JP2000062245A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a flaw at the end part of a belt or the nonlinear shape thereof from appearing on a recording sheet by forming an image based on an imaginary belt end signal. SOLUTION: A belt end detector 2 detects the end part of a light shield and the end part of a photosensitive belt. A ramp signal is generated with reference to detection of the end part of the light shield and delivered to a comparator 7. The comparator 7 compares the output from an integrator 6 with the ramp signal and generates an imaginary belt end signal which is fed back to a phase comparator 4 and subjected to phase comparison with a belt end signal from the belt end detector 2. A charge pump 5 performs charge/ discharge processing based on the phase difference signal and delivers a marking signal detected by a belt seam marking detector 8 to a charge pump gain switch 9 in order to control the charge/discharge current to increase at a belt seam part. A voltage varied through charge/discharge processing is outputted after being integrated by an integrator 6. An image forming section 2000 forms an image based on the imaginary belt end signal.

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, and more particularly to an image forming apparatus provided with a photosensitive belt which is scanned by a laser beam system.

[0002]

2. Description of the Related Art In a conventional image forming apparatus using a laser beam scanning method, when a belt-shaped photosensitive member is used, the belt moves in the main scanning direction. There was a problem that misalignment caused printing misalignment.

As a solution to such a problem, Japanese Patent Laid-Open Nos. 4-274467 and 4-275574 have been published.
As disclosed in Japanese Patent Laid-Open Publication No. 2003-242242, a method of detecting the end portion of the photoconductor belt by the same laser beam scanning as that used for latent image formation, and determining the writing position in the main scanning direction based on the detection signal. Is proposed.

A method equivalent to the above method is shown in FIG. 10 as a prior art example 1. The belt edge detector of the image forming apparatus shown in FIG. 10 includes a belt edge detector 2, a pixel clock synchronization circuit 10, and a pixel clock generator 11.
A counter 12, a forced light emission signal generation unit 13, an image data storage unit 14, a laser driver 15, and a laser 1.
6 and.

In FIG. 10, a belt end detector 2 detects a belt end portion during scanning as a belt end signal. The pixel clock synchronization circuit 10 outputs the belt edge signal detected by the belt edge detector 2 in synchronization with the clock signal generated by the pixel clock generator 11. The counter 12 detects the belt edge signal detected by the belt edge detector 2 and the pixel clock synchronizing circuit 1
Pulses with the signal output from 0 are counted and output as a count value. The forced light emission signal generation unit 13 includes a counter 12
A laser emission signal is generated based on the count value output by the laser. The image data storage unit 14 outputs image data based on the count value from the counter 12. The laser driver 15 controls the driving of the laser 16 according to the laser emission signal from the forced emission signal generation unit 13 and the image signal from the image data storage unit 14.

In the image forming apparatus shown in FIG. 10, for example, even if one straight line is recorded in the sub-scanning direction, the image written on the recording paper has the same shape as the jagged shape at the belt end. There is a problem that it is recorded as a line. To solve this problem,
As a second conventional example, there is an image forming apparatus shown in FIG.

In the image forming apparatus shown in FIG. 11 as the second conventional example, the virtual belt edge generating section 1000 and the image forming section 20 are provided.
00 and 00. Virtual belt edge generation unit 1000
Is a belt edge detector 2, a ramp signal generator 3, a phase comparator 4, a charge pump 5, an integrator 6, a comparator 7, a pixel clock synchronization circuit 10, a pixel clock generator 11, and a counter. 12, a forced light emission signal generation unit 13, an image data storage unit 14, a laser driver 15, and a laser 16. The image forming unit 2000 has the same configuration as that of the first conventional example, and therefore its description is omitted.

First, the difference from the image forming apparatus of Conventional Example 1 will be described. In the image forming apparatus of Conventional Example 2, a ramp signal generator 3 that generates a ramp signal based on the belt edge signal output from the belt edge detector 2, and a virtual belt edge signal that is a feedback signal from the comparator 7. A phase comparator 4 for comparing and outputting a phase difference from the belt end signal from the belt end detector 2, and a phase comparator 4
A charge pump 5 that performs charge / discharge processing according to an output signal from the charge pump 5, and an integrator 6 that outputs a signal obtained by integrating the change in voltage in the charge / discharge processing performed by the charge pump 5.
And a comparator 7 which sends the result of comparing the output signal from the ramp signal generator 3 and the signal from the integrator 6 as a virtual belt end signal, and sends it to the phase comparator 4 and the image forming unit 2000. It is provided in.

