JP2022123969A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that reduces the likelihood of the occurrence of image defects, while preventing the occurrence of stripe-like scratches in a circumferential direction of an image carrier.SOLUTION: An image forming apparatus comprises: an image carrier; an electrifying device; an exposure device; a developing device; transfer means; a cleaning blade that is brought into pressure contact with an outer peripheral surface of the carrier to remove a residual toner on the image carrier; a temperature and humidity detection device that detects the temperature and humidity on the periphery of the image carrier; a driving mechanism that reciprocates the image carrier or the cleaning blade along a rotation axis direction; and a control unit that executes the reciprocation when the temperature and humidity on the periphery of the image carrier detected by the temperature and humidity detection device are equal to or less than predetermined values.SELECTED DRAWING: Figure 6

Description

The present invention relates to an image forming apparatus.

Conventionally, in image forming apparatuses such as copiers, printers, and facsimiles, a toner image is formed by transferring toner contained in a developer onto an image carrier such as a photosensitive drum, and the formed toner image is transferred to a sheet of paper or the like. After transferring to the recording medium, residual toner on the image carrier is cleaned. The cleaned residual toner is stored in the cleaning section or in a residual toner storage container arranged outside the cleaning section. In order to remove the residual toner on the image carrier, an image forming apparatus is generally known that has a cleaning blade that is in pressure contact with the image carrier.

In such an image forming apparatus, the cleaning blade is always pressed against the image carrier at the same position in the axial direction. As a result, paper dust, toner external additives, and the like clogged in the gap between the tip of the cleaning blade and the image carrier remain, and these remaining substances are rubbed against the image carrier at the same position in the axial direction. As a result, as the number of printed sheets increases, streaky scratches (drum peripheral scratches) are generated along the circumferential direction on the outer peripheral surface of the image carrier, and the resulting image is affected.

As a countermeasure against the circumferential damage of the drum, for example, Japanese Patent Application Laid-Open No. 2002-100000 discloses an image forming apparatus provided with a drive mechanism capable of reciprocating the image carrier in the axial direction. The driving mechanism disclosed in Patent Document 1 can move the image carrier in the axial direction while it is being rotationally driven. In this way, residual toner on the drum can be removed while the drum and the cleaning blade move relative to each other along the axial direction. That is, the tip of the cleaning blade is pressed against the image carrier at different positions in the axial direction. As a result, residual matter (paper dust, toner external additives, etc.) clogged in the gap between the tip of the cleaning blade and the image bearing member can easily move in the axial direction, and can be prevented from rubbing against the same portion. can. As a result, the image forming apparatus disclosed in Japanese Patent Laid-Open No. 2002-300011 can suppress the occurrence of circumferential scratches on the drum.

JP-A-62-273586

In recent years, due to the demand for faster image forming speed and energy saving, the melting point of the toner contained in the developer tends to be lowered, and the toner tends to soften in a high-temperature and high-humidity environment. Therefore, in the image forming apparatus of Patent Document 1, when the image carrier and the cleaning blade move relative to each other in the axial direction in a high-temperature and high-humidity environment, the softened toner is rubbed against the image carrier by the cleaning blade. As a result, the toner that should be scraped off may adhere to the image carrier without being scraped off, and may remain as it is. As a result, the residual toner may be printed on the recording medium, resulting in an image defect.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide an image forming apparatus that suppresses the occurrence of streak-like scratches in the circumferential direction of an image carrier and prevents image defects from occurring.

In order to achieve the above object, the configuration of the present invention is an image forming apparatus including an image carrier, a charging device, an exposure device, a developing device, transfer means, and a cleaning blade. The image carrier has a cylindrical shape with a photosensitive layer formed on the outer peripheral surface, and is connected to a rotation shaft passing through the central axis of the cylinder. The charging device charges the photosensitive layer of the image carrier. The exposure device forms an electrostatic latent image by irradiating beam light onto the image carrier charged by the charging device. The developing device supplies developer to the electrostatic latent image formed on the image carrier by the exposure device to form a toner image. The transfer means transfers the toner image formed on the image bearing member by the developing device onto the recording medium or the intermediate transfer member. The cleaning blade is pressed against the outer peripheral surface of the image carrier and cleans residual toner on the image carrier. The image forming apparatus includes a temperature/humidity detection device that detects the temperature and humidity around the image carrier, a driving mechanism that reciprocates the image carrier or cleaning blade along the direction of the rotation axis, and a temperature/humidity detection device. a control unit that executes the reciprocating movement when the temperature and humidity around the image carrier are equal to or less than predetermined values.

According to the configuration of the present invention, the controller reciprocates the image carrier or the cleaning blade when the temperature and humidity around the image carrier are equal to or less than predetermined values. Then, since the contact point between the image carrier and the cleaning blade moves from a predetermined position in the axial direction, it is possible to suppress the occurrence of streaky scratches in the circumferential direction of the image carrier. Further, the control section does not execute the reciprocating movement of the cleaning blade when the temperature and humidity around the image bearing member rise above predetermined values and the environment becomes a high-temperature and high-humidity environment. Therefore, the softened toner is prevented from rubbing against the image carrier, and the toner is less likely to remain on the image carrier, resulting in less image defects.

