JP2001171221A - Stencil printing machine - Google Patents

Abstract

(57) [Problem] To be able to output a stable signal without being affected by light from a light source used for drying a printing paper by detection of a sensor for detecting a printing paper, and to prevent malfunction of a printing operation. . SOLUTION: A printing paper P after printing is sent to a dryer 3, and ink is cured and dried by light emission of a drying unit 17 from a light source. The printing paper P after printing is the paper detection sensor 20
Detects the transport state. The paper detection sensor 20 is disposed near the drying unit 17 and is disposed under the influence of light from the light source. The malfunction prevention circuit holds the detection signal of the paper detection sensor 20 during the charging period of the light source,
Since the value immediately before light emission of the light source is output, the influence at the time of light emission is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stencil printing machine that uses a stencil sheet made by stenciling, and dries and discharges ink that has passed through the perforations of the stencil sheet. The present invention relates to a stencil printing machine configured to detect and dry ink by irradiating light to prevent erroneous detection of an optical sensor.

[0002]

2. Description of the Related Art In a stencil printing machine, printing is performed by passing ink from a perforated stencil sheet into a printing sheet. In order to perform good continuous printing with this stencil printing machine, the passage or discharge state of printing paper immediately after printing is detected. Since the ink is not dried on the printing paper immediately after printing, an optical sensor that does not contact the printing paper is used.

[0003] The optical sensor is composed of a light-emitting portion that emits light in a visible light region or an infrared light region, and a light-receiving portion that receives light in a specific region. Also, the detection method is
There are a format for recognizing the presence of the print paper when the light is blocked by the print paper, and a format for recognizing the presence of the print paper by the light reflected by the print paper. This optical sensor is arranged near the conveyance path of the printing paper.

In a stencil printing machine, in order to promote drying of an ink after printing, an ink of a type which is cured by a chemical change due to light irradiation may be used. In this case, as a light irradiation device, a fixing device using a flash of a light source such as a xenon flash may be arranged at a stage subsequent to the printing unit. The xenon flash is relatively inexpensive, can sufficiently follow the printing speed, and can obtain strong power. Such an irradiation device is disclosed in, for example,
No. 2498. Further, an ink fixing device provided for improving print quality such as prevention of strike-through or bleeding of the ink of a printed matter is also arranged near the transport path in order to reduce the size of the entire printing apparatus.

[0005]

The light of the xenon flash used in the above-mentioned irradiation device has a wide emission wavelength range from the ultraviolet region to the infrared region, and covers almost the wavelength to which a general optical sensor responds. . For this reason, when an optical sensor for detecting the passage of the printing paper is mounted near the irradiation device, the optical sensor may react to the light of the xenon flash and cause an erroneous detection.

FIG. 5 is a timing chart for explaining this erroneous detection. Light emission charging is performed at predetermined intervals shown in (a) and light emission is performed in a short time as shown in (b).
As shown in (c), it is apparent that the optical sensor is affected at the time of this light emission and noise is mixed in at times t1, t2,..., T6. This erroneous detection hinders the normal operation of the printing press, causing printing errors and printing stoppage. Accordingly, ink, printing paper, stencil paper, etc. may be lost or maintenance may be required. Further, since such an irradiation device depends on the ink to be used, it is usually compatible with an option. In order to eliminate the above-mentioned noise mixing, a response when the irradiation device is connected and a response when the irradiation device is not connected must be performed each time.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a detection of a sensor for detecting a printing sheet is performed by a stable signal without being affected by light from a light source used for drying the printing sheet. It is an object of the present invention to provide a stencil printing machine which can output a stencil and can prevent a malfunction of a printing operation.

[0008]

In order to achieve the above object, a stencil printing machine according to the present invention comprises a printing unit for mounting a stencil sheet made on a printing drum for printing, and a printing unit for printing on the printing unit. An optical paper detection sensor that detects the conveyance state of the printing paper in a non-contact manner, and an ink image formed on the printing paper immediately after printing, which is provided near the paper detection sensor, and irradiates light from a light source. A drying unit for drying, and a malfunction prevention circuit for holding and outputting a detection state of the paper detection sensor during a charging period of a light source in the drying unit are provided.

