JPH11180025A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a damage of a conveying system member including a printing drum at the time of stopping a motor. SOLUTION: A motor decelerating command signal is output to a motor driving means under the conditions that occurrence of a fault such as a sheet jam or the like is recognized and a specified value or more of a printing speed is recognized. A control means for outputting a motor stop command signal to the motor drive means after a predetermined time is elapsed is provided. In the case of the fault such as the jam, conveying system members 16, 17 including a printing drum 2 are stopped in the state that the printing speed is decelerated to a low speed drive of less than a specified value. Thus, a shock applied to a power transmission system is alleviated to prevent a damage of the transmission system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus for transferring an image on a printing drum to a sheet while feeding a sheet by rotating a conveying member including a printing drum by a motor.

[0002]

2. Description of the Related Art Generally, when a paper jam occurs, the printing apparatus detects the jam, stops a motor of a driving system, stops printing, and performs a jam processing. For example, JP-A-8-
As described in Japanese Patent Publication No. 318669, while holding a sheet between a printing drum (hereinafter, referred to as a plate cylinder) and an impression cylinder around which a plate-making master has been wound, ink is transferred from the master on the printing drum. In a stencil printing machine that exudes and transfers to a sheet, the sheet is gripped by a holding claw provided on the impression cylinder, and the impression cylinder is rotated in synchronization with the rotation of the printing drum, so that the paper is transferred to the printing drum and the impression cylinder. The printing drum and the impression cylinder are stopped when a jam is detected.

Further, as described in Japanese Patent Application Laid-Open No. 60-216358, when an image on which a sheet is transferred by an electrophotographic method is fixed by a fixing and discharging device, a recording sheet conveyance accident occurs. In some cases, the driving system for driving the recording paper is automatically stopped, and the fixing and discharging device is automatically stopped after discharging the recording paper.

Further, as described in Japanese Patent Application Laid-Open No. 59-109069, the motor of the image forming apparatus is gently stopped in a normal state when the motor is stopped, and the motor is rapidly stopped in a jam occurrence character. I have to.

Further, as described in Japanese Patent Application Laid-Open No. 63-69420, when the drum of the printing apparatus is driven by a motor, if the load is abnormally increased, the torque is increased to increase the power transmission system. The motor is stopped instantaneously because the member is destroyed.

[0006]

As described above, the motor for driving the transport system member including the printing drum is:
When any abnormality such as a jam occurs, the vehicle is rapidly stopped, so that the shock in the drive system increases. A quick stop can reduce the time during which a shock is applied to the drive system, but the magnitude of the shock increases the back electromotive force generated in the motor, which may damage the power transmission system.

[0007]

According to the first aspect of the present invention,
In a printing apparatus that transfers an image on the printing drum to a sheet while feeding a sheet by feeding a sheet by rotating a conveyance system member including a printing drum by a motor, an error detecting unit that detects an error such as a jam, and a printing speed. Printing speed detecting means for detecting, and a motor driving means for driving the motor,
A motor deceleration command signal is output to the motor drive unit under the condition that the abnormality detection unit recognizes that an abnormality has occurred and the print speed detection unit recognizes that the print speed is equal to or higher than a specified value, and after a predetermined time elapses, Control means for outputting a motor stop command signal to the motor driving means is provided.

Therefore, when an abnormality such as a jam occurs, it is possible to stop the conveying system member including the printing drum in a state where the printing speed is reduced to a low speed drive lower than the specified value, and the power transmission system Can be reduced.

According to a second aspect of the present invention, in the first aspect of the present invention, there is provided a rotational position detecting means for detecting a rotational position of the printing drum, and the control means recognizes that an abnormality has occurred by the abnormality detecting means. Under a condition that the printing speed is recognized by the printing speed detecting unit as being equal to or higher than a specified value, a motor deceleration command signal is output to the motor driving unit, and a motor stop command signal is output to the motor driving unit after a lapse of a predetermined time, After outputting a motor low-speed rotation command signal to the motor driving means after a certain period of time, when the rotation position detecting means detects that the printing drum has returned to the home position, the motor driving means outputs a motor stop command signal to the motor driving means. Control to output is executed.

