JPH0897980A - Method and device for adjusting image reader - Google Patents

Abstract

PURPOSE: To reduce dispersion in the adjustment when an output timing of image data is adjusted so as not to cause deviation in the read image resulting from position deviation of each line sensor in the image reader having plural line sensors arranged in zigzag. CONSTITUTION: Line sensors 31-33 of the image reader read an original on which a straight line target is described and picture element data representing a read image of each part of the straight line target by each line sensor are acquired and a regression line of picture element groups corresponding to the picture element data is obtained, a relative position deviation in a direction of each regression line corresponding to the original feed direction is obtained and a setting value of a delay of line memories 61-63 delaying a read image of the line sensors 31-33 is decided based on the position deviation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus for reading an image from a document by a plurality of line sensors arranged in a staggered manner, and more particularly to a method for adjusting the output timing of each image data obtained from each line sensor. Regarding the device.

[0002]

2. Description of the Related Art In a copying machine or the like, a line sensor in which a large number of light detecting sensors are linearly arranged is used as a means for reading an image displayed on the surface of a document. That is, in a copying machine or the like, an original is fed at a constant speed in a direction traversing the longitudinal direction of the line sensor, and while the original is fed, the output signals of the respective light detecting sensors constituting the line sensor are sequentially scanned. The / D conversion process is repeated to obtain pixel data representing an image on the document surface.

In order to read a manuscript of a certain size in a copying machine, it is necessary to use a line sensor having a length corresponding to it. However,
Since there is a manufacturing limit even if the length of the line sensor is increased, it is common in a copying machine to connect a plurality of line sensors to form one long line sensor. When using a plurality of line sensors in this way, it is necessary to accurately position each line sensor so that each line sensor is accurately aligned. However, it is generally difficult to arrange the line sensors completely in a straight line, and the line sensors are slightly displaced from each other along the document feeding direction, that is, in a staggered arrangement. Will be done.

When the originals are read by the run sensors arranged in a zigzag manner as described above, the images read by the line sensors are also displaced along the original feeding direction (sub-scanning direction). In order to accurately reproduce the image of the original, the relative positional deviation between the line sensors in the sub-scanning direction is obtained, and the image read by each line sensor is shifted in the sub-scanning direction by the amount of this relative positional deviation. Correction operation becomes necessary. There have been the following two types of correction operation methods that have been conventionally performed.

<Method 1> Relative positional deviation between line sensors in the sub-scanning direction is compensated by adjusting the output timing of image data obtained from each line sensor.
In order to compensate for this, when the arrangement of each line sensor is completed, the joint between the line sensors is observed with a microscope, and the relative positional deviation amount of each line sensor in the sub-scanning direction is visually determined. Then, the delay amount of the delay device inserted in advance after each line sensor is set so as to compensate for this positional deviation amount.

<Method 2> This method also basically adjusts the output timing of the image data obtained from each line sensor to compensate for the relative positional deviation in the sub-scanning direction between the line sensors. However, in carrying out this method, as shown in FIG. 10A, the monitor B for displaying the read image is connected to the image reading apparatus A. Then, the correction operation is performed according to the flow shown in FIG.

First, the image reading apparatus A is caused to read a document in which one straight line (hereinafter referred to as a straight line target) is drawn in a direction orthogonal to the document feeding direction (step Sa).
1). Next, the image of the linear target obtained by this reading is confirmed by the monitor B (step Sa2).

FIG. 10C shows an example of a read image of a linear target. In this figure, an arrow X indicates a main scanning direction which is a line sensor arrangement direction (direction orthogonal to the document feeding direction), and an arrow Y indicates a sub scanning direction orthogonal thereto (direction corresponding to the document feeding direction). Is shown. If there is no displacement in each line sensor, one straight line image will be displayed on the monitor B.
As shown in (c), a deviation in the sub-scanning direction corresponding to the positional deviation of each line sensor occurs between the images read by each line sensor. In this step Sa2, the read image by each line sensor projected on the monitor B is confirmed, and the sub-scanning at the joint portion of the straight line image (three straight line images in the illustrated example) read by each line sensor is performed. Measure the deviation in direction.

Next, in order to correct the deviation measured in the above step Sa2, the delay amount applied to the pixel data obtained from each line sensor is determined (step S3). That is, in the case of the example in FIG. 10C, the read images L1 to L3 of each part of one straight line are read in the order of L1, L3, and L2, and therefore the line sensor that reads the straight line image L1 is the original document. This means that the licensors, which are located closest to the sending side and read the linear images L3 and L2, are sequentially arranged after this licensor. Therefore, in the case of this example, the delay amount n1 corresponding to the amount of positional deviation in the Y direction between the linear image L1 and the linear image L2 is set for the delay device at the subsequent stage of the line sensor that has read the linear image L1. The delay amount n3 corresponding to the amount of positional deviation in the Y direction between the linear image L3 and the linear image L2 is set for the delay device in the subsequent stage of the line sensor that has read the linear image L3.

