JP2008009035A - Process cartridge, image forming apparatus with the same, bias voltage measurement device for process cartridge, and development bias condition measuring method using the device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process cartridge in which the need for image stabilization control for image formation is eliminated by storing development bias conditions in advance, and also to provide an image forming apparatus having the process cartridge, a bias voltage measuring device for the process cartridge, and a development bias condition measuring method using it. <P>SOLUTION: The process cartridge includes: an image carrier; a charging means for uniformly charging the image carrier; a developing means for rendering an electrostatic latent image, formed on the image carrier, visible; and a storage means. The process cartridge is held by the image forming apparatus so as to be freely detached. In the process cartridge, the development bias conditions corresponding to the image forming apparatus are measured in advance and stored in the storage means. When the process cartridge is mounted in the image forming apparatus, a development bias voltage corresponding to the process cartridge is applied based upon the development bias conditions stored in the storage means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a process cartridge that is detachably held in an image forming apparatus main body, an image forming apparatus including the process cartridge, and a developing bias condition measuring method for the process cartridge.

  Many image forming apparatuses using an electrophotographic system use a process cartridge in order to facilitate maintenance. The process cartridge referred to here has a structure in which an image carrier consisting of a photosensitive drum or the like, a charging unit, a developing unit, a cleaning unit, etc. are integrated as a unit, and is detachably held in the image forming apparatus main body. It is. Since the process cartridge generally has a shorter life than the main body of the image forming apparatus, it is necessary to replace it with a new one after it has been used up.

  Normally, an image forming apparatus has a control function of changing image forming conditions so that an appropriate image can be always formed when a process cartridge is replaced or in response to a change in the internal environment (temperature, humidity, etc.). In particular, in a color image forming apparatus, a pattern image is formed with toner on the surface of a photosensitive drum or on a transfer belt for the purpose of correcting a shift in image forming position for each color, So-called image stabilization control is performed in which the toner adhesion amount of the pattern image is detected using a photoelectric sensor or the like, and various image forming conditions are determined based on the detection results. Based on the result of detecting the toner adhesion amount of these pattern images, the image stabilization control is performed here to adjust the development bias voltage, the exposure amount on the surface of the photosensitive drum, etc., and always obtain an appropriate image density. That's it.

  The image stabilization control is performed by detecting the pattern image formed on the surface of the photosensitive drum of the process cartridge, and the pattern transferred after the pattern image formed on the surface of the photosensitive drum is transferred to the transfer belt. Some are performed by detecting an image.

  In order to perform such image stabilization control, it is known that a process cartridge includes a storage unit that stores optimum image forming process conditions. When the process cartridge is mounted on the image forming apparatus, the image forming apparatus A technique for performing image formation by calling an optimum image forming process condition is disclosed (for example, refer to Patent Document 1). Japanese Patent Application Laid-Open No. 2005-228561 describes a technique relating to a process cartridge including a storage unit that stores optimum image forming process conditions corresponding to each model for a plurality of types of image forming apparatuses.

However, in an image forming apparatus that performs image stabilization control as described in Patent Document 1, image formation is not performed while image stabilization control is being performed. There's a problem. Further, since toner is consumed for image stabilization control, the amount of toner to be used for a desired output image is reduced.
JP 2002-251120 A

  The present invention solves the above-described problems, and stores a developing bias condition for obtaining an appropriate image in a process cartridge in advance, thereby simplifying the configuration without performing image stabilization control during image formation. An object of the present invention is to provide a process cartridge with high image forming productivity, an image forming apparatus including the process cartridge, a bias voltage measuring apparatus for the process cartridge, and a developing bias condition measuring method using the process cartridge.

  The object of the present invention can be achieved by the following constitution.

  1. An image carrier, a charging unit that uniformly charges the image carrier, a developing unit that visualizes an electrostatic latent image formed on the image carrier, and a storage unit. In a process cartridge that is detachably held in the apparatus, a developing bias condition corresponding to the image forming apparatus is measured in advance and stored in the storage unit, and when the process cartridge is attached to the image forming apparatus, A process cartridge configured to apply a developing bias voltage corresponding to the process cartridge based on a developing bias condition stored in the storage unit.

  2. 2. The process cartridge according to 1, wherein the developing bias condition is a leak generating bias voltage.

