JP2007326245A - Printing equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To exert the stable performance of the feeding, conveying of a printing paper with various rollers and its sending in a printing unit on slippage or the like in a printing equipment. <P>SOLUTION: This printing equipment is equipped with the printing unit 2 with a rotational speed adjustable printing plate cylinder, a paper housing part 7, a paper feeding and conveying device 20 for separating printing paper one by one from the paper housing part 7 by a separately paper feeding part and conveying the printing paper to the printing unit, paper detecting devices 66, 67 and 68 for detecting a printing paper under conveying and a controller for controlling the rotational speed of the printing plate cylinder 16 or the conveying speed of the paper feeding and conveying device 20 so as to form images in the regular printing range of the printing paper based on the positions of the printing paper detected with the paper detecting devices 66, 67 and 68. In addition, the paper detecting device has an image sensor for reading the interference fringe pattern of laser beam due to the irregularities on the surface of the paper by utilizing the laser beam. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a printing apparatus that continuously prints a large number of printing sheets using a printing plate cylinder, and in particular, a printing unit having a printing plate cylinder and a pressing roller, a sheet storage unit, and the sheet storage A paper feeding / conveying device that separates the printing paper one by one from the printing unit and transports it to the image forming unit of the printing unit, and a paper detection device that detects the printing paper in the conveyance path of the paper feeding / conveying device. And a control device that controls the rotational speed of the printing plate cylinder or the transport speed of the paper feed transport device.

  FIG. 16 shows a conventional example of this type of printing apparatus (Patent Document 1), in which a printing unit 202 mainly composed of a printing plate cylinder 200 and a pressing roller 201 and a plurality of sheets for storing a large number of printing sheets P are shown. Each of the paper storage units 205 includes a storage unit 205, a paper insertion table 206, a discharge device 210 that discharges the printed paper P after printing, a paper tray 211 that stores the discharged print paper P, and the like. And a sheet feeding / conveying device 213 that separates and feeds the printing sheets P one by one from the sheet insertion table 206 and conveys them to the image forming unit of the printing unit 202.

  The sheet feeding / conveying device 213 includes a sheet feeding roller 214 that is disposed in each sheet storage unit 205 and the sheet insertion stand 206 to separate and feed the printing sheet P, and a plurality of pairs of conveying rollers disposed in the middle of the conveying path 209. 215 and a pair of timing rollers 217 and the like arranged at the conveyance end portion, and paper detection devices 220 for detecting printing paper are arranged at a plurality of locations along the conveyance path 209, respectively.

  The paper detection device 220 controls the state of the printing paper P being transported so that various operations of feeding and transporting the printing paper P to the image forming unit at a predetermined timing can be performed smoothly and as specified. Conventionally, as these paper detection devices 220, transmission type optical sensors for detecting light shielding are used.

FIG. 17 shows the details of the transport roller 215, its driving device, and the paper detection device (light sensor) 220. The transport roller 215 is linked to a drive motor 304 via a power transmission mechanism 303, and the drive motor An encoder 323 that detects a rotation angle (rotation phase position) is provided in 304, and the encoder 323 is electrically connected to the control device 320. On the other hand, the paper detection device 220 is mainly composed of a light emitting unit 312 and a light receiving unit 313 arranged with the conveyance path interposed therebetween, and the light from the light emitting unit 312 is blocked by the paper P, thereby the presence and position of the paper. Based on these detection results, the printing unit 202 and the paper feeding / conveying device 213 shown in FIG. 16 are controlled to be driven synchronously, or a paper feeding error is detected. Yes.
JP-A-6-40137

  As shown in FIGS. 16 and 17, it is difficult to detect the slip amount of the printing paper P in the paper detection device (optical sensor) 220 using light blocking and transmission. That is, in FIG. 16, paper dust or the like adheres to the outer peripheral surface of the paper feed roller 214, the transport roller 215, or the timing roller 217, or the rollers P, 215, and 217 are worn. Slip may occur on the outer peripheral surfaces of the rollers 214, 215, and 217. Due to the slip phenomenon, the actual paper feed amount to the printing unit 202 by the timing roller 217 tends to be smaller than the assumed paper feed amount. In response to such a slip phenomenon, in the paper detection device 220 using a transmission type optical sensor, as a slip detection method, for example, counting the number of steps of the encoder of the drive motor after the paper leading edge blocks the transmission state of the optical sensor. The actual paper length obtained by calculating the total number of pulses until the rear edge of the paper passes through the optical sensor and the optical sensor enters the transmission state, and the previously known paper By comparing the length, it was estimated that slip occurred when (the actual measured paper length> the previously known paper length). In this case, it is practically impossible to detect the moment when the slip occurs, and in the subsequent paper transport process after the front end of the paper blocks the transmission state of the optical sensor (the actual measured paper length> preliminarily known). The slip can only be detected at the time when the sheet length is reached, that is, at least after the previously known sheet length. For this reason, at the timing when the slip is detected, there is no room for accelerating the paper conveyance speed, and there are many cases where the printing process can only be stopped as an error occurs.

(Object of invention)
The present invention makes it possible to reliably detect the slip amount of the print paper, the position of the print paper, the transport speed, the displacement amount, and the skew in the printing apparatus, and when the print paper is transported, An object of the present invention is to always allow printing at a predetermined image forming position on a printing paper even if rotation unevenness occurs in the plate cylinder.

  In order to solve the above-mentioned problems, a first aspect of the present invention provides a printing unit having a printing plate cylinder capable of adjusting the rotation speed and a pressing roller, a paper storage portion for storing a large number of printing papers, and the paper storage portion. A paper feeding / conveying device that separates the printing paper one by one from the paper feeding / conveying unit to the image forming unit of the printing unit, a paper detection device that detects the printing paper in the conveyance path of the paper feeding / conveying device, A control device for controlling the rotational speed of the printing plate cylinder or the transport speed of the paper feed transport device so that an image is formed in the normal print range of the print paper based on the position of the print paper detected by the paper detection device The paper detection device includes: a light emitting unit that irradiates laser light from a laser light source onto a surface of the printing paper that is being conveyed; and a paper surface within a predetermined detection region that is irradiated with the laser light. From anti A plurality of interferences periodically read by the image sensor, and a light receiving unit having an image sensor that reads an interference fringe pattern of the laser light due to unevenness on the surface of the paper and converts it into an electrical signal. The positions of the common portions of the stripe patterns are compared, and the displacement amount of the printing paper is input to the control device.

