JP3073513B2 - Image forming device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a digital electrophotographic copying machine and a printer, and more particularly, to an image forming apparatus formed by such a digital image forming apparatus. Related to automatic image adjustment.

2. Description of the Related Art FIG. 6 shows a schematic configuration of a digital electrophotographic copying machine. In this figure, a main charging section (48), a developing section (50), a transfer section (44), a separation section (45), a cleaning section are arranged around a photosensitive drum (46) rotating at a constant speed along a rotating direction. (47) are provided respectively. A laser output unit (38) is provided on an exposure unit (49) on the photosensitive drum (46).
The laser light emitted from is emitted. By the irradiation of the laser light, an electrostatic latent image corresponding to digital image data obtained by reading the document is formed on the photosensitive drum (46). That is, the document table (40) and the document pressing member (39)
The image of the original placed between is read by scanning with an optical system and converted into an electric signal by the light receiving unit (37).
Digital image data is obtained by performing A / D conversion, etc.
The laser light output section (38) outputs a laser light based on the 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, in order to keep the optical path length to the light receiving section (37) constant, the mirror unit (36) is moved at half the moving speed of the exposure unit (35).
At the same speed.

The electrostatic latent image formed on the photosensitive drum (46) in this manner becomes a toner image in the developing section (50), and this toner image is transferred to recording paper in the transfer section (44). At this time, the photosensitive drum (46) of the recording paper is adjusted so that the leading end of the toner image on the photosensitive drum (46) coincides with the leading end of the recording paper.
It is necessary to adjust the paper feed timing to the printer. For this reason, in the copying machine shown in FIG. 6, the leading end of the recording paper conveyed from the cassette (41) or the manual paper feed table (42) by the pickup roller (71), the feed roller (72), etc. A registration roller (43) is provided in front of the photosensitive drum (46) in the transport path for the purpose of adjusting the timing of reaching the drum (46) (hereinafter, referred to as “tip timing”).
In some cases, instead of the registration roller (43), a pawl for stopping the contact of the recording paper fed by the feed roller is projected into the transport path. And conventionally, the timing to start the rotation of the registration roller,
Alternatively, the timing at which the nail protruding into the conveyance path is released by a solenoid or the like has been manually adjusted so that the leading edge of the toner image on the photosensitive member and the leading edge of the recording paper coincide. That is, the leading edge timing is adjusted by manually adjusting the time from when the exposure of the leading edge of the document is started to when the resist is turned on (start of rotation of the resist roller or release of the pawl),
The leading edge of the toner image and the leading edge of the recording paper are aligned. However, there is a problem that such manual adjustment of the timing of the tip requires time, and the adjustment accuracy varies due to the skill of the operator.

On the other hand, in Japanese Patent Application Laid-Open No. Sho 60-209454, a photoelectric element is arranged in a passage of a copy material (recording paper), and a predetermined test chart as shown in FIG. 2. Description of the Related Art A copying apparatus has been proposed in which a passing state is detected by a photoelectric element, and control is performed so as to adjust sheet feeding timing (leading end timing) based on the detection output. According to this copying apparatus, the above-mentioned problem is solved because the paper feed timing (tip timing) is automatically adjusted. However, in this copying machine, the passing state of the copying material on which the test chart is copied is detected, and it is assumed that there is no deviation in the scanning speed of the optical system in adjusting the sheet feeding timing (leading edge timing). However, in practice, the scanning speed of the optical system may be deviated due to a manufacturing error of the outer diameter of the pulley for driving the optical system, and in this case, the scanning output of the optical system is included in the detection output. Speed error affects. Therefore,
Adjustment of the paper feed timing (tip timing) cannot always be performed accurately.

On the other hand, adjustment of the scanning speed of the optical system is disclosed in
No. 82064 proposes a copying apparatus capable of automatically adjusting a copying magnification in an exposure direction, that is, a scanning speed of an optical system. In this copying apparatus, an original having two light-dark changing portions separated by a predetermined distance in the exposure direction as shown in FIG. 5 is copied onto a transfer paper (recording paper), and is transferred along a transport path of the transfer paper (recording paper). The light-dark change portion on the transfer paper (recording paper) is detected by the detecting means provided, the transit time of two light-dark change portions separated by a predetermined distance is measured, and the ratio of the transit time to a preset reference time is measured. , The scanning speed of the optical system is automatically adjusted. In Japanese Patent Application Laid-Open No. 64-82064, the scanning speed of the optical system is automatically adjusted by detecting a light-dark change portion formed on a photoconductor instead of detecting a light-dark change portion on a transfer paper. A configured copying device has also been proposed. However, the configuration of these copying apparatuses aims at automatic adjustment of the scanning speed of the optical system (copy magnification in the exposure direction), and does not mention the adjustment of the timing of feeding the recording paper to the photoconductor (the leading edge timing). .

