JPH0577004B2 - - Google Patents

Description

[Detailed description of the invention]

"Industrial Application Field" The present invention relates to an image inspection apparatus for inspecting the quality of images reproduced by, for example, a facsimile machine, a printing machine, or a copying machine. "Prior Art" In offices, various information devices output graphic information such as text and images. A typical example of this is a copying machine that copies original documents. A copying machine forms an electrostatic latent image on a photosensitive drum, reads image information using an image sensor such as a CCD, and develops the image using a developing device, or uses a recording head such as a thermal head. The image is reproduced on the paper. When designing such information devices or shipping these information devices from factories, reproduced images are inspected. There are two types of such tests: (i) Inspection of whether the information equipment operates normally according to predetermined procedures and reproduces images. (ii) checking that the quality of the reproduced images is within market acceptance or specifications established when the equipment was designed; For example, in the case of a copying machine, the inspection items include the position of the image relative to the copied paper, the density of the image relative to the original, and the resolution. The inspector uses a scale, a magnifying lens, a measuring device, or visually inspects the copier to check whether each process in the copier is working properly and to check for errors in image reading and toner image transfer position. Determine if there are any. In the case of copying machines, the latter inspection is also performed by an inspector. That is, the quality of the image is determined by the inspector directly comparing the image copied on the paper with the sample. In the conventional inspection as described above, the inspector is the main person, and the following problems have arisen. (i) Measured values or test results changed when different testers were used. (ii) Even for the same tester, the measured values or test results changed due to familiarity with the test or the psychological influence of the previously tested test subject. (iii) Measured values or test results also changed due to physical or mental fatigue of the examiner. In order to avoid such drawbacks, an image inspection device that automatically performs inspection has been proposed (Japanese Patent Application Laid-Open No.
59-10345 and JP-A-59-10346). This image inspection apparatus is provided with a table on which an object to be inspected having an image is positioned and placed. The object to be inspected is set on this table, and the detection section is placed opposite to it. Then, the detection data output from this detection section is supplied to a data processing section, and the position, density, and resolution of the image are digitized based on the detection data. FIG. 17 shows a table on which an object to be inspected is placed in this proposed apparatus.
An L-shaped guide 201 is arranged on this table so that the end of the object to be inspected, such as copy paper, can be positioned. Suction holes 203 are arranged in a grid pattern on the entire surface of the table 202. Each suction hole 203 is connected to a vacuum pump (not shown). In this device, after the end face of the object to be inspected is placed along the guide 201, the vacuum pump is operated and the object to be inspected is suctioned and fixed onto the table 202 by its suction pressure. In this state, image inspection is started. ``Problems to be Solved by the Invention'' However, with this proposed image inspection apparatus, when paper on which a chart has been copied (hereinafter referred to as copy paper) is used as the inspection object, for example,
Positioning with respect to the region to be measured becomes inaccurate, and sometimes the optical density measurement work is completely wasted. This will be explained specifically. FIG. 18 shows an example of a chart for checking the copy status. This chart 204 includes a pattern 205 for resolution inspection, a pattern 206 representing various shadings for inspecting optical density, and the like. When this chart 204 is set on a platen (not shown) of a copying machine and a copy is made, the position where the image is copied on each copy sheet may be shifted to a considerable extent depending on the copying machine. Also, for example, if the copy magnification is not set accurately, the positions of the patterns 205 and 206 will be out of alignment. FIG. 19 is a slightly exaggerated representation of a copy sheet with such an error. This copy paper 207 is moved by a guide 20 as shown in FIG.
