JP2000033764A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deflection-generating part of a sheet, before it reaches a nip part, from coming into contact with a master which is through with a makeup process and thereby prevent the sheet from becoming smeared by ink, even when a deflection is generated near the holding part of the tip part of the sheet with a catcher claw by setting a sheet conveying velocity to be higher than the peripheral velocity of an impression cylinder, in a stencil printing device of a sheet catcher impression cylinder system or the like. SOLUTION: In a sheet conveying velocity control system (sheet conveying velocity V' > the peripheral velocity V of impression cylinder 20) in which a force to make the tip part of a sheet 3 slip off a catcher claw 21 does not work, a guide member 160 for guiding the sheet 3 so that the deflection 3B- generating part of the sheet 3, before it reaches a nip part formed by the outer peripheral face of a plate cylinder 1 and the outer peripheral face of the impression cylinder 20, does not come into contact with a master 2 which is through with a makeup process on the plate cylinder 1 is installed in a sheet conveying path R located before the nip part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a printing apparatus,
The present invention relates to a printing device such as a stencil printing device that performs printing by winding a master around a plate cylinder and pressing a sheet with an impression cylinder or a plate cylinder.

[0002]

2. Description of the Related Art In a stencil printing apparatus, which is one of the printing apparatuses, a mark for forming a print image by pressing a printing sheet with a pressing means against a plate cylinder around which a master made of a plate is wound around an outer peripheral surface. There is already known an example in which a pressure cylinder having a diameter substantially equal to the outer diameter of the plate cylinder and rotating at a speed substantially equal to a peripheral speed of the plate cylinder in a direction opposite to the plate cylinder is used as the pressure device. This impression cylinder has a concave portion provided on a part of its outer peripheral portion in order to avoid interference with a master clamper which holds the front end portion of a master provided on the outer periphery of the plate cylinder. Since the amount of movement when the pressure is turned on / off can be reduced, the printing pressure noise can be reduced, and the noise of the stencil printing apparatus can be reduced.

Usually, the leading end of the fed paper is clamped and held in the recess of the impression cylinder.
Alternatively, the clamp device may be referred to as a “clamp”. The leading edge of the paper fed by the gripper is conveyed by a rotating impression cylinder while holding the paper, and the sheet is pressed against the plate cylinder to perform printing (the outer diameter of the plate cylinder and the outer diameter of the impression cylinder). Can be clamped and printed one sheet at a time, so that in the stencil printing process, the paper cannot be peeled off by the paper ejection nail or peeling nail while the leading end of the paper remains attached to the plate cylinder. So-called "paper ejection (paper)
It is possible to prevent "rolling up" and to improve the positional accuracy (registration accuracy) of the printed image in the paper transport direction.

Hereinafter, with reference to FIG. 21 to FIG. 26, a problem in clamping a sheet by a gripper of a clamp device in an impression cylinder and a sheet conveying operation will be described. For example, in a stencil printing apparatus as shown in FIG. 21, for the purpose of reducing noise of the stencil printing apparatus and improving the registration accuracy of the paper 3, etc., an impression cylinder 20 having a gripper 21 as a pressing means, so-called "paper The "pressing cylinder method" is used. As shown in FIG. 21, the impression cylinder 20 has an outer diameter Da (diameter) equal to the outer diameter Da (diameter) of the plate cylinder 1. 20 also makes one rotation. For this reason, as shown in the figure, a holding claw 21 for clamping the leading end of the fed paper 3 can be provided on the impression cylinder 20, while the leading end of the paper 3 abuts against the holding claw 21. By feeding the paper, the registration accuracy of the paper 3 can be improved. In FIG. 21, the holding claws 21 and the paper discharge claws 44 are simply shown. FIG.
2 and FIG. 26, the clamp device 150
An openable / closable gripper 21 for clamping the leading end of the fed paper 3, a shaft 156 fixed to the base end of the gripper 21 with a screw and extending in the direction of one bus line on the outer periphery of the impression cylinder 20; A cam follower 157 which engages with a cam (not shown) for driving the gripper 21 to open and close; a shaft 156 and a cam follower 1;
And a base 155 fixed to the recess 57 and transmitting the movement of the cam to the holding claws 21; a base 155 fixed to the recess 22 and supporting both ends of the shaft 156 by a predetermined angle;
It is mainly composed of a magnet 154 that holds the gripper 21 at its closing position with its magnetic force, and a tension spring 158 that urges the gripper 21 in the closing direction. As shown in FIG. 22, the gripper 21 is printed by the impression cylinder 20 when the paper nail 151 clamps the leading end of the paper 3 and comes to the position of the paper ejection nail 44 after being clamped by the paper nail 151. It is composed of a peeling claw 152 for peeling off the paper 3 and a stopper claw 153 for abutting on the leading end of the fed paper 3 to position the leading end of the paper 3 and is integrally formed by cutting and bending a sheet metal.

The magnet 154 is fixed on the upper portion of the base 155, and holds the leading end of the sheet 3 clamped by the sheet claw 151 in the closed position by its magnetic force. The base 155 includes a gripper 21 that swings open and close.
The notch 154a is formed at a plurality of places so that the paper claw 151, the stopper claw 153, and the peeling claw 152 do not interfere with each other. The extension spring 158 is connected to the arm 15.
9 near the cam follower 157 and the end plate 2 of the impression cylinder 20
0a is disposed between the pin 20b and the pin 20b.
The gripper 21 opens and closes according to the cam curve of the cam, but is closed by the urging force of the tension spring 158 when closing.

[0006] Due to the structure of the clamp device 150 described above, the gripper 21 is adapted to move the shaft 156 in accordance with the movement of the cam.
Swings and opens and closes with the fulcrum as a fulcrum. And the claw 21
A predetermined timing for clamping the leading end of the sheet 3 sent from the pair of registration rollers 33a, 33b by the cam, for example, the rotational position of the gripper 21 in the impression cylinder 20 shown in FIG. Paper holding position), and hold the leading edge of the paper 3 with the holding claws 21.
After being abutted against the stopper pawl 153, the leading end of the paper 3 is clamped by the paper pawl 151 of the holding pawl 21 so that the leading end of the paper 3 is a pair of upper and lower guide plates 38, 38 shown in FIGS. The gripper 21 is closed at a predetermined timing after exiting the downstream end. Next, the impression cylinder 20 rotates while holding the sheet 3 on the outer peripheral surface of the impression cylinder 20. When the impression cylinder 20 reaches the vicinity of the rotation position shown in FIG. And the leading end of the sheet 3 has passed through the nip portion N formed by pressing the outer peripheral surface of the plate cylinder 1 and the outer peripheral surface of the impression cylinder 20 via the master 2 and the paper 3. Then, the rotational position shown in FIG.
Paper discharge claw 44).
The gripper 21 is opened again at a position immediately before the operation, and the opening and closing operation is performed so as to send the printed sheet 3 to the sheet discharging and conveying device 49.

As described above, the gripper 2 of the impression cylinder 20
The rotation position of 1 changes sequentially from →→,
Since the leading end of the paper 3 is discharged at a position beyond the rotational position where the ink is transferred to the paper 3, the paper 3 does not wind up on the plate cylinder 1 due to the adhesive force of the ink. Such opening / closing timing of the gripping position of the gripper 21 at the rotation position of the impression cylinder 20 prevents a clamping error of the leading end of the paper 3 by the gripper 21 described later, and also enables the plate cylinder in the vicinity of the nip portion N. In order to prevent interference with the outer peripheral surface of the pair of guide plates 1, the guide plates are set as close as possible to the downstream ends of the pair of guide plates 38.

[0008]

However, the impression cylinder 2
If 0 rotates while holding the sheet 3 on the outer peripheral surface of the impression cylinder 20, the following problems and problems will occur. In FIG. 22, reference symbol A denotes the length of the leading edge margin of the sheet. 1
The distance to the paper 53 in the paper transport direction X of the printed paper 3 as shown in FIG.
Of the print image G on which the print image G is formed. The gripper 21 is designed to be laid out with the tip of the paper nail 151 as close as possible to the pressing point C in order to minimize the paper tip margin length A as much as possible. ), The paper transport speed V ′ when the leading end of the paper 3 collides with the stopper claw 153 of the gripping claw 21 (hereinafter, may be simply referred to as “contact”). Is slower than the peripheral speed V of the impression cylinder 20, the leading edge of the sheet 3 to be clamped by the gripper 21 is held before the outer peripheral surface of the plate cylinder 1 and the outer peripheral surface of the impression cylinder 20 are pressed. 21 or a gap is formed between the stopper claw 153 and the leading end of the paper 3, and the leading end position of the paper 3 with respect to the stopper claw 153 shifts.

When the leading edge of the paper 3 is completely removed from the gripper 21 and is not clamped as described above, the paper ejecting pawl 4 is held with the leading edge of the paper 3 stuck to the outer peripheral surface of the plate cylinder 1.
4 or the peeling claw 152, causing a jam called “discharge (paper) curling up” as described above, and even if the leading end of the paper 3 does not completely come out of the holding claw 21, the stopper claw 153 can be used. When the leading end position of the sheet 3 with respect to the sheet 3 is shifted, the positional accuracy (registration accuracy) of the print image G in the sheet transport direction X of the printed sheet 3 is deteriorated.

In order to solve the above-mentioned problem, the sheet conveying speed V ′ when the leading end of the sheet 3 comes into contact with the stopper claw 153 of the holding claw 21 is actually set to the impression cylinder 2 as described later.
By setting the peripheral speed V to be higher than the peripheral speed V of 0, for example, as shown in FIG. A paper transport speed control method (V ′> V) in which no force is exerted such that the leading end of the sheet No. 3 comes off.
When such a sheet conveyance speed control method (V ′> V) is adopted, the plate cylinder is pressed before the bent portion 3B generating portion near the leading end of the sheet 3 is pressed by the nip portion N as shown in FIG. 1
May come into contact with the master 2 on the outer peripheral surface of the master 3, which may cause a problem in that the bent portion 3 </ b> B of the paper 3 is stained by ink oozing from the master 2 on the master.

