JPH07177312A - Image forming device and method therefor - Google Patents

Abstract

PURPOSE:To provide an image forming device capable of forming an image without need for moving a lens even when an original platen has a corner as the datum and the carrying of ADF has the center as the datum. CONSTITUTION:The image forming device provided with an automatic original carrying device for automatically carrying an original to an original platen is constituted of an illuminating lamp for exposing the platen, a CCD sensor 38 for outputting multi-valued picture data correspondingly to the intensity of reflected light from the platen exposed by the lamp, a line buffer 74a for storing picture data for the width direction of the platen which are outputted from the sensor 38, and a line buffer control circuit 74 for changing an effective picture data area and reading out picture data stored in the buffer 74a in accordance with the use or non-use of the automatic original carrying device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus provided with an automatic paper feeding device and an image forming method.

[0002]

2. Description of the Related Art A copying machine is known as an image forming apparatus equipped with an automatic document feeder (hereinafter, abbreviated as ADF: AUTO DOCUMENT FEEDER). Here, conventionally,
The relationship between the position set on the original, the ADF conveyance reference, the drawing position on the photosensitive drum, and the paper is as follows.

First, the document table is based on the corner, and the AD
When the conveyance standard of F is the corner standard, the drawing on the drum is the corner standard, and the paper conveyance is the corner standard. Secondly, when the document table is the center reference, the ADF conveyance reference is the center reference, the drawing on the drum is the center reference, and the sheet conveyance is the center reference. Also,
Thirdly, there is a system in which the original table is a corner reference, the ADF conveyance reference is a center reference, and the original reference is variable by moving the lens.

[0004]

In the above-mentioned first one, all the elements involved in the image reference are adjusted to the corner reference, and since the document conveyance and the sheet conveyance are biased to one side, abrasion is caused. However, there is a problem that deterioration and stains tend to be biased to one side, and the possibility of skew generally increases.

Further, in the above-mentioned second type, since the original must be placed by hand so that the center line of the original table and the center of the original sheet are aligned with each other, the image will be misaligned if it is not placed correctly, and the operation is performed. There was a problem of poor sex.

Further, in the above-mentioned third one,
It was necessary to provide a mechanism for moving the lens in the main scanning direction depending on the length of the paper width. Strictly speaking, there is a problem that the image forming position due to the lens movement must be optically corrected or compromised as a distortion error.

The present invention has been made in view of the above points, and an object thereof is to obtain an image without moving the lens even when the document table is a corner reference and the ADF conveyance reference is a center reference. An object is to provide an image forming apparatus and an image forming method capable of forming the image.

[0008]

An image forming apparatus according to a first aspect of the present invention is an image forming apparatus equipped with an automatic document feeder for automatically feeding a document to an original table, and an exposing means for exposing the original table. , Light receiving means for outputting multi-valued image data corresponding to the intensity of reflected light from the document table exposed by the exposing means, and image data in the width direction of the document table output from the light receiving means. Holding means for holding the data, and changing the effective image data area from the image data stored in the holding means when the automatic document feeder is used and when the automatic document feeder is not used. And a read-out means for reading out.

In the image forming method according to the second aspect, the image data in the width direction from the platen held by the holding means is used when the automatic document feeder is used and when the automatic document feeder is not used. The effective image data area is variably read so that the same image data format is provided when the automatic document feeder is used and when it is not used. .

An image forming apparatus according to a third aspect of the present invention is an image forming apparatus equipped with an automatic document feeder for automatically feeding a document to a document table, the exposing means exposing the document table, and the exposing means. Light receiving means for outputting multi-valued image data corresponding to the intensity of light reflected from the exposed document table, and widthwise image data from the document table output from the light receiving means are held. The holding means and the effective image data stored in the holding means when the automatic document feeder is used and when the automatic document feeder is not used.
It is characterized by comprising a reading means for changing and reading the data area and a print control means for changing the print start position according to the paper width and printing the image data read from the reading means. .

In the image forming method according to the fourth aspect, the image data in the width direction from the platen held by the holding means is used when the automatic document feeder is used and when the automatic document feeder is not used. The effective image data area is varied and read so that the same image data format is provided when the automatic document feeder is used and when it is not used, and the read image data is read. The printing start position is changed according to the width of the paper and printing is performed.

