JP2009139393A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize an image forming apparatus securing strength of a frame without reducing assembling workability. <P>SOLUTION: A scanner substrate 40 for electrical connection with a scanner unit 3 is provided to a left sidewall 31 opposing to a left frame 32a of a scanner unit 3 body so that the sum of the length L4 of the scanner unit 3 body and the length L5 of a second protrusion 38b is longer than the length L6 between the left frame 32a and a right frame 32b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine, a printer, a facsimile, and a composite device thereof.

  2. Description of the Related Art Conventionally, it is desirable that an electrophotographic image forming apparatus has a configuration in which various parts, particularly electrical parts, can be removed as easily as possible when they fail. This is because, when an electrical component causing a failure is specified, the failed component is replaced by a service person in the market. In Patent Document 1, after temporarily holding the scanner unit by the temporary holding member, the scanner unit is positioned while securing the strength of the frame by the opening and closing member, and the market interchangeability is very good.

The electrical connection from the image forming apparatus to the scanner unit is connected from the side surface of the image forming apparatus by a bundle line connected to a control board provided in the image forming apparatus.
JP 2003-248367 A

  In recent years, there has been a demand for smaller image forming apparatuses than ever before. It is particularly desired to reduce the height of the discharge unit on which the image-formed sheets are stacked. When the vertical tandem method described in Patent Document 1 is further reduced in size, particularly in order to reduce the height of the discharge unit provided at the upper part of the apparatus, the scanner units arranged in parallel in the vertical direction (up and down) Further, it is conceivable to reduce the interval between the photosensitive drums.

  FIG. 8 is a schematic perspective view showing the frame 130 of the vertical tandem image forming apparatus and the scanner unit 103 attached to the frame 130.

  When the distance between the scanner units 103 is reduced due to the downsizing of the image forming apparatus, the distance between the holes of the frame body 130 opened to pass the bundled wire electrically connected from the image forming apparatus to the scanner unit 103 is also reduced. End up.

  Also, the scanner unit 103 itself is downsized as the image forming apparatus is downsized.

  However, since the size of the sheet S does not change, the distance between the side plates 132a and 132b constituting the frame body 130 hardly changes. For this reason, the bundle connection position 140 of the scanner unit 103 is in a direction away from the side plate 132a.

  When the bundle connection position 140 of the scanner unit 103 moves to the center side of the image forming apparatus, when connecting the bundle line to the scanner unit 103, the assembling operator will be in contact with the scanner unit 103 in the size of the hole in the bundle path so far. The bundled wires cannot be connected. For this reason, it is necessary to connect the bundled wire to the scanner unit 103 by enlarging the hole 139 or using a special tool.

  As described above, when the interval between the holes is narrow and the holes are enlarged, the holes are connected to form one large hole. In this case, since a large hole is opened in the frame body 130, there is a concern about a decrease in the frame body strength of the image forming apparatus.

  When connecting the bundled wire to the scanner unit 103 using a special tool, the assembly workability at the time of manufacture is deteriorated, and each serviceman is asked to connect the scanner bundled wire when the scanner unit 103 is replaced on the market. There is a concern that the need to provide

  The present invention has been made in view of the circumstances as described above, and it is an object of the present invention to ensure the strength of the frame and reduce the size of the image forming apparatus without degrading the assembly workability.

In order to achieve the above object, the present invention provides:
An exposure unit for exposing a rotatable image carrier;
A first frame and a second frame which are provided opposite to each other and hold the exposure unit;
With
A first protrusion provided to protrude from the main body of the exposure unit toward the first frame body and a first hole provided in the first frame body are engaged,
By engaging a second protrusion provided to protrude from the main body of the exposure unit toward the second frame, and a second hole provided in the second frame,
In the image forming apparatus in which the exposure unit is held by the first frame and the second frame,
Of the main body of the exposure unit, a portion facing the first frame body is provided with a connection portion for electrical connection with the exposure unit,
The sum of the length of the main body of the exposure unit and the length of the second protrusion in the rotation axis direction of the image carrier is the distance between the first hole and the second hole in the rotation axis direction. It is characterized by being longer.