  3. An image forming apparatus, wherein the process cartridge according to 1 or 2 is detachably held.

  4. A bias voltage measuring apparatus for a process cartridge, wherein the process cartridge according to item 1 or 2 is detachably held and configured to measure a leak occurrence bias voltage of the process cartridge.

  5. A developing bias condition measuring method, comprising: measuring a leak generating bias voltage of the process cartridge using the bias voltage measuring apparatus according to 5.4.

  According to the present invention, the development bias voltage setting value can be adjusted and optimized according to the variation in the development bias condition when manufacturing the process cartridge, and the process cartridge is mounted on the image forming apparatus to form an image. In this case, since it is not necessary to perform image stabilization control, image formation with high productivity can be performed.

  FIG. 1 is an overall configuration diagram of an image forming apparatus according to an embodiment of the present invention in which a process cartridge is mounted and driven.

  An image forming apparatus A shown in FIG. 1 irradiates a drum-shaped photosensitive drum 7 provided in a process cartridge with a laser light image based on image information from an optical system 1 to form a latent image on the photosensitive drum 7. Then, the latent image is developed to form a toner image. In synchronization with the formation of the toner image, the recording medium 2 is transported from the paper feed cassette 3a by the transport means 3 including a pickup roller 3b, a pair of feed rollers 3c, a pair of transport rollers 3d, a pair of registration rollers 3e, and the like. The toner image formed on the photosensitive drum 7 is transferred onto a recording medium 2 by applying a voltage to a transfer roller 4 serving as a transfer unit, and the recording medium 2 is guided by a guide plate 3f and conveyed to a fixing unit 5. Is done. The fixing unit 5 includes a driving roller 5a and a fixing roller 5c incorporating a heater 5b, and fixes the transferred toner image by applying heat and pressure while passing through the recording medium 2. The recording medium 2 is transported by a pair of discharge rollers 3g and 3h which are transport means 3, and is discharged to the discharge unit 6 through a reverse transport path. The image forming apparatus A can also be manually fed by a manual feed tray 3i and a roller 3j.

  On the other hand, the process cartridge B shown in FIG. 1 includes, in addition to the photoconductor 7, a charging unit 8 for charging the photoconductor, a developing unit 10 for developing a latent image formed on the photoconductor, and remaining on the photoconductor after transfer. A process unit such as a cleaning unit 11 for removing the toner to be processed, and a storage element EP for storing a process condition unique to the process cartridge B.

  The developing unit 10 forms a toner image on the photosensitive drum 7. That is, toner is sent out from the toner storage portion 10a by the feeding member 10b, the developing roller 10d is rotated, and a toner layer is formed on the surface of the developing roller 10d by the developing blade 10e. Then, the toner layer on the surface of the developing roller 10d is transferred to the photosensitive drum 7 to form a toner image.

  In the cleaning means 11, after the toner image on the photosensitive drum 7 is transferred onto the recording medium 2 by the transfer roller 4, the toner remaining on the photosensitive drum 7 is scraped off by the cleaning blade 11a. The toner is collected in the waste toner reservoir 11c by the squeeze roller 11b.

  Each member such as the photosensitive drum 7 forms a developing unit by welding a toner container 12a for storing toner and a developing frame 12b for holding a developing member such as a developing roller 10d, and this is configured as a cleaning frame. A process cartridge mounting means provided in the apparatus main body 13 is formed as a process cartridge by being housed in a process cartridge frame formed by coupling a cleaning unit having the photosensitive drum 7 and the cleaning means 11 attached to the body 12c. It is detachably mounted via a mounting guide member that is not.

  When the process cartridge B is attached to the image forming apparatus A, the process cartridge side coupling means and the main body side coupling means (not shown) are coupled, and the photosensitive drum 7 and the like can be rotated by being driven by the apparatus main body 13. .

  FIG. 2 is a schematic diagram of a bias voltage measuring apparatus for measuring a leak occurrence bias voltage which is a developing bias condition of the process cartridge according to the embodiment of the present invention.

