JP2005115064A - Color image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color image forming apparatus which can prevent a leak current and detect the value of a current applied to a transfer member accurately. <P>SOLUTION: The color image forming apparatus has a plurality of image forming units each of which forms a latent image onto an image carrier by using a latent image forming means, develops the latent image into a toner image with developer by using a developing means, and transferring the toner image onto an image receiving member by using a primary transfer means. The color image forming apparatus forms a color image by sequentially transferring, one on another, the toner images formed on the image receiving members. The image forming apparatus is provided with: a voltage control means which applies constant voltage control to the primary transfer means of at least one of the image forming units; an output current detection means for detecting an output current value during the constant voltage control by the voltage control means; and a high voltage control means for determining output voltage to be applied to the transfer means from a constant voltage value based on the constant voltage control means and the result of the calculation of an input obtained from the output current detection means. The voltage is also simultaneously applied to the primary transfer means of the image forming unit adjacent to the image forming unit to which voltage is applied by the constant voltage control means and whose current is being detected by the current detection means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus using an electrophotographic process, and in particular, has a plurality of image forming units including an image carrier, a charging unit, and a developing unit, and further forms a multicolor image using an intermediate transfer member. The present invention relates to a multicolor image forming apparatus.

  Conventionally, in a multicolor image forming apparatus using an intermediate transfer member, due to endurance fluctuations in the resistance value of the primary transfer means for transferring the toner image from the photosensitive member as the intermediate transfer member or the image carrier to the intermediate transfer member and environmental fluctuations. An ATVC control method (Active Transfer Voltage Control) is employed in order to prevent transferability deterioration and to apply an appropriate primary transfer bias (see, for example, Patent Document 1).

The ATVC control method is a method in which the primary transfer portion is set to a constant current with a preset value for the non-image portion on the photosensitive member at the time of start-up of the apparatus at the start of the day or before rotation before image formation. Then, a change in resistance of the primary transfer means is detected based on a change in the generated voltage value at this time (hereinafter referred to as ATVC control 1), and constant voltage control (hereinafter referred to as ATVC control) is performed as a result of calculating the previous generated voltage value during image formation. 2).
JP 2002-123385 A

  However, the constant current control value performed in the ATVC control 1 is very weak, such as several μA, and the leakage current between the high-voltage power supply circuits corresponding to each primary transfer means in the high-voltage power supply substrate and between the holding members of the primary transfer means. If this occurs, the ATVC control 1 is not accurately performed, and the ATVC control 2 that performs constant voltage control based on the result of the arithmetic processing based on the result AVTC1 is not normally performed. There was sex.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a color image forming apparatus that can prevent a leakage current and accurately detect a current value applied to a transfer member.

  (1) According to the present invention, a latent image is formed on an image carrier by a latent image forming unit, the latent image is developed as a toner using a developer by a developing unit, and the toner image is received by a primary transfer unit. In a color image forming apparatus which has a plurality of image forming units to be transferred onto a member and forms a color image by sequentially transferring multiple toner images formed on the image receiving member, the plurality of image forming units. Among them, voltage control means for performing constant voltage control on the primary transfer means of at least one image forming unit, output current detection means for detecting an output current value during constant voltage control by the voltage control means, and the constant voltage control means And a high voltage control means for determining an output voltage to the transfer means from a calculation result of an input from the output current detection means, and the constant voltage control means A color image forming apparatus that simultaneously applies a voltage to a primary transfer unit of an image forming unit adjacent to an image forming unit that is detecting current by the current detecting unit prevents leakage current. In addition, it is possible to provide a color image forming apparatus capable of accurately detecting a current value applied to the transfer member.

  (2) The voltage applied to the primary transfer unit of the image forming unit whose current is detected by the current detection unit is set to the same voltage value as the voltage applied to the primary transfer unit of the adjacent image forming unit. According to the color image forming apparatus described in (1), which is characterized, it is possible to provide a color image forming apparatus capable of preventing leakage current and accurately detecting a current value applied to a transfer member.

  (3) Furthermore, the color image forming apparatus according to (1) or (2), wherein the current detection of the image forming units located at both ends is performed at the same time, thereby preventing leakage current and supplying to the transfer member. A color image forming apparatus capable of detecting an applied current value with high accuracy can be provided.