On the other hand, when the length A of the leading edge of the paper is to be reduced, the leading edge D of the paper pawl 151 projects outward from the outer diameter Da of the impression cylinder 20 and is wound around the outer peripheral surface of the plate cylinder 1. Since the leading end D of the paper pawl 151 comes into contact with the master 2 and hits the stencil master 2 of the same part every rotation, the stencil master 2 of the part is torn. When the master 2 having been made in this way is torn, the ink supplied to the outer peripheral surface of the plate cylinder 1 will protrude from the torn portion, and the protruding ink will contaminate the paper claw 151, and In order to prevent the tip D of the paper nail 151 of the gripper 21 from hitting the master 2 on the plate cylinder 1, the gripper 21 is attached to the tip of the paper nail 151. D is inclined to the center side of the impression cylinder 20 so that D falls within the outer diameter dimension Da,
Thus, the layout structure is such that the leading end of the sheet 3 is slightly bent toward the inside wound around the impression cylinder 20 and clamped.

When the leading end of the sheet 3 is bent toward the inside of the impression cylinder 20 and clamped by the structure of the gripper 21 as described above, the following problems occur. As shown in FIG. 22, when the relationship between the sheet conveying speed V ′ and the peripheral speed V of the impression cylinder 20 is V ′ ≦ V, the gripper 21 moves the leading end of the sheet 3 toward the inside of the impression cylinder 20. Even if the paper 3 is slightly bent and clamped, the paper 3 is held on the outer peripheral surface of the impression cylinder 20 and is conveyed to a position before the nip portion N between the outer peripheral surface of the plate cylinder 1 and the outer peripheral surface of the impression cylinder 20. However, from the above-described circumstances, the sheet conveying speed V ′ and the peripheral speed V of the impression cylinder 20 are V ′>
Since the relationship of V, that is, the relationship of the above-described paper conveyance speed control system (V ′> V), is satisfied, if the leading end of the paper 3 is slightly bent toward the inside of the impression cylinder 20 and is clamped, FIG. 3B, the vicinity of the leading end of the sheet 3 bends toward the outer peripheral surface of the plate cylinder 1 from the pressing point C as a starting point.
Generate The bending 3B is generated in this manner, and the nip N
Before the leading end portion of the sheet 3 reaches the nip portion N, the master 3 on the outer peripheral surface of the plate cylinder 1
Is transferred to the surface of the sheet 3 from the perforated portion of the master 2 that has been made. The length on the paper 3 in the paper transport direction X from the leading end of the paper 3 at the contact point with the stopper claw 153 to the point where the bending 3B of the paper 3 comes into contact with the stencil master 2 is near the leading end of the paper 3. When the flexure 3B is generated, the length of the paper 3 is slightly longer than when the paper 3 is conveyed while being held on the outer peripheral surface of the impression cylinder 20 without generating the flexure 3B. On the rear side (upstream in the paper transport direction X) of the print image formed by transferring the ink to the position, the portion near the leading end of the paper 3 where the bending 3B is generated as described above is the outer peripheral surface of the plate cylinder 1 There is a problem that ink stains are generated when the master 2 comes in contact with the master 2 having been made.

The clamp device 150 'shown in FIG. 25 is designed so that the tip D of the paper pawl 151 can be used even when a thick paper 3' such as a drawing paper, a thick paper (135 kg or more) or a postcard is clamped by the grippers 21. 24 so as not to come into contact with the master 2 on which the plate has been made.
Is laid out further inside the outer circumference dimension Da of the impression cylinder 20 than the layout of FIG. In addition,
The positional relationship between the gripper 21 and the pressing point C is exaggerated. In this case, since a step is generated between the upper surface of the magnet 154 of the gripper 21 and the pressing point C, the bending 3B 'starts from the pressing point C due to the waist of the thick paper 3'. Generated as described above with reference to FIG.

Therefore, the present invention has been made in view of the above-mentioned circumstances, and an impression cylinder having a gripper capable of carrying and printing while clamping the leading end of a sheet, that is, a so-called “paper gripping pressure”. In a stencil printing machine using the "cylinder method", the paper transport speed when the leading edge of the paper abuts the gripper is set faster than the peripheral speed of the impression cylinder, so that the gripper holds the leading edge of the paper. Even if a paper conveyance speed control method is used in which a bend is generated in the vicinity and a force such that the leading end of the paper comes out of the gripper does not work, the bending generation portion of the paper before reaching the nip portion is a master having a plate made. It is an object of the present invention to provide an improved stencil printing apparatus capable of preventing ink stains on paper by preventing the paper from coming into contact with paper.

[0015]

According to the first aspect of the present invention,
A plate cylinder for winding the master made on the outer peripheral surface, and an impression cylinder having a holding means for holding a leading end portion of the fed sheet and having an impression cylinder having substantially the same diameter as the outer diameter of the plate cylinder. In a printing apparatus for printing on the paper by pressing the impression cylinder relatively to the plate cylinder via the printing cylinder, before reaching a nip portion formed by the outer peripheral surface of the plate cylinder and the outer peripheral surface of the impression cylinder A sheet guide means for guiding the sheet so that the sheet portion before reaching the nip does not contact the master on the plate cylinder.

According to a second aspect of the present invention, in the printing apparatus according to the first aspect, a registration roller for feeding a leading end of the sheet toward the holding means is provided on the sheet transport path, and A pressure roller driving means for rotating the drum, and a registration roller driving means for rotating the registration roller, wherein the paper transport speed when the leading edge of the paper contacts the holding means is higher than the peripheral speed of the pressure drum. The speed is also set to be fast, and a bend is generated in the vicinity of the holding portion at the leading end of the sheet by the holding means.

According to a third aspect of the present invention, in the printing apparatus of the second aspect, the registration roller driving means is a stepping motor.

According to a fourth aspect of the present invention, in the printing apparatus according to the first, second or third aspect, a flexible member is provided at a downstream end of the paper conveying path of the paper guiding means. I do.

The "impression cylinder having substantially the same diameter as the outer diameter of the plate cylinder" in the first aspect of the present invention means that the outer diameter of the plate cylinder is the same as the outer diameter of the impression cylinder, and also that the outer diameter of the impression cylinder is the same as that of the impression cylinder. This includes cases where it is within the dimensional tolerance range.

According to the first aspect of the present invention, the printing is performed on the sheet by pressing the impression cylinder relatively to the plate cylinder via the sheet, and printing is performed by pressing the impression cylinder against the plate cylinder. There are a press cylinder contact / separation method for performing printing, a plate cylinder contact / separation method for performing printing by pressing the plate cylinder against the impression cylinder, and a combined method. Specific examples of the impression cylinder contact / separation method include an impression cylinder and a contact / separation unit thereof according to an embodiment of the invention described later. on the other hand,
As the plate cylinder contact / separation method, there is a well-known method in which the plate cylinder moves to the impression cylinder side (including a type in which an ink roller inside the plate cylinder projects to the impression cylinder side) to perform printing.

The holding means according to the first aspect of the present invention,
In addition to those described in the embodiments described below, examples having grip claws include the techniques described in FIGS. 1 and 2 of JP-A-5-201115.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention including embodiments (hereinafter, simply referred to as "embodiments") will be described below with reference to the drawings. Throughout the embodiments and the like, components having the same function, shape, and the like are denoted by the same reference numerals, and description thereof is omitted as much as possible. Components that are configured as a pair and do not need to be specifically distinguished and described in the drawings will be replaced with the description by appropriately describing one of them for the sake of simplification of description.

Embodiment 1 Hereinafter, a first embodiment of the present invention (hereinafter, simply referred to as “Embodiment 1”) will be described. The first embodiment includes an embodiment for solving the above-described problem of the present invention and includes another novel technology. Therefore, the new technology will be described first. This new technology has been made in view of the following circumstances of the prior art.

An example of a paper feed mechanism in a stencil printing apparatus and a method of transporting paper using the paper feed mechanism will be described with reference to the drawings. As shown in FIG. 15, the sheet feeding device 29 'in the stencil printing apparatus includes an elevator type sheet feeding table 31.
A call roller 30 and a paper feed roller 32 rotatably supported by a side plate (not shown); a separation roller 34 that presses against the paper feed roller 32 to prevent double feeding; A pair of registration rollers 33a and 33b for feeding at a predetermined timing between the outer peripheral surface of the cylindrical plate cylinder 1 and the press roller 40 as a pressing means, and a nip portion between the registration roller pair 33a and 33b and the plate It has a pair of guide plates 38 ′, 38 ′ for guiding between the outer peripheral surface of the drum 1 and the outer peripheral surface of the press roller 40.

The paper feed table 31 is driven by a driving device (not shown) so that the top of the loaded paper 3
The sheet 3 is moved up and down so as to come into contact with a predetermined pressing force (a pressing force at which the sheet 3 can be transported). On the left side of the paper feed table 31,
A paper feed front plate 35 is provided for abutting and aligning the leading ends of the paper 3 stacked on the paper feed table 31. Paper feed roller 32
A cam (not shown) rotating in synchronization with the plate cylinder 1, a sector gear having a cam follower engaged with the cam,
The one-way clutch is incorporated and the sector gear is rotated clockwise by a feed roller gear meshing with the sector gear. The call roller 30 and the paper feed roller 32 are connected by an endless belt 37 and have a driving force transmission relationship.

The pair of registration rollers 33a and 33b are rotatably supported by the side plate in front of (in downstream of) the sheet conveying direction X with respect to the separation roller 34. Registration roller pair 3
Similarly to the sheet feeding roller 32, the cams 3a and 33b shown in FIGS. 19 and 20 rotate in synchronization with the plate cylinder 1, a sector 51 swinging around a spindle 51b,
Cam follower 5 disposed at one end of the cam and engaged with the cam 50
3 and a sector gear 51 formed at the other end of the sector 51.
a, and a registration roller gear 54 in which the one-way clutch 52 is incorporated and meshes with the sector gear 51a, rotates the registration roller 33b below the pair of registration rollers 33a, 33b in a counterclockwise direction. The sheet feed speed of the pair of registration rollers 33a and 33b is set to be equal to the peripheral speed of the plate cylinder 1. Hereinafter, a method of feeding paper using the above-described sector gear 51a is referred to as a sector gear method.

