JP3167012U - Drum cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drum cartridge capable of stably pressing an entire developing cartridge as compared with a structure in which a pressing member locally presses a part of the developing cartridge. SOLUTION: A drum cartridge 50 rotatably supports a photosensitive drum 32, and has a housing 51 having a housing portion 54 in which a developing cartridge 33 is detachably housed, and a photosensitive drum in the housing portion 54 of the housing 51. It is provided on the opposite side of the 32 and includes a pressing member 52 that presses the developing cartridge 33 toward the photosensitive drum 32. Then, the pressing member 52 extends along the axial direction of the photosensitive drum 32 over the entire width of the photosensitive drum 32. [Selection diagram] Fig. 2

Description

  The present invention relates to a drum cartridge to which a developing cartridge is attached.

  Generally, in an image forming apparatus such as a laser printer, an electrostatic latent image is formed on the surface of a photosensitive drum by exposing the surface of the photosensitive drum charged by a charger with a laser or the like, and the electrostatic latent image is developed. Toner is supplied from the roller to form a toner image on the surface of the photosensitive drum. The toner image is attracted by a transfer roller that sandwiches the paper with the photosensitive drum, whereby the toner image is transferred to the paper to form an image.

As such an image forming apparatus, there is conventionally known an apparatus including a developing cartridge having a developing roller and a drum cartridge having a photosensitive drum and to which the developing cartridge can be attached (see Patent Document 1). In this technique, the developing roller is excellent with respect to the photosensitive drum by providing a pressed member on both sides in the axial direction of the developing roller of the developing cartridge and by providing a pressing member that presses the pressed member on the drum cartridge or the like. Is pressed.
JP 2000-250378 A

  By the way, various improvements are desired for such a drum cartridge.

  Accordingly, an object of the present invention is to provide an improved device for a drum cartridge.

The present invention that solves the above-described problems provides a housing having a housing portion that rotatably supports a photosensitive drum and in which a developing cartridge is detachably accommodated, and a side opposite to the photosensitive drum in the housing portion of the housing. And a pressing member that presses the developing cartridge toward the photosensitive drum, wherein the pressing member is provided movably in a direction that moves forward and backward with respect to the photosensitive drum. The photosensitive drum is characterized in that it extends over the entire width of the photosensitive drum along the axial direction of the photosensitive drum.

  According to the present invention, since the pressing member extends over the entire width of the photosensitive drum, the entire developing cartridge is more stable than the conventional structure in which the pressing member locally presses a part of the developing cartridge. Can be pressed.

  According to the present invention, since the pressing member extends over the entire width of the photosensitive drum, the entire developing cartridge can be stably pressed.

1 is a cross-sectional view showing a laser printer according to a first embodiment of the present invention. It is a perspective view which shows the detailed structure of a drum cartridge. FIG. 4 is a side view (a) showing a state where the developing cartridge is mounted on the drum cartridge, and a side view (b) showing a state where a developing cartridge smaller than the developing cartridge shown in FIG. 3A is mounted on the drum cartridge. FIG. 5A is a side view showing a drum cartridge according to a second embodiment, and FIG. 5B is a side view showing a state of the drum cartridge when a developing cartridge smaller than the developing cartridge of FIG.

[First Embodiment]
Next, a first embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the drawings to be referred to, FIG. 1 is a sectional view showing a laser printer according to a first embodiment of the present invention.

  In the following description, first, the overall configuration of the laser printer will be described briefly, and then the details of the features of the present invention will be described. Further, in the following description, the description will be made in the direction based on the user when the laser printer 1 is used. That is, in FIG. 1, the right side is referred to as “front side”, the left side is referred to as “back side”, the back side in the vertical direction of the paper surface is referred to as “right side”, and the front side in the vertical direction of the paper surface is referred to as “left side”. Called. As for the vertical direction, the vertical direction in the figure is referred to as the “vertical direction” as it is.

<Overall configuration of laser printer>
As shown in FIG. 1, the laser printer 1 includes a feeder unit 4 for feeding a sheet 3 into a main body casing 2, an image forming unit 5 for forming an image on the sheet 3, and the like.