  In FIG. 2, a bias voltage measuring device (hereinafter also referred to as a measuring jig) JP is installed in a manufacturing process for manufacturing the process cartridge B, and includes a measuring jig main body JP1 and a jig drum JP2. The measuring jig JP has a configuration in which a process cartridge semi-finished product B1 from which the photosensitive drum is removed from the process cartridge B can be mounted. A DC power supply JP3, an AC power supply JP4 that can apply a variable voltage, and a measuring instrument JP5 that measures a voltage applied to the AC power supply JP4 are electrically connected to the jig drum JP2.

  When measuring the leakage bias voltage of the process cartridge, the process cartridge semi-finished product B1 is attached to the measuring jig JP, and the DC power supply JP3 and the AC power supply between the jig drum JP2 and the developing roller 10d of the process cartridge semi-finished product B1 are connected. DC and AC bias voltages are applied by the power supply JP4, and the voltage applied to the AC power supply JP4 is increased stepwise to measure the voltage VppH at which a leak occurs (hereinafter, this voltage is referred to as a leak occurrence bias voltage). Measure with the instrument JP5. The voltage information measured by the measuring instrument JP5 is sent to the control device JS installed in the manufacturing process of the process cartridge B, and after being electrically processed by the control device JS, the process cartridge is passed through the measuring jig JP. It is written in the storage element EP of the semi-finished product B1.

  Note that as the element used for the memory element EP, any of a semiconductor memory element, a nonvolatile magnetic memory, and an optical memory may be used, but a semiconductor memory element is more preferable.

  In addition, the jig drum JP2 may be a photosensitive drum as a dielectric, and may be a metal cylinder having conductivity such as aluminum, but may be formed of a flat plate having dielectricity or conductivity.

  FIG. 3 is a block diagram of a control system when measuring the leakage occurrence bias voltage of the process cartridge according to the present invention in the manufacturing process.

  In FIG. 3, JS is a control device installed in the manufacturing process of the process cartridge B, and has a built-in memory JS1. The memory JS1 processes the measured leakage occurrence bias voltage VppH of the semifinished product B1 of the process cartridge. A program for writing to the storage element EP of the cartridge semi-finished product B1 is provided. In this program, data that can select the optimum value of the AC bias voltage Vpp is inputted by comparing the operation time and the environmental conditions of the process cartridge B with the measured leakage occurrence bias voltage VppH of the semifinished process cartridge B1. The optimum value is selected by the control device JS and written into the storage element EP of the process cartridge semi-finished product B1 via the measuring jig JP.

  FIG. 4 is a block diagram of a control system when the process cartridge according to the present invention is mounted on the image forming apparatus.

  In FIG. 4, when the process cartridge B is attached to the image forming apparatus A, information on the leak occurrence bias voltage VppH written in the storage element EP of the process cartridge B is stored in the control unit SE built in the image forming apparatus A. Sent. The control unit SE has a built-in memory SE1 having a program for determining the output value of the high-voltage power supply HV based on the value of the leak generation bias voltage VppH. Based on this, the output value of the high-voltage power supply HV is determined.

  FIG. 5 is a graph for explaining a leak generation bias voltage setting value of the process cartridge according to the embodiment of the present invention.

  In FIG. 5, the horizontal axis represents the distance Ds between the photosensitive drum and the developing roller, and the vertical axis represents the AC bias voltage Vpp. The inclined straight line a indicates the limit of the leak generation region, and the straight line b indicates the limit of the concentration unevenness generation region. As can be seen from FIG. 5, when the AC bias voltage Vpp is too high, leakage occurs, and when it is too low, the density becomes uneven.

Assuming that the minimum value Ds1 and the maximum value Ds2 of the distance Ds between the photosensitive drum and the developing roller are Ds2, the value of the AC bias voltage at the point where the minimum value Ds1 of Ds intersects the straight line a becomes the leak generation bias voltage VppH, and Ds The value of the AC bias voltage at the point where the maximum value Ds2 intersects the straight line b is the density unevenness occurrence bias voltage VppL. Here, the difference between the leak generation bias voltage VppH and the density unevenness generation bias voltage VppL is referred to as a constant for determining the AC bias voltage. When expressed as VppOW, the initial setting value VppS of the AC bias voltage is:
VppS = VppH− (VppOW / 2)
It is represented by

  FIG. 6 is a flowchart for explaining the procedure for measuring the leak occurrence bias voltage of the process cartridge according to the embodiment of the present invention.

