JP2018124873A - Image reading device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reading device that replaces image data according to the timing of occurrence of an abnormality.SOLUTION: An image reading device 100 includes: an image reading unit 103 that receives reflected light from an image of a document illuminated with light from a light source 101 and outputs an image signal 26 and a line synchronization signal 21 indicating the cycle of one line for each line along a main scanning direction; a normal-line-synchronization signal generating unit 1404 that eliminates an abnormal signal from the line synchronization signal to generate a normal line synchronization signal 23; an abnormal-line position signal generating unit 1403 that generates an abnormal-line position signal 27 only when the timing of generating an abnormal signal included in the line synchronization signal lies within an effective image signal 26a, among image signals, which is necessary for image formation; and an image data generation unit 119 that generates image data for each line based on the image signal and the normal line synchronization signal, and replaces image data of the line from which the abnormal-line position signal is output with image data of another line.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image reading apparatus that reads an image of a document.

  The image reading device reads an image of a document and converts the read information into digital data. The image reading apparatus can read a monochrome image and a color image. The image reading apparatus can be provided in an image forming apparatus such as a copying machine or a facsimile. The image reading device illuminates a document with light emitted from a light source, receives reflected light, reads an image for each line along the main scanning direction, and generates line data. If an abnormality due to an external factor such as electrostatic noise occurs during reading of an image of a document, abnormal line data is generated. When an image is formed based on abnormal line data, the image deteriorates. Therefore, Patent Document 1 detects a current value flowing through a light source, and when it is determined that an abnormal state has occurred based on a comparison result between the detected current value and a reference value, abnormal line data is converted into normal previous line data. A replacement image reading apparatus is disclosed.

JP 2012-209713 A

  In Patent Document 1, even when an abnormality occurs in a part of line data due to electrostatic noise, it is determined that all of the read line data for one line is abnormal line data having an abnormality. However, even line data that has been determined to be abnormal line data may be line data that is obtained by normally reading an image for one line. Even though the read line data includes normal image data, it may be determined as abnormal line data and replaced with previous line data.

  The line data includes an effective part (hereinafter referred to as an effective image area) for forming an image to be finally output, and an invalid part (hereinafter referred to as an invalid image) used for adjustment of timing not used for image formation. Area). In order to finally output a desired image, data of an effective image area is extracted from the line data, and various image processing such as image rearrangement processing is performed. The length of the effective image area in the line data varies depending on the reading conditions (color mode, monochrome mode, reading resolution). In many cases, the abnormal state occurs only in the invalid image area. When an abnormality occurs only in the invalid image area of the read line data, as disclosed in Patent Document 1, if the read line data is replaced with the previous line data, the normal line arrangement is disturbed, resulting in image degradation. It becomes the cause of.

  Therefore, the present invention replaces the image data of the line in which an abnormal signal is generated in the effective image signal of the image signal with the image data of another line, and an abnormal signal is generated outside the effective image signal. An image reading apparatus that does not replace image data is provided.

In order to solve the above problems, an image reading apparatus according to an embodiment of the present invention includes:
A light source that emits light for illuminating the document;
An image reading unit that receives reflected light from the image of the document and outputs an image signal and a line synchronization signal indicating a cycle of one line for each line along the main scanning direction;
A normal line synchronization signal generator that generates a normal line synchronization signal by removing the abnormal signal when the line synchronization signal includes an abnormal signal;
When the generation timing of the abnormal signal included in the line synchronization signal is within the effective image signal necessary for image formation in the image signal, an abnormal line position signal is output, and the generation timing of the abnormal signal is An abnormal line position signal generator that does not output the abnormal line position signal when it is outside the effective image signal;
An image data generation unit that generates image data for each line based on the image signal and the normal line synchronization signal, and replaces the image data of the line from which the abnormal line position signal is output with image data of another line;
Is provided.

  According to the present invention, the image data of the line in which an abnormal signal is generated in the effective image signal among the image signals is replaced with the image data of another line, and when an abnormal signal is generated outside the effective image signal. Does not replace image data. Thereby, normal effective image data can be used, and deterioration of the quality of the read image can be prevented.

1 is a block diagram of an image reading apparatus. FIG. 3 is a cross-sectional view of the image reading apparatus. The timing diagram of the abnormal line position signal produced | generated from an abnormal line synchronizing signal. Explanatory drawing of the replacement processing of image data. 6 is a flowchart showing an image reading operation. Explanatory drawing of the production | generation process of a mask signal and an effective image area signal. Explanatory drawing of the production | generation process of an abnormal line position signal. Explanatory drawing of the count operation | movement of the frequency | count of replacement of image data. The block diagram of an abnormal line position determination part. The flowchart which shows the production | generation operation | movement of an abnormal line position signal and a normal line synchronizing signal. The block diagram of an image data generation part. 5 is a flowchart showing an image data generation operation. 5 is a flowchart showing image data replacement processing operation. The timing diagram of a line memory selection signal, an abnormal line position signal, and an image data replacement signal.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

(Image reading device)
FIG. 2 is a cross-sectional view of the image reading apparatus 100. The image reading apparatus 100 includes a main body 10, an original table glass 203 disposed on the upper portion of the main body 10, and an image reading unit (image sensor unit) 103 that can move in the sub-scanning direction SD inside the main body 10. The image reading unit 103 is coupled to the drive belt 200. The drive belt 200 is wound around the drive gear 201 and the pulley 12. The drive gear 201 is rotated by the motor 105. When the motor 105 rotates forward or backward, the drive belt 200 rotates forward or backward via the drive gear 201 to reciprocate the image reading unit 103 in the sub-scanning direction SD. The white reference plate 204 is provided at one end of the document table glass 203 in the sub scanning direction SD. The image reading unit 103 reads an image of the document 202 placed on the document table glass 203 while moving in the sub scanning direction SD from the left to the right in FIG.

