JP3728308B2 - Image forming apparatus - Google Patents

Description

  The present invention belongs to a technical field of an image forming apparatus used in a laser beam printer, a laser beam FAX, or the like.

  FIG. 13 is an explanatory cross-sectional view showing a configuration of a conventional laser beam printer.

  In FIG. 1, 1 is a laser beam printer, 2 is a photosensitive drum, 3 is a scanner unit, 4 is a mirror, 5 is a charger, 6 is a developing machine, 7 is a transfer roller, 8 is a drum cleaner, 9 is a paper cassette, 10 Is a paper feed roller, 13 is a fixing device, 14 is a paper discharge sensor, 15 is a paper discharge tray, 16 is a top sensor, 40 is a printer controller, and 25 is a CPU.

  In this configuration, when receiving a print signal from the printer controller 40, the CPU 25 drives the paper feed roller 10 to feed paper from the paper cassette 9. In parallel with this, a laser (not shown) and a scanner motor (not shown) in the scanner unit 3 operate. In synchronization with the fed paper approaching the photosensitive drum 2, a video signal is transmitted from the printer controller 40, a laser beam is scanned on the photosensitive drum 2, and a latent image corresponding to the video signal is displayed on the photosensitive drum. 2 is formed. Thereafter, toner is adhered by the developing device 6 to be visualized, transferred onto the paper being conveyed by the transfer roller 7, fixed by the fixing device 13, and output as a hard copy.

  Conventionally, in this configuration and operation, the CPU 25 detects the leading and trailing edges of the paper with the top sensor 16 and the paper discharge sensor 14 and the door open with a door sensor (not shown). When the door is opened, paper transport is delayed due to poor paper feed, or the paper is skewed and transport of the paper stops, the transport roller is stopped and jammed, and the status is sent to the print controller 40. are doing. The same applies when paper is present in the machine at power-on.

The above operation has been configured so as to be possible in the past.
JP 05-080651 A

  However, in the conventional example, there are problems that the photosensitive drum is deteriorated and the image of the print sample is thinned by repeating printing with the cartridge integrated with the photosensitive drum.

  The present invention has been made in order to solve the above-described conventional problems, and can cope with changes in the state of the photosensitive drum and the state of the print sample image to prevent the quality of the image formed and recorded on the recording medium from being deteriorated. An object of the present invention is to provide an image forming apparatus using an integrated cartridge.

  The image forming apparatus of the present invention achieves the above object by the following configuration.

(1) An image forming apparatus that mounts a cartridge containing a photosensitive member and a nonvolatile memory and forms an image on a recording medium.
Cleaning execution means for cleaning the photoconductor by applying a voltage different from that during printing to the photoconductor at a predetermined timing including at the end of printing, after closing the door, and after jamming; Read / write means for reading the number of cleanings of the photosensitive member from the nonvolatile memory or writing to the nonvolatile memory, and control means for switching and controlling image forming conditions corresponding to the read from the nonvolatile memory. An image forming apparatus.
(2) The image forming apparatus according to (1), wherein the control unit switches a developing voltage in response to a read from the nonvolatile memory.
(3) The image forming apparatus according to (1), wherein the control unit switches a laser light amount corresponding to a read from the nonvolatile memory.
(4) The image forming apparatus according to any one of (1) to (3), wherein the nonvolatile memory is an EEPROM.

  According to the present invention, it is possible to prevent deterioration of the photosensitive drum caused by repeating printing with the same cartridge. Further, since the life of the photosensitive drum is extended, it is possible to prevent the image quality in the print sample from being deteriorated. Needless to say, as long as the same cartridge is used, the image will not be disturbed for a long time.

In order to extend the life of a photosensitive drum by repeating printing and to keep the quality of a print sample constant, an image forming apparatus according to the present invention is equipped with a photosensitive drum integrated cartridge incorporating an EEPROM. By memorizing the number of prints, when a certain number of prints is reached,
1. Increase the driving torque of the motor.
2. Switch the image to point symmetry.

Further, by storing the number of times the photosensitive drum is cleaned as a means other than the above, when a certain number of cleanings is reached,
3. Switch the development voltage.
4). Switch the laser light quantity.

  Details of the above embodiment will be described with reference to examples.

  An embodiment of the present invention is an image forming apparatus in which a photosensitive drum integrated cartridge incorporating a photosensitive drum and a nonvolatile memory is mounted, and an image is formed and recorded on a recording medium. Read / write means for reading from the memory or writing to the non-volatile memory is provided, and the apparatus main body is controlled as a basic configuration in response to the read from the non-volatile memory.

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

(First embodiment)
A first embodiment of the present invention will be described with reference to FIG. 1, FIG. 2, FIG. 3, and FIG. FIG. 14 shows a conventional example.

