JP3029142B2 - Printing evaluation method and printing evaluation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print evaluation method and a print evaluation apparatus for evaluating the output image quality of an image output device using a print object such as paper as a medium.

[0002]

2. Description of the Related Art Conventionally, the evaluation of printing on an image output device such as an ink jet printer, a laser beam printer, etc., has been mostly performed by manual visual sensory evaluation in a production process. In addition, a pattern suitable for each evaluation item is printed on the entire surface or a part of separate paper.

[0003]

However, in the above-mentioned visual inspection, a constant pitch horizontal line or the like is printed on the entire surface of the evaluation paper in order to perform fine evaluation, for example, paper feed pitch unevenness, and the whole paper is compared to evaluate a part of the pitch unevenness. are doing. Therefore, only one item can be evaluated on one sheet of paper.

[0004] Therefore, in order to evaluate, for example, dozens of print items, dozens of print sheets must be output, which requires a great amount of output time and evaluation time. In addition, there are individual differences in the evaluation results, and the individual evaluation results themselves are ambiguous values. In addition, since the eyes are abused, for example, by staring at the entire surface of the paper for measurement, the load on the inspector is very large.

[0005] The present invention has been made in view of the above points,
It is an object of the present invention to provide a print evaluation method and a print evaluation device capable of reducing the load on an inspector for print evaluation and evaluating print quality at high speed and with high accuracy. .

[0006]

According to the present invention, there is provided a print evaluation method comprising the steps of: printing on a printing object, including a plurality of measurement areas corresponding to a plurality of inspection items; A pattern is read using a reading unit, and image signals corresponding to the plurality of measurement areas, which are output from the reading unit, are input to different arithmetic processing units, and each of the plurality of inspection items is input by each processing unit. Is characterized in that arithmetic processing for evaluation of is performed in parallel. Further, the print evaluation apparatus according to the present invention includes a reading unit that reads a print evaluation pattern including a plurality of measurement patterns corresponding to a plurality of inspection items printed on a print target, and the plurality of output units that are output from the reading unit. A plurality of processing means for performing print evaluation on a plurality of inspection items based on an image signal corresponding to the measurement pattern, and inputting the image signals corresponding to the plurality of measurement areas to different arithmetic processing means. In addition, arithmetic processing for evaluating each of a plurality of inspection items is performed in parallel by each arithmetic processing means.

[0007] Thereby, image signals corresponding to a plurality of measurement areas are processed in parallel by different processing means, respectively, and a plurality of inspection items are evaluated.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a print evaluation apparatus according to the present invention. The imaging device 1 is a one-dimensional CCD
It is composed of a light receiving element such as a line sensor, captures an image of the test paper 4 to be evaluated, and converts it into an electric signal for each scan. The illumination 3 illuminates the imaging position of the imaging device 1, and the stage 2 is arranged so as to move in a direction orthogonal to the arrangement of the light receiving elements of the imaging device 1. An image to be evaluated can be read as an image. The video signals obtained by the imaging device 1 are converted from analog data to digital data by A / D converters 5 to 7, and after performing processes such as dark correction and shading correction, the image signals are sent to image processing units 8 to 11. Will be transferred. The image processing units 8 to 11 can divide and store the captured image data in a plurality of evaluation target areas, and connect a plurality of image processing units to one A / D conversion unit via a bus 15. In this case, the plurality of image processing units can operate in parallel. Further, as shown in the image processing unit 9, a histogram calculation unit 13 and a run code calculation unit 14 can be connected via the image bus 12. When the histogram calculation unit 13 and the run code calculation unit 14 are connected, the image data transferred from the A / D conversion unit 5 is stored in the image memory in the image processing unit 9 and at the same time, the histogram calculation unit 13 The calculation result is also transferred to the run code calculation unit 14, and the calculation result is stored in the memory in each calculation unit. The calculation results stored here can be read out by the image processing unit 9 via the image bus 12.

The control CPU 16 controls the A / D converters 5 to 5 in accordance with an operation command from the host computer 21.
7. It controls the image processing units 8 to 11, the floppy disk controller (FDC) 17, and the display image memory 18. The floppy disk 20 stores parameters of the present system, for example, binarization levels set in the A / D converters 5 to 7, data of dark correction and shading correction, and image processing units 8 to 11. The image processing parameters such as the number of image capture areas, the range of the capture area of each area, the criterion for each evaluation item, and the window size of the smoothing filter are stored. The contents of these parameters can be read and rewritten according to an instruction from the host computer 21. Data of the image memories of the image processing units 8 to 11 can be transferred to the display image memory 18 via the bus 15, and the captured image data is displayed on the display monitor 19.

The stage controller 23 controls the stage 2 according to an operation command from the host computer 21. The sequencer 22 controls the operation such as positioning and detachment of the inspection paper 4.

FIG. 2 is an external perspective view showing a specific configuration of the image pickup apparatus 1, stage 2, illumination 3, etc. shown in FIG.

In FIG. 1, an image pickup apparatus 1 comprises four image pickup units 1-1 to 1-4 having light receiving elements of a CCD line sensor, and outputs obtained video signals to A / D converters 5 to 7. Here, the imaging units 1-1, 1-2 and 1-3, 1-4
Are paired, and each of the imaging units 1-3 and 1-4 is A
The video signal is output to the / D converter 6. The stage 2 further has a cylinder unit 2-1 for adsorbing the inspection paper 4 to the surface of the stage 2, and the control is performed by the stage controller 23 similarly to the stage 2.

The illuminator 3 comprises two illuminators 3-1 and 3-2 constituted by halogen lamps, corresponding to the imaging units 1-1, 1-2 and 1-3, 1-4, respectively. Is provided. As long as the illumination 3 has a sufficient light quantity, a fluorescent lamp is preferable from the viewpoint of the calorific value and the like.

FIG. 3 is a block diagram of an image memory control unit in the image processing units 8 to 11. In the area storage circuit 24,
The values of the start X coordinate, the end X coordinate, the start Y coordinate, and the end Y coordinate of the area for taking in the image are written. When taking in a plurality of areas, the start and end XY coordinates of each of the plurality of areas are written in the area storage circuit 24. Further, a plurality of areas may be set to overlap each other.
The comparison circuit 25 compares the X and Y coordinates of the currently input image with the value set in the area storage circuit 24,
If the X and Y coordinates of the currently input image are within the range of the X and Y coordinates set in the area storage circuit 24, a control signal 26 is sent to the image data control circuit 27, and the image data is sent to the image data control circuit 27. Write to memory 28. After all data of the set area is stored in the image memory 28, the CPU 2
Reference numeral 9 reads image data and performs image processing set in the ROM 30 and the RAM 31.

FIG. 4A shows a case where a plurality of areas 35 to 38 are set in the inspection object 34. FIG. 4B is FIG.
Shows a case where the data of the area set in the step (1) is stored in the image memory 28 of one image processing unit.

The data of the areas 35 to 38 are divided and stored as 41 to 44 area data in the image memory 28 of the image processing section. In this case, FIG.
Is realized by writing the start and end points of the X and Y coordinates of the area 1 (35) to the area 4 (38) in the area storage circuit 24.

Next, FIG. 4C is an explanatory diagram in the case where image data of a plurality of areas is stored separately in a plurality of image processing units. The X and Y coordinate values of the start and end of the area 1 (35) are written only in the area storage circuit of the image processing section 1, and only the area 1 data (53) is stored in the image memory 28-1. It is captured. Similarly, the image processing unit 2 is in charge of the area 2 (36), the image processing unit 3 is in charge of the area 3 (37), and the image processing unit 4 is in the area 4 (3).
By taking charge of 8), image data of a plurality of areas can be divided and handled by a plurality of image processing units. By adopting such an area capture method,
Only the necessary parts can be divided and stored in the image memory efficiently from the huge image area, and the image processing units can be operated in parallel by sharing them to multiple image processing units. Speedup can be realized.

Next, a printing position accuracy evaluation method will be described with reference to FIGS. FIG. 5 shows an embodiment of an evaluation pattern output by the inspection object, FIG. 6 shows an example of a measurement point area of the pattern, FIG. 7 shows a processing flow chart of a printing position accuracy evaluation method, and FIG. . The printing position accuracy evaluation process will be described below with reference to the drawings.

An evaluation pattern is fetched into an image processing device by image input (S ₁ ) and binarized (S ₂ ). Then, as shown in FIG. 6, the coordinate values of the paper edge or the print line are sequentially calculated for the measurement point areas required for the print position accuracy evaluation set in the area storage circuit 24 in advance (S
₃ ). First, it is determined whether the paper edge position measurement or the print line position measurement is within the set measurement point area (S ₄ ). If it is the print line position, a line edge pattern is searched from the binarized data (S ₅ ). The coordinates of the rising position and the falling position shown in FIG. 8 are stored, the center value of the print line width is calculated from both values, and the center value is stored as the print line position. The measurement point area when the paper edge, stores the position coordinates falling explore the edge pattern from the binary data (S ₁₅ ~S _17). FIG. 8 shows the relationship between the binarized signal output and the falling position and the rising position. When the calculation of the coordinate values for all the measurement points is completed, the positional relationship between the measurement points is calculated, and the quality of the printing position is determined (S13).

