JPH03175304A - Measuring apparatus of positional shifting amount of recording paper - Google Patents

Abstract

PURPOSE:To detect the correct boundary of patterns by applying a formula to obtain the sum of squares of the deviation between the data of coordinates of the boundary of the patterns by a video image and an approximate straight line approximate to the boundary of the patterns to each constant of the approximate straight line. CONSTITUTION:An X-Y table 12 is moved to position the pattern of a recording paper 11 at the center of the viewfield of a video camera 17. A stepping motor 26 in a filter disk 19 is rotated through control of a computer system 22 and a blue filter is set in an optical axis connecting a white light source 18 and an optical fiber 20. As a result, the blue light irradiated the surface of the recording paper 11. At this time, the reflecting intensity of light is suddenly changed at the boundary between the surface of the recording paper 11 and the pattern, which is detected by the camera 17. Then, the detected image is stored in an image memory 21 as image data binarized by a predetermined threshold value. A group of these image data becomes two approximate straight lines in the X-Y coordinates. The sum of squares of the deviation between the two straight lines and the data of the coordinates of the boundary is obtained.

Description

Detailed Description of the Invention [Field of Industrial Application] This invention measures the amount of misalignment of prints during paper conveyance during printing on recording paper printed by a copying machine or printing device, and is particularly applicable to color prints. The present invention relates to a deviation measuring device.

[Conventional technology]

FIG. 14 shows the configuration of a recording paper deviation measuring device described in, for example, Japanese Patent Laid-Open No. 60-242343.

In the figure, a recording paper l on which a cross-shaped mark IA is recorded is fixed on a table 2A that moves on a table 2 in the direction indicated by an arrow Y. A gate-shaped structural member 5 provided above the table 2A is provided with a moving device 5A movable in the direction of arrow X, and a laser unit 3 is provided in the moving device t5A. A measurement unit 4 is attached to the lower end of the laser unit 3. FIG. 15 shows the detailed configuration of the measurement unit 4. In the figure, a laser light source 3A is, for example, a He-Ne laser, which is converted into parallel light by an optical system 6 and irradiated onto the surface of the recording paper l. The laser beam reflected on the surface of the recording paper l passes through the optical system 6A and is detected by the photoelectric conversion element 7. The control device 8 is a device for moving the two people at the table and the moving device 5A in the X and Y directions, respectively, according to data set in advance by the computer 9, and transmits data representing the positions of the two people at the table and the laser unit 3 to the computer 9. It has a means (not shown) for inputting information. The control device 8 further controls the operation of the laser light source 3A, and also converts the output of the charging conversion element 7 into A/D and inputs it to the computer 9.

In the conventional recording paper misalignment detector configured as described above, the recording paper l on which the cross-shaped mark IA shown in FIG. Detect the position of IA.

The data of the detected cross-shaped mark IA is input to the computer 9 and compared with the data of the correct position inputted in advance. Then, the amount of deviation from the correct position is detected.

[Problem to be solved by the invention]

In conventional recording paper displacement measuring devices, the recording paper has irregularities due to its surface condition, so the boundary between the ink area recorded on the recording paper and the background color area of the recording paper is not a straight line but an irregularity of approximately 50 μm. It becomes a curve with . As a result, when the detection unit 4 measures the position, the error in the detected position increases, making it impossible to accurately measure the amount of positional deviation.

In addition, the measurement unit had to be moved to the measurement position one by one, which added to the mechanical error of this movement system.

[Means to solve the problem]

A device for measuring the amount of positional deviation of recording paper according to the first invention includes:
A video image of a recording paper on which at least two patterns are printed at a predetermined position illuminated by light selected by the illumination light color selection means is generated, and image data obtained by converting the video image into a binary signal is generated. Obtain boundary coordinate data that is stored in the image memory and represents the coordinates of the boundary where the signal level changes greatly in the image data, and set approximate straight lines that approximate the lines connecting each boundary, and also set the approximate straight lines and the boundary coordinates. At least two approximate straight lines are obtained by calculating the first sum of squares of the deviation from the data, and further solving the equation for calculating the sum of squares using the constant of the approximate straight line as a variable for the variable and finding the equation of the straight line. The positions of the patterns indicated by the intersections of the patterns are detected, and a cubic curve passing through each of the at least two positions is set, and each position of the at least two patterns and the three The apparatus includes means for determining a second sum of squares of deviations from the next curve, and solving for the variables a formula for determining the sum of squares, in which a constant of the approximate curve is a variable, to determine an equation of the curve.