  According to the present invention, it is possible to ensure the strength of the frame and to reduce the size of the image forming apparatus without reducing the assembling workability.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the invention is applied and various conditions. It is not intended to limit the scope to the following embodiments.

(overall structure)
FIG. 1 is a longitudinal sectional view showing an overall configuration of a full-color laser beam printer (hereinafter, printer) A which is an embodiment of an image forming apparatus (multicolor image forming apparatus) to which the present invention can be applied.

  The printer A has four photosensitive drums 1 (1a to 1d) that can rotate as image carriers. Around each photosensitive drum 1, the charging unit 2 (2a to 2d), the exposure unit 3 (3a to 3d), the developing unit 4 (4a to 4d), and the transfer member 5 (5a to 5d) are sequentially arranged according to the rotation direction. The cleaning means 6 (6a to 6d) and the like are arranged to constitute an image forming means.

Here, the charging means 2 (2a to 2d) charges the surface of the photosensitive drum 1 uniformly. Further, the exposure means (hereinafter referred to as scanner unit) 3 (3a to 3d) irradiates a laser beam on the basis of image information to form an electrostatic latent image on the photosensitive drum 1, and constitutes an exposure unit. ing. Further, the developing means 4 (4a to 4d) is for visualizing the toner image by attaching toner to the electrostatic latent image. The transfer member 5 (5a to 5d) is for transferring the toner image on the photosensitive drum 1 to the sheet S. The cleaning means 6 (6a to 6d) removes the post-transfer toner remaining on the surface of the photosensitive drum 1 after the transfer.

  Further, the photosensitive drum 1, the charging unit 2, the developing unit 4 and the cleaning unit 6 are integrally formed as a cartridge to form a process cartridge 7 (7a to 7d).

  The sheet S fed from the feeding unit 8 is conveyed to an image forming unit (image forming unit) by a conveying unit 9 constituted by a transfer conveying belt 9a, and a toner image of each color is sequentially transferred to form a multicolor image. Then, the fixing unit 10 heats and fixes the image. The sheet S heat-fixed by the fixing unit 10 is discharged and stacked on the discharge unit 13 by the discharge roller pair 12.

  In double-sided recording, the sheet S fixed by the fixing unit 10 is conveyed to the double-sided conveyance path 15 by reversely rotating the discharge roller pair 12 before being completely discharged by the discharge roller pair 12. (Direction of arrow B). The sheet S conveyed to the double-sided conveyance path 15 passes through the oblique feeding roller 16 on the front surface of the apparatus main body and is conveyed vertically (vertically) downward to the U-turn roller 17, and an image is formed by the U-turn roller 17 and the registration roller 8 d. It is conveyed to the forming means.

(Feeding department)
The feeding unit 8 includes a feeding cassette 8a, a manual feeding tray 8b, a manual feeding unit 8c, and a registration roller 8d. The feeding cassette 8a stores a plurality of sheets S and is loaded on the bottom of the apparatus main body. When forming an image from the feeding cassette 8a, the sheets S are separated and fed one by one by the cassette pickup roller 8a1, and conveyed to the conveying means 9 by the cassette conveying roller 8a2 and the registration roller 8d.

  The manual feed tray 8b is normally stored in front of the apparatus main body, but is rotated and opened from the apparatus main body when used, and a plurality of sheets S are stacked. When forming an image from the manual feed tray 8b, the sheets S are separated and fed one by one by the manual pickup roller 8c1, and conveyed to the conveying means 9 by the manual conveyance roller 8c2 and the registration roller 8d.

  Separation and conveyance of the sheet S in the feeding cassette 8a and the manual feeding unit 8c are performed by a feeding motor (not shown) in the feeding unit 8 via a gear drive train.

