Image forming apparatus

Abstract

This image formation device (100) comprises: an intermediate transfer belt (15B) provided to a main body housing (3); an opening / closing unit (30) that can open and close; a secondary transfer roller (152) that is provided to the opening / closing unit (30) and brought into contact with the intermediate transfer belt (15B) when the opening / closing unit (30) is closed; a guide member (31) that is provided to the opening / closing unit (30) so as to be swingable and that guides a sheet in the area in which the intermediate transfer belt (15B) and the secondary transfer roller (152) are in contact; a conductive sheet (32) covering the guide member (31); and a conductive spring (33) that is provided to the opening / closing unit (30) and whereby the guide member (31) is biased toward the intermediate transfer belt (15B) side via the conductive sheet (32) and pressed against a contact section (3E) on the main body housing (3) side when the opening / closing unit (30) is closed. The guide member (31) is brought into contact with the conductive spring (32) by gravity when the opening / closing unit (30) is opened.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus.

Background Art

[0002] In an electrophotographic image forming apparatus, since the charging of a sheet affects the image quality, conventionally, techniques for discharging the sheet have been studied. For example, Patent Document 1 discloses a resin guide member having a boss protruding toward a metal housing on its side surface, being supported by the housing via the boss, having a paper conveyance surface, and a static elimination member provided at an end face of the guide member for removing the charge charged on the paper, and a metal compression coil spring having a natural length larger than the length of the boss, surrounding the boss, connecting the housing and the static elimination member, and grounding the static elimination member. Patent Document 2 discloses a conveyance guide for guiding a recording material, a support member having a support portion for rotatably supporting the conveyance guide, a first torsion coil spring for biasing the conveyance guide in the rotation direction of the conveyance guide, and a second torsion coil spring for biasing the conveyance guide in the axial direction of the support portion, and the first torsion coil spring and the second torsion coil spring are conductive and each apply a different potential to the conveyance guide.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] As a means for eliminating static electricity before transferring the toner image to the sheet, it is conceivable to use a guide member for guiding the sheet to the nip portion of the transfer roller. For example, in the case of a color image forming apparatus, a guide member is provided on the upstream side in the sheet conveyance direction of the nip portion between the intermediate transfer belt and the secondary transfer roller. The surface of the guide member is covered with a grounded conductive sheet, and the sheet is eliminated of static electricity when it comes into contact with the conductive sheet.

[0005] In many cases, in consideration of the recovery work when the sheet is jammed, a configuration is adopted in which the conveyance path near the secondary transfer roller is opened. For example, the secondary transfer roller is provided on an opening / closing unit hinged to the main body of the image forming apparatus, and when a sheet jam occurs, the opening / closing unit is opened to separate the secondary transfer roller from the intermediate transfer belt.

[0006] Here, in order to surely ground the conductive sheet, a configuration in which a conductive spring is pressed against the conductive sheet is desirable. However, in this configuration, when opening and closing the opening / closing unit, the positional relationship between the conductive spring and the conductive sheet slightly changes due to the distortion generated in the opening / closing unit, and friction occurs between the conductive spring and the conductive sheet. Since the conductive sheet is vulnerable to friction, there is a risk of being worn out during repeated opening and closing.

[0007] An object of the present invention is to provide an image forming apparatus capable of suppressing friction between a conductive sheet and a conductive spring when opening and closing an opening / closing unit in consideration of the above circumstances.

Means for Solving the Problems

[0008] To solve the above problems, an image forming apparatus according to the present invention includes a main body having an opening, an image carrier provided on the main body for carrying a toner image, an opening / closing unit provided at the opening and capable of opening and closing, a transfer roller provided on the opening / closing unit and contacting the image carrier when the opening / closing unit is closed, a guide member swingably provided on the opening / closing unit for guiding a sheet in a contact area between the image carrier and the transfer roller, a conductive sheet covering the guide member, and a conductive spring provided on the opening / closing unit for urging the guide member toward the image carrier side through the conductive sheet when the opening / closing unit is closed, thereby pressing the guide member against a contact portion on the main body side. When the opening / closing unit is opened, the guide member contacts the conductive spring by gravity.