  FIG. 1 is a block diagram of the image reading apparatus 100. The image reading apparatus 100 includes a CPU (control unit) 106, an image reading unit 103, a motor driving unit 104, a motor 105, a light source 101, a light source driving unit 102, an image processing unit 107, a memory 108, and a controller (control unit) 109. . The image reading apparatus 100 further includes a PC connection unit 110, an operation unit 111, a printer interface (hereinafter referred to as I / F) 112, a facsimile I / F 113, and a hard disk drive (hereinafter referred to as HDD) 114.

  The image reading unit 103 includes a solid-state imaging device (hereinafter referred to as an image sensor) 115 and an AD conversion unit 116. The CPU 106 is electrically connected to the light source driving unit 102, the image reading unit 103, the motor driving unit 104, the image processing unit 107, and the controller 109. The CPU 106 controls the entire image reading apparatus 100. The CPU 106 generates various control signals for controlling at least the motor driving unit 104, the image reading unit 103, and the image processing unit 107, and performs data communication with them. The motor driving unit 104 controls the rotation of the motor 105 based on the timing signal generated by the CPU 106 and moves the image reading unit 103 in the sub scanning direction SD. The light source 101 serving as a light emitting unit includes a light emitting element such as a light emitting diode (LED) or a cold cathode tube. The light source driving unit 102 supplies a current to the light source 101 based on the timing signal generated by the CPU 106. The light source 101 is supplied with current from the light source driving unit 102 to emit light and illuminate the original.

  An image sensor 115 serving as a light receiving unit receives reflected light from a document illuminated by the light source 101. The image sensor 115 photoelectrically converts the reflected light based on the timing signal generated by the CPU 106 to generate an analog image signal. The image sensor 115 outputs an analog image signal to the AD converter 116. The AD conversion unit 116 performs analog processing such as sample hold processing, offset processing, and gain processing on the analog image signal. The AD converter 116 performs A / D conversion for converting the analog image signal subjected to the analog processing into a digital image signal. The AD conversion unit 116 outputs a line synchronization signal for obtaining one line period of the digital image signal together with the digital image signal to the image processing unit 107. The image processing unit 107 performs format conversion of the digital image signal for each line cycle, and generates image data having a predetermined arrangement similar to the image information of the document. The image data generated by the image processing unit 107 is temporarily stored in the memory (storage unit) 108. The memory 108 transfers the image data to the controller 109.

  The controller 109 is electrically connected to the CPU 106, memory 108, PC connection unit 110, operation unit 111, printer I / F 112, facsimile I / F 113, and HDD 114. The controller 109 performs predetermined processing on the image data received from the memory 108. The controller 109 stores image data that has undergone predetermined processing in an HDD (storage unit) 114. Thereafter, the image data stored in the HDD 114 is transferred to the printer via the printer I / F 112 or to the facsimile apparatus via the facsimile I / F 113. The PC connection unit 110 is an interface such as USB, Ethernet, IEEE 1394, or IEEE 1298 that connects the personal computer (PC) and the image reading apparatus 100. The operation unit 111 is a user interface having a display (display unit) and input buttons. The user inputs information such as a copy start instruction to the image reading apparatus 100 by pressing an input button or a touch pad displayed on the display.

  The image processing unit 107 includes a format conversion unit 117, an abnormal line position determination unit 118, and an image data generation unit 119. The image processing unit 107 includes a dedicated circuit such as an application specific integrated circuit (ASIC) or a programmable gate array (field programmable gate array). The CPU 106 performs various settings for the image processing unit 107 and causes the image processing unit 107 to perform an image processing operation. The format conversion unit 117 receives the digital image signal AD-converted by the AD conversion unit 116. The digital image signal is input from the AD conversion unit 116 to the format conversion unit 117 as a differential signal, for example. The format conversion unit 117 performs format conversion such as serial-parallel conversion on the digital image signal. The format converter 117 also extracts a line synchronization signal for determining one line cycle of the digital image signal from the digital image signal converted into the parallel signal.

  The abnormal line position determination unit 118 includes a counter 120. The counter 120 counts the cycle of the line synchronization signal output from the format conversion unit 117. If the counted cycle is not a predetermined cycle of the line synchronization signal, the abnormal line position determination unit 118 outputs an abnormal line position signal indicating that the signal output from the format conversion unit 117 is an abnormal signal to the image data generation unit. It outputs to 119. The format conversion unit 117 outputs the digital image signal for one line subjected to the format conversion to the image data generation unit 119. The image data generation unit 119 generates image data from the digital image signal for one line whose format has been converted, and stores the image data in the memory 108. An image data generation unit 119 as an image data rearrangement unit reads out the image data stored in the memory 108 and rearranges it to generate image data having a predetermined arrangement. The image data generation unit 119 finally generates image data having a predetermined arrangement similar to the read document image.