(Image forming part)
The photosensitive drum 1 as an image carrier is configured by applying an organic photoconductor layer (OPC) to the outer peripheral surface of an aluminum cylinder. Both ends of the photosensitive drum 1 are rotatably supported by flanges, and a driving force is transmitted to one end from a driving motor (not shown), thereby rotating counterclockwise in FIG. Driven by rotation.

  The charging unit 2 is a conductive roller formed in a roller shape. The charging unit 2 is brought into contact with the surface of the photosensitive drum 1 and a charging bias voltage is applied by a power source (not shown) to It is charged uniformly.

  The scanner unit 3 has a polygon mirror. The polygon mirror is irradiated with image light corresponding to an image signal from a laser diode (not shown).

The developing means 4 (4a to 4d) includes toner storage portions 4a1 to 4d1, developing rollers 4a2 to 4d2, and the like. Here, the toner storage units 4a1 to 4d1 store toners of black, cyan, magenta, and yellow, respectively. Developing roller 4a2-4d
No. 2 is adjacent to the surface of the photosensitive drum, is driven to rotate by a driving unit (not shown), and performs a developing operation when a developing bias voltage is applied from a developing bias power source (not shown).

  In addition, transfer members 5a to 5d that are in contact with the transfer and transport belt 9a are provided adjacent to the four photosensitive drums 1a to 1d, respectively, inside a transfer and transport belt 9a described later. These transfer members 5a to 5d are connected to a transfer bias power source (not shown). Then, a positive charge is applied from the transfer members 5a to 5d to the sheet via the transfer conveyance belt 9a, and each negative color on the photosensitive drum 1 is applied to the sheet S in contact with the photosensitive drum 1 by this electric field. The toner images are sequentially transferred to form a multicolor image.

(Sheet conveying means)
The sheet S fed from the feeding unit 8 is conveyed by the conveying unit 9 to an image forming area (image forming unit). A transfer conveyance belt 9a as a sheet carrier constituting the conveyance means 9 is stretched and supported by four rollers including a driving roller 9b and driven rollers 9c to 9e, and is arranged to face all the photosensitive drums 1a to 1d. It is installed.

  The transfer conveyance belt 9 a is circulated and moved by a driving roller 9 b so as to electrostatically attract the sheet S to the outer peripheral surface facing the photosensitive drum 1 and bring the sheet S into contact with the photosensitive drum 1. Thus, the sheet S is conveyed to the transfer position by the transfer conveyance belt 9a, and the toner image on the photosensitive drum 1 is transferred.

  In addition, an adsorption roller 9f that holds the sheet S together with the transfer conveyance belt 9a and attracts the sheet S to the transfer conveyance belt 9a is disposed at the most upstream position of the transfer conveyance belt 9a. When transporting the sheet, an electric field is formed between the opposing driven rollers 9c by applying a voltage to the suction roller 9f, and dielectric polarization is generated between the transfer transport belt 9a and the sheet S. The electrostatic attraction force is generated in both of them.

(Fixing part)
The fixing unit 10 applies heat and pressure to the image formed on the sheet S to fix the toner image, and includes a fixing belt 10a and an elastic pressure roller 10b.

  The fixing belt 10a is a cylindrical belt having an electromagnetic induction heat generating layer, and is guided by a belt guide member 10c having a built-in magnetic field generating means including an exciting coil and a T-shaped magnetic core. The elastic pressure roller 10b sandwiches the fixing belt 10a, and forms a fixing nip portion N having a predetermined width with a predetermined pressure contact force with the belt guide member 10c.

  The elastic pressure roller 10b is rotationally driven by a driving means (not shown), and the cylindrical fixing belt 10a rotates accordingly, and electromagnetic induction heat generation of the fixing belt 10a is performed by feeding power from an excitation circuit (not shown) to the excitation coil.

  In a state where the fixing nip portion N rises to a predetermined temperature and is adjusted in temperature, the sheet S on which an unfixed toner image is formed is conveyed from the image forming portion and introduced into the fixing nip portion N. At this time, the sheet S on which the unfixed toner image is formed is introduced between the fixing belt 10a and the elastic pressure roller 10b in the fixing nip portion N with the image surface facing upward, that is, facing the fixing belt surface. Then, the sheet S is nipped and conveyed through the fixing nip N so that the image surface is in close contact with the outer surface of the fixing belt 10a and the sheet S is moved (conveyed) together with the fixing belt 10a.