  FIG. 1 is a flowchart of the first embodiment, FIG. 2 is an explanatory diagram of changes in the driving torque of the cartridge and the driving torque of the motor due to an increase in the number of prints in the first embodiment, and FIG. It is a principal part block diagram of the Example of. FIG. 14 is an explanatory diagram showing the relationship between the driving torque of the cartridge and the driving torque of the motor as the number of prints in the conventional example increases.

  The driving torque of the cartridge increases as the remaining amount of toner decreases. Therefore, as shown in FIG. 1, when the number of cartridges used is small, optimal motor rotation is realized by normal driving torque with low motor driving torque. When the number increases to a certain number, the driving torque is increased. That is, the motor driving torque is determined according to the life of the cartridge, and when the number of prints is small, the motor driving torque is lowered.

  A means for reducing the driving torque of the motor will be described with reference to FIG.

  In FIG. 3, 31 is a CPU, 32 is a sawtooth wave generation circuit, 33 is an operational amplifier, 34 is a transistor, and 35 is a motor. By increasing the D / A output of the CPU 31, the output duty of the operational amplifier 33 is reduced. Furthermore, the driving torque of the motor 35 decreases as the ON time of the transistor 34 becomes shorter.

(Second embodiment)
A second embodiment of the present invention will be described with reference to FIGS.

  FIG. 4 is a flowchart of the second embodiment, and FIG. 5 is an explanatory diagram of changes in deterioration on the left and right sides of the photosensitive drum as the number of prints increases. FIG. 6 is a block diagram of the second embodiment, and FIG. 7 is an explanatory diagram of a point-symmetric image.

  Deterioration of the photosensitive drum occurs as the number of printed sheets increases, and when viewed from the left and right sides of the drum, FIG. 5 shows that the deterioration of the left side is severe. Therefore, as shown in FIG. 5, when a certain number of prints is reached, a point-symmetric image is displayed, that is, the screen of the host computer or word processor is used with an image forming apparatus such as a laser beam printer or laser beam FAX. In this case, the upper left side of the screen is printed from the lower right side on the photosensitive drum, so that deterioration of one side of the photosensitive drum can be prevented.

  A means for outputting a point-symmetric image will be described with reference to FIG.

  In FIG. 6, the printer controller 60 includes 61 CPUs, 62 RAMs, 63 ROMs, 64 I / Os, and 65 I / Os.

  As a result of communicating with the printer, the engine reads the number of prints from the EEPROM of the cartridge. If the result is a fixed number (for example, 1000), the controller unit 60 receives the status from the engine. Thus, the controller unit 60 writes data from the final address of the DRAM 8 in the RAM 62 in order to print the image symmetrically. Next, when all the images have been developed, the images are sent from ADR0 of the DRAM 1 as usual. That is, as shown in FIG. 7, the data at the lower right end of the page is read first, and the data at the upper left end of the page is read last. Therefore, the image becomes point symmetric compared to the normal case. It is also possible to change the point symmetry of an image twice (for example, 1000 sheets and 2000 sheets).

(Third embodiment)
In a normal electrophotographic process, the high voltage applied from the LBP main body to the photosensitive drum in the cartridge includes a primary AC charging output, a primary DC charging output, a developing AC output, a developing DC output, and a transfer charging voltage.

  FIG. 8 is an explanatory diagram of the high voltage related part. During printing, primary charging is applied by the charging roller 81 to smooth the potential on the photosensitive drum. The development output is applied by the developing unit 83 to embody the latent image formed by the laser beam 82. When a toner image is formed in the toner container portion 84, a positive transfer charging voltage is output, and the toner image is transferred onto the transport paper by the transfer roller 85.

  Also, at the end of printing, or after closing the door or after jamming, a negative transfer charging voltage and a primary AC charging voltage are applied to clean the cartridge, unlike during printing.

  Application of only the primary AC charging voltage generally tends to lower the sensitivity of the photosensitive drum and make the print sample thinner. For this reason, the drum is deteriorated when one sheet of printing is repeated rather than continuous multiple printing. Therefore, the photosensitive drum in which a large amount of toner remains is deteriorated, and the print sample may be thinned. In this embodiment, in order to prevent such a phenomenon, the number of times the cartridge is cleaned is stored in the EEPROM built in the cartridge. The output is set high to correct the thin density.

  FIG. 9 is a flowchart of the third embodiment, and FIG. 10 is a block diagram showing the main configuration of the present embodiment.

  In FIG. 9, in the standby state (S21), door open / close (S22) or print signal reception (S23) is monitored. When the print signal is received, the total number of cleanings is loaded from the EEPROM in the CRG (S24), and it is determined whether it is 2000 or more (S25) or 1000 or more (S26). If it is 2000 or more, the development DC output is increased by 10% (S32). If it is 1000 or more, the development DC output is increased by 5% (S33), and printing is executed (S27). The means for changing the development DC output will be described later. Thereafter, the printing operation is maintained and the end of printing is monitored (S28).

