15 instructed by the CPU 10 respectively switch the defective transmission path to the detour and proceed to step S41 shown in FIG.

  FIG. 8 is a flowchart showing a process for switching the defective transmission path to the detour in the data bus 20c shown in FIG. After the process of step S34 or step S36 shown in FIG. 7, the process proceeds to step S41.

  In step S41, the CPU 10 generates test data for the 24 data buses 20c for transmitting the CMY image data, and transmits the generated test data to the input processing ASIC 13 via the control bus 19. The test data is CMY 24-bit image data obtained by removing 8-bit image data of K color from the 32-bit image data of CMYK generated in step S11. The input processing ASIC 13 transmits the test data received from the CPU 10 to the area separation ASIC 14 via the data bus 20c. The test data transmitted to the area separation ASIC 14 is transferred to the image writing unit 17 via the halftone ASIC 15 and the image writing device 16 and printed as a test print pattern by the image writing unit 17. Also in this case, since the test data is CMY 24-bit test data, as in the case where the test data is input from the halftone ASIC 15, the position of each bit of the test print pattern is determined if there is no abnormality in the transmission path. Of these, printing is not performed at the position of each bit of K color.

  In step S42, the CCD sensor 11 reads the printed test print pattern to generate RGB image data, and transmits the generated RGB image data to the CPU 10 via the scanner ASIC 12. In step S43, the CPU 10 converts the RGB image data received from the scanner ASIC 12 into CMY image data, and corresponds to each K bit among the positions corresponding to each bit of the printed test print pattern. It is determined whether or not all the bits of the CMY image data are printed by confirming whether or not the positions other than the positions are printed. When all the CMY bits are printed, the process proceeds to step S44, and when there are unprinted bits among the CMY bits, the process proceeds to step S45.

  In step S44, it is determined whether or not the CMY white print portion of the printed test print pattern is white. When the white print portion of CMY is all white, the process proceeds to step S51 shown in FIG. 9, and when the white print portion is not white, the process proceeds to step S45.

  In step S45, the CPU 10 determines that the transmission path of the data bus 20c connecting the input processing ASIC 13 and the area separation ASIC 14 is defective. If it is determined in step S43 that there is an unprinted bit, the defective transmission path is a defective transmission path for transmitting image data of non-printed bits. When it is determined that the printed portion is not white, the transmission path for transmitting the image data of the color density bits printed on the white printed portion is a defective transmission path.

  In step S46, the CPU 10 performs a correction process for the data bus 20c connecting the input process ASIC 13 and the region separation ASIC 14. That is, the CPU 10 instructs the bit switching unit A30 connected to the defective transmission path among the three bit switching units A30 of the input processing ASIC 13 to switch the defective transmission path to the detour, and the region separation. Of the three bit switching units B31 of the ASIC 14, the bit switching unit B31 to which the defective transmission path is connected is instructed to switch the defective transmission path to the detour. The bit switching unit A30 of the input processing ASIC 13 and the bit switching unit B31 of the region separation ASIC 14 instructed by the CPU 10 respectively switch the defective transmission path to a detour and proceed to step S51 shown in FIG.

  FIG. 9 is a flowchart showing a process of switching the defective transmission path to the detour in the data bus 20b shown in FIG. After the process of step S44 or step S46 shown in FIG. 8, the process proceeds to step S51.

  In step S 51, the CPU 10 creates test data for the 24 data buses 20 b for transmitting RGB image data, and transmits the generated image data to the scanner ASIC 12 via the control bus 19. The test data is CMY 24-bit image data obtained by removing 8-bit image data of K color from the 32-bit image data of CMYK generated in step S11. The scanner ASIC 12 transmits the test data received from the CPU 10 to the input processing ASIC 13 via the data bus 20b.

  The input processing ASIC 13 transmits the test data received from the scanner ASIC 12 to the region separation ASIC 14 without performing conversion from RGB to CMY according to an instruction from the CPU 10. The test data transmitted to the area separation ASIC 14 is transferred to the image writing unit 17 via the halftone ASIC 15 and the image writing device 16 and printed as a test print pattern by the image writing unit 17. Also in this case, since the test data is CMY 24-bit test data, as in the case where the test data is input from the halftone ASIC 15, the position of each bit of the test print pattern is determined if there is no abnormality in the transmission path. Of these, printing is not performed at the position of each bit of K color.

  In step S52, the CCD sensor 11 reads the printed test print pattern to generate RGB image data, and transmits the generated RGB image data to the CPU 10 via the scanner ASIC 12. In step S53, the CPU 10 converts the RGB image data received from the scanner ASIC 12 into CMY image data, and corresponds to each K bit among the positions corresponding to each bit of the printed test print pattern. It is determined whether or not all the bits of the CMY image data are printed by confirming whether or not the positions other than the positions are printed. When all the CMY bits are printed, the process proceeds to step S54, and when there are unprinted bits among the CMY bits, the process proceeds to step S55.

  In step S54, it is determined whether the CMY white print portion of the printed test print pattern is white. When the white print portion is not white, the process proceeds to step S55, and when the CMY white print portion is all white, the process is terminated.

