JP2006315288A - Plate-making apparatus and stencil printing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plate-making apparatus and a stencil printing apparatus by which the problems of difficulty in setting an optimum plate-making condition and the occurrence of strike-through, set-off and winding-up jam are solved. <P>SOLUTION: The plate-making apparatus comprises an image information holding section which temporarily holds either one or both of image information input from an image information input section 131 and binary image information from an image conversion section 132, an image dividing section for dividing the image information held by the image information holding section into two or more small regions, and an image discriminating section for computing the feature quantity of the image information of respective small regions divided by the image dividing section. The apparatus adaptively controls the condition setting of the plate-making corresponding to the feature quantity of the image information of respective small regions. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a stencil printing apparatus and a stencil printing apparatus.

  In a stencil printing device, a stencil sheet is heated and melted by a thermal head by a stencil printing unit to punch and stencil master is wound around the outer peripheral surface of a porous and cylindrical plate cylinder, and ink is applied to the inner peripheral surface of the stencil cylinder. Then, the printing paper is pressed against the master wound around the outer peripheral surface of the plate cylinder by the pressing body, and the ink exuded from the perforated portion of the master is transferred to the printing paper for printing. The plate-making unit controls the energy of the thermal head based on the temperature and humidity detected by the sensor, thereby fading the printed image due to insufficient ink ejection when the temperature is low, and printing due to excessive ink ejection when the temperature is high. A roll-up jam that causes the paper to wind around the plate cylinder, making it impossible to discharge, a back-through that the ink of the previous print adheres to the back of the next print, and the ink on the front of the print oozes out to the back of the print This prevents problems such as turning over.

  Patent Document 1 discloses a physical quantity representative of the temperature of a thermal head in a method for controlling a thermal head for thermal plate making, in which a dot matrix type plate making for each dot is formed on a thermal stencil sheet for each dot, For example, the interval time of the plate making operation for each line by the thermal head is measured prior to the plate making operation for each line, it is determined whether or not this interval time is a predetermined value or more, and the interval time is a predetermined value or more. In this case, there is described a method for controlling the thermal head for thermal plate making, in which the thermal head is driven to generate heat (preheat) with an output greater than a quantitative output that does not change the thermal stencil sheet.

  Patent Document 2 discloses a thermal head based on a humidity data signal related to humidity information detected by a humidity sensor in a microcomputer and based on a signal related to a low humidity environment drive condition variable instruction from a humidity control on / off key. A plate-making printing apparatus is described that controls a thermal head drive circuit and the like so as to change the energization cycle (printing cycle) to each of the heating elements and to change the energy applied to each heating element of the thermal head.

  In Patent Document 3, an image signal of two pages of front and back pages is read by an image reading unit and output to a control unit. The control unit performs image processing by A / D converting the image signal and then image memory. The image data of the area for 100 lines is sequentially read out from the image memory, and the image density detection unit calculates the percentage of the number of black data with respect to the total number of data as the image density, and the front and back surfaces stored in the image memory. If the image density of the image data is 30% or less, the image data is almost composed of characters. Therefore, the image data is printed at a normal print density, and the image data exceeds 30% in at least one area of the image data. In some cases, since a solid part is included, a double-sided printing device is described that performs stencil data to reduce the print density by performing a thinning process, which is a process for reducing the print density, on the front and back image data. It has been.

Japanese Patent Laid-Open No. 7-314763 JP-A-2005-35091 JP 2004-306462 A

  In the stencil printing apparatus, by controlling the energy of the thermal head based on the temperature and humidity detected by the sensor, the printed image is blurred due to insufficient ink ejection when the temperature is low, and due to excessive ink ejection when the temperature is high. It prevents problems such as roll-up jams, breakthroughs, and setbacks. However, the energy control of the thermal head is performed collectively over the entire image surface, and the content of the image is not considered.

  For this reason, as a result of controlling the energy of the thermal head, it is difficult to set optimal plate-making conditions for the entire image, such as excessive ink supply in the photographic image area even if the solid image area is well filled. there were. In addition, when trying to make a plate and print an image with a particularly large solid portion at the leading edge of the stencil sheet in the paper discharge direction, the above-mentioned control alone may cause back-through and set-off. There was a case where jamming occurred without preventing the roll-up.

An object of the present invention is to provide a plate making apparatus and a stencil printing apparatus which can set optimum plate making conditions and can provide a print image with good image quality.
Another object of the present invention is to provide a plate-making apparatus and a stencil printing apparatus that can prevent occurrence of show-through, set-off, and roll-up jam.

