JP4608975B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine and a printer, and more particularly to an image forming apparatus including a transfer conveyance belt that transfers a toner image while electrostatically attracting and conveying a transfer material.

  In an image forming apparatus such as a copying machine or a printer using an electrophotographic system, for example, a photosensitive member (photosensitive drum) formed in a drum shape is uniformly charged, and the photosensitive drum is controlled based on image information. An electrostatic latent image is formed on the photosensitive drum by exposure with the exposed light. The electrostatic latent image is converted into a visible image (toner image) with toner, and the toner image is transferred from the photosensitive drum to a transfer material by a transfer device, and then heated and pressed by a fixing device to form the toner image. It is fixed on the transfer material.

In a transfer device used in such an image forming apparatus, in recent years, a transfer conveyance belt is brought into contact with a photosensitive drum, a transfer material is sandwiched in a contact area between the transfer conveyance belt and the photosensitive drum, and the transfer conveyance is performed. A transfer system is employed in which a transfer bias is applied to the belt to transfer the toner image on the photosensitive drum.
In the transfer device using such a transfer conveyance belt, compared with the conventional corona charging method, a high-voltage power supply is not required, so that the device can be downsized and the manufacturing cost can be reduced. In addition, there is an advantage that the generation of ozone is extremely small, and in addition, the transfer performance is stable against dirt caused by adhesion of paper dust or toner. Furthermore, it is possible to configure the unit around the transfer conveyance belt so that it can be brought into and out of contact with the photosensitive drum, or to be pulled out from the front side of the image forming apparatus. Jam processing when (jam) occurs is easy. In addition, the occupation area of the image forming apparatus can be reduced.

  However, in the transfer apparatus using the transfer conveyance belt, the transfer material conveyed from the conveyance roll is stable with high positional accuracy with respect to the contact area (transfer area) between the transfer conveyance belt and the photosensitive drum. If it is not sent to the transfer material, transfer defects such as image displacement may occur on the transfer material. For this purpose, it is necessary to position the transfer entrance guide for guiding the transfer material to the contact area between the transfer conveyance belt and the photosensitive drum with high accuracy. In addition, a paper jam (jam) may also occur in this transfer entrance guide, and it is necessary to have a configuration that can easily perform jam processing at that time.

Here, as a conventional technique for accurately conveying the transfer material to the transfer region, a guide member configured to be movable forward and backward with respect to the photosensitive drum at the upstream side in the transfer material conveyance direction of the nip position between the photosensitive drum and the transfer roll. There is a technique in which the guide member is urged toward the photosensitive member by the urging member, and the guide member is positioned at a predetermined position by the positioning member (see, for example, Patent Document 1).
In addition, as a conventional technique for facilitating the jam processing in the transfer area, the sheet conveying means is divided into three members, a transfer corotron section, an upstream conveying apparatus section, and a downstream conveying apparatus section, and these are oscillated with each other. Connect as possible. Then, the downstream conveying device is supported so as to be swingable with respect to the main body frame, and by swinging this, the other members are interlocked to swing, thereby forming a space below the image carrier. In addition, there is a technique in which the upstream side transport device unit is pushed down in conjunction with each other (see, for example, Patent Document 2).

JP-A-10-104960 (page 2-4) JP-A-3-267970 (page 5-6)

However, in the configuration in which the guide member (transfer entrance guide) is fixedly arranged with respect to the photosensitive drum as in the technique described in Patent Document 1, the positional accuracy with respect to the photosensitive drum can be set satisfactorily. However, since the transfer entrance guide that guides the transfer material to the transfer area cannot be easily released from the photosensitive drum, there is a disadvantage that the jam handling is difficult when a paper jam occurs in the transfer entrance guide. It was.
Further, as in the technique described in Patent Document 2, in the configuration in which the sheet conveying means is divided into a plurality of members and these members are swung while interlocking, the transfer entrance guide is easily released from the photosensitive drum. Therefore, the jam processing is easy, but the configuration is complicated, and there is an inconvenience that the apparatus becomes large and the manufacturing cost increases.

Accordingly, the present invention has been made to solve the above technical problems, and an object of the present invention is to accurately convey a transfer material to a transfer region with a simple configuration.
Another object is to realize a configuration capable of easily performing a paper jam processing.

  For this purpose, the image forming apparatus of the present invention includes a toner image carrier that carries a toner image, and a transfer conveyance unit that transfers the toner image carried by the toner image carrier to a transfer material and conveys the transfer material. And a housing holding the transfer conveyance means, and a housing integrally joined to the upstream side of the transfer material in the conveyance direction, supporting one surface of the transfer material, and transferring the transfer material between the toner image carrier and the transfer conveyance means. And a guide member that leads to the contact portion.

