JP5974337B2 - Abnormality detection method for folded paper - Google Patents

Description

  The present invention relates to a method for detecting an abnormality of a folded sheet, and more particularly to a method for detecting a deformation of a folded sheet of a printed material such as a catalog, a pamphlet, and a manual with high accuracy.

  A large number of printed materials of the same type such as catalogs, pamphlets, and manuals are folded by a folding machine in order to arrange them into a predetermined size, and the shape of each paper is uniform. Therefore, it is necessary to detect and exclude the deformed sheet because the deformed sheet causes a problem when transported by an automatic sheet inserting machine or the like.

  As an abnormality detection method for such folded paper, as described in Patent Document 1, the back of the paper is captured by a color TV camera or a monochrome TV camera to obtain video information, or a luminance meter. There has been proposed a method in which luminance information is obtained using the above, and then the obtained video information and luminance information are binarized or binarized and detected simultaneously with the number counting.

  However, when two overlapping sheets are folded or when the thickness of the paper sandwiched at the exit of the folding machine is binarized or ternarized to detect an abnormality, the thickness abnormality is detected. This is a problem when detecting an abnormality with high accuracy because it does not target the state of the final fold.

  JP 2007-238324 A

  The present invention provides a method for detecting an abnormality of a sheet after folding, capable of analyzing the shape of a final sheet fold in the folding process with high accuracy and detecting an abnormality in a plurality of folded sheets. It is the purpose.

