JP2006030743A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect a correct timing of replenishing a lubricant supply body by correcting detection error caused when detecting the timing of replenishing the lubricant supply body. <P>SOLUTION: The output of a surface condition sensor that detects the surface condition of a photoreceptor is read as a relative value that is a ratio between an output when a lubricant is not applied and an output when the lubricant is applied. The output of the surface condition sensor is used to detect the supply timing of the lubricant supply body. In addition, the surface condition of the photoreceptor is detected in a state without fogging thereon, thereby eliminating the detection error caused by fogging. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic image forming apparatus, and more particularly to an image forming apparatus using a lubricant to improve toner image transferability.

  In recent years, even in electrophotographic image forming apparatuses, high-quality color images comparable to offset printing have been required.

  There are several types of methods for forming a color image using two or more colors of toner by an electrophotographic method. To obtain a good image with little color misregistration, the toner images are superimposed on the intermediate transfer member. The method is advantageous. An image forming method using such an intermediate transfer member is hereinafter referred to as an intermediate transfer member method.

  In the case of the intermediate transfer body method, when transferring the toner image from the photosensitive member to the intermediate transfer member, a primary transfer unit is configured, and the transfer roller to which voltage is applied is pressed from the back side of the intermediate transfer member to the photosensitive member side. Many transfer methods are used.

  However, in this transfer, there is a problem that a part of the toner image is not transferred and remains on the photosensitive member, and a desired transfer is not performed. In particular, the toner forming the central portion of a line image or dot image is subject to strong pressure due to the nip between the photosensitive member and the intermediate transfer member in the transfer process, and tends to agglomerate. There is a problem that a phenomenon called “hollow-out” occurs in which the image remains on the photosensitive member without being transferred and the central portion of the image is white.

  The hollow-out phenomenon is caused by the magnitude relationship between the adhesion force between the toner and the photosensitive member and the adhesion force between the toner and the intermediate transfer member. It is possible to reduce the probability of occurrence by reducing the attachment force.

  As a method for reducing the adhesion between the toner and the photoconductor, a method of applying a lubricant to the surface of the photoconductor is effective, and a metal stearate such as zinc stearate is generally used as the lubricant. . For example, as described in Patent Document 1, using an application roller, the lubricant is scraped off from a solid lubricant supply body, and the lubricant is applied onto the photoconductor by an application method of applying to the photoconductor. Is done.

Patent Document 1 adopts a method in which a small amount of lubricant is continuously transferred to the application roller by pressing the lubricant supply body against the application roller with a spring.
JP 2003-330320 A

  Since the lubricant is consumed by image formation, a new supply is required when the remaining amount is low. On the other hand, the photoconductor is also a component with a long life and requires replenishment. Therefore, it would be advantageous if the replenishment of the lubricant could be made coincident with the replenishment of the photoconductor. Therefore, it has become necessary to replenish the lubricant independently of the photoreceptor.

  However, in the past, since there was no means for accurately replenishing the lubricant, there was a problem that the replenishment was too early and the running cost was increased, or the replenishment was too late and the lubricant was insufficient and the image quality was degraded. was there.

  An object of the present invention is to always accurately supply a lubricant by detecting the timing of replenishment of the lubricant, to prevent a decrease in image quality, and to suppress an increase in running cost. In particular, an object of the present invention is to provide a detection technique that can reliably detect the replenishment time by reducing detection errors caused during the replenishment time of the lubricant.