Here, the housing can be configured to be swingable so that the toner image carrier and the transfer conveying means are brought into contact with and separated from each other. Further, on the upstream side of the transfer material conveyance direction of the housing, the other surface of the transfer material, which is configured separately from the housing, is regulated so that the transfer material is brought into contact with the toner image carrier and the transfer conveyance means. The guide member may further include a guiding guide member, and the guide member may be in contact with the regulating guide member with a predetermined gap at a position where the housing abuts the transfer conveying unit against the toner image carrier.
In addition, the guide member may include a swinging portion that swings an upstream portion of the guide member in the conveyance direction of the transfer material. In this case, the swinging portion of the guide member can be disposed in the vicinity of the upstream side in the conveyance direction of the transfer material at the joint portion with the housing. Further, the swinging portion of the guide member may be configured to have a lower rigidity than the upstream portion of the guide member in the conveyance direction of the transfer material. Further, the swinging portion of the guide member may be formed to be thinner than the upstream portion of the guide member in the conveyance direction of the transfer material.

  The image forming apparatus of the present invention includes a toner image carrier that carries a toner image, a transfer conveyance unit that transfers the toner image carried by the toner image carrier to a transfer material, and conveys the transfer material, and a transfer material A guide member for guiding the toner image carrier to the contact portion between the toner image carrier and the transfer conveying means, a first guide portion for restricting one surface of the transfer material, and a second guide portion for supporting the other surface of the transfer material; The second guide portion of the guide member is in contact with the first guide portion while being elastically deformed.

  Here, the second guide portion of the guide member may be arranged on a support body that holds the transfer conveyance means. Further, the toner image carrier and the transfer conveying means are configured to be able to contact and separate, and the first guide portion and the second guide portion of the guide member are mutually connected when the transfer conveying means comes into contact with the toner image carrier. It can be characterized by abutting. Further, the second guide portion of the guide member may be characterized in that the rigidity of the upstream portion in the conveyance direction of the transfer material is high and the rigidity of a portion of the downstream portion in the conveyance direction is low. Furthermore, the second guide portion of the guide member may have a portion formed at a portion of the transfer material downstream in the transport direction that is thinner than the upstream portion in the transport direction.

  As an effect of the present invention, it is possible to obtain a good transfer image without image misalignment or the like by accurately transporting the transfer material to the transfer region with a simple configuration. In addition, paper jam processing can be facilitated and high operability can be realized.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus to which the exemplary embodiment is applied. The image forming apparatus shown in FIG. 1 includes a charger 11 that charges the photosensitive drum 10 around the photosensitive drum 10 as an example of a toner image carrier that rotates in the direction of arrow A, and an electrostatic image on the photosensitive drum 10. Laser exposure device 12 for writing the latent image (exposure beam is indicated by Bm in the figure), developing device 13 for storing the toner and making the electrostatic latent image on the photosensitive drum 10 visible with the toner, transfer unit Before the electrostatic transfer at 15, a pre-transfer charger 14 that charges the toner image on the photoconductive drum 10, and a recording paper (paper) P that is a transfer material in the transfer unit 15 for the toner image formed on the photoconductive drum 10. A transfer unit 20 for transferring the toner image, an image density sensor 18 for adjusting an image density disposed in the vicinity of the photosensitive drum 10 on the downstream side of the transfer unit 15, and a charge amount of residual toner after electrostatic transfer is reduced. Chestnut Training electrifier 16 for electrophotography and a drum cleaner 17 which residual toner on the photosensitive drum 10 is removed is provided. Further, a fixing device 60 for fixing the unfixed toner image transferred onto the paper P and a control unit 30 for controlling the operation of each device (each unit) are provided.

  The transfer unit 20 is disposed inside the transfer conveyance belt 21 stretched between the drive roll 22 and the idle roll 23, and is in pressure contact with the photosensitive drum 10 via the transfer conveyance belt 21. And a transfer roll 24. Further, it has a function of transferring the toner image on the photosensitive drum 10 to the paper P conveyed to the transfer unit 15 and a function of conveying the paper P on which the toner image has been transferred in the transfer unit 15 to the fixing device 60. is doing.

  The image forming apparatus according to the present embodiment also includes a paper tray 50 that stores paper P, a pickup roll 51 that picks up and transports the paper P accumulated in the paper tray 50 at a predetermined timing, and a pickup as a paper transport system. A transport roll 52 that transports the paper P fed by the roll 51, a registration roll 54 that feeds the transported paper P to the transfer unit 15 at a predetermined timing, and a transport that guides the paper P transported by the transport roll 52 to the registration roll 54. A chute 53, an inlet chute 55 that guides the paper P fed from the registration roll 54 to the transfer unit 15, and a fixing inlet guide 56 that guides the paper P on which the toner image is transferred by the transfer unit 20 to the fixing device 60 are provided. ing.

  Next, a basic image forming process of the image forming apparatus according to the present embodiment will be described. In the image forming apparatus as shown in FIG. 1, image data output from an image reading device (IIT) not shown or a personal computer (PC) not shown is subjected to predetermined image processing by an image processing device not shown. . In the image processing apparatus, the input reflectance data is subjected to predetermined image processing such as various kinds of image editing such as shading correction, position shift correction, gamma correction, frame deletion editing, and movement editing. The image data that has undergone image processing is output to the laser exposure unit 12.