In the vicinity of the lower portion of the plate cylinder 1, there is a press roller 40 as a pressing means which can freely contact and separate from the plate cylinder 1 via the master 2.
Are rotatably disposed at the free ends of the pair of roller arms 41, 41. The roller arm pair 41, 41 has a base end fixed to a support shaft 42 rotatably supported by the side plate, and a driving member such as a cam (not shown) attached to the end of the support shaft 42. Thereby, the free end is swung in accordance with the rotation of the plate cylinder 1. At the lower left of the plate cylinder 1, a paper discharge device 43 'is provided. Paper ejection device 43 '
Is a swingable peeling claw 49 for peeling the leading end of the paper 3 stuck to the master 2 on the plate cylinder 1 from the outer peripheral surface of the plate cylinder 1 by the adhesive force of the ink, and a printing peeled by the peeling claw 49. A transport belt 48 for adsorbing and transporting the completed paper 3 to a discharge tray (not shown), a transport roller front 46, and the like are provided.

Next, the procedure for transporting the sheet 3 will be described.

As shown in FIG. 15, the sheet 3 is fed by the call roller 30, and the sheet feed roller 32 and the separation roller 3 are fed.
4 prevents the sheet 3 from being double fed, and only the topmost sheet 3 is sent to the registration roller pair 33a, 33b.
When the leading end of the sheet 3 collides with the nip portion of the pair of registration rollers 33a and 33b, and is further conveyed, and a predetermined amount of curved bending 3A is formed upward as shown in FIG. The rotation with the roller 30 stops. Thereafter, the pair of registration rollers 33a, 33b is rotated at a predetermined timing by the operation of the cam 50 shown in FIGS. 19 and 20, and the bending 3A (shown by a broken line) of the sheet 3 disappears as shown in FIG. And one-way clutch 5
The paper 3 is conveyed between the outer peripheral surface of the plate cylinder 1 and the outer peripheral surface of the press roller 40 while the paper feed roller 32 and the call roller 30 are driven and rotated by the conveyance of the paper 3 by the operation of 6. By the rotation of the pair of registration rollers 33a and 33b, as shown in FIG. 18, the leading end of the sheet 3 is conveyed between the outer peripheral surface of the plate cylinder 1 and the outer peripheral surface of the press roller 40, and at the same time, the press roller 40 The stencil printing has been performed by the press roller 40 pressing the sheet 3 against the outer peripheral surface of the plate cylinder 1 as it rises.

However, the sector gear system described above has the following disadvantages.

(1) When the paper 3 is transported from the state shown in FIG. 17 to the state shown in FIG.
Although the paper feed roller 32 and the calling roller 30 are driven and rotated by the conveyance of the paper 3 by the operation of 6, the load is applied to the paper 3. Furthermore, since the separation roller 34 does not rotate, this also becomes a load on the paper 3, which increases the load on the paper 3. As a result, since the leading end of the paper 3 is free, the paper 3 is
There is a problem in that the slippage occurs between the nip portions b, and the positional accuracy (registration accuracy) in the paper transport direction X varies.

(2) When the paper 3 is transported, as shown in FIG. 15, the leading end of the paper 3 is
In order to stop once at the nip portion 33b, pressure is applied between the registration roller pair 33a and 33b by a spring (not shown). The rotation of the pair of registration rollers 33a and 33b must be stopped until the next sheet 3 is conveyed.
The brake is applied to the drive mechanism of the lower registration roller 33b, which is the driving side, so that the pair of registration rollers 33a, 33b immediately stops rotating after the reciprocation of 1a. The cam 50 for moving the sector gear 51a is a plate cylinder 1
Since the driving force is obtained from the main motor on the side and the pair of registration rollers 33a and 33b are constantly braked as described above, the load on the main motor increases and the power of the main motor increases. There was a problem that it had to be taken.

On the other hand, the above-described paper holding impression cylinder method has the following disadvantages. In a conventional printing apparatus using the paper holding impression cylinder method, for example, as in a stencil printing apparatus disclosed in Japanese Patent Application No. 8-25194 proposed by the present applicant, a rotary drive between the plate cylinder and the impression cylinder is used. Since the transmission system is via a vertical adjustment mechanism consisting of many components, and because it is a long-path rotary drive transmission system connected to the main motor, a paper-holding impression cylinder method has been adopted. However, due to the backlash of the gear train of the vertical adjustment mechanism or the loosening or extension of the timing belt, the transport timing of the paper 3 from the pair of registration rollers 33a, 33b with respect to the paper holding clamper (also called a holding claw) is slightly shifted. As a result, there is a problem that the paper 3 is wound up.

In order to solve the above-mentioned problems, the applicant of the present application has proposed a novel technique relating to paper feed control in a printing apparatus using a paper holding cylinder system, as disclosed in Japanese Patent Application No. 9-1455.
No. 18 and Japanese Patent Application No. 9-310716. This new technique will be briefly described with reference to FIGS. 4, 5 and 7. A timing detecting means (light-shielding means) for setting the timing for feeding the leading end of the sheet 3 to the gripper 21 of the impression cylinder 20 will be described. The plate 106 and the photo sensor 107) are
Side, and controls the stepping motor 102 below the registration roller to feed the leading end of the sheet 3 in accordance with the output signal from the photo sensor 107 in synchronization with the rotation position of the holding claw 21 (sheet holding position). And a control device 110 as a registration roller drive control means. The above-described technique is based on the configuration shown in FIGS.
And the control device 1 is replaced with the control device 111.
This roughly corresponds to a control configuration having 10.

However, the above technique has the following disadvantages to be improved. This will be described with reference to FIGS. 12 and 13. When the leading end of the sheet 3 is sent from the pair of registration rollers 33a and 33b, the impression cylinder 20 is driven by the driving force transmission mechanism of the main motor as described above.
By swinging and displacing each sheet of paper and pressing against the outer peripheral surface of the plate cylinder 1, the load fluctuates and the speed fluctuation increases until the outer peripheral surface of the plate cylinder 1 is pressed. As a result, the leading end of the sheet 3 is held by the holding claws 21. That is, since the peripheral speed of the outer periphery of the impression cylinder 20 is constantly fluctuating, the light shielding plate 10
6 is detected by the photo sensor 107 only,
In the above-described paper feeding control method in which the registration roller lower stepping motor 102 is driven and controlled so that the leading edge of the paper 3 is fed in synchronization with the paper gripping position of the gripper 21, the gripper 21 is securely connected to the gripper 21. In addition, it is difficult to completely eliminate clamping errors.

Accordingly, this new technique has been made in order to solve the above-mentioned disadvantages.
The first object is to provide a pulse encoder for detecting at least the rotational speed fluctuation in the impression cylinder on the impression cylinder side for controlling the timing of feeding the leading edge of the sheet to the holding means. Eliminating clamping errors in the gripping claws on the drum, preventing paper roll-up, etc., more reliably, stabilizing the timing of feeding the leading edge of the paper to the holding means, and improving reliability. Another object of the present invention is to provide a printing apparatus capable of further improving the registration accuracy. The second purpose is the first
In addition to the purpose of the above, the registration roller is driven by controlling the driving of the registration roller driving means to feed the leading edge of the sheet in synchronization with the rotation position of the holding means based on the output pulse signal from the encoder sensor. In addition to reducing the load on the drive system by making the drive system independent of the main motor that drives the plate cylinder and pressing means (press cylinder, etc.),
An object of the present invention is to provide a printing apparatus which can be manufactured at low cost by reducing the power of a main motor.

A third object is that, in addition to the second object, the registration roller driving means is constituted by a stepping motor, thereby eliminating the need for mechanical parts for regulating the registration roller and the rotation direction, thereby reducing the cost. An object of the present invention is to provide a printing apparatus in which a program of a control device can be simplified, and a calculation process is speeded up and tracking accuracy of feedback control is increased. A fourth objective is to use the first, second or third
In addition to the above-mentioned purpose, the timing for feeding the leading edge of the sheet to the holding means is arranged on the impression cylinder side to stabilize the feeding timing.
An object of the present invention is to provide a printing apparatus capable of improving reliability.

A fifth object is to provide, in addition to the first object, paper feed timing detecting means for determining the timing of feeding the leading edge of the paper to the registration roller on the impression cylinder side. It is an object of the present invention to provide a printing apparatus capable of stabilizing feeding timing and improving reliability. The sixth purpose is
In addition to the second or third object, the paper feed timing detecting means for determining the timing for feeding the leading edge of the paper to the registration roller is provided on the impression cylinder side, thereby stabilizing the paper feed timing. -To provide a printing apparatus capable of improving reliability.

The above-mentioned new technology has the following technical configuration. The first technical configuration is the first technical configuration described above.
In order to achieve the object of (1), a plate cylinder for winding the master made on the outer peripheral surface and holding means for holding the leading end of the fed sheet are provided with a pressure substantially equal to the outer diameter of the plate cylinder. Having a cylinder, in a printing apparatus that performs printing by pressing the impression cylinder relatively to the plate cylinder, for controlling the timing of feeding the leading end of the sheet to the holding unit,
A pulse encoder for detecting at least rotation speed fluctuation in the impression cylinder is provided on the impression cylinder side. As pulse encoders, there are an incremental type that detects the relative rotation amount that can detect rotation speed fluctuations, and an absolute type that detects an absolute rotation amount that can detect rotation speed fluctuations and position detection. is there. Since the pulse encoder according to the first aspect detects at least the rotational speed fluctuation in the impression cylinder, it includes both an incremental type and an absolute type. As the pulse encoder, a photo encoder is preferable in terms of stabilizing the detection performance and improving the reliability, but a magnetic encoder or the like may be used if this is not required. "Impression cylinder side" means, in the impression cylinder contact / separation method, the side of the impression cylinder that also includes a member that is displaced substantially synchronously with the displacement operation of the impression cylinder itself or the plate cylinder. Say. In the case of the plate cylinder contact / separation method, it refers to the impression cylinder itself including the impression cylinder itself or the apparatus main body near the impression cylinder.

