JP2014044288A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus in which a load for moving a holding member can be reduced and the holding member can be accurately positioned by a simple constitution.SOLUTION: A holding member 100 holding a developing unit 60 is turnably supported between a contact position where a developing roller 61 contacts with a corresponding photosensitive drum 51 and a separation position where the front-side end is positioned below the contact position, and the developing roller 61 is separated from the corresponding photosensitive drum 51, with respect to a body housing 2 with a rear side in the body housing 2 as a turning center; and is movably supported between the separation position and a pull-out position where the holding member is pulled out to the outside of the body housing 2, with respect to the body housing 2. An image forming apparatus comprises: a compression coil spring 230 for energizing the front-side portion of the holding member 100 toward the contact position from the separation position; and a positioning part 223 disposed in the body housing 2, for positioning the holding member 100 at the contact position by abutting a part of the holding member 100 turning from the separation position to the contact position on it.

Description

  The present invention relates to an image forming apparatus including a holding member that detachably holds a plurality of developing devices and can be pulled out from the inside of the apparatus main body.

  As an electrophotographic image forming apparatus, conventionally, a plurality of photosensitive drums arranged in the front-rear direction, a plurality of developing units provided corresponding to the respective photosensitive drums below the photosensitive drum, and a plurality of developing units There has been known one provided with a holding member for holding a container and an elevating mechanism for raising and lowering a mounting table on which the holding member is placed (see Patent Document 1). In the image forming apparatus of Patent Document 1, the developing member can be replaced by pulling down the holding member by the lifting mechanism and pulling it out from the main body. After replacing the developing device, the holding member is attached to the main body and pushed up by the lifting mechanism. Thus, an image can be formed on a sheet.

JP 2006-184553 A

  By the way, in the prior art, when the developing device is replaced, the entire holding member is moved in parallel up and down, so that the load for moving the holding member is large. Further, since the entire holding member is translated in the vertical direction, it is difficult to accurately determine the position when the holding member is pushed up, that is, the position of the holding member in a state where image formation is possible. Therefore, the conventional technology has a problem that the configuration of the lifting mechanism and the configuration for positioning the holding member are complicated.

  The present invention has been made in view of the above background, and provides an image forming apparatus capable of reducing the load for moving the holding member and accurately positioning the holding member with a simple configuration. With the goal.

In order to achieve the above-described object, an image forming apparatus of the present invention corresponds to an apparatus main body, a plurality of photosensitive drums arranged in a direction intersecting the vertical direction in the apparatus main body, and each photosensitive drum. A plurality of developing units each having a developing roller for supplying a developer to a corresponding photosensitive drum, and each developing unit is detachably held, and at least a part of the developing unit from the inside of the apparatus main body is retained. And a holding member that can be pulled out of the apparatus main body.
The holding member has a contact position where the developing roller contacts the corresponding photosensitive drum with respect to the apparatus main body with the upstream side in the pull-out direction in the apparatus main body as a rotation center, and an end portion on the downstream side in the pull-out direction below the contact position. The developing roller is supported so as to be rotatable between the developing roller and a separating position separated from the corresponding photosensitive drum, and the holding member is pulled out of the apparatus main body with respect to the apparatus main body. It is supported so as to be movable between the drawing positions.
The image forming apparatus further includes a first urging member that urges a portion of the holding member on the downstream side in the pulling direction from the separated position toward the contact position, and the apparatus main body. And a positioning portion that positions the holding member at the contact position by abutting a part of the rotated holding member.

  According to such a configuration, since the holding member is supported so as to be rotatable about the upstream side in the pull-out direction, the holding member is moved as compared with the configuration in which the entire holding member is translated in the vertical direction. Therefore, it is possible to reduce the load. Thereby, while being able to simplify the structure for moving a holding member, since a holding member can be moved easily, operativity can be improved. Further, in the configuration in which the entire holding member is translated in the vertical direction, it is necessary to determine both the upstream side and the downstream side of the holding member in the pulling direction when the holding member is moved to the contact position. Therefore, the holding member can be positioned relatively accurately with a simple configuration as compared with the configuration for determining both positions.

In the image forming apparatus described above, the holding member is provided corresponding to each developing device, and includes a plurality of second urging members that urge the developing roller toward the corresponding photosensitive drum when at least in the contact position. It can be set as the structure which has.
In this case, when the holding member is in the contact position, the upward moment around the rotation center acting on the holding member by the first biasing member is around the rotation center acting on the holding member by the plurality of second biasing members. It can be configured to be larger than the downward moment.