The device for measuring the amount of positional deviation of recording paper according to the second invention generates a video image of the recording paper printed at a predetermined position with two sets of patterns composed of at least two types of colors, and The image data obtained by converting the image into binary signal data is stored in the image memory, and the boundary coordinate data representing the coordinates of the boundaries where the signal level changes greatly in the image data is determined and approximated to a line connecting each boundary. In addition to setting an approximate straight line to By determining, the position of the pattern indicated by the intersection of at least two approximate straight lines is detected, and the amount of deviation from the predetermined distance of the distance between at least two types of patterns provided at a predetermined distance apart. It is equipped with a means to calculate.

A recording paper positional deviation measuring device according to a third aspect of the invention is such that the video imaging means in the first and second inventions is replaced by a plurality of video imaging devices whose respective positional relationships are accurate.

A recording paper positional deviation measuring device according to a fourth aspect of the invention comprises: a driving mirror for controlling illumination and reflection of illumination light; and a driving mirror for controlling illumination light irradiation and reflection; This is a photoelectric conversion element.

[For production]

In the first invention, the boundary is represented most accurately by solving a formula for calculating the sum of squares of the deviation between the boundary coordinate data of the pattern based on the video image and the approximate straight line that approximates the boundary of the pattern for each constant of the approximate straight line. A straight line is set, the position of the pattern is identified from at least two straight lines, and a cubic curve passing through at least two pattern positions is set, and the position and cubic curve are determined based on the edge of the recording paper. By solving the equation representing the sum of squares of the deviation from the approximate curve for each constant of the approximate curve, a cubic curve equation is obtained, and this cubic equation represents the deviation in the feeding direction of the recording paper.

In the second invention, the positions of a plurality of patterns of different colors arranged at predetermined intervals are detected in the same manner as in the first invention, and the color is detected by comparing the predetermined intervals of each pattern with the position of each pattern. Detect deviation.

In the third invention, a plurality of graphic patterns located at separate positions are simultaneously converted into video images by a plurality of video imaging devices.

In the fourth invention, a mechanism for controlling irradiation of the graphic pattern on the recording paper scans the photoelectric conversion element or converts it into a video image.

[Embodiments of the invention]

FIG. 1 shows the configuration of an apparatus to which a method according to an embodiment of the present invention is applied. In the figure, an X-Y table 12 is provided that is movable on a pedestal 13 in the directions of arrows X and Y.
A recording paper 1) printed by a color printer is fixed on a Y table 12. X-Y table 1
The surface of 2 is painted black to prevent light reflection.

A fine movement table 15 is attached to a support 14 provided on the pedestal 13 and is movable in the vertical direction as shown by arrow Z. A video camera 17 having an optical system 16 is attached to the fine movement table 15 . Another support 14 is provided on the pedestal 13, and a lighting device 18 is attached to the support 14.

The illumination device 18 includes a light source 18A, a filter disk 19, and a motor 2 for rotating the filter disk 19.
6.

Although not shown, the motor 26 stops the necessary filters of the filter disk 19 between the light source 18A and the optical fiber 20 under the control of the CPU 22A. An embodiment of this filter disk 19 is shown in Fig. 1).

The emitted light from the light source 18A is guided onto the recording paper 1) to be measured through the optical fiber 20, and illuminates the surface thereof.

The light source 18A is a white light source, and by rotating a filter disk 19 provided with a large number of filters to a predetermined position, light having one of red, green, and blue colors can be selectively emitted.