  The present invention achieves the above-described object, and aligns a plurality of folded sheets so that the back portion is aligned in the same plane, and presses the aligned plurality of sheets with a pressing plate from both sides, obliquely in front of the back portion. Irradiate light to create a shadow part in the recess between the back and a non-shadow part in the back part, and press the plate on both sides and the back part of the plurality of aligned sheets with an analog color TV camera from the front, The shadow portion of the concave portion is imaged so as to be perpendicular to the horizontal scanning line of the color image signal obtained from the analog color television camera, and the horizontal scanning line 1 of the back imaging portion of the obtained analog color image signal. Value obtained by multi-leveling the intensity of red, green, and blue colors of the analog signal for each minimum resolution unit of the analog color TV camera by a color analog-digital conversion circuit from one end to the other end Conversion to The intensity values of the converted red, green, and blue colors are sequentially assigned from one end to the other end corresponding to each constituent point of the digital signal composed of the number of resolutions of the analog color TV camera. The measurement signal of the color intensity of the constituent point for one horizontal scanning line from one end to the other end is sequentially stored for each constituent point and the preset value of the paper reference line. Compared to, the first time the color becomes stronger than the paper baseline value, and the color becomes weaker than the paper baseline value. When the color becomes weaker than the paper base line value and becomes weaker than the paper base line value from the weakened state, it is determined as a non-shadow part, and the determined non-shadow part is used as the back part of the paper. The number of sheets is counted and the number of sheets is counted, and the paper from one end to the other end The value obtained by subtracting the color strength of the paper reference line from the color intensity of the component point where the color is stronger than the standard value is added to the previous point of the component point where the color is weaker than the next paper reference value. Folding is characterized in that an abnormality is detected by calculating the area of each sheet, then calculating the average area from the number of sheets, and comparing the area of each sheet with the average area or the area of a normal sheet This is a method for detecting anomalies in paper with high accuracy, aligning multiple folded sheets so that the back is aligned on the same plane, pressing the aligned sheets from both sides with pressing plates, and illuminating light from the front of the back diagonally. Irradiate to create shadows in the recesses between the backs and non-shadows in the backs, and press the plate on both sides and the backs of the plurality of aligned sheets from the front with an analog monochrome TV camera. The shaded area of the recess is monochrome The image signal obtained from the TV camera is imaged so as to be perpendicular to the horizontal scanning line of the image signal, and the intensity of the luminance of the analog signal for one horizontal scanning line of the back imaging unit of the obtained analog monochrome image signal is From the one end to the other end, the monochrome analog-to-digital conversion circuit converts the value into a multivalued value for each minimum resolution unit of the analog monochrome television camera, and converts the converted luminance intensity value from one end to the other end. Up to this point, the digital signal composed of the number of resolutions of the analog monochrome TV camera is sequentially stored in correspondence with each component point, and the luminance of the component point corresponding to one horizontal scanning line from one end to the other end is increased. The measurement signal is sequentially compared for each component point with the value of the component point and the preset value of the paper reference line. For the first time, the brightness becomes stronger than the value of the paper reference line. When the brightness becomes weaker than the quasi-line value, it is determined as a non-shadow part, and from the next time the brightness becomes weaker than the paper reference line value, the brightness becomes stronger than the paper reference line value and the paper reference line When the brightness becomes lower than the value of, it is determined as a non-shadow part, the determined non-shadow part is regarded as the back part of the paper, the number of back parts is added up to count the number of sheets, and from one end to the other end The value obtained by subtracting the intensity of the paper reference line from the intensity of the component point where the brightness is higher than the paper reference value is added to the previous point before the component point where the brightness is lower than the paper reference value. Folding is characterized in that an abnormality is detected by calculating the area of each sheet, calculating the average area from the number of sheets, and comparing the area of each sheet with the average area or the area of a normal sheet. This is a high-precision abnormality detection method for processed paper, and it is folded. Align the multiple sheets so that the back is aligned in the same plane, press the aligned sheets from both sides with pressing plates, and irradiate light from the front of the back diagonally to the shadow between the back and the shadow on the back. A shadow portion is generated, and the pressing plates on both sides and the back portions of the plurality of aligned sheets are obtained from a digital television camera from the front, and the shadow portion of the recess is obtained from the digital television camera. The above-mentioned digital television camera captures an image signal so as to be perpendicular to the horizontal scanning line of the image signal, and the intensity of the image signal for one horizontal scanning line of the back imaging unit of the obtained image signal from one end to the other end Are stored in order corresponding to each constituent point of the digital signal composed of the number of resolutions, and the strength of the image signal of the constituent point for one horizontal scanning line from one end to the other end is sequentially set to each constituent point. For each component point value and Compared with the specified paper baseline value, the image signal becomes stronger than the paper baseline value for the first time, and the image signal becomes weaker than the paper baseline value for the first time. After that, when the image signal is weaker than the paper reference line value, the image signal becomes stronger than the paper reference line value, and when the image signal becomes weaker than the paper reference line value, it is determined as a non-shadow portion. The determined non-shadow part is the back of the paper, the number of backs is added up to count the number of papers, and the image signal strength at the component point where the image signal is stronger than the paper reference value from one end to the other end Then, the value obtained by subtracting the strength of the image signal of the paper reference line is added up to the point before the component point where the image signal was weaker than the next paper reference value to obtain the area of each paper, and then from the number of papers Calculate the average area and calculate the area of each paper as the average area or positive By comparing the area of a sheet, a highly accurate abnormality detection method of the folded processed sheet and detects an abnormality.

  According to the method for detecting an abnormality of a folded sheet of the present invention, it is possible to detect an abnormality after folding from the information on the final fold of each sheet with high accuracy by using multi-valued data.

