JP5158461B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, or a printer that forms a visible image such as a toner image on its front surface while an endless belt member is moved endlessly.

  In this type of image forming apparatus, when a belt member such as an intermediate transfer belt that moves endlessly while being stretched by a plurality of stretch members is greatly undulated, the image quality is deteriorated. For example, in the vicinity of a primary transfer nip for transferring a toner image from an image carrier such as a photoconductor to an intermediate transfer belt, or a secondary transfer nip for secondary transfer from an intermediate transfer belt to a recording sheet. Suppose that the belt wavy. Then, the vibration due to the undulation propagates to the transfer nip, and vertical stripe-like density unevenness occurs in the toner image. Further, for example, in an image forming apparatus of a type in which the amount of toner attached to a reference patch image formed on an intermediate transfer belt is detected by a reflective photosensor, and image forming conditions such as toner density and developing bias are adjusted based on the detection result. Suppose the belt wavy. Then, the vibration due to the undulation propagates to the detected portion of the reflection type photosensor on the intermediate transfer belt, and the detection accuracy of the toner adhesion amount with respect to the reference patch image is deteriorated. This causes poor adjustment of image forming conditions and deteriorates image quality.

  Therefore, in the image forming apparatus described in Patent Document 1, the back plate is fixed to the inner side of the loop of the intermediate transfer belt, and is rubbed against the back surface of the belt member that moves endlessly, thereby suppressing the undulation of the belt member. It has become.

JP 2001-5247 A

  However, the present inventors have found through experiments that the image quality deterioration due to the vibration of the intermediate transfer belt cannot be sufficiently suppressed only by rubbing a rubbing member such as a back plate on the back surface of the intermediate transfer belt. It was. Specifically, in general, only the both ends in the belt width direction of the rubbing member such as the back plate that slides on the back surface of the intermediate transfer belt is fixed to the belt unit side plate in the same manner as the stretching roller for stretching the belt. The central part is in a state of being bridged between the side plates. Such a rubbing member has its original shape when the strength of its waist exceeds the frictional force with the belt after its center is slightly bent in the belt moving direction by friction with the belt. Repeat the action of returning. By repeating this, the central portion of the rubbing member that rubs against the intermediate transfer belt vibrates in the belt moving direction. Then, this vibration propagates to a transfer nip of the intermediate transfer belt and a portion to be detected by a reflection type photo sensor. In recent years when image quality is improved, there is a risk that it is difficult to obtain a desired image quality even if slight image quality degradation occurs due to such vibration.

  The present invention has been made in view of the above background, and an object of the present invention is to provide an image forming apparatus capable of suppressing deterioration in image quality caused by vibration of a rubbing member such as a back plate as compared with the prior art. That is.

In order to achieve the above object, the invention of claim 1 is directed to an endless belt member that is endlessly moved while being stretched by a plurality of tension members, and a visible image is formed on the front surface of the belt member. In an image forming apparatus comprising: a visible image forming unit; a rubbing member that rubs against a back surface of the belt member that moves endlessly; and a support that supports the rubbing member at a plurality of positions in the belt member width direction. Of the entire region of the rubbing member in the width direction of the belt member, the non-fixed region is fixed to the non-fixed region as a deflection inhibiting means for inhibiting the non-fixed region that is not fixed to the support in the rubbing direction. A reinforcing member that reinforces the region is provided , and the reinforcing member is made of a material having a specific gravity higher than that of the rubbing member .
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the rubbing member is rubbed against the back surface of a horizontal stretch region extending in the horizontal direction out of the entire circumferential region of the belt member. It is characterized by being arranged as described above.
The invention according to claim 3 is the image forming apparatus according to claim 2, wherein the weight of the region where the reinforcing member is fixed out of the entire region of the rubbing member in the belt member width direction, and the reinforcement A value obtained by dividing the sum of the weight of the members by the weight of the region where the reinforcing member is not fixed in the entire region is 1.8 or more.
According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, among the non-fixed areas of the rubbing member, the two rubbing members adjacent to each other are fixed. The central region is less likely to bend in the rubbing direction than the fixed region, or the deflection of the central region in the rubbing direction is inhibited by the reinforcing member.
According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the sliding member is made of a fluororesin or a polyacetal resin.
According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, as the rubbing member, at least a rubbing surface of the base with the belt member has a smaller coefficient of friction than the base. A material provided with a surface layer made of a material is used.
According to a seventh aspect of the invention, in the image forming apparatus according to any one of the first to sixth aspects, the rubbing member having a plurality of raised portions on a contact surface with the belt member is used. To do.
According to an eighth aspect of the present invention, in the image forming apparatus according to any one of the first to seventh aspects, an optical sensor that detects the amount of light reflection on the front surface of the belt member and a predetermined result based on the detection result. Control means for carrying out the control of the above, and the rubbing member is disposed so as to be rubbed against the belt back surface area on the back surface of the light reflection amount detection portion by the optical sensor on the front surface. It is a feature.
According to a ninth aspect of the present invention, in the image forming apparatus according to any one of the first to seventh aspects, a nip forming body that forms a transfer nip in contact with the front surface of the belt member is provided, and the rubbing is performed. The member is disposed in the vicinity of the transfer nip.
According to a tenth aspect of the present invention, in the image forming apparatus according to any one of the first to ninth aspects, the reinforcing member is fixed only at a center of the non-fixed region in the belt member width direction. is there.
According to an eleventh aspect of the present invention, in the image forming apparatus according to any one of the first to tenth aspects, the reinforcing member is screwed and fixed to the non-fixed region.
According to a twelfth aspect of the present invention, in the image forming apparatus according to any one of the first to eleventh aspects, as the visible image forming means, a visible image formed on the surface of the image carrier is used as the belt member from the surface. A transfer nip for transferring the intermediate image transferred to the front surface to a recording sheet by using an intermediate transfer belt having an intermediate transfer surface and contacting the front surface And a rubbing member provided in the vicinity of the transfer nip.

