JP2006251409A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To bring an intermediate transfer member into contact with and separate it from a latent image carrier to detect an amount of sticking toner before transfer and an amount of sticking toner left untransferred, by one sensor. <P>SOLUTION: A latent image carrier 2 and an intermediate transfer unit (an intermediate transfer belt 5 and a transfer roller 6) are separated from each other, and then a test pattern 1 is generated on the latent image carrier 2. Laser light is radiated from an optical sensor 4 to the test pattern 1 to detect reflected light. The amount of sticking toner of the test pattern 1 is detected from a value of the reflected light. Next, the latent image carrier 2 and the intermediate transfer unit are brought into contact with each other again, and a test pattern 2 is generated on the latent image carrier 2 in the same condition as the test pattern 1. Laser light is radiated to the test pattern 2 to detect reflected light. The amount of sticking toner of the test pattern 2 is detected from a value of the reflected light. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that detects a transfer rate in accordance with the amount of toner adhered and controls an image forming operation at an optimum transfer rate.

  Conventionally, after transferring the toner image on the latent image carrier to the intermediate transfer member, the amount of toner remaining on the latent image carrier is detected by a sensor, and the transfer conditions are changed according to the toner amount to optimize the transfer rate. As means for achieving this, the inventions disclosed in Patent Document 1 to Patent Document 5 are known.

  Patent Document 1 discloses an invention capable of obtaining a reproduction that more faithfully reproduces a multicolor original.

  Patent Document 2 discloses an invention that can always obtain good image quality without accelerating the deterioration of the intermediate transfer member.

  Patent Document 3 discloses an invention for measuring a residual toner density of a latent image carrier and calculating a transfer rate with and without transferring a toner image to an intermediate transfer member.

  Patent Document 4 discloses an invention that has a transfer belt that can freely contact and separate from a photoconductor, measures the toner density on the photoconductor with a reflective sensor, and separates the belt from the photoconductor during measurement. It is disclosed.

Further, Patent Document 5 discloses an invention in which measurement is performed by adding a correction coefficient including a deviation from a target value at the time of measurement to the output light amount of a reflection type sensor that detects the toner adhesion amount on the image carrier. Has been.
JP-A-5-045994 JP-A-8-272231 JP-A-8-21694 Japanese Patent Laid-Open No. 10-2222026 JP 2002-229279 A

  However, in the conventional technique, a new sensor has to be provided in order to measure the remaining toner adhesion amount after transfer.

  Accordingly, the present invention provides an image forming apparatus that can detect the toner adhesion amount before transfer and the toner adhesion amount remaining after transfer with one sensor by contacting and separating the intermediate transfer member. It is an object.

  In order to achieve the above object, the invention described in claim 1 includes a latent image carrier, and a developing unit that visualizes the electrostatic latent image by supplying toner to the electrostatic latent image on the latent image carrier. An intermediate transfer member that is capable of coming into contact with and separating from the latent image carrier and rotates, and after transferring the toner image on the latent image carrier to the intermediate transfer member, the toner image on the intermediate transfer member is transferred by the transfer device. An image forming apparatus for electrically transferring to a transfer material, wherein the toner is not transferred to an intermediate transfer member but is separated from the latent image carrier and the amount of toner remaining on the latent image carrier is detected. The image forming apparatus includes a first detection unit and a second detection unit configured to detect an adhesion amount of toner remaining on the latent image carrier after the toner is transferred to the intermediate transfer member.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the first detection means and the second detection means are detected by one sensor.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the first detection means and the second detection means for detecting the toner adhesion amount are reflection type optical sensors. It is characterized by that.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the toner adhesion amount detected by the first detection means and the second detection means are detected. The image forming apparatus further includes a comparison unit that compares the toner adhesion amount, and calculates a transfer rate from a comparison result of the comparison unit.

  According to a fifth aspect of the present invention, in the image forming apparatus according to the fourth aspect, the first test pattern created from the toner adhesion amount detected by the first detection unit and the second detection unit And a second test pattern created from the detected toner adhesion amount, and the transfer rate is calculated from the first test pattern and the second test pattern.

  According to a sixth aspect of the present invention, in the image forming apparatus according to the fifth aspect, the first test pattern and the second test pattern are the same test pattern.