For example, tip margin = ay-iy and b
y-ji, right angle = | (ay-by) / (ax-bx) + (cx-
dx) / (cy-dy) | × 100%, skewness = | (ay-iy) − (by-ji) / (ax−)
bx) | × 100%, parallelism = | (ay−ey) − (by−fy) / (ax−
bx) | × 100%, etc. and the standard value. Where a
To f, i, j indicate each measurement point in FIG.
X and Y represent the X coordinate value and the Y coordinate value of each measurement point. Further, the frame line of the evaluation pattern is not limited to the image-formable area frame, but may be a certain rule, for example, 5 mm from the top edge of the paper.
A combination of horizontal lines output at the position, vertical lines output at a position 4 mm from the left end, and the like may be used.

FIG. 9 shows how to evaluate the linearity of a printed line. This evaluation is performed by the image processing unit 9.

The image (line pattern) input in S40 is binarized (S41), and the line pattern is stored in the run code memory 77 in the run code calculation unit 14 as an edge position and a line width (S42). At this time, by specifying the line width limit, noise components such as those larger or smaller than the limit line width can be excluded, and only the data of the line pattern is stored. Next, smoothing is performed in each block in order to eliminate fine irregularities of the edge (S
43). The data used at this time uses the position coordinates of the edge detected in S42. Next, straight line approximation is performed using the smoothed edge coordinates (S44), and this straight line is used as a reference straight line for linearity evaluation. Then, the peak position of the smoothed edge coordinates is detected (S45).

In this case, the peak position means the position of the peak or valley of the undulation of the edge. As a method of detecting peaks,
The difference between adjacent edge coordinates is obtained, and it is checked whether the sign of the difference value is positive or negative. At this time, a point at which the sign changes from positive to negative or from negative to positive is defined as a peak position. When the difference is zero, the midpoint of the zero section is set as the peak position. Then, the difference between the obtained peak position and the reference straight line is calculated (S46), and the maximum value of the difference between the peak position and the reference line is obtained (S47). Then, it is evaluated whether the product is defective or not (S48).

FIG. 12 is a view for explaining run code data used when evaluating linearity.

Reference numeral 57 denotes a line pattern, and reference numeral 58 denotes a scanning position where the run code data is obtained. 59 is the starting point coordinates of the pattern stored in the run code memory 77, and 60 is the pattern width also stored in the run code memory 77. When an image is input and binarized, it is stored as run code data in the run code memory 77, so that data can be stored more efficiently than when a two-dimensional image is directly stored in the memory. Also, when capturing an image as run code data, the maximum width limit
By setting the minimum width limit value 62, a pattern such as the noise component 61 is not sampled, and data of only a line pattern can be captured.

Next, evaluation of pitch unevenness will be described with reference to FIG.

The image input in S20 is fetched as multi-value data having multi-tone density values (S2).
1) The projection operation is performed by the histogram operation unit 13 and stored in the histogram memory 78 (S22). Here, projection refers to adding multi-value data in the line length direction of a printed line pattern. The one-dimensional data obtained in S23 is smoothed to remove noise components (S24). Next, the peak position of the smoothed projection data is detected (S2).
5). Here, the peak position refers to the position of the peak or valley of the projection data. As a peak detection method, the difference between adjacent projection data is taken, and the sign of the difference value is positive,
Check if it is negative. At this time, a point at which the sign changes from positive to negative or from negative to positive is defined as a peak position. When the difference is zero, the midpoint of the zero section is set as the peak position. Also,
As a peak detection method, the presence of a peak or a valley may be used to determine the center of gravity of the section, and the value may be used as the peak position.

Next, the interval between the peaks adjacent to the peak position obtained in S25 is calculated and set as the pitch interval (S2).
6). Then, the quality of the pitch interval is determined (S27).
Evaluation is made based on the maximum value and the minimum value of the pitch interval. Alternatively, the variance of all the pitches may be obtained, and the evaluation may be made based on the degree of pitch variation. Further, when the pitch interval changes periodically, for example, when the even-numbered pitch and the odd-numbered pitch alternate, the difference between the average value of the even-numbered pitch and the average value of the odd-numbered pitch is calculated. May be evaluated based on whether the difference exceeds a reference value. S27
If it is determined to be defective, the evaluation is terminated. S2
If it is determined to be good in 7, the process proceeds to the next evaluation. In other words, even if the pitch interval is good, if the contrast between the printed line and the background portion varies, this will appear as density unevenness of the entire image, and the print quality will deteriorate. In order to perform the evaluation in this case, the peak difference between white and black, that is, the height of adjacent valleys and peaks is calculated (S28).

Next, the frequency distribution of the peak difference obtained in S28 is calculated (S29). If the contrast is constant,
A high frequency distribution appears at the position of a certain peak difference, and there is little variation in the frequency distribution. Conversely, when the contrast is uneven, the frequency distribution is low and the variation is large. Therefore, h / w is calculated as the height h and the base width w of the frequency distribution as an evaluation function, and is set as the state value of the contrast (S30). Then, based on the value of the evaluation function obtained in S30, good or bad is determined, and the evaluation is completed (S3).
1).

FIG. 11A is a diagram showing a peak difference frequency distribution when the contrast is constant, and FIG. 11B is a diagram showing a peak difference frequency distribution when the contrast is uneven. h ₁ and h ₂ are the maximum values w ₁ and w ₂ of the respective frequency distributions, and the base widths of the frequency distributions.

FIG. 13 is a diagram for explaining the projection of a line pattern. 64 is a printed line pattern, and 65 is a noise component existing between the line patterns. Reference numeral 66 denotes a line length direction, and the result of adding multi-value data in this direction is 67 projection data. In the projection data, a line pattern portion appears as a peak of 68 peaks, and a background portion between the line patterns appears as a peak valley of 69. By taking this projection data, noise components between the line patterns and unevenness at the edge of the line pattern can be removed, and the pitch of 70 lines can be accurately extracted.

FIG. 14 is a diagram for explaining a defective state when a line pattern is printed, that is, a pitch unevenness. 7
1 is a printed line pattern, 72 is projection data,
The pitch of the defective portion 73 is smaller than that of the normal portion 73, and the peak difference 76 of the defective portion is smaller than the peak difference 75 between the peak and the valley adjacent to the normal portion. .

Second Embodiment Next, an embodiment in which a plurality of evaluation items as described above are processed in parallel using a composite pattern will be described. FIG.
FIG. 5 is a diagram showing a print evaluation device according to a second embodiment of the present invention. The imaging device 101 is composed of four light receiving elements such as a one-dimensional CCD line sensor and the like.
05 is captured and converted into an electric signal. The illumination 102 illuminates the imaging position of the imaging device 101 in a line shape.
The stage 103 is arranged so as to move in a direction orthogonal to the direction in which the light receiving elements of the imaging device 101 are arranged.
01 and the stage 103, the image of the inspection paper 105 to be evaluated can be read as a two-dimensional image.
Reference numeral 108 denotes a stage control unit, which is a host computer 1
The stage 103 is driven in accordance with the instruction 09. The stage 103 is provided with a linear encoder 104 and stage sensors 112 to 115, and the output of the linear encoder 104 is used when correcting the speed unevenness of the stage 103. Also, the stage sensor 112 ~
The output of 115 is used as a trigger signal for stage drive and image capture. A correction chart 106 is provided on the stage 103, and is used when correcting sensitivity unevenness or a shading state of the image capturing apparatus 101.

The video signal obtained from the imaging device 101 is
The image is sent to the image processing unit 107, the image processing is performed for each item to be evaluated, and the result is transferred to the host computer 109.
The image processing unit 107 is capable of inputting from a plurality of imaging devices. Reference numeral 110 denotes a display monitor, which can display image data captured by the image processing unit 107. A program for controlling the image processing unit 107 and parameters necessary for image processing are stored in the external storage unit 111, and the contents can be read and rewritten from the host computer 109. Reference numeral 118 denotes a result display monitor, and 119 denotes a printer, both of which output evaluation results from the host computer. In addition, a plurality of suction holes 117 are provided in the inspection paper setting area on the stage 103 in accordance with the size of the inspection paper.

