JP3746171B2 - Method and apparatus for detecting base paper in printing press - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for detecting a base paper in a printing press, and in particular, a method for detecting whether or not a base paper to be mounted on the outer peripheral surface of the drum in a printing press having a rotatable drum such as a stencil printing press is installed. It relates to the device.
[0002]
[Prior art]
Conventionally, a stencil printing machine or the like uses a stencil sheet (master) in which a film and Japanese paper are bonded together. A reflective optical sensor comprising an LED as a light emitting element and a photoelectric conversion element as a light receiving element that receives the reflected light of the area irradiated by the LED is mounted on the outer peripheral surface of the drum (plate cylinder). The presence or absence of the used base paper is detected.
[0003]
By the way, when the optical sensor is used, as shown in FIG. 4, when assembling individual sensors, a treatment provided with a reference reflector having a reflectance equivalent to that of the base paper and capable of being stably supplied. A sensor was set on the tool at a fixed distance d from the reflector, and the required output voltage of the sensor was obtained by adjusting the light emission amount on the light emitting side or the gain on the light receiving side. In this case, when adjusting on the light emitting side, as shown in FIG. 5, an electric current is passed through the LED that is the light emitting source, the fixed resistor R, and the variable resistor VR connected in series, and the adjustment of the variable resistor VR is performed. The required output voltage V _OUT was obtained from the light receiving portion made of a photoelectric conversion element.
[0004]
Alternatively, after incorporating the sensor into the printing press, the actual base paper was detected and adjusted for each unit to obtain a stable output voltage V _OUT .
[0005]
[Problems to be solved by the invention]
However, since the base paper obtained by laminating the film and Japanese paper is very thin and translucent, it is difficult to perform stable detection using an optical sensor. Moreover, conventionally, when determining the presence or absence of a base paper, as shown in FIG. 6, whether the output voltage level of the optical sensor when the drum is at a predetermined rotational position exceeds or does not exceed a predetermined detection reference level. Since the presence or absence of the base paper is determined, there is a disadvantage that the presence or absence of the base paper cannot be detected if the base paper is wrinkled or dirty.
[0006]
In addition, adjusting the optical sensor for each printing press is a very laborious operation, which increases the manufacturing time of the printing press and increases the product cost.
[0007]
Furthermore, by adjusting the sensors individually at the time of product shipment, the output voltage level is lowered due to the deterioration of the LED due to the paper dust peculiar to the printing press and the light emission lifetime of the LED. Sometimes happened. When this erroneous detection occurs, a service man or the like is called by the user each time to adjust or replace the optical sensor according to the current state of the product.
[0008]
In view of the above circumstances, the present invention enables stable detection of the presence or absence of a base paper mounted on the outer peripheral surface of the drum, facilitates sensor adjustment, and overcomes the influence of sensor deterioration. It is an object of the present invention to provide a detection method and apparatus.
[0009]
[Means for Solving the Problems]
A method for detecting the presence or absence of a base paper according to the present invention includes :
On the outer circumferential surface, a first detection reference position in the region is also not covered by the sheet during sheet mounted is set, on the outer peripheral surface, the second detection area covered by the base paper during sheet mounting using the drum the reference position is set,
The surface state at the first and second detection reference positions when the base paper is not mounted is detected by using a sensor, and the surface state at the first and second detection reference positions at that time is determined. Storing the first output difference of the sensor;
When detecting the presence or absence of the base paper, the surface state at the first and second detection reference positions is detected using the sensor, and the difference between the surface states at the first and second detection reference positions at that time is detected. To determine the second output difference of the corresponding sensor,
Based on the comparison of the first and second output difference, it is characterized in detecting the presence or absence of the base paper attached.
[0010]
The first and second detection reference positions are preferably provided with reflection reducing means such as an antireflection cloth.
[0011]
The first and second detection reference positions are preferably provided apart from each other along the rotation direction of the drum.
[0012]
The sensor is preferably an optical sensor that optically detects the surface state of the first and second detection reference positions.
[0013]
Next, an apparatus for detecting whether or not a base paper is mounted according to the present invention is as follows.
