JPH0630203A - Image forming device - Google Patents

Abstract

PURPOSE:To maintain a print function in a satisfactory condition with simple constitution by using a scanner part as every kind of detecting means. CONSTITUTION:An original and recording paper can be carried on the same carrier path 27, and the scanner part 26 is installed at the downstream side in the carrying direction from a transfer part at a photosensitive material 4 and a transfer charger 8 in a printer part. The degree of ground staining of a part to be ground stain-detected(white ground part) on the recording paper 3 on which an image is formed is detected by the scanner part 26, and a bias voltage, the rotating speed of a developing roller 7a, and the transfer current of the transfer charger 8 can be controlled based on a detection 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 having a printer section and a scanner section.

[0002]

2. Description of the Related Art Conventionally, in a printer or the like which forms an image by an electrophotographic method using a dry toner, an automatic density control means for controlling the density of a formed image to be constant,
Various control means and detection means for maintaining the printer function in a constant state, such as toner consumption amount detection means, stain detection means for determining whether or not toner cleaning is necessary for each part of the printer unit, are provided. ing.

[0003]

SUMMARY OF THE INVENTION In the above-mentioned conventional printers and the like, many independent control means or detection means are required in order to maintain the printer function in a constant and good state, and the structure becomes complicated and high. It is a cause of cost.

It is an object of the present invention to provide an image forming apparatus in which the scanner section is used as various detecting means and the print function can be maintained in a good condition with a simple structure.

[0005]

In order to achieve the above object, a printer section for forming an image on a recording sheet and a scanner section for reading an image of an original and replacing it with image data are provided, and recording is performed on the same conveyance path. In an image forming apparatus that conveys a paper and an original, the first means of the present invention includes a scanner unit for enabling the reading of the background stain detection portion of the image-formed recording paper sent from the printer unit. It is characterized in that it is provided on the downstream side of the printer section in the carrying direction, and has means for adjusting the image density on the basis of the detection signal of the background stain detection section from the scanner section.

The second means is provided with a scanner section downstream from the printer section in the conveying direction in order to detect the image density of the image-formed recording paper sent from the printer section, and the image from the scanner section is provided. It is characterized in that a means for detecting the amount of developer consumed by adding the density value after the replenishment of the developer based on the density detection signal is provided.

The third means is provided with a scanner section downstream from the printer section in the carrying direction in order to detect the image density of the recording sheet on which the image has been formed and sent from the printer section. It is characterized by further comprising means for adding a density value based on the density detection signal to determine the cleaning time for the printer section.

[0008]

According to the above-mentioned first means, the scanner section detects the image density of the white background portion of the recording paper on which the image has been formed, which is the background contamination detected portion, and this detection signal is used as the background contamination degree signal. For example, by increasing or decreasing the developer supply amount in the printer unit or by increasing or decreasing the transfer current in the image transfer unit,
Adjust the image density so that background stains do not occur.

According to the second means, the image density of the recording paper on which the image has been formed is detected by the scanner section, and the image density value from the time after the developer is replenished to that time is detected based on the image density detection signal. Is added, the consumption amount of the developer is detected by the added value, and the developer consumption state and the developer end are determined.

According to the third means, since the amount of scattered developer and the added value of image density (consumed amount of developer) are close to each other in proportion, the image of the recording paper on which the image has been formed by the scanner unit is formed. By detecting the density and adding the image density value based on this image density signal, the developer adhesion state in each part of the printer part is estimated, so that the cleaning timing for each part is determined.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a laser printer having a printer unit and a scanner unit according to an embodiment of the present invention. The recording process of an electrophotographic printer device is known, and the printer In the section, the recording paper 3 fed from the paper feed cassette C in the direction of the registration roller pair 2 by the rotation of the paper feed roller 1 is conveyed to the drum-shaped photoconductor 4 at a timing by the registration roller pair 2. . The photoconductor 4 is driven to rotate counterclockwise, and at that time,
The surface is charged by the charging charger 5, and the laser beam from the laser optical system 6 is irradiated to form an electrostatic latent image on the surface.

When the latent image passes through the developing section 7, it is visualized by toner under the action of the developing roller 7a, and this visible image is transferred onto the recording paper 3 conveyed to the photoconductor 4 by the transfer charger 8. The transferred visible image on the recording paper 3 is fixed by a fixing device 9 having a fixing roller pair 9a.

On the other hand, after the transfer of the visible image, the cleaning device 12 removes the residual toner from the photoconductor 4, and the charge eliminating lamp P removes the electric charge. The toner removed from the photoconductor 4 is stored in the toner recovery tank 13 and recovered.

