JP3581897B2 - Image forming device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus that forms an image on recording paper, and more particularly, to an image forming apparatus that can accurately detect a defect occurring in an image recorded on recording paper.
[0002]
[Prior art]
FIG. 9 is a side sectional view of a laser printer as an example of a conventional image forming apparatus, wherein 1 is a photosensitive drum carrying an electrophotographic photosensitive member on which an image is formed by an electrophotographic method, and 2 is a photosensitive drum. A cleaning unit pressed against the body drum 1; a charger 3 for uniformly charging the photosensitive drum 1 to a predetermined potential; 4 a laser diode (LD) as a light source of the laser beam L and a laser beam L from the LD A light writing unit for scanning the photosensitive drum 1 charged by the charger 3 with the laser light L, and a developing unit 5 for developing an electrostatic latent image formed on the photosensitive drum 1 with toner Reference numeral 6 denotes a toner magazine for supplying toner to the developing device 5.
[0003]
Reference numeral 7 denotes a transfer roller in contact with the outer peripheral surface of the photosensitive drum 1, reference numeral 8 denotes a fixing device, reference numeral 9 denotes a paper feed cassette for storing recording paper P, reference numeral 10 denotes a paper discharge tray formed on the upper surface of the apparatus main body, and reference numeral 11 Reference numeral denotes a paper feed roller for separating and feeding one sheet of recording paper P from the paper supply cassette 9, reference numeral 12 denotes a pair of registration rollers, and reference numeral 13 denotes a discharge for discharging the recording paper P on which the toner image is fixed to a discharge tray 10. It is a pair of paper rollers.
[0004]
Next, an image forming operation by the laser printer shown in FIG. 9 will be briefly described. The charger 3 uniformly charges the photosensitive drum 1 rotating in the direction of the arrow. The optical writing unit 4 scans the photosensitive drum 1 uniformly charged to a predetermined potential with a laser beam L modulated based on image information, thereby forming an electrostatic latent image corresponding to the image information on the photosensitive drum 1. Form. The developing device 5 develops the electrostatic latent image by selectively attaching toner to the electrostatic latent image to form a toner image on the photosensitive drum 1.
[0005]
On the other hand, one sheet of recording paper P separated and fed from the sheet feeding cassette 9 by the sheet feeding roller 11 is temporarily held by the pair of registration rollers 12 and then the leading end of the toner image formed on the photosensitive drum 1 is changed. The conveyance is resumed by the registration roller pair 12 at the timing when the predetermined position is reached. The transfer roller 7 transfers the toner image on the photosensitive drum 1 to the recording paper P fed by the registration roller pair 12. The recording paper P is separated from the photosensitive drum 1 by a separation claw not shown or the like, and is conveyed to the fixing device 8. The recording sheet P is pressed and heated by the fixing device 8 to fix the toner image thereon, and is discharged onto the discharge tray 10 by the discharge roller pair 13.
[0006]
It is known that in a laser printer device as shown in FIG. 9, the image quality changes due to the deterioration over time of the components such as the photosensitive drum 1 and changes in the external environment such as humidity during image formation. For example, an electrophotographic photosensitive member (hereinafter simply referred to as a photosensitive member) carried by the photosensitive drum 1 deteriorates with an increase in the number of exposures, and when the photosensitive member deteriorates, a phenomenon occurs in which the contrast and the image density decrease. Therefore, in a laser printer, the image quality deteriorates with time. Further, the charging characteristics of the toner also change due to the influence of temperature and humidity. From this, the toner amount per unit area attached to the electrostatic latent image formed on the photosensitive drum 1 varies depending on the temperature and humidity at the time of image formation, so that the density of the toner image is kept constant for a long time. It will be difficult to keep.
[0007]
In order to prevent the deterioration of image quality due to deterioration of the components over time and changes in the external environment as described above, an image forming apparatus using an electrophotographic method, such as a laser printer, is generally regularly maintained by a service person. Is done. In this maintenance, parts whose life is determined in advance, such as the photosensitive drum 1, are replaced as necessary, and the exposure intensity by the optical writing unit 4 and the developing unit are changed according to the state of the image recorded on the recording paper P. The recording conditions such as the voltage of the developing bias applied to the transfer roller 5 and the voltage of the transfer bias applied to the transfer roller 7 are adjusted, and further, the optical components in the optical writing unit 4, the developing device 5, the transfer roller 7, etc. Is cleaned and removed.
