JPH06348073A - Laser plate making device - Google Patents

Abstract

PURPOSE:To easily adjust and hold the width of the front blank part of a photoconductive sheet member to be constant. CONSTITUTION:A leading edge detection means 20 detecting the leading edge part in the carrying direction of the photoconductive sheet member carried by a pair of carrying rollers and outputting a detection signal, a set means optionally setting a count value for keeping the width of the front blank part from the leading edge part of the photoconductive sheet member by a laser exposure means 62 constant according to the variance of the carrying speed of a carrying mechanism including a pair of carrying rollers, a front blank part time arithmetic means counting a some fixed periodic signal when the detection signal is inputted from the detection means 20 and transmitting a synchronizing signal for calculating the end position of the front blank part when the counted value becomes equal to the set count value and a host computer 108 transmitting a front blank part end signal to the exposure means 62 in fixed timing after the sychronizing signal is detected are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention sequentially conveys a photoconductive sheet member inside a device by a pair of conveying rollers.
The present invention relates to a laser plate making apparatus that makes a plate of an original image on a photoconductive sheet member by performing charging, laser exposure, development, and fixing, and particularly, a conveying speed of a conveying mechanism including a pair of conveying rollers of a main body of the laser plate making apparatus. The present invention relates to a laser plate making apparatus capable of easily adjusting and holding the front margin portion of a photoconductive sheet member to a constant width by correcting the wobble caused by the above.

[0002]

2. Description of the Related Art Conventionally, a laser plate making apparatus using an electrophotographic system has been widely used as one of plate making apparatuses. As a conventional example of this type of laser plate making apparatus, there is a plate making apparatus disclosed in, for example, Japanese Patent Laid-Open No. 62-125371.

FIG. 3 is a schematic diagram showing an example of the overall configuration of a laser plate making machine to which the present invention is applied.

As shown in FIG. 3, the laser plate making machine is provided with a paper feed cassette 12 on the right side of the main body 10 and a paper discharge tray 14 on the left side of the main body 10, and a photoconductive sheet as a material of the plate is shown in the figure. Transported from right to left. The broken line in the drawing indicates the transport path of the photoconductive sheet.

Inside the paper feed cassette 12, for example, a large number of photoconductive sheets each formed by coating a conductive sheet with a photoconductive layer sensitive to laser light are housed. Also, the bottom surface of the paper feed cassette 12 is not flat,
A slight step 12a is provided on the main body 10 side. Due to the step 12a, the photoconductive sheet is easily separated,
When the photoconductive sheets are taken out from the paper feed cassette 12, a plurality of sheets are prevented from being taken out in an overlapping manner.

On the other hand, the photoconductive sheets in the paper feed cassette 12 are taken out one by one by the supply roller 16 and sent to the conveying path. Side guides are provided on both sides of the entrance of the transport path to accurately adjust the widthwise position of the photoconductive sheet in the transport direction.

Further, a leading edge detecting sensor 20 for detecting the leading edge of the photoconductive sheet in the feeding direction along the feeding path,
A first conveying roller pair 22, a corona charger 24, a sheet supporting member 26, a second conveying roller pair 28, and a developing device 30 are sequentially provided.

The front end detection sensor 20 is composed of a light emitting / light receiving integrated type optical sensor provided on both sides of the conveyance path. When the light receiving portion detects that the light beam from the light emitting portion is cut off by the photoconductive sheet. , Detect the leading edge of the photoconductive sheet.

The detection signal of the tip detecting sensor 20 is used as the basis of various operation timings. The first transport roller pair 22 is driven to rotate by the DC motor 56.

The photoconductive sheet exiting from the first conveying roller pair 22 is charged with a positive electrostatic charge on its surface by a corona charger 24. The sheet supporting member 26 flatly supports the photoconductive sheet being conveyed. The surface of the photoconductive sheet on the sheet supporting member 26 is exposed by the laser exposure section 62.

The laser exposure unit 62 includes a semiconductor laser 64.
A polygon mirror 66 for scanning the laser light emitted from the semiconductor laser 64 in one direction, and a polygon mirror 66.
It is composed of an fθ lens 68 for keeping the scanning speed of the laser beam scanned by the laser light on a plane constant, and a reflection mirror 70, so that the laser beam reflected by the reflection mirror 70 is applied to the photoconductive sheet. It has become.

The semiconductor laser 64 is turned on (irradiated) / off (cut off) in accordance with binary image data showing black and white of a document (binary image) supplied by a floppy disk or the like (not shown). In this embodiment, the laser light is blocked at the pixel portion of the original image, and the positive electrostatic charge on the surface of the photoconductive sheet is left as it is. In addition, laser light is applied to the portion of the original image other than the pixels, and an electrostatic latent image is formed on the surface of the photoconductive sheet.