If the target is read again after performing this operation, the straight line images L1 to L3 representing the respective parts of one straight line are simultaneously output from the respective delay devices in the subsequent stages of the respective line sensors, As shown in FIG. 10D, an image in which the displacement has been corrected can be obtained.

[0011]

However, either of the above methods 1 and 2 has a drawback that it takes time and labor to measure the positional deviation of the line sensor. Therefore, if the correction operation is performed using these methods at the time of manufacturing the image reading apparatus, there is a problem that the manufacturing cost increases. In addition, each of the above methods has a problem in that the measurement result of the positional deviation varies among individual measurers, and as a result, the degree of adjustment of the output timing of the image data of each line sensor varies.

The present invention has been made in view of the above-mentioned circumstances, and there is very little variation in the adjustment degree of the output timing of the image data of each line sensor, and moreover,
An object of the present invention is to provide an adjusting method and an adjusting device for an image reading device that can be easily and quickly implemented.

[0013]

First, the invention according to claim 1 is a state in which a plurality of line sensors arranged in a line so that their longitudinal directions are the same, and a manuscript and each of the line sensors are opposed to each other. And scanning means for relatively moving the line sensors in a direction orthogonal to the arrangement direction of the line sensors, and sampling the output signals of the line sensors at regular intervals so that the originals read by the line sensors are read. Each delay of each delay device of the image reading apparatus having a plurality of A / D converters for sequentially outputting pixel data representing an image and a plurality of delay devices for respectively delaying each pixel data corresponding to each line sensor In the method of adjusting time, a) a document having a linear pattern is read by each line sensor, and b) an A / D corresponding to each line sensor. The regression line of the pixel group corresponding to each pixel data is obtained based on the pixel data representing the image of each part of the straight line pattern obtained from the converter, and c) in the relative movement direction of the original document and each line sensor of each regression line. The gist of an adjusting method of an image reading apparatus is characterized in that a relative positional deviation amount in a corresponding direction is obtained, and d) a delay time set in each delay device is determined based on each positional deviation amount.

According to a second aspect of the present invention, a plurality of line sensors arranged in a line so as to have the same longitudinal direction, and the line sensor of each of the line sensors with the original and the line sensors facing each other. Scanning means for relatively moving in a direction orthogonal to the arrangement direction and pixel data representing an image on the original read by the line sensors by sampling output signals of the line sensors at regular intervals. A plurality of A / D converters for sequentially outputting,
A device for adjusting each delay time of each of the delay devices of the image reading device having a plurality of delay devices for respectively delaying each pixel data corresponding to each of the line sensors, by giving a predetermined command, When an original with a linear pattern is read by each of the line sensors,
Based on pixel data representing an image of each part of the linear pattern obtained from an A / D converter corresponding to each line sensor,
The regression line of the pixel group corresponding to each pixel data is obtained, the relative positional displacement amount of each regression line in the direction corresponding to the relative movement direction of the original and each line sensor is determined, and this relative positional displacement amount is calculated. An adjusting device for an image reading device is characterized by comprising a correction means for setting a delay time determined on the basis of each of the delay devices.

[0015]

According to the first or second aspect of the present invention, the regression line of each read image of the straight line pattern read by each line sensor is obtained from the pixel data forming each read image, and the relative of each regression line is determined. The delay time set in each delay device is determined based on the amount of positional displacement.
In this way, the delay time is adjusted without the subjective elements being introduced, so that the variation in the adjustment degree can be made extremely small.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. A. Configuration of Embodiment FIG. 1 is a block diagram showing the configuration of an image reading apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 1 is a clock generator for generating various clock signals used for timing control of each section in the image reading apparatus.
Reference numerals 31 to 33 are line sensors each using a CCD (charge coupled device), which are arranged in a staggered manner in the main scanning direction. Reference numeral 2 is a CCD driver, which synchronizes with the clock signal supplied from the clock generator 1
.About.33 are driven, and read signals are output from the respective sensors.

The read signals output from the sensors 31 to 33 are passed through amplifiers 41 to 43 and A / D converters 51 to 53.
Respectively, are sampled by a sampling clock having a predetermined sampling frequency, and are converted into pixel data which is a digital signal. Line memories 61 to 63 are provided as delay devices. A / D converter 5
The pixel data output from 1 to 53 are delayed by the line memories 61 to 63 for a predetermined time. The array circuit 7 forms and outputs image data for one line from each pixel data subjected to the delay processing by the line memories 61 to 63. This image data is stored in a subsequent page memory (not shown).