<Configuration of feeder section>
The feeder unit 4 has a known structure, and mainly includes a paper feed tray 12, a paper pressing plate 13, and a paper transport mechanism 14. In the feeder unit 4, the sheet 3 in the sheet feeding tray 12 is moved upward by the sheet pressing plate 13 and conveyed to the image forming unit 5 by the sheet conveying mechanism 14.

<Configuration of image forming unit>
The image forming unit 5 includes a scanner unit 20, a process cartridge 30, a fixing unit 40, and the like.

  The scanner unit 20 includes a laser light emitting unit (not shown), a polygon mirror 21, lenses 22, 23, reflecting mirrors 24, 25, 26, and the like. In the scanner unit 20, the laser beam is irradiated on the surface of the photosensitive drum 32 by high-speed scanning through a path indicated by a chain line in the drawing.

  The process cartridge 30 can be attached to and detached from the main casing 2 by appropriately opening the front cover 11 on the front side of the main casing 2. The process cartridge 30 is mainly composed of a drum cartridge 50 and a developing cartridge 33.

  The drum cartridge 50 mainly includes a photosensitive drum 32, a scorotron charger 34 and a transfer roller 35. In the drum cartridge 50, the surface of the photosensitive drum 32 is uniformly positively charged by the scorotron charger 34 and then exposed by high-speed scanning of the laser beam from the scanner unit 20. Thereby, the potential of the exposed part is lowered, and an electrostatic latent image based on the image data is formed. The details of the drum cartridge 50 will be described later.

  The developing cartridge 33 is detachably attached to the main casing 2 via the drum cartridge 50 or is detachably attached to the drum cartridge 50 fixed to the main casing 2. The developing cartridge 33 mainly includes a developing roller 36, a layer thickness regulating blade 37, a supply roller 38, and a toner hopper 39 as an example of a toner storage unit. The wall 33A located on the opposite side of the developing roller 36 with respect to the toner hopper 39 is pressed by a pressing member 52 described in detail later.

  In the developing cartridge 33, the toner in the toner hopper 39 is stirred by the agitator 39A and then supplied to the developing roller 36 by the supply roller 38. At this time, the toner is positively frictionally charged between the supply roller 38 and the developing roller 36. Is done. The toner supplied onto the developing roller 36 enters between the layer thickness regulating blade 37 and the developing roller 36 as the developing roller 36 rotates, and is further developed as a thin layer having a constant thickness while being frictionally charged. It is carried on a roller 36.

  Next, the toner carried on the developing roller 36 is supplied to the electrostatic latent image formed on the surface of the photosensitive drum 32 by the rotation of the developing roller 36, and the toner image is formed on the surface of the photosensitive drum 32. It is formed. Thereafter, the sheet 3 is conveyed between the photosensitive drum 32 and the transfer roller 35, whereby the toner image carried on the surface of the photosensitive drum 32 is transferred onto the sheet 3.

  The fixing unit 40 has a known structure and includes a heating roller 41 and a pressing roller 42. In the fixing unit 40, the toner transferred onto the paper 3 is thermally fixed while the paper 3 passes between the heating roller 41 and the pressing roller 42. The paper 3 thermally fixed by the fixing unit 40 is sent out onto a paper discharge tray 46 by a paper discharge roller 45.

<Detailed structure of drum cartridge>
Next, the detailed structure of the drum cartridge 50 which is a characteristic part of the present invention will be described. In the drawings to be referred to, FIG. 2 is a perspective view showing a detailed structure of the drum cartridge.

  As shown in FIG. 2, the drum cartridge 50 is provided on a housing 51 that rotatably supports the photosensitive drum 32 and the like, a pressing member 52 provided on the front side in the housing 51, and the left and right sides of the housing 51. A restricting member 53 is provided.

  The casing 51 mainly includes a left side wall 51A and a right side wall 51B arranged on the left and right sides, a bottom wall 51C arranged below, and a rear wall 51D arranged on the front side. The photosensitive drum 32 is supported by a portion on the back side of the wall 51B. In front of the photosensitive drum 32, an accommodating portion 54 for detachably accommodating the developing cartridge 33 is formed by the walls 51A to 51D described above.