According to a second technical configuration, in order to achieve the second object described above, in the first technical configuration, a registration roller that sends out the leading edge of the sheet toward the holding unit and a rotation of the registration roller are changed. Registration roller driving means, and the pulse encoder comprises an encoder provided on the impression cylinder and an encoder sensor provided in the vicinity of the encoder, and based on an output pulse signal from the encoder sensor, A registration roller drive control unit for controlling the drive of the registration roller drive unit so as to feed the leading edge of the sheet in synchronization with the rotation position. As a specific example of the registration roller drive control means, a microcomputer or a microprocessor is preferably used.

According to a third technical configuration, in order to achieve the third object described above, in the second technical configuration, the registration roller driving unit includes a stepping motor and corresponds to one pulse width of the pulse encoder. The amount of movement of the outer periphery of the impression cylinder is set to be the same as the amount of sheet feeding by which the stepping motor sends the sheet in one pulse. According to a fourth technical configuration, in order to achieve the above-described fourth object, in the first, second, or third technical configuration, a timing for setting a timing for feeding the leading edge of the sheet to the holding unit is provided. The detection means is arranged on the impression cylinder side.

According to a fifth technical configuration, in order to achieve the fifth object described above, in the first technical configuration, there is provided a registration roller for sending out the leading edge of the sheet toward the holding means, A sheet feed timing detecting means for determining a timing for feeding the leading edge of the sheet to the impression cylinder side. According to a sixth technical configuration, in order to achieve the sixth object described above, in the second or third technical configuration, a paper feed timing for setting a timing for feeding the leading edge of the sheet to the registration roller is provided. The detection means is arranged on the impression cylinder side.

Specific examples of the timing detecting means in the fourth technical configuration and the paper feed timing detecting means in the fifth and sixth technical configurations include a transmission type optical sensor in terms of stabilization and reliability of the detecting operation. (Photo interrupter type photo sensor) and a light shielding member are preferably used. If the stabilization and reliability of the detection operation do not need to be so desired, a reflection type optical sensor or the like or a microswitch having a mechanical contact may be used.

FIG. 4 shows a stencil printing apparatus as an example of a printing apparatus. This stencil printing apparatus includes a cylindrical plate cylinder 1 for winding a stencil master 2 around an outer peripheral surface, and a stencil writing device 19 disposed to the right of the plate cylinder 1 for stencil making and transporting the stencil 2.
And an ink supply device 28 disposed inside the plate cylinder 1 to supply ink to the master 2 on the plate cylinder 1, and a leading end of the fed sheet 3 disposed below the plate cylinder 1 and fed. An impression cylinder 20 provided with a gripper 21 as a holding means for holding and holding, and pressing the master 2 on the outer peripheral surface of the plate cylinder 1 through the paper 3;
The paper feeding device 29 includes a paper feeding device 29 disposed on the right side of the impression cylinder 20 and feeds the paper 3 to the holding claws 21 of the impression cylinder 20, and a paper discharge device 43 disposed on the left side of the impression cylinder 20. I have. The plate cylinder 1 is shown in FIG.
As shown in the figures, the cylindrical body has a porous structure and a plurality of layers of mesh screens (not shown) wound around the outer peripheral surface thereof, and is rotatably supported around the shaft pipe 11.
The plate cylinder 1 is rotated by a main motor 60 also serving as an impression cylinder driving unit via a drive system (not shown). This main motor is composed of, for example, a DC motor and does not transmit a driving force to a paper feed drive system as described later, so that it is smaller than a conventional main motor. On the outer peripheral surface of the plate cylinder 1, a master clamper 12 for holding the leading end of the master 2 punched and made by the plate making / writing device 19 is arranged. The master clamper 12 faces a stage (not shown) made of a ferromagnetic material provided along a generatrix on the outer peripheral surface of the cylindrical body, and is rotatably supported via a clamper shaft. It is configured such that magnets are adhered to opposing surfaces. When the plate cylinder 1 occupies a predetermined rotation position, the master clamper 12 is opened and closed by transmitting a driving force by an opening / closing device (not shown).

The plate making / writing device 19 includes a support shaft 10b for supporting the master 2 so as to be able to be fed out from a master roll 10 formed by being wound in a roll shape around a core tube 10a, and a master 2
Roller 9 that conveys the paper, a thermal head 17 that is provided to be able to contact and separate from the platen roller 9, a pair of upper and lower cutter members 4 that are provided downstream of the platen roller 9 and cut the master 2, 2 mainly includes plate feed roller pairs 5a and 5b for sending the leading end of the plate 2 toward the master clamper 12. The platen roller 9 has its shaft rotatably supported, is driven to rotate at a predetermined peripheral speed by a pulse motor 6, and conveys the master 2 while pressing it against a thermal head 17. The thermal head 17
The master 2 has a plurality of heating elements arranged in a row in the width direction of the master 2, and is provided so as to be able to freely contact and separate from the platen roller 9 by a well-known contact and separation mechanism (not shown). The thermal head 17 is provided with a document reading unit A for reading a document (not shown).
The master 2 has a function of selectively perforating the master 2 based on a digital image signal processed and transmitted by the / D conversion unit and the plate making control unit to form a perforated image. The upper cutter member 4 is moved up and down by an eccentric cam 8 rotated by a cutter drive motor 7 to cut the master 2.

The ink supply device 28 rotates in synchronization with the plate cylinder 1 in the same direction, and supplies ink to the inner peripheral surface of the plate cylinder 1 in parallel with the ink roller 13 with a slight gap. And a doctor roller 15 that forms an ink reservoir 16 with the ink roller 13, and a shaft pipe 11 that supplies ink to the ink reservoir 16.
The ink roller 13 and the doctor roller 15 are connected to the shaft pipe 1.
Each is rotatably supported by a side plate fixed to 1. The ink supplied from the ink reservoir 16 to the outer peripheral surface of the ink roller 13 is supplied to the inner peripheral surface of the plate cylinder 1 because a slight gap is provided between the plate cylinder 1 and the outer peripheral surface of the ink roller 13. . The ink is pumped by an ink pump from an ink pack disposed at an appropriate position, and is supplied to the shaft pipe 11.
Is supplied to the ink reservoir 16 through the supply hole.

In the first embodiment, as described in the related art, the gripper 2 is used as a pressing means for the purpose of winding up the discharged paper, improving registration accuracy of the paper 3 and reducing noise.
1 is used. The support structure of the impression cylinder shaft 23 by the arm pairs 25a and 25b shown in FIGS.
The illustration of the locking structure 26b is simply shown.

The end plates 20a at both ends of the impression cylinder 20 are fixedly supported by an impression cylinder shaft 23 as shown in FIGS. A bearing support portion 25 is provided outside the both end plates 20a of the impression cylinder 20.
A pair of arms 25a and 25b each having a cam follower 27 composed of a bearing c and a bearing are provided. These pairs of arms 25a and 25b are provided with an impression cylinder shaft 23.
Are rotatably supported via bearings 23A mounted on both ends of the impression cylinder shaft 23, respectively. Thereby, the impression cylinder 20 is rotatable because both ends of the impression cylinder shaft 23 are rotatably supported by the bearing support portions 25c via the respective bearings 23A. Arm pair 25
One end of one arm 25a of each of the first and second arms 25a and 25b is connected to a fulcrum shaft 24 fixed to a pair of one side plates (not shown) of the apparatus main body.
a through a bearing (not shown), and one end of the other arm 25b is supported by a fulcrum shaft 24b rotatably supported by the other side plate via a bearing (not shown). ing. The two fulcrum shafts 24a and 24b are disposed coaxially with the arm pairs 25a and 25b.

A drive gear (not shown) for transmitting rotation to the impression cylinder 20 is fixed to the inner end side of the fulcrum shaft 24b rotatably supported by the other arm 25b.
An impression cylinder gear (not shown) that meshes with the drive gear is fixed to the impression cylinder shaft 23 on the 5b side. A toothed impression cylinder pulley (not shown) for transmitting the rotational force of the plate cylinder 1 is fixed to the outer end side of the fulcrum shaft 24b. A toothed belt (not shown) is provided between the fixed end plate and a toothed plate cylinder-side pulley attached to the end plate.
Is wrapped around. On the other hand, on the end plate of the plate cylinder 1,
Another pulley is mounted coaxially with the plate cylinder side pulley. Thereby, the rotational force of the main motor 60 is transmitted to the another pulley via the toothed belt, and the plate cylinder side pulley, the toothed belt, the impression cylinder side pulley,
By being transmitted to the drive gear and the impression cylinder gear, the impression cylinder 20 rotates counterclockwise at the same peripheral speed as the peripheral speed of the plate cylinder 1 so that the pressing position with the plate cylinder 1 is the same. Rotated in the direction.

The outer peripheral portion of the impression cylinder 20 has a cylindrical portion that contacts the outer peripheral surface of the plate cylinder 1 and the master clamper 12 of the plate cylinder 1.
In order to avoid collision with the concave portion, a concave portion 22 concaved in a D-shape is formed. To put it concretely, the impression cylinder 20 is made of synthetic resin for its main body to reduce the weight, and nitrile rubber is wrapped around the outer periphery of the cylindrical part. Rotation unevenness is reduced. Impression cylinder 20
In the concave portion 22 of the impression cylinder 20, a clamper device 150 having a holding claw 21 for clamping the leading end of the sheet 3 is disposed in the concave portion 22 of the impression cylinder 20 as shown in detail in FIG.
The structure and operation of the clamper device 150 are the same as those described in detail in the related art, and a description thereof will be omitted to avoid redundant description. 4 and 21, the holding claws 21 are shown only in a somewhat simplified manner, and the detailed structure of the clamper device 150 including FIGS. 5 and 14 is omitted.

When the paper 3 is plain paper, thin paper, or the like, the paper clamper 21 holds the front end of the paper 2 up to about 2 mm from the front end of the paper 3 so that the paper 3 is moved around the outer periphery of the impression cylinder 20. Held on the surface. On the other hand, when the paper 3 is a thick paper or the like, the paper clamper 21 is not completely closed due to the clamping reaction force caused by the large stiffness of the paper 3 during clamping, and the leading end of the paper clamper 21 is not closed. In order to prevent the ink from splashing on the master 2 or the mesh screen on the outer peripheral surface of the plate cylinder 1, the paper 3 may be controlled so as to rotate and convey the paper 3 without touching the leading end of the paper 3. .

