JP2009151104A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prolong the service life of a photosensitive drum, while timely performing the start of falling processing of high voltage output. <P>SOLUTION: In an image forming apparatus, when the bottom end of a recording paper on which an image is formed passes through a transfer means, before the next printing request is received, electrification by an electrifying means is stopped, when the next printing request is received before a discharged paper detecting means detects the bottom end of a conveyed recording paper, the electrification by the electrifying means is restarted, and when the next printing request is not received, falling processing of an image forming means is performed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to an image forming apparatus in which, after an image carrier is charged, exposure, development, and transfer processes are performed to transfer an image onto a recording sheet.

Conventionally, in an image forming apparatus that employs an electrophotographic image forming process, in order to extend the life of a photosensitive drum that is an image carrier, the AC high voltage output time applied to a charging roller that is a charging unit is shortened as much as possible, A countermeasure for reducing the AC high-voltage output has been proposed during the interval between recording sheets being conveyed.
In addition, when the next print reservation is not made within a predetermined time after the transfer, a countermeasure is proposed in which a high voltage output is lowered so that the photosensitive drum is not burdened by the high voltage output as much as possible.

JP 05-307287 A Japanese Patent Laid-Open No. 08-015952

However, once the high voltage output falling processing is entered, at least (falling processing time + starting processing time) is required until the next transfer. Here, the larger the image information, the longer it takes to prepare for the start of printing, and the longer it takes to send a print reservation.
Therefore, a document with larger image information has a higher possibility of receiving a print reservation during the high voltage output lowering process.

For example, when a plurality of originals with large image information are instructed to be printed at a time, all the print reservations for the second and subsequent pages enter the high-voltage output falling process, and the space between all the pages will be ) (Lowering process time + high pressure starting process time). When this happens, productivity becomes worse and the user can wait until all printing is completed.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that can alleviate the deterioration of productivity as much as possible and can also take measures against the life of a photosensitive drum.

The image forming apparatus according to the present invention includes, as image forming means, a charging means for charging the surface of the image carrier, a latent image forming means for irradiating light carrying image information to form a latent image on the image carrier, An apparatus comprising: developing means for developing toner on a latent image on an image carrier; and transfer means for transferring a toner image on the developed image carrier to recording paper. In an image forming apparatus having a paper discharge detecting means for detecting that paper has been discharged from the main body, when the trailing edge of the recording paper on which an image is formed passes through the transfer means before receiving the next print request, When the next print request is received before the discharge means detects the trailing edge of the transported recording paper after the charging means stops charging, the charging means resumes charging. If the image is not received, the image forming means Characterized by comprising a print control means for performing.

According to the present invention having such a configuration, the life of the photosensitive drum can be extended while the start-up process of the high-voltage output can be started at an appropriate timing.

Further, the next print request is not received until the discharge detection unit detects the trailing edge of the conveyed recording paper, and the next print request is received while the print control unit is executing the shutdown process. When the paper discharge detection means detects the trailing edge of the recording paper and receives a print request, it counts the time from the start of the next shutdown process. The print control means may set an extension mode for extending the time to be performed.

Further, when the extension mode is set by the print control means, if the next print request is received before the discharge detection means detects the trailing edge of the conveyed recording paper, the print control means The extended mode may be canceled.

According to the present invention, the life of the photosensitive drum can be extended while the start-up process of the high voltage output of the image forming apparatus can be started at an appropriate timing with a simple configuration.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of a printer as an example of an image forming apparatus including a process cartridge including a developing device of the present invention.

FIG. 1 is a schematic configuration diagram of a laser printer which is an example of an image forming apparatus according to the present invention.
100 hardware configurations control 200 high voltage output configurations.
The CPU 101 controls the scanner control 104 and the laser scanner circuit 106.
Is used to control the laser scanner 203. The CPU 101 controls the high voltage control 105 and uses the high voltage circuit 107 to control the voltage to the charging roller 202 as the charging unit, the voltage control to the developing unit 205 as the developing unit, and the transfer roller 206 as the transfer unit. As a result, a toner image is created on the photosensitive drum 201, which is an image carrier, and is transferred to a recording sheet. Further, the recording paper conveyance state is detected by the sensor detection circuit 108.

Each unit of the high voltage configuration 200 controlled by the hardware configuration 100 will be described.
Reference numeral 201 denotes a photosensitive drum which is an image carrier. Reference numeral 202 denotes a charging roller as charging means for the photosensitive drum 201, which rotates following the rotation of the photosensitive drum 201. The charging roller 202 is applied with a voltage of a charging bias (AC component, DC component) from the high voltage circuit 107, and the peripheral surface of the rotating photosensitive drum 201 is uniformly negatively charged.

The surface of the photosensitive drum uniformly negatively charged by the charging roller 202 is subjected to scanning exposure by the laser beam 204 output from the laser scanner 203 after image modulation corresponding to target image information is performed. The potential of the exposed portion is attenuated, and an electrostatic latent image corresponding to target image information is formed on the surface of the photosensitive drum 201. The electrostatic latent image is developed as a toner image by the toner of the developing device 205.