Advantages of the Invention

[0009] According to the present invention, friction between the conductive sheet and the conductive spring when opening and closing the opening / closing unit can be suppressed.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0011] First, the overall configuration of the image forming apparatus 100 will be described. FIG. 1 is a perspective view showing the appearance of the image forming apparatus 100. FIG. 2 is a front view schematically showing the internal configuration of the image forming apparatus 100. Hereinafter, the front side (front side) of the image forming apparatus 100 is defined as the side closer to the viewer in FIG. 2, and the left and right directions are described based on the direction when the image forming apparatus 100 is viewed from the front. In each figure, U, Lo, L, R, Fr, and Rr indicate up, down, left, right, front, and rear, respectively.

[0012] The image forming apparatus 100 includes a printer 1, a scanner 110, and an original conveying device 120. The scanner 110 is provided above the printer 1, and the original conveying device 120 is provided above the scanner 110. The original conveying device 120 conveys the original along a conveyance path passing through the reading position of the scanner 110. The scanner 110 is a flatbed type image scanner that reads the original and generates image data. The printer 1 forms an image based on the image data on the sheet S.

[0013] The printer 1 includes a rectangular parallelepiped main body housing 3 (an example of the main body). A paper feed cassette 4 for accommodating the sheet S and a paper feed roller 5 for feeding the sheet S to the right from the paper feed cassette 4 are provided at the lower part inside the main body housing 3. An image forming device 6 for forming a toner image by an electrophotographic method is provided above the paper feed cassette 4, and a fixing device 7 for fixing the toner image on the sheet S is provided at the upper right of the image forming device 6. A paper discharge roller 8 for discharging the sheet S on which the toner image is fixed and a paper discharge tray 9 on which the discharged sheets S are stacked are provided above the fixing device 7.

[0014] Inside the main body housing 3, a conveyance path 10 is provided that extends from the paper feed roller 5 through the image forming device 6 and the fixing device 7 to the paper discharge roller 8. The conveyance path 10 is mainly formed by plate-like members that face each other with a gap for passing the sheet S, and conveyance rollers 17 for sandwiching and conveying the sheet S are provided at a plurality of locations in the conveyance direction Y. A registration roller 18 is provided on the upstream side in the conveyance direction Y from the image forming device 6. On the right side of the fixing device 7, a reverse conveyance path 10R is provided that branches off from the conveyance path 10 on the downstream side in the conveyance direction Y from the fixing device 7 and merges into the conveyance path 10 on the upstream side in the conveyance direction Y from the registration roller 18.

[0015] The image forming device 6 includes a photosensitive drum 11 whose potential changes upon irradiation with light, a charging device 12 for charging the photosensitive drum 11, an exposure device 13 that emits laser light according to image data, a developing device 14 that supplies toner to the photosensitive drum 11, an intermediate transfer unit 15 that transfers the toner image from the photosensitive drum 11 to the sheet S, and a cleaning device 16 that removes the toner remaining on the photosensitive drum 11. The intermediate transfer unit 15 includes an endless intermediate transfer belt 15B wound around a driving roller 15D and a driven roller 15N, a primary transfer roller 151 that faces the inner peripheral surface of the intermediate transfer belt 15B at a position corresponding to the photosensitive drum 11 and generates a primary transfer bias, and a secondary transfer roller 152 that faces the outer peripheral surface of the intermediate transfer belt 15B at a position corresponding to the driving roller 15D and generates a secondary transfer bias. A toner container 20 for supplying toner to the developing device 14 is connected to the developing device 14.