In these inventions, of the entire region of the rubbing member in the width direction of the belt member, since the movement of the fixed region fixed to the support is restricted by the support, even if the rubbing with the belt member occurs It does not bend in the rubbing direction. Therefore, it does not vibrate with sliding. On the other hand, the non-fixed area that is not fixed to the support body bends in the rubbing direction with the friction with the belt member. For this reason, it vibrates in the rubbing direction with the rubbing with the belt member.
Therefore, by inhibiting the reinforcing member as inhibitors unit deflection deflection of the non-fixed region of the rubbing member become distorted in accordance with the friction with the belts member, rubbing member associated with the friction with the belt member Reduce vibration. As a result, image quality deterioration due to vibration of the rubbing member can be suppressed as compared with the conventional case.

Hereinafter, an image forming apparatus according to the present invention, an electrophotographic printer (hereinafter, simply referred to as a printer) Before describing implementation form of, for printer according to the reference embodiment that can help in understanding the present invention Explain .
First, the basic configuration of the printer will be described. FIG. 1 is a schematic configuration diagram showing the printer from the front. In the figure, the printer includes four process cartridges 6Y, 6M, 6C, and 6K for forming yellow, magenta, cyan, and black (hereinafter referred to as Y, M, C, and K) toner images. . These use Y, M, C, and K toners of different colors as the image forming material, but the other configurations are the same and are replaced when the lifetime is reached. Taking a process cartridge 6Y for generating a Y toner image as an example, as shown in FIG. 2, a drum-shaped photosensitive member 1Y as an image carrier, a drum cleaning device 2Y, a charge eliminating device 3Y, a charging device 4Y, and a developing device 5Y. Etc.

  In the photoreceptor 1Y, a surface layer of an organic semiconductor, which is a photoconductive substance, is coated on an aluminum cylinder. An amorphous silicon surface layer may be coated. Further, it may be a belt shape instead of a drum shape.

  The charging device 4Y uniformly charges the surface of the photoreceptor 1Y that is rotated clockwise in the drawing by a driving unit (not shown). The uniformly charged surface of the photoreceptor 1 </ b> Y is exposed and scanned by the laser beam L to carry a Y electrostatic latent image. The Y electrostatic latent image is developed into a Y toner image by the developing device 5Y using Y toner. Then, primary transfer is performed on a first intermediate transfer belt 8 described later.

  The drum cleaning device 2Y removes the toner remaining on the surface of the photoreceptor 1Y after the intermediate transfer process. Further, the charge removal device 3Y removes the residual charge of the photoreceptor 1Y after cleaning. By this charge removal, the surface of the photoreceptor 1Y is initialized and prepared for the next image formation. In the other process cartridges 6M, C, and K, M, C, and K toner images are similarly formed on the photoreceptors 1M, C, and K, and are primary-transferred superimposed on the first intermediate transfer belt 8. The The developing device (such as 5Y) may use a two-component developer containing toner and a magnetic carrier, or may use only toner powder.

  An optical writing unit 7 is disposed below the process cartridges 6Y, 6M, 6C, and 6K in the drawing. An image data processing device (not shown) generates an exposure scanning control signal based on an image information signal sent from a personal computer or the like and sends it to the optical writing unit 7. The optical writing unit 7 serving as a latent image forming unit irradiates the photoconductors 1Y, 1M, 1C, and 1K in the process cartridges 6Y, 6M, 6C, and 6K with a laser beam L emitted based on the exposure scanning control signal. Electrostatic latent images for Y, M, C, and K are formed on the photoreceptors 1Y, 1M, 1C, and 1K exposed by this irradiation. The optical writing unit 7 irradiates the photosensitive member through a plurality of optical lenses and mirrors while scanning a laser beam (L) emitted from a light source with a polygon mirror rotated by a motor. Instead of the optical writing unit 7 having such a configuration, one that irradiates LED light from the LED array may be employed.

  The electrostatic latent images for Y, M, C, and K formed on the photoreceptors 1Y, 1M, 1C, and 1K are converted into Y, M, C, and K by developing devices in the process cartridges 6Y, 6M, 6C, and 6K, respectively. After being developed into a K toner image, a transfer process by a transfer device is performed. This transfer apparatus has a first transfer unit 15 and a second transfer unit 24.

  A first paper cassette 25 and a second paper cassette 26 are disposed below the optical writing unit 7 so as to overlap in the vertical direction. The first paper cassette 25 and the second paper cassette 26 accommodate a recording paper bundle in which a plurality of recording papers P as recording bodies are stacked.

  On the right side of the first paper cassette 25 and the second paper cassette 26 in the drawing, paper feeding means is disposed. The sheet feeding means includes a first sheet feeding roller 28, a second sheet feeding roller 29, a registration roller pair 31, a sheet feeding path 32, and the like. The first paper feed roller 28 and the second paper feed roller 29 are in contact with the uppermost recording paper P of the recording paper bundle accommodated in the first paper cassette 25 and the second paper cassette 26. Then, the uppermost recording paper P is sent out toward the paper feed path 32 by being driven to rotate by a driving means (not shown). The fed recording paper P is sandwiched between rollers of a registration roller pair 31 disposed near the end of the paper feed path 32.

  The registration roller pair 31 rotates both rollers in the forward direction so as to sandwich the recording paper P, but once the recording paper P is sandwiched, the rotation of both rollers is temporarily stopped. Then, rotation of both rollers is resumed at an appropriate timing, and the recording paper P is sent out to a secondary transfer nip described later.

  The first transfer unit 15 of the transfer device is disposed above the four process cartridges 6Y, 6M, 6C, and 6K that are arranged in the horizontal direction. The first intermediate transfer belt 8, which is a belt member, four primary transfer rollers 9Y, 9M, 9C, and 9K, the first cleaning device 10, the drive roller 11, the secondary transfer backup roller 12, the tension roller 13, and the nip upstream roller 14 and so on. The endless first intermediate transfer belt 8 is endlessly moved counterclockwise in the figure by the rotational drive of the drive roller 11 while being stretched around these rollers.

  The four primary transfer rollers 9Y, 9M, 9C, and 9K sandwich the first intermediate transfer belt 8 that is moved endlessly in this manner between the photoreceptors 1Y, 1M, 1C, and 1K. By this sandwiching, primary transfer nips for Y, M, C, and K where the front surface of the first intermediate transfer belt 8 and the photoreceptors 1Y, 1M, 1C, and 1K abut are formed. A primary transfer bias having a polarity opposite to that of toner (for example, plus) is applied to the primary transfer rollers 9Y, 9M, 9C, and 9K by a power source (not shown). By this application, a primary transfer electric field for electrostatically moving the toner image on the photoreceptor toward the first intermediate transfer belt 8 is formed in the primary transfer nips for Y, M, C, and K, respectively. . Instead of the four primary transfer rollers 9Y, 9M, 9C, and 9K of the bias application system, a charger system that discharges from the electrodes may be used.

