JPH0876522A - Image forming device - Google Patents

Abstract

PURPOSE: To provide an image forming device shortening time for multiple exposure and eliminating exposure deviation as for the image forming device fetching exposure start position data based on the following resolution before completing exposure based on the preceding resolution in the case of exposing by different resolution. CONSTITUTION: This image forming device possesses a moving means 42 moving a recording medium 2 and an exposure device 4 forming an electrostatic latent image by repeating exposure by the scanning line of the different resolution on the recording medium 2 for N times based on image information sent from a host device, and is provided with a storing means 19 storing position data specifying the exposure start position of Nth exposure by the different resolution in the image information or an exposure finish position before completing (N-1)th exposure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus such as a liquid developing electrophotographic apparatus, and particularly when exposing with different resolutions, before the exposure with the previous resolution is completed, the exposure start position with the latter resolution is reached. The present invention relates to an image forming apparatus that captures the movement data of the above.

Conventionally, in plate making in commercial offset printing, a developed silver salt film is used as a PS plate (Pre-sensitized Plate).
It was done by closely baking to
A so-called direct plate making apparatus has been proposed in which a plate material using a photosensitive material having a high sensitivity to a laser beam is exposed by a laser and developed.

In such an apparatus, there is a case where one plate material surface needs to be exposed with different resolutions such as a character portion and a photograph portion. Conventionally, one data is adjusted to the resolution of the other. A method of exposing with the same resolution, or a method of once exposing with one resolution and then exposing again with another resolution on the same plate material (called multiple exposure) is used.

As described above, in the method of exposing the character portion and the photograph portion at the same resolution, if the photograph portion is exposed at the resolution of the character portion, the photograph portion becomes a rough image, and if the character portion is exposed at the resolution of the photograph portion. However, the method of exposing twice with different resolutions has the drawback that it takes time and the image is likely to be misaligned because the same plate material is manually set twice.

In order to deal with this, a method of performing multiple exposure with a plurality of exposure units has been proposed. However, it is necessary to provide a plurality of exposure units, which makes the apparatus large and expensive. .

Therefore, there is a demand for a method capable of shortening the exposure process time with one unit and preventing exposure deviation.

[0007]

2. Description of the Related Art An automatic plate making apparatus has been proposed by the applicant of the present invention in Japanese Utility Model Laid-Open No. 4-112266, the outline of which will be described below.

FIG. 13 shows a part of the automatic plate making apparatus, in which 1 is a storage case for stacking a plurality of plate materials (hereinafter referred to as works) 2a and 3 is a pickup device,
4a is an exposure device, 5 is a developing device, 6 is a drying unit, and 7 is a fixing unit.

The exposure device 4a includes a charger 40 and a polygon mirror.
It is composed of a scanning optical system such as 41, a table 42a, and a laser irradiation device (not shown). The work 2a is a plate material in which a surface of an aluminum plate is coated with a photosensitive material having high sensitivity to a laser beam.

The developing device 5 includes a developer 50 on the surface of the work 2a.
And a liquid recovery tray 52 for recovering the developer 50, an electrode plate 53, a ground terminal 54, and the like.

With this structure, the work 2a in the storage case 1 is supplied onto the transfer line by the pickup device 3, sent to the exposure device 4a, and set on the table 42a. Then, based on the exposure recording information sent from a host computer (hereinafter referred to as a host) (not shown), the exposure mechanism including the laser irradiation device, the charger 40, the polygon mirror 41, etc. is driven, and the table 42a displays the resolution. (Eg 454 DPI (dots / inch),
681 DPI, 909 DPI), and the laser beam from the laser irradiation device is irradiated as scanning light by the rotating polygon mirror 41 to form an electrostatic latent image on the surface of the work 2a.

The work 2a on which the electrostatic latent image is formed is conveyed to the developing device 5, a predetermined bias voltage is applied to the work 2a whose back surface is in contact with the ground terminal 54, and the developer 50 is supplied to the exposed surface. Are uniformly wetted, and toner is attached to the electrostatic latent image on the work 2a for development.

The developed work 2a is passed through a drying section 6 and a fixing section 7, a cooling device (not shown), an elution device for etching a portion where toner is not adhered, and a gum portion is gummed for protecting the plate surface. Then, it is dried and the plate making process is completed.

Here, the structure of the exposure device 4a will be described in more detail. As shown in FIG. 14 (a), a belt mechanism 43 for conveying the work 2a in the direction of arrow A is provided so as to be movable up and down. The carrying surface is located above the upper surface of the table 42a (shown by the solid line in the figure) during the carrying, and is located below the upper surface of the table 42a (shown by the two-dot chain line in the drawing) during the exposure. An exposure mechanism 44 including a polygon mirror 41 is arranged above the belt mechanism 43.

