JP2000169009A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printer capable of accurately feeding a print paper with no jam to print. SOLUTION: This printer has electrostatic drums 1, 8; platens 3, 9 rotating with abutting on the electrostatic drums 1, 8; disk members 21, 22 disposed at both end sides of the platens 3, 9 and rotating at the same peripheral speeds as peripheral speeds of the platens 3, 9; a pair of endless chains 13 moving corresponding to the peripheral speeds of the electrostatic drums 1,8 and the platens 3, 9; and a gripper unit 40, whose both end parts are supported by the chains 13, and which is formed with a pair of fitting parts capable of fitting in positioning recessed parts respectively formed on the disc members 21, 22 and is provided with plural grippers 43 for gripping the tip part of a print paper.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus such as a wet electronic printing apparatus and an offset printing apparatus.
In particular, the present invention relates to a printing apparatus that performs printing on a sheet of printing paper.

[0002]

2. Description of the Related Art In such a printing apparatus, a sheet of printing paper supplied from a paper feeding unit is sequentially transferred between a plurality of grippers to convey and execute printing, such as an electrostatic drum or a blanket cylinder. The printing on the printing paper is executed by passing through the contact portion between the printing cylinder and the impression cylinder.

[0003]

In the case where the printing paper is conveyed by sequentially transferring the printing paper between a plurality of grippers, the position of the printing paper when transferring the printing paper must be adjusted unless each gripper is adjusted with high precision. Misregistration occurs, resulting in misregistration of the printed image. Further, when the printing paper is delivered, there is a problem that the paper is likely to be jammed.

On the other hand, in a simple printing apparatus, a transport mechanism using a suction belt or a roller transport mechanism is also employed. However, it is difficult to perform high-precision printing when using a conveyance mechanism using a suction belt or a roller conveyance mechanism. The same is true.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a printing apparatus capable of carrying out printing by transporting printing paper accurately and without causing a jam. And

[0006]

According to a first aspect of the present invention, there is provided a printing cylinder for performing printing, which is opposed to the printing cylinder in a state in which the printing cylinder is in contact with the printing cylinder, and which has the same peripheral speed as the peripheral speed of the printing cylinder. A rotating impression cylinder, a pair of disk members disposed at both ends of the impression cylinder and rotating at the same peripheral speed as the peripheral speed of the impression cylinder, and a contact portion between the printing cylinder and the impression cylinder. A pair of endless ropes that are arranged to pass through both ends and move in accordance with the peripheral speeds of the printing cylinder and the impression cylinder, and both ends thereof are supported by the ropes, and the pair of endless ropes are supported by the ropes. A pair of engaging portions capable of engaging with the positioning portions formed on the disk member, and a gripper unit provided with a plurality of grippers for holding the leading end of the printing paper. It is characterized by.

According to a second aspect of the present invention, in the first aspect, both end portions of the gripper unit are supported by the cable body so as to be movable in a longitudinal direction of the cable body.

According to a third aspect of the present invention, in the printing apparatus according to any one of the first and second aspects, the positioning portion includes a positioning recess formed on an outer peripheral portion of the disk member.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a main part of a printing apparatus according to the present invention, and FIG. 2 is a schematic side view thereof.

This printing apparatus performs printing by a wet electrophotography system, and includes a paper feeding unit 11 for feeding sheet-like printing paper and a printing cylinder for executing printing on the surface of the printing paper. An electrostatic drum 1, an impression cylinder 3 disposed opposite to the electrostatic drum 1, an electrostatic drum 8 as a printing cylinder for performing printing on the back surface of the printing paper, and the electrostatic drum 8. An impression cylinder 9 arranged oppositely, a paper discharge unit 12 for collecting printing paper on both sides of which are printed, and a plurality of gripper units 40 connected to a chain 13 for transporting the printing paper. Prepare.

The printing paper supplied from the paper supply unit 11 is transferred to a gripper unit 40 described later via the conveyor 18. The printing paper passes through the abutting portions of the electrostatic drums 1 and 8 and the impression cylinders 3 and 9 while the leading end thereof is held between the gripper units 40, thereby printing on both surfaces thereof. After that, the discharge unit 12
Is discharged.

