JP2020134919A - Image forming unit and image forming apparatus - Google Patents

Abstract

To provide an image forming unit capable of securing image forming performance excellent in protecting an image carrier in spite of being compact.SOLUTION: An image forming unit includes an image carrier 11, a main body 21, a shutter unit 60, a first guide part, and a holding part. The image carrier includes an image carrying surface 11S capable of carrying a developer image. The main body holds the image carrier, so as to expose a part of the image carrying surface. The shutter unit includes a first shutter member 61 and a second shutter member 62. The first shutter member is held to be rotatable around a rotation shaft 611J and includes a first inner surface. The second shutter member is held to be rotatable around a second rotation shaft 612J and includes a second inner surface. The shutter unit can be state-shifted between a closing state where the first inner surface and the second inner surface cover the image carrying surface and an opening state where the first inner surface and the second inner surface are folded and the image carrying surface is exposed.SELECTED DRAWING: Figure 2A

Description

The present invention relates to an image forming apparatus that forms an image using an electrophotographic method, and an image forming unit mounted on the image forming apparatus.

The applicant is an electrophotographic method in which a developer is attached to an electrostatic latent image formed by exposing a photosensitive drum to obtain a developer image, and then the developer image is transferred to a printing medium. An image forming apparatus has already been proposed (see, for example, Patent Document 1).

JP-A-2018-124362

By the way, in such an image forming apparatus, when the image forming unit including the image carrier (photosensitive drum) is attached to or removed from the main body of the image forming apparatus, the user's hand is attached to the image carrier. There is a risk of touching it. In that case, the life of the image carrier may be shortened or the printed image may be deteriorated.

Therefore, it is desired to provide an image forming apparatus capable of ensuring excellent image forming performance by protecting the image carrier while being compact, and an image forming unit mounted on the image forming apparatus.

An image forming unit according to an embodiment of the present invention includes an image carrier, a main body, a shutter unit, a first guide portion, and a holding portion. The image-bearing body includes an image-supporting surface capable of supporting a developer image. The body holds the image carrier so that part of the image carrier is exposed. The shutter unit has a first shutter member and a second shutter member. The first shutter member is rotatably held about the first rotation axis with respect to the main body and includes a first inner surface. The second shutter member is rotatably held around a second rotation axis that is substantially parallel to the first rotation axis with respect to the first shutter member, and is held on the second inner surface, the first. Includes abutment and a second abutment. Further, the shutter unit has a closed state in which the first shutter member and the second shutter member are deployed so that the first inner surface and the second inner surface cover the image-carrying surface, and the first inner surface and the second inner surface. It is possible to shift to an open state in which the first shutter member and the second shutter member are folded so that the inner surfaces face each other and the image-carrying surface is exposed. The first guide portion is supported by the main body in a peripheral region other than the effective image forming region facing the image-carrying surface, and the image is in contact with the first abutting portion when the state shifts between the closed state and the open state. The movement of the second shutter member in the direction away from the supporting surface is restricted. The holding portion is supported by the main body in the peripheral region and abuts on the second contact portion to hold the shutter unit in the open state.

The image forming apparatus as one embodiment of the present invention includes the image forming unit as one embodiment of the present invention.

In the image forming unit and the image forming apparatus as one embodiment of the present invention, by having the above-described configuration, the shutter unit has an image-carrying surface regardless of the arrangement position of the image-bearing body with respect to the main body and the posture of the image-bearing unit. The state can be smoothly transitioned from the closed state that covers the image to the open state that exposes the image-carrying surface. In addition, the space swept by the shutter unit during the state transition can be made smaller.

According to the image forming unit and the image forming apparatus as one embodiment of the present invention, excellent image forming performance can be ensured by protecting the image-carrying surface while being small in size. The effect of the present invention is not limited to this, and any of the effects described below may be used.

It is a schematic diagram which shows the whole structure example of the image forming apparatus which concerns on 1st Embodiment of this invention. It is a 1st cross-sectional schematic diagram which shows the example of composition of the main part of the image forming unit mounted on the image forming apparatus shown in FIG. It is a 2nd cross-sectional schematic diagram which shows the example of composition of the main part of the image forming unit mounted on the image forming apparatus shown in FIG. It is a perspective view which shows the appearance of the image forming unit mounted on the image forming apparatus shown in FIG. It is a first perspective view which shows the appearance of the shutter unit shown in FIG. It is a second perspective view which shows the appearance of the shutter unit shown in FIG. It is a first cross-sectional view which shows the shutter unit in a closed state and the vicinity thereof among the image forming units shown in FIG. It is a first cross-sectional view which shows the shutter unit in an open state and the vicinity thereof among the image forming units shown in FIG. It is a first cross-sectional view which shows the shutter unit in an intermediate state, and the vicinity thereof among the image forming units shown in FIG. It is a second cross-sectional view which shows the shutter unit in an open state and the vicinity thereof among the image forming units shown in FIG. It is a second cross-sectional view which shows the shutter unit in an intermediate state and the vicinity thereof among the image forming units shown in FIG. It is sectional drawing which shows the state transition operation of the shutter unit shown in FIG. It is sectional drawing which shows the state transition operation of the shutter unit following FIG. 7A. It is sectional drawing which shows the state transition operation of the shutter unit following FIG. 7B. It is a 1st perspective view which shows the appearance of the image forming unit which concerns on 2nd Embodiment of this invention. It is a 2nd perspective view which shows the appearance of the image formation unit which concerns on 2nd Embodiment of this invention. It is a 1st perspective view which shows the appearance of the shutter unit shown in FIG. 8A. It is a second perspective view which shows the appearance of the shutter unit shown in FIG. 8A. It is a side view of the image forming unit shown in FIG. 8A. It is a side view of the image forming unit shown in FIG. 8B. FIG. 8 is a partially enlarged perspective view showing an enlarged view of the vicinity of the lever of the image forming unit shown in FIG. 8A. FIG. 5 is a cross-sectional view showing a state of the image forming unit at the first position when the shutter unit shown in FIG. 8A shifts from the closed state to the open state. FIG. 5 is a cross-sectional view showing a state of the image forming unit at a second position when the shutter unit shown in FIG. 8A shifts from a closed state to an open state. It is sectional drawing which shows the state of the image formation unit at the 1st position in the stage following FIG. 12A. It is sectional drawing which shows the state of the image formation unit at a 2nd position in the stage following FIG. 12B. FIG. 3 is a cross-sectional view showing the state of the image forming unit at the first position in the stage following FIG. 13A. FIG. 3 is a cross-sectional view showing the state of the image forming unit at the second position in the stage following FIG. 13B. It is sectional drawing which shows the state transition operation of the shutter unit shown in FIG. 8A. It is sectional drawing which shows the state transition operation of the shutter unit following FIG. 15A. It is sectional drawing which shows the state transition operation of the shutter unit following FIG. 15B. It is sectional drawing which shows the state transition operation of the shutter unit following FIG. 15C.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description is a specific example of the present invention, and the present invention is not limited to the following aspects. Further, the present invention is not limited to the arrangement, dimensions, dimensional ratio, etc. of each component shown in each figure. The explanation will be given in the following order.
1. 1. First Embodiment 2. Second embodiment 3. Modification example

<1. First Embodiment>
[1.1 Configuration of image forming apparatus]
FIG. 1 is a schematic view showing an overall configuration example of an image forming apparatus according to a first embodiment of the present invention. This image forming apparatus corresponds to a specific example of the "image forming apparatus" of the present invention, and forms an image (for example, a color image) with respect to a medium (also referred to as a printing medium or a transfer material) PM such as paper. , An electrophotographic printer.

The image forming apparatus of FIG. 1 has a paper feed tray 1 for accommodating a medium PM, a medium conveying section 2, an image forming section 3, a transfer section 4, a fixing section 5, and a discharging section inside the housing 10. A control unit 7, a control unit 7, and a drive unit 8 including a motor are provided. In the present embodiment, the transport direction in which the medium PM is transported in the transfer unit 4 is the Y-axis direction, the width direction of the medium PM orthogonal to the transport direction is the X-axis direction, and the X-axis direction and the Y-axis. The direction orthogonal to both directions is the Z-axis direction.

(Paper tray 1)
The paper feed tray 1 is a member that stores the media PM in a stacked state, and is detachably attached to, for example, the lower part of the image forming apparatus.

(Media transfer unit 2)
The medium transport unit 2 has a paper feed roller 2A and a pair of resist rollers 2B. The medium transport unit 2 takes out the media PM one by one from the paper feed tray 1, and transports the medium PM between the image forming unit 3 and the transfer unit 4 by using the paper feed roller 2A and the pair of resist rollers 2B. It is designed to be transported on the road.