The object of the present invention is achieved by the following invention.
(Claim 1)
A photoreceptor,
Latent image forming means for forming an electrostatic latent image on the photoreceptor;
Developing means for developing the electrostatic latent image;
An intermediate transfer member;
Primary transfer means for transferring the toner image on the photosensitive member to the intermediate transfer member;
Secondary transfer means for transferring the toner image on the intermediate transfer member to a recording medium;
In an image forming apparatus having a lubricant application means for applying a lubricant to the surface of the photoreceptor,
A lubricant supplier mounted on the lubricant application means;
A surface condition sensor for inspecting the surface condition of the photoreceptor;
Control means for detecting the replenishment time of the lubricant,
The surface condition sensor comprises a regular reflection type surface condition sensor comprising a light emitting element that projects light onto the photoconductor and a light receiving element that detects light specularly reflected by the photoconductor,
The control means rotates the photoconductor for a predetermined time while applying the lubricant and the received light amount L1 of the regular reflection type surface state sensor when the photoconductor is rotated for a predetermined time without applying the lubricant. When the ratio L2 / L1 of the specular reflection type surface state sensor when L2 / L1 is equal to or greater than a predetermined value, a signal that prompts replenishment of the lubricant supply body is output. Image forming apparatus.
(Claim 2)
A photoreceptor,
Latent image forming means for forming an electrostatic latent image on the photoreceptor;
Developing means for developing the electrostatic latent image;
An intermediate transfer member;
Primary transfer means for transferring the toner image on the photosensitive member to the intermediate transfer member;
Secondary transfer means for transferring the toner image on the intermediate transfer member to a recording medium;
In an image forming apparatus having a lubricant application means for applying a lubricant to the surface of the photoreceptor,
A lubricant supplier mounted on the lubricant application means;
A surface condition sensor for inspecting the surface condition of the photoreceptor;
Control means for detecting the replenishment time of the lubricant,
The surface condition sensor comprises a diffuse reflection type surface condition sensor comprising a light emitting element that projects light onto the photoconductor and a light receiving element that detects light irregularly reflected by the photoconductor, and
The control means includes a light receiving amount L1 of the light receiving element when the photoconductor is rotated for a predetermined time without applying the lubricant, and when the photoconductor is rotated for a predetermined time while applying the lubricant. An image forming apparatus that outputs a signal that prompts replenishment of the lubricant supply body when L2 / L1 of the ratio of the light receiving element to the light receiving amount L2 becomes equal to or less than a predetermined value.
(Claim 3)
A photoreceptor,
Latent image forming means for forming an electrostatic latent image on the photoreceptor;
Developing means for developing the electrostatic latent image;
An intermediate transfer member;
Primary transfer means for transferring the toner image on the photosensitive member to the intermediate transfer member;
Secondary transfer means for transferring the toner image on the intermediate transfer member to a recording medium;
In an image forming apparatus having a lubricant application means for applying a lubricant to the surface of the photoreceptor,
A lubricant supplier mounted on the lubricant application means;
A surface condition sensor for inspecting the surface condition of the photoreceptor;
Control means for detecting the replenishment time of the lubricant;
Developing bias adjusting means for adjusting the developing bias in the developing means,
The developing bias adjusting means sets a state in which there is substantially no fog on the photosensitive member, and in this state, the surface state sensor detects the surface state of the photosensitive member, and the control means includes the surface state sensor. An image forming apparatus that detects the replenishment timing of the lubricant supply body based on the detection result.
(Claim 4)
The surface condition sensor comprises a regular reflection type surface condition sensor comprising a light emitting element that projects light onto the photoconductor and a light receiving element that detects light specularly reflected by the photoconductor,
The development bias adjusting means changes the development bias in steps, and uses the received light amount of the light receiving element when a change in the received light amount of the light receiving element per step becomes a predetermined value or less as a detection value. The image forming apparatus according to claim 3, wherein the control unit outputs a signal that prompts replenishment of the lubricant supply body when a predetermined amount or more is increased from a reference value.
(Claim 5)
The surface condition sensor comprises a diffuse reflection type surface condition sensor comprising a light emitting element that projects light onto the photoconductor and a light receiving element that detects light irregularly reflected by the photoconductor,
The development bias adjusting means changes the development bias in steps, and uses the received light amount of the light receiving element when a change in the received light amount of the light receiving element per step becomes a predetermined value or less as a detection value. The image forming apparatus according to claim 3, wherein the control unit outputs a signal that prompts replenishment of the lubricant supply body when a predetermined amount or more is decreased from a reference value.
(Claim 6)
The image forming apparatus according to claim 1, wherein the developing unit performs development using a polymerized toner.
(Claim 7)
A plurality of image forming portions each having the photosensitive member, the latent image forming unit, the developing unit, and the primary transfer unit are provided, and a color toner image in which a plurality of toner images are superimposed is formed on the intermediate transfer member. The image forming apparatus according to any one of claims 1 to 6.
(Claim 8)
The image forming apparatus according to claim 1, wherein the lubricant is made of a metal stearate.
(Claim 9)
The image forming apparatus according to claim 1, wherein the surface state sensor is used as a density sensor that detects a density of a toner image.
(Claim 10)
The image forming apparatus according to claim 1, wherein the control unit corrects a detection error by controlling a light emission amount of a light source of the surface state sensor.

  According to the invention of any one of claims 1 to 10, the replenishment timing of the lubricant supply body mounted on the image forming apparatus is accurately detected. Lubricant replenishment is too early, and the lubricant is not wasted.

  According to the first or second aspect of the present invention, the detection error caused by the toner adhering to the sensor window is corrected well, and the replenishment timing of the lubricant supply body is always accurately detected.

  According to the invention of any one of claims 3 to 5, even when the toner adheres to the surface of the photoreceptor, the detection error due to the fog is corrected well, and the replenishment timing of the lubricant supply body is always accurate. Detected.

  According to the invention of claim 6, since image formation is performed using uniform toner in shape and particle size distribution, a high quality image with excellent image characteristics such as resolution, gradation expression and color reproducibility is formed. An image forming apparatus is realized.

  According to the seventh aspect of the present invention, an image forming apparatus for forming a high-quality color image is realized.

  According to the ninth aspect of the present invention, an image forming apparatus that realizes a high-quality image with stable image quality is realized. In addition, since a common sensor is used for the image quality control density sensor and the lubricant replenishment control sensor, an increase in cost due to the provision of the lubricant replenishment timing detection function can be avoided.

  According to the tenth aspect of the present invention, the detection error due to the toner adhering to the sensor window is corrected.

<Embodiment 1>
FIG. 1 is a diagram showing a color image forming apparatus according to an embodiment of the present invention.

  This color image forming apparatus is called a tandem type color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, an intermediate transfer unit 7, a sheet feeding and conveying unit, and a fixing unit 24. Become. A document image reading device SC is disposed above the color image forming apparatus.

  The image forming unit 10Y that forms a yellow image includes a charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, a transfer roller 5Y as a primary transfer unit, and a cleaning unit 6Y disposed around the photoreceptor 1Y. The image forming unit 10M that forms a magenta image includes a photoreceptor 1M, a charging unit 2M, an exposure unit 3M, a developing unit 4M, a transfer roller 5M as a primary transfer unit, and a cleaning unit 6M. The image forming unit 10C that forms a cyan image includes a photoreceptor 1C, a charging unit 2C, an exposure unit 3C, a developing unit 4C, a transfer roller 5C as a primary transfer unit, and a cleaning unit 6C. The image forming unit 10K that forms a black image includes a photoreceptor 1K, a charging unit 2K, an exposure unit 3K, a developing unit 4K, a transfer roller 5K as a primary transfer unit, and a cleaning unit 6K.

  The belt-like intermediate transfer member 7 is semiconductive and is wound around a plurality of rollers and supported so as to be able to circulate.