[0008]
If the image quality deteriorates before the period of the regular maintenance, the user calls the service center to call the service person and have the service person perform maintenance on the laser printer or find out the cause of the image quality deterioration. After that, you have to maintain it yourself by referring to the manual.
[0009]
[Problems to be solved by the invention]
However, when maintaining the laser printer, it is necessary to ascertain the density, unevenness, contrast, etc. of the entire image recorded on the recording paper, and to maintain / adjust the components so that they are maintained / adjusted to an appropriate level. It is necessary to judge the replacement time, reset the recording conditions, and find a necessary cleaning location. For this reason, it is generally difficult for the user to find the cause of the image quality deterioration, and if the recording condition of the laser printer is adjusted based on the wrong cause, the image quality may be worsened. Was.
[0010]
For the purpose of reducing the burden on the user due to such maintenance and stabilizing the image quality before the period of the periodic maintenance, JP-A-6-110285 discloses a toner image formed on a photosensitive drum. Discloses an image forming apparatus which measures the density of the image and corrects the developing bias based on the measurement result. However, in this image forming apparatus, the toner density of a test pattern formed of a low-density portion and a high-density portion formed on a photoreceptor drum is measured, and recording conditions are set so that a predetermined image density is obtained based on the measurement result. Is just a matter of optimizing. For this reason, even if image defects such as local chipping and background contamination occur in the image recorded on the recording paper, it is not possible to reset the recording conditions of the image forming apparatus so as to eliminate these image defects. There's a problem.
[0011]
An object of the present invention is to solve the above problem by accurately detecting a defect occurring in an image recorded on a recording sheet and automatically adjusting various recording conditions so that the image defect is removed. It is to provide a possible image forming apparatus.
[0012]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, an image forming apparatus according to claim 1 of the present invention comprises an image information holding unit for holding recording image information, and a recording paper on a recording sheet based on the recording image information held by the image information holding unit. And a recording unit for recording an image on an image forming apparatus, Normal recording Mode switching means for switching to either a self-diagnosis mode or a self-diagnosis mode; and image reading for reading an image recorded by the recording means on recording paper when the operation mode of the apparatus is switched to the self-diagnosis mode by the mode switching means. Means, image reading means for comparing the read image information read by the image reading means with the recorded image information held by the image information holding means, and the read image information compared by the image comparing means When a mismatch is detected between the recorded image information and the image information, the image discriminating means for discriminating the content of the discrepancy and the recording means corresponding to the discrepancy between the image information discriminated by the image discriminating means. After the recording conditions are reset, the image corresponding to the recording image information is re-recorded on the recording paper by the recording means. Also, even after resetting the recording conditions for the recording unit, if the image comparison unit detects a mismatch between the read image information and the recorded image information, the abnormality including the recorded image information for which the mismatch is detected is included. An image area and a normal image area excluding the abnormal image area are set, and partial image recorded in the abnormal image area is moved to the normal image area to generate new recording image information for recording on recording paper. Recording the partial image on recording paper by recording means based on the new recording image information. Control means.
[0013]
According to the image forming apparatus of the first aspect, the read image information is compared with the recorded image information, and when a mismatch is detected between the read image information and the recorded image information, the mismatch between the image information is determined. After the recording conditions are reset for the recording means in accordance with the content of the recording medium, the image corresponding to the recording image information is re-recorded on the recording paper, thereby causing a defect occurring in the image recorded on the recording paper. Can be accurately detected, and the recording conditions are reset so that the image defect is removed according to the content of the image defect. It is possible to easily detect the density abnormality of the whole image, the local density abnormality, the local chipping of the image, the background dirt, and the like, and automatically set an appropriate recording condition so as to eliminate these image defects. Again It is constant Also, in the original recorded image information, the image recorded in the abnormal image area is moved to the normal image area by generating new recorded image information by moving the image recorded in the abnormal image area to the normal image area. New recorded images can be recorded on recording paper, and information can be obtained from the images recorded on the recording paper. Can be.