  The first intermediate transfer belt 8 has a surface smoothness made of a base layer made of fluororesin, PVDF (Poly Vunyli Dene Chloride), polyimide resin, etc., and a fluororesin coated on the front side. It has a multilayer structure consisting of a coating layer excellent in Then, the Y, M, C, and K primary transfer nips are sequentially passed along with the endless movement. At each primary transfer nip, the Y, M, C, and K toner images on the photoreceptors 1Y, 1M, 1C, and 1K are superimposed on the first intermediate transfer belt 8 by the action of the nip pressure and the primary transfer electric field, and are primary. Transcribed. As a result, a four-color superimposed toner image (hereinafter referred to as a four-color toner image) is formed on the first intermediate transfer belt 8.

  The secondary transfer backup roller 12 that stretches the first intermediate transfer belt 8 is disposed at a position to bite into a second intermediate transfer belt 16 described later. By such a biting arrangement, a secondary transfer nip is formed in which the front surface of the first intermediate transfer belt 8 and the front surface of the second intermediate transfer belt 16 that is a belt member abut each other.

  The visible four-color toner image formed on the first intermediate transfer belt 8 enters the secondary transfer nip as the first intermediate transfer belt 8 moves endlessly. Then, secondary transfer is performed on the second intermediate transfer belt 16 or the recording paper P at the secondary transfer nip.

  Transfer residual toner that has not been secondarily transferred to the second intermediate transfer belt 16 or the recording paper P adheres to the front surface of the first intermediate transfer belt 8 after passing through the secondary transfer nip. This is cleaned by the first cleaning device 10. Specifically, after passing through the secondary transfer nip, the first intermediate transfer belt 8 is arranged so as to abut on the outer surface (front surface) side of the loop, and the loop. It is sandwiched between tension rollers 13 arranged on the inner surface side. Then, the transfer residual toner on the front surface is mechanically or electrostatically collected by the first cleaning device 10 and cleaned.

  The second transfer unit 24 of the transfer device is disposed on the right side of the first transfer unit 15 in the drawing, and includes an endless second intermediate transfer belt 16, a second cleaning device 18, a transfer charger 23, and the like. Yes. A secondary transfer roller 17, a nip expansion roller 19, a tension roller 20, a drive roller 21 and the like are also provided. The second intermediate transfer belt 16 is endlessly moved clockwise in the drawing by the rotational driving of the driving roller 21 while being stretched around these four rollers.

  To the secondary transfer roller 17 of the second transfer unit 24, a secondary transfer bias having a polarity (for example, plus polarity) opposite to that of the toner is applied by a power source (not shown). By this application, a secondary transfer electric field is formed in the secondary transfer nip to electrostatically move the four-color toner image on the first intermediate transfer belt 8 toward the second intermediate transfer belt 16.

  The registration roller pair 31 of the paper feeding means feeds the recording paper P sandwiched between the rollers at a timing at which the recording paper P can be brought into close contact with the four-color toner image on the first intermediate transfer belt 8 in the secondary transfer nip. However, when the four-color toner image is the first toner image to be transferred to the first surface of the recording paper P (the surface facing upward on the stack unit 40 described later), the recording paper P is not sent out. . Therefore, in this case, the first toner image on the first intermediate transfer belt 8 is secondarily transferred to the front surface of the second intermediate transfer belt 16 in the secondary transfer nip. On the other hand, when the four-color toner image on the first intermediate transfer belt 8 is the second toner image to be transferred to the second surface of the recording paper P (the surface facing downward on the stack unit 40), The registration roller pair 31 sends out the recording paper P at a timing that can be synchronized with the second toner image. Therefore, in this case, the second toner image is secondarily transferred to the second surface of the recording paper P at the secondary transfer nip, and becomes a full-color image combined with the white color of the recording paper P. At this time, the first toner image previously secondarily transferred onto the second intermediate transfer belt 16 is brought into close contact with the first surface of the recording paper P at the secondary transfer nip, and the belt is then applied by the action of the secondary transfer bias. Drawn to the side. It is in close contact with the first surface of the recording paper P, but is not tertiary transferred there.

  At the outlet of the secondary transfer nip, the first intermediate transfer belt 8 is separated from the recording paper P, and the recording paper P is held and conveyed only on the surface of the second intermediate transfer belt 16. Then, along with the endless movement of the second intermediate transfer belt 16, it is sent to a tertiary transfer section described later.

  In the tertiary transfer portion of the second transfer unit 24, the transfer charger 23 is opposed to a place where the second intermediate transfer belt 16 is wound around the drive roller 21 with a predetermined gap. The recording paper P on the second intermediate transfer belt 16 is given a charge of the opposite polarity (for example, positive polarity) to the toner on the second surface side by the transfer charger 23. By applying this charge, the first toner image sandwiched between the first surface of the recording paper P and the second intermediate transfer belt 16 is thirdarily transferred to the first surface of the recording paper P to form a full color image. . As a member to which the primary transfer bias and the secondary transfer bias are applied, members having other shapes such as a brush may be used instead of the rollers (9, 17). Further, instead of the electrostatic transfer method in which a transfer bias is applied to the member, a non-contact discharge method may be employed.

  The recording paper P with the toner images transferred on both sides is separated from the second intermediate transfer belt 16 and sent to a fixing device 35 described later.

  After passing through the tertiary transfer portion, the second intermediate transfer belt 16 is sandwiched between the drive roller 21 and the second cleaning device 18, and the transfer residual toner on the surface is mechanically or electrostatically cleaned. . If the second cleaning device 18 is always in contact with the second intermediate transfer belt 16, the first toner image secondarily transferred onto the second intermediate transfer belt 16 is also cleaned. Therefore, the second cleaning device 18 is brought into contact with and separated from the second intermediate transfer belt 16 by being swung in the direction of the arrow in the figure by a swing mechanism (not shown). At least while the first toner image passes through the cleaning position, the first toner image is separated from the second intermediate transfer belt 16 to avoid cleaning the first toner image.