  According to a seventh aspect of the present invention, in the image forming apparatus according to the fourth aspect, the output light amount of the photosensor output when the detection is performed by the first detection unit and the second detection unit is the same. It is characterized by that.

  As described above, according to the image forming apparatus of the present invention, the toner adhesion amount before transfer and the remaining toner adhesion amount after transfer are detected by one sensor by contacting and separating the intermediate transfer member. Can do.

Hereinafter, the image forming apparatus of the present embodiment will be described with reference to the drawings. In addition, this embodiment is not limited to what is described below, A various change is possible in the range which does not deviate from the meaning.
FIG. 1 is a block diagram illustrating a configuration of the image forming apparatus according to the present exemplary embodiment.

  The image forming apparatus 1 according to the present embodiment includes a latent image carrier 2, a developing device 3, an optical sensor 4, an intermediate transfer belt 5, a transfer roller 6, an intermediate transfer belt cleaning unit 7, and a paper feeding device 8. A sheet feeding roller 9, a registration roller 10, a secondary transfer roller 11, a fixing unit 12, an exposure unit 13, and a cleaning unit 14.

  The latent image carrier 2 forms an electrostatic latent image for each color component when laser light is exposed from the exposure unit 13, and in this embodiment, a photosensitive member is used. The developing device 3 develops the electrostatic latent image formed on the latent image carrier 2 with laser light. The developing device 3 includes developing units corresponding to the respective colors, that is, developing units corresponding to the respective colors of black (K), magenta (M), cyan (C), and yellow (Y). The optical sensor 4 detects toner adhering to the latent image carrier 2, and in the present embodiment, a reflective optical sensor is used.

  The intermediate transfer belt 5 transfers the electrostatic latent image formed on the latent image carrier 2 and passes through a position where the latent image carrier 2 and the transfer roller 6 are in contact with each other. Is transcribed. The transferred electrostatic latent image is transferred when the transfer sheet from the sheet feeding device 8 is conveyed to the secondary transfer roller 11.

  The intermediate transfer belt cleaning unit 7 removes the untransferred electrostatic latent image remaining on the intermediate transfer belt 5 after the electrostatic latent image is transferred onto the transfer paper by the secondary transfer roller 11. Similarly, the cleaning unit 14 transfers the electrostatic latent image from the latent image carrier 2 to the intermediate transfer belt 5 via the transfer roller 6, and then the untransferred portion remaining on the latent image carrier 2. The electrostatic latent image is removed.

  The paper feeding device 8 stores transfer paper on which the electrostatic latent image is transferred. The transfer paper is conveyed from the paper feeding device 8 via the paper feeding roller 9. The registration roller 10 conveys the electrostatic latent image to the secondary transfer roller 11 in accordance with the timing of transferring the electrostatic latent image onto the conveyed transfer paper. Note that the timing of conveying the transfer paper is detected by a sensor (not shown), and the registration roller 10 conveys the transfer paper according to an instruction from the sensor.

  The secondary transfer roller 11 transfers the electrostatic latent image transferred onto the intermediate transfer belt 5 onto transfer paper. The fixing unit 12 heats and presses the transfer paper on which the electrostatic latent image has been transferred via the secondary transfer roller 11 to fix it. The exposure unit 13 irradiates the latent image carrier 2 with laser light in accordance with an image signal sent from an image processing unit (not shown).

  When calculating the transfer rate in the present embodiment, first, as shown in FIG. 2A, the intermediate transfer unit (the intermediate transfer belt 5 and the transfer roller 6) is separated from the latent image carrier 2. Then, a test pattern 1 is created on the latent image carrier 2, and after the test pattern 1 is detected by the optical sensor 4, the intermediate transfer unit is applied to the latent image carrier 2 as shown in FIG. Touch (return to the original position).

Next, the operation of the above-described embodiment will be described with reference to the drawings.
FIG. 3 is a flowchart showing an operation for calculating the transfer rate in the image forming apparatus of the present embodiment.

  First, the latent image carrier 2 and the intermediate transfer unit (intermediate transfer belt 5 and transfer roller 6) are separated (step S1). After separating the intermediate transfer unit, next, a test pattern 1 is created on the latent image carrier 2 (step S2).