The recording paper 3 discharged from the fixing device 9 is guided to a pair of double-sided conveyance rollers 18 by a rotatable double-sided entrance guide 17. The recording paper 3 is conveyed to the reversing roller pair 19 rotating clockwise by the double-sided conveying roller pair 18 and passes through the reversing sensor 20. After a lapse of a predetermined time after the recording paper 3 passes the reversing sensor 20, the reversing roller pair 19 changes its rotation direction counterclockwise, and the recording paper 3 is conveyed in two directions by the rotatable reversing guide 17 '. It

The recording paper 3 again fed to the registration roller pair 2 is conveyed to the photosensitive member 4 by the registration roller pair 2 at a timing, and the toner is fixed on the recording paper 3 through the same procedure as above. To be done. At this time, the opposite side of the case where the sheet is fed from the sheet feeding roller 1 is in contact with the photoconductor 4, so that double-sided recording is performed on the recording sheet 3. After passing through the fixing device 9, the double-sided recording paper 3 is guided by the double-sided entrance guide 17, discharged to the paper discharge unit 11, and stored.

C is provided downstream of the printer section in the recording paper feeding direction.
A scanner unit 26 including a reading head 25, which is a reading unit for reading image information including a CD (charge coupled device), is installed. The original document conveyed to the reading head 25 is sent out from the paper feed cassette C to the same conveyance path 27 as the recording paper by the rotation of the paper feed roller 1.

In the figure, 14 is a controller for outputting various control signals, 15 is a printer control section for controlling each section of the laser printer having the above construction, and 16 is a registration sensor.

FIG. 2 is a block diagram showing an example of a control system of the laser printer of FIG. 1. Reference numeral 14 is the above-mentioned controller which is connected to an external device 30 and sends image information to the printer device, and 31 is a printer. A CPU in the form of a microcomputer for controlling the apparatus, which is connected to a ROM 32 corresponding to each processing means to execute processing described later and has a working RAM and the like. A main motor drive circuit 33 drives a main motor 34 that conveys the recording paper 3 and drives the fixing device 9 and the developing unit 7.

Reference numeral 39 is a polygon motor drive circuit for driving the polygon motor 40 of the laser optical system 6, and has a FG signal detection circuit for detecting the number of revolutions of the polygon motor 40. Reference numeral 35 is a paper feed clutch drive circuit of a paper feed clutch 36 that drives a paper feed roller that feeds the recording paper 3, 37 is a registration clutch drive circuit of a registration clutch 38 that drives the registration roller pair 2, and 42 is from the controller 14. Image signal W
A laser drive circuit for driving the laser device 41 by an image signal VIDEO generated from DATA, 44 is a main scanning synchronization signal LSYNC from the synchronization detection signal DETP obtained by the synchronization detector 43 according to the rotation of the polygon motor 40, and a main scanning Write valid area signal LGATE, sub-scanning write valid area signal F
An optical write signal control circuit that obtains GATE and sends it to the controller 14.

Further, the laser device 41 includes a laser drive circuit 42.
A semiconductor laser unit that outputs a laser beam in response to the driving, and a light receiving element (not shown) provided for adjusting the light amount thereof.

The CPU 31 and the controller 14 are connected by a bidirectional serial interface consisting of a reception data signal PERXD, a transmission data signal PETXD, a reception ready signal PEDTR, and a transmission ready signal PECTS, and the state of the printer device judged by the CPU 31 is sent to the controller 14. Or the controller 14 sends a command to control the printer device.

In the above structure, the CPU 31 controls the controller 14 that the printer is ready for recording operation.
Let us know. The controller 14 confirms that the recording operation is possible and sends a recording operation start command to the CPU 31.
Upon receiving the recording operation start signal, the CPU 31 turns on the polygon motor drive signal PMST to rotate the polygon motor 40 to immediately start the recording operation. The polygon motor 40 outputs an FG pulse having a frequency corresponding to its rotation speed, and this pulse is detected by the FG signal detection circuit and sent to the polygon motor drive circuit 39 so that it has the same frequency as the polygon motor reference clock PMCK. , The polygon motor speed is controlled. At the same time, the main motor drive signal MMST is turned on to rotate the main motor 34.

The controller 14 receives the recording density information input according to the switch operation of the external device or the operator depending on the image content, regardless of the recording operation, and the CPU 31
Send a recording density specification command to. In response to this, the CPU 31 sends a rotation speed control signal PMCON to the polygon motor drive circuit 39. The rotation speed control signal PMCON is a signal for determining the polygon motor reference clock PMCK and is either the reference clock itself or a signal for selecting one of a plurality of clocks provided in the polygon motor drive circuit 39 as the reference clock. Is.

The polygon motor drive circuit 39 can stabilize the rotation of the polygon motor 40 by controlling the current to the polygon motor 40 so that the cycle of the FG pulse becomes a constant level. Therefore, the CPU 31 can switch the rotation speed of the polygon motor 40 according to the specified recording density by switching the rotation speed control signal PMCON after receiving the recording density specifying command.