First reflection reducing means provided in a region not covered by the base paper even when the base paper is mounted on the outer peripheral surface of the drum;
Second reflection reducing means provided in a region covered with the base paper when the base paper is mounted on the outer peripheral surface of the drum;
An optical sensor capable of detecting a reflection state at a portion where the first and second reflection reducing means are provided;
The first output difference of the optical sensor according to the difference in the reflection state at the part where the first and second reflection reducing means are detected by the optical sensor when the base paper is not attached. Storage means for storing;
The second output difference of the optical sensor according to the difference in reflection state at the part where the first and second reflection reducing means detected by the optical sensor are detected when the presence or absence of the base paper is detected. Comparing means for comparing the first output difference with the first output difference;
Detection means for detecting the presence or absence of the base paper based on a comparison result by the comparison means;
It is characterized by having.
[0014]
It is preferable that the first and second reflection reducing means are provided apart from each other along the rotation direction of the drum.
[0015]
【The invention's effect】
According to the present invention, it becomes unnecessary to secure a margin more than necessary when detecting the presence or absence of a base paper, and it is possible to relatively determine the presence or absence of a base paper.
[0016]
Further, by performing the relative comparison, it is possible to set the adjustment range of the sensor to a loose range without setting a strict range as in the conventional case.
[0017]
Furthermore, there is an advantage that it is not necessary to consider the deterioration of the sensor by performing the relative comparison.
[0018]
In particular, by providing reflection reducing means such as an anti-reflective cloth at the first and second detection reference positions, even if the base paper is translucent, the contrast between the portion where the base paper is present and the portion where the base paper is not present can be obtained. It becomes large and it becomes easy to judge the presence or absence of the base paper.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a base paper detection method and apparatus in a printing press according to the present invention will be described in detail with reference to the drawings.
[0020]
FIG. 1 is a side view schematically showing a configuration of a stencil printing machine to which the present invention is applied. The stencil printing machine includes a document reading unit 1, a plate making unit 3, a stencil printing mechanism unit 5, and a plate discharging unit. 7, a paper feed unit 9, and a paper discharge unit 11.
[0021]
The document reading unit 1 includes a document setting table 21 on which a document to be printed is placed, reflection type document sensors 23 and 25 for detecting the presence or absence of a document in the document reading unit 1, a document transport roller pair 27, and A stepping motor 29 that rotationally drives the document conveying roller pair 27, a contact-type image sensor 31 that optically reads an image of the document and converts it into an electrical signal, and a document discharge tray 33 are provided.
[0022]
The plate making unit 3 performs perforating plate making on the stencil sheet R wound in a roll shape, and includes a thermal head 35 and a platen roller 37 that are aligned in a direction in which a plurality of heating elements penetrate the stencil sheet S. A pair of base paper transport rollers 39, a stepping motor 41 that rotationally drives the platen roller 37 and the base paper transport roller pair 39, and a base paper cutter 43.
[0023]
The stencil printing mechanism 5 includes a cylindrical drum 45 having an ink passage structure that can rotate around a central axis, a base paper clamp 47 provided on an outer peripheral surface portion of the ink non-passage area of the drum 45, An ink supply mechanism 53 including a squeegee roller 49 and a dock roller 51, a main motor 55 for rotating the drum 45 in the counterclockwise direction in FIG. 1, a press roller 59, and a solenoid device 61 for driving the press roller. And.
[0024]
The plate discharging unit 7 is configured to determine whether or not the stencil sheet S is present in the stencil conveying roller pair 65, the stencil conveying roller pair 65 that peels and conveys the used stencil sheet S from the drum 45 toward the stencil box 63. And a transmissive plate discharge sensor 69 for detection.
[0025]
The paper feed unit 9 includes a paper feed base 71 on which the print paper P is stacked and moved up and down, a pickup roller 73 that picks up the print paper P one by one from the paper feed base 71, and the rotation of the main motor 55 for pick-up roller 73, a paper feed clutch 75 that intermittently transmits to the paper 73, a paper transport roller pair 77 that feeds the print paper P between the drum 45 and the press roller 59 at a predetermined timing, and the presence or absence of the print paper P in the paper transport roller pair 77 portion. And a transmissive paper sensor 79 for detection.