As shown in FIG. 14B, the table 42a is provided with a plurality of suction holes 45 so that air is sucked from the suction holes 45 onto a suction box 46 connected to a vacuum pump (not shown). It is fixed. Work on table 42a
When 2a is positioned, air is sucked and the work 2a is placed on the table.
It is set by adsorbing to 42a.

The lower portion of the suction box 46 is screwed into a feed screw 47, and the feed screw 47 is connected to a servomotor (hereinafter referred to as a motor) M1 via pulleys P1 and P2 and a belt BL. Therefore, the table 42a is rotated by the forward / reverse rotation of the motor M1,
Move in the directions of arrows A and B. (Hereinafter, the direction of arrow A is referred to as the forward direction and the direction of arrow B is referred to as the reverse direction.) When the work 2a is a plate such as a newspaper, the work 2a has a size of two surfaces and the main scanning directions are opposite to each other with the same exposure data Is scanning.

In the case of multiple exposure, which will be described later, the table 42a is returned in the reverse direction by the reverse rotation of the motor M1. With this device, when making a plate such as a newspaper, Fig. 15 (a)
As shown in (b) and,
There are cases in which exposures with different resolutions are required, such as (in the article) and the photograph portion or the advertisement portion (in the article below).

In this case, a method of exposing one data to the resolution of the other and exposing it at the same resolution is used. However, for example, if the photograph portion is exposed at a low resolution of the character portion, the photograph portion is rough. There is a problem that it takes a long time to expose an image and a character portion at a high resolution of a photograph portion.

As another method, there is also performed a method of exposing "in the article" at one resolution and then multiple-exposure "below the article" at another resolution on the same plate material. This method includes a method of manually resetting the plate material to the origin of the table 42a and a method of automatically returning the table 42a to the origin and setting it.

The method of manually setting has the drawbacks that it is troublesome and that the same plate material is manually set twice so that an image is likely to be misaligned. A method of automatically returning the table 42a to the origin will be described below.

As shown in FIG. 16, when the "in-article" exposure on the work 2a is completed, the aperture is changed to change the dot diameter of the scanning light to the diameter of the resolution "under article", 2a is returned to the origin 0 of the table 42a, the dot period and the moving speed are changed for the resolution of "article below", and the work 2a is moved to the exposure start position of "article below",
Do the "under article" exposure.

Here, the resolution of "in article" is 454 DPI,
If the resolution of "under article" is set to 909 DPI, the dot diameter for "under article" will be 1
/ 2 times, the dot cycle is halved, and the moving speed of the workpiece 2a during exposure is also halved.

However, according to this method, since the work 2a is returned to the origin 0 of the table 42a again after the "in-article" exposure is completed, the movement distance becomes long, and thus the exposure process takes time. There is.

In order to deal with this, Japanese Patent Laid-Open No. 3-132775 "image forming apparatus" has been proposed. This method
This is a method of performing multiple exposure with a plurality of exposure units having different resolutions.

[0025]

According to the above-mentioned conventional method, the method disclosed in Japanese Patent Laid-Open No. 3-132775 requires a double exposure process, which requires a long time, and requires a plurality of exposure units. There is a problem that it becomes large and expensive.

It is an object of the present invention to provide an image forming apparatus capable of performing multiplex recording at different resolutions in a short time and in which exposure deviation does not occur.

[0027]

FIG. 1 is a block diagram showing the principle of the present invention (corresponding to claim 1). In the figure, 2
Is a recording medium, 42 is a moving means for moving the recording medium 2, and 4 is an electrostatic latent image formed on the recording medium by repeating exposure by scanning lines of different resolutions N times based on image information sent from a higher-level device. The exposure device 19 is a storage means for storing position data specifying the exposure start position or the exposure end position of the Nth exposure with different resolutions in the image information before the N-1th exposure is completed.

Therefore, the position data is stored in the storage means 19 before the (N-1) th exposure is completed. A problem when performing multiple exposure is the accuracy of the exposure start position of the (N-1) th exposure and the Nth exposure.
In order to improve the accuracy, the recording medium 2 may be returned to the origin of the exposure start at both the N-th exposure and the (N-1) th exposure, and idling may be performed from that position to the exposure start position. Then it takes extra time for the blank feed. Therefore, necessary position data is stored in the storage means 19.

The following are means corresponding to claims 2 to 5. In the second aspect, the moving means 42 is configured such that the exposure device 4 finishes exposing the recording medium 2 at the (N-1) th time,
The position data designating the exposure start position or the exposure end position stored in the storage means 19 is read out, and the recording medium 2 is moved in the forward direction or the reverse direction from the position where the predetermined approach amount is added to the position data.