Even if the end surface is fixed along the pattern 1 and the predetermined pattern positions 208 and 209 are optically scanned, a portion different from the patterns 205 and 206 may be inspected. For example, even if positioning is performed with respect to a pattern for resolution measurement consisting of a plurality of parallel lines, the copy paper 207
If the pattern is set at a relative tilt, the angle at which this pattern is scanned will be tilted, causing a problem in that the determined resolution will include an error. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image inspection apparatus that can accurately detect a measurement location placed on a holding means and enable highly accurate measurement. "Means for Solving the Problems" In the present invention, (a) an original image showing at least two standard measurement points and an inspection pattern used for inspecting image information is projected at an arbitrary reduction ratio; A holding means for holding a reproduced sheet-like object to be inspected; and (b) a storage means for storing the standard measurement points and the expected position of the inspection pattern relative to the planned placement position of the object to be inspected in a coordinate system on the inspection side. (c) position measuring means for scanning the vicinity of the standard measurement points stored in the storage means and measuring the location of the standard measurement points; and (d)
Conversion information for converting between the coordinate system on the inspection object side and the coordinate system on the inspection side based on the relationship between the respective existing positions of at least two measured standard measurement points and their respective positions in the inspection side coordinate system and (e) a position for calculating the position on the object to be inspected where the test pattern is predicted to exist based on the conversion agent information and the expected position of the test pattern stored in the storage means. An image inspection apparatus is provided with a prediction means and (f) a measurement means for measuring image information at a position predicted by the position prediction means. That is, in the present invention, for example, when inspecting an image obtained by copying a predetermined chart using a copying machine, an original image or a chart with at least two standard measurement points and an inspection pattern used for inspecting image information can be arbitrarily used. A sheet-like object to be inspected or a copy reproduced by projection at a magnification of 1 is held in a holding means, and is read by a reading device to inspect the image. At this time, the positions of two or more standard measurement points are measured by the position measuring means and compared with the values stored in advance in the storage means to determine the magnification and retention of the image reproduced on the inspected object. Discrimination of positional deviation or rotation, etc. Then, the calculation means calculates conversion information for converting the coordinate system on the inspection object side and the coordinate system on the inspection side, and based on this, the position prediction means determines the position of the inspection pattern. Performs a prediction calculation to determine whether it exists. As a result, even if the reduction ratio etc. are undetermined, the position where the inspection pattern is predicted to exist can be accurately determined based on the expected existence position stored in advance in the storage means, and by reading the image information at this position, It becomes possible to measure the inspection pattern. "Example" The present invention will be described in detail with reference to Examples below. Outline of Apparatus FIG. 1 shows the external appearance of the optical density measuring apparatus for image inspection according to this embodiment. This optical density measurement device for image inspection includes an inspection section 1, a computer section 2,
and a printer section 3. Of these, the inspection section 1 is a section that continuously inspects copy paper 4 as an object to be inspected. The inspection section 1 includes a supply tray 5 and a discharge tray 6. When inspecting a copying machine, a desired chart is set in the copying machine, and copy sheets 4 obtained thereby are stacked on a supply tray 5 as shown. The copy sheets 4 are fed one by one into a cylindrical chart holder 8 by a feed roller 7.
The surface of the chart holding section 8 is covered with an insulating film, and the copy paper 4 is electrostatically attracted to this surface by a charging operation by an electrostatic charge supply device (not shown). In this state, an image inspection of the copy paper 4 as the object to be inspected is performed. At this time, a placement position detection device, which will be described later, detects the location of the standard measurement location, based on which the location of the inspection location is predicted, and the desired image inspection is performed at that location. The copy paper 4 that has been inspected is peeled off from the chart holder 8 by a peeling mechanism that will be described later. The peeled copy sheets 4 are sequentially discharged onto the discharge tray 6. The inspection section 1 is equipped with an operation display panel 9, which displays a power switch 11, movement keys 12 used to manually specify the pattern of the object to be inspected, and concentration data as measurement results. A display 13 is arranged. The computer section 2 can be configured by a commercially available computer, and performs identification of inspection items, processing of data such as concentration data, and various displays. This part is equipped with a keyboard 15 as an input means, a CRT 16 as a display means, a disk drive device 17 for driving a floppy disk, and an internal CPU for data processing.
(central processing unit) etc. are installed. The printer section 3 is a section that outputs test results and the like, and in this embodiment a dot printer is used. FIG. 2 shows an outline of the inspection section of this optical density measuring device for image inspection. This inspection section 1
A shaft 21 for rotating the feed roller 7 receives driving force from a feed roller drive motor 23 via a chain 22. The supply tray 5 is adapted to be given a force to move upward by the excitation of a solenoid (not shown), and at the time of this excitation, the top layer surface of the copy paper 4 as the object to be inspected comes into contact with the feed roller 21. When the feed roller 21 rotates by a predetermined amount in this state, only one sheet of copy paper 4 in the uppermost layer is fed out. Prior to this feeding, the surface of the chart holder 8 is uniformly charged by a charging mechanism (not shown). As a result, the sent copy paper 4 is electrostatically attracted to the chart holding section 8. The rotation of the cylindrical chart holder 8 in the circumferential direction (Y-axis direction) is performed by the driving force of a chart holder drive motor 26 connected to a decelerator 25 . In this embodiment, the outer diameter of the chart holding part 8 is the diameter
162.77 mm, the step angle of the chart holder drive motor 26 was 1.8 degrees, and the reduction ratio of the speed reducer 25 was 1/256. As a result, the chart holder drive motor 26 is driven one step, and the surface of the chart holder 8 is increased by 10 μm in the Y-axis direction.
You will only have to move. Control of the rotational position of the chart holder 8, that is, the position control in the Y-axis direction, is performed using a point detected by a photo sensor 28 in a notch 27 provided at the end of the cylinder as a reference point. A ball screw 32 rotated by an X-axis stepping motor 31 is arranged above the chart holding part 8 so that its axis is parallel to the rotation axis of the cylindrical chart holding part 8. The optical head mounting block 33 has its Y-axis direction movement hole 34.