  It is sectional drawing which shows an example of the paper normally folded.   It is sectional drawing which shows an example in which the last crease | fold of the folded paper was sharp.   It is sectional drawing which shows an example which the last crease | fold of the folded paper was deform | transformed.   It is explanatory drawing which shows the means to detect abnormality of the several paper 1 by which the folding process was carried out.   FIG. 6 is a cross-sectional view of a state in which 12 sheets that have been normally folded are aligned.   6 is a graph showing the signal strength from the start end to the end end of one horizontal scanning line obtained by imaging the paper of FIG. 5, and is a schematic graph showing the intersection of the paper reference line and the graph. .   It is the graph which showed the detail which calculates | requires the area | region which shows the straight line which connected between the structural point of the 1st sheet | seat of the 1st sheet of a left end part, and a structural point, and a paper reference line.   FIG. 10 is a cross-sectional view of a state in which 10 sheets that have been normally folded and 2 sheets of deformed paper are aligned.   FIG. 9 is a graph showing the signal strength from the start edge to the end edge of one horizontal scanning line obtained by imaging the paper of FIG. 8, and is a schematic graph showing the intersection of the paper reference line and the graph. .   This is a graph showing the strength of the signal from the start edge to the end edge of one horizontal scanning line by imaging 25 normal sheets that have been aligned, and an actual concrete example showing the intersection of the sheet reference line and the graph It is a graph based on typical data.   Image of 23 sheets of aligned normal paper and 2 sheets of deformed paper from the right end to the 3rd sheet and from the left end to the 3rd sheet, and display the signal strength from the start edge to the end edge of one horizontal scanning line It is a graph based on actual specific data showing the intersection of the sheet reference line and the graph.   24 sheets of normal paper and 2 sheets of paper that were folded on the 5th sheet from the left edge were aligned and one sheet was aligned. It is a graph that displays the signal strength from the start end to the end end of one line, and is a graph based on actual specific data that shows the intersection of the sheet reference line and the graph.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an example of a sheet folded to a desired size, where 1 is a folded sheet, 2 is a back part of the folded sheet 1, and the back part 2 is a semicircle as shown in the figure. Become a shape.

  FIG. 2 shows an example in which the final crease of the folded paper is sharp, where 1 is the folded paper, 2 is the back of the folded paper 1, and the back 2 is sharp as shown in the figure. Become a shape. For some reason, when a larger pressure than usual is applied to the sheet during folding or at the discharge portion, a phenomenon that the final fold is sharp may occur, and an abnormality such as deformation of the entire sheet may occur.

  FIG. 3 shows an example in which the final fold of the folded paper does not have a normal semicircular shape but is distorted. 1 is the folded paper, 2 is the folded paper 1 The back portion 2 has a distorted semicircular shape as shown in the figure. If for some reason a slip occurs on one side of the roller that carries the paper by pressing both sides of the paper in the folding machine, an unnecessary force acts only on one side of the paper and the last crease is deformed The final crease is distorted and the entire paper is bent, the paper is wrinkled, or the printed characters are hard to read when the paper is opened due to deformation of the paper in the final crease. There is a case.

  FIG. 4 shows a means for measuring the thickness of a plurality of folded sheets 1. The plurality of folded sheets 1 are aligned so that the back portions 2 are aligned on the same plane, and the pressing plates 3 are arranged from both sides. Then, the illumination device 4 irradiates light from an oblique direction in front of the back part 2 to generate a non-shadow part (bright part) 5 on the convex part of the back part and a shadow part 6 in the concave part between the back parts. The illuminating device 4 may be arranged on either the right side or the left side, but if it is arranged in both the right and left diagonal directions and irradiated from both diagonal directions, uniform illumination is possible. is there. Horizontal scanning of the shadow portion 6 and the TV camera signal is performed so that all the shadow portions 6 are imaged by the television camera 7 in which the back portion 2 and the holding plates 3 on both sides of the aligned sheets 1 are fixedly arranged in front of the same. Take an image so that it is perpendicular to the line. The position of the television camera 7 is preferably at the center of the plurality of sheets 1 so that left and right can be imaged uniformly. The obtained image is checked on the image monitor 8 to obtain a good image.

  Next, when the TV camera 7 is an analog color TV camera, an analog color image signal obtained from the color TV camera is converted by the color analog-to-digital conversion circuit 9 to the intensity of red, green, and blue colors. Converted into a multi-valued digital signal, sent to the computer 10, and the intensity of each color of the multi-valued digitized signal is converted into a multi-valued color signal corresponding to each constituent point constituting the horizontal scanning line. Convert. When the camera is a digital system, a digital signal may be sent directly to the computer 10 and used for calculation. Further, all three colors of the obtained digital signal can be used for counting, or the optimum color signal that appears most strongly according to the color of the paper can be selected and used as a representative signal. In particular, when the paper color is amber / blue, only the blue signal appears clearly, and the intensity of the red / green color becomes unclear, so it is better not to use it for counting to prevent erroneous counting. Often good. In the case of dark blue / blue paper colors, it is difficult to count using a monochrome camera. Therefore, it is desirable to use a color television camera for counting papers of these colors.

