JP4885477B2 - Printing device - Google Patents

Description

  The present invention relates to a printing apparatus that performs printing by pressing a recording medium against an outer peripheral surface of a printing drum, and more particularly to a printing apparatus that has a function of forcibly separating a recording medium from the surface of the printing drum by blowing air.

For example, in a stencil printing apparatus, the outer periphery of a porous printing drum (plate cylinder) having ink supply means inside a master that has been perforated by a thermal head or the like based on data read from a document or data received from an externally connected device Printing is performed by pressing a recording medium such as a printing paper against the printing drum by pressing means such as a press roller that is wound around the surface and is provided so as to be able to contact with and separate from the outer peripheral surface of the printing drum.
By the pressing (printing pressure) by the pressing means, the ink supplied to the drum inner peripheral surface oozes out through the drum opening portion and the master punching portion, and is transferred to the printing paper to form a printed image.

The printing paper that has passed through the printing site pressed by the press roller is in close contact with the surface of the printing drum due to the adhesive force of the ink. In this state, the printing paper moves with the rotation of the printing drum while being in close contact with the printing drum, and is not separated in the paper discharge direction, causing a so-called “roll-up phenomenon”, resulting in a jam.
In order to solve this problem, conventional methods forcibly separating the leading end of the printing paper in the drum rotation direction with a wedge-shaped separation claw, or between the surface of the printing drum and the printing paper by air blowing means (air knife) have been used. A system in which air is blown and separated, or a system using these in combination is employed.
Even with such a separation method, if there are many solid portions (portions where the ink transfer area is large) at the leading end of the printing paper in the drum rotation direction, separation is not performed smoothly and time is required. The timing may be delayed and a roll-up jam may occur.

When printing continuously with multiple sheets of paper, the time for discharging the printing paper is limited for control purposes, and if the time is exceeded, it is considered that the printing paper has not been separated from the printing drum, and a roll-up jam occurs. It was judged.
In order to avoid a problem in the case where there are many solid portions at the front end portion of the printing paper, a contrivance has been made to make the margin of the front end portion of the printing paper as long as possible and to make the separation smooth. When the margin is increased, the timing for feeding the printing paper to the printing drum may be advanced. Adjustment of the paper feed timing is generally performed by adjusting the position of the print paper in the paper feed direction on the paper feed table.

JP 2002-154260 A Japanese Patent Laid-Open No. 10-217595

By adjusting the position of the printing paper conveyance direction and changing the length of the leading margin, some degree of roll-up jam can be avoided, but the certainty is not very high, and the margin length can be changed. Since the printing position changes, there is a problem that the printed material is different from the desired one for the user.
Further, when the amount of the solid portion is different at both ends in the width direction orthogonal to the conveyance direction of the printing paper, there is a problem that the discharge timing is different at both ends and the discharge posture is shifted.
When the paper discharge posture is deviated, the paper discharge alignment becomes worse when the print paper is discharged to the paper discharge tray, and it takes time to align the paper after printing. In particular, during double-sided printing, the paper cannot be turned over and set on the paper feed stand, so the effect on the efficiency of the entire printing operation is significant.

  In the configuration having the air blowing means, it is possible to facilitate separation even if there are many solid portions if the air volume is increased, but if the air volume is set to the state where the image density is the largest (the solid portion is large), Otherwise, excessive energy (electric power) is always consumed, which is not appropriate from the viewpoint of energy saving.

  SUMMARY OF THE INVENTION The main object of the present invention is to provide a printing apparatus that can reduce winding jam as much as possible by increasing the separation of the recording medium from the printing drum without changing the position of the recording medium, and can also save energy. .

In order to achieve the above object, in the invention described in claim 1, air is blown between the surface of the printing drum and the recording medium, and the air blowing means for separating the printed recording medium from the printing drum; In a printing apparatus having recording medium receiving means for receiving a recording medium separated from a printing drum, the printing apparatus has separation state detection means for detecting a separation state of the recording medium from the printing drum, and the separation state detection means It comprises a recording medium detection means for detecting the recording medium that has reached the medium receiving means, determines a separation state by a time interval from a reference position to detection by the recording medium detection means, and according to the determined separation state, The air volume for the next recording medium in the air blowing state by the air blowing means is controlled.