In the evaluation apparatus of this embodiment, an image can be captured and evaluated at the same stage speed during the same scan by a plurality of sensors having different measurement resolutions. For example, the 5000-bit line sensor 801 shown in FIG.
Measurement width 250mm, measurement resolution 50 by / 7x optical system
The entire surface of A4 paper is scanned at μm. The 1000-bit line sensor 802 has a measurement width of 10 mm and a measurement resolution of 10 μm by a 1 / 3.57-fold optical system as shown in FIG.
The pitch unevenness measurement area 509 shown in FIG. In this configuration, both sensors are driven at a frequency of 8 MHz, so that a single stage movement allows a simultaneous measurement resolution of 50 MHz.
Different measurements of μm and 10 μm are possible. In other words, 5000 bits are required as the number of sensor bits in order to cover the width of A4 paper at a measurement resolution of 50 μm.
In order to obtain a resolution of μm, at a sensor driving frequency of 8 MHz, the moving speed S of the stage is as follows: S = 50 μm × 8 MHz ÷ 5000 bits = 80 mm /
sec, and one scan of A4 vertical paper = 3.75 sec, which enables high-speed operation. To obtain a measurement resolution of 10 μm at the same stage speed, the number of sensor bits = 10 μm ×
8 MHz ÷ (80 mm / sec) = 1000 bits (measurement area 10 mm). Then, as shown in FIG.
While moving, 1000 times for 5000 bit sensor once
The bit sensor performs five scans.

In this embodiment, a line sensor 205 described later is used.
And 206 (FIG. 18) with a 5000-bit sensor, and line sensors 207 and 208 (FIG. 18) with a 1000-bit sensor.
It is composed of a t sensor.

Next, control of the operation of the apparatus performed by the image processing unit 107 and the stage control unit 108 will be described with reference to FIG.
This will be described with reference to FIG. First, an inspection paper 105 to be evaluated is set on the stage 103 of the apparatus by an operator or a paper supply mechanism (not shown) in R2, and a start switch of the apparatus is turned on by the operator in R3, or Is turned on by the trigger signal from
The vacuum device 116 is operated to suck the test paper 105 and fix it on the stage 103. After the suction is completed, the stage 103 starts moving at R5, and the image processing unit 107 enters an image input waiting state at R6.

When the stage sensor 1 is turned on while the stage 103 is moving (R7), the image processing unit 107 starts capturing image data at R8, and the image on the stage outward path set in the image processing unit 107 in advance is set. When the capture of the image data for the capture area is completed, the input of the image data is terminated at R9. And the image processing unit 107
The image data captured in R10 is evaluated for each evaluation item.
The processing is performed in R17, and the processing result is transferred to the host computer 109 in R31. After the input of the image data is completed, when the stage 103 reaches the end of movement and the stage sensor 2 is turned on (R18), the movement of the stage 103 is stopped at R19. Then, the stage 103 immediately starts moving in the reverse direction (R26). The image processing unit 107 enters a state of waiting for input of image data of an image area to be taken in the stage movement return path (R21). And
When the stage sensor 3 is turned on (R22), the capture of image data on the return path is started (R23). When the image data for the image capturing area in the stage return path set in the image processing unit 107 is completed in the same way as the outward path (R24), the input of the image data is terminated, and the captured image data is output for each evaluation item. The processing is performed in R25 to R30, and the processing result is transferred to the host computer 109 in R31. Then, in the host computer 109, the evaluation / determination of the items captured for the forward path is performed in parallel with the capture and processing of the image data in the return path, and then the evaluation / determination of the items for the return path is performed, and the evaluation results are put together. Output to the display monitor 118 and the printer 119.

After the input of the image data for the return path is completed, the stage 103 further moves on the return path, and stops moving the stage 103 when the stage sensor 4 detects that it has reached the stage origin position (R33, R34). . Then, the vacuum device 116 is stopped at R35, and the inspection paper 1
05 is released. Finally, the inspection paper 105 is discharged from the moving stage 103 by an operator or a paper discharge mechanism (not shown), and a series of operations is completed.

In this embodiment, the inspection items performed on the outward path of the stage 103 include a printing position accuracy measurement, a linearity measurement (low frequency component and high frequency component), and a partial magnification measurement, which will be described later. The inspection items performed on the return path of the stage 103 include pitch unevenness measurement and density measurement.

FIG. 18 shows the image processing unit 107 shown in FIG.
FIG. 3 is a block diagram showing the configuration of FIG. 200 is a control CPU for controlling the entire image processing unit, and 201 to 204 are A
/ D processing unit, the line sensor 205 in the imaging device 101
Control signal output to MPU-208 and MPU processing unit 2
Image data, timing signals, and two-dimensional coordinate data are output to 09 to 214. Reference numerals 209 to 214 denote MPU processing units 209 to 214 each having an image memory as described later.
A predetermined calculation process is performed based on the image data from the D processing unit, and the calculation result is sent to the control CPU 200. 21
A run code processing unit 5 calculates a run code from the binary image input from the image bus, and stores the position coordinate data and the width data of the changing point of the binary image in its own memory. 21
Reference numeral 6 denotes a projection (histogram) processing unit that calculates projection data of the multi-valued image or the binary image input from the image bus onto the XY coordinate axes and stores the data in its own memory. The line sensors 205 to 208 are driven by control signals output from the A / D processing units 201 to 204, and send their video outputs to the A / D processing units 201 to 204. 218-22
Reference numeral 1 denotes an image bus, two-dimensional XY coordinate data output from the A / D processing units 201 to 204, digitized binary data
The multi-valued image data, area effective signal, and clock signal are transferred to the connected MPU processing units 209 to 214, the run code processing unit 215, and the histogram processing unit 216.
MPU buses 222 and 223 are MPU processes 212 and 2.
13 transfers the partial area information to the projection processing unit 216 and the run code processing unit 215. Reference numeral 217 denotes a system in which the control CPU 200 executes processing units (201 to 204, 2
09-214). Reference numeral 224 denotes an input start trigger signal line for inputting timings at which the A / D processing units 201 to 204 output timing signals, image data, and two-dimensional coordinate data to the image buses (218 to 222). Start signal is connected.

FIG. 19 is a block diagram showing the configuration of the A / D processing units 201 to 204. Reference numeral 302 denotes an input of the above-described image input start trigger signal, and reference numeral 303 denotes an encoder pulse output from the encoder 104 in accordance with the movement of the stage 103. Signal input, 304 is a scan start pulse output for driving the line sensors 205 to 208, 305 is a clock pulse output for driving the line sensors 205 to 208, and 306 is driven by the A / D processing unit. Analog image signals output from the line sensors 205 to 208, 307 is a digital image signal output from the line sensors 205 to 208 similarly driven by the A / D processing unit, 315 is a timing pulse generator, And outputs the necessary divided clock signal. An X coordinate counter 314 counts clocks generated by the timing pulse generator 315 by a predetermined number of clocks, generates and outputs a scan start pulse for driving a connected line sensor, and outputs the scan start pulse to the Y coordinate counter 313. It outputs a count-up pulse and outputs X coordinate data to the image bus 300. 3
Reference numeral 13 denotes a Y coordinate counter, and an input start trigger signal 30
2, the counting operation is performed for a predetermined number of pulses by the count-up pulse from the X coordinate counter 314, and the Y coordinate data 308 is output to the image bus 300. The Y coordinate counter can also count the Y coordinate by an encoder pulse 303 generated according to the movement of the stage 103. As a result, it is possible to correct speed unevenness when the stage 103 moves as described later. An A / D converter 316 converts an analog image signal from a line sensor connected to an A / D processing unit into a digital value. An input signal selector 317 selects one of the analog signal 306 and the digital signal 307 from the line sensor. Reference numeral 318 denotes a memory for dark correction, which is storage means for inputting correction data previously created from a video signal of a line sensor, such as a calibration chart. 320 is a memory for shading correction,
This is also storage means for inputting correction data previously created from the video signal of the line sensor using a calibration chart or the like.
A subtractor 319 subtracts the digital value of the video signal from the line sensor (output of the selector 317) from the data stored in the dark correction memory in advance. A divider 321 divides a signal output from the subtractor 319 by data from the shading correction memory 321. Reference numeral 323 denotes a binarization level holding unit, and 322 denotes a comparator which outputs the signal output from the divider 321 and the binarization level holding unit 3.
The binary data is output by comparing with the binarization level set at 23. Reference numeral 324 denotes an interface with the system bus 301, which is connected to the control CPU 200 for system control via the system bus 301. Reference numeral 300 denotes an X coordinate data 308, a Y coordinate 309 data, an area valid signal / clock 310, and a multi-valued image data 31 for each MPU processing unit, projection processing unit, and run code processing unit.
This is an image bus for outputting one- and two-level image data 312 and the like.