  According to the above configuration, the paper detection device employs laser light and detects the interference fringe pattern to detect the position and displacement of the paper being conveyed, so the sensor sensitivity is high and the contrast difference on the paper surface is low. It is possible to detect reliably even when there is not, and it is possible to reliably detect the position and amount of displacement regardless of the material of the paper to be detected in addition to glossy paper. Furthermore, since the laser beam has high coherency, even a minute unevenness can be reliably detected.

  In this way, the position, displacement amount, slip amount, and skew of the printing paper being conveyed can be detected easily and accurately, so that the image forming unit of the printing unit is not affected by slip or the like. The printing start position of the stencil sheet mounted on the surface of the printing plate cylinder can always coincide with the printing start position of the printing paper fed from the paper feeding / conveying device, so that the predetermined image forming position of the printing paper can be obtained. Image formation (printing) can be performed accurately.

  According to a second aspect of the present invention, in the printing apparatus according to the first aspect, an LED light source is provided instead of the laser light source of the light emitting unit, and a light / dark pattern is read by the image sensor instead of the interference fringe pattern. Has been.

  According to the above configuration, since the LED light is irradiated onto the paper and the positions of the common portions of the light and dark patterns of the reflected light are compared, the displacement amount can be accurately recognized even in a dark place.

  According to a third aspect of the present invention, in the printing apparatus according to the first or second aspect, the paper detection device is disposed at least at one place on a conveyance path at a predetermined distance from the image forming unit of the printing unit. Yes.

  According to the above configuration, the cost of parts can be saved, and since the position and displacement of the printing paper can be detected a predetermined time before the printing start by the printing unit, the printing start position of the stencil sheet with sufficient time, It is possible to match the printing start position of the printing paper.

  According to a fourth aspect of the present invention, in the printing apparatus according to any one of the first to third aspects, a plurality of the paper detection devices are disposed on the transport path, and a distance between the respective paper detection devices is determined by the printing. It is set below the minimum printable paper length that can be printed by the unit.

  According to the above configuration, even when printing paper of any length is printed, the displacement amount of the printing paper being conveyed can be detected without interruption over the entire length of the conveyance path from the paper storage unit to the printing unit. it can.

  According to a fifth aspect of the present invention, in the printing apparatus according to any one of the first to fourth aspects, the paper detection device is configured to read a displacement amount in a conveyance direction of the printing paper every predetermined cycle, and the control The apparatus is configured to recognize that the printing paper is in the slip state when the detected displacement amounts are relatively compared and a mutual difference of a predetermined value or more occurs.

  According to the above configuration, the slip of the paper can be recognized from any transport position with respect to the printing paper being transported, and the slip amount can be accurately calculated.

  According to a sixth aspect of the present invention, the control device is configured to accelerate the transport speed of the transport paper feeder in accordance with the detected slip amount.

  According to the above configuration, even if the printing paper slips in the conveyance path, the printing paper conveyance speed is adjusted so that the printing start position matches the stencil sheet mounted on the outer peripheral surface of the printing plate cylinder. Therefore, the image forming position of the printing paper does not shift.

  According to a seventh aspect of the present invention, in the printing apparatus according to the sixth aspect, the control device is configured to stop the printing plate cylinder when the detected slip amount is a predetermined value or more.

  According to the above configuration, it is possible to prevent printing failure when the slip amount is large.

  The invention according to claim 8 is the printing apparatus according to any one of claims 1 to 7, further comprising a rotation phase position detection device for detecting a rotation phase position of the printing plate cylinder, wherein the sheet detection device is at least The position of the printing paper fed to the printing plate cylinder from the conveyance terminal end of the paper feeding / conveying device is arranged at a position where it can be detected, and the control device conveys the paper feeding / conveying device detected by the paper detecting device. The printing start position of the printing paper and the printing plate are based on the position of the printing paper fed from the terminal portion to the printing plate cylinder and the rotational phase position of the printing plate cylinder detected by the rotational phase position detection device. When the printing start position of the stencil sheet on the surface of the cylinder is predicted to shift, the feeding timing from the conveyance end by the sheet feeding conveyance device so that the two printing start positions coincide at the start of printing It is configured to control.

  According to the above configuration, not only the slip phenomenon of the paper feeding / conveying apparatus but also the printing start position of the stencil sheet mounted on the surface of the printing plate cylinder is prompt even if the printing plate cylinder has uneven rotation. And the printing start position of the printing paper sent out from the paper feeding / conveying device can be matched, and image formation (printing) can be accurately performed at a predetermined image forming position on the printing paper.

  A ninth aspect of the present invention is the printing apparatus according to any one of the first to seventh aspects, further comprising a rotational phase position detecting device for detecting a rotational phase position of the printing plate cylinder, wherein the paper detecting device is at least The position of the printing paper separated and fed from the paper storage unit by the separation paper feeding unit of the paper feeding / conveying device is arranged at a position where it can be detected, and the control device is configured to perform the separation paper feeding detected by the paper detection device. Based on the position of the printing paper and the rotational phase position of the printing plate cylinder detected by the rotational phase position detection device, the printing start position of the printing paper and the printing start position of the stencil sheet on the surface of the printing plate cylinder In the case where it is predicted that a deviation will occur, the separation sheet feeding timing of the sheet feeding / conveying device is controlled by the separation sheet feeding unit so that the two printing start positions coincide at the start of printing.