  According to a second aspect of the present invention, in the printing apparatus according to the first aspect, the recording medium receiving means is a suction conveying apparatus that conveys the separated recording medium while sucking the separated recording medium to a discharge unit. .

According to a third aspect of the present invention, in the printing apparatus according to the first or second aspect, the reference position is a recording medium conveyance start position in rotation of the printing drum .

According to a fourth aspect of the present invention, in the printing apparatus according to any one of the first to third aspects, the recording medium detection unit and the air blowing unit are each perpendicular to a conveyance direction of the recording medium. It is arranged at the central part in the width direction of the medium .

According to a fifth aspect of the present invention, in the printing apparatus according to any one of the first to third aspects, the recording medium detecting unit and the air blowing unit are each perpendicular to a conveyance direction of the recording medium. It is arranged at both ends in the width direction of the medium.

According to a sixth aspect of the present invention, in the printing apparatus according to the fifth aspect , when there is a difference in detection timings of the recording medium detection means arranged at both ends, the recording medium detected later The air volume of the air blowing means corresponding to the recording medium detecting means is increased .

According to a seventh aspect of the present invention, in the printing apparatus according to any one of the first to sixth aspects, the detection information from the separation state detection unit and the air volume of the air blowing unit, which are obtained in advance, And the air volume of the air blowing means is set based on the relation data table .

According to the present invention, it is possible to reduce the roll-up jam without adjusting the position of the printing paper (position adjustment in the paper conveyance direction) and obtain a printed matter intended by the user.
Further, it is possible to reduce the roll-up jam regardless of the amount of the solid portion, and it is possible to save energy by always setting the optimum air volume.
Further, it is possible to correct the paper discharge alignment regardless of the amount of the solid portion and the position of the solid portion, and it is possible to improve the handleability of the printed paper after printing.

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
First, based on FIG. 1, the overall configuration of the stencil printing apparatus and the outline of the stencil printing process in this embodiment will be described.
A document reading unit 80 having an ADF function is provided in the upper part of the apparatus main body 50, and a printing drum unit 100 having a porous printing drum (plate cylinder) 101 is provided in the lower central part thereof. A plate making device 90 is provided on the upper right side of the printing drum unit 100, and a plate discharging device 70 is provided on the upper left side of the printing drum unit 100. In addition, a paper feeding device 110 is provided below the plate making device 90, a printing pressure unit 120 is provided below the printing drum unit 100, and a paper discharge unit 130 is provided below the plate discharging device 70.

Next, the printing operation of the stencil printing apparatus according to the above configuration will be described.
First, a document 60 having an image to be printed is placed on a document placing table (not shown) disposed at the top of the document reading unit 80, and a plate making start key on an operation panel (not shown) is pressed. Along with pressing of the plate making start key, a plate removing process is first executed. That is, in this state, the used master 61b used in the previous printing remains attached to the outer peripheral surface of the printing drum 101 of the printing drum unit 100.

When the printing drum 101 rotates counterclockwise and the rear end portion of the used master 61b on the outer peripheral surface of the printing drum 101 approaches the plate release peeling roller pair 71a, 71b, the plate release peeling roller pair 71a, 71b is rotating. One discharge plate peeling roller pair 71a scoops up the rear end portion of the used master 61b.
The used master 61b is a pair of discharge plate conveying belts 72a and 72b wound around a pair of discharge plate rollers 73a and 73b disposed on the left side of the pair of discharge plate peeling rollers 71a and 71b and the pair of discharge plate peeling rollers 71a and 71b. While being transported in the direction of the arrow Y1, it is discharged into the discharge plate box 74 and is peeled off from the outer peripheral surface of the printing drum 101 to complete the discharge plate process. At this time, the printing drum 101 continues to rotate counterclockwise. The used master 61 b that has been peeled and discharged is then compressed inside the plate discharging box 74 by the compression plate 75.