The image forming apparatus of the second conventional example compares the phase difference between the actual belt end signal detected by the belt end detector 2 and the virtual belt end signal, and performs the charging / discharging process according to the phase difference. By doing so, the writing position by the laser is shifted to prevent printing deviation on the recording paper.

[0010]

However, since the image forming apparatuses of the above-mentioned conventional examples 1 and 2 are intended to prevent the print misregistration at the time of forming an image, the belt end portion which is printed on the recording paper is prevented. There is a problem that it does not prevent scratches and non-linear shapes.

Further, in the image forming apparatus of the second conventional example, when there is a step at the belt seam, the virtual belt end signal as shown in FIG. 7 does not follow the actual belt end.

The present invention relates to an image forming apparatus for forming an image using a photosensitive belt by a laser beam system,
An object of the present invention is to provide an image forming apparatus that prevents a scratch or a non-linear shape at the belt end from appearing in a recorded image.

[0013]

In order to solve the above-mentioned problems, the present invention according to claim 1 provides a virtual belt end signal in an image forming apparatus for forming an image using a photoconductor belt by a laser beam scanning method. A virtual belt end signal generation unit that generates the image and an image forming unit that forms an image using the virtual belt end signal generated by the virtual belt end signal generation unit. A marking indicating the belt seam portion is provided on the top, and a marking detection unit that detects the marking and a charging / discharging process switching unit that switches the charging / discharging process based on the marking detected by the marking detection unit are configured. Is characterized by.

According to a second aspect of the present invention, in the first aspect, the image forming section includes a pixel clock generator, a pixel clock synchronizing circuit, a counter, a forced light emission signal generating section, and an image data storage section. The pixel clock generator includes a laser driver and a laser. The pixel clock generator generates a clock signal for timing the output of image data. The pixel clock synchronization circuit synchronizes the virtual belt end signal with the clock signal and a counter. Counts the pulse of the virtual belt end signal and the pulse of the virtual belt end signal synchronized with the clock signal as the count value, and the forced light emission signal generation unit generates the laser light emission signal based on the count value from the counter. However, the image data storage unit is based on the count value and the virtual belt end signal synchronized with the clock signal. The laser driver outputs an image data signal, the laser driver outputs a laser control signal for outputting a laser beam based on the laser emission signal and the image data signal, and the laser controls the latent image on the photoreceptor based on the laser control signal. A feature is that a laser beam for forming an image is output.

The invention according to claim 3 is the invention according to claim 1 or 2.
In the invention described above, the virtual belt end signal generation unit includes a belt end detector, a ramp signal generator, a phase comparator, a charge pump, an integrator, a comparator, a belt seam marking detector, and a charge pump. When a signal indicating the start of scanning is input, the belt edge detector is configured with a gain switching unit, and detects the edge portion of the light shielding body by laser scanning and at the same time outputs the belt edge signal to detect the edge portion of the photosensitive belt. At the same time, the output of the belt end signal is stopped, and the lamp signal generator starts the output of the voltage that rises constantly with the detection of the end portion of the light shielding body by the belt end detector as a reference and the detection of the end portion of the photoconductor belt. At the same time, the voltage that stops the output is output as a ramp signal, and the phase comparator compares the phase difference between the belt end signal and the feedback signal sent from the comparator. , A phase difference signal is output, the belt seam marking detector detects the marking provided on the photoconductor belt, and outputs it as a marking detection signal.The charge pump gain changer outputs the charge pump based on the marking detection signal. Outputs a switching signal for switching the charging / discharging processing of the charge pump, the charge pump performs the charging / discharging processing based on the phase difference signal and the switching signal,
The voltage changed by the charging / discharging process is output, the integrator outputs a signal obtained by performing an integration process on the changed voltage, the comparator compares the ramp signal with the signal subjected to the integration process, and outputs a virtual belt end signal, The virtual belt end signal is sent out to the image forming unit at the same time as it is sent out to the phase comparator as a feedback signal.

According to a fourth aspect of the present invention, in the third aspect of the invention, the phase difference signal has a detection time from the end of the light shield to the end of the belt as t1, and a virtual belt end signal is generated from the end of the light shield. When the detection time to the virtual belt end indicated by the virtual belt end signal generated by the means is t2, when t1> t2, a predetermined amount of electric charge is charged,
When t1 <t2, a specified amount of electric charge is discharged, and t1 = t2
At the time of, it is a signal for controlling so as not to perform the charging / discharging process.