[0012]

In the image forming apparatus according to the present invention, the effective image data area is changed from the image data stored in the holding means when the automatic document feeder is used and when the automatic document feeder is not used. The read image data is read out by changing the print start position according to the width of the paper.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus according to an embodiment of the present invention will be described below with reference to the drawings. 1 is a control block diagram of a digital copying machine having an ADF function, FIG. 2 is a diagram showing a detailed configuration of a line buffer control circuit, FIG. 3 is a diagram showing a detailed configuration of a time difference buffer buffer control circuit, and FIG. FIG. 5 is a cross-sectional view of a digital copying machine having an ADF function, FIG. 5 is a view showing a state where an original is placed on a platen with reference to a center, and FIG. 6 is a state where an original is placed on an original with reference to a corner. FIG. 7 is a flow chart showing the overall operation of the digital copying machine, FIG. 8 is a view showing the format of image data stored in the line buffer, and FIG. 9 is a time difference buffer buffer. It is a timing chart for explaining operation.

First, the structure of a digital copying machine with an ADF function will be described with reference to FIG. In this digital copying machine, when the ADF function is used, the original is placed on the original table based on the center, and when the original is manually set on the original table, the original is placed on the original table based on the corner. To be done. In FIG. 4, reference numeral 1 is an ADF (automatic document feeder). An ADF tray 2 on which an original is placed is placed on the upper end of the ADF 1.
Is attached. A document D is placed inside the ADF1.
A conveyor belt 3 that conveys is provided. A reversing roller 3a and a flapper 3b are provided at the end of the conveyor belt 3. Further, the discharge tray 3 is provided on the upper part of the ADF 1.
c is provided. A sensor (not shown) for detecting whether the document D is placed on the ADF tray 2
Is provided.

Reference numeral 10 denotes an original table on which an object to be read, that is, an original D is placed. Inside the document table 10 (below),
An illumination lamp 22 for illuminating the document D placed on the document table 10,
A reflector 24 that collects the illumination light generated from the illumination lamp 22 on the original D, and a first carriage 20 that reflects the reflected light from the original D toward a second carriage 30 (described later).
Are arranged.

The first carriage 20 incorporates a first mirror 26 that bends the reflected light from the document D. The first carriage 20 is movably arranged in parallel with the document table 10,
By a pulse motor (not shown) via a toothed belt (not shown), the platen 10 is moved in parallel along the document table 10.

The second carriage 30 includes the first carriage 20.
The second mirror 32 and the third mirror 34, which sequentially bend the reflected light from the original D that has been bent via the first mirror 26, are arranged at right angles to each other. The second carriage 30 is driven by the first carriage 20 by a toothed belt or the like (not shown) that drives the first carriage 20, and moves onto the document table 10 at a speed half that of the first carriage 20. Moved in parallel along.

Below the first carriage 20, in a plane including the optical axis of the light reflected by the second carriage 30, it is movably formed by a drive mechanism (not shown).
While giving the reflected light from the second carriage 30 a converging property, the moving lens itself forms an image of the reflected light at a desired magnification, and the reflected light focused through the lens 36. It has a CCD sensor 38 that performs photoelectric conversion and outputs an electric signal (the image of the document D is converted) to an image memory 72 described later.

The image forming unit 6 includes a light source, that is, a semiconductor laser 42.
And an optical device 40 for changing the intensity of the light from the laser 42 in accordance with the image information of the document D read through the reading section 4 and directing the light toward a recording medium, that is, a photoconductor. .

The optical device 40 includes a first lens and a first lens (not shown) for converging the laser light generated from the laser 42 and converting it into laser light having a substantially circular cross-sectional shape. An optical deflecting device 44 for deflecting the light converted into laser light having a circular cross-sectional shape along the axial direction of the photoconductor described later, the deflected laser light being desired on the photoconductor described below. Second lens 46 for matching the deflection angle of the laser light and the distance from the optical axis on the photoconductor to the position where the beam is to be imaged, in order to form images sequentially at the positions It contains a Mira-48 that folds the light back toward the photoreceptor.

An optical device 40 is provided approximately at the center of the image forming section 6.
A recording medium, that is, a photoconductor 50, on which an electrostatic latent image (image) is formed, is arranged by the laser light from. A charging device for charging the photoreceptor 50 with a predetermined electric charge around the photoreceptor 50.
52, a developing device 54 for developing the electrostatic latent image formed on the photoconductor 50 by supplying a toner, and an AC for separating the transfer material, that is, the paper P fed from the paper cassette from the photoconductor.
A transfer device 56 that integrally has a voltage application device 56a and transfers the toner image formed on the photoconductor 50 to the paper P, and a charge characteristic of the photoconductor 50 while removing the charge distribution in the photoconductor 50. A cleaning device 58 for sequentially removing the residual toner and returning it to the initial state is arranged in order.