FIG. 3 is a perspective view showing the connection between the electrostatic drum 1 and the impression cylinder 3 described above.

A gear 14 that rotates in synchronization with the electrostatic drum 1 is coaxially disposed beside the electrostatic drum 1.
The gear 14 meshes with a gear 15 having the same diameter as the gear 14. The gear 15 includes a gear 33 disposed coaxially with the impression cylinder 3, a gear 34, and a gear 3.
5 and a shaft 36. For this reason, the electrostatic drum 1 and the impression cylinder 3 are configured to rotate at the same peripheral speed in synchronization with each other. Here, the “peripheral speed” described in this specification refers to the speed of the outer peripheral portion of the cylindrical member or the disk-shaped member.

In this embodiment, the impression cylinder 3
Are smaller in diameter than the electrostatic drum 1, but the impression cylinder 3 and the electrostatic drum 1 may have the same diameter. In this case, a gear having the same diameter as the gear 14 rotating in synchronization with the electrostatic drum 1 may be provided on the side of the impression cylinder 3, and the gear and the gear 14 may be directly meshed.

At both ends of the impression cylinder 3, a pair of disc members 21
Are arranged coaxially with the gear 15 described above. Therefore, the disk member 21 rotates at the same peripheral speed as the peripheral speed of the impression cylinder 3 in synchronization with the gear 15. This disk member 2
1 has a sprocket portion 19 that engages with the chain 13. The disk member 21 is formed with two positioning recesses 37 (only one is shown in FIG. 3) to be described later.

The electrostatic drum 8 and the impression cylinder 9 for printing on the back surface of the printing paper are also provided with gears 16 and 17 having the same configuration as the gears 14 and 15 and the disk member 21.
And a disk member 22 are provided.

FIG. 4 is a schematic side view showing the vicinity of the electrostatic drum 1 and the impression cylinder 3 described above.

On the outer peripheral portion of the electrostatic drum 1, an electrostatic drum 1
A recording head 2 for irradiating a light beam on the recording medium 2 to form an electrostatic latent image, and a charging unit 4 for charging the electrostatic drum 1
A liquid toner supply unit 5 for supplying liquid toner to the electrostatic drum 1, a cleaning unit 6 for removing toner remaining on the electrostatic drum 1, and a charge removing unit for removing charge from the electrostatic drum 1 7 are provided.

When printing is performed using the electrostatic drum 1, the outer peripheral portion of the electrostatic drum 1 rotating counterclockwise in FIG. Next, the recording head 2 scans the outer periphery of the electrostatic drum 1 with a light beam to form an electrostatic latent image on the photoconductive layer on the outer periphery of the electrostatic drum 1. Then, in the liquid toner supply unit 5, the photoconductive layer of the electrostatic drum 1 on which the electrostatic latent image is formed comes into contact with the liquid toner composed of the toner powder and the non-conductive solvent, so that the toner powder is removed. The electrostatic latent image is developed as a toner image by electrophoresis. This toner image is transferred to the printing paper wound around the outer peripheral portion of the impression cylinder 3.

The electrostatic drum 8 also performs printing on the back surface of the printing paper by the same configuration as that of the electrostatic drum 1 described above.

Referring again to FIGS. 1 to 3, the pair of chains 13 has an endless shape. The chain 13 is engaged with sprockets 23, 24, 25, 26, 27 and 28, which are paired with each other, in addition to the sprocket portions 19 formed on the disc members 21 and 22 described above. Therefore, the above-described disc members 21 and 22 rotate at the same peripheral speed in synchronization with the electrostatic drums 1 and 8 and the impression cylinders 3 and 9. And this pair of chains 13
Are provided with a plurality of gripper units 40 (1 in FIG. 1).
Are shown).

FIG. 5 is a plan view showing a main part of the gripper unit 40, and FIGS.
FIG. 3 is a side view schematic diagram of No. 3; In FIG. 5, only the left end of the gripper unit 40 is shown. The right side of the gripper unit 40 also has the same configuration as the left end shown in FIG.

The gripper unit 40 has a support bar 42 having, at both ends thereof, engagement portions 41 for engaging the positioning recesses 37 formed in the disk member 21 described above.
And a plurality of grippers 43 arranged at a constant pitch in the longitudinal direction of the support bar 42.

