JPH04119066A - Picture forming device - Google Patents

Abstract

PURPOSE:To correctly adjust front end timing by transcribing the picture of a test chart to recording paper, and detecting relative positional relation by a detecting means from the recording paper, and adjusting the paper feeding timing of the recording paper to a photosensitive body by a paper feeding means based on a detected result. CONSTITUTION:The test chart is a pattern as shown in a figure, and it consist of a white part 31 being l1 in width at a front end side and a black part 32 at a rear end side. The position of a boundary between the white part and the black part of the picture of this test chart outputted by a printer part is detected by a position detecting sensor 12. Then, the front end timing is adjusted by controlling a resist solenoid 11 through an I/O 9 based on this detected result. When the front end of the white part of the test picture is detected by the sensor, counting is performed in order to measure the length of a part equivalent to the width l1 of the white part 31 of the test chart. The front end timing T is calculated by a specified formula based on a count value. The calculated front end timing T after adjustment is stored in a ROM 6.

Description

[Detailed Description of the Invention] Lt top side ll top! The present invention relates to image forming apparatuses such as digital electrophotographic copying machines and printers, and more particularly to automatic adjustment of images formed by such digital image forming apparatuses.

Moxibustion comes from Natsumi Mugi FIG. 6 shows a schematic configuration of a digital electrophotographic copying machine.

In this figure, a photoreceptor drum (46
), the main charging section (48), the developing section (50), the transfer section (44), and the separating section (45) are arranged along the rotational direction around the
) and a cleaning section (47) are provided, respectively. Then, the exposure section (49) on the photoreceptor drum (46)
) is irradiated with laser light emitted from the laser output section (38). By irradiating the laser beam, an electrostatic latent image corresponding to digital image data obtained by reading the original is formed on the photoreceptor drum (46). That is, the image of the document placed between the document table (40) and the document holding member (39) is read by scanning with an optical system,
The light receiving section (37) converts it into an electrical signal and then performs A/D conversion etc. to obtain digital image data, and the laser light output section (38) outputs laser light based on this digital image data. . Here, scanning of the original by the optical system is performed by moving the exposure unit (35) from left to right in the figure. At this time, the light receiving section (3
In order to maintain a constant optical path length up to 7), the mirror unit (36) is
are moving in the same direction at a speed of

The electrostatic latent image thus formed on the photoreceptor drum (46) becomes a toner image in the developing section (50), and this toner image is transferred onto recording paper in the transfer section (44). At this time, it is necessary to adjust the timing of feeding the recording paper to the photosensitive drum (46) so that the leading edge of the toner image on the photosensitive drum (46) and the leading edge of the recording paper coincide. For this purpose, in the copying machine shown in FIG. 6, the cassette (41)
or the pickup roller (71) from the manual feed tray (42).
), the feed roller (72), etc., for the purpose of adjusting the timing at which the leading edge of the recording paper reaches the photoreceptor drum (4B) (hereinafter referred to as "leading edge timing").
A registration roller (43) is provided in front of the photosensitive drum (46) in the conveyance path.

Further, instead of the registration roller (43), a pawl for stopping the recording paper fed by the feed roller may be protruded into the conveyance path. and,
Conventionally, the timing for starting the rotation of the registration rollers or the timing for releasing the pawl protruding into the conveyance path using a solenoid, etc., has been manually adjusted so that the leading edge of the toner image on the photoconductor matches the leading edge of the recording paper. I was adjusting. In other words, the resist is turned ON after the exposure of the leading edge of the document is started.
The leading edge timing is adjusted by manually adjusting the time until the registration roller starts rotating or the claw is released, and the leading edge of the toner image and the leading edge of the recording paper are aligned. However, such manual adjustment of the tip timing requires time, and there are problems in that the adjustment accuracy varies depending on the skill level of the operator.

On the other hand, in Japanese Patent Application Laid-Open No. 80-209454, a photoelectric element is arranged in the passage path of the copy material (recording paper), and the copy material (recording paper) on which a predetermined test chart is copied as shown in FIG. A copying apparatus has been proposed that detects the passing state with a photoelectric element and controls the sheet feeding timing (leading edge timing) to be adjusted based on the detection output. According to this copying device, the paper feed timing (leading edge timing) is automatically
is adjusted, the above problem is solved. However, this multi-military aircraft detects the passing state of the copy material that has been copied from the test chart, and determines the paper feed timing (leading edge timing).
It is assumed that there is no deviation in the scanning speed of the optical system during the adjustment. However, in reality, the scanning speed of the optical system may deviate due to manufacturing errors in the outer diameter of the pulley used to drive the optical system. Speed error affects this. Therefore, the paper feeding timing (leading edge timing) cannot necessarily be adjusted accurately.