The malfunction prevention circuit may be arranged inside the drying unit.

The malfunction prevention circuit includes a sample timing generation circuit that outputs a sampling signal for a time shorter than a charging cycle of the light source, a charging signal during a charging period of the light source provided in the drying unit, and the sampling signal. Is input, a sample timing circuit that outputs the sampling signal only during the charging period, a detection signal of the paper detection sensor, and a sampling signal of the sample timing circuit are input, and each time the sampling signal is input, And a sensor information holding circuit for holding a detection signal of the paper detection sensor.

Further, the drying unit including the malfunction preventing circuit can be configured to be detachable.

According to the above configuration, the transport state of the printing paper printed by the printing unit is detected by the paper detection sensor in a non-contact manner. The printed ink image is dried by irradiating light from a light source provided in a drying unit. Since the paper detection sensor and the drying unit are close to each other, the light of the light source can be easily erroneously detected by the paper detection sensor.
Here, the malfunction prevention circuit holds and outputs the detection state of the paper detection sensor during the charging period of the light source, so that even if light enters the paper detection sensor, the detection state immediately before light source emission is output. Reliability can be maintained. The drying unit including the malfunction prevention circuit is detachable from the printing press.

[0013]

FIG. 1 is a side view showing the configuration of a stencil printing machine according to the present invention. The stencil printing machine 1 includes a printing device 2
And a drying unit 3. The printing apparatus 2 includes a paper feed table 5 on which the printing paper P is stacked, a paper feeding roller 6 for feeding the printing paper P, a printing unit 7, and a paper discharging unit 8.

The printing means 7 prints on the printing paper P according to the principle of stencil printing. After the stencil sheet to be used is made by a stencil making means (not shown), the printing drum 1
0. The printing drum 10 has a cylindrical peripheral wall that is at least partially permeable to ink.
The motor rotates in the direction A by driving a motor (not shown). The stencil sheet is mounted on the outer periphery of the printing drum 10 with the leading end sandwiched by the clamp 11. Inside the printing drum 10,
An ink supply means 12 for supplying a fixed amount of ink to the inner peripheral surface of the peripheral wall is provided. The printing unit 7 uses UV ink using a photocurable resin that is cured by a chemical change of the ink due to light irradiation in order to promote drying of the ink after printing.

The printing drum 10 is provided with a press roller 13 opposed thereto. The printing paper P passes between the printing drum 10 and the press roller 13 due to the rotation of the paper feeding roller 6 and is printed.
Discharged to the side. After the printing is completed, the used stencil sheet is separated from the printing drum 10 by the plate discharging means and discharged.

The printing paper P printed by the printing means 7 passes through the drying unit 3 and is conveyed to the paper discharge tray 14. The drying unit 3 is configured to be detachable from the printing apparatus 2, and is mounted when using UV ink using the above-described photocurable resin. The drying unit 3 also includes a printing device 2
Belt 15 for transporting the printing paper P discharged from the printer
A suction unit 16 provided below the conveyor belt 15 for adsorbing the printing paper P to the conveyor belt 15;
And a drying unit control circuit 18 for controlling the operation of the drying unit 3.

The drying unit 17 has a width of, for example, 50 mm along the direction in which the printing paper P is transported, and continuously emits light to the printing paper P being transported. As the light source, the above-described xenon flash or the like is used. By this light emission, the ink is chemically changed and cured and dried.

In order to control the above-described series of printing and drying operations, a paper detection sensor 20 is disposed immediately after the printing drum 10. The sheet detection sensor 20 is configured by a non-contact sensor that faces the conveyance path of the printing sheet P and detects the printing sheet P immediately after printing, for example, an optical sensor that emits and receives light. The control means 30 includes a CPU, ROM, RA
M, etc., based on the detection signal of the paper detection sensor 20,
The setting of the paper feed timing, the response to a paper output jam error, and the overall operation of the stencil printing machine 1 are totally controlled.