  Above the second transfer unit 24 in the figure, a fixing device 35 as a fixing means is disposed. The fixing device 35 has two fixing rollers 35a and 35b that contact each other while rotating in the forward direction to form a fixing nip. Each of the fixing rollers 35a and 35b has heating means such as a halogen lamp (not shown), and heats the recording paper P sandwiched between the fixing nips from both sides. By this heating, the full-color images respectively formed on both sides of the recording paper P are fixed on the recording paper P. After fixing, the recording paper P is reversed along the reversing guide member 36, and then discharged to the outside through the paper discharge roller pair 37. And it is stacked on the stack part 40 formed on the upper surface of the housing of the printer body.

  The surface temperatures of the two fixing rollers 35a and 35b are respectively detected by temperature detection means (not shown). This temperature detection means transmits the detection result to a fixing temperature control circuit (not shown). The fixing temperature control circuit performs ON / OFF control of the power supply to the heat generating means of the fixing rollers 35a and b based on the detection result of the surface temperature sent from the temperature detecting means, and the surfaces of the fixing rollers 35a and 35b. Maintain the temperature within a certain range (target range).

  As described above, the printer applies a four-color toner image, which is a precursor of a full-color image, to both sides of the recording paper P before being sent to the fixing device 35 that performs the fixing process of the full-color image by the transfer device. Transcript. As a result, one-pass image formation can be performed on both sides of the recording paper P.

  The first toner image is formed prior to the second toner image. Then, after secondary transfer from the first intermediate transfer belt 8 to the second intermediate transfer belt 16 at the secondary transfer nip, it is tertiary transferred onto the first surface of the recording paper at the tertiary transfer portion. The first surface is a surface facing upward in the stack portion 40. Therefore, the recording sheets P stacked on the stack unit 40 are sequentially stacked with the first toner image formed in the front direction facing up and the second toner image formed thereafter facing up. Go. In this printer, in order to align the page numbers of the recording sheets P stacked in this order in order from the smallest, the first toner is the first one with the larger page number for the images of two consecutive page numbers, odd and even. Form as an image. For example, the image on the second page is formed as the first toner image prior to the image on the first page. As a result, even if documents of several pages are output continuously, the page numbers can be aligned in order from the bottom in the stack unit 40. However, when executing the single-sided printing mode in which an image is formed only on the second surface of the recording paper P, images are formed in order from the page with the smallest page number, and each image is secondarily transferred onto the second surface of the recording paper P. . Thus, even in the single-sided printing mode, the page numbers can be aligned in order from the bottom in the stack unit 40.

  In the four photoconductors 1Y, 1M, 1C, and 1K, each color toner image formed for the second toner image is formed as a non-mirror image (hereinafter referred to as a normal image). This is because the formed toner images of the respective colors change in the order of mirror image and normal image in the process of reaching the recording paper P through two transfer steps of primary transfer and secondary transfer. By forming a normal image on each photoconductor, a normal image is formed on the second surface of the recording paper P. On the other hand, since the toner images of the respective colors formed for the first toner image are subjected to the third transfer, the transfer process is increased once more than the second toner image. Therefore, it is formed as a mirror image on each photoconductor. As a result, a normal image, a mirror image, and a normal image are changed in the order of each transfer, and a normal image can be formed on the first surface of the recording paper P.

  A bottle container 54 is disposed above the first transfer unit 15 in the drawing. In the bottle container 54, toner bottles BY, BM, BC, and BK containing toner to be supplied to the developing devices in the process cartridges (6Y, M, C, and K) are stored.

  FIG. 3 is an enlarged configuration diagram showing the four process cartridges 6Y, 6M, 6C, and 6K and the first transfer unit 15 of the transfer device. A backing member 110 is disposed inside the loop of the first intermediate transfer belt 8 of the first transfer unit 15 and in the vicinity of the drive roller 11. The backing member 110 is fixed to the inner side of the belt loop so as to slidably rub against the entire back surface of the first intermediate transfer belt 8 immediately after passing the stretched position by the driving roller 11. .

  In the printer having the above basic configuration, the combination of the process units 6Y, 6M, 6K, the optical writing unit, the transfer device, and the like is a combination of the first intermediate transfer belt 8 and the second intermediate transfer belt as belt members. It functions as a visible image forming means for forming a toner image that is a visible image on the front surface of 16.

  An optical sensor unit 120 is disposed outside the loop of the first intermediate transfer belt 8 so as to face the front surface of the first intermediate transfer belt 8 with a predetermined gap. Of the entire region of the front surface of the first intermediate transfer belt 8, the region backed by the backing member 110 is a region to be detected by the optical sensor unit 120. Specifically, the optical sensor unit 120 has a plurality of light emitting elements (not shown) and a plurality of light receiving elements (not shown), and the light emitted from the light emitting elements is the front surface of the first intermediate transfer belt 8. Irradiate the detected area, which is a backing area by the backing member 110 in FIG. The light reflected by the detection region is received by the light receiving element of the optical sensor unit 120, and the light receiving element outputs a voltage having a value corresponding to the amount of received light to a control unit (not shown). The amount of reflected light in the detection area of the first intermediate transfer belt 8 has a correlation with the toner adhesion amount per unit area in the detection area. Therefore, the amount of light received by the light receiving element represents the toner adhesion amount in the detection area.

  The printer performs a process called a process control process immediately after a power switch (not shown) is turned on, immediately after rising from the energy saving mode, and whenever a predetermined number of printouts are performed. The energy saving mode is a state in which the power supply to the heating means of the fixing device (35) is stopped when an image formation command such as a print command signal sent from a personal computer (not shown) is not given for a predetermined time or more. This is a mode for waiting for an image formation command.

  In the process control process, first, the optical sensor unit 120 is calibrated. Specifically, the output voltage value from the light receiving element in a state where light emission by the light emitting element of the optical sensor unit 120 is turned off is detected as Vsg. A ROM of a control unit (not shown) stores in advance Vs0 that is a saturation output voltage value from the light receiving element when a high-density black solid toner image is detected. The light emission amount of the light emitting element is adjusted so that a value obtained by subtracting Vs0 from Vsg described above becomes a predetermined value (for example, 1.5 V). By this adjustment, the optical sensor unit 120 is calibrated.