Therefore, when an abnormality such as a jam occurs, the conveyance system member including the printing drum can be stopped in a state where the printing speed is reduced to a low speed drive lower than the specified value, so that the power transmission system can be stopped. Can be reduced. Further, after the transport system member including the printing drum is stopped, the motor can be driven at a low speed to return the printing drum to the home position without giving a shock to the power transmission system.

[0011]

An embodiment of the present invention will be described with reference to the drawings. The printing apparatus according to the present embodiment is an example of a stencil printing apparatus. The configuration of the stencil printing apparatus A will be schematically described with reference to FIG. The stencil printing apparatus A includes an image reading unit 1 that reads a document image. The printing drum 2 is rotatably supported by the opposing side plates (not shown). The printing drum 2 has an ink supply mechanism (not shown) including an ink roller 3 therein, and is configured to bleed ink from a screen formed on the outer periphery. A clamp 4 for gripping the end of is provided to be freely openable and closable. Further, on the outer circumference of the printing drum 2, an impression cylinder 5 for pressing the fed paper P against the printing drum 2, an advancing / retracting peeling claw 6 for peeling the paper P from the printing drum 2, and A plate discharging section 7 for peeling a used master wound around the print drum 2 and a plate making section 9 for making a master 8 based on an image read by the image reading section 1 are arranged. The plate making section 9 includes a platen roller 10 and a thermal head 11 that is disposed so as to be able to freely contact and separate from the platen roller 10, a roller 12 that conveys the master 8 toward the printing drum 2, and a cutter 13 that cuts the master 8.
And

The paper P is stacked on a paper feed tray 14 which can be moved up and down. Above the paper feed tray 14, a certain amount of paper P is controlled by raising the paper feed tray 14 which is controlled in accordance with the number of papers P. A paper feed roller 15 for feeding the uppermost sheet P maintained at a height, and a pair of registration rollers 16 driven in synchronization with the rotation of the print drum 2 are provided. Further, on the downstream side of the impression cylinder 5, a paper discharge belt 17 and a paper discharge tray 18 are sequentially arranged.

Next, a series of operations in the stencil printing apparatus A will be described. This operation is not a feature of the present invention and will be described briefly. First, in order to make a master 8, an unmade master 8 is passed between the platen roller 10 and the thermal head 11 and between the pair of rollers 12. When the plate making process is executed, the platen roller 10 and the roller 12 are driven, and at the same time, a voltage is applied to a specific resistance heating element of the thermal head 11 based on the image data of the document read by the image reading unit 1, and the master 8 is driven. Plate making is performed.

The master 8 thus produced is sent out toward the printing drum 2 by the rollers 12, and in synchronization with this operation, the clamp 4 of the printing drum 2
, And the tip of the master 8 is gripped by the clamp 4. Therefore, the printing drum 2 is rotated clockwise, and the master 8 on which the plate has been made is cut by the cutter 13 so that the master 8 is wound around the printing drum 2.

Thereafter, the printing process is executed. The uppermost sheet P in the sheet feed tray 14 is fed by the sheet feed roller 15, and the registration roller 1
6 is driven to press the paper P against the master 8 on the printing drum 2 with the impression cylinder 5 displaced upward when the leading end of the paper P passes between the printing drum 2 and the impression cylinder 5. The ink in the drum 2 oozes out of the perforated portion of the master 8 and is transferred to the paper P. That is, printing is performed. The printed paper P is discharged to a discharge tray 18 by a discharge belt 17.

The stencil printing apparatus A according to the present embodiment includes a home position sensor 19 disposed below the printing drum 2 and a paper sensor 20 for detecting the presence or absence of the paper P on the discharge belt 17. I have. The home position sensor 19 outputs a signal indicating that the printing drum 2 is located at the home position when the optical axis is interrupted by a light shielding piece (not shown) protruding from a part of the outer periphery of the printing drum 2. Sensor.