  In order to achieve the above object, an invention according to claim 1 includes an image information input unit that inputs image information, and an image conversion unit that converts the image information input by the image information input unit into binary image information. A plate making unit for punching a perforated base paper based on binary image information from the image conversion unit, image information input by the image information input unit, and binary image information from the image conversion unit An image information holding unit that temporarily holds one or both of the above, an image dividing unit that divides the image information held in the image information holding unit into one or more small regions, and an image dividing unit An image discriminating unit that calculates a feature amount of the image information of each divided small area, and adaptively controls the platemaking condition setting according to the feature amount of the image information of each small area.

  According to a second aspect of the present invention, in the plate making apparatus according to the first aspect, the feature amount of the image information of each small area divided by the image dividing unit is defined by the Mahalanobis distance.

  According to a third aspect of the present invention, in the plate making apparatus according to the first aspect, the feature amount of the image information of each small area divided by the image dividing unit is calculated from the binary image information converted by the image converting unit. This is defined by the dot density of the output pattern.

  According to a fourth aspect of the present invention, in the plate making apparatus according to any one of the first to third aspects, the energy of the plate making is adaptively controlled as a condition setting of the plate making.

  According to a fifth aspect of the present invention, in the plate making apparatus according to any one of the first to fourth aspects, the dot density of the output pattern is adaptively controlled as the condition setting of the plate making.

  The invention according to claim 6 is the plate making apparatus according to any one of claims 1 to 5, wherein a plurality of plate making conditions according to the feature amount of the image information of each small area calculated by the image discriminating unit. It has a plate making condition storage unit for storing and a sensor for measuring at least one of temperature and humidity, and the plate making condition is selected from a plurality of plate making conditions stored in the plate making condition storage unit, The selection is made adaptively according to the printing condition including the feature amount of the image information of each small area and the measurement result of the sensor.

  The invention according to claim 7 is the plate making apparatus according to any one of claims 1 to 6, wherein the plate making condition storage unit holds a plurality of sets of plate making conditions, and the plate making conditions are the plurality of sets of plate making. From the conditions, each user adaptively selects from the plate making conditions of the set selected according to the purpose.

  The invention according to claim 8 is the plate making apparatus according to any one of claims 1 to 7, wherein the plate making conditions stored in the plate making condition storage unit can be rewritten by a user within a limited range. There is something.

  The invention according to claim 9 is the plate making apparatus according to any one of claims 1 to 8, wherein the plate making conditions determined for the image information of each small area divided by the image dividing unit are The plate-making conditions that are applied to the central pixels of the small areas and are determined for the pixels other than the central pixels of the small areas are the plate-making conditions determined for the central pixels of the adjacent small areas. It is determined by interpolation processing.

  A tenth aspect of the present invention is a stencil printing apparatus including the plate making apparatus according to any one of the first to ninth aspects.

According to the present invention, it is possible to set an optimum plate-making condition and provide a printed image with good image quality.
According to the present invention, it is possible to prevent the occurrence of show-through, set-off, and roll-up jam.

FIG. 17 shows the overall configuration of a digital thermal stencil printing apparatus having a plate making apparatus according to an embodiment of the present invention.
A document reading device 80 is mounted on the upper portion of the apparatus main body frame 50, and a digital thermal plate-making plate making section 19 is disposed below the document reading device 80. A printing drum device 100 in which a printing drum 101 as a porous plate cylinder is disposed is provided on the left side of the plate making unit 19, and a plate discharging device 70 is disposed on the left side thereof. A sheet feeding device 110 is disposed below the plate making unit 19, and a printing pressure device 120 is disposed below the printing drum 101. A paper discharge device 130 is disposed at the lower left of the apparatus main body frame 50.

  A user places an original 60 having an image to be printed on an original placement table (not shown) disposed on the upper part of the original reading device 80, and presses a plate-making button on a control panel or a personal computer (hereinafter referred to as a personal computer). When instructing plate making via a network from a PC), a plate discharging process is first executed. At this time, the used master 12 used in the previous printing remains attached to the outer peripheral surface of the printing drum 101 of the printing drum apparatus 100.

  When the printing drum 101 rotates counterclockwise and the rear end portion of the used master 12 on the outer peripheral surface of the printing drum 101 approaches the plate release peeling roller pair 71a, 71b in the plate discharging device 70, the roller pair 71a, 71b is While rotating, the rear end portion of the used master 12 is scooped up by one of the discharge plate peeling rollers 71b, and the discharge plate roller pairs 73a and 73b and the discharge plate peeling roller pair 71a disposed on the left side of the discharge plate peeling roller pairs 71a and 71b, While being conveyed in the direction of arrow Y1 by the pair of discharged plate conveying belts 72a and 72b stretched between 71b, the discharged master 74 is discharged into the discharged plate box 74, and the used master 12 is peeled off from the outer peripheral surface of the printing drum 101. Ends. At this time, the printing drum 101 continues to rotate counterclockwise. The used master 12 that has been peeled and discharged is then compressed inside the plate discharge box 74 by the compression plate 75.