The photoconductive sheet exiting from the second conveying roller pair 28 passes through the developing device 30 filled with the developing solution in which the toner is melted. Since the toner is previously charged with a negative electrostatic charge, the negative toner is attached to the pixel portion of the electrostatic latent image formed on the photoconductive sheet, and the electrostatic latent image on the photoconductive sheet is adhered. Is developed.

The developing unit 30 is provided in the tank 72 and a lower portion of the tank 72, and a suction pump 7 for circulating the developing solution.
4. It has a developer discharge pipe 76 for spraying the developer from the suction pump 74 onto the photoconductive sheet.

Further, the developing device 30 includes a lower guide plate 78 provided below the transport path on the photoconductive sheet and gently bent along the transport path, and a lower guide plate provided on the transport path. The curved counter electrode 80, which is gently bent like 78, is provided with the lower guide plate 78 and the curved counter electrode 80.
The photoconductive sheet is designed to pass between the two.

The lower guide plate 78 is grounded,
A predetermined voltage is applied to the curved counter electrode 80 according to the polarity of the toner, and the lower guide plate 78 is provided in order to improve the developing efficiency.
A line of electric force is generated vertically between the curved counter electrode 80 and the curved counter electrode 80.

The photoconductive sheet that has passed through the developing device 30 is
A solvent (developing solution) is squeezed out by a squeezing roller pair 82 similar to the conveying roller pair, heated and dried from below by a panel heater 84 which is a heating means of the fixing unit, and further out of the main body 10 by a third conveying roller pair 86. The paper is conveyed and stored in the paper discharge tray 14.

On the other hand, a line flow fan 88 is provided above the developing device 30, and hot air from the line flow fan 88 on the conveying path immediately after the developing device 30 and the panel heater 8 are provided.
4 is sprayed onto the photoconductive sheet on 4 to dry the photoconductive sheet from above. This allows the photoconductive sheet after development to be quickly dried. Then, by being dried, the toner image (original image) is fixed on the photoconductive sheet. The line flow fan 88 is provided as an auxiliary element of the panel heater 84.

By the way, in such a plate making apparatus,
Formation of an electrostatic latent image of a document image on the photoconductive sheet by the laser exposure section is performed as follows.

That is, a laser light detection sensor (hereinafter referred to as a BD sensor) for detecting the scanning origin position of the laser light.
Sends a scanning origin position signal (hereinafter referred to as a BD signal), which is a synchronization signal for controlling the writing position for each laser scanning, to the host computer, and the BD signal causes the writing signal to be sent from the host computer. Laser light is turned on / off while scanning by a writing signal, and exposed (forms an electrostatic latent image on the photoconductive sheet).

Here, when writing (forming an electrostatic latent image) by scanning with laser light is performed, the writing start position (writing start position) is the tip of the photoconductive sheet due to structural factors of the plate making apparatus. Then, the photoconductive sheet is entirely exposed to laser light for a certain time from that point to form a front margin portion, and writing is started with the exposure scanning end position of the front margin portion as the writing position. The width of the front margin portion is defined to be a constant width (20 mm) from the tip of the photoconductive sheet according to the standard.

However, the assembling accuracy of the carrying mechanism including the carrying roller pair of the laser plate making apparatus varies from one plate making apparatus to another. Then, since the transport speed varies due to the variation in the assembly accuracy, it is difficult to adjust the front margin portion of the photoconductive sheet to a constant width, and the writing position also varies.

Furthermore, the conveying speed changes due to the abrasion of the conveying roller pair due to long-term use. Therefore, it is difficult to keep the front margin portion at a constant width.

As a result, there is a problem in that the precision of the front margin position control is lowered, and as a result the quality of the plate making is lowered.

[0025]

As described above, in the conventional laser plate making apparatus, there are variations in the carrying speed caused by variations in the assembly accuracy of the carrying mechanism of the laser plate making apparatus body to be used, and in the case of long-term use. Adjust the front margin of the photoconductive sheet to a certain width by changing the speed,
There was a problem that it could not be held.

The present invention has been made to solve the above-mentioned problems, and includes variations in the assembly accuracy of the transport mechanism including the transport roller pair of the main body of the laser plate making apparatus to be used, and changes in the transport roller pair over time. It is possible to easily adjust and hold the front margin portion of the photoconductive sheet member to a constant width by correcting the variation in the conveyance speed caused by the above, and thereby improve the front margin position control accuracy and improve the plate making quality. It is an object of the present invention to provide an extremely reliable laser plate making apparatus capable of performing the above.