The laser exposure unit 12 irradiates the photosensitive drum 10 with an exposure beam Bm emitted from, for example, a semiconductor laser, according to the input image data. After the surface of the photosensitive drum 10 is charged to a predetermined charging potential by the charger 11, the surface is scanned and exposed by the laser exposure device 12 to form an electrostatic latent image.
The formed electrostatic latent image is developed with a toner image by the developing device 13. That is, for example, a developer carrying body (developing sleeve) 13a carrying a developer composed of toner and carrier is applied with a developing bias composed of a DC voltage from a power source (not shown) or a developing bias in which a DC voltage is superimposed on an AC voltage. Thus, a developing electric field is formed between the photosensitive drum 10. As a result, the toner on the developing sleeve 13a is transferred to the image portion of the electrostatic latent image, and the electrostatic latent image is visualized.

  Here, in the image forming apparatus according to the present embodiment, a setup cycle is executed every predetermined cycle. That is, prior to the actual image forming operation, a predetermined patch area is developed under predetermined conditions. At that time, as will be described later, the transfer conveyance belt 21 of the transfer unit 20 is set to be separated from the photosensitive drum 10. In this state, the developed patch area passes through the transfer section 15 as it is, and the density of the toner image in the patch area is measured by the image density sensor 18 disposed on the downstream side of the transfer section 15. The toner density signal measured by the image density sensor 18 is sent to the control unit 30. Then, in accordance with an instruction from the control unit 30 based on the signal from the image density sensor 18, the charging potential of the photosensitive drum 10 by the charger 11 and / or the developing bias value applied to the developing device 13 is adjusted, and a predetermined image is obtained. The density is set to be maintained.

  Next, the toner image formed on the photosensitive drum 10 in the actual image forming operation is conveyed to the transfer unit 15 where the photosensitive drum 10 and the transfer unit 20 abut. When the toner image is transported to the transfer unit 15, in the paper transport system, the pickup roll 51 rotates in accordance with the timing at which the toner image is transported to the transfer unit 15, and the paper P of a predetermined size is supplied from the paper tray 50. The The paper P supplied by the pickup roll 51 is transported by the transport roll 52, and reaches the registration roll 54 through the transport chute 53. In the registration roll 54, the paper P is temporarily stopped, and the registration roll 54 rotates in accordance with the movement timing of the photosensitive drum 10 carrying the toner image. Thereby, the position of the paper P and the position of the toner image are aligned, and the paper P is sent out from the inlet chute 55 to the transfer unit 15.

  In the transfer unit 15, the sheet P conveyed at the same timing is sandwiched between the photosensitive drum 10 and the transfer roll 24 via the transfer conveyance belt 21 of the transfer unit 20. At that time, a voltage (transfer bias) having a polarity opposite to the charging polarity of the toner (here, negative polarity) is applied to the transfer roll 24, whereby the photosensitive member is transferred from the transfer roll 24 to the transfer conveyance belt 21. A charge having a polarity opposite to the toner charging polarity on the drum 10 is applied. As a result, the unfixed toner image carried on the photoconductor drum 10 is electrostatically transferred onto the paper P in the transfer unit 15 pressed by the photoconductor drum 10 and the transfer roll 24.

Thereafter, the sheet P on which the toner image has been electrostatically transferred is peeled off and conveyed from the photosensitive drum 10 while being electrostatically attracted to the transfer conveyance belt 21 of the transfer unit 20, and downstream of the transfer unit 20 in the sheet P conveyance direction. To the fixing device 60 provided on the side. When the sheet P is not peeled off from the photosensitive drum 10 and remains adsorbed on the photosensitive drum 10, it is disposed near the surface of the photosensitive drum 10 on the downstream side of the transfer unit 15. The paper P is separated from the photosensitive drum 10 by a separation claw (not shown) and is electrostatically attracted to the transfer conveyance belt 21.
At the rear end of the transfer conveyance belt 21 on the fixing device 60 side, the sheet P is peeled from the transfer conveyance belt 21 due to the curvature when the transfer conveyance belt 21 is wound around the drive roll 22 and the stiffness of the sheet P. Then, the paper P is guided to the fixing inlet guide 56 and conveyed to the fixing device 60.
The unfixed toner image on the paper P conveyed to the fixing device 60 is fixed on the paper P by being subjected to fixing processing by heat and pressure in the fixing device 60. Then, the paper P on which the fixed image is formed is conveyed to a paper discharge mounting portion provided in a discharge portion of the image forming apparatus, and a series of image forming operations is completed.

  The image forming apparatus according to the present embodiment is configured to form a single color toner image. However, the present invention is a color that forms a color toner image by superimposing, for example, yellow, magenta, cyan, and black toner images. It can also be applied to an image forming apparatus.

Next, the transfer unit 20 will be described in detail.
FIG. 2 is a cross-sectional view showing the configuration of the transfer unit 20. As shown in FIG. 2, the transfer unit 20 transfers the toner image on the photosensitive drum 10 onto the paper P, and at the same time, the transfer transport unit 20A as an example of a transfer transport unit that transports the paper P on which the toner image is transferred. A retraction mechanism 20B that contacts and separates the transfer conveyance unit 20A from the photosensitive drum 10, and a cleaning unit 20C as an example of a cleaning unit that removes adhering substances such as paper dust and toner adhering to the transfer conveyance unit 20A. The inlet chute 20D guides the incoming paper P to the transfer unit 15.