  According to this, since the second urging member is provided corresponding to each developing roller, each developing roller is attached to the corresponding photosensitive drum only by the first urging member without providing the second urging member. Each developing roller can be urged with high accuracy as compared with the configuration in which the urging is urged. Further, since the upward moment is larger than the downward moment when the holding member is in the contact position, in the configuration in which the plurality of second urging members are provided, the developing roller is separated from the corresponding photosensitive drum. Can be suppressed.

  The image forming apparatus described above can be configured to include a stopper that is provided in the apparatus main body and maintains the holding member rotated from the contact position to the separated position at the separated position.

  According to this, since the holding member can be maintained at the separated position, an operation when the holding member is moved from the separated position to the drawn position or moved from the drawn position to the contact position as compared with a configuration without a stopper. Can be improved.

  The above-described image forming apparatus includes a first guide portion that is provided in the apparatus main body and guides the rotation between the contact position and the separation position of the holding member, and the first guide portion is the rotation center of the holding member. The holding member is engaged with a part of the holding member, and when the holding member is between the contact position and the separation position, the movement of the holding member to the drawing position is restricted. When in the separation position, the holding member can be configured to be allowed to move to the drawing position.

  According to this, it is possible to prevent the holding member from being pulled out when it is between the contact position and the separation position.

  The above-described image forming apparatus includes a second guide portion that is provided in the apparatus main body and guides the movement of the holding member between the separation position and the pull-out position, and the second guide portion is a lower end portion of the first guide portion. It can be set as the structure extended toward the drawing direction downstream side.

  In the above-described image forming apparatus, a plurality of first urging members may be provided and arranged symmetrically with respect to the rotation axis direction center of the photosensitive drum of the holding member.

  According to this, since the holding member can be urged from the separated position toward the contact position with a good balance in the direction of the rotation axis of the photosensitive drum, the position accuracy of the holding member can be improved.

  According to the present invention, the load for moving the holding member can be reduced, and the holding member can be accurately positioned with a simple configuration.

1 is a diagram illustrating an overall configuration of a color printer as an example of an image forming apparatus according to an embodiment of the present disclosure. It is a figure which shows the color printer which concerns on embodiment of the state which has a front cover in an open position. It is a figure which shows the color printer which concerns on embodiment of the state which has a holding member in a separation position. It is a figure which shows the color printer which concerns on embodiment of the state which has a holding member in a drawer position. It is an enlarged view of a guide part. It is the figure which looked at the holding member and compression coil spring in a contact position from the front. It is a figure which shows the whole structure of the color printer which concerns on a modification. It is a figure which shows the color printer which concerns on the modification in the state which has a front cover in an open position. It is a figure which shows the color printer which concerns on the modification in the state which has a holding member in a separation position. It is a figure which shows the color printer which concerns on the modification of the state which has a holding member in a drawing-out position.

  Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, first, a schematic configuration of the color printer 1 as an example of the image forming apparatus will be described, and then a detailed configuration of the color printer 1 according to the characteristic part of the present invention will be described. In the following description, the direction will be described with reference to the user who uses the color printer 1. That is, the left side in FIG. 1 is “front”, the right side is “rear”, the front side is “right”, and the back side is “left”. Also, the vertical direction in FIG.

<Schematic configuration of color printer>
As shown in FIG. 1, the color printer 1 includes a main body housing 2 as an example of an apparatus main body, a paper feeding unit 3 that supplies paper S, and an image forming unit 4 that forms an image on the supplied paper S. It is mainly equipped with. In addition, the image forming unit 4 mainly includes a photoconductor unit 5, a developing unit 6, a transfer unit 7, and a fixing unit 8.

  The main body housing 2 has an opening 2A for allowing the developing unit 6 (holding member 100) to be pulled out, and a front cover 21 for opening and closing the opening 2A. The front cover 21 is pivoted about the lower part to displace the main body housing 2 between a closed position shown in FIG. 1 that covers the opening 2A and an open position shown in FIG. 2 that exposes the opening 2A. It is provided as possible.