  When the TV camera 7 is a monochrome TV camera, the obtained image signal is changed from the color analog-digital conversion circuit 9 to a monochrome analog-digital circuit and sent to the monochrome analog-digital circuit, and the analog luminance signal is multi-valued. 2 is sent to the computer 10 in FIG. 2, and the brightness of the image signal is converted into a multi-valued signal for each constituent point constituting the horizontal scanning line.

  The converted red, green, and blue color intensity values are sequentially stored from one end to the other end in correspondence with each constituent point of the digital signal that is composed of the number of resolutions of the analog color TV camera. In addition, when counting the plurality of aligned sheets 1, the signal strength of each constituent point constituting the horizontal scanning line from one pressing plate 3 to the other pressing plate 3 through the plurality of sheets 1 is determined. Is detected for one horizontal scanning line in a direction perpendicular to the shadow portion 6, and the computer monitor 11 takes the horizontal scanning line composing point on the X axis and the signal strength on the Y axis as shown in FIG. And a graph connecting the points indicating the signal strength with respect to each of the horizontal scanning line composing points with a straight line. In this graph, the bright part 5 and the shadow part 6 form peaks and valleys and appear to swing, and the bright part 5 and the shadow part 6 can be known as the difference in signal strength.

FIG. 6 is a schematic diagram for explanation in which 12 sheets of normal paper are aligned between the pressing plates as shown in FIG. 5, and the color intensity of each component point of the digital signal is connected by a straight line. This graph shows the signal strength on the Y axis and the horizontal scanning line composing point on the X axis.
In FIG. 6, points where the preset sheet reference line intersects the graph are indicated by 24 points from the right end to A, B... X, and at the point A, the graph crosses the sheet reference line upward, and B The sheet crosses the paper reference line downward at the point, further crosses the paper reference line upward at the C point, crosses the paper reference line downward at the D point, and similarly repeats up to the X point.

  First, after the paper reference line is crossed upward, it is judged to be one sheet of paper by crossing the paper downward. After that, the paper base line is crossed downward, and then the paper base line is crossed upward. When the sheet reference line is crossed downward, it is newly determined as one sheet, and the number of sheets is added for each determination. In the case of this example, one sheet of paper between A and B, one sheet of paper between C and D, and this are sequentially repeated. Finally, it is determined that there is one sheet of paper between W and X, and the number of sheets is 12 Accumulate with sheets.

Next, means for detecting an abnormality will be described. By adding all the values obtained by subtracting the value of the paper reference value from the value of the Y-axis of the constituent point for each of A-B, C-D,. , Calculate the area of each part surrounded by the graph above the paper reference line, then calculate the average area from all the calculated areas, compare each area with the average area, the difference is If it exceeds the allowable value or falls below the allowable value, it is detected as abnormal. In the above description, the case where the average area is calculated from all the areas has been described, but in actuality, since an excessively small value or an excessively large value may be obtained, the average area value is From each area, exclude the largest number of sheets, for example, from 1/8 to 1/4, in order, and remove from 1/8 to 1/4, starting from the smallest area. It is also possible to calculate by dividing the total area and dividing by the remaining number. According to this method, an accurate average area can be calculated easily.
In the case of the schematic diagram of FIG. 6, since all the areas of one sheet are 918 and all are normal sheets, no abnormal sheet is detected.

  Next, the area calculating means will be described in detail with reference to FIG. 7. Intersection points A, B, C... In FIG. However, in reality, as shown in the detailed diagram of the first graph at the left end portion shown in FIG. 7, the graph is obtained by connecting the constituent points with a straight line in order, as shown in FIG. The intersection of the graph and the paper reference line is the intersection of the straight line connecting the constituent points before and after it and the paper reference line. In this example, the constituent point that first exceeds the graph is c, and the constituent point that is below is It becomes h point. Accordingly, the area of one sheet is vertical from the constituent point g immediately before the intersections C, c, d, e, f, g, and h of the line segment vertically drawn from the point c and the sheet reference line. Is obtained by integrating the values obtained by subtracting the reference line value from the Y axis values of c, d, e, f, and g. It is done. The intersection X between the line segment bc and the paper reference line, and the intersection Y between the line segment g-h and the paper reference line are calculated, and the areas of the polygons X, c, d, e, f, g, and Y are obtained. Thus, a more accurate area can be obtained.