  The color images formed by the image forming units 10Y, 10M, 10C, and 10K are sequentially transferred onto the circulating intermediate transfer body 70 by the transfer rollers 5Y, 5M, 5C, and 5K, and are superimposed and synthesized. Is formed. The recording paper P as a recording medium accommodated in the paper feeding cassette 20 is fed by a paper feeding means 21 and passes through a plurality of intermediate rollers 22A, 22B, 22C, 22D and a registration roller 23 as a secondary transfer means. Are transferred to the transfer roller 5A, and the color images are collectively transferred onto the recording paper P by the transfer roller 5A. The recording paper P onto which the color image has been transferred is fixed by the fixing means 24, conveyed to the paper discharge roller 25, and discharged onto a paper discharge tray 26 outside the apparatus.

  On the other hand, after the color image is transferred onto the recording paper P by the transfer roller 5A, the recording paper P intermediate transfer body 70 passes through the cleaning means 6A, and the residual toner is removed.

  FIG. 2 shows the structure of the image forming units 10Y, 10M, 10C, and 10K in FIG. Since the image forming units 10Y, 10M, 10C, and 10K have the same structure, in the following description, the image forming units 10Y, 10M, 10C, and 10K are collectively referred to as 10, and the photoreceptors 1Y, 1M, 1C, and 1K. Is collectively referred to as a photoreceptor 1, charging means 2Y, 2M, 2C and 2K are collectively referred to as 2, and exposure means 3Y, 3M, 3C and 3K are collectively referred to as exposure means 3 and developing means 4Y, 4M and 4C. And 4K are collectively referred to as developing means 4, transfer rollers 5Y, 5M, 5C and 5K are collectively referred to as 5, and cleaning means 6Y, 6M, 6C and 6K are collectively referred to as 6. Further, the lubricant applying means described below is provided in each of the image forming units 10Y, 10M, 10C, and 10K. The exposing unit 3 and the developing unit 4 constitute an image forming unit that forms a toner image on the photoreceptor 1.

  As the photosensitive member 1, a well-known one such as an OPC photosensitive member or an aSi photosensitive member is used. An OPC photosensitive member is preferable, and a negatively charging OPC photosensitive member is particularly preferable. OPC is used.

  As the charging means 2, a corona discharge device such as a scorotron or a corotron is used, and a scorotron discharge device is preferably used.

  As the exposure means, a light emitting element that emits light according to image data, such as a laser or an LED array, is used.

  As the developing means 4, a developing device using a two-component developer mainly composed of a carrier and a toner or a developing device using a one-component developer mainly composed of a toner without including a carrier is used. A two-component developing device using a diameter toner is preferable. In addition, a developing device that performs development by regular development or a device that performs reversal development can be used in the developing device. However, a developing bias having the same polarity as the charging of the photosensitive member 1 is applied to the developing sleeve 4a, and the charging of the photosensitive member is the same. Reversal development in which development is performed with toner charged to polarity is preferable. In this embodiment, development is performed by reversal development using negatively charged toner.

  As the toner having a small particle diameter, a toner having a volume average particle diameter of 3 to 6 μm is preferable.

  The volume average particle diameter is an average particle diameter based on volume, and is a value measured by “Coulter Counter TA-II” or “Coulter Multisizer” (both manufactured by Coulter, Inc.) equipped with a wet disperser.

  A high-quality image having a high resolving power can be formed by such a small particle size toner. A toner having a volume average particle diameter larger than 6 μm weakens the characteristics of high image quality.

  When a toner having a volume average particle size of less than 3 μm is used, the image quality is likely to deteriorate due to fogging.

  In the present invention, spherical toner is desirable, and the degree of spheroidization is desirably 0.94 or more and 0.98 or less.

Degree of spheroidization = (perimeter of a circle with the same area as the particle projection image) / (perimeter of the particle projection image)
The degree of spheroidization is obtained by taking a photograph of resin particles enlarged 500 times with a scanning electron microscope or laser microscope for 500 resin particles, and using an image analysis apparatus “SCANNING IMAGE ANALYSER” (manufactured by JEOL Ltd.) Then, the photographic image is analyzed, the circularity is measured, and the arithmetic average value can be obtained. Moreover, as a simple measuring method, it can measure with "FPIA-1000" (made by Toa Medical Electronics Co., Ltd.).

  When the spheroidization degree is less than 0.94, it is pulverized as a result of being subjected to strong stress in the developing means, and fog and toner scattering are likely to occur. If the sphericity is greater than 0.98, it may be difficult to maintain high cleaning performance.

  For the toner having a small particle diameter and a high sphericity as described above, it is desirable to use a polymerized toner.

  The polymerized toner means a toner obtained by forming a binder resin for toner and forming the toner shape by polymerization of a raw material monomer or prepolymer of the binder resin and subsequent chemical treatment. More specifically, it means a toner obtained through a polymerization reaction such as suspension polymerization or emulsion polymerization and, if necessary, a step of fusing particles between them. In a polymerized toner, a raw material monomer or prepolymer is uniformly dispersed in an aqueous system and then polymerized to produce a toner, so that a toner having a uniform toner particle size distribution and shape can be obtained.

  Specifically, a polymer is produced by emulsion polymerization of a monomer in a liquid of an aqueous medium to which an emulsion is added or a suspension polymerization method, and then an organic solvent, agglomeration is produced. It can manufacture by the method of adding an agent etc. and making it associate. A method of preparing by mixing with a dispersion liquid of a release agent or a colorant necessary for the constitution of the toner at the time of association, or a toner component such as a release agent or a colorant dispersed in a monomer Examples thereof include emulsion polymerization. Here, the association means that a plurality of resin particles and colorant particles are fused.

  The transfer roller 5 is a semiconductive rubber roller. A transfer voltage having a polarity opposite to that of the toner is applied to the transfer roller 5 by a power source 5E. The transfer roller 5 uses a spring 5R to transfer the intermediate transfer member 7 to the photosensitive member. Press to 1.

  The cleaning means 6 performs cleaning with a cleaning blade made of a rubber blade.