[0014]
In addition, the image forming apparatus according to claim 2, an image information holding unit that holds recording image information, a recording unit that records an image on recording paper based on the recording image information held by the image information holding unit, In an image forming apparatus including a reading unit that reads an image recorded on a fed document sheet, a mode switching unit that switches an operation mode of the device to a normal recording mode or a self-diagnosis mode; When the operation mode of the apparatus is switched to the self-diagnosis mode by the means, the recording paper on which the image is recorded by the recording means is fed to the image reading means, and the image is read from the recording paper by the image reading means. Paper feed means, and read image information read from recording paper by the image reading means, and record image information held by the image information holding means An image comparing means for comparing, and when a mismatch is detected between the read image information and the recorded image information compared by the image comparing means, an image determining means for determining the content of the mismatch, After the recording conditions are reset for the recording means in accordance with the content of the mismatch between the image information determined by the image determination means, the image corresponding to the recorded image information is re-recorded on the recording paper by the recording means. Let Also, even after resetting the recording conditions for the recording unit, if the image comparison unit detects a mismatch between the read image information and the recorded image information, the abnormality including the recorded image information for which the mismatch is detected is included. An image area and a normal image area excluding the abnormal image area are set, and partial image recorded in the abnormal image area is moved to the normal image area to generate new recording image information for recording on recording paper. Recording the partial image on recording paper by recording means based on the new recording image information. Control means.
[0015]
According to the image forming apparatus of the second aspect, in addition to the effect obtained by the image forming apparatus of the first aspect, a dedicated image reading unit for reading an image recorded on a recording sheet is not required. By applying the present invention to an image forming apparatus such as a facsimile machine or a copying machine which is provided with an image reading unit for an original in advance, a cost increase can be suppressed.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a side view of a laser printer to which the image forming apparatus according to the first embodiment of the present invention is applied, and FIG. 2 is a block diagram showing a configuration of a control unit in the laser printer shown in FIG. In 1, members corresponding to the members already described with reference to FIG. 9 are denoted by the same reference numerals, and description of those members will be omitted in the description of the present embodiment.
[0025]
In FIG. 1, reference numeral 21 denotes a scanner unit on which a CCD (Charge Coupled Device) line image sensor, a light source for illumination, and the like are mounted, and 22, a platen roller in contact with a contact glass disposed on the upper surface of the scanner unit 21; The scanner unit 21 and the platen roller 22 are disposed downstream of the fixing device 8 and upstream of the sheet discharge roller pair 13 in the recording paper P conveyance path. Here, when the operation mode of the apparatus is switched to a self-diagnosis mode to be described later, the scanner unit 21 prints an image formed on the recording paper P conveyed at a constant speed by the platen roller 22 at a constant period on the main scanning line. And outputs a line reading signal corresponding to the image on the main scanning line. Reference numeral 23 denotes a recording paper sensor disposed immediately before the scanner unit 21 on the conveyance path of the recording paper P.
[0026]
In FIG. 2, reference numeral 31 denotes a CPU (Central Processing Unit) for controlling the entire apparatus, and 32 denotes a transmission / reception connected to a printer control device (not shown) such as a personal computer capable of outputting an image signal via a communication line, a cable, or the like. The control unit 33 includes various operation keys operated by the user, a liquid crystal panel, and an LED (Light Emitting).
An operation / display unit having a display panel for displaying various kinds of information to a user by means of a Diode, etc., and a ROM (Read) in which a program for controlling the apparatus is stored
An Only Memory (35) stores control data for defining operating conditions of the apparatus, a RAM (Random Access Memory) functioning as a work memory of the CPU 31, and a 36 corresponds to an image to be recorded on the recording paper P. An image memory 37 for temporarily storing recording image information; 37, an optical writing unit control unit for generating a drive signal for modulating light emission of an LD (Laser Diode) based on the recording image information; Is a scanner unit control unit that accumulates a line reading signal for each main scanning line read by the scanner and generates read image information corresponding to one image.
