JPH0687551A - Plural plate feed detecting method for planographic printing plate - Google Patents

Abstract

PURPOSE:To enable the detection of plural plate feed by radiating laser beams to the side face of a printing plate, and after receiving the reflected light and converting it into electric output, detecting this output to judge the outputted time. CONSTITUTION:An uppermost printing plate 201 sucked by a suction pad 304 is lifted up to a position 304A from a position 304B in accordance with the ascent of the suction pad 304. During this ascent, the printing plate 201 crosses laser beams emitted from the sensor head 306 of a laser type photoelectric switch. At this time, in compliance with the time of the side face of the printing plate 201 crossing the laser beams, reflected light also enters the light receiving part of the sensor head 306 by the same corresponding time. The reflected light having entered the light receiving part in the sensor head 306 is converted into an electric signal, and the time of the laser beams being detected is judged by a plural plate feed judging circuit. In the case of judging plural plates, a plural plate detection alarm signal is sent to the control part of the whole processing device. Plural plate feed can be thereby prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a plurality of sheets in a plate making apparatus for a planographic printing plate, and more particularly, a method for detecting a plurality of sheets in a plate making apparatus for an electrophotographic planographic printing plate having a side surface coated with an insulating resin. Regarding

[0002]

2. Description of the Related Art Many methods for producing a lithographic printing plate are already known. For example, a printing original plate is brought into close contact with an original made of a silver salt film, and the photosensitive layer of the original plate is directly exposed to ultraviolet rays or the like,
This is a plate making method in which a cured portion corresponding to the image portion of the original and a non-cured portion corresponding to the non-image portion are formed, the non-cured portion is washed and removed with alkali or water, and the cured portion is made ink-receptive. . The printing plate produced by this method is called P
It is called S version and is widely used.

On the other hand, due to advances in computer image processing technology, memory development of large-capacity data, and data communication technology, etc., in recent years, a computer is consistently operated from original input, correction, editing, layout to page setting, and a high-speed communication network. An electronic editing system that can output to an end plotter at a remote place by satellite communication is being put to practical use. In particular, in the field of newspaper printing where immediacy is required, not only electronic editing systems but also plate making systems that can directly obtain a printing plate from the data are being put to practical use. Currently, in such a plate-making system, a system using an electrophotographic process and exposing with a laser light source (semiconductor laser, He-Ne laser, etc.) is being studied from various aspects.

In such a system, an elution type electrophotographic lithographic printing plate as described below can be used advantageously because it can be printed under the same printing conditions as the PS plate used conventionally. it can. As the main plate making process, the printing plate is charged, exposed, and developed, an image is formed with toner, the non-image portion where the toner does not adhere is removed with an eluent, and the surface of the support that has been previously hydrophilized Exposed to make a printing plate. Here, since the image portion protected by the toner is lipophilic, offset printing can be performed.

The electrophotographic lithographic printing plate is prepared from an electrophotographic photoreceptor in which a photoconductive layer containing a photoconductive substance is coated on a conductive support such as aluminum. Examples of the material forming the photoconductive layer of this electrophotographic photoreceptor include JP-B-37-17162, 38-758 and 46-3.
9405, JP-A Nos. 52-2437 and 57-161.
863, 58-2854, 58-28760
No. 58-118658, No. 59-12452,
59-49555, 62-217256, 6
Organic photoconductive compound / binder resin materials such as those described in JP-A-3-226668 and JP-A-1-261569 are excellent in practical sensitivity and printing durability.

In the plate making process of the electrophotographic lithographic printing plate,
On the photoconductive layer of the electrophotographic photosensitive member, a predetermined charging process is first performed to apply a uniform charge. The exposure then forms an electrostatic latent image corresponding to the image. Then development and fixing process using electrophotographic developer is performed,
A toner image corresponding to the electrostatic latent image is formed. The non-image areas other than the toner image are dissolved and removed (eluted) by an eluent containing an alkaline agent, etc., followed by washing with water or adjusting the apparent pH of the plate surface with an acidic rinse,
If necessary, a plate surface protective solution (protective gum solution) may be applied to obtain a final printing plate.