The gripper 43 has a first holding portion 44 fixed to the support bar 42 and a second holding portion 45 swinging about the support bar 42. The second holding portion 45 includes a spring 46
The tip of the first holding portion 44 is urged in the direction in which the tip of the first holding portion 44 comes into contact with the tip of the first holding portion 44. In addition, each gripper 43
Are connected to each other by a connecting bar 47. A cam follower 48 is attached to both ends of the connecting bar 47.

The gripper 43 includes a gripper unit 4
0 moves together with the pair of chains 13, and the cam follower 48 comes into contact with the cam 31 or 32 (see FIG. 2) disposed on the apparatus main body, thereby forming the printing paper S shown in FIG.
Is released. Also, cam follower 48
Is not in contact with the cams 31 or 32, the printing paper S shown in FIG.

The pair of chains 13 includes a casing 51.
Is fixed. A shaft 52 penetrating through holes formed at both ends of the support bar 42 is provided inside the casing 51. Therefore, the support bar 42
Is supported so as to be movable in the longitudinal direction of the pair of chains 13.

A spring 53 is provided in a region between the support bar 42 and the casing 51 on the outer periphery of the shaft 52. By the action of the spring 53, the support bar 42
Is disposed near the center of the shaft 52 in a normal state.

It should be noted that the gripper unit 40 having the above-described structure is configured so that the disk member 21
22 are arranged at a half pitch of the outer circumference. However, only one gripper unit 40 is shown in FIG. 1 and is not shown in FIG.

When printing is performed by the printing apparatus having the above-described configuration, the feeder 11 feeds the conveyor 1
8, the printing paper is supplied to the gripper 43 of the gripper unit 40 that moves together with the pair of chains 13.
At this time, the gripper 43 has its cam follower 48
6 comes into contact with the cam 31 and once becomes the release state shown in FIG. 6, and then returns to the holding state shown in FIG. 7, thereby holding the leading end of the printing paper.

The leading end of the printing paper is gripper 43.
While passing through the contact portion between the electrostatic drum 1 and the impression cylinder 3. Thereby, printing is performed on the surface of the printing paper.

At this time, it is generally difficult to accurately convey the printing paper in a chain delivery mechanism that conveys the printing paper using a chain or the like. However, in this printing apparatus, the positional accuracy of the printing paper is maintained by utilizing the engaging portion 41 of the gripper unit 40 and the positioning recess 37 formed in the disk member 21.

That is, in a state where the printing paper whose leading end is held by the gripper 43 is conveyed to the contact portion between the electrostatic drum 1 and the impression cylinder 3, as shown in FIGS. 8 (a) to 8 (c). The engaging portion 41 of the gripper unit 40
Engages with a positioning recess 37 formed in the disk member 21 that rotates at the same peripheral speed as the impression cylinder 3. And, as described above, the impression cylinder 3 and the electrostatic drum 1 are
4, 35, 15, and 14 are connected. For this reason, it is possible to maintain the positional relationship between the gripper 43 holding the leading end of the printing paper and the electrostatic drum 1 with high accuracy, and to execute printing with high accuracy.

At this time, the support bar 42 of the gripper unit 40 is connected to a shaft 52 provided in the casing 51.
The pair of chains 13 is supported by the pair of chains 13 so as to be movable in the longitudinal direction by the action of the springs 53. Therefore, the engagement state between the engagement portion 41 and the positioning recess 37 can be easily obtained, and the gripper can be obtained. It is possible to maintain the positional relationship between the electrostatic drum 43 and the electrostatic drum 1 with high accuracy.

Since the position of the printing paper in the direction orthogonal to the longitudinal direction of the pair of chains 13 is determined by the holding position between the electrostatic drum 1 and the impression cylinder 3, the gripper 4
It is not necessary to maintain the position of the chain 3 and the electrostatic drum 1 in a direction orthogonal to the longitudinal direction of the chain 13 with particularly high precision.

The printing paper, which has passed the contact portion between the electrostatic drum 1 and the impression cylinder 3 and has its surface printed, then passes through the contact portion between the electrostatic drum 8 and the impression cylinder 9 Then, printing is performed on the back surface by the same operation as described above.