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the marking is composed of any one of a light transmission window, a light reflector and a magnetic body. And

According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the belt seam marking detector is a transmission type optical sensor, a reflection type optical sensor or a magnetic sensor. It is characterized by being configured.

According to a seventh aspect of the present invention, in the invention according to any one of the first to sixth aspects, the image forming apparatus is:
A plurality of optical systems including a laser, a collimator lens, a polygon mirror, and an Fθ lens are installed.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an image forming apparatus according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Figure 1
10 to 10, there is shown an embodiment of an image forming apparatus according to the present invention. The same parts as those shown in the prior art are designated by the same reference numerals.

FIG. 1 is a block diagram showing the overall configuration of an image forming apparatus which is an embodiment of the present invention. In FIG. 1, a virtual belt end generation unit 1000 in an image forming apparatus according to an embodiment of the present invention includes a belt end detector 2, a ramp signal generator 3, a phase comparator 4, and a charge pump 5.
, Integrator 6, comparator 7, belt seam marking detector 8, and charge pump gain switching device 9
The pixel clock synchronization circuit 10, the pixel clock generator 11, the counter 12, the forced light emission signal generation unit 13, the image data storage unit 14, the laser driver 15, and the laser 16.

In FIG. 1, the belt end detector 2 detects the end of the light shield at the laser scanning start portion and the end of the photosensitive belt by the same laser beam used when forming a latent image. A belt end signal is output to the ramp signal generator 3 and the phase comparator 4 from the detection of the end of the light shield to the detection of the end of the photosensitive belt.

The ramp signal generator 3 is the belt end detector 2
Based on the detection time of the end portion of the light shield detected by the above, a ramp signal in which the voltage linearly rises is generated and sent to the comparator 7 until the end portion of the photosensitive belt is detected. At the same time when the edge of the photoconductor belt is detected, the output from the ramp signal generator 3 is stopped.

The comparator 7 compares the ramp signal from the ramp signal generator 3 with the output signal from the integrator 6,
The output is sent as a virtual belt end signal. The virtual belt end signal is transmitted to the phase comparator 4 and the image forming unit 2 which will be described later.
000 to the pixel clock synchronizing circuit 10 and the counter 12.

The phase comparator 4 compares the phase difference between the belt end signal output from the belt end detector 2 and the virtual belt end signal which is the feedback signal from the comparator 7. This phase difference is output to the charge pump 5 as a phase difference signal.

The charge pump 5 charges or discharges a prescribed amount of electric charge to the integrator 6 based on the phase difference signal from the phase comparator 4.

The belt seam marking detector 8 detects the marking indicating the seam portion provided in the vicinity of the seam of the photoconductor belt provided on the photoconductor belt, and supplies the marking to the charge pump gain switching unit 9 as a marking detection signal. Send out.

The charge pump gain switching section 9 switches so as to increase the charging / discharging amount and charging / discharging time by the charge pump 5 based on the marking detection signal sent from the belt seam marking detector 8.

The integrator 6 holds the voltage that has changed as a result of the charge / discharge processing by the charge pump 5, and sends a signal obtained by integrating the held voltage to the comparator 7. The signal from the integrator 6 is always output. For example, when image formation is performed using the image forming apparatus according to the present embodiment, the integrator 6 at the first (first) scanning
In the second and subsequent scans, the integrator 6 holds a signal obtained by integrating the voltage change of the charge / discharge processing by the charge pump 5 in the previous processing, and thus the signal concerned is held. Since the image is formed by using, it becomes stable.

In the image forming apparatus according to the embodiment of the present invention, the belt seam marking detector 8 for detecting the marking provided in the vicinity of the seam on the end portion of the photoconductor belt detects the seam portion of the photoconductor belt to perform marking. The signal is sent to the charge pump gain switching unit 9 as a detection signal. The charge pump gain switching unit 9 to which the marking detection signal is input increases the charge / discharge amount or charge / discharge time from the charge pump 5 in the belt seam portion to send out a signal that is not affected by the step in the belt seam portion. It becomes possible to do.

Next, processing when forming an image using the virtual belt end signal will be described. The pixel clock generator 11 generates a clock signal which is the basis of image signal output timing. Since the pixel clock signal and the virtual belt end signal are asynchronous, the virtual belt end signal must be synchronized with the reference clock of the image signal in order to form a latent image by laser scanning at a desired position. Therefore, the generated clock signal is sent to the pixel clock synchronization circuit 10.

The pixel clock synchronizing circuit 10 synchronizes the virtual belt end signal from the comparator 7 with the clock signal from the pixel clock generator 11 and sends it to the counter 12 and the image data storage 14.