As a general configuration of a stencil printing machine, a printing drum and a paper discharge portion are generally installed linearly with a paper discharge table due to functional restrictions such as paper discharge paper alignment. For this reason, it is not possible to provide a means for blocking the light emitted by the drying unit 17, and continuous light enters the paper detection sensor 20.

FIG. 2 is a block diagram showing the electrical configuration of the present invention. FIG. 2 shows a configuration of a malfunction prevention circuit (sensor unit circuit) 22 for preventing a malfunction of the sheet detection sensor 20 due to light emission of the drying unit 17.

The sensor unit circuit 22 is constituted by a logic circuit such as a logic element. The charge signal for light emission in the drying unit control circuit 18 is input to the sample timing gate circuit 24. The sample timing gate circuit 24 samples the charging signal based on the sample signal of the sample timing generator 25.

FIG. 3 is a timing chart showing the operation timing of the apparatus. In the drying unit 17, the minimum interval (min) of the charging time TA for light emission is 62.5 ms, and the light emission time TB is 1 ms. As described above, the light emission time TB ends in an extremely short time as compared with the charging time TA.
This operation is controlled by the drying unit control circuit 18. As shown in FIG. 3, the sampling interval in the sample timing gate circuit 24 is set to an interval sufficiently shorter than the charging cycle TA. In addition, sampling is not performed during a period TC (when charging is not performed) in which the charging signal is invalid.

The sensor information holding circuit 26 receives a detection signal of the paper detection sensor 20 and a sampling value of a charging signal. The sensor information holding circuit 26 holds the value of the detection signal of the paper detection sensor 20 at the time of charging. The sampling value of the charging signal is input to the gate terminal 26a of the sensor information holding circuit 26. Therefore, each time the value of the detection signal of the paper detection sensor 20 is input during the charging period, the value of the detection signal is updated and held.

Also, during the charging period (period TA in the figure), sampling is not performed, so that the value of the detection signal of the paper detection sensor 20 at the end of the charging period is kept held. By the way, if the sensor signal changes during the period TC (in a non-charging state) during which the charging signal is invalid (at the time of non-charging), it is necessary to wait until the timing (timing tB) at which the charging signal becomes valid (charging period). Outputs the value of the detection signal of the paper detection sensor 20 from the control unit.

The sensor signal output circuit 27 outputs the value of the detection signal of the sheet detection sensor 20 held in the sensor information holding circuit 26 to the control means 30.

On the control means 30 side, the paper detecting sensor 20
, The overall operation of the stencil printing machine 1 such as the setting of the paper feed timing, the response to the paper output jam error, the light emission timing of the drying unit, and the like are controlled. In this control, the detection signal of the paper detection sensor 20 is transmitted to the drying unit 1.
Since the influence of light emission at 7 (a change in value due to noise or the like) can be eliminated, various controls based on the detection signal can be stably executed without malfunction.

In the above-described embodiment, an example in which the paper detection sensor 20 is disposed near the printing drum 10 has been described. However, the invention is not limited to this. In addition, a similar effect can be obtained by applying the present invention to an optical sensor in a portion where malfunction due to light emission of the drying unit 17 is considered, such as a paper passing confirmation sensor 28 (see FIG. 1) disposed immediately after the drying unit 17. Can be.

Further, the present invention is not limited to a malfunction in which light enters the optical sensor, but can be applied to a portion where a sensor malfunction due to mixing of electrical noise at the time of discharge of a xenon flash is considered. By installing this device between the sensor and the CPU without changing the sensor, noise can be eliminated without changing the control of the printing press main body.