  Returning to FIG. 1, the paper feed unit 3 is provided in the lower part of the main body housing 2, and a paper feed tray 31 that stores the paper S, and a paper supply that supplies the paper S from the paper feed tray 31 to the image forming unit 4. The mechanism 32 is mainly provided. The sheets S in the sheet feed tray 31 are separated one by one by the sheet supply mechanism 32 and supplied to the image forming unit 4.

  The photoconductor unit 5 is provided at an upper portion in the main body housing 2 and mainly includes four photoconductor drums 51, four chargers 52, and four exposure heads 53. The four photoconductor drums 51 are positioned so that the center of rotation of the four photosensitive drums 51 is located higher in the direction intersecting the vertical direction, specifically, in the direction connecting the diagonally upper front and the rear diagonally lower in FIG. In this way, one charger 52 and one exposure head 53 are arranged corresponding to each photosensitive drum 51. The exposure head 53 is provided with a light emitting unit such as a plurality of light emitting diodes (not shown) arranged on the surface facing the photoconductive drum 51, and the light emitting unit blinks based on the image data, whereby the photoconductive drum 51 has a light emitting unit. Expose the surface.

  The developing unit 6 is disposed below the photosensitive unit 5, and a total of four developing units 60 provided corresponding to the photosensitive drums 51, and a substantially box-shaped holding member 100 that holds the developing units 60. And has mainly. Each developing device 60 includes a developing roller 61 and a supply roller 62 for supplying toner as an example of a developer to the corresponding photosensitive drum 51, a layer thickness regulating blade 63, and a toner storage portion 64 for storing the toner. And so on.

  The transfer unit 7 is provided above the photosensitive unit 5 and mainly includes a drive roller 71, a driven roller 72, an intermediate transfer belt 73, four primary transfer rollers 74, and a secondary transfer roller 75. doing. The intermediate transfer belt 73 is stretched between the driving roller 71 and the driven roller 72, and the lower surface is disposed to face the four photosensitive drums 51. The primary transfer roller 74 is disposed to face the photosensitive drum 51 through the intermediate transfer belt 73, and the secondary transfer roller 75 is disposed to face the drive roller 71 through the intermediate transfer belt 73.

  The fixing unit 8 is provided above the driving roller 71, and mainly includes a heating roller 81 and a pressure roller 82 that is disposed to face the heating roller 81 and presses the heating roller 81.

  In the image forming unit 4, the surface of the photosensitive drum 51 is uniformly charged by the charger 52 and then exposed by the exposure head 53, whereby an electrostatic latent image based on image data is formed on the photosensitive drum 51. Is formed. Further, the toner in the toner container 64 is supplied to the developing roller 61 via the supply roller 62 and enters between the developing roller 61 and the layer thickness regulating blade 63 so as to form a thin layer having a constant thickness. Supported on. Then, the toner on the developing roller 61 is supplied to the photosensitive drum 51, whereby the electrostatic latent image is visualized and a toner image is formed on the photosensitive drum 51.

  The toner images formed on the respective photosensitive drums 51 are sequentially superimposed and transferred from the respective photosensitive drums 51 onto the intermediate transfer belt 73. Then, the sheet S conveyed from the sheet feeding unit 3 passes between the intermediate transfer belt 73 and the secondary transfer roller 75, whereby the toner image on the intermediate transfer belt 73 is transferred to the sheet S. The sheet S on which the toner image has been transferred passes between the heating roller 81 and the pressure roller 82 to thermally fix the toner image, and is formed on the upper surface of the main body case 2 from within the main body case 2 by the discharge roller 23. The paper is discharged onto the discharged paper discharge tray 22.

<Detailed configuration of color printer>
Next, a detailed configuration of the color printer 1 according to the characteristic part of the present invention will be described.
In the color printer 1, the holding member 100 is a photosensitive member corresponding to the developing roller 61 shown in FIGS. 1 and 2 with respect to the main body case 2 with the rear side upstream in the pull-out direction in the main body case 2 as a rotation center. A contact position that contacts the body drum 51, and a separation position in which the front end, which is the downstream side in the drawing direction shown in FIG. 3, is located below the contact position and the developing roller 61 is separated from the corresponding photosensitive drum 51. It is supported so that it can rotate between the two. Further, the holding member 100 is movable with respect to the main body housing 2 between a separation position in the main body housing 2 shown in FIG. 3 and a drawing position pulled out of the main body housing 2 shown in FIG. It is supported.