Reference numeral 100 is a control circuit composed of a CPU and the like. The control circuit 100 causes the apparatus to function as an image reading apparatus by performing the control of the respective units described above, and when performing a correction operation for compensating the positional deviation of the sensors 31 to 33 in the sub-scanning direction, Line memories 61 to 6 necessary for detecting the positional deviation and compensating for the positional deviation
Processing such as setting the delay time of 3 is performed.

B. Operation of Embodiment Hereinafter, the operation of this embodiment will be described. In the present embodiment, the correction operation for compensating the positional deviation of the sensors 31 to 33 in the sub scanning direction is executed according to the flow shown in FIG. First, a document on which a straight line target is drawn is inserted from a document insertion port (not shown) of this image reading apparatus and read by the sensors 31 to 33 (step S).
1). As a result, image data representing the image of the straight line target is stored in the page memory. FIG. 3 illustrates the reading operation of this linear target. When the linear sensors 201 on the original 200 are read by the line sensors 31 to 33 arranged in a staggered manner as shown in this figure, three linear images 201a read by the respective line sensors are shown in the page memory as shown. ~ 201
The image data of c is obtained in the page memory.

Each processing of steps S2 to S5 after step S1 is executed by the CPU in the control circuit 100.
First, in step S2, the regression line of the read image of each part of the straight line target read by each line sensor is obtained based on the image data stored in the page memory. In this embodiment, by reading the linear target by the line sensors 31 to 33, image data of the three linear images 201a to 201c, which are divided from each other, can be obtained in the page memory. Therefore, the regression line of these three straight line images is obtained.

Details of this processing will be described below with reference to FIGS.
Will be described with reference to. Note that, for simplicity, only the calculation of the regression line of the straight line image 201a will be described below, and the other straight line images 201b and 201c are not different from the case of the straight line image 201a, and the description thereof will be omitted.

The regression line of the straight line image 201a is obtained based on the coordinate value of each dot forming the straight line image 201a. Prior to this, the straight line image 201a is selected from all the images.
You need to select only the dots that belong to. Therefore, the following processing is executed.

First of all, as shown in FIG.
Assuming a straight line X = X1 which is considered to pass almost the center of a, the dots existing on this straight line are searched in the + Y direction. In FIG. 4, reference numeral 203 indicates a region where dots exist. Then, the following processing is performed in this search.

A. When the Y coordinate value was increased, it was confirmed that more than a predetermined number (for example, 3) of dots appeared in succession, and the first searched dot (Y coordinate value Y coordinate value of the minimum value). b. The Y-coordinate value is further increased from the Y-coordinate value obtained in the process a, and it is confirmed that a dot-free point (for convenience, a dot-free point) continuously appears for a predetermined number (for example, 3) or more. Then, the Y coordinate value of the dot (the one having the smallest Y coordinate value) searched first among the predetermined number of continuous dotless points at this time is obtained. c. The Y coordinate value Y1 at the center of the Y coordinate values obtained in the processes a and b is obtained. Through the above processing, X = X1
Coordinate values of the center point of the straight line image 201a (X1, Y
1) is obtained. d. A rectangle 202a having a predetermined area centered on the center point obtained in the above-mentioned c is obtained, and the inside of the rectangle 202a
It is regarded as the range in which only the dots forming the are present and is subjected to the following processing. Here, as the rectangle 202a, it is preferable to use a rectangle whose side in the X direction is as long as possible, provided that the dots of the straight line image 201b adjacent to the straight line image 201a are not included inside.

Next, as shown in FIG. 5, all the X coordinate values Xi in the search range 202a are processed by the above processes a to c.
(I = 1, 2, ...) And the straight line image 201a
Of each center point in each X coordinate value Xi of (Xi, Y
i) is calculated.

Next, as shown in FIG. 6, a regression line function Y = AX + B is obtained based on the coordinate values (Xi, Yi) of the respective center points obtained above. Here, if the variance of Yi is σy, the covariance of Xi and Yi is σxy, and the averages of Xi and Yi are Xm and Ym, the constants A and B of the above function are: A = σxy / σx ² B = Ym− It can be calculated by (σxy / σx ² ) Xm.