Therefore, it is possible to provide an image forming apparatus that suppresses the occurrence of streak-like scratches in the circumferential direction of the image carrier and prevents the occurrence of image defects.

Schematic diagram showing the configuration of the image forming apparatus 100 of the present invention Enlarged view of the vicinity of the image forming portion Pa in FIG. Schematic view of drive mechanism 40 for photosensitive drums 1a to 1d in image forming apparatus 100 viewed from above Schematic view of the drive mechanism 40 viewed from the side (downward in FIG. 3) Appearance perspective view of fixed cam 51 and rotating cam 53 FIG. 2 is a block diagram showing an example of a control path of the image forming apparatus 100 of the first embodiment; FIG. Flowchart showing an example of control by the control unit 90 according to the first embodiment Flowchart showing details of control in step S4 Flowchart showing an example of control by the control unit 90 according to the second embodiment FIG. 10 is a flow chart detailing a portion of the flow chart shown in FIG. 9;

An image forming apparatus according to a first embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus 100 of the present invention. Four image forming units Pa, Pb, Pc, and Pd are arranged in order from the upstream side (the right side in FIG. 1) in the conveying direction in the main body of the image forming apparatus 100 . These image forming units Pa to Pd are provided corresponding to images of four different colors (cyan, magenta, yellow and black). and black images are sequentially formed.

Photoreceptor drums 1a, 1b, 1c and 1d carrying visible images (toner images) of respective colors are arranged in these image forming units Pa to Pd. An OPC photoreceptor on which a layer (OPC) is formed is used. The coefficient of friction of the outer peripheral surfaces (organic photosensitive layers) of the photosensitive drums 1a to 1d is 0.2 or more and 0.8 or less (preferably 0.2 or more and 0.6 or less).

An intermediate transfer belt 8 (intermediate transfer member) rotated clockwise in FIG. 1 by driving means (not shown) is provided adjacent to each of the image forming stations Pa to Pd. The toner images formed on these photoreceptor drums 1a to 1d are sequentially primary-transferred and superimposed on an intermediate transfer belt 8 that moves in contact with the respective photoreceptor drums 1a to 1d, and then transferred to a secondary transfer roller. By the action of 9, the image is secondary-transferred onto a sheet S as an example of a recording medium, fixed onto the sheet S by the fixing section 7, and then discharged from the main body of the apparatus. An image forming process is performed on each of the photosensitive drums 1a to 1d while rotating the photosensitive drums 1a to 1d counterclockwise in FIG.

A driving mechanism 40 is connected to the photosensitive drums 1a to 1d (see FIG. 6). The driving mechanism 40 reciprocates the photosensitive drums 1a to 1d in a direction along the rotation axis (hereinafter referred to as "axial direction"). The details of the configuration of the drive mechanism 40 will be described later.

The paper S onto which the toner image is to be transferred is housed in a paper cassette 16 at the bottom of the main body of the image forming apparatus 100, and conveyed to the secondary transfer roller 9 via a paper feed roller 12a and a pair of registration rollers 12b. . A dielectric resin sheet is used for the intermediate transfer belt 8, and a seamless belt is mainly used. A blade-shaped belt cleaner 19 for removing toner remaining on the surface of the intermediate transfer belt 8 is arranged downstream of the secondary transfer roller 9 with respect to the rotation direction of the intermediate transfer belt 8 .

Next, the image forming units Pa to Pd will be described. Charging devices 2a, 2b, 2c and 2d for charging the photosensitive drums 1a to 1d and image information on the photosensitive drums 1a to 1d are provided around and below the rotatably arranged photosensitive drums 1a to 1d. , developing devices 3a, 3b, 3c and 3d for forming toner images on the photosensitive drums 1a to 1d, and removing developer (residual toner) remaining on the photosensitive drums 1a to 1d. Cleaning devices 5a to 5d are provided for cleaning.

When the start of image formation is input by the user, first, the surfaces of the photosensitive drums 1a to 1d are uniformly charged by the charging devices 2a to 2d, and then the surfaces of the photosensitive drums 1a to 1d are irradiated with light by the exposure device 4. Then, an electrostatic latent image corresponding to the image data is formed on each of the photosensitive drums 1a to 1d. The developing devices 3a to 3d are provided with developing rollers arranged opposite to the photosensitive drums 1a to 1d, and are filled with predetermined amounts of two-component developer containing yellow, cyan, magenta, and black toners, respectively. The toner is supplied onto the photosensitive drums 1a to 1d by the developing rollers of the developing devices 3a to 3d, and adheres electrostatically to form an electrostatic latent image formed by exposure from the exposure device 4. A toner image is formed.

Then, an electric field is applied between the primary transfer rollers 6a to 6d and the photosensitive drums 1a to 1d by the primary transfer rollers 6a to 6d (transfer means) with a predetermined transfer voltage, and yellow, Cyan, magenta and black toner images are primarily transferred onto the intermediate transfer belt 8 . These four-color images are formed with a predetermined positional relationship for predetermined full-color image formation. Thereafter, residual toner remaining on the surfaces of the photosensitive drums 1a to 1d is removed by the cleaning devices 5a to 5d in preparation for subsequent formation of new electrostatic latent images.