The above-described printing drum 2 and registration roller 1
6. A motor 2 for driving a conveyance system member such as a discharge belt 17
1 (see FIG. 2) incorporates an encoder (not shown) and is further connected to a motor drive circuit 22 as motor drive means. Although not shown, the control circuit 23 for controlling the operation of the motor drive circuit 22 includes a CPU and an RO in which a program executed by the CPU is written.
The microcomputer has a microcomputer including a RAM for storing variable data such as M and work data in a rewritable manner, an encoder pulse counter for counting encoder pulses output from the motor 21, and a timer.

Furthermore, the stencil printing apparatus A according to the present embodiment detects printing speed, printing speed detecting means, rotating position (home position) of the printing drum 2, and rotational position detecting means, and detects jam. Abnormality detecting means. The printing speed detecting means has a function of detecting the printing speed by determining, by the CPU, how many encoder pulses output from the motor 21 have been received within a predetermined time set in a timer in the control circuit 23. The rotational position detecting means has a function of detecting the rotational position (home position) of the printing drum 2 by determining the detection signal of the home position sensor 19 by the CPU of the control circuit 23 described above. The abnormality detecting means has a function of detecting a jam by the CPU of the control circuit 23 judging a detection signal of the paper sensor 20 at a predetermined timing described later.

Further, the control circuit 23 recognizes that an abnormality (jam) has occurred by the above-described abnormality detecting means, and recognizes that the printing speed is equal to or higher than a specified value by the printing speed detecting means. A motor deceleration command signal is output to the motor drive circuit 22 after a lapse of a predetermined time, and a motor low speed rotation command signal is output to the motor drive circuit 22 after a lapse of a predetermined time. Functions as control means for outputting a motor stop command signal to the motor drive circuit 22 when the rotational position detecting means detects that the motor has returned to the home position.

Hereinafter, the control operation process of the motor 21 will be described with reference to the flowchart shown in FIG. The motor 21 drives the printing drum 2, the registration roller 16, the paper discharge belt 17, and the like. Thus, the conveyance speed and printing speed of the paper P are affected by the rotation speed of the motor 21. Further, since the paper feed roller 15 stops after delivering the paper P to the registration roller 16, when driven by the above-described motor 21 without using another motor, the paper P is transmitted to the motor 21 via a clutch (not shown). The rotation of the paper feed roller 15 is controlled by the operation of the clutch.

When printing is started, the paper P on the paper feed tray 14 is fed toward the registration roller 16 as described above, and the paper P is discharged from the printing drum 2 around which the stencil master 8 is wound. The paper belt 17 is driven by the motor 21 and starts rotating clockwise. When the registration roller 16 is driven in synchronization with the rotation of the printing drum 2, the paper P
Is fed between the printing drum 2 and the impression cylinder 5. When the leading end of the paper P passes between the printing drum 2 and the impression cylinder 5, the paper P is pressed against the master 8 on the printing drum 2 by the impression cylinder 5 displaced upward, so that printing on the paper P is performed. . The printed paper P is discharged toward a discharge tray 18 by a discharge belt 17.

In the printing process, in step S1 in FIG. 3, it is determined whether or not the printing drum 2 is at the home position. Specifically, the rotating printing drum 2
When the CPU of the control circuit 23 recognizes the detection signal of the home position sensor 19 when the optical axis is shielded by the light shielding piece, it is determined that the printing drum 2 is located at the home position. That is, step S1 corresponds to a rotational position detecting unit that detects the rotational position (home position) of the printing drum 2.

The control circuit 23 starts counting the number of encoder pulses input from the motor 21 to the encoder pulse counter after recognizing that the printing drum 2 is at the home position in step S1 (S2). When it is determined in step S3 that the count number has reached the predetermined value, it is determined whether a paper feed jam has occurred (S4). Specifically, if the timing at which the printing drum 2 is driven from the home position by a predetermined number of steps is normal, the sheet P is discharged from the discharge belt 1
7, the detection signal of the paper sensor 20 is monitored at this timing. If the paper sensor 20 has output a detection signal indicating that there is no paper, it recognizes that the paper P has not reached that jam. That is, step S4 corresponds to abnormality detection means for detecting an abnormality (jam).