(Image forming unit 3)
The image forming unit 3 is a mechanism for forming a toner image to be transferred to the medium PM fed out on the transport path. The image forming unit 3 includes an image forming unit 30 (30C, 30M, 30Y, 30K), an exposure device 40 (40C, 40M, 40Y, 40K), a toner cartridge 50 (50C, 50M, 50Y, 50K), and a toner. It has a supply transport path 51 (51C, 51M, 51Y, 51K).

The exposure apparatus 40 (40C, 40M, 40Y, 40K) exposes the surface of the photosensitive drum 11 (11K, 11C, 11M, 11Y) described later from the outside of the image forming unit 30 (30C, 30M, 30Y, 30K). This is a device for forming an electrostatic latent image on the surface of the photosensitive drum 11 (11K, 11C, 11M, 11Y). The exposure apparatus 40 (40C, 40M, 40Y, 40K) has a plurality of light emitting units arranged in a width direction orthogonal to the transport direction of the medium PM with respect to one corresponding photosensitive drum 11 (11K, 11C, 11M, 11Y). Have. Each light emitting unit includes, for example, a light source such as an LED (Light Emitting Diode) that emits irradiation light, and a lens array that forms an image of the irradiation light on the surface of a photosensitive drum 11 (11K, 11C, 11M, 11Y). It is configured.

The toner cartridge 50 (50C, 50M, 50Y, 50K) is a container for storing the toner T (TK, TC, TM, TY) for supplying to the image forming unit 30 (30C, 30M, 30Y, 30K). The toner cartridge 50C contains a cyan toner TC, the toner cartridge 50M contains a magenta toner TM, the toner cartridge 50Y contains a yellow toner TY, and the toner cartridge 50K contains a black toner TK. The toner supply transport path 51 (51C, 51M, 51Y, 51K) is provided so as to connect the toner cartridge 50 (50C, 50M, 50Y, 50K) and the image forming unit 30 (30C, 30M, 30Y, 30K). There is. Therefore, the toners of each color stored in the toner cartridges 50 (50C, 50M, 50Y, 50K) are transferred to the image forming unit 30 (30C) via the corresponding toner supply transport paths 51 (51C, 51M, 51Y, 51K). , 30M, 30Y, 30K), respectively.

Here, the image forming unit 30 (30C, 30M, 30Y, 30K) corresponds to a specific example of the "image forming unit" of the present invention, and the toner T (TK, TC, TM, TY) corresponds to the "development" of the present invention. Corresponds to a specific example of "agent". The detailed configuration of the image forming unit 30 (30C, 30M, 30Y, 30K) will be described later.

(Transfer unit 4)
The transfer unit 4 is also called a transfer belt unit. The transfer unit 4 sandwiches the transfer belt 41, the drive roller 42 for driving the transfer belt 41, the idle roller 43 driven by the drive roller 42, and the transfer belt 41, and the photosensitive drum 11 (11K, 11C, 11M, It has a transfer roller 44 (44C, 44M, 44Y, 44K) arranged to face the 11Y). The drive roller 42 and the idle roller 43 are substantially columnar members that can rotate about a rotation shaft portion extending in the width direction (X-axis direction), respectively. The transfer unit 4 conveys the medium PM conveyed from the paper feed tray 1 through the medium transfer unit 2 toward the downstream fixing unit 5, and in the image forming unit 30 (30C, 30M, 30Y, 30K), respectively. This is a mechanism for sequentially transferring the formed toner image to the surface of the medium PM.

The transfer belt 41 is an endless elastic belt made of a resin material such as a polyimide resin. The transfer belt 41 is stretched (stretched) by the drive roller 42 and the idle roller 43. The drive roller 42 is rotationally driven in the direction in which the medium PM is conveyed in the transfer direction by the rotational force transmitted from the drive unit 8 based on the control of the control unit 7, and circulates and rotates the transfer belt 41. The drive roller 42 is arranged on the upstream side of the image forming unit 30 (30C, 30M, 30Y, 30K). The idle roller 43 adjusts the tension applied to the transfer belt 41 by the urging force of the urging member. The idle roller 43 rotates in the same direction as the drive roller 42, and is arranged on the downstream side of the image forming unit 30 (30C, 30M, 30Y, 30K).

The transfer roller 44 (44C, 44M, 44Y, 44K) rotates in the opposite direction to the photosensitive drum 11 (11K, 11C, 11M, 11Y) to convey the medium PM along the conveying direction, and the image forming unit 30. It is a member for electrostatically transferring a toner image formed of (30C, 30M, 30Y, 30K) onto a medium PM. The transfer roller 44 (44C, 44M, 44Y, 44K) is made of, for example, a foamable semi-conductive elastic rubber material.

(Fixing part 5)
The fixing unit 5 is a member for fixing the toner image on the medium PM by applying heat and pressure to the toner image transferred on the medium PM that has passed through the transfer unit 4. The fixing portion 5 includes, for example, an upper roller 5A and a lower roller 5B.

The upper roller 5A and the lower roller 5B are configured to include a heat source that is a heating heater such as a halogen lamp inside, and functions as a heating roller that applies heat to the toner image on the medium PM. The upper roller 5A is controlled by the control unit 7 and rotates in the direction in which the medium PM is conveyed in the transfer direction by the rotational force transmitted from the drive unit 8. The heat source in the upper roller 5A and the lower roller 5B receives a bias voltage controlled by the control unit 7 and controls the surface temperatures of the upper roller 5A and the lower roller 5B. The lower roller 5B is arranged to face the upper roller 5A so that a pressure contact portion is formed between the lower roller 5B and the upper roller 5A, and functions as a pressure roller that applies pressure to the toner image on the medium PM. To do. The lower roller 5B may have a surface layer made of an elastic material.

(Control unit 7)
The control unit 7 controls the entire processing operation in the image forming apparatus, for example, by executing a predetermined program. The control unit 7 is an I / F control unit that receives print data or control commands from an external device such as a personal computer (PC) or transmits a signal regarding the state of the image forming device, and a microprocessor, ROM, and RAM. It is composed of an input / output port and the like, and has a print control unit that receives print data and control commands from the I / F control unit and controls the print operation.

[1.2 Configuration of image forming unit 30]
2A and 2B are schematic cross-sectional views showing a schematic configuration example of the image forming unit 30 according to the embodiment of the present invention. In FIG. 2A, the shutter unit 60 described later is in the open state, and in FIG. 2B, the shutter unit 60 described later is in the closed state. Further, in the present embodiment, the image forming units 30K, 30C, 30M, and 30Y have substantially the same structure except that the types of toners used are different from each other. Therefore, in principle, the image forming unit 30 will be described below. I will explain it by writing. Along with this, in the following description, in principle, the exposure apparatus 40 (40C, 40M, 40Y, 40K) is simply referred to as the exposure apparatus 40, and the toner cartridge 50 (50C, 50M, 50Y, 50K) is simply referred to as the toner cartridge 50. The toner supply transport path 51 (51C, 51M, 51Y, 51K) is simply referred to as the toner supply transport path 51, and the transfer roller 44 (44C, 44M, 44Y, 44K) is simply referred to as the transfer roller 44. The drum 11 (11K, 11C, 11M, 11Y) is simply referred to as the photosensitive drum 11.

The toner is composed of a non-magnetic material containing, for example, a binder resin such as a polyester resin, a charge control agent as an internal additive, a mold release agent and a colorant, and an external additive such as silica or titanium oxide. It is a thing. Of these, the color of the toner image formed by the image forming unit 30 can be changed by appropriately selecting the color of the colorant.

As shown in FIG. 2A, the image forming unit 30 includes a developing device 201 and a drum unit 202. A toner supply transport path 51 connected to the toner cartridge 50 is mounted on the upper part of the developing device 201.

(Developer 201)
In the developing device 201, for example, in the internal space 21V of the housing 21, the developing roller 22, the developing blade 23, the supply roller 24, the stirring members 25A and 25B, the toner amount detecting unit 26, and the first toner transfer spiral 27 are used. And a second toner transfer spiral 28.

The housing 21 has an input port 29 into which toner is input at an upper portion where the toner supply transport path 51 is mounted. The insertion port 29 is provided in a portion of the housing 21 other than both ends in the width direction (X-axis direction), and is particularly preferable to be provided in the central portion in the width direction. The toner from the toner cartridge 50 is temporarily accommodated in the internal space 21V of the housing 21. The housing 21 is a specific example corresponding to the "main body" of the present invention.