By the way, when a toner image is obtained by so-called reversal development in the above-mentioned developing process, a good image without fog and line thinning can be obtained due to its excellent developing characteristics. Recently, particularly high resolution and high quality image reproducibility are required, and a method for producing an electrophotographic lithographic printing plate by reversal development is a method that meets this quality requirement.

When reversal development is performed, first, in the exposure step, light is irradiated to a portion to which toner is to be attached, that is, an image area, and the potential of the light irradiated portion is attenuated to almost 0V. To be At this time, the portion where light irradiation is not performed, that is, the portion corresponding to the non-image portion, maintains the initial charging potential as it is. In the developing process area, a predetermined developing bias is applied between the electrode and the electrophotographic lithographic printing plate through the electrode filled with the liquid developer. In this case, as the toner particles in the developer, those having the same polarity as the electrophotographic planographic printing plate side charged by a predetermined method are used. In such a state, when the photoconductor having an electrostatic latent image is carried into the developing electric field in the developing process area, the toner particles in the developer are migrated to the photoconductor side by the developing electric field, which is a light irradiation portion. Toner particles are attached to the 0V portion of the photoconductor. At this time, the portion corresponding to the non-image area where the initial charging potential remains repels the toner particles, and the adhesion of the toner particles is avoided.

As a developer used for such reversal development, either a dry developer or a liquid developer can be generally adopted, but when a liquid developer is used, the toner particles are made fine. Therefore, high resolution and good image reproducibility can be obtained. The liquid developer is
A pigment (dye) or polymer particles are dispersed in a highly insulating medium, colored as necessary, and a charge control agent is added to this to impart a predetermined charge.

Further, in the reversal development, printing stains may occur on the side surface of the printing plate due to toner adhesion at the time of development. To prevent this, an insulating resin or the like is applied to the plate before plate making in advance. It is known that
3-178240, JP-A-4-22972, etc.).

[0011]

By the way, image data from a PS plate automatic plate making apparatus or a computer is
In an apparatus for directly making a printing plate including an electrophotographic reversal development process using a laser light source, a printing plate before the plate making is preliminarily stacked at a predetermined position on a dedicated table in a predetermined position in the apparatus. Mounting. Next, from this state, the plate feeding process of automatically supplying the plate to the exposing (or charging and exposing) process for each sheet is automatically performed. In such an apparatus, it is general that no interleaving paper or the like is inserted between each of the multiple printing plates before printing, which are stacked. As such a device, for example, "Newspaper Technology", No. 133 P16-23 (19
The computer direct plate making apparatus described in 90) and the like can be mentioned.

In the stacked printing plates before plate making in the apparatus as described above, the gap between the printing plates is exhausted by the air between the plates due to the weight of the plates to bring them into close contact with each other. As described above, the printing plates often come into close contact with each other and are fed. In particular, a printing plate coated with a resin or the like on the side surface for the purpose of preventing printing stains on the side surface is significantly generated due to the resin on the side surface. If such a multi-plate feeding occurs, it causes a problem such as a conveyance jam in a subsequent process.

In order to avoid the occurrence of the above problems,
Various mechanisms have been put into practical use for the purpose of preventing multiple-sheet feeding, but it has not been possible to completely prevent multiple-sheet feeding. Therefore, it was necessary to detect when multiple sheets were supplied and take appropriate measures. One of the methods is to use a proximity sensor, but if the support is a non-ferrous metal such as aluminum, the sensor sensitivity is low, so it must be used very close to the printing plate. However, there are problems such as that there is a limit to the number of sheets and the accuracy of determining whether one sheet is a single sheet is poor.

[0013]

The above object can be achieved by the following constitution of the present invention. A first aspect of the present invention is a step of supplying a stacked pre-processed printing plate to a next step in an apparatus for plate-making by exposing and developing a sheet-shaped planographic printing plate at least, and at least a semiconductor Means (A) for irradiating the side surface of the printing plate with laser light, means (B) for receiving the reflected light and converting it to an electric output, and means for detecting the electric output and determining the time during which the electric output is output. (C)
And a time period during which the laser light emitted from the means (A) is reflected by the side surface of the printing plate and the laser light is detected by the means (B) is determined by the means (C). Is. As the means (A) and the means (B) in the present invention, commercially available photoelectric switches using laser light and controllers related thereto can be used.