If it is determined in step S4 that a jam has occurred, it is then determined whether the printing speed is equal to or higher than a specified value. Specifically, since the printing speed is determined by the rotation speed of the motor 21 that drives the printing drum 2, the control circuit 23
The number of encoder pulses of the motor 21 counted by the encoder pulse counter is determined within a predetermined time set by the timer, and the printing speed can be recognized by a method such as comparing this with a reference value. That is, step S5 corresponds to a printing speed detecting unit that detects the printing speed.

If it is determined in step S5 that the printing speed is equal to or higher than the specified value, the CPU of the control circuit 23
Outputs a motor deceleration command signal to the motor drive circuit 22 (S6), and then starts a timer (S6).
7). In this case, the value set in the timer is
Wait time until deceleration (about 100 ms)
It is. When a predetermined time corresponding to the wait time has elapsed (S8), the rotation speed of the motor 21 (the printing drum 2
Is reduced to a desired speed, so that the CPU of the control circuit 23
(S9). In step S5 described above, when the CPU of the control circuit 23 determines that the printing speed is lower than the specified value, the process proceeds to step S9.

When the CPU outputs a motor stop command signal in step S9, the motor 21 stops. Also at this time, the CPU sets the wait time required until the motor 21 stops in the timer, and when the CPU determines that the predetermined time corresponding to the wait time has elapsed (S10).
Then, a motor low-speed rotation command signal is output to the motor drive circuit 22 (S11). Thereby, the motor 21 rotates the printing drum 2 at a low speed. When the light-shielding piece reaches the home position sensor 19 due to the rotation of the printing drum 2, the CPU determines that it is the moment when the printing drum 2 is located at the home position (S12), and sends a motor stop command signal to the motor drive circuit 22. Is output. This allows
The transport system members such as the printing drum 2 stop.

Here, FIGS. 4 and 5 show a temporal change in the rotation speed of the printing drum 2 from the detection of a jam until the stop of the motor 21. FIG. 4 shows that the rotation speed of the printing drum 2 is high when the jam is detected (the printing speed is equal to or higher than a specified value).
Step S6 to decelerate before stopping the motor 21
9 is a time chart when controlling the operation of the motor 21 after the processing of S8. FIG. 5 is a time chart when the operation of the motor 21 is controlled by omitting the processing of steps S6 to S8 because the rotation speed of the printing drum 2 is low (the printing speed is less than the specified value) when a jam is detected.

As described above, when an abnormality such as a jam occurs, the transport system member including the print drum 2 can be stopped in a state where the printing speed is reduced to a low speed drive lower than the specified value. Thereby, the shock applied to the power transmission system can be reduced, and damage to the power transmission system can be prevented.

Further, when a jam occurs, the transport system member including the print drum 2 is stopped, and then the motor 21 is stopped.
Can be driven at a low speed to return the printing drum 2 to the home position without giving a shock to the power transmission system. Thus, it is possible to immediately shift to the printing process after the jam processing.

Generally, the printing drum 2 is configured to be detached from the printing press main body only at the home position. Therefore, when the printing drum 2 is removed for jam clearance or the like, the printing is stopped when the motor 21 is stopped. Since the drum 2 is located at the home position, the print drum 2 can be immediately removed.

That is, steps S6 to S8 are performed under the conditions that the motor drive circuit 2 recognizes that an abnormality such as a jam has occurred and that the printing speed is equal to or higher than a specified value.
The control means outputs a motor deceleration command signal to the second control means.

Steps S6 to S13 are performed under the conditions that the motor drive circuit 22 recognizes that an abnormality such as a jam has occurred and recognizes that the printing speed is equal to or higher than a specified value.
A motor deceleration command signal is output to the motor drive circuit 22 after a lapse of a predetermined time, and a motor low speed rotation command signal is output to the motor drive circuit 22 after a lapse of a predetermined time. Outputs a motor stop command signal to the motor drive circuit 22 when detecting that the motor has returned to the home position.

