JP4568509B2 - Stencil type duplex printing device - Google Patents

Description

  The present invention relates to a stencil type double-sided printing apparatus that prevents printing paper from being soiled by undried ink in a printing process.

In printing by a stencil printer, the paper is fed into a printing section between a plate cylinder on which a stencil sheet is mounted and a printing pressure roller that can come in contact with and separate from the plate cylinder. Thus, the contacting / separating operation of the printing roller with respect to the plate cylinder is controlled so that the printing roller contacts the plate cylinder with a predetermined printing pressure. If the printing roller is pressed directly against the plate cylinder when no paper is present in the printing section, the ink from the stencil sheet will be transferred to the printing roller. A technique for stopping the printing operation of the printing roller on the plate cylinder when the sheet is not fed is known in a stencil printing apparatus that performs two-color printing with two plate cylinders described in Patent Document 1. .
Even in a stencil type duplex printing apparatus that performs printing on both front and back sides of a sheet, printing is performed on the front side of the sheet fed from the paper feed unit and on the back side of the sheet printed in the front side printing process. In both the backside printing step and the backside printing step, the contact / separation operation of the printing roller with respect to the plate cylinder is controlled.
In the back surface printing process, the printing pressure roller contacts the front surface of the paper so as to press the back surface of the paper already printed on the front surface against the plate cylinder. Since the ink of the printed image formed on the front surface of the paper is not immediately dried, the printing pressure roller comes into contact with the undried ink of the printed image in the back surface printing process. In order to minimize the ink stain on the peripheral surface of the printing roller due to the contact with the undried ink, a countermeasure for preventing the stain is formed by forming the peripheral surface of the printing roller with a fine uneven surface.

  FIG. 9 is an enlarged partial cross-sectional view of a printing roller in which fine irregularities are formed on the circumferential surface with glass beads, and undried ink 4 is attached to the glass beads 3 fixed to the circumferential surface of the printing roller 1 with an adhesive 2. Shows a state where is transferred from the printed image. The transfer ink 4 from the printed image adheres only to the apex area of the concave and convex portions of the glass beads, and even if the ink is transferred in fine dots on the paper to be pressed next, it does not become a noticeable stain. Patent Document 2 describes a pressing rotation member as a printing pressure roller having minute irregularities on an outer peripheral surface in a stencil printing apparatus.

Japanese Patent Laid-Open No. 11-151852 JP2002-219849

  In a stencil type duplex printing apparatus that performs double-sided printing by a front surface printing process that performs printing on the front surface of paper fed from a paper feeding unit and a back surface printing process that performs printing on the back surface of the paper printed in the front surface printing process The use of a printing roller having a fine irregular surface on the peripheral surface is effective as a measure for preventing contamination by the printing roller in the back surface printing process. However, due to a paper conveyance trouble such as a paper conveyance jam, when the pressure roller is pressed directly against the plate cylinder in a state where the paper is not present in the printing unit between the plate cylinder and the printing pressure roller in the back surface printing process, As shown in FIG. 10, there is a problem that a large amount of ink from the stencil sheet is transferred to the fine uneven surface of the printing roller, and the fine uneven surface printing roller is not useful for preventing contamination.

  When ink is transferred and adhered to the printing pressure roller, conventionally, the adhered ink is removed from the peripheral surface of the printing pressure roller by a cleaning device using a cleaning roller. In this cleaning method, however, the cleaning performance due to contamination of the cleaning roller is removed. If the cleaning is continued in such a state, the ink will transfer from the cleaning roller to the printing roller, causing a problem with the cleaning endurance performance. Had to be replaced.

  With a normal cleaning method using felt or cloth, it is difficult to remove even the ink that has entered the concave portions of the fine irregularities made of the beads of the printing roller, as shown in FIG. Further, even with a cleaning method using a fine bristle brush, only an experimental result was obtained in which the entire fine uneven surface of the printing roller was painted with ink.

  In order to improve the cleaning performance of the printing roller, for example, as disclosed in Patent Document 2, in a cleaning method using a liquid such as silicone oil having a specific viscosity, a liquid application device is required or liquid leakage is caused. There are problems such as the above problems, the cost of the liquid recovery mechanism, and the waste liquid treatment is troublesome.