Then, the toner image is fed and conveyed between the photosensitive drum 201 and a transfer roller 206 as a contact transfer means, and the rotational speed of the photosensitive drum 201 and the top sensor 208 positioned in the conveyance path are The toner images created according to the timing are sequentially transferred onto the recording paper. The transfer roller 206 is in pressure contact with the photosensitive drum 201 with a predetermined pressing force, and rotates in the forward direction with respect to the rotation of the photosensitive drum 201 at substantially the same peripheral speed as the photosensitive drum 201. A transfer bias is applied.

The recording paper that has passed through the transfer portion is sequentially separated from the photosensitive drum 201 and conveyed to the fixing device 209, where the transfer toner image is subjected to fixing processing.
After receiving the fixing process, it is checked whether or not the recording paper is normally discharged by a paper discharge sensor 210 which is a paper discharge detection unit.

300 is a control flow diagram of the present invention.
When printing is started, a high voltage output start-up process is performed and a printing operation is started.
During the printing operation, a charging bias (AC component, DC component) is applied (S301). A charging bias is applied to the position of the photosensitive drum 201 where the trailing edge of the recording paper conveyed and image-formed passes through the nip position of the transfer roller 206 (the portion in contact with the photosensitive drum 201) (S301). ). If the next page has been reserved for printing after the trailing edge of the recording paper has elapsed, the charging bias is continuously applied for the next transfer.

If there is no print reservation, the charging AC component is stopped (S304). at this point,
Negative charges are not placed on the photosensitive drum 201. After charging AC is stopped, the printer waits for a print reservation until the paper discharge sensor 210 in the paper discharge unit detects the rear edge of the recording paper conveyed through the apparatus (S305, S308). When a print reservation is received before detection, if the print reservation extension time is set, the setting is canceled (cleared) (S306), the next page is fed (S307), and the charging AC is reapplied. In step S301, a transfer operation is performed.

If no print reservation is received before the trailing edge is detected, it is checked whether the print reservation extension time is set (S309). If there is a print reservation extension time, it waits for a print reservation until the time elapses (S310, S311). If there is no print reservation extension time, post-rotation processing (high-pressure falling processing) is entered (S312). When the post-rotation is entered, a print reservation acceptance timer is started, and it is checked whether a print reservation comes during the post-rotation (S313).

When the print reservation is received, the number of times of continuous entry in the post-rotation is incremented, and when the continuous number counter is equal to or greater than the predetermined number (S316), the current print reservation waiting time extension and the reservation are received. The time (obtained from the print reservation timer) is compared, and the longer one is set as the print reservation waiting extension time (S317). Thereafter, the print reservation acceptance timer is cleared (S318), and the post-rotation process is awaited (S319).

If there is no print reservation during the post-rotation processing, the print reservation extension waiting time is cleared (S321), the print reservation reception timer is cleared (S322), the continuous number counter is cleared (S323), and the process proceeds to standby. Normally, printing is started upon receipt of a print reservation in the standby state. Therefore, if a print reservation is received during post-rotation, printing starts immediately after shifting to the standby state.

The preferred embodiments of the present invention have been described above, but various modifications and changes other than those mentioned above can be made. For example, the image forming apparatus of the present invention has been described by taking a laser printer as an example, but it may be a copying machine, a facsimile, or a complex machine thereof.

It is a high voltage | pressure structure and hardware block diagram of embodiment which concerns on this invention. It is a high voltage | pressure control flowchart of embodiment which concerns on this invention.

Explanation of symbols

201 Photosensitive drum 202 Charging roller 205 Developer 206 Transfer roller 101 CPU
107 High Voltage Circuit 210 Paper Discharge Sensor

Claims (3)

As an image forming means,
Charging means for charging the surface of the image carrier;
Latent image forming means for irradiating light carrying image information to form a latent image on the image carrier, developing means for developing toner on the latent image on the image carrier, and the developed image carrier A transfer means for transferring the toner image on the recording paper,
In an image forming apparatus having a sheet discharge detecting means for detecting that a recording sheet on which an image is formed is conveyed and discharged from the apparatus main body,
Before the next print request is received, when the trailing edge of the recording paper on which the image is formed passes through the transfer unit, charging by the charging unit is stopped,
By the time when the discharge detection means detects the trailing edge of the conveyed recording paper,
When the next print request is received, charging by the charging unit is resumed. When the next print request is not received, a print control unit is provided for performing a process of lowering the image forming unit. An image forming apparatus. The next print request is not received until the discharge detection means detects the trailing edge of the conveyed recording paper, and the next print request is received while the print control means is executing the shutdown process. Counts the time from when the paper discharge detection means detects the trailing edge of the recording paper to when it receives a print request. The image forming apparatus according to claim 1, wherein the print control unit sets an extension mode for extending a start time. When the extension mode is set by the print control means, when the next print request is received before the discharge detection means detects the trailing edge of the conveyed recording paper, the print control means 3. The image forming apparatus according to claim 2, wherein the set extension mode is canceled.

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