is screwed together with the ball screw 32. Therefore, when the X-axis stepping motor 31 rotates,
It is guided by two guide bars 35 and 36 arranged parallel to the ball screw 32 to move in the X-axis direction. In this embodiment, the pitch of the ball screw 32 is 5 mm. By setting the step angle of the X-axis stepping motor 31 to 0.72 degrees, the optical head mounting block 33 moves by 10 μm in the X-axis direction with one step drive. Two limit switches 37 and 38 are arranged in the X-axis direction to limit the range of movement of the optical head mounting block 33. A density detection section 41, which will be described next, is attached to the optical head mounting block 33. A magnifying eyepiece lens 42 is also attached to the density detection unit 41, so that the position of the image captured by the objective lens 43 can be confirmed during focus adjustment and especially during manual operation. FIG. 3 shows the optical structure of the optical head. The concentration detection section 41 includes a tungsten lamp 51 for illumination. The light emitted from the tungsten lamp 51 is focused by the illumination lens 52, and the measurement site 53 of the chart holder 8 is illuminated. The reflected light from the measurement site 53 is reflected by the objective lens 4.
3, and is split into two directions by a prism 54 equipped with a semi-transparent mirror (beam splitter). One of the branched lights is reflected by a mirror 55, passes through a measurement field of view adjustment mechanism 56, has its wavelength component corrected by a color correction filter 57, and enters a photomultiplier tube 58. Here, the measurement field of view adjustment mechanism 56 includes an aperture plate 59 and a field lens 6 in the optical path.
1 is placed. The aperture plate 59 is a plate provided with a rectangular opening as shown in FIG. This 50 μm x 2500 μm opening area contains 5 images of the measurement site on the copy paper.
The image is magnified twice as much. Then, the light beam reflected from a rectangular area (FIG. 4) with a long side of 500 μm and a short side of 10 μm on the chart, that is, on the copy paper 4 in this embodiment, passes through this opening and enters the photomultiplier tube 58 described above. It will be incident. The aperture plate 59 is an aperture plate rotation solenoid 62
The longitudinal direction of the opening can be set at any desired angle. The other light branched by the prism 54 is
The traveling direction is changed by the roof-shaped prism 64, and an erect image is formed on the observation screen 65. The image of the measurement site 53 thus formed can be enlarged and observed using the magnifying eyepiece 42. Circuit Configuration of Optical Density Measuring Device for Image Inspection (Principle Configuration of the Device) First, the fundamental configuration of the circuit of the optical density measuring device for image inspection will be explained. The following FIG. 5 shows an outline of the circuit configuration of the optical density measuring device for image inspection. This device is equipped with external signal input means 72 for instructing desired inspection items. The measurement control means 73
According to the inspection item indicated by the external signal input means 72, the position and type of the pattern to be inspected and the inspection processing procedure are set. The pattern information storage means 74 stores the pattern to be inspected in the object to be inspected, and the processing procedure storage means 75 stores the inspection processing procedure for the pattern to be inspected. The measurement means 76 scans the surface of the object to be inspected under the control of the measurement control means 73 and detects the image density. The arithmetic processing means 78 performs arithmetic processing on the data obtained from the measuring means 76 according to a processing procedure instructed by the measurement control means 73. The test results obtained thereby are outputted by the output means 83.
The output means 83 is typically the printer section 3 shown in FIG. 1, but the test results can also be displayed on the CRT screen of the computer section 2. The operation of this optical density measuring device for image inspection will be explained in more detail. In the optical density measurement apparatus for image inspection, the type of the object to be inspected and the inspection items are encoded by the external signal input means 72 during inspection. The chart code 84 for identifying the chart copied to the object to be inspected and the inspection item code 85 representing the inspection item are transmitted to the measurement control means 73.
sent to. The measurement control means 73 sends the chart code 84 to the pattern information storage means 74. The pattern information storage means 74 is a chart code 84.
A pattern code 86 representing the pattern to be inspected included in the chart represented by , and a representative point position 87 representing a representative position of the pattern to be inspected are output. Of these, the pattern code 86 is sent to the processing procedure storage means 75 together with the inspection item code 85, and the image density detection format 88 corresponding to the inspection item and pattern to be inspected and the arithmetic processing code 89 representing the arithmetic processing procedure are used for measurement control. means 73
will be loaded into. At this stage, the type of pattern to be inspected required for inspection, the positional information of the pattern on the copy paper, and the results corresponding to the image density detection method and inspection items for the pattern are calculated. Information regarding the method is set in the measurement control means 73 in a coded state. Among these pieces of information, a representative point position 87 representing the coordinates of the position where the pattern exists and an image density detection format 88 are sent to the measuring means 76.
The measuring means 76 moves to the representative point position 87 instructed by the measurement controlling means 73 and detects the image density to be measured according to the image density detection format 88. The detection result is the concentration data column 91
It is output to the arithmetic processing means 78 as . At the end of the density data string 91, an end signal 92 is added to instruct the start of arithmetic processing. When the arithmetic processing means 78 receives the end signal 92, it selects a corresponding arithmetic processing routine based on the arithmetic processing code 89 previously supplied from the measurement control means 73. This arithmetic processing routine is then loaded into the internal arithmetic processing routine memory area. In the arithmetic processing means 78, the density data string 91 described above is stored in a density data string memory area. The arithmetic processing means 78 processes this concentration data string 91 using the routine loaded into the arithmetic processing routine memory area, and supplies the results corresponding to the test items to the output means 83 as the test results 93.