  In parallel with the plate removal process, the document reader 80 reads the document. That is, the document 60 placed on a document placement table (not shown) is conveyed in the directions of arrows Y2 to Y3 by the rotation of the separation roller 81, the front document conveyance roller pair 82a and 82b, and the rear document conveyance roller pair 83a and 83b. While reading the image. When there are a large number of documents 60, only the lowermost document is conveyed by the action of the separating blade 84. In reading the image of the original 60, the original 60 is conveyed on the contact glass 85, illuminated by the fluorescent lamp 86, and the reflected light is reflected by the mirror 87, and then the CCD (photoelectric conversion element such as a charge coupled device) is passed through the lens 88. This is performed by entering the image sensor 89. The document 60 from which the image has been read is discharged onto the document tray 80A.

  Reflected light from the document 60 is photoelectrically converted by the image sensor 89, and an analog image signal, which is an analog electric signal, is converted into a digital image signal by an analog / digital converter (not shown). As will be described later, the digital image signal is converted into binary image data by an image conversion unit and input to a thermal head driving circuit.

  On the other hand, the plate making and plate feeding steps are performed in parallel with the image reading operation. That is, the stencil sheet 12 b is set so as to be able to be fed out to a predetermined part of the plate making unit 19, drawn out from a stencil sheet roll 12 A formed in a roll around the core tube 12 a, and is stencil sheet 12 b to the thermal head 10. The platen roller 14 that is pressed through the roller and the pair of tension rollers 15a and 15b are rotated downstream in the sub-scanning direction Y (also in the stencil sheet conveying direction). With respect to the stencil sheet 12b conveyed in this manner, a large number of (a plurality of) minute heating elements 9 arranged in a line in the main scanning direction perpendicular to the sub-scanning direction Y of the thermal head 10 include the thermal head. Thermoplasticity of the stencil sheet 12b that is selectively driven by the drive circuit in accordance with the binary image data and generates heat and is in contact with the generated heat generating element 9 through a protective film layer (not shown). The resin film portion is heated and melted to be perforated. In this manner, the master 12 is manufactured by writing the image information as a perforation pattern on the stencil sheet 12b by selective melting and perforation of the stencil sheet 12b according to the binary image data.

  The platen roller 14 is connected to the stencil sheet feed motor 11 through a rotation transmission member (not shown) such as a timing belt and a gear, and is rotated by the stencil sheet feed motor 11. The rotational driving force of the master feed motor 11 is applied to a pair of upper and lower reversing rollers 17a, 17b via a tension transmission pair 15a, 15b and an electromagnetic clutch (not shown) via a rotation transmission member (not shown) such as a gear. It is to be transmitted.

The leading end of the master 12 is fed toward the outer peripheral side of the printing drum 101 by the pair of reverse rollers 17a and 17b while being guided on the guide plate 16, and the traveling direction is changed downward by the plate feed guide plate 18 as shown in the figure. The printing drum 101 in the plate feeding position state hangs down toward the expanded master clamper 102 (indicated by a two-dot chain line). At this time, the used master 12 has already been removed from the printing drum 101 by the plate discharging process.
When the leading end of the master 12 is clamped by the master clamper 102 at a fixed timing, the printing drum 101 rotates in the direction A (clockwise direction) in the figure and gradually winds the master 12 that has been subjected to plate making around the outer peripheral surface. Go. The rear end of the master 12 that has been subjected to plate making is cut into a fixed length by a cutter 13.

  When the preprinted master 12 of one plate is wound around the outer peripheral surface of the printing drum 101, the plate making and plate feeding processes are finished, and the printing process is started. First, the uppermost one of the printing sheets 62 stacked on the sheet feeding table 51 is sent in the direction of arrow Y4 toward the registration roller pair 113a and 113b by the sheet feeding roller 111 and the separation roller pair 112a and 112b. Further, it is sent to the printing pressure device 120 at a predetermined timing synchronized with the rotation of the printing drum 101 by the registration roller pair 113a, 113b. When the fed printing paper 62 comes between the printing drum 101 and the press roller 103, the press roller 103 that has been separated below the outer peripheral surface of the printing drum 101 moves upward, so that the outer periphery of the printing drum 101 is moved. It is pressed by the master 12 that has been pre-rolled around the surface. In this way, ink oozes out from the perforated portion of the printing drum 101 and the perforated pattern portion of the master 12 that has been made (not shown), and the oozed ink is transferred to the surface of the printing paper 62 to form a printed image. Is done.