On the other hand, regarding adjustment of the scanning speed of the optical system, Japanese Patent Laid-Open No. 64
No.-82064 proposes a copying apparatus capable of automatically adjusting the copying magnification in the exposure direction, that is, the scanning speed of the optical system. In this copying apparatus, a document as shown in FIG. 5, which has two brightness changing parts separated by a predetermined distance in the exposure direction, is copied onto transfer paper (recording paper).
A detection means installed in the conveyance path of the recording paper detects the light-dark change area on the transfer paper (recording paper), measures the passing time of two light-dark change areas separated by a predetermined distance, and calculates the passing time and the previously calculated area. The scanning speed of the optical system is automatically adjusted based on the ratio to the set reference time. Furthermore, in Japanese Patent Application Laid-Open No. 6482064, the scanning speed of the optical system is automatically adjusted by detecting the brightness changing area formed on the photoreceptor instead of detecting the brightness changing area on the transfer paper. Copying devices have also been proposed. However, the configuration of these copying devices aims to automatically adjust the scanning speed of the optical system (copying magnification in the exposure direction), and the timing of feeding the recording paper to the photoreceptor (
There is no mention of adjusting the tip timing (1).

``Oshi'' J1 Marushi-, L9ζtゑ11 When adjusting images in an image forming apparatus, manual adjustment work is time-consuming, and there are problems in that adjustment accuracy varies depending on the skill level of the operator, etc.
In contrast, copying apparatuses capable of automatic adjustment as described above have been considered. However, as already mentioned, in the automatic adjustment of the paper feeding timing (leading edge timing) described above, errors in the scanning speed of the optical system affect the adjustment accuracy. In addition, in the automatic adjustment in the above-mentioned copying machine, the paper feed timing (
Adjustment of the tip timing) and adjustment of the scanning speed of the optical system are considered separately.

Therefore, the present invention accurately adjusts the timing at which the recording paper is fed to the photoreceptor without being affected by the error in the scanning speed of the optical system, and also adjusts the timing at which the recording paper is fed and the scanning speed of the optical system. An object of the present invention is to provide a digital image forming apparatus that can simultaneously and automatically perform the following steps.

In order to achieve the above object, the image forming apparatus according to the first aspect transfers an image formed on a photoreceptor based on digital image data to a recording paper conveyed by a paper feeding means. In a digital image forming apparatus, a storage means for storing a predetermined test chart as digital image data; and detecting a relative positional relationship between an image of the predetermined test chart transferred to the recording paper and a leading edge of the recording paper. a detection means for forming an image of the predetermined test chart on the photoreceptor based on the digital image data stored by the storage means, transferring the image to recording paper, and transferring the image from the recording paper to the detection means; and a control means for controlling the relative positional relationship to be detected, and for controlling the feeding timing of the recording paper to the photoreceptor by the paper feeding means to be adjusted based on the detection result.

Further, in the image forming apparatus according to the second aspect, an image of a document placed on a document table is scanned and read by an optical system and converted into digital image data, and based on the digital image data, an image of a document is placed on a photoreceptor. In a digital image forming apparatus that forms an image on a sheet of paper and transfers the image to a recording paper conveyed by a paper feeding means, a predetermined test chart having two brightness/dark changes separated by a predetermined distance is stored as digital image data. a storage means for forming an image of the predetermined test chart on the photoconductor based on the digital image data stored by the storage means and transferring the image to a recording paper, the recording paper being used as a document for the above-mentioned test chart; When placed on the document table, the image on the recording paper is scanned and read by an optical system to obtain digital image data, and from the leading edge of the pattern represented by the digital image data to the brightness change area near the leading edge. A first distance defined as the distance between the two brightness changing parts in the pattern and a second distance defined as the distance between the two brightness changing parts in the pattern are calculated from the digital surface image data, and the calculated second distance and Adjusting the scanning speed of the optical system based on a distance ratio with a predetermined reference second distance, and correcting the calculated first distance based on the distance ratio to eliminate the influence of an error in the scanning speed. a control unit configured to control the feeding timing of the recording paper to the photoreceptor by the paper feeding unit based on the difference between the corrected first distance and a predetermined reference first distance; According to the image forming apparatus according to the first claim, an image of a predetermined test chart stored as digital image data is formed on a photoreceptor, and the image is transferred to a recording paper. transcribed into. Then, the relative positional relationship between the transferred image of the test chart and the recording paper is detected, and the timing of feeding the recording paper to the photoreceptor is adjusted based on the detected relative positional relationship. This corrects the misalignment between the leading edge of the image formed on the photoreceptor and the leading edge of the recording paper to which the image is transferred.

