Image forming apparatus

Abstract

The wiring process that electrically connects the main body of the image forming apparatus and the developing unit with cables is omitted. [Solution] The image forming apparatus comprises a photoreceptor drum, a developing unit, a unit frame that is displaceable around an axis parallel to the rotation axis of the developing roller, and which moves the developing roller closer to the photoreceptor drum when displaced in one direction and moves the developing roller away from the photoreceptor drum when displaced in the other direction, a unit-side contact attached to the unit frame, and a main body-side contact, wherein the unit-side contact and the main body-side contact come into contact when the unit frame is displaced in one direction, and the contact between the unit-side contact and the main body-side contact is released when the unit frame is displaced in the other direction.

Description

Technical Field

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

Background Art

[0002] An image forming apparatus includes a developing unit that develops an electrostatic latent image into a toner image. For example, the developing unit is detachable from the main body of the image forming apparatus. Therefore, a unit frame on which the developing unit is mounted is installed on the main body of the image forming apparatus. The developing unit is detachably mounted on the unit frame. Such an image forming apparatus is disclosed in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Normally, a cable is used to electrically connect the main body of the image forming apparatus and the developing unit. For example, the unit frame on which the developing unit is mounted and the main body of the image forming apparatus are electrically connected by a cable. However, when a cable is used for the electrical connection between the main body of the image forming apparatus and the developing unit, it is difficult to replace the wiring process of electrically connecting the main body of the image forming apparatus and the developing unit with automatic production by a robot or the like because the posture of the cable is hard to be determined.

[0005] The present invention has been made to solve the above problems, and an object thereof is to provide an image forming apparatus capable of omitting the wiring process of electrically connecting the main body of the image forming apparatus and the developing unit with a cable.

Means for Solving the Problems

[0006] An image forming apparatus according to one aspect of the present invention comprises a photoreceptor drum, a developing unit having a developing roller positioned opposite the photoreceptor drum and rotatably supported, which supplies toner from the developing roller to an electrostatic latent image on the photoreceptor drum to develop a toner image, a unit frame to which the developing unit is detachably mounted, which is displaceable about an axis parallel to the rotation axis of the developing roller, which moves the developing roller closer to the photoreceptor drum by being displaced in one direction about the axis, and moves the developing roller away from the photoreceptor drum by being displaced in the other direction about the axis, a unit-side contact attached to the unit frame and electrically connected to the developing unit mounted on the unit frame, and a body-side contact positioned to be able to contact the unit-side contact. By displacing the unit frame in one direction from a state in which the unit-side contact and the body-side contact are not in contact, the unit-side contact and the body-side contact come into contact, and by displacing the unit frame in the other direction from a state in which the unit-side contact and the body-side contact are in contact, the contact between the unit-side contact and the body-side contact is released. [Effects of the Invention]

[0007] In the configuration of the present invention, the wiring process of electrically connecting the main body of the image forming apparatus and the developing unit with a cable can be omitted. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram of an image forming apparatus according to an embodiment. [Figure 2] This is a schematic diagram of an image forming unit according to an embodiment. [Figure 3] This is a perspective view of a developing unit according to an embodiment. [Figure 4] This is a perspective view of the unit frame and its surroundings (excluding the developing unit) according to the embodiment. [Figure 5] This is a schematic perspective view (viewed from above) of a unit frame according to an embodiment. [Figure 6]This is a schematic perspective view (viewed from below) of the unit frame according to the embodiment. [Figure 7] This is a schematic diagram of the unit frame according to the embodiment when it is in its normal position. [Figure 8] This is a schematic diagram showing the unit frame according to the embodiment in the attachment / detachment position. [Figure 9] This is a schematic diagram showing the pressed portion of the unit frame according to the embodiment when it is being pressed. [Figure 10] This is a schematic diagram showing the unit frame in an embodiment when the pressed portion is not being pressed. [Figure 11] This is a perspective view of the rear portion of the unit frame and its surrounding area according to the embodiment. [Figure 12] This is a perspective view of the unit-side contact according to the embodiment. [Modes for carrying out the invention]

[0009] The image forming apparatus 100 of this embodiment will be described below with reference to Figures 1 to 12, using a tandem-type color laser printer as an example. The present invention is not limited to color laser printers, but can also be applied to monochrome printers and multifunction devices.