[0016] The image forming device 6 includes four sets of the photosensitive drum 11, the charging device 12, the exposure device 13, the developing device 14, the primary transfer roller 151, the cleaning device 16, and the toner container 20, and forms a color image by overlapping four-color toner images on the intermediate transfer belt 15B. Note that the present invention may be applied to an image forming device that forms a color image with three or fewer or five or more colors of toner.

[0017] The control unit 2 includes an arithmetic unit and a storage unit. The arithmetic unit is, for example, a CPU (Central Processing Unit). The storage unit includes storage media such as a ROM (Read Only Memory), a RAM (Random Access Memory), and an EEPROM (Electrically Erasable Programmable Read Only Memory). The arithmetic unit performs various processes by reading and executing a control program stored in the storage unit. Note that the control unit 2 may be realized only by an integrated circuit without using software.

[0018] An operation panel 19 is provided on the front side of the scanner 110. The operation panel 19 includes a display panel, a touch panel provided overlapping the display surface of the display panel, and a keypad adjacent to the display panel. The control unit 2 causes the display panel to display a screen representing operation menus, statuses, etc. of the printer 1 and the scanner 110, and controls each part of the printer 1 and the scanner 110 according to operations detected by the touch panel and the keypad.

[0019] The basic image forming operation of printer 1 is as follows. When a single-sided printing job is input from an external computer or the like to printer 1, the paper feed roller 5 feeds the sheet S from the paper feed cassette 4 to the conveyance path 10, the registration roller 18 whose rotation has been stopped corrects the skew of the sheet S, and the registration roller 18 feeds the sheet S to the image forming device 6 at a predetermined timing. In the image forming device 6, the charging device 12 charges the photosensitive drum 11 to a predetermined potential, the exposure device 13 writes a latent image on the photosensitive drum 11, the developing device 14 forms a toner image by developing the latent image using the toner supplied from the toner container 20, the primary transfer roller 151 transfers the toner image to the intermediate transfer belt 15B, and the secondary transfer roller 152 transfers the toner image to the sheet S. Subsequently, the fixing device 7 sandwiches and conveys the sheet S while melting the toner image to fix the toner image on the sheet S, and the paper discharge roller 8 discharges the sheet S to the paper discharge tray 9. The cleaning device 16 removes the toner remaining on the photosensitive drum 11. In the case of double-sided printing, the sheet S with the toner image fixed on the first side is fed into the conveyance path 10 via the reverse conveyance path 10R, so that the toner image is transferred to the second side.

[0020] Next, the image forming apparatus 100 will be described in detail. FIG. 3 is a perspective view of the opening / closing unit 30. FIG. 4 is a cross-sectional view of the guide member 31 and its peripheral portion. FIGS. 5 and 6 are perspective views of the guide member 31 and its peripheral portion. FIG. 7 is a cross-sectional view of the guide member 31 and its peripheral portion. FIG. 8 is a cross-sectional view when the opening / closing unit 30 is closed. FIG. 9 is a cross-sectional view when the opening / closing unit 30 is opened.

[0021] The image forming apparatus 100 includes a main body housing 3 (an example of a main body) having an opening 3A, an intermediate transfer belt 15B (an example of an image carrier) that carries a toner image, an opening / closing unit 30 provided in the opening 3A and capable of opening and closing, a secondary transfer roller 152 (an example of a transfer roller) provided in the opening / closing unit 30 and contacting the intermediate transfer belt 15B when the opening / closing unit 30 is closed, a guide member 31 swingably provided in the opening / closing unit 30 and guiding a sheet S in a contact area between the intermediate transfer belt 15B and the secondary transfer roller 152, a conductive sheet 32 covering the guide member 31, and a conductive spring 33 provided in the opening / closing unit 30 and pressing the guide member 31 against a contact portion 3E on the main body housing 3 side by urging the guide member 31 toward the intermediate transfer belt 15B side through the conductive sheet 32 when the opening / closing unit 30 is closed. When the opening / closing unit 30 is opened, the guide member 31 contacts the conductive spring 33 by gravity.