A position corresponding to the upstream side in the rotational direction of the photoconductor 50 and immediately below the photoconductor 50 is a built-in device for feeding a paper P, for example, copy paper or OHP sheet, toward the photoconductor 50. The formula paper cassette 14a is inserted. Further, at a position corresponding to the upstream side of the photoconductor 50 in the rotation direction, the photoconductor 50
A bypass tray 14b for feeding the sheets P of various sizes one by one is arranged on the right side of the sheet.

Between the photoconductor 50 and the paper cassette 14a,
Paper feed roller 61 for pulling out the paper P one by one from the cassette 14a
a, a paper feed roller 61b for feeding the paper P supplied from the bypass tray 14b, and a paper P pulled out via the paper feed roller 61a or 61b for feeding toward the photoconductor 50. A pair of conveying rollers 62, a feeding path 63 for feeding the paper P from the conveying roller 62 to the photoconductor 50, and a skew of the paper P are corrected and the toner on the photoconductor 50 is corrected. A pair of timing rollers 64 for aligning the leading edge of the image and the leading edge of the sheet P and feeding the sheet P at the same speed as the movement speed of the outer peripheral surface of the photoconductor 50 is arranged.

The toner image formed on the photoconductor 50 is transferred to a position corresponding to the downstream of the photoconductor 50 in the rotational direction, and the sheet P in which the toner is electrostatically attached is conveyed. A conveying device 66, a fixing device 68 that melts the toner transferred to the paper P by heating and fixes the toner on the paper P, and a pair of discharges that discharges the paper P having the toner image fixed to the outside of the device. It has a roller 16. To the left of the discharge roller 16, a discharge tray 16a on which the paper P having the toner image fixed is stocked is arranged.

An operation panel A is provided on the upper surface of the digital copying machine as shown in FIG. 5 or 6, and is provided with a ten key, a start key, a paper selection switch and the like.

Next, a control block diagram of this digital copying machine will be described with reference to FIG. In FIG. 1, 71
Is a CPU (central processing unit) that controls the entire copying machine. The system bus 71a from the CPU 71 is connected with a ROM 72 for storing the control programs shown in the flowchart of FIG. 7, a RAM 73 for storing various data, a lie buffer control circuit 74, and a time difference buffer buffer 75. There is.

The analog image signal from the CCD sensor 38 shown in FIG. 4 is output to the A / D converter 39 and converted into multi-valued image data. Further, the output of the A / D converter 39 is output to a shading correction / filter circuit 40 which performs shading correction and filter processing. The output of the shading correction / filter circuit 40 is output to the line buffer control circuit 74 as an input image signal. The line buffer control circuit 74 includes a line buffer that stores the image data of one line of the document placed on the document table 10 in the main scanning direction.

Further, the output of the line buffer control circuit 74 is output to the image processing circuit 76, subjected to various kinds of image processing, and then output to the time difference buffer buffer control circuit 75.
The time difference buffer buffer control circuit 75 absorbs the difference between the synchronization cycle of the image processing circuit 76 and the synchronization circuit of the laser drive circuit 77, and outputs it to the laser drive circuit 77. An image is drawn on the photoconductor 50 by the laser drive circuit 77.

Next, the configuration of the line buffer control circuit 74 will be described with reference to FIG. A RAM (random access memory) 74a used as a line buffer is connected to the line buffer control circuit 74. The line buffer 74a stores image data for one line in the main scanning direction of the document table 10 as shown in FIG. For example,
Image data is stored from the leading edge ld to the trading edge td of the document O in accordance with the center of the document table 10 as in the ADF.

That is, the length of the leading edge ld and the trading edge td of the document O is determined by the length of the document O in the main scanning direction. On the other hand, as shown in FIG. 6, when the original O is placed on the original table 10 with the corner as a reference, the leading edge ld of the original O is placed at the start position st of the line buffer 74a. Image data is stored, and the image data up to the trading edge td of the document O is stored.