According to the image forming apparatus described in Item #2, an image of a predetermined test chart stored as digital image data is formed on the photoreceptor, and the image is transferred to recording paper. Then, when the recording paper is placed as a document on the document table, the image of the test chart on the recording paper is scanned and read by an optical system and converted into digital image data.

The pattern represented by this digital image data has two brightness/darkness changing parts, and the distance from the tip of this pattern to the brightness/darkness changing part near the tip, that is, the first distance, and the two brightness/darkness changes in this pattern. The distance between the parts, that is, the second distance is calculated from the digital l-image data.

Then, the scanning speed of the optical system is adjusted based on the distance ratio between the calculated second distance and a predetermined reference second distance. Here, since this distance ratio corresponds to the speed ratio between the current scanning speed and the reference scanning speed (it is the reciprocal of the speed ratio), the error in the scanning speed can be corrected by this adjustment. In addition, by correcting the calculated first distance based on the distance ratio, it is possible to remove the influence of the error in the scanning speed of the optical system, and the first distance after correction only eliminates the influence of the error in the tip timing. It is what you receive. Then, the tip timing is adjusted based on the difference between the corrected first [distance] and a predetermined reference first distance. Therefore, the tip timing shift can be corrected without being affected by the error in the scanning speed of the optical system.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the image forming apparatus of the present invention (hereinafter referred to as "Embodiment 1") will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the main structure of a digital copying machine embodying the present invention. In this figure, image data that is scanned by an optical system and converted into electrical signals by a sensor such as a COD is first converted into digital data by an A/D converter (1), and then subjected to shading correction. - Temporarily stored in line memory (3). During normal copy operation, the image data stored in the line memory undergoes image processing in the image processing circuit (4), and then is sent to the printer section (not shown) where the image is finally printed on recording paper. Output. Also, CPU (5), ROM (6)
.

A control section (20) is composed of the RAM (7) and the control section (20), and the control section (20) performs various controls based on input from the operation section (8) and the status of each part of the copying machine. Adjustment of the tip timing, which is one of the objects of the present invention, is also performed by this control section. That is, the digital image data of the test chart stored in the ROM (6) is sent to the line memory (3), and the image of this test chart is output by the printer unit via the image processing circuit (4). Here, the test chart has a pattern as shown in FIG. 3, and the width on the tip side is 9. The position of the boundary between the white part and the black part of the image of this test chart output by the printer unit is determined by the position detection sensor (12) ) is detected. Then, the tip timing is adjusted by controlling the registration solenoid (11) via the I/O (9) based on this detection result. Note that when adjusting the scanning speed of the optical system, the optical scanner motor controller (10) is controlled via l10 (9).

The adjustment of the tip timing in this embodiment will be explained below based on the flowchart of FIG. 2.

First, in step (#1), it is determined whether the mode is the leading edge timing adjustment mode or not, and if the mode is the leading edge timing adjusting mode, the process proceeds to step (#2). In step (#2), wait until the print key is turned on. When the print key is turned on, the digital image data of the test chart (Fig. 3) stored in the ROM (6) is read out and tested in the printer section. Output as an image (step #3). Then, if the tip of the white part of the output test image is detected by the sensor (if the sensor is turned on), the white part of the test chart (
Counting is started to measure the length of the portion corresponding to width 9 of 31) (steps #4 and #5). Thereafter, the process waits until the rear end of the white part (the boundary between the white part and the black part) of the test image is detected by the sensor (until the sensor is turned off) (step #6). Counting continues during this waiting period, and ends when the rear end of the white portion is detected (step #7). The count value at this time represents the width of the white portion of the test image, in other words, the relative positional relationship between the test image and the leading edge of the recording paper, and the leading edge timing is adjusted based on this count value. That is, in step (#8), the adjusted tip timing T is calculated using the following equation.