(Processing of abnormal line position determination unit)
Next, the generation operation of the abnormal line position signal 27 executed by the abnormal line position determination unit 118 will be described. FIG. 3 is a timing diagram of the abnormal line position signal 27 generated from the abnormal line synchronization signal 21. When there is no external factor such as electrostatic noise, the format conversion unit 117 outputs a predetermined line synchronization signal 20 to the abnormal line position determination unit 118. However, when an external factor such as electrostatic noise occurs, the format conversion unit 117 outputs an abnormal line synchronization signal 21. Therefore, as shown in FIG. 3, the abnormal line position determination unit 118 generates a mask signal 22 having a width W (hereinafter referred to as a mask region) shorter than a cycle (one line cycle) T of a predetermined line synchronization signal 20; Mask processing is performed on the abnormal line synchronization signal 21.

  The mask signal 22 is generated by the method described below. First, the counter 120 starts counting on the basis of the line synchronization signal 21a input first. The counter 120 counts up to a mask section setting count value (hereinafter referred to as a mask setting value) set by the CPU 106. When the count value of the counter 120 reaches the mask setting value, the count value of the counter 120 is cleared to ‘0’. The abnormal line position determination unit 118 generates a mask signal 22 in which the count operation section (a section where the count value is not “0”) of the counter 120 is used as a mask area (mask section) W. The abnormal line position determination unit 118 generates the line synchronization signals (abnormal signals) 21b and 21c input within the mask region W of the mask signal 22 as the pre-abnormal line position signal 24. The pre-abnormal line position signal 24 may be an inverted signal or a non-inverted signal of the line synchronization signals 21b and 21c input in the mask region W.

  The predetermined line synchronization signal 20 is input from the AD converter 116 to the format converter 117 together with the digital image signal 26. Accordingly, an abnormality that occurs in the input line synchronization signal 21 also occurs in the digital image signal 26 in the same manner, and the position of the abnormality that occurs in the line synchronization signal 21 is the same as the position of the abnormality that occurs in the digital image signal 26. It is. As shown in FIG. 3, the digital image signal 26 includes an effective image signal 26 a necessary for image formation and an invalid image signal 26 b unnecessary for image formation during one line period T. The effective image area 25a where the effective image signal 26a is provided and the invalid image area 25b where the invalid image signal 26b is provided are set based on the color mode, monochrome mode and reading resolution set by the user via the operation unit 111. The CPU 106 sets an area setting count value (hereinafter referred to as an area setting value) for setting the effective image area 25 a and the invalid image area 25 b in the abnormal line position determination unit 118 based on the information set by the operation unit 111. . The abnormal line position determination unit 118 generates an effective image area signal 25 based on the area setting value set by the CPU 106. The valid image area signal 25 is an invalid image area 25a in which the count value of the counter 120 is from “0” to the area set value (for example, the signal value in that section is “0”), and the count value is larger than the area set value. And an image area (for example, the signal value of the section is “1”) 25b.

  The abnormal line position determination unit 118 compares the pre-abnormal line position signal 24 with the effective image area signal 25, and determines whether or not the pre-abnormal line position signals 24a and 24b are in the effective image area 25a. The abnormal line position determination unit 118 invalidates (removes) the pre-abnormal line position signal 24b in the invalid image area 25b. This is because the abnormality corresponding to the pre-abnormal line position signal 24b is not an abnormality in the effective image signal. When the pre-abnormal line position signal 24a is present in the effective image area 25a, the pre-abnormal line position signal 24a is output to the image data generation unit 119 as the abnormal line position signal 27. This is because the abnormality corresponding to the pre-abnormal line position signal 24a is an abnormality in the effective image signal 26a. Further, the abnormal line position determination unit 118 invalidates (removes) the line synchronization signals 21b and 21c generated in the mask region W among the line synchronization signals 21a, 21b, and 21c, and generates a normal line synchronization signal 23. .

(Processing of image data generator)
Next, image data replacement processing executed by the image data generation unit 119 will be described. The image data generation unit 119 generates image data for each line based on the digital image signal 26 and the normal line synchronization signal 23, and uses the image data of the line from which the abnormal line position signal 27 is output as the image data of other lines. Replace with. In this embodiment, the image data generation unit 119 replaces the image data of the line from which the abnormal line position signal 27 is output with the image data of the previous line. Note that the image data of the line from which the abnormal line position signal 27 is output may be replaced with the image data of the next line. FIG. 4 is an explanatory diagram of image data replacement processing. The abnormal line position determination unit 118 inputs the normal line synchronization signal 23 and the abnormal line position signal 27 to the image data generation unit 119. The format converter 117 inputs the format-converted digital image signal 26 to the image data generator 119. The image data generation unit 119 generates image data 28 from the digital image signal 26 for one line for each normal line synchronization signal 23. The image data generation unit 119 rearranges the image data 28 for one line for each pixel so as to have an arrangement similar to the image information of the read original. The image data generation unit 119 stores the image data for one line subjected to the rearrangement process in the memory 108. The memory 108 has at least two line memories (line memory A and line memory B). The image data generation unit 119 stores image data for one line alternately in the line memory A and the line memory B sequentially unless the abnormal line position signal 27 is input. The image data generation unit 119 reads the image data of the previous line from the line memory B while the image data of the current line is stored in the line memory A. Similarly, the image data generation unit 119 reads the image data of the previous line from the line memory A while storing the image data of the current line in the line memory B.