The image memory 21 is a memory that converts an image detected by the video camera 17 into a digital signal and stores the digital signal.

The computer system 22 includes a CPU 22A and a memory 23, and processes the data in the image memory 21 and stores the results in the memo IJ23. Further, the monitor television 29 is a display device for monitoring images stored in the image memory 21. The CPU 22A provides a signal to the stepping motor drive circuit 25 via the table position control circuit 24, and three stepping motors 26, 27 and 28 are driven by the signal.

Figure 2 shows the recording paper used for measurement. In the figure, a pattern of nine squares is printed on the surface of the recording paper. Patterns 31, 32 and 33 are yellow prints, and patterns 34, 35 and 36 are macenta prints. Patterns 37, 38 and 39 are cyan prints.

Next, the measuring method in this example will be explained with reference to FIG. 9. In the following description of each step, the numbers in parentheses at the end of the sentences indicate the step numbers in the flowchart of FIG. First, the X-Y table I2 is moved to position the pattern 3I at the center of the field of view of the video camera 16.

A stepping motor 26 in the filter disk 19 is rotated under the control of the computer system 22, and a blue filter is set between the optical axes connecting the white light source 18 and the optical fiber 20. As a result, the surface of the recording paper 1) is irradiated with blue light. The blue light is reflected by the surface of the white recording paper 30, or absorbed by the pattern 31 printed with yellow ink. As a result, the reflected light intensity changes rapidly at the boundary between the recording paper surface and the pattern 31, and this state is detected by the video camera 17 (101).

The detected image is divided into "l" and "0" by a predetermined threshold.
The image data is stored in the image memory 21 as binarized image data (102). The capacity of this image memory 21 is, for example, 5
It is 12 words x 512 words. r of this image data
The point varying between lJ and rOJ is the boundary, indicated by the image shown in Figure 3 (103). In the figure, the shaded area is the data rOJ, and the non-shaded area is the data rlJ.

The boundary between both data is generally zigzag due to the unevenness of the paper surface.

In FIG. 3, if the boundary range from point 50 to point 51 is range vFII, and the boundary range from point 5 to point 52 is range 2, then in the X-Y coordinates shown in the figure, range l
is expressed by the first equation, and range 2 is expressed by the boundary coordinate data group shown by the second equation.

(xo, yo), (x+, 3'+) ... (X6-1, y++-+), (x,, y
a)... (1) (xll, ya), (x, 14+
, yn◆1) (x, s, y,)
...... (2) These data groups are
When expressed as an approximate straight line at the Y coordinate, as shown in Figure 4, 2
The straight line of the book is 46°47, and is expressed by the third equation and the fourth equation, respectively (104).

y=ax+b ・・・・・・(
3) y=dx+c ・・・・・・
(4) Since the test pattern is a square, the fifth orthogonal equation holds for both straight lines.

ad=-1... (5) Next, the sum of squares of the deviation e between these two straight lines and the boundary coordinate data of ranges 1 and 2 is determined (105).

The deviation e is equal to the distance between the boundary coordinate data (x, y) and the approximate straight line. If the slope of the boundary 45 is small with respect to the X-Y coordinates, the deviations e++e+ in ranges 1 and 2 are determined by the following equations 6 and 7.

er = y, -(ax, 10b) ・--(6)e
r = Xr (a7+ 10c) '=...
(7) Therefore, the sum of squares Z of the deviations is expressed by the eighth equation (105).

l=n Equation 8 is a function using constants a, b, c, and n as variables, that is, f (a, b, c, n) (hereinafter, this function will be simply written as f for simplicity). Therefore, the boundary coordinate data (Xo,
Ya) ... (x,, y,) The two straight lines that approximate
The coordinates (x
c.

By defining yc) as the position of the pattern, the boundary of the printed pattern can be specified (107
). In this way, the positions of the other patterns 32 and 33 can also be detected. In Equation 9, a condition is given in which each partial differential is set to O, but a condition in which each partial differential is set to another value can also be given. Another color pattern, magenta pattern 3
4.35.36, or cyan pattern 37.38.3
9, the filter disk 19 is rotated to select an appropriate filter, and the color of the irradiated light is changed for measurement.