T=Ts + (C-C@)/Ni+
...■ However, T8: Tip timing before adjustment C: Count value while the white part of the test image passes the sensor (count value from step #5 to step #7) C0: Reference count value 1: Count value per unit time of tip timing. The adjusted leading edge timing T calculated by the above equation is stored in a nonvolatile memory in step (#9), and the processing in the leading edge timing adjustment mode is ended.

After executing the processing in the leading edge timing adjustment mode described above, the leading edge timing becomes T, and the misalignment between the leading edge of the recording paper and the leading edge of the toner image on the photoreceptor is corrected. In the above processing, the test image is based on the image data of the test chart stored in the ROM (6), so the scanning speed of the optical system has no effect. Therefore, even if there is a deviation in the scanning speed of the optical system, accurate tip timing adjustment can be automatically performed without being affected by this deviation.

The embodiment described above is an example in which the present invention is applied to a digital copying machine, but since the document reading section is not involved in the above-mentioned leading edge timing adjustment processing,
The present invention regarding leading edge timing adjustment can also be applied to an electrophotographic printer device.

Hereinafter, another embodiment (hereinafter referred to as "Embodiment 2") of the image forming apparatus of the present invention will be described with reference to the drawings.

In this embodiment, a digital copying machine is configured so that the leading edge timing and the scanning speed of the optical system can be adjusted simultaneously and automatically. The configuration of the main parts of this embodiment is almost the same as that of Embodiment 1 shown in FIG. 1, but in this embodiment, the position detection sensor (12)
is not necessary. Moreover, the test chart stored in the ROM (6) has a pattern as shown in FIG. 5(a),
It has a band-shaped black part (51) at a position Ql away from the tip, and a band-shaped black part (52) at a position further 92 away from the black part in the rear end direction. In other words, this test chart has two transition areas from bright to dark (bright/dark transition areas), the distance from the tip of the pattern to the first bright/dark transition area is Ql, and the distance from the first bright/dark transition area to the next bright/dark transition area is Ql. The distance to the brightness change part is g2.

Adjustment of the scanning speed and tip timing of the optical system (adjustment of speed and tip timing) in this embodiment will be explained below based on the flowchart of FIG. 4.

First, in step (#11) it is determined whether or not the mode is the speed/tip timing adjustment mode, and if it is the speed/tip timing adjustment mode, the process proceeds to step (#12). Step (#1
In 2), wait until the print key is turned on. When the print key is turned on, the digital image data of the test chart (Fig. 5 (a)) stored in the ROM (6) is read out and tested in the printer section. Output it as an image on recording paper (step #13). The recording paper on which this test image is output is the original (hereinafter referred to as the "test image original").
It is read as .

That is, in step (#14), the process waits until the test image original is set on the original table, and once the test image original is set on the original table, reading of the test image is started (step #15). This reading is performed by scanning the test image original with an optical system, and the test image data converted into electrical signals by a sensor such as a COD is subjected to A/D conversion and shading correction.
Store it in RAM (7) (step #16). Then, the scanning speed and tip timing of the adjusted optical system are calculated from the data of the test image stored in the RAM (7) (step #17). This calculation method will be described below.

The test image stored as digital image data in the RAM (7) by the above reading has a pattern as shown in FIG. ) corresponds to the black parts (51) and (52), respectively, and the distance from the tip to the black part (61) is 9
．． ' is 9. in Figure (a). , the black parts (61) and (62)
The distance 92° between them respectively corresponds to Q2 in FIG. Here, since only the error in the scanning speed of the optical system affects 92' and not the error in the tip timing, the scanning speed V of the optical system after adjustment can be calculated by the following equation.

V=(fl2”/Q2)Vll
-■ However, ve is the scanning speed of the optical system before adjustment. On the other hand, Q1' is affected by the tip timing error and the scanning speed error of the optical system. First, if we make a correction to remove the influence of the scanning speed error of the optical system, we get
The distance from the tip to the black part (61) is Ql''(ffa/I12'). Therefore, the adjusted tip timing T can be calculated by the following equation.

However, T-: The distance scanned at the normal scanning speed per unit time of the tip timing before adjustment. 2: The distance scanned at the tip timing.