  As shown in FIG. 4, when the abnormal line position signal 27 is input while the N + 1 line image data is being stored in the line memory B, the image data generation unit 119 converts the current N + 1 line image data to the previous N lines. Replace with image data. Specifically, the image data generation unit 119 reads the image data of the previous N lines from the line memory A without reading the image data of N + 1 lines from the line memory B. Then, the image data generating unit 119 stores the next N + 2 line image data in the line memory B while reading the previous N line image data from the line memory A. As described above, the image data generation unit 119 replaces the image data of the line corresponding to the abnormal line position signal 27 with the image data of the previous line. Further, the image data generation unit 119 has a function of counting the number of replacements of image data. If the number of replacements of the image data occurs continuously for the set number of times or more set by the CPU 106, the CPU 106 displays an error on the display of the operation unit 111.

(Image reading operation)
Next, an image reading operation executed by the CPU 106 will be described. FIG. 5 is a flowchart showing the image reading operation. The CPU 106 executes an image reading operation according to a program stored in the ROM 121. The user operates the operation unit 111 to instruct the start of the image reading operation. An instruction to start an image reading operation is input to the CPU 106 via the controller 109. The CPU 106 starts an image reading operation. The CPU 106 drives the image reading unit 103 (S51). The CPU 106 controls the light source driving unit 102 to turn on the light source 101. The CPU 106 drives the image sensor 115 of the image reading unit 103 so that the document can be read. The CPU 106 controls the motor driving unit 104 to drive the motor 105 (S52). As the motor 105 rotates, the image reading unit 103 is moved in the sub-scanning direction SD. When the image reading apparatus 100 is provided with an automatic document feeding device, the image reading unit 103 may be stopped at the reading position and the document may be conveyed.

  The image sensor 115 reads an image line by line along the main scanning direction orthogonal to the sub-scanning direction SD, and outputs an analog image signal to the AD conversion unit 116 (S53). The AD converter 116 converts the analog image signal into a digital image signal (S53). The AD conversion unit 116 outputs a serial digital image signal together with the line synchronization signal to the image processing unit 107 as a differential signal. The format converter 117 converts the serial digital image signal from the AD converter 116 into a parallel digital image signal (S54). Further, the abnormal line position determination unit 118 generates an abnormal line position signal 27 and a normal line synchronization signal 23 from the input line synchronization signal 21 (S54). The format conversion unit 117 also outputs a parallel digital image signal to the image data generation unit 119.

  The abnormal line position determination unit 118 generates the mask signal 22 of the mask area W of the line synchronization signal 21 based on the mask setting value set by the CPU 106 (S55). Further, the abnormal line position determination unit 118 generates an effective image region signal 25 having an effective image region 25a for determining the effective image signal 26a of the digital image signal 26 based on the region setting value set by the CPU 106 ( S55).

  FIG. 6 is an explanatory diagram of the generation process of the mask signal 22 and the effective image area signal 25. As shown in FIG. 6, the mask signal 22 and the effective image area signal 25 are generated based on the count value of the counter 120 and the mask setting value and area setting value set by the CPU 106. The counter 120 starts counting when the line synchronization signal 21 is input. For example, when the mask setting value set by the CPU 106 is 7499, the value of the mask signal 22 becomes “0” according to the count start of the counter 120, and becomes “1” when the count value of the counter 120 reaches 7499. become. When the count value of the counter 120 reaches 7499, it is cleared to ‘0’. The counter 120 starts counting again when the next line synchronization signal 21 is input. Further, for example, when the area setting value set by the CPU 106 is 7200, the value of the effective image area signal 25 becomes “0” when the counter 120 starts counting, and the count value of the counter 120 reaches 7200. Then it becomes '1'. The counter 120 counts one for each pixel.

  The abnormal line position determination unit 118 generates an abnormal line position signal 27 (S55). FIG. 7 is an explanatory diagram of the generation process of the abnormal line position signal 27. The generation process of the abnormal line position signal 27 depends on the reading conditions (color mode, monochrome mode, reading resolution) set by the user from the operation unit 111. In accordance with the reading conditions set by the user from the operation unit 111, the CPU 106 sets area setting values in the image processing unit 107. FIG. 7A is an explanatory diagram of the generation process of the abnormal line position signal 27 when the effective image area 25a is 7200 pixels. One line length of the predetermined line synchronization signal 20 is set to 7500 pixels. The mask area W is set to 7499 pixels. The counter 120 starts counting based on the line synchronization signal 21a input first. The line synchronization signals 21b and 21c generated in the mask area W until the count value of the counter 120 reaches 7499 are masked. Note that the mask setting value is always set to a value smaller than one line length of the predetermined line synchronization signal 20. The effective image area 25a is set to 7200 pixels. The invalid image area 25b is 300 pixels. The abnormal line position determination unit 118 generates the line synchronization signal 21b generated in the effective image area 25a as the abnormal line position signal 27. The line synchronization signal 21c generated in the invalid image area 25b is not generated as an abnormal line position signal. The abnormal line position determination unit 118 generates a normal line synchronization signal 23 excluding the line synchronization signals 21b and 21c generated in the mask region W (S55). The abnormal line position determination unit 118 outputs the normal line synchronization signal 23 and the abnormal line position signal 27 to the image data generation unit 119.

  FIG. 7B is an explanatory diagram of the generation process of the abnormal line position signal 27 when the effective image area 25a is 2400 pixels. For example, when the reading condition is set to the monochrome mode, the effective image area 25a is set to 2400 pixels as shown in FIG. The invalid image area 25b is 5100 pixels. The abnormal line position determination unit 118 does not generate the abnormal line position signal 27 because the line synchronization signal 21 is not generated in the effective image area 25a. The abnormal line position determination unit 118 invalidates (removes) the line synchronization signals 21b, 21c, and 21d generated in the invalid image area 25b, and does not generate the abnormal line position signal 27. The abnormal line position determination unit 118 generates a normal line synchronization signal 23 excluding the line synchronization signals 21b, 21c, and 21d generated in the mask region W (S55). The abnormal line position determination unit 118 outputs the normal line synchronization signal 23 and the abnormal line position signal 27 to the image data generation unit 119.