  As shown in FIG. 2, a lubricant application unit is provided between the transfer roller 5 and the cleaning unit 6. FIG. 2 is a front view of the image forming unit, and FIG. 3 is a side view of the lubricant application unit. As shown in FIGS. 2 and 3, the lubricant application means comprises a brush roller, and includes a lubricant application roller 30 that applies the lubricant to the photosensitive member 1 by rotation, a solid rod-like lubricant supply body 31, and a lubricant 31. The support member 33 includes a spring 32A and a spring 32B that press the lubricant supply body 31 against the lubricant application roller 30 with a predetermined pressure.

  The lubricant is applied to the surface of the photoreceptor mainly for the purpose of improving transferability and cleaning properties, and generally comprises a fatty acid metal salt. Specific examples of the lubricant include metal stearate such as zinc stearate, aluminum stearate, copper stearate, magnesium stearate, zinc oleate, manganese oleate, iron oleate, copper oleate, magnesium oleate, etc. Metal oleate, metal palmitate such as zinc palmitate, copper palmitate, magnesium palmitate, metal linoleate such as zinc linoleate and zinc linoleate, metal ricinoleate such as zinc ricinoleate and lithium ricinoleate Salts, and the like. Metal stearates are preferred, zinc stearate is particularly preferred, and zinc stearate is used in the present embodiment.

  The photoconductor 1 rotates as indicated by an arrow, and the lubricant application roller 30 rotates to scrape off the lubricant from the lubricant supply 31 and apply it to the surface of the photoconductor.

  Although the volume of the lubricant supply body 31 is reduced by application, the amount of biting of the lubricant supply body 31 into the lubricant application roller 30 by the springs 32A and 32B is maintained substantially constant, and the amount of lubricant applied is substantially constant. Yes.

  When the lubricant supply body 31 is nearly exhausted, the lubricant application amount gradually decreases from the appropriate value, and the application amount decreases. When the lubricant supply body 31 is lost or its volume is reduced to a level where uniform application is not possible, a new lubricant supply body 31 is replenished and loaded.

  It is necessary that such a replenishment of the lubricant supply body 31 is reliably performed and proper lubricant application is always performed. For this purpose, the control means 40 performs replenishment control described below.

  The control means 40 as a control means for detecting the replenishment timing of the new lubricant supply body 31 maintains the amount of lubricant applied to the photoreceptor 1 at an appropriate value based on the detection value of the regular reflection type surface state sensor 41. Replenishment control is performed.

  The regular reflection type surface state sensor 41 includes a light projecting element 41A composed of an LED (light emitting diode) and a light receiving element 41B composed of a phototransistor. The light projecting element 41 </ b> A and the light receiving element 41 </ b> B each have directivity, the light projecting element 41 </ b> A projects light at an incident angle of 45 ° to the photoconductor 1, and the light receiving element 41 </ b> B is a regular reflection light from the photoconductor 1. That is, specularly reflected light having a reflection angle of 45 ° is detected. The light receiving element 41B has little sensitivity to irregularly reflected light.

  The regular reflection type surface state sensor 41 optically inspects the surface state of the photoreceptor 1 between the developing means 4 and the transfer roller 5 as shown in the figure. In the present embodiment, a reference pattern referred to as a patch image is formed on the photoreceptor 1, the density of the reference pattern is detected, and toner is supplied to the developing unit 4 and image formation is performed based on the detected value. Although the image quality control for controlling the conditions is performed, the regular reflection surface state sensor 41 is also used as a density sensor for detecting the density of the reference pattern formed on the photoconductor in such image quality control. The image quality control is described in JP-A-8-146749, JP-A-8-234536, JP-A-2002-207326, and the like.

  In a state where an appropriate amount of lubricant is present on the surface of the photoconductor 1, the surface of the photoconductor 1 is in a cloudy state and exhibits irregular reflection, but as the amount of lubricant on the surface of the photoconductor decreases, the photoconductor 1 The surface of the surface is close to a mirror surface, and the reflected light of the photoreceptor 1 has a larger amount of specularly reflected light.

  The control means 40 reads the output of the regular reflection type surface state sensor 41 and determines that the amount of lubricant has decreased when the amount of light received by the light receiving element 41B increases.

  In the normal state, the application of the lubricant is performed uniformly as described above. However, when the lubricant supply body 30 is used up and its replenishment is required, the amount of application decreases. To do. Therefore, the control means 40 monitors the output of the regular reflection type surface state sensor 41, determines that the lubricant supply body needs to be replenished when the amount of light received by the light receiving element 41B exceeds a predetermined value, and lubrication is performed. A signal that prompts replenishment of the agent supply body 31 is output and displayed on the display means 50.

  In the present embodiment, the error correction described below is performed based on the above-described supply control of the lubricant supplier.

  FIG. 4 is a flowchart of replenishment control for notifying the replenishment of the lubricant supplier 31.

  In STEP 1, a developing bias that does not cause fogging is set in the developing sleeve 4a of the developing unit.

  Next, in STEP 2, the photosensitive member 1 is rotated for a predetermined time t <b> 1 while the lubricant application brush 30 is separated from the photosensitive member 1. By such rotation of the photosensitive member 1, the lubricant remaining on the photosensitive member 1 is scraped and removed by the developing brush of the developing unit 4 and the cleaning blade of the cleaning unit 6.

  When the photosensitive member 1 is rotated for a predetermined time t1 and no lubricant is present on the surface of the photosensitive member 1, the control means 40 reads the output of the regular reflection type surface state sensor 41 to obtain the output S1 (STEP 3). .

  Next, the lubricant application brush 30 is brought into contact with the photoreceptor 1, and the photoreceptor 1 and the lubricant application brush 30 are rotated for a predetermined time t2 to apply the lubricant to the surface of the photoreceptor 1 (STEP 4).