  According to the above configuration, as in the case of claim 8, even when rotation irregularity of the printing plate cylinder occurs, the printing start position of the stencil sheet mounted on the surface of the printing plate cylinder The printing start position of the printing paper fed from the paper storage unit can be matched, and the image can be accurately formed (printed) at a predetermined image forming position on the printing paper. In particular, the timing at which the sheet is fed separately from the paper storage unit as in claim 9 is synchronized with the printing unit together with the timing at which the sheet is fed from the conveyance end of the sheet feeding and conveying device to the printing unit. By doing so, it is possible to accurately form (print) an image accurately at a predetermined image forming position on the printing paper.

  A tenth aspect of the present invention is the printing apparatus according to any one of the first to ninth aspects, wherein the control device displaces the displacement amount in the transport direction of the interference fringe pattern or the light and dark pattern in a direction orthogonal to the transport direction. The amount is calculated, and when the amount of displacement in the direction orthogonal to the transport direction is equal to or greater than a predetermined value, it is recognized that the transport paper is skewed.

  According to the above configuration, the skew of the printing paper can be always easily detected.

  1 to 15 show an embodiment of a stencil printing apparatus according to the present invention, which will be described below with reference to the drawings.

[Overall structure of stencil printing machine]
FIG. 1 is a schematic side view of a stencil printing apparatus. In an upper half of the printing apparatus main body 1, a printing unit 2, a plate making apparatus 3, a plate discharging apparatus 4, a paper discharge apparatus 5, and an operation panel 6 are provided. The control device 50 and the like are arranged, and in the lower half of the printing apparatus main body 1, the paper storage unit 7 is arranged in two upper and lower stages. A manual paper insertion table 10 is detachably provided on one side of the printing apparatus main body 1, and a paper tray 11 for storing printed paper P after printing is provided on the other side. Yes. A sheet feeding / conveying device 20 extending from each sheet storage unit 7 and the sheet insertion table 10 to the image forming unit 2a of the printing unit 2 is arranged from the lower half to the upper half in the printing apparatus main body 1. Yes.

  The printing unit 2 includes a printing plate cylinder 16 in which the ink supply roller 15 is inscribed and rotationally driven in the direction of the arrow R, and a vertically movable pressing roller 17 opposed to the printing plate cylinder 16 so as to be press-contactable from below. The image forming unit 2 a is configured between the pressing roller 17 and the lower end of the printing plate cylinder 16. A large number of ink passage holes are formed in the peripheral wall of the printing plate cylinder 16, and the stencil sheet N made by the plate making apparatus 3 is mounted. The front end of the stencil sheet N in the rotation direction is a sheet clamp. 18 is fixed. The printing plate cylinder 16 is linked to a drive motor 21 via a power transmission mechanism 22, and the drive motor 21 is configured to be capable of adjusting the rotation speed.

  The plate discharging device 4 removes the used stencil sheet N mounted on the printing plate cylinder 16 and draws it into the plate discharging device 4 with a drawing roller and winds it up as a plate discharging roll.

  Each paper storage unit 7 includes a paper feed tray 25 on which a large number of printing papers P are stacked.

  The paper discharge device 5 includes a paper discharge belt and a suction fan. The print paper P on the paper discharge belt is sucked by the suction fan and discharged onto the paper receiving tray 11.

  The plate making apparatus 3 includes a master roll 30 for plate making, a thermal head 31 and the like. Plate making paper (stencil base paper) N is made by the thermal head 31 (perforated) to form a printing plate cylinder 16 of the printing unit 2. It comes to wear.

[Paper feeding device]
FIG. 2 is an enlarged side view of the sheet feeding / conveying device 20. The sheet feeding / conveying device 20 includes a sheet feeding roller (separated sheet feeding unit) 51 disposed in each sheet storage unit 7 and insertion table 10, and printing. A pair of feed rollers 52 disposed at the conveyance end portion in the vicinity of the image forming unit 2 a of the unit 2, and a guide plate 53 constituting a paper conveyance path 55 from each paper feed roller 51 to the feed roller 52; , And a plurality of pairs of transport rollers 54 arranged at intervals on the transport path 55.

  Each of the paper feed rollers 51 is in contact with the uppermost printing paper P of each paper storage unit 7 and insertion base 10 and is opposed to the scooping plate 57, and is respectively clutched to a drive motor 61 that is intermittently driven at a predetermined timing. The uppermost printing paper P is separated from the lower paper and is fed one by one into the transport path 55 by operating at a predetermined timing.

  The transport rollers 54 rotate at the same speed at the same time through an interlocking mechanism including a chain and a sprocket, and the interlocking mechanism is interlocked and connected to a common drive motor 64 capable of adjusting the rotational speed. As the interlocking mechanism and driving mechanism of each conveyance roller 54, in addition to the above-described configuration, for example, one or a plurality of conveyance rollers 54 from the side close to the feeding roller 52 is replaced with another conveyance roller 54. Can be configured to be driven independently by another interlocking mechanism and driving mechanism. With such a configuration, it is possible to perform fine speed correction at each part of the transport roller 54 that can be independently driven, and no significant speed correction between the feeding roller 52 and the printing plate cylinder 16 is required.

  The feeding roller 52 disposed at the conveyance end portion of the conveyance path 55 is linked to a drive motor 62 that can adjust the rotation speed. The feeding roller 52 can be connected to an interlocking connection mechanism common to the transport roller 54.

[Arrangement of paper detection device and rotational phase device detection device]
On the conveyance path 55, three first sheet detection devices 66 disposed in the vicinity of the sheet feeding downstream side of each sheet feeding roller 51, and one second sheet disposed at the conveyance end portion. A detection device 67 and a plurality of third paper detection devices 68 arranged in the vicinity of the conveyance downstream side of each conveyance roller 54 are arranged. The first paper detection device 66 detects the state of the print paper P immediately after being fed by the paper feed roller 51, and the second paper detection device 67 is sent from the feed roller 52 to the image forming unit 2 a of the printing unit 2. The state of the printing paper P immediately after the feeding of the printing paper P is detected, and the second paper detection device 68 detects the state of the printing paper P in the middle of conveyance.