The developing roller 22 carries toner on its surface to supply toner to the photosensitive drum 11, and is a substantially columnar rotating body that develops toner on an electrostatic latent image supported on the image-supporting surface 11S of the photosensitive drum 11. Is. The developing rollers 22 are arranged so that their surfaces are in contact with the photosensitive drum 11. The developing roller 22 has, for example, a shaft and an elastic layer that covers the outer periphery (surface) of the shaft. The shaft of the developing roller 22 is a columnar member made of a material having good conductivity, for example, a metal material including iron (Fe), aluminum (Al), stainless steel, and the like. Further, as a constituent material of the elastic layer of the developing roller 22, a rubber material such as silicone rubber or urethane is used. Specific examples thereof include those using a polyether polyol and an aliphatic isocyanate as a base polymer. The elastic layer of the developing roller 22 may contain carbon black such as acetylene black or ketjen black as a conductive agent in order to adjust its resistance value. Under the control of the control unit 7, the developing roller 22 rotates counterclockwise in the same direction as the supply roller 24 (in this example, as shown by the arrow R22 in FIG. 2A) due to the rotational force transmitted from the drive unit 8. It is designed to rotate in the direction opposite to that of the photosensitive drum 11)).

The developing blade 23 is a toner regulating member that forms a layer (toner layer) made of toner on the surface of the rotating developing roller 22 and regulates (controls, adjusts) the thickness of the toner layer. The developing blade 23 is a plate-shaped elastic member (leaf spring) made of stainless steel such as JIS standard SUS304, and the tip of the plate-shaped elastic member is arranged so as to slightly abut on the surface of the developing roller 22. There is.

The supply roller 24 is located at the lowermost part of the internal space 21V, that is, on the side opposite to the input port 29, and is a substantially columnar rotating body as a developer supply member that supplies the toner T to the developing roller 22. As shown in FIG. 2A, the supply roller 24 has, for example, a two-layer structure of a shaft (core metal) and an elastic layer covering the outer peripheral surface of the shaft. A coat layer may be further provided so as to cover the outer peripheral surface (surface) of the elastic layer of the supply roller 24. The shaft of the supply roller 24 is a columnar member made of a material having good conductivity, for example, a metal material including iron (Fe), aluminum (Al), SUM material, stainless steel, and the like. As a constituent material of the elastic layer of the supply roller 24, for example, a foamed elastic material containing a plurality of cells (voids) inside, specifically, a rubber material such as foamed silicone rubber or urethane foam is preferably used. Further, the supply roller 24 is arranged so that the surface of the supply roller 24 is in contact with the surface of the developing roller 22. Here, the supply roller 24 is in the same direction as the developing roller 22 centering on the shaft extending in the X-axis direction by the rotational force transmitted from the drive unit 8 under the control of the control unit 7 (in this example, FIG. 2A). The toner T is supplied to the surface of the developing roller 22 by rotating (counterclockwise as shown by the arrow R24). Therefore, at the contact portion between the supply roller 24 and the developing roller 22, the surface of the supply roller 24 and the surface of the developing roller 22 move in opposite directions.

The stirring members 25A and 25B are, for example, rotating members obtained by bending a rod-shaped member having a diameter of about several mm into a crank shape, and stir the toner existing in the internal space 21V of the housing 21. Rotational force is transmitted from the drive unit 8 to the stirring members 25A and 25B under the control of the control unit 7. The stirring members 25A and 25B are synchronously rotated by a rotational force from the drive unit 8 in the directions indicated by arrows R25A and R25B in FIG. 2, for example, with a rotation axis extending in the X-axis direction as the center, for example, at a constant rotation speed. (Rotates clockwise in FIG. 2A). The stirring members 25A and 25B are provided between the supply roller 24 and the first toner transfer spiral 27.

The first toner transfer spiral 27 is a member provided in the internal space 21V of the housing 21 and transports the toner in the X-axis direction while stirring the toner by rotating by the rotational force from the drive unit 8. Rotational force is transmitted from the drive unit 8 to the first toner transfer spiral 27 based on the control of the control unit 7. As shown in FIG. 2A, the first toner transfer spiral 27 is provided between the toner amount detection unit 26 and the second toner transfer spiral 28 in the horizontal direction. For example, the toner amount detection unit 26 and the second toner It is preferable that it is arranged diagonally below the transport spiral 28. Further, the first toner transfer spiral 27 may be located, for example, directly below the inlet 29 of the housing 21 in the vertical direction.

The second toner transfer spiral 28 is provided in the internal space 21V of the housing 21 like the first toner transfer spiral 27. The second toner transport spiral 28 is a member that transports toner in the X-axis direction while stirring the toner by rotating with a rotational force transmitted from the drive unit 8 under the control of the control unit 7. As shown in FIG. 2A, the second toner transfer spiral 28 is provided between the wall surface of the housing 21 and the first toner transfer spiral 27 in the horizontal direction, and is, for example, obliquely upward of the first toner transfer spiral 27. It should be placed in.

The toner amount detecting unit 26 (FIG. 2A) is a mechanism for detecting the remaining amount of toner contained in the internal space 21V of the housing 21. The toner amount detecting unit 26 is located in the internal space 21V of the housing 21 on the side opposite to the second toner transport spiral 27 with the first toner transport spiral 27 in the horizontal direction. That is, the toner amount detecting unit 26 is provided between the first toner transfer spiral 27 and the wall portion of the housing 21 on the opposite side of the second toner transfer spiral in the horizontal direction. Further, the toner amount detection unit 26 is preferably located diagonally above the first toner transfer spiral 27.

The developing device 201 further includes, for example, a shutter unit 60 and a guide member 70 supported by the housing 21, respectively. The details of the shutter unit 60 and the guide member 70 will be described later.

(Drum unit 202)
Subsequently, the components of the drum unit 202 in the image forming unit 20 will be described with reference to FIGS. 2A and 2B.

The drum unit 202 has, for example, a photosensitive drum 11, a charging roller 12, a cleaning blade 13, and a toner transfer spiral 14 inside a housing 21 common to the developing device 201.

The photosensitive drum 11 is a columnar member capable of supporting an electrostatic latent image on the surface (image-supporting surface) 11S, and is configured by using a photoconductor (for example, an organic photoconductor). Specifically, the photosensitive drum 11 has a conductive support and a photoconductive layer that covers the outer periphery (surface) thereof. The conductive support is made of, for example, a metal pipe made of aluminum. The photoconductive layer has, for example, a structure in which a charge generation layer and a charge transport layer are laminated in this order. The photosensitive drum 11 is rotatably held by the housing 21 so that a part of the image-carrying surface 11S is exposed. The photosensitive drum 11 is controlled by the control unit 7 and rotates at a predetermined rotation speed in the rotation direction R11 indicated by the arrow, which is the direction in which the medium PM is conveyed in the transfer direction.
The image-supporting surface 11S is a specific example corresponding to the "image-supporting surface" of the present invention.

The charging roller 12 is a member (charging member) that charges the surface (surface layer portion) of the photosensitive drum 11, and is arranged so as to be in contact with the image-supporting surface 11S of the photosensitive drum 11. The charging roller 12 has, for example, a metal shaft and a semi-conductive rubber layer (for example, a semi-conductive epichlorohydrin rubber layer) that covers the outer periphery (surface) thereof. The charging roller 12 rotates in the same direction as the photosensitive drum 11, for example.

The cleaning blade 13 is a member that cleans the image-supporting surface 11S of the photosensitive drum 11 by scraping and collecting the toner T remaining on the image-supporting surface 11S of the photosensitive drum 11. The cleaning blade 13 is arranged so as to come into contact with the image-carrying surface 11S with a counter (project in the opposite direction to the rotation direction R11 of the photosensitive drum 11). Such a cleaning blade 13 is made of an elastic body such as polyurethane rubber, for example.

The toner transfer spiral 14 is a member that conveys the toner T scraped off by the cleaning blade 13 in the X-axis direction, for example, and discharges the toner T to the outside of the housing 21.

(Shutter unit 60)
Next, a detailed configuration of the shutter unit 60 in the developing apparatus 201 will be described with reference to FIGS. 3 and 4A and 4B. FIG. 3 is a perspective view showing the appearance of the image forming unit 30 when viewed from diagonally below, and FIGS. 4A and 4B are perspective views showing the appearance of the shutter unit 60. In particular, FIG. 4A shows the appearance seen from the photosensitive drum 11, and FIG. 4B shows the appearance seen from the side opposite to the photosensitive drum 11.