  At this time, on the inner peripheral side of the printing drum 101, ink is supplied from the ink supply pipe 104 to the ink reservoir 107 formed between the ink roller 105 and the doctor roller 106, and in the same direction as the rotation direction of the printing drum 101. Ink is supplied to the inner peripheral side of the printing drum 101 by the ink roller 105 that is in contact with the inner peripheral surface while rotating in synchronization with the rotation speed of the printing drum 101. The ink supply tube 104, the ink roller 105, and the doctor roller 106 constitute an ink supply unit that supplies ink to the master 12 that has been made on the printing drum 101.

The printing paper 62 on which the printing image is formed in the printing pressure device 120 is peeled off from the print drum 101 by the paper discharge peeling claw 114 in the paper discharge device 130 and sucked by the suction fan 118, while the suction paper discharge inlet roller 115 and By the counterclockwise rotation of the conveyor belt 117 that is stretched around the suction discharge outlet roller 116, it is conveyed toward the sheet discharge device 130 as indicated by the arrow Y5, and is sequentially discharged onto the sheet discharge tray 52 and stacked. Is done. In this way, so-called plate printing is completed.
Next, when the number of prints is set with a numeric keypad (not shown) and the plate making is instructed as described above, each of the paper feeding, printing, and paper discharge steps is repeated for the set number of prints in the same process as the plate printing. This is done and the entire process of stencil printing is completed.

  As shown in FIG. 1, the plate making apparatus of the present embodiment includes a data input unit 131 as an image information input unit for inputting a plurality of bits, for example, 8-bit image data from a document reading device (hereinafter referred to as a scanner) 80 or a PC. The plate making condition setting unit 132 to which the image information from the data input unit 131 is input, and the image conversion unit that converts the image information from the data input unit 131 into binary pseudo grayscale image information (binary image data). 133 and the plate making unit 19 in which the plate making conditions are set by the plate making condition setting unit 132 and the binary image data is input from the image conversion unit 133 may be included. However, as shown in FIG. The binary image data from the unit 133 may be input to the plate making condition setting unit 134 as a 1-bit output dot pattern.

  Here, as shown in FIG. 3, the plate making apparatus of the present embodiment includes a data input unit 131 as an image information input unit for inputting image data of a plurality of bits, for example, 8 bits from a scanner 80 or a PC, and this data input. A plate making condition setting unit 132 to which image information from the unit 131 is input, an image conversion unit 133 that converts the image information from the data input unit 131 into binary pseudo-grayscale image information (binary image data), and an image The plate making condition setting unit 134 to which the binary image data from the conversion unit 133 is input as a 1-bit output dot pattern, and the plate making conditions are set by the plate making condition setting units 132 and 134, and the binary value from the image conversion unit 133 is set. And a plate making unit 19 to which the image data is input.

  When the user presses the plate making button on the control panel or instructs the plate making from the PC via the network, the 8-bit image information input from the scanner 80 or from the PC via the network to the data input unit 131 is the plate making condition setting unit 132 and The image conversion unit 133 inputs the image information to binary image data and outputs the binary image data to the thermal head driving circuit and the plate making condition setting unit 134.

  In the plate making condition setting unit 132, as shown in FIG. 4, the image information from the data input unit 131 is temporarily stored in the data storage unit 135 as an image storage unit, and the image dividing unit 136 is stored in the data storage unit 135. The obtained image information is divided into one or more small area image data. In this small region, as shown in FIG. 6A, image data in which pixels are arranged in a matrix in the main scanning direction and the sub-scanning direction is simply N1 pixels in the main scanning direction and every N2 pixels in the sub-scanning direction. Can be divided into regions A, B, C... For each of N1 × N2 pixels, or each pixel when image information is raster scanned as shown in FIGS. It is good also as a rectangular or circular area | region centered. However, platemaking conditions are determined for each small area, but if a rectangular or circular area centered on a pixel is defined as the small area, the platemaking conditions determined for each small area are determined for the central pixel of the small area. Only applies.

  Image information input to the plate making apparatus of the present embodiment can be broadly classified into two types of image information: character image information and photographic image information. FIG. 7 shows an example of a density histogram of character image information, and FIG. 8 shows an example of a density histogram of photographic image information. In the density histogram, the horizontal axis represents the image density, and the vertical axis represents the existence frequency of the density. Here, the amount of calculation can be reduced by removing non-image portions such as the background from the image information by threshold processing and making only the image portions subject to calculation of the plate making conditions. As shown in FIG. 7, the density histogram of the character image information tends to be a unimodal distribution indicating the character portion, and the density histogram of the photographic image information is compared with the density histogram of the character image information as shown in FIG. In many cases, it shows a flat distribution.

  The image data of each small region divided by the image dividing unit 136 is transferred to the image determining unit 137, and the image determining unit 137 determines whether the image data of each small region from the image dividing unit 136 is classified as character image data. Alternatively, it is determined using the Mahalanobis distance whether the image data is classified. The Mahalanobis distance is an index that is used, for example, to determine whether the newly input data is included in C1 or C2 distribution when given distributions C1 and C2. There are various calculation methods. Here, the simplest calculation method will be described.