Next, as shown in FIG. 7, assuming the straight lines LU and LD separated from the regression line Y = AX + B obtained above by a constant distance, the dots and the straight lines LD above the straight line LU in FIG. 7 are assumed. The regression line Y = AX + B is obtained again by excluding the dots located below. By performing such processing, the straight line image 201
The influence of dots unrelated to a (dots corresponding to noise) is removed, and the regression line of the straight line image 201a is accurately obtained. The above processing is performed on the other straight line images 201b and 201.
It is also carried out for c, and each regression line is obtained.

Next, in step S3, the straight line image 201
The following coordinate values, which are Y coordinate values at the joints a to 201c, are obtained based on the regression lines obtained in step S2. Y _1R : Y coordinate value of the right end of the straight line image 201a. It is obtained by substituting the X coordinate value corresponding to the joint of the line sensors 31 and 32 into the function of the regression line of the straight line image 201a. Y _2L : Y coordinate value of the left end portion of the straight line image 201b. It is obtained by substituting the X coordinate value corresponding to the joint of the line sensors 31 and 32 into the function of the regression line of the straight line image 201b. Y _2R : Y coordinate value of the right end portion of the straight line image 201b. It is obtained by substituting the X coordinate value corresponding to the joint of the line sensors 32 and 33 into the function of the regression line of the straight line image 201b. Y _3L : Y coordinate value of the left end of the straight line image 201c. It is obtained by substituting the X coordinate value corresponding to the joint of the line sensors 32 and 33 into the function of the regression line of the straight line image 201c. Then, the positional shift amount at the joint portion of each straight line image, that is, the difference of each Y coordinate value between the adjacent straight line images is obtained.

Next, in step S4, the line sensors 31 to 31 are operated according to the positional deviation amount obtained in step S3.
The delay amounts n1 to n3 to be applied to the 33 read images are determined. That is, the delay amount applied to the line sensor that read the latest linear image is set to 0, the Y coordinate value of the end of the linear image read by that line sensor, and the end of each linear image read by another line sensor. Y
A delay amount to be applied to another line sensor is determined so as to match the coordinate value. FIG. 8 shows line sensors 31 to 33.
Various types of arrangements are assumed, and specific examples of the processing in each case are shown.

First, (a) shows the case where the central line sensor 32 is arranged at the rearmost position, and the reading of the linear target by this line sensor is performed at the latest delay. In this case, the delay amount applied to the image read by the line sensor 32, that is, the delay amount n2 set in the line memory 62 is set to zero. Then, the above step S3
The difference between the Y coordinate values Y _2L and Y _1R obtained in step Y _2L −Y _2R
The corresponding delay amount n1 is the delay amount applied to the line sensor 31, and the delay amount n3 corresponding to the difference Y _2R −Y _3L between the Y coordinate values Y _2R and Y _3L is the delay amount applied to the line sensor 33.

Next, in the case of (b), the line sensor 31
The delay amount n1 applied to the read image of is set to 0. Then, the difference between the left end portion of the Y-coordinate value Y _2L and Y _1R Y coordinate value Y _1R and the straight line image 201b at the right end of the linear image 201a Y _1R
The delay amount n2 corresponding to −Y _{2L is} the delay amount applied to the line sensor 32. By applying this delay amount n2,
The image read by the line sensor 32 on the straight line target moves to the position indicated by the broken line. Therefore, in the case of (b), the delay amount n3 corresponding to Y _2R + Y _1R -Y _2L -Y _3L is applied to the line sensor 33,
The left end of the straight line image read by the line sensor 33 is connected to the right end of the straight line image indicated by the broken line.

The same applies to the other cases (c) to (e). As shown in FIG. 8, each straight line image obtained when the straight line target is read by each line sensor is adjacent to each other at each end. The amount of delay applied to each line sensor is determined so as to be connected to the straight line image.

Next, in step S5, the line memory 6
The control information for the delay process performed by 1 to 63 is set based on each delay amount obtained in step S4, and the entire process for the correction operation is completed. This allows
After that, the pixel data of each image read by the line sensors 31 to 33 is delayed by the delay amount obtained in step S4 and sent to the array circuit 7.

FIG. 9 shows the delay processing performed in the line memories 61 to 63. A / D converter 51-
Each pixel data sequentially output from 53 is 000
Addresses 0, 0001, 0002, ... Are sequentially stored in the storage areas of the line memories 61 to 63 while sequentially increasing the write address. Then, in parallel with the writing of the pixel data, the reading of the pixel data is performed. Here, when the delay amount to be applied to the pixel data is K, the pixel data in the storage area that is K addresses before the write address of the pixel data at each time point, that is, the pixel data currently written The pixel data output from the A / D converter before the K address is read from the line memory. The above delay processing is performed by each of the line memories 61 to 63, and image data without distortion is output from the array circuit 7.