The intermediate transfer belt 8 is stretched over a plurality of suspension rollers including a driven roller 10 and a drive roller 11 . The drive roller 11 is connected to a drive motor 62 (see FIG. 6). Drive motor 62 is connected to control section 90 of image forming apparatus 100 . The driving motor 62 applies rotational driving force to the driving roller 11 to rotate the driving roller 11 according to an instruction from the control unit 90 .

As the drive roller 11 rotates, the intermediate transfer belt 8 starts to rotate clockwise, and the sheet S is transferred from the pair of registration rollers 12b to the secondary transfer roller 9 ( transfer means), and the full-color image is secondarily transferred onto the sheet S at the nip portion (secondary transfer nip portion) with the intermediate transfer belt 8 . The sheet S onto which the toner image has been transferred is conveyed to the fixing section 7 .

The sheet S conveyed to the fixing section 7 is heated and pressurized when passing through the nip portion of the fixing roller pair 13, and the toner image is fixed on the surface of the sheet S to form a predetermined full-color image. The sheet S on which a full-color image is formed is distributed in the conveying direction by the branching section 14 branching in a plurality of directions. When an image is formed only on one side of the sheet S, the sheet S is directly discharged to the discharge tray 17 by the discharge roller pair 15 .

On the other hand, when images are formed on both sides of the sheet S, a part of the sheet S that has passed through the fixing section 7 is once protruded from the discharge roller pair 15 to the outside of the apparatus. After that, the sheet S is distributed to the sheet conveying path 18 at the branch portion 14 by rotating the discharge roller pair 15 in the reverse direction, and is conveyed again to the registration roller pair 12b with the image surface being reversed. Then, the next image formed on the intermediate transfer belt 8 is transferred by the secondary transfer roller 9 onto the surface of the sheet S on which the image is not formed, conveyed to the fixing section 7, and after the toner image is fixed, It is discharged to the discharge tray 17 .

FIG. 2 is an enlarged view of the vicinity of the image forming portion Pa in FIG. Note that the image forming units Pb to Pd also have basically the same configuration, so description thereof will be omitted. Around the photosensitive drum 1a, a charging device 2a, a developing device 3a, a cleaning device 5a, and a neutralization lamp 20 are arranged along the drum rotation direction (counterclockwise direction in FIG. 2). A primary transfer roller 6a is arranged on both sides.

The charging device 2 a has a charging roller 21 that contacts the photosensitive drum 1 a to apply a charging bias (DC voltage) to the surface of the drum, and a charging cleaning roller 23 that cleans the charging roller 21 . In the present invention, in order to reduce the amount of ozone generated and to reduce the cost of a charging bias power supply (not shown), a charging bias consisting of only a DC voltage is applied to the charging roller 21. A method of applying a bias in which an AC bias is superimposed on the .

The developing device 3a is of a two-component developing type having two agitating and conveying screws 25, a magnetic roller 27, and a developing roller 29. A magnetic brush standing on the surface of the magnetic roller 27 is used to apply thin toner to the developing roller 29. A layer is formed, and a developing bias having the same polarity (positive) as that of the toner is applied to the developing roller 29 to fly the toner onto the drum surface.

The cleaning device 5 a has a cleaning blade 31 and a toner discharge screw 33 . The cutting edge of the cleaning blade 31 is in contact with the outer peripheral surfaces of the photosensitive drums 1a to 1d. As the photosensitive drums 1a to 1d rotate, the tip of the cleaning blade 31 scrapes off the residual toner. The JIS-A hardness of the tip of the cleaning blade 31 is 60 degrees or more and 80 degrees or less (preferably 70 degrees or more and 78 degrees or less).

A neutralizing lamp 20 is arranged between the cleaning device 5a and the charging device 2a. The charge removing lamp 20 removes residual charges on the surface of the photosensitive drum 1a by irradiating the surface of the photosensitive drum 1a with light.

Next, an example of the configuration of the drive mechanism 40 according to the image forming apparatus 100 of the first embodiment will be described with reference to FIGS. 3 to 5. FIG. FIG. 3 is a schematic view of the driving mechanism 40 for the photosensitive drums 1a to 1d in the image forming apparatus 100 as viewed from above. FIG. 4 is a schematic view of the drive mechanism 40 viewed from the side (downward in FIG. 3). 5 is an external perspective view of the fixed cam 51 and the rotating cam 53. FIG. The upper side of FIG. 3 corresponds to the front side (rear side) of FIG. 1, and the arrangement of the photosensitive drums 1a to 1d is left-right reversed between FIG. 1 and FIG.