FIG. 20 is a block diagram showing the configuration of the MPU processing units 209 to 214. An image bus 400 is connected to the above-described A / D processing unit. Reference numeral 402 denotes a timing signal input such as an area valid signal and a clock, 403 denotes an X coordinate data input, 404 denotes a Y coordinate data input, 405 denotes a binary image data input, and 406 denotes a multi-value image data input.
Reference numeral 409 denotes a timing generation unit which generates a timing signal used in the MPU processing unit. Reference numeral 410 denotes an area storage / detection unit that stores each area information used by the MPU processing unit,
Each area is detected based on the input X coordinate data 403 and Y coordinate data 404. That is, the MPU processing unit stores in advance X, Y coordinate information corresponding to a plurality of necessary cutout positions with respect to the entire X, Y coordinates specified by the MPU 417 on the MPU processing unit. A valid signal is output to the thinning detection unit 412 according to the information. The thinning storage detection unit 412 is a storage unit that previously stores the thinning amounts of X and Y corresponding to a plurality of areas in accordance with an instruction of the MPU 417 on the MPU processing unit, and stores image data in the corresponding area during operation. A timing signal for thinning out is generated and output to the image memory address counter 414 and the MPU bus 401. 4
Reference numeral 14 denotes an image memory address counter. When an image input instruction is given to the image memory 415 by the effective area information corresponding to a plurality of areas from the thinning storage detection unit 412,
The address counter of the image memory 415 is incremented, and a write address and a write signal are output to the image memory 415. The image memory 415 can store input image data of a plurality of processing areas. Reference numeral 411 denotes a serial / parallel conversion unit, which is a conversion unit for storing the binary image data 405 as an input signal in the image memory 415; and 413, a selection unit for image data to be input to the image memory 415. Select image data. A memory 416 stores a control program and data of the MPU. The MPU 417 performs operation setting and image processing in the MPU processing unit. Reference numeral 418 denotes an interface with the system bus 420, and reference numeral 419 denotes an I / O.
O port, MPU 417 and control CPU 200
And an information transmission unit. An output unit 401 outputs an MPU control signal 408 and a plurality of effective processing area information 407 to a run code processing unit and a projection processing unit connected to the MPU processing unit via an MPU bus.

FIG. 21 is a block diagram showing the configuration of the projection processing unit 216. Reference numeral 420 denotes an image bus, which is an area valid signal and a clock signal 422 and multi-valued image data 42 output from the A / D processing unit 203 via the image bus 220.
3 is input. A timing generation unit 426 generates and outputs a timing signal required by the projection processing unit. 427
Is an address counter that generates an address signal for the projection memory 431 based on a timing signal from the timing generator 426. A memory clear circuit 428 generates and outputs a signal for clearing the contents of the projection memory 431. Reference numeral 429 denotes an address selection unit of the projection memory 431, which selects an address according to a clear operation, a projection generation operation, and an MPU read operation. The selection instruction is selected by the MPU 417 of the MPU processing unit via the MPU bus 421. Similarly, 430 is an input data selection unit of the projection memory,
32 is a data output buffer of the projection memory 431, 433
Is a projection operation unit. A data operation unit for adding the projection memory data stored in the data output buffer 432 and the multi-valued image data 423 from the image bus 420 and writing it back to the projection memory 431 is a control circuit.
From the effective area information 424 from the U bus 421 and the MPU bus 425, a condition signal for generating a timing signal necessary for the operation of the projection processing unit is output to the timing generation unit 426.

FIG. 22 is a block diagram showing the configuration of the run code processing unit. Reference numeral 440 denotes an image bus, and the A / D processing unit 2
02, an area effective signal and a clock signal 442, X coordinate data 444, Y
The coordinate data 443 and the binary image data 445 are input.
Reference numeral 448 denotes a timing generation unit which generates and outputs a timing signal required for the run code generation of the run code processing unit. 44
9 is an address counter for run code memories 452 and 45
A memory address at the time of 3,454 run code data creation operation is generated. 451 is a run code memory 452, 4
The addresses of 53 and 454 are stored in the MPU of the MPU processing unit 212.
The selection is made by one of the read operation from the CPU and the run code generation operation. Reference numeral 452 denotes a Y coordinate memory for storing Y coordinate data of one run code. An X coordinate memory 453 stores the X coordinate data of the start position or the end position of one run code. Reference numeral 454 denotes a width memory which stores the number of pixels of one run code in the X direction. Memory 452, 45
3,454 is Y coordinate data for one run code,
X coordinate data and X direction width data are stored at the same offset value in each of the three memories. Reference numeral 455 denotes a selection unit for input data in the Y coordinate memory, 457 denotes a selection unit for input data in the X coordinate memory, 459 denotes a selection unit for input data in the X direction width memory, and the selection units 455, 457, and 459 denote run code processing. The selection is made according to an instruction from the MPU processing unit 212 by the operation of the unit. Reference numeral 456 denotes a buffer for reading the Y coordinate memory data from the MPU processing unit 212, and 458 denotes a MPU processing unit 212 for the X coordinate memory data.
A reading buffer 460 is a buffer for reading X-direction width memory data from the MPU processing unit 212. Reference numeral 450 denotes an effective width detection unit, which is an MPU processing unit 212.
The instruction signal and each write data are output so that only valid run code data is written to the run code memories 452, 453, and 454 in accordance with the set values in which the upper limit and the lower limit of the X direction width are set by the setting from. . 461
Is a control unit that controls setting values and the like necessary for the operation of the run code processing unit in accordance with an instruction from the MPU processing unit 212. An MPU bus 441 transfers a control signal 447 from the MPU of the MPU processing unit 212 and a run code processing effective area signal 446 to the run code processing unit 215.

Next, the composite pattern for print evaluation in this embodiment will be described with reference to FIG. FIG. 23A is an example of a print pattern for evaluating a printing device using a plurality of rollers in a paper feed system, and FIGS.
(F) shows a measurement area for each evaluation item in the pattern. Thus, one sheet of inspection paper 501
Printable area 502, density evaluation pattern 5
03, the pattern 504 for partial magnification, the constant pitch horizontal line 505 for paper feed evaluation are printed out, and each measurement area 506 to 511 is taken in by this print evaluation device, and the leading end resist, the left end resist, the squareness, the skewness, and the bend. And a plurality of items such as paper feed pitch unevenness, jitter, overall magnification, partial magnification, and density.

Next, an embodiment of the image clipping process will be described with reference to FIGS. 23 (a) to 23 (f). FIG.
(A) is a composite pattern diagram recorded on the inspection paper 105 for performing the above inspection. Reference numeral 502 denotes a printable area in which a density pattern 503, a partial magnification pattern 504, and a constant pitch horizontal line 505 are printed. FIG.
2B shows a print position accuracy measurement target pattern and an image processing cut-out area 50 of the composite pattern shown in FIG.
FIG. FIG. 23C is a diagram showing a pattern to be measured for linearity measurement and image processing cutout areas 507 and 508 in the composite pattern of FIG. FIG. 23D is a diagram showing a pattern to be measured for pitch unevenness measurement and an image processing cutout area 509 in the composite pattern in FIG. 22A. FIG. 23E is a diagram showing a pattern to be measured for partial magnification measurement and an image processing cut-out area 510 in the composite pattern in FIG. 23A. FIG. 23F is a diagram showing a pattern to be measured for partial magnification measurement and an image processing cut-out area 511 in the composite pattern in FIG. Then, the respective image processing units shown in FIG. 18 perform processing corresponding to the respective measurement items.

That is, the MPU processing unit 209 is operated by the stage 10
A is read by the line sensor 205 on the outward path
Image data corresponding to the image processing cut-out area 506 (FIG. 23B) is extracted from the image data output via the / D processing unit 201, and print position accuracy measurement as described later is performed. Also, the MPU processing unit 210 performs an image processing cut-out area 507 from the image data output from the A / D processing unit 201 on the outward path of the stage 103 (FIG. 23C).
Is taken out, and linear low-frequency measurement is performed. Further, the MPU processing unit 210 extracts image data corresponding to the image processing cut-out area 511 (FIG. 23 (f)) from the image data output from the A / D processing unit 201 on the return path of the stage 103, and performs density measurement. or,
The MPU processing unit 211 performs A
Image data corresponding to the image processing cut-out area 510 (FIG. 23E) is extracted from the image data output from the / D processing unit 201, and the partial magnification is measured. Also, MPU
The processing unit 212 is read by the line sensor 206,
Image data corresponding to the image processing cut-out area 508 (FIG. 23C) is extracted from the image data output via the A / D processing unit 202, and connected to the MPU processing unit 212 via the MPU bus 222. The run code processing unit 215 generates and stores the run code data from the extracted image data as described above, and the MPU processing unit 21
2 performs the measurement of the high frequency component of the straight line based on the run code data as described later. Also, the MPU processing units 213 and 21
Reference numeral 4 denotes a line sensor 207 on the return path of the stage 103.
A / D processing units 203 and 2 read by
The image data corresponding to each area of the image processing cut-out area 509 (FIG. 23D) is extracted from the image data output through the MPU bus 223 and the MPU bus 223.
The projection processing units 216 and 225 connected to the MPU processing units 213 and 214 via the CPU 26 generate and store projection data as described above, and the MPU processing units 213 and 214 generate pitch unevenness based on the projection data as described later. Perform the measurement.

As described above, each MPU processing unit receives information on the necessary image cut-out area position, the number of areas, and the thinning interval from the control CPU 200, and performs image data input, run code processing, projection processing, and the like to obtain necessary image information. And performs image processing specified in advance, and outputs processing results such as an image position and a line width to the control CPU 200.
Transfer to

Next, the thinning-out function at the time of sampling image data in this embodiment will be described. FIG. 24 is a diagram for explaining the thinning function and shows a case of low frequency component linearity measurement. In the figure, reference numeral 601 denotes inspection paper 1
05, a line image drawn in the image processing cutout area 507 on the image processing area 05, an X-direction area width (Xw) of the image processing cutout area 507, and 603, an image processing cutout area 5
07 is the Y direction area width (Yw).