In the process where the sheet S is nipped and conveyed through the fixing nip N together with the fixing belt 10a, the fixing belt 10a is heated by electromagnetic induction heat generation, and the unfixed toner image on the sheet S is heated and fixed.

  The sheet S on which the toner image is fixed is discharged and stacked on the discharge unit 13 by the discharge roller pair 12.

(Scanner unit mounting part)
Next, attachment of the scanner unit 3 to the frame 30 as the frame of the printer A will be described with reference to FIG. FIG. 2 is a schematic perspective view showing the frame 30 of the printer A, and shows a state in which only one scanner unit 3 is arranged on the uppermost stage. 2 shows the state of the frame 30 in a state where the printer A is installed. In the following description, the left and right sides are referred to for convenience in the state of the frame 30 shown in FIG.

  The photosensitive drum 1 is positioned by drum positioning portions 34a to 34h provided in a left frame 32a as a first frame and a right frame 32b as a second frame.

  Here, the left frame 32a and the right frame 32b are provided to face each other. A central frame 36 is provided between the left frame 32a and the right frame 32b, and the left frame 32a, the right frame 32b, and the central frame 36 are provided on the upper surface of the lower frame 33. A frame 30 is configured.

The scanner unit 3 is photosensitive when projections 38a and 38b projecting from the side wall of the scanner unit 3 main body are engaged with holes 35a to 35h provided in the left frame 32a and the right frame 32b constituting the frame 30. It is attached at a position facing the body drum 1. Here, the protrusion 38a constitutes a first protrusion provided so as to protrude from the scanner unit 3 main body (exposure unit main body) toward the left frame 32a. The protrusion 38b constitutes a second protrusion provided so as to protrude from the main body of the scanner unit 3 toward the right frame 32b. Moreover, the hole parts 35a-35d comprise the 1st hole, and the hole parts 35e-35h comprise the 2nd hole. The side wall of the scanner unit 3 main body refers to a portion of the scanner unit 3 that faces the left frame 32a and a portion of the scanner unit 3 that faces the right frame 32b. Among these, the side wall facing the left frame 32 a of the scanner unit 3 is referred to as the left side wall 31.

  In the scanner unit 3, a protrusion 38 c protruding from the main body of the scanner unit 3 is engaged with a hole 37 provided in the central frame 36.

  The electrical connection (electrical connection) between the printer A and the scanner unit 3 is performed by connecting a bundle line connected to an electric board 44 provided under the frame 30 to a left side wall 31 of the scanner unit 3 main body. It is performed by being connected to the scanner substrate 40 as a. More specifically, the bundled wire connected to the electric board 44 is connected to a connector provided on the scanner board 40, whereby the printer A and the scanner unit 3 are electrically connected.

  In the present embodiment, the scanner substrate 40 is provided on the left side wall 31 of the main body of the scanner unit 3 facing the left frame 32a. At this time, the bundle wire connected to the electric board 44 provided under the frame 30 is connected to the scanner board 40 through the bundle work holes 39a to 39d provided in the left frame 32a.

  Next, a case where the scanner unit 3 is downsized will be described.

FIG. 3 is a diagram showing a further miniaturized version of the scanner unit and frame shown in FIG.

  When the scanner unit 3 is downsized, the size of the sheet S on which an image is formed (passed through) does not change, so the relative position between the left frame 32a and the right frame 32b, that is, the left frame 32a and the right frame 32b. The length (distance) between and does not change. Accordingly, the projections 38a and 38b to which the scanner unit 3 is attached are not miniaturized, and are arranged in an engaged state (inserted) with respect to the holes 35a to 35h as in FIG.