  FIG. 3 is a perspective view showing the configuration of the transfer unit 20. As shown in FIG. 3, the transfer conveyance unit 20 </ b> A of the transfer unit 20 is stretched around the transfer conveyance belt 21 and the transfer conveyance belt 21 arranged in the axial direction of the photosensitive drum 10, and rotates in the arrow B direction. A drive roll 22 that is moved, an idle roll 23 that stretches the transfer conveyance belt 21 to apply a predetermined tension, and a transfer roll 24 that forms a transfer electric field with the photosensitive drum 10 to transfer a toner image onto the paper P. It is comprised by.

As the transfer / conveying belt 21, for example, a chloroprene blend rubber containing an appropriate amount of an antistatic agent such as carbon black is used, and its volume resistivity is set to 10 ⁶ to 10 ⁸ Ωcm. It is a belt. The driving roll 22 is configured such that driving is transmitted by a coupling 25 from a driving motor (not shown) on the image forming apparatus main body side, and rotates the transfer conveyance belt 21 at a predetermined speed. The transfer roll 24 is composed of a tube of EPDM and NBR blend rubber dispersed with carbon on the surface, and a roll of EPDM rubber dispersed with carbon on the inside, and the hardness is set to 25 ° (Asker C), for example. A transfer bias having a polarity (positive polarity) opposite to the toner charging polarity (negative polarity) is stably applied to the transfer roll 24 from a transfer power source (not shown). As a result, a charge having a polarity opposite to the toner charging polarity on the photosensitive drum 10 is applied from the transfer roll 24 to the transfer conveyance belt 21.
In addition, the transfer conveyance unit 20A is configured such that the idle roll 23 side is swung by the retract mechanism unit 20B with the drive roll 22 as the rocking center, and is configured to be able to contact and separate from the photosensitive drum 10.

  The transfer conveyance unit 20A of the present embodiment is configured by using a transfer conveyance belt 21 that is provided with a transfer roll 24 therein and stretched between a drive roll 22 and an idle roll 23. A configuration having only a transfer roll, a configuration having a conveyance belt that conveys the paper P to the fixing device 60 downstream of the transfer conveyance belt 21, and a conveyance belt that conveys the paper P to the fixing device 60 downstream of the transfer roll. It is also possible to adopt other configurations.

  Next, the retract mechanism unit 20B is disposed below the transfer conveyance unit 20A. FIG. 4 is a perspective view illustrating a configuration in a state where the transfer conveyance unit 20 </ b> A is removed from the transfer unit 20. As shown in FIG. 4, the retract mechanism unit 20B is disposed at both ends in the width direction of the transfer conveyance unit 20A. The retraction mechanism unit 20B pushes up and down while supporting the idle roll 23 of the transfer conveyance unit 20A. A plate 31 is fixedly provided, and includes a link shaft 32 that swings the contact / separation plate 31, a swing arm 33 that is connected to the center of the link shaft 32, and a DC solenoid 34 that drives the swing arm 33 to swing. Yes. In the retract mechanism 20B, when a current is passed through the direct current solenoid 34, the direct current solenoid 34 moves the swing arm 33 in a downward direction. As a result, the link shaft 32 connected to the swing arm 33 rotates, and the contact / separation plates 31 fixed to both ends of the link shaft 32 swing upward.

  In the transfer unit 20, the transfer conveyance unit 20 </ b> A is set in a state of being separated from the photosensitive drum 10 at the time of measuring the toner image density in the patch area (setup cycle) or in the standby state of the image forming apparatus. FIG. 5 is a diagram illustrating a state where the transfer conveyance unit 20 </ b> A is separated from the photosensitive drum 10. As shown in FIG. 5, during the setup cycle of the image forming apparatus or during standby, the DC solenoid 34 of the retract mechanism unit 20B is not energized, and the swing arm 33 connected to the DC solenoid 34 is pushed up. Is set to the correct position. Therefore, the link shaft 32 connected to the swing arm 33 positions the contact / separation plates 31 fixed to both ends of the link shaft 32 downward. Since both ends of the idle roll 23 of the transfer conveyance unit 20A are supported by the contact / separation plate 31, the transfer conveyance unit 20A is set in a state of being separated from the photosensitive drum 10 by the contact / separation plate 31.

  On the other hand, during a normal image forming operation, the transfer conveyance unit 20A is set in a state of being in contact with the photosensitive drum 10. FIG. 6 is a diagram illustrating a state where the transfer conveyance unit 20 </ b> A is in contact with the photosensitive drum 10. During the image forming operation, the paper P that has been fed to the registration roll 54 and has been waiting is sent out by the registration roll 54 in accordance with the movement timing of the photosensitive drum 10 carrying the toner image. At this time, the sensor (not shown) detects that the leading edge of the paper P has been guided to the inlet chute 55 and has reached the vicinity of the contact portion between the photosensitive drum 10 and the transfer conveyance belt 21. When the control unit 30 inputs a signal from this sensor, the control unit 30 turns on the DC solenoid 34 of the retract mechanism unit 20B and starts energization. As a result, the DC solenoid 34 moves the swing arm 33 in a downward direction. When the swing arm 33 is pushed down, the link shaft 32 connected to the swing arm 33 rotates, and the contacting / separating plates 31 fixed to both ends of the link shaft 32 swing upward. Then, the idle roll 23 of the transfer conveyance unit 20 </ b> A whose both end portions are supported by the contact / separation plate 31 is set in a state of being in contact with the photosensitive drum 10. At that time, a nip portion is formed at a contact portion between the photosensitive drum 10 and the transfer conveyance belt 21.