According to a third aspect of the present invention, in the image forming apparatus, the position and storage means at which the (N-1) th exposure by the exposure device 4 is completed.
Based on the position data read from 19, the forward movement or the reverse movement corresponding to the smaller of the movement amount to the position to start the Nth exposure and the movement amount to the position to end the Nth exposure. Equipped with selection means for selecting direction movement,
The exposure device 4 is moved by the moving means 42 in the forward direction or the reverse direction selected by the selecting means to perform the Nth exposure.

In the fourth and fifth aspects, a predetermined time (in the fifth aspect, from the timing signal of the scanning line at the start of exposure)
The movement of the recording medium 2 by the moving means 42 is started after the elapse of (setting so that it comes to the center of the interval time of the timing signal).

The moving means 42 can also be realized by moving the exposure device 4 and the recording medium 2 relatively.

[0033]

In FIG. 1, the position data of the Nth exposure is stored in the storage means 19 before the N-1th exposure is completed, so that at the time when the N-1th exposure is completed, It is possible to immediately read the position data from the storage means 19 and relatively move to the corresponding position by the moving means 42 to start the Nth exposure. Therefore, the idle feed amount of the multiple exposure is reduced, the moving distance can be reduced, and the exposure process time can be shortened.

The following is the operation corresponding to claims 2 to 5. According to the second aspect, the exposure start position or the exposure end position read out from the storage means 19 is added to the position data which is added with a predetermined approach amount N in the forward direction or the reverse direction.
Since the exposure is performed after the movement speed is stabilized by starting the exposure of the second time, the deviation of the scanning line at the start position of the multiple exposure is prevented, and the accuracy of the exposure position can be improved.

According to a third aspect of the present invention, based on the position data designating the position at which the (N-1) th exposure is finished and the exposure start position or the exposure end position read from the storage means 19, the Nth exposure is made positive by the selecting means. Direction or the reverse direction, whichever has the smaller movement amount, is selected, and the Nth exposure is started in the selected forward direction or the reverse direction, whereby the idle feed amount can be further reduced and the movement distance can be shortened. In addition, the time of the exposure process can be shortened.

In the fourth and fifth aspects, after a predetermined time (in the fifth aspect, it is set so as to be located at the center of the interval between the timing signals) from the timing signal of the start of the scanning line, the recording medium 2 and the exposure are exposed. By starting the relative movement of the device 4, the main scanning and the sub scanning can be synchronized, the deviation of the scanning line at the start of the exposure can be prevented, and the accuracy of the exposure position can be improved.

[0037]

EXAMPLES Examples 1 to 3 in which the present invention is applied to an exposure apparatus of an automatic plate making apparatus described in the conventional example will be described below with reference to FIGS.
This will be described with reference to 12. The same reference numerals denote the same objects throughout the drawings. Examples 1 to 3 are cases of multiple exposure in the article (N-1) and the article bottom (N).

1) Description of Embodiment 1 FIG. 2 is a block diagram showing Embodiment 1 of the present invention (corresponding to claim 1, claim 2, claim 4 and claim 5), and FIG. 4 is a flowchart of Example 1, FIG. 4 is an explanatory diagram of Example 1, and FIG. 5 is a time chart of Example 1.

This case is the case of multiple exposure in the article and under the article. Therefore, in the case where N-1 is 1 and N is 2 in claim 1, etc. (the same applies to the second and third embodiments below). There is).

The work 2a and the article bottom exposure start / end position step number data (hereinafter referred to as the article bottom start / end step number) file 194 in FIG. 2 correspond to the recording medium 2 and the storage means 19 in FIG. 2 transfer control unit 170, drive circuit
21, the motor M1 and the table 42a correspond to the moving means 42 of FIG.

In the first embodiment, as shown in FIG. 4, exposure is performed by completely superimposing the inside of the article and the bottom of the article, and the exposure is performed while conveying in the forward direction. FIG. 2 shows only a portion related to the present invention. In the figure, 16 is a CPU, 17 is a ROM, 18, 19a is a RAM, 20 is an interface section, 21 and 22 are drive circuits, 23 is a BD sensor, and 24 is a Indicates a sensor amplifier.

The CPU 16 controls each part according to the control program stored in the ROM 17. The ROM 17 includes control programs such as the conveyance control unit 170, the exposure control unit 171, the reception control unit 172, a data conversion unit 173, and a return position calculation unit 174.
, Run-up amount table 175 and delay time table 176
It has.

The transfer control section 170 commands the drive circuit 21 to move the table 42a to control the transfer of the work 2a.
That is, based on the main scanning start timing signal sent from the exposure control unit 171, the table 42a is moved from the origin 0, the exposure in the article is completed, and the movement amount counter 194
When it stops at the article stop position S1 that has counted the end step number S1 in the article, the return position calculation unit 174 is notified, and the step number S4 of the calculation result returned from the return position calculation unit 174
After returning the table 42a up to, it is moved in the forward direction and stopped after the exposure under the article is completed.

