JP2006119173A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which can calculate a reference bias Vo close to a normal state even when a paper sheet reaches or nearly reaches a transfer nip before ATVC is completed. <P>SOLUTION: In an image forming apparatus equipped with an image carrying body and a transfer means to transfer a toner image formed on the surface of the image carrying body onto a transfer material at a transferring position, the apparatus is equipped with a bias output means to output a transfer bias, a transfer bias control means to vary the bias, and a constant current control means to control the transfer means to a predetermined current by varying the transfer bias when a transfer material does not pass the transfer position. If the transfer material reaches the transfer position or an optionally set position in the upstream side of the transfer position in the conveying direction of the transfer material during the constant current control process, the constant current control means employs the transfer bias currently outputted as a reference bias Vo. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is an image forming process means unit of an appropriate principle and method such as electrophotography, electrostatic recording, and magnetic recording. The present invention relates to an image forming apparatus such as a printer, a copier, a recording machine, and a facsimile machine that outputs an image formed product by forming and supporting the image by a direct method and thermally fixing the image as a permanently fixed image on a recording medium.

  In an image forming apparatus such as a laser printer, when the transfer nip portion is in a non-image area, the transfer roller is set to a predetermined current value or a constant current value so as to obtain a stable transfer property in any environment. Perform control or constant voltage control, read the voltage value or current value generated in the transfer roller, adjust the resistance value of the variable resistor so that the total resistance becomes the predetermined resistance value, and fix this resistance value Some perform image formation (see Patent Document 1).

  In recent years, various methods have been used to shorten the first print time. As one of the methods, paper feeding is performed without waiting for the end of the transfer control (hereinafter referred to as “ATVC”) as described above. Some start paper transport. However, even in that case, paper feeding is performed at the timing when the paper reaches the transfer nip after ATVC ends.

JP-A-9-106203

  If paper is fed before the end of ATVC, depending on the configuration of the paper feed unit and the type of paper, the paper may protrude from the paper feed unit, and the time from the start of paper feed until the paper reaches the transfer nip can be shortened. There was sex. Therefore, the paper may reach the transfer nip before the end of ATVC.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus capable of calculating a reference bias Vo close to normal even when the paper reaches or is likely to reach the transfer nip after ATVC is finished after feeding. There is.

  In order to achieve the above object, an invention according to claim 1 is an image forming apparatus comprising: an image carrier; and a transfer unit that transfers a toner image formed on the surface of the image carrier to a transfer material at a transfer site. Bias output means for outputting the transfer bias, transfer bias control means for varying the bias, and when the transfer material does not pass through the transfer portion, the transfer bias is varied, and the transfer means is controlled to a predetermined current value. And a control means for performing the above.

  According to a second aspect of the present invention, in the first aspect of the invention, the constant current control means sets the transfer material arbitrarily at the upstream side in the transfer material conveyance direction from the transfer portion or the transfer portion during the constant current control. When the point is reached, the transfer bias output at that time is set as the reference bias Vo.

  According to a third aspect of the present invention, in the first aspect of the present invention, the constant current control means is configured such that the transfer material is arbitrarily set upstream of the transfer portion or the transfer portion in the transfer material conveyance direction during the constant current control. If the preset time has not elapsed, an error is notified to the controller that controls the image forming apparatus, and if not, it is output at that time. The transfer bias is a reference bias Vo.

  According to the present invention, even when the paper reaches or is likely to reach the transfer nip after the feeding and before the ATVC is completed, the reference bias Vo close to the normal time can be calculated.

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

<Embodiment 1>
FIG. 1 is a schematic configuration diagram of an image forming apparatus according to the present embodiment.

  In FIG. 1, reference numeral 104 denotes a photosensitive drum composed of an organic photosensitive member or an amorphous silicon photosensitive member, which is driven to rotate clockwise with a predetermined peripheral speed (process speed). The peripheral surface of the rotating photosensitive drum 104 is uniformly charged to a predetermined polarity and potential by the charging roller 105. Then, corresponding to the time-series electric digital pixel signal of the target image information output from the laser optical box 108 and input from an image signal generator (not shown) such as an image reading device or a computer to the charged surface. The modulated (on / off-converted) laser beam is changed by the laser beam reflecting mirror 109 and irradiated to perform scanning exposure, and an electrostatic latent image corresponding to the image information is formed.

  The electrostatic latent image thus formed corresponding to the target image is developed by the developing device 106.

  Next, one sheet of recording material is fed from the sheet feeding cassette 103 to the photosensitive drum 104 by the sheet feeding roller 102, so that a mirror image toner image on the photosensitive drum 104 side is formed on the recording material. It is formed. The transfer roller 107 transfers a toner image from the photosensitive drum 104 to the recording material by supplying a charge having a polarity opposite to that of the toner from the back surface of the recording material. The recording material that has received the transfer of the toner image in this manner is separated from the photosensitive drum 104 and sent to the fixing device 110 to receive thermal fixing of the toner image.