Next, a method for determining the edge position 41 of the recording paper will be described. The X-Y table is moved to bring the edge 41 of the recording paper into the center of the field of view of the video camera. The X-Y table uses a black plate and absorbs blue, green, and red irradiation light. Therefore, only the recording paper reflects light. Since the reflection intensity of the light emitted by the illumination device 18 changes sharply at the boundary between the edge of the recording paper and the X-Y table, the image data is binarized using a predetermined threshold.

Next, when the coordinate data group indicating the boundary of the recording paper is approximated by a straight line as in the case of the pattern described above, the straight line is expressed by Equation 10.

x=ay+b ・・・・・・ α
ω The deviation e between this straight line and the boundary coordinate data is expressed as follows, and the sum of squares of the deviations Z is expressed as follows. The sum of squares Z is a function g(a, b
) (hereinafter, this function will be simply written as g for simplicity),
It is obtained by solving equation 13, which takes partial differentiation with respect to each variable.

Next, the approximate straight line (x=
Find the distance between ax+b). Measure the above distance at several points on the recording paper. For example, in what is shown in FIG. 5 (al), measurements are performed on three patterns 31, 32, and 33.

In FIG. 5(a), the position of the pattern 31 is (XyI
), the position of pattern 32 is represented by (X!,)'2), and the position of pattern 33 is represented by (X3.Y2), then the distances between each position and the edge of the recording paper are distance Ll, distance L2, and distance L3. expressed. The conveyance state of the recording paper is approximated by a curve from the positions of these three points and their respective distance data.

Assuming that the curve to be approximated is a cubic curve, Equation 14 is assumed (108).

x=ay" 10 by" +cy+d ・・・-Q
4) Taking the edge of the recording paper as the reference for the X coordinate, the recording position of the turn is the pattern Oυ... (Ll, y'') pattern
... (L2.Yi) Pattern (to) ...
It is expressed as (L2.ys). Based on this, curve approximation is performed by the least squares method, and the sum of squares Z of deviations between this curve and the recording position is determined (109). The deviation e is the 15th
It is expressed by the formula.

e + = X I (a 3' + 10b 'i l+ CY + +
d)...α9 Therefore, the sum of squares Z of the deviations can be obtained from Equation 16.

Z= Σ (x+ a)'+ 1=1 by+ Cyt d) ・・・・・・ α
G equation 16 is a function h(a,
b, c, d) (hereinafter, for simplicity, this function will be simply referred to as h
), a, b by solving equation 17, which takes partial differentiation with each variable.

Each value of c and d can be obtained (1)0).

As a result, if this assumed cubic equation includes cubic and quadratic terms, meandering occurs in the conveyance of the recording paper, as shown in Figure 5(b), and if it only includes linear terms, then (ago, b
=o) Fig. 5(e) +: Indicates that the recording paper is simply fed diagonally as shown. Furthermore, the amount of deviation of the recording paper can be determined from the value of the constant d (1) 1). In Equation 17, the condition that each partial differential is set to O is given, but the condition may be set to other values.

The above measurements were performed on white or yellow recording paper, but in order to measure the recording state on magenta recording paper, a green filter was used to measure the pattern 34 shown in Figure 2.
36, the same processing as in the case of yellow is performed. Furthermore, in order to measure the recording state on cyan recording paper, similar results can be obtained by performing the same processing as above using patterns 37 to 39 using a red filter. An example will be described.

In the second invention, as shown in FIG. 6, a yellow mark 31A is provided on the recording paper of the test object,
Overlaid on it is a slightly smaller square magenta mark 32.
A is provided. Also, superimposed on the magenta mark 32A is an even smaller square cyan mark 33A.
is provided. And marks 31B, 3 similar to the combination of the three color marks of yellow, magenta, and cyan.
A set of 2B and 33B are provided at a predetermined distance apart.