[0027]
Next, a description will be given of a processing operation and an image recording operation for image information in the above-described laser printer device of the present embodiment. The image memory 36 serving as image information holding means holds page-by-page recording image information input from the printer control device via the transmission / reception control unit 32. The CPU 31 outputs recording image information corresponding to the first page from the image memory 36 to the optical writing unit control unit 37 by issuing a recording command from the printer control device or the operation / display unit 33.
[0028]
The CPU 31 turns on the optical writing unit 4 in synchronization with the input of the recording image information, and causes the LD to emit light based on the drive signal generated by the optical writing unit control unit 37, thereby causing the laser from the optical writing unit 4 to emit light. An electrostatic latent image is formed on the photosensitive drum 1 which is charged to a predetermined potential by the light L and rotates in the direction of the arrow. Thereafter, as in the case of the conventional laser printer, the electrostatic latent image is developed by the developing device 5 to form a toner image on the photosensitive drum 1, and the toner image is transferred by the transfer roller 7 to the recording paper P. Is transferred to After the recording sheet P is heated and pressed by the fixing unit 8 to fix the toner image, the recording sheet P is inserted between the scanner unit 21 and the platen roller 22, and is fixed on the scanner unit 21 by the platen roller 22. At a reading speed of The recording paper P discharged from the scanner unit 21 by the platen roller 22 is discharged onto the discharge tray 10 by the discharge roller pair 13.
[0029]
Further, in the laser printer device of the present embodiment, in order to prevent the deterioration of the image quality due to the aging deterioration of components related to the electrophotographic process such as the photosensitive drum 1 and the change of the external environment such as temperature and humidity, the operation of the device is performed. The mode is switched from the normal recording mode to the self-diagnosis mode, and the recording conditions for forming an image on the recording paper P are reset. Here, the recording conditions are, for example, the exposure intensity of the photoconductor drum 1 by the optical writing unit 4, that is, the light emission intensity of the LD, the voltage of the developing bias applied to the developing device 5, and the transfer applied to the transfer roller 7. The bias voltage and the like include the state of components that affect image quality in the electrophotographic process, for example, the state of adhesion of dirt.
[0030]
FIG. 3 is a flowchart for explaining the control operation in the self-diagnosis mode in the laser printer shown in FIG. The operation when the operation mode of the laser printer device of the present embodiment is switched to the self-diagnosis mode will be described with reference to FIG.
[0031]
The switching of the operation mode itself is executed by the CPU 31 having a function as a mode switching means. The user can switch the operation mode or set the switching timing by the following two methods. First, when the user operates a mode switching key (not shown) arranged on the operation / display unit 33 in the normal recording mode, the operation / display unit 33 outputs a mode switching signal to the CPU 31. The CPU 31 switches the operation mode from the normal recording mode to the self-diagnosis mode in response to the input of the mode switching signal. The RAM 35 stores a constant for defining the switching timing of the operation mode. The CPU 31 switches the operation mode from the normal recording mode to the self-diagnosis mode at regular intervals corresponding to the constant stored in the RAM 35. . Here, the fixed cycle for switching the operation mode may be defined by the number of transfers since the previous mode switching, or by the elapsed time from the completion of resetting the recording condition in the previous self-diagnosis mode. Is also possible. Further, the constant for defining the switching timing of the operation mode may be stored in the RAM 35 before shipment from the factory according to the model or the like, or an arbitrary value may be stored in the RAM 35 by the operation / display unit 33 by the user. You may be able to.
[0032]
When the operation mode is switched from the normal recording mode to the self-diagnosis mode at the above timing (step S1), the CPU 31 records image information corresponding to a predetermined test pattern image stored in the image memory 36 (hereinafter, recorded image information). Information D _T Is output to the optical writing unit control unit 37 (step S2). At this time, the recorded image information D _T Is continuously stored in the image memory 36 without being erased. Thus, a test pattern image is recorded on the recording paper P based on a known electrophotographic process. When the recording paper P on which the test pattern image is recorded turns on the recording paper sensor 23, the CPU 31 turns on the scanner unit 21 and reads the image recorded on the recording paper P by the scanner unit 21 (steps S3 to S3). S4).