[0010] For ease of understanding, the diagrams referenced in the following explanation use the XYZ Cartesian coordinate system. The Z direction is the vertical direction and corresponds to the up and down direction of the image forming apparatus 100. The flat surface on which the image forming apparatus 100 is installed is perpendicular to the Z direction. The direction of the arrow on the Z axis is upward, and the opposite direction is downward.

[0011] The X direction is one horizontal direction, and the Y direction is the other horizontal direction. For example, the X direction corresponds to the front-to-back direction of the image forming apparatus 100. The Y direction corresponds to the left-to-right direction of the image forming apparatus 100.

[0012] <Overall configuration of the image forming apparatus> As shown in FIG. 1, the image forming apparatus 100 of the present embodiment includes a main conveyance path MP. The image forming apparatus 100 also includes a sheet cassette CA. The sheet cassette CA is detachable from the main body of the image forming apparatus 100. The sheet cassette CA houses sheets S. The main conveyance path MP extends from the sheet cassette CA, passes through the transfer position and the fixing position in this order, and reaches the discharge tray ET.

[0013] In a printing job, the sheet S in the sheet cassette CA is supplied to the main conveyance path MP. Then, the sheet S is conveyed along the main conveyance path MP, and an image is printed on the conveyed sheet S. In other words, the transfer process of the toner image onto the conveyed sheet S is performed at the transfer position. At the fixing position, the fixing process of the toner image onto the sheet S is performed.

[0014] The image forming apparatus 100 includes image forming units P for four colors, cyan, magenta, yellow, and black. Each image forming unit P forms a toner image of the corresponding color. Hereinafter, the configuration of one image forming unit P will be described in detail. The basic configurations of the respective image forming units P are the same as each other. Therefore, the description of the configurations of the other image forming units P will be omitted by referring to the following description.

[0015] The image forming unit P has a configuration as shown in FIG. 2. The image forming unit P includes a developing unit 1. The image forming unit P also includes a photosensitive drum 10. The photosensitive drum 10 is unitized together with a charging device 101 and a cleaning device 102. Note that the image forming unit P includes an exposure device 103. There is one exposure device 103, which is shared by each image forming unit P.

[0016] When the image forming unit P forms an image, the photosensitive drum 10 rotates. The charging device 101 charges the outer peripheral surface of the photosensitive drum 10. The exposure device 103 exposes the outer peripheral surface of the photosensitive drum 10 to form an electrostatic latent image on the outer peripheral surface of the photosensitive drum 10. Then, the developing unit 1 supplies toner to the electrostatic latent image on the outer peripheral surface of the photosensitive drum 10 and develops the electrostatic latent image into a toner image. The cleaning device 102 removes residual toner on the outer peripheral surface of the photosensitive drum 10.

[0017] Returning to FIG. 1, the image forming apparatus 100 includes an intermediate transfer belt 104. The intermediate transfer belt 104 is an endless belt. The intermediate transfer belt 104 contacts the outer peripheral surface of the photosensitive drum 10 and is driven (rotated) in the direction indicated by arrow D in that state.

[0018] The image forming apparatus 100 includes a plurality of primary transfer rollers 105. One primary transfer roller 105 is assigned to each of the colors cyan, magenta, yellow, and black. Each primary transfer roller 105 is disposed on the inner peripheral side of the intermediate transfer belt 104. Each primary transfer roller 105 is disposed to face the photosensitive drum 10 carrying the toner image of the corresponding color with the intermediate transfer belt 104 interposed therebetween.

[0019] Also, the image forming apparatus 100 includes one secondary transfer roller 106. The secondary transfer roller 106 is press-contact with the outer peripheral surface of the intermediate transfer belt 104 at the transfer position. The secondary transfer roller 106 forms a transfer nip with the intermediate transfer belt 104. The main conveyance path MP passes through the transfer nip.

[0020] In a printing job, the sheet S is conveyed toward the transfer position (i.e., the transfer nip). The conveyed sheet S passes through the transfer nip.

[0021] The intermediate transfer belt 104 receives the primary transfer of toner images from each photoreceptor drum 10. The intermediate transfer belt 104 rotates with the toner images supported on its outer surface. As the sheet S passes through the transfer nip, the sheet S comes into contact with the outer surface of the intermediate transfer belt 104. This results in a secondary transfer of the toner image to the sheet S as it passes through the transfer nip.

[0022] Furthermore, various rotating parts of the image forming unit P, such as the photosensitive drum 10, rotate around an axis extending in the X direction. Similarly, the primary transfer roller 105 and the secondary transfer roller 106 also rotate around an axis extending in the X direction.