  When the calibration of the sensor is completed, the plotter startup operation is performed next. In this plotter start-up operation, predetermined drive bias, development bias, and transfer bias are started after each drive motor is started.

  When the plotter startup operation is performed, gradation pattern detection processing is performed next. In this gradation pattern detection process, first, a K gradation pattern image composed of 17 reference toner images having different toner adhesion amounts is formed on the Y photoconductor 1Y, and then the first intermediate transfer belt 8 is formed. Is transcribed. At this time, the toner adhesion amount with respect to each reference toner image in the K gradation pattern image is adjusted by the difference in development potential. The developing potential is a potential difference between the electrostatic latent image on the photoreceptor 1Y and the surface potential (developing bias VB) of the developing roller of the developing device. The development potential is adjusted by the difference in optical writing intensity with respect to the photoreceptor 1Y. The electrostatic latent image for each reference toner image in the K gradation pattern image is detected by a potential sensor (not shown) prior to development, and the detection result is output to the control unit. Further, the optical sensor unit 120 detects the toner adhesion amount per unit area for each reference toner image in the K gradation pattern image. The control unit calculates the development potential when developing each reference toner image based on the output signal from the potential sensor and the development bias VB. Further, based on the output signal from the optical sensor unit 120, the toner adhesion amount for each reference toner image is calculated. Then, an approximate linear equation indicating the relationship between the toner adhesion amount for each reference toner image and the development potential corresponding to each reference toner image is calculated. This approximate linear expression indicates the image forming ability of the visible image forming means. Therefore, the control unit measures the image forming performance by performing the gradation pattern detection process.

  After obtaining the above approximate linear equation, the control unit specifies the optimum development potential for obtaining the target toner adhesion amount, and then based on the data table stored in advance in the ROM. The photosensitive belt uniform charging potential VL, the developing bias VB, and the optical writing intensity VD that match the developing potential are specified. And a specific result is memorize | stored in NVRAM which is a non-volatile information storage means. Such gradation pattern detection processing is also performed for M, C, and K.

  After performing the process control process as described above, when performing a print job based on the image information signal, the photosensitive member uniform charging potential VL, the developing bias VB, and the optical writing intensity VD for each color are respectively set. It is set to the same value as the data stored in the NVRAM during the process control process. This suppresses fluctuations in image density and gradation reproducibility caused by fluctuations in the environment (temperature and humidity) and toner characteristics (fluidity, bulk density, etc.), and ensures high-quality images over a long period of time. Can be formed.

  In the case of performing the process control processing as in this printer, if the detected area of the first intermediate transfer belt 8 undulates along with the endless movement of the belt, the amount of light received by the light receiving element changes due to the undulation. . As a result, the detection accuracy of the toner adhesion amount with respect to each reference toner image is deteriorated, and it becomes difficult to accurately detect the image forming performance of the visible image forming unit. Therefore, in the present printer, as described above, the detection area is tensioned by sliding the backing member 110 on the back side of the detection area of the first intermediate transfer belt 8 so that the detection area is corrugated. It is suppressed.

  However, the present inventors, through experiments, have deteriorated image quality due to deterioration in detection accuracy of the toner adhesion amount only by rubbing the backing member 110 that is a rubbing member on the back side of the detected region of the first intermediate transfer belt 8. It was found that it cannot be suppressed sufficiently. Specifically, the backing member 110 that rubs against the back surface of the first intermediate transfer belt 8 may vibrate as the first intermediate transfer belt 8 moves endlessly, and this vibration is detected by the intermediate transfer belt 8. Propagation to the area may deteriorate the detection accuracy of the toner adhesion amount.

  FIG. 4 is an enlarged plan view showing the conventional backing member 110 from the upper side in the vertical direction together with the unit front side plate 130 and the unit rear side plate 131 of the first transfer unit (15). The unit front plate 130 and the unit rear plate 131 in the figure are arranged at a predetermined distance in the belt width direction of the first intermediate transfer belt (8) (not shown). Various rollers for stretching the first intermediate transfer belt (8) are rotatably supported at the ends in the roller axial direction. Both ends of the backing member 110 in the belt width direction are fitted into notches provided in the unit front side plate 130 and the unit rear side plate 131, respectively. By this fitting, the backing member 110 is fixed to the unit front plate 130 and the unit rear plate 131 at both ends in the belt width direction. The span of the backing member 110 between the unit front side plate 130 and the unit rear side plate 131 has a length in the belt width direction larger than the width of the first intermediate transfer belt (8). It contacts the belt (8) over the entire width direction.

  When the first intermediate transfer belt (8) (not shown) moves endlessly, the contact portion of the belt with the backing member 110 moves in the direction of the arrow X1 as shown in FIG. The backing member 110 that rubs against the back surface of the first intermediate transfer belt (8) is pulled in the direction of the arrow X1 by friction with the belt, and the central portion in the belt width direction is bent in the direction of the arrow X1. The backing member 110 bent in this way exhibits a force (hereinafter referred to as a restoring force) for restoring the bending in the arrow X1 direction by the strength of its own waist. When this restoring force exceeds the frictional force between the backing member 110 and the first intermediate transfer belt (8), the center portion of the backing member 110 is deformed in the direction opposite to the bending direction as indicated by an arrow X2 in the figure. The bending is restored, and further, it is slightly bent in the direction of the arrow X2 from the original state. Thereafter, it is bent again in the direction of the arrow X1 along with the friction with the belt. By repeating such bending and restoration, the backing member 110, particularly the central portion thereof, vibrates in the direction of the arrow X1-X2. Such vibration of the backing member 110 causes a problem of increasing noise in addition to causing deterioration of image quality.

Next, a characteristic configuration of the printer will be described.
FIG. 6 is an enlarged plan view showing the backing member 110 in the printer together with the unit front side plate 130 and the unit rear side plate 131 of the first transfer unit (15) from the upper side in the vertical direction. Both ends of the backing member 110 in the belt width direction are fixed portions 110b that are thinner than the main body portion 110a on the center side, and are fitted in through openings (not shown) provided in the unit front side plate 130 and the unit rear side plate 131. I'm hurt. By this fitting, the backing member 110 is fixed to the unit front side plate 130 and the unit rear side plate 131 at the fixing portions 110b which are fixing regions at both ends in the belt width direction. The main body 110a of the backing member 110 has a length in the belt width direction that is greater than the width of the first intermediate transfer belt (8), and is located in the entire width direction of the first intermediate transfer belt (8). Touch across.