FIG. 9 is a histogram showing the standard deviation values of density calculated from a large number of character image data and photographic image data. As shown in FIG. 9, the character image data has a small density change, that is, the standard deviation distribution is concentrated in a small region, and the photographic image data has a wider distribution than the character image data.
Now, the standard deviation histogram shown in FIG. 9, the average value m _T of the standard deviation of the character image _data, and the distribution and V _T, the average value of m _P of the standard deviation of the photographic image _data, the distribution V _P And When the standard deviation of the density in the image data of each small area divided by the image dividing unit 136 is x, the Mahalanobis distance D _T of the character image data of each small area and the Mahalanobis distance D of the photographic image data of each small area _P is obtained by the following equation.

D _T ² = (x−m _T ) ² / V _T (1)
D _P ² = (x−m _P ) ² / V _P (2)
In order to determine whether the image data of each small area is character image data or photographic image data, the following determination formula using the above two formulas is calculated.
J = D _T -D _P (3)
Here, J <0 indicates that the small area image data is classified as character image data, and J> 0 indicates that the small area image data is classified as photographic image data.

The image determination unit 137 stores the average values m _T and m _P and the distributions V _T and V _P of the standard deviation of the density of the image data measured in advance using a large number of character image data and photographic image data in the storage unit. Whether or not the image data of each small area stored and divided by the image dividing unit 136 is classified as character image data or photographic image data is determined by the above calculation. Here, for the sake of simplicity, description has been made with one variable (standard deviation value of concentration), but the same applies to the case of multiple variables. The Mahalanobis distance D in the case of multiple variables (i variables) is obtained by the following equation.

_{^{D 2 = (x i -m i}} ) T C (x i -m i) ··· (4)
Here, T represents transposition of the matrix, and C represents a covariance matrix between each variable of the character image or the photographic image.
As shown in FIGS. 10 to 12, the plate-making condition storage unit 138 includes thermal heads (T / T) for each of the surroundings of the present embodiment, for example, the temperature and humidity around the plate-making unit 19 and the feature amount J of the image data of each small area. H) An energy rate of 10 is stored.

  A temperature sensor for detecting the temperature and a humidity sensor for detecting the humidity are installed in the vicinity of the present embodiment, for example, in the vicinity of the plate making unit 19, and the image determination unit 137 has the feature amount of the image data of each small region as described above. When J is calculated, the plate making conditions of the plate making unit 19 are determined with reference to the data stored in the plate making condition storage unit 138 from the feature amount J, the temperature data from the temperature sensor, and the humidity data from the humidity sensor. Set the plate making conditions.

The energy rate of the thermal head (T / H) 10 with respect to the temperature detected by the temperature sensor is r _A1 , the energy rate of the thermal head (T / H) 10 with respect to the humidity detected by the humidity sensor is r _A2 , and image data of each small region. When the energy rate of the thermal head (T / H) 10 with respect to the characteristic quantity J is r _A3 , the energy rate R _A of the thermal head (T / H) 10 with respect to the small region is obtained by the following equation.

R _A = r _A1 × r _A2 × r _A3 (5)
As a result of the calculation of Expression (5), R _A becomes a real value of 1.00 or less, and the plate making conditions of the plate making unit 19 are controlled by the energy rate R _A of the thermal head 10. This makes it possible to perform appropriate plate making control based on the contents of the image as well as the printing environment such as temperature and humidity, and provide a higher quality printing result. Here, the plate making conditions of the plate making unit 19 are controlled by the energy rate R _A of the thermal head 10, which is the voltage or pulse applied to the thermal head 10 as the plate making conditions of the plate making unit 19 by the thermal head driving circuit. This is realized by controlling the width (energization time width) by the energy rate R _A of the thermal head 10.

  Further, the image conversion unit 133 converts the input multi-value image information into binary image information (image information indicating whether or not to stencil on a stencil sheet), that is, the output pattern of this embodiment. In the plate making condition setting unit 134, as shown in FIG. 5, binary image information from the image conversion unit 133 is temporarily stored in a data storage unit 139 as an image storage unit, and the image division unit 140 stores data. Similar to the image dividing unit 136, the image information stored in the unit 139 is divided into one or more small area image data as described above. The physical quantity of each small area is calculated by the output dot density. This output dot density is obtained as follows.

Output dot density = number of output dots / total number of pixels included in the small area (6)
As shown in FIGS. 13 to 15, the plate making condition storage unit 142 stores an output dot rate (perforation dot rate) for each of the temperature, humidity, and output dot density around the present embodiment, for example, near the plate making unit 19. ing.
When the image determination unit 141 calculates the output dot density of each small area as described above, the plate making condition storage unit 141 has the output dot density, the temperature data from the temperature sensor, and the humidity data from the humidity sensor. The plate-making conditions are set by determining the plate-making conditions of the plate-making unit 19 with reference to the stored data.