  At this time, since the intermediate transfer unit is already separated from the latent image carrier 2, laser light is emitted from the optical sensor 4 to the test pattern 1 remaining on the latent image carrier 2 without transferring the toner. The reflected light when irradiated is detected (step S3). Then, the toner adhesion amount of the test pattern 1 is detected from the value of the reflected light (step S4).

  After detecting the toner adhesion amount of the test pattern 1, the latent image carrier 2 and the intermediate transfer unit are brought into contact again (step S5). Next, the test pattern 2 is created on the latent image carrier 2 under the same conditions as when the test pattern 1 was created (step S6).

  Then, since the intermediate transfer unit and the latent image carrier 2 are in contact with each other, the optical sensor is used for the test pattern 2 that has been transferred to the intermediate transfer unit and not transferred onto the latent image carrier 2. The reflected light when the laser beam is irradiated from 4 is detected (step S7). Then, the toner adhesion amount of the test pattern 2 is detected from the value of the reflected light (step S8).

The transfer rate is calculated based on the toner adhesion amount of the test pattern 1 and the toner adhesion amount of the test pattern 2 thus obtained (step S9). This transfer rate is calculated by the following calculation formula (1).
Transfer rate = 1− (toner adhesion amount of test pattern 2 / toner adhesion amount of test pattern 1) (1)

  After calculating the transfer rate in this way, the optimum transfer conditions can be derived from the calculated transfer rate using existing techniques.

  As described above, according to the image forming apparatus of the present embodiment, the test pattern 1 and the test pattern 2 can be detected by a single sensor by performing contact and separation of the intermediate transfer unit. Therefore, cost can be reduced. In addition, since one sensor is used, variations in the amount of light output from the sensor and variations in light reception can be eliminated. Therefore, detection accuracy can be improved as compared with the case of using two sensors.

1 is a block diagram illustrating a configuration of an image forming apparatus according to an exemplary embodiment. FIG. 3 is a diagram illustrating separation / contact between a latent image carrier and an intermediate transfer unit in the image forming apparatus according to the present exemplary embodiment. 4 is a flowchart illustrating an operation of the image forming apparatus according to the exemplary embodiment. It is a figure which shows the test pattern 1 and the test pattern 2 in this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Latent image carrier 3 Developing device 4 Optical sensor 5 Intermediate transfer belt 6 Transfer roller 7 Intermediate transfer belt cleaning unit 8 Paper feed device 9 Paper feed roller 10 Registration roller 11 Secondary transfer roller 12 Fixing unit 13 Exposure unit 14 Cleaning unit

Claims (7)

A latent image carrier;
Developing means for supplying toner to the electrostatic latent image of the latent image carrier to visualize the electrostatic latent image;
An intermediate transfer member that can be moved toward and away from the latent image carrier and rotates,
An image forming apparatus that electrically transfers a toner image of the intermediate transfer member to a transfer material by a transfer device after transferring the toner image on the latent image carrier to the intermediate transfer member,
First detecting means for detecting an adhesion amount of the toner remaining on the latent image carrier separated from the latent image carrier without transferring the toner to the intermediate transfer member;
An image forming apparatus comprising: a second detection unit configured to detect an adhesion amount of the toner remaining on the latent image carrier after the toner is transferred to the intermediate transfer member.   The image forming apparatus according to claim 1, wherein the first detection unit and the second detection unit are detected by a single sensor.   3. The image forming apparatus according to claim 1, wherein the first detection unit and the second detection unit that detect the toner adhesion amount are reflection type optical sensors. 4. A comparison means for comparing the toner adhesion amount detected by the first detection means with the toner adhesion amount detected by the second detection means;
4. The image forming apparatus according to claim 1, wherein a transfer rate is calculated from a comparison result of the comparison unit. A first test pattern created from the toner adhesion amount detected by the first detection means and a second test pattern created from the toner adhesion amount detected by the second detection means And
The image forming apparatus according to claim 4, wherein a transfer rate is calculated based on the first test pattern and the second test pattern.   The image forming apparatus according to claim 5, wherein the first test pattern and the second test pattern are the same test pattern.   5. The image forming apparatus according to claim 4, wherein output light amounts of the photosensors output when detection is performed by the first detection unit and the second detection unit are the same. 6.

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