At this time, since the leading end of the printing paper is held by the gripper unit 40 until printing on both sides is completed, the printing paper is received between the plurality of grippers. No misalignment or jam occurs as in the case of handing over.

The printing paper on which printing has been completed is conveyed toward the paper discharge unit 12 by the gripper unit 40. In the paper discharge unit 12, the cam follower 48 of the gripper unit 40 comes into contact with the cam 32, so that the gripper 43
Is in the release state shown in FIG. 6, and the printing paper sandwiched there is released.

In the above-described embodiment, a case has been described in which the present invention is applied to a printing apparatus having electrostatic drums 1 and 8 as printing cylinders and performing printing by a wet electrophotographic method. The present invention may be applied to a general printing device such as an offset printing device. In this case, the blanket cylinder that transfers the ink to the printing paper corresponds to the printing cylinder.

In the above-described embodiment, the chain 13 is used as the cord, but another cord such as a synchronous belt or a wire may be used.

Further, in the above-described embodiment,
Although the case where single color printing is performed on both sides of the printing paper has been described, for example, the present invention can be applied to a multicolor printing apparatus that performs two-color or four-color printing on both sides of the printing paper. .

[0041]

According to the first aspect of the present invention, a gripper unit having both ends supported by a cord body and having an engaging portion engageable with a positioning portion formed on a disk member is utilized. Since the printing paper is conveyed, it is possible to effectively prevent the occurrence of a position shift or a jam that occurs when the printing paper is delivered. For this reason, it is possible to carry out printing with high accuracy by transporting the printing paper with high accuracy and without causing a jam.

According to the second aspect of the present invention, since both ends of the gripper unit are movably supported in the longitudinal direction of the cord, the engagement relationship between the positioning portion and the engagement portion can be easily established. Obtainable.

According to the third aspect of the present invention, since the positioning portion is constituted by the positioning concave portion formed on the outer peripheral portion of the disk member, the engaging relationship with the engaging portion can be obtained with a simple configuration. be able to.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a main part of a printing apparatus according to the present invention.

FIG. 2 is a schematic side view showing a main part of the printing apparatus according to the present invention.

FIG. 3 is a perspective view showing a connection relationship between the electrostatic drum 1 and the impression cylinder 3;

FIG. 4 is a schematic side view showing the vicinity of the electrostatic drum 1 and the impression cylinder 3;

FIG. 5 is a plan view showing a main part of the gripper unit 40.

6 is a schematic side view of the gripper 43. FIG.

FIG. 7 is a schematic side view of the gripper 43.

FIG. 8 is an explanatory diagram illustrating an engagement operation between an engagement portion 41 and a positioning recess 37.

[Explanation of symbols]

 1, 8 Electrostatic drum 3, 9 Impression cylinder 11 Paper feed section 12 Paper discharge section 13 Chain 14, 15 Gear 16, 17 Gear 19 Sprocket section 21, 22 Disk member 37 Positioning recess 40 Gripper unit 41 Engagement section 42 Support Bar 43 Gripper 44 First sandwiching section 45 Second sandwiching section 47 Connecting bar 48 Cam follower 51 Casing 52 Shaft 53 Spring S Printing paper

Claims (3)

[Claims] 1. A printing cylinder for performing printing, an impression cylinder that is disposed opposite to the printing cylinder in contact with the printing cylinder and rotates at the same peripheral speed as the peripheral speed of the printing cylinder, and at both ends of the impression cylinder. A pair of disk members disposed and rotating at the same peripheral speed as the peripheral speed of the impression cylinder; and a pair of disk members disposed so as to pass through both ends of a contact portion between the printing cylinder and the impression cylinder, and the printing is performed. A pair of endless ropes that move in accordance with the circumferential speed of the trunk and the impression cylinder, and both ends of the ropes are supported by the ropes, and are engageable with positioning portions formed on the pair of disc members, respectively. And a gripper unit in which a pair of engaging portions are formed and a plurality of grippers for holding the leading end of the printing paper are arranged. 2. The printing apparatus according to claim 1, wherein both ends of the gripper unit are supported by the cable so as to be movable in a longitudinal direction of the cable. 3. The printing apparatus according to claim 1, wherein the positioning section includes a positioning recess formed on an outer peripheral portion of the disk member.