The impression cylinder 20 is configured to be able to freely contact and separate from the outer peripheral surface of the plate cylinder 1 by contacting / separating means described later. The contact / separation means includes an arm pair 25a, 25b that swings the impression cylinder 20 about the fulcrum shafts 24a, 24b, and an arm pair 25a,
A pair of cam followers 27, 27 each composed of a bearing rotatably supported at the other end of 25b, a pair of printing pressure springs 26a, 26b for urging the pair of arms 25a, 25b toward the plate cylinder 1, and a pair of Cam follower 27,
27 and a pair of cams (not shown) that selectively contact each other.

The pair of cams are connected to the plate cylinder 1 and the main motor 60 by a toothed belt (not shown).
The rotation is performed in synchronization with the rotation of the plate cylinder 1.
The pair of cams are connected to the master clamper 12 of the plate cylinder 1.
The contour peripheral surface is formed so as to slidably contact the pair of cam followers 27, 27 so that the outer peripheral portion except the concave portion 20a of the impression cylinder 20 presses against a predetermined printing opening region excluding the disposition portion. . When the paper 3 is erroneously conveyed or when making a plate, the pair of cams and the pair of cams are actuated by the operation of a printing pressure release mechanism provided with a pressure release solenoid (not shown) provided on the apparatus main body on the impression cylinder 20 side. Cam follower 27,2
The printing cylinder 1 is released by releasing the printing pressure so that the printing cylinder 7 does not slide.
And the impression cylinder 20 are separated from the plate cylinder 1 without being pressed against the plate cylinder 1.
The impression cylinder 20 holding the pair of printing pressure springs 26a, 26
6 b presses against the outer peripheral surface of the plate cylinder 1. As described above, the impression cylinder 20 causes the fulcrum shaft 2 to rotate by the operation of the printing pressure release mechanism and the rotation of the pair of cams.
A position pressed against the plate cylinder 1 around 4a, 24b;
It is brought into contact with and separated from a position separated from the plate cylinder 1.

The printing pressure springs 26a and 26b are
0 is applied to the plate cylinder 1 to generate a printing pressure. Impression cylinder 2
In order to uniformly apply the pressing force to the plate cylinder 1 of zero, printing pressure springs 26a and 26b are attached to each of the arm pairs 25a and 25b at both ends of the impression cylinder 20, respectively. The detailed configuration of the drive system including the above-described main motor 60 and the above-mentioned contact / separation means is described in, for example,
The same components as those shown in FIGS. 1 to 5 of 216448 are used.

A plate discharging device 18 is provided on the left side of the plate cylinder 1. The plate discharging device 18 separates the used master 2 already wound on the plate cylinder 1 from the outer peripheral surface of the plate cylinder 1. And store it.

In the vicinity of the left side of the impression cylinder 20, a paper discharge device 43 is disposed. The paper discharging device 43 is different from the conventional paper discharging device 43 ′ shown in FIG. 15 and the like only in that it has a paper discharging claw 44 for peeling and guiding the printed paper 3 instead of the peeling claw 49. . The paper discharging device 43 includes a paper discharging claw 44 and a transport belt 48 stretched between a front of a transport roller 46 and a rear of a transport roller 47 for transporting the sheet 3 peeled and guided by the paper discharge claw 44 and suction. It is composed of a fan (not shown). The transport belt 48 is set to be driven by a motor or the like at a transport speed higher than the peripheral speed of the plate cylinder 1. On the left side of the paper discharge device 43, a paper discharge table 45 for stacking the discharged paper 3 is provided.

On the right side of the impression cylinder 20, a paper feeder 29 is disposed. The sheet feeding device 29 is different from the conventional sheet feeding device 29 ′ shown in FIG.
And a main motor 60 instead of the sector gear system which is the conventional driving system for the pair of registration rollers 33a and 33b. And a registration roller independent driving system rotated by a registration roller lower stepping motor 102 that is independent of the rotation driving force of the pair of guide plates 38 ′ and 38 ′ instead of the pair of guide plates 38 ′ and 38 ′. Having a pair of guide plates 38, 38 for guiding the leading end of the sheet 3;
A sheet for guiding the sheet 3 so that a bend 3B shown in FIG. 2 which is a sheet portion before reaching a nip formed by the outer peripheral surface of the platen 1 and the outer peripheral surface of the impression cylinder 20 does not contact the master 2 on the plate cylinder 1. The main difference is that a guide member 160 as guide means is newly provided.

As described above, in the first embodiment, the pair of registration rollers 33a and 33b feeds the leading end of the sheet 3 at a predetermined timing toward the holding claw 21 of the impression cylinder 20 occupying a predetermined rotation position. It is configured. The distance from the nip between the pair of registration rollers 33a and 33b to the nip between the impression cylinder 20 and the plate cylinder 1 is predetermined so as to be always constant.

The feed roller stepping motor 100 is
It has a function as a feed roller driving unit that rotates the feed roller 32. Paper feed roller stepping motor 100
Is a toothed endless belt 10 stretched between a drive pulley provided on the output shaft of the feed roller stepping motor 100 and a feed pulley provided on the shaft of the feed roller 32.
1, and is connected to a paper feed roller 32. Thus, the paper feed roller 32 is rotated clockwise by the rotation of the paper feed roller stepping motor 100. A one-way clutch (not shown) is incorporated in each shaft of the feed roller 32 and the call roller 30 so that the feed roller 32 and the call roller 30 rotate only in the clockwise direction.

Registration roller lower stepping motor 10
Reference numeral 2 has a function as registration roller driving means for rotating the registration roller 33b. The registration roller lower stepping motor 102 is provided with a toothed endless belt 103 wound between a driving pulley provided on the output shaft of the registration roller lower stepping motor 102 and a registration pulley provided on the shaft of the registration roller 33b. Via the registration roller 33b.

The registration pulley and the registration roller 33
A registration roller electromagnetic clutch 122 for connecting and disconnecting the rotational driving force of the registration roller lower stepping motor 102 is interposed between the shaft b and the shaft b. When the registration roller electromagnetic clutch 122 is turned on, the registration pulley is connected to the shaft of the registration roller 33b, and the rotational driving force of the registration roller lower stepping motor 102 is transmitted to the registration roller 33b. Accordingly, the registration roller 33b is rotated in the counterclockwise direction, and the registration roller 33a is driven to rotate in the clockwise direction via the conveyance of the sheet 3. Registration roller electromagnetic clutch 12
When 2 is turned off, the connection between the registration pulley and the shaft of the registration roller 33b is disconnected, and the rotational driving force of the registration roller lower stepping motor 102 is not transmitted to the registration roller 33b.

As shown in FIGS. 1 and 4, the guide member 160 is formed in a plate shape from a steel plate or a synthetic resin such as ABS resin (ABS) or polycarbonate resin (PC). The bent portion 3B is formed to have an appropriate thickness such that permanent deformation is not caused by an external force enough to contact and press the generated portion. The guide member 160 is located on the sheet transport path R before reaching the nip portion, and is provided between the master clamper 12 protruding outward from the outer peripheral surface of the plate cylinder 1, the outer peripheral surface of the plate cylinder 1, and the outer peripheral surface of the impression cylinder 20. It is provided at a position where it does not touch. Also, the opening timing position of the holding claw 21 is
The guide member 160 is set at a position upstream of the rotation of the impression cylinder 20 that does not contact the guide member 160.
Is set at the rotational position of the impression cylinder 20 between the downstream end of the paper transport path R of the first paper path and the downstream end of the paper transport path R of the lower guide plate 38. As will be described later, the gripper 21 clamps and closes the leading end of the paper 3 at a predetermined timing after the leading end of the paper 3 has exited the downstream end of the pair of upper and lower guide plates 38, 38 in the paper transport path R. The impression cylinder 20 conveys the paper 3. At this time, the guide member 160 is moved immediately before the leading end of the paper 3 is pressed by the nip between the outer peripheral surface of the plate cylinder 1 and the outer peripheral surface of the impression cylinder 20. Up to the leading end of the sheet 3. The size of the guide member 160 in the width direction orthogonal to the paper transport direction X is set slightly larger than the maximum paper size (for example, A3 size) used in the stencil printing apparatus.

Referring to FIG. 4 to FIG.
The control configuration related to the paper feed control of the stencil printing apparatus in the above will be described. As shown in FIG. 4 and FIG. And each is attached with a screw. Each of the light-shielding plates 105 and 106 is made of, for example, a sheet metal or a synthetic resin, has an L-shape in a front view and a side view, and has a tip protruding forward. On the other hand, a photo interrupter type photo sensor 104 and a photo sensor 107 are attached to the inner side wall of the arm 25a at predetermined intervals in the radial direction of the impression cylinder 20 by screws. The photo sensor 104 and the photo sensor 107 are
This is a known light transmission type optical sensor including a light emitting unit and a light receiving unit.

The light shielding plate 105 and the photo sensor 104
The impression cylinder 20 is attached so as to selectively engage and shield light only at a predetermined rotation position rotated in the counterclockwise direction,
It has a function as sheet feed timing detecting means for setting the timing for feeding the leading end of the sheet 3 to the pair of registration rollers 33a and 33b. The light-shielding plate 105 is attached to the end plate 20a of the impression cylinder 20 when the rear end of the A3 size paper 3 passes through the nip of the pair of registration rollers 33a and 33b, and engages with the photo sensor 104 to turn on the output. A signal is generated, and the paper feed roller stepping motor 100 is driven to rotate so that the paper feed roller 32 is rotated. At this time, as will be described later, the registration roller electromagnetic clutch 122 is turned off, and the registration roller 33b is controlled so as not to rotate in the counterclockwise direction and to remain stopped.