When the output dot rate for the temperature detected by the temperature sensor is r _B1 , the output dot rate for the detected humidity of the humidity sensor is r _B2 , and the output dot rate for the output dot density of each small region is r _B3 , the final output dot rate R _B is obtained by the following equation.
R _B = r _B1 × r _B2 × r _B3 (7)
As a result of the calculation of Expression (7), R _B becomes a real value of 1.00 or less. After calculating the dot rate R _B , the image determination unit 141 sets the plate making conditions by determining to thin out the output dots of each small area in accordance with the dot rate R _B. Various output dot thinning methods are conceivable. The simplest output dot thinning method is a method in which the thermal head drive circuit decimates the output dot in a grid in accordance with the dot rate R _B in each small region, the small region division as shown in FIG. 6 (a) This is effective when

Valid Output dot thinning method when you have made small region division as shown in FIG. 6 (b) (c), for example, if the dot rate R _B of a dot is determined, the thermal head drive The dot is perforated in the thermal head 10 only when the random number value rand (0, 1) of 0 to 1 generated by the circuit using the random number generation algorithm satisfies the following conditions, otherwise the dot is not perforated. Thus, there is a method of processing binary image data.

rand (0,1) <R _B (8)
In Expression (8), it is possible to prevent occurrence of periodic dot omission by determining whether or not to thin out dots using random numbers.
By the processing using such a dot thinning method, it is possible to prevent the occurrence of jam due to excessive ink ejection even when an image having a large solid area is printed in a high-temperature and high-humidity printing environment. In addition, when the solid image is concentrated on the leading edge of the printing paper in the case of high temperature and high humidity, the printing paper can be obtained only by controlling the plate-making energy (heating energy of the thermal head 10) and the dot thinning process. In the case where it is impossible to prevent the occurrence of “rolling jam” that sticks to the printing drum 101 and cannot be discharged, such a case is determined from the image data by the determination means, and the thermal head driving is performed. The image data may be processed by a circuit or the like so that the front and back of the image with respect to the printing paper discharge direction are reversed.

When the above-described processing is completed and the plate-making conditions in all areas of the image are determined, the plate-making unit 19 punches the stencil sheet according to these plate-making conditions to create a master 12, and transfers the master 12 to the printing drum 101. Wind and start printing.
As described above, the plate-making conditions in each small area are determined from the feature quantity, temperature, humidity, etc. of the small area. The platemaking conditions are stored in advance in the platemaking condition storage units 138 and 142, but a plurality of sets (a plurality of sets) of platemaking conditions (temperature, humidity, and characteristics of image data of each small region are set according to the user's request. It is possible to input the energy ratio of the thermal head 10 with respect to each of the amounts J, the output dot ratio with respect to each of temperature, humidity, and output dot density) from the operation unit, and additionally store them in the plate making condition storage units 138 and 142. The user can select one set of plate making conditions with the operation unit from among a plurality of sets of plate making conditions set in the plate making condition storage units 138 and 142, and the plate making condition setting units 132 and 134. Determines one platemaking condition from a set of platemaking conditions selected by the user in accordance with a selection signal from the operation unit, as described above, from the feature amount of the small area, the temperature, the humidity, and the like. The plate making condition setting units 132 and 134 cause the plate making conditions in the plate making condition storage units 138 and 142 to be rewritten within a range limited in advance by the plate making conditions input from the operation unit by the user, and the plate making condition storage unit. When the plate making conditions additionally stored in 138 and 142 are set, the setting range of the plate making conditions is limited to the extent that no trouble occurs during plate making or printing. As a result, it is possible to prevent machine failure and extreme deterioration of image quality.

  As shown in FIGS. 6B and 6C, when a small region is defined by a rectangular or circular region centered on each pixel, the pixel is centered in order to define a plate making condition at an arbitrary pixel position. It is necessary to calculate the physical quantity of the rectangular or circular area, and the processing speed may decrease due to the increase of the calculation quantity. However, since the plate-making conditions are set for each pixel, the processing step at the boundary portion of each adjacent small region is different from the case where the small region is simply divided into NI × N2 pixels as shown in FIG. There is an advantage that it does not occur.

  In addition, when the small area is simply divided into NI × N2 pixels as shown in FIG. 6A, the plate-making conditions determined in the small area are applied only to the central pixel of the small area. The plate-making conditions for the pixels are determined by interpolation processing using the plate-making conditions for the center pixel of each adjacent small region by the plate-making condition setting units 132 and 134, thereby preventing a processing step at the boundary portion of each adjacent small region. Is possible.