As shown in FIG. 10, points 37, 38, 39, 40, 4 represent the positions of each mark by the same process as in the first invention.
Find the positions of 1 and 42. In FIG. 10, steps 201 to 207 are substantially performed in step 1 of FIG.
Equivalent to 01-107. The position of each point above is expressed by X-Y coordinates as shown in Fig. 6, for example, the point (Xy+
+ya, ) represents the position of the first specific point of yellow. Next, the distance between each point is compared with a predetermined reference recording distance. The reference recording distance in the X direction in the figure is expressed by the number of dots on a print head (for example, a thermal head). That is, as shown in FIG. 7, the yellow mark 31
Amount of deviation in distance in the X direction between point 37 of A and point 38 of magenta mark 32A.

is expressed by the 18th equation.

△X ys= (Xml X yl)-d I”
h """ αQ However, X and Xyl are the coordinates of the first specific point 1 of magenta and yellow, respectively. Also, the point 38 of the magenta mark 32A and the cyan mark 33A
The amount of deviation ΔX,c in the distance between the points 39 is expressed by Equation 19 (208).

△Xme= (xc+xa+) a2- h
--α9 Here, dl is the number of dots between points 37 and 38, d2 is the number of dots between points 38 and 39, and h represents the reference pitch between each dot.

On the other hand, the shift amount in the Y direction is the paper feeding distance, and is determined by mechanical elements such as the diameter of the printer's platen. However, since the diameter of the platen differs from printer to printer due to manufacturing errors, the amount of shift varies from printer to printer. The Y coordinates of the boundaries of the yellow, magenta, and cyan patterns including the above errors are expressed by Equations 20.21 and 22, respectively.

y' = 1! □(L+△L,) ・・・・
・・ @y“ =1−+(L+△L,) ・
・・・・・・ Cυy' =1c+(L+ΔL,)
・・・・・・ ■Here is 1!1. is the number of lines from the predetermined origin of the yellow pattern, yoke, and fc+
represent the number of lines from a predetermined origin of the magenta pattern and the cyan pattern, respectively. Also, L is 1 line,
ΔL2, ΔL1, and ΔLe are the deviations of the distances between yellow, magenta, and cyan lines, respectively. The amount of deviation △y between the yellow pattern and the magenta pattern. is expressed by Equation 23.

△ya, = (y, + yy+) - (y' - y',) ...... @2nd
In formula 3, the first term on the right side is yellow pattern 31A
and magenta pattern 32A, and the second
Item is yellow pattern 31A when no color shift occurs.
and the magenta pattern 32A.

Substituting Equation 20.21 into Equation 23, we get the 24th △y,
g+= (y ml −y y+)(f−1(L+△
L,) −z,, (L+△L,)) = (y−+−y□) (7ml−f,,) ・L −1,1・△L.

+1!1・△L.

= (y ml y −+) −(l,・L −f ,,・L) −(1,,・△L, −1,,・△L,) ・・・・・・ (
(to) In equation 24, the mechanical error E is expressed by equation 25.

E = f, , △L, -1. ．．・△L, ・・・・
... (2) Assuming that the number of recording lines is constant, the distance between the lines of each color, where l+z is the distance between the patterns 31A and 32B. Therefore, the amount of color shift Δy0 between the yellow pattern and the magenta pattern is expressed by Equation 27 by substituting Equation 26 into Equation 23.

△y□=(ys+yy+)yl-y 1I (1゜12 Also, the color between magenta pattern and cyan pattern △y-
c= (y c+ y −+) In the conventional measuring device, the mechanical error E was included in the amount of deviation and could not be measured separately, but in this embodiment, the error E A deviation amount (Δy1.) from which is removed is obtained.

In the above embodiment, in order to obtain pattern boundary information, blue light, green light, and red light were sequentially irradiated onto the recording paper 11 using the blue, green, and red filters on the filter disk 19, but the recording paper 11 was illuminated with white light and colored. If a video camera is used, image processing for three colors can be performed simultaneously.

