JP2003295716A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a user from being charged for the formation of an abnormal image in error. <P>SOLUTION: A photodetector detects light from a laser diode (LD) for exposing and scanning a photosensitive drum and outputs a synchronization detection signal (DETP signal) for performing positioning in the main scanning direction of optical writing of an electrostatic latent image in the drum. A forced lighting signal for emitting the LD is added to an LD driving signal in order to obtain the DETP signal. Whether the output timing of the DETP signal and the forced lighting signal is normal or not is judged, and when the existence of abnormality is judged (Y of step S21), the counting-up operation of a total counter for counting up the total number of prints in order to charge the user for printing is inhibited (step S22). <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus.

[0002]

2. Description of the Related Art The technique disclosed in Japanese Unexamined Patent Publication No. 8-252945 discloses a horizontal synchronizing signal for accurately determining a period abnormality of a horizontal synchronizing signal, which is one of the causes of intensive deterioration of a certain portion of a photoconductor. Monitors whether the cycle of the sync signal is longer than the reference cycle or normal, and when it is judged to be abnormal, continuously turns on the laser diode that optically writes the electrostatic latent image on the photoconductor to generate the horizontal sync signal. In order to reliably detect the period of the horizontal synchronizing signal, the photodetector for receiving the laser beam certainly receives the light from the laser diode to identify the cause of the period abnormality.

[0003]

In an electrophotographic image forming apparatus such as a digital copying machine or a laser printer, an electrostatic latent image is recorded on a photosensitive member by exposure scanning of a laser beam. In such raster scanning, synchronization in scanning signals is important, and if synchronization between main scans is not established, the vertical lines of an image to be formed will be jagged.

Also in the image forming apparatus in which the main scanning is synchronized, abnormal rotation of the polygon motor for rotating the polygon mirror for scanning the laser beam due to external noise such as static electricity during printing may occur. An abnormality occurs in the CLK signal used for optically writing the electrostatic latent image, and abnormal images such as vertical line fluctuations and horizontal stripes occur.

Further, the digital copying machine is provided with a total counter for counting the total number of printed sheets in order to collect a fee from the user according to the number of printed sheets.

However, the vertical line fluctuations as described above,
Even if an abnormal image such as a horizontal stripe is generated, if the total number of printed sheets is counted up by the total counter, there is a problem that the user is erroneously charged for the number of printed sheets having the abnormal image.

An object of the present invention is to prevent the user from being erroneously charged for the formation of an abnormal image.

[0008]

According to a first aspect of the present invention, in an image forming apparatus for forming an image on a sheet by an electrophotographic method, an exposure is performed by scanning a photosensitive member to optically write an electrostatic latent image. An apparatus, a photodetector that detects light output from the exposure apparatus, and outputs a synchronization detection signal for performing position alignment in the main scanning direction of optical writing of an electrostatic latent image on the photoconductor; A light emitting unit that adds a forced lighting signal for causing the light emitting element to emit light to obtain a detection signal to the drive signal of the light emitting element, and whether or not the output timing of at least one of the synchronization detection signal and the forced lighting signal is normal or not is determined. Judgment means for judging, a total counter for counting the total number of sheets of the image formation for charging for the image formation, and the synchronization detection signal or the forced lighting signal by the judgment means. When the output timing is judged to be abnormal, an image forming apparatus, characterized in that even if the image formation is performed and a, and inhibiting means for inhibiting the counting of the total counter.

Therefore, when an abnormal image is generated due to an abnormal output timing of the synchronization detection signal or the forced lighting signal, the total counter is not counted up, so that the user is mistakenly charged for the formation of the abnormal image. Can be prevented.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, when the determination unit determines that the output timing of the synchronization detection signal or the forced lighting signal is abnormal, the inhibition unit causes It is characterized by further comprising setting means for setting whether or not to prohibit the total counter from counting up even when the image formation is performed, and reception means for receiving the input of the setting of the setting means.

Therefore, when an abnormal image occurs,
Since it is possible to set whether or not to count up the total counter, it is possible to deal with the occurrence of an abnormal image in accordance with the purpose.

The invention according to claim 3 is the invention according to claim 1 or 2.
In the image forming apparatus according to the item (1), when the determination unit determines that the output timing of the synchronization detection signal or the forced lighting signal is abnormal, an abnormal image counter that counts the number of images formed is provided. Is characterized by.

Therefore, it is possible to know both the number of formed images of only the abnormal image and the total number of formed images including the abnormal image from the count values of the total counter and the abnormal image counter.

The image forming apparatus according to any one of claims 1 to 3, further comprising an image reading device for reading an image of an original, and the image forming is performed based on the image data read by the image reading device. It may be performed (Claim 4).

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described.