  When the transfer conveyance unit 20 </ b> A comes into contact with the photosensitive drum 10, the paper P on the transfer conveyance belt 21 conveyed by the rotation drive of the drive roll 22 enters the nip portion between the photosensitive drum 10 and the transfer conveyance belt 21. A transfer bias having a polarity (plus polarity) opposite to the toner charging polarity (minus polarity) is applied to the transfer roll 24 from a transfer power source (not shown), so that the toner on the photosensitive drum 10 is transferred to the transfer conveyance belt 21. A charge having a polarity opposite to the charging polarity is applied. Then, the toner on the photosensitive drum 10 is transferred to the paper P. Thereafter, the paper P is transported in a state of being electrostatically attracted to the transfer transport belt 21 and sent to the fixing device 60.

  Next, as shown in FIG. 2, the cleaning unit 20 </ b> C attached to the cleaning brush 41 and the cleaning brush 41 that wipes off the adhering matter such as paper dust and toner adhered on the surface of the transfer conveyance belt 21 of the transfer conveyance unit 20 </ b> A. A flicker bar 42 disposed so as to bite into the cleaning brush 41 so as to knock off the deposits, and is disposed on the downstream side of the cleaning brush 41 in the transport direction of the transfer transport belt 21, on the surface of the transfer transport belt 21. A cleaning blade 43 that scrapes off deposits, a cleaning brush 41 and a cleaning box 44 that receives the paper dust and toner removed from the surface of the transfer and transport belt 21 by the cleaning blade 43, and a paper bottle that collects paper dust and toner in the cleaning box 44. A recovery coil 45 to be conveyed (not shown); It is constituted by a blade holder 46 for holding the leaning blade 43.

The cleaning brush 41 is a brush roll in which brush fibers made of conductive polyester (electric resistance 10 ⁵ to 10 ⁶ Ω) having a thickness of 5.7 denier and a fiber density of 30 K / inch ² are formed on the surface. The transfer conveyance belt 21 is configured to rotate in the forward direction and the conveyance direction. The cleaning blade 43 is a plate-like member made of urethane rubber having a thickness of 1 mm, for example, and is disposed in counter contact with the transfer conveyance belt 21. Then, the cleaning brush 41 rotates in the direction opposite to the conveyance direction of the transfer conveyance belt 21 and wipes off adhesions such as paper dust and toner adhering to the surface of the transfer conveyance belt 21 to transfer most of the adhesion matters. Collected in the cleaning box 44 from the surface of the conveyor belt 21. Further, the cleaning blade 43 disposed on the downstream side of the cleaning brush 41 scrapes off deposits that could not be wiped off by the cleaning brush 41 and collects them in the cleaning box 44. In particular, when the adhesion force of the adhered matter to the transfer / conveying belt 21 is strong as in the case of using a polymer toner having a small particle size as the toner, the effect of reducing the adhesion force due to contact with the cleaning brush 41 and the cleaning Due to a synergistic effect with the scraping effect of the blade 43, the deposits can be sufficiently removed.

  Further, the collection coil 45 conveys paper dust, toner, and the like in the cleaning box 44 to a collection bottle (not shown) while rotating in the direction of arrow C in FIG. The collecting coil 45 is moved in the direction of arrow C, that is, in the direction away from the fixing device 60 side of paper dust and toner collected on the bottom surface of the cleaning box 44 (upstream side in the direction of conveying the paper P of the transfer conveying belt 21). By rotating so as to be moved, paper dust, toner, and the like are conveyed along the side wall 44a in the cleaning box 44 on the side opposite to the fixing device 60 side. Therefore, the collected toner is difficult to receive heat from the fixing device 60, and the fusion between the toners can be suppressed. Therefore, the collected paper powder, toner, and the like can be smoothly conveyed to the collection bottle. .

Further, the inlet chute 20D is disposed on the upstream side of the transfer conveying unit 20A in the transfer unit 20, and is integrally joined to the housing 70. The photosensitive drum inlet chute 55a integrally formed with the photosensitive drum unit that supports the photosensitive drum 10 and the resist roll inlet chute 55b integrally formed with the resist roll unit that supports the resist roll 54 (FIG. Inlet chute 55 is configured in combination with an upper inlet chute (regulation guide member, first guide portion) composed of 1). In this case, the inlet chute portion 20 </ b> D constitutes a lower inlet chute (guide member, second guide portion) of the inlet chute 55. That is, the inlet chute 55 is composed of a separate upper inlet chute and lower inlet chute, and the lower inlet chute is integrally configured with the transfer unit 20 as an inlet chute portion 20D.
The inlet chute 55 supports one surface (lower surface) of the sheet P conveyed from the resist roll 54 by the inlet chute 20D, and the other surface (upper surface) of the photosensitive drum inlet chute 55a and the resist roll. While being regulated by the inlet chute 55b, it is carried into the nip portion between the photosensitive drum 10 and the transfer conveyance belt 21 in the transfer portion 15 while maintaining an accurate posture without being inclined.