  As described above, according to the present invention, a latent image is formed on an image carrier by a latent image forming unit, the latent image is developed as a toner using a developer by a developing unit, and the toner image is formed by a primary transfer unit. In a color image forming apparatus that has a plurality of image forming units to be transferred onto an image receiving member and sequentially multiplex-transfers toner images formed on the image receiving member to form a color image, the plurality of images Among the forming units, a voltage control unit that performs constant voltage control on a primary transfer unit of at least one image forming unit, an output current detection unit that detects an output current value during constant voltage control by the voltage control unit, and the constant voltage A constant voltage value based on the control means, and a high voltage control means for determining an output voltage to the transfer means from a calculation result of an input from the output current detection means, and the constant voltage control A color image forming apparatus is characterized in that a voltage is applied by a stage and a voltage is simultaneously applied to a primary transfer unit of an image forming unit adjacent to an image forming unit that is performing current detection by the current detection unit. It is possible to provide a color image forming apparatus capable of preventing an electric current and accurately detecting an applied current value to a transfer member.

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

  Embodiments of the present invention will be described below. FIG. 2 is a configuration diagram of the color image forming apparatus of this embodiment.

  The laser printer 401 includes a deck 402 for storing recording paper. The deck paper presence sensor 403 detects the presence or absence of the recording paper P in the deck 402, the pickup roller 404 that feeds the recording paper P from the deck 401, and the pickup roller 404. A deck paper feed roller 405 that conveys the fed recording paper P and a retard roller 406 that is paired with the deck paper feeding roller 405 and prevents double feeding of the recording paper P are provided.

  A registration roller pair 407 that synchronously conveys the recording paper P and a pre-registration sensor 408 that detects the conveyance state of the recording paper P to the registration roller pair are disposed downstream of the deck paper feed roller 405. An intermediate transfer belt (hereinafter referred to as ITB) 409, which is an intermediate transfer body, is disposed downstream of the registration roller pair 407. On the ITB 409, four colors (yellow Y, magenta M, cyan C, The images formed by the image forming unit including the process cartridges 410Y, 410M, 410C, 410B for the black B) and the scanner units 420Y, 420M, 420C, 420B are sequentially superimposed by the primary transfer rollers 430Y, 430M, 430C, 430B. As a result, a color image is formed and further transferred and conveyed onto the recording paper P by the secondary transfer roller 431.

  Downstream of the secondary transfer roller 431, in order to thermally fix the toner image transferred onto the recording paper P, a pair of the fixing roller 433 and the pressure roller 434 having a heater 432 for heating therein, and recording from the fixing roller. A pair of fixing and discharging rollers 435 for conveying the paper P, a fixing and discharging sensor 436 for detecting a conveying state from the fixing unit, a pair of conveying rollers 437 for conveying a recording sheet from the fixing unit, A paper discharge sensor 438 for detecting the conveyance state of the recording paper P and a paper discharge roller pair 439 for discharging the recording paper P are provided.

  Each scanner unit 420 emits a laser unit 421 that emits a laser beam modulated based on each image signal sent from a video controller 440 described later, and the laser beam from each laser unit 421 is sent to each photosensitive drum 105. It comprises a polygon mirror 422 for scanning upward, a scanner motor 423, and an imaging lens group 424.

  Each process cartridge 410 includes a photosensitive drum 105, a charging roller 103 and a developing roller 102, and a toner storage container 411 necessary for a known electrophotographic process, and is configured to be detachable from the laser printer 401. ing.

  Further, when the video controller receives image data sent from an external device 441 such as a personal computer, the video controller expands the image data into bitmap data and generates an image signal for image formation.

  Reference numeral 110 denotes a DC controller which is a control unit of the laser printer, and an MPU (microcontroller) having a RAM 207a, a ROM 207b, a timer 207c, a digital input / output port 207d, a D / A port 207e, and an A / D port 207f (not shown). Computer) 207, various input / output control circuits (not shown), and the like.

  Further, reference numeral 106 denotes a high voltage power supply unit, which is not shown, a charging high voltage power supply or development superimposed high voltage power supply corresponding to each process cartridge, and a primary transfer high voltage power supply or primary transfer current not shown corresponding to each primary transfer roller. It comprises a detection circuit and a secondary transfer high voltage power source (not shown).