In parallel with the plate removal process, the document reading unit 80 reads the document. A document 60 placed on a document table (not shown) is exposed and read while being conveyed in the directions of arrows Y2 to Y3 by the rotation of the separation roller 81, the pair of front document transport rollers 82a and 82b, and the pair of rear document transport rollers 83a and 83b. To be served. At this time, when there are a plurality of documents 60, the separation blade 84 feeds them one by one from the lowest document. In reading the image of the original 60, the reflected light from the surface of the original 60 illuminated by the fluorescent lamp 86 is reflected by the mirror 87 while being conveyed on the contact glass 85, and is constituted by a CCD (charge coupled device) through the lens 88. This is performed by being incident on the image sensor 89.
The original 60 is read by a well-known reduction-type original reading method, and the original 60 from which the image has been read is discharged onto the original tray 80A. The electrical signal photoelectrically converted by the image sensor 89 is input to an analog / digital (A / D) conversion board (not shown) in the apparatus main body 50 and converted into a digital image signal.

In parallel with this image reading operation, plate making and plate feeding processes are performed based on the image information converted into digital signals. A roll-shaped masterless master 61 set at a predetermined portion of the plate-making apparatus 90 is pulled out of a roll state and is pressed against a thermal head 91 as a recording device via the master 61, and a tension roller The pair 93a, 93b is transported to the downstream side of the transport path.
A plurality of minute heating resistors arranged in a line on the thermal head 91 with respect to the master 61 transported in this way are each in response to a digital image signal sent from an A / D conversion board (not shown). The thermoplastic resin film of the master 61 that selectively generates heat and is in contact with the generated heating resistor is melt-pierced.
In this way, image information is written as a drilling pattern by position-selective melt drilling of the master 61 according to the image information.

  The leading end of the master-making master 61a on which image information has been written is fed toward the outer peripheral side of the printing drum 101 by a pair of feed rollers 94a and 94b, and the traveling direction is changed downward by a guide member (not shown). The printing drum 101 in the plate feeding position state hangs down toward the expanded master clamper 102 (indicated by a virtual line). At this time, the used master 61b has already been removed from the printing drum 101 by the plate discharging process.

  When the leading edge of the master-making master 61a is clamped by the master clamper 102 at a fixed timing, the printing drum 101 gradually winds the master-making master 61a around the outer peripheral surface while rotating in the direction A (clockwise direction) in the figure. Go. The rear end portion of the master-making master 61a is cut into a fixed length by a cutter 95.

When one plate-made master 61a is wound around the outer peripheral surface of the printing drum 101, the plate-making and plate-feeding steps are finished, and the printing step is started. First, the uppermost one of the printing sheets 62 as the sheet-like recording medium stacked on the sheet feeding table 51 is sent out in the direction of arrow Y4 by the sheet feeding roller 140 toward the registration roller pair 142, and The registration roller pair 142 is sent to the printing pressure portion (image transfer portion) 120 at a predetermined timing synchronized with the rotation of the drum portion 100. When the fed printing paper 62 comes between the printing drum 101 and the press roller 103 as a pressing member, the press roller 103 that is spaced below the outer peripheral surface of the printing drum 101 is moved upward by a printing pressure applying mechanism (not shown). Is moved by the pre-made master 61 a wound around the outer peripheral surface of the printing drum 101.
Thus, ink oozes out from the opening portion of the printing drum 101 and the perforation pattern portion (both not shown) of the master-making master 61a, and the oozing ink is transferred to the surface of the printing paper 62 to form a printed image. The The first printing after the plate feeding process may be referred to as printing.

On the inner peripheral side of the printing drum 101, ink is supplied from an ink supply pipe 104 to an ink reservoir 107 formed between the ink roller 105 and the doctor roller 106, in the same direction as the rotation direction of the printing drum 101, and Ink is supplied to the inner peripheral side of the printing drum 101 by an ink roller 105 that rolls in contact with the inner peripheral surface while rotating in synchronization with the rotation speed of the printing drum 101.
The press roller 103 is disposed outside the printing drum 101 at a position facing the ink roller 105.