[0022] A rectangular opening 3A is provided on the right side surface of the main body housing 3 (see FIGS. 1 and 2). A rectangular cover 3C that can be opened and closed is provided in the opening 3A. The lower end portion of the cover 3C is coupled to the lower end portion of the opening 3A via a hinge 3H. By opening the cover 3C, it becomes possible to remove a sheet S jammed in the conveyance path 10 and perform internal maintenance.

[0023] [Opening / Closing Unit] An opening / closing unit 30 (see FIG. 3) that can be opened and closed is provided to the left of the cover 3C. The lower end portion of the opening / closing unit 30 is coupled to the main body housing 3 via a hinge (not shown). When the cover 3C is opened, it becomes possible to open the opening / closing unit 30. Note that the opening / closing unit 30 may be integrated with the cover 3C.

[0024] The opening / closing unit 30 includes an inversion conveyance path 10R, a secondary transfer roller 152, one of a pair of rollers constituting the resist roller 18, a guide member 31, and the right plate-shaped member 10P of the pair of left and right plate-shaped members 10P constituting the conveyance path 10 (see FIGS. 2 and 3). The secondary transfer roller 152 and the guide member 31 are provided above one of the rollers of the resist roller 18. When the opening / closing unit 30 is closed, the secondary transfer roller 152 contacts the intermediate transfer belt 15B, and when the opening / closing unit 30 is opened, the secondary transfer roller 152 separates from the intermediate transfer belt 15B.

[0025] [Guide member] As shown in FIG. 3, the guide member 31 is provided on the upstream side in the conveyance direction Y of the sheet S with respect to the contact region between the secondary transfer roller 152 and the intermediate transfer belt 15B. As shown in FIGS. 6, 8, and 9, the guide member 31 has an elongated curved portion 31C having the width direction of the sheet S intersecting the conveyance direction Y as the longitudinal direction, a bottom portion 31B protruding rightward from the lower end portion of the curved portion 31C, protruding portions 31P protruding toward the intermediate transfer belt 15B from both end portions in the width direction of the curved portion 31C, and support portions 31S provided at the lower portions of both end portions in the width direction of the curved portion 31C. The support portion 31S is coupled to the opening / closing unit 30 via a swing shaft 31A having the width direction as the axial direction. The curved portion 31C is curved so that the cross section in the width direction bulges toward the intermediate transfer belt 15B, and the curved portion 31C contacts the right side surface of the sheet S conveyed from below to guide the sheet S. The main body housing 3 is provided with a contact portion 3E that contacts the protruding portion 31P when the opening / closing unit 30 is closed.

[0026] [Conductive sheet] The conductive sheet 32 is, for example, a sheet made of a conductive resin and covers the guide member 31. As shown in FIGS. 8 and 9, the conductive sheet 32 is provided over the curved portion 31C of the guide member 31, the lower surface, the right surface, and the upper surface of the bottom portion 31B.

[0027] [Conductive spring] The conductive spring 33 is, for example, a metal torsion coil spring and is wound around the swing shaft 31A of the guide member 31 as shown in FIGS. 6 and 7. The first end portion 331 of the steel wire constituting the conductive spring 33 is disposed upward and is in contact with the right surface of the bottom portion 31B of the guide member 31. The second end portion 332 of the steel wire is disposed rightward and is in contact with a leaf spring-shaped grounding member 34 (see FIG. 6) provided in the opening / closing unit 30. By the second end portion 332 obtaining a reaction force from the grounding member 34, the first end portion 331 biases the bottom portion 31B of the guide member 31 leftward.

[0028] [First regulating member] The first regulating member 41 is provided in the opening / closing unit 30 and regulates the elastic deformation of the conductive spring 33 toward the guide member 31 to a predetermined amount. As shown in FIG. 7, the first regulating member 41 is disposed between the bottom portion 31B and the swing shaft 31A of the guide member 31. When the opening / closing unit 30 is closed (see FIG. 8), the first regulating member 41 faces the first end portion 331 of the conductive spring 33 with a predetermined interval therebetween. When the opening / closing unit 30 is opened (see FIG. 9), the conductive spring 33 contacts the first regulating member 41, and thus the elastic deformation of the conductive spring 33 toward the guide member 31 is regulated to a predetermined amount.