The shutter unit 60 is supported by the housing 21 so as to cover a part of the image-supporting surface 11S exposed from the housing 21 in the photosensitive drum 11. The shutter unit 60 includes a first shutter member 61 and a second shutter member 62. The shutter unit 60 can shift between the closed state and the open state by changing the postures of the first shutter member 61 and the second shutter member 62 with respect to the housing 21. The closed state referred to here is a state in which the shutter unit 60 is expanded so as to cover a part of the image-carrying surface 11S of the photosensitive drum 11. On the other hand, the open state is a state in which the photosensitive drum 11 is degenerated so as to expose a larger portion of the image-carrying surface 11S.
The shutter unit 60 is a specific example corresponding to the "shutter unit" of the present invention, and the first shutter member 61 is a specific example corresponding to the "first shutter member" of the present invention. The member 62 is a specific example corresponding to the "second shutter member" of the present invention.

The first shutter member 61 includes a round bar-shaped first shaft 611 extending in the X-axis direction, a round bar-shaped second shaft 612 extending substantially parallel to the first shaft 611, and a first shaft. It has a flat plate-shaped first flat plate portion 613 that connects the 611 and the second shaft 612. The first flat plate portion 613 is fixed to both the first shaft 611 and the second shaft 612, and includes a first inner surface 613S that can face the image-carrying surface 11S in the closed state. A lever 614 is provided at the first end of the first shaft 611, and a spring 615 as an urging member is provided at the second end of the first shaft 611 opposite to the lever 614. In the present embodiment, a plurality of first flat plate portions 613 are provided so as to be dispersedly arranged between the lever 614 at the first end portion and the spring 615 at the second end portion. .. The first shutter member 61 is rotatably held by the housing 21 with respect to the housing 21 around the rotation shaft 611J of the first shaft 611. Further, a first rotation angle regulating portion 631 (see FIG. 4B) including a first contact surface 631S (see FIG. 5A described later) is provided on a part of the second shaft 612 in the X-axis direction.

The lever 614 is integrated with the first shaft 611, and is in contact with, for example, a protrusion 10T (see FIGS. 7A to 7C described later) provided on the inner surface of the housing 10 and receives a rotational force from the protrusion. The first shaft 611 (first shutter member 61) is rotated by the above.

The spring 615 is an urging member that applies an urging force to the first shutter member 61 to shift the state from the open state to the closed state.

The second shutter member 62 is rotatably held by the first shutter member 61 with respect to the first shutter member 61 around the rotation shaft 612J of the second shaft 612. The second shutter member 62 has a grip portion 621 that rotatably holds the second shaft 612, and a second flat plate portion 622 fixed to the grip portion 621. In the present embodiment, the plurality of grip portions 621 are arranged in the gaps between the plurality of first flat plate portions 613. Further, the second flat plate portion 622 includes a second inner surface 622S that can face the image-carrying surface 11S in the closed state. Further, a second rotation angle regulation unit 632 (see FIG. 4A) is provided at a position corresponding to the first rotation angle regulation unit 631 in a part of the second flat plate portion 622. The second rotation angle regulating unit 632 includes a second contact surface 632S (see FIG. 5A described later) that comes into contact with the first contact surface 631S in the closed state. Further, the second shutter member 62 abuts on a peripheral region located outside the effective image forming region of the image-carrying surface 11S in the longitudinal direction (X-axis direction) of the image forming unit 30 with the guide member 70 described later. A contact portion 623 and a second contact portion 624 are provided. The effective image forming region means a region in which an image that can be transferred to the medium PM is formed. The first contact portion 623 is a specific example corresponding to the "first contact portion" of the present invention, and the second contact portion 624 corresponds to the "second contact portion" of the present invention. This is a specific example.

5A to 5C show schematic cross-sectional views of the shutter unit 60 and its vicinity. 5A to 5C show a cross section in the direction of the arrow along the VV line shown in FIG. In FIG. 5A, the shutter unit 60 is in the closed state, in FIG. 5B, the shutter unit 60 is in the open state, and in FIG. 5C, it is in an intermediate state between the closed state and the open state. Further, FIGS. 6A and 6B show a cross section in the arrow-viewing direction along the VI-VI line shown in FIG. In FIG. 6A, the shutter unit 60 is in the closed state. FIG. 6A shows a state in which the holding portion 72 of the guide member 70 is in contact with the outer surface 624G of the second contact portion 624, and the shutter unit 60 is held in the open state. In this open state, the second contact portion 624 is held by the holding portion 72 so as to ride on the holding portion 72. The outer surface 624G refers to the surface of the second contact portion 624 other than the inner surface facing the image-carrying surface 11S of the photosensitive drum 11. In FIG. 6B, when the shutter unit 60 shifts from the closed state to the open state, a part of the second shutter member 62 (for example, the outer surface 623G described later) is a guide surface 71S of the guide portion 71 of the guide member 70. It shows the state at the time of contact with.

In the shutter unit 60, as shown in FIG. 5A, when the first contact surface 631S and the second contact surface 632S come into contact with each other in the closed state, the second shutter member 62 with respect to the first shutter member 61 The angle of formation is regulated. That is, in the shutter unit 60, the angle θ formed by the first inner surface 613S and the second inner surface 622S shifts from the minimum angle θmin to the maximum angle θmax by shifting from the open state to the closed state. In the shutter unit 60 that has reached the closed state, the angle θ is regulated so as not to exceed a predetermined maximum angle θmax due to the contact between the first contact surface 631S and the second contact surface 632S.
The first contact surface 631S and the second contact surface 632S are specific examples corresponding to the "first contact surface" and the "second contact surface" of the present invention, respectively.

As shown in FIG. 5A, in the shutter unit 60, the first shutter member 61 and the second shutter member so that the first inner surface 613S and the second inner surface 622S face the image-carrying surface 11S, respectively, in the closed state. 62 is deployed. On the other hand, as shown in FIG. 5B, in the open state, the first shutter member 61 and the second shutter member 62 are folded so that the first inner surface 613S and the second inner surface 622S face each other. .. In the open state, the angle θ is the minimum angle θmin.

In the cross section orthogonal to the X-axis, it is preferable that the shutter unit 60 shifts between the closed state and the open state without protruding from the region overlapping the housing 21. This is because it is not necessary to increase the size of the housing 21 in order to secure a space for the shutter unit 60 to sweep when the state is changed, which is advantageous for making the overall configuration of the image forming unit 30 compact.

The second inner surface 622S of the second shutter member 62 may have a rib 64 (FIG. 4A) capable of contacting a peripheral region of the image-supporting surface 11S that is out of the effective image forming region. In the closed state of the shutter unit 60, the second inner surface 622S of the second shutter member 62 comes into contact with the effective image forming region of the image supporting surface 11S, so that the effective image forming region of the image supporting surface 11S is damaged. This is because it can be surely avoided.

(Guide member 70)
The guide member 70 is supported by the housing 21 and has a guide portion 71 including a guide surface 71S as shown in FIGS. 6A and 6B. The guide portion 71 is provided at a position away from the first shaft 611 and the photosensitive drum 11, and is in contact with the outer surface 623G opposite to the second inner surface 622S of the first contact portion 623 of the second shutter member 62. 2 The shutter member 62 is guided. The guide unit 71 regulates the movement of the second shutter member 62 in the direction away from the image-carrying surface 11S when the shutter unit 60 shifts to the state.

In the cross section orthogonal to the X-axis, the distance between the first shaft 611 and the guide surface 71S of the guide member 70 is preferably wider than the second distance between the first shaft 611 and the second shaft 612. As a result, when the shutter unit 60 shifts between the open state and the closed state, the guide member 70 can be prevented from interfering with the first shaft 611, that is, not in direct contact with the first shaft 611. Further, by providing the guide member 70 outside the effective image forming region on the image-carrying surface 11S in the X-axis direction, when the shutter unit 60 shifts between the open state and the closed state, the guide member 70 and the shutter Interference of the unit 60 can be prevented.

Further, in the cross section orthogonal to the X-axis, the distance between the image-supporting surface 11S and the guide surface 71S of the guide member 70 is preferably wider than the distance between the image-supporting surface 11S and the first shaft 611. This is because the space swept by the shutter unit 60 when the state of the shutter unit 60 changes can be made smaller.