[0023] The image forming apparatus 100 includes a fixing unit F. The fixing unit F includes a heating roller and a pressure roller. The heating roller has a built-in heater. The pressure roller is pressed against the heating roller. The heating roller and the pressure roller are pressed against each other, forming a fixing nip at the fixing position.

[0024] In a print job, the sheet S, which has undergone toner image transfer processing, passes through the fuser nip. That is, the sheet S is sandwiched between the heating roller and the pressure roller in the fuser nip. The fuser unit F heats the sheet S as it passes through the fuser nip. Pressure is applied to the sheet S in the fuser nip. By heating and pressurizing the sheet S, which has undergone toner image transfer processing, the fuser unit F fixes the toner image to the sheet S. After the fixing process, the sheet S is discharged into the discharge tray ET.

[0025] The image forming apparatus 100 includes a transport unit (the reference numerals are omitted). The transport unit includes a transport roller pair. The transport roller pair includes a pair of rollers. The pair of rollers has a transport nip between them. The transport roller pair transports the sheet S that enters the transport nip by rotating. The transport unit transports the sheet S along the main transport path MP. The transport unit also transports the sheet S along the double-sided printing transport path DP, which will be described later.

[0026] The image forming apparatus 100 is capable of performing both single-sided printing jobs, in which a toner image is printed on only one side of a sheet S, and double-sided printing jobs, in which a toner image is printed on both sides of a sheet S. To perform double-sided printing jobs, the image forming apparatus 100 is equipped with a double-sided printing transport path DP.

[0027] The duplex printing transport path DP branches off from the main transport path MP at a branching point downstream of the fixing position in the sheet transport direction. Then, the duplex printing transport path DP rejoins the main transport path MP at a merging point upstream of the transfer position in the sheet transport direction.

[0028] If the execution job is a single-sided printing job, the sheet S passes through the transfer nip only once, and the transfer process is performed once on the sheet S while it is passing through the transfer nip. After the first transfer process, the sheet S is then discharged into the output tray ET.

[0029] If the execution job is a duplex printing job, the sheet S passes through the transfer nip twice, as the transfer process is performed once on each side of the sheet S. Specifically, when the sheet S passes through the transfer nip for the first time, the transfer process is performed on one side of the sheet S. After the first transfer process, after the rear end of the sheet S has passed the branching point but before the sheet S is completely discharged into the discharge tray ET, the sheet S is switched back. This causes the sheet S to be drawn into the duplex printing transport path DP from its rear end.

[0030] Subsequently, the sheet S is transported along the double-sided printing transport path DP. Then, the sheet S on the double-sided printing transport path DP is returned to the main transport path MP from the merging point. The sheet S returned to the main transport path MP is transported along the main transport path MP and passes through the transfer nip again. At this time, the orientation of the front and back sides of the sheet S is reversed compared to when it passed through the transfer nip the previous time. As a result, when the sheet S passes through the transfer nip for the second time, the transfer process is performed on the opposite side of the sheet S to the previous side.

[0031] <Configuration of the developing device> The following description focuses on one developing unit 1 and explains its configuration. The basic configuration of each developing unit 1 is the same. Therefore, the configurations of the other developing units 1 will be omitted, relying on the explanation below.

[0032] The developing unit 1 extends in the X direction, as shown in Figure 3. The developing unit 1 includes a developing container 110. The developing container 110 has its longitudinal direction in the X direction. The developing container 110 contains a developer containing toner. The developer contained in the developing container 110 is, for example, a magnetic one-component developer containing magnetic toner. The toner in the developing container 110 is used for developing.

[0033] The developing unit 1 includes a developing roller 11, as shown in Figure 2. The developing roller 11 is located inside the developing container 110. The developing roller 11 is supported so as to be rotatable around an axis extending in the X direction.

[0034] The developing roller 11 exposes its outer surface from the inside to the outside of the developing container 110. Specifically, the developing container 110 has an opening (not shown in numerals) at a position facing the photoreceptor drum 10. The outer surface of the developing roller 11 is exposed to the outside through this opening. As a result, the outer surface of the developing roller 11 and the outer surface of the photoreceptor drum 10 face each other. The developing roller 11 carries toner on its outer surface and supplies toner to the electrostatic latent image on the outer surface of the photoreceptor drum 10.