  FIG. 3 is a block diagram showing a control system. Each of the drive motors 61 for the paper feed rollers 51, the drive motor 62 for the feed rollers 52, and the drive motor 64 for the transport rollers 54 has predetermined reference rotation angles. Rotation phase position detectors (encoders) 71, 72, 74 for detecting the rotation amount with respect to the rotation angle, that is, the rotation phase position are provided. Further, the printing plate cylinder 16 is provided with a rotation phase position detecting device 70 for directly detecting the rotation phase position of the printing plate cylinder 16, but it can also be provided in the drive motor 21 for the plate cylinder. It is.

[Control device]
The control device 50 includes a CPU or a microprocessor 76 and a RAM 77 and a ROM 78 as storage devices. The input unit of the control device 50 includes first, second, and third paper detection devices 66, 67, and 68 disposed in the paper feed conveyance path 55, and rotational phase position detection devices 70, 71, 72, 74 is electrically connected. The position information of the printing paper P immediately after the separation paper feeding is input from the first paper detection device 66 arranged near the paper feed roller 51, and the second paper detection device arranged near the feed roller 52. The position information of the printing paper P immediately after feeding is input from 67, and the position information of the printing paper P in the middle of conveyance is input from the third paper detection device 68 arranged in the middle of the conveyance path. Further, the rotation phase position detection device 71 of the drive motor 61 of the paper feed roller 51, the rotation phase position detection device 72 of the drive motor 62 of the feed roller 52, and the rotation phase position detection device 74 of the drive motor 64 of the transport roller 54 are used. The information of the rotational phase position from the reference rotational position of each drive motor 61, 62, 64 is input. In addition, information on the rotational phase position from the reference rotational position of the printing plate cylinder 16 is input from the rotational phase position detection device 70 of the printing plate cylinder 16.

  A drive motor 21 for the printing plate cylinder 16, a drive motor 61 for the paper feed roller 51, a drive motor 62 for the feed roller 52, and a drive motor 64 for the transport roller 54 are electrically connected to the output unit of the control device 50. The rotation speed (including start / stop) is controlled by a command signal from the control device 50.

[Details of paper detection device]
FIG. 6 is a perspective view showing a specific structure of the third paper detection device 68 arranged in the middle of the transport path 55. The paper detection device 68 includes a light emitting unit 44 incorporating a laser light source (laser oscillation unit) 45. And a light receiving unit 47 containing an image sensor 48, and the image sensor 48 is electrically connected to the control device 50. If necessary, a lens 46 is disposed in front of the laser light source 45 in the light emitting unit 44, and a lens 49 is also disposed below the image sensor 48 in the light receiving unit 47.

  The light emitting unit 44 is installed at a predetermined distance (for example, 7 mm to 10 mm) and a predetermined angle from the paper P in the transport path, and irradiates the laser light from the laser light source 45 onto the paper P through the lens 46. It is like that. The irradiation area S and the third paper detection device 68 shown on the paper P are exaggerated with dimensions larger than the actual size in order to facilitate understanding thereof.

  The light receiving unit 47 is arranged at a predetermined distance (for example, 5 mm to 10 mm) from the paper P in the transport path. In particular, the image sensor 48 is arranged to be substantially parallel to the paper. The laser beam reflected from the surface of P is received by the image sensor 48 through the lens 49, and for example, an interference fringe pattern (speckle pattern) of the laser beam as shown in the upper part of FIG. 7 is formed on the image sensor. Then, the formed interference fringe pattern is read, converted into an electric signal, and input to the control device 50. The reading area B of the paper P by the image sensor 48 is shown in a substantially square shape in the irradiation area S. The reason why the interference fringes are generated will be explained in detail. When the laser light hits the paper surface (rough surface), the slight unevenness on the paper surface can cause a slight difference in the distance from the paper surface, which reflects from the paper. This is because a phase difference occurs in the diffused light. The interference fringe pattern is determined by the state of the paper surface. If the paper is stationary, the interference fringe pattern is also stationary. If the paper is moved, the interference fringe pattern is also moved at the same speed as the paper. The irregularities on the surface of the paper that cause the interference fringe pattern are formed not only by the roughness of the surface, but also by a variety of paper fiber patterns or unevenness.

  The image sensor 48 is an array of a large number of image sensor pixels that detect an interference fringe pattern of laser light. For example, 30 × 30 = 900 pixels (1 pixel = 1/800 inch) is formed in a square shape. The interference fringe pattern in the reading area B can be read (photographed).

  Further, the image sensor 48 is set to periodically read the interference fringe pattern in the reading area B on the paper P being conveyed, and the detection cycle is set to 130 μsec, for example. Note that this detection cycle can be changed as appropriate according to the type of paper, and can be changed, for example, to a maximum of about 81 μsec. Also, 1 pixel = 1/800, which is a reference for resolution, can be appropriately changed.

  Based on the position of the paper P moving in the transport path, the displacement amount (movement amount), the moving speed, the slip, the slip amount, the skew, the skew angle, and the paper length are detected by the third paper detection device 68. Can be detected. Of course, the presence or absence of the paper P can also be detected.

  The structure of the first and second paper detection devices 66 and 67 shown in FIGS. 2 and 3 is basically the same as that of the third paper detection device 68 shown in FIG. 6, and detailed description thereof will be omitted.