[0027]

In order to achieve the above object, in the present invention, a photoconductive sheet member is sequentially charged by a pair of rotating conveying rollers, a charging means for sequentially charging the photoconductive sheet member, and a photoconductive sheet member. The photoconductive sheet member is passed through a fixing unit including a laser exposure unit that exposes the conductive sheet member, a developing unit that develops the photoconductive sheet member, and a heating unit that fixes the photoconductive sheet member. In a laser plate making apparatus for producing a plate of an original image thereon, there is provided a leading edge detecting means for detecting a leading end portion in the feeding direction of a photoconductive sheet member fed by a feeding roller pair and outputting a detection signal, and a feeding roller pair. A count value for keeping the front margin portion from the leading end portion of the photoconductive sheet member by the laser exposure means to a constant width can be arbitrarily set according to the variation in the transport speed of the mechanism. When the detection signal from the fixing means and the tip detection means is input, a certain periodic signal is counted from that time, and at the time when the count value becomes equal to the count value set by the setting means. A front margin time calculating means for transmitting a synchronization signal for calculating the front margin end position, and a laser exposure means for outputting the front margin end signal at a certain timing after detecting the synchronization signal from the front margin time calculating means. And a host computer for sending to.

Here, in particular, as the certain periodic signal, the scanning origin position signal output from the laser light detecting sensor for detecting the scanning origin position of the laser light by the laser exposure means is counted. .

Further, in the above laser plate making apparatus, a latch means for latching a certain fixed periodic signal is added,
The latch signal from the latch means is counted by the front margin time calculating means, and the latch of the latch means is cleared every time the latch signal is counted.

[0030]

Therefore, in the laser plate making apparatus of the present invention,
The operator presets a count value for keeping the front margin portion of the photoconductive sheet member constant according to the variation in the transport speed of the transport mechanism including the transport roller pair of the laser plate making apparatus body to be used.

Next, when the leading end portion of the photoconductive sheet member conveyed by the pair of conveying rollers in the conveying direction is detected by the leading end detecting means and the detection signal is input to the front margin time calculating means, it is from that point. A constant periodic signal is counted. Then, when this count value becomes equal to the count value set by the setting means, at that time point, a synchronization signal for calculating the front margin end position is sent to the host computer.

Then, the host computer sends a front margin end signal to the laser exposure means at a certain timing after detecting the synchronization signal.

By changing and setting the count value in this way, the end position of the front margin portion can be easily adjusted, the assembly precision of the transport mechanism including the transport roller pair can be varied, and the transport roller pair can be adjusted. It is possible to correct the variation in the transport speed caused by the change with time and adjust and hold the front margin portion of the photoconductive sheet member to a constant width.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

Since an example of the entire structure of the laser plate making machine to which this embodiment is applied is the same as the conventional example shown in FIG. 3, its explanation is omitted here.

FIG. 1 is a block diagram showing a configuration example of a front margin position control device which is a feature of the laser plate making apparatus according to the present invention.

That is, the front margin position control device of this embodiment, as shown in FIG. 1, has the leading edge detection sensor 20, a switch 100 as setting means, a latch circuit 102, and
Parallel input / output circuits (hereinafter,
PIO) 104, central processing unit (hereinafter referred to as CPU) 106, and host computer 1
It is composed of 08 and.

Here, the leading edge detection sensor 20 detects the leading edge portion in the transport direction of the photoconductive sheet transported by the transport roller pairs 22, 28, 86 and outputs a detection signal VSYNC.

Further, the switch 100 is provided with a laser exposure unit 6 according to variations in the transport speed of the transport mechanism including the transport roller pairs 22, 28, 86 of the main body of the laser plate making apparatus to be used.
The count value for keeping the front margin portion of the photoconductive sheet by 2 in a constant width can be manually set by the operator.

Further, the latch circuit 102 is provided in the laser exposure unit 62, and is a certain periodic signal BD output from the BD sensor for detecting the scanning origin position of the laser beam by the laser exposure unit 62. The signal BD is latched and the latch signal LTBD is output.

The latch circuit 102 is provided in order to reliably capture the BD signal BD because the BD signal BD output from the BD sensor has a narrow pulse width.

On the other hand, the PIO 104 is a tip detection sensor 2
Detection signal VSYNC from 0, set count value from switch 100, latch signal LT from latch circuit 102
The BD, the clear signal CLR and the synchronization signal VSYNC from the CPU 106 are input, the clear signal CLR is output to the latch circuit 102, the latch signal LTBD and the set count value are sent to the CPU 106, and the LTBD synchronization signal VSYNC ′ is sent to the host computer 108. The input / output switching control is performed so that the output is output to.