The output means 83 will output this content. The image density detection and density data arithmetic processing operations described above are sequentially performed for all patterns to be inspected that are preset in the measurement control means 73. The arithmetic processing means 78 not only performs arithmetic processing on each pattern, but also performs statistical processing of the arithmetic processing results corresponding to all set patterns to be inspected. In this way, the desired inspection results for the object to be inspected can be obtained. (Configuration of External Signal Input Means) Next, the configuration of the external signal input means will be explained using FIG. 6. The external signal input means 72 includes encoding means 101. Chart name 102 and inspection item 103 input by the operator are encoded by this encoding means 101. When the code type discrimination means 104 receives the coded information,
This is divided into chart code and inspection item code. The code control unit 105 then outputs the chart code 84 and test item code 85. (Structure of Pattern Information Storage Means) FIG. 7 shows the structure of the pattern information storage means. The pattern information storage means 74 supplies the chart code 84 to the pattern information storage position retrieval means 107. The pattern information storage position search means 107 searches for the position of the pattern to be inspected and sends it to the pattern information storage unit 108 as a point 109. FIG. 8 shows the inside of the pattern information storage section. The pattern information storage unit 108 stores as data the pattern codes of all the objects to be inspected in the corresponding chart using the chart code as a key, and the representative point positions of the respective patterns represented by these pattern codes. ing. In this figure, for example, for chart code “XXX”, there are three pattern codes a,
a and b are prepared. This is this chart
This means that two types of patterns specified by pattern codes a and b are displayed on the chart specified by the code "XXX", and the coordinates of the three patterns in total are at the representative point position. It is as shown. The pattern represented by the pattern code a is, for example, a resolution measurement pattern (not shown) in the Electrophotography Society Test Chart "No. 1-R 1975". In this test chart, this pattern is placed in the upper left and lower right parts. The pattern represented by pattern code b is a pattern for density measurement in this electrophotographic society test chart. In this test chart, various density samples are displayed in a row at the bottom, forming a pattern for density measurement. The pattern information output means 110 uses a pointer 109 to output the contents stored in the pattern information storage section 108 from the pattern information storage position search means 107.
Read from the position indicated by. The read contents are all pattern codes related to one chart code indicated by pointer 109 and their representative point positions. Pattern code 86 and representative point position 87 for it
The combination of measurement control means 73 shown in FIG.
are sequentially read out under the control of the measurement control means 7.
3 is sent inside. (Configuration of processing procedure storage means) Next, the contents of the processing procedure storage means 75 are shown in FIG. The processing procedure storage means 75 contains the inspection item code 8.
5 and pattern code 86 are provided. Of these, test item code 85 is detected by test item code detection means 112, and pattern code 86 is detected by pattern detection means 113. Test item code detection means 112
The detection result of the pattern detection means 113 is outputted as a first pointer 114 to the processing code storage means 115, and the detection result of the pattern detection means 113 is similarly outputted as the second pointer 115 to the processing code storage means 116. FIG. 10 shows the contents of the processing code storage means. The processing code storage means 116 stores (i) an arithmetic processing code, (ii) a pattern code, and (iii) an image density detection code for each inspection item code. The first pointer 114 output from the above-mentioned test item code detection means 112 specifies a test item code for specifying the test item. Then, the second pointer 115 output from the pattern detection means 113 selects the arithmetic processing code in that inspection item code.