  However, the other parts are reduced in size, and the left and right side walls of the scanner unit 3 move toward the center of the frame body. As the side wall of the scanner unit 3 moves, the scanner substrate 40, which is an electrical connection with the printer A, also moves toward the center of the frame body.

  In the printer before the downsizing, the bundled wire connection hole can be connected with the length L of the bundled wire working hole 39a. However, since the scanner substrate 40 is moved to the center side of the frame body by the downsizing, the bundled wire working hole 39a. If this is the case, it will be difficult to connect the bundled wires.

  Therefore, it is necessary to make the bundling work hole 39a have a larger length L1 (L <L1) so that the connection can be made at a deeper position (center side of the frame body).

  In this case, it is necessary to enlarge other bundling work holes simultaneously with the expansion of the bundling work holes 39a. Depending on the size of the bundling work holes 39a, the bundling work holes 39a may be connected to other bundling work holes. There is concern about the decline.

  In order to avoid this, when the bundling work hole 39a is not enlarged, it is conceivable to connect the bundling using a special tool, but the assembling workability is lowered.

  Therefore, in this embodiment, the scanner unit 3 is provided close to the bundling work hole 39a of the left frame 32a in order to reduce the size of the printer without reducing the assembling workability.

  FIG. 4 is a schematic cross-sectional view showing the scanner unit and the frame shown in FIG. 3, and shows a state in which the scanner unit 3 is brought close to the bundling work hole 39a of the left frame 32a. FIG. 7 is a schematic diagram showing a state where the scanner unit is simply miniaturized as a comparative example.

  Normally, when the scanner unit 3 is brought close to the bundling work hole 39a of the left frame 32a, the first protrusion 38a and the first hole 35a remain engaged, but the second protrusion 38b and the second hole 35b is not engaged when the second protrusion 38b is separated from the second hole 35b. In this state, the fulcrum of the scanner unit 3 disappears, and the scanner unit 3 may fall (FIG. 7).

  In order to prevent this, a holding member may be added in the vicinity of the second protrusion 38b or the like, but in such a case, extra cost is required.

On the other hand, in this embodiment, when the scanner unit 3 is assembled to the frame 30, the length L2 to the side wall from which the left frame 32a and the first protrusion 38a protrude is equal to the right frame 32b and the second protrusion. It is provided to be shorter than the length L3 to the tip of 38b. That is, the sum of the length L4 of the main body of the scanner unit 3 and the length L5 of the second protrusion 38b is set to be longer than the length L6 between the left frame 32a and the right frame 32b. Here, the lengths L2, L3, L4, L5, and L6 indicate the length of the photosensitive drum 1 in the rotation axis direction. Further, the length L6 between the left frame 32a and the right frame 32b of the present embodiment is a distance in the rotation axis direction of the photosensitive drum 1 between the hole 35a and the hole 35e. In the present embodiment, the left frame 32 a and the right frame 32 b are substantially orthogonal to the rotation axis direction of the photosensitive drum 1.

  Thus, in this embodiment, even when the length of the second protrusion 38b is in contact with the left frame 32a, the engagement state with the second hole 35b is maintained (released). Is not)) length.

  Therefore, even when the scanner unit 3 is brought close to (moved to) the bundling work hole 39a of the left frame 32a, the scanner unit 3 is engaged with the first protrusion 38a and the first hole 35a, and The second protrusion 38b and the second hole 35b are continuously held. For this reason, the holding member as described above is not necessary.

  As described above, the scanner substrate 40 can be brought close to (moved to) the left frame 32a during the assembly work, so that it is not necessary to increase the size of the bundling work hole 39a as described above to L1.

  Furthermore, by providing the scanner unit 3 so that the scanner substrate 40 is positioned closer to the left frame 32a, it is possible to make L1 smaller than L, and the frame rigidity without increasing the cost even if the image forming apparatus is downsized. Assembly workability can be improved while maintaining In other words, it is possible to provide an image forming apparatus that ensures the frame rigidity even when the image forming apparatus is miniaturized and is easy to assemble at the time of assembly or market replacement.