  As shown in FIG. 1, the holding member 100 is formed in a substantially box shape with an upper opening, and holds each developing device 60 in a detachable manner (see FIG. 4). A handle 110 having a substantially U shape in plan view is provided on the front wall of the holding member 100. The handle 110 is gripped by the user when the holding member 100 is rotated between the contact position and the separation position and when the holding member 100 is moved between the separation position and the extraction position.

  A total of eight second urging members 120 are provided inside the holding member 100, specifically, on the upper surface of the lower wall 101, corresponding to each developing device 60. The second urging member 120 is, for example, a compression coil spring, and is disposed one by one (only one is shown) below each developing device 60 mounted on the holding member 100 in a state of being separated left and right. The second urging member 120 is pressed and shrunk when the holding member 100 is in the contact position, thereby pressing the corresponding developing device 60 substantially upward via the developing device support plate 130, thereby developing the developing device 60. The roller 61 is urged toward the corresponding photosensitive drum 51.

  The left and right side walls (only one shown) of the holding member 100 are provided with a substantially cylindrical rotating shaft portion 140 and a positioning shaft portion 150 that protrude outward in the left-right direction. The rotation shaft portion 140 is provided at the rear portion of the holding member 100 and rotates when the holding member 100 is rotated between the contact position and the separation position in a state where the rotation member 140 is supported by a shaft support portion 210 described later. Act as the center. Further, the positioning shaft portion 150 is provided at the front portion of the holding member 100 and engages with a guide portion 220 described later when the holding member 100 is in a contact position, a separation position, or the like.

  In the main body housing 2 of the color printer 1, a shaft support portion 210, a guide portion 220, a compression coil spring 230 as a first urging member, a holding member support plate 240, and a stopper 250 are provided. .

  The shaft support portion 210 is a portion that supports the holding member 100 so as to be rotatable between the contact position and the separation position, and is provided on both left and right sides of the rear portion of the holding member 100 corresponding to the left and right rotation shaft portions 140. One is provided (only one is shown). The shaft support portion 210 extends downward from the lower wall portion 211 capable of supporting the rotation shaft portion 140 from below and the rear end of the lower wall portion 211, and the rotation shaft portion 140 can contact from the front side. It is formed in a substantially L shape having a rear wall portion 212.

  The guide part 220 is a part that guides the movement of the front part of the holding member 100, and corresponds to the left and right positioning shaft parts 150, one on each front part of the inner surfaces of the left and right side walls of the main body housing 2 (one side Only shown). The guide portion 220 is formed in a groove shape that can be engaged with the positioning shaft portion 150 that is a part of the holding member 100, and guides the rotation between the contact position and the separation position of the holding member 100. 1 guide part 221, and the 2nd guide part 222 which guides the back-and-forth movement between the separation position and the drawing position of holding member 100 are provided.

  The first guide portion 221 is a portion of the groove-shaped guide portion 220 that extends substantially vertically and has an arc shape centered on the rotation center (rotation shaft portion 140) of the holding member 100 at the contact position or the separation position. It is. As shown in FIG. 5, the upper end portion of the first guide portion 221 has a closed shape, and the holding shaft 100 is brought into contact with the positioning shaft portion 150 rotated from the separated position to the contact position from substantially below. The positioning portion 223 is positioned at the contact position.

  The second guide portion 222 is a portion of the groove-shaped guide portion 220 that extends substantially horizontally from the lower end portion of the first guide portion 221 toward the front side. The upper and lower wall surfaces constituting the second guide portion 222 extend substantially parallel to each other from the lower end portion of the first guide portion 221 toward the front side, and then extend from the rear end to the front at the front end of the second guide portion 222. The gaps are formed to extend away from each other so that the gap gradually increases, and to extend substantially parallel again with the gap widened. And the front-end part of the 2nd guide part 222 is opened toward the front.

  The positioning shaft portion 150 engaged with the first guide portion 221 reaches the lower end portion (separated position) of the first guide portion 221 from the state positioned at the upper end portion of the first guide portion 221 (the state at the contact position). Up to the state immediately before the movement, the front-rear movement is restricted by the front and rear wall surfaces of the groove constituting the first guide portion 221. The positioning shaft portion 150 can move forward along the second guide portion 222 after reaching the separated position. In other words, the first guide portion 221 restricts the movement of the holding member 100 to the drawing position when the holding member 100 is between the contact position and the separation position, and the holding member 100 when the holding member 100 is in the separation position. It is comprised so that the movement to the extraction | drawer position may be permitted.