In the example shown in FIG. 10, the image density detection specified by the image density detection code "A" and the calculation processing specified by the calculation processing code "A" are performed for the pattern specified by the pattern code "a". I know it will be done. two pointers 114, 11
The code content specified by 5 is temporarily stored in a storage area within the processing code storage means 116. Returning to FIG. 9, the explanation will be continued. The inspection procedure search means 117 reads out the image density detection code 118 stored in the processing code storage means 116. In the example shown in FIG. 10 described above, the image density detection code 118 is "a". Based on this, the third pointer 119 as address information is output to the inspection procedure storage means 121. FIG. 11 shows the contents of the inspection procedure storage means. The inspection procedure storage means 121 stores image density detection formats for each image density detection code. There are multiple sets of image density detection formats, each of which is stored in block units. The contents of these block units are, for example, (i) measurement start position, (ii) direction, (iii) interval, (iv) total number of points,
(v) It is in the slit direction. Here, (i) the measurement start position is shown as a relative representative point. As described above, the representative point is indicated by the coordinates that serve as a reference for each pattern, whereas the counter representative point is the difference between the coordinate value of the starting position and the coordinate value of the representative point when scanning the pattern. (ii)
The direction is the scanning direction, and there are two types of directions: the X-axis direction and the Y-axis direction. (iii) Interval is the sampling interval for concentration detection, and (iv) Total number of points is the total number of sampled data. (v) The slit direction refers to the direction of the opening of the aperture plate 59 shown in FIG. In this embodiment, the aperture is set parallel to the X-axis or parallel to the Y-axis rotated 90 degrees therefrom. The third pointer 119 specifies the image density detection code. In the example shown in FIG. 11, the image density detection code "a" is selected. The first code output means 122 reads out the image density detection format 88 selected by the third pointer 119 and supplies it to the measurement means 76 under the control of the measurement control means 73 shown in FIG. On the other hand, the second code output means 123
The arithmetic processing code 89 is read from 6 and is similarly supplied to the arithmetic processing means 78 under the control of the measurement control means 73. (Configuration of Measuring Means) The following FIG. 12 shows the contents of the measuring means. The measuring means 75 can be roughly divided into three parts: (i) an image density detection section, (ii) a detection aperture control section, and (iii) a moving section. Measurement output terminal 75
Then, based on the image density detection format 8 supplied from the measurement control means 73, the image density is detected in a predetermined format by moving over the object to be inspected (in this embodiment, the copy paper 4 on which the chart has been copied). I will do it. That is, the measurement control means 73
Image density detection format 88 supplied from
(See Figure 11) is the data sampling control section 1
Based on the format 88 that is supplied to the image forming apparatus 31 and decoded here, the image density detection section, the detection aperture control section, and the moving section are controlled. By the way, the data sampling control unit 131
The current position of the light receiving means 133 is known from data 133 obtained from the drive control section 132. Therefore, the data sampling control section 131
calculates the amount by which the light receiving means 133 should be moved by comparing it with the measurement start position obtained from the image density detection format 88. Data 134 regarding the determined movement amount etc. is sent to the drive control section 132. The drive control unit 132 calculates the amount of movement in the X-axis direction and the amount of movement in the Y-axis direction based on the data 134,
X-axis direction drive signal 1 with the number of pulses corresponding to these
35 and a Y-axis direction drive signal 136. The X-axis direction drive signal 135 is supplied to the X-axis stepping motor 31, and the Y-axis direction drive signal 13
6 is supplied to a chart holder drive motor 26 (see FIG. 2) which also serves as a stepping motor. As already explained, the concentration detection section 41 (FIG. 2) is moved in the X-axis direction by the X-axis stepping motor 31. Also, the chart holding part drive motor 2
6 rotates the drum-shaped chart holder 8 in the Y-axis direction, and the light receiving means 133 consisting of a photomultiplier tube 58 and the like moves to a desired measurement position. The data sampling control section 131 then decodes the image density detection direction, sampling interval, total number of sampling points, and slit direction. First, compare the opening direction with the current opening direction,
An angle signal 138 representing the comparison result with the designated angle is output. Angle signal 138 is provided to an angle signal generator 139. Angle signal generator 139
supplies a control signal 141 to the aperture plate rotation solenoid 62 (see FIG. 3) to rotate the aperture plate 61 by a desired angle. When the setting of the light receiving means 133 is completed as described above, the data sampling control section 131 sets the total number of points obtained from the image density detection format 88 in a counter (not shown) in the control section. Then, the image density detection direction and the sampling interval are outputted to the drive control section 132 as data 134 and set. The drive control section 132 moves the concentration detection section 41 or the chart holding section 8 by a predetermined amount according to the designated detection direction. By the way, the detection output 143 outputted from the light receiving means 133 is amplified by an amplifier 144 in the image density detection section, and the output 145 is logarithmically converted by a logarithmic converter 146. Conversion output 147 is provided to A/D converter 148. The A/D converter 148 is supplied with an A/D signal 151 from an A/D signal generator 149 for specifying the time at which A/D conversion is to be performed. A/D signal generator 14
9 is the A/D signal 1 by the A/D start signal 152 supplied from the data sampling control section 131.
However, the output of a counter (not shown) in the data sampling control section 131 is used as the A/D start signal 152. That is, this counter is preset with a count value corresponding to the measurement start position, and the count value increases as the light receiving means 133 starts moving. When the count value of the counter reaches the preset value, an A/D start signal 152 is output. When A/D conversion is finished,
A/D signal generating section 149 outputs end signal 153. When the data sampling control section 131 receives the end signal 153, it manages the above-mentioned counter and instructs the drive control section 132 to move the light receiving means 133, and if necessary, starts the next A/D at a predetermined timing. A signal 152 will be output. In this way, it becomes possible to manage the sampling interval of concentration data. On the other hand, when A/D conversion is instructed by the A/D signal 151, the A/D converter 148 outputs 1
47 is converted from analog to digital. The converted density data 154 is sequentially stored in an image density buffer 155. Stored concentration data 154
is supplied to the arithmetic processing means 78 as a concentration data string 91, and is subjected to arithmetic processing. Now, when the sampling of the concentration data progresses and the built-in counter counts a certain value as the final value, the data sampling control section 131 outputs an end signal 156 to the measurement control means 73.