  The image data generation unit 119 generates image data based on the digital image signal for one line sequentially input from the format conversion unit 117, and stores it in the memory 108 (S56). The image data generation unit 119 rearranges the image data for one line for each pixel so that the arrangement is the same as that of the read document image. As described above, the memory 108 includes the line memory A and the line memory B. When the abnormal line position signal 27 is not input, the image data generation unit 119 reads the image data from the line memory B while storing the image data in the line memory A, and stores the image data in the line memory B. In the meantime, image data is read from the line memory A. The image data generation unit 119 sequentially repeats the process of storing and reading image data in the line memories A and B.

  When the abnormal line position signal 27 is input, the image data generation unit 119 performs the operation described with reference to FIG. For example, when the abnormal line position signal 27 is input while the image data of the (N + 1) th line is stored in the line memory B, the image data of the (N + 1) th line stored in the line memory B is discarded. Then, the image data generation unit 119 reads the Nth line image data stored in the line memory A instead of the N + 1th line image data, and converts the N + 1th line image data into the Nth line image data. replace. The image data generation unit 119 stores the image data of the (N + 2) th line in the line memory B while reading the image data of the Nth line from the line memory A. By this operation, the image data of the line where the abnormality has occurred is replaced with the image data of the previous line having no abnormality. Thereafter, unless the abnormal line position signal 27 is inputted, the image data is sequentially stored in the line memory A → the line memory B → the line memory A... And the corresponding line memory B → the line memory A → the line memory B sequentially. Read image data from. The image data generation unit 119 repeats the above operation until reading of all image data is completed.

  The image data generation unit 119 has a function of counting the number of times image data replacement processing has been executed. FIG. 8 is an explanatory diagram of the operation of counting the number of replacements of image data. The CPU 106 presets the number of times that the image data is continuously replaced in the image data generation unit 119 as a number setting value. In this embodiment, the number of times setting value is 4. However, the number-of-times setting value is not limited to 4, and may be set to any numerical value such as 3, 5, or 6. The image data generation unit 119 counts the number of times that the image data is continuously replaced. When the image data is not replaced, the count value of the number of replacements is reset to “0”. The CPU 106 determines whether or not the number of times that the image data is continuously replaced is smaller than the number of times setting value (S57). If the number of times image data has been replaced continuously is equal to or greater than the number setting value (four times) (NO in S57), CPU 106 stops the replacement process and document reading operation, and displays error information on operation unit 111. (S58). If the number of times the image data is continuously replaced is smaller than the set number of times (YES in S57), the CPU 106 determines whether the image data of the last line of the document has been read (S59). If the image of the last line has not been read (NO in S59), the process returns to S54, and image data for the next line is generated. When the image data of the last line has been read (YES in S59), the CPU 106 ends the document reading operation.

(Abnormal line position signal and normal line synchronization signal generation operations)
An operation in which the abnormal line position determination unit 118 generates the mask signal 22, the effective image area signal 25, the abnormal line position signal 27, and the normal line synchronization signal 23 in S55 will be described with reference to FIGS. FIG. 9 is a block diagram of the abnormal line position determination unit 118. The abnormal line position determination unit 118 includes a counter 120, a mask signal generation unit 1401, an effective image region signal generation unit 1402, an abnormal line position signal generation unit 1403, and a normal line synchronization signal generation unit 1404. FIG. 10 is a flowchart showing an operation of generating the abnormal line position signal 27 and the normal line synchronization signal 23. When the generation operation of the abnormal line position signal 27 and the normal line synchronization signal 23 is started, the CPU 106 sets a mask setting value and a region setting value in the abnormal line position determination unit 118 (S101). The line synchronization signal 21 from the format conversion unit 117 is input to the counter 120, the mask signal generation unit 1401, the effective image region signal generation unit 1402, the abnormal line position signal generation unit 1403, and the normal line synchronization signal generation unit 1404. When the line synchronization signal 21 is input (S102), the counter 120 starts a count operation for incrementing one pixel at a time based on the falling edge of the line synchronization signal 21 (S103). The counter 120 counts the number of pixels for one line. In this embodiment, the line synchronization signal 21 is negative logic (low active) with a width of one pixel. Negative logic (low active) is a logic structure in which the voltage level is 1 when the voltage level is low and 0 when the voltage level is high. However, the line synchronization signal 21 may be positive logic (high active). In that case, the counter 120 starts the counting operation with reference to the rise of the line synchronization signal. The count value of the counter 120 is input to the mask signal generation unit 1401 and the effective image area signal generation unit 1402.

  The mask signal generation unit 1401 starts generating the mask signal 22 having the mask region W at the rising edge of the line synchronization signal 21 (S104). The mask signal 22 is set to “1” representing the mask region W. At the same time, the effective image area signal generation unit 1402 starts generating the effective image area signal 25 having the effective image area 25a at the rising edge of the line synchronization signal 21 (S104). The effective image area signal 25 is set to “1” representing the effective image area 25a. In this embodiment, the mask signal 22 and the effective image area signal 25 are negative logic (low active), but may be positive logic (high active). The mask signal generation unit 1401 outputs the mask signal 22 to the abnormal line position signal generation unit 1403 and the normal line synchronization signal generation unit 1404. The effective image region signal generation unit 1402 outputs the effective image region signal 25 to the abnormal line position signal generation unit 1403 and the normal line synchronization signal generation unit 1404.