In addition, although white light is separated into blue, green, and red by a filter on a filter disk, a prism may also be used.
A laser or the like may be used as a light source. In addition, as a pattern on the recording paper, a pattern in which yellow, magenta, and cyan were overlapped by shifting a predetermined distance was used, but as shown in FIG. 8(a), a rectangular pattern in which yellow, magenta, and cyan were printed individually, As shown in (b), a pattern with a triangular geometric shape may be used. Also, Figure 8 (
As shown in C) and FIG. 8(d), yellow, magenta, and cyan square, triangular, or other patterns may be stacked one on top of the other while being shifted by a certain distance.

FIG. 12 is a diagram showing an embodiment of the third invention of the present invention, and in the figure, IA, 1)゜13 to 29 are the same as those explained in the first and second inventions above. be. Fine movement table 1 supporting video camera 17 and optical system 16
A plurality of imaging means 5 are provided, each of which takes an image of a different location on the recording paper 1), and the relative position thereof is accurately grasped by the CPU 22A via the image memory 21. Then, the images detected by each video camera 17 are processed by a computer in the same manner as described in the first and second inventions above to calculate the boundaries of the images, and the distance between the images of each video camera 17 is calculated. calculate.

Compared to the above-mentioned first and second inventions, the apparatus for measuring the amount of deviation in the position of recording paper having such a configuration does not require two-dimensional movement of the object to be measured, and can perform measurements quickly. Since there is no movement error in the mechanical drive system caused by the stepping motors 26 and 27, highly accurate measurement is possible.

FIG. 13 is a diagram showing the constituent elements of the imaging means in the fourth aspect of the present invention. In the figure II, 18, 21
．． 22A and 25 are similar to those described above. 51 is a photoelectric conversion element, 52 is a semi-transparent mirror, 53 is a drive mirror, 53A is a drive motor for the drive mirror 53, and 54 is an optical lens. Of these, the photoelectric conversion element 51, semi-transparent mirror 52, drive mirror 53, and optical lens 54 are used in place of the optical system 16 and video camera 17 of the apparatus shown in FIG.
5. In the imaging means of the fourth invention, specific light emitted from the light source 18 is reflected by the drive mirror 53 through the semi-transparent mirror 52, and the optical lens 54 illuminates the aperture measurement surface. The reflected light passes through the optical lens 54 and the drive mirror 53, is reflected by the semi-transparent mirror 52, and enters the photoelectric conversion element 51.

The image information obtained thereby is point information, but by gradually changing the reflection angle of the drive mirror 53, the irradiated area can be scanned. At this time, the drive mirror 53
By appropriately selecting the angular change rate of can be increased.

〔Effect of the invention〕

According to the first aspect of the present invention, the recording paper is irradiated with light suitable for the color of the recording paper and the pattern, and the recorded predetermined pattern is converted into an electrical signal by a video camera and stored in an image memory. Then, the boundary coordinate data is obtained from the image data stored in the image memory, and the deviation between the approximate straight line and each coordinate data of the pattern is calculated.
By solving the equation representing the sum of products, the equation representing the boundary is obtained,
The boundary can be found from that formula. Therefore, the correct pattern boundary can be detected without being affected by the unevenness of the surface of the recording paper. Furthermore, since the illumination light can be changed depending on the color of the recording paper and the pattern, measurements can be made even in the case of colors such as .

According to the second aspect of the present invention, it is possible to measure the amount of color misregistration between each color, excluding mechanical errors such as the platen of the printer.

According to the third aspect of the present invention, by providing a plurality of video imaging means, there is no need to move the video imaging unit to the measurement position each time, measurement can be carried out quickly, and the moving mechanical system of the video imaging means is Measurements can be made with high accuracy without errors.