[0029] [Second regulating member] The second regulating member 42 is provided in the opening / closing unit 30 and regulates the swing of the guide member 31 toward the intermediate transfer belt 15B in a state where the guide member 31 contacts the conductive spring 33 elastically deformed to a predetermined amount by gravity when the opening / closing unit 30 is opened. As shown in FIGS. 8 and 9, the second regulating member 42 is provided to the right of the conductive spring 33 and above the swing shaft 31A. The guide member 31 is provided with an opposing portion 31F (see FIG. 9) opposing the second regulating member 42. When the opening / closing unit 30 is closed (see FIG. 8), the opposing portion 31F and the second regulating member 42 face each other with an interval therebetween. When the opening / closing unit 30 is opened (see FIG. 9), the opposing portion 31F contacts the second regulating member 42, and thus the swing of the guide member 31 toward the intermediate transfer belt 15B is regulated.

[0030] Next, the operation of the above configuration will be described. As shown in FIG. 8, when the opening / closing unit 30 is closed, the protrusion 31P of the guide member 31 is pressed against the contact portion 3E (see FIG. 4), and the conductive spring 33 is pressed against the conductive sheet 32. At this time, the first restricting member 41 faces the first end portion 331 of the conductive spring 33 with a predetermined interval therebetween. Also, the opposing portion 31F and the second restricting member 42 face each other with an interval therebetween. A predetermined gap is provided between the conductive sheet 32 covering the curved portion 31C of the guide member 31 and the intermediate transfer belt 15B, and the sheet S is discharged of static electricity as the sheet S is conveyed while contacting the conductive sheet 32.

[0031] On the other hand, when the opening / closing unit 30 is opened, as shown in FIG. 9, since the protrusion 31P of the guide member 31 separates from the contact portion 3E, the conductive spring 33 pushes the guide member 31 toward the intermediate transfer belt 15B side. At this time, when the conductive spring 33 contacts the first restricting member 41, the elastic deformation of the conductive spring 33 toward the guide member 31 side is restricted to a predetermined amount. Also, when the opposing portion 31F contacts the second restricting member 42, the swinging of the guide member 31 toward the intermediate transfer belt 15B side is restricted. Since the bottom portion 31B of the guide member 31 comes into contact with the conductive spring 33 via the conductive sheet 32 by gravity, only the load due to gravity acts between the conductive sheet 32 and the conductive spring 33. Thus, when the opening / closing unit 30 is opened, the conductive spring 33 stops biasing the guide member 31, so that the friction between the conductive sheet 32 and the conductive spring 33 when opening and closing the opening / closing unit 30 can be suppressed.

[0032] According to the image forming apparatus 100 according to the present embodiment described above, a main body housing 3 (an example of a main body) having an opening 3A, an intermediate transfer belt 15B (an example of an image carrier) that carries a toner image, an opening / closing unit 30 provided in the opening 3A and capable of opening and closing, a secondary transfer roller 152 (an example of a transfer roller) provided in the opening / closing unit 30 and contacting the intermediate transfer belt 15B when the opening / closing unit 30 is closed, a guide member 31 that is swingably provided in the opening / closing unit 30 and guides the sheet S in a contact area between the intermediate transfer belt 15B and the secondary transfer roller 152, a conductive sheet 32 that covers the guide member 31, and a conductive spring 33 provided in the opening / closing unit 30 and pressing the guide member 31 against a contact portion 3E on the main body housing 3 side by urging the guide member 31 toward the intermediate transfer belt 15B side through the conductive sheet 32 when the opening / closing unit 30 is closed. When the opening / closing unit 30 is opened, the guide member 31 contacts the conductive spring 33 by gravity. According to this configuration, when the opening / closing unit 30 is opened, the conductive spring 33 stops urging the guide member 31, so that friction between the conductive sheet 32 and the conductive spring 33 when opening and closing the opening / closing unit 30 can be suppressed.