  Reference numeral 450 denotes a main motor, which rotates the ITB 409, the photosensitive drum 105, and each conveyance system roller via a drive transmission system (not shown).

  Next, a control block diagram of the present embodiment will be described with reference to FIG.

  The high voltage power supply unit in the figure is provided with primary transfer high voltage power supplies (500B to 500Y) which are constant voltage power supplies, and voltage control signals (VcntB to VcntY) from the D / A port (207e) of the CPU (207). ) Is supplied to each primary transfer roller (430B to 430Y). Also, primary transfer current detection circuits (501B to 501Y) are connected to the primary transfer high-voltage power supplies (500B to 500Y), respectively, and current values output from the primary transfer high-voltage power supplies (500B to 500Y) are detected. The voltage corresponding to the detected current is sent to the A / D port (207f) of the CPU (207) as a current detection signal (IsnsB to IsnsY). The CPU 207 monitors the current detection signal during constant current control, and controls the voltage control signal so that the current applied to the primary transfer roller 430 becomes a target value.

  Next, the constant current control timing of this embodiment will be described based on the timing chart of FIG.

  First, ATVC1 of the B primary transfer roller is performed. At this time, the C primary transfer high voltage adjacent to the B primary transfer roller also outputs the same voltage as the B primary transfer high voltage value. After ATVC1 of the B primary transfer roller is completed, ATVC1 of the C primary transfer roller is performed. At this time, the B primary transfer high voltage and the M primary transfer high voltage adjacent to the C primary transfer roller are also output with the same voltage as the C primary transfer high voltage value. . Subsequently, after ATVC1 of the C primary transfer roller is completed, ATVC1 of the M primary transfer roller is performed. At this time, the C primary transfer high voltage and the Y primary transfer high voltage adjacent to the M primary transfer roller are set to the same voltage as the C primary transfer high voltage value. Output. Finally, after ATVC1 of the M primary transfer roller is completed, ATVC1 of the Y primary transfer roller is performed, and at this time, the M primary transfer high voltage adjacent to the Y primary transfer roller is also output with the same voltage as the Y primary transfer high pressure value. Then, ATVC1 of the Y primary transfer roller ends, and ATVC1 of all the primary transfer rollers ends.

  Next, the ATVC1 control of this embodiment will be described based on the flowchart of FIG.

  First, ATVC1 of the B primary transfer roller is performed (S101). Until the ATVC1 of the B primary transfer roller is completed (S103), the C primary transfer high voltage value is output at the same voltage as the B primary transfer high voltage value (S102). After ATVC1 of the B primary transfer roller ends, B and the C primary transfer high pressure value are turned off (S104).

  Next, ATVC1 of the C primary transfer roller is performed (S105). Until the ATVC1 of the C primary transfer roller is completed (S107), the B and M primary transfer high voltage values are output at the same voltage as the C primary transfer high voltage value (S106). After ATVC1 of the C primary transfer roller ends, the primary transfer high pressure values of B, C, and M are turned off (S108).

  Subsequently, ATVC1 of the M1st transfer roller is performed (S109). Until the ATVC1 of the M primary transfer roller is completed (S111), the C and Y primary transfer high voltage values are output to the same voltage as the M primary transfer high voltage value (S110). After completion of ATVC1 of the M primary transfer roller, the primary transfer high pressure values of C, M, and Y are turned off (S112).

  Finally, ATVC1 of the Y primary transfer roller is performed (S113). Until the ATVC1 of the Y primary transfer roller is completed (S115), the M primary transfer high voltage value is output to the same voltage as the Y primary transfer high voltage value (S114). After the end of ATVC1 of the Y primary transfer roller, the primary transfer high pressure values of M and Y are turned off (S116).

  As described above, according to this embodiment, a latent image is formed on the image carrier by the latent image forming unit, the latent image is developed as a toner by using the developer by the developing unit, and the toner image is transferred to the primary transfer unit. In a color image forming apparatus for forming a color image by sequentially transferring a plurality of toner images formed on the image-receiving member by a plurality of image forming units that are transferred onto the image-receiving member by the plurality of image forming units. Among the image forming units, a voltage control unit that performs constant voltage control on a primary transfer unit of at least one image forming unit, an output current detection unit that detects an output current value during constant voltage control by the voltage control unit, and the constant unit. A constant voltage value based on the voltage control means, and a high voltage control means for determining an output voltage to the transfer means from a calculation result of the input from the output current detection means. By means of a color image forming apparatus, the voltage is applied by the means, and the same voltage is simultaneously applied to the primary transfer means of the image forming unit adjacent to the image forming unit that is performing current detection by the current detecting means, It is possible to provide a color image forming apparatus capable of preventing leakage current and accurately detecting an applied current value to a transfer member.