FIG. 1 is a block diagram showing a schematic configuration of a digital copying machine according to this embodiment. This digital copying machine implements the image forming apparatus of the present invention.

As shown in FIG. 1, this digital copying machine is a scanner 1 which is an image reading device for reading an image of a document.
Is equipped with. The scanner 1 A / D-converts a read image signal to perform signal processing such as black offset correction, shading correction, and pixel position correction.
And an image processing circuit 3 for performing various image processes on the image signal after A / D conversion, and outputs the image signal after these processes to the printer 14.

The printer 14 forms an image read by the scanner 1 on a sheet by electrophotography. Printer 14
Is a laser diode (LD) 21 which is a light emitting element for optically writing an electrostatic latent image on a photoconductor drum 24 (see FIG. 2) not shown, an LD control section 5 for controlling the LD 21, and a printer 14. A printer control unit 4 for controlling the whole is provided.

The CPU 7 centrally controls the digital copying machine, the ROM 8 stores various control programs executed by the CPU 7, and the RAM 9 serves as a work area of the CPU 7. The image memory 12 stores the image data read by the scanner 1. Data is exchanged between the respective devices via the system bus 10, and the I / F 11 serves as an interface between the system bus 10 and the image processing circuit 3. The operation panel 13 displays various messages to the user and accepts various operations from the user.

FIG. 2 is a block diagram showing a schematic configuration of the printer 14. The laser beam emitted from the LD 21 is collimated by a collimator lens (not shown), deflected by a deflector 22 composed of a rotary polygon mirror, imaged on the surface of the photosensitive drum 24 by an fθ lens 23, and charged by a charger (not shown). The surface of the rotating photosensitive drum 24 is exposed and scanned. An exposure device is realized by the LD 21, a collimator lens (not shown), a deflector 22, an fθ lens 23, and the like.

The photodetector 25 is arranged outside the information writing area on the surface of the photoconductor drum 24, receives and detects the laser beam deflected by the rotary polygon mirror 22, and detects the laser beam to the photoconductor 24 by the LD 21. A synchronous detection signal (hereinafter referred to as "DET") for performing position alignment in the main scanning direction of optical writing of a latent image.
P signal ”). The printer control unit 4 outputs the image signal to the semiconductor laser drive circuit 26, and controls the timing by the DETP signal from the photodetector 25. The semiconductor laser drive circuit 26 drives the LD 21 in response to an image signal from the printer control unit 4 to form an electrostatic latent image on the photosensitive drum 2. This electrostatic latent image is developed by a developing device (not shown) and transferred onto a sheet or the like by a transfer device (not shown).

The laser beam emitted from the LD 21 in a direction different from that of the deflector 22 is a photodetector (PD) 2
Incident on 7, the light intensity of the laser beam is detected,
The control circuit 28 controls the semiconductor laser drive circuit 26 according to the output signal of the PD 27 to make the output light amount of the LD 21 constant (APC control). Specifically, the drive power supply for each light emitting element of the LD 21 is adjusted and held by an external signal so that the output light amount becomes constant.

FIG. 3 is a block diagram showing a schematic configuration of electrical connection between the printer control unit 4 and its peripheral portion. Figure 3
As shown in FIG. 3, the printer control unit 4 includes a memory block 31 that performs speed conversion and format conversion of the image data output from the image processing circuit 3, and a memory block 31.
The image processing unit 32 performs image processing on the image data from the image processing unit 32, and the output data control unit 34 performs processing such as γ conversion and P sensor pattern addition on the image data from the image processing unit 32. Output data control unit 3
4, the output data is sent to the LD control unit, and the output data control unit 34 has a PLL (phase locked loop) circuit 3
CLK signal from 7, 38, DET from sync detection plate 40
P signals are input respectively.

FIG. 4 is a block diagram showing the structure of the output data control unit 34. As shown in FIG. 4, the clock control unit 48 performs phase control based on the DETP signal from the synchronization detection plate 40 and the CLK signal from the PLL circuit 37, thereby driving the main scanning counter 49 and the sub-scanning counter 50. Then, based on the outputs of the main scanning counter 49 and the sub-scanning counter 50, the main / sub-scanning gate signal generation unit 54 generates a gate signal and outputs it to each block. The output data control unit 34 adds to the image signal from the image processing unit 32 a P sensor pattern for putting toner of a certain density on the photoconductor drum 24 in order to acquire data that determines the image forming process condition. A P pattern block 45 for changing the weight of the image data and a γ conversion block 46 for changing the weight of the image data. Further, in synchronization with the timing of the APC control operation for keeping the light amount of the LD 21 constant, image data is added to a DATA signal described later that drives the LD 21, and a forced lighting signal described below is added to LDon / o.
ff Block 47 is also provided. LD on / off block 47
The light emitting means is realized by.