Problems to be Solved by the Invention In the adjustment of an image in an image forming apparatus, there is a problem that manual adjustment work requires time, and the adjustment accuracy varies due to the skill of a worker and the like. As described above, a copying apparatus capable of automatic adjustment has been considered. However, as described above, in the automatic adjustment of the paper feed timing (tip timing), an error in the scanning speed of the optical system affects the adjustment accuracy. In the automatic adjustment in the above-described copying apparatus, the adjustment of the paper feed timing (tip timing) and the adjustment of the scanning speed of the optical system are considered separately.

Therefore, the present invention accurately adjusts the feeding timing of the recording paper to the photosensitive member without being affected by the error of the scanning speed of the optical system, and adjusts the feeding timing and the scanning speed of the optical system. It is an object of the present invention to provide a digital image forming apparatus capable of simultaneously and automatically performing image formation.

Means for Solving the Problems In order to achieve the above object, in the image forming apparatus according to the first aspect, an image formed on a photoconductor based on digital image data has been conveyed by a paper feeding unit. In a digital image forming apparatus for transferring to a recording sheet, storage means for storing a predetermined test chart as digital image data; and a relative position between the image of the predetermined test chart transferred to the recording sheet and a leading end of the recording sheet. Detecting means for detecting a positional relationship; forming an image of the predetermined test chart on the photoconductor based on digital image data stored by the storage means; transferring the image to a recording sheet; The relative position relationship is detected from the paper by the detection unit, and a timing of feeding the recording paper to the photoconductor by the paper supply unit based on the detection result And control means for controlling so as to adjust.

Further, in the image forming apparatus according to the second aspect, an image of a document placed on a document table is read while being scanned by an optical system, converted into digital image data, and a photosensitive member is formed based on the digital image data. In a digital image forming apparatus for forming an image on the recording medium and transferring the image to recording paper conveyed by paper feeding means, a predetermined test chart having two light-dark changing portions separated by a predetermined distance as digital image data A storage unit for storing, an image of the predetermined test chart is formed on the photoconductor based on the digital image data stored by the storage unit, and the image is transferred to a recording sheet, and the recording sheet is used as a document. When placed on the platen, the image on the recording paper is read while scanning with an optical system to obtain digital image data, which is represented by the digital image data. A first distance defined as a distance from a leading end of the pattern to a light-dark change portion closer to the leading end, and a second distance defined as a distance between two light-dark change portions in the pattern. The scanning speed of the optical system is adjusted based on a distance ratio between the calculated second distance and a predetermined reference second distance, and the calculated first distance is used as the distance ratio. Based on the difference between the corrected first distance excluding the effect of the scanning speed error and the predetermined reference first distance, the paper feeding means feeds the recording paper to the photoconductor. And control means for controlling so as to adjust the paper timing.

According to the image forming apparatus of the first aspect, an image of a predetermined test chart stored as digital image data is formed on a photoconductor, and the image is transferred to recording paper. 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 photoconductor is adjusted based on the detected relative positional relationship. As a result, the deviation between the leading edge of the image formed on the photoconductor and the leading edge of the recording paper onto which the image is transferred is corrected.

According to the image forming apparatus of the second aspect, an image of a predetermined test chart stored as digital image data is formed on a photoconductor, and the image is transferred to a recording sheet. Then, when the recording sheet is placed on a document table as an original, the image of the test chart on the recording sheet is read while being scanned by an optical system, and is converted into digital image data. The pattern represented by the digital image data has two light-dark change portions. The distance from the tip of the pattern to the light-dark change portion closer to the tip, that is, the first distance, and the two light-dark change in the pattern. The distance between the parts, that is, the second distance is calculated from the digital image data. Then, the scanning speed of the optical system is adjusted based on the calculated distance ratio between the second distance and the predetermined reference second distance. Here, this distance ratio corresponds to the speed ratio between the current scanning speed and the reference scanning speed (which is the reciprocal of the speed ratio), so that an error in the scanning speed can be corrected by this adjustment. Further, by correcting the calculated first distance based on the distance ratio, it is possible to eliminate the influence of the error of the scanning speed of the optical system. Received. Then, the tip timing is adjusted based on a difference between the corrected first distance and a predetermined reference first distance. Therefore, it is possible to correct the deviation of the leading end timing without being affected by the error of the scanning speed of the optical system.