In the cross section orthogonal to the X axis, the first length from the rotating shaft 611J of the first shaft 611 to the rotating shaft 612J of the second shaft 612 is on the side opposite to the rotating shaft 612J of the second shaft 612. It should be shorter than the second length to the tip (see FIGS. 2A and 2B). This is because the length of the first shutter member 61 is shorter than the length of the second shutter member 62, so that the space swept when the shutter unit 60 shifts to the state can be made smaller.

Further, the guide member 70 may further include a holding portion 72. As shown in FIG. 6A, the holding portion 72 abuts on the second contact portion 624 of the second shutter member 62 in the open state to hold the posture of the folded shutter unit 60. .. In the open state, when the holding portion 72 comes into contact with the outer surface 624G of the second contact portion 624, the second shutter member 62 hangs down so as to protrude from the housing 21 due to its own weight, and another member (for example, the transfer portion). It is designed to prevent interference with 4). In the open state, the guide surface 71S of the guide portion 71 of the guide member 70 may be separated from the outer surface 623G of the first contact portion 623.

[1.3 Actions / Effects]
(A. Basic operation)
In this image forming apparatus, the toner image is transferred to the medium PM as follows.

When print image data and a print command are input to the control unit 7 from an external device such as a PC for the image forming device in the activated state, the control unit 7 responds to each component of the image forming device with the print command. To start the printing operation of the print image data.

For example, as shown in FIG. 1, the media PM housed in the paper feed tray 1 is picked up one by one from the top by a pickup roller or the like, and the skew is corrected by the feed roller to the downstream image forming unit 3. It is conveyed in the direction indicated by the arrow Y1. In the image forming unit 3, the toner image is transferred onto the medium PM as follows.

In the image forming unit 3, the toner image of each color is formed by the following electrophotographic process according to the printing command of the control unit 7. Specifically, the control unit 7 activates the drive unit 8 to charge the toner contained in the toner cartridge 50 into the internal space 21V of the housing 21 from the charging port 29, and pushes the photosensitive drum 11 in the direction of the arrow Y11. Rotate at a constant speed. Along with this, the charging roller 12, the developing roller 22, and the supply roller 24 also start rotating in a predetermined direction.

On the other hand, the control unit 7 applies a predetermined voltage to the charging rollers 12 of each color to uniformly charge the surface of the photosensitive drum 11 of each color. Next, the control unit 7 activates the exposure device 40, irradiates the photosensitive drum 11 of each color with light corresponding to the color component of the printed image based on the image signal, and creates an electrostatic latent image on the surface of the photosensitive drum 11 of each color. Form each.

The toner T is supplied to the developing roller 22 via the supply roller 24 and is supported on the surface of the developing roller 22. The developing roller 22 adheres toner to the electrostatic latent image formed on the photosensitive drum 11 to form a toner image. Further, a predetermined voltage is applied to the transfer roller 44 in the transfer unit 4, and an electric field is generated between the photosensitive drum 11 and the transfer roller 44. When the medium PM runs between the photosensitive drum 11 and the transfer roller 44 in that state, the toner image formed on the photosensitive drum 11 is transferred onto the medium PM. That is, in this image forming apparatus, the toner image is transferred to the medium PM by directly touching the image-carrying surface 11S with the medium PM.

After that, the toner image on the medium PM is fixed to the medium PM by applying heat and pressure to the fixing portion 5. The medium PM on which the toner image is fixed is conveyed in the direction of arrow Y4 shown in FIG. 1, and is discharged to a stacker outside the image forming apparatus by the discharging unit.

(B. State transition operation of shutter unit 60)
In the present embodiment, when the image forming unit 30 is mounted at a predetermined position inside the housing 10, the shutter unit 60 in the closed state shifts to the open state. Hereinafter, the operation of the state transition of the shutter unit 60 will be described with reference to FIGS. 7A to 7C. 7A to 7C are cross-sectional views showing an enlarged view of a main part of the image forming unit 30 when it is mounted at a predetermined position inside the housing 10.

First, the image forming unit 30 is moved so as to approach the housing 10 from above, and as shown in FIG. 7A, the protrusion 10T provided inside the housing 10 comes into contact with the lever 614. As a result, the lever 614 starts rotating in the rotation direction R614 indicated by the arrow with the rotation shaft 611J as the center of rotation.

When the image forming unit 30 is further moved downward as it is, the lever 614 further rotates in the rotation direction R614 as shown in FIG. 7B, and the lever 614 finally moves to the rotation direction R614 until the state shown in FIG. 7C. Rotate. FIG. 7C shows a state in which the image forming unit 30 has been mounted at a predetermined position.

In the shutter unit 60, the first shaft 611 rotates together with the lever 614. Therefore, the lever 614 comes into contact with the protrusion 10T and rotates in the rotation direction R614 from the position of FIG. 7A to the position of FIG. 7C, so that the first shutter member 61 and the second shutter member 62 are interlocked with each other in FIG. 5A. The state transition from the indicated closed state to the open state is started. At this time, as shown in FIGS. 5C and 6B, the contact between the first contact surface 631S of the first rotation angle regulating portion 631 and the second contact surface 632S of the second rotation angle regulating portion 632 is released. , The outer surface 623G of the first contact portion 623 and the guide surface 71S of the guide portion 71 come into contact with each other. After that, the guide member 70 causes the second shutter member 62 to be separated from the outside of the housing 21 (away from the image-carrying surface 11S) by its own weight by releasing the contact between the first contact surface 631S and the second contact surface 632S. The outer surface 623G is guided by the guide member 70 so as to restrict the drooping in the vertical direction), and the state shifts to the open state shown in FIG. 5B. By guiding the outer surface 623G by the guide member 70 in this way, it is possible to prevent the second shutter member 62 from being separated from the image-carrying surface 11S by its own weight at the time of state transition. At the time of the transition, the first shutter member 61 rotates in the first rotation direction R61 (FIG. 5A) with respect to the housing 21, and the second shutter member 62 rotates in the first rotation direction with respect to the first shutter member 61. It rotates in the second rotation direction R62 (FIG. 5A) opposite to R61. At the time of transition from the closed state to the open state, for example, on the paper of FIG. 5A, the first rotation direction R61 is a counterclockwise rotation, and the second rotation direction R62 is a clockwise rotation. Further, when the state is changed from the open state to the closed state, the directions are opposite to each other. Further, in the open state, as shown in FIG. 6A, when the holding portion 72 comes into contact with the second contact portion 624, the second shutter member 62 hangs down so as to protrude from the housing 21 due to its own weight. It is regulated that it interferes with the member (for example, the transfer unit 4).

On the contrary, when the image forming unit 30 is removed from the housing 10 from the state where the image forming unit 30 is mounted at a predetermined position of the housing 10, the shutter unit 60 performs the reverse operation as described above. .. That is, since the lever 614 is constantly subjected to the urging force from the spring 615, when the image forming unit 30 is lifted upward so as to be separated from the housing 10, the lever 614 is in contact with the protrusion 10T and is shown from the position of FIG. 7C. It rotates in the direction opposite to the rotation direction R614 to the position of 7A. As a result, the shutter unit 60 is in the closed state shown in FIG. 5A while the outer surface 623G is guided by the guide member 70 from the open state shown in FIG. 5B in which the first shutter member 61 and the second shutter member 62 are interlocked. It will shift to the state until.

(C. Action and effect of image forming apparatus)
As described above, in the present embodiment, since the shutter unit 60 and the guide member 70 having the above-described configuration are provided, the shutter unit 60 determines the arrangement position of the photosensitive drum 11 with respect to the housing 21 and the image forming unit 30. Regardless of the posture, the state can be smoothly transitioned from the closed state covering the image-carrying surface 11S to the open state exposing the image-carrying surface 11S. Moreover, the space swept by the shutter unit 60 at the time of the state transition can be made smaller. Therefore, according to the image forming unit 30 and the image forming apparatus of the present embodiment, excellent image forming performance can be ensured by protecting the image-carrying surface 11S in spite of its small size.

Further, in the present embodiment, the first shutter member 61 has the first rotation angle regulating portion 631 including the first contact surface 631S, and the second shutter member 62 has the second rotation including the second contact surface 632S. The angle regulating portion 632 is provided, and the angle θ formed by the second shutter member 62 with respect to the first shutter member 61 is regulated by the contact between the first contact surface 631S and the second contact surface 632S in the closed state. I made it. Therefore, in the closed state, the shutter unit 60 is configured to be self-supporting without relying on the guide member 70. That is, since it is not necessary to separately provide a member for supporting the second shutter member 62 in the closed state, there is no unnecessary member at a position covering the image-supporting surface 11S in the closed state. Therefore, the exposure of the image-carrying surface during use (at the time of image formation) is not hindered.