[Details of rotational phase position detector]
4 and 5 show details of the third paper detection device 68, the conveyance roller 54, the drive motor 64 for the conveyance roller 54, and the rotational phase position detection device 74 arranged in the middle of the conveyance path. The rotational phase position detector 74 provided in the drive motor 64 includes, for example, a rotary plate 36 that rotates integrally with the output shaft 35 of the drive motor 64, and a detection unit 37 that faces the rotary plate 36 from both sides in the axial direction. A plurality of slits 36 a are formed in the rotating disk 36 at equal intervals in the circumferential direction, and the slits 36 a are detected by a detection unit 37. The detection unit 37 is electrically connected to the control device 50, and the detected rotation amount (rotation angle or rotation phase position) of the drive motor 64 is input to the control device 50. The rotational phase position detectors 71 and 72 provided in the other drive motors 61 and 62 shown in FIGS. 2 and 3 and the rotational phase position detector 70 provided in the printing plate cylinder 16 are also shown in FIGS. 5 has basically the same structure as the rotational phase position detector 74 shown in FIG.

  FIG. 15 is a development view of the outer peripheral surface of the printing plate cylinder 16 and the printing paper P in a front-to-back relationship during normal printing. Are provided with an opening 40 (indicated by oblique lines) in which the ink permeation holes are distributed. The opening 40 is in a substantially maximum printing range, and the front end 40a in the rotation direction R of the opening 40 is a printing plate. The stencil sheet N is mounted so as to cover the first opening 40, which is the printing start position of the cylinder 16. The front end portion of the stencil sheet N is held by the paper clamp 18. On the other hand, the front end (print start position) 43a of the print range (diagonal line) 43 of the print paper P is separated from the front end Pa of the print paper P by a predetermined distance (margin) Z, and printing of the print paper P starts when printing starts. When the position 43a matches the printing start position (printing start position of the stencil sheet N) 40a of the printing plate cylinder 16, accurate image formation without deviation is performed.

[Detection of moving amount and moving speed of printing paper by paper detection device]
FIG. 6 shows a method of detecting the movement amount and movement speed of the printing paper P in the conveyance direction F by the third paper detection device 68 provided in the middle of the conveyance path 55. The upper and lower stages are image sensors. 48 shows a state before and after one reading cycle. For example, if the position of the paper P shown in the upper row is the nth reading position by the paper detection device 68, the position of the paper P shown in the lower row indicates the (n + 1) th reading position one cycle after the position shown in the upper row. ing.

  In FIG. 6, the interference fringe patterns of the reading area B of the sheet P at the position shown in the upper stage and the reading area B of the sheet P at the position shown in the lower stage are read by the image sensor 48, and each interference fringe pattern is converted into an electric signal. This is converted and input to the control device 50, the position of each paper P is detected, the displacement of the common part of both interference fringe patterns is calculated, and the movement amount and speed of the paper P are detected.

  FIG. 7 shows an example of an interference fringe pattern imaged on the image sensor 48 in an easy-to-understand manner. The upper part of FIG. 7 corresponds to the upper part of FIG. 6, and the reading at the nth reading position is performed. The interference fringe pattern of the area B is shown. The lower part of FIG. 7 corresponds to the lower part of FIG. 6 and shows the interference fringe pattern of the reading area B at the (n + 1) th reading position after one cycle. The common part of the interference fringe pattern is temporarily indicated by a triangle T (1,2). As shown in the lower part, the position of the common portion (shaded triangle) T1 at the n-th reading and the position of the common portion T2 (black triangle) at the (n + 1) -th reading are the same reading area. The amount of movement A1 (= A) in the conveyance direction F of the paper P in a predetermined cycle can be obtained from the difference D1 in the conveyance direction of T1 and T2 by comparing on the two-dimensional coordinates in B. Further, the transport speed of the printing paper P can be obtained from the movement amount A1 (D1) and a predetermined period (time).

  If the displacement amount D1 (movement amount A1) obtained in this way is the same as the displacement amount (movement amount) corresponding to the preset conveyance speed, the movement amount and conveyance speed of the printing paper P in the conveyance direction F are , It can be recognized that the normal value set in advance is maintained.

[Slip detection by paper detector]
8 and 9 show a case where the printing paper P is completely stopped due to slip, and FIGS. 10 and 11 show a case where the printing paper P is moving in a slip state. 10 and 10 show the same relationship as the relationship between the upper and lower steps in FIG. 6, and the upper and lower steps in FIGS. 9 and 11 show the same relationship as the relationship between the upper and lower steps in FIG. ing.

  In FIG. 8, when the printing paper P is completely stopped due to the slip, the printing paper P does not advance at all from the n-th reading at the upper stage to the n + 1-th reading at the lower stage. It has stopped.

  Therefore, as shown in FIG. 9, the common portions T1 and T2 are not displaced between the common portion T1 at the time of the upper nth reading and the common portion T2 at the time of the lower (n + 1) th reading. The displacement amounts of the common portions T1 and T2 are zero. When such a displacement amount 0 is detected, it is recognized that the printing paper P is completely stopped due to slipping, and for example, the printing apparatus is stopped and maintenance of the conveying means is performed.

  On the other hand, in FIG. 10, when the printing paper P is moving in a slipping state, the printing paper P is temporarily changed between the upper n-th reading time and the lower n + 1-th reading time. It moves with a movement amount A2 smaller than the normal movement amount A1.

  Accordingly, as shown in FIG. 11, a displacement amount D2 between the common portion T1 at the time of the n-th reading in the upper stage and the common portion T2 at the time of the (n + 1) -th reading is obtained, and this is calculated as a normal displacement set in advance. By comparing with the amount D1, the slip amount in a predetermined cycle can be obtained. In this case, the rotational speed of the drive motor 64 of the conveying roller 54 is increased by a command signal from the control device 50 in FIG. 3 according to the obtained slip amount, and the printing start position of the printing paper P and the printing plate cylinder 16 are increased. Control is performed so that the printing start positions of the stencil sheets N on the surface of the sheet are matched. In particular, when the slip amount is large at a predetermined value position, the drive motors 61, 62, 64 of the paper feeding / conveying device 20 and the drive motor 21 of the printing plate cylinder 16 are stopped.