  The present invention intends to solve the above-mentioned problems by controlling the contact / separation operation of the printing roller with respect to the plate cylinder in the back surface printing process for printing on the back surface of the paper in the stencil type duplex printing apparatus. .

According to the first aspect of the present invention, the first plate-making image for printing on the front surface of the paper fed from the paper feed unit and the second plate-making image for printing on the back surface of the paper are the circles. A plate cylinder arranged side by side in the circumferential direction, a printing roller with fine irregularities on the circumferential surface contacting and separating from the plate cylinder, and a pressing roller contacting and separating the printing roller for contacting and separating the printing roller from and to the plate cylinder The printing roller is brought into contact with the first printing area corresponding to the first plate-making image on the plate cylinder, and printing is performed on the surface of the sheet fed from the first sheet feeding unit. A first printing means, a temporary stock means provided obliquely below the plate cylinder and provided with a refeed tray for temporarily stocking paper that has been printed by the first printing means; and refeeding from the temporary stocking means A second paper feeding unit and a second printing area corresponding to a second plate-making image on the plate cylinder In a stencil type double-sided printing apparatus comprising: a second printing unit that contacts and separates the printing roller; and a second printing unit that performs printing on a back surface of a sheet re-fed from the second sheet feeding unit. A paper detection sensor that is provided in the temporary stocking unit and detects paper transport to a second printing section of paper that is re-fed from the second paper feed section; upon detection, and a mark pressure operation stop means for inhibiting a pressing operation of the second indicia pressure region in the plate cylinder of the impression roller by the impression roller moving means, the indicia application operation stop means A rocking member that supports the printing roller, a first cam that rocks the rocking member to move the printing roller in contact with and away from the plate cylinder in the first printing region, and the printing pressure. Previous to bring the roller into and out of the plate cylinder in the second printing area A second cam that swings the swing member, and a third cam that swings the swing member to bring the printing pressure roller into and out of contact with the plate cylinder in both the first printing region and the second printing region. And a cam switching means for selecting one of the first to third cams, and the paper detection sensor is used for the paper detection during double-sided printing by the first printing means and the second printing means. The first cam is selected by the cam switching means when a conveyance trouble is detected .
According to a second aspect of the invention, in the stencil-type double-sided printing apparatus according to claim 1, the paper detection sensor, and the paper leading edge detection sensor disposed in the sheet conveyance direction downstream side of the pre-Symbol one o'clock stock means, the paper conveying direction upstream It is a sheet trailing edge detection sensor arranged on the side .

  According to the present invention, in the stencil type double-sided printing apparatus, when the paper detection sensor detects a paper conveyance trouble, the pressing operation of the printing roller on the plate cylinder by the printing roller contacting / separating means is prohibited in the back surface printing process. Since the printing pressure operation stopping means is provided, the printing roller does not touch the printing cylinder and does not touch the printing cylinder when the paper is not present in the printing section between the printing cylinder and the printing pressure roller in the back side printing process. There is an effect that ink transfer to the roller is prevented and ink smearing of the printing roller is minimized.

The stencil type duplex printing apparatus of FIG. 1 includes a first printing unit and a second printing unit, and the first printing unit includes a first plate cylinder 101 on which a stencil sheet M1 that has been subjected to plate making is mounted, A first printing pressure roller 102 which can be brought into contact with and separated from the first printing cylinder 101, and a first printing section formed between the first printing cylinder 101 and the first printing pressure roller 102; Consists of.
The second printing means includes a second plate cylinder 103 on which the stencil stencil M2 that has been subjected to plate making is mounted, a second printing pressure roller 104 that can contact and separate from the second plate cylinder 103, and a second printing cylinder 103 A second printing unit formed between the plate cylinder 103 and the second printing pressure roller 104 is configured. Each of the plate cylinders 101 and 103 has a well-known configuration having a porous support plate and a mesh screen wound around the outer peripheral surface thereof, and is driven to rotate in the direction of the arrow by a plate cylinder driving means (not shown). . Inside the plate cylinders 101 and 103, known ink supply devices 105 and 106 are arranged, respectively.
The first printing pressure roller 102 is disposed below the first printing cylinder 101 so as to press the surface of the paper P fed from the paper feeding unit 107 against the first printing cylinder 101, and the second printing pressure roller. 103 are respectively arranged above the second plate cylinder 103 so as to press the back surface of the paper P that has passed through the first printing unit against the second plate cylinder 103.