FIG. 16 shows an example of the interpolation processing.
Assume that the distance between central pixels of four adjacent small regions is 1, and each position is (x, y), (x + 1, y), (x, y + 1), (x + 1, y + 1). If each platemaking condition (thermal head energy rate or output dot rate) is R (x, y), R (x + 1, y), R (x, y + 1), R (x + 1, y + 1), platemaking condition setting The units 132 and 134 obtain the plate-making conditions R (u, v) at arbitrary positions (u, v) existing inside the quadrangle formed by the four central pixels by the following expression.

R (u, v) = (1−L _y ) {(1−L _x ) R (x, y) + L _x R (x + 1, y) + L _y {(1−L _x ) R (x, y + 1) + L _xR (x + 1, y + 1) (9)
According to the present embodiment, the input image information is divided into one or more small areas, and a feature value that is an index representing “character image quality” or “photograph image quality” is calculated for each small area. By setting the plate making conditions based on the feature amount, it is possible to provide an optimal ink discharge amount in each small region, and it is possible to provide a higher quality printing result. In addition, since ink consumption can be minimized, printing costs can be reduced, and furthermore, ink on the paper surface oozes out to the back of the paper when the printed paper is stacked due to excessive ink ejection. It is possible to prevent occurrence of “back-up” in which the ink of the previous printed matter adheres to the back side of the next printed matter, and “roll-up jam” that sticks to the printing drum and cannot be discharged.

According to the present embodiment, it is possible to perform more stable image discrimination by using the Mahalanobis distance as a feature amount that is an index representing “character image quality” or “photo image quality” of each small region.
The occurrence of the roll-up jam can be predicted by the ratio of the solid image, that is, the dot density of the binarized output dot pattern. In the present embodiment, by calculating the dot density of the output dot pattern in the small region, it is possible to predict the occurrence of show-through, set-off, or roll-up jam.

According to the present embodiment, by controlling the heat generation energy of the thermal head as the plate-making condition, it becomes possible to control the diameter of the holes punched in the stencil sheet, and the ink discharge amount can be controlled.
Controlling the dot density of the output pattern as the plate making condition indicates that the dot thinning process is performed. In the present embodiment, if there is a risk of occurrence of behind-the-scenes, set-off, or roll-up jams from the dot density of the output pattern, the output dots are thinned out to the extent that roll-up jams do not occur. As a result, it is possible to prevent ink from being over-discharged and to prevent the occurrence of roll-up jams.

  The amount of ink transferred to the printing paper and the degree of bleeding are greatly affected by the printing environment such as temperature and humidity. In the present embodiment, after calculating a feature value indicating “character image quality” or “photo image quality” or a feature value indicating whether or not a roll-up jam occurs, it is not necessary to control the plate-making conditions using only this feature value. In addition, the platemaking conditions are determined in consideration of the printing environment such as temperature and humidity. As a result, it is possible to provide an optimal printing result under any environment.

  The correspondence between parameters such as temperature, humidity, and feature quantity set during development and the platemaking conditions is not necessarily optimal for all users. The optimum plate making conditions need to be finely adjusted depending on the user's preference, the climate of the user's living area, and the like. Therefore, in the present embodiment, a plurality of sets of correspondences between parameters and plate making conditions are stored in advance in the plate making condition storage units 138 and 142 in the apparatus, and the user sets one set among them according to his / her preference and environment. Can be selected, so that an optimum print result can be provided without being influenced by the user's preference or the climate of the user's living area.

  As described above, the correspondence relationship between the parameters such as temperature, humidity, and feature quantity set at the time of development and the plate making conditions is not necessarily optimal for all users. For example, even if a plurality of sets of correspondences between parameters and plate making conditions are stored in the apparatus during development, it is conceivable that the user cannot obtain the desired printing result. Therefore, in the present embodiment, it is possible for the user to arbitrarily set the correspondence between each parameter such as temperature, humidity, and feature quantity and the plate making conditions, thereby providing an optimal printing result to all users. Is possible.

  However, if the user completely sets the correspondence between each parameter and the plate making conditions, depending on the conditions, there is a possibility that the image quality of the printing result will be remarkably lowered, or in the worst case, a machine failure may be caused. . Therefore, in the present embodiment, the platemaking conditions that can be set by the user are limited to a range in which the machine can operate stably and a certain level of image quality can be secured. As a result, it is possible to prevent a significant deterioration in image quality due to an inappropriate setting change by the user and to prevent a machine failure.