  The recording material that has undergone thermal fixing is conveyed by the FU roller 111 and the FD roller 112 and is discharged to the discharge tray 113.

  FIG. 2 is a block diagram of the control system.

The image forming control unit 300 is controlled by a main control unit including a microprocessor that controls the entire image forming apparatus, a ROM that stores a control program, a RAM that stores data, and a gate element. Functionally,
Communication control means 301 for performing communication with the controller 200
A transfer bias control unit 302 that determines a transfer bias based on information from the transfer current detection unit 401 and outputs the result to the transfer bias output unit 402.
Paper transport control means 303 that controls paper transport based on information from the paper transport sensor 500
Etc.

  FIG. 3 is a flowchart showing the control of the image forming apparatus in the present embodiment.

  First, when a print instruction is input from the controller, the transfer bias control means proceeds to step 1, starts constant transfer current control, and proceeds to step 2.

  In step 2, the way is set to the paper feed timing.

  In step 4, it is checked whether or not the transfer constant current control has been completed. If it has been completed, the process proceeds to step 6, and the average value of the transfer bias output during the constant current control is ended as the reference voltage Vo. If the transfer constant current control is not completed, the process proceeds to step 5.

  In step 5, it is checked whether the fed paper has reached the TOP sensor. If it has not reached, the process returns to step 4; if it has reached, the process proceeds to step 7 where the currently output transfer bias is used as a reference. End as bias Vo.

  By the control as described above, the reference bias Vo close to the normal time can be calculated even when the paper reaches or is likely to reach the transfer nip after the feeding and before the ATVC is completed.

<Embodiment 2>
In the first embodiment, when the paper reaches the TOP sensor during the constant transfer current, the transfer bias that is currently output unconditionally is set to the reference voltage Vo.

  In this embodiment, the transfer bias currently output is set to the reference voltage Vo only when an arbitrarily set time has elapsed since the start of the transfer constant current control.

  FIG. 4 is a flowchart showing the control of the image forming apparatus in the present embodiment.

  First, when a print instruction is input from the controller, the transfer bias control means proceeds to step 1, starts constant transfer current control, and proceeds to step 2.

  In step 2, the way is set to the paper feed timing.

  In step 4, it is determined whether an arbitrarily set time has elapsed since the start of the transfer constant current control. Here, the arbitrary time is the time from the start of constant current control to the output of a bias close to the target transfer bias. If the time has elapsed, the process proceeds to step 7, and if not, the process proceeds to step 5.

  In step 5, it is checked whether the fed paper has reached the TOP sensor. If it has not reached, the process returns to step 4; .

  In step 7, it is checked whether or not the transfer constant current control is completed. If completed, the process proceeds to step 9 and the transfer bias average value output during the constant current control is set as the reference voltage Vo. If the transfer constant current control is not completed, the process proceeds to step 8.

  In step 8, it is checked whether the fed paper has reached the TOP sensor. If not, the process returns to step 7, and if it has reached, the process proceeds to step 7 where the currently output transfer bias is used as a reference. End as bias Vo.

  By the control as described above, the reference bias Vo close to the normal time can be calculated even when the paper reaches or is likely to reach the transfer nip after the feeding and before the ATVC is completed.

1 is a cross-sectional view illustrating an example of an image forming apparatus according to the present invention. It is a block diagram of a control system in the present invention. It is a flowchart showing the control in Embodiment 1 of this invention. It is a flowchart showing the control in Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Image forming apparatus 102 Paper feed roller 103 Paper feed cassette 104 Photosensitive drum 105 Charging roller 106 Developing device 107 Transfer roller 108 Laser optical box 109 Laser light reflecting mirror 110 Thermal fixing device 111 FU roller 112 FD roller 113 Paper discharge tray 114 FU tray s1 TOP sensor s2 Paper discharge sensor

Claims (3)

In an image forming apparatus having an image carrier and a transfer means for transferring a toner image formed on the surface of the image carrier to a transfer material at a transfer site,
Bias output means for outputting the transfer bias, transfer bias control means for varying the bias, and when the transfer material does not pass through the transfer portion, the transfer bias is varied, and the transfer means is controlled to a predetermined current value. And an image forming apparatus.   When the transfer material reaches an arbitrary set point on the upstream side of the transfer portion or the transfer portion in the transfer material conveyance direction during the constant current control, the constant current control means is configured to determine the transfer bias output at that time. 2. The image forming apparatus according to claim 1, wherein the reference bias is set to Vo.   The constant current control means is arbitrarily set from the start of the constant current when the transfer material reaches an arbitrary set point upstream of the transfer part or the transfer part in the transfer material transport direction during the constant current control. 2. If the time has not elapsed, an error is notified to a controller that controls the image forming apparatus, and if not, the transfer bias output at that time is set as a reference bias Vo. The image forming apparatus described.

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