FIG. 4 is a diagram for explaining the attachment / detachment structure of the drying unit 3 including the malfunction prevention circuit 22. The drying unit 3 is connected to the printing device 2 via a connector 31. As shown in FIG. 4A, when the drying unit 3 is not connected to the printing apparatus 2, the short pin 32 is inserted into the connector 31. As a result, the detection signal of the paper detection sensor 20 is applied to the short pin 3 at the connector 31 portion.
2 to the control means 30.

When the drying unit 3 is connected to the printing apparatus 2, as shown in FIG.
Is input to the malfunction prevention circuit 22 of the drying unit 3 through the connector 31 and the malfunction prevention circuit 2
Control means 3 as a detection signal from which the influence of a malfunction is eliminated in step 2
Input to 0. FIG. 4C is a diagram showing a conventional configuration example for reference. As shown in FIG. 4, a detection signal of the paper detection sensor 20 is directly input to the control unit 30 without passing through the connector 31. Only the charging signal of the drying unit control circuit 18 of the drying unit 3 is input to the control means 30 via the connector 31.

[0031]

According to the present invention, when the optical paper detection sensor and the light source of the drying unit are disposed close to each other, the malfunction prevention circuit detects the detection state of the paper detection sensor during the charging period of the light source. This is a configuration for holding and outputting.
As a result, even when the light of the light source enters the paper detection sensor, the reliability of the detection signal can be secured without the paper detection sensor being affected by the light of the light source, and malfunction of the apparatus can be prevented. Become. The above effect can be obtained only by providing the malfunction prevention circuit between the control means for controlling the printing operation, and there is no need to change the control content of the control means. At the same time, it is possible to eliminate the influence of electrical noise generated when the light source emits light. In addition, there is no need to synchronize the drying unit and the stencil printing machine, and the drying unit can be manufactured regardless of the type of the stencil printing machine. In addition, since the stencil printing machine does not require modification by connecting a drying unit, the maintainability can be improved.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of a stencil printing machine according to the present invention.

FIG. 2 is a block diagram showing an internal configuration of a malfunction prevention circuit.

FIG. 3 is a timing chart for explaining the operation of the malfunction prevention circuit.

FIG. 4 is a diagram showing a detachable configuration of a drying unit including a malfunction prevention circuit.

FIG. 5 is a timing chart showing sensor error detection in the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Stencil printing machine, 2 ... Printing apparatus, 3 ... Drying unit, 5
... Sheet feeding table, 6 ... Sheet feeding roller, 7 ... Printing means, 8 ... Sheet discharging means, 15 ... Conveying belt, 17 ... Drying unit, 18 ... Drying unit control circuit, 20 ... Paper detection sensor, 22 ... Failure prevention circuit (Sensor unit circuit), 24: sample timing gate circuit, 25: sample timing generator, 2
6 ... Sensor information holding circuit, 27 ... Sensor signal output circuit,
30: control means, P: printing paper.

Claims (4)

[Claims] A printing unit for mounting a stencil sheet made on a printing drum for printing, an optical paper detection sensor for detecting a transport state of the printing paper printed by the printing unit in a non-contact manner, A drying unit provided near the paper detection sensor and drying an ink image formed on printing paper immediately after printing by irradiating light from a light source; and detecting the paper during a charging period of the light source in the drying unit. A stencil printing machine comprising: a malfunction prevention circuit for holding and outputting a detection state of a sensor. 2. The stencil printing machine according to claim 1, wherein the malfunction prevention circuit is disposed inside the drying unit. 3. The malfunction prevention circuit includes: a sample timing generation circuit that outputs a sampling signal for a time shorter than a charging cycle of the light source; a charging signal during a charging period of a light source provided in the drying unit; and the sampling signal. Is input, a sample timing circuit that outputs the sampling signal only during the charging period, a detection signal of the paper detection sensor, and a sampling signal of the sample timing circuit are input, and each time the sampling signal is input, 2. The stencil printing machine according to claim 1, further comprising: a sensor information holding circuit that holds a detection signal of the sheet detection sensor. 4. The stencil printing machine according to claim 2, wherein the drying unit including the malfunction prevention circuit is detachable.