The printing paper 62 on which the printing image is formed in the printing pressure unit 120 is separated from the printing drum 101 by the separation claw 114, and is sucked and transported to a suction transport device 119 as a recording medium receiving unit having a suction fan 118. . Specifically, the rotation of the conveyance belt 117 stretched around the suction discharge inlet roller 115 and the suction discharge outlet roller 116 of the suction conveyance device 119 is brought into close contact with the conveyance belt 117 and the arrow Y5. In this manner, the sheet is conveyed toward the sheet discharge unit 130 and sequentially discharged and stacked on the sheet discharge table 52. In this way, so-called trial printing is completed.
Next, when the number of prints is set with a numeric keypad (not shown) and a print start key (not shown) is pressed, the steps of paper feeding, printing and paper discharge are repeated for the set number of prints in the same process as the trial printing. All the processes of stencil printing are completed.

FIG. 2 is a simplified schematic diagram of FIG. 1 from the viewpoint of clarifying the features of the present invention. The parts omitted in FIG. 1 and the description thereof will be described. From the time when the printing drum 101 rotates and the shielding plate 20 provided on the printing drum 101 shields the paper feeding start sensor (recording medium conveyance start sensor) 21 provided on the apparatus main body 50, The stacked printing paper 62 is conveyed toward the printing pressure section via the paper feed roller 140 and the registration roller pair 142.
Inside the conveyance belt 117 of the suction conveyance device 119, a paper discharge sensor 22 is provided as a recording medium detection unit that detects the printing paper 62 separated from the printing drum 101. An air blowing means (air knife) 23 for blowing air between the surface of the printing drum 101 and the printing paper 62 is provided on the lower surface of the plate discharging device 70. The paper discharge sensor 22 and the air blowing means 23 are respectively disposed at the central portion in the paper width direction orthogonal to the conveyance direction of the print paper 62.
The air blowing means 23 includes a fan motor 24 shown in FIG. 3, a fan (not shown) that is rotationally driven by the fan motor 24, and a casing (not shown) in which a blowout port is throttled.

When the printing paper 62 is peeled off from the surface of the printing drum 101, the leading end of the printing paper 62 in the drum rotation direction is first peeled off by the separation claw 114, and subsequently peeled off by the air flow blown out from the air blowing means 23.
The air blowing means 23 is controlled by the control means 25 shown in FIG. The control means 25 is a microcomputer having an I / O interface 26, a CPU 27, a ROM 28, a RAM 29, and the like.
An encoder 31 is attached to a main motor (not shown) that rotationally drives the printing drum 101, and all timings are managed by counting the number of pulses of the encoder 31. In this embodiment, the number of pulses of the encoder 31 is described as 1000 pulses / rotation.
Here, the fan motor 24 uses a system in which the rotational speed can be varied by inputting a pulse corresponding to the frequency from the outside and the air volume can be increased or decreased. However, the air volume can be increased or decreased by varying the drive voltage. A method that can be used may be used.

In the present embodiment, a separation state detection unit that detects (monitors) the separation state (behavior) of the printing paper 62 from the printing drum 101 is provided, and the control unit 25 is based on detection information from the separation state detection unit. Controls the air volume of the air blowing means 23.
Counting of the number of pulses of the encoder 31 is started after the paper feed start sensor 21 is turned on (reference position), and the number of pulses until the leading edge of the print paper 62 is detected by the paper discharge sensor 22 is counted. The separation state of the sheet 62 can be grasped.
The shielding plate 20, the paper feed start sensor 21, the encoder 31, and the paper discharge sensor 22 constitute a separation state detection unit.