[0033]
The scanner unit control section 38 accumulates the line read signal from the scanner unit 21 and stores the read image information (hereinafter, read image information D). _S ), And the read image information D _S Is stored in the image memory 36 (step S5). The CPU 31 having functions as an image comparing unit and an image determining unit reads the read image information D in the image memory 36. _S Is recorded image information D _T And the read image information D _S And recorded image information D _T Is determined (step S6).
[0034]
Then, the CPU 31 reads the read image information D _S And recorded image information D _T If it is determined that is the same (NO in step S6), the self-diagnosis mode is terminated and the operation mode is returned to the normal recording mode because there is no need to adjust the recording conditions (step S7). . Further, the CPU 31 returns the operation mode to the normal recording mode, and displays on the display panel of the operation / display unit 33 that the self-diagnosis mode has ended and that image recording on the recording sheet P can be normally performed.
[0035]
On the other hand, the CPU 31 reads the read image information D _S And recorded image information D _T Is determined to be inconsistent with the recorded image information D (step S6: YES). _T Image information D in comparison with _S Is detected, and the content of the mismatch is determined (step S8). The CPU 31 has the image information D _S , D _T For example, the type of image defect such as an abnormal image density, background contamination, blurring of a continuous image, or a local omission of an image is determined as the content of the mismatch. Further, it is determined whether or not these image defects have directionality, continuity, and periodicity, and the read image information D is determined based on the determination results. _S And recorded image information D _T Then, the cause of the mismatch is estimated (step S9). As a method of estimating the cause of the mismatch, a data table is provided in the ROM 34 for each type of image defect, and the cause of the mismatch is stored in the data table in accordance with the combination of the directionality, continuity, and presence or absence of periodicity. Is set, and the CPU 31 is caused to read from the data table corresponding to the type of the image defect the cause of the mismatch that matches the combination of the presence / absence of the directionality, continuity, and periodicity. Further, the ROM 34 stores the image information D _S , D _T Image information D according to the type of cause of the mismatch between _S , D _T An adjustment program for adjusting the recording condition so as to remove the discrepancy between them is stored.
[0036]
The CPU 31 reads the read image information D _S And recorded image information D _T After estimating the cause of the mismatch between the image information D and the image information D _S , D _T Is determined (step S10), and the image information D is adjusted by adjusting the recording conditions. _S , D _T If it is determined that the inconsistency cannot be removed (No in step S10), it is impossible for the user to correct the image defect using the operation / display unit 33, and the repair / adjustment is performed by a service center or the like. Is displayed, and the operation mode is returned to the normal recording mode (steps S11 to S12).
[0037]
Further, the CPU 31 adjusts the recording condition to adjust the image information D. _S , D _T If it is determined that the mismatch can be removed (Yes in step S10), the image recording condition on the recording sheet P is reset according to the adjustment program corresponding to the cause of the mismatch between the image information (step S13). . When the resetting of the recording condition is completed, the CPU 31 executes the same control as in steps S3 to S6 described above in steps S14 to S17 again, and reads the read image information D. _S And recorded image information D _T Is determined to be the same (No in step S17), it is not necessary to readjust the recording conditions, so that the self-diagnosis mode is terminated and the operation mode is returned to the normal recording mode (step S18). ).
[0038]
On the other hand, the CPU 31 reads the read image information D _S And recorded image information D _T If it is determined that there is a mismatch between the image information D and the image information D _S , D _T It is determined that the inconsistency cannot be removed, and it is impossible for the user to correct the image defect by the operation / display unit 33. Therefore, an alarm message notifying that a repair / adjustment is requested to a service center or the like is displayed. At the same time, the operation mode is returned to the normal recording mode (steps S19 to S20).
[0039]
Next, in the self-diagnosis mode in the laser printer of the present embodiment, the read image information D _S And recorded image information D _T A description will be given of a specific example of a countermeasure in a case where a mismatch is detected, that is, when an image defect occurs in a recorded image. 4 and 5 are explanatory diagrams showing a test pattern image used in the self-diagnosis mode and a recorded image in which an image defect has occurred, respectively. Here, FIGS. 4A and 5A are test pattern images. 4 (b) and FIG. 5 (b) show images formed on the recording paper P, respectively.