The light shielding plate 106 and the photo sensor 107
The impression cylinder 20 is attached so as to selectively engage and shield light only at a predetermined rotation position rotated in the counterclockwise direction,
The registration roller electromagnetic clutch 122 is turned on and has a function as timing detection means for determining the timing for starting feeding of the leading end of the sheet 3 toward the holding claws 21 of the impression cylinder 20. The position at which the light shielding plate 106 is attached to the end plate 20a of the impression cylinder 20 is determined by the distance on the paper transport path R from the nip portion of the pair of registration rollers 33a, 33b until the leading end of the paper 3 abuts on the gripper 21 and the light shielding plate. 106 is an impression cylinder 20 that is engaged with the photosensor 107 to generate an ON output signal.
From the rotation position of the paper 3, and hold the leading edge of the paper 3 with the holding claw 2
1 is located at a position where the distance on the outer peripheral surface of the impression cylinder 20 reaches the same distance. As a result, the feed amount of the paper 3 and the rotational movement amount of the impression cylinder 20 can always be controlled to be the same, and the leading edge of the paper 3 abuts against the gripping claws 21 at exactly the right timing to reliably grip the paper. Can be clamped.

As shown in FIG. 5 and FIG.
In the rear end plate 20a, two spacers 123 are provided.
, An encoder 120 is attached with a screw 124. The encoder 120 is an incremental-type photo encoder in the first embodiment, and is a one-channel photo encoder in which a number of slits are radially arranged on an outer peripheral portion. On the other hand, an encoder sensor 121 is attached to the inner wall of the arm 25b in the vicinity of the encoder 120 with a screw or the like sandwiching the outer periphery of the encoder 120. The encoder 120 and the encoder sensor 121 function as a pulse encoder for detecting a rotation speed fluctuation in the impression cylinder 20 for controlling the timing of feeding the leading end of the sheet 3 to the holding claws 21 of the impression cylinder 20. have. The amount of movement of the outer periphery of the impression cylinder 20 corresponding to one pulse width of the encoder 120 is set to be the same as the sheet feed amount by which the registration roller lower stepping motor 102 sends the sheet 3 in one pulse.

In FIG. 7, reference numeral 111 denotes a control device for controlling the paper feed of the stencil printing apparatus according to the first embodiment. The control device 111 includes a CPU (not shown).
(Central processing unit), an I / O (input / output) port, a ROM (read-only storage device), a RAM (read-write storage device), a timer, and the like. Consists of a computer.

The CPU of the control device 111 (hereinafter simply referred to as “control device 111” for simplicity of description) is electrically connected to the photo sensor 104 via the input port. And the photo sensor 104
And an output signal for rotationally driving the sheet feeding roller stepping motor 100 and the registration roller lower stepping motor 102 is received. The control device 111 is electrically connected to the photo sensor 107 through the input port, and receives an output signal for turning on the registration roller electromagnetic clutch 122 from the photo sensor 107. The control device 111 is electrically connected to the encoder sensor 121 via the input port, and receives an output pulse signal related to the rotation speed fluctuation of the impression cylinder 20 from the encoder sensor 121. The controller 111 controls the feed roller stepping motor 100 via the output port.
And electrically connects the leading edge of the sheet 3 to the pair of registration rollers 3 based on an output signal from the photosensor 104.
It has a function of controlling the drive of the sheet feeding roller stepping motor 100 so as to feed the sheets 3a and 33b. The control device 111 is electrically connected to the registration roller electromagnetic clutch 122 via the output port, and has a function of controlling the activation of the registration roller electromagnetic clutch 122 based on an output signal from the photosensor 107. The control device 111 is electrically connected to the registration roller lower stepping motor 102 via the output port, and adjusts the timing to the paper holding position of the holding claw 21 based on the output pulse signal from the encoder sensor 121. It has a function as registration roller drive control means for controlling the drive of the registration roller lower stepping motor 102 to feed the leading end of the sheet 3.

In the ROM in the control device 111, the control operation contents of the timing chart shown in FIG. 8 obtained in advance by experiments and the like are stored in advance. ROM above
A value obtained by converting a constant distance from the nip portion of the registration roller pair 33a, 33b to the nip portion between the impression cylinder 20 and the plate cylinder 1 into the number of pulses of the registration roller lower stepping motor 102 is stored in advance as data. I have. The RAM in the control device 111 temporarily stores the calculation result of the CPU, and stores the photo sensor 104 and the photo sensor 10
7 or an output pulse signal from the encoder sensor 121 is stored as needed to input and output these signals.

The operation of the stencil printing apparatus configured as described above will be described. When the document is set on the document reading unit and the start button is pressed, the plate cylinder 1 is rotated, and the used master is peeled off from the outer peripheral surface of the plate cylinder 1 by the plate discharging device 18 and discarded. Thereafter, the plate cylinder 1 stops at a position where the master clamper 12 occupies the plate feeding position located substantially to the right in FIG. 4, and the clamper shaft is rotated,
The master clamper 12 is opened to enter a plate feeding standby state.

Next, when the pulse motor 6 is driven, the platen roller 9 starts to rotate, and the master 2 is conveyed while being fed out. On the other hand, when a scanner (not shown) operates in the document reading section, an image of the document is read, and the digital image signal is processed and sent out by the A / D conversion section and the plate making control section. The seventeen heating elements are selectively heated, and the master 2 is selectively heated and pierced according to the image information.

The master 2 is conveyed by the rotation of the platen roller 9, and the leading end of the master 2 is sent out to the master clamper 12 which is expanding in a plate feeding standby state. When the number of steps of the pulse motor 6 reaches a certain set value, the clamper shaft is rotated to close the master clamper 12 so that the leading end of the master 2 having been made the master clamper 1
It is pinched by 2.

At the same time as this clamping operation, the plate cylinder 1 and the impression cylinder 2
0 is rotated at substantially the same peripheral speed as the transport speed of the master 2, and the master 2 having been made is wound around the outer peripheral surface of the plate cylinder 1. When the master 2 having been made is wound on the outer peripheral surface of the plate cylinder 1 for a predetermined length, the rotation of the plate cylinder 1, the impression cylinder 20, and the platen roller 9 is stopped. Simultaneously with this stopping operation, the cutter drive motor 7 is rotated, and the eccentric cam 8 lowers the upper cutter member 4 to cut the master 2. Then, the plate cylinder 1 is again rotated in the clockwise direction, and the rear end (not shown) of the cut master 2 is pulled out from the plate making / writing device 19, and the master 2 having completed the plate making is completely formed on the outer peripheral surface of the plate cylinder 1. It is wound up.

Next, the procedure for transporting the sheet 3 will be described with reference to FIGS. As shown in FIGS. 8 and 9, when the impression cylinder 20 rotates counterclockwise and the light shielding plate 105 passes through the photo sensor 104, an ON output signal is input to the control device 111, and the sheet feeding roller stepping is performed. The motor 100 is driven to rotate. As a result, the paper feed roller 32 is rotated in the clockwise direction, and at the same time, the paper 3 is fed by the rotation of the call roller 30 in the same direction. Thus, only the uppermost sheet 3 is sent to the pair of registration rollers 33a and 33b. Then, when the leading end of the sheet 3 collides with the nip portion of the pair of registration rollers 33a and 33b and is further conveyed, and a predetermined amount of curved bending 3A is formed upward as shown in FIGS. The paper roller 32 and the call roller 30 stop.

The feed amount of the paper 3 at this time is the feed amount obtained by adding +5 to 6 mm to the distance on the paper transport path R between the nip portion of the pair of registration rollers 33a and 33b and the paper feed front plate 35. It is set as follows. In the control device 111,
Paper feed roller stepping motor 1 corresponding to the feed amount
By performing a calculation for converting the number of steps into a number corresponding to the above-mentioned feed amount so as to drive-control 00, and sending a command signal to the feed roller stepping motor 100, the bending deflection 3
The paper 3 is fed by the paper feed roller 32 as long as A is formed. When the light shielding plate 105 passes through the photo sensor 104, the registration roller lower stepping motor 102 is driven to rotate, and at this time, the registration roller electromagnetic clutch 122 is turned off.
b stops without rotating.

Next, the gripper 21 of the impression cylinder 20 is
Open at a predetermined timing shown in FIG. As shown in FIGS. 8 and 11, the impression cylinder 20 further rotates counterclockwise,
When the light shielding plate 106 passes through the photo sensor 107 at a predetermined timing, an ON output signal thereof is input to the control device 111, and the registration roller electromagnetic clutch 122 is turned on. Along with this, the rotation of the registration roller lower stepping motor 102 rotates the registration roller 33 b in a counterclockwise direction, and starts feeding the leading end of the sheet 3 toward the holding claw 21 of the impression cylinder 20. At this time, the control device 111
Is controlled to rotate the registration roller 33b at the same peripheral speed as the peripheral speed of the impression cylinder 20 by using the registration roller lower stepping motor 102 to rotate the registration roller 33b at the same peripheral speed as the peripheral speed of the impression cylinder 20. Rotated counterclockwise at peripheral speed.

After the light shielding plate 106 passes through the photo sensor 107, the control device 111
In order to feed the leading edge of the sheet 3 in synchronization with the sheet holding position of the holding claw 21 by taking in the output pulse signal from
, So-called feedback control is performed.

As described above, the registration roller lower stepping motor 102 feeds the paper 3 in one pulse and the impression cylinder 2 corresponding to one pulse width of the encoder 120.
The outer peripheral movement amount of 0 is set to be the same. Thereby, for example, the control device 111 detects the time required for the outer peripheral movement of the impression cylinder 20 corresponding to one pulse width of the encoder 120 fixed to the impression cylinder 20 by the timer in the control device 111, and the registration roller The difference from the time during which the lower stepping motor 102 is rotated by one pulse is calculated and obtained. If the time required for one pulse of the registration roller lower stepping motor 102 is long due to load fluctuation on the impression cylinder 20 side, the time difference Is converted to the speed of the stepping motor 102 below the registration roller to increase the speed of the stepping motor 102 below the registration roller. On the contrary, the control device 1
11 performs feedback control such that when the time required for one pulse of the registration roller lower stepping motor 102 is short, the time difference is converted to the speed of the registration roller lower stepping motor 102 and the registration roller lower stepping motor 102 is decelerated. ing. In other words, the control device 111 always tracks the pulse fluctuation detected by the encoder sensor 121 due to the load fluctuation of the impression cylinder 20, etc., and changes the speed of the registration roller lower stepping motor 102 according to the pulse fluctuation. Feedback control (in FIG. 8, represented by encoder feedback control) using the above-described pulse encoder for controlling is performed.