Embodiment 1 Hereinafter, an embodiment (hereinafter, referred to as “embodiment 1”) of an image forming apparatus of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a main configuration of a digital copying machine embodying the present invention. In this figure, image data obtained by scanning an original with an optical system and converting it into an electric signal by a sensor such as a CCD is first converted into digital data by an A / D converter (1), and then subjected to shading correction. It is temporarily stored in the line memory (3). During a normal copying operation, the image data stored in the line memory is subjected to image processing by the image processing circuit (4), and then sent to a printer unit (not shown) to finally print the image on a recording sheet. Is output. Also, CPU (5), ROM (6), and R
The control unit (20) is composed of the AM (7), and the control unit (2)
Various controls are performed based on the input from the operation unit (8) and the state of each part of the copying machine by (0). The control of the tip timing, which is one of the objects of the present invention, is also performed by the control unit. 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 the 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.
It has from white portions of the l ₁ (31) black portion of the rear side (32). The position of the boundary between the white part and the black part of the image of the test chart output by the printer unit is detected by the position detection sensor (12). And based on this detection result
By controlling the registration solenoid (11) via the I / O (9), the tip timing is adjusted. When adjusting the scanning speed of the optical system, the optical scanner motor controller (10) is controlled via the I / O (9).

Hereinafter, the adjustment of the tip timing in the present embodiment will be described with reference to the flowchart of FIG.

First, it is determined in step (# 1) whether or not the mode is the tip timing adjustment mode. If the mode is the tip timing adjustment mode, the process proceeds to step (# 2). In step (# 2), the process waits until the print key is turned on. If the print key is turned on, the digital image data stored in the ROM (6) and read out from the test chart (FIG. 3) is read out and the test image is printed by the printer unit. (Step # 3). When the sensor detects the tip of the white portion of the output test image (when the sensor is turned on), the white portion (31) of the test chart is displayed.
Starts counting for measuring the length of the portion corresponding to the width l ₁ (step # 4, # 5). Thereafter, the process waits until the rear end of the white portion (the boundary between the white portion and the black portion) of the test image is detected by the sensor (until the sensor is turned off) (step # 6). The counting is continued during this standby, and the counting ends when the trailing edge 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, the tip timing T after adjustment in step (# 8) is calculated by the following equation.

T = T ₀ + (C−C ₀ ) / K ₁ , where T ₀ : leading edge timing before adjustment C: count value while the white portion of the test image passes through the sensor (from step # 5 to step # 7) C ₀ : Reference count value K ₁ : Count value of the tip timing per unit time. The adjusted tip timing T calculated by the above equation is stored in the nonvolatile memory in step (# 9), and the process in the tip timing adjustment mode ends.

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

The embodiment described above is an example in which the present invention is applied to a digital copying machine. However, since the reading section of the document is not involved in the above-described processing of the leading edge timing adjustment, the present invention for the leading edge timing adjustment is not required. Can also be applied to an electrophotographic printer.

Embodiment 2 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.

The present embodiment is configured so that adjustment of the leading edge timing and adjustment of the scanning speed of the optical system can be simultaneously and automatically performed in a digital copying machine. The configuration of the main part of this embodiment is almost the same as that of the first embodiment shown in FIG. 1, but in this embodiment, the position detection sensor (12) is used.
Is unnecessary. Further, the test chart stored in the ROM (6) is a pattern as shown in FIG. 5 (a), a black portion of the strip at a position separated by l ₁ from the tip to (51),
Has strip-shaped black portion (52) at its from the black portions further apart toward the rear end by l ₂ position. That is, the change of the light to dark in the test chart (dark change portion) is present twice, the distance from the tip of the pattern to the first light-dark change portion is l _1, following from the first light-dark change portion the distance to the light-dark change part of an l _2.

Hereinafter, adjustment of the scanning speed and the tip timing (adjustment of the speed and the tip timing) of the optical system in the present embodiment will be described with reference to the flowchart of FIG.

First, it is determined in step (# 11) whether or not the mode is the speed / tip timing adjustment mode. If the mode is the speed / tip timing adjustment mode, the process proceeds to step (# 12). Step (# 12)
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 the printer section outputs the digital image data as a test image. Output to recording paper (step # 13). The recording paper on which the test image is output is read as a document (hereinafter, referred to as a “test image document”). That is, in step (# 14), the process waits until the test image document is set on the platen. When the test image document is set on the platen, 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 data of the test image converted into an electric signal by a sensor such as a CCD is subjected to A / D conversion and shading correction.
It is stored in AM (7) (step # 16). And RAM
From the test image data stored in (7), the adjusted scanning speed and tip timing of the optical system are calculated (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. 5B, and the belt-like black portions (61) and (62)
Corresponds to the black portions (51) and (52) in FIG. 11A, respectively, and the distance l ₁ ′ from the tip to the black portion (61) is shown in FIG.
To the l _1, the distance l ₂ between the black portion (61) (62) 'correspond respectively to l ₂ of FIG. (A). Here, since l ₂ ′ is affected only by the error in the scanning speed of the optical system and not by the error in the tip timing, the scanning speed V of the adjusted optical system can be calculated by the following equation.