  The second embodiment of the present invention will be described below based on the timing chart of FIG.

  A difference from the first embodiment is that ATVC1 of B primary transfer and Y primary transfer is performed simultaneously. At this time, the C primary transfer high voltage value outputs the same voltage as the B primary transfer high voltage value performing ATVC1, and the M primary transfer high voltage value outputs the same voltage as the Y primary transfer high voltage value performing ATVC1, Leakage current is prevented.

  Next, the ATVC1 control of the second embodiment will be described based on the flowchart of FIG.

  First, ATVC1 of the B and Y primary transfer rollers is performed (S201), and until the ATVC1 of the B and Y primary transfer rollers is completed (S203), the C primary transfer high voltage value is the same voltage as the B primary transfer high voltage value and the M primary transfer. As the high voltage value, the same voltage as the Y primary transfer high voltage value is outputted (S202). After ATVC1 of the B and Y primary transfer rollers is completed, the B, C, M, and Y primary transfer high pressure values are turned off (S204).

  Subsequent ATVC1 of the C primary transfer roller is the same as in the first embodiment.

  As described above, according to this embodiment, a latent image is formed on the image carrier by the latent image forming unit, the latent image is developed as a toner by using the developer by the developing unit, and the toner image is transferred to the primary transfer unit. In a color image forming apparatus for forming a color image by sequentially transferring a plurality of toner images formed on the image-receiving member by a plurality of image forming units that are transferred onto the image-receiving member by the plurality of image forming units. Among the image forming units, a voltage control unit that performs constant voltage control on a primary transfer unit of at least one image forming unit, an output current detection unit that detects an output current value during constant voltage control by the voltage control unit, and the constant unit. A constant voltage value based on the voltage control means, and a high voltage control means for determining an output voltage to the transfer means from a calculation result of the input from the output current detection means. The same voltage is applied simultaneously to the primary transfer unit of the image forming unit adjacent to the image forming unit that is applied with the voltage, and the current detecting unit detects the current. A color image forming apparatus capable of preventing leakage current, accurately detecting an applied current value to a transfer member, and further shortening the time of ATVC1 by a color image forming apparatus characterized by performing current detection simultaneously. Can be provided.

Timing chart of Example 1 1 is a configuration diagram of a color image forming apparatus according to a first embodiment. Control block diagram of embodiment 1 Flow chart of the first embodiment Timing chart of Example 2 Flow chart of embodiment 2

Explanation of symbols

401 Color image forming apparatus (laser printer)
430 Primary transfer roller 409 Intermediate transfer belt 106 High voltage power supply 207 CPU
500 Primary transfer high voltage power source 501 Primary transfer current detection circuit

Claims (3)

  An image forming unit that forms a latent image on the image carrier by a latent image forming unit, develops the latent image as a toner using a developer by a developing unit, and transfers the toner image onto an image receiving member by a primary transfer unit. In a color image forming apparatus for forming a color image by sequentially transferring a plurality of toner images formed on the image receiving member, and at least one of the plurality of image forming units. A voltage control means for controlling the primary transfer means at a constant voltage, an output current detection means for detecting an output current value during constant voltage control by the voltage control means, a constant voltage value based on the constant voltage control means, and the output A high voltage control means for determining an output voltage to the transfer means from a calculation result of an input from the current detection means, a voltage is applied by the constant voltage control means, and the current detection Color image forming apparatus and applying a voltage simultaneously to the primary transfer unit of the image forming unit adjacent to the image forming unit is performing a current detected by the means.   The voltage applied to the primary transfer unit of the image forming unit whose current is detected by the current detection unit is set to the same voltage value as the voltage applied to the primary transfer unit of the adjacent image forming unit. The color image forming apparatus according to 1.   The color image forming apparatus according to claim 1 or 2, wherein the current detection of the image forming units located at both ends is simultaneously performed.

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