By the encoder feedback control as described above by the control device 111, the movement amount of the outer periphery of the impression cylinder 20 and the paper feed amount for feeding the paper 3 after the light shielding plate 106 has passed the photo sensor 107 are always the same. . Under the encoder feedback control by the control device 111 as described above, the resist roller 33b is rotated counterclockwise, whereby the upper resist roller 33a is driven to rotate clockwise through the paper 3. As a result, as shown in FIG. 12, the bending 3A (shown by a broken line) of the sheet 3 disappears. At this time, the operation of each one-way clutch causes the paper feed roller 32 and the call roller 30 to rotate while being driven by the conveyance of the paper 3.
The leading end of the sheet 3 is conveyed toward the gripping claws 21 of the impression cylinder 20 and collides with the gripping claws 21.

At this timing, as shown in FIG. 8 and FIGS. 12 to 13, the gripper 21 of the impression cylinder 20 grips and grips the leading end of the sheet 3 and then grips the gripper 2.
1 is closed, and thus the impression cylinder 20
The paper 3 rotates while being held on the outer peripheral surface of the plate cylinder, and the leading end of the sheet 3 is conveyed between the outer peripheral surface of the plate cylinder 1 and the outer peripheral surface of the impression cylinder 20. At this time, as described above, the mounting position of the light shielding plate 106 to the end plate 20a of the impression cylinder 20 is determined by the registration roller pair 33a,
The distance on the sheet transport path R from the nip portion of the sheet 33b to the tip of the sheet 3 abutting on the gripper 21 and the light-shielding plate 106
Is the same distance from the rotational position of the impression cylinder 20 that generates the ON output signal by engaging with the photosensor 107 on the outer peripheral surface of the impression cylinder 20 to the holding claw 21 against which the leading end of the sheet 3 is abutted. A command signal is sent from the control device 111 to the registration roller lower stepping motor 102 so that the feed amount of the paper 3 is equal to the outer peripheral movement amount of the impression cylinder 20 because the paper 3 is attached at a certain position. As a result, the leading end of the sheet 3 is reliably held and held by the holding claws 21 without causing a clamping error or the like.

As shown in FIG. 13, the impression cylinders 26a and 26b of the contact / separation means apply pressure to the paper 3 conveyed between the outer peripheral surface of the plate cylinder 1 and the outer peripheral surface of the impression cylinder 20, as shown in FIG. The nip N is formed by the upward swinging displacement of the plate 20 against the outer peripheral surface of the plate cylinder 1, and the outer peripheral surface of the impression cylinder 20 presses the sheet 3 against the outer peripheral surface of the plate cylinder 1 ( In FIG. 8, the impression pressure of the impression cylinder 20 is turned on).

In this way, by pressing the outer peripheral surface of the impression cylinder 20, the sheet 3 is continuously pressed against the pre-made master 2 wound on the outer peripheral surface of the rotating plate cylinder 1. 2 comes into close contact with the outer peripheral surface of the plate cylinder 1, and the ink oozes out from the perforated portion of the plate cylinder 1 to the perforated portion of the stencil master 2, and is transferred to the surface of the paper 3, and stencil printing is performed. . At this time, the ink roller 13 also rotates in the same direction as the rotation direction of the plate cylinder 1. The ink in the ink pool 16 is rotated by the rotation of the ink roller 13 so that the ink
Is regulated on the surface of the plate cylinder 1 when passing through the gap between the ink roller 13 and the doctor roller 15.
Is supplied to the inner peripheral surface.

During this time, the above-described pulse encoder / feedback control is performed by the control device 111. The setting pulse of the stepping motor 102 below the registration roller corresponding to the distance from the nip portion of the registration roller pair 33a, 33b to the nip portion between the impression cylinder 20 and the plate cylinder 1 stored in the ROM by the control device 111. When it is determined that the registration roller lower stepping motor 102 has been rotationally driven and controlled, the rotation of the registration roller lower stepping motor 102 is stopped, and at the same time, the registration roller electromagnetic clutch 122 is turned off. Pulse encoder
The feedback control ends.

When the impression cylinder 20 is further rotated and the gripper 21 is opened at the paper discharge position before the paper discharge claw 44, the printed paper 3 is separated by the paper discharge claw 44 and conveyed by the conveyance belt 48. Then, the sheet is discharged and stacked on the sheet discharge table 45. In this way, so-called printing is performed in which the master 2 having been made is filled with ink, and the printing drum 1 is separated from the impression cylinder 20 to return to the initial state, and a printing standby state is set.

After the printing is completed, the operator visually checks the discharged printed matter and checks the print image quality and the position of the printed image. Are repeated for the set number of prints, and the entire stencil printing process is completed.

Therefore, according to the first embodiment, the following advantages can be obtained. First, in a stencil printing apparatus using the paper holding impression cylinder method, a pulse encoder for detecting a rotation speed fluctuation in the impression cylinder 20 for controlling the timing of feeding the leading end of the sheet 3 to the holding claw 21 (Encoder 120 and encoder sensor 1
21) is arranged on the impression cylinder 20 side, so that the leading end of the paper 3 is securely held and held by the holding claws 21 so that the paper 3
Can be prevented more reliably, the timing of feeding the paper to the holding claws 21 can be stabilized, and the reliability can be improved. As a result, the resist accuracy can be further improved. Second, the control device 111
Based on the output pulse signal from the encoder sensor 121, the registration roller lower stepping motor 102 is fed back to feed the leading end of the sheet 3 in timing with the sheet holding position of the holding claws 21. The drive system for driving the drive roller 33b is made independent of the main motor 60 for driving the plate cylinder 1 and the impression cylinder 20, so that the load on the drive system can be reduced and the power of the main motor 60 can be reduced to make it inexpensive.

Third, since the registration roller driving means is constituted by the registration roller lower stepping motor 102, there is no need for mechanical parts for regulating the brake and rotation direction of the registration roller pair 33a, 33b, so that the cost can be reduced.
The program of the control device can be simplified, and the arithmetic processing can be accelerated to increase the tracking accuracy of the feedback control. Fourth, the light-shielding plate 106 and the photosensor 107 for setting the timing for feeding the leading end of the sheet 3 to the holding claws 21 are arranged on the impression cylinder 20 side, so that the feeding timing can be stabilized and Reliability can be improved. Fifth, the registration roller pair 33a,
The light-shielding plate 105 and the photosensor 104 for setting the timing for feeding the leading end of the sheet 3 to the press roller 33b are arranged on the impression cylinder 20 side, thereby stabilizing the feeding timing and improving the reliability. Can be. Sixth, the feed roller driving means is connected to the feed roller stepping motor 100.
, The need for a mechanical component for regulating the rotation direction of the paper feed roller 32 is eliminated and the cost can be reduced. In addition, a drive system for driving the paper feed roller 32 and the call roller 30 is formed by the plate cylinder 1 and the impression cylinder 20. The load on the drive system can be reduced independently of the main motor 60 to be driven, and the power of the main motor 60 can be further reduced to make it inexpensive.

The above-described variable speed control of the stepping motor 102 under the registration roller by the control device 111 has been described in the case where the ideal feedback control is performed using the pulse encoder. Since the distance from the nip portion of the pair 33a, 33b to the outer peripheral surface of the plate cylinder 1 and the nip portion of the impression cylinder 20 is very short, for example, 100 mm, the speed of the stepping motor 102 under the registration roller is increased due to rapid pulse fluctuation. The control device 1
Stepping motor 102 under registration roller 11
May not be able to follow the pulse fluctuation detected by the encoder sensor 121 due to the load fluctuation of the impression cylinder 20 or the like. In such a case, in addition to the above-described feedback control by the control device 111, the paper transport speed V ′ when the leading end of the paper 3 comes into contact with the stopper claw 153 of the gripper 21 is faster than the peripheral speed V of the impression cylinder 20. As shown in FIG. 1, by setting
The paper conveyance speed control method (V ′> V) in which the bending 3B is generated in the vicinity of the holding portion of the leading end of the paper 3 due to the above, and a force such that the leading end of the paper 3 comes out of the gripper 21 does not work. . The paper transport speed V ′ is usually set to 1.01 to 1.03 times the peripheral speed V of the impression cylinder 20 according to the printing speed.

In the first embodiment, even when the above-described paper conveyance speed control method (V ′> V) is adopted, the guide member 160 is provided as described above, so that the leading end of the paper 3 The bent 3B generating portion generated in the vicinity of the holding portion is conveyed together with the rotation of the impression cylinder 20 while being guided by the guide member 160, so that the bent 3B generating portion of the sheet 3 before reaching the nip portion becomes the bent 3B generating portion of the plate cylinder 1. In order to prevent the master 3 from making contact with the master 2 on the outer peripheral surface, the surface of the paper 3 is not stained with ink.

(Modification of First Embodiment) FIGS. 4 to 13
, A modified example of the first embodiment will be described. This modification is different from the first embodiment in that the photosensor 104 and the light shielding plate 10 in the first embodiment shown in FIGS.
5. Photo sensor 107, light shielding plate 106, incremental encoder 120 and encoder sensor 12
1 and instead of these, as shown in FIG. 14, an absolute type pulse encoder (hereinafter, referred to as "pulse encoder") for detecting an absolute rotation amount capable of detecting a rotational speed fluctuation and a position of the impression cylinder 20 is provided. , "Absolute type pulse encoder") on the impression cylinder 20 side.

As shown in FIG. 14, the absolute type pulse encoder is mounted on an end plate 20a of an impression cylinder 20, and has a multi-channel photo encoder 220 in which a number of slits are radially arranged on the outer periphery in a plurality of stages. The arm 25b is sandwiched by the outer periphery of the photo encoder 220.
And a plurality of encoder sensors 221 attached to the control unit. The control operation in this modification is the same as that in the first embodiment.
The only difference is that the above-described operations of the photosensor 104, the light-shielding plate 105, the photosensor 107, the light-shielding plate 106, the incremental encoder 120 and the encoder sensor 121 are performed by one absolute pulse encoder, and it is technically obvious. The description is omitted.