Next, the swinging operation of the transfer unit 20 in the image forming apparatus will be described. FIG. 7 is a diagram illustrating a state in which the transfer unit 20 is installed in the image forming apparatus and is in contact with the photosensitive drum unit 10 a that supports the photosensitive drum 10. In the transfer unit 20, the rotation axis of the drive roll 22 of the transfer conveyance unit 20 </ b> A is supported by a bearing on a main body frame (not shown) of the image forming apparatus, and the transfer unit 20 swings around the rotation axis of the drive roll 22. It is configured to be free. The transfer unit 20 is urged by the transfer unit push-up lever 80 by pushing up the transfer unit push-up lever 80, and comes into contact with the photosensitive drum unit 10a. At that time, an abutting portion (an abutting portion of the transfer unit 20) provided on the end of the transfer unit 20 on the side wall 73 of the housing 70 opposite to the rotation center of the transfer unit 20 is provided. The transfer unit 20 is positioned with respect to the photosensitive drum 10 by being abutted against the photosensitive drum unit 10a.
In this state, the photosensitive drum 10 and the transfer conveyance belt 21 of the transfer unit 20 are in contact with each other with a predetermined positional relationship, and a nip portion having a predetermined width is formed. Further, the photosensitive drum 10 and the transfer roll 24 of the transfer unit 20 are set with a predetermined positional relationship. Then, the optimum transfer of the toner image onto the paper P is executed.

  On the other hand, for example, when a paper jam (jam) occurs in the transfer unit 20, the transfer unit 20 releases the photosensitive drum unit with the rotation center of the transfer unit 20 as the swing axis by releasing the transfer unit push-up lever 80. Separate from 10a. FIG. 8 is a view showing a state in which the transfer unit 20 is separated from the photosensitive drum 10. As the transfer unit 20 is separated from the photoconductor drum 10 in this manner, the transfer unit 20 and the photoconductor drum 10, the inlet chute 20D, the photoconductor drum inlet chute 55a, and the resist roll inlet chute 55b Thus, the sheet P jammed between the two can be easily removed.

  As described above, the inlet chute 20D of the transfer unit 20 is configured so as to be integrated with the photosensitive drum unit 10a (see FIG. 7) that supports the photosensitive drum 10 as the transfer unit 20 swings. The drum inlet chute 55a and the resist roll inlet chute 55b integrally formed with the resist roll unit 54a (see FIG. 8) that supports the resist roll 54 are configured to come in contact with and separate from each other. That is, when the transfer unit 20 is in contact with the photosensitive drum unit 10a, as shown in FIG. 9, the inlet chute 20D that is a lower inlet chute has a photosensitive drum inlet chute 55a that is an upper inlet chute and a resist roll. The inlet chute 55b is abutted with a predetermined positional relationship to form the inlet chute 55 as a whole. On the other hand, in a state where the transfer unit 20 is separated from the photosensitive drum unit 10a, the inlet chute 20D is positioned away from the photosensitive drum inlet chute 55a and the resist roll inlet chute 55b, and the paper P enters the transfer unit 15 into the protruding portion. Is released (see FIG. 8).

In this case, each part of the inlet chute 55 is positioned as follows. In the state where the inlet chute 20D is in contact with the photosensitive drum inlet chute 55a and the resist roll inlet chute 55b to form the inlet chute 55, the inlet chute 20D configured integrally with the transfer unit 20 has the photosensitive drum unit. It is set at a predetermined position with respect to the photosensitive drum inlet chute 55a integrally formed with 10a. That is, when the abutting portion of the side wall 73 of the transfer unit 20 (the abutting portion of the transfer unit 20: see FIG. 7) is abutted against the photosensitive drum unit 10a, the photosensitive drum unit 10a and the transfer unit 20 are positioned. In addition, the inlet chute 20D and the photosensitive drum inlet chute 55a are positioned at predetermined positions.
The inlet chute 20D and the resist roll inlet chute 55b are both ends in the width direction of the inlet chute 20D facing the resist roll inlet chute 55b when the photosensitive drum unit 10a and the transfer unit 20 are positioned. The abutting portion 84 disposed on the surface is abutted against the resist roll inlet chute 55b, and is set at a predetermined position (see FIG. 9).

  In addition, when the inlet chute portion 20D is in contact with the photosensitive drum inlet chute 55a and the resist roll inlet chute 55b, the metal leaf springs 85 disposed on the upper surface side of the inlet chute portion 20D are both made of metal. The photosensitive drum inlet chute 55a and the resist roll inlet chute 55b formed in the above are configured to be electrically connected to each other. As described above, the photosensitive drum inlet chute 55a and the resist roll inlet chute 55b are electrically connected by the leaf spring 85 of the inlet chute 20D, so that the photosensitive drum inlet chute 55a and the resist roll inlet chute 55b are connected. , And grounded through a high-resistance (for example, 200 MΩ) resistor 65 connected to any one (in FIG. 9, the resistor 65 is connected to the resist roll inlet chute 55b). Therefore, for example, even if the volume resistance value of the paper P decreases in a high humidity environment, the charge applied from the transfer roll 24 to the transfer conveyance belt 21 is transferred via the paper P to the photosensitive drum inlet chute 55a and the resist roll inlet. Leakage from the chute 55b is suppressed, and good transfer processing can be performed.