<2. Second Embodiment>
[2.1 Configuration of image forming unit 130]
Next, the image forming unit 130 according to the second embodiment of the present invention will be described. 8A and 8B are perspective views showing an example of the overall configuration of the image forming unit 130 when viewed from diagonally below. The image forming unit 130 can be mounted on the image forming apparatus shown in FIG. 1 in the same manner as the image forming unit 30 in the first embodiment. As shown in FIGS. 8A and 8B, the image forming unit 130 has a shutter unit 100 (described later) and a guide member 170 (described later) instead of the shutter unit 60 and the guide member 70. In particular, FIG. 8A shows a state when the shutter unit 100 is in the closed state, and FIG. 8B shows a state when the shutter unit 100 is in the open state. The image forming unit 130 has substantially the same configuration as the image forming unit 30 except for those differences. Therefore, in the following, the components different from the image forming unit 30 will be described, and the description of the components substantially the same as the image forming unit 30 will be omitted as appropriate.

[2.2 Configuration of Shutter Unit 100]
A detailed configuration of the shutter unit 100 will be described with reference to FIGS. 9A to 14B in addition to FIGS. 8A and 8B. 9A and 9B are perspective views showing the appearance of the shutter unit 100. In particular, FIG. 9A shows the appearance seen from the photosensitive drum 11, and FIG. 9B shows the appearance seen from the side opposite to the photosensitive drum 11.

The shutter unit 100 is supported by the housing 21 so that a part of the image-supporting surface 11S exposed from the housing 21 of the photosensitive drum 11 can be covered. The shutter unit 100 includes a first shutter member 101 and a second shutter member 102. The shutter unit 100 is capable of shifting between a closed state and an open state by changing the postures of the first shutter member 101 and the second shutter member 102 with respect to the housing 21. The closed state referred to here is a state in which the shutter unit 100 is expanded so as to cover a part of the image-carrying surface 11S of the photosensitive drum 11. On the other hand, the open state is a state in which the photosensitive drum 11 is degenerated so as to expose a larger portion of the image-carrying surface 11S.
The shutter unit 100 is a specific example corresponding to the "shutter unit" of the present invention, and the first shutter member 101 is a specific example corresponding to the "first shutter member" of the present invention. The member 102 is a specific example corresponding to the "second shutter member" of the present invention.

The first shutter member 101 includes a round bar-shaped first shaft 103 extending in the X-axis direction, a round bar-shaped second shaft 104 extending substantially parallel to the first shaft 103, and a first shaft. It has a flat plate-shaped first flat plate portion 105 that connects the 103 and the second shaft 104. The first flat plate portion 105 is fixed to both the first shaft 103 and the second shaft 104. The first flat plate portion 105 includes a first inner surface 105S that can face the image-carrying surface 11S in the closed state, and a first outer surface 105SS that is opposite to the first inner surface 105S. As shown in FIG. 9A, for example, a plurality of first flat plate portions 105 are provided, and a first opening 101K is provided between adjacent first flat plate portions 105.

A lever 107 is provided at the first end of the first shaft 103, and a spring 106 as an urging member is provided at the second end of the first shaft 103 opposite to the lever 107. In the present embodiment, a plurality of first flat plate portions 105 are provided so as to be dispersedly arranged between the lever 107 at the first end portion and the spring 106 at the second end portion. ..

The first shutter member 101 is rotatably held by the housing 21 with respect to the housing 21 about the rotation shaft 103J of the first shaft 103. Further, a first rotation angle regulating portion 108 (see FIG. 9B) is provided on a part of the second shaft 104 in the X-axis direction, similarly to the second shaft 612 of the first embodiment.

The lever 107 is integrated with, for example, the first shaft 103. The lever 107 comes into contact with, for example, a protrusion 10T (see FIGS. 7A to 7C) provided on the inner surface of the housing 10 of the image forming apparatus shown in FIG. 1, and receives a force F from the protrusion to move to the rotation direction 107R. It is designed to rotate (see FIGS. 10A and 10B). As the lever 107 rotates, the first shaft 103 (first shutter member 101) rotates about the rotation shaft 103J. Note that FIG. 10A shows the image forming unit 130 when the shutter unit 100 is in the unfolded closed state, and FIG. 10B shows the image forming unit 130 when the shutter unit 100 is in the folded open state. That is, in the image forming unit 130 in the state of being separated from the housing 10 of the image forming apparatus, the shutter unit 100 is in the closed state, but when it is attached to the housing 10 of the image forming apparatus, the shutter unit 100 is in the open state. Printing operation becomes possible.

The spring 106 is an urging member that applies an urging force for shifting the state from the open state to the closed state to the first shutter member 101.

The second shutter member 102 is rotatably held by the first shutter member 101 with respect to the first shutter member 101 about the rotation shaft 104J of the second shaft 104. The second shutter member 102 has a grip portion 109 that rotatably holds the second shaft 104, and a second flat plate portion 110 that is fixed to the grip portion 109. In the present embodiment, the plurality of grip portions 109 are arranged in the gaps between the plurality of first flat plate portions 105. Further, the second flat plate portion 110 further includes a second inner surface 110S and a second outer surface 110SS on the opposite side of the second inner surface 110S. The second inner surface 110S is provided so as to face the image-carrying surface 11S in the closed state. As shown in FIG. 9A, for example, a plurality of second flat plate portions 110 are provided, and a second opening 102K is provided between adjacent second flat plate portions 110. In the open state, the shutter unit 100 is folded so that the first flat plate portion 105 is housed in the second opening 102K and the second flat plate portion 110 is housed in the first opening 101K. Further, a second rotation angle regulating portion 111 (see FIG. 9A) is provided at a position corresponding to the first rotation angle regulating portion 108 in a part of the second flat plate portion 110. The second rotation angle regulating unit 111 comes into contact with the first rotation angle regulating unit 108 in the closed state. Further, the second shutter member 102 can come into contact with the guide member 170, which will be described later, with a peripheral region located outside the effective image forming region of the image supporting surface 11S in the longitudinal direction (X-axis direction) of the image forming unit 130. The first contact portion 102a, the second contact portion 102b, and the third contact portion 102c are provided. The effective image forming region means a region in which an image that can be transferred to the medium PM is formed. Here, the second shutter member 102 is rotatably held by the first shutter member 101 on the second shaft 104, and the first contact portion 102a is between the second contact portion 102b and the second shaft 104. The third contact portion 102c is provided between the second contact portion 102b and the first contact portion 102a.
The first contact portion 102a is a specific example corresponding to the "first contact portion" of the present invention, and the second contact portion 102b corresponds to the "second contact portion" of the present invention. As a specific example, the third contact portion 102c is a specific example corresponding to the “third contact portion” of the present invention.

[2.3 Configuration of guide member 170]
FIG. 11 shows an enlarged view of the vicinity of the lever 107 of the image forming unit 130 shown in FIG. 8A. As shown in FIG. 10, the guide member 170 has a first guide portion 171, a holding portion 172, and a second guide portion 173. The first guide portion 171 and the holding portion 172 and the second guide portion 173 are integrated, for example, and are supported by, for example, a housing 21. However, the first guide portion 171 and the holding portion 172 and the second guide portion 173 may be separate bodies. Alternatively, any two of the three components of the first guide unit 171 and the holding unit 172 and the second guide unit 173 may be integrated.
The first guide unit 171 is a specific example corresponding to the "first guide unit" of the present invention, and the holding unit 172 is a specific example corresponding to the "holding unit" of the present invention. Section 173 is a specific example corresponding to the "second guide section" of the present invention.

12A and 12B are cross-sectional views showing the state of the image forming unit 130 in the intermediate stage when the shutter unit 100 shifts from the closed state to the open state. FIG. 12A shows a cross section in the direction of the arrow along the VV line shown in FIG. FIG. 12B shows a cross section in the arrow-viewing direction along the WW line shown in FIG. 13A and 13B are cross-sectional views showing the state of the image forming unit 130 at the stage following FIGS. 12A and 12B. FIG. 13A shows a cross section in the arrow-viewing direction along the VV line shown in FIG. FIG. 13B shows a cross section in the arrow-viewing direction along the WW line shown in FIG. 14A and 14B are cross-sectional views showing a state of the image forming unit 130 in which the shutter unit 100 is in the open state. FIG. 14A shows a cross section in the arrow-viewing direction along the VV line shown in FIG. FIG. 14B shows a cross section in the arrow-viewing direction along the WW line shown in FIG.