In FIG. 8, the position of the pressing plate is set at the same position as in FIG. 5, the distance between the pressing plates is the same, the third sheet from the left end is a sheet with a sharp crease, and the sheet is the third sheet from the right end. As shown in FIG. 8, an abnormal sheet in which the color strength of each component point of the digital signal is connected with a straight line by aligning the sheet with the fold line of the sheet and the normal sheet together with 10 normal sheets as shown in FIG. Is a schematic graph for explanation in the case of including the signal intensity, and the signal strength is shown on the Y axis and the horizontal scanning line composing point is shown on the X axis.
In this case as well, in the same manner as in FIG. 6, the paper first exceeds the paper reference line first, and then it is determined to be one sheet by crossing the lower direction. After exceeding the sheet reference line in the upward direction, the sheet reference line is crossed downward and rearward to newly determine one sheet and add up. In this example, the number of sheets is set to 12.

Next, means for detecting an abnormality will be described.
As described with reference to FIG. 7, the area calculation method will be described with reference to FIG. Add all values obtained by subtracting the value of the paper reference value from the value of the Y-axis of the constituent point for each of AB, CD,. To calculate the area of each part surrounded by the graph above the paper reference line, then calculate the average area from all the calculated areas, compare each area with the average area, and the difference is An abnormality is detected when the allowable value is exceeded or below the allowable value.

  In the above description, the case where the average area is calculated from all the areas has been described, but in actuality, there may be an excessively small value or an excessively large value. From each area, exclude the largest number of sheets, for example, from 1/8 to 1/4, in order, and remove from 1/8 to 1/4, starting from the smallest area. It is also possible to calculate by dividing the total area and dividing by the remaining number. According to this method, an accurate average area can be calculated easily.

  In the case of the schematic diagram of FIG. 8, the area of the third sheet from the left end is 556, the third sheet from the right end is 711, and the others are 918. In the case of one-half, there are three each, and the average of the remaining six sheets. In this example, the average area is 918. When the third sheet from the right end is compared, it becomes 556/918 = 0.61, which is 39% smaller. If the allowable value is set to plus or minus 30%, it is below the allowable value and detected as being abnormally small. . Further, when the third sheet from the right end is compared, it is 711 ÷ 918 = 0.77, which is 23% smaller. If the allowable value is plus or minus 20%, it is below the allowable value and detected as being abnormally small. .

  In addition, when the wide-angle lens is used, the normal paper area is the central area when there is a difference in the imaging state between the central area and the peripheral area, or when the total thickness of the entire paper is wide and illumination cannot be performed uniformly. And the peripheral portion, the abnormal sheet can be detected by a method of comparing the calculated data with the sheet area data for each sheet position obtained from the normal sheet imaging result. Comparing the data of FIG. 6 and the data of FIG. 8 when all the normal sheets are inspected, in the case of the third sheet from the right end, it becomes 556 ÷ 918 = 0.61, which is 39% smaller, which is acceptable. If the value is set to plus or minus 30, it is below the allowable value and detected as being abnormally small. In the case of the third sheet from the right end, 711 ÷ 918 = 0.77, which is 23% smaller. If the allowable value is plus or minus 20%, it exceeds the allowable value and is detected to be abnormally large. The

The description so far has been made using schematic and ideal graphs using FIGS. 6 and 8, but will be described in more detail using graphs based on actual specific data.
FIG. 10 is a graph obtained by aligning and capturing 25 normal sheets in an appropriate state between the pressing plates, and is a case where the sheet reference value is set to 150.