FIG. 25A is a diagram schematically showing the memory contents when the image data in the image processing cut-out area 507 shown in FIG. 24 is stored in the image memory without performing the thinning process. 611 indicates a line image in the image memory;
612 is a virtual line when the line image 611 is approximated by a straight line;
Is the X direction area width as in 605, and 614 is the Y direction area width as in 606.

FIG. 25B is a diagram schematically showing the contents when the image data in the image processing cut-out area 507 shown in FIG. 24 is subjected to the thinning-out processing and stored in the image memory. Reference numeral 621 denotes a line image in the image memory, 622 denotes an imaginary line obtained by linearly approximating the line image 621, 623 denotes an X-direction area width similar to 605, and 624 denotes a Y-direction area width similar to 606. Here, the amount of image memory required when thinning out in the Y direction in FIGS. 25 (a) and 25 (b) is 1/2 ⁿ when the thinning amount is 2 ⁿ ,
Image memory is saved, information is compressed, and processing is facilitated.
In this embodiment, a virtual straight line 61 is obtained from the line images 611 and 621.
Assuming 2,622, the linearity is determined from the difference between the position of the virtual straight line and the square in the X direction, so this function is particularly effective when the change in the X direction is smaller than the change in the Y direction.

Next, the parallel processing operation for a plurality of evaluation items in this embodiment will be described. Here, the A / D processing units 201, 202, and 203 and the MPU processing unit 2 in FIG.
09, 212, 213, line sensors 205, 206,
The parallel processing performed by 207 will be described as an example.

FIG. 26 is a view for explaining an embodiment of the parallel processing as an image to be measured. Reference numeral 701 denotes a scanning direction (X direction) of the imaging apparatus (line sensor) 101 in FIG.
Reference numeral 702 denotes a moving direction (Y direction) of the stage 103.
Reference numeral 703 denotes an area occupied by absolute coordinates generated in the A / D processing units 201 to 204, and here, coordinate values 0 to 49 in the X direction.
9 shows an example when the coordinate values are 0 to 6999 in the Y direction. Reference numeral 704 denotes a composite pattern to be measured (FIG. 2
3) the pattern image on the inspection paper, 705 is the image effective area of the line sensor (X direction), 706 is the stage movement area (Y direction), 711, 712, 713, and 714
Denotes an area where the MPU processing unit 209 cuts out and processes an image, and corresponds to the area 506 shown in FIG. Reference numerals 712 and 722 denote areas where the MPU processing unit 213 cuts out and processes images.
Corresponds to the area 509 shown in FIG. 731 is M
An area where the PU 212 cuts out and processes an image,
This corresponds to the area 508 shown in FIG. Reference numeral 704 denotes an X-direction coordinate value of an area processed by each MPU processing unit, and reference numeral 741 denotes a Y-direction coordinate value of an area processed by each MPU processing unit. Here, for example, MPU
In one of the rectangular areas 711 to be cut out 209, X
The direction is within the range indicated by X1 to X2, and the Y direction is within the range indicated by Y1 to Y2. Similarly, in area 712, X
7 to X8 and Y1 to Y2, X1 to X2 in area 713
And Y5 to Y6, and X7 to X8 and Y5 in the area 714.
To Y6, X3 to X4 and Y2 to Y5 in the area 721,
In area 722, X5 to X6 and Y2 to Y5, area 7
In 31, X7 to X8 and Y2 to Y5.

FIG. 27 is a diagram for explaining the processing areas assigned to the respective MPU processing units in association with each other.
27B shows an area processed by the MPU processing unit 209, FIG. 27B shows an area processed by the MPU processing unit 213, and FIG. 27C shows an area processed by the MPU processing unit 212.

FIG. 28 is a timing chart in the X direction for cutting out each area in the parallel processing described above. Here, the logic is represented by active-low logic.
(A) shows an effective area of the line sensors 205, 206, and 207, and the A / D processing units 201, 202, and
203 outputs the X coordinate data 309 to the image bus 218 via the image bus 300. (B) is an MPU processing unit 20
An area effective signal in the X direction for cutting out the area 711 in FIG. 26 out of the nine processing areas is valid for a period from X1 to X2. (C) is an X-direction area valid signal for cutting out the area 712 in FIG. 26 of the processing area of the MPU processing unit 209, and is valid during the period from X8 to X9. (D) is an area effective signal in the X direction for cutting out the area 713 in FIG. 26 of the processing area of the MPU processing unit 209, and is effective during the period from X1 to X2.
FIG. 26E shows the processing area of the MPU processing unit 209 in FIG.
Is an area valid signal in the X direction for cutting out the area 714 of the above, and is valid during the period from X8 to X9. (F) is M
26 of the processing area of the PU processing unit 213
21 is an area effective signal in the X direction for cutting out X21.
Valid for a period from to X4. (G) is an area effective signal in the X direction for cutting out the area 722 in FIG. 26 of the processing area of the MPU processing unit 213, and is effective during the period from X5 to X6. (H) is an area valid signal in the X direction for cutting out the area 731 in FIG. 26 of the processing unit area of the MPU processing unit 212, and is valid during the period from X7 to X8.

FIG. 29 is a timing chart in the Y direction for cutting out each area during the parallel processing described above. Here, similarly, the active low logic is used. (A) shows an effective area when the stage is moved, and during the low period, the A / D processing units 201, 202, and 203 transfer the Y coordinate data 308 to the image bus 218 via the image bus 300.
Output to (B) is an area valid signal in the Y direction for cutting out the area 711 in FIG. 26 of the processing area of the MPU processing unit 209, and is valid during the period from Y1 to Y2. (C) is an area valid signal in the Y direction for cutting out the area 712 in FIG. 26 of the processing area of the MPU processing unit 209, and is valid during the period from X1 to X2. (D)
Is an area effective signal in the Y direction for cutting out the area 713 in FIG. 26 of the processing area of the MPU processing unit 209.
It is valid during the period from Y5 to Y6. (E) is an area valid signal in the Y direction for cutting out the area 714 in FIG. 26 of the processing area of the MPU processing unit 209,
Valid for a period of up to 6. (F) is an MPU processing unit 213
26 is an area valid signal in the Y direction for cutting out the area 721 of FIG. 26 out of the processing area of FIG. 26, and is valid for the period from Y2 to Y5. (G) is an area valid signal in the Y direction for cutting out the area 722 in FIG. 26 of the processing area of the MPU processing unit 213, and is valid during the period from Y2 to Y5. (H) is a valid signal in the Y direction for cutting out the area 731 in FIG. 26 of the processing area of the MPU processing unit 212, and is valid during the period from Y2 to Y5.

Here, in FIGS. 26 and 27, the cut-out positions of the areas are, for example, that the start point Y1 and the end point Y2 in the Y direction of 711 and 712 have the same coordinates, but each has a different cut-out area setting value. Needless to say, it does not matter. The same applies to the X direction. The same area may be input as an input image between the MPU processing units.
A plurality of cutout areas may overlap in the same MPU processing unit.

The operation when the overall configuration as shown in FIG. 15 has the configuration of the image processing section as shown in FIG. 18 will now be described. The stage starts moving from the origin position, and an input start trigger signal 224 (302) is input to the A / D processing unit 201 at a predetermined position. Then, A / D processing section 201 outputs the absolute coordinate data of area 703 shown in FIG. That is, 0 to 4999 in the X direction and 0 to 6 in the Y direction.
The coordinate data is output to the image bus 218 until 999. At this time, the MPU processing units 209 to 211 are instructed in advance by the control CPU 200 with respect to the image area to be cut out by the MPU processing unit with respect to the absolute coordinates. Each MPU processing unit has a program corresponding to a processing method for an input image and a method of obtaining a processing result. The line sensor 205 is driven by the A / D processing unit 201, generates a video signal, and outputs the video signal to the A / D processing unit 201. At this time, the X coordinate counter 313 counts up according to one scan of the line sensor, and the absolute coordinate data (0 to 4999 in the X direction) is output from the A / D processing unit 201 to the image bus 218. Similarly, the generation of the Y coordinate data starts after the stage start signal 224 is input to the A / D processing unit 201, and the Y coordinate counter 313 counts up every time the line sensor 205 performs one scan. A / D processing unit 201
Is output to the image bus and continues until a predetermined coordinate value is reached. In FIG. 25, the process is continued until the coordinate value changes from 0 to 6999. At this time, each of the MPU processing units 209 to 211 performs input of an image, writing to an image memory, and the like when an absolute coordinate value corresponding to an area in charge of each applies.
At this time, since each MPU processing unit operates independently, a plurality of processes are operating in parallel when viewed as an image processing system. In FIG. 26, first, 0 to 49 is set in the X direction.
One scan of 99 is completed and the Y coordinate counts up one by one. At this time, when the Y coordinate becomes Y1 and the X coordinate value becomes X1, first, it corresponds to the image cutout area, which is the area 71 of the MPU processing unit 209.
In the area 1, up to the first one line X2 in the X direction of 711 is input to the image memory 415 on the MPU processing unit 209, and when it is finished, the first one line of the area 712 in the MPU processing unit 209 is again returned. Minute input (from X7 to X8). In this way, it is 71 until the Y coordinate value becomes Y2.
In areas 1 and 712, the MPU processing unit 209 inputs an image. As described above, when the Y coordinate value becomes Y2 and the X coordinate value becomes X3, it corresponds to the area 721 which is the area of the MPU processing section 213. Therefore, the MPU processing section 213 stores the image information corresponding to its own image memory 415. input.
When the stage continues to move and the Y coordinate ends at Y6 and the X coordinate ends at X8, three M of the MPU processing units 209, 213 and 211 are set.
The necessary image information is completely input to all the PU processing units.
Each MPU processing unit performs individual processing (the same processing may be performed) when each image data has been input to the image input area in its own image memory, and after calculating each image processing result, the control CPU 200. In response to the request from the CPU, the processing result is transferred to the control CPU 200, and a series of operations ends.