  Further, on the left side wall 51A and the right side wall 51B, the rotation shaft 36A of the developing roller 36 protruding from the outer surface of the developing cartridge 33 is provided, and the photosensitive drum 32 protruding from the outer surface (left side wall 51A and right side wall 51B) of the drum cartridge 50 is provided. A guide groove 51E for guiding toward the rotation shaft 32A is formed. Furthermore, slide grooves 51F extending in the front-rear direction are formed in the left side wall 51A and the right side wall 51B.

  The pressing member 52 is provided on the opposite side of the housing portion 54 of the housing 51 from the photosensitive drum 32 and presses the developing cartridge 33 housed in the housing portion 54 toward the photosensitive drum 32 side. The pressing member 52 includes a contact member 52A and a coil spring 52B as an example of an urging member.

  The contact member 52 </ b> A is a rectangular member that extends along the axial direction of the photosensitive drum 32, and extends across the entire width of the photosensitive drum 32. Here, the “width of the photosensitive drum 32” refers to the length in the axial direction of the large-diameter portion of the photosensitive drum 32 (the portion in sliding contact with the developing roller 36). The left and right side surfaces of the contact member 52A are formed with slide pieces 52C that protrude outward in the left-right direction and engage slidably with the slide grooves 51F of the housing 51. Thereby, the contact member 52 </ b> A is movable in the front-rear direction with respect to the housing 51.

  The coil spring 52 </ b> B is provided between the contact member 52 </ b> A and the rear wall 51 </ b> D of the housing 51, and is compressed when the developing cartridge 33 is housed in the housing portion 54 of the housing 51. 33 is pressed toward the photosensitive drum 32 side. Note that any number of coil springs 52B may be provided as long as they are arranged with a good balance in the left-right direction with respect to the contact member 52A.

  The restricting member 53 restricts the movement of the developing roller 36 to the inner side (the photosensitive drum 32 side) of the rotation shaft 36A in order to keep the distance between the photosensitive drum 32 and the developing roller 36 in the developing cartridge 33 constant. It is a member to do. The regulating member 53 is formed in a plate shape, and a U-shaped engagement groove 53A is formed at one end thereof, and a cylindrical surface 53B is formed at the other end.

  The engagement groove 53 </ b> A has an inner peripheral surface formed so as to coincide with the outer peripheral surface of the rotation shaft 32 </ b> A of the photosensitive drum 32, and thus engages with the rotation shaft 32 </ b> A of the photosensitive drum 32 in a rotatable manner. The cylindrical surface 53B is formed in a cylindrical surface shape that is equidistant from the center of the rotating shaft 32A of the photosensitive drum 32 when the engaging groove 53A engages with the rotating shaft 32A of the photosensitive drum 32.

  The restricting member 53 configured as described above has the engaging groove 53A engaged with the rotating shaft 32A of the photosensitive drum 32, and the cylindrical surface 53B is disposed so as to overlap the guide groove 51E of the housing 51 in a side view. Later, it is fixed to the casing 51 with an adhesive, screws or the like. After fixing in this way, when the developing cartridge 33 is mounted in the housing portion 54 of the housing 51, the regulating member 53 contacts between the rotating shaft 32 </ b> A of the photosensitive drum 32 and the rotating shaft 36 </ b> A of the developing roller 36. Thus, the distance between the axes of the photosensitive drum 32 and the developing roller 36 is kept constant.

  Next, the operation of the drum cartridge 50 according to this embodiment will be described. In the drawings to be referred to, FIG. 3A is a side view showing a state in which the developing cartridge is mounted on the drum cartridge, and FIG. 3B is a side view showing a state in which a developing cartridge smaller than the developing cartridge in FIG. (B).

  As shown in FIG. 3A, when the developing cartridge 33 is attached to the drum cartridge 50, the coil spring 52B is contracted by a predetermined amount, and the developing cartridge 33 is moved by the contact member 52A extending over the entire width of the photosensitive drum 32. It is pressed toward the photosensitive drum 32 in a stable state. At this time, the rotation shaft 36A of the developing roller 36 of the developing cartridge 33 is regulated by the regulating member 53, so that the distance between the rotation shaft 32A of the photosensitive drum 32 and the rotation shaft 36A of the developing roller 36 is kept constant. It is.