[0035] The developing roller 11 has a shaft 111, a sleeve 112, and a magnet 113. The shaft 111 extends in the X direction. The sleeve 112 is a cylindrical body extending in the X direction. The shaft 111 is inserted into the sleeve 112.

[0036] The sleeve 112 is rotatably supported around the axis of the shaft 111. For example, flanges FL (see Figure 3) are positioned at both axial ends of the shaft 111, rotatable relative to the shaft 111. The flanges FL rotate when power is transmitted from the motor M (see Figure 4). The sleeve 112 is fixed to the flanges FL and rotates together with the flanges FL.

[0037] The sleeve 112 has an outer surface facing the photoreceptor drum 10. That is, the outer surface of the sleeve 112 becomes the outer surface of the developing roller 11. Toner is carried on the outer surface of the sleeve 112, and this toner is supplied to the electrostatic latent image on the outer surface of the photoreceptor drum 10.

[0038] The magnet 113 is positioned inside the sleeve 112. The magnet 113 is fixed to the outer surface of the shaft 111 and extends along the axis of the shaft 111. The magnet 113 has multiple magnetic poles in the circumferential direction of the shaft 111. The magnetic force of the magnet 113 causes toner to be carried on the outer surface of the developing roller 11 (i.e., the outer surface of the sleeve 112), and a magnetic brush is formed on the outer surface of the developing roller 11.

[0039] Furthermore, the developing unit 1 includes a metal regulating blade 12. The regulating blade 12 is held in a metal blade holder 120. The regulating blade 12 is positioned upstream of the developing roller 11 in the rotational direction of the developing roller 11, relative to the area where the developing roller 11 and the photosensitive drum 10 face each other.

[0040] The regulating blade 12 is positioned so that its tip is close to the outer surface of the developing roller 11 (i.e., the outer surface of the sleeve 112). The tip of the regulating blade 12 faces the outer surface of the developing roller 11 at a predetermined distance.

[0041] The developing unit 1 comprises two agitation screws MS. Each agitation screw MS is located inside the developing container 110. Each agitation screw MS is supported so as to be rotatable around an axis extending in the X direction.

[0042] Each stirring screw MS has a structure in which blades are spirally wound around its axis of rotation. Each stirring screw MS conveys the developer in the X direction while stirring it as it rotates. Each stirring screw MS conveys the developer in opposite directions to each other.

[0043] The developer in the developing unit 1 becomes electrically charged when agitated and is supported on the outer surface of the developing roller 11 to form a magnetic brush. The magnetic brush on the outer surface of the developing roller 11 passes between the developing roller 11 and the regulating blade 12, and is regulated to a certain layer thickness by the regulating blade 12.

[0044] Subsequently, the rotation of the developing roller 11 transports a magnetic brush of a predetermined thickness to the area where the developing roller 11 and the photoreceptor drum 10 face each other. A developing voltage is applied to the developing roller 11. This creates a potential difference between the developing roller 11 and the photoreceptor drum 10, and toner in the magnetic brush is supplied to the photoreceptor drum 10.

[0045] <Support frame for the developing unit> As shown in Figure 4, the image forming apparatus 100 includes a unit frame 2. The unit frame 2 is installed on the main body of the image forming apparatus 100. One unit frame 2 is assigned to each developing unit 1. Each unit frame 2 supports the corresponding developing unit 1. Each developing unit 1 is detachably mounted to the corresponding unit frame 2. That is, each developing unit 1 is detachably mounted to the main body of the image forming apparatus 100.

[0046] The following will focus on one unit frame 2 and describe its configuration in detail. The configuration of each unit frame 2 is the same. Therefore, the descriptions of the configurations of the other unit frames 2 will be omitted, relying on the explanation below.

[0047] The unit frame 2 has the structure shown in Figures 5 and 6. Note that Figures 5 and 6 are schematic representations of the unit frame 2 and do not accurately depict its actual dimensions and shape.

[0048] The unit frame 2 is supported so as to be displaceable around an axis Ax parallel to the rotation axis of the developing roller 11. Note that the X direction is synonymous with the axial direction of axis Ax (i.e., the axial direction of the rotation axis of the developing roller 11).