Further, the polygon motor drive circuit 39 turns on the polygon motor lock signal PMLK when the polygon motor 40 reaches the steady rotation speed corresponding to the recording density, and C
Send to PU31. When the recording operation is started, the CPU 31 turns on the paper feed clutch drive signal FDCL, drives the paper feed roller 1, and causes the recording paper 3 stored in the cassette C.
Is conveyed to the position of the registration roller pair 2. And
After confirming that the polygon motor lock signal PMLK is turned on, the sub-scanning writing effective area signal FGATE is sent to the controller 14. The controller 14 is FGAT
The image signal WDATA is transmitted after a predetermined time in synchronization with the turning on of E. The CPU 31 sends FGATE, turns on the registration clutch drive signal RGCL after a predetermined time, conveys the recording paper 3 toward the recording position of the photoconductor 4, and forms an image at the predetermined position of the recording paper.

The CPU 31 adjusts the amount of laser light when the FGATE signal is off. The light amount signal fed back from the light receiving element of the laser device 41 is compared with a predetermined level by a comparator in the laser drive circuit 42, and binarized L
It is input to the CPU 31 as a DCT signal. The CPU 31 changes the laser drive signal by using digital-analog conversion, holds the laser light amount when the laser light amount reaches a predetermined value and the LDCT signal changes, and adjusts the laser light amount. Further, by irradiating the mirror on the rotating polygon motor 40 with the laser light, the synchronization detector 43 detects a synchronization signal of a constant cycle according to the rotation of the polygon motor 40.

The optical write signal control circuit 44 outputs the sync detection signal D
ETP is input to generate an image writing clock WCLK synchronized with the DETP signal. At the same time, the WCLK signal is counted, and when the predetermined count is reached, the main scanning synchronization signal LSYNC and the main scanning writing effective area signal LGATE are generated. Further, the sub-scanning writing effective area internal signal F from the CPU 31
SYNC is input and a sub-scanning write effective area signal FGATE is generated in synchronization with the LSYNC signal. When writing an image in which the LGATE signal and the FGATE signal are on, the image signal WDATA from the controller 14 is set to WC.
It is captured in synchronization with the LK signal, converted into a VIDEO signal for driving the laser device 41, and transmitted to the laser drive circuit 42.

The scanner unit 26 reads an original from the reading head 25, sends data to the controller 14 via the CPU 31, and performs data processing and storage. Transfer control circuit 47
Shows the current of the transfer charger 8 by the signal of CPU31.
Turn on / off or up / down. Development control device 48
Turns on / off or up / down the voltage of the developing bias circuit 52 by a signal from the CPU 31, and turns on / off or up / down the rotation speed of the developing roller 7a by a signal from the CPU 31. The counter unit 45 counts the density (gradation) of the recording paper read by the reading head 25 in page units. The non-volatile memory 46 accumulates the density of each page counted by the counter unit 45 when the writing of the image of each page is completed. The display device 50 informs a user or a service person of the state of the printer device by characters, sounds, pictures, lights, or the like.

The operation of automatically adjusting the image density in this embodiment will be described with reference to the flowchart of FIG. The recording paper 3 is printed through the transfer charger 8 of the printer section.
After the image formation, when passing through the scanner unit 26, the read head 25 reads the density in the outer portion (white background portion) of the image area which is the background stain detection portion at the rear end of the recording paper 3.
(S3-1), the density (gradation) is converted into an electric signal as the amount of background stain (S3-2).

The electric signal is sent to the CPU 31 and compared with a reference value indicating the density at the time when scumming starts (S3-3),
If it is larger than the reference value (YES in S3-3), it is determined that the background stain has occurred, and a control signal is output to the transfer control device 47 or the development control device 48 in the printer section, and the bias voltage of the development bias circuit 52 or the development The operation of the printer unit is suppressed so that the rotation speed of the roller 7a or the transfer current of the transfer charger 8 is reduced to reduce the toner supply amount or the transfer rate (S3-4).

On the other hand, if it is smaller than the reference value (NO in S3-3),
It is determined that there is no background stain, and the printer unit is driven with a constant bias voltage, developing roller rotation speed, and transfer current.
(S3-5).

FIG. 4 is a flowchart relating to the detection and display of the amount of toner used in this embodiment. When printing is started (S4-1), the recording paper 3 that has undergone the printing operation passes through the reading head 25. At this time, the image density is read by the reading head 25 (S4-2), and this value is put into the counter unit 45 and sequentially added (S4-3).

When printing is completed (Y in S4-4
S), the count value in the counter unit 45 is read by the CPU 31, and the total toner usage amount is calculated based on the preset toner usage amount per count value,
The amount of toner used for image formation is additionally stored in the non-volatile memory 46 (S4-5). At this time, the CPU 31 causes C
The LEAR signal is made true, and the counter value is cleared thereby (S4-6).