Further, a clock control unit 51 for generating a CLK signal whose phase is controlled based on the DETP signal from the synchronization detection plate 40 and the CLK signal from the PLL circuit 38, and a synchronization detection monitoring signal, which will be described later, by the CLK signal. A monitoring signal generation unit 52 that generates a lighting monitoring signal and an abnormality monitoring unit 53 that monitors a DETP signal and a DATA signal described later are provided.

FIG. 5 is a timing chart of each signal of the printer 14. In FIG. 5, the DETP signal is active low, and the DATA signal which is the output signal of the LDon / off block 47 is active high. First, in order to obtain the DETP signal, a forced lighting signal is added to the DATA signal in addition to the image data, and L is set at a predetermined timing.
Control for turning off the forced lighting signal (DATA signal) when the DETP signal is input is started for each main scan. That is, in FIG. 5, in the DATA signal, the symbol a corresponds to a signal for writing the image data of each main scan by lighting the LD 21 and optically writing the image data.
Reference symbol b corresponds to a compulsory lighting signal for lighting the LD 21 so that the photodetector 25 receives light between each main scan in order to generate the DETP signal.

The synchronization detection monitor signal and the forced lighting monitor signal are PLL circuits 38 whose phases are controlled by the synchronization signal.
It is generated by the monitor signal generation unit 52 by the CLK signal sent by. The abnormality monitoring unit 53 monitors the DETP signal when the synchronization detection monitoring signal is high, and determines that the DETP signal is normal when the DETP signal is low during that period and abnormal when the DETP signal is not low. Further, the abnormality monitoring unit 53
When the forced lighting monitoring signal is high, the DATA signal is monitored, and if the DATA signal becomes high during that period, it is determined to be normal, and if it is not high, it is determined to be abnormal.

In FIGS. 6 and 7, the CPU 7 has an abnormality monitoring section 53.
It is a flowchart of the process performed via. First, as shown in FIG. 6, when the forced lighting monitoring signal becomes high during the operation of the printer 14 and the timing of monitoring the DATA signal (forced lighting signal) comes (step S1).
Y), it is determined whether the DATA signal is low (step S2), and if it is low (Y in step S2),
It is determined that an abnormality has been detected (step S3). When it is not low (N in step S2), it is determined whether or not the DATA signal is high (step S4), and the DATA signal is high.
h and the forced lighting monitoring signal is high, DATA
When it is time to monitor the signal (forced lighting signal) (Y in step S4, N in step S5), it is determined that an abnormality has been detected (step S3).

If not (N in step S4),
When it is determined that there is no abnormality (step S5) and the copying operation by the digital copying machine is continuing (step S5)
6 N), the process returns to step S1, and when the process is completed (Y in step S6), the process is completed.

Further, as shown in FIG. 7, during the operation of the printer 14, the synchronization detection monitoring signal becomes high and the DET
When it is time to monitor the P signal (step S
11), it is determined whether or not the DETP signal is high (step S12), and when it is high (Y in step S12), it is determined that an abnormality has been detected (step S1).
3). When it is not high (N in step S12),
It is determined whether the DETP signal is high (step S1
4) When the DETP signal is high and the forced lighting monitoring signal is high and the timing for monitoring the DETP signal is reached (Y in step S14, N in step S15), it is determined that an abnormality has been detected (step S13). .

If not (N in step S14), it is judged that there is no abnormality (step S15), and if the copying operation by the digital copying machine is continuing (N in step S16), the process returns to step S11. If it has ended (Y in step S16), the process ends.
Judgment means is realized by the abnormal processing shown in FIGS.

Then, the CPU 7 performs the processing shown in FIG.
That is, this digital copying machine is provided with a total counter for counting the total number of printed sheets printed by the printer 14 in order to charge the user according to the number of printed sheets, and the count value of the total counter indicates this. The usage fee is collected from the user according to the number of printed sheets. When an abnormality is detected in steps S3 and S13 during printing by the printer 14 (Y in step S21), counting up of the total counter is prohibited even if printing is performed by the printer 14 (step S22). When no abnormality is detected in steps S3 and S13 (N in step S21), if printing is performed by the printer 14, the total number of printed sheets is counted up by the total counter (step S2).
3). The prohibition means is realized by step S22.

Abnormality According to the digital copying machine explained, D
When an abnormal image occurs due to an abnormal output timing of the ETP signal or the forced lighting signal, the total counter is not counted up (step S22).
It is possible to prevent the user from being charged for the formation of the abnormal image by mistake.