  When printing is completed, the photosensitive drum is cleaned (S29), the total number of cleanings already loaded is incremented by 1, and written to the EEPROM (S30), and the process returns to standby.

  When the door open / close is detected in standby (S22), the total cleaning count is loaded from the EEPROM in the CRG (S31), the photosensitive drum is cleaned (S29), and the total cleaning count already loaded is incremented by one. Write to the EEPROM (S30) and return to standby.

  The means for changing the development DC output will be described with reference to FIG.

  In FIG. 10, 100 is a CPU, 101 is a low-pass filter, 102 is a DC component cutting capacitor, 106 is a transformer, 103 is a comparator, 104 is a reference voltage generating circuit, and 105 is a developing sleeve.

  In FIG. 10, the CPU 100 outputs a pulse having a predetermined frequency, passes through the low-pass filter 101 and the capacitor 102, becomes a sine wave immediately before the transformer 106, and is boosted by the transformer 106 to generate a development AC output.

  Further, the CPU 100 outputs a development DC output control signal from the D / A port and inputs it to the comparator. A development DC output is generated from the reference voltage generation circuit based on the development DC output control signal, and is added to the development AC output to obtain a normal development output.

  The development DC output control signal is generally used to control the density of the print sample according to the user's preference. At the same time, the development DC output control signal is used as a correction signal when the deterioration of the photosensitive drum described above is detected. To do.

  The above configuration / control contributes to stabilization of the quality of the print sample.

(Fourth embodiment)
A fourth embodiment of the present invention will be described with reference to FIGS. In the previous embodiment, when the deterioration of the drum was detected, the development DC output was changed. In this embodiment, instead, the amount of laser light is changed.

  In the flowchart shown in FIG. 11, the same steps as those in the flowchart of FIG. 9 of the third embodiment are denoted by the same step symbols, and only different portions from the previous embodiment will be described. In S25 and S26, it is monitored whether it is 2000 or more and 1000 or more. If it is 2000 or more, the laser light quantity is increased by 20% (S42), and if it is 1000 or more, the laser light quantity is increased by 10% (S43).

  FIG. 12 is a block diagram showing a specific configuration of the laser light amount UP.

  Reference numeral 120 denotes a CPU, 121 denotes a laser driving circuit, 122 denotes a laser, 123 denotes a light amount measuring pin photodiode, 124 denotes an amplifier, and 125 denotes a comparator.

  The CPU 120 determines the reference of the laser light quantity at the D / A port 126. The value and the measurement result of the light quantity measurement pin photodiode 123 are compared by the comparator 125, and the result is reflected in the laser drive circuit 121. Therefore, by changing the D / A port 126, the light amount can be increased by 10% and 20%.

  Therefore, a stable print sample can be realized by changing the laser light amount in accordance with the deterioration of the drum due to repeated cleaning.

It is a flowchart of a 1st Example. It is drive torque explanatory drawing of a 1st Example. It is a principal part block diagram of a 1st Example. It is a flowchart of a 2nd Example. It is explanatory drawing of the change of deterioration of the photosensitive drum of a 2nd Example. It is a principal part block diagram of a 2nd Example. It is explanatory drawing of the point-symmetric image of a 2nd Example. It is explanatory drawing of the high voltage related part of a 3rd Example. It is a flowchart of a 3rd Example. It is a principal part block diagram of a 3rd Example. It is a flowchart of the 4th example. It is a principal part block diagram of a 4th Example. It is sectional explanatory drawing of the conventional laser beam printer. It is drive torque explanatory drawing of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser beam printer 2 Photosensitive drum 3 Scanner unit 5 Charging device 6 Developer 7 Transfer roller 8 Drum cleaner

Claims (4)

An image forming apparatus that mounts a cartridge containing a photosensitive member and a nonvolatile memory and forms and records an image on a recording medium,
Cleaning execution means for cleaning the photoconductor by applying a voltage different from that during printing to the photoconductor at a predetermined timing including at the end of printing, after closing the door, and after jamming;
Read / write means for reading from the nonvolatile memory or writing to the nonvolatile memory the number of cleanings of the photosensitive member,
An image forming apparatus comprising control means for switching and controlling image forming conditions corresponding to reading from the nonvolatile memory. It said control means, the image forming apparatus according to claim 1 which before SL in response to the read from the non-volatile memory and switches the developing voltage.   The image forming apparatus according to claim 1, wherein the control unit switches a laser light amount corresponding to a read from the nonvolatile memory.   The image forming apparatus according to claim 1, wherein the nonvolatile memory is an EEPROM.

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