The scanning speed V of the optical system after adjustment and the tip timing T (correction value) after adjustment calculated by the above formulas 0 and 0 are as follows:
In step (118), the data is stored in a non-volatile memory, and the speed/edge timing adjustment mode processing is completed.

In the operation of the copying machine after executing the processing in the speed/edge timing adjustment mode described above, the scanning speed of the optical system is V,
The tip timing becomes T, which means that the scanning speed of the optical system and the tip timing are adjusted simultaneously and automatically. That is, the scanning speed of the optical system becomes the normal speed, and the misalignment between the leading edge of the recording paper and the leading edge of the toner image on the photoreceptor is corrected. In addition, when calculating the tip timing T after adjustment, a correction was made to remove the influence of the scanning speed error of the optical system, so there was a deviation in the scanning speed of the optical system (from the normal scanning speed). Even if there is a deviation), accurate tip timing adjustment can be performed automatically without being affected by this.

As described above, according to the image forming apparatus according to the first aspect, the tip timing can be adjusted accurately without being affected by the error in the scanning speed of the optical system.

Further, according to the image forming apparatus according to the second aspect, it is possible to simultaneously adjust the scanning speed of the optical system and the tip timing, and in this case, the adjustment of the tip timing is also performed at the scanning speed of the optical system. This can be done accurately without being affected by errors.

In the image forming apparatus according to any of the first and second claims, the adjustment is automatically performed, so the time required for the adjustment work is shortened and the accuracy of adjustment is stabilized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the main part configuration of a digital copying machine embodying the present invention, and FIG. A diagram showing the pattern of the test chart used in the example, No. 4rxJ is a flowchart showing the details of the adjustment of the scanning speed of the optical system and the adjustment of the tip timing in another example of the present invention, and FIG. A diagram showing a test chart pattern used in the example and a pattern represented by digital image data obtained by outputting the test chart pattern as a test image onto a recording paper and then reading the test image on the recording paper. FIG. 6 is a diagram showing a schematic configuration of a digital copying machine. (6)...ROM (memory means). (12)...Position detection sensor (position detection means). (20)...Control unit (control means). (31)...White part. (32)...Black part. (51) (52) (61) (62)...band-shaped black part. (35)... Exposure unit (optical system). (36) ---Mirror unit (optical system). (43)... Registration roller (paper feeding means). (44)...Transfer section. (46)...Photosensitive drum. No. Kasumi No. (a) ROMu”-Test No.
direction

Claims (2)

[Claims] (1) In a digital image forming device that transfers an image formed on a photoconductor based on digital image data onto a recording paper conveyed by a paper feeding means, a predetermined test chart is used as digital image data. a storage means for storing; a detection means for detecting the relative positional relationship between the image of the predetermined test chart transferred to the recording paper and the leading edge of the recording paper; An image of the predetermined test chart is formed on the photoreceptor based on the image, the image is transferred to recording paper, the relative positional relationship is detected from the recording paper by the detection means, and the detection result is An image forming apparatus comprising: a control means for controlling a timing at which recording paper is fed to the photoreceptor by the paper feeding means based on the timing of feeding the recording paper to the photoreceptor. (2) An optical system scans and reads the image of the document placed on the document table, converts it into digital image data, forms an image on the photoreceptor based on the digital image data, and feeds the image. A digital image forming apparatus that transfers data onto a recording sheet conveyed by a storage means, comprising: a storage means for storing a predetermined test chart having two light/dark changing portions separated by a predetermined distance as digital image data; An image of the predetermined test chart is then formed on the photoreceptor based on the stored digital image data, the image is transferred to recording paper, and the recording paper is placed as a document on the document table. Then, the image on the recording paper is scanned and read by an optical system to obtain digital image data, and it is defined as the distance from the tip of the pattern represented by the digital image data to the brightness change part near the tip. A first distance defined as a distance between two brightness changing parts in the pattern and a second distance defined as a distance between two brightness changing parts in the pattern are calculated from the digital image data, and the calculated second distance and a predetermined reference second distance are calculated from the digital image data. The scanning speed of the optical system is adjusted based on the distance ratio between 1 distance and a predetermined reference first distance, the control means controls to adjust the timing of feeding recording paper to the photoreceptor by the paper feeding means, based on the difference between the first distance and a predetermined reference first distance. image forming device.