  Of the entire region in the belt width direction of the backing member 110, the main body 110a, which is a non-fixed region that is not fixed to the unit front plate 130 or the unit rear plate 131 as a support, is attached to the unit front plate 130 or the unit rear plate 131. It is thicker than the fixed part 110b which is a fixed region to be fixed. Thereby, the main-body part 110a is hard to bend in the rubbing direction compared with the fixing | fixed part 110b. In such a configuration, the backing member 110 accompanying the rubbing with the first intermediate transfer belt (8) compared to the conventional case where the ease of bending in the rubbing direction is the same in the entire region of the backing member 110 in the belt width direction. Reduce the amount of bending (especially in the center). Thus, by suppressing the vibration of the backing member 110 due to the rubbing with the first intermediate transfer belt (8), it is possible to suppress image quality degradation caused by the vibration as compared with the conventional case.

  In addition, although the example which made the main-body part 110a harder to bend in the rubbing direction than the fixing | fixed part 110b by making the main-body part 110a thicker than the fixing | fixed part 110b was demonstrated, the main-body part 110a is fixed to the fixing | fixed part 110b by another method. Also, it may be difficult to bend. For example, even if the main body part 110a and the fixing part 110b have the same thickness, the main body part 110a is made of a material having higher rigidity than the fixing part 110b, so that the main body part 110a is rubbed more than the fixing part 110b. It is possible to make it difficult to bend in the direction.

Next, a description will be given of a printer according to this embodiment of the present invention. Note that the configuration of the printer according to the implementation mode, unless noted below, is similar to the printer according to the reference embodiment.

  FIG. 7 is an enlarged exploded perspective view showing the backing member 110 and the surrounding configuration in the printer. In the figure, a reinforcing member 111 is fixed by screws at the center in the belt width direction of the main body 110a of the backing member 110. A main body accompanying sliding with the first intermediate transfer belt 8 by reinforcing the main body portion 110a by fixing the reinforcing member 111 to the main body portion 110a which is a non-fixed region that is not fixed to the unit front side plate 130 or the unit rear side plate 131. The bending of the portion 110a in the rubbing direction is hindered. As a result, as shown in FIG. 8, it is possible to suppress the vibration of the main body 110a of the backing member 110 and to suppress the image quality deterioration due to the vibration as compared with the conventional case.

In this printer, similarly to the configuration of the printer according to the reference embodiment previously shown in FIG. 3, the backing member 110 is horizontally stretched extending in the horizontal direction in the entire circumferential region of the first intermediate transfer belt 8. It arrange | positions so that it may rub against the back surface of an area | region. In such a configuration, gravity acts on the backing member 110 in a surface direction orthogonal to the rubbing direction with the first intermediate transfer belt 8. Then, since the stress due to its own weight or the weight of the reinforcing member 111 acts on the main body part 110a of the backing member 110 shown in FIG. 7 in the surface direction perpendicular to the rubbing direction, The reinforcing member 111 is not bent in the rubbing direction with the belt due to the weight of the reinforcing member 111. Under such a configuration, in this printer, the reinforcing member 111 is made of a material having a specific gravity higher than that of the backing member 110. More specifically, the backing member 110 is made of a plastic material, while the reinforcing member 111 is made of a metal material having a specific gravity higher than that of plastic. By using such a reinforcing member 111, a large stress is applied to the reinforcing member 111 in a direction orthogonal to the rubbing direction with the belt. When such a stress is applied, the bending of the main body portion 110a of the backing member 110, which is still slightly generated even when the reinforcement is performed by fixing the reinforcement member 111, is reduced by the stress in the gravity direction due to the weight of the reinforcement member 111. be able to. Thereby, the vibration of the main body 110a can be further suppressed as compared with the case where the reinforcing member 111 is made of a material having a specific gravity smaller than that of the backing member 110.

  The present inventors prepared a printer testing machine having the configuration shown in FIG. 7 and four types of backing reinforcement units. The backing reinforcement unit is a combination of the backing member 110 and the reinforcing member 111. The four types of prepared backing reinforcement units have mutually different ratios of the reinforced region weight M1 and the non-reinforced region weight M2. In addition, the reinforcement area | region weight M1 is the value which added the weight of the area | region where the reinforcement member 111 is fixed among all the area | regions in the belt width direction in the backing member 110, and the weight of the reinforcement member 111 which is a weight member. . Further, the non-reinforcing region weight M2 is the weight of the region where the reinforcing member 111 is not fixed in the entire region of the backing member 110 in the belt width direction.

The inventors investigated the vibration suppression effect of the backing member 110 while sequentially replacing the backing reinforcement unit mounted on the printer testing machine with the above-mentioned four types, and in three stages of x, Δ, and ○. An experiment to evaluate was performed. An evaluation of “x” indicates that the deterioration of the detection accuracy of the toner adhesion amount due to the vibration of the backing member 110 exceeds a permissible range. An evaluation of Δ indicates that although the accuracy of detection of the toner adhesion amount is slightly deteriorated due to the vibration of the backing member 110, the degree of deterioration is at a level where there is no problem. An evaluation of “◯” indicates that the deterioration of the accuracy of detecting the toner adhesion amount due to the vibration of the backing member 110 is not recognized. The results of this experiment are shown in Table 1 below.

  As shown in Table 1, if the value obtained by dividing the reinforcing region weight M1 by the non-reinforcing region weight M2 is 1.8 or more, the vibration suppressing effect of the backing member 110 can be evaluated as ◯. Therefore, in this printer, a backing reinforcement unit having a value obtained by dividing the reinforcing area weight M1 by the non-reinforcing area weight M2 is 1.8 or more.