When the movement of the table 42a is started, as shown in FIG. 5, the delay time is delayed with respect to the main scanning start timing signal (scanning light detection signal from the BD sensor 23) from the exposure controller 171. The movement is controlled to start after the time τ set in the table 176.

That is, in FIG. 5, the exposure start step number is set to be approximately at the center position of the scanning interval (for example, 1410 ms) of the main scanning timing signal (with delay time τ, about
Rotation of the motor M1 (that is, movement of the table 42a) is started for 0.7 ms), and steady rotation occurs after the rising time has elapsed. This is for synchronizing the main scanning and the sub-scanning and improving the accuracy of the exposure position. Therefore, the synchronization is performed at the start of exposure in the article and at the start of the exposure under the article.

The exposure control section 171 controls the exposure by instructing the drive circuit 22 to drive the exposure mechanism 44 including the BD sensor 23. That is, according to the exposure command, the data file 18
The in-article data of 0 and the in-article start / end step number file 193 read the in-article start step number, send a main scanning start timing signal to the conveyance control unit 170, and move the workpiece 2a on the table 42a on the table 42a. Exposure is started after receiving the detection signal of the BD sensor 23 after passing through the position based on the number of start steps (count by the movement amount counter 196). When exposure is completed, the data file under article 18
The data of 1 is read, and the work 2a moved to the exposure start position under the article is exposed.

When the reception control section 172 completes the reception of the image information in the article received from the host by the interface section 20, the reception control section 172 sends a reception completion notice to the host and sends a transmission request signal for the image information below the article. Start receiving below. It also controls the storage / reading of the received image information in the RAMs 18 and 19a and the data conversion. That is, the in-article data file 180 and the in-article data file 181 of the RAM 18 are the in-article data and the in-article data of the received in-article data, in-article start / end scanning number, and in-article data Storing / reading to / from the article start / end scan number and article bottom start / end scan number to / from article start / end scan number file 190 and article bottom start / end scan number file 191 in RAM 19a .

Further, the data conversion unit 173 is controlled to convert the start / end scanning number in the article into the step number of the motor M1,
The article start / end step number is stored / read in the article start / end step number file 193.

Also, the article bottom start / end scanning number is converted into the scanning line number of the resolution in the article, and as the second article bottom starting / ending scanning line number, the article bottom starting / ending conversion scanning number file 19
Store / read in 2.

The data conversion unit 173 converts the scanning number data into the number of steps of the motor M1 according to the resolutions of the scanning lines in the article and under the article, and the scanning number data under the article in the scanning line of the resolution in the article. Convert to a number.

When the return position calculation unit 174 receives the end-of-article notification from the conveyance control unit 170, it reads the approaching amount α from the approaching amount table 175, and the article read from the article start / end step number file 194. The position S2-α = S4 in which the amount of run-up α is added to the number S2 of lower start steps is calculated and sent to the conveyance control unit 70. That is, the table 42a is returned to the position of S4.

In the approach amount table 175, the approach amount α (the number of steps until the rotation of the motor M1 at the start of rotation is stabilized) is set with respect to the exposure start position under the article.
The delay time table 176 is a delay time τ for starting the movement of the table 42a with respect to the main scanning start timing signal.
Is remembered. The delay time τ is the resolution (that is,
The optimum value is set according to the moving speed of the table 42a) and the approach amount α.

The RAM 18 is provided with an in-article data file 180 and an under-article data file 181, and stores one page each of the exposure data in the article and the exposure data under the article. R
The AM 19a includes an article start / end scan number file 190, an article bottom start / end scan number file 191, an article bottom start / end conversion scan number file 192, an article start / end step number file 193, and an article bottom start / end step. Number files 19
4. A scanning line counter 195 and a movement amount counter 196 are provided.

The article start / end scan number file 190 and the article bottom start / end scan number file 191 are the article start / end position scan number and article bottom start /
The number of scans at the end position is stored.

Below article start / end conversion scan number file 192
Stores the number of scans converted by the data conversion unit 173 from the number of scans stored in the article bottom start / end scan count file 191.

Start / end step number file 193 in article
Stores the number of steps at the start / end positions in the article. The number of steps is 190 in the start / end scan number file in the article.
This is the value obtained by converting the number of scans stored in the number of steps in the data conversion unit 173 into the number of steps of the motor M1.

Below article start / end step number file 194
Stores the number of steps at the start / end position under the article. This number of steps corresponds to the number of steps counted by the movement amount counter 196, which will be described below, when the value counted by the scanning number counter 195, which will be described below, coincides with the value under article start / end conversion number of scans 192. Remember the value.