[0049] The unit frame 2 is displaceable in one direction and in the opposite direction around the axis Ax. In other words, the developing unit 1 is displaceable in one direction and in the other direction around the axis Ax. By displacing the developing unit 1 around the axis Ax, the developing roller 11 can be brought closer to the photoreceptor drum 10 or moved further away from the photoreceptor drum 10. Figure 7 shows the position of the unit frame 2 when the developing roller 11 is close to the photoreceptor drum 10. Figure 8 shows the position of the unit frame 2 when the developing roller 11 is moved further away from the photoreceptor drum 10.

[0050] When the developing unit 1 is attached to the unit frame 2, the unit frame 2 is held in the attachment / detachment position (see Figure 8). In this state, the developing unit 1 is attached to the unit frame 2, and by displacing the unit frame 2 in one direction around the axis Ax, the unit frame 2 returns to its normal position (see Figure 7). As a result, the developing roller 11 is positioned opposite the photoreceptor drum 10. In other words, the print job can now be executed.

[0051] On the other hand, by displacing the unit frame 2, which is in its normal position, in another direction around the axis Ax, the unit frame 2 reaches the attachment / detachment position (see Figure 8). This causes the developing roller 11 to separate from the photoreceptor drum 10. By holding the unit frame 2 in the attachment / detachment position, the developing unit 1 can be removed from the unit frame 2.

[0052] The unit frame 2 has a frame bottom 21. The frame bottom 21 is plate-shaped with the Z direction being the thickness direction. When viewed from the Z direction, the frame bottom 21 is approximately rectangular with the X direction being the longitudinal direction and the Y direction being the short direction. The developing unit 1 is placed on the frame bottom 21. Frame walls 210 are provided at both ends of the frame bottom 21 in the Y direction, with the walls rising upwards. The pair of frame walls 210 suppress misalignment of the developing unit 1 in the Y direction on the frame bottom 21.

[0053] Furthermore, the unit frame 2 has a pair of support parts 22. The pair of support parts 22 are provided at one end (right end) in the Y direction of the frame bottom 21. One support part 22 is located on one side (front) in the X direction of the frame bottom 21, and the other support part 22 is located on the other side (rear) in the X direction of the frame bottom 21. One support part 22 is a cylindrical body with axis Ax as its central axis. The other support part 22 is a cylindrical body with axis Ax as its central axis.

[0054] The main body of the image forming apparatus 100 is provided with a circular fitting hole centered on axis Ax, and a cylindrical fitting shaft centered on axis Ax. One support part 22 (cylindrical body) fits into the fitting hole on the main body side, and the other support part 22 (cylindrical body) fits into the fitting shaft on the main body side. As a result, the unit frame 2 is supported so as to be displaceable around axis Ax.

[0055] The unit frame 2 has a rear frame portion 23. The rear frame portion 23 holds the drive system, including the gear G and the motor M (see Figure 4). When the developing unit 1 is mounted on the unit frame 2, that is, when the developing unit 1 is positioned on the bottom portion 21 of the frame, the rotating parts of the developing unit 1, such as the developing roller 11, are connected to the motor M via the gear G.

[0056] Here, the unit frame 2 has a pressed portion 20 on the frame bottom 21. The pressed portion 20 protrudes downward from the frame bottom 21. The pressed portion 20 is positioned on the opposite side in the Y direction from the position of the pair of support portions 22 on the frame bottom 21. The pair of support portions 22 are positioned on the right side, while the pressed portion 20 is positioned on the left side.

[0057] The main body of the image forming apparatus 100 is provided with a slider that can slide in the X direction, although this is not shown in the figure. The slider is located below the bottom of the frame 21.

[0058] The slider has a pressing portion 200 (see Figures 9 and 10) that protrudes upward. The part to be pressed 20 is positioned on the movement path of the pressing portion 200 in the X direction. This allows the part to be pressed 20 to be pressed upward by the pressing portion 200 or released by moving the slider in the X direction.

[0059] Figure 9 schematically illustrates the state in which the pressed portion 20 is pressed upward by the pressing portion 200. Figure 10 illustrates the state in which the upward pressure on the pressed portion 200 by the pressing portion 200 is released. From the state shown in Figure 9, the state shown in Figure 10 is achieved by moving the slider to one side (front side) in the X direction. In Figure 10, the pressed portion 20 in the state pressed by the pressing portion 200 is shown by a dashed line.

[0060] When the pressing part 200 is not pressing against the pressed part 20, the left end of the frame bottom 21 is positioned lower than the right end when viewed from the X direction (see Figure 8). As a result, the developing roller 11 is held in a position separated from the photoreceptor drum 10. In other words, the unit frame 2 is held in the attachment / detachment position.