The line buffer control circuit 74 can set the write address and the read address of the line buffer 74a to be variable. This is set by a control signal from the CPU 71. That is, the line buffer control circuit 74 stores the image data as shown in FIG. 5 in the case of the center reference when writing the image data in the line buffer 74a and in the case of the corner reference in FIG. As shown in, the image data is read from the start position st of the line buffer 74a.
Data is stored.

Then, the image data is output from the line buffer 74a.
When reading the data, if the center reference is as shown in FIG. 5, the image data from the reading edge ld to the trading edge td of the original O is read from the middle of the line buffer 74a. I have to.

On the other hand, in the case of the corner reference as shown in FIG. 6, the image data from the start position st of the line buffer 74a to the trading edge td of the original O is read out. There is. Therefore, the line buffer control circuit
The format of the image data read from the line buffer 74a of 74 has a common format as shown in FIG.

Next, the structure of the main part of the time difference buffer buffer control circuit 75 will be described with reference to FIG. In FIG. 3, 81 is reset by the horizontal synchronizing signal H from the CPU 71, decrements the preset count value Po at the timing of the input image clock signal CLK, and decrements "0".
The output control counter outputs the reset signal RESET to the output counter 82. The preset count value Po is set by the control signal CT1 from the CPU 71. The count value Po is set smaller when the size width of the document D is larger, and set larger when the size width of the document D is smaller.

The reset signal RESET output from the output control counter 81 is output to the output counter 82. This output counter 82 is reset by the reset signal RESET,
After that, the count value counted according to the image clock signal CLK is output as the address signal ADS of the buffer RAM 83.

The buffer RAM 83 stores image data in a common format as shown in FIG. 8 (A). Then, the image data read from the buffer RAM 83 is output to the laser drive circuit 77.

Next, the operation of the embodiment of the present invention constructed as above will be described. First, the type of key operated on the operation panel A is determined (step S1). If it is determined in step S1 that the "start" key has been operated, it is determined whether or not there is a document on the ADF tray 2 (step S2).

If the determination in step S2 is "YES", the leading edge ld and the leading edge td are set in the buffer control circuit 74 (step S3). That is, ld = Cn− (width of document D) / 2 is set as the read start position, and td = Cn + (width of document D) / 2
Is the read end position.

Then, referring to the paper size from the signal from the paper selection switch operated on the operation panel A, the photosensitive member is referred to.
50 drawing points Xst are obtained and set in the time difference buffer buffer control circuit 75 (step S4).

Thereafter, other setting processing is performed and the operation start processing is started (steps S5 and S6). That is, the analog image signal from the CCD sensor 38 is A / D
It is output to the converter 39 and converted into multi-valued image data. Further, the output of the A / D converter 39 is output to a shading correction / filter circuit 40 which performs shading correction and filter processing. The output of the shading correction / filter circuit 40 is output to the line buffer control circuit 74 as an input image signal.

In the line buffer 74a of the line buffer control circuit 74, as shown in FIG.
The image data for the line is stored. For example, image data is stored from the leading edge ld to the trading edge td of the document D in accordance with the center of the document table 10 like ADF.

That is, the lengths of the leading edge ld and the trading edge td of the document D are determined by the length of the document D in the main scanning direction. On the other hand, as shown in FIG. 6, when the document D is placed on the document table 10 with the corner as a reference, the leading edge ld of the document D is placed in the line buffer 74a at the start position st of the line buffer. Image data is stored, and the image data up to the trading edge td of the document D is stored.

When the image data is read from the line buffer control circuit 74, when the center reference is as shown in FIG. 5, the reading edge ld of the document D is read from the middle of the line buffer 74a. Trading edge
The image data up to td is read out.

On the other hand, in the case of the corner reference as shown in FIG. 6, the image data from the start position st of the line buffer 74a to the trading edge td of the document D is read out. There is. Therefore, the line buffer control circuit
The format of the image data read from the line buffer 74a of 74 has a common format as shown in FIG.

The image data is sent to the image processing circuit 76.
Then, after being subjected to various kinds of image processing, it is stored in the buffer RAM 83 of the time difference buffer control circuit 75. The output control counter 81 is set in advance with a count value Po that decreases as the size width of the document D increases and increases as the size width of the document D decreases.
When the image clock CLK is counted and Po is counted in the output control counter 81 as shown in (4), the reset signal RESET is output to the output counter 82, and the output counter 82 outputs the address signal ADS.