  FIG. 11 shows an image in which a total of 25 sheets including a sheet having a sharp final fold on the third sheet from the left end, a sheet having a deformed final fold on the third sheet from the right end, and 23 normal sheets are properly aligned. In this graph, the sheet reference value is set to 150. When this graph is compared with the graph of FIG. 10, it can be seen that the area of the abnormal paper is small, and if the allowable value is plus or minus 30%, the area of the paper with a sharp final crease and the paper with the final crease deformed It can be seen that is below the allowable value and an abnormality is detected. Since other sheets are within the allowable range, it was determined to be normal.

  In FIG. 12, two sheets of paper are stacked on the fifth sheet from the left end, and 25 sheets of paper with a large fold thickness and 24 normal sheets are aligned, and the back of the fifth sheet from the right end is raised and the same This is a graph taken in a state where the lines are not arranged in a plane and the alignment state is not appropriate, and the sheet reference value is set to 150. Compared with the graph of FIG. 10, the graph of this figure shows that the fifth sheet from the left edge folded and folded has a larger sheet area, and the paper that is improperly aligned has a smaller sheet area. If the tolerance value is set to plus or minus 30%, the area of the paper that is folded with two sheets of paper exceeds the tolerance value, an abnormality is detected, and the paper is not properly aligned. It is found that an abnormality is detected below the value, and in addition to the deformation of the sheet, an abnormality in thickness and an abnormality in the alignment state can also be detected. Since other sheets are within the allowable range, it was determined to be normal.

  The allowable value varies depending on settings such as the difference in the number of sheets, the number of sheets, the thickness, and the accuracy of measurement, but is desirably 10% to 30%. The allowable value of, for example, plus or minus 25% is a set value that is determined to be abnormal when the area to be compared is 25% above and 25% below the average area.

Implementation of the present invention can also be performed as follows.
That is, the calculated area of each sheet is stored with the number of sheets corresponding to each sheet from the right end, and the area of the sheet is calculated and compared with the stored area for each subsequent inspection. When the area is larger than the allowable value or when the area is smaller than the allowable value, it is detected as an abnormal sheet, and the abnormality can be displayed together with the sheet position on the monitor screen.

  As described above, it is possible to detect an abnormal sheet with high accuracy by calculating the area of the sheet and detecting an abnormal sheet by comparing with an appropriate allowable value setting.

DESCRIPTION OF SYMBOLS 1 Folded paper 2 Back part 3 Holding plate 4 Illumination device 5 Bright part 6 Shadow part 7 Television camera 8 Image monitor 9 Color analog-digital conversion circuit 10 Computer 11 Computer monitor

Claims (3)