[0033] Further, according to the image forming apparatus 100 according to the present embodiment, a first regulating member 41 is provided in the opening / closing unit 30 to regulate elastic deformation of the conductive spring 33 toward the guide member 31 side to a predetermined amount. When the opening / closing unit 30 is opened, the guide member 31 contacts the conductive spring 33 elastically deformed to the predetermined amount by gravity. Therefore, compared with the case where elastic deformation of the conductive spring 33 is not regulated to the predetermined amount, friction between the conductive sheet 32 and the conductive spring 33 can be suppressed.

[0034] Further, according to the image forming apparatus 100 according to the present embodiment, a second regulating member 42 is provided in the opening / closing unit 30 to regulate swinging of the guide member 31 toward the intermediate transfer belt 15B side in a state where the guide member 31 contacts the conductive spring 33 elastically deformed to a predetermined amount by gravity when the opening / closing unit 30 is opened. Therefore, compared with the case where swinging of the guide member 31 is not regulated, friction between the conductive sheet 32 and the conductive spring 33 can be prevented.

[0035] Also, according to the image forming apparatus 100 according to the present embodiment, since the image carrier is the intermediate transfer belt 15B wound around a plurality of rollers, in the image forming apparatus 100 that forms a color image, the friction between the conductive sheet 32 and the conductive spring 33 when opening and closing the opening / closing unit 30 can be suppressed.

[0036] The above embodiment may be modified as follows.

[0037] In the above embodiment, an example in which the conductive spring 33 is a torsion coil spring is shown, but as the conductive spring 33, a compression coil spring, a leaf spring, or the like may be used.

[0038] In the above embodiment, an example in which the cover 3C swings around the hinge 3H provided at the lower end portion is shown, but the cover 3C may be configured to be opened and closed by sliding in the left-right direction via a slide rail (not shown).

[0039] In the above embodiment, an example in which the image carrier is the intermediate transfer belt 15B is shown, but the image carrier may be a photosensitive drum provided in an image forming apparatus that forms a monochrome image.

Claims

1. A main body having an opening, An image carrier provided on the main body for carrying a toner image, An opening / closing unit provided at the opening and capable of opening and closing, A transfer roller provided on the opening / closing unit and contacting the image carrier when the opening / closing unit is closed, A guide member provided on the opening / closing unit so as to be swingable and guiding a sheet in a contact area between the image carrier and the transfer roller, A conductive sheet covering the guide member, A conductive spring provided on the opening / closing unit and urging the guide member toward the image carrier side via the conductive sheet when the opening / closing unit is closed, thereby pressing the guide member against a contact portion on the main body side, and An image forming apparatus characterized in that when the opening / closing unit is opened, the guide member contacts the conductive spring by gravity.

2. The opening / closing unit is provided with a first regulating member that regulates elastic deformation of the conductive spring toward the guide member side to a predetermined amount, The image forming apparatus according to claim 1, characterized in that when the opening / closing unit is opened, the guide member contacts the conductive spring elastically deformed to the predetermined amount by gravity.

3. The opening / closing unit is provided with a second regulating member that regulates swinging of the guide member toward the image carrier side in a state where the guide member contacts the conductive spring elastically deformed to the predetermined amount by gravity when the opening / closing unit is opened, the image forming apparatus according to claim 2.

4. The image forming apparatus according to claim 1, characterized in that the image carrier is an intermediate transfer belt wound around a plurality of rollers.

5. The image forming apparatus according to claim 1, characterized in that the opening / closing unit is rotatably supported by the main body.

6. The image forming apparatus according to claim 1, characterized in that the conductive spring is a torsion coil spring wound around a swing axis of the guide member.

Images