  In FIG. 7 described above, the reinforcing member 111 includes both end portions that are two fixing regions adjacent to each other in the backing member 110 out of the entire region in the belt width direction of the main body 110a that is a non-fixing region of the backing member 110. It is being fixed to the center area | region of the fixing | fixed part 110b. As shown in FIG. 8, the amount of deflection of the main body 110a in the rubbing direction is the largest in the central region between the two fixing portions 110b. That is, the amplitude in the rubbing direction of the main body 110a is greatest in the above-described central region. In this printer, the reinforcing member 111 is fixed in the central region where the amplitude is maximized in this way, and the vibration in the central region is suppressed, so that the reinforcing member 111 is fixed in the non-central region of the main body 110a. Thus, the vibration of the main body 110a is suppressed. In addition, as the backing member 110, a member having a length in the belt width direction of 350 [mm] is used. By fixing the reinforcing member 111 only in the central region of the main body 110a of the backing member 110, the weight can be reduced by 30% as compared with the case where the reinforcing member is fixed in the entire region of the main body 110a. I was able to.

Next, the printer according to the implementation mode will describe each embodiment apparatus of adding a more characteristic configuration.
[First Embodiment Apparatus]
In the apparatus of the first embodiment, as the backing member 110, the main body 110a is made of a fluororesin or a polyacetal resin. Fluororesin and polyacetal resin are known as substances having a very small friction coefficient. By using the backing member 110 made of such a fluororesin or polyacetal resin, compared to the case of using the backing member 110 made of a material having a relatively large friction coefficient such as rubber, the first intermediate due to the rubbing with the backing member 110 is used. Roughening of the back surface of the transfer belt 8 is suppressed. As a result, it is possible to suppress an increase in vibration of the backing member 110 over time due to the roughening of the back surface of the first intermediate transfer belt 8 over time.

[Second Embodiment Apparatus]
In the apparatus according to the second embodiment, the backing member 110 has a friction coefficient smaller than that of the substrate on at least a sliding surface (upper surface in FIG. 7) with the first intermediate transfer belt 8 in the substrate made of resin or the like of the main body 110a. A surface layer made of a material is used. As a result, as the backing member 110 is used, the back surface of the first intermediate transfer belt 8 is changed over time as compared with the case where the solid base surface of the main body 110a is rubbed against the first intermediate transfer belt 8. The increase in the vibration of the backing member 110 over time due to the roughening can be suppressed.

[Embodiment 3 apparatus]
In the apparatus of the third embodiment, the backing member 110 is a member in which a plurality of raised brushes are erected on the rubbing surface of the main body 110a with the first intermediate transfer belt 8. By sliding and rubbing the surface on which the plurality of raised brushes are erected on the belt, it is possible to improve the effect of scraping foreign matter on the back surface of the belt and to clean the back surface of the first intermediate transfer belt 8 satisfactorily. In addition, there is a possibility that the frictional force between the main body 110a and the belt may be increased over time by capturing foreign matter between the raised hairs and increasing the amount of the captured over time, but this increases the frictional force. The accompanying increase in the vibration amount can be kept at a problem-free level due to the vibration suppressing effect of the reinforcing member 111.

[Fourth embodiment apparatus]
In the apparatus of the fourth embodiment, the same thing as the backing reinforcement unit shown in FIG. 7 is also provided in the second transfer unit 24 shown in FIG. This backing reinforcing unit is disposed in the vicinity of the secondary transfer nip inside the loop of the second intermediate transfer belt 16. Specifically, the “near” here refers to two stretching rollers (secondary transfer roller 17, nip expansion) that stretch the second intermediate transfer belt 16 before and after the secondary transfer nip in the belt moving direction. It is between the rollers 19). In such a configuration, the back reinforcing unit provided inside the loop of the second intermediate transfer belt 16 suppresses undulation and vibration (vibration in the rubbing direction) of the second intermediate transfer belt 16 in the vicinity of the secondary transfer nip. The deterioration of the secondary transfer performance due to them can be suppressed.

Above, in the printer according to the implementation embodiments, as the deflection inhibiting means for inhibiting deflection of the rubbing direction of the backing member 110, of the total area of the belt width direction of the backing member 110, 130 Ya support serving unit front plate A reinforcing member 111 that is fixed to the main body 110a that is an unfixed region that is not fixed to the unit rear plate 131 and reinforces the main body 110a is used. In such a configuration, the vibration of the backing member 110 due to the friction with the belt can be suppressed only by using the conventional backing member 110 and fixing the reinforcing member 111 thereto.

In the printer according to the implementation mode, a rubbing member serving backing member 110, out of the circumferential direction of the entire area of the first intermediate transfer belt 8, so causing rubbing on the back of the horizontal stretching region extending in the horizontal direction The reinforcing member 111 that functions as a deflection inhibiting means is a member that functions as a weight member made of a material having a higher specific gravity than the backing member 110, and is fixed to the main body 110a that is a non-fixed region. . In such a configuration, the vibration of the main body 110a can be further suppressed as compared with the case where the reinforcing member 111 is made of a material having a specific gravity smaller than that of the backing member 110 for the reason described above.

In the printer according to the implementation form, of the total area of the belt member width direction of the backing member 110, and the weight of the area weight member serving as a reinforcing member 111 is fixed, the sum of the weight of the reinforcing member 111 A value obtained by dividing a certain reinforcing area weight M1 by a non-reinforcing area weight M2 that is a weight of an area where the reinforcing member 111 is not fixed in the entire area is 1.8 or more. In such a configuration, for the reason described above, the vibration suppressing effect of the backing member 110 by the reinforcing member 111 can be evaluated as “good”.

In the printer according to the implementation form of the main body 110a is a non-fixed region of the backing member 110, the central region between the two fixed portions 110b are two fixed regions adjacent to each other in the backing member 110 The reinforcement member 111 inhibits the bending in the rubbing direction. In such a configuration, the vibration of the main body 110a can be suppressed as compared with the case where the reinforcing member 111 is fixed to the non-central region of the main body 110a to inhibit the bending of the main body 110a.

  Further, in the first embodiment apparatus, since the backing member 110 is made of a fluororesin or polyacetal resin, for the reason described above, a material made of a material having a relatively high friction coefficient such as rubber is used. In comparison with the above, it is possible to suppress an increase in the vibration of the backing member 110 over time due to the roughening of the back surface of the first intermediate transfer belt 8 over time.

  Further, in the second embodiment apparatus, as the backing member 110, a surface layer made of a material having a smaller friction coefficient than the base is provided on at least the rubbing surface of the main body 110a base with the first intermediate transfer belt 8. Therefore, for the reason described above, the back surface of the first intermediate transfer belt 8 is compared with the case where the solid base surface of the main body 110a is rubbed against the first intermediate transfer belt 8. An increase in the vibration of the backing member 110 over time due to the roughening over time can be suppressed.