The slip of the feeding roller 52 in FIGS. 2 and 3 is also detected and controlled in the same manner as the conveying roller 54.
[Detect paper length]
FIG. 12 shows a paper length detection method. The upper part shows a state at the start of length detection, and the lower part shows a state at the end of length detection. At the time of starting the upper length detection, the front end of the printing paper P is detected by the image sensor 48, and then the reading area B (B ′) is read every cycle as shown by the virtual line in the lower row. The amount of movement of the paper P for each period is detected by obtaining the amount of displacement of the common part. Then, when the trailing edge of the paper P is detected, the length L1 in the transport direction F of the paper P is obtained by integrating the displacement amount of the common part detected for each cycle.

  In this length detection method, even if the paper P slips, the amount of displacement of the common portion for each period changes according to the slip amount. Therefore, even if slip occurs, the paper length L1 is accurately obtained. be able to.

[Detect paper skew]
FIGS. 13 and 14 show a skew detection method for paper, and the upper and lower parts of FIG. 13 show the same relationship as the upper and lower parts of FIG. 6, and the upper and lower parts of FIG. FIG. 7 shows the same relationship as that shown in FIG.

  That is, in FIG. 13, the left and right applied pressures or frictional forces of the rollers or the like are changed during one cycle or several cycles from the n-th reading position in the upper stage to the (n + 1) -th reading position shown in the lower stage. The paper P may be skewed due to a difference or the like.

  In the lower part of FIG. 14, when the paper P is skewed, the common portion T1 is displaced to T2 as the paper P is skewed. Specifically, the common portion T1 is displaced by a displacement amount D2 in the paper conveyance direction F, and is also displaced by a displacement amount E2 in a direction perpendicular to the conveyance direction F. The displacement direction and displacement amount of the paper are detected from the displacement amount D2 in the transport direction F and the displacement amount E2 in the direction perpendicular to the transport direction F. That is, the skew state itself of the sheet can be detected, and the skew angle θ and the displacement amount in the skew direction can also be detected.

[Basic operation of stencil printing machine]
(1) An example of the basic operation of the stencil printing apparatus will be briefly described. In FIG. 1, the printing paper P is selected from the paper storage unit 7 and the manual paper insertion table 10 by a paper selection key on the operation panel 6. For example, the printing paper P in the lower paper storage unit 7 is selected.

(2) When the print start key on the operation panel 6 is operated, the printing plate cylinder 16 is maintained in the stopped state in FIG. 2. First, the paper feed roller 51 and the transport roller arranged in the selected paper storage unit 7. 54 is rotated by the drive motors 61 and 64. The printing paper P is separated from the paper storage unit 7 one by one by the rotation of the paper feed roller 51, fed into the transport path 55, transported through the transport path 55 by the transport roller 54, and then a little later. Then, the feeding roller 52 starts to rotate. Due to this delay in starting rotation, the leading edge of the printing paper P is bent, and the entire front edge of the printing paper P abuts against the tangent to the feeding roller 52 so that the printing paper P is in contact with the printing plate cylinder 16. It will be transported straight.

  When the feeding roller 52 rotates, the printing paper P is sent to the printing unit 2 side, and when the front end Pa of the printing paper P reaches just below the printing plate cylinder 16, the pressing roller 17 moves to the printing plate cylinder 16 side. Then, the printing paper P is pressed against the surface of the printing plate cylinder 16 to start the pressing action. At this time, as shown in FIG. 15, after the paper clamp 18 passes just below the printing plate cylinder 16 (position facing the pressing roller 17), the pressing roller 17 moves to the printing plate cylinder 16 side. Is started (position H0). The pressing roller 17 is in contact with the leading end portion Pa of the printing paper P before the front end 40 a of the opening portion 40 of the printing plate cylinder 16, and the printing paper P is applied to the stencil paper N mounted on the printing plate cylinder 16. Energize (position H1). The printing paper P is conveyed while being sandwiched between the printing plate cylinder 16 and the pressing roller 17, and when the pressing roller 17 faces the front end 40a of the opening 40 of the printing plate cylinder 16 (position H2), Printing on the printing paper P is possible. Before the end of printing, the pressing roller 17 starts to separate from the printing plate cylinder 16 (position H3) before the rear end 40b of the opening 40 passes just below the printing plate cylinder 16. As a result, the press state in which the printing paper P is pressed against the printing plate cylinder 16 is released, and printing on the printing paper P becomes impossible.

  Subsequent to the printing of the first printing paper P, the printing paper in the paper storage unit 7 is sequentially separated and fed from the top, conveyed, and continuously fed to the image forming unit of the printing unit 2.

[Basic control]
Basically, slipping of the printing paper P, uneven rotation of the printing plate cylinder 16, deviation of the feeding timing of the printing paper P to the printing plate cylinder 16, deviation of feeding timing, etc. occur during the printing operation. However, the printing start position 40a of the stencil sheet N mounted on the printing plate cylinder 16 and the printing start position 43a of the printing paper P fed from the feeding roller 52 to the image forming unit 2a are always in a state of being consistent. In order to be able to perform printing, the position, displacement amount, conveyance speed, etc. of the printing paper detected by the paper detection devices 66, 67, 68, and the drive motor 61 detected by the rotational phase difference detection devices 70, 71, 72, 74 are provided. 62, 64 and the rotational phase difference of the printing plate cylinder 16, the rotational speed of the printing plate cylinder 16, the rotational speed and operation timing of the paper feed roller 51, the rotational speed of the conveying roller 54, and the feeding roller 52 Controlling the rotation speed and operation timing. Hereinafter, main individual control will be briefly described.

(1) Control at the time of slip detection During a printing operation, when slip occurs in at least one of the paper feed roller 51, the transport roller 54, and the feed roller 52, for example, when slip occurs in the transport roller 54 10 and FIG. 11, the common portion T1 for the upper nth reading calculated based on the paper detection position by the third paper detection device 68 and the common for the n + 1th reading are calculated. By comparing the displacement amount D2 with the portion T2 and a preset normal displacement amount D1, a slip amount in a predetermined cycle is obtained, and a predetermined signal is received by a command signal from the control device 50 according to the obtained slip amount. The rotational speed of the drive motor 64 of the transport roller 54 in FIGS. 2 and 3 is increased so that the printing paper is transported at the transport speed of FIG. Thus, finally, the printing start position 43a of the printing paper P in FIG. 15 and the printing start position 40a of the stencil sheet N on the surface of the printing plate cylinder 16 are controlled so as not to deviate.