[0061] With the unit frame 2 held in the attachment / detachment position, moving the slider in the X direction and pressing the pressed portion 20 upward with the pressing portion 200 causes the left end of the frame bottom 21 to be displaced upward when viewed from the X direction, and the vertical positions of both the left and right ends of the frame bottom 21 become approximately the same (see Figure 7). As a result, the developing roller 11 is positioned opposite the photoreceptor drum 10. In other words, the unit frame 2 returns to its normal position.

[0062] The slider having the pressing portion 200 is moved back and forth in the X direction by the user's operation of the image forming apparatus 100. That is, the slider moves in the X direction by the user's operation, causing the pressed portion 20 to be pressed upward by the pressing portion 200, or the pressure to be released.

[0063] For example, although not shown in the diagram, the developing unit 1 and its surroundings are covered by a front cover. The front cover is rotatable (openable and closable) around an axis extending in the Y direction. When the front cover is opened, the developing unit 1 is exposed, and the developing unit 1 can be attached to and detached in the X direction.

[0064] The slider, which has a pressing portion 200, is connected to the front cover via a link member (not shown). As a result, when the front cover is opened, the slider is pulled to one side in the X direction (front side), and the pressing portion 200 moves to that side in the X direction. When the front cover is closed, the slider is pushed back to the other side in the X direction (rear side), and the pressing portion 200 moves to the other side in the X direction.

[0065] When the front cover is open, the pressing part 200 is held in a position where it does not come into contact with the pressed part 20 (see Figure 10). In other words, the pressing part 200 does not press the pressed part 20 upward. As a result, the unit frame 2 is held in the attachment / detachment position.

[0066] As the front cover is closed from an open position, the pressing portion 200 approaches the pressed portion 20. When the front cover is completely closed, the pressed portion 20 rides onto the pressing portion 200 (see Figure 9). In other words, the pressed portion 20 is pressed upward by the pressing portion 200. As a result, the unit frame 2 returns to its normal position. If the front cover is not opened in this state, the unit frame 2 will be held in its normal position.

[0067] As the front cover is opened from its closed position, the pressing portion 200 separates from the pressed portion 20, thus releasing the upward pressure applied by the pressing portion 200 to the pressed portion 20 (see Figure 10). The unit frame 2 then reaches the attachment / detachment position. Thereafter, by keeping the front cover open, the unit frame 2 is held in the attachment / detachment position.

[0068] <Contacts on the main unit and contacts on the unit side> The image forming apparatus 100 is equipped with a main body-side contact 3 (see Figures 7 and 8). The main body-side contact 3 is installed on the main body of the image forming apparatus 100 and connected to a circuit board (not shown). This circuit board controls power supply to the developing unit 1, etc. The main body-side contact 3 is, for example, a wire spring made of metal wire.

[0069] Furthermore, as shown in Figures 11 and 12, the image forming apparatus 100 is equipped with a unit-side contact 4. The unit-side contact 4 is attached to the unit frame 2. The unit-side contact 4 is electrically connected to the developing unit 1 mounted on the unit frame 2. In other words, when the developing unit 1 is removed from the unit frame 2, the electrical connection between the developing unit 1 and the unit-side contact 4 is released.

[0070] The unit-side contact 4 is a leaf spring formed by bending a metal plate. The unit-side contact 4 is positioned on the end face of the outer edge of the frame's rear surface 23 when viewed from the X direction. The unit-side contact 4 generates a biasing force in the circumferential direction centered on the axis Ax when viewed from the X direction. The unit-side contact 4 integrally has a mounting portion 40 that is attached to the frame's rear surface 23. For example, the unit-side contact 4 is attached to the unit frame 2 by screwing the mounting portion 40 to the frame's rear surface 23.

[0071] In the developing unit 1, the developing roller 11 and the regulating blade 12 are electrically connected to the unit-side contact 4, respectively. Compression coil springs 41 and 42 are used to electrically connect the developing unit 1 to the unit-side contact 4. The compression coil springs 41 and 42 are held in the unit frame 2 so as to generate a biasing force in the X direction. The compression coil springs 41 and 42 are electrically connected to the unit-side contact 4 by bringing one end of each in the X direction into contact with the unit-side contact 4 (for example, the mounting portion 40). Note that in Figure 12, the unit frame 2 is omitted from the illustration in order to clarify the contact positions of the compression coil springs 41 and 42 with respect to the unit-side contact 4.