Next, a method for evaluating the printing position accuracy will be described with reference to FIG. This processing is performed by the MPU processing unit 209. At S1, an image input area is set in area storage detection section 410 (FIG. 20) in MPU processing section 209. The setting area of this part is like the area 506 in FIG. Black circles (ab) in the area 506 indicate a paper edge or a measurement point of a print line. S
When the setting of the image input area is completed in 1, an input start trigger signal 30 which is a trigger signal for image input is set in S 2.
Wait until 2 turns ON. Input start trigger signal 30
Image input is started when 2 is turned on, and it is checked in step S3 whether the X and Y coordinates of the input image data are within the set area 506. The image data is stored in the image memory 415 as image data binarized at a predetermined binarization level. If the input image data is out of the set range, the process waits until image data in the set area is input. In S5, it is checked whether or not the input area has been completed. If the X and Y coordinates of the input image data are still within the set area, the process returns to S4 and is stored in the image memory 415 as image data binarized at a predetermined binarization level. Continue. If the X and Y coordinates of the input image data reach the end of the set area 506, the storage of the image data in the image memory 415 is terminated at that point, and the flow branches to S6. Next, in S6, the area number of the measurement point is designated. In the example of FIG. 23B, the area number is designated as No. 1 for the measurement at the measurement points a, c, k, and i. Next, in S7, whether the point to be measured is the paper edge or the line center is selected. FIG.
In the example of (b), measurement points i, j, k, and 1 are paper edges, and a, b, c, d, e, f, g, and h are line centers. If it is determined in S7 that the measurement point is at the center of the line, the flow branches to S8 to read out the image data of the portion corresponding to the designated area number among the image data stored in the image memory 415. The image data read out here is binarized so that the paper portion becomes 0 and the upper surface of the stage 103 on which the print line and the paper are set becomes 1.
In S9, an edge pattern of the binarized print line is searched. The data of the print line portion has a configuration in which data 1 of the paper portion continues, a plurality of 1s continue, and then 0 of the paper portion continues again. Therefore, in S10, the point at which the pattern changes from 0 to 1 in the pattern, that is, the appearance of the rising edge pattern is repeatedly confirmed. If the rising pattern is confirmed, the coordinates of the point changed from 0 to 1 in S11 are stored,
By S12, the image data is read again. S1
3. In S14, the same processing as in S9 and S10 is performed. However, in S14, the point at which the binarized data changes from 1 to 0, that is, the appearance of the falling pattern of the edge is confirmed. If the falling pattern is confirmed, the coordinate value of the point changed from 1 to 0 is stored in S15. Next, in S16, the midpoint between the rising point of the edge stored in S11 and the falling point stored in S15 is calculated, and the coordinate value is stored as the center point of the print line in S17.

Next, when the paper edge is the measurement point,
The process branches from S7 to S18 to read out the image data of the portion corresponding to the designated area number from the image data stored in the image memory 415. In S19, an edge pattern of a boundary formed between the paper and the upper surface of the stage is searched from the binarized image data. After 1 which is the data of the upper surface portion of the stage continues, 1 which is the data of the paper portion appears continuously. Therefore, in S20, the point where the data changes from 1 to 0 in the pattern, that is, the appearance of the falling pattern of the edge is repeatedly confirmed. If the falling pattern is confirmed, the result is stored in S21 with the point coordinate value changed from 1 to 0 as the position of the paper edge. Next, it is checked whether or not all the points to be measured have been completed in S22. If the measurement points still remain, the processing from S6 is repeated. If all the measurement points have been completed, the process branches to S23, and the mutual positional relationship between the points is calculated. Here, the calculation method of the mutual positional relationship is, for example, the tip resist = ay-iy and by-gy orthogonality = | (ay-by) / (ax-bx) + (cx-
dx) / (cy-dy) | × 100% skewness = | ((ay−iy) − (by−ji)) / (a
x−bx) | × 100% Parallelism = | ((ay−ey) − (by−fy)) / (a
x−bx) | × 100%.

Next, in S24, the calculation result of each evaluation item and
Compare with the minimum and maximum limits of each evaluation item,
If the calculation result is between the minimum limit value and the maximum limit value, it is determined to be non-defective in S25, and the evaluation is terminated. If the calculation result does not fall between the minimum limit value and the maximum limit value, it is determined to be defective in S26 and the evaluation is terminated.

Next, evaluation of pitch unevenness will be described.
FIG. 32A is a diagram illustrating projection of a line pattern. Reference numeral 1201 denotes a printed line pattern, and 1202 denotes a noise component existing between the line patterns. Reference numeral 1200 denotes a line length direction, and the result of adding multi-value data in this direction is projection data 1206. In the projection data 1206, a portion corresponding to the position of the line pattern 1201 appears as a peak 1205, and a background portion between the line patterns appears as a peak valley 1204. By taking this projection data, it is possible to remove the effects of noise components between the line patterns and the irregularities of the edge portions of the line patterns.
03 can be accurately extracted.

FIG. 32B is a diagram for explaining a defective state when a line pattern is printed. Reference numeral 1207 denotes a printed line pattern, and reference numeral 1212 denotes projection data. When attention is paid to the peak position, the interval between the defective portion pitch 1208 and the normal portion pitch 1211 is smaller. In the projection data 1212, focusing on the peak difference between adjacent peaks and valleys, the peak difference 1209 of the defective portion is smaller than the peak difference 1210 of the normal portion. By calculating the pitch or peak difference of the projection data from these facts, it is possible to separate the defective part from the normal part.

Next, a specific method of evaluating pitch unevenness will be further described with reference to FIG. This processing is performed by the MPU processing unit 213. At S30, MPU processing section 213
The image input area is set in the area storage detection unit 410 of the above. The setting area in this case is area 5 in FIG.
It looks like 09. When the setting of the image input area is completed, the process waits in step S31 until an input start trigger signal 302, which is a trigger signal for image input, is turned on. Image input is started when the input start trigger signal 302 is turned on, and it is checked in step S32 whether the X and Y coordinates of the input image data are within the set area 509. If so, the projection data is sent to the projection processing unit 2 in S33.
16 is stored in the projection memory 431 within the range.
Continue image input until the range of the set area comes. In S34, the end of the set area is checked. If it is still within the set range, the projection data is kept stored in the projection memory in S33, and if the input area is completed, the flow branches to S35.

In S35, the input projection data is read out, and in S36, smoothing is performed. The reason why the smoothing is performed here is to remove spike-like noise in the projection data and make it easier to determine the peak position.

Next, in S37, the peak positions of the white, ie, the background portion, and the black, ie, the line pattern portion, are detected. As a peak detection method, take the difference between adjacent projection data,
It is checked whether the sign of the difference value is positive or negative. At this time, a point at which the sign changes from positive to negative or from negative to positive is defined as a peak position. When the difference is zero, the midpoint of the zero section is set as the peak position. As a method of detecting the peak position, the position of the center of gravity of the section where the peak or the valley exists may be obtained, and the value may be used as the peak position. Next, in S38, the interval between the peaks of the adjacent line pattern portions among the peak positions obtained in S37 is calculated, and is set as the pitch interval.

Next, in S39, the variance of the pitch obtained in S38 is obtained, and in S40, the maximum and minimum pitches among the pitches obtained in S38 are obtained. At S41,
The maximum value obtained in S40 is compared with the maximum limit value of the pitch recognized as a non-defective product. If the maximum value is smaller than or equal to the limit value, the process branches to S42. If the maximum value is larger than the limit value, the process branches to S50, and at this point, it is determined to be defective. Next, in S42, the minimum value obtained in S40 is compared with the minimum pitch value recognized as a non-defective product. If the minimum value is greater than or equal to the limit value, the flow branches to S43. If the minimum value is smaller than the limit value, the process branches to S50, where it is determined that the device is defective. Next, in S43, the variance obtained in S39 is compared with the limit value of the variance of the pitch recognized as a non-defective product. If the value of the variance is smaller than or equal to the limit value, S is determined.
Branch to 44. If the variance value is greater than the limit,
The process branches to S50, and is determined to be defective at this point.