  The abnormal line position signal generation unit 1403 and the normal line synchronization signal generation unit 1404 determine whether or not the line synchronization signal 21 is input (S105). When the line synchronization signal 21 is not input (NO in S105), the effective image area signal generation unit 1402 determines whether or not the count value of the counter 120 has reached the area setting value (S106). If the count value has not reached the region setting value (NO in S106), the effective image region signal 25 remains “1” representing the effective image region 25a, and the process returns to S105. The abnormal line position signal generation unit 1403 and the normal line synchronization signal generation unit 1404 determine whether or not the line synchronization signal 21 is input again (S105). When the line synchronization signal 21 is input (YES in S105), the line synchronization signal 21 is within the mask area W (mask signal = '1') and within the effective image area 25a (effective image area signal = '1'). Indicates that an abnormality has occurred. The abnormal line position signal generation unit 1403 calculates a negative logical product (NAND) of the mask signal 22 and the line synchronization signal 21 and generates an abnormal line position signal 27 (S107). That is, the abnormal line position signal generation unit 1403 generates an abnormal signal included in the line synchronization signal 21 (21b in FIG. 7A) within the effective image signal 26a necessary for image formation in the digital image signal 26. If there is, the abnormal line position signal 27 is output. The abnormal line position signal 27 is positive logic (high active). The normal line synchronization signal generation unit 1404 performs normal line synchronization in which the abnormal line position signal 27 is excluded by OR processing of the line synchronization signal 21 in the mask area W (mask signal = '1') and the generated abnormal line position signal 27. A signal 23 is generated (S107). The process proceeds to S106.

  When the count value reaches the region setting value (YES in S106), the valid image region signal generation unit 1402 represents the value of the valid image region signal 25 from '1' representing the valid image region 25a to the invalid image region 25b. Switching to “0”, the effective image area 25a is terminated (S108). Thereafter, the valid image area signal 25 is maintained at ‘0’ representing the invalid image area 25b. The abnormal line position signal generation unit 1403 and the normal line synchronization signal generation unit 1404 determine whether or not the line synchronization signal 21 is input (S109). When the line synchronization signal 21 is not input (NO in S109), the mask signal generation unit 1401 determines whether or not the count value of the counter 120 has reached the mask setting value (S110). When the count value does not reach the mask setting value (NO in S110), the mask signal 22 remains “1” indicating the mask area W, and the process returns to S109. The abnormal line position signal generation unit 1403 and the normal line synchronization signal generation unit 1404 determine whether the line synchronization signal 21 is input again (S109). When the line synchronization signal 21 is input (YES in S109), the line synchronization signal 21 is in the mask area W (mask signal = '1') and in the invalid image area 25b (effective image area signal = '0'). Indicates that an abnormality has occurred. The abnormal line position signal generation unit 1403 receives the line synchronization signal 21 (abnormal signal) in the invalid image area 25b (effective image area signal = '0') and in the mask area W (mask signal = '1'). Even if it does, the abnormal line position signal 27 is not generated. That is, the abnormal line position signal generation unit 1403 generates an abnormal signal of the line synchronization signal 21 (21c in FIG. 7A, 21b, 21c, and 21d in FIG. 7B) outside the effective image signal 26a. The abnormal line position signal 27 is not output when At this time, the normal line synchronization signal generator 1404 removes the input line synchronization signal 21 (abnormal signal) and generates a normal line synchronization signal 23 (S111).

  The generation of the normal line synchronization signal 23 is the same as the processing described in S107. However, in S111, the abnormal line position signal 27 is not generated, and only the normal line synchronization signal 23 is generated. The mask signal generation unit 1401 determines whether or not the count value of the counter 120 has reached the mask setting value (S110). The process returns to S109 until the count value of the counter 120 reaches the mask setting value, and the invalid image area 25b (effective image area signal = “0”) and the mask area W (mask signal = “1”) continue. When the count value reaches the mask setting value (YES in S110), the mask signal generation unit 1401 switches the value of the mask signal 22 from “1” representing the mask area W to “0” representing the non-mask area. The area W is terminated (S112). The CPU 106 clears the count value of the counter 120 to “0” (S113). The abnormal line position determination unit 118 determines whether or not the line synchronization signal 21 is input (S114). When the line synchronization signal is input (YES in S114), the process returns to S103, and the counter 120 starts counting the number of pixels in the next line. The CPU 106 generates the abnormal line position signal 27 and the normal line synchronization signal 23 for the next line. If the line synchronization signal 21 is not input in S114 (NO in S114), the CPU 106 ends the generation operation of the abnormal line position signal 27 and the normal line synchronization signal 23. In this way, the processing of the abnormal line position determination unit 118 in S55 generates the abnormal line position signal 27 and the normal line synchronization signal 23 based on the input line synchronization signal 21 by a series of operations of S101 to S114. To do.

(Image data replacement process)
The abnormal line position signal 27 and the normal line synchronization signal 23 generated by the abnormal line position determination unit 118 are input to the image data generation unit 119. The digital image signal 26 whose format has been converted by the format converter 117 is input to the image data generator 119. The image data generation unit 119 executes image data generation and image data replacement processing for each line based on the digital image signal 26, the abnormal line position signal 27, and the normal line synchronization signal 23. The operation in which the image data generation unit 119 replaces the image data in S56 will be described with reference to FIGS. 11, 12, 13, and 14. FIG.