Further, the second invention according to the present invention is such that the lithographic printing plate is an electrophotographic lithographic printing plate having a photoconductive layer on a metallic support, and the developing treatment is an electrophotographic liquid reversal developing treatment. Is.

Furthermore, a third invention according to the present invention is the structure according to the second invention, which has at least an insulating resin layer on a side surface of the electrophotographic lithographic printing plate. The insulating resin used in the present invention is a polymer that holds a positive or negative charge by a charging means such as corona discharge, and the material thereof is not limited, and may be fluorine-based or silicone-based.

According to a fourth aspect of the present invention, in the step of supplying the stacked unprocessed printing plates to the next step, air placed opposite the side surface of the stacked unprocessed printing plates. It is the structure of the said 2nd invention and 3rd invention characterized by having an injection means.

The air jetting means in the present invention is a means for blowing compressed air to the side surface portion of the loaded printing plates and inserting air between the printing plates to prevent feeding of a plurality of sheets. The air pressure does not include 0 and it is higher than 10Kg / c
It may be in the range of m ² , and it is preferable that the injection port is narrowed to a diameter of 5 mm or less.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1, FIG. 2, and FIG. 3 schematically show a configuration example of a plate making device plate feeding section according to the present invention. In FIG. 2, the positioning pins 202 move to predetermined positions (202B state), and then the pressing members 203 move to predetermined positions (203B state), so that the printing plate 201 is pressed against the positioning pins 202. The distance between the positioning pin 202B and the pressing member 203B in the pushed state is set to be 0.5 mm larger than the dimension of the printing plate 201, so that the printing plate 201 is not stressed. This distance can be arbitrarily set within 1 mm, and a mechanism having a tolerance may be provided in the pushing member 203 so that the pushing force does not exceed a certain force.

Next, referring to FIG. 1, the printing plate pallet 1 is shown.
JIS 1050 aluminum sheets (0.
(3 mm thickness) is coated with a photoconductive layer using a metal-free phthalocyanine as a photoconductive material, and a side surface is coated with an insulating resin. A pair of coaxially attached suction pads 104 to 109 attached to the arm 103 descend (at positions 104B to 109B) and contact the surface of the printing plate 101, and suction is started to perform suction. Thereafter, compressed air is jetted from the air jet port 110 to the side surface of the printing plate 101. As a result, a gap is provided between each of the stacked printing plates to allow the infiltration of air. Next, the suction pad 1 closest to the side surface of the printing plate 101 on which the compressed air is jetted
Only for 04, the operation of raising and lowering (state of 104B) is repeated several times, and finally the suction pad 104
Is stopped at the raised position (the position of 104A). It is desirable that the position of the suction pad 104 be as close as possible to the side surface of the printing plate 101.
The distance between the suction pads 104 and 105 is preferably larger than the distance between other suction pads, for example, the distance between the suction pads 108 and 109, because stress on the printing plate 101 can be reduced. Further, with regard to the suction pad, there is a physical influence on the printing plate, and in the electrophotographic planographic printing plate, since it does not particularly affect the charging performance,
Although the elasticity of the pad itself is also required, it is desirable to have a mechanism (for example, ball joint, spring, etc.) having directional freedom in the pad mounting portion and the like. An air cylinder is preferably used as the means for moving the suction pad 104 up and down.

Next, description will be given with reference to FIG. The uppermost printing plate 201 sucked by the suction pad 304 is lifted as the suction pad 304 moves upward (from the position of 304B to the position of 304A). At the time of this rise, the laser light emitted from the sensor head 306 of the laser type photoelectric switch (LZ-151 manufactured by KEYENCE) is applied to the printing plate 305.
Crosses. At this time, the reflected light also enters the light receiving portion of the sensor head for the same amount of time as the side surface of the printing plate 201 crosses the laser beam.