  At the stage where this lubricant application process is performed for a predetermined time t2, the control means 40 reads the output of the regular reflection type surface state sensor 41 and obtains the output S2 (STEP 5).

  The light receiving element 41B shows an output proportional to the amount of received light. Therefore, the output ratio S2 / S1 is equal to the ratio L2 / L1 of the amount of received light.

  Based on the ratio L2 / L1 between the received light amount L1 when the lubricant is not applied and the received light amount L2 when the lubricant is applied, the control means 40 determines whether or not the lubricant supplier 31 needs to be replenished.

  That is, when the ratio L2 / L1 is equal to or greater than the predetermined threshold value K0, the amount of lubricant on the photoconductor 1 is small, so it is determined that the lubricant supplier needs to be replenished (YES in STEP 6), and the lubricant supplier is replenished. A signal for prompting is output and displayed on the display unit 50 to that effect (SUTEP7). In other cases, it is determined that it is unnecessary (NO in STEP 6).

  Toner is likely to adhere to the light projecting element 41A and the light receiving element 41B, and the amount of light received by the light receiving sensor 41B is reduced due to the adhesion of the toner, and detection errors are likely to occur. However, as described above, the light receiving element 41B Since the amount of lubricant on the photosensitive member 1 is inspected not by the absolute value of the output but by the relative value when the lubricant is applied and when the lubricant is not applied, the detection error due to contamination of the light projecting element 41A and the light receiving element 41B is corrected and excluded. Is done.

When the performance of the entire detection system deteriorates due to toner adhering to the light projecting element 41A and the light receiving element 41B, the detection performance can be maintained by adjusting the amount of light emitted from the light projecting element 41A. . That is, when the output level of the light receiving element 41B is equal to or less than a range showing a linear output with respect to the amount of received light, correction is performed to increase the output of the light projecting element 41A, and the output of the light receiving element 41B is linearly changed. Correction is performed to maintain the characteristic range.
<Embodiment 2>
FIG. 5 shows an image forming unit in Embodiment 2 of the present invention.

  This embodiment is the same as FIGS. 2 and 3 in terms of the device configuration and the principle of detecting the lubricant replenishment timing, except that the irregular reflection surface state sensor 42 is used. Further, the irregular reflection surface state sensor 42 can also be used as a density sensor in image quality control.

  The irregular reflection type surface state sensor 42 includes a light projecting element 42A made of an LED (light emitting diode) and a light receiving element 42B made of a phototransistor. Each of the light projecting element 42A and the light receiving element 42B has directivity, and the light projecting element 42A projects light onto the photosensitive member 1 at an incident angle of 45 °. The light receiving element 42B receives irregularly reflected light from the photoreceptor 1, that is, reflected light having a reflection angle of 0 °, but the light receiving element 42B has little sensitivity to regular reflected light.

  The supply control of the lubricant supply body 31 is performed according to the flowchart of FIG.

  In STEP 1, the developing bias is set to a value that does not cause fogging.

  Next, in STEP 2, the photosensitive member 1 is rotated for a predetermined time t <b> 1 while the lubricant application brush 30 is separated from the photosensitive member 1. By such rotation of the photosensitive member 1, the lubricant remaining on the photosensitive member 1 is scraped and removed by the developing brush of the developing unit 4 and the cleaning blade of the cleaning unit 6.

  When the photosensitive member 1 is rotated for a predetermined time and no lubricant is present on the surface of the photosensitive member 1, the control means 40 reads the output of the irregular reflection type surface state sensor 42 and obtains an output S1 (STEP 3).

  Next, the lubricant application brush 30 is brought into contact with the photoreceptor 1, and the photoreceptor 1 and the lubricant application brush 30 are rotated for a predetermined time t2 to apply the lubricant to the surface of the photoreceptor 1 (STEP 4). At the stage where this lubricant application step is performed for a predetermined time t2, the control means 40 reads the output from the irregular reflection type surface state sensor 42 to obtain the output S2 (STEP 5).

  The light receiving element 42B shows an output proportional to the amount of received light. Therefore, the output ratio S2 / S1 is equal to the ratio L2 / L1 of the amount of received light.

  Based on the light reception amount ratio L2 / L1, it is determined whether or not the lubricant supplier 31 needs to be replenished.

  That is, when the ratio L2 / L1 is equal to or less than the predetermined threshold value K1, the amount of lubricant on the photosensitive member 1 is small, so it is determined that the lubricant supplier needs to be replenished (YES in STEP 6A). (NO in STEP6A).

Toner is likely to adhere to the light projecting element 42A and the light receiving element 42B, and the amount of light received by the light receiving sensor 42B is reduced due to the adhesion of the toner, so that a detection error is likely to occur. However, as described above, the light receiving element Since the amount of lubricant on the photosensitive member 1 is inspected not by the absolute value of the output of 42B but by the relative value when the lubricant is applied and when the lubricant is not applied, the detection error due to contamination of the light projecting element 42A and the light receiving element 42B is corrected. Excluded.
<Embodiment 3>
In the present embodiment, a surface condition sensor for inspecting the surface condition of the photosensitive member is used to detect the replenishment timing of the lubricant supply member, and the detection error caused by the fog that adheres toner to the photosensitive member is corrected. The replenishment time is detected.

  In the present embodiment, the lubricant application unit shown in FIG. 2 is used, and replenishment control is performed according to the flowchart shown in FIG.

  In STEP 10, a stepwise developing bias is applied to the developing sleeve 4 a of the developing unit 4 to rotate the photoreceptor 1.

  As shown in FIG. 8, the developing bias is applied so as to lower the potential of the developing sleeve 4a by a constant value ΔV from the initial value V2.