  As shown in FIG. 1, the compression coil spring 230 is a member that urges the front side portion of the holding member 100 from the separated position toward the contact position via the holding member support plate 240. As shown in FIG. 6, two are provided side by side on the left and right. The two compression coil springs 230 are arranged symmetrically with respect to the center in the left-right direction that is the rotation axis direction of the photosensitive drum 51 of the holding member 100 (see the straight line shown by the one-dot chain line in FIG. 6).

  In the present embodiment, the compression coil spring 230 employs a biasing force that can push up the holding member 100 in the separated position to the contact position by two total biasing forces. Further, as shown in FIG. 1, when the holding member 100 is in the contact position, the upward moment around the rotation center acting on the holding member 100 by the urging forces of the two compression coil springs 230 is four second urging forces. The downward moment about the rotation center acting on the holding member 100 is larger than the reaction force of the force that urges the developing roller 61 corresponding to the member 120 toward the photosensitive drum 51.

  The holding member support plate 240 is a plate-like member that supports the front portion of the holding member 100 from below, and is provided on the compression coil spring 230. A supported portion 102 protruding downward is formed on the front portion of the lower wall 101 of the holding member 100, and the holding member support plate 240 supports the supported portion 102 from below. A predetermined gap is formed by the supported portion 102 between the rear portion of the holding member support plate 240 and the lower wall 101 of the holding member 100, whereby a stopper 250 is described later on the rear portion of the holding member support plate 240. The locking part 251 can be engaged.

  The stopper 250 is a member that maintains the holding member 100 rotated from the contact position to the separation position at the separation position against the biasing force of the compression coil spring 230, and is provided above the front portion of the paper feed tray 31. . The stopper 250 includes a locking portion 251 that can be engaged with the rear portion of the holding member support plate 240, a pressed portion 252 that extends forward from below the locking portion 251, and the locking portion 251 and the pressed portion 252. Is formed in a generally bowl shape in side view. The locking portion 251 formed so as to protrude forward from the upper end portion of the connecting portion 253 is a flat inclined surface 251A whose front end surface faces obliquely upward.

  The stopper 250 is supported so as to be slidable in the front-rear direction with respect to the main body housing 2 and is urged forward by an urging member 260 such as a compression coil spring. Accordingly, the stopper 250 causes the pressed portion 252 to be directed rearward by the pressing portion 21A provided on the front cover 21 when the front cover 21 is displaced from the open position shown in FIG. 2 to the closed position shown in FIG. As a result, the urging member 260 slides backward while being compressed. Further, when the front cover 21 is displaced from the closed position shown in FIG. 1 to the open position shown in FIG. 2, the stopper 250 is released from the restriction by the pressing portion 21A, so that the urging member 260 has the original shape. It slides forward by the urging force when returning to.

<Effects of color printer>
Next, an operation for replacing the developing device 60 and an operation at that time will be described, and an operation effect of the color printer 1 according to the present embodiment will be described.
When the developing device 60 is replaced, first, the front cover 21 in the closed position shown in FIG. 1 is opened and displaced to the open position shown in FIG. As a result, the stopper 250 moves forward by the biasing force of the biasing member 260.

  Next, the handle 110 of the holding member 100 exposed from the opening 2A is gripped, and the front portion of the holding member 100 is pushed down against the biasing force of the compression coil spring 230, so that the holding member 100 is removed from the contact position as shown in FIG. It is made to rotate to the separation position shown in FIG. At this time, the positioning shaft portion 150 of the holding member 100 moves in the first guide portion 221 from the upper end portion toward the lower end portion, but the wall surface on the front side of the groove constituting the first guide portion 221 Since the forward movement of the positioning shaft portion 150 is restricted, it is possible to prevent the holding member 100 from being pulled forward when it is between the contact position and the separation position.