[0026]
The paper discharge unit 11 includes a paper separation claw 81 that separates the printed printing paper P from the drum 45, and a paper discharge tray 83 on which the printed printing paper P is stacked.
[0027]
A magnet piece 85 is attached to the end of the drum 45, and the drum is positioned at the rotational position where the base paper clamp 47 is located directly above the main body side, that is, at the plate-starting rotational position. A plate-setting reference position sensor 87 constituted by a magnetic sensor that sometimes responds to the magnet piece 85 is fixedly arranged.
[0028]
Further, a rotary encoder 89 is connected to the main motor 55, and this rotary encoder 89 is reset by an output signal of the plate setting reference position sensor 87 to quantitatively detect the rotational position of the drum 45. ing.
[0029]
On the outer peripheral surface of the drum 45, an antireflection piece (reflection reduction) made of black sponge or the like is provided at an angular position that is never covered by the base paper S even when the base paper S is mounted on the outer peripheral surface of the drum 45. (Means) 91 is affixed to be a base position without base paper (first detection reference position). Further, when the base paper S is mounted at an angular position necessary for determining the presence or absence of the base paper S during the printing operation and the plate making operation, that is, in a state where the base paper S is mounted on the outer peripheral surface of the drum 45, the ink of the base paper S is impermeable. Anti-reflection pieces 93 are also affixed to the angular positions that are always covered by the region, and are used as base paper presence / absence detection reference positions (second detection reference positions).
[0030]
As shown in FIG. 2, the antireflection pieces 91 and 93 are affixed to both sides of the base paper clamp 47 along the rotation direction of the drum 45, and the angle between the base position without base paper and the base position detection base position θ is set in the range of 30 ° to 300 °, and the angle facing the rotation center of the antireflection piece 93 attached to the base paper presence / absence detection reference position is set in the range of 20 ° to 45 °.
[0031]
On the other hand, on the main body side, in a state where the drum 45 is located at the plate rotation start position as shown in FIG. 1 and FIG. An optical sensor 95 is fixed toward the outer peripheral surface of the drum 45. For example, as shown in FIG. 5, the optical sensor 95 includes a light emitting unit composed of an LED and a light receiving unit composed of a photoelectric conversion element, and is configured in a reflective type.
[0032]
Next, a method for detecting whether or not the base paper is attached to the drum 45 will be described.
[0033]
First, in a state where the base paper S is not mounted on the drum 45, the drum 45 is stopped at the plate rotation start position as shown in FIG. 1 and FIG. Opposite the optical sensor 95, the output voltage level of the optical sensor 95 at the reference position without base paper is stored as level 1 in FIG.
[0034]
Next, the drum 45 is rotated counterclockwise in FIGS. 1 and 2 by a predetermined angle, and the antireflection piece 93 provided at the base paper presence / absence detection reference position is opposed to the optical sensor 95 to detect the presence / absence of this base paper. The output voltage level of the optical sensor 95 at the reference position is obtained as level 2 in FIG. 3 and compared with the stored output voltage level of level 1, and the difference between both output voltage levels is obtained and stored.
[0035]
The operation states to be stored include all operations in which the drum 45 performs a low speed operation when the base paper is not loaded with a drum, that is, a confidential operation, a plate removal operation, a plate making operation, an auto idling operation, and the like. Thus, by confirming the state of no base paper in all operations, the cause of deterioration of the sensor 95 (due to paper dust or the like) can be ignored.
[0036]
Next, detection of whether or not the base paper S is attached to the drum 45 includes plate making operation (plate making), plate discharging operation, and printing in progress.
[0037]
That is, the output voltage level 3 at the base paper presence / absence detection reference position and the output voltage level 1 at the base paper absence reference position during the above operation are respectively obtained, and the voltage difference between the level 3 and the level 1 at that time is calculated in advance. The presence / absence of the base paper can be easily detected by comparing the voltage difference between level 2 and level 1 in the state where the base paper is not loaded with the drum.