A drum rotating shaft 43 for inputting a driving force to the photosensitive drums 1a to 1d is rotatably supported by a side frame 41 on the rear side (deep side of the paper surface of FIG. 1) of the image forming apparatus 100 main body. A driving force is input to one end of a drum rotating shaft 43 protruding outside (upper side in FIG. 3) of the side frame 41 by a driving motor and a gear train (both not shown). A drum coupling 45 that can be connected to the photosensitive drums 1a to 1d is movable in the axial direction of the drum rotation shaft 43 at the other end of the drum rotation shaft 43 protruding inside the side frame 41 (lower side in FIG. 3). extrapolated. A coil spring 47 is sandwiched between the tip 43a of the drum rotating shaft 43 and the drum coupling 45, and the drum coupling 45 is biased by the coil spring 47 toward the side frame 41 (upward in FIG. 3). ing. The photosensitive drums 1a to 1d are also axially slidably supported in the image forming portions Pa to Pd, and are biased toward the side frame 41 by biasing means (not shown). Note that FIG. 3 shows only the drum rotation shaft 43 and the drum coupling 45 corresponding to the photosensitive drum 1a.

A fixed cam 51 and a rotating cam 53 are arranged between the side frame 41 and the drum coupling 45 . The fixed cam 51 is fixed to the side frame 41 , and the rotating cam 53 is rotatably fitted around the drum rotating shaft 43 . Further, the rotating cam 53 is integrally formed with the cam driving gears 55a-55d.

A drive input gear 57 meshes with the cam drive gears 55b and 55c. The drive input gear 57 is a two-stage gear composed of a large-diameter first gear portion 57a and a small-diameter second gear portion 57b. The first gear portion 57a is a spur gear that meshes with the cam drive gears 55b and 55c. The second gear portion 57b is a one-way gear capable of transmitting driving force in only one direction (clockwise direction in FIG. 3), and is a claw gear having claw-shaped gear teeth formed on the outer peripheral surface. A one-way clutch is provided in the bearing portion of the drive input gear 57 so that the drive input gear 57 can rotate only clockwise with respect to the support shaft. A driving pawl 61 reciprocatingly moved by a solenoid 60 is engaged with gear teeth of the second gear portion 57b. One end of the drive claw 61 is rotatably supported by the iron core 63 of the solenoid 60 . The other end side of the driving claw 61 rotates downward under its own weight.

An idle gear 59a meshes with the cam drive gears 55a and 55b, and an idle gear 59b meshes with the cam drive gears 55c and 55d. The idle gears 59a and 59b are spur gears, and the idle gears 59a and 59b are rotatably supported by a rotating shaft fixed to the side frame 41. As shown in FIG.

As shown in FIG. 5, the fixed cam 51 has a cam body 51a and a cam follower 51b. The cam follower 51b is an annular protrusion that protrudes from the side surface of the cam body 51a and contacts the cam surface 53b of the rotating cam 53. As shown in FIG. The cam follower 51b is formed so that the axial distance is different (displaced) in the circumferential direction, and a maximum portion (projection) and a minimum portion (recess) are formed at 180° intervals.

The rotating cam 53 has a cam body 53a and a cam surface 53b. The cam surface 53b is annularly formed on the side surface of the cam body 53a and contacts the cam follower 51b of the fixed cam 51 . The cam surface 53b has a maximum portion (convex portion) and a minimum portion (concave portion) of 180 degrees so that the axial distance always changes (displaces) by a predetermined amount per unit rotational angle of the rotating cam 53 in the circumferential direction. ° are formed one by one at intervals. Here, the fixed cam 51 having the cam follower 51b is fixed to the side frame 41, and the movement of the fixed cam 51 in the axial direction (vertical direction in FIG. 3) is restricted. Therefore, the rotating cam 53 having the cam surface 53b moves relative to the fixed cam 51 having the cam follower 51b in the axial direction according to the contact position between the cam follower 51b and the cam surface 53b.

When the iron core 63 of the solenoid 60 is retracted, the drive claw 61 moves rightward in FIG. 3, and rotates the second gear portion 57b of the drive input gear 57 clockwise by a predetermined angle. As a result, the first gear portion 57a of the drive input gear 57 also rotates clockwise by a predetermined angle, and the cam drive gears 55b and 55c meshing with the first gear portion 57a also rotate counterclockwise by a predetermined angle.

When the iron core 63 of the solenoid 60 protrudes in preparation for the next rotation operation, the driving claw 61 moves leftward in FIG. Since it is a transmittable one-way gear, even if the second gear portion 57b is rotated counterclockwise by the driving pawl 61, the driving force is not transmitted to the first gear portion 57a.

When the cam drive gears 55b and 55c rotate counterclockwise by a predetermined angle, the idle gears 59a and 59b meshing with the cam drive gears 55b and 55c rotate clockwise by a predetermined angle, and the cams mesh with the idle gears 59a and 59b. The drive gears 55a and 55d also rotate counterclockwise by a predetermined angle. That is, all the cam drive gears 55a to 55d rotate counterclockwise by a predetermined angle.

When the cam drive gears 55a to 55d rotate by a predetermined angle, the rotating cams 53 integrally formed with the cam drive gears 55a to 55d also rotate by a predetermined angle. As a result, the contact position between the cam follower 51b formed on each fixed cam 51 and the cam surface 53b formed on each rotating cam 53 changes. As a result, the drum coupling 45 moves axially, and the photosensitive drums 1a to 1d connected to the drum coupling 45 also move axially.

At the position where the minimum portion of the cam surface 53b contacts the maximum portion of the cam follower 51b and the maximum portion of the cam surface 53b contacts the minimum portion of the cam follower 51b, the axial distance between the fixed cam 51 and the rotating cam 53 is minimized. , the photosensitive drums 1a to 1d are arranged at positions closest to the side frame 41 (uppermost in FIG. 3).

As the rotating cam 53 rotates further, the photosensitive drums 1a to 1d gradually move downward in FIG. At a position where the maximum portion of the cam surface 53b contacts the maximum portion of the cam follower 51b and the minimum portion of the cam surface 53b faces the minimum portion of the cam follower 51b, the axial distance between the fixed cam 51 and the rotating cam 53 becomes maximum. , the photosensitive drums 1a to 1d are arranged at the farthest position from the side frame 41 (the lowest position in FIG. 3). When the rotating cam 53 rotates further, the photosensitive drums 1a to 1d move upward again in FIG. 3 and repeat the reciprocating movement in the axial direction. At this time, the drum rotating shafts 43 of the photosensitive drums 1a to 1d rotate in the opposite direction (clockwise direction in FIG. 3) to the cam driving gears 55a to 55d. 55a-55d. However, since the drive input gear 57 is provided with a one-way clutch, the rotation of the cam drive gears 55b and 55c is not transmitted to the drive input gear 57. FIG.

As described above, since the photoreceptor drums 1a to 1d reciprocate in the axial direction, the cleaning blade 31 (see FIG. 2) in contact with the photoreceptor drums 1a to 1d is clogged with paper dust, external toner additives, and the like. Therefore, there is no danger that the same position on the surface of the photosensitive drums 1a to 1d will be rubbed repeatedly. Therefore, the residual toner on the photoreceptor drums 1a to 1d is cleaned without damaging the surfaces of the photoreceptor drums 1a to 1d.

The reciprocating movement of the photoreceptor drums 1a to 1d is periodic movement of one reciprocation per predetermined number of rotations of the photoreceptor drums 1a to 1d. A preferable cycle of reciprocation is a cycle of one reciprocation when the predetermined number of rotations of the photosensitive drums 1a to 1d is 10 or more and 200 or less (more preferably 50 or more and 100 or less).

Also, the cleaning blade 31 can be fixedly attached to, for example, the cleaning devices 5a to 5d. As a result, compared to a configuration in which the cleaning blade 31 is reciprocated in the axial direction of the photosensitive drums 1a to 1d, the configuration of the sealing portions of the cleaning devices 5a to 5d is simpler, so that toner does not flow outside the cleaning devices 5a to 5d. There is no risk of scattering.

In addition, the arrangement of the fixed cam 51 and the rotating cam 53 in the axial direction is reversed from that of the present embodiment, and the fixed cam 51 is fixed to the drum coupling 45 side (for example, the photosensitive drums 1a to 1d are rotatably held). The rotary cam 53 may be arranged on the side frame 41 side and driven to rotate.

FIG. 6 is a block diagram showing an example of control paths of the image forming apparatus 100 of the first embodiment. Since various parts of the apparatus are controlled when the image forming apparatus 100 is used, the overall control path of the image forming apparatus 100 is complicated. Therefore, here, the portion of the control path that is necessary for implementing the present invention will be mainly described.

The control unit 90 includes a CPU (Central Processing Unit) 91 as a central processing unit, a read-only memory (ROM) 92, a readable/writable memory (RAM) (Random Access Memory) 93, a temporary A temporary storage unit 94 for temporarily storing image data and the like, a counter 95, and a plurality (here, two) for transmitting control signals to each device in the image forming apparatus 100 and receiving input signals from the operation unit 80. at least an I/F (interface) 96 of Also, the control unit 90 can be arranged at any place inside the main body of the image forming apparatus 100 .

The ROM 92 stores a program for controlling the image forming apparatus 100 and data such as numerical values necessary for control that are not changed while the image forming apparatus 100 is in use. The RAM 93 stores necessary data generated during control of the image forming apparatus 100, data temporarily necessary for controlling the image forming apparatus 100, and the like. The RAM 93 (or ROM 92) also stores temperature and humidity setting values (temperature and humidity under a high temperature and high humidity environment) when reciprocating movement is executed. A counter 95 accumulates and counts the number of printed sheets.

The control unit 90 transmits a control signal from the CPU 91 to each device in the image forming apparatus 100 through the I/F 96 . Signals and input signals indicating the state of each part and device are transmitted to the CPU 91 through the I/F 96 . The parts and devices controlled by the control unit 90 include, for example, the image forming units Pa to Pd, the exposure device 4, the in-machine temperature and humidity sensor 50, the drive motor 62, the drive mechanism 40, the image input unit 70, the operation unit 80, and the like. mentioned.

The image input unit 70 is a receiving unit that receives image data transmitted from a host device such as a personal computer to the image forming apparatus 100 . The image signal input from the image input section 70 is converted into a digital signal and sent to the temporary storage section 94 .

The operation unit 80 is provided with a liquid crystal display unit 81 and LEDs 82 indicating various states. Various settings of the forming apparatus 100 are set to the default state. The liquid crystal display section 81 indicates the state of the image forming apparatus 100, and displays the image forming state and the number of print copies. Various settings of the image forming apparatus 100 are performed from the printer driver of the personal computer.

The in-machine temperature/humidity sensor 50 (temperature/humidity detection device) is provided at an arbitrary location inside the image forming apparatus 100 (preferably a location near the photosensitive drums 1a to 1d) and is connected to the controller 90. The internal temperature/humidity sensor 50 can detect the temperature and humidity around the photosensitive drums 1 a to 1 d , and the detected temperature/humidity is sent to the controller 90 .

A solenoid 60 of the drive mechanism 40 is connected to the control section 90 . The controller 90 reciprocates the photosensitive drums 1a to 1d when the temperature detected by the internal temperature/humidity sensor 50 is below a predetermined temperature (32 degrees) and the humidity is below a predetermined humidity (85% relative humidity). A predetermined instruction (specifically, an instruction to execute reciprocating movement of the iron core 63 to the solenoid 60) is issued. The reciprocating movement of the photoreceptor drums 1a to 1d is executed when the photoreceptor drums 1a to 1d rotate (when the drive motor 62 is activated).

Next, reciprocating movement of the photosensitive drums 1a to 1d by the controller 90 according to the first embodiment will be described in detail with reference to FIGS. 7 and 8. FIG. FIG. 7 is a flow chart showing an example of control by the control unit 90 according to the first embodiment.

As shown in FIG. 7, first, the control unit 90 determines whether or not the drive motor 62 is applying rotational driving force to the drive roller 11 (hereinafter referred to as "drive transmission state") (step S1 ). When the drive motor 62 is in the drive transmission state (Yes in step S1), the internal temperature and humidity sensor 50 measures the temperature and humidity around the photosensitive drums 1a to 1d (step S2). The temperature and humidity measured at this time are sent to the control unit 90 .

Next, based on the transmitted temperature and humidity, the control unit 90 determines that the surroundings of the photosensitive drums 1a to 1d are in a high-temperature and high-humidity environment (environment with a temperature of 32° C. or higher and a relative humidity of 85% or higher). It is determined whether or not (step S3).

If it is determined in step S3 that the surroundings of the photosensitive drums 1a to 1d are not in a high-temperature, high-humidity environment (No in step S3), the controller 90 reciprocates the photosensitive drums 1a to 1d once in the axial direction. (step S4). Details of the control of the reciprocating movement of the photosensitive drums 1a to 1d in step S4 will be described later.

Next, the controller 90 determines whether or not the drive motor 62 is in the drive transmission state (step S5). If the drive motor 62 is in the drive transmission state (Yes in step S5), the process returns to step S2. On the other hand, if it is determined in step S5 that the driving motor 62 is not in the drive transmission state (the driving motor 62 is in a stopped state) (No in step S5), the control unit 90 controls the reciprocating movement of the photosensitive drums 1a to 1d. terminate. That is, the control unit 90 repeats steps S2 to S5 until it is determined in step S5 that the drive motor 62 is not in the drive transmission state (the drive motor 62 is stopped).

FIG. 8 is a flowchart showing in detail the control in step S4. As shown in FIG. 8, when it is determined in step S3 that the surroundings of the photosensitive drums 1a to 1d are not in a high-temperature and high-humidity environment (No in step S3), the controller 90 causes the iron core 63 of the solenoid 60 to protrude. It is determined whether or not it is in the state (step S41).

When it is determined in step S41 that the iron core 63 is not in the projected state (No in step S41), the iron core 63 is projected (step S42). Next, the protruding iron core 63 is retracted (step S43). On the other hand, if it is determined in step S41 that the iron core 63 is protruding (Yes in step S41), step S42 is skipped and the process proceeds to step S43, in which the iron core 63 is retracted. Since one end of the driving claw 61 reciprocates due to the reciprocation of the iron core 63, the photosensitive drums 1a to 1d reciprocate in the axial direction as described above.

As described above, when the temperature and humidity around the photosensitive drums 1a to 1d are below the predetermined values (temperature: 32°C, relative humidity: 85%), the control unit 90 controls the photosensitive drums 1a to 1d or cleaning. Reciprocating movement of the blade 31 is executed. As a result, the contact points between the photoreceptor drums 1a to 1d and the cleaning blade 31 change from a fixed position, so that it is possible to suppress the occurrence of linear scratches in the circumferential direction of the photoreceptor drums 1a to 1d. Further, when the temperature and humidity around the photosensitive drums 1a to 1d rise above the predetermined values and the environment becomes a high-temperature and high-humidity environment, the control unit 90 does not perform the reciprocating movement. Therefore, the softened toner is prevented from being rubbed against the photosensitive drums 1a to 1d, so that the toner is less likely to remain on the photosensitive drums 1a to 1d, and image defects are less likely to occur.

Therefore, it is possible to provide an image forming apparatus 100 capable of suppressing defective images while suppressing streaky scratches from occurring in the circumferential direction of the photosensitive drums 1a to 1d.

Here, as described above, the coefficient of friction of the outer peripheral surface (organic photosensitive layer) of the photosensitive drums 1a to 1d according to the present invention is 0.2 or more and 0.8 or less (preferably 0.2 or more and 0 .6 or less). By doing so, the adhesive force of the toner to the photosensitive drums 1a to 1d is weakened, and it is possible to more preferably suppress the residual toner. Further, the frictional force generated between the cleaning blade 31 and the photoreceptor drums 1a to 1d is reduced, and damage to the photoreceptor drums 1a to 1d can be suppressed.

Further, if the JIS-A hardness of the cutting edge portion of the cleaning blade 31 is less than 60 degrees, the toner scraping performance deteriorates and the toner tends to remain. If the angle is larger than 80 degrees, the amount of wear on the outer peripheral surfaces of the photosensitive drums 1a to 1d increases. On the other hand, the JIS-A hardness of the cutting edge portion of the cleaning blade 31 according to the present invention is 60 degrees or more and 80 degrees or less (preferably 70 degrees or more and 78 degrees or less) as described above. In this way, the toner on the outer peripheral surfaces of the photoreceptor drums 1a to 1d can be suitably scraped off, and abrasion of the photoreceptor drums 1a to 1d can be suppressed.

In addition, as described above, a suitable cycle of reciprocation is one reciprocation when the predetermined number of rotations of the photosensitive drums 1a to 1d is 10 or more and 200 or less (more preferably 50 or more and 100 or less). It is a cycle to In this way, color misregistration is less likely to occur on the photosensitive drums 1a to 1d, and the toner scraping performance of the cleaning blade 31 is also favorable.

Next, control of the control section 90 of the second embodiment according to the present invention will be described with reference to FIGS. 9 and 10. FIG. In addition, below, the difference with 1st Embodiment is described, the same code|symbol is attached|subjected to the structure similar to 1st Embodiment, and description is abbreviate|omitted.

FIG. 9 is a flow chart showing an example of control by the control unit 90 according to the second embodiment. FIG. 10 is a flow chart showing details of a portion of the flow chart shown in FIG. Note that steps S1 to S3 and step S5 in FIG. 9 are common to the above-described control (see the flow charts in FIGS. 7 and 8), so description thereof will be omitted.

The controller 90 according to the second embodiment slows down the reciprocating speed of the photosensitive drums 1a to 1d in the axial direction as the temperature and humidity around the photosensitive drums 1a to 1d increase. That is, as the temperature and humidity around the photosensitive drums 1a to 1d increase, the reciprocating cycle of the photosensitive drums 1a to 1d is lengthened. Here, the reciprocating speed of the photoreceptor drums 1a to 1d is set to the first The speed is changed in three stages from the first speed to the third speed.

Each temperature/humidity (first temperature/humidity, second temperature/humidity, third temperature/humidity) is a temperature and humidity value set arbitrarily within a range that does not correspond to a high-temperature/high-humidity environment. Among the first temperature/humidity to the third temperature/humidity, the temperature and humidity at the first temperature/humidity are the lowest, and the temperature and humidity at the third temperature/humidity are the highest. Further, among the speeds (first speed, second speed, third speed), the first speed is the fastest and the third speed is the slowest.

The cycle of the reciprocation when the photoreceptor drums 1a to 1d reciprocate at the first speed is 10 or more and less than 100 (preferably 50 or more and less than 100) rotations of the photoreceptor drums 1a to 1d. It makes one round trip in the direction. The reciprocating cycle of the photoreceptor drums 1a to 1d reciprocating at the second speed is one reciprocation in the axial direction for every rotation number of 100 or more and less than 150 of the photoreceptor drums 1a to 1d. The cycle of the reciprocating movement of the photoreceptor drums 1a to 1d at the third speed is one reciprocation in the axial direction for every rotation number of 150 or more and 200 or less.

As shown in FIG. 9, when it is determined in step S3 that the environment around the photoreceptor drum is not in a high-temperature, high-humidity environment (No in step S3), the control unit 90 sets the temperature and humidity around the photoreceptor drum to the first temperature. It is determined whether or not it is lower than the humidity (step S6). When the temperature and humidity around the photosensitive drums are lower than the first temperature and humidity (Yes in step S6), the controller 90 reciprocates the photosensitive drums 1a to 1d in the axial direction once at the first speed (step S7).

If it is determined in step S6 that the temperature and humidity around the photosensitive drums are higher than the first temperature and humidity (No in step S6), then as shown in FIG. It is determined whether or not the surrounding temperature and humidity are lower than the second temperature and humidity (step S8). If the temperature and humidity around the photoreceptor drums 1a to 1d are lower than the second temperature and humidity (Yes in step S8), the control unit 90 reciprocates the photoreceptor drums 1a to 1d once at the second speed (step S9), and then Go to step S5.

If the temperature and humidity around the photoreceptor drums 1a to 1d are higher than the second temperature and humidity (No in step S8), the control unit 90 causes the photoreceptor drums 1a to 1d to reciprocate once at the third speed ( Step S10), and then proceed to step S5. The temperature and humidity around the photosensitive drums 1a to 1d at step S10 are the third temperature and humidity.