  Next, the configuration of the inlet chute 20D of the transfer unit 20 will be described. FIG. 10 is a diagram illustrating a configuration of the inlet chute 20D. As shown in FIG. 10, the inlet chute 20D is formed of a resin such as elastically deformable polycarbonate (PC), and the fixing chute 81 that fixes the inlet chute 20D to the transfer unit 20 main body, the paper of the inlet chute 20D. A swinging portion 82 that can swing the upstream side in the P conveying direction, a resist side facing portion 83 that faces the resist roll inlet chute 55b, and a position that faces the resist roll inlet chute 55b, and is disposed at both ends in the width direction. And a plate spring 85 formed of a metal such as SUS that electrically connects the photosensitive drum inlet chute 55a and the resist roll inlet chute 55b.

  As described above, when the photoreceptor drum unit 10a and the transfer unit 20 are positioned in contact with the inlet chute portion 20D, the abutting portions 84 at both ends in the width direction are abutted against the resist roll inlet chute 55b. Thus, the inlet chute portion 20D and the resist roll inlet chute 55b are set at predetermined positions. However, for example, when the fixing portion 81 of the inlet chute portion 20D is attached to the transfer unit 20 main body, an attachment error may occur between them. In that case, the error of the set position in the abutting portion 84 located away from the fixed portion 81 becomes large, and the abutting portion 84 may abut against the resist roll inlet chute 55b. At this time, since the resist roll inlet chute 55b side is firmly fixed to the resist roll unit 54a, the central portion in the width direction of the resist side facing portion 83 is caused by the force acting on the abutting portion 84 on the resist roll inlet chute 55b side. Curving towards. When such a curvature occurs in the resist side facing portion 83, the gap between the resist roll inlet chute 55b and the resist side facing portion 83 is narrowed, and the conveyance of the paper P is hindered and the paper is transferred to the transfer portion 15 with high accuracy. It becomes difficult to guide P. Therefore, transfer defects such as image displacement may occur in the transfer unit 15. In particular, when the curve is large, there is a possibility that the paper P cannot be conveyed.

  In view of this, in the inlet chute 20D of the present embodiment, a swinging portion 82 that allows the registration-side facing portion 83 to swing is provided in the vicinity of the upstream side of the fixed portion 81 in the sheet P conveyance direction. When the abutting portion 84 is strongly abutted against the resist roll inlet chute 55b, the swinging portion 82 is elastically deformed on the resist side facing portion 83 side with the fixed portion 81 side of the swinging portion 82 as a fulcrum ( It is configured to be bent. With this configuration, the swinging portion 82 can be bent and the force acting on the resist-side facing portion 83 can be absorbed. Therefore, the abutting force of the abutting portion 84 against the resist roll inlet chute 55b can be reduced, so that the center portion in the width direction of the resist side facing portion 83 is prevented from being curved toward the resist roll inlet chute 55b. Therefore, it is possible to maintain a predetermined gap between the resist roll inlet chute 55b and the resist side facing portion 83. As a result, it is possible to stabilize the conveyance of the paper P, guide the paper P to the transfer unit 15 with high accuracy, and obtain a good transfer image without image misalignment or the like.

Here, in order to cause the swinging portion 82 to bend, the swinging portion 82 is formed thinner than the thickness of the resist side facing portion 83. Thus, by forming the thickness of the swinging portion 82 thinner than the thickness of the resist side facing portion 83, the rigidity of the swinging portion 82 can be set smaller than the rigidity of the resist side facing portion 83. Specifically, while the thickness of the resist-side facing portion 83 is set to 2 mm, the thickness of the swing portion 82 is set to 0.5 to 0.8 mm, so that the rigidity of the swing portion 82 is increased. The resist side facing portion 83 is reduced to about 25 to 40% of the rigidity. In particular, in order to increase the strength against the curvature of the abutment portion 84 of the resist side facing portion 83 where the abutting force against the resist roll inlet chute 55b is concentrated, A 5 mm thick rib is formed.
With such a configuration, it is possible to increase the strength of the resist side facing portion 83, particularly the abutting portion 84, against the curvature. Furthermore, when a strong urging force is applied to the abutting portion 84, the oscillating portion 82 elastically deforms (bends) the resist side facing portion 83 with the fixed portion 81 side as a fulcrum, thereby resisting the resist side. The force acting on the portion 83 can be absorbed. Therefore, it is possible to suppress the bending at the resist side facing portion 83, the gap between the resist roll inlet chute 55b and the resist side facing portion 83 is maintained, the conveyance of the paper P is stabilized, and the highly accurate paper P Can be realized.