Therefore, according to this modification, the advantages of the first embodiment (except for the advantages of the photosensor 104, the light shielding plate 105, the photosensor 107, the light shielding plate 106, the incremental encoder 120 and the encoder sensor 121 in the above advantage) In addition to the above terms, the absolute type pulse encoder is appropriately replaced with the photo encoder 220 and the encoder sensor 221), and the number of components of the control configuration can be reduced.

Second Embodiment FIGS. 2 and 3 show a second embodiment. The second embodiment has a guide member 160a as a sheet guiding unit instead of the guide member 160 of the first embodiment, as compared with the configuration of the first embodiment, and the guide member 160a is located downstream of the sheet transport path R. The only difference is that a flexible member 161 is provided at the side end.

The guide member 160a is the same as the guide member 160.
The guide member 160 a is formed such that the downstream end of the paper transport path R is shorter than that of the guide member 160. The flexible member 161 is attached to the downstream back surface of the U-shaped guide member 160a with an appropriate adhesive or a double-sided adhesive tape. The flexible member 161 is formed in a sheet shape from, for example, a leaf spring or a synthetic resin such as polyester. The flexible member 161 is formed so as to generate an appropriate elastic deformation by an external force when the bent portion 3B of the sheet 3 generates a contact pressure. The elasticity and thickness are determined. The elastic force and the thickness of the flexible member 161 are deflected when the sheet conveying speed V ′ is higher than that of the first embodiment (about 1.03 times the peripheral speed V of the impression cylinder 20). Even if 3B becomes large, the paper 3 can be conveyed without applying excessive stress, and the paper 3 is set to such an extent that the paper 3 is not damaged or broken. From this point, the flexible member 16
When 1 is formed of polyester, the flexible member 1
The thickness of 61 is preferably set in the range of 0.1 to 0.6 mm. The guide member 160 is located on the sheet transport path R before reaching the nip portion, and is provided between the master clamper 12 protruding outward from the outer peripheral surface of the plate cylinder 1, the outer peripheral surface of the plate cylinder 1, and the outer peripheral surface of the impression cylinder 20. It is provided at a position where it does not contact and does not contact the master 2 on the outer peripheral surface of the plate cylinder 1 due to its own elastic deformation. According to the second embodiment, the sheet conveying speed V ′ is set to be higher than that of the first embodiment, and even if the bending 3B generation portion of the sheet 3 becomes large, the flexible member 161 of the guide member 160 a The sheet 3 can be conveyed without exerting excessive stress on the sheet 3 by acting on the bending 3B generating portion of the sheet 3 with the above-described constant elastic force, so that the sheet 3 is not damaged or broken. Further, it is possible to prevent the bent 3B generating portion before reaching the nip portion from coming into contact with the stencil master 2 on the outer peripheral surface of the plate cylinder 1, which may cause ink stains on the surface of the paper 3. Absent.

The guide member 16 in the first embodiment
The guide member 160a and the flexible member 161 according to the second embodiment and the second embodiment are provided in the above-described sector gear system using a cam as a driving unit for the pair of registration rollers 33a and 33b. It goes without saying that even when V ′> V) is employed, the function is effectively performed. In the sector gear system,
Compared with the registration roller stepping motor driving method of the first and second embodiments, the variation in the speed fluctuation during the control is relatively small.
0 is sufficient, but in the case of the registration roller stepping motor driving method, there may be a relatively large variation in the speed fluctuation at the time of the control. Therefore, the guide member 160a and the flexible member 161 in the second embodiment are used. Is more effective.

As described above, the present invention has been described with respect to the specific embodiments and the like including the examples. However, the configuration of the present invention is not limited to the above-described embodiments and modified examples and the like. It is obvious to those skilled in the art that various embodiments and examples can be configured according to the necessity and use within the scope of the present invention.

[0097]

As described above, according to the first and second aspects of the present invention, the paper transport path before reaching the nip formed by the outer peripheral surface of the plate cylinder and the outer peripheral surface of the impression cylinder is provided. By providing paper guide means for guiding the paper so that the paper portion before reaching the nip does not contact the master made on the plate cylinder, the paper transport speed when the leading edge of the paper comes into contact with the holding means is reduced. By setting it faster than the peripheral speed of the impression cylinder,
In such a case that the bending is generated in the vicinity of the holding portion of the leading end of the sheet by the holding unit, in other words, even if a paper conveyance speed control method in which a force such that the leading end of the sheet comes off from the holding unit does not work is adopted, Since the sheet guide means guides the sheet so that the bent portion of the sheet before reaching the nip portion does not contact the master on which the plate is made, it is possible to prevent the ink stain on the sheet.

According to the third aspect of the present invention, since the registration roller driving means is a stepping motor,
The paper transport mechanism can be simplified, and the width of the paper transport control can be further expanded. The effect of the paper guiding means is more effectively achieved.

According to the fourth aspect of the present invention, since the flexible member is provided at the downstream end of the sheet conveying path of the sheet guiding means, the sheet conveying speed is much faster than the peripheral speed of the impression cylinder. Even if a larger deflection is set, the elastic force of the flexible member acts constantly on the large deflection generating portion, so that the sheet can be conveyed without applying excessive stress to the sheet, As a result, the paper is not damaged or broken, and the effects of the first and second aspects of the invention are achieved.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional front view of a main part around a plate cylinder and an impression cylinder of a stencil printing machine according to a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional front view of a main part around a plate cylinder and an impression cylinder of a stencil printing machine according to a second embodiment of the present invention.

FIG. 3 is a perspective view of a main part around a plate cylinder and an impression cylinder in FIG. 2;

FIG. 4 is a schematic partial cross-sectional front view of a stencil printing apparatus to which Embodiment 1 is applied.

FIG. 5 is an exploded perspective view of a main part showing a mounting structure of control components around the impression cylinder in the first embodiment.

FIG. 6 is a plan view of a main part in FIG. 5;

FIG. 7 is a block diagram illustrating a sheet feeding control configuration according to the first exemplary embodiment.

FIG. 8 is a timing chart of a sheet feeding operation in the first embodiment.

FIG. 9 is a front view of a main part illustrating a sheet conveyance operation when a sheet feeding roller is activated in the first embodiment.

FIG. 10 is a front view of a main portion illustrating an operation of forming a curved bending of a sheet between a registration roller and a sheet feeding roller according to the first exemplary embodiment.

FIG. 11 is a front view of a main part showing a sheet conveyance operation when a registration roller is activated in the first embodiment.

FIG. 12 is a front view of a main part illustrating an operation of transporting the leading end of the sheet to the gripper in the first embodiment.

FIG. 13 is a front view of a main part illustrating a sheet conveyance operation at the beginning of printing according to the first embodiment.

FIG. 14 is an exploded perspective view of a main part showing a mounting structure of control components around an impression cylinder in a modification of the first embodiment.

FIG. 15 is a front view of a main part showing a configuration of a paper feeding mechanism in a conventional stencil printing apparatus and a paper conveying operation when a paper feeding roller is started.

And FIG. 16 is a front view of a main part showing an operation of forming a curved bending of a sheet between a registration roller and a sheet feeding roller in a conventional stencil printing apparatus.

FIG. 17 is a front view of a main portion showing a sheet conveying operation immediately after a registration roller is activated in a conventional stencil printing apparatus.

FIG. 18 is a front view of a main part showing a sheet conveying operation at the beginning of printing in a conventional stencil printing apparatus.

FIG. 19 is a front view of an example of a paper feed drive mechanism in a conventional stencil printing apparatus and a main part showing the operation thereof.

FIG. 20 is a front view of an example of a paper feed drive mechanism in a conventional stencil printing apparatus and a main part showing the operation thereof.

FIG. 21 is a schematic front view showing a rotation position of a holding claw and a sheet conveyance operation accompanying a rotation operation of an impression cylinder in a conventional stencil printing apparatus.

FIG. 22 is a partial cross-sectional front view of the vicinity of a holding claw in a conventional impression cylinder.

FIG. 23 is a plan view for explaining a leading edge margin length of a printed sheet.

FIG. 24 is a simplified partial cross-sectional front view for explaining a problem of a paper clamp and a paper transport operation in a conventional impression cylinder.

FIG. 25 is a simplified partial cross-sectional front view for explaining problems of a paper clamp and a paper transport operation in a conventional impression cylinder.

FIG. 26 is an exploded perspective view of a main part around a clamp device in a conventional impression cylinder.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Plate cylinder 2 Master 3 Paper 3B Deflection of paper 20 Impression cylinder 21 Holding claw as holding means 29 Paper feed device 33a, 33b Registration roller pair 60 Main motor as impression cylinder drive means 100 Feed roller stepping motor 102 Registration roller drive Registration roller lower stepping motor 160, 160a as a means Guide member 161 as a paper guide means Flexible member R Paper transport path V Peripheral speed of impression cylinder V 'Paper transport speed X Paper transport direction

Claims (4)

[Claims] 1. A plate cylinder for winding a master made on an outer peripheral surface, and an impression cylinder having a holding means for holding a leading end portion of a fed sheet and having a diameter substantially equal to the outer diameter of the plate cylinder. A printing apparatus for printing on the sheet by pressing the impression cylinder relatively to the plate cylinder via a sheet, wherein the printing apparatus is formed by an outer peripheral surface of the plate cylinder and an outer peripheral surface of the impression cylinder. Paper guide means for guiding the paper so that the paper portion before reaching the nip portion does not contact the master on the plate cylinder is provided on the paper transport path before reaching the nip portion. Printing device. 2. The printing apparatus according to claim 1, further comprising a registration roller for feeding a leading end of the sheet toward the holding unit, the registration roller being configured to rotate the impression cylinder. A driving unit, and a registration roller driving unit that rotates the registration roller, wherein a sheet conveyance speed when the leading end of the sheet comes into contact with the holding unit is set to be faster than a peripheral speed of the impression cylinder. ,
A printing apparatus wherein a bending is generated in the vicinity of a holding portion of a leading end portion of the sheet by the holding means. 3. The printing apparatus according to claim 2, wherein said registration roller driving means is a stepping motor. 4. A printing apparatus according to claim 1, wherein a flexible member is provided at a downstream end of said paper conveying path of said paper guiding means.