JP2006079010A - Image forming apparatus and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of making a print image uniform even when a process cartridge is replaced. <P>SOLUTION: The process cartridge is provided with a photoreceptor drum and an ID chip 10. A write CPU 7 is connected to an LD driver IC 6 for adjusting light intensity of an LD 5 and the write CPU 7 performs non-contact communication with the ID chip 10. Deviation amount data of the photoreceptor drum is stored in the ID chip 10. The write CPU 7 reads the deviation amount data of the photoreceptor drum 3 by non-contact from the ID chip 10 and calculates LD light intensity suitable for its deviation amount. A signal indicating the LD light intensity is transmitted to the LD driver IC 6 and the LD driver IC 6 adjusts the light intensity of the LD 5. In addition, the write CPU 7 calculates the deviation amount of the photoreceptor drum, based on read values of sensors 1, 2 which read toner patterns of the photoreceptor drum and stores it in the ID chip 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus provided with a process cartridge containing a photosensitive member, and a process cartridge.

Conventionally, a photosensitive drum, a charging roller, a cleaning device, etc. are integrated into a process cartridge that is detachably mounted on the image forming apparatus main body, and a storage device for storing the sensitivity information of the photosensitive drum is provided so that an image can be formed. The sensitivity information read from the storage device is compared with the standard sensitivity information, and the amount of laser light applied to the photosensitive drum is controlled in accordance with the comparison result, so that the sensitivity variation of the photosensitive drum in the process cartridge is controlled. There has been proposed an image forming apparatus that forms an image with an appropriate density (see, for example, Patent Document 1). Further, the detection image formed on the photosensitive drum is detected by the density sensor, and the image forming condition is controlled based on the detected density and the stored sensitivity information, so that the image forming condition is not dependent on the process cartridge. Has been proposed (see, for example, Patent Document 2).
JP 10-31332 A JP-A-10-39723

In the conventional image forming apparatus, a unique eccentricity occurs in each photosensitive drum in the process cartridge, and density unevenness occurs in the printed image every time the process cartridge is replaced. Such a problem has not been considered in the above-mentioned Patent Documents 1 and 2.
Accordingly, it is an object of the present invention to provide an image forming apparatus that solves the above-described problems and can make a printed image uniform even when the process cartridge is replaced.

  An image forming apparatus according to a first aspect of the invention forms an electrostatic latent image by scanning a light beam corresponding to an input image from a light source on a photosensitive drum in a process cartridge that is detachably attached to the main body of the image forming apparatus. In the image forming apparatus formed and developed with toner, the electrostatic latent image is provided with a storage unit provided in the process cartridge for storing the eccentric amount of the photosensitive drum, and the eccentric amount from the storage unit. And adjusting means for adjusting the light quantity of the light source based on the read eccentric amount.

According to a second aspect of the present invention, there is provided an image forming apparatus according to the first aspect, wherein the sensor detects a toner concentration of a toner image formed on the photosensitive drum, and the bias of the photosensitive drum is based on the detected toner concentration. A writing means is provided for obtaining the core amount and writing the eccentric amount in the storage means.
An image forming apparatus according to a third aspect of the present invention is the image forming apparatus according to the first or second aspect, wherein a plurality of the sensors are arranged substantially parallel to the axial direction of the photosensitive drum. Image forming apparatus.

An image forming apparatus according to a fourth aspect of the present invention is the image forming apparatus according to the second or third aspect, wherein the sensor detects a density of a toner pattern formed on the photosensitive drum.
An image forming apparatus according to a fifth aspect of the present invention is the image forming apparatus according to any one of the first to fourth aspects, wherein the storage means is an ID chip.

According to a sixth aspect of the present invention, there is provided a process cartridge including at least a photosensitive drum, wherein a storage means for storing an eccentric amount of the photosensitive drum is provided.
A process cartridge according to a seventh aspect of the present invention is the process cartridge according to the sixth aspect, wherein the storage means is an ID chip.