This address signal ADS is used as a buffer RAM
The image data as shown in FIG. 8 (A), which is output as a signal designating the address of 83 and is stored in the buffer RAM 83, is read by the laser drive circuit 77.

Then, by the laser drive circuit 77,
An image is drawn on the photoconductor 50. As described above, the corner reference platen and the center reference conveyance ADF can be used without a mechanical variable mechanism such as a lens variable mechanism or an optical correction mechanism, and without compromising the image distortion error. It is possible to provide an apparatus that can obtain the same image and has the advantages of the corner reference document table, the center conveyance reference, and the paper center reference. That is, the advantage of the corner reference document table is that it is easy to displace and place the document on anyone who puts it on the document table, and the advantage of the center transport standard ADF is that abrasion and deterioration are concentrated in the center, and skew during transport hardly occurs. As the paper center reference, drawing is performed with high accuracy in accordance with the paper transport position, so that image distortion does not occur.

In the above embodiment, the image data format read from the line buffer control circuit 74 is unified as shown in FIG. 8A, but effective image data is obtained as shown in FIG. 8B. The dummy data may be inserted in front of.

[0049]

As described above in detail, according to the present invention, a common image data format can be obtained even when the document table is the corner reference and the ADF conveyance reference is the center reference. When printing, the start position for drawing on the photoconductor is controlled according to the paper size, so the same image can be obtained with the corner reference document table and the center reference conveyance ADF.
It is possible to provide an image forming apparatus and an image forming method that have the advantages of the corner reference document table and the advantages of the center conveyance reference ADF.

[Brief description of drawings]

FIG. 1 is a control block diagram of a digital copying machine having an ADF function according to an embodiment of the present invention.

FIG. 2 is a diagram showing a detailed configuration of a line buffer control circuit according to the first embodiment.

FIG. 3 is a diagram showing a detailed configuration of a time difference buffer buffer control circuit according to the first embodiment.

FIG. 4 is a sectional view of a digital copying machine having an ADF function according to the embodiment.

FIG. 5 is a view showing a state in which a document is placed on a document table according to a center according to the embodiment.

FIG. 6 is a view showing a state in which a document is placed on a document table according to the corner reference according to the embodiment.

FIG. 7 is a flowchart showing the overall operation of the digital copying machine according to the embodiment.

FIG. 8 is a diagram showing a format of image data stored in a line buffer according to the embodiment.

FIG. 9 is a timing chart for explaining the operation of the time difference buffer buffer according to the embodiment.

[Explanation of symbols]

1 ... ADF, 2 ... ADF tray, 3 ... conveying belt, 71 ...
CPU, 72 ... ROM, 73 ... RAM, 74 ... Line buffer control circuit, 75 ... Time difference buffer buffer, 77 ... Laser drive circuit.

Claims (4)

[Claims] 1. An image forming apparatus equipped with an automatic document feeder for automatically feeding a document to a document table, comprising: an exposing means for exposing the document table; and an exposing means for exposing the document table from the document table. Light receiving means for outputting multi-valued image data corresponding to the intensity of reflected light, holding means for holding image data output from the light receiving means in the width direction of the platen, and the automatic document feeder. Image reading means for varying the effective image data area from the image data stored in the holding means when the automatic document feeder is not used and when the automatic document feeder is not used. Forming equipment. 2. The effective image data area of the image data in the width direction from the platen held by the holding means can be changed when the automatic document feeder is used and when the automatic document feeder is not used. The image forming method is characterized in that the same image data format is provided when the automatic document feeder is used and when the automatic document feeder is not used. 3. An image forming apparatus provided with an automatic document feeder for automatically feeding a document to a document table, wherein an exposing means for exposing the document table, and a device for exposing the document table from the document table exposed by the exposing means. Light receiving means for outputting multi-valued image data corresponding to the intensity of reflected light, holding means for holding image data in the width direction from the platen outputted from the light receiving means, and automatic document feeding Reading means for changing and reading the effective image data area from the image data stored in the holding means when the apparatus is used and when the automatic document feeder is not used; An image forming apparatus comprising: a print control unit that prints the image data by changing the print start position according to the paper width. 4. The effective image data area of the image data in the width direction from the platen held by the holding means is changed when the automatic document feeder is used and when the automatic document feeder is not used. When the automatic document feeder is used and when the automatic document feeder is not used, the same image data format is provided so that the read image data can be read according to the paper width. An image forming method characterized in that printing is performed by changing a print start position.