A paper feed unit 107 feeds paper loaded on a paper feed stand 108 that can be raised and lowered, and a separation unit 110 that separates and feeds the paper fed by the paper feed roller 109 one by one. And is mainly composed. The fed paper is conveyed to the first printing unit by the registration roller 111 at a predetermined timing, printed on the surface thereof by the first printing means, and peeled off from the first plate cylinder 101. After being peeled off at 112 and sent to the second printing section by the intermediate sheet conveying device 113 including an endless belt, printing is performed on the back surface thereof by the second printing means, and then the peeling claw 114 is peeled off from the second plate cylinder 103. And is conveyed and discharged to a paper discharge tray (not shown).
The paper transport device 113 is provided with a light reflection type paper detection sensor 145 that detects paper sent from the first printing unit to the second printing unit.

  The first printing pressure roller 102 is a rubber roller whose peripheral surface is polished, and is rotatably supported at one end of the swing member 115. The swinging member 115 is pivotally attached to a stationary member of the apparatus main body by a shaft 116, and a cam follower 117 made of a roller is provided at the other end. The cam follower 117 is in contact with the printing pressure release cam 120 by the urging force of the printing pressure spring 119 having one end fixed to the swing member 115. The printing pressure release cam 120 is fixed to a shaft 121 that rotates in synchronization with the first plate cylinder 101, and the first printing pressure roller 102 is rotated by the rotation of the printing pressure release cam 120. The print plate abuts on the first plate cylinder 101 and is separated from the first plate cylinder 101 in the non-print region.

At a position corresponding to the lower end of the oscillating member 115, the printing pressure is released so that the first printing pressure roller 102 can be held away from the first printing cylinder 101 regardless of the rotation of the printing cylinder. A holding device 122 is provided.
The printing pressure release holding device 122 has a base portion that is swingably supported by a shaft 123, a locking member 124 having a locking claw 124a at the tip, and a clockwise direction around the shaft 123 in the drawing. And a solenoid 126 that rotates the locking member 124 against the elasticity of the spring 125. The solenoid 126 is in an off state, that is, the locking member 124 is the spring 125. When the swinging member 115 is rotated counterclockwise about the shaft 116 by the printing pressure release cam 120 in the state where the swinging member 115 is pulled up, the locked portion 115a at the lower end of the swinging member 115 is locked by the locking claw 124a. The first printing roller 102 is locked and held in a state of being separated from the first plate cylinder 101. When printing is started, the solenoid 126 is turned on, the locked portion 115a is released from the locking claw 124a, and the marking of the first printing roller 102 on the first plate cylinder 101 by the printing pressure release cam 120 is performed. Pressure operation is performed.

The second printing unit is disposed on the downstream side of the first printing unit in the paper conveyance direction via the intermediate conveyance device 113.
The second printing roller 104, which is a circumferential fine surface irregularity roller, is composed of a circumferential fine surface irregularity roller having fine irregularities on the circumferential surface. The second printing pressure roller 104, which is a peripheral fine uneven roller, is a method of winding a sheet of fine glass beads adhered, a synthetic resin sheet having innumerable fine protrusions formed on the peripheral surface by molding, It is made by other methods, for example, a method in which fine glass beads are applied and bonded to the peripheral surface of a rubber roller.
Since the ink of the printed image formed on the surface of the paper by the first printing unit does not dry immediately, the second printing roller 104 is in contact with the undried ink, but the second printing roller 104 By adopting the peripheral surface fine uneven roller, the ink stain on the peripheral surface of the second printing pressure roller 104 due to the contact with the undried ink can be reduced.