When the measurement control means 73 receives this end signal 156, it supplies data for the next block to the data sampling control section 131 as an image density detection format 88. In this way, concentration data is collected for each part to be measured. (Configuration of arithmetic processing means) FIG. 13 shows the configuration of the arithmetic processing means. The calculation processing means includes a calculation control section 161. The calculation control unit 161 is supplied with the calculation processing code 89 from the measurement control means. The arithmetic processing code 89 is a code representing the arithmetic processing procedure. The calculation control unit 161 uses this calculation processing code 8.
9, and the result is arithmetic processing code 16
2 is supplied to the arithmetic processing address search means 163. The arithmetic processing address search means 163 uses the arithmetic processing code 162 to search the arithmetic processing storage section 164.
Perform a search. In the calculation processing storage unit 164,
A group of arithmetic processing data necessary for various tests is stored. When the arithmetic processing address search means 163 moves the pointer pointer 165 to the start address of the corresponding memory area by searching, it sends an end signal 166 to the arithmetic control section 161. After receiving the end signal 166, the arithmetic control unit 161 receives the start signal 1.
67 is generated and supplied to the loader starter 168. When loader starter 168 receives activation signal 167, it generates load signals 169 and 171. (i) A series of arithmetic processing contents 172 indicated by the pointer 165 in the arithmetic processing storage section 164
and (ii) image density buffer 155 (12th
The concentration data string 91 stored in the file (see figure) is loaded into the working area 174. After loading, the loader starter 168 supplies a start signal 175 to the working area 174 to activate it and transfer control to the working area 174 itself. At the same time, the working area 174 executes desired arithmetic processing on the concentration data string 91. The result is stored in the calculation result output buffer 177 as the calculation result 176. The output means 83 shown in FIG.
Input as and visualize. Details of Placement Position Detection Device In this optical density measurement device for image inspection, the copy paper 4 is first held in the chart holder 8, and after its position is determined, the density is measured for each pattern. Therefore, positioning with respect to copy paper 4 will be explained next, and then density measurement work for each pattern will be explained. (Positioning for each measurement site) In order to measure the image from the copy paper on which the chart has been copied, the objective lens 43 of the optical head must be
must accurately capture the target measurement area. By the way, if the density detection unit 41 side is unilaterally set at a predetermined coordinate position, an error of approximately ±5 mm from the desired position on the copy paper 4 will occur. This is due to the following reasons. (i) Misalignment that occurs when a chart is copied using a copier. As already explained, this may include errors in positioning (registration misalignment) between the copy paper 4 and the photosensitive drum of the copying machine, and errors in setting the magnification. Contains errors caused by skew (rotation) during transportation. (ii) Misalignment when set in chart holder 8. This is a deviation that occurs when the copy paper 4 sent out from the supply tray 5 is set in the chart holder 8, and is caused by an error in the setting of the supply tray 5 or a misalignment in position alignment when the copy paper 4 is sent out. do. In this embodiment, the target position can be reached with an accuracy of ±0.5 mm. For this purpose, the 14th
As shown in the figure, position detection patterns 192 and 193 are arranged at, for example, two positions on a chart 191 used in an optical density measuring device for image inspection. These position detection patterns 192, 193
The coordinates of are known for each chart type by the optical density measuring device for image inspection. Let the coordinates of these patterns 192 and 193 on the chart be (x ₁ ,
y ₁ , x ₂ , y ₂ ). The device uses these coordinates (x ₁ , y ₁ , x ₂ , y ₂ ) to scan the copy paper 4 around it, detects changes in the density of the image, and detects changes in the copy paper 4 on the machine side. Detect the position of. Let the coordinate values detected on the device side be (X ₁ , Y ₁ , X ₂ , Y ₂ ). By assembling the relational expressions for both coordinate systems (x, y) and (X, Y), the actual position (X ₀ , Y ₀ ) corresponding to the coordinates (x ₀ , y ₀ ) of the pattern to be measured can be determined. This coordinate value (X ₀ , Y ₀ ) is used to cause the density detection unit 41 to reach the target image area. (Coordinate correction using two standard measurement points) FIG. 15 is for explaining the principle of coordinate correction that enables desired positioning using two standard measurement points. In this figure, the X-axis and Y-axis are coordinates on the image inspection device, and these will be referred to as absolute coordinates. The x-axis and y-axis are coordinates on the chart, and will be referred to as chart coordinates. Furthermore, the x'-axis and the y'-axis are coordinates on the copy paper as the object to be inspected, and these will be referred to as the coordinates of the object to be inspected. Assuming that the chart is copied at a copying magnification of m, the coordinates of the object to be inspected (x', y') and the chart coordinates (x, y) are in the relationship expressed by the following equation (1). x'=mX y'=mY...(1) The inclination of the inspected object coordinates (x', y') with respect to the absolute coordinates (X, Y) is θ, and the origin of the inspected object coordinates on the absolute coordinates is (DX , DY). Generally, if an arbitrary point (x ₁ ′, y ₁ ′) in the coordinates of the object to be inspected and its corresponding absolute coordinates are (X ₁ , Y ¹ ), then
The relationship between the two is as follows. X ₁ = x ₁ ′cosθ−y ₁ ′sinθ+DX Y ₁ =x ₁ ′sinθ−y ₁ ′cosθ+DY Therefore, any point in chart coordinates (x ₁ , y ₁ )
When the absolute coordinates corresponding to are (X ₁ , Y ₁ ), the relationship between the two is expressed by the following equation (2). X ₁ =m(x ₁ cosθ−y ₁ sinθ)+DX Y ₁ =m(x ₁ sinθ−y ₁ cosθ)+DY (2) This equation (2) can also be expressed as follows. x ₁ = [(X ₁ −DX) cosθ + (Y ₁ −DY) sinθ]/m y ₁ = [(Y ₁ −DX) cosθ − (X ₁ −DX) sinθ]/m …(3) Chart coordinates (x, y) and absolute coordinates (X, Y)
When performing coordinate transformation between the two, the following five coordinate transformation parameters are required. m, sin θ, cos θ, DX, DY Therefore, as shown in Fig. 14, the coordinates (x ₁ , y ₁ , x ₂ , y ₂ ) of the two position detection patterns 192 and 193 on the chart are clues. The absolute coordinates (X ₁ , Y ₁ , X ₂ , Y ₂ ) on the device side are detected as follows. Using this result, five parameters are determined as follows.