(2) Control at the time of occurrence of rotation unevenness of printing plate cylinder In FIG. 2, the position of the printing paper P fed from the feeding roller 52 to the printing plate cylinder 16 and the displacement amount based on this position (detected by the paper detection device 67) ) And the rotational phase position relative to the reference phase position of the printing plate cylinder 16 detected by the rotational phase position detection device 70 of the printing plate cylinder 16 in FIG. When the print start position 43a is compared with the print start position 40a at the front end of the opening portion of the printing plate cylinder 16, and it is expected that the two print start positions (40a, 43a) are displaced, The rotational speed of the drive motor 62 of the feed roller 52 is increased or decreased so that both print start positions (40a, 43a) match. Alternatively, the drive motor 21 of the printing plate cylinder 16 is accelerated or decelerated in place of the rotational speed control of the feeding roller 52 or together with the rotational speed control of the feeding roller 52.

  For example, when the printing start position 43a of the printing paper P is shifted from the printing start position 40a of the printing plate cylinder 16 to the rear in the feeding direction (conveyance direction F) due to uneven rotation of the printing plate cylinder 16 or the like. If predicted, the speed of the feeding roller 52 is increased or the rotational speed of the drive motor 21 of the printing plate cylinder 16 is decreased to start printing (position H2) as shown in FIG. The printing start position 43a of the printing paper P is matched with the printing start position 40a of the printing plate cylinder 16.

  On the other hand, due to rotation unevenness of the printing plate cylinder 16 or the like, the printing start position 43a of the printing paper P is shifted from the printing start position 40a of the printing plate cylinder 16 to the front in the feeding direction (conveyance direction F) at the start of printing. If the speed of the feeding roller 52 is reduced or the rotational speed of the printing plate cylinder 16 is increased, at the start of printing (position H2) as shown in FIG. The printing start position 43a of the printing paper P is matched with the printing start position 40a of the printing plate cylinder 16.

(3) Control of paper feed roller 51 Along with the rotational speed control of the feed roller 52 or the printing plate cylinder 16, the separation paper feed timing of the paper feed roller 51 matches the printing timing of the printing plate cylinder 16. To control. For example, if the separation paper feed timing of the paper feed roller 51 is too fast relative to the printing timing of the printing plate cylinder 16, the separation paper feed timing by the paper feed roller 51 is delayed, and conversely the separation paper feed timing is too fast. In this case, control is performed so as to delay the separation paper feed timing of the paper feed roller 51.

[Other effects in the present embodiment]
(1) The paper detection devices 66, 67, and 68 used in the present embodiment are configured to irradiate the surface of the printing paper with laser light and read the interference fringe pattern of the laser light due to the unevenness of the paper surface with the image sensor 48. Since the position and displacement amount of the printing paper are detected from the interference fringe pattern, the paper position and displacement amount (movement amount) can be accurately determined from any conveyance position with respect to the printing paper P being conveyed. It can be detected and calculated. In addition, it has high sensor sensitivity and can reliably detect even when there is no contrast difference on the surface of the paper that cannot be detected by LED light or the like, and it can reliably detect the amount of displacement regardless of the paper material to be detected in addition to glossy paper. it can. In addition, since the laser beam has strong coherency, it is possible to reliably detect even a minute unevenness change.

(2) The intervals in the conveyance direction of the paper feed roller 51, the conveyance roller 54, and the feeding roller 52 are set to be smaller than the length of the minimum length of the printing paper P that can be printed by the printing plate cylinder 16. Therefore, even when printing paper P of any length is printed, the displacement amount of the printing paper P being conveyed is detected without interruption over the entire length of the conveyance path 55 from the paper storage unit to the printing unit 2. Can do.

“Another embodiment of the present invention”
(1) In the present invention, in FIG. 1, the portion having the paper storage unit 7 is configured to be separable from the main components of the printing apparatus including the printing unit 2, the plate making apparatus 3, the plate discharging apparatus 4, and the like. In this case, before connecting the paper feeding device having the paper storage unit 7 to the printing device, for example, a sheet of paper is supplied from the paper insertion table 10 for manual feeding, Based on the printing result of the printing paper P, the printing start position of the printing paper P sent to the image forming unit 2a is compared with the printing start position of the printing plate cylinder 16, and there is a deviation between the two positions. Controls the timing of the feeding roller 52 and / or the printing timing of the printing plate cylinder 16 so that the timing of feeding by the feeding roller 52 matches the printing timing of the printing plate cylinder 16. In this case, the one sheet of printing paper can be conveyed at the maximum speed that can be exhibited by the paper feeding and conveying apparatus, and printing can be started the fastest.

(2) In each of the above embodiments, the laser light source is provided as the light source 45 of the paper detection devices 66, 67, 68 in FIGS. 5 and 6, but the paper detection devices 66, 67, 68 may be arranged. Except for the difference in the light source, it is the same as in each of the above-described embodiments, so detailed description of the structure, detection method and control method is omitted, but in short, the LED light source irradiates the surface of the paper being conveyed from the LED light source The LED light reflected from the paper surface within a certain detection area irradiated with the LED light is received by the image sensor, and the light / dark pattern of the LED light due to the light and darkness of the paper surface is read and converted into an electrical signal. The use of an LED light source is more cost effective than the use of a laser light source.

  The present invention is not limited to stencil printing apparatuses, and can be applied to various printing apparatuses.