  Further, when the holding member 100 rotates from the contact position to the separation position, the holding member support plate 240 that supports the front portion of the holding member 100 is also pushed downward. The rear portion of the plate 240 abuts on the inclined surface 251A of the locking portion 251 of the stopper 250, and then contacts the inclined surface 251A. As a result, a force pushed backward acts on the inclined surface 251 </ b> A, so that the stopper 250 moves backward while compressing the biasing member 260. When the rear portion of the holding member support plate 240 passes through the inclined surface 251 </ b> A, the stopper 250 moves forward by the biasing force of the biasing member 260, whereby the locking portion 251 is moved to the upper surface of the rear portion of the holding member support plate 240. Engage with. As a result, the holding member support plate 240 is maintained at the position shown in FIG. 3 against the urging force of the compression coil spring 230, so that the holding member 100 is maintained at the contact position.

  After the holding member 100 is rotated from the contact position to the separated position, the holding member 100 is pulled out forward to move the holding member 100 from the inside of the main body housing 2 to the drawing position outside the main body housing 2 shown in FIG. Let Then, the old developing device 60 is removed from the holding member 100, the new developing device 60 is mounted on the holding member 100, and the developing device 60 is replaced. After the replacement of the developing device 60, the holding member 100 is pushed backward to move the holding member 100 from the pulled-out position outside the main body housing 2 to the separated position inside the main body housing 2 shown in FIG. In the color printer 1, the holding member 100 can be maintained at the separated position by the stopper 250, so that the holding member 100 is moved from the separated position to the drawn position or from the drawn position to the separated position as compared with the configuration without the stopper. The operability when moving can be improved.

  When the holding member 100 reaches the separated position from the pulled-out position, the rotating shaft portion 140 of the holding member 100 is supported on the lower wall portion 211 of the shaft support portion 210 and supported from below, and is attached to the rear wall portion 212. Abut. As a result, the front and rear and upper and lower positions of the rotation shaft portion 140 (the rear portion of the holding member 100) with respect to the main body housing 2 are determined.

  Thereafter, the front cover 21 in the open position is closed and displaced to the closed position shown in FIG. Then, the pressed portion 252 of the stopper 250 is pushed rearward by the pressing portion 21A, so that the stopper 250 moves rearward, and the engagement between the locking portion 251 and the upper surface of the rear portion of the holding member support plate 240 is released. The Accordingly, the front portion of the holding member 100 is lifted upward by the compression coil spring 230 via the holding member support plate 240, and the holding member 100 rotates from the separated position to the contact position.

  When the holding member 100 reaches the contact position from the separated position, the positioning shaft portion 150 abuts on the positioning portion 223 that is the upper end portion of the first guide portion 221, thereby positioning the positioning shaft portion 150 (holding member) at the contact position. The upper and lower positions of the front part of 100 are determined. In the color printer 1, the two compression coil springs 230 are arranged symmetrically with respect to the center in the left-right direction of the holding member 100, so that the holding member 100 is urged from the separated position to the contact position with a good balance in the left-right direction. And the positional accuracy of the holding member 100 can be improved.

  According to the color printer 1 described above, since the holding member 100 is supported so as to be rotatable about the rear side as a rotation center, the holding member 100 is compared with a configuration in which the entire holding member is translated up and down. The load for moving 100 can be reduced. Thereby, for example, in the configuration in which the holding member is moved from the contact position to the separated position by human power, when the entire holding member is translated up and down, a mechanism for supporting human power is necessary because the load is large, In the present embodiment, since a mechanism for supporting human power is not required, the configuration for moving the holding member can be simplified. Moreover, since the load for moving the holding member 100 is small, the holding member 100 can be easily moved, so that the operability can be improved.

  In the present embodiment, the holding member 100 can be automatically rotated from the separated position to the contact position by the biasing force of the compression coil spring 230 by displacing the front cover 21 from the open position to the closed position. Compared with a configuration in which the holding member is manually rotated from the separated position to the contact position, the operability can be further improved.

  Further, in the configuration in which the entire holding member is translated up and down, it is necessary to determine both the rear side and the front side of the holding member when the holding member is moved to the contact position. Since the position of a certain rotation shaft portion 140 is fixed, it is only necessary to determine the position of the positioning shaft portion 150 that is the front portion of the holding member 100. Therefore, the holding member 100 can be positioned relatively accurately with a simple configuration as compared with the configuration that determines both positions.