[Formula] sinθ=(x ₁ −x ₂ )(Y ₁ −Y ₂ )−(y _{1
−y 2} ) (X ₁ −X ₂ )/(x ₁ −x _{2 )} ² + (y ₁ − _{y 2} ) _{2 cosθ} =(x _{1 −}
−y ₂ ) (Y ₁ − Y ₂ ) / (x _{1 −} x ₂ ) ² + (y ₁ − y ₂ ) ₂ DX=α ₁ / (x ₁ − x ₂ ) ² + (y ₁ − y ₂ ) _{2However , α 1} ⁼ _{_} ^_ _{_ _ _ _ _ _} ^_ _{_} ^_ _{_ _ _ _ _ _} y ₂ −x ₂ y ₁ )−Y ₂ (x ₁ y ₂ −x ₂ y ₁ ) DY=α ₂ /(x ₁ −x ₂ ) ² +(y ₁ −y ₂ ) _2where α ₂ =Y ₁ (x ₂ ² +y ₂ ² −x ₁ x ₂ −y ₁ y ₂ ) +Y ₂ (x ₁ ² +y ₁ ² −x ₁ x ₂ −y ₁ y ₂ ) −X ₁ (x ₁ y ₂ −x ₂ y _{1 )} +X ₂ (x ₁ y ₂ −x _{2 y 1} ) Therefore, by using these five parameters, the image inspection device can Its position (X _i , Y _i ) on the copy paper 4 at the top can be determined. FIG. 16 shows this procedure. When the copy paper 4 is automatically set in the chart holder 8 shown in FIG. 1, the coordinates of the position detection patterns 192 and 193 shown in FIG. Detection section 41
moves. Then, reading scanning is performed with some margin, and the position of this position detection pattern is measured. When this is completed, position measurement is also performed for the second position detection pattern (step in FIG. 16). The data sampling control section 131 in the computer section 2 is as follows:
Based on this, the five parameters described above are calculated (step). Thereafter, the coordinates of the representative point position and the coordinate values of the paired representative point are called for one of the patterns to be inspected (step).
By adding the coordinates of the representative point to the coordinates of the representative point position, the coordinates of that point on the chart can be determined. The chart coordinates are converted into absolute coordinates using the five parameters determined previously (step). Thereafter, the concentration detection section 41 is moved to the representative point serving as the measurement start point (step). Measurement is started in this state (step). Specifically, the aperture plate 59 is oriented in a predetermined direction, the optical head is relatively moved in the X-axis direction or the Y-axis direction, and images are sampled. The measurement results are
It is displayed on the CRT 16 or display 13 as necessary (step). After completing the measurement for one pattern,
It is determined whether a pattern to be measured exists (step). When the next measurement is to be performed on the same copy sheet 4, its coordinates are read out (step) and the same operations as described above are performed. In this way, density measurements are performed for each requested pattern. When all measurements are completed for one copy paper 4 (no copy paper), this copy paper 4 is discharged to the output tray 6 and the next copy paper is sent out from the supply tray 5. In this state where the copy paper 4 to be measured remains (step: present), the position of the standard measurement point is first determined for the newly set copy paper 4 (step), and then the position of the standard measurement point is determined as described above. Measurements are made for each pattern during operation (step ~). When the measurement work has been completed for all of the copy sheets 4 scheduled for measurement (step; N), all inspections have been completed. "Modification" Above, we have explained the method of measuring two predetermined points and arriving at the predicted position.