The second printing pressure roller 104 is rotatably supported at one end of the swing member 130 above the second plate cylinder 103. The swing member 130 is pivotally attached to a stationary member of the apparatus main body by a shaft 131, and a cam follower 132 made of a roller is provided at the other end. The cam follower 132 is in contact with the printing pressure release cam 134 by the elasticity of the printing pressure spring 133 having one end fixed to the swing member 130. The printing pressure release cam 134 is fixed to a shaft 135 that rotates in synchronization with the second plate cylinder 103, and the printing pressure release cam 133 rotates the second printing pressure roller 104 to print the second plate cylinder 103. The second plate cylinder 103 is brought into contact with the second plate cylinder 103 via the stencil sheet M2 in the region, and is separated from the second plate cylinder 103 in the non-printing region.
The pressure roller contacting / separating means is constituted by the swinging member 130, the printing pressure spring 133, the printing pressure release cam 134, and the means for rotating the printing pressure release cam 134 in synchronization with the rotation of the second plate cylinder 103.

In FIG. 2, the position corresponding to the upper end of the swing member 130 is a separation position in a state where the second printing roller 104 is separated from the second plate cylinder 103 regardless of the rotation of the second plate cylinder. The printing pressure release holding device 136 for holding the printing pressure and the printing pressure operation stopping means for immediately restraining the second printing pressure roller 104 to the separated position when a situation where the sheet is not conveyed to the second printing unit occurs. 137 is provided.
The printing pressure release holding device 136 includes a locking member 138, a spring 139, and a solenoid 140. Since the operation of the printing pressure release holding device 136 is the same as that of the printing pressure release holding device 122 already described, the description thereof is omitted.

  The printing pressure stopping means 137 is provided with an L-shaped locking member 142 that is swingably supported by a shaft 141, and gives the locking member 142 a counterclockwise rotation behavior around the shaft 141 in the drawing. The spring 143 and the solenoid 144 that rotates the locking member 142 clockwise against the elasticity of the spring 143 are configured. The front end of the locking member 142 forms a locking portion 142a. When the solenoid 144 is turned on and the locking member 142 rotates clockwise against the spring 143, the locking portion 142a It occupies a position in the swing locus of the locked portion 130a of the swing member 130 and restricts the operation of the swing member 130. FIG. 2 shows a state in which the solenoid 144 is on.

  The solenoid 144 is turned on when the paper detection sensor 145 (FIG. 1) does not detect the paper. The paper detection sensor 145 detects that the paper is jammed when the leading edge of the paper printed in the front surface printing process does not reach the sensor 145 even at a predetermined timing. In order to prevent the second printing pressure roller 104 from coming into contact with the second plate cylinder by activating the printing pressure operation stopping means 137 promptly, the paper detection sensor 145 causes a paper conveyance trouble as much as possible. Early detection is required. For this reason, the paper detection sensor 145 is disposed at a position that is as close as possible to the first printing unit of the paper conveyance path 113 and that does not cause erroneous detection.

In FIG. 2, when the paper detection sensor 145 detects a paper conveyance trouble, the printing pressure release cam 134 that is rotating at high speed has already passed through the cam follower 132 at its top 134a, and the locking member 138 is The swinging member 130 is opened by being pulled up by the solenoid 140. Therefore, at this time, if the movement of the swinging member 130 is not stopped, the second printing roller 104 comes into contact with the second plate cylinder, and the second printing roller 104 is stained with ink. Arise.
When the sheet detection sensor 145 detects a sheet conveyance trouble, the printing pressure operation stopping means 137 indicates the movement of the swinging member 130 released from the locking member 138, and the second printing pressure roller 104 performs the second printing operation. Since the ink is immediately stopped before it comes into contact with the plate cylinder, ink stains on the second printing pressure roller 104 are prevented.

FIG. 3 shows another example of the printing pressure operation stopping means for stopping the operation of the second printing pressure roller 104.
The locking member 150 is supported by an immovable member so that the upper end of the locking member 150 can swing on a shaft 151, and one end of a link 152 is connected to the lower end of the locking member 150 by a shaft 153. The other end of the link 152 is connected to the gear 155 by a shaft 154. The gear 155 meshes with a small gear 157 fixed to the shaft of the motor 156 and is rotationally driven in the direction of the arrow, and reciprocates the locking member 150 by the crank motion of the link 152.