  Next, the operation of the drum cartridge 50 when the developing cartridge 330 formed smaller in the front-rear direction than the normal size developing cartridge 33 shown in FIG.

  As shown in FIG. 3B, when the developing cartridge 330 smaller in the front-rear direction than the normal size is mounted on the drum cartridge 50, the coil spring 52B extends more than when the normal size developing cartridge 33 is mounted. By being in the state, the contact member 52A is in good contact with the developing cartridge 330. Therefore, even when the developing cartridge 330 smaller than the normal size is mounted, the developing cartridge 33 is pressed toward the photosensitive drum 32 in a stable state by the contact member 52A. Further, at this time, the rotation shaft 36A of the developing roller 36 of the developing cartridge 330 is regulated by the regulating member 53 in the same manner as when the normal size developing cartridge 33 is mounted, so that the rotation shaft 32A of the photosensitive drum 32 and the developing shaft are developed. The inter-axis distance between the roller 36 and the rotation shaft 36A is kept constant.

  Here, since the amount of contraction of the coil spring 52B is different between the form shown in FIG. 3A and the form shown in FIG. 3B, the urging force applied to the developing cartridges 33 and 330 from the coil spring 52B is different. . However, since the distance between the rotation shaft 32 </ b> A of the photosensitive drum 32 and the rotation shaft 36 </ b> A of the developing roller 36 is kept constant by the regulating member 53, the force pressing the developing roller 36 against the photosensitive drum 32 becomes constant. The nip width between the photosensitive drum 32 and the developing roller 36 is constant. Here, the nip width is the length along the curved surface of the concave portion generated on the surface of the developing roller 36 by pressing the developing roller 36 against the photosensitive drum 32 (or the concave portion of the developing roller 36 in the photosensitive drum 32). The circumferential length of the part in contact with

  According to the above, the following effects can be obtained in the present embodiment.

  Since the contact member 52A extends over the entire width of the photosensitive drum 32, the entire developing cartridge can be stably pressed as compared with the conventional structure in which the pressing member locally presses a part of the developing cartridge. . More specifically, when the pressing member locally presses a part of the developing cartridge, the developing roller or the like bends in the width direction (axial direction), so that the nip between the developing roller and the photosensitive drum is formed. Although it may become unstable in the axial direction, the nip between the developing roller and the photosensitive drum is stabilized by pressing the entire width of the developing cartridge.

  Since the regulating member 53 that keeps the distance between the rotating shaft 32A of the photosensitive drum 32 and the rotating shaft 36A of the developing roller 36 constant is provided, even when the developing cartridges 33 and 330 having different sizes are mounted, The nip width between the photosensitive drum 32 and the developing roller 36 can be made constant.

[Second Embodiment]
Next, a second embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In addition, since this embodiment changes a part of structure of above-mentioned 1st Embodiment, about the component similar to 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted. To do. 4 is a side view showing a drum cartridge according to the second embodiment, and FIG. 4 shows a state of the drum cartridge when a developing cartridge smaller than the developing cartridge of FIG. 4A is mounted. It is a side view (b).

  As shown in FIG. 4A, in the drum cartridge 60 according to the second embodiment, instead of removing the regulating member 53 provided in the first embodiment, the drum cartridge 60 according to the position in the front-rear direction of the contact member 52A. The angle of the coil spring 52B (the angle with respect to the upper surface 51G of the casing 51) changes. Specifically, one end of the coil spring 52B is rotatably provided at the rear portion of the contact member 52A, and the other end is rotatably provided at the rear wall 51D of the housing 51. The other end of the coil spring 52B is arranged at a position higher than one end of the coil spring 52B when viewed from the front-rear direction (the moving direction of the contact member 52A).

  Here, the structure for rotatably supporting the end portions of the coil spring 52B is arbitrary. For example, as shown in FIG. 4A, the contact member 52A and the rear wall 51D of the casing 51 are respectively supported. A pedestal 70 that can rotate is provided, and both ends of the coil spring 52 </ b> B may be fixed to each pedestal 70.