The toner usage amount data accumulated in the non-volatile memory 46 is sent to the CPU 31, and the display device 50 displays the usage amount (S4-7). When the toner is replenished (YES in S4-8), the non-volatile memory 46 is cleared.
(S4-9).

FIG. 5 is a flow chart relating to toner end detection and display in this embodiment, and step (S5-
1) to (S5-6) are the same as the above steps (S4-1) to (S4-6), but in the flow of FIG. 5, the toner usage accumulated in the nonvolatile memory 46 by the CPU 31 is used. The amount data is compared with a predetermined toner end value, and if the toner end value is reached (S5-7), the display device 5
A toner end display is displayed at 0 (S5-8). When toner is supplied (YES in S5-9), the toner end display is erased and the non-volatile memory 46 is cleared (S5-10).

FIG. 6 shows the detection of the cleaning time in this embodiment.
It is a flow chart concerning display, from step (S6-1) to
Up to (S6-6), the flow is almost the same as the above steps (S4-1) to (S4-4), but in the flow of FIG. 6, the integrated value of the density value and the toner scattering rate are substantially proportional. Since there is a relationship, the total toner scattering rate is calculated by the count value by setting the toner scattering rate per count value in step (S6-5), and is additionally stored in the non-volatile memory 46.

The data value of the toner scattering rate stored in the non-volatile memory 46 is sent to the CPU 31, and the amount of toner adhered to the wire of the transfer charger 8 at which the transfer failure in the printer section starts or the charge removal at which the charge removal failure starts. When it is determined that the toner scattering amount is larger than the scattering amount at which the defect starts (YES at S6-7), the display device 50 displays "charger cleaning required" or "static elimination". Display "Lamp cleaning required" (S6-8).

[0039]

As described above, according to the first means of the present invention, since the degree of background stain can be detected from the recording paper on which the image has been formed by the scanner section, the image density can be adjusted so as not to cause background stain. According to the second means, the image density can be detected from the recording paper on which the image has been formed by the scanner unit. Therefore, the consumption amount of the developer can be detected by adding the density value. According to the third means, the scattering amount of the developer can be detected by adding the density value. Therefore, the cleaning time of each part of the printer can be determined, and the scanner part can be used as various detecting means with a simple configuration. Therefore, it is possible to provide the image forming apparatus capable of maintaining the printer function in a good state.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a laser printer that is an embodiment of an image forming apparatus of the present invention.

FIG. 2 is a block diagram showing an example of a control system of a laser printer.

FIG. 3 is a flowchart of automatic adjustment of image density.

FIG. 4 is a flowchart for detecting and displaying the amount of toner used.

FIG. 5 is a flowchart of toner end detection and display.

FIG. 6 is a flowchart of detection and display of cleaning time.

[Explanation of symbols]

4 ... Photoreceptor, 5 ... Charging charger, 7 ... Developing unit,
7a ... Developing roller, 8 ... transfer charger, 14 ... controller, 25 ... reading head, 26 ... scanner section,
27 ... Transport path, 31 ... CPU, 47 ... Transfer control device,
48 ... Development control device, 52 ... Development bias circuit.

Claims (3)

[Claims] 1. An image forming apparatus, comprising: a printer section for forming an image on a recording sheet; and a scanner section for reading an image of a document and replacing it with image data, wherein the recording sheet and the document are conveyed on the same conveyance path. The scanner unit is provided downstream of the printer unit in the transport direction in order to make it possible to read the portion of the recording sheet on which the image has been formed that has been sent out from the printer unit, and the scanner unit of the background contamination detected unit from the scanner unit can be read. An image forming apparatus comprising means for adjusting an image density based on a detection signal. 2. An image forming apparatus, comprising: a printer section for forming an image on a recording sheet; and a scanner section for reading an image of a document and replacing it with image data, wherein the recording sheet and the document are conveyed on the same conveyance path. In order to detect the image density on the recording paper on which an image has been formed and which has been sent from the printer unit, the scanner unit is provided downstream of the printer unit in the transport direction, and the developer is detected based on the image density detection signal from the scanner unit. An image forming apparatus comprising means for detecting a developer consumption amount by adding density values after replenishment. 3. An image forming apparatus, comprising: a printer section for forming an image on a recording sheet; and a scanner section for reading an image of a document and replacing it with image data, wherein the recording sheet and the document are conveyed on the same conveyance path. In order to detect the image density on the recording sheet on which the image has been formed and sent from the printer unit, the scanner unit is provided downstream of the printer unit in the transport direction, and the density value is determined based on the image density detection signal from the scanner unit. The image forming apparatus is provided with a unit for adding the value to determine the cleaning time for the printer unit.