  According to this printing pressure operation stopping means 137, when the paper detection sensor 145 (FIG. 1) detects a paper conveyance trouble, the cam follower 132 has already fallen into the valley of the printing pressure release cam 134 as shown in FIG. Even if the second printing roller 104 comes into contact with the second plate cylinder, the motor 156 rotates the gear 157 at an emergency high speed to push the swinging member 130 back to the right in the drawing at the lower end of the locking member 150. As a result, the contact of the second printing roller 104 with the second plate cylinder can be instantly eliminated. When the processing of the paper conveyance trouble is finished, the printing pressure operation stopping means is returned to the initial setting state shown in FIG.

Printing device of Figure 4 showing the implementation of the embodiment of the present invention includes a single plate cylinder, a stencil-type double-sided printing apparatus of monohull type for printing on both sides of the paper by the one impression roller.
A stencil sheet M made by the plate making apparatus 202 is wound around the plate cylinder 201 with the clamp 203 holding the leading end thereof. On the stencil sheet M, a first plate-making image as a front-side printing plate-making image and a second plate-making image as a back-side printing plate-making image are punched and plated side by side in the rotational direction of the plate cylinder 201. On the plate cylinder, I indicates a first printing area corresponding to the first plate-making image, and II indicates a second printing area corresponding to the second plate-making image.
The plate making apparatus 202 includes a thermal head 205 that forms a perforated image on the base paper drawn from the base paper roll 204, a platen roller 206 that presses the base paper against the thermal head 205, a cutter 207 that cuts the pre-made base paper, a conveyance roller, and the like. . Such a plate making apparatus, an original image reading apparatus for sending an image signal to the thermal head 205, an image signal processing means, and the like are well known in a plate making / printing integrated stencil printing apparatus, and thus the description thereof is omitted.

The paper feed unit 208 includes a paper feed roller 109 that feeds the paper on the paper feed stand 209 that can be moved up and down, and a separation unit 211 that separates and feeds the paper P delivered by the paper feed roller 210 one by one. It is mainly configured by.
The paper P stacked on the paper feed tray 209 is sized in accordance with the first and second printing areas I and II, for example, A4 size paper, or both the first and second printing areas I and II. A corresponding size, for example, A3 size paper is selectively placed. A4 size paper is fed to the printing unit via the registration roller 212 from the paper feed table 209 by lateral feeding and A3 size paper is fed longitudinally. The printing unit is formed between the plate cylinder 201 and a printing pressure roller 213 that can contact and separate the plate cylinder 201 via paper.

In FIG. 5, the printing pressure roller 213 is rotatably supported at one end of the swing member 215. The swing member 215 is pivotally attached to a stationary member of the apparatus main body by a shaft 216, and a cam follower 217 made of a roller is provided at the other end. The cam follower 217 is in contact with the printing pressure release cam 220 by the biasing force of the printing pressure spring 219 having one end fixed to the swing member 215. The printing pressure release cam 220 is fixed to a shaft 221 that rotates in synchronization with the plate cylinder 201, and the printing pressure release cam 220 rotates so that the printing pressure roller 213 contacts the plate cylinder 201 in the printing area of the plate cylinder 201. In the non-printing area, the plate cylinder 201 is separated.
A driving pulley 222 is provided on the shaft 216, and a driven pulley 223 is provided on the printing pressure roller 213. A timing belt 224 that drives the printing pressure roller 213 is stretched between the pulleys. The driving pulley 222 rotationally drives the printing pressure roller 213 in the direction of the arrow at the same peripheral speed as the peripheral speed of the plate cylinder 201 via the timing belt 224.

  At a position corresponding to the lower end of the swing member 215, a printing pressure release holding device 225 capable of holding the printing roller 213 apart from the plate cylinder 201 regardless of the rotation of the printing cylinder, and printing. When a situation occurs in which the sheet is not conveyed to the printing section, printing pressure operation stopping means 226 is provided for immediately restraining the printing pressure roller 104 to the separated position.

  The printing pressure release holding device 225 has a base portion that is swingably supported by a shaft 226, a locking member 228 having a locking claw 228a at the tip, and a clockwise direction about the shaft 227 in the drawing. And a solenoid 230 that rotates the locking member 228 against the elasticity of the spring 229. The solenoid 230 is in an off state, that is, the shaft is moved by the printing pressure release cam 220. When rotated counterclockwise about 216, the locked portion 215a is locked by the locking claw 228a, and the printing roller 213 is held in a state of being separated from the plate cylinder 201. When printing is started, the solenoid 230 is turned on, the locked portion 215a is released from the locking claw 228a, and the printing pressure operation of the printing pressure roller 213 to the plate cylinder 201 by the printing pressure release cam 220 is performed.