According to the first and sixth aspects of the present invention, the image forming apparatus reads out the eccentric amount of the photosensitive drum from the storage means provided in the process cartridge, so that the amount of light of the light source is automatically adjusted to adjust the toner image. The density can be adjusted.
According to the second to fourth aspects of the present invention, the current eccentric amount of the photosensitive drum calculated from the density detected by the sensor can be periodically updated, for example, in the storage unit.
According to the fifth and seventh aspects of the invention, by using the ID chip as the storage unit, the image forming apparatus main body side can read data without contact.

  FIG. 11 is a diagram showing the configuration of the process cartridge according to the embodiment of the present invention. The process cartridge 100 has a configuration in which the photosensitive drum 3, the charging roller 17, the developing unit 9, and the cleaning unit 11 are integrally coupled. The process cartridge 100 is detachable from an image forming apparatus main body such as a copying machine or a printer.

  The ID chip 10 includes an IC chip on which information is recorded and an antenna coil, and is a medium that can communicate without contact with the outside. The ID chip 10 is not limited to the position shown in FIG. 11 but is provided at a position where communication with the outside is possible without contact and there is no problem with the relationship with other members.

Next, the operation will be described.
Toner conveyance from the toner cartridge 270 to the developing unit 9 is performed by an air pump (not shown). In addition, an optical sensor (not shown) is incorporated in a conveying nozzle (not shown), and toner near-end detection (not shown) is also performed. The toner conveyed from the toner cartridge 270 to the developing unit 9 is agitated with the developer by two screws (conveying screw (left) 9B and conveying screw (right) 9C) and conveyed to the developing roller 31. The amount of the agent on the roller 31 is regulated by the developing doctor blade 90 and supplied onto the photosensitive drum 3. Further, a T sensor (toner density sensor) 9E is provided on the front side of the developing unit 9, The toner density in the agent is detected and toner density control is performed, and density detection sensors 1 and 2 are disposed in the vicinity of the photosensitive drum 3 on the main body side of the image forming apparatus. The density of a toner pattern to be described later is detected.

  Charging of the photosensitive drum 3 is performed by the charging roller 17. The charging roller 17 rotates in a direction opposite to that of the photosensitive drum 3, and enables uniform charge on the drum surface. On the upper side of the charging roller 17, a charging cleaning row 7 </ b> A is attached in a state of being always in contact with the charging roller 17, and the charging roller 17 is cleaned. Untransferred toner on the photosensitive drum 3 is collected by the cleaning unit 11 by the cleaning blade 11B and the cleaning brush 11A. The cleaning blade 11B is attached in the counter direction with respect to the drum rotation direction, and is always in contact with the drum. The cleaning brush 11A rotates in the direction opposite to the drum, collects untransferred toner together with the blade, and sends it to the waste toner transport coil 11C side. The waste toner is transported from the waste toner transport coil 11C to the waste toner discharge port and collected by a waste toner bottle (not shown).

Next, the image forming process will be described.
In the image forming apparatus having the process cartridge 100, the photosensitive drum 3 is rotationally driven at a predetermined peripheral speed. In the rotation process, the photosensitive drum 3 is uniformly charged at a predetermined positive or negative potential on the peripheral surface thereof by the charging roller 17, and then from an image exposure device (not shown) such as slit exposure or laser beam scanning exposure. Upon receiving image exposure by the laser beam L, electrostatic latent images are sequentially formed on the peripheral surface of the photosensitive drum 3. The formed electrostatic latent image is developed with toner by the developing unit 9, and the developed toner image is synchronized with the rotation of the drum between the photosensitive drum 3 and the transfer device (not shown) from the paper feeding unit. The transfer material is sequentially transferred to the fed transfer material. The transfer material that has received the image transfer is separated from the surface of the photosensitive drum 3 and introduced into an image fixing device (not shown) to be fixed, and printed out as a copy (copy). The surface of the photosensitive drum 3 after the image transfer is cleaned by the transfer unit 11 after the transfer residual toner is removed, and after being further neutralized, it is repeatedly used for image formation.