V = (l ₂ ′ / l ₂ ) V ₀ , where V ₀ is the scanning speed of the optical system before adjustment. On the other hand, l ₁ ′ is affected by an error in the tip timing and an error in the scanning speed of the optical system. First, when correction is performed to eliminate the effect of the scanning speed error of the optical system, the distance from the tip to the black portion (61) is l ₂ ′ (l ₂ / l ₂ ′). Therefore, the adjusted tip timing T can be calculated by the following equation.

Here, T ₀ : leading edge timing before adjustment K ₂ : distance scanned at a regular scanning speed per unit time of leading edge timing.

The adjusted scanning speed V of the optical system and the adjusted tip timing T (correction value) calculated by the above equations and the above equations.
Is stored in the non-volatile memory in step (# 18), and the processing in the speed / tip timing adjustment mode ends.

In the operation of the copier after executing the above-described processing of the speed / tip timing adjustment mode, the scanning speed of the optical system is V and the tip timing is T, and the adjustment of the scanning speed of the optical system and the tip timing are simultaneously and automatically performed. It was done in. That is, the scanning speed of the optical system becomes a regular speed, and the deviation between the leading end of the recording paper and the leading end of the toner image on the photoconductor is corrected. In addition, when calculating the adjusted leading end timing T, a correction is made to eliminate the influence of the scanning speed error of the optical system, so that the scanning speed of the optical system is deviated (from the normal scanning speed). Even if it is shifted), accurate adjustment of the tip timing can be automatically performed without being affected by this.

As described above, according to the image forming apparatus of the first aspect, it is possible to accurately adjust the leading end timing without being affected by the error of the scanning speed of the optical system.

Further, according to the image forming apparatus of the second aspect, the adjustment of the scanning speed of the optical system and the adjustment of the tip timing can be performed at the same time. Can be performed accurately without being affected by the error of

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

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of a main part of a digital copying machine embodying the present invention, FIG. 2 is a flow chart showing the content of adjustment of the leading edge timing in one embodiment of the present invention, and FIG. FIG. 4 is a flowchart showing a test chart pattern used in one embodiment, FIG. 4 is a flowchart showing the contents of adjustment of a scanning speed and timing adjustment of an optical system in another embodiment of the present invention, and FIG. Diagram showing a pattern of a test chart used in the embodiment and a pattern represented by digital image data obtained by reading the test image on the recording paper after outputting the test chart pattern as a test image on the recording paper, Sixth
FIG. 1 is a diagram showing a schematic configuration of a digital copying machine. (6) ROM (storage means), (12) position detection sensor (position detection means), (20) control unit (control means), (31) white part, (32) Black part, (51) (52) (61) (62) ... Black band part, (35) ... Exposure unit (optical system), (36) ... Mirror unit (optical system), (43) ... Registration roller (feeding means), (44) transfer section, (46) photosensitive drum.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI B65H 9/00 B65H 9/00 B

Claims (2)

(57) [Claims] 1. A digital image forming apparatus for transferring an image formed on a photoreceptor based on digital image data to recording paper conveyed by a paper feeding means, wherein a predetermined test chart is converted into a digital image and an image. Storage means for storing as data, detection means for detecting a relative positional relationship between the image of the predetermined test chart transferred to the recording paper and the leading end of the recording paper, and a digital image stored by the storage means An image of the predetermined test chart is formed on the photoreceptor based on the data, the image is transferred to recording paper, and the relative positional relationship is detected from the recording paper by the detection unit. Control means for controlling so as to adjust the timing of feeding the recording paper to the photoconductor by the paper feeding means based on the paper feeding means. Apparatus. 2. An image of a document placed on a platen is read while being scanned by an optical system, and is converted into digital image data.
A digital image forming apparatus for forming an image on a photoreceptor based on the digital image data and transferring the image to recording paper conveyed by paper feeding means, comprising two light-dark changing portions separated by a predetermined distance Storage means for storing a predetermined test chart as digital image data; forming an image of the predetermined test chart on the photoreceptor based on the digital image data stored by the storage means; When the recording sheet is transferred and placed on the platen as an original, the image on the recording sheet is read while scanning with an optical system to obtain digital image data, and from the leading end of the pattern represented by the digital image data. A first distance defined as a distance to a light-dark change portion closer to the tip, and a distance between two light-dark change portions in the pattern. Is calculated from the digital image data, and the scanning speed of the optical system is adjusted based on the calculated distance ratio between the second distance and a predetermined reference second distance. Correcting the first distance based on the distance ratio, based on the difference between the first distance excluding the effect of the scanning speed error and a predetermined reference first distance, and setting the photosensitive position by the sheet feeding means. Control means for controlling so as to adjust the feeding timing of the recording paper to the body. An image forming apparatus comprising: