JP2013114254A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress fluctuations in the voltage output of power supply based on fluctuations in load when a secondary transfer member is brought into contact with an intermediate transfer body while reducing a cost of device configuration and a space for component arrangement.SOLUTION: There is provided an image forming apparatus 50 which comprises: a rotatable intermediate transfer body 9; a secondary transfer roller 10 which is brought into contact with and separated from the intermediate transfer body 9 in order to transfer a toner image to a transfer material; an ICL roller 39 which is brought into contact with and separated from the intermediate transfer body 9 in order to recover toner remaining on the intermediate transfer body 9; and a high-voltage power supply part 400 for applying a voltage to a secondary transfer roller 10 and the ICL roller 39. A motor 217-2a brings both ends in a longitudinal direction of the ICL roller 39 into contact with and separating from the intermediate transfer body 9. When the ICL roller 39 is contacted with the intermediate transfer body 9, the other end in the longitudinal direction of the ICL roller 39 is contacted with the intermediate transfer body 9 after one end in the longitudinal direction of the ICL roller 39 is contacted with the intermediate transfer body 9.

Description

  The present invention relates to an image forming apparatus using an electrophotographic system, and relates to an image forming apparatus such as a copying machine, a printer, and a facsimile.

  Conventionally, yellow (Y), magenta (M), cyan (C), and black (Bk) photosensitive drums are arranged in series, and the toner images of each color are sequentially superimposed on the intermediate transfer member, and finally collectively. An image forming apparatus that secondarily transfers a toner image from an intermediate transfer member to a transfer material is known. In addition, in order to collect the toner remaining on the intermediate transfer member from the intermediate transfer member, the remaining toner is charged by a charging means contacting and separating from the intermediate transfer member, and the charged toner is moved from the intermediate transfer member to the photosensitive drum. The structure to make is also known conventionally.

  In Patent Document 1, when a secondary transfer member that contacts and separates from the intermediate transfer member contacts and separates from the intermediate transfer member, it is applied to the secondary transfer member to prevent the occurrence of minute discharge at the contact portion. A configuration is disclosed in which contact and separation are performed after the high voltage is turned off.

JP 2004-334120 A

  However, an image forming apparatus in which an applied member to which a voltage is applied from a power source such as a secondary transfer member or a charging member is brought into contact with and separated from an intermediate transfer member of a conventional image forming apparatus has the following problems. For example, when using a common power source for applying a voltage to the secondary transfer member or the charging member, the secondary transfer member in a separated state is applied to the intermediate transfer member while the voltage is being applied from the power source to the charging member. You may touch. In this case, when the secondary transfer member comes into contact with the intermediate transfer member, a load fluctuation occurs, and the voltage output of the power source may fluctuate.

  Although a configuration in which a power source for applying a voltage to the secondary transfer member and the charging member is provided separately can be considered, the cost increases. Further, since a power supply is required individually, it is necessary to secure a space for the power supply circuit.

  The present invention has been made under such circumstances. The power supply based on the load variation when the secondary transfer member comes into contact with the intermediate transfer member is achieved while reducing the apparatus configuration cost and the component arrangement space. The purpose is to suppress fluctuations in voltage output.

  In order to achieve the above object, the present invention has the following configuration.

  An image forming means for forming a toner image; a rotatable intermediate transfer member; a primary transfer member for primarily transferring the toner image from the image forming means to the intermediate transfer member; and for transferring the toner image to a transfer material. A secondary transfer member that contacts and separates from the intermediate transfer member; a toner charging member that contacts and separates from the intermediate transfer member to charge the toner remaining on the intermediate transfer member; the secondary transfer member and the toner A power supply unit that applies a voltage to the charging member; and a contact / separation unit that moves the toner charging member to contact and separate the toner charging member from the intermediate transfer member. An image forming apparatus that moves an applied toner charging member from a separated state to a contact state, wherein the contact / separation unit separates the toner charging member to which a voltage is applied by at least the power supply unit. When the toner charging member is moved from the contact state to the contact state, one end of the toner charging member in the longitudinal direction perpendicular to the rotation direction of the intermediate transfer member is brought into contact with the intermediate transfer member, and the other end is brought into contact with the intermediate transfer member. An image forming apparatus, wherein the toner charging member is moved so as to be in contact therewith.

  According to the present invention, it is possible to suppress fluctuations in the voltage output of the power source based on load fluctuations when the secondary transfer member comes into contact with the intermediate transfer member, while reducing the apparatus configuration cost and the component arrangement space.

Sectional drawing which shows the structure of the image forming apparatus of Example 1,2. The block diagram which shows the system configuration | structure of Example 1,2. FIG. 6 is a diagram illustrating an image forming operation according to the first and second embodiments. The figure explaining the system configuration | structure of the contact-separation mechanism of the charging member of Example 1, The figure which shows the rotation state of a cam The figure explaining the contact-separation state of the charging member of Example 1 6 is a flowchart for explaining a charging member contact sequence according to the first embodiment. The figure explaining the system configuration | structure of the contact-separation mechanism of the charging member of Example 2. FIG. The figure which shows the rotation state of the cam of Example 2. The figure explaining the contact-separation state of the charging member of Example 2. Flowchart for explaining a charging member contact sequence according to the second embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

  The configuration of the image forming apparatus will be described with reference to FIG.

<Configuration of image forming apparatus>
The drum unit 13 is configured integrally with an electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) 15 that is a drum-shaped image carrier and a cleaning container 14. The drum unit 13 is detachable from the image forming apparatus 50, and can be easily replaced according to the life of the photosensitive drum 15. A cleaner blade 16 and a conductive roller 17 that performs primary charging are disposed on the periphery of the photosensitive drum 15. The photosensitive drum 15 rotates in the direction of the arrow according to the image forming operation by the driving force of a driving roller (not shown). The surface of the photosensitive drum 15 is uniformly charged by bringing the conductive roller 17 as a drum charging member for the photosensitive drum into contact with the photosensitive drum 15 and applying a voltage to the conductive roller 17.

  The photosensitive drum 15 uniformly charged by the conductive roller 17 is exposed by a scanner unit 30 which is an exposure unit for forming an electrostatic latent image. When image information developed from an image (not shown) is received, a laser diode (not shown) of the scanner unit 30 irradiates the polygon mirror 31 with laser light corresponding to the image information. The polygon mirror 31 is rotated at a high speed by the scanner motor 31a, and the laser beam reflected by the polygon mirror 31 selectively exposes the surface of the photosensitive drum 15 rotating at a constant speed through the imaging lens 32 and the reflection mirror 33.

  The developing unit that forms a toner image on the photosensitive drum 15 develops the electrostatic latent image formed on the photosensitive drum 15 by the exposure unit with toner. The developing unit includes a yellow developing device 20Y, a magenta developing device 20M, a cyan developing device 20C, and a black developing device 20Bk that respectively store toners as developers of yellow, magenta, cyan, and black. Here, Y, M, C, and Bk mean that they correspond to each color of yellow, magenta, cyan, and black. Each of these developing devices is detachably held by a developing rotary 23 that rotates about a shaft 22. When a toner image is formed, each developing device is held by the developing rotary 23 and is centered on the shaft 22. Rotate. Then, after the developing roller of the developing device for the color to be developed stops at the developing position for applying toner to the photosensitive drum 15, a toner image is formed on the photosensitive drum 15. At the time of forming a color image, the developing rotary 23 rotates every rotation of the intermediate transfer member 9, and toner images are formed in the order of the yellow developing device 20Y, the magenta developing device 20M, the cyan developing device 20C, and the black developing device 20Bk. The intermediate transfer member 9 rotates four times to multiplex-transfer yellow, magenta, cyan, and black toner images, and as a result, a color image is formed on the intermediate transfer member 9. The intermediate transfer member 9 is rotatable in the direction of the arrow in the figure. FIG. 1 shows a state in which the yellow developing device 20Y is stopped at the developing position. The yellow developing device 20Y sends the toner to the application roller 20YR by a mechanism for sending the toner in the container. Then, a thin layer of toner is applied to the outer periphery of the developing roller 20YS rotating in the illustrated arrow direction by the coating roller 20YR rotating in the illustrated arrow direction and the blade 20YB pressed against the outer periphery of the developing roller 20YS. Charges (triboelectric charge). In this state, by applying a developing bias to the developing roller 20YS facing the photosensitive drum 15 on which the electrostatic latent image is formed, the electrostatic latent image formed on the photosensitive drum 15 is developed with toner. The magenta developing device 20M, the cyan developing device 20C, and the black developing device 20Bk are similarly developed with toner. Each developing roller of each color developing device is connected to a developing high-voltage power source or driving source provided for each color provided in the image forming apparatus 50 when the developing device for each color is moved to the developing position. A voltage is selectively applied sequentially for each development and driven.

  In order to multiplex-transfer the toner image formed on the photosensitive drum 15 in the developing unit by the primary transfer roller 41 (primary transfer member) forming the primary transfer unit, the intermediate transfer member 9 rotates in the direction of the arrow shown in the figure. Yes. By rotating the intermediate transfer member 9 four times, the toner images of each color are transferred in the order of yellow, magenta, cyan, and black, and a color image is formed on the intermediate transfer member 9. A non-image area on the outer periphery of the intermediate transfer member 9 is provided with a home position mark (hereinafter referred to as an HP mark) 9b that serves as a reference for the timing of starting image formation for each color, and an optical sensor 9a for detecting the home position mark. It has been.

  The cleaning unit cleans the toner remaining on the photosensitive drum 15 after the toner image formed on the photosensitive drum 15 is transferred to the intermediate transfer body 9 by the developing unit, and the cleaned toner is collected in the cleaning container 14. The

  The paper feed unit feeds a transfer material 2 as a transfer material, and is composed of a cassette 1 containing a plurality of transfer materials 2, a paper feed roller 3, and a resist roller pair 8. During the printing operation, the paper feed roller 3 is driven and rotated in accordance with the printing operation, feeds the transfer material 2 in the cassette 1 one by one, and reaches the registration roller pair 8. The registration roller pair 8 is provided with a shutter 11 for correcting the skew of the transfer material 2 conveyed to the registration roller pair 8 and detecting the leading edge for detecting that the transfer material 2 has reached the shutter 11. A sensor 6 is provided. The leading edge detection sensor 6 detects the leading edge of the transfer material 2 and conveys the transfer material 2 to the secondary transfer portion by the registration roller pair 8 in accordance with the timing of the printing operation. As a result, in the secondary transfer, which is the next step, the image formed on the intermediate transfer body 9 and the transfer material 2 can be aligned.

  The secondary transfer portion includes a secondary transfer roller 10 and a secondary transfer counter roller 5 that can be contacted and separated. Here, the secondary transfer roller is a member to be applied that is brought into contact with and separated from the intermediate transfer member 9 and to which a voltage is applied from the power supply unit. A high voltage is supplied to the secondary transfer roller 10 from a high-voltage power supply unit 400 (see FIG. 3). The secondary transfer roller 10 can be brought into and out of contact with the intermediate transfer member 9 as shown by a solid line state (separated state) and a broken line state (contact state). While the toner images of the respective colors are multiplex-transferred on the intermediate transfer member 9, the secondary transfer roller 10 is positioned below the solid transfer line so as not to disturb the toner image formed on the intermediate transfer member 9. It is away from the body 9. After the toner images of the respective colors are transferred onto the intermediate transfer member 9, the secondary transfer roller 10 moves to the position indicated by the broken line in accordance with the timing of secondary transfer of the image to the transfer material 2. The moved secondary transfer roller 10 and the secondary transfer counter roller 5 press the transfer material 2 and the intermediate transfer member 9 with a predetermined pressure. At the same time, a high voltage is applied to the secondary transfer roller 10 and the image on the intermediate transfer member 9 is transferred to the transfer material 2. Here, the intermediate transfer member 9 and the secondary transfer roller 10 are respectively driven to rotate, and the transfer material 2 sandwiched between the two is subjected to secondary transfer and at the same time, fixed to perform fixing in the next step. It is conveyed to the section 25.

  The fixing unit 25 includes a fixing roller 26 and a pressure roller 27 for fixing the image on the transfer material 2 by applying heat and pressure. The fixing roller 26 is pressurized by the pressure roller 27, and a fixing nip portion N having a predetermined width is formed with a predetermined pressing force. The transfer material 2 is conveyed from the secondary transfer portion so that the image surface faces the surface of the fixing roller 26. At this time, the temperature of the fixing nip N is controlled to a predetermined temperature, and the transferred transfer material 2 is heated by the fixing roller 26 and is heated and fixed by being pressed by the pressure roller 27. The The above is the configuration of each part of the image forming apparatus. Next, a series of operations in which the image forming apparatus performs image formation will be described.

  Next, an image forming operation will be described.

  First, the sheet feeding roller 3 is rotated to feed one sheet of the transfer material 2 in the cassette 1, conveyed to the registration roller pair 8, and waits until a color image is formed on the intermediate transfer member 9. In order to form an image, the surface of the photosensitive drum 15 is uniformly charged by the conductive roller 17, and an electrostatic latent image of a yellow image is first formed by the scanner unit 30. At the same time as the electrostatic latent image is formed, the yellow developing device 20Y is driven, so that the yellow toner adheres to the electrostatic latent image on the photosensitive drum 15 and has the same polarity as the charged polarity of the photosensitive drum 15 and a voltage of almost the same potential. Is applied for development. In order to primarily transfer the toner image formed on the photosensitive drum 15 to the intermediate transfer member 9, a voltage having a characteristic opposite to that of the toner image formed on the photosensitive drum 15 is applied to the primary transfer roller 41 from a power source. 15 toner images are primarily transferred onto the intermediate transfer member 9. When the yellow toner image is primarily transferred to the intermediate transfer body 9, the development rotary 23 rotates, and the magenta developing device 20 </ b> M that performs image formation next rotates to move the development position for image formation on the photosensitive drum 15. To stop. A magenta toner image is formed on the electrostatic latent image formed by charging and exposing the photosensitive drum 15 in the same manner as yellow. The toner image formed on the photosensitive drum 15 is primarily transferred to the intermediate transfer member 9 in the same manner as yellow. Next, formation of electrostatic latent images of cyan and black, development, and primary transfer to the intermediate transfer member 9 are performed, and toner images of four colors of yellow, magenta, cyan, and black are transferred onto the surface of the intermediate transfer member 9 in a multiple manner. An image is formed.

Then, after a color image is formed on the intermediate transfer member 9, the transfer material 2 that has been kept on standby by the registration roller pair 8 is conveyed. The transfer material 2 is pressed into contact with the intermediate transfer body 9 by the secondary transfer roller 10 and the secondary transfer counter roller 5, and at the same time, a bias having a characteristic opposite to that of the toner is applied to the secondary transfer roller 10. The color image is transferred to the transfer material 2.
After the color image is transferred from the intermediate transfer member 9 to the transfer material 2, residual toner is generated on the intermediate transfer member 9 without being secondarily transferred to the transfer material 2. This residual toner needs to be collected from the intermediate transfer member 9 in preparation for the next image formation. In this embodiment, the residual toner is transferred to an intermediate transfer member by a charging roller (hereinafter referred to as an ICL roller) 39 which is a stick-shaped toner charging member that charges the residual toner to a polarity opposite to the charging polarity of the toner at the time of development. Collect from 9.
The ICL roller 39 abuts on the intermediate transfer member 9 at the position of the broken line in FIG. Here, the ICL roller, which is a toner charging member, is a member to be applied that is in contact with and separated from the intermediate transfer member 9 and to which a voltage is applied from the power supply unit.

  A high voltage is supplied to the ICL roller 39 from the high-voltage power supply unit 400 (see FIG. 3). The high voltage power supply unit 400 is the same as the high voltage power supply unit 400 that supplies a high voltage to the secondary transfer roller 10 described above. After charging the residual toner, the ICL roller 39 is separated from the intermediate transfer member 9 (the position indicated by the solid line in the figure). When continuous image formation is performed, the yellow toner image of the next image is formed on the photosensitive drum 15 while the ICL roller 39 contacts the intermediate transfer member 9 and charges the residual toner. The When the formed image is primarily transferred onto the intermediate transfer member 9 and passes the contact position of the ICL roller 39, the ICL roller 39 is separated from the intermediate transfer member 9.

  The residual toner charged by the ICL roller 39 is electrostatically transferred to the photosensitive drum 15 at the primary transfer portion where the photosensitive drum 15 and the intermediate transfer body 9 are in contact with each other, and is collected in the cleaning container 14 by the cleaner blade 16. When image formation is continuously performed on a plurality of transfer materials 2, the residual toner is transferred to the photosensitive drum 15, and the yellow toner image which is the first color of the next image is transferred from the photosensitive drum 15 to the intermediate transfer. The primary transfer to the body 9 may be performed simultaneously.

  After the secondary transfer of the color image from the intermediate transfer member 9 to the transfer material 2 is completed, the secondary transfer roller 10 is separated from the intermediate transfer member 9. In the case where the next image (second page) is printed while the transfer material 2 is nipped and conveyed between the secondary transfer roller 10 and the intermediate transfer member 9 and the color image is secondarily transferred. Then, the yellow toner image of the next image is formed on the photosensitive drum 15. After the yellow toner image is formed on the photosensitive drum 15, the secondary transfer roller 10 holds the transfer material 2 between the intermediate transfer body 9 and before the next magenta toner image starts to be formed. Move from the contact position to the separation position. After the transfer material 2 is peeled off from the intermediate transfer member 9, the transfer material 2 is conveyed to the fixing unit 25, fixed at the fixing nip portion N, and then transferred onto the discharge tray 37 at the top of the main body via the discharge roller pair 36. The sheet is discharged downward, and the image forming operation ends.

  FIG. 2 is a block diagram for explaining the system configuration of the image forming apparatus. The host computer 200 transmits print data (character code, graphic data, image data, process conditions, etc.) described in a page description language such as PCL to the controller unit 201. The controller unit 201 receives print data from the host computer 200. The received print data is sequentially analyzed for each color, and image information that is a bitmap composed of dot data necessary for forming an image by the image forming apparatus 50 (hereinafter referred to as image development) is generated. Sequentially. Here, as an example, a method of performing image development by the controller unit 201 has been described. However, image development is not necessarily performed by the controller unit 201, for example, image development is performed by the host computer 200 and image information is transmitted to the controller unit 201. May be. The engine unit 202 forms an image based on image information sequentially input from the controller unit 201. Therefore, the electrostatic latent image is formed on the photosensitive drum 15, the toner image is formed for each color, the primary transfer and the secondary transfer. A series of image forming operations such as fixing processing is controlled. Processing from the formation of the electrostatic latent image to primary transfer (hereinafter referred to as printing operation) is performed in parallel with the above-described image development. The video interface unit 210 connects the engine unit 202 and the controller unit 201. The video interface unit 210 includes a serial communication unit 203 and an image formation signal unit 204. The serial communication unit 203 receives a command or signal transmitted from the controller unit 201 to the engine unit 202, and transmits a signal requesting the status of the image forming apparatus or image information from the engine unit 202 to the controller unit 201. . The image formation signal unit 204 receives image information transmitted from the controller unit 201 to the engine unit 202.

  The CPU 211 controls each control unit and communication unit in the engine unit 202, and compares data sent to the controller unit 201 with data held in a ROM (not shown) of the engine unit 202. The CPU 211 performs serial communication with the video interface unit 210. The CPU 211 is a drive that controls a sensor control unit 218 that controls an optical sensor 9 a that detects the HP mark 9 b on the intermediate transfer member 9, a main motor 219 that drives the intermediate transfer member 9, the photosensitive drum 15, and the development rotary 23. The control unit 217 is controlled. The drive control unit 217 includes a motor driver (see FIG. 4A) of a motor (drive unit) for bringing both ends of the ICL roller 39 into and away from the intermediate transfer member 9. Further, the CPU 211 generates a vertical synchronization signal (/ TOP signal) 220 for starting a printing operation. Further, the CPU 211 controls the image formation control unit 212 that controls the horizontal synchronization signal (/ BD signal) 221 and the image data (Video signal) 222 between the video interface unit 210 and the scanner unit 30. Further, the CPU 211 controls the fixing control unit 213, the paper feed control unit 214, the high voltage control unit 215, and the nonvolatile memory control unit 216, respectively. Finally, the CPU 211 controls a solenoid drive circuit 1201 for driving a solenoid (see FIG. 4A) described later, and receives a signal from a photo interrupter 3000 described later.

  As in this embodiment, the development rotary 23 rotates every rotation of the intermediate transfer body 9, and development is performed sequentially, so that the toner image is multiplex-transferred to the intermediate transfer body 9 to form a color image. In the apparatus, it is necessary to perform primary transfer from the same position on the intermediate transfer member 9. This is because if the primary transfer is not performed from the same position on the intermediate transfer member 9, the toner images of the respective colors are shifted and primarily transferred to the intermediate transfer member 9, and the image cannot be formed correctly. is there. Therefore, the HP mark 9b provided on the circumference of the intermediate transfer member 9 is detected by the optical sensor 9a. The engine unit 202 transmits a / TOP signal 220 to the controller unit 201 at the timing when the HP mark 9b is detected by the optical sensor 9a. The controller unit 201 that has received the / TOP signal 220 transmits image information generated by image expansion to the engine unit 202. The engine unit 202 can perform multiple transfer to the same position on the intermediate transfer body 9 by forming an image of each color based on the received image information.

  Specifically, the engine unit 202 transmits the first color (yellow) / TOP signal 220 to the controller unit 201 at the timing when the optical sensor 9 a detects the HP mark 9 b. The controller unit 201 that has received the / TOP signal 220 transmits yellow image information obtained by developing the image to the engine unit 202. The engine unit 202 that has received the image information forms an electrostatic latent image on the photosensitive drum 15 based on the image information, and develops the formed electrostatic latent image with toner. Then, the toner image formed on the photosensitive drum 15 is primarily transferred to the intermediate transfer member 9. As described above, since the printing operation is started with the HP mark 9b as a reference, the time from when the HP mark 9b is detected and the / TOP signal 220 is transmitted to when the toner image of each color is first transferred can be made constant. Therefore, multiple transfer can be performed at the same position on the intermediate transfer member 9.

  Thereafter, similarly to yellow, a magenta / TOP signal 220 is transmitted to the controller unit 201 at the timing when the optical sensor 9a detects the HP mark 9b. Similarly, for cyan and black, four colors are transferred to the same position on the intermediate transfer body 9 by transmitting the / TOP signal 220 at the timing when the optical sensor 9a detects the HP mark 9b.

  When the peripheral length of the intermediate transfer member 9 is shortened in order to reduce the size of the image forming apparatus, the secondary transfer roller 10 and the ICL roller 39 need three contact / separation positions as shown in FIG. First, during the primary transfer of the four colors, the secondary transfer roller 10 and the ICL roller 39 are both in the first position (FIG. 3A). Thereafter, when starting the secondary transfer, since the trailing edge of the toner image on the intermediate transfer member 9 does not pass through the ICL roller 39, only the secondary transfer roller 10 is brought into contact with the ICL roller 39 to be separated. The second position is obtained (FIG. 3B). In this state, no voltage is applied to the primary transfer roller 41. When the rear end of the toner image on the intermediate transfer member 9 passes through the ICL roller 39 after the start of the secondary transfer, the ICL roller 39 is also in the third position where it contacts (FIG. 3C). Even in this state, no voltage is applied to the primary transfer roller 41. When the residual toner after the secondary transfer passes through the ICL roller 39, the first position is again set in preparation for the next printing. Here, when a common power supply unit (high-voltage power supply unit 400 in the present embodiment) is used for the ICL roller 39 and the secondary transfer roller 10, when the transition from the start of the secondary transfer described above to the start of the secondary transfer is performed. The ICL roller 39 comes into contact with the intermediate transfer member 9 in a state where a voltage is applied.

  When the ICL roller 39 in a state where a voltage is applied is brought into contact with the intermediate transfer member 9, if the entire contact surface of the ICL roller 39 is brought into contact with the intermediate transfer member 9 at a time, a secondary load is caused by a sudden load fluctuation. The output value of the high-voltage power supply unit 400 that applies a voltage to the transfer roller 10 changes. As a result, a secondary transfer failure or the like may occur.

  As a countermeasure against the contact and separation of the toner charging member to which the voltage is applied from the high-voltage power supply unit 400 with respect to the intermediate transfer body 9, a part of the contact surface of the ICL roller 39 is first brought into contact with the intermediate transfer body 9, Next, the remaining part of the ICL roller 39 is brought into contact with the intermediate transfer member 9. With this configuration, output fluctuations of the high-voltage power supply unit 400 that applies the voltage of the secondary transfer roller 10 can be suppressed. A specific configuration for suppressing high voltage output fluctuation is shown below.

  The configuration of the contact / separation portion of the ICL roller 39 and the contact / separation operation, which are characteristic parts of the present embodiment, will be described.

  First, a system configuration for contacting and separating the ICL roller 39 will be described with reference to FIG. The left and right ends of the longitudinal axis of the ICL roller 39 are urged by springs 1102a and 1102b which are elastic bodies. The springs 1102a and 1102b, which are elastic bodies, are pressed against the intermediate transfer body 9 by being pressed by the cams 1100a and 1100b. The longitudinal direction refers to a direction orthogonal to the rotation direction of the intermediate transfer member 9. Here, since the left and right ends of the ICL roller shaft are controlled to move in the same manner on the left and right, only the case where the spring 1102a is pressed and controlled will be described here, and the description of the movement control of the spring 1102b will be omitted. To do. In the spring 1102a, the pressing state of the spring is determined by the state of the cam 1100a. The cam 1100a is connected to the toothless gear 1202a by a camshaft 2050a (first camshaft). The cam 1100b is connected to the toothless gear 1202b by a camshaft 2050b (second camshaft). In the missing gear 1202a, when the solenoid 1200a performs a suction operation for a certain period of time, the claw is disengaged from the hooking portion (not shown) of the missing gear 1202a, and the power of the motor 217-2a is lost via the drive gear 1203a. It is transmitted to the gear 1202a. The toothless gear 1202a is configured to rotate 1/2 by one suction operation of the solenoid 1200a. Accordingly, the contact / separation state sequentially changes between the two states by driving the solenoid 1200a. The contact state of the cam 1100a is notified to the CPU 211 by the photo interrupter 3000a that detects the position of the cam 1100a. The solenoid 1200a is driven by a signal output from the CPU 211 via the solenoid drive circuit 1201a.

  Next, a cam structure is demonstrated in detail using FIG.4 (b) and FIG.4 (c). Here, since the cams 1100a and 1100b have the same configuration, the configuration of the cams 1100a and 1100b will be described together as the cam 1100. As shown in FIG. 4B and FIG. 4C, the cam has two surfaces (1111 and 1112) according to the distance from the rotation center. The contact / separation state of the ICL roller 39 is determined depending on whether the ICL is directed. As shown in FIG. 4B, when the surface 1111 faces the spring 1102, the spring 1102 is not pressed, so the ICL roller 39 is in a separated state. At this time, the photo interrupter 3000 notifies the CPU 211 of the cam separation state (rotation phase) as a detection result. In this embodiment, the rotational phase of the cam is directly detected by the photo interrupter 3000. As shown in FIG. 4C, when the surface 1112 faces the spring 1102, the spring 1102 is pressed, and the ICL roller 39 is in contact. Also in this case, the contact state of the cam is notified to the CPU 211 by the photo interrupter 3000.

  Next, the contact / separation state of the ICL roller 39 will be described in detail with reference to FIG. As shown in FIG. 5, the ICL roller 39 has three states of contact and separation.

  FIG. 5A shows a state in which the ICL roller 39 is separated from the intermediate transfer member 9. In this state, the cam 1100a has the surface 1111 facing the spring, and the cam 1100b also has the surface 1111 facing the spring.

  FIG. 5B shows a state in which one end of the ICL roller contact surface is in contact with the intermediate transfer member 9. In this state, the cam 1100a has the surface 1111 facing the spring, and the cam 1100b (first cam) has the surface 1112 in contact with the spring. Therefore, only the right end (one end) of the ICL roller 39 is in contact with the intermediate transfer member by the spring 1102b, and the left end (the other end) is separated. Note that the right end and the left end of the ICL roller 39 refer to left and right ends when the ICL roller 39 is viewed from the circumferential movement direction of the intermediate transfer member 9.

  FIG. 5C shows a state in which all the ICL roller contact surfaces are in contact with the intermediate transfer member 9. In this state, the cam 1100a (second cam) has the surface 1112 in contact with the spring, and the cam 1100b also has the 1112 surface in contact with the spring.