Here, when the pitch interval changes periodically, for example, when the even-numbered pitch and the odd-numbered pitch alternate, the average value of the even-numbered pitch and the odd-numbered pitch are replaced with the comparison of the maximum value and the minimum value. May be determined from the average value of the pitches of the above, and the difference may be evaluated based on whether or not the difference exceeds a reference value.

In S44, a product that satisfies the conditions of S41 to S43 is provisionally determined as a non-defective product. Here, only temporary judgment is made that even if the pitch is non-defective, if the contrast between the printed line pattern and the background part varies, it will appear as density unevenness of the entire printed image, and the print quality will deteriorate. Because there is. To perform the evaluation in this case, in S45, the peak difference between white and black, that is, the height of the adjacent valley and peak is calculated. Next, S4
In 6, the frequency distribution of the peak difference obtained in S45 is calculated. When the contrast is constant, a high frequency distribution appears at the position of a certain peak difference, and the variation of the frequency distribution is small.
Conversely, when the contrast is uneven, the height of the frequency distribution is low and the variation of the frequency distribution is large. Therefore, in S47, the height of the frequency distribution is defined as h,
H / w is calculated with the base width set to w, and is set as a contrast state value. In step S48, the contrast state value obtained in step S47 is compared with the limit value of the contrast state recognized as a non-defective product. If the contrast state value is greater than or equal to the limit value, the process branches to step S49 to determine a non-defective product. And the final determination is made, and the evaluation of the pitch unevenness ends. Also, if the contrast state value is smaller than the later value,
After branching to S50 and determining that the product is defective, the evaluation of pitch unevenness ends.

FIG. 34A shows that the contrast is constant,
FIG. 34B is a diagram illustrating a peak difference frequency distribution in a case of a non-defective product, and FIG. 34B is a diagram illustrating a peak difference frequency distribution in a case of a defective product having a variation in contrast. h1, h
2 is the maximum value w1 of each frequency distribution, w2 is the base width of the frequency distribution.

Next, evaluation of the linearity of a printed line will be described. FIG. 35A is a diagram illustrating run code data used when evaluating the high frequency component of the linearity of the print pattern. Reference numeral 1300 denotes a printed line pattern, and reference numeral 1301 denotes a scanning position at which run code data is obtained. When a line pattern such as 1300 is scanned by sequentially storing the starting point and the width of the binary graphic existing on the scanning position, the X coordinate of the starting point 1301 of the line pattern is determined by the X in the run code processing unit 215. The Y coordinate is stored in the memory 452, the Y coordinate is stored in the Y memory 453 in the run code processing unit 215, and the pattern width 1303 is stored in the width memory 454 in the run code processing unit 215. Since a noise component 1304 exists around the line pattern 1300, the maximum width limit 1306 (ΔW ₂ ) and the minimum width limit 1305 (Δ
By setting W ₁ ), a pattern such as the noise component 1304 is not sampled, and data of only a line pattern can be captured.

FIG. 33B is a diagram for explaining the principle of linearity evaluation. 1310 is a printed line pattern, 13
12 is a smoothing curve obtained when the center line of the printed line pattern is smoothed, 1313 is an approximate straight line obtained by linearly approximating the smoothed curve, and 1311 is the maximum difference between the approximate straight line and the smoothed curve. This is the maximum amplitude representing the value. The linearity is evaluated by comparing the maximum amplitude with a predetermined limit value.

A specific method for evaluating the linearity will be further described with reference to FIG. This processing is performed by the MPU processing unit 212.

First, in S60, an image input area is set in the area storage detection section 410 in the MPU processing section 212. The setting area in this case is area 5 in FIG.
08. When the setting of the image input area is completed, the process waits in step S60 until an input start trigger signal 302, which is a trigger signal for image input, is turned on. Image input is started when the input start trigger signal 302 is turned on, and X and X of the image data input in S62.
It is checked whether or not the Y coordinate is within the set area. If the Y coordinate is outside the set area, the process waits until the set area is input. If it is within the set area, the image data input in S63 is binarized at a predetermined binarization level, and a binarization pattern appearing in S64 and thereafter is examined. In S64, an appearing binarization pattern is examined. In S64, a comparison is made between the appearing binary pattern width and the minimum value limit value ΔW ₁ (1305). If the pattern width is larger than or equal to the minimum value limit value ΔW ₁ , the process proceeds to S65. S
At 67, the end of the area is checked. If the currently input image data is still within the area, the process returns to S63.
In S65, performs a comparison between the pattern width of the binary appearing the maximum width limit value ΔW ₂ (1306), the smaller pattern width than the maximum width limit value [Delta] W _2, the start point coordinates of the pattern at S66 The Y coordinate is written to the Y memory 452 and the pattern width is written to the width memory 454 in the X memory 453. If the pattern width is larger than the maximum width limit value, it is checked whether or not the area ends in S67. At S66,
After storing the pattern data, the end of the input area is checked in S67. If the currently input image data is within the set area, S63 to S66 are repeated. If the input image data exceeds the set area, the input of the binary data is terminated at that point, and the flow branches to S68.

In S68, the stored run code data, specifically, the contents of the X memory 453, the Y memory 452, and the width memory 454 are read. Based on the data read in S68, the center line of the line pattern is calculated in S69. By calculating the center line, it is possible to remove the influence of the displacement of the pattern position due to the thickening or thinning of the line pattern itself. The position coordinates of the center line can be easily obtained from the starting point of the pattern and the pattern width. Next, in S70,
The center line obtained in S69 is smoothed. Here, by further smoothing the center line as shown by the dotted line in FIG. 32 (b), it is possible to remove the influence of the unevenness seen at the edge of the pattern. Next, in S71, the smoothed data is divided into appropriate blocks, and linear approximation is performed using the smoothed data in the blocks divided in S72. In S73, a peak position is detected from the smoothed data in the divided block. Here, the peak position refers to the position of the peak or valley of the smoothed undulation. As a peak detection method, a difference between adjacent smoothed data is obtained, and it is checked whether the sign of the difference value is positive or negative. At this time, a point at which the sign changes from positive to negative or from negative to positive is defined as a peak position. When the difference is zero, the midpoint of the zero section is set as the peak position.

Next, in S74, the peak position determined in S73 is the approximate straight line 1313 determined in S72 (FIG. 13C).
The maximum value (maximum amplitude 1311) of the absolute value of the value obtained in S74 is calculated in S75. Next, in S76, the above-described steps S72 to S72 are performed for all blocks.
It is determined whether or not S75 has been completed. If all blocks have not been completed, the operations of S72 to S75 are repeated. if,
If the operations of S72 to S75 have been completed for all blocks, the process branches to S77.

In S77, the largest value among the maximum absolute values of the difference between the peak position from the approximate straight line in each block is extracted, and in S78, the maximum value is compared with the limit value. If the maximum value is smaller than or equal to the limit value, the flow branches to S79 to determine a non-defective product, and terminates the evaluation of linearity. On the other hand, if the maximum value is larger than the limit value, the process branches to S80, where it is determined that the product is defective, and the evaluation of linearity ends.

Here, a method for correcting the stage speed unevenness will be described with reference to FIG. In the evaluation apparatus of this embodiment, an image is captured by positioning the paper to be inspected on the moving stage 103 and scanning the paper under the sensor.
Therefore, if the moving speed of the stage that moves with the paper placed thereon varies, the measured image expands and contracts in the moving direction, and the true value cannot be measured. In this embodiment, both the scan start pulse of the line sensor and the output of the linear encoder 104 are counted by the Y coordinate counter 313 in the A / D processing unit in order to correct this variation. That is, the output of the line sensor is output from the A / D processing units 201 to 201.
The image data is acquired by A / D conversion at the time when the Y coordinate counter 31 is read at each timing of the scan start pulse 304 (each sample hold signal).
The value of the linear encoder 104 attached to the stage 103 counted at 3 is stored in the host computer 109.
To the internal memory. That is, as shown in FIG. 30A, the number of sensor scans (order) and the encoder value are associated with each other, and the actual movement of the stage in one sensor scan is stored. Then, when a line to be evaluated is detected from the image data, a measured value is calculated from the value in the memory.

For example, in the case of evaluating the paper feed pitch unevenness, FIG.
As shown in FIG. 1B, the captured image data is first projected in the main scanning direction, and a line to be evaluated is detected from the value. Further, the center of gravity 907 of the line is calculated, and where the center of gravity corresponds to the number of sensor scans in FIG. 30A is searched. In the example of FIG. 30B, the line centroid position 907 is the scan (N + 3.1) time,
As the measured values in this case, assuming that the encoder value of the (N + 3) th scan is E + 3 and the encoder value of the (N + 4) th scan is E + 4, (E + 3) + ((E + 4) − (E +
3) It can be calculated as x 0.1.