The first guide portion 171 is supported by the housing 21 in a peripheral region other than the effective image forming region. As shown in FIGS. 12A to 14B, the first guide portion 171 makes a first contact in the peripheral region at the time of transition between the closed state shown in FIG. 10A and the open state shown in FIG. 10B. It comes into contact with the portion 102a. The first guide portion 171 is adapted to restrict the movement of the second shutter member 102 in the direction away from the image-carrying surface 11S by contacting the first contact portion 102a in the peripheral region.

The holding portion 172 is supported by the housing 21 in a peripheral region other than the effective image forming region. The holding portion 172 is adapted to abut the second contact portion 102b in the peripheral region to hold the shutter unit 100 in the open state.

The second guide portion 173 is the third contact portion 102c after the first contact portion 102a and the first guide portion 171 are in contact with each other at the time of transition between the closed state and the open state of the shutter unit 100. The movement of the second shutter member 102 in the direction away from the image-carrying surface 11S is restricted. The second guide portion 173 contacts the third contact portion 102c and guides the third contact portion 102c when the state shifts from the closed state to the open state, so that the second inner surface 110S is first. It is designed to be closer to the inner surface 105S. The third contact portion 102c includes a protruding portion of the second outer surface 110SS that protrudes in the opposite direction to the second inner surface 110S.

[2.4 Actions / Effects]
(About the state transition operation of the shutter unit 100)
In the present embodiment, as described above, when the image forming unit 130 is mounted at a predetermined position inside the housing 10 of the image forming apparatus, the shutter unit 100 in the closed state is mounted on the same as the image forming unit 30. The state shifts to the open state.

For example, from the closed state shown in FIG. 15A, that is, the state in which the second shutter member 102 of the shutter unit 100 covers the image-carrying surface 11S of the photosensitive drum 11, the first step shown in FIG. 15B and the first step shown in FIG. 15C are shown. After the second stage, the state shifts to the open state shown in FIG. 15D, that is, the printable state. 15A to 15D are cross-sectional views showing the state transition operation of the shutter unit stepwise, and show a cross-sectional view in the arrow-viewing direction along the X-ray line shown in FIG. Also, FIG. 15B corresponds to FIGS. 12A and 12B, FIG. 15C corresponds to FIGS. 13A and 13B, and FIG. 15D corresponds to FIGS. 14A and 14B.

In the shutter unit 100, the first shaft 103 rotates together with the lever 107. Therefore, as shown in FIGS. 10A and 10B, when the lever 107 receives the force F and rotates in the rotation direction 107R, the first shutter member 101 and the second shutter member 102 are interlocked with each other from the closed state. Start the state transition to the open state. At this time, the contact between the first rotation angle regulating unit 108 and the second rotation angle regulating unit 111 is released, and the process proceeds to the first stage shown in FIGS. 12A and 12B. Specifically, as shown in FIG. 12A, the outer surface of the first contact portion 102a and the guide surface 171S of the first guide portion 171 come into contact with each other. After that, the first guide portion 171 regulates the second shutter member 102 from hanging toward the outside of the housing 21 (in the direction away from the image-carrying surface 11S) due to the weight of the second shutter member 102. While the outer surface of the contact portion 102a is guided, the shutter unit 100 shifts to the second stage shown in FIGS. 13A and 13B. The third contact portion 102c does not contact the first guide portion 171 (see FIGS. 12B and 15B).

In this way, the first contact portion 102a of the second shutter member 102 is guided by the guide surface 171S of the first guide portion 171. Therefore, when the state shifts, the second shutter member 102 has its own weight to guide the image-carrying surface 11S. You can prevent yourself from leaving.

In the subsequent second step shown in FIGS. 13A and 13B, the third contact portion 102c comes into contact with the guide surface 173S of the second guide portion 173, and as a result, the first contact portion 102a is separated from the guide surface 171S. It will be. When the rotation of the lever 107 in the rotation direction 107R (FIG. 10B) further progresses, the shutter unit so that the second shutter member 102 approaches the first shutter member 101 while the third contact portion 102c is guided by the guide surface 173S. 100 is gradually folded. Finally, as shown in FIG. 14A, the second contact portion 102b comes into contact with the holding portion 172, and the shutter unit 100 is in the open state. In the open state, as shown in FIG. 14B, the third contact portion 102c is separated from the guide surface 173S. In this way, in the open state, when the holding portion 172 comes into contact with the second contact portion 102b as shown in FIG. 14A, the second shutter member 102 hangs down so as to protrude from the housing 21 due to its own weight. It is regulated that it interferes with other members (for example, the transfer unit 4).

As described above, in the present embodiment, since the shutter unit 100 and the guide member 170 having the above-described configuration are provided, the shutter unit 100 determines the arrangement position of the photosensitive drum 11 with respect to the housing 21 and the image forming unit 130. Regardless of the posture, the state can be smoothly transitioned from the closed state covering the image-carrying surface 11S to the open state exposing the image-carrying surface 11S. Moreover, the space swept by the shutter unit 100 at the time of the state transition can be made smaller. Therefore, according to the image forming unit 130 of the present embodiment, excellent image forming performance can be ensured by protecting the image-carrying surface 11S despite its small size.

Further, in the present embodiment, the first shutter member 101 has the first rotation angle regulating unit 108, and the second shutter member 102 has the second rotation angle regulating unit 111. The angle θ formed by the second shutter member 102 with respect to the first shutter member 101 is regulated by the contact between the first rotation angle regulating unit 108 and the second rotation angle regulating unit 111 in the closed state. Therefore, in the closed state, the shutter unit 100 is configured to be self-supporting without relying on the guide member 170. That is, since it is not necessary to separately provide a member for supporting the second shutter member 102 in the closed state, there is no unnecessary member at a position covering the image-supporting surface 11S in the open state. Therefore, the exposure of the image-carrying surface during use (during image formation) is not hindered.

Further, in the present embodiment, the guide member 170 is provided with the second guide portion 173, the second shutter member 102 is provided with the third contact portion 102c, and the second guide portion 173 is opened with the shutter unit 100 closed. At the time of transition between the states, the first contact portion 102a and the first guide portion 171 are brought into contact with each other, and then the third contact portion 102c is brought into contact with the third contact portion 102c. Thereby, even after the first contact portion 102a has passed through the first guide portion 171, the movement of the second shutter member 102 in the direction away from the image-carrying surface 11S can be restricted. As a result, it is possible to reliably prevent the second contact portion 102b of the second shutter member 102 from slipping under the holding portion 172 without being held by the holding portion 172. The guide surface 171S of the first guide portion 171 may be extended, but in that case, a longer stroke is required, and it becomes difficult to effectively use the limited space.

Further, in the present embodiment, when the state shifts from the closed state to the open state, the first contact portion 102a passes outside the holding portion 172 which is opposite to the photosensitive drum 11 when viewed from the holding portion 172. .. Further, the third contact portion 102c comes into contact with the second guide portion 173 after the first contact portion 102a passes outside the holding portion 172. Further, the second contact portion 102b is adapted so that the third contact portion 102c comes into contact with the holding portion 172 after the third contact portion 102c comes into contact with the second guide portion 173. Therefore, the first guide portion 171 and the holding portion 172 and the second guide portion 173 do not protrude to the outside (position far away from the housing 21 and the photosensitive drum 11) from the locus of the second shutter member 102, and the shutter unit. 100 can be folded.

Further, when the shutter unit 100 shifts from the closed state to the open state, the first flat plate portion 105 is housed in the second opening 102K and the second flat plate portion 110 is housed in the first opening 101K. I made it foldable. Therefore, in the open state, the thickness and weight of the folded shutter unit 100 can be reduced, and the size can be further reduced.

<3. Modification example>
Although the present invention has been described above with reference to some embodiments, the present invention is not limited to the above embodiments and can be modified in various ways. For example, in the above embodiment, the image forming apparatus for forming a color image has been described, but the present invention is not limited to this, and for example, an image forming apparatus for forming a monochrome image may be used. Further, in the above-described embodiment, the image forming apparatus of the direct transfer method has been described, but the present invention can also be applied to the secondary transfer method.

Further, the structure, shape, dimensional ratio, and the like of the shutter unit and the like described in the above embodiment are merely examples, and the present invention is not limited thereto. The same applies to the components other than the shutter unit.