  As described above, in this embodiment, since reversal development using negatively charged toner is performed, the initial value V2 is negative, and the figure shows the absolute value of the potential. Due to such a step-like potential, the potential difference V1-V2 between the charging potential V1 of the photoreceptor 1 and the potential V2 of the developing sleeve 4a increases in a step-like manner.

  The initial value V <b> 1-V <b> 2 of the potential difference is set to such a low value that fog is generated on the photoconductor 1. In one example, it is 50V. As the potential difference increases, fog decreases.

  Due to the reduction of fog on the photoconductor 1, the surface of the photoconductor 1 becomes close to a mirror surface and the specular reflection becomes strong. Accordingly, the output of the regular reflection type surface state sensor 41 increases as the fog decreases, but the increase rate, that is, the increase ΔS of the output of the regular reflection type surface state sensor 41 per step ΔV (for example, 10V) is small. Thus, the stage when the output increase ΔS of the regular reflection type surface state sensor 41 per step ΔV becomes equal to or less than a predetermined value K2 (for example, 0.1 V), that is, the saturation stage can be made without fogging.

  Accordingly, when the output increase ΔS of the regular reflection type surface state sensor 41 per step ΔV is equal to or less than a predetermined threshold value, the value indicating the surface state of the photoreceptor 1 from which the light reception amount of the light receiving element 41B has removed the error due to fogging. It becomes.

  In STEP 11, the increase ΔS of the output of the regular reflection type surface state sensor 41 is read. In STEP 12, when the increase ΔS becomes equal to or less than the predetermined threshold value K 2 (YES in STEP 12), the surface state of the photoreceptor 1 is detected. Then, the supply timing of the lubricant supply body 31 is detected.

This replenishment time is detected according to the steps from STEP 2 to STEP 7 in the first embodiment.
<Embodiment 4>
In the present embodiment, a surface condition sensor for inspecting the surface condition of the photosensitive member is used to detect the replenishment timing of the lubricant supply member, and the detection error caused by the fog that adheres toner to the photosensitive member is corrected. The replenishment time is detected.

  In the present embodiment, the lubricant application part shown in FIG. 5 is used, but the method for inspecting the surface state of the photoconductor 1 by correcting the influence of fogging of the photoconductor 1 is the same as in the third embodiment. Is.

  Also in the present embodiment, the stepwise developing bias shown in FIG. 8 is applied to the developing sleeve 4 a of the developing means 4. Then, the surface state of the photoreceptor 1 that has passed through the developing means 4 with the developing bias applied is inspected by the irregular reflection type surface state sensor 42.

  The potential difference is increased stepwise by decreasing the potential of the developing sleeve 4a step by step by a constant value ΔV.

  As described above, in the present embodiment, since reversal development using negatively charged toner is performed, fogging decreases as the potential difference increases.

  Due to the reduction of fog on the photoconductor 1, the surface of the photoconductor 1 becomes close to a mirror surface and the specular reflection becomes strong. Therefore, as the fog is reduced, the output of the irregular reflection type surface state sensor 42 is decreased. However, the rate of reduction, that is, the decrease width of the output of the irregular reflection type surface state sensor 42 per step ΔV is reduced, and the irregular reflection per step ΔV. The stage where the output of the mold surface state sensor 42 is saturated can be made free of fog.

  Therefore, the value representing the surface state of the photoreceptor 1 from which the output of the irregular reflection type surface state sensor 42 has removed an error due to fogging when the output decrease of the irregular reflection type surface state sensor 42 per step ΔV is equal to or less than a predetermined threshold value. It becomes.

  FIG. 9 is a flowchart of supply control according to the fourth embodiment.

  In STEP 10, a stepwise developing bias is applied to the developing sleeve 4 a of the developing unit 4 to rotate the photoreceptor 1.

  In STEP 11A, the decrease ΔS ′ of the output of the irregular reflection type surface state sensor 42 is read, and in STEP 12A, when the decrease ΔS ′ is equal to or less than a predetermined threshold K3 (YES in STEP 12A), the surface state of the photoreceptor 1 is detected. Then, the supply timing of the lubricant supply body 31 is detected. This replenishment time is detected according to the steps from STEP 2 to STEP 7 in the second embodiment.

An image was formed with the following settings using the color image forming apparatus shown in FIG.
Image forming apparatus: A4 (vertical) 65 sheets / minute, color copying machine process speed (speed of photosensitive member and intermediate transfer member): 320 mm / sec
Photoconductor: negatively chargeable OPC, drum-shaped photoconductor having a diameter of 60 mm. Photoconductor charge voltage: variable (standard value: -700 V)
Development bias: DC + AC
DC component: variable (standard value: -500V)
AC component: sine wave
1 kVp-p (voltage)
5 kHz (frequency)
Photoconductor solid exposure potential: -50V
Exposure means: Semiconductor laser (wavelength: 780 μm)
Development sleeve / photoreceptor distance: about 0.35 mm
Developer transport amount to developing sleeve: 25 mg / cm ²
Toner: Polymerized toner having a volume average particle diameter of 4.5 μm (YMCK 4 colors)
Carrier: volume average particle size 25 μm, magnetization strength 60 emu / g
Lubricant: Solid rod-like zinc stearate Lubricant supply size: width 8 mm x thickness 5 mm x length 330 mm
Lubricating roller: φ12mm brush roller
Hair material: Toray SA-7
Hair length: 3mm
Hair thickness: 6.26d
Flocking density: 15000 / cm ²
Rotation speed: 200 times per minute
The amount of biting into the lubricant supply body and photoconductor of the brush roller: 1 mm
Primary transfer means: φ20mm firing roller
Pressure against intermediate transfer member: 500 gf
<Example 1>: Example of Embodiment 1 A regular reflection type surface state sensor having an incident angle and a light receiving angle of 45 ° was used.