The counter 12 counts the pulses of the virtual belt end signal from the comparator 7 and also counts the pixel clock signal sent from the pixel clock synchronizing circuit 10 with the virtual belt end signal as a reference and outputs it as a count value. To do.

The image data storage unit 14 specifies the image recording start time in the sub-scanning direction (photosensitive belt driving direction) based on the counted value of the virtual belt end signal from the counter 12, and also determines the pixel clock signal. The image recording start time in the main scanning direction (laser scanning direction) is specified based on the count value, and the image data is output in synchronization with the pixel clock signal.

The forced light emission signal generating section 13 includes a counter 12
A laser emission signal near the belt end is generated based on the count value of.

The laser driver 15 drives the laser 16 in accordance with the image signal from the image data storage unit 14 and the laser emission signal from the forced emission signal generation unit 13 to form a latent image on the photosensitive belt. By performing these processes for each color laser, the recorded image is not affected by the non-linear shape of the belt end portion, and the print displacement due to the movement of the belt in the main scanning direction does not occur.

FIG. 2 shows the structure of the photosensitive belt 60 used in the image forming apparatus according to the embodiment of the present invention. In FIG. 2, the photoreceptor belt 60 has a seam portion 6
A belt seam marking (also simply referred to as marking) 62 is provided in the vicinity of 1. This marking 62 is
It is composed of a light transmission window, a light reflector, or a magnetic material.

FIG. 3 is an enlarged view of the end portion of the photosensitive belt of the image forming apparatus according to the embodiment of the present invention. What is indicated by a dashed line is the virtual belt end, and the actual belt end is shown to be jagged.

In FIG. 3, the photoconductor belt 60 is made of a material that does not transmit a laser beam. The photosensitive belt 60 is driven by a driving power source (not shown), and the laser beam is scanned in the traveling direction and the vertical direction by the driving. The light shield 110 is made of a material that does not transmit the laser beam, and is fixedly arranged at a position where the laser beam is scanned. The belt end detector 2 is arranged on the back surface of the light shield 110 and the photoconductor belt 60 when viewed from the laser beam incident direction.

FIG. 4 is a diagram for explaining the arrangement of the photoconductor belt, the laser scanning section for four colors, the belt edge detector, the light shield, and the developing device, and the operating condition thereof. The laser beams from the lasers 51 to 54 for the respective colors are collimated by the collimator lenses 101 to 104, reflected by the rotating polygon mirrors 141 to 144 for the respective colors, and passed through the Fθ lenses 31 to 34 on the photosensitive belt 60. To scan.
Belt edge detector 21 corresponding to each color laser beam scanning
24 and the light shields 111 to 114 are arranged at the positions described in FIG. Belt seam marking detectors 221 to 224 for detecting markings near the seam of the photoconductor belt 60 are arranged. The seam marking detectors 221 to 224 are configured according to the constituent means of the marking 62 such as a transmissive optical sensor, a reflective optical sensor, and a magnetic sensor. In addition, the latent image formed on the photoconductor belt 60 by each laser beam scanning is the developing device 241.
Through 244, the images are sequentially developed, and finally an image is formed on the recording paper.

The time chart shown in FIG. 5 is a diagram showing three processing patterns in the image forming apparatus according to the embodiment of the present invention. In FIG. 5, the phase comparator 4
Is the time from the edge of the belt edge signal output from the belt edge detector 2 indicating the edge of the light shield to the edge of the actual belt edge, and the belt edge signal output from the belt edge detector 2 is When the time from the edge indicating the end of the light shield to the virtual belt end indicated by the virtual belt end signal fed back from the comparator 7 is t2, t1> t
A signal indicating whether 2 or t1 <t2 or t1 = t2 is output.

The virtual belt end signal starts to be output when the voltage of the output signal from the integrator 6 and the voltage of the ramp signal from the ramp signal generator 3 overlap in the comparator 7, and the output from the ramp signal generator 3 starts. The output is stopped when is stopped.

As a first processing pattern, the charge pump 5 charges the integrator 6 with a predetermined amount of electric charge when the phase difference signal from the phase comparator 4 indicates t1> t2.

As the second processing pattern, the phase comparator 4
When the signal from 1 indicates t1 <t2, the integrator 6 is discharged with a specified amount of electric charge.

As the third processing pattern, the phase comparator 4
If the signal from indicates t1 = t2, charge / discharge processing is not performed.