  Finally, the contact sequence of the ICL roller 39 will be described with reference to the flowchart of FIG. This sequence is a control sequence in which the live ICL roller 39 is brought into contact with the intermediate transfer member 9 after the start of image formation. At the start of this sequence, both the cam 1100a and the cam 1100b are separated from the springs 1102a and 1102b (hereinafter referred to as separated positions) corresponding to the positions where the ICL roller 39 is separated from the intermediate transfer body 9. It shall be. In S100, the CPU 211 receives the output signal of the photo interrupter 3000a. In S101, the CPU 211 determines whether or not the cam 1100a is in the separated position. When the CPU 211 determines in S101 that the cam 1100a is in the separated position, the CPU 211 receives the output signal of the photo interrupter 3000b in S102. In S103, the CPU 211 determines whether the cam 1100b is in the separated position. If the CPU 211 determines in S103 that the cam 1100b is in the separated position, the CPU 211 drives the solenoid 1200b in S104 to bring the right end of the ICL roller 39 into contact with the intermediate transfer member 9 (see FIG. 5B). Next, in S105, the solenoid 1200a is driven to bring the left end of the ICL roller 39 into contact with the intermediate transfer member 9 (see FIG. 5C), and the process ends. Thus, the ICL roller 39 transitions from the separated state to the contact state. If the CPU 211 determines in S101 that the cam 1100a is not in the separation position, the CPU 211 stops image formation in S106, transmits information on the ICL roller separation failure to the controller unit 201, and ends. If the CPU 211 determines in S103 that the cam 1100b is not in the separation position, the CPU 211 stops image formation in S106, transmits information on the ICL roller separation failure to the controller unit 201, and ends. Thus, after the start of image formation, the control for moving the live ICL roller 39 to the intermediate transfer member 9 is completed. According to this embodiment, the contact surface of the ICL roller 39 in the high voltage application state with the intermediate transfer member 9 is sequentially controlled to prevent a sudden change in the load impedance, thereby changing the high voltage output of the secondary transfer roller 10. Can be reduced.

  According to this embodiment, it is possible to suppress fluctuations in the voltage output of the power source based on load fluctuations when the secondary transfer member comes into contact with the intermediate transfer member, while reducing the apparatus configuration cost and the component arrangement space.

  In the first embodiment, since the two types of cams (1100a, 1100b) have cam shafts (2050a, 2050b) independently, two types of solenoids and solenoid drive circuits for driving the cams are required. . In this embodiment, the shape of the two types of cams (2100a, 2100b) is devised, and the camshaft is used in common, thereby reducing the cost by using a single cam drive configuration.

  In the present embodiment, the three states of the ICL roller 39 can be determined by one camshaft, so there is only one cam drive configuration. Also in the present embodiment, as shown in FIG. 7, the spring 2102a and the spring 2102b are determined in a spring pressing state by the states of the cam 2101a and the cam 2101b. However, the cams 2101 a and 2101 b are connected to one camshaft 2100, and the camshaft 2100 is connected to a missing gear 2202. In the missing gear 2202, when the solenoid 1200 a performs a suction operation for a certain period of time, the claw is disengaged from the hooking portion (not shown) of the missing gear 2202, and the power of the motor 217-2 a is lost via the drive gear 2203. It is transmitted to the tooth gear 2202. Furthermore, the missing gear 2202 is configured to rotate 1/3 by one suction operation of the solenoid 1200a. Accordingly, the contact / separation state sequentially changes among the three states by driving the solenoid. For example, the contact / separation state of the ICL roller 39 changes from separation → right end contact → left / right end contact → separation.

  First, the cam configuration will be described in detail. As shown in FIG. 8, two types of cams (2101 a and 2101 b) are connected to one camshaft 2100. And it has three surfaces (2110, 2111, 1122) according to the distance from the rotation center of the camshaft 2100, and an ICL roller according to which surface is directed to the spring 2102a and the spring 2102b. The contact / separation state of 39 is determined. As shown in FIG. 8A, when the surface 2112 faces the spring, the spring 2102a and the spring 2102b are not pressed, so the ICL roller 39 is in a separated state. As shown in FIG. 8B, when the surface 2111 faces the spring, the spring 2102a is not pressed and the spring 2102b is pressed, so that the ICL roller 39 is in contact with only the right end. As shown in FIG. 8C, when the surface 2110 faces the spring, the spring 2102a and the spring 2102b are pressed, so that the ICL roller 39 is in contact with both the left and right ends. The camshaft 2100 is provided with a flag 3003 and a flag 3004, and the contact / separation state of the ICL roller 39 can be detected by detecting the flag with the photo interrupter 3001 and the photo interrupter 3002. Here, the output of the photo interrupter with respect to the contact / separation state of the ICL roller 39 is shown in Table 1 below. The data in Table 1 is stored in a ROM (not shown) or the like of the engine unit 202, and is read by the CPU 211 at any time and used for movement / separation control of the ICL roller 39.

  Next, the contact / separation state of the ICL roller will be described in detail with reference to FIG. As shown in FIG. 9, the ICL roller has three states of contact and separation.

  FIG. 9A shows a state in which the ICL roller 39 is separated from the intermediate transfer member 9. In this state, since the camshaft 2100 has the surface 2112 facing the spring, the spring 2102a has the left end of the ICL roller in the separated state, and the spring 2102b has the right end of the ICL roller in the separated state.

  FIG. 9B shows a state where one end of the ICL roller contact surface is in contact. In this state, since the camshaft 2100 has the surface 2111 facing the spring, the spring 2102a has the left end of the ICL roller in a separated state, and the spring 2102b has the right end of the ICL roller in contact.

  FIG. 10C shows a state where all of the ICL roller contact surfaces are in contact. In this state, since the camshaft 2100 has the surface 2110 facing the spring, the spring 2102a is in contact with the left end of the ICL roller, and the spring 2102b is in contact with the right end of the ICL roller.