Further, in the first embodiment, the first contact portion 623 and the second contact portion 624 are provided only at one position (one end portion in the X-axis direction) of the second shutter member 62. However, the present invention is not limited thereto. That is, in the present invention, the second shutter member may be provided with a plurality of first contact portions and a plurality of second contact portions, respectively. In the present invention, for example, the first contact portion and the second contact portion may be provided at both ends in the X-axis direction of the second shutter member in the X-axis direction. In that case, it is preferable to provide a plurality of guide members (guide portion and holding portion) at positions corresponding to each of the first contact portions and positions corresponding to each of the second contact portions. By restricting the plurality of first contact portions and the plurality of second contact portions in the second shutter member by the plurality of guide members, the state transition between the closed state and the open state and the open state holding are performed. This is because the shutter unit can be stabilized at that time. For example, when the shutter unit is made of resin or the like, it is possible to restrict the second shutter member from hanging due to its own weight due to bending in a direction not regulated by the guide member.

Further, in the above embodiment, the LED head using the light emitting diode as the light source is used as the exposure device, but for example, an exposure device using a laser element or the like as the light source may be used.

Further, in the above-described embodiment, an image forming apparatus having a printing function has been described as a specific example of the "image forming apparatus" in the present invention, but the present invention is not limited thereto. That is, in addition to such a printing function, the present invention can be applied to, for example, an image forming apparatus that functions as a multifunction device having a scanning function and a fax function.

1 ... Paper feed tray, 2 ... Medium transport unit, 3 ... Image forming unit, 4 ... Transfer unit, 5 ... Fixing unit, 6 ... Discharge unit, 7 ... Control unit, 8 ... Drive unit, 30 (30C, 30M, 30Y) , 30K) ... Image forming unit, 40 (40C, 40M, 40Y, 40K) ... Exposure device, 50 (50C, 50M, 50Y, 50K) ... Toner cartridge, 51 (51C, 51M, 51Y, 51K) ... Toner supply and transfer Road, 201 ... developing device, 202 ... drum unit, 11 (11K, 11C, 11M, 11Y) ... photosensitive drum, 11S ... image-bearing surface, 12 ... charging roller, 13 ... cleaning blade, 14 ... toner transfer spiral, 21 ... Body, 21V ... Internal space, 22 ... Development roller, 23 ... Development blade, 24 ... Supply roller, 25A, 25B ... Stirring member, 26 ... Toner amount detector, 27 ... First toner transfer spiral, 28 ... Second toner transfer Spiral, 29 ... Input port, 60 ... Shutter unit, 61 ... 1st shutter member, 611 ... 1st shaft, 612 ... 2nd shaft, 613 ... 1st flat plate, 614 ... Lever, 615 ... Spring, 62 ... 2nd Shutter member, 621 ... Grip portion, 622 ... Second flat plate portion, 623 ... First contact portion, 624 ... Second contact portion, 631 ... First rotation angle regulating portion, 631S ... First contact surface, 632 ... 2nd rotation angle regulating part, 632S ... 2nd contact surface, 70 ... guide member, 71 ... guide part, 72 ... holding part, 100 ... shutter unit, 101 ... first shutter member, 102 ... second shutter member, 103 ... 1st shaft, 104 ... 2nd shaft 104, 105 ... 1st flat plate portion, 106 ... spring, 107 ... lever, 108 ... 1st rotation angle regulating portion, 109 ... gripping portion, 110 ... 2nd flat plate portion, 111 ... Second rotation angle regulating unit, 130 ... image forming unit, 170 ... guide member, 171 ... first guide unit, 172 ... holding unit, 173 ... second guide unit.

Claims (19)

An image carrier including an image-carrying surface capable of carrying a developer image,
A main body that holds the image carrier so that a part of the image carrier is exposed,
A first shutter member that is rotatably held about the first rotation axis with respect to the main body and includes a first inner surface, and the first rotation axis with respect to the first shutter member. It has a second inner surface, a first contact portion, and a second shutter member including a second contact portion while being rotatably held about a second rotation axis parallel to the second rotation axis. A closed state in which the first shutter member and the second shutter member are deployed so that the first inner surface and the second inner surface cover the image-bearing surface, and the first inner surface and the second. A shutter unit capable of shifting to an open state in which the first shutter member and the second shutter member are folded so that the inner surfaces of the image-bearing surface are exposed.
The image is supported by the main body in a peripheral region other than the effective image forming region facing the image-carrying surface, and the image is supported while being in contact with the first contact portion at the time of transition between the closed state and the open state. A first guide portion that regulates the movement of the second shutter member in a direction away from the surface, and
An image forming unit provided with a holding portion that is supported by the main body in the peripheral region and that abuts on the second contact portion to hold the open state of the shutter unit. The first shutter member includes a first contact surface and includes a first contact surface.
The second shutter member includes a second contact surface that contacts the first contact surface in the closed state.
When the first contact surface and the second contact surface come into contact with each other in the closed state, the angle formed by the second shutter member with respect to the first shutter member is regulated. The image forming unit according to claim 1. In the cross section orthogonal to the first axis of rotation,
Claim 1 or claim 2 in which the first distance between the first rotation shaft and the first guide portion is wider than the second distance between the first rotation shaft and the second rotation shaft. The image forming unit described in. In the cross section orthogonal to the first axis of rotation,
The image forming unit according to claim 3, wherein the third distance between the image-supporting surface and the guide portion is wider than the fourth distance between the image-supporting surface and the first rotation axis. In the cross section orthogonal to the first axis of rotation,
The first length from the first rotation axis to the second rotation axis in the first shutter member is the same as the second rotation axis from the second rotation axis in the second shutter member. The image forming unit according to any one of claims 1 to 4, which is shorter than the second length to the tip on the opposite side. The image forming unit according to any one of claims 1 to 5, wherein the first guide portion is separated from the first contact portion in the open state. Claimed from claim 1, in which the first shutter member and the second shutter member are interlocked with each other to perform a rotation operation as the first rotation shaft rotates at the time of the state transition. Item 6. The image forming unit according to any one of items 6. At the time of the state transition, the first shutter member rotates in the first rotation direction with respect to the main body, and the second shutter member rotates with respect to the first shutter member in the direction opposite to the first rotation direction. The image forming unit according to claim 7, which rotates in the second rotation direction of the above. In the cross section orthogonal to the first axis of rotation,
The image forming unit according to any one of claims 1 to 8, wherein the shutter unit is such that the state transition is performed without protruding from the region overlapping the main body. Any one of claims 1 to 9, wherein the second inner surface of the second shutter member has a protrusion that can come into contact with the peripheral region that is out of the effective image forming region of the image-carrying surface. The image forming unit described in the section. A second guide portion supported by the main body in the peripheral region is further provided.
The second shutter member further includes a third contact portion.
The second guide portion is the third hit after the first contact portion and the first guide portion are in contact with each other at the time of transition between the closed state and the open state. The image forming unit according to claim 1, wherein the image forming unit comes into contact with the contact portion and restricts the movement of the second shutter member in a direction away from the image-supporting surface. The second guide portion abuts on the third contact portion and guides the third contact portion when the state shifts from the closed state to the open state, thereby guiding the second contact portion. The image forming unit according to claim 11, wherein the inner surface is brought closer to the first inner surface. The first shutter member further includes a first outer surface opposite to the first inner surface.
The second shutter member further includes a second outer surface opposite to the second inner surface.
The image forming unit according to claim 11 or 12, wherein the third contact portion includes a protruding portion protruding in the opposite direction to the second inner surface on the second outer surface. At the time of transition from the closed state to the open state
The first contact portion passes outside the holding portion, which is opposite to the image carrier when viewed from the holding portion.
The third contact portion comes into contact with the second guide portion after the first contact portion passes outside the holding portion.
The second contact portion is any one of claims 11 to 13, wherein the third contact portion contacts the second guide portion and then contacts the holding portion. The image forming unit according to item 1. The first shutter member includes a first flat plate portion and a first opening portion.
The second shutter member includes a second flat plate portion and a second opening portion.
According to claim 11, the shutter unit is folded so that the first flat plate portion is housed in the second opening and the second flat plate portion is housed in the first opening in the closed state. Item 3. The image forming unit according to any one of items 13. The second shutter member is rotatably held by the first shutter member on the second rotation axis.
In the second shutter member, the first contact portion is provided between the second contact portion and the second rotation shaft, and the third contact portion is the second contact portion. The image forming unit according to any one of claims 11 to 15, which is provided between the contact portion and the first contact portion. The image forming unit according to any one of claims 1 to 16, wherein in the open state, the second contact portion is held by the holding portion so as to ride on the holding portion. An image forming apparatus including the image forming unit according to any one of claims 1 to 17. The image forming apparatus according to claim 18, wherein the developer image is transferred to the medium when the image-carrying surface comes into direct contact with the medium.

Images