  FIG. 11 is a block diagram of the image data generation unit 119. The image data generation unit 119 includes a line counter 1501, a line memory selection unit 1502, an image data replacement signal generation unit 1503, a replacement counter 1504, and a line memory interface 1505. FIG. 12 is a flowchart showing the image data generation operation. When the image data generation operation is started, the digital image signal 26, the abnormal line position signal 27, and the normal line synchronization signal 23 are input to the image data generation unit 119 (S121). The digital image signal 26 is input to the line memory interface 1505. The abnormal line position signal 27 is input to the line memory selection unit 1502 and the image data replacement signal generation unit 1503. The normal line synchronization signal 23 is input to the line counter 1501, the line memory selection unit 1502, the image data replacement signal generation unit 1503, and the replacement counter 1504.

  The line counter 1501 counts the number of lines based on the normal line synchronization signal 23. The line counter 1501 starts counting on the basis of the normal falling edge of the line synchronization signal 23. The value of the line counter 1501 is “1” (first line). The value of the line counter 1501 is incremented by 1 every time a normal line synchronization signal 23 is input. When all the lines have been read, the value of the line counter 1501 is cleared to ‘0’. The line count value 30 of the line counter 1501 is input to the line memory selection unit 1502, the image data replacement signal generation unit 1503, and the line memory interface 1505. The image data generation unit 119 generates image data based on the digital image signal 26 of the first line. The image data generation unit 119 stores the image data of the first line in the line memory B. The CPU 106 determines whether or not the value of the line counter 1501 is “2” (second line) (S122). When the count value of the line counter 1501 becomes “2” (YES in S122), the CPU 106 enables the image data replacement function and starts the image data replacement process (S123). The CPU 106 executes image data replacement processing (S124).

  Hereinafter, the image data replacement processing in S124 will be described with reference to FIG. FIG. 13 is a flowchart showing the image data replacement processing operation. The digital image signal 26, the normal line synchronization signal 23, and the abnormal line position signal 27 are sequentially input to the image data generation unit 119 (S131). The line memory interface 1505 generates image data for the Nth line based on the digital image signal 26 for the Nth line (S132). The line memory interface 1505 stores the image data of the Nth line in the line memory A (S133). The line memory interface 1505 reads the image data of the (N−1) th line from the line memory B (S134). The image data replacement process is started from the second line, and the image data of the first line is stored in the line memory B.

  The line memory selection unit 1502 generates a line memory selection signal 31 for selecting a line memory for storing and reading image data (S135). The line memory selection signal 31 is input to the line memory interface 1505. The line memory interface 1505 sets the line memory B as the line memory X and the line memory A as the line memory Y based on the line memory selection signal 31. FIG. 14 is a timing chart of the line memory selection signal 31, the abnormal line position signal 27, and the image data replacement signal 32. The line memory selection unit 1502 generates a 1-bit line memory selection signal 31 that transitions at the falling edge of the normal line synchronization signal 23 as shown in FIG. The line memory selection signal 31 does not transition at the falling edge of the current line synchronization signal 23 when an abnormal state has occurred in the previous line. At this time, the line memory interface 1505 selects the same line memory as that in the previous line as the line memory to be stored and the line memory to be read out.

  The line memory interface 1505 generates image data of the (N + 1) th line based on the digital image signal 26 of the (N + 1) th line (S136). The line memory selection unit 1502 and the image data replacement signal generation unit 1503 determine whether or not the abnormal line position signal 27 is input to the Nth line (S137). As shown in FIG. 14, the abnormal line position signal 27 is positive logic (high active). When the abnormal line position signal 27 (= '1') is input to the Nth line (YES in S137), the image data replacement signal generation unit 1503 displays the image data replacement signal 32 indicating that there is an abnormality in the Nth line. Is generated (S138). The image data replacement signal 32 is a 1-bit signal that transitions at the falling edge of the normal line synchronization signal 23, and its initial value is “0”. When the abnormal line position signal 27 (= '1') is input to the Nth line (YES in S137), the image data replacement signal 32 is the rising edge of the normal line synchronization signal 23 of the next line (N + 1th line). It goes down to '1'. When the abnormal line position signal 27 is not input to the (N + 1) th line (abnormal line position signal 27 = '0'), the image data replacement signal 32 is the normal line synchronization signal 23 of the next line (N + 2th line). It becomes '0' at the falling edge. The image data replacement signal generation unit 1503 outputs the image data replacement signal 32 to the replacement counter 1504 and the line memory interface 1505 on the (N + 1) th line.

  When the abnormal line position signal 27 (= '1') is not input to the Nth line (NO in S137), the image data replacement signal generation unit 1503 does not output the image data replacement signal 32 (image data replacement signal = '0). '). The line memory interface 1505 stores the image data of the (N + 1) th line in the line memory X (X = B) (S139). The line memory interface 1505 reads the image data of the Nth line from the line memory Y (Y = A) (S140). When the abnormal line position signal 27 (= '1') is input to the Nth line (YES in S137), the line memory interface 1505 stores the image data of the (N + 1) th line in the line memory Y (Y = A). (S141). The line memory interface 1505 reads the image data of the (N-1) th line from the line memory X (X = B), and replaces the image data of the Nth line with the image data of the (N-1) th line (S142). By this processing, the image data of the line where the abnormality has occurred is replaced with the image data of the previous line. When the abnormal line position signal 27 (= '1') is input to the Nth line (YES in S137), the line memory selection signal 31 output from the line memory selection unit 1502 is the next line (N + 1th line). Does not make a transition. Accordingly, the line memory interface 1505 stores the image data of the (N + 1) th line in the same line memory A as the previous line (Nth line), and the N-1th line from the same line memory B as the previous line (Nth line). Image data is read out.