Alternatively, the CPU 7 may perform the processing shown in FIGS. 9 and 10. That is, as shown in FIG. 9, the user operates the operation panel 13 to display a predetermined total counter setting screen on the display of the operation panel 13 (Y in step S41), and the printer is displayed on the total counter setting screen. It is selected whether or not to count up the total counter when the abnormal printing by 14 occurs (step S42). The input means is realized by step S42. When it is selected to count up (Y in step S42), the predetermined variable N is set to 1 (step S43), and when not to count up (N in step S42), the predetermined variable is set. N is set to 0 (step S44),
The value of the variable N is stored in the nonvolatile memory of the ROM 8 or the like. The setting means is realized by steps S43 and S44.

Then, as shown in FIG.
At the time of printing of No. 4, the value of the stored variable N is judged (step S51), and when N = 1, the total counter is incremented by the number of printed sheets (step S5).
2) If N = 0, the process proceeds to step S21 and subsequent steps (step S53).

Therefore, in this case, whether or not the total counter is counted up when an abnormal image occurs can be set by the process of FIG. 9, so that the occurrence of the abnormal image can be dealt with in accordance with the purpose. It will be possible.

Further, when an abnormality is detected in steps S3 and S13, an abnormal image counter for counting the number of printed sheets printed in the abnormal state is provided, and the processing of FIG. 11 is performed instead of the processing of FIG. You may do it. That is, when the CPU 7 determines that the abnormality is detected in steps S3 and S13 (Y in step S61), it increments the abnormal image counter according to the number of printed sheets (step S62). In this case, the total counter is not incremented. When it is determined that no abnormality is detected (N in step S61), the total counter is incremented according to the number of printed sheets (step S63). In this case, the abnormal image counter is not incremented.

Therefore, in this case, it is possible to know both the number of prints of only the abnormal image and the total number of prints including the abnormal image from the count values of the total counter and the abnormal image counter.

[0039]

According to the invention described in claim 1, it is possible to prevent the user from being erroneously charged for the formation of the abnormal image.

According to a second aspect of the invention, in the image forming apparatus according to the first aspect, when an abnormal image occurs,
By setting whether or not to count up the total counter, it is possible to deal with the occurrence of an abnormal image in accordance with the purpose.

The invention according to claim 3 is the same as claim 1 or 2.
In the image forming apparatus described in (1), it is possible to know both the number of formed images including only the abnormal image and the total number of formed images including the abnormal image.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall electrical connection of a digital copying machine according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram showing a schematic configuration of a printer of a digital copying machine.

FIG. 3 is a block diagram showing an electrical connection of a printer control unit and the like of the printer.

FIG. 4 is a block diagram showing an electrical connection of an output data control unit of the printer control unit.

FIG. 5 is a timing chart illustrating the operation of the digital copying machine.

FIG. 6 is a flowchart illustrating the operation of the digital copying machine.

FIG. 7 is a flowchart illustrating an operation of the digital copying machine.

FIG. 8 is a flowchart illustrating the operation of the digital copying machine.

FIG. 9 is a flowchart illustrating the operation of the digital copying machine.

FIG. 10 is a flowchart illustrating the operation of the digital copying machine.

FIG. 11 is a flowchart illustrating the operation of the digital copying machine.

[Explanation of symbols]

1 Image reading device 14 Printer

Claims (4)

[Claims] 1. An image forming apparatus for forming an image on a sheet by an electrophotographic method, wherein an exposure device for exposing and scanning a photoconductor to optically write an electrostatic latent image, and detecting light output from the exposure device. And a photodetector for outputting a synchronization detection signal for aligning the optical writing of the electrostatic latent image on the photoconductor in the main scanning direction, and forcing the light emitting element to emit light to obtain the synchronization detection signal. A light emitting means for adding a lighting signal to the drive signal of the light emitting element, a judging means for judging whether the output timing of at least one of the synchronization detection signal and the forced lighting signal is normal, and for charging for the image formation. And a total counter for counting the total number of sheets of the image formation, and when the determination unit determines that the output timing of the synchronization detection signal or the forced lighting signal is abnormal. An image forming apparatus characterized by even the image forming is performed and a, and inhibiting means for inhibiting the counting of the total counter. 2. When the determination unit determines that the output timing of the synchronization detection signal or the forced lighting signal is abnormal, whether or not the count-up of the total counter is prohibited even if the image formation is performed by the prohibition unit. The image forming apparatus according to claim 1, further comprising: a setting unit that sets whether or not the setting unit and a receiving unit that receives an input of the setting of the setting unit. 3. An abnormal image counter for counting the number of images formed when the determination unit determines that the output timing of the synchronization detection signal or the forced lighting signal is abnormal. The image forming apparatus according to claim 1 or 2. 4. An image reading device for reading an image of a document is provided, and the image formation is performed based on image data read by the image reading device.
The image forming apparatus according to any one of 1.