The above processing is performed for each scan. The integrator 6 holds a signal obtained by integrating the voltage changed by the charging / discharging process, and is compared with the ramp signal in the comparator 7 at the next scanning to generate a virtual belt end signal.

In the phase comparator 4, the above-mentioned t1, t2
Although it is possible to calculate the actual value, the only necessary information is whether t1 or t2 is larger, and the calculated time difference is actually in the nanosecond range. Since it is necessary to be detected at high speed, the above processing is performed by the sequential circuit configured by the logic circuit.

The charge / discharge amount per time by the charge pump 5 in the image forming area depends on the time t2 from the detection time of the end of the light shield of the virtual belt end signal and the value of t1 due to the scratch or non-linear shape of the belt end. The value is selected to be a sufficiently small value so as to reduce the fluctuation even when it fluctuates abruptly for each scanning, and to follow the movement of the belt in the scanning direction. The fluctuation cycle of t1 due to the movement of the belt in the scanning direction is sufficiently longer than that due to a scratch on the belt end portion or a non-linear shape.

The belt seam portion 61 where no image is formed has a step as shown in FIG. 2, and the size of the step is much larger than the scratches and the non-linear shape of the belt end. is there. If the charging / discharging amount by the charge pump 5 is set to the same amount as that of the image forming area, the virtual belt end portion is largely deviated from the actual belt end portion, and FIG.
It becomes like an oblique one-dotted line part shown in. In order to prevent this, the belt seam marking detector 8 detects the marking 62 provided near the belt seam portion 61, and the charge pump gain switching device 9 detects the charge / discharge amount of the charge pump 5 near the belt seam portion 61. Switch to larger. The charge / discharge amount is switched by the charge pump 5 by changing the charge / discharge time or the charge / discharge current.

After a predetermined time has passed, the belt seam portion 61
When the image forming area is entered from the vicinity, the charge / discharge amount is restored.
As a result, as shown in FIG. 6, even if the belt seam portion 61 has a step, the virtual belt end signal does not form an image. In the vicinity of the belt seam portion 61, the signal follows the belt position under the influence of the shape of the belt end portion, and becomes a signal which is not influenced by the damage of the belt in the image forming area.

Next, another embodiment of the present invention will be described with reference to FIG.
Will be described with reference to. In another embodiment of the present invention, the optical system is composed of one, and the laser beam emitted from the laser 51 is a collimating lens 101.
The light is collimated by the laser beam, is reflected by the rotating polygon mirror 141, and scans the photosensitive belt 60 via the Fθ lens 31. The belt edge detector 21 and the light shield 111 corresponding to the laser beam scanning are arranged at the positions described in FIG. Belt seam marking detection means 221 for detecting the marking 62 near the belt seam on the photoconductor belt 60 is arranged.

The latent image of the image formed on the photosensitive belt 60 by the first laser beam scanning is developed by the developing device 241, and is formed on the photosensitive belt 60 by the second laser beam scanning. The latent image of the formed image is sequentially developed in the order of latent image formation and development, such as being developed by the developing device 242. In order to form a four-color image, the image cannot be formed on the recording paper without rotating the photoconductor belt 60 four times, but the output image is not affected by scratches or non-linear shapes at the belt end. It will be of quality.

FIG. 9 is a flow chart showing an operation example in the embodiment of the present invention. The edge of the light shield is detected by laser scanning (step S1). Generation of a ramp signal is started based on the detection time of the end of the light shield detected in step S1 (step S2). The output of the ramp signal stops at the same time when the belt end is detected. In step S2, the generated ramp signal is compared with the output signal from the integrator to generate a virtual belt end signal (step S4).

Next, when the actual belt end portion is detected by laser scanning (step S3), the phase difference between the belt end signal and the virtual belt end signal fed back from the comparator is compared (step S5). The charge pump performs charge / discharge processing based on the phase difference signal indicating the compared phase difference (step S6). The signal obtained by integrating the voltage change during the charge / discharge processing is held by the integrator (step S7). The signal subjected to the integration processing in step S7 is supplied again to step S4 as an output signal from the integrator.

In step S4, the virtual belt end signal generated is synchronized with the clock signal for synchronizing with the image data signal in the image forming section (step S8). The pulses of the virtual belt end signal synchronized with the clock signal are counted and sent as a count value (step S9). Image data is transmitted based on the transmitted count value (step S10), and a laser emission signal is generated (step S11). The drive of the laser beam is controlled based on the image data sent in step S10 and the laser emission signal generated in step S11 (step S12).