[0072] The other end of the compression coil spring 41 in the X direction is tightly wound so as not to be compressed in the X direction. The other end of the compression coil spring 41 in the X direction contacts the developing roller 11. For example, a retaining hole (not shown) extending in the X direction is formed in the unit frame 2, and the compression coil spring 41 is placed in the retaining hole. The shaft 111 is positioned by being inserted into the retaining hole of the unit frame 2. As a result, the X-direction end surface of the shaft 111 contacts the compression coil spring 41, and the developing roller 11 and the unit-side contact 4 are electrically connected via the compression coil spring 41.

[0073] The other end of the compression coil spring 42 in the X direction is similarly tightly wound so as not to be compressed in the X direction. The other end of the compression coil spring 42 in the X direction contacts the blade holder 120. As a result, the regulating blade 12 and the unit-side contact 4 are electrically connected via the compression coil spring 42.

[0074] The unit-side contact 4 comes into contact with or moves away from the main body-side contact 3 as the unit frame 2 is displaced around the axis Ax. Specifically, the main body-side contact 3 is positioned on the movement path of the unit-side contact 4 when the unit frame 2 is displaced around the axis Ax, as viewed from the X direction. Furthermore, the position of the main body-side contact 3 in the X direction is the same as the position of the unit-side contact 4 in the X direction. As a result, as shown in Figures 7 and 8, the displacement of the unit frame 2 around the axis Ax causes the unit-side contact 4 to move away from or approach the main body-side contact 3.

[0075] When the unit frame 2 is held in the attachment / detachment position (see Figure 8), the unit-side contact 4 does not contact the main body-side contact 3. In other words, simply attaching the developing unit 1 to the unit frame 2 does not electrically connect the main body of the image forming apparatus 100 to the developing unit 1. Furthermore, when removing the developing unit 1 from the unit frame 2, the main body of the image forming apparatus 100 and the developing unit 1 are not electrically connected.

[0076] When the unit frame 2 is held in the attachment / detachment position, that is, when the unit-side contact 4 and the main body-side contact 3 are not in contact, displacing the unit frame 2 in one direction (clockwise) around the axis Ax causes the unit-side contact 4 and the main body-side contact 3 to come into contact, as shown in Figure 7. The position of the unit frame 2 when the unit-side contact 4 and the main body-side contact 3 are in contact is the normal position. In other words, by displacing the unit frame 2 in one direction around the axis Ax from the attachment / detachment position to the normal position, the unit-side contact 4 and the main body-side contact 3 come into contact.

[0077] When the unit frame 2 is held in its normal position, that is, when the unit-side contact 4 and the main body-side contact 3 are in contact, displacing the unit frame 2 in the opposite direction (counterclockwise) around the axis Ax releases the contact between the unit-side contact 4 and the main body-side contact 3, as shown in Figure 8. In other words, by displacing the unit frame 2 in the opposite direction around the axis Ax, moving it from the normal position to the detachable position, the unit-side contact 4 and the main body-side contact 3 become non-contact.

[0078] In this embodiment, the unit-side contact 4 can be brought into contact with or separated from the main body-side contact 3 by displacing the unit frame 2 around the axis Ax. In other words, the electrical connection of the unit frame 2 to the main body of the image forming apparatus 100 can be switched on and off simply by displacing the unit frame 2 around the axis Ax.

[0079] This eliminates the need for a dedicated step in the assembly process of the image forming apparatus 100 to electrically connect the main body of the image forming apparatus 100 to the unit frame 2. In other words, the wiring step of electrically connecting the main body of the image forming apparatus 100 and the unit frame 2 with cables (including harnesses, etc.) can be omitted.

[0080] For example, in recent years, the assembly of image forming apparatus 100 is often carried out by automated production using robots, etc. However, the wiring process, which involves handling cables and other components whose orientation is not fixed, is unsuitable for automated production.

[0081] On the other hand, in this embodiment, since it is only necessary to displace the unit frame 2 around the axis Ax, it is suitable for automated production. If the electrical connection between the main body of the image forming apparatus 100 and the unit frame 2 is performed by automated production, the automated production rate will increase. This will reduce the cost of assembling the image forming apparatus 100.