  According to the above configuration, as shown in FIG. 4A, when the normal size developing cartridge 33 is mounted on the drum cartridge 60, the contact member 52A is separated from the rear wall 51D of the housing 51 by the distance X. The coil spring 52B contracts by a predetermined amount and tilts by a predetermined angle α. As a result, an urging force F1 corresponding to the amount of contraction of the coil spring 52B is applied to the contact member 52A at an angle α, and the contact member 52A is a force FX1 (F1 · cos α) as a longitudinal component of the urging force F1 in the front-rear direction. Pressed.

  As shown in FIG. 4B, when the developing cartridge 330 smaller than the normal size is mounted on the drum cartridge 60, the contact member 52A moves from the rear wall 51D of the housing 51 to the position of the distance Y. As a result, the coil spring 52B contracts by a smaller amount than in the case of FIG. 4A and tilts at an angle β smaller than the angle α. As a result, a small biasing force F2 corresponding to the small amount of contraction of the coil spring 52B is applied to the contact member 52A at an angle β, and the contact member 52A has a force FX2 (F2 · cos β) of the front-rear direction component of the biasing force F2 in the front-rear direction. ).

  Therefore, according to this embodiment, the force FX1 of the front-rear direction component when the developing cartridge 33 of the normal size is mounted and the force FX2 of the front-rear direction component when the developing cartridge 330 smaller than the normal size is mounted are The nip width between the photosensitive drum 32 and the developing roller 36 can be made constant by appropriately setting the contraction amount and angle of the coil spring 52B so as to be the same.

  In addition, this invention is not limited to the said embodiment, It can utilize with various forms so that it may illustrate below.

  In each said embodiment, although the press member was comprised with 2 components, a contact member and a biasing member, this invention is not limited to this, You may comprise with 1 components, such as a leaf | plate spring.

  In the first embodiment, the regulating member 53 that contacts the rotating shaft 32A of the photosensitive drum 32 and the rotating shaft 36A of the developing roller 36 is used. However, the present invention is not limited to this. For example, a member that does not contact the rotating shaft of the photosensitive drum may be disposed at a position that is a predetermined distance away from the rotating shaft center of the photosensitive drum and that overlaps the guide groove. Even in this case, the distance between the rotation shaft of the photosensitive drum and the rotation shaft of the developing roller can be maintained at the predetermined distance.

  In the second embodiment, the other end of the coil spring 52B is shifted upward from one end when viewed from the front-rear direction, but the present invention is not limited to this, and the other end of the coil spring from the one end is viewed from the front-rear direction. May be shifted downward or left and right.

32 Photosensitive drum 32A Rotating shaft 33 Developing cartridge 36 Developing roller 36A Rotating shaft 50 Drum cartridge 51 Housing 51A Left side wall 51B Right side wall 51C Bottom wall 51D Rear wall 51E Guide groove 51F Slide groove 52 Press member 52A Contact member 52C Slide piece 53 Restriction Member 54 receiving part

Claims (4)

A housing that rotatably supports the photosensitive drum and has a housing portion in which the developer cartridge is removably housed;
A drum cartridge provided on the opposite side of the housing portion of the housing from the photosensitive drum, and a pressing member that presses the developing cartridge toward the photosensitive drum;
The pressing member is provided so as to be movable in a direction to advance and retreat with respect to the photosensitive drum, and extends across the entire width of the photosensitive drum along the axial direction of the photosensitive drum. cartridge. The developing cartridge includes a wall portion pressed by the pressing member, a toner storage portion that stores toner, and a developing roller that is positioned on the opposite side of the wall portion with respect to the toner storage portion. Yes,
The casing is provided with a regulating member that regulates movement of the rotating shaft of the developing roller toward the photosensitive drum in order to keep a constant distance between the photosensitive drum and the developing roller. The drum cartridge according to claim 1.   3. The control member according to claim 2, wherein the regulating member is provided between the shaft of the photosensitive drum and the shaft of the developing roller so as to contact the shaft of the photosensitive drum and the shaft of the developing roller. The drum cartridge as described. The pressing member includes a contact member that contacts the developing cartridge, and an urging member provided between the contact member and the housing.
The urging member has one end rotatably provided on the contact member and the other end rotatably provided on the housing, and is provided at a position different from the one end when viewed from the moving direction of the contact member. The drum cartridge according to claim 1, wherein an angle with respect to the housing is variable according to a position of the contact member when viewed from an axial direction of the photosensitive drum.

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