Next, parts related to the present invention will be described.
The concentration detection sensors 1 and 2 in FIG. 11 are arranged as shown in FIG. 2 when viewed from the side. That is, the image density at both ends of the photosensitive drum 3 is detected. A description will be given of obtaining the eccentricity of the shaft 3A of the photosensitive drum 3 by using these sensors 1 and 2.
The density of the toner pattern written on the photosensitive drum 3 with the light quantity of a normal LD (laser diode) is detected by the sensors 1 and 2, and the eccentricity is calculated from the density difference between the sensors 1 and 2 as shown in FIG. Then, it is recorded in advance on the ID chip 10 in the process cartridge 100 as eccentricity data.

FIG. 1 shows a configuration for adjusting the LD light quantity based on eccentricity data according to an embodiment of the present invention.
In FIG. 1, a write CPU 7 is connected to an LD driver IC 6 that adjusts the light quantity of the LD 5 by a voltage input from an external terminal, and the write CPU 7 can read and write data by communicating with the ID chip 10 in a non-contact manner. Has been made.
The writing CPU 7 reads the eccentric amount data of the photosensitive drum 3 from the ID chip 10 and calculates the LD light amount corresponding to the eccentric amount based on FIG. A signal indicating the LD light amount is sent to the LD driver IC 6, and the LD driver IC 6 adjusts the light amount of the LD 5 as shown in FIG.
By this operation, it is possible to automatically adjust the density according to the amount of eccentricity of the process cartridge 100 in the process cartridge 100.

The process for obtaining the eccentric amount of the photosensitive drum 3 will be described in more detail.
When the value of the reference voltage v supplied to the external terminal is changed, the LD driver 6 in FIG. 1 changes the light quantity of the LD 5 in accordance with the change rate. It is assumed that v = V in the default state.
In order to measure the amount of eccentricity of the photosensitive drum 3, first, a toner pattern 8 is formed on both ends of the photosensitive drum 3 (positions where the sensors 1 and 2 are located) as shown in FIG. At this time, the reference voltage input to the LD driver 6 is v = V.

FIG. 6 shows a case where the photosensitive drum 3 is parallel to the scanning direction of the laser beam L (when there is no eccentricity). In this case, since the length of the laser beam L to both ends of the photosensitive drum 3 is the same, when the drawn toner pattern 8 is read by the density detection sensors 1 and 2, the same is applied to each sensor as shown in FIG. Indicates the concentration.
FIG. 8 shows a case where the photosensitive drum 3 is not parallel to the scanning direction of the laser beam L (when there is eccentricity). In this case, since the length of the laser beam L to both ends of the photosensitive drum 3 is different, the exposure power when the laser beam L reaches the photosensitive drum 3 also changes, and the toner pattern 8 in FIG. When read by the sensors 1 and 2 for detection, different concentrations are shown in each sensor as shown in FIG.

Now, the positions of the density detection sensors 1 and 2 are x1 and x2, and the read toner density is d.
Assuming 1 and d2, a line connecting them (see FIG. 9) indicates the eccentric amount of the photosensitive drum 3. In order to correct the image density variation due to the eccentricity, the reference voltage v input to the LD driver 6 is adjusted. The amount of adjustment is obtained as follows.
As shown in FIG. 9, when the toner density when the photosensitive drum 3 is horizontal with respect to the scanning direction of the laser beam L is D, the photosensitive drum 3 is not horizontal with respect to the scanning direction of the laser beam L. In this case, the fluctuation rates of the toner density read by the density detection sensors 1 and 2 are d1 / D and d2 / D, respectively. In order to make the toner density the same as in the horizontal state, as shown in FIG. 10, a reference voltage having a variation rate that is the reciprocal of the toner concentration variation rate may be input. Accordingly, the reference voltages v1 and v2 at the positions x1 and x2 of the density detection sensors 1 and 2 are (D / d1) V and (D / d2) V, respectively. The straight line connecting these two points is
v = (DV / x1-x2) [(d1-d2) .x + (d2x1-d1x2)] (1)

  When this linear reference voltage value v is reflected in accordance with the position of the photosensitive drum 3, even if the photosensitive drum 3 is inclined with respect to the scanning direction of the laser beam L, images having the same density can be obtained. Can do. In FIG. 1, the writing CPU 7 periodically calculates the eccentricity amount of the photosensitive drum 3 based on the detected density of the density detection sensors 1 and 2 and updates the stored value of the ID chip 10.