[0040]
In the recorded image shown in FIG. 4B, a longer toner stain occurs in the transport direction of the recording paper P (sub-scanning direction) than the test pattern image shown in FIG. 4A. As a cause of such an image defect, it is presumed that foreign matter such as toner adheres to the charging wire of the charger 3 and a charging failure to the photosensitive drum 1 occurs. Therefore, in such a case, it is determined that the charging wire of the charger 3 needs to be cleaned in order to prevent the occurrence of image defects. At this time, when the apparatus has a wire cleaner mechanism for the charger 3, the CPU 31 activates the wire cleaner mechanism to clean the charging wire of the charger 3, and does not include the wire cleaner mechanism. In this case, the operation / display unit 33 displays a message instructing the user to clean the charging wire of the charger 3.
[0041]
Further, in the recorded image shown in FIG. 5B, compared with the test pattern image shown in FIG. 5A, the image is periodically or continuously missing in the sub-scanning direction. As a cause of such an image defect, it is presumed that image formation is disabled at the damaged portion because the photosensitive drum 1 is locally damaged. Therefore, in such a case, it is determined that it is necessary to replace the photosensitive drum 1 or a process cartridge which is a replacement part including the photosensitive drum 1 in order to prevent the occurrence of image defects. At this time, the CPU 31 determines that the image defect cannot be removed by adjusting the recording conditions, and it is impossible for the user to correct the image defect by the operation / display unit 33. Display an alarm message notifying that a request is made.
[0042]
However, even if an image defect as shown in FIG. 5B occurs and it is determined that the image defect cannot be removed by adjusting the recording conditions, the user wants to record the image on the recording paper P and obtain information from the recorded image. Sometimes. Even in such a case, the laser printer according to the present embodiment has an image division program for enabling information to be obtained from an image recorded on the recording paper P.
[0043]
Next, the image division program will be described. Even when an alarm message notifying that a repair / adjustment is requested to a service center or the like in the self-diagnosis mode is displayed, when it is necessary to urgently obtain information from the image recorded on the recording paper P, the ROM 34 is used. An operation for activating the image division program stored in the operation / display unit 33 is executed. Thereby, when forming an image on the recording paper P based on the recording image information in the normal recording mode, the CPU 31 detects the recording image information in which the mismatch is detected with respect to the image forming area corresponding to the recording image information. Is set, and an abnormal image area excluding the abnormal image area is set.
[0044]
When an image is recorded in the abnormal image area, the CPU 31 deletes the image recorded in the abnormal image area from the original recorded image information because there is a strong possibility that the user cannot read the image due to some image defect. In the original recorded image information, new recorded image information is generated by moving the image recorded in the abnormal image area to the normal image area. Then, the CPU 31 outputs to the image memory 36 the original recorded image information from which the image recorded in the abnormal image area has been deleted and the new recorded image information in which the image recorded in the abnormal image area has moved to the normal image area. Then, an image is recorded on each of two recording papers P based on these two pieces of recording image information.
[0045]
For example, as shown in FIG. 5B, when the image defect occurs only in one of the two image areas divided by the center line in the main scanning direction, as shown in FIG. As shown, two normal image areas A divided by a center line in the main scanning direction with respect to an image forming area A corresponding to the recorded image information. ₁ And abnormal image area A ₂ Is set, and as shown in FIG. ₂ Image information and abnormal image area A from which the image recorded in ₂ The image recorded in the normal image area A ₁ Two recording papers P based on the new recording image information moved to ₁ , P ₂ , Respectively, to record an image. Here, the number of divisions of the image area divided by the image division program does not need to be limited to two, and it is also possible to divide the image area into two or more and disperse and record the image on the recording paper P of the number equal to the division number. It is possible. Further, it is not necessary to divide the image area equally, and it is also possible to divide the image area based on an arbitrary position in the sub-scanning direction as a reference.
[0046]
Further, in the description of the control operation in the self-diagnosis mode described above, the description has been given based on the case where the entire image surface of the recording paper P is read by the scanner unit 21. The scanner unit 21 needs to be provided with a line image sensor wider than the width of the recording paper P. However, it is rare that an image is recorded uniformly on the entire image surface of the recording paper P, and the reading width by the line image sensor becomes longer, and the cost of the scanner unit 21 of the sensor increases rapidly. Therefore, as shown in FIG. _P The image recorded on the recording paper P is read using a CCD line image sensor 21a having a reading width W of about 1/2 _S And recorded image information D _T The cost of the scanner unit 21 can be greatly reduced without significantly lowering the detection accuracy when detecting a mismatch with the scanner unit 21.