  Further, since the holding member 100 is provided with the second urging member 120 corresponding to each developing roller 61, the developing roller 61 is provided with, for example, the compression coil spring 230 without providing the second urging member 120. As compared with the configuration in which the developing roller 61 is biased toward the corresponding photosensitive drum 51, each developing roller 61 can be biased with high accuracy. Further, when the holding member 100 is in the contact position, an upward moment around the rotation center acting on the holding member 100 by the compression coil spring 230 is downward about the rotation center acting on the holding member 100 by the second biasing member 120. Therefore, in the configuration in which the second urging member 120 is provided, the development roller 61 can be prevented from moving away from the corresponding photosensitive drum 51.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. About a concrete structure, it can change suitably in the range which does not deviate from the meaning of this invention as follows.

  In the embodiment, the compression coil spring 230 is exemplified as the first urging member. However, the present invention is not limited to this, and for example, a tension coil spring 270 as shown in FIG. 7 may be used. Supplementally, a total of two tension coil springs 270 are provided on both the left and right sides of the front portion of the holding member 100 (only one is shown), and are arranged symmetrically with respect to the center of the holding member 100 in the left-right direction. Each tension coil spring 270 has an upper end fixed to a spring fixing portion (not shown) provided in the main body housing 2 and a lower end locked to a locked portion 241 provided on both the left and right sides of the holding member support plate 240. Has been.

  Here, the operation of the tension coil spring 270 accompanying the operation of the color printer 1 according to the modification will be briefly described. The front cover 21 is displaced to the open position shown in FIG. 8, and the holding member 100 is shown in FIG. 9 from the contact position. When rotated to the separated position, the tension coil spring 270 is extended by the downward movement of the holding member support plate 240, and the holding member support plate 240 is maintained at the position shown in FIG. , Maintained in a stretched state. Thereafter, the holding member 100 is moved from the separated position to the drawing position shown in FIG. 10, the developing device 60 is replaced, the holding member 100 is moved again from the drawn position to the separated position shown in FIG. 7 is displaced to the closed position shown in FIG. 7, the engagement between the stopper 250 and the holding member support plate 240 is released, so that the tension coil spring 270 returns to its original shape. Accordingly, the front portion of the holding member 100 is lifted upward via the holding member support plate 240, so that the holding member 100 rotates from the separated position to the contact position.

  In the said embodiment, although the structure provided with two 1st urging members, such as the compression coil spring 230, was illustrated, this invention is not limited to this, Even if there is only one 1st urging member. Three or more may be provided. When only one first urging member is provided, it is desirable that the first urging member is disposed at the center of the holding member in the rotation axis direction of the photosensitive drum. When three or more first urging members are provided, the first urging members are arranged symmetrically with respect to the rotation axis direction center of the photosensitive drum of the holding member in order to urge the holding member in a balanced manner. It is desirable to do.

  In the embodiment, the compression coil spring is exemplified as the second urging member 120. However, the second urging member is not limited to this as long as the member can perform the same function. For example, the second urging member is a compression such as a torsion spring. A member other than a coil spring, or an elastically deformable member such as sponge or rubber may be used. Moreover, in the said embodiment, although the holding member 100 had the 2nd biasing member 120, this invention is not limited to this, The structure which does not have a 2nd biasing member may be sufficient.

  The configuration of the stopper 250 shown in the above embodiment is an example, and the configuration of the stopper 250 is not limited to the configuration of the above embodiment as long as the same function can be achieved. Further, the present invention may be configured without a stopper.

  The configuration of the guide portion 220 shown in the embodiment is an example, and the guide portion for guiding the movement of the holding member is not limited to the configuration of the embodiment. For example, in the above-described embodiment, the guide portion 220 is formed in a groove shape. However, the guide portion 220 is not limited to this, and the guide portion is formed in a rail shape having a substantially U shape in cross-section that engages with a part of the holding member. May be. In the above embodiment, the guide portion 220 includes the second guide portion 222 extending from the lower end portion of the first guide portion 221 toward the front side. However, the present invention is not limited thereto. The structure which is not provided may be sufficient. In this case, a rail or the like for guiding movement of the holding member between the separation position and the drawing position may be provided in the apparatus main body.