According to the fourth aspect of the present invention, by using the video imaging means consisting of a driving mirror and a photoelectric conversion element, it is possible to subdivide the measurement accuracy unit and perform highly accurate measurement.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an apparatus to which the present invention is applied, Fig. 2 is a plan view of a sample recording paper, Fig. 3 is a diagram showing the boundaries of a pattern represented by image data, and Fig. 4 is a diagram showing the boundaries. Figure 5 (a) is a plan view of the recording paper showing the details of measuring the pattern position, Figure 5 (b) and Figure 5 (C) are the approximate curves and the pattern position. 6 is a plan view of the recording paper showing the arrangement of color patterns; FIG. 7 is a plan view of the recording paper showing the detailed arrangement of the color patterns; FIG. Figure (bl, Figure 8 (C1) and Figure 8 (d) are plan views of recording paper showing the arrangement of color patterns;
FIG. 9 is a flowchart showing the steps of the first invention, FIG. 1θ is a flowchart showing the steps of the second invention, FIG. A diagram showing an embodiment of the third invention. FIG. 13 is a diagram showing an outline of the configuration of an imaging means according to the fourth invention of the invention. FIG. 14 is a diagram showing the amount of deviation in the position of recording paper using a conventional technique. 15 is a detailed view of a laser unit used in the apparatus shown in FIG. 14, and FIG. 16 is a plan view of a sample recording paper according to the prior art. In the figure, 1.1), 30.41 is recording paper, 6.16
is an optical system! 7 is a video camera, 18 is a light source, 19 is a filter disk, 21 is an image memory, 22 is a computer system, 7.51 is a photoelectric conversion element, 53 is a driving mirror, and 54 is an optical lens. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (4)

[Claims] (1) Illumination light selection means for selecting illumination light of a color corresponding to the color of a predetermined graphic pattern on recording paper; video imaging means for generating a video image of recording paper on which a plurality of graphic patterns are printed; A means for converting an image into binary signal data and storing the image data in an image memory, a means for generating boundary coordinate data representing the coordinates of a boundary where the signal level changes greatly in the image data, and approximating a line connecting each boundary. means for setting data for an approximate straight line; means for determining the sum of squares of deviations between the approximate straight line and the boundary coordinate data;
Means for calculating the equation of the straight line by solving the function for calculating the sum of squares using the constant of the approximate straight line as a variable, means for calculating the representative position of the graphic pattern indicated by at least the intersection of the two approximate straight lines. , means for setting a curve function that passes through each representative position of the plurality of graphic patterns, and a second square of the deviation between each representative position of the plurality of graphic patterns and the curve function with reference to the edge of the recording paper. A position of a recording paper characterized in that it is provided with means for calculating the sum, and means for solving the second sum of squares equation for the variables, using the constant of the curve function as a variable, to obtain the equation of the curve function. A device for measuring the amount of deviation. (2) illumination light selection means for selecting illumination light of a color corresponding to the color of a predetermined graphic pattern on the recording paper; a recording paper on which a plurality of graphic patterns made up of at least two different colors are printed at predetermined positions; A video imaging means for generating a video image, a means for converting the video image into binary signal data and storing the image data in an image memory, and a boundary coordinate representing the coordinate of a boundary where the signal level changes greatly in the image data. data generation means, means for setting data for approximate straight lines that approximate each line connecting each boundary, means for calculating the first sum of squares of the deviation between the approximate straight line and the boundary coordinate data, and a means for determining the constant of the approximate straight line. means for solving the function for calculating the sum of squares for the variables and calculating the equation of the straight line;
means for specifying the position of each of the graphic patterns indicated by the intersection of at least the two approximate straight lines; and a means for determining the amount of deviation from the specified value between the graphic patterns, which are set in advance to be separated by a predetermined distance, from the identified graphic pattern. 1. An apparatus for measuring the amount of deviation in the position of recording paper, comprising: means for calculating. (3) The apparatus for measuring the amount of deviation in the position of recording paper according to claims (1) and (2), further comprising a plurality of video imaging means capable of accurately grasping the positional relationship between the recording sheets. (4) The amount of deviation in the position of the recording paper according to claims (1) and (2), wherein the video imaging means is comprised of a mechanism for controlling illumination and reflection of illumination light, and a photoelectric conversion element. measuring device.