It is also possible to measure points and arrive at a desired position based on the results. When measuring three points, the amount of expansion and contraction of the object to be inspected in the X-axis direction and Y-axis direction can be determined by measuring the position detection patterns placed at three locations. It becomes possible to reach the point more accurately. Furthermore, by measuring four or more points, it is possible to approximately calculate the local expansion and contraction of the object to be inspected.
Furthermore, it is possible to reach the target point with high precision. Next, for reference, six parameters obtained by measuring three points are shown. However, here, m _x is the magnification of the object to be inspected in the X-axis direction with respect to the chart, and m _y
is the magnification of the object to be inspected relative to the chart in the Y-axis direction.

【formula】

[Formula] sinθ=(x ₁ −x ₃ )(Y ₁ −Y ₃ )−(y _{1
−y 3} ) (X ₁ −X ₃ )/(x ₁ −x _{3 )} ² + (y ₁ − _{y 3} ) ² _cosθ =(x _{1 −}
−y ₃ ) (Y ₁ − Y ₃ ) / (x _{1 −} x ₃ ) ² + (y ₁ − y ₃ ) ² DX=α ₃ / (x ₁ − x ₃ ) ² + (y ₁ − y ₃ ) ^2However _{, α 3 =} X _{1 ( x 3} ² ₊ y ₃ ² _{−x 1 x} ³ _{−y 1} ^y _{23 + 3} −x ₃ y ₁ )−Y ₃ (x ₁ y ₃ −x ₃ y ₁ ) DY=α ₄ /(x ₁ −x ₃ ) ² +(y ₁ −y ₃ ) ^2However , α ₄ =Y ₁ ( x ₃ ² +y ₃ ² −x ₁ x ₃ −y ₁ y ₃ ) +Y ₃ (x ₁ ² +y ₁ ² −x ₁ x ₃ −y ₁ y ₃ ) −X ₁ (x ₁ y ₃ −x ₃ y _{1 ) + _ _ _}
It goes without saying that the present invention can be widely applied to other general positioning applications. "Effects of the Invention" As described above, according to the present invention, it is possible to calculate the accurate amount of deviation of the object to be inspected and the reduction ratio with respect to the original image, and by increasing the number of measurement points, it is possible to reduce the expansion, contraction, distortion, etc. of the object to be inspected. It also becomes possible to measure various quantities.
Also, if you perform coordinate transformation based on the calculated amount of deviation,
It is possible to accurately position the target position.

[Brief explanation of drawings]

Figures 1 to 16 are for explaining one embodiment of the present invention, of which Figure 1 is a perspective view of an automatic image inspection device, and Figure 2 is a schematic configuration diagram showing the main parts of the inspection section. , Fig. 3 is an explanatory diagram showing the arrangement of the optical components of the optical head, Fig. 4 is an explanatory diagram showing the size of the measurement unit area on copy paper, and Fig. 5 is the circuit configuration of the automatic image inspection device. 6 is a block diagram showing the structure of the external signal input means, FIG. 7 is a block diagram showing the structure of the pattern information storage means, and FIG. 8 is an explanation showing the structure of the pattern information storage section. 9 is a block diagram showing the structure of the processing procedure storage means, FIG. 10 is a block diagram showing the structure of the processing code storage means, FIG. 11 is a block diagram showing the structure of the inspection procedure storage means, and FIG.
Figure 2 is a block diagram showing the configuration of the measuring means;
The figure is a block diagram showing the configuration of the arithmetic processing means.
Figure 4 is a plan view showing the main parts of the chart, Figure 15 is an explanatory diagram showing the principle of coordinate correction, Figure 16 is a flowchart to explain position detection and measurement work associated with it, and Figure 17 is a diagram illustrating the principle of coordinate correction. FIG. 18 is a plan view showing a table of a conventionally proposed device, FIG. 18 is a plan view showing a measuring portion of a chart, and FIG. 19 is a plan view showing an example of a copy of the chart shown in FIG. 18. 1...Inspection section, 2...Computer section, 3...
Printer section, 4... Copy paper (inspected section), 8
...Chart holding part, 26...Chart holding part drive motor, 31...X-axis stepping motor, 4
DESCRIPTION OF SYMBOLS 1... Concentration detection section, 131... Data sampling control section, 132... Drive control section, 133... Light receiving means.

Claims (1)

[Scope of Claims] 1. A sheet-like object to be inspected that is reproduced by projecting an original image showing at least two standard measurement points and an inspection pattern used for inspecting image information at an arbitrary reduction ratio. a storage means for storing the standard measurement point and the expected location of the inspection pattern relative to the scheduled placement position of the object to be inspected in a coordinate system on the inspection side; and a standard measurement point stored in the storage device. a position measuring means for scanning the vicinity of the standard measuring point and measuring the existing position of the standard measuring point; a calculation means for calculating conversion information for converting between the coordinate system on the object side and the coordinate system on the inspection side; It is characterized by comprising a position prediction means for calculating a position on the inspection object where an inspection pattern is predicted to exist, and a measurement means for measuring image information at the position predicted by the position prediction means. Image inspection equipment.