At the time of the first (first) scanning,
Since the voltage change signal held in the integrator is indefinite, the generated ramp signal is compared with the indefinite voltage change signal sent from the integrator in step S4, and the virtual belt end is compared. Generate a signal. The virtual belt end signal generated here is sent to the phase comparator as a feedback signal. In the second and subsequent scans,
The integrator holds a signal obtained by integrating the voltage change at the time of the previous scanning, and sends the integrated signal to the comparator.

[0057]

As is apparent from the above description, according to the image forming apparatus of the present invention, since the latent image is formed by laser scanning with reference to the virtual photoconductor belt end signal, the belt is formed on the photoconductor belt. It is possible to form a latent image of desired image data at a desired position such that the edge of the belt does not appear on the recording paper image even if the edge has a scratch or has a non-linear shape.

Further, according to the image forming apparatus of the present invention, the marking indicating the seam is provided on the end portion of the photoconductor belt, and in accordance with the signal detected by the marking detector, the filling of the belt seam portion where the image formation is not performed is performed. By increasing the amount of discharge or charging / discharging time, there is no influence of the step at the belt seam. Therefore, the image formed by the laser beam scanning of each color and developed by the developing device has high quality which is not affected by the shape of the end portion of the photosensitive belt.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged view of the vicinity of an end portion of a photosensitive belt.

FIG. 3 is a view showing a joint portion of a photosensitive belt.

FIG. 4 is a diagram for explaining an operating condition of laser scanning in the embodiment of the present invention.

FIG. 5 shows a time chart in the embodiment of the present invention.

FIG. 6 is an enlarged view of a photosensitive belt end portion when the virtual belt end portion and the belt end portion follow each other.

FIG. 7 is an enlarged view of the photosensitive belt end portion when the virtual belt end portion and the belt end portion do not follow each other.

FIG. 8 is a diagram for explaining an operating condition of laser scanning according to another embodiment of the present invention.

FIG. 9 is a flowchart showing an operation example of the embodiment of the present invention.

FIG. 10 is a block diagram showing a configuration of an image forming apparatus of Conventional Example 1.

11 is a block diagram showing a configuration of an image forming apparatus of Conventional Example 2. FIG.

[Explanation of symbols]

1 Virtual belt edge generator 2 Belt edge detector 3 ramp signal generator 4 Phase comparator 5 charge pump 6 integrator 7 comparator 8 Belt seam marking detector 9 Charge pump gain changer 10 pixel clock synchronization circuit 11 pixel clock generator 12 counter 13 Forced emission signal generator 14 Image data storage 15 Laser driver 16 laser

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[Procedure amendment]

[Submission date] July 19, 1999 (1999.7.1)
9)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

In the image forming apparatus shown in FIG. 10, for example, even if one straight line is recorded in the sub-scanning direction, the image written on the recording paper has the same shape as the jagged shape at the belt end. There is a problem that it is recorded as a line. To solve this problem ,
The Japanese Patent Application No. Hei 10 (1999) filed previously by the inventor shown in FIG .
No. 10-238463 (filing date: July 17, 1998)
Day) image forming device.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

The image forming apparatus shown in FIG . 11 is composed of a virtual belt edge generating section 100 and an image forming section 200. The virtual belt edge generation unit 100 uses the belt edge detector 2
, A ramp signal generator 3, a phase comparator 4, a charge pump 5, an integrator 6, a comparator 7, a pixel clock synchronization circuit 10, a pixel clock generator 11, a counter 12, and a forced light emission signal generation. Part 13
An image data storage unit 14, a laser driver 15,
And a laser 16. The image forming unit 200 is
Since the configuration is the same as that of the conventional example 1, description thereof will be omitted.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

First, the difference from the image forming apparatus of Conventional Example 1 will be described. In the image forming apparatus shown in FIG. 11, the ramp signal generator 3 that generates a ramp signal based on the belt end signal output from the belt end detector 2 is used.
And a phase comparator 4 for comparing and outputting a phase difference between a virtual belt end signal which is a feedback signal from the comparator 7 and a belt end signal from the belt end detector 2, and an output signal from the phase comparator 4. A charge pump 5 that performs charge / discharge processing in response to the charge pump, an integrator 6 that outputs a signal obtained by integrating the change in voltage in the charge / discharge processing performed by the charge pump 5, and an output signal from the ramp signal generator 3 Bowl 6
There is newly provided a phase comparator 4 and a comparator 7 which sends out the result of comparison with the signal from the virtual belt end signal as a virtual belt end signal.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