  In the manufacturing process in which the leakage occurrence bias voltage VppH of the process cartridge B is measured and written to the storage element EP, as shown in FIG. 6, the process cartridge semi-finished product B1 is first set on the measuring jig JP (step S1).

  Next, the DC power supply JP3 and the AC power supply JP4 are turned on to apply a bias voltage (step S2).

  It is confirmed whether or not a leak has occurred due to the voltage Vpp applied by the AC power supply JP4 (step S3). When no leak has occurred (No at step S3), the process proceeds to step S4, and when a leak has occurred (step S3). (Yes) proceeds to step S6.

  When no leak has occurred, the process proceeds to step S4, and in step S4, the voltage Vpp applied by the AC power source JP4 is increased by one step (here, one step is a pitch of 40 to 50 V).

  Next, it is confirmed whether or not a leak has occurred again (step S5). If no leak has occurred (No in step S5), the process returns to step S4. If a leak has occurred (Yes in step S5), the process returns to step S6. move on.

  When a leak occurs, the process proceeds to step S6, and the measured leak occurrence bias voltage is written into the storage element EP of the process cartridge semi-finished product B1 by the writing device (step S6).

  Finally, the process cartridge semi-finished product B1 that has been measured is removed from the measurement jig JP (step S7). The process cartridge semi-finished product B1 becomes a process cartridge (finished product) B by incorporating a photosensitive drum in a next process (not shown).

  In the embodiment of the present invention, the development bias condition is the leak generation bias voltage in the AC bias voltage. However, the DC bias voltage or the duty ratio (a numerical value representing developability, with respect to the time of one cycle of the AC bias voltage). It represents the ratio of voltage application time).

  According to the present invention, it is not necessary to perform image stabilization control, image formation productivity is increased, toner consumption is reduced, and an increase in the number of extra image formations can be suppressed.

1 is an overall configuration diagram of an image forming apparatus that is mounted and driven by a process cartridge according to an embodiment of the present invention. 2 is a bias voltage measuring device for measuring a leak occurrence bias voltage which is a developing bias condition of a process cartridge according to an embodiment of the present invention. It is a block diagram of a control system when measuring a leak occurrence bias voltage of a process cartridge according to the present invention in a manufacturing process. FIG. 2 is a block diagram of a control system when the process cartridge according to the present invention is mounted on the image forming apparatus. It is a figure for demonstrating the leak generation bias voltage setting value of the process cartridge which concerns on this invention. It is a flowchart for demonstrating the procedure which measures the leak generation bias voltage of the process cartridge which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical system 2 Recording medium 3 Conveying means 4 Transfer roller 5 Fixing means 6 Ejection part 7 Photosensitive drum (image carrier)
DESCRIPTION OF SYMBOLS 8 Charging means 9 Opening part 10 Developing means 11 Cleaning means 13 Apparatus main body 14 Opening / closing cover A Image forming apparatus B Process cartridge B1 Process cartridge semi-finished product Ds Distance between photosensitive drum and developing roller EP Storage element JP Measuring jig (bias voltage) measuring device)
JP1 Measuring jig body JP2 Jig drum JP3 DC power supply JP4 AC power supply Vpp AC bias voltage VpppH Leakage generation bias voltage VppS AC bias voltage setting value VppOW Constant for determining AC bias voltage

Claims (5)

An image carrier, a charging unit that uniformly charges the image carrier, a developing unit that visualizes an electrostatic latent image formed on the image carrier, and a storage unit. In the process cartridge that is detachably held in the apparatus,
Development bias conditions corresponding to the image forming apparatus are measured in advance and stored in the storage unit;
When the process cartridge is mounted on the image forming apparatus, a developing bias voltage corresponding to the process cartridge is applied based on a developing bias condition stored in the storage unit. Process cartridge. The process cartridge according to claim 1, wherein the development bias condition is a leak generation bias voltage. An image forming apparatus, wherein the process cartridge according to claim 1 is detachably held. 3. A bias voltage measuring device for a process cartridge, wherein the process cartridge according to claim 1 is detachably held, and is configured to measure a leak occurrence bias voltage of the process cartridge. 5. A developing bias condition measuring method, wherein the bias voltage measuring device according to claim 4 is used to measure a leak occurrence bias voltage of the process cartridge.

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