  In the third embodiment, since the backing member 110 has a plurality of raised portions on the contact surface with the first intermediate transfer belt 8, the effect of scraping foreign matter on the back surface of the belt is enhanced. The back surface of the first intermediate transfer belt 8 can be cleaned well.

In the printer according to the implementation embodiments, an optical sensor unit 120 for detecting the amount of light reflection at the front surface of the first intermediate transfer belt 8, process control is a predetermined control based on the detection result by this And a control unit as control means for performing the above. The backing member 110 is disposed so as to slide on the belt back surface area on the back side of the detected area, which is a light reflection amount detection location by the optical sensor unit 120 in the first intermediate transfer belt 8. With such a configuration, it is possible to suppress the deterioration of the toner adhesion amount due to the vibration of the detection area of the first intermediate transfer belt 8, and it is possible to suppress the image quality deterioration due to the deterioration.

  In the fourth embodiment, a first intermediate transfer belt 8 is provided as a nip forming member that forms a secondary transfer nip by contacting the front surface of the second intermediate transfer belt 16 that is a belt member. A backing member is disposed in the vicinity of the secondary transfer nip inside the loop of the second intermediate transfer belt 16. In such a configuration, the second intermediate transfer belt 16 in the vicinity of the secondary transfer nip is suppressed from undulations and vibrations (vibrations in the rubbing direction), thereby suppressing deterioration in secondary transfer performance.

1 is a schematic configuration diagram showing a printer according to a reference form. FIG. 3 is an enlarged configuration diagram illustrating a process cartridge for Y in the printer. FIG. 3 is an enlarged configuration diagram illustrating four process cartridges and a first transfer unit of the transfer device in the printer. The enlarged plan view which shows the conventional backing member from the vertical direction upper side with the unit front side plate and unit rear side plate of a 1st transfer unit. The schematic diagram which shows the same lining member which vibrates. The enlarged plan view which shows the backing member in the printer which concerns on a reference form from the vertical direction upper side with the unit front side plate and unit rear side plate of a 1st transfer unit. The expansion exploded perspective view which shows the same backing member and its surrounding structure. The schematic diagram which shows the backing member of the state by which the vibration is suppressed by the reinforcement member.

Explanation of symbols

6Y, M, C, K: Process cartridge (part of visible image forming means)
7: Optical writing unit (part of visible image forming means)
8: First intermediate transfer belt (belt member)
15: First transfer unit (part of visible image forming means)
16: Second intermediate transfer belt (belt member)
24: Second transfer unit (part of visible image forming means)
110: Backing member (rubbing member)
110a: Main body (non-fixed area)
110b: fixed part (fixed area)
111: Reinforcing member (deflection inhibiting means, weight member)
120: Optical sensor unit 130: Unit front plate (support)
131: Unit rear plate (support)

Claims (12)

An endless belt member that is endlessly moved while being stretched by a plurality of tension members, a visible image forming unit that forms a visible image on the front surface of the belt member, and an endlessly moving belt member In an image forming apparatus comprising: a rubbing member that rubs against the back surface; and a support that supports the rubbing member at a plurality of locations in the belt member width direction.
Of the entire region of the rubbing member in the width direction of the belt member, the non-fixed region is fixed to the non-fixed region as a deflection inhibiting means for inhibiting the non-fixed region that is not fixed to the support in the rubbing direction. An image forming apparatus comprising: a reinforcing member that reinforces an area; and the reinforcing member made of a material having a specific gravity higher than that of the rubbing member . The image forming apparatus according to claim 1.
The rubbing member, of the total area of the circumferential direction of the belt member, the image forming apparatus characterized by being arranged so as cause rubbing on the back of the horizontal stretching region extending in the horizontal direction. The image forming apparatus according to claim 2,
Of the entire region of the rubbing member in the belt member width direction, the sum of the weight of the region where the reinforcing member is fixed and the weight of the reinforcing member is fixed. An image forming apparatus, wherein a value obtained by dividing by a weight of an unoccupied area is 1.8 or more. The image forming apparatus according to any one of claims 1 to 3,
Of the non-fixed region of the rubbing member, the central region between two adjacent fixed regions of the rubbing member is made less likely to bend in the rubbing direction than the fixed region, or An image forming apparatus, wherein the reinforcing member inhibits the bending in the rubbing direction. The image forming apparatus according to any one of claims 1 to 4,
An image forming apparatus characterized in that a material made of a fluororesin or a polyacetal resin is used as the rubbing member. The image forming apparatus according to any one of claims 1 to 4,
An image forming apparatus, wherein the rubbing member is provided with a surface layer made of a material having a smaller friction coefficient than that of the base on at least a rubbing surface of the base with the belt member. The image forming apparatus according to claim 1,
An image forming apparatus, wherein a member having a plurality of raised portions on a contact surface with the belt member is used as the rubbing member. The image forming apparatus according to claim 1,
An optical sensor for detecting the amount of light reflection on the front surface of the belt member and a control means for performing predetermined control based on the detection result thereby are provided, and the rubbing member is mounted on the front surface. An image forming apparatus, wherein the image forming apparatus is disposed so as to be rubbed against a belt back surface region on the back side of a portion where a light reflection amount is detected by the optical sensor. The image forming apparatus according to claim 1,
An image forming apparatus comprising: a nip forming body that forms a transfer nip by contacting a front surface of the belt member; and the rubbing member is disposed in the vicinity of the transfer nip. The image forming apparatus according to claim 1,
An image forming apparatus, wherein the reinforcing member is fixed only at a center of the non-fixed region in the belt member width direction. The image forming apparatus according to claim 1,
An image forming apparatus, wherein the reinforcing member is screwed and fixed to the non-fixed region. The image forming apparatus according to claim 1,
As the visible image forming means, a visible image formed on the surface of the image carrier is used for intermediate transfer from the surface to the front surface of the intermediate transfer belt as the belt member,
A nip forming body for forming a transfer nip for transferring the visible image intermediately transferred to the front surface to a recording sheet by contacting the front surface;
An image forming apparatus comprising the rubbing member disposed in the vicinity of the transfer nip.

Images