When the lubricant is not applied, the output of the surface condition sensor S1 = 12V (set to S1 = 12V by correcting the light amount of the light emitting element LED)
Output of surface condition sensor S2 = 9V when applying proper amount of lubricant
The threshold of S2 / S1 (threshold for determining that replenishment is necessary) was set to 0.9, and the replenishment detection of the lubricant supply body was performed every 1000 image formations.

  During the experiment of forming 200,000 sheets, the lubricant supply body was replenished in the vicinity of 80000 sheets and 150,000 sheets based on the “replenishment required” signal of the control means. In the replenishment control, the developing sleeve potential was set to −450 V so as not to cause fogging when the photosensitive member was rotated.

A toner image is formed by arranging 30 dots of φ0.5 mm on the photoconductor at intervals of 10 mm in the horizontal direction (photosensitive member width direction) and 10 dots at intervals of 20 mm in the vertical direction (photosensitive member movement direction), and transferring them to the intermediate transfer member. Then, the occurrence rate of “missing” in the output image was examined. It should be noted that the occurrence rate of “missing” α = {number of dots in which “missing” occurred / 300 (total number of dots)} × 100
An image inspection was performed based on a judgment criterion that a “missing” occurrence rate α was 5% or less, and it was satisfactory through the formation of 200000 sheets of images.
<Example 2>: Example of Embodiment 2 An irregular reflection type surface state sensor having an incident angle of 45 ° and a light receiving angle of 0 ° was used.

Output S1 of surface condition sensor when lubricant is not applied S1 = 9V (set to S1 = 9V by light quantity correction of light emitting element LED)
Output S2 of surface condition sensor when applying proper amount of lubricant S2 = 12V
The threshold of S2 / S1 (threshold for determining that replenishment is necessary) was set to 1.2, and the replenishment detection of the lubricant supply body was performed every 1000 image formations.

  During the experiment of forming 200,000 sheets, the lubricant supply body was replenished in the vicinity of 80000 sheets and 150,000 sheets based on the “replenishment required” signal of the control means. In the replenishment control, the developing sleeve potential was set to −450 V so as not to cause fogging when the photosensitive member was rotated.

  A toner image is formed by arranging 30 dots of φ0.5 mm on the photoconductor at intervals of 10 mm in the horizontal direction (photosensitive member width direction) and 10 dots at intervals of 20 mm in the vertical direction (photosensitive member movement direction), and transferring them to the intermediate transfer member. Then, the occurrence rate of “missing” in the output image was examined.

The image inspection was performed based on a judgment criterion that the “missing” occurrence rate α was 5% or less, and it was good through the image formation of 200000 sheets.
<Example 3>: Example of Embodiment 3 A regular reflection type surface state sensor having an incident angle and a light receiving angle of 45 ° was used.

  The initial value V1−V2 = 50V of the difference between the charging potential and the developing bias is set to 50V, the developing bias increasing step ΔV = 10V, and when the increase in the output of the surface state sensor corresponding to ΔV becomes 0.1V or less. The surface condition of was detected.

Output S1 = 12V of the surface condition sensor when the lubricant is not applied (S1 = 12V is set by correcting the light amount of the light emitting element LED)
Output of surface condition sensor S2 = 9V when applying proper amount of lubricant
The threshold of S2 / S1 (threshold for determining that replenishment is necessary) was set to 0.9, and the replenishment detection of the lubricant supply body was performed every 1000 image formations.

  During the experiment of forming 200,000 sheets, the lubricant supply body was replenished in the vicinity of 80000 sheets and 150,000 sheets based on the “replenishment required” signal of the control means.

  A toner image is formed by arranging 30 dots of φ0.5 mm on the photoconductor at intervals of 10 mm in the horizontal direction (photosensitive member width direction) and 10 dots at intervals of 20 mm in the vertical direction (photosensitive member movement direction), and transferring them to the intermediate transfer member. Then, the occurrence rate of “missing” in the output image was examined.

An image inspection was performed based on a judgment criterion that a “missing” occurrence rate α was 5% or less, and it was satisfactory through the formation of 200000 sheets of images.
<Example 4>: Example of Embodiment 4 An irregular reflection type surface state sensor having an incident angle of 45 ° and a light receiving angle of 0 ° was used.

  The initial value V1−V2 = 50V of the difference between the charging potential and the developing bias is set to 50V, the developing bias increasing step ΔV = 10V, and when the output decrease of the surface state sensor corresponding to ΔV becomes 0.1V or less, the photoconductor. The surface condition of was detected.

Output S1 of surface condition sensor when lubricant is not applied S1 = 9V (set to S1 = 9V by light quantity correction of light emitting element LED)
Output S2 of surface condition sensor when applying proper amount of lubricant S2 = 12V
The threshold of S2 / S1 (threshold for determining that replenishment is necessary) was set to 1.2, and the replenishment detection of the lubricant supply body was performed every 1000 image formations.

  During the experiment of forming 200,000 sheets, the lubricant supply body was replenished in the vicinity of 80000 sheets and 150,000 sheets based on the “replenishment required” signal of the control means.

  A toner image is formed by arranging 30 dots of φ0.5 mm on the photoconductor at intervals of 10 mm in the horizontal direction (photosensitive member width direction) and 10 dots at intervals of 20 mm in the vertical direction (photosensitive member movement direction), and transferring them to the intermediate transfer member. Then, the occurrence rate of “missing” in the output image was examined.

  An image inspection was performed based on a judgment criterion that a “missing” occurrence rate α was 5% or less, and it was satisfactory through the formation of 200000 sheets of images.