  Arrange the folded sheets so that the back is aligned on the same plane, press the aligned sheets from both sides with pressing plates, and irradiate light from the front of the back diagonally to the recess between the back and shadow. A non-shadow portion is formed in the analog color TV camera from the front with the holding plates on both sides and the backs of the aligned plural sheets, and the shadow portion of the recess is the analog color television. The color image signal obtained from the camera is imaged so as to be perpendicular to the horizontal scanning line of the color image signal, and the analog signal of the horizontal scanning line of the back imaging unit of the obtained analog color image signal of the red, green, and blue colors of the analog signal The intensity is converted into a multivalued value for each minimum resolution unit of the analog color TV camera from one end to the other end by a color analog-digital conversion circuit, and the converted red, green, and blue colors The strength value of From one end to the other end, the digital signal composed of the number of resolutions of the analog color TV camera is sequentially stored in correspondence with each constituent point, and one horizontal scanning line is configured from one end to the other end. By comparing the point color intensity measurement signal with the component point value and the preset paper baseline value for each component point sequentially, the first time the color becomes stronger than the paper baseline value. When the color becomes weaker than the paper base line value, it is determined as a non-shadow area.From the next time, the color becomes weaker than the paper base line value, and the color becomes stronger than the paper base line value. When the color becomes weaker than the value of the reference line, it is determined as a non-shadow portion, the determined non-shadow portion is regarded as the back portion of the paper, the number of back portions is added up to count the number of sheets, and from one end to the other Is the color strength of the component point where the color is stronger than the paper reference value to the edge? The value obtained by subtracting the color strength of the paper reference line is added up to the point before the component point where the color became weaker than the next paper reference value to obtain the area of each paper, and then the average area is calculated from the number of paper sheets. A highly accurate abnormality detection method for folded paper, characterized in that an abnormality is detected by calculating and comparing the area of each paper with the average area or the area of a normal paper.   Arrange the folded sheets so that the back is aligned on the same plane, press the aligned sheets from both sides with pressing plates, and irradiate light from the front of the back diagonally to the recess between the back and shadow. A non-shadow portion is generated in the analog monochromatic television camera from the front with the holding plates on both sides and the backs of the aligned plural sheets, and the shadow portion of the concave portion is the analog monochromatic television. The image signal obtained from the camera is imaged so as to be perpendicular to the horizontal scanning line of the image signal, and the intensity of the luminance of the analog signal for one horizontal scanning line of the back imaging unit of the obtained analog monochrome image signal is determined from one end. A monochrome analog-to-digital conversion circuit converts the value to a multivalued value for each minimum resolution unit of the analog monochrome television camera up to the other end, and converts the converted luminance intensity value from one end to the other end. Thus, the digital signal composed of the number of resolutions of the analog monochrome TV camera is sequentially stored in correspondence with each component point, and the luminance of the component point corresponding to one horizontal scanning line from one end to the other end is increased. The measurement signal is sequentially compared for each constituent point with the value of the constituent point and the preset value of the paper reference line. For the first time, the brightness becomes stronger than the value of the paper reference line. When the brightness becomes weaker than the value, it is determined as a non-shadow part, and from the next time the brightness becomes weaker than the paper baseline value, the brightness becomes stronger than the paper baseline value and the paper baseline value. When the brightness decreases, it is determined as a non-shadow part, the determined non-shadow part is regarded as the back of the paper, the number of backs is added up to count the number of sheets, and the paper reference value from one end to the other end The intensity of the brightness of the component point with higher intensity Then, the value obtained by subtracting the intensity of the paper reference line is added up to the point before the component point where the brightness became lower than the next paper reference value to obtain the area of each paper, and then the average area from the number of papers And detecting the abnormality by comparing the area of each sheet with the average area or the area of a normal sheet.   Arrange the folded sheets so that the back is aligned on the same plane, press the aligned sheets from both sides with pressing plates, and irradiate light from the front of the back diagonally to the recess between the back and shadow. A non-shadow portion is generated, and the holding plates on both sides and the back portions of the plurality of aligned sheets are a digital TV camera from the front, and the shadow portion of the recess is from the digital TV camera. The obtained image signal is imaged so as to be perpendicular to the horizontal scanning line, and the strength of the image signal for one horizontal scanning line of the back imaging unit of the obtained image signal is calculated from one end to the other end. The digital signal composed of the number of resolutions of the TV camera is sequentially stored corresponding to each component point, and the intensity of the image signal of the component point corresponding to one horizontal scanning line from one end to the other end is sequentially determined. For each component point, the value of the component point Compared with the paper reference line value that has been set in advance, the image signal becomes stronger than the paper reference line value for the first time, and when the image signal becomes weaker than the paper reference line value, it is determined as a non-shadow area. From the next time the image signal becomes weaker than the paper reference line value, the image signal becomes stronger than the paper reference line value, and the image signal becomes weaker than the paper reference line value. The determined non-shadow portion is the back portion of the paper, and the number of the back portions is added up to count the number of sheets, and the image signal of the constituent point where the image signal is stronger than the paper reference value from one end to the other end The value obtained by subtracting the strength of the image signal of the paper reference line from the strength of the paper is added up to the point before the component point where the image signal was weaker than the next paper reference value to obtain the area of each paper, and then Calculate the average area from the number of sheets, and calculate the area of each sheet as the average surface. Or by comparing the area of the normal paper, folding and detects an abnormality processed precision abnormality detection method of the sheet.

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