By doing so, the relative speed between the photoreceptor drums 1a to 1d and the cleaning blade 31 gradually increases as the temperature and humidity around the photoreceptor drums 1a to 1d decrease from the temperature of the high-temperature and high-humidity environment. get faster. In other words, the relative speed between the photoreceptor drums 1a to 1d and the cleaning blade 31 gradually slows down as the environment approaches a high temperature and high humidity environment. As a result, compared to the case where the photosensitive drums 1a to 1d are suddenly stopped at the time the photosensitive drums 1a to 1d reach a high-temperature and high-humidity environment while the relative speed between the photosensitive drums 1a to 1d and the cleaning blade 31 is kept constant, the drive mechanism 40, or The load applied to the photosensitive drums 1a to 1d can be reduced, and the product life of the image forming apparatus 100 can be lengthened. In addition, even if the environment is approaching a high-temperature and high-humidity environment and the toner is gradually softened, it is possible to suitably suppress the toner from adhering and remaining on the photosensitive drums 1a to 1d.

Further, the reciprocating movement of the photosensitive drums 1a to 1d of the second embodiment can be changed by changing the reciprocating speed of the iron core 63 of the solenoid 60. FIG.

In addition, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention. For example, in each of the above-described embodiments, an example of application to a tandem color printer 100 using an intermediate transfer belt has been shown, but the present invention is not limited to this, and a direct transfer type printer that directly transfers a toner image onto a recording medium. and monochrome image forming apparatuses such as a monochrome copier and a monochrome printer.

In the configuration of the driving mechanism 40 of each of the above embodiments, the driving force is applied to the photosensitive drums 1a to 1d by projecting and retracting the iron core 63 of the solenoid 60. The configuration is not limited to the above-described embodiment, as long as it can reciprocate the photosensitive drums 1a to 1d in the axial direction by applying a directional driving force. For example, a configuration including a motor can be adopted instead of the solenoid 60 of the above embodiment. In this case, a link mechanism comprising a plurality of cams, gears, etc. is arranged between the motor and the photosensitive drums 1a to 1d. The rotational driving force of the motor is transmitted to the photosensitive drums 1a-1d via the link mechanism.

In addition, the control unit 90 according to the second embodiment may be configured to be capable of changing the speed of the reciprocating movement in four or more steps. In this case, four or more set values are defined for the number of temperature and humidity, and the control unit 90 executes speed change of the reciprocating movement of the photosensitive drums 1a to 1d so as to correspond to each set value.

INDUSTRIAL APPLICABILITY The present invention can be applied to image forming apparatuses such as copiers, printers, facsimiles, and multifunction devices using electrophotography. It can be used for an image forming apparatus that

1a to 1d photoreceptor drum (image carrier)
2a to 2d charging device 3a to 3d developing device 4 exposure device 6a to 6d primary transfer roller (transfer means)
8 intermediate transfer belt (intermediate transfer body)
9 secondary transfer roller (transfer means)
31 cleaning blade 40 drive mechanism 50 internal temperature and humidity sensor (temperature and humidity detector)
90 control unit 100 image forming apparatus S paper (recording medium)

Claims (6)

an image carrier having a cylindrical shape having a photosensitive layer formed on the outer peripheral surface thereof, and to which a rotating shaft passing through the central axis of the cylinder is connected;
a charging device that charges the photosensitive layer of the image carrier;
an exposure device that forms an electrostatic latent image by irradiating the image carrier charged by the charging device with a beam light;
a developing device that supplies a developer to the electrostatic latent image formed on the image carrier by the exposure device to form a toner image;
a transfer means for transferring the toner image formed on the image bearing member by the developing device onto a recording medium or an intermediate transfer member;
a cleaning blade that is pressed against the outer peripheral surface of the image carrier and cleans residual toner on the image carrier;
In an image forming apparatus comprising
a temperature/humidity detection device for detecting temperature and humidity around the image carrier;
a drive mechanism that reciprocates the image carrier or the cleaning blade along the direction of the rotation axis;
a control unit that executes the reciprocating movement when the temperature and humidity around the image carrier detected by the temperature/humidity detection device are equal to or lower than predetermined values;
An image forming apparatus comprising: 2. The image forming apparatus according to claim 1, wherein the drive mechanism reciprocates only the image carrier along the rotation axis direction. 3. The image forming apparatus according to claim 1, wherein the coefficient of friction of the outer peripheral surface of said image carrier is 0.2 or more and 0.8 or less. 4. The image forming apparatus according to claim 1, wherein the cleaning blade has a JIS-A hardness of 60 degrees or more and 80 degrees or less. 5. The reciprocating movement according to any one of claims 1 to 4, wherein the reciprocating movement is a periodic movement that makes one reciprocating motion per predetermined number of rotations of the image carrier, and the predetermined number of rotations is 10 or more and 200 or less. The image forming apparatus according to 1. 6. A method according to claim 5, wherein said controller reduces said predetermined number of revolutions when said image carrier makes one reciprocation as the temperature and humidity around said image carrier decrease from said predetermined values. image forming device.

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