  When the image is divided into small areas, the simplest method is to simply divide the image into rectangular areas for every N1 × N2 pixels. However, in this method, since the plate making conditions are determined in each small region, there is a possibility that a step in the plate making conditions may occur at the boundary between adjacent small regions. If a level difference in plate making conditions appears on the printed matter as a boundary line, it may be recognized as an unnatural pattern by human eyes. Therefore, in this embodiment, the plate-making conditions determined in each small area are applied only to the central pixel of the small area, and the plate-making conditions at an arbitrary pixel position are applied to the central pixel of the small area. It is determined by interpolation processing using plate making conditions and plate making conditions applied to the center pixel of each adjacent small region. Thereby, it is possible to prevent a step of the plate making condition from occurring at the boundary portion between each adjacent small region, and it is possible to provide a visually natural printing result.

It is a block diagram which shows the example of the plate-making apparatus of one Embodiment of this invention. It is a block diagram which shows the other example of the plate-making apparatus of the embodiment. It is a block diagram which shows another example of the plate-making apparatus of the embodiment. It is a block diagram which shows the platemaking condition setting part of the platemaking apparatus. It is a block diagram which shows the other platemaking condition setting part of the platemaking apparatus. It is a figure for demonstrating each method which divides | segments image information into a small area in the said platemaking condition setting part. It is a figure which shows the example of the density histogram of character image information. It is a figure which shows the example of the density histogram of photographic image information. It is a figure which shows the value of the standard deviation of the density | concentration calculated from each of many character image data and photographic image data with a histogram. It is a figure which shows the energy rate of the thermal head with respect to the air temperature of a stencil printing apparatus. It is a figure which shows the energy rate of the thermal head with respect to the humidity of a stencil printing apparatus. It is a figure which shows the energy rate of the thermal head with respect to the feature-value of the image data of each small area | region of a stencil printing apparatus. It is a figure which shows the output dot rate with respect to the air temperature of a stencil printing apparatus. It is a figure which shows the output dot rate with respect to the humidity of a stencil printing apparatus. It is a figure which shows the output dot rate with respect to the output dot density of a stencil printing apparatus. It is a figure which shows the example of an interpolation process. It is sectional drawing which shows one Embodiment of this invention.

Explanation of symbols

131 Data Input Unit 132, 134 Plate Making Condition Setting Unit 133 Image Conversion Unit 135, 139 Data Storage Unit 136, 140 Image Dividing Unit 137, 141 Image Discriminating Unit 138, 142 Plate Making Condition Setting Unit

Claims (10)

  Based on the image information input unit that inputs image information, the image conversion unit that converts the image information input by the image information input unit into binary image information, and the binary image information from the image conversion unit Image information for temporarily holding one or both of a plate making unit for making a plate by punching perforated base paper, and image information input by the image information input unit and binary image information from the image conversion unit A holding unit, an image dividing unit that divides the image information held in the image information holding unit into one or more small regions, and a feature amount of image information of each small region divided by the image dividing unit And a plate making apparatus, wherein the plate making condition setting is adaptively controlled in accordance with a feature amount of image information of each small area. The plate making apparatus according to claim 1,
A plate making apparatus, wherein a feature amount of image information of each small region divided by the image dividing unit is defined by a Mahalanobis distance. The plate making apparatus according to claim 1,
A plate making apparatus, wherein a feature amount of image information of each small area divided by the image dividing unit is defined by a dot density of an output pattern composed of binary image information converted by the image converting unit. In the plate-making apparatus as described in any one of Claims 1-3,
A plate making apparatus that adaptively controls energy of the plate making as a condition setting of the plate making. In the plate making apparatus as described in any one of Claims 1-4,
A plate-making apparatus that adaptively controls the dot density of an output pattern as the plate-making condition setting. In the plate-making apparatus as described in any one of Claims 1-5,
A plate making condition storage unit for storing a plurality of plate making conditions according to the feature amount of the image information of each small area calculated by the image discriminating unit, and a sensor for measuring at least one of temperature and humidity. And
The plate making conditions are adaptively selected from a plurality of plate making conditions stored in the plate making condition storage unit according to printing conditions including the feature amount of the image information of each small area and the measurement result of the sensor. An apparatus for making a plate. In the plate making apparatus as described in any one of Claims 1-6,
The plate-making condition storage unit holds a plurality of sets of plate-making conditions, and the plate-making conditions are adaptively selected from among the plurality of sets of plate-making conditions according to the purpose by each user. A plate making apparatus characterized by that. In the plate-making apparatus as described in any one of Claims 1-7,
A plate making apparatus stored in the plate making condition storage unit can be rewritten by a user within a limited range in advance. In the plate-making apparatus as described in any one of Claims 1-8,
The platemaking conditions determined for the image information of each small area divided by the image dividing unit are applied to the central pixel of each small area and determined for the pixels other than the central pixel of each small area. The plate-making apparatus is characterized in that the plate-making conditions are determined by an interpolation process using the plate-making conditions determined for the central pixel of each of the adjacent small regions.   A stencil printing apparatus comprising the plate making apparatus according to any one of claims 1 to 9.

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