When the latch signal LTBD from the PIO 104 is input, the CPU 106 counts the latch signal LTBD from that time point, and at the time point when this count value becomes equal to the set count value from the PIO 104, the front margin Sync signal VSYN for calculating the end position
It has a pre-margin time calculation function for sending C'and a clear function for outputting a clear signal CLR to the PIO 104 every time the latch signal LTBD is counted.

Further, the host computer 108 is
The front margin end signal VIDEO is sent to the laser exposure unit 62 at a certain timing after detecting the synchronization signal VSYNC ′ from the IO 104.

Next, the control operation of the laser plate making apparatus of the present embodiment having the above-mentioned structure will be described.

First, a count value for keeping the front margin portion of the photoconductive sheet at a constant width in accordance with the variation of the transport speed of the transport mechanism including the transport roller pairs 22, 28, 86 of the main body of the laser plate making apparatus used. When the operator sets in advance by the switch 100, the set count value is input to the PIO 104. At the same time, the laser exposure unit 6
The whole surface exposure scanning of the laser light by 2 is started.

Next, the leading edge of the photoconductive sheet transported by the pair of transport rollers 22, 28, 86 in the transport direction is detected by the leading edge detection sensor 20, and the detection signal VSYNC is output.
Is input to the PIO 104.

The BD circuit BD, which is a certain periodic signal output from the BD sensor for detecting the scanning origin position of the laser light by the laser exposure unit 62, is the latch circuit 1.
02, and the latch signal LTBD is PIO1.
It is input to 04.

Further, in the PIO 104, the set count value, the detection signal VSYNC, and the latch signal LTBD input as described above are input to the CPU 106, respectively.

On the other hand, in the CPU 106, when the latch signal LTBD is input from the PIO 104, the latch signal LTBD is counted from that time point. Then, when this count value becomes equal to the set count value from the PIO 104, the synchronization signal VSYNC ′ for calculating the front margin end position is sent to the host computer 108 at that time.

In this case, the CPU 106 outputs the clear signal CLR to the PIO 104 each time the latch signal LTBD is counted, and the clear signal CLR is input to the latch circuit 102 to clear the latch (see FIG. 2).

Then, from the host computer 108, the front margin end signal VIDEO is sent to the laser exposure unit 62 at a certain timing after detecting the synchronization signal VSYNC ', and at that time, the laser exposure unit 62 causes The exposure scanning of the front margin portion is completed.

In this way, the operator selects the switch 1 according to the variation in the transport speed of the transport mechanism including the transport roller pairs 22, 28, 86 of the main body of the laser plate making apparatus to be used.
By changing and setting the count value with 00,
The end position of the front margin part is adjusted, the variation in the assembly accuracy of the transport mechanism and the variation in the transport speed caused by the passage of time are corrected to adjust the front margin part of the photoconductive sheet to a constant width. Retained.

As described above, in this embodiment, the count value is changed and set according to the variation in the transport speed of the transport mechanism including the transport roller pairs 22, 28 and 86 of the laser plate making apparatus main body to be used. Therefore, the end position of the front margin part is adjusted to correct variations in the assembly accuracy of the transport mechanism and variations in the transport speed caused by changes over time, so that the front margin part of the photoconductive sheet can be easily moved to a constant width. Can be adjusted and held.

A latch circuit 102 which latches a BD signal BD, which is a certain periodic signal output from the BD sensor that detects the scanning origin position of the laser light by the laser exposure unit 62, and outputs a latch signal LTBD. Since the above is provided, even if the pulse width of the BD signal BD output from the BD sensor is narrow, it is possible to reliably capture the BD signal BD.

As a result, it is possible to prevent the writing start position from being varied by the scanning of the laser beam due to the variation in the transport speed, to improve the accuracy of the front margin position control, and consequently to improve the quality of the plate making. .

The present invention is not limited to the above embodiment, but can be implemented in the same manner as described below.

(A) In the above embodiment, the case where the present invention is applied to the laser plate making apparatus has been described, but the present invention is not limited to this, and the present invention is similarly applied to the same type of laser printer apparatus and optical plate making apparatus. It is possible to

(B) In the above embodiment, the case where the BD signal from the BD sensor that detects the scanning origin position of the laser beam by the laser exposure unit 62 is counted as a certain constant signal has been described. However, the present invention is not limited to this, and it is also possible to count some other fixed periodic signal.

(C) In the above embodiment, the case where the latch circuit 102 for latching the BD signal BD output from the BD sensor is provided has been described, but this may be provided as necessary and is necessary for the present invention. Not an essential element.