In this manner, the encoder value of each line to be evaluated is calculated, the pitch interval is obtained by calculating the difference between the encoder values, and the unevenness of the paper feed pitch can be evaluated without the influence of the movement speed of the stage. It is possible.

In the above-described embodiment, an example has been described in which a pattern for evaluating a printing apparatus using a plurality of rollers in a paper feed system is used, but the composite pattern is not limited to this.

FIG. 37 shows an embodiment of a composite pattern for evaluating a printing apparatus which feeds paper by one driving roller and a roller driven by the driving roller. As in the case of the composite pattern shown in FIG. 23, a plurality of measurement areas are fetched and the same items are evaluated. Performed by pattern. Therefore, the evaluation pattern does not need to be printed over the entire length of the paper, so that the printing time can be reduced, and at the same time, the evaluation time can be reduced.

The measurement positions are 12 points al to l, which are at the following positions on the paper, and the X and Y coordinates of each point are measured.

[Measurement position] i, a, e: 5th digit (14.83 mm from left end) j, b, f: 76th digit (195.17 mm from left end) k, c, g: 3rd line (upper end) L, d, h: 31st line (132.1 mm from upper end) 1 line = 4.233 mm 1 digit = 2.54 mm Note that the X coordinate and Y coordinate at each point are (a _x ,
a _y ), (b _x , b _y ),... (l _x , l _y ).

Next, the inspection items and the evaluation items will be described.

1. 1. Advanced resist: a _y -i _y , b _y -j _y Left end resist: c _x -kx

[0089]

[Outside 1]

The above calculations are performed, and each calculation result is compared with each standard value to judge pass / fail. If it is judged to be bad, a warning is displayed.

[0091]

[Outside 2] The above operation is performed for the main direction, and the result is -1m to +
It is determined whether the distance is within the range of 1 mm, and if not, a warning is displayed.

[0092]

[Outside 3] The above operation is performed for the sub-direction, and the result is from -1.7% to
It is determined whether it is within the range of + 0.3%, and if not, a warning is displayed.

7. Carriage pitch unevenness: 1 in line 10
The density histogram value is calculated for the vertical dot line in the sub-scanning direction, and the center value pitch is calculated. The center value pitch is compared with a standard value to judge the quality, and a warning is displayed in the case of a defect.

8. Unidirectional printing unevenness: 1 in lines 10 and 11
The density histogram value of the vertical dot line is calculated in the sub-scanning direction, and a positional shift of the same digit is made. It is determined whether or not the amount of displacement is within the allowable range, and if not, a warning is displayed.

9. Bi-directional printing unevenness: 1 in lines 11 and 12
The density histogram value of the vertical dot line is calculated in the sub-scanning direction, and a positional shift of the same digit is made. It is determined whether or not the amount of displacement is within the allowable range, and if not, a warning is displayed.

10. Paper feed pitch unevenness: A density histogram value is calculated for the horizontal line of one dot on the 14th to 33rd lines in the main scanning direction, and the center value pitch is calculated. The center value pitch is compared with a standard value to judge the quality, and a warning is displayed in the case of a defect.

[0097]

As described above, according to the present invention, a print pattern including a plurality of measurement areas printed on a printing object is read, and image signals corresponding to each measurement area are input to different arithmetic processing means. In addition, since each arithmetic processing unit performs arithmetic processing for evaluating a plurality of inspection items in parallel, a plurality of items must be evaluated as in the case of print evaluation in a production process of an image output device such as a printer. Even in this case, it is not necessary to output a print target for each evaluation item, and high-speed and high-precision print evaluation can be performed. Production costs can be reduced by reducing the number of output print targets for evaluation and reducing inspection time. And the quality assurance reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a print evaluation device of the present invention.

FIG. 2 is an external perspective view showing details of a part of the print evaluation device shown in FIG.

FIG. 3 is a block diagram illustrating an image memory control unit.

FIG. 4 is a diagram illustrating a case where data of a plurality of areas to be inspected is stored in an image memory.

FIG. 5 is a diagram showing an example of an evaluation pattern.

FIG. 6 is a diagram showing a measurement point area of an evaluation pattern.

FIG. 7 is a flowchart illustrating a print position accuracy evaluation method.

FIG. 8 is a diagram showing a binary signal output.

FIG. 9 is a flowchart illustrating a print linearity evaluation method.

FIG. 10 is a flowchart showing a pitch unevenness evaluation method.

FIG. 11 is a diagram showing a peak difference frequency distribution.

FIG. 12 is a diagram illustrating run code data.

FIG. 13 is a diagram illustrating projection of a line pattern.

FIG. 14 is a diagram illustrating pitch unevenness.

FIG. 15 is a diagram illustrating a print evaluation device according to a second embodiment of the present invention.

16 is a diagram illustrating a line sensor of the printing evaluation device shown in FIG.

FIG. 17 is a flowchart illustrating a print evaluation method according to the second embodiment.

FIG. 18 is a block diagram illustrating details of an image processing unit.

FIG. 19 is a block diagram illustrating details of an A / D processing unit.

FIG. 20 is a block diagram illustrating details of an MPU processing unit.

FIG. 21 is a block diagram illustrating details of a projection processing unit.

FIG. 22 is a block diagram illustrating details of a run code processing unit.

FIG. 23 is a diagram showing a composite pattern for print evaluation in the second embodiment.

FIG. 24 is a diagram showing a partial measurement area of a composite pattern.

FIG. 25 is a view for explaining the contents of image data of the measurement area shown in FIG. 24 stored in a memory;

FIG. 26 is a diagram showing a relationship between absolute coordinates on the stage and each area on the composite pattern.

FIG. 27 is a diagram illustrating a processing area assigned to each MPU processing unit in association with each other;

FIG. 28 is a timing chart showing an X-direction cutout timing for each area.

FIG. 29 is a timing chart showing a Y-direction cutout timing for each area.

FIG. 30 is a diagram for explaining speed unevenness correction of a stage.

FIG. 31 is a flowchart illustrating a print position accuracy evaluation method according to the second embodiment.

FIG. 32 is a diagram illustrating the principle of a pitch unevenness evaluation method.

FIG. 33 is a flowchart showing a pitch unevenness evaluation method.

FIG. 34 is a diagram showing a peak difference frequency distribution.

FIG. 35 is a diagram illustrating the principle of linearity evaluation.

FIG. 36 is a flowchart showing a linearity evaluation method.

FIG. 37 is a diagram showing another example of the composite pattern.

[Explanation of symbols]

 Reference Signs List 1 imaging device 2 stage 4 inspection paper 5-7 A / D conversion unit 8-11 image processing unit 13 histogram calculation unit 14 runcode calculation unit 16 control CPU 21 host computer 101 imaging device 103 stage 104 linear encoder 105 inspection paper 107 image Processing unit 109 Host computer 201 to 204 A / D processing unit 205 to 208 Line sensor 209 to 214 MPU processing unit 215 Run code processing unit 216, 225 Projection processing unit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-242343 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 29/46 G01B 11/24 G01N 21 / 84 G01N 21/88

Claims (9)

(57) [Claims] 1. A print pattern, which is printed on a printing object and includes a plurality of measurement areas corresponding to a plurality of inspection items, is read by a reading unit, and the plurality of measurement areas output from the reading unit are read. A print evaluation method comprising: inputting an image signal corresponding to each of the plurality of inspection items to different arithmetic processing means, and performing arithmetic processing for evaluating each of the plurality of inspection items in parallel by each of the arithmetic processing means. 2. An image signal output from the reading means is subjected to A / D conversion, and a digital signal obtained by the A / D conversion is subjected to arithmetic processing according to each inspection item, thereby evaluating each inspection item. 2. The method according to claim 1, wherein
Printing evaluation method described in 1. 3. The print evaluation method according to claim 1, wherein the print pattern includes a measurement area for evaluating linearity. 4. The print evaluation method according to claim 1, wherein the print pattern includes a measurement area for evaluating print density. 5. The print evaluation method according to claim 1, wherein the print pattern includes a measurement area for evaluating a partial magnification. 6. The print evaluation method according to claim 1, wherein the print pattern includes a measurement area for paper feed evaluation. 7. A reading unit for reading a print evaluation pattern including a plurality of measurement patterns according to a plurality of inspection items printed on a printing target, and a plurality of measurement patterns output from the reading unit. And a plurality of arithmetic processing means for performing arithmetic processing for print evaluation on a plurality of inspection items based on the corresponding image signals. A print evaluation apparatus, wherein the print evaluation apparatus receives an input and performs arithmetic processing for evaluating each of a plurality of inspection items in parallel by each arithmetic processing means. 8. The print evaluation pattern comprises any combination of a printable area frame pattern, a density evaluation pattern, a partial magnification measurement pattern, and a paper feed evaluation constant pitch horizontal line pattern. The print evaluation device according to claim 7. 9. The arithmetic processing unit performs A / D conversion of an image signal output from the reading unit, and performs arithmetic processing according to each inspection item on a digital signal obtained by performing the A / D conversion. The print evaluation device according to claim 7, wherein the print evaluation is performed by performing the print evaluation.