  Finally, the contact sequence of the ICL roller will be described with reference to the flowchart of FIG. As in the first embodiment, at the start of this sequence, the cam 2101a and the cam 2101b are in the separated position, and the ICL roller 39 is in the separated state with respect to the intermediate transfer member 9.

  In this sequence, a description will be given of the control for bringing the ICL roller 39 in a live state into contact with the intermediate transfer member 9 after the start of image formation. In step S200, the CPU 211 receives output signals from the photo interrupter 3001 and the photo interrupter 3002. In S201, the CPU 211 determines whether the camshaft 2100 is in the separated position with reference to the output signals of the two photo interrupters (3001, 3002) and Table 1. If the camshaft 2100 is in the separated position in S201, the CPU 211 drives the solenoid 1200a in S202 to bring the right end of the ICL roller 39 into contact with the intermediate transfer member 9 (see FIG. 9B). In step S203, the CPU 211 drives the solenoid 1200a to bring the left end of the ICL roller 39 into contact with the intermediate transfer member 9 (see FIG. 9C), and ends the control. Thus, the ICL roller 39 transitions from the separated state to the contact state. Here, if the camshaft 2100 is not in the separation position in S201, the CPU 211 stops image formation in S204, informs the controller unit 201 of information on the ICL roller separation failure, and ends the control. Thus, after the image formation is started, the control for bringing the ICL roller 39 in the live state into contact with the intermediate transfer member 9 is completed. According to the present embodiment, the solenoid drive circuit and the solenoid can be made one, and the cost can be reduced.

  According to this embodiment, it is possible to suppress fluctuations in the voltage output of the power source based on load fluctuations when the secondary transfer member comes into contact with the intermediate transfer member, while reducing the apparatus configuration cost and the component arrangement space.

9 Intermediate transfer member 10 Secondary transfer roller 39 ICL roller 400 High voltage power supply unit 211 CPU

Claims (7)

An image forming means for forming a toner image; a rotatable intermediate transfer member; a primary transfer member for primarily transferring the toner image from the image forming means to the intermediate transfer member; and for transferring the toner image to a transfer material. A secondary transfer member that contacts and separates from the intermediate transfer member; a toner charging member that contacts and separates from the intermediate transfer member to charge the toner remaining on the intermediate transfer member; the secondary transfer member and the toner A power supply unit that applies a voltage to the charging member; and a contact / separation unit that moves the toner charging member to contact and separate the toner charging member from the intermediate transfer member. An image forming apparatus that moves the applied toner charging member from a separated state to a contact state,
The abutting / separating portion is a longitudinal direction orthogonal to the rotation direction of the intermediate transfer body of the toner charging member when at least the toner charging member to which a voltage is applied by the power supply unit is moved from the separating state to the abutting state. An image forming apparatus, wherein the toner charging member is moved so that one end of the toner contacts the intermediate transfer member and the other end contacts the intermediate transfer member. The abutting / separating portion includes a first cam and a second cam that abut against and separate from an elastic body that urges both ends in the longitudinal direction of the toner charging member, and the first cam and the second cam. A driving unit for driving, and a first cam shaft and a second cam shaft for transmitting the driving force of the driving unit to the first cam and the second cam, respectively.
When the toner charging member comes into contact with the intermediate transfer member, the contact / separation portion drives the drive unit, and drives the first cam via the first cam shaft, thereby charging the toner. One end of the member in the longitudinal direction is brought into contact with the intermediate transfer member, and then the second cam is driven via the second cam shaft so that the other end in the longitudinal direction of the toner charging member is connected to the intermediate transfer member. The image forming apparatus according to claim 1, wherein the image forming apparatus is brought into contact with a transfer body. The abutting / separating portion includes a first cam and a second cam that abut against and separate from an elastic body that urges both ends in the longitudinal direction of the toner charging member, and the first cam and the second cam. A driving unit for driving, and one camshaft for transmitting the driving force of the driving unit to the first cam and the second cam,
When the toner charging member comes into contact with the intermediate transfer member, the contact / separation portion drives the drive unit, and drives the first cam via the cam shaft, whereby the length of the toner charging member is increased. One end of the toner charging member is brought into contact with the intermediate transfer member, and then the second cam is driven via the camshaft to bring the other end in the longitudinal direction of the toner charging member into contact with the intermediate transfer member. The image forming apparatus according to claim 1, wherein:   The image forming apparatus according to claim 2, wherein the first cam and the second cam have two contact surfaces according to a distance from a rotation center. Detecting means for detecting a rotational phase of the first cam and the second cam;
The image forming apparatus according to claim 2, wherein the contact / separation unit is controlled based on a detection result of the detection unit.   6. The image forming apparatus according to claim 5, wherein the detection unit is a photo interrupter that detects a rotation phase of the first cam and the second cam. Having a flag installed on the camshaft;
The image forming apparatus according to claim 5, wherein the detection unit detects a rotation phase of the first cam and the second cam by detecting the flag.

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