(D) In the above embodiment, as shown in FIG. 1, a BD generator 110 for generating the BD signal BD is provided as necessary so that the BD signal BD is output to the host computer 108. Host computer 10
The front margin end signal VIDEO from 8 is supplied to the BD generation unit 11
The signal may be sent to the laser exposure unit 62 in synchronization with the BD signal BD from 0.

[0062]

As described above, according to the present invention, the leading end detecting means for detecting the leading end portion in the carrying direction of the photoconductive sheet member carried by the carrying roller pair and outputting the detection signal, and the carrying roller pair are provided. Including a setting unit capable of arbitrarily setting a count value for keeping the front margin portion of the photoconductive sheet member by the laser exposure unit at a certain width in accordance with the variation in the transport speed of the transport mechanism, and the leading end detection. When a detection signal from the means is input, a certain periodic signal is counted from that time point, and at the time point when the count value becomes equal to the count value set by the setting means, the front margin end position is set. A front margin time calculating means for transmitting a synchronization signal for calculation, and a laser exposure means for outputting the front margin end signal at a certain timing after detecting the synchronization signal from the front margin time calculating means. Since it is configured to include a host computer for sending out to the photolithography machine, it corrects the variation in the assembly accuracy of the transport mechanism including the transport roller pair of the laser plate making apparatus main body to be used, and the variation in the transport speed caused by the change over time, and the photoconductive Provided is a highly reliable laser plate making apparatus capable of easily adjusting and holding the front margin portion of the flexible sheet member to a constant width, thereby improving the precision of the front margin position control and improving the plate making quality. it can.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a front margin position control device in a laser plate making apparatus according to the present invention.

FIG. 2 is a timing chart diagram for explaining an operation in the embodiment.

FIG. 3 is a schematic diagram showing an example of the overall configuration of a laser plate making machine to which the present invention is applied.

[Explanation of symbols]

10 ... Main body, 12 ... Paper feed cassette, 12a ... Step, 14
... Paper discharge tray, 16 ... Supply roller, 20 ... Tip detection sensor, 22 ... First conveying roller pair, 24 ... Corona charger, 2
6 ... Sheet support member, 28 ... Second conveyance roller pair, 30 ...
Developing device, 56 ... DC motor, 62 ... Laser exposure unit, 64
... semiconductor laser, 66 ... polygon mirror, 68 ... fθ lens, 70 ... reflection mirror, 72 ... tank, 74 ... suction pump, 76 ... developer discharge pipe, 78 ... lower guide plate,
80 ... Curved counter electrode, 82 ... Aperture roller pair, 84 ... Panel heater, 86 ... Third conveyance roller pair, 100 ... Switch,
102 ... Latch circuit, 104 ... PIO, 106 ... CP
U, 108 ... Host computer, 110 ... BD generation unit.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location G03G 15/00 301 H04N 1/04 104 Z 7251-5C

Claims (3)

[Claims] 1. A charging means for sequentially charging a photoconductive sheet member by a pair of rotating conveyance rollers, a charging means for exposing the photoconductive sheet member, and a photoconductive sheet. Developing means for developing the member,
And a laser plate making apparatus for making a plate of an original image on the photoconductive sheet member by passing through a fixing means having a heating means for fixing the photoconductive sheet member, and is conveyed by the conveying roller pair. The photoconductive sheet formed by the laser exposure unit according to the leading edge detection unit that detects the leading end of the photoconductive sheet member in the transport direction and outputs a detection signal, and the variation in the transport speed of the transport mechanism including the pair of transport rollers. A setting means capable of arbitrarily setting a count value for keeping a front margin portion from the tip end portion of the member at a constant width, and when a detection signal from the tip end detection means is input, a certain period from that point A synchronous signal for counting the desired signal and calculating the end position of the front margin when the count value becomes equal to the count value set by the setting means. A front margin time calculating means for transmitting a front margin time calculating means, and a host computer for transmitting a front margin end signal to the laser exposing means at a constant timing after detecting a synchronization signal from the front margin time calculating means. A laser plate making apparatus characterized by comprising. 2. The certain periodic signal includes:
2. The laser plate making apparatus according to claim 1, wherein a scanning origin position signal output from a laser light detection sensor that detects the scanning origin position of the laser light by the laser exposure unit is counted. 3. The laser plate making apparatus according to claim 1, wherein a latch means for latching the certain constant periodic signal is added, and the latch signal from the latch means is counted by the front margin time calculating means. A laser plate making apparatus characterized in that the latch of the latch means is cleared every time the latch signal is counted.