[0038]
As described above, according to the present embodiment, it becomes unnecessary to secure a margin more than necessary, and it is possible to relatively determine the presence or absence of the base paper.
[0039]
In addition, by performing relative comparison, the adjustment range of the optical sensor 95 is set to a loose range where the difference is more than what V, without setting a strict range within a predetermined level ± 0.2V. Is possible.
[0040]
Furthermore, there is an advantage that it becomes unnecessary to consider the deterioration of the sensor 95 by performing the relative comparison.
[0041]
Furthermore, by providing reflection reducing means such as anti-reflective cloths 91 and 93 at the reference position without base paper and the reference position for detecting presence / absence of base paper, even when the base paper S is translucent, the base paper S is present. And the contrast when not present, and the presence / absence of the base paper is easily determined.
[Brief description of the drawings]
FIG. 1 is a side view showing a schematic configuration of a stencil printing machine to which the present invention is applied. FIG. 2 is an explanatory view of the main part of FIG. 1. FIG. FIG. 5 is an explanatory view of a conventional photoelectric sensor adjustment method. FIG. 5 is an explanatory view of a light emitting side adjustment method of the photoelectric sensor. FIG. 6 is an explanatory view of a conventional base paper presence / absence detection method.
DESCRIPTION OF SYMBOLS 3 Plate making part 5 Stencil printing mechanism part 35 Thermal head 37 Platen roller 39 Base paper conveyance roller pair 41 Stepping motor 45 Drum 47 Base paper clamp 55 Main motor 89 Rotary encoder 91, 93 Antireflection piece (reflection reduction means)
95 Optical sensor P Printing paper R Stencil paper

Claims (6)

A method for detecting whether or not a base paper is mounted on the drum in a printing machine having a rotatable drum on which a base paper is mounted on an outer peripheral surface,
As the drum , a first detection reference position is set in an area on the outer peripheral surface that is not covered with the base paper even when the base paper is mounted. using the detection reference position of 2 is set drum,
A surface state at the first and second detection reference positions when the base paper is not mounted is detected using a sensor, and the surface state at the first and second detection reference positions at that time is determined. Storing the first output difference of the sensor;
When detecting whether or not the base paper is loaded, the surface state at the first and second detection reference positions is detected using the sensor, and the difference between the surface states at the first and second detection reference positions at that time is detected. A second output difference of the sensor according to
Wherein the first and on the basis of a comparison of the second output difference, sheet detection method in a printing machine, characterized by detecting the presence or absence of the base paper attached.   2. The method according to claim 1, wherein reflection reducing means is provided at the first and second detection reference positions.   3. The method according to claim 1, wherein the first and second detection reference positions are provided apart from each other along a rotation direction of the drum.   4. A method according to claim 1, wherein the sensor comprises a reflective optical sensor. A device for detecting whether or not a base paper is mounted on the drum in a printing machine having a rotatable drum on which a base paper is mounted on an outer peripheral surface,
First reflection reducing means provided on a region of the outer peripheral surface of the drum that is not covered with the base paper even when the base paper is mounted;
Second reflection reducing means provided in an area on the outer peripheral surface of the drum that is covered with the base paper when the base paper is mounted;
An optical sensor capable of detecting a reflection state at a portion where the first and second reflection reducing means are provided;
A first output difference of the optical sensor according to a difference in reflection state at a portion where the first and second reflection reducing means are detected by the optical sensor when the base paper is not attached. Storage means for storing;
The second output of the optical sensor according to the difference in the reflection state at the part where the first and second reflection reducing means are detected by the optical sensor when detecting whether or not the base paper is mounted. Comparing means for comparing the difference with the first output difference;
Detection means for detecting the presence or absence of the base paper based on a comparison result by the comparison means;
A base paper detection device in a printing press, comprising:   6. The apparatus according to claim 5, wherein the first and second reflection reducing means are provided apart from each other along the rotation direction of the drum.

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