C. Other Embodiments The following may be considered as other embodiments of the present invention. (1) In the above embodiment, the adjustment device according to the present invention is incorporated in the image reading device.
It is also possible to prepare an adjusting device separate from the image reading device at the manufacturing site and adjust the delay time of each line memory in the image reading device by this adjusting device.

(2) When the regression line of the straight line image obtained by reading the straight line target is obtained, it is judged whether or not the gradient between the regression lines is within a predetermined range. Then, if it is not within the predetermined range, there is a possibility that the original of the straight line target has not been inserted straightly, and therefore a message prompting reinsertion is output. By adding such a function to the above embodiment, it is possible to prevent an inappropriate delay amount from being set in the line memory.

(3) The present invention can be applied to applications other than the compensation of positional deviation of a plurality of line sensors. For example, the document conveyance direction needs to have an accurate right angle at the intersection with the line sensor arrangement direction. However, if this intersection angle deviates from the right angle, the original inserted in the copying machine will have its leading edge aligned with the line. Reading is performed in a state in which the sensor is inclined with respect to the arrangement direction. In this case, some correction processing is required in order to perform accurate image reading, but the technique of the above-described embodiment can be applied to this correction processing. Further, although a technique of adjusting the magnification in the main scanning direction and the sub scanning direction of the image reading device may be used based on the reading result of a predetermined pattern, the technique of the above embodiment may be applied to this technique. It is possible.

[0038]

As described above, according to the adjusting method of the present invention, the delay amount applied to each line sensor of the image reading apparatus is determined without the intervention of subjective elements, so that the output timing of the image data is determined. It is possible to extremely reduce the variation in the adjustment degree of. Further, according to the adjusting device of the present invention, the above adjusting method can be carried out easily and quickly, so that the manufacturing cost of the image reading device and the quality variation can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an image reading apparatus to which the present invention is applied.

FIG. 2 is a flowchart showing an adjusting method according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a procedure for performing the adjustment method.

FIG. 4 is a diagram illustrating a procedure for performing the adjustment method.

FIG. 5 is a diagram illustrating a procedure for performing the adjustment method.

FIG. 6 is a diagram illustrating a procedure for performing the adjustment method.

FIG. 7 is a diagram illustrating a procedure for performing the adjustment method.

FIG. 8 is a diagram illustrating a procedure for performing the adjustment method.

FIG. 9 is a diagram illustrating delay processing by a line memory.

FIG. 10 is a diagram illustrating a method of adjusting a conventional image reading apparatus.

[Explanation of symbols]

 31-33 ... Line sensor, 51-53 ... A / D converter, 61-63 ... Line memory (delay device), 100 ... Control circuit (adjusting device).

Claims (2)

[Claims] 1. A plurality of line sensors arranged in a line so that their longitudinal directions are the same, and a document and the respective line sensors are opposed to each other in a direction orthogonal to the arrangement direction of the respective line sensors. A scanning unit for moving and a plurality of A / Ds for sequentially outputting pixel data representing an image on the original read by each line sensor by sampling an output signal of each line sensor at regular intervals. In a method of adjusting each delay time of each delay device of an image reading apparatus having a converter and a plurality of delay devices each delaying each pixel data corresponding to each line sensor, a) a linear pattern is represented. The original document is read by each line sensor, and b) an image of each part of the linear pattern obtained from an A / D converter corresponding to each line sensor. The regression line of the pixel group corresponding to each pixel data is obtained based on the pixel data representing c, and c) The relative displacement amount of each regression line in the direction corresponding to the relative movement direction of the document and each line sensor is obtained. D) An adjusting method for an image reading apparatus, characterized in that a delay time set in each delay device is determined based on each positional deviation amount. 2. A plurality of line sensors arranged in a line so that their longitudinal directions are the same, and a document and the respective line sensors are opposed to each other in a direction orthogonal to the arrangement direction of the respective line sensors. A scanning unit for moving and a plurality of A / Ds for sequentially outputting pixel data representing an image on the original read by each line sensor by sampling an output signal of each line sensor at regular intervals. A device for adjusting each delay time of each delay device of an image reading device having a converter and a plurality of delay devices for respectively delaying each pixel data corresponding to each line sensor, wherein a linear pattern is represented. When the original document is read by each of the line sensors, the A /
The regression line of the pixel group corresponding to each pixel data is obtained based on the pixel data representing the image of each part of the straight line pattern obtained from the D converter, and the regression line of each regression line corresponds to the relative movement direction of the document and each line sensor. An adjustment device for an image reading apparatus, comprising: a correction unit that obtains a relative positional deviation amount in the predetermined direction and sets a delay time determined based on the relative positional deviation amount in each of the delay devices. .