[0047]
FIG. 8 is a cross-sectional view of a facsimile apparatus to which the image forming apparatus according to the second embodiment of the present invention is applied. In FIG. 8, members corresponding to those already described with reference to FIG. 9 are the same. The reference numerals are used, and description of those members is omitted in the description according to the present embodiment.
[0048]
The facsimile apparatus shown in FIG. 8 is different from the laser printer apparatus shown in FIG. 1 in the structure of the facsimile apparatus in that a document scanner apparatus B is provided above a printer apparatus A having the same functions as the laser printer apparatus shown in FIG. A guide lever 24 for switching the transport destination of the recording paper P discharged from the fixing device 8 is disposed at the boundary between the printer A and the original scanner B, and is dedicated to reading the image of the recording paper P. Is that the scanner unit 21 is omitted.
[0049]
Here, the document scanner apparatus B separates one document from one or a plurality of documents (hereinafter, referred to as a document bundle) loaded in the document loading unit 51 and curves the document in a substantially U-shape. The document is transported along the document transport path 52, and the image formed on the document is read by the scanner unit 53 and discharged onto the document discharge unit 54. Further, the control unit in the facsimile apparatus shown in FIG. 8 is configured similarly to that shown in FIG. 2, and the scanner unit control unit 38 accumulates a line reading signal from the scanner unit 53 instead of the scanner unit 21, Generate read image information corresponding to one image.
[0050]
In the operation when the operation mode of the apparatus is switched from the normal recording mode to the self-diagnosis mode, the difference between the facsimile apparatus shown in FIG. 8 and the laser printer apparatus shown in FIG. 1 is that the guide lever 24 is indicated by a two-dot chain line. The recording paper P ejected from the fixing device 8 is slid from the position shown to the position shown by the solid line, fed into the document transport path 52 of the document scanner B, and a test is performed on the recording paper P by the scanner unit 53. The point is that the pattern image is read. At this time, the CPU 31 controls the scanner unit 53, the guide lever 24 that constitutes the reading paper feeding unit, and the pair of conveyance rollers 55 arranged in the document conveyance path 52. By turning off 53 and ending the self-diagnosis mode, the transport roller pair 55 is stopped, and the guide lever 24 is returned to the position indicated by the solid line.
[0051]
The CPU 31 reads the read image information D in the self-diagnosis mode in the same manner as described with reference to FIG. _S And recorded image information D _T And the image information D _S , D _T The recording conditions for recording an image on the recording paper P based on the electrophotographic process are reset so that the discrepancy between the components is eliminated, and the deterioration of parts such as the photosensitive drum 1 related to the electrophotographic process with the lapse of time and the like. This prevents image quality from changing due to changes in the external environment such as humidity.
[0052]
Further, if necessary, the CPU 31 executes the image division program to execute the image recording program to delete the original recorded image information from which the image recorded in the abnormal image area has been erased and to move the image recorded in the abnormal image area to the normal image area. The recorded image information is output to the image memory 36, and an image is recorded on each of two recording sheets P based on the two recorded image information.
[0053]
【The invention's effect】
As described above, according to the image forming apparatus of the present invention, the read image information is compared with the record image information, and when a mismatch is detected between the read image information and the record image information, the image information After resetting the recording condition for the recording means in accordance with the content of the mismatch, the image corresponding to the recorded image information is re-recorded on the recording paper, thereby causing an image generated on the recording paper. Can be detected with high accuracy, and the recording conditions are reset so that the image defect is removed in accordance with the content of the image defect. For example, it is possible to easily detect a density abnormality of the entire image, a local density abnormality, a local chipping of the image, a background stain, and the like, and automatically set an appropriate recording condition so as to eliminate these image defects. It is possible to re-set.
[Brief description of the drawings]
FIG. 1 is a side view of a laser printer to which an image forming apparatus according to a first embodiment of the present invention is applied.