The printing drum is not limited to the one around which a master having been made is wound, and a photosensitive drum for forming an electrostatic latent image may be used. That is, the present invention is also applicable to a printing apparatus that forms an image by an electrophotographic method.

[0034]

According to a first aspect of the present invention, there is provided a printing apparatus for transferring an image on a printing drum to a sheet while feeding a sheet by rotating a conveying system member including a printing drum by a motor. Abnormality detection means for detecting abnormality;
A printing speed detection unit for detecting a printing speed, and a motor driving unit for driving the motor, wherein the motor is recognized under the condition that it is recognized that an abnormality such as a jam has occurred and the printing speed is recognized to be a specified value or more. A control means for outputting a motor deceleration command signal to the driving means and outputting a motor stop command signal to the motor driving means after a certain time has elapsed is provided, so that when an abnormality such as a jam occurs, the printing speed is set to a specified value. The conveyance system member including the print drum can be stopped in a state where the speed is reduced to a low speed drive of less than. Thereby, the shock applied to the power transmission system can be reduced, and damage to the power transmission system can be prevented.

According to a second aspect of the present invention, in the first aspect of the present invention, the apparatus further comprises a rotational position detecting means for detecting a rotational position of the printing drum, and the control means recognizes that an abnormality such as a jam has occurred and Under the condition that the printing speed is recognized as being equal to or higher than the specified value, a motor deceleration command signal is output to the motor driving unit, a motor stop command signal is output to the motor driving unit after a lapse of a certain time, and further, after a lapse of a certain time. After outputting the motor low-speed rotation command signal to the motor drive unit, the control to output a motor stop command signal to the motor drive unit when the rotation position detection unit detects that the print drum has returned to the home position. When an error such as a jam occurs, the print speed is reduced to a low speed that is less than the specified value. The transfer system member comprising can be stopped. Thereby, the shock applied to the power transmission system can be reduced, and damage to the power transmission system can be prevented. Further, after the transport system member including the printing drum is stopped, the motor can be driven at a low speed to return the printing drum to the home position without giving a shock to the power transmission system. Thus, it is possible to immediately shift to the printing process after the jam processing.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view showing a schematic configuration of a stencil printing apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram of a control system for controlling the operation of the motor.

FIG. 3 is a flowchart illustrating a motor operation control process.

FIG. 4 is a time chart showing motor operation control processing when the printing speed is equal to or higher than a specified value.

FIG. 5 is a time chart showing motor operation control processing when the printing speed is lower than a specified value.

[Explanation of symbols]

 2 Print drum, transport system member 16, 17 Transport system member 21 Motor 22 Motor drive means S1 Rotational position detection means S4 Abnormality detection means S5 Printing speed detection means S6 to S13 Control means

Claims (2)

[Claims] An abnormality detecting means for detecting an abnormality such as a jam in a printing apparatus for transferring an image on the printing drum to a sheet while feeding a sheet by rotating a conveying system member including a printing drum by a motor. A printing speed detecting unit for detecting a printing speed, and a motor driving unit for driving the motor, wherein the abnormality detecting unit recognizes that an abnormality has occurred, and the printing speed detecting unit determines that the printing speed is equal to or greater than a specified value. And a control means for outputting a motor deceleration command signal to the motor driving means under the condition that the motor driving means is recognized, and outputting a motor stop command signal to the motor driving means after a lapse of a predetermined time. 2. A control device comprising: a rotational position detecting means for detecting a rotational position of the printing drum; and a control means recognizing that an abnormality has occurred by the abnormality detecting means, and a printing speed being equal to or higher than a specified value by the printing speed detecting means. Under the condition that
After outputting a motor deceleration command signal to the motor driving means, outputting a motor stop command signal to the motor driving means after a lapse of a predetermined time, outputting a motor low speed rotation command signal to the motor driving means after a lapse of a predetermined time, 2. The printing apparatus according to claim 1, wherein when the rotational position detecting unit detects that the printing drum has returned to the home position, the motor driving unit outputs a motor stop command signal to the motor driving unit. apparatus.