On the other hand, the printing pressure operation stopping means 226 includes a locking member 250 that immediately stops the operation of the printing pressure roller 213 when a paper conveyance trouble is detected.
The locking member 250 is supported by a non-moving member so as to be swingable by a shaft 251, and one end of a link 252 is connected to the free end portion by a shaft 253. The other end of the link 252 is connected to the gear 255 by a shaft 254. The gear 255 is meshed with a small gear 257 fixed to the shaft of the motor 256, is rotationally driven in the direction of the arrow, and reciprocates the locking member 250 by the crank motion of the link 252.

In FIG. 4, on the downstream side of the printing unit in the sheet conveyance direction, a path switching claw that is selectively switched between a first position for moving a printed sheet straight and a second position (the position shown in the drawing) that is sent obliquely downward to the left. 258 is provided.
The first printing in which the sheet (A4 size) fed from the sheet feeding unit 208 to the printing unit is formed by the registration roller 212 with the first printing area I of the plate cylinder 201 and the printing pressure roller 213 at a predetermined phase timing. The first printing unit prints the surface image by the first printing unit. The printed sheet A of the front image is guided diagonally downward to the left by the passage switching claw 258 and the leading end thereof falls on the movement guide 259 and is fed to the clamper 260.
Below the moving guide 259, a refeed tray 261 provided with a belt-type suction conveyance device is disposed. The belt-type suction conveyance device is relatively weak with a plurality of conveyance belts 364 that are stretched over a pair of rollers 262 and 263 arranged so as to sandwich the refeed tray 261 from the front and back, and run in the direction of arrow a. And a fan 265 that generates a suction force. A refeed tray provided with a belt-type suction conveyance device in a single cylinder type stencil type duplex printing apparatus as shown in FIG. 4 is described in Japanese Patent Application Laid-Open No. 2003-266906.

The movement guide 259 reciprocates in synchronization with the rotation of the plate cylinder 201 in an inclined direction indicated by an arrow b while maintaining a posture substantially parallel to the refeed tray 261 above the refeed tray 261. It is supposed to be.
The movement guide 259 holding the leading edge of the sheet moves to the rear end of the sheet re-feeding tray 261 while descending and stops, and opens the clamper 260 to release the sheet. The released sheet is conveyed rightward in the drawing by the belt-type suction conveyance device until the leading end of the sheet abuts against a stopper 266 described later. The movement guide 259 that has finished transporting the paper to the refeed tray 261 returns to the paper receiving position shown in the figure, and opens the clamper 260 at this position to wait for reception of the front surface printed paper.
In the same figure, the paper B already on the refeed tray 261 is brought to the refeed tray 261 prior to the paper A by the same operation as the paper transport operation of the movement guide 259 described for the paper A. The sheet having the surface image printed thereon is fed forward (to the right in the drawing) by the conveyor belt 264, and the leading end of the sheet abuts against the stopper 266 and is placed in a stopped state. In this state, the leading edge of the sheet B is located between the printing pressure roller 213 and the refeed roller 267 occupying a position away from the pressure roller 213. The stopper 266 advances and retreats with respect to the paper path in synchronization with the rotation of the plate cylinder 201, and the refeed roller 267 contacts and separates from the printing pressure roller 213 with a predetermined operational relationship with the stopper 266. .
A leading edge detection sensor 268 for detecting the arrival of the leading edge of the paper to be re-fed is provided at the front edge of the transport belt 264, and a portion corresponding to the trailing edge of the paper on the re-feed tray 261. Are respectively provided with trailing edge detection sensors 269 for detecting the passage of the trailing edge of the sheet conveyed by the conveying belt 264.