[0082] Furthermore, in this configuration, when the developing unit 1 is removed from the unit frame 2, the unit frame 2 is held in the attachment / detachment position, so that the main body of the image forming apparatus 100 and the developing unit 1 are not electrically connected. This prevents the developing unit 1 from being removed from the unit frame 2 while the main body of the image forming apparatus 100 and the developing unit 1 are electrically connected. Moreover, during the assembly of the image forming apparatus 100, even with the developing unit 1 attached to the unit frame 2, the assembly work can be easily performed with the electrical connection between the main body of the image forming apparatus 100 and the developing unit 1 disconnected.

[0083] Furthermore, in this embodiment, the unit frame 2 has a mounting position P1 (see Figure 7) on a line extending from the axis Ax in a first direction D1 when viewed from the X direction, where the unit-side contact 4 is attached. In addition, the unit frame 2 has a pressed position P2 (see Figure 7) on a line extending in a second direction D2, which is different from the first direction D1, when viewed from the X direction. The unit frame 2 has a pressed portion 20 at the pressed position P2. That is, the pressed position P2 is the position that is pressed by the pressing portion 200.

[0084] In this configuration, by pressing the pressed portion 20 of the unit frame 2 (i.e., the pressed position P2), the unit frame 2 can be easily displaced in one direction around the axis Ax. That is, by pressing the pressed portion 20 of the unit frame 2, the unit-side contact 4 can be easily brought into contact with the main body-side contact 3.

[0085] Furthermore, in this embodiment, the unit-side contact 4 is composed of a leaf spring. The unit-side contact 4, acting as a leaf spring, presses against the main body-side contact 3 when in contact with it. This ensures that contact between the unit-side contact 4 and the main body-side contact 3 is reliably maintained.

[0086] In this embodiment, when viewed from the X direction, the distance L1 in the first direction D1 from the axis Ax to the mounting position P1 is shorter than the distance L2 in the second direction D2 from the axis Ax to the pressed position P2. Therefore, the moment with axis Ax as the axis of rotation and mounting position P1 as the point of application is smaller than the moment with axis Ax as the axis of rotation and pressed position P2 as the point of application. As a result, when the unit frame 2 is displaced in one direction around axis Ax to reach the normal position, the biasing force generated by the contact between the unit-side contact 4 and the main body-side contact 3 can be suppressed from interfering.

[0087] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the description of the embodiments above, and furthermore, all modifications within the meaning and scope equivalent to the claims are included. [Explanation of Symbols]

[0088] 1 developing unit 2 Unit Frames 3. Main unit side contacts 4 Unit-side contacts 10 Photoconductor drum 11. Developing Roller 100 Image forming apparatus 200 Pressing part Ax axis D1 1st direction D2 2nd direction L1 distance L2 distance P1 Mounting position P2 Pressed position

Claims

1. Photosensitive drum and A developing unit having a developing roller positioned opposite the photoreceptor drum and rotatably supported, which supplies toner from the developing roller to the electrostatic latent image on the photoreceptor drum to develop a toner image, The developing unit is detachably mounted to a unit frame that is displaceable about an axis parallel to the rotation axis of the developing roller, and by displacing in one direction about the axis, the developing roller is moved in a direction toward the photoreceptor drum, and by displacing in the other direction about the axis, the developing roller is moved in a direction toward away from the photoreceptor drum, A unit-side contact attached to the unit frame and electrically connected to the developing unit mounted on the unit frame, It comprises a main body-side contact positioned to be in contact with the unit-side contact, An image forming apparatus in which, by displacing the unit frame in one direction from a state in which the unit-side contact and the main body-side contact are not in contact, the unit-side contact and the main body-side contact come into contact, and by displacing the unit frame in the other direction from a state in which the unit-side contact and the main body-side contact are in contact, the contact between the unit-side contact and the main body-side contact is released.

2. The unit frame has mounting positions on a line extending in a first direction from the axis, as viewed from the axial direction of the axis, where the unit-side contacts are attached. The unit frame has a position to be pressed on a line extending in a second direction different from the first direction from the axis, as viewed from the axial direction of the axis, The image forming apparatus according to claim 1, wherein the pressed position is pressed, causing the unit frame to be displaced in one direction and the unit-side contact to come into contact with the main body-side contact.

3. The image forming apparatus according to claim 2, wherein the distance in the first direction from the axis to the mounting position is shorter than the distance in the second direction from the axis to the pressed position.

4. The image forming apparatus according to claim 3, wherein the unit-side contact is a leaf spring, and when in contact with the main body-side contact, it presses the main body-side contact.

Images