According to the present embodiment, the process cartridge 100 having the ID chip 10 can have the eccentric amount of the photosensitive drum 3 that each has, so even if the process cartridge is replaced, the LD light amount is changed according to the process cartridge. By adjusting, an image having a constant density can be obtained.
Further, by providing the toner density detection sensors 1 and 2 and the writing CPU 7, even if the eccentric amount of the photosensitive drum 3 changes, the eccentric amount stored in the ID chip 10 is updated according to the change. Therefore, the light amount adjustment based on the current eccentricity amount can always be performed, and an image with a constant density can always be obtained.
In addition, since the LD driver 6 automatically changes the light quantity of the LD 5 in accordance with the eccentric amount of the photosensitive drum 3, it is not necessary to adjust the image density with human hands.

It is a block diagram which shows the structure which adjusts LD light quantity based on the eccentric amount data by embodiment of this invention. It is a block diagram which shows the arrangement | positioning relationship between a photoconductor drum and a density detection sensor. FIG. 10 is a characteristic diagram illustrating a method of obtaining the eccentric amount of the photosensitive drum with two sensors. It is a characteristic view which shows the method of calculating | requiring a light quantity from eccentricity. It is a block diagram which shows the toner pattern which a sensor detects. It is a block diagram which shows the relationship with the photoreceptor drum laser beam when there is no eccentricity. FIG. 6 is a characteristic diagram showing a detected toner density when there is no eccentricity. It is a block diagram which shows the relationship with the photoreceptor drum laser beam when there exists eccentricity. FIG. 6 is a characteristic diagram illustrating a relationship between a detected toner density and an eccentric amount when there is an eccentricity. It is a characteristic view which shows the relationship between the amount of eccentricity when there exists eccentricity, and the light quantity of LD. It is a block diagram of the process cartridge by embodiment of this invention.

Explanation of symbols

1, 2 Concentration detection sensor 3 Photosensitive drum 3A Photosensitive drum shaft 5 LD
6 LD driver 7 Writing CPU
7A Charging cleaning roller 8 Toner pattern 9 Development unit 9B Conveying screw (left)
9C Conveying screw (right)
9E T sensor (toner density sensor)
DESCRIPTION OF SYMBOLS 10 ID chip 11 Cleaning unit 11A Cleaning brush 11B Cleaning blade 11C Waste toner conveyance coil 17 Charging roller 31 Developing roller 90 Developing doctor blade 270 Toner cartridge L Laser beam

Claims (7)

An electrostatic latent image is formed by scanning a light beam according to an input image from a light source on a photosensitive drum in a process cartridge that is detachably attached to the image forming apparatus main body, and the electrostatic latent image is formed with toner. In the image forming apparatus to be developed,
Storage means for storing the eccentric amount of the photosensitive drum provided in the process cartridge;
An image forming apparatus, comprising: an adjustment unit that reads the eccentric amount from the storage unit and adjusts the light amount of the light source based on the read eccentric amount.   A sensor for detecting a toner density of a toner image formed on the photosensitive drum, and a writing for calculating an eccentricity amount of the photosensitive drum based on the detected toner density and writing the eccentricity amount in the storage unit 2. The image forming apparatus according to claim 1, further comprising means.   The image forming apparatus according to claim 1, wherein a plurality of the sensors are arranged substantially parallel to the axial direction of the photosensitive drum.   4. The image forming apparatus according to claim 2, wherein the sensor detects a density of a toner pattern formed on the photosensitive drum.   The image forming apparatus according to claim 1, wherein the storage unit is an ID chip.   A process cartridge comprising at least a photoconductive drum, comprising a storage means for storing an eccentric amount of the photoconductive drum.   7. The process cartridge according to claim 6, wherein the storage means is an ID chip.

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