  The replacement counter 1504 counts the number of times the image data is continuously replaced based on the image data replacement signal 32 (S143). When the image data replacement signal 32 is ‘1’ at the rising edge of the normal line synchronization signal 23, the replacement counter 1504 increases the count value by one. When the image data replacement signal 32 is ‘0’ at the rising edge of the normal line synchronization signal 23, the replacement counter 1504 clears the count value to ‘0’. The replacement counter 1504 determines whether or not the count value (number of consecutive replacements) is equal to or greater than the number of times set initially set by the CPU 106 (S144). If the count value is equal to or greater than the set number of times (YES in S144), the replacement counter 1504 outputs an error signal to the CPU. Upon receiving the error signal, the CPU 106 displays an error on the display of the operation unit 111 (S145). The CPU 106 ends the image data replacement processing operation and the image data generation operation.

  If the count value is smaller than the set number of times (NO in S144), the CPU 106 determines whether or not reading of the image data for all lines has been completed based on the line count value 30 of the line counter 1501 (S146). When reading of the image data of all lines is completed (YES in S146), the CPU 106 ends the image data replacement processing operation and the image data generation operation. If reading of the image data of all lines has not been completed (NO in S146), the CPU 106 determines whether or not the image data of the line where the abnormality has occurred has been replaced with the image data of the previous line (S147). Specifically, when the image data replacement signal 32 is “1”, the image data of the line where the abnormality has occurred is replaced with the image data of the previous line (YES in S147). Since the image data of the (N + 1) th line is stored in the line memory A (S141), and the image data of the (N-1) th line is read from the line memory B (S142), the process returns to S135, and is stored and read out. Switch the line memory. The line memory selection unit 1502 stores the image data in the line memory B (X = B), and generates the line memory selection signal 31 so as to read the image data from the line memory A (Y = A) (S135). On the other hand, when the image data replacement signal 32 is “0”, no abnormality has occurred in the Nth line, and therefore, replacement of image data in units of lines has not been performed (NO in S147). In order to switch between saving and reading line memories, the line memory selection unit 1502 saves the image data in the line memory A (X = A), and reads the image data from the line memory B (Y = B). The selection signal 31 is generated (S148). A series of image data replacement processing is executed by the operations of S131 to S148.

  According to the present embodiment, the image data of the line in which an abnormality has occurred in the effective image signal 26a in the digital image signal 26 is replaced with the image data of another line, and when an abnormality has occurred in the invalid image signal 26b, the image is displayed. Do not replace data. Thereby, normal effective image data can be used, and deterioration of the quality of the read image can be prevented.

21 ... Line synchronization signal 21b, 21c ... Line synchronization signal (abnormal signal)
DESCRIPTION OF SYMBOLS 23 ... Normal line synchronizing signal 26 ... Digital image signal 26a ... Effective image signal 27 ... Abnormal line position signal 100 ... Image reading apparatus 101 ... Light source 103 ... Image reading part 119: Image data generation unit 1403: Abnormal line position signal generation unit 1404: Normal line synchronization signal generation unit

Claims (8)

A light source that emits light for illuminating the document;
An image reading unit that receives reflected light from the image of the document and outputs an image signal and a line synchronization signal indicating a cycle of one line for each line along the main scanning direction;
A normal line synchronization signal generator that generates a normal line synchronization signal by removing the abnormal signal when the line synchronization signal includes an abnormal signal;
When the generation timing of the abnormal signal included in the line synchronization signal is within the effective image signal necessary for image formation in the image signal, an abnormal line position signal is output, and the generation timing of the abnormal signal is An abnormal line position signal generator that does not output the abnormal line position signal when it is outside the effective image signal;
An image data generation unit that generates image data for each line based on the image signal and the normal line synchronization signal, and replaces the image data of the line from which the abnormal line position signal is output with image data of another line;
An image reading apparatus comprising:   The image reading apparatus according to claim 1, wherein the other line is image data of a line immediately preceding the line from which the abnormal line position signal is output.   The apparatus further comprises an effective image area signal generation unit that generates an effective image area signal having the effective image area based on an area setting value for setting an effective image area in which the effective image signal is provided. The image reading apparatus according to 1 or 2. Further equipped with an operation unit operated by the user,
The image reading apparatus according to claim 3, wherein the area setting value is set based on a reading condition input from the operation unit.   The apparatus further comprises a mask signal generation unit that generates a mask signal having a mask region for removing the abnormal signal from the line synchronization signal to generate the normal line synchronization signal. The image reading apparatus according to any one of 1 to 4.   6. The image reading apparatus according to claim 1, further comprising at least two line memories that store image data for each line generated by the image data generation unit.   The image reading apparatus according to claim 6, further comprising a line memory selection unit that switches between storing and reading image data for each line in the at least two line memories. A replacement counter that counts the number of times the image data of the line from which the abnormal line position signal is output is replaced with image data of another line;
8. The image reading apparatus according to claim 1, wherein the replacement counter outputs an error signal for displaying an error on a display unit when the count value reaches a set number of times.

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