The stopper 266 moves backward from the paper path at a predetermined timing, and the refeed roller 267 abuts against the printing pressure roller 213 via the paper B to rotate the paper B at the same peripheral speed as the plate cylinder 201. It feeds between the pressure roller 213 and the curved guide plate 270. The sheet B is fed to the second printing section formed by the second printing region II of the plate cylinder 201 and the printing pressure roller 213 while receiving the conveying force of the printing pressure roller 213, and this second printing is performed. In this section, the back side image is printed by the second printing means, and the double-sided printing on the paper B is finished here.
When the front surface printing by the first printing means is finished, that is, when the rear end of the surface-printed paper has passed the passage switching claw 258, the passage switching claw 258 moves the paper straight from the second position shown in the figure. Therefore, the surface-printed paper B advances straight to the left in the drawing and is discharged by a paper discharge conveying device including a belt 273 and a suction fan 274 that spans between a pair of rollers 271 and 272. The paper is discharged onto the tray 275.

  A sheet to be sent from the refeed tray 261 to the second printing unit at a predetermined timing stays on the refeed tray 261 due to a conveyance trouble and is detected by the trailing edge detection sensor 269 or the movement guide 259. If the leading edge detection sensor 268 detects that the leading edge of the sheet does not hit the stopper 266 due to a trouble in conveying the sheet, the gear 256 is rotated at an emergency high speed by the motor 256 in FIG. The contact between the printing pressure roller 213 and the plate cylinder 201 is instantly canceled by pushing the swinging member 215 released from the right side back in the drawing at the upper end of the locking member 250.

FIG. 6 shows another example of the printing pressure operation stopping means for controlling the operation of the printing pressure roller 213 in FIG.
The printing pressure operation stopping means shown in FIG. 6 is different from the printing pressure operation stopping means in FIG. 5 which employs a link mechanism, and uses the printing pressure release cam to stop the printing pressure operation of the printing pressure roller.
The shaft 221 is provided with three printing pressure release cams 276a, 276b, and 276c that are integrated in the axial direction.
The printing pressure release cam 277a as the first cam is in the first printing area I of the plate cylinder 201, the printing pressure release cam 276b as the second cam is in the second printing area II, and the third printing area I. The printing pressure release cam 277c as a cam swings the swinging member 215 to bring the printing pressure roller 213 into and out of contact with the plate cylinder 201 in both the first printing region I and the second printing region II. Let
One of the three printing pressure release cams is selected by a printing pressure range switching mechanism as cam switching means according to double-sided printing or single-sided printing, and the cam follower 217 of the swing member 215 is selected as the selected printing pressure release cam. Corresponds.

FIG. 7 shows an example of the printing pressure range switching mechanism. A flange 278 is provided integrally with the cam group along with the printing pressure release cams 277a, 277b, and 277c on the cam shaft 221, and a U-shaped groove portion 280 formed in the rack 279 is formed on the flange 278. Is engaged. The rack 279 is slidable in a direction parallel to the cam shaft 221 and supported by a non-moving member by a support mechanism (not shown), and a pinion gear 282 fixed to the shaft of a stepping motor 281 as a cam switching motor. I'm engaged.
A printing pressure range switching mechanism of a printing pressure roller with respect to a plate cylinder using three printing pressure release cams as shown in FIG. 7 is described in Japanese Patent Application Laid-Open No. 2003-266906.

As shown in FIG. 7, the printing pressure release cam 277c is selected, and during the double-sided printing in which the front surface printing is performed in the first printing region I and the back surface printing is performed in the second printing region II, the refeed tray 261 ( When a conveyance trouble occurs in the paper to be sent to the printing unit at a predetermined timing from FIG. 4, and this is detected by the leading edge detection sensor 262 or the trailing edge detection sensor 263, the pinion gear 282 is moved by the motor 282 in FIG. 7. The rack 279 is moved to the right side to switch the cam for the cam follower 217 from the printing pressure release cam 277c to the printing pressure release cam 277a, and the printing roller 213 contacts the plate cylinder 201 in the second printing region II. To prevent ink stains on the printing roller 213.
In the first printing area I, second printing area II, and both areas I and II of the plate cylinder, the double-sided printing apparatus using three cams for contacting and separating the printing pressure roller to and from the printing cylinder conveys to the paper. By adopting a cam switching means for selecting one cam when trouble occurs, there is an effect that it is not necessary to provide a printing pressure operation stopping means specially.
FIG. 8 is a block diagram of the control unit of the printing pressure stopping means in the stencil type duplex printing apparatus shown in FIG.