The behavior of the printing paper 62 is monitored at the timing shown in the timing chart shown in FIG. That is, it is performed by managing the time (number of pulses) for the print paper 62 to reach the paper discharge sensor 22 between the roll-up detection start position (point B) and the roll-up detection end position (point C).
In the ROM 28 or RAM 29 of the control means 25, a relation data table between the detection information from the separation state detection means and the air volume of the air blowing means 23, which is obtained in advance by experiments or the like (including computer simulation), that is, FIG. As shown, a relational data table of the arrival time (timing count number) to the paper discharge sensor 22 between the points B and C and the input pulse frequency of the fan motor 24 is stored.

When a printing start key (not shown) is pressed on the operation panel 30 shown in FIG. 4, the main motor is activated and the printing drum 101 is rotated. When the paper feed start sensor 21 is shielded by the shielding plate 20 on the printing drum 101, the printing paper 62 on the paper feed tray 51 is transported and printing is performed by the printing pressure unit 120.
The leading edge of the printing paper 62 that has passed through the printing pressure section 120 is peeled off by the separation claw 114, and further peeled off by the air flow from the air blowing means 23. In this case, when there are many solid images at the leading end of the printing paper 62, the time until the printing paper is peeled off becomes longer than when there are few solid images. If not, it was conventionally judged as a paper roll-up jam.

In this embodiment, the separation state of the printing paper 62 is monitored, and when the arrival time of the printing paper 62 to the paper discharge sensor 22 is delayed, the rotational speed of the fan motor 24 is varied to control the air volume of the air blowing means 23. By making it variable, paper roll-up jams are reduced.
For example, when the arrival time to the paper discharge sensor 22 between the points B and C is 880 pulses, the control unit 25 sets the input pulse frequency 2900 (Hz) corresponding to this for the next printing paper 62. Select and control the fan motor 24. The fan air volume in this case is 0.74 m ³ / min.
Thereby, the air volume of the air blowing means 23 increases and the separation function is enhanced.
In the case of different printing (jobs), when the arrival time (pulses) to the paper discharge sensor 22 between the points B and C decreases, the corresponding input pulse frequency is selected and the fan motor 24 is controlled. .
Therefore, it is possible to always obtain the optimum air volume for separation and to save energy.

A second embodiment will be described with reference to FIGS. In addition, the same part as the said embodiment is shown with the same code | symbol, and unless it was especially required, the description on the structure and function which were already demonstrated is abbreviate | omitted, and only the principal part is demonstrated.
As shown in FIG. 7, the paper discharge sensor 22 and the air blowing means 23 are respectively disposed at both ends of the paper width direction orthogonal to the conveyance direction of the print paper 62. The air blowing means 23A arranged at the right end in the transport direction (paper discharge direction) of the printing paper 62 has a fan motor 24A, and a paper discharge sensor 22A is arranged correspondingly.
The air blowing means 23B disposed at the left end in the conveyance direction (paper discharge direction) of the printing paper 62 has a fan motor 24B, and a paper discharge sensor 22B is disposed correspondingly.

  In the ROM 28 or RAM 29 of the control means 25, a relation data table between the detection information from the separation state detection means and the air volume of the air blowing means 23, which is obtained in advance by experiments or the like (including computer simulation), that is, FIG. As shown, a relationship data table between arrival times (timing count numbers) to the paper discharge sensors 22A and 24B between the points B and C and the input pulse frequencies of the fan motors 24A and 24B is stored.

When the solid portion of the print image is biased to either the left or right side of the print paper 62, the print paper 62 is peeled off from the print drum 101, causing variations in the left and right sides. For example, when the solid portion exists at the right end, it takes time to separate the right side, and as shown in FIG. 10, the printing paper 62 finally separated from the printing drum 101 has a horizontal posture with the left side leading. Shift.
In this case, as a result, the paper discharge alignment is deteriorated, and the above-described labor is required.