[0009] images forming device This compares the phase difference of the actual belt end signal detected by the belt edge detector 2 and the virtual belt end signal, were charged and discharged process in accordance with the phase difference, By shifting the writing position by the laser, printing deviation on the recording paper is prevented.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

[0010]

However, since the image forming apparatus of the above-mentioned conventional example 1 is intended to prevent the print misregistration at the time of forming an image, the belt edge portion which is printed on the recording paper and the scratches on the belt end may be prevented. There is a problem that it does not prevent non-linear shapes.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

Further, in the image forming apparatus of Japanese Patent Application No. 10-238463 , when there is a step at the belt joint, the virtual belt end signal as shown in FIG. 7 does not follow the actual belt end. There is a point.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

[0013]

In order to solve the above problems SUMMARY OF THE INVENTION, invention of claim 1, wherein, in an image forming apparatus for forming an image by using a photoreceptor belt by a laser beam scanning method, the belt of the photosensitive belt Output by detecting the edge
A virtual belt end signal generator for generating a virtual belt end signal from the belt end detection signal, and an image forming unit for forming an image using the virtual belt end signal generated by the virtual belt end signal generating unit, virtual belt end signal generator, tentative
Change the output timing of the ideal belt end signal by charging and discharging
Charge / discharge means and belt joint provided on the photoconductor belt
Marking detection signal by detecting the marking indicating the eyes
Marking detecting means for outputting
Based on the marking detection signal output from
Charge / discharge amount switching means for switching the charge / discharge amount according to the level
Characterized in that it is configured with the an.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

The invention according to claim 3 is the invention according to claim 1 or 2.
In the invention described above, the virtual belt end signal generation unit includes a belt end detector, a ramp signal generator, a phase comparator, a charge pump, an integrator, a comparator, a belt seam marking detector, and a charge pump. When a signal indicating the start of scanning is input, the belt edge detector is configured with a gain switching unit, and detects the edge portion of the light shielding body by laser scanning and at the same time outputs the belt edge signal to detect the edge portion of the photosensitive belt. At the same time, the output of the belt end signal is stopped, and the lamp signal generator starts the output of the voltage that rises constantly with the detection of the end portion of the light shielding body by the belt end detector as a reference and the detection of the end portion of the photoconductor belt. At the same time, the voltage that stops the output is output as a ramp signal, and the phase comparator compares the phase difference between the belt end signal and the feedback signal sent from the comparator. , A phase difference signal is output, the belt seam marking detector detects the marking provided on the photoconductor belt, and outputs it as a marking detection signal.The charge pump gain changer outputs the charge pump based on the marking detection signal. Outputs a switching signal for switching the charging / discharging amount of, the charge pump switches the charging / discharging amount based on the phase difference signal and the switching signal ,
And outputs a voltage more changes to the switching, the integrator outputs the integral processing signals altered voltage, the comparator compares the ramp signal and the integral processed signals, and outputs the virtual belt end signal, The virtual belt end signal is sent out to the image forming unit at the same time as it is sent out to the phase comparator as a feedback signal.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

According to a sixth aspect of the present invention, in the invention according to any one of the third to fifth aspects, the belt seam marking detector is a transmission type optical sensor, a reflection type optical sensor or a magnetic sensor. It is characterized by being configured.

[Procedure Amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

FIG. 1 is a block diagram showing the overall configuration of an image forming apparatus which is an embodiment of the present invention. In FIG. 1, an image forming apparatus according to an embodiment of the present invention is a virtual bell.
Consists of the edge generating unit 1000 and the image forming unit 2000
The virtual belt end generation unit 1000 includes the belt end detector 2, the ramp signal generator 3, the phase comparator 4, the charge pump 5, the integrator 6, the comparator 7, and the belt seam marking detector 8 When, a charge pump gain switching unit 9, the image forming unit 2000 includes a pixel clock synchronization circuit 10, the pixel clock generator 11, a counter 12, forced light emission signal generator 13
An image data storage unit 14, a laser driver 15,
And a laser 16.

[Procedure Amendment 12]

[Document name to be amended] Statement

[Name of item to be corrected] 0032

[Correction method] Change

[Correction content]

The pixel clock synchronization circuit 10 synchronizes the virtual belt end signal from the comparator 7 with the clock signal from the pixel clock generator 11 and sends it to the counter 12 and the image data storage unit 14.