  In step S55, the CPU 10 determines that the transmission path of the data bus 20b connecting the scanner ASIC 12 and the input processing ASIC 13 is defective. If it is determined in step S53 that there is an unprinted bit, the defective transmission path is a defective transmission path for transmitting image data of unprinted bits. When it is determined that the printed portion is not white, the transmission path for transmitting the image data of the color density bits printed on the white printed portion is a defective transmission path.

  In step S56, the CPU 10 performs a correction process for the data bus 20b connecting the scanner ASIC 12 and the input process ASIC 13. That is, the CPU 10 instructs the bit switching unit A30 connected to the defective transmission path among the three bit switching units A30 of the scanner ASIC 12 to switch the defective transmission path to the detour, and the input processing ASIC13. Among the three bit switching units B31, the bit switching unit B31 connected to the defective transmission path is instructed to switch the defective transmission path to the detour. The bit switching unit A30 of the scanner ASIC 12 and the bit switching unit B31 of the input processing ASIC 13 instructed by the CPU 10 respectively switch the defective transmission path to the detour and terminate.

  In the above-described embodiment, the CPU 10 generates test data. However, the test data generator is provided in each of the scanner ASIC 12, the input processing ASIC 13, the area separation ASIC 14, the halftone ASIC 15, and the image writing device 16, and each test data generator is provided. May generate test data. In this case, the scanner ASIC 12, the input processing ASIC 13, the area separation ASIC 14, the halftone ASIC 15, and the image writing device 16 generate test data with the respective test data generators according to instructions from the CPU 10. Input processing ASIC 13 via data bus 20b, region separation ASIC 14 via data bus 20c, halftone ASIC 15 via data bus 20d, image writing device 16 via data bus 20e, and image writing via data bus 20f To the unit 17.

  In this way, the confirmation image data generated by causing the CCD sensor 11 serving as the reading unit to read the white image and the black image is read via the data bus 20a serving as the first inter-part transmission unit. Since the defective transmission path included in the first inter-part transmission means is specified based on the received confirmation image data received from the scanner ASIC 12 which is a processing means connected to the transmission means, the transmission path on the image input side Thus, it is possible to switch the defective transmission path to the detour. Therefore, it is possible to improve the unnaturalness of the image due to the defective transmission path on the input side.

  Furthermore, when transmitting a set of test data to the data bus which is the transmission means, the second inter-part transmission means on the output side of the processing means connected to the image writing section 17 which is the output means sequentially upstream. For example, since one set of test data is transmitted in order from the data bus on the output side of the image writing device 16, the halftone ASIC 15, the area separation ASIC 14, the input processing ASIC 13, and the scanner ASIC 12, the output side transmission means includes a plurality of second transmission means. It can be specified which second inter-part transmission means is defective even if it is constituted by the inter-part transmission means. Therefore, it is possible to improve the unnaturalness of the image due to the defective transmission line on the output side.

  Furthermore, when a defective transmission path is specified, a set of test data is set for the next transmission path after switching the defective transmission path to a detour with respect to the transmission path including the transmission path in which the failure is specified. Therefore, even if there is a defect in the upstream transmission line and downstream transmission line, the bit of the upstream defective transmission line has the same weight as the bit corresponding to the downstream detour. If the bit is not a weight bit, a defective transmission line on the upstream side can be specified. Therefore, if the bit weight of the defective transmission path is not the same as the bit weight of the detour, the upstream defective transmission path and the downstream defective transmission path can be specified.

  4 to 9 are flowcharts showing processing steps of an image forming method according to another embodiment of the present invention. In this way, test data for outputting an output image formed only from image data transmitted through one transmission path is generated for all transmission paths included in the transmission means to form a set of test data, A set of generated test data is transmitted through a transmission line, a print confirmation pattern which is a set of output images formed from the set of test data is output, and the output set of output images is read and checked. Image data is generated, and image data forming an output image not included in one set of output images indicated by the confirmation image data among a set of output images to be formed from one set of test data is transmitted. Since the transmission line is specified as a defective transmission line, and the specified defective transmission line is switched to another transmission line, the bit image data of the defective transmission line is transmitted via a detour. It can be. Therefore, even if there is a failure in the transmission path for transmitting image data, an image with reduced unnaturalness can be output.

1 is a block diagram illustrating a schematic configuration of an image forming apparatus 1 according to an embodiment of the present invention. FIG. 2 is a diagram showing a print confirmation pattern based on a set of test data generated by the image forming apparatus 1 shown in FIG. 1. FIG. 2 is a block diagram illustrating a part of a detailed configuration relating to switching of a defective transmission path in the image forming apparatus 1 illustrated in FIG. 1. It is a flowchart which shows the process which switches the defect transmission path in the data bus 20a shown in FIG. 1 to a detour. It is a flowchart which shows the switching process to the detour of the defective transmission path in the data bus 20f shown in FIG. It is a flowchart which shows the switching process to the detour of the defective transmission path in the data bus 20e shown in FIG. It is a flowchart which shows the switching process to the detour of the defective transmission path in the data bus 20d shown in FIG. It is a flowchart which shows the switching process to the detour of the defective transmission path in the data bus 20c shown in FIG. It is a flowchart which shows the switching process to the detour of the defective transmission path in the data bus 20b shown in FIG.

Explanation of symbols

1 Image forming apparatus 10 CPU
11 CCD sensor 11a A / D converter 12 Scanner ASIC
13 Input processing ASIC
14 Area separation ASIC
15 Halftone ASIC
Reference Signs List 16 Image writing device 17 Image writing unit 19 Control bus 20 Data bus 21 Transmission path 22 Bypass 30 Bit switching unit A
31 bit switching part B
32, 33 ON / OFF switch 34 ON / GND switch

Claims (9)

An image forming apparatus including transmission means including a plurality of transmission paths provided for each bit in order to transmit image data bit by bit, and output means for outputting an image based on the image data transmitted by the transmission means. And
Test data which generates test data consisting only of image data transmitted through one transmission path for all transmission paths included in the transmission means, and sets a plurality of test data consisting only of the generated test data as a set of test data Generating means;
An image forming apparatus, further comprising: a control unit that transmits the set of test data to a transmission unit and causes the output unit to output a set of output images. Further comprising reading means for reading an image and generating image data,
The control means causes the reading means to read the set of output images, generates confirmation image data, and identifies a defective transmission path based on the generated confirmation image data. The image forming apparatus according to 1. When the output means outputs the set of output images, the output means outputs the non-printed output image that becomes white when no image data is transmitted to any of the plurality of transmission paths. Output with the image,
The control means, when there is a white output image in the set of output images indicated by the confirmation image data, identifies a transmission path for transmitting the image data that has become the white output image as a defective transmission path If an output image of a color different from white is output to the non-printing output image, the transmission path for transmitting the image data of the output image output to the non-printing output image is specified as a defective transmission path. The image forming apparatus according to claim 2. And further includes switching means for switching the transmission line to another transmission line,
4. The image forming apparatus according to claim 2, wherein the switching unit switches the defective transmission line controlled and specified by the control unit to another transmission line. The image data represents one pixel with a predetermined number of bits, and each bit representing the one pixel has a weight frequency representing the density of the pixel in binary number,
5. The switching means switches a defective transmission path to a transmission path for transmitting image data of bits having a weight frequency smaller than that of bits of image data transmitted through the defective transmission path. The image forming apparatus described in 1. And further comprising at least one processing means for processing image data between the reading means and the output means,
The transmission means includes a first inter-part transmission means for connecting the reading means and one of the processing means.
The control unit causes the reading unit to read a white image and a black image before transmitting the set of test data to the transmission unit, and generates confirmation image data. The generated confirmation image data Is received from the processing means connected to the reading means via the first inter-part transmission means, and a defective transmission path included in the first inter-part transmission means is specified based on the received confirmation image data. The image forming apparatus according to claim 4, wherein: The processing means includes a plurality of processing means,
The transmission means connects one of the processing means excluding the processing means connected to the reading means and the output means, and the plurality of the reading means as the upstream side and the output means as the downstream side. A plurality of second inter-part transmission means for connecting the processing means in series,
The control means transmits the set of test data to the transmission means to identify a defective transmission path from the second inter-part transmission means on the output side of the processing means connected to the output means. After transmitting one set of test data, the one set of test data is transmitted from the second inter-unit transmission means on the output side of the processing means upstream of the processing means connected to the output means. The image forming apparatus according to claim 6, wherein a defective transmission path included in the second inter-part transmission unit is specified.   When the control means identifies a defective transmission path in the first inter-part transmission means, the control means switches the defective transmission path to a detour, and further passes the set of test data to the transmission means. When a defective transmission path is specified in one second inter-unit transmission means when transmitting and specifying a defective transmission path, the defective transmission path is switched to a detour by the switching means, The one set of test data is sent to the second inter-part transmission means on the output side of one upstream processing means connected to the second inter-part transmission means in which the transmission path is detected. The image forming apparatus according to claim 7, wherein the image forming apparatus transmits the image. In order to transmit image data bit by bit, test data consisting only of image data transmitted over one transmission path is generated for all transmission paths provided for each bit, and only the generated test data is generated. A test data generation step in which a plurality of test data consisting of
A transmission step of transmitting a set of test data generated in the test data generation step via a transmission line;
A set of output images formed from a set of test data transmitted in the transmission process, and a non-printing output image that becomes white when no image data is transmitted to any of the plurality of transmission paths; An output process for outputting
An image data generation step of reading a set of output images output in the output step and generating confirmation image data;
When there is a white output image in the set of output images indicated by the confirmation image data, the transmission path for transmitting the image data that has become the white output image is specified as a defective transmission path, and non-printing output is performed. When an output image of a color different from white is output to the image, a specific step of specifying a transmission path to which the image data of the output image output to the non-printing output image is to be transmitted as a defective transmission path;
An image forming method, further comprising a switching step of switching the defective transmission path specified in the specific process to another transmission path.