1 is a diagram showing a color image forming apparatus according to an embodiment of the present invention. 2 is a front view of an image forming unit according to Embodiment 1. FIG. It is a side view of a lubricant application means. 5 is a flowchart of supply control for notifying supply of a lubricant supply body in the first embodiment. 6 is a front view of an image forming unit according to Embodiment 2. FIG. 6 is a flowchart of supply control for notifying supply of a lubricant supply body in a second embodiment. 10 is a flowchart of supply control for notifying supply of a lubricant supply body in a third embodiment. It is a graph which shows development bias. 10 is a flowchart of supply control for notifying supply of a lubricant supply body in a fourth embodiment.

Explanation of symbols

1, 1Y, 1M, 1C, 1K photoconductor 5, 5Y, 5M, 5C, 5K transfer roller (primary transfer means)
7 Intermediate transfer member,
DESCRIPTION OF SYMBOLS 30 Lubricant application roller 31 Lubricant supply body 40 Control means 41 Regular reflection type surface state sensor 42 Diffuse reflection type surface state sensor

Claims (10)

A photoreceptor,
Latent image forming means for forming an electrostatic latent image on the photoreceptor;
Developing means for developing the electrostatic latent image;
An intermediate transfer member;
Primary transfer means for transferring the toner image on the photosensitive member to the intermediate transfer member;
Secondary transfer means for transferring the toner image on the intermediate transfer member to a recording medium;
In an image forming apparatus having a lubricant application means for applying a lubricant to the surface of the photoreceptor,
A lubricant supplier mounted on the lubricant application means;
A surface condition sensor for inspecting the surface condition of the photoreceptor;
Control means for detecting the replenishment time of the lubricant,
The surface condition sensor comprises a regular reflection type surface condition sensor comprising a light emitting element that projects light onto the photoconductor and a light receiving element that detects light specularly reflected by the photoconductor,
The control means rotates the photoconductor for a predetermined time while applying the lubricant and the received light amount L1 of the regular reflection type surface state sensor when the photoconductor is rotated for a predetermined time without applying the lubricant. When the ratio L2 / L1 of the specular reflection type surface state sensor when L2 / L1 is equal to or greater than a predetermined value, a signal that prompts replenishment of the lubricant supply body is output. Image forming apparatus. A photoreceptor,
Latent image forming means for forming an electrostatic latent image on the photoreceptor;
Developing means for developing the electrostatic latent image;
An intermediate transfer member;
Primary transfer means for transferring the toner image on the photosensitive member to the intermediate transfer member;
Secondary transfer means for transferring the toner image on the intermediate transfer member to a recording medium;
In an image forming apparatus having a lubricant application means for applying a lubricant to the surface of the photoreceptor,
A lubricant supplier mounted on the lubricant application means;
A surface condition sensor for inspecting the surface condition of the photoreceptor;
Control means for detecting the replenishment time of the lubricant,
The surface condition sensor comprises a diffuse reflection type surface condition sensor comprising a light emitting element that projects light onto the photoconductor and a light receiving element that detects light irregularly reflected by the photoconductor, and
The control means includes a light receiving amount L1 of the light receiving element when the photoconductor is rotated for a predetermined time without applying the lubricant, and when the photoconductor is rotated for a predetermined time while applying the lubricant. An image forming apparatus that outputs a signal that prompts replenishment of the lubricant supply body when L2 / L1 of the ratio of the light receiving element to the light receiving amount L2 becomes equal to or less than a predetermined value. A photoreceptor,
Latent image forming means for forming an electrostatic latent image on the photoreceptor;
Developing means for developing the electrostatic latent image;
An intermediate transfer member;
Primary transfer means for transferring the toner image on the photosensitive member to the intermediate transfer member;
Secondary transfer means for transferring the toner image on the intermediate transfer member to a recording medium;
In an image forming apparatus having a lubricant application means for applying a lubricant to the surface of the photoreceptor,
A lubricant supplier mounted on the lubricant application means;
A surface condition sensor for inspecting the surface condition of the photoreceptor;
Control means for detecting the replenishment time of the lubricant;
Developing bias adjusting means for adjusting the developing bias in the developing means,
The developing bias adjusting means sets a state in which there is substantially no fog on the photosensitive member, and in this state, the surface state sensor detects the surface state of the photosensitive member, and the control means includes the surface state sensor. An image forming apparatus that detects the replenishment timing of the lubricant supply body based on the detection result. The surface condition sensor comprises a regular reflection type surface condition sensor comprising a light emitting element that projects light onto the photoconductor and a light receiving element that detects light specularly reflected by the photoconductor,
The development bias adjusting means changes the development bias in steps, and uses the received light amount of the light receiving element when a change in the received light amount of the light receiving element per step becomes a predetermined value or less as a detection value. The image forming apparatus according to claim 3, wherein the control unit outputs a signal that prompts replenishment of the lubricant supply body when a predetermined amount or more is increased from a reference value. The surface condition sensor comprises a diffuse reflection type surface condition sensor comprising a light emitting element that projects light onto the photoconductor and a light receiving element that detects light irregularly reflected by the photoconductor,
The development bias adjusting means changes the development bias in steps, and uses the received light amount of the light receiving element when a change in the received light amount of the light receiving element per step becomes a predetermined value or less as a detection value. The image forming apparatus according to claim 3, wherein the control unit outputs a signal that prompts replenishment of the lubricant supply body when a predetermined amount or more is decreased from a reference value. The image forming apparatus according to claim 1, wherein the developing unit performs development using a polymerized toner. A plurality of image forming portions each having the photosensitive member, the latent image forming unit, the developing unit, and the primary transfer unit are provided, and a color toner image in which a plurality of toner images are superimposed is formed on the intermediate transfer member. The image forming apparatus according to any one of claims 1 to 6. The image forming apparatus according to claim 1, wherein the lubricant is made of a metal stearate. The image forming apparatus according to claim 1, wherein the surface state sensor is used as a density sensor that detects a density of a toner image. The image forming apparatus according to claim 1, wherein the control unit corrects a detection error by controlling a light emission amount of a light source of the surface state sensor.

Images