[Procedure Amendment 13]

[Document name to be amended] Statement

[Correction target item name] 0049

[Correction method] Change

[Correction content]

The belt seam portion 61 where no image is formed has a step as shown in FIG. 2, and the size of the step is much larger than the scratches and the non-linear shape of the belt end. is there. If the charging / discharging amount by the charge pump 5 is set to the same amount as that of the image forming area, the virtual belt end portion is largely deviated from the actual belt end portion, and FIG.
It becomes like an oblique one-dotted line part shown in. In order to prevent this, the belt seam marking detector 8 detects the marking 62 provided near the belt seam portion 61, and the charge pump gain switching unit 9 detects that the charge / discharge amount by the charge pump 5 is near the belt seam portion 61. Switch to larger. The charge / discharge amount is switched by the charge pump 5 by changing the charge / discharge time.

Claims (7)

[Claims] 1. An image forming apparatus for forming an image using a photoconductor belt according to a laser beam scanning method, wherein a virtual belt end signal generation unit for generating a virtual belt end signal and a virtual belt end signal generation unit for generating the virtual belt end signal. And an image forming unit that forms an image using the virtual belt end signal, the virtual belt end signal generating unit provides a marking indicating a belt seam portion on the photoconductor belt, and detects the marking. An image forming apparatus comprising: a marking detection unit; and a charging / discharging process switching unit that switches the charging / discharging process based on the marking detected by the marking detection unit. 2. The image forming unit includes a pixel clock generator, a pixel clock synchronization circuit, a counter, a forced light emission signal generating unit, an image data storage unit, a laser driver, and a laser, and the pixel The clock generator generates a clock signal for timing the output of image data, the pixel clock synchronization circuit synchronizes the virtual belt end signal with the clock signal, and the counter outputs the virtual belt end signal. The pulse and the pulse of the virtual belt end signal synchronized with the clock signal are counted as a count value, the forced light emission signal generation unit generates a laser light emission signal based on the count value from the counter, the image The data storage unit is based on the count value and the virtual belt end signal synchronized with the clock signal. Then, the image data signal is output, the laser driver outputs a laser control signal for outputting a laser beam based on the laser emission signal and the image data signal, the laser, the laser control signal The image forming apparatus according to claim 1, wherein a laser beam for forming a latent image on the photoconductor is output based on the image forming apparatus. 3. The virtual belt end signal generator includes a belt end detector, a ramp signal generator, a phase comparator, a charge pump, an integrator, a comparator, a belt seam marking detector, and a charge. When a signal indicating the start of scanning is input, the belt end detector detects the end portion of the light shielding body by laser scanning and at the same time outputs the belt end signal to the end portion of the photosensitive belt. At the same time, the output of the belt end signal is stopped, and the ramp signal generator starts the output of a voltage that rises constantly based on the detection of the end of the light shield by the belt end detector, The voltage that stops the output at the same time when the body belt end is detected is output as a ramp signal, and the phase comparator sends the belt end signal and the comparator. The phase difference signal is compared and output as a phase difference signal, the belt seam marking detector detects the marking provided on the photosensitive belt, and outputs the marking detection signal as the marking detection signal. The pump gain switching device outputs a switching signal that switches charging / discharging processing of the charge pump based on the marking detection signal, and the charge pump performs charging / discharging processing based on the phase difference signal and the switching signal. , Outputting a voltage changed by the charge / discharge processing, the integrator outputs a signal obtained by performing an integration processing of the changed voltage, the comparator compares the ramp signal and the signal subjected to the integration processing, virtual, A belt end signal is output, and the virtual belt end signal is the phase ratio as the feedback signal. 3. The image forming apparatus according to claim 1, wherein the image forming apparatus outputs the image to the image forming unit at the same time when it is sent to a comparator. 4. The phase difference signal has a detection time t from the edge of the light shield to the edge of the belt.
1, and when the detection time from the light shield end portion to the virtual belt end portion indicated by the virtual belt end signal generated by the virtual belt end signal generation means is t2, when t1> t2 Charge a certain amount of charge, t1 <t2
4. The image forming apparatus according to claim 3, wherein the signal is a signal for discharging a specified amount of electric charges at the time of, and controlling not to perform the charging / discharging process at t1 = t2. 5. The image forming apparatus according to claim 1, wherein the marking is composed of any one of a light transmitting window, a light reflecting body, and a magnetic body. 6. The belt seam marking detector is constituted by any one of a transmissive optical sensor, a reflective optical sensor, and a magnetic sensor, according to any one of claims 1 to 5. Image forming device. 7. The image forming apparatus according to claim 1, wherein a plurality of optical systems each including a laser, a collimator lens, a polygon mirror, and an Fθ lens are installed. Image forming device.