The scanning number counter 195 detects the start time of the scanning light based on the detection signal of the BD (Beam Detect) sensor 23 which detects the reflected light of the mirror provided near the end of the scanning. Count the number of exposure scan lines. Cleared before the exposure in the article and the exposure below the article.

The movement amount counter 196 counts up and down the steps of the motor M1 as the movement amount of the conveyed table 42a. The exposure mechanism 44 is a portion of the exposure apparatus 4a described in the conventional example, excluding the transport mechanism such as the table 42a.

Having such a structure and function, the operation will be described below with reference to the flow chart of FIG. 3 and the explanatory view of FIG. 4 (a). First, the work 2a is set at the origin 0 of the table 42a.

The in-article data sent from the host is stored in the in-article data file 180, the in-article start / end scan count is stored in the in-article start / end scan count file 190, and the in-article start / end scan count is immediately stored as data. The number of steps is converted by the conversion unit 173 and stored in the article start / end scan number file 193.

The article bottom data sent from the host is stored in the article bottom data file 181, and the article bottom start / end scan number is stored in the article bottom start / end scan number file 191, and the article bottom start / end scan number is immediately stored. The conversion unit 173 converts it into the article-converted scanning number (L2, L3) and stores it in the article bottom start / end conversion scanning number file 192.

In response to the exposure command, the in-article data, the in-article start scan number, and the in-article start step number are read out, and when the main scanning start timing signal is transmitted from the exposure control section 171, the transport control section 170 determines the delay time. The time τ is read from the table 176, the conveyance of the table 42a is started with a delay of the time τ from the timing signal, and at the same time, the movement amount counter 196 starts counting and receives the timing signal of the main scanning after the arrival of the start step number in the article. Then, the exposure of the data in the article is started and the count of the scanning number counter 195 is started.

Eventually, the count of the movement amount counter 196 reaches the end step number in the article and stops at the position of the step number S1 via the margin. During this time, the scanning counter 195
The values S2 and S3 of the movement amount counter 196 at the time when the value of and the value of the article below start / end conversion scan number file 192 match are stored in the article below start / end step number file 194.

Then, in response to the exposure end notification from the conveyance control unit 170, the return position calculation unit 174 reads the approaching amount α from the approaching amount table 175, and the start of article start / end of article start read from the step number file 194. Based on the number of steps S2, S2-α = S4 is calculated, and the number of steps S4 is sent to the transfer control unit 170.

The table 42a is returned to the position of the step number S4. After the movement amount counter 196 down-counts from S1 to S4, the article bottom data, the article bottom start scanning number, and the article bottom start step number S2 are read, and the table 42a is moved in the forward direction (the movement amount counter 196 counts. ) After exposure, the number of end-of-article end scans and the number of end-of-article end steps S3
After that, the movement of the table 42a is stopped. (Even at the start of this movement, the main scanning and the sub-scanning are synchronized by the time τ, but the description is omitted. The same applies to Embodiments 2 and 3 described later.) Next, a numerical example is shown in FIG. Will be described with reference to.

In the figure, after the run-up in the article (up to the position of 152 mm) from the origin 0 of the table 42a, the exposure in the article is started, and the stop position is passed from the exposure end position (the position of 493 mm) to the subsequent margin. Reach S1 (685mm position).

Before reaching this position, the article start / end step numbers S2 and S3 are stored. Stop position in the article
When S1 is reached, the number of steps S2 (212mm position) under the article stored previously is returned to the position S4 (212-20 = 192mm position) before by the running amount α (= 20mm) under the article.

Then, the table 42a is moved in the positive direction based on the previously stored article bottom data to perform exposure. 2) Description of Embodiment 2 FIG. 6 is a block diagram showing Embodiment 2 (corresponding to Claim 1, Claim 2, Claim 4 and Claim 5) of the present invention, and FIG. A flow chart, FIG. 8 is an explanatory diagram of the second embodiment.

The second embodiment of FIG. 6 is the first embodiment described with reference to FIG.
8 is that the bottom of the article is exposed in the opposite direction as shown in FIG. FIG. 6 shows only the parts relevant to the present invention. In the figure, 16a is a CPU, 17
a indicates a ROM.

The CPU 16a controls each part according to the control program stored in the ROM 17a. ROM17a is
Control programs for the transport control unit 170a, the exposure control unit 171, the reception control unit 172, etc., a data conversion unit 173, a return position calculation unit 174a, an approach amount table 175, and a delay time table.
It has 176.

The transfer controller 170a controls the transfer of the work 2a by instructing the drive circuit 21 to move the table 42a.
That is, based on the main scanning start timing signal sent from the exposure control unit 171, the table 42a is moved from the origin 0 after the time τ set in the delay time table 176, and the exposure in the article is completed, When stopped at the stop position S1 in the article, the return position calculation unit 174a is notified, and after the number of running steps of the calculation result returned from the return position calculation unit 174a has passed, the article is moved in the opposite direction until the exposure under the article is completed. .
Further, as in the first embodiment, the main scanning and the sub-scanning are synchronized by the time τ at the start of the movement for the exposure of the article.

When the return position calculation unit 174a receives the end-of-article notification from the conveyance control unit 170a, the number of end-of-article end steps
Based on S3, the running amount α ′ (see FIG. 8A) is calculated and sent to the transport control unit 170a.

Having such a structure and function, the operation will be described below with reference to the flowchart of FIG. 7 and the explanatory view of FIG. 8 (a). In this case, until the exposure in the article is finished and stopped, the procedure is completely the same as the steps 1 to 3 described in the first embodiment, so the description thereof will be omitted and the flow will be described.

The article bottom data, the article bottom scan number, and the article bottom step number S3 are read out, and while moving in the opposite direction, exposure is performed in reverse from the end of the article bottom data, and the article bottom scan number and article bottom start are performed. When the number of steps S2 is reached, the exposure under the article ends.

Next, a numerical example will be described with reference to FIG. In the figure, after starting from the origin 0 of the table 42a (up to the position of 152mm) in the article, exposure in the article is started, and after the margin from the exposure end position (position of 493mm) to the stop position S1 (685mm) Position). Before reaching this position, the numbers S2 and S3 of the start / end steps under the article are stored.

The movement of the table 42a is started in the reverse direction, and the article bottom data is exposed in the reverse writing direction from the position of the ending step S3 previously stored after the running amount α '. 3) Description of Third Embodiment FIG. 9 is a block diagram showing the third embodiment (corresponding to claim 1, claim 3, claim 4 and claim 5) of the present invention.
10 is a flowchart of the third embodiment, FIG. 11 is an explanatory diagram of the third embodiment, and FIG. 12 is an explanatory diagram showing a transfer determination table.

The third embodiment shown in FIG. 9 is the first embodiment described with reference to FIG.
The difference from the second embodiment described with reference to FIG. 6 is that the position where the exposure is stopped in the article is closer to the exposure start position and the exposure end position under the article, and the forward exposure or the reverse exposure is performed. It is determined whether or not the directional exposure is to be performed and then moved. In this case, even if the exposure in the article is finished, it is controlled so as to stop without moving to the end of the relevant surface of the work 2a.

FIG. 9 shows only the portion related to the present invention. In the figure, 16b is a CPU and 17b is a ROM. The CPU 16b controls each unit according to the control program stored in the ROM 17b.

The ROM 17b includes a control program for the transport control unit 170b, the exposure control unit 171, and the reception control unit 172, a data conversion unit 173, a forward / reverse direction exposure selection unit (hereinafter referred to as a forward / reverse selection unit) 174b, and a run-up amount table. 175, a delay time table 176 and a transfer determination table 177.

The transfer controller 170b controls the transfer of the work 2a by instructing the drive circuit 21 to move the table 42a.
That is, based on the main scanning start timing signal sent from the exposure control unit 171, the table 42a is moved from the origin 0 after the time τ set in the delay time table 176, and the exposure in the article is completed, When stopped at the stop position S1 in the article, the forward / reverse selection unit 174b is notified, and based on the movement step position S6 and the movement direction of the forward / reverse direction selection result and the calculation result replied from the forward / reverse selection unit 174b, the table is displayed. 42a
After moving, move in the selected direction until the exposure under the article ends. Further, similarly to the first and second embodiments, the main scanning and the sub-scanning are synchronized by the time τ at the start of the movement for the exposure of the article.

When the forward / reverse selection unit 174b receives the end-of-article notification from the conveyance control unit 170b, it is read from the stop position step count S1 and the article start / end step count file 194 counted by the movement amount counter 196. Based on the article underexposure start step number S2 and the article underexposure end step number S3, S2-S1 = Sa and S3-S1 = Sb are calculated, and the absolute value of Sa and Sb are compared. , Transfer determination table 177
First, the forward / reverse direction of the article under-exposure is determined by the determination method set in, and the run-up amount α is read from the run-up amount table 175.
Or Sb ± α) to move position S6 = S1 ± (Sa ± α or Sb ±
After obtaining α) (see FIG. 12), it notifies the transport control unit 170.

As shown in FIGS. 11 and 12, the transfer determination table 177 is a table in which the forward / backward direction of the article bottom exposure by the forward / reverse selection unit 174b, the adjustment amount of the running amount α, and the determination method of the number of movement steps are set. is there.

That is, FIGS. 11 (a) to 11 (d) show the relationship between the exposure positions in the article and below the article, and (a) to (d) in FIG.
It corresponds to 12 (a) to (d). Figure 11 (a) shows the case where the under-article exposure is performed at a slight distance after the in-article exposure is performed. Corresponds to a). (c) is the case where a part (less than half) of the exposure under the article overlaps the exposure position in the article.
(b) is the case where a part (more than half) of the exposure under the article overlaps the exposure position in the article. (d) is the case where all the exposures under the article overlap the exposure positions in the article.
Corresponds to (b).

As shown in FIGS. 12 (a) and 12 (b), when Sa <Sb, the exposure is performed in the positive direction. If the value of Sa is positive as shown in (a), S1 + (Sa−α ) = S6, the transport start position under this article
Move forward to S6. (However, this is the case when Sa> α, and when Sa <α, the direction is negative.) Therefore, from S1, Sa−
From position S6 advanced by α, conveyance for exposure in the positive direction is started.

If the value of Sa is negative as in (b), S1−
(Sa + α) = S6, and the article moves in the opposite direction to the article bottom transport start position S6. Therefore, from the position S6, which is returned by Sa + α from S1, the conveyance for exposure starts in the reverse direction.

Further, as shown in (c) and (d), Sa> Sb
In the case of, in the reverse direction exposure, if the value of Sb is positive, as shown in (c), S1 + (Sb + α) = S6, and the article moves to the forward direction at the article bottom transport start position S6. Therefore, from the position S6 advanced by Sb + α from S1, the conveyance for exposure starts in the opposite direction.

If the value of Sb is negative as shown in (d), S1- (S
b−α) = S6, and moves in the opposite direction to the article bottom transport start position S6. (However, this is the case of Sb> α, and Sb <α
When it is, the direction is positive. Therefore, the conveyance for exposure starts in the opposite direction from the position S6, which is returned by Sb-α from S1.

Having such a structure and function, the operation will be described below with reference to the flowchart of FIG. In this case, until the exposure in the article ends and the exposure is stopped, the first embodiment is performed.
Since it is exactly the same as that described in 1 to 3, the description thereof will be omitted, and the flow will be described.

The forward / reverse selecting unit 174b uses the article bottom start step number S2 and article bottom end step number S3 read from the article bottom start / end step number file 194, and the counted post-exposure stop position step in the article. S2 based on the number S1
-S1 = Sa and S3-S1 = Sb are calculated and the magnitude is compared, and Sa <
Depending on Sb or Sb> Sb, the transfer determination table 177 (FIG. 12) is referred to, the forward / reverse direction of the article bottom exposure is selected, and the number of movement steps in consideration of the approach amount α is obtained. Stop position number of steps
The number of movement steps is added to S1 to calculate the number of steps S6. (Therefore, when Sa = Sb, since forward and reverse may be in either direction, it is sufficient to decide in advance either direction.) When the positive exposure is selected, the table 42a to the position of the step number S6 After moving in the forward or reverse direction, read the article bottom data, the article bottom start scan number and the article bottom start step number S2, perform exposure while moving in the positive direction,
When the number of end-of-article end scanning and the number of end-of-article end step number S3 are reached, the exposure under the article ends.

When the backward exposure is selected, the table 42a is moved in the forward direction or the backward direction to the position of the step number S6, and then the article bottom data, the article bottom end scanning number and the article bottom end step number S3 are read out. Exposure is performed in reverse from the end of the article bottom data while moving in the opposite direction, and when the article bottom start scan number and article bottom start step number S2 are reached, the article bottom exposure ends.

In this way, it is possible to shorten the time required for the exposure process by reducing the idle feeding for the conveyance for the exposure in the article and under the article. That is, as in the first embodiment,
Although the inside of the article and the bottom of the article are conveyed in the same direction for exposure, only the table 42a is returned to the position where the approaching amount α is added to the exposure start position under the article.
The transport distance is shortened compared to the method of returning the bottom of the article to the exposure start position in the article.

Further, as in the second embodiment, when the article bottom is overlapped with the article, the exposure end position under the article is exposed in the opposite direction from the position in which the run-up amount α is taken into consideration. The transport distance is further shortened, and the exposure process time can be shortened. Further, as in the third embodiment, the forward / reverse direction of the exposure direction under the article is determined according to the positional relationship between the inside of the article and the article, and the shorter one of the transport distances is selected to further reduce the transport distance. Therefore, the time of the exposure process can be shortened.

Further, by starting the movement of the table 42a after τ time from the main scanning timing signal for starting the exposure, the main scanning and the sub scanning can be synchronized, and the accuracy of the exposure position can be improved.

In the above example, the case where the run-up amount α and the delay time τ are set at the start of the movement of the table 42a for the (N-1) th and Nth exposures in the case of multiple exposure has been described, but it is not multiple exposure. The same effect can be obtained when the movement of the table 42a for exposure in the case of (exposure with one type of resolution) is started.

[0096]

As described above, according to the present invention, in claim 1, the position data of the Nth exposure is stored in the storage means before the N-1th exposure is completed. , When the (N-1) th exposure is completed, the position data can be immediately read from the storage means to start the Nth exposure from the corresponding position. Therefore, the idle feed amount of the multiple exposure is reduced, the moving distance can be reduced, and the exposure process time can be shortened.

According to the second aspect of the present invention, the Nth exposure is started in the forward or reverse direction from the position where the predetermined starting distance is added to the position data designating the exposure start position or the exposure end position read from the storage means. Since the exposure is performed after the movement speed is stabilized, the deviation of the scanning line at the start position of the multiple exposure is prevented, and the accuracy of the exposure position can be improved.

According to a third aspect of the present invention, the N-th exposure is performed in the forward direction by the selection means based on the position data designating the position at which the (N-1) th exposure is completed and the exposure start position or the exposure end position read from the storage means. By selecting the one with the smaller movement amount in the reverse direction or the reverse direction and starting the Nth exposure in the selected forward or reverse direction, the jump feed amount can be further reduced and the movement distance can be reduced. Moreover, the time of the exposure process can be further shortened.

In claims 4 and 5, after a predetermined time has elapsed from the timing signal of the start of the scanning line (in claim 5,
The recording medium 2 is located at the center of the time interval of the timing signal).
By starting the relative movement of the exposure device 4 and the exposure device 4, the main scanning and the sub-scanning can be synchronized, the deviation of the scanning line at the start of the exposure can be prevented, and the accuracy of the exposure position can be improved. There is an effect.

[Brief description of drawings]

FIG. 1 is a block diagram of the principle of the present invention.

FIG. 2 is a block diagram showing a first embodiment of the present invention.

FIG. 3 is a flowchart of the first embodiment.

FIG. 4 is an explanatory diagram of the first embodiment.

FIG. 5 is a time chart of the first embodiment.

FIG. 6 is a block diagram of a second embodiment.

FIG. 7 is a flowchart of the second embodiment.

FIG. 8 is an explanatory diagram of the second embodiment.

FIG. 9 is a block diagram of a third embodiment.

FIG. 10 is a flowchart of the third embodiment.

FIG. 11 is an explanatory diagram of the third embodiment.

FIG. 12 is an explanatory diagram showing a transfer determination table according to the third embodiment.

FIG. 13 is a diagram showing a part of the automatic plate making device while omitting it.

FIG. 14 is a configuration diagram showing an exposure apparatus.

[Figure 15] Explanatory diagram in and below the article

FIG. 16 is an explanatory diagram of exposure in and under the article.

[Explanation of symbols]

2 is a recording medium, 2a is a work,
4, 4a is an exposure device, 19 is a storage means, and 19a is R
AM, 21,22 is a drive circuit, 42 is a transportation means,
42a is a table, 170, 170a and 170b are conveyance control units, 174 and 174a are return position calculation units,
174b is a forward / reverse selection unit, 175 is an approach amount table, 176 is a delay time table, 177 is a transfer determination table, 190
Is the article start / end scan number file, 191 is the article bottom start / end scan number file, 192 is the article bottom start / end scan number file, 193 is the article start / end step number file, and 194 is the article bottom start / End step number file,
M1 is a motor

Claims (5)

[Claims] 1. A moving device for moving a recording medium, and an exposure device for forming an electrostatic latent image on the recording medium by repeating exposure by scanning lines having different resolutions N times based on image information sent from a host device. An image forming apparatus including: and position data designating an exposure start position or an exposure end position of the Nth exposure with the different resolutions in the image information is stored before the N-1th exposure is completed. An image forming apparatus comprising a storage unit. 2. The moving means designates the exposure start position or the exposure end position stored in the storage means when the exposure device finishes the (N-1) th exposure of the recording medium. The image forming apparatus according to claim 1, wherein the position data is read, and the recording medium is moved in a forward direction or a reverse direction from a position in which a predetermined approach amount is added to the position data. 3. The image forming apparatus, based on the position data read from the storage unit and the position where the (N-1) th exposure by the exposure device is finished,
A selection means for selecting the forward movement or the backward movement corresponding to the smaller one of the movement amount to the position where the exposure of the first time is started and the movement amount to the position where the N-th exposure is ended, The exposure apparatus is moved by the moving means in the forward direction or the reverse direction selected by the selecting means,
The image forming apparatus according to claim 1, wherein the Nth exposure is performed. 4. The movement of the recording medium by the moving means is started after a lapse of a predetermined time from a timing signal of the scanning line at the start of the exposure.
The image forming apparatus according to claim 2 or 3. 5. The image forming apparatus according to claim 4, wherein the predetermined time is set substantially at a center of an interval time of the timing signal.