In the present embodiment, the separation state of the printing paper 62 is monitored on the left and right (both ends), and when the arrival time of the printing paper 62 to the paper discharge sensors 22A and 22B is delayed, the rotation speeds of the fan motors 24A and 24B Is changed to change the air volume of the air blowing means 23A and 23B, thereby reducing the paper roll-up jam.
For example, when the arrival time to the paper discharge sensor 22A between point B and point C is 900 pulses and the arrival time to the paper discharge sensor 22B is 880 pulses, the control unit 25 applies to the next printing paper 62. Selects the input pulse frequencies 3000 (Hz) and 2900 (Hz) corresponding to this, and controls the fan motors 24A and 24B.
Thus, the air volume of the right air blowing means 23A (0.78 m ³⁾ is increased compared to the air volume (0.74 m ³⁾ of the left air blowing means 23B, together with the separation function is enhanced, the left and right separation misregistration It is corrected.
Therefore, it is possible to always obtain the optimum air volume for separation, to save energy, and to eliminate the deviation of the paper discharge posture.
In the present embodiment, the air blowing means and the paper discharge sensor are arranged at both ends in the paper width direction orthogonal to the conveyance direction of the printing paper 62, but may be arranged at a central portion to form a three-position arrangement.

In each of the above-described embodiments, the suction conveyance device 119 is exemplified as the recording medium receiving unit.
Further, although the separation claw 114 and the air blowing means 23 are used in combination, the separation claw 114 and the air blowing means 23 may be separated only.

1 is a schematic front view of a stencil printing apparatus according to a first embodiment of the present invention. 1 is a schematic diagram of a stencil printing apparatus from the viewpoint of explaining the gist of the invention. It is a principal part top view. It is a control block diagram. It is a timing chart concerning separation control. It is a relationship data table of the detection information from a separation state detection means, and the air volume of an air blowing means. It is a principal part top view in 2nd Embodiment. It is the same control block diagram. It is a relationship data table between the detection information from the separation state detection means and the air volume of the air blowing means. It is a top view for demonstrating discharge discharge | emission.

Explanation of symbols

DESCRIPTION OF SYMBOLS 22 Paper discharge sensor as a recording medium detection means 23 Air blowing means 62 Printing paper as a recording medium 101 Printing drum 119 Adsorption conveyance apparatus as a recording medium receiving means

Claims (7)

Printing having air blowing means for blowing air between the surface of the printing drum and the recording medium to separate the printed recording medium from the printing drum, and recording medium receiving means for receiving the recording medium separated from the printing drum In the device
A separation state detection unit that detects a separation state of the recording medium from the printing drum, and the separation state detection unit includes a recording medium detection unit that detects the recording medium that has reached the recording medium receiving unit;
Judge the separation state by the time interval from the reference position to the detection by the recording medium detection means,
According to the determined separation state, an air volume for the next recording medium in the air blowing state by the air blowing means is controlled. The printing apparatus according to claim 1,
The printing apparatus, wherein the recording medium receiving means is an adsorption conveyance apparatus that conveys the separated recording medium while sucking the separated recording medium to a discharge unit. The printing apparatus according to claim 1 or 2,
The printing apparatus according to claim 1, wherein the reference position is a conveyance start position of a recording medium in rotation of the printing drum. The printing apparatus according to any one of claims 1 to 3,
The printing apparatus according to claim 1, wherein the recording medium detection unit and the air blowing unit are respectively disposed at a central portion in the width direction of the recording medium orthogonal to the conveyance direction of the recording medium. The printing apparatus according to any one of claims 1 to 3,
The printing apparatus, wherein the recording medium detection unit and the air blowing unit are respectively disposed at both ends in the width direction of the recording medium orthogonal to the conveyance direction of the recording medium. The printing apparatus according to claim 5, wherein
When there is a difference in the detection timing of the recording medium detection means disposed at both ends, the air volume of the air blowing means corresponding to the recording medium detection means on which the recording medium is detected later is increased. Printing device to do. The printing apparatus according to any one of claims 1 to 6,
It has a relation data table of detection information from the separation state detection means and the air volume of the air blowing means, which are obtained in advance, and the air volume of the air blowing means is set based on the relation data table. Printing device to do.

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