It is the schematic of embodiment of the stencil printing apparatus concerning this invention. FIG. 2 is an enlarged side view of a sheet feeding / conveying device of the stencil printing apparatus of FIG. 1. It is a block diagram which shows the control system of the stencil printing apparatus of FIG. FIG. 2 is a simplified perspective view of a feed roller and its driving device of the stencil printing machine of FIG. 1. FIG. 2 is a schematic side view showing a feeding roller, a driving device, and a paper detection device of the stencil printing machine of FIG. 1. It is explanatory drawing which shows the detection method of the position of a printing paper, a movement amount, and a movement speed. It is a figure which shows the change of the interference fringe pattern by the image sensor corresponding to FIG. It is explanatory drawing which shows the detection method when printing paper stops by slip. It is a figure which shows the change of the interference fringe pattern by the image sensor corresponding to FIG. It is explanatory drawing which shows the detection method in case the printing paper is moving in the slip state. It is a figure which shows the change of the interference fringe pattern by the image sensor corresponding to FIG. It is explanatory drawing which shows the detection method of the length of the conveyance direction of a printing paper. It is explanatory drawing which shows the detection method of skew of a printing paper. It is a figure which shows the change of the light-and-dark pattern by the image sensor corresponding to FIG. It is a figure which shows the developed printing cylinder and printing paper. It is the schematic of the conventional printing apparatus. FIG. 17 is a perspective view of the light-blocking photosensor type paper detection device of FIG. 16.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printing apparatus main body 2 Printing unit 7 Paper storage part 16 Printing plate cylinder 17 Pressing roller 21 Driving motor 44 for printing plate cylinder Light emitting part 45 Laser light source 47 Light receiving part 50 Control device 51 Paper feed roller (separation paper feeding part)
52 Feed roller 54 Transport roller 61 Drive motor 62 for feed roller Drive motor 64 for feed roller Drive motor 66, 67, 68 for transport roller Paper detection device 70, 71, 72, 74 Rotation phase position detection device

Claims (10)

A printing unit having a printing cylinder and a pressure roller capable of adjusting the rotation speed, a paper storage unit for storing a large number of printing papers, and separating the printing papers one by one from the paper storage unit by a separation paper feeding unit Printing based on the paper feed transport device transported to the image forming unit of the printing unit, the paper detection device for detecting the print paper in the transport path of the paper feed transport device, and the position of the print paper detected by the paper detection device A control device that controls a rotation speed of the printing plate cylinder or a conveyance speed of a paper feed conveyance device so that an image is formed in a regular printing range of paper,
The paper detection device receives a laser beam reflected from a paper surface in a predetermined detection area irradiated with the laser light, and a light emitting unit that irradiates the surface of the printing paper being conveyed with a laser light from a laser light source. A light receiving unit having an image sensor that reads an interference fringe pattern of laser light due to unevenness on the paper surface and converts it into an electrical signal, and a position of a common portion of the plurality of interference fringe patterns periodically read by the image sensor The printing apparatus is configured to input the displacement amount of the printing paper to the control device. The printing apparatus according to claim 1.
The paper detection device includes an LED light source instead of a laser light source of the light emitting unit, and is configured to read a light / dark pattern instead of the interference fringe pattern by the image sensor. The printing apparatus according to claim 1 or 2,
The printing apparatus according to claim 1, wherein the paper detection device is disposed at least at one place on a conveyance path at a predetermined distance from an image forming unit of the printing unit. In the printing apparatus in any one of Claims 1-3,
A plurality of the paper detection devices are arranged on the transport path, and a distance between the paper detection devices is set to be equal to or less than a minimum print paper length that can be printed by the printing unit. . In the printing apparatus in any one of Claims 1-4,
The paper detection device is configured to read a displacement amount in a conveyance direction of the printing paper every predetermined cycle,
The control device is configured to relatively compare the detected displacement amounts and recognize that the printing paper is in a slip state when a mutual difference of a predetermined value or more occurs. Printing device. The printing apparatus according to claim 5.
The printing apparatus is configured to accelerate the conveyance speed of the paper feeding / conveying device in accordance with the detected slip amount. The printing apparatus according to claim 6.
The control device is configured to stop the printing plate cylinder when the detected slip amount is a predetermined value or more. In the printing apparatus in any one of Claims 1-7,
A rotational phase position detecting device for detecting a rotational phase position of the printing plate cylinder;
The paper detection device is disposed at a position where at least the position of the printing paper fed into the printing plate cylinder from the conveyance terminal portion of the paper feeding conveyance device can be detected,
The control device includes: a position of a printing sheet fed from a conveyance terminal portion of the sheet feeding conveyance device detected by the sheet detection device to a printing plate cylinder; and a printing plate cylinder detected by the rotational phase position detection device. If the printing start position of the printing paper and the printing start position of the stencil sheet on the surface of the printing plate cylinder are predicted to be shifted based on the rotational phase position of A printing apparatus configured to control a feeding timing from a conveyance end portion by a paper feed conveyance device so as to match. In the printing apparatus in any one of Claims 1-7,
A rotational phase position detecting device for detecting a rotational phase position of the printing plate cylinder;
The paper detection device is arranged at a position where at least the position of the printing paper separated and fed from the paper storage unit by the separation paper feeding unit of the paper feeding and conveying device can be detected,
The control device starts printing of the printing paper based on the position of the printing paper at the time of separation feeding detected by the paper detection device and the rotational phase position of the printing plate cylinder detected by the rotational phase position detection device. When the printing start position of the stencil sheet on the surface of the printing plate cylinder is predicted to be shifted, the separation feeding of the paper feeding / conveying device is performed so that the printing start positions coincide with each other at the start of printing. The printing apparatus is configured to control the separation and feeding timing by a unit. In the printing apparatus in any one of Claims 1-9,
The control device calculates a displacement amount in the conveyance direction of the interference fringe pattern or the light and dark pattern and a displacement amount in a direction orthogonal to the conveyance direction, and when the displacement amount in the direction orthogonal to the conveyance direction is a predetermined value or more, the conveyance sheet Is configured to recognize that the printer is skewed.

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