  As described above, in the image forming apparatus according to the present embodiment, the inlet chute 55 includes the separate upper inlet chute and lower inlet chute. The lower inlet chute is integrally formed with the transfer unit 20 as an inlet chute 20D, and as the transfer unit 20 contacts and separates from the photosensitive drum unit 10a that supports the photosensitive drum 10, the photosensitive drum inlet chute is arranged. The upper inlet chute including the 55a and the resist roll inlet chute 55b is configured so as to be able to contact and separate. Therefore, by separating the transfer unit 20 from the photosensitive drum 10, between the transfer unit 20 and the photosensitive drum 10, the inlet chute 20D (lower inlet chute), the photosensitive drum inlet chute 55a, and the registration roll are also provided. Since the space between the inlet chute 55b (upper inlet chute) is released, the jammed paper P can be easily removed.

  Further, in the inlet chute portion 20D, by providing the swinging portion 82 whose rigidity is set smaller than that of other portions, when the transfer unit 20 is brought into contact with the photosensitive drum unit 10a to form the inlet chute 55, When the inlet chute portion 20D is strongly abutted against the resist roll inlet chute 55b, the swinging portion 82 is elastically deformed (bends), so that the force acting on the inlet chute portion 20D can be absorbed. . Thereby, in the region where the inlet chute 20D abuts against the resist roll inlet chute 55b, it is possible to prevent the central portion in the width direction from being curved toward the resist roll inlet chute 55b. Therefore, a predetermined gap between the resist roll inlet chute 55b and the inlet chute portion 20D is maintained, the conveyance of the paper P is stabilized, the paper P is guided to the transfer portion 15 with high accuracy, and there is no image misalignment. It becomes possible to obtain a simple transfer image.

  Examples of utilization of the present invention include application to copying machines, printers, facsimiles, and multifunctional machines using electrophotography.

1 is a schematic configuration diagram of an image forming apparatus of the present invention. It is sectional drawing which shows the structure of a transfer unit. It is a perspective view which shows the structure of a transfer unit. FIG. 3 is a perspective view illustrating a configuration of a transfer unit in a state where a transfer conveyance unit is removed. FIG. 6 is a diagram illustrating a state where a transfer conveyance unit is separated from a photosensitive drum. FIG. 6 is a diagram illustrating a state where a transfer conveyance unit is in contact with a photosensitive drum. FIG. 4 is a diagram illustrating a state where a transfer unit is in contact with a photosensitive drum unit. FIG. 6 is a diagram illustrating a state where a transfer unit is separated from a photosensitive drum. FIG. 6 is a diagram illustrating an inlet chute state when the transfer unit is in contact with the photosensitive drum unit. It is a figure which shows the structure of an inlet chute part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Photosensitive drum, 10a ... Photosensitive drum unit, 11 ... Charger, 12 ... Laser exposure device, 13 ... Developing device, 15 ... Transfer part, 17 ... Drum cleaner, 20 ... Transfer unit, 20A ... Transfer conveyance part, 20B Retract mechanism 20C Cleaning unit 20D Inlet chute 21 Transfer transfer belt 22 Drive roll 23 Idle roll 25 Coupling 30 Control unit 31 Contact / separation plate 32 Link shaft, 33 ... swing arm, 34 ... DC solenoid, 41 ... cleaning brush, 42 ... flicker bar, 43 ... cleaning blade, 44 ... cleaning box, 45 ... collection coil, 46 ... blade holder, 54 ... resist roll, 54a ... Registration roll unit, 55 ... Inlet chute, 55a ... Photoconductor drum Beam inlet chute, 55b ... registration roller inlet chute, 60 ... fuser, 70 ... housing, 81 ... fixed portion, 82 ... swinging portion, 83 ... resist side facing portion, 84 ... abutting portion, 85 ... plate spring

Claims (6)

A toner image carrier for carrying a toner image;
Transfer transfer means for transferring the toner image carried by the toner image carrier to a transfer material and conveying the transfer material;
A guide member that guides the transfer material to a contact portion between the toner image carrier and the transfer conveyance unit, and holds a first guide unit that regulates one surface of the transfer material, and the transfer conveyance unit. A guide member that is disposed on the support and includes a second guide portion that supports the other surface of the transfer material,
The second guide portion of the guide member and the first guide portion when the transfer material upstream side portion of the second guide portion abuts against the first guide portion. An image forming apparatus characterized in that the downstream side portion of the second guide portion in the transport direction of the transfer material is elastically deformed while maintaining a predetermined gap with the portion. 2. The image forming apparatus according to claim 1 , wherein the second guide portion of the guide member has an abutting portion that abuts against the first guide portion at an upstream portion in the transport direction. The image forming apparatus according to claim 2 , wherein the second guide portion of the guide member has a rib structure in the vicinity of the abutting portion in the upstream portion in the transport direction. 2. The image forming apparatus according to claim 1 , wherein the second guide portion of the guide member is formed such that the rigidity in the upstream portion in the transport direction is high and the rigidity in the downstream portion in the transport direction is low. The image forming apparatus according to claim 1 , wherein the second guide portion of the guide member is formed such that a downstream portion in the transport direction is thinner than an upstream portion in the transport direction. The toner image carrier and the transfer conveyance means are configured to be contactable and separable, and the transfer guide means includes the first guide portion of the guide member and the upstream portion of the second guide portion in the conveyance direction. The image forming apparatus according to claim 1 , wherein when the toner image bearing members are in contact with each other, they are in contact with each other.

Images