FIG. 2 is a block diagram showing a configuration of a control unit in the laser printer shown in FIG.
FIG. 3 is a flowchart for explaining a control operation in a self-diagnosis mode in the laser printer shown in FIG. 1;
FIG. 4 is an explanatory diagram showing a test pattern image used in a self-diagnosis mode and a recorded image in which an image defect has occurred.
FIG. 5 is an explanatory diagram showing a test pattern image used in a self-diagnosis mode and a recorded image in which an image defect has occurred.
FIG. 6 is an explanatory diagram of a divided image processed by an image dividing program.
FIG. 7 is an explanatory diagram showing an example of a line image sensor and an image reading range in the laser printer device shown in FIG. 1;
FIG. 8 is a cross-sectional view of a facsimile apparatus to which an image forming apparatus according to a second embodiment of the present invention has been applied.
FIG. 9 is a side sectional view of a laser printer as an example of a conventional image forming apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Photoreceptor drum, 3 ... Charger, 4 ... Optical writing unit, 5 ... Developing unit, 7 ... Transfer roller, 21, 53 ... Scanner unit, 22 ... Platen roller, 23 ... Recording paper sensor, 24 ... Guide lever, 31: CPU, 32: Transmission / reception control unit, 33: Operation / display unit, 34: ROM, 35: RAM, 36: Image memory, 37: Optical writing unit control unit, 38: Scanner unit control unit, P: Recording paper

Claims (2)

An image forming apparatus comprising: an image information holding unit that holds recording image information; and a recording unit that records an image on recording paper based on the recording image information held by the image information holding unit.
A mode switching means for switching the operation mode of the apparatus between the normal recording mode and the self-diagnosis mode; and an image recorded by the recording means when the operation mode of the apparatus is switched to the self-diagnosis mode by the mode switching means. Image reading means for reading the image from the recording paper, image comparing means for comparing the read image information read by the image reading means with the recorded image information held by the image information holding means, When a mismatch is detected between the read image information and the recorded image information, image discriminating means for discriminating the content of the discrepancy, and a discrepancy content between the image information discriminated by the image discriminating means. After resetting the recording conditions for the recording means in accordance with the above, the recording means corresponds to the recording image information for the recording paper. That the image is recorded again, also, the even after re-setting of the recording conditions for the recording means, when a mismatch between the read image information and the recorded image information is detected by the image comparison means, mismatch An abnormal image area including the detected recording image information and a normal image area excluding the abnormal image area are set, and a partial image recorded in the abnormal image area is moved to the normal image area and recorded on recording paper. image forming apparatus characterized by generating a new record image information, and control means for Ru is recording the partial image on a recording paper by the recording means on the basis of the new recording image information for. Image information holding means for holding recording image information, recording means for recording an image on recording paper based on the recording image information held by the image information holding means, and an image recorded on a fed document sheet An image forming apparatus comprising:
A mode switching means for switching the operation mode of the apparatus to the normal recording mode or the self-diagnosis mode; and an image is recorded by the recording means when the operation mode of the apparatus is switched to the self-diagnosis mode by the mode switching means. Reading paper feeding means for feeding the recording paper fed to the image reading means and reading an image from the recording paper by the image reading means; and holding the image information read from the recording paper by the image reading means. Means for comparing the recorded image information with the recorded image information held by the means, and if a mismatch is detected between the read image information and the recorded image information compared by the image comparison means, the content of the mismatch Image discriminating means for discriminating the image information, and writing the information to the recording means in correspondence with the content of the mismatch between the image information discriminated by the image discriminating means. After re-set conditions, re-recorded by an image corresponding to the recorded image information to the recording sheet by the recording unit, also after re-setting of the recording conditions for the recording means, reading said by the image comparing unit image When a mismatch is detected between the information and the recorded image information, an abnormal image region including the recorded image information where the mismatch is detected and a normal image region excluding the abnormal image region are set, and the abnormal image is set. The partial image to be recorded in the area is moved to the normal image area to generate new recording image information for recording on recording paper, and the partial image is recorded on recording paper by recording means based on the new recording image information. an image forming apparatus characterized by comprising a control means for Ru is recorded.

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