It is a side view of a stencil type double-sided printing apparatus having two plate cylinders. It is a side view which shows an example of the printing pressure operation | movement stop mechanism in the stencil type duplex printing apparatus of FIG. It is a side view which shows another example of the printing pressure operation | movement stop mechanism in the stencil type double-sided printing apparatus of FIG. It is a side view of a monohull type stencil type double-sided printing apparatus for illustrating the implementation of the invention. FIG. 5 is a side view showing an example of a printing pressure operation stopping mechanism in the stencil type duplex printing apparatus of FIG. 4. FIG. 5 is a side view showing a printing pressure roller control mechanism provided with three printing pressure release cams for each printing region of the plate cylinder in the stencil type duplex printing apparatus of FIG. 4. It is the figure which looked at FIG. 6 from the lower part. FIG. 8 is a block diagram of the control unit of the printing pressure stopping means in the stencil type duplex printing apparatus shown in FIG. It is an expanded partial sectional view of a printing roller in which fine irregularities are formed on the peripheral surface with glass beads. FIG. 3 is an enlarged partial cross-sectional view showing a state where a large amount of ink from the stencil sheet has been transferred to the fine uneven surface of the printing pressure roller.

Explanation of symbols

101, 103, 201 Plate cylinder 102, 104, 213 Printing roller 107 Paper feeding unit 113 Paper transport path 180 Paper feeding unit 130, 215 Oscillating member 135, 220, 277a, 277b, 277c Printing pressure release cams 137, 226 Printing pressure operation stopping mechanism 145, 268, 269 Paper detection sensor 261 Second paper feeding unit I First printing area
II Second printing area

Claims (2)

A first plate making image for printing on the front surface of the paper fed from the paper feeding unit and a second plate making image for printing on the back surface of the paper are arranged side by side in the circumferential direction. A printing cylinder,
A printing roller with fine irregularities on the circumferential surface coming into contact with and separating from the plate cylinder;
A pressure roller contacting / separating means for bringing the printing pressure roller into and out of contact with the plate cylinder;
The printing roller is brought into contact with a first printing area corresponding to the first plate-making image of the plate cylinder, whereby printing is performed on the surface of the paper fed from the first paper feeding unit. Printing means;
Temporary stocking means provided with a refeed tray that is provided obliquely below the plate cylinder and temporarily stocks paper that has been printed by the first printing means;
A second paper feeding section for refeeding from the temporary stock means;
In the second printing unit in which the printing roller comes in contact with and separates from the second printing area corresponding to the second plate-making image of the plate cylinder, the back surface of the sheet re-feeded from the second sheet feeding unit A stencil type double-sided printing apparatus comprising: a second printing unit that performs printing;
A paper detection sensor provided in the temporary stocking means for detecting the conveyance of paper to the second printing unit for paper re-fed from the second paper feeding unit;
When the paper detection sensor detects a paper conveyance trouble, printing pressure operation stopping means for prohibiting the pressure roller contacting / separating means from pressing the printing roller against the second printing pressure area in the plate cylinder; The printing pressure operation stopping means includes a swinging member that supports the printing pressure roller,
A first cam that swings the swinging member to bring the printing roller into and out of contact with the plate cylinder in the first printing region;
A second cam that rocks the rocking member to bring the printing roller into and out of contact with the plate cylinder in the second printing region;
A third cam that swings the swinging member to bring the printing roller into and out of contact with the plate cylinder in both the first printing region and the second printing region;
Cam switching means for selecting one of the first to third cams,
During the double-sided printing by the first printing means and the second printing means, when the paper detection sensor detects a paper conveyance trouble, the cam switching means selects the first cam. Stencil type duplex printing device. In the stencil type double-sided printing device according to claim 1,
Sheet detection sensor, and the paper leading edge detection sensor disposed in the sheet conveyance direction downstream side of the pre-Symbol one o'clock stock means, stencil type double-sided, characterized in that the paper trailing edge detection sensor disposed in the sheet conveyance direction upstream side Printing device.

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