FIG. 4 is a conceptual diagram of a multiple-plate feeding determination circuit. Laser light emitted from the sensor head 306 is reflected by the printing plate 201 and enters a light receiving portion (not shown) in the sensor head 306, is converted into an electric signal, and is passed through an amplifier unit 408 to a plurality of plate supply determination circuits. Is input to the counter section 404 of. In accordance with this input time, the counter unit 404 sends the numerical value (1) based on the signal from the clock unit 403 to the comparator 405. Comparator 405
Then, in advance, the thickness of one printing plate 201 and the printing plate 2
A comparison is made with the numerical value (2) from the constant part 406 in which the constant calculated from the rising speed of 01 is set.
When (1)> (2), it is determined that a plurality of sheets have been latched 407.
An electric signal is sent to the control unit of the whole plate making apparatus. On the other hand, when (1) ≦ (2), a signal for normal operation is sent from the latch 407.

In the case of the present embodiment, a plurality of sheets are detected when the printing plate is raised, but it is needless to say that a plurality of sheets are detected by the method according to the present invention even in a state where the printing plate is temporarily stopped after being raised and during conveyance to the next step. Detection is possible. The position of the sensor head is not particularly limited as long as it is a position where the side surface can be irradiated with the laser light and the reflected light can be received.

When a plural-sheet detection alarm is issued, for example, the plate-making operation is temporarily stopped, the printing plate is returned to the dedicated table again, and the operator is informed that the number of sheets is plural.
In order to take appropriate measures such as the above, such a sequence is built in the plate making machine in advance, and it is possible to prevent a plurality of sheets from being fed.

In the plate making apparatus of this embodiment, the printing plate supplied as described above is subjected to charging and exposing treatment in a charging and exposing step (not shown), and further electrophotographic liquid in a reversal developing step (not shown). Inverse development processing is performed.

[0025]

According to the present invention, it is possible to detect troubles such as jamming in the subsequent process by detecting even if a plurality of plates are fed in the plate feeding process in the plate making apparatus of the planographic printing plate. In particular, even when an electrophotographic planographic printing plate having a side surface coated with a resin or the like is used, it is possible to similarly prevent a plurality of plates from being supplied.

[Brief description of drawings]

FIG. 1 is a schematic side view of a plate feeding section of a plate making apparatus according to the present invention.

FIG. 2 is a schematic plan view of a plate feeding section of the plate making apparatus according to the present invention.

FIG. 3 is a schematic front view of a plate feeding section of the plate making apparatus according to the present invention.

FIG. 4 is a conceptual diagram of a multiple-plate feeding determination circuit according to the present invention.

[Explanation of symbols]

 101 Electrophotographic planographic printing plate (stacked state) 102 Printing plate pallet 103 Plate feeding arm 104A, B Plate feeding pad 105A, B 〃 106A, B 〃 107A, B 〃 108A, B 〃 109A, B 〃 110 Air jet 201 Electrophotographic planographic printing plate 202A, B Positioning pin 203A, B Pressing material 302 Dedicated stand 303 Plate feeding arm 304A, B Plate feeding pad 306 Sensor head 403 Clock part 404 Counter part 405 Comparator 406 Constant part 407 Latch part 408 Laser type photoelectric Switch (amplifier unit)

Claims (4)

[Claims] 1. A step of supplying at least a semiconductor laser beam to a next step of a stacked plate before processing in an apparatus for plate-making by exposing and developing a sheet-shaped planographic printing plate. A means (A) for irradiating the side surface of the printing plate, a means (B) for receiving the reflected light and converting the light into an electrical output, and a means (C) for detecting the electrical output and determining the output time. And a laser beam emitted from the means (A) is reflected by the side surface of the printing plate, and the time during which the laser beam is detected by the means (B) is determined by the means (C). A method for detecting multiple plate feeding of printing plates. 2. The planographic printing plate according to claim 1, wherein the planographic printing plate is an electrophotographic planographic printing plate having a photoconductive layer on a metal support, and the developing treatment is electrophotographic liquid reversal developing treatment. Multiple plate feeding detection method. 3. The method of detecting a plurality of lithographic printing plates as claimed in claim 2, wherein at least an insulating resin layer is provided on a side surface of the electrophotographic lithographic printing plate. 4. The method according to claim 2, wherein in the step of supplying the stacked unprocessed printing plates to the next step, there is provided an air jetting device installed so as to face a side surface of the stacked unprocessed printing plates. The method for detecting a plurality of lithographic printing plates as described in 3 above.