  In the above embodiment, as shown in FIG. 4, the holding member 100 is such that the developing device 60 on the most upstream side in the pull-out direction can be replaced, so that the holding member 100 can be replaced with the main body housing 2 from within the main body housing 2. However, the present invention is not limited to this. For example, the holding member may be configured such that the entire holding member can be pulled out of the apparatus main body from the apparatus casing. Further, the holding member may be configured to be detachable from the apparatus main body from the drawing position. Moreover, in the said embodiment, although the holding member 100 was formed in the substantially box shape which upper part opened, this invention is not limited to this, For example, a holding member is formed in the substantially frame shape which opened up and down. It may be.

  The configuration of the positioning unit 223 shown in the embodiment is an example, and the positioning unit of the present invention is not limited to the configuration of the embodiment. For example, in the above-described embodiment, the positioning unit 223 is provided in the guide unit 220. However, the positioning unit 223 is not limited thereto, and the positioning unit may be provided independently of the guide unit. Specifically, the positioning portion provided independently of the guide portion can be configured as, for example, a boss or a surface with which the upper surface of the side wall of the holding member abuts.

  The configuration of the developing device 60 shown in the above embodiment is an example, and the developing device of the present invention is not limited to the configuration of the above embodiment. For example, the developing device may be configured to include two or more supply rollers in order to satisfactorily supply the developer from the bottom to the top, or a plurality of units for moving the developer upward stepwise. The structure provided with conveyance members, such as a room and several agitators, may be sufficient.

  In the above embodiment, the color printer 1 is exemplified as the image forming apparatus. However, the present invention is not limited to this, and may be, for example, a copying machine or a multi-function machine including a document reading device such as a flat bed scanner.

DESCRIPTION OF SYMBOLS 1 Color printer 2 Main body housing | casing 51 Photosensitive drum 60 Developer 61 Developing roller 100 Holding member 120 2nd biasing member 140 Rotating shaft part 150 Positioning shaft part 221 1st guide part 222 2nd guide part 223 Positioning part 230 Compression Coil spring 250 stopper

Claims (6)

The device body;
A plurality of photosensitive drums arranged in a direction intersecting the vertical direction in the apparatus body;
A plurality of developing units provided corresponding to the respective photosensitive drums and having developing rollers for supplying a developer to the corresponding photosensitive drums;
An image forming apparatus comprising: a holding member that detachably holds each of the developing devices, and a holding member that can be pulled out of the apparatus main body from the apparatus main body to the outside of the apparatus main body;
The holding member has a contact position where the developing roller contacts the corresponding photosensitive drum with respect to the apparatus main body with the upstream side in the drawing direction as a rotation center within the apparatus main body, and an end portion on the downstream side in the drawing direction. Positioned below the contact position, the development roller is supported so as to be rotatable between a separation position separated from the corresponding photosensitive drum, and the separation position with respect to the apparatus body, and the apparatus body It is supported so that it can move between the drawer position pulled out,
further,
A first urging member that urges a portion of the holding member on the downstream side in the pulling direction from the separated position toward the contact position;
A positioning portion that is provided in the apparatus main body and that positions the holding member at the contact position by contacting a part of the holding member rotated from the separated position to the contact position. An image forming apparatus. The holding member includes a plurality of second urging members that are provided corresponding to the respective developing devices and urge the developing roller toward the corresponding photosensitive drum when at least in the contact position.
When the holding member is in the contact position, an upward moment around the rotation center acting on the holding member by the first urging member acts on the holding member by the plurality of second urging members. The image forming apparatus according to claim 1, wherein the image forming apparatus is larger than a downward moment around the rotation center.   3. The image forming apparatus according to claim 1, further comprising a stopper provided in the apparatus main body and configured to maintain the holding member rotated from the contact position to the separated position at the separated position. apparatus. A first guide portion provided in the apparatus body for guiding rotation between the contact position and the separation position of the holding member;
The first guide portion extends in an arc shape centered on the rotation center and engages with a part of the holding member, and when the holding member is between the contact position and the separation position 2. The structure according to claim 1, wherein movement of the holding member to a drawing position is restricted, and movement of the holding member to a drawing position is allowed when the holding member is in the separated position. The image forming apparatus according to claim 3. A second guide portion provided in the apparatus main body for guiding movement of the holding member between the separation position and the extraction position;
The image forming apparatus according to claim 4, wherein the second guide portion extends from the lower end portion of the first guide portion toward the downstream side in the pull-out direction.   The plurality of first urging members are provided, and are arranged symmetrically with respect to the center of the holding member in the rotation axis direction of the photosensitive drum. The image forming apparatus described in the item.

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