  In this embodiment, four scanner units 3 are used in parallel. However, the present invention is not limited to this, and two scanner units may be provided in the printer. Corresponding to the provision of a plurality of photosensitive drums, a plurality of scanner units may be provided. However, a single scanner unit may be provided in the printer.

  Further, the left frame 32a and the right frame 32b may be configured integrally with the same component.

  In the present embodiment, the case where the left frame 32a and the right frame 32b are provided so as to be substantially orthogonal to and substantially parallel to the rotation axis direction of the photosensitive drum 1 has been described. It is not limited to. When the left frame 32a and the right frame 32b are not substantially perpendicular to the rotation axis direction of the photosensitive drum 1, the lengths L2, L3, L4, L5, and L6 described above are set to the rotation axis of the photosensitive drum 1. The length of the direction may be used. The length L6 described above may be the distance in the rotation axis direction of the photosensitive drum 1 between the hole 35a and the hole 35e. That is, the sum of the length L4 of the main body of the scanner unit 3 and the length L5 of the second protrusion 38b in the direction of the rotation axis of the photosensitive drum 1 is greater than the length L6 between the hole 35a and the hole 35e. Should be longer.

  Further, in the present embodiment, the connection portion for connecting the bundled wires has been described, but the present embodiment can also be suitably applied to the adjustment portion for adjusting the laser of the scanner unit 3 and the cover attachment portion after the laser adjustment. Can do.

  The second embodiment of the present invention will be described below.

FIG. 5 is a schematic cross-sectional view showing the scanner unit and the frame of this embodiment. In the present embodiment, different components from the first embodiment will be described.
The description of the same components as in FIG.

  In the first embodiment described above, when the electrical connection between the scanner unit 3 and the electrical board 44 of the printer A is performed, if the bundle is connected to the scanner board 40 in advance, the bundle is connected. In this state, the scanner unit 3 must be incorporated into the printer A. In such a case, there is a concern that the workability due to the bundled wires connected to the scanner unit 3 may be reduced, the bundled wires may be damaged, or the bundled wire connection may be uncertain. .

  For this reason, during normal assembly work, whether the bundled wire is connected to the scanner substrate 40 of the scanner unit 3 and then connected to the electric substrate 44, or the bundled wire originally connected to the electric substrate 44 is connected to the scanner substrate 40 Either.

  At this time, in the state of the first embodiment, the scanner unit 3 is in a state in which the first protrusion 38a and the second protrusion 38b are engaged with the first hole 35a and the second hole 35b, respectively. It has become. Therefore, if the bundled wire is to be connected to the scanner substrate 40 as it is, the scanner unit 3 is not fixed. Therefore, the scanner unit 3 loses the connection force (operating force) applied by the operator when the bundled wire is connected. Concern about moving. In such a case, there is a concern that the workability may be deteriorated because it is necessary to connect the bundled wires while pressing the scanner unit 3.

  In order to prevent this, in this embodiment, the scanner unit 3 is provided with stoppers 43a and 43b as restricting portions so that the stopper 43a contacts the left frame 32a and the stopper 43b contacts the right frame 32b when the bundled wires are connected. . The stopper 43a and the stopper 43b only need to be in contact with the left frame 32a and the right frame 32b, respectively, when the bundled wires are connected. However, when the scanner unit 3 is installed at a predetermined installation position, that is, at the time of image formation. You may provide so that it may contact.

  With such a configuration, when the bundle is connected, the stopper 43a contacts the left frame 32a and the stopper 43b contacts the right frame 32b. Therefore, the movement of the scanner unit 3 to the right frame 32b side (second frame side) is restricted. can do. In this way, the movement of the scanner unit 3 can be restricted against the connection force when connecting the bundled wires, and the bundled wires can be connected smoothly.

  Similarly to the first embodiment, since the scanner substrate 40 is close to the left frame 32a, the size of the bundling work hole 39a can be reduced, and the frame body rigidity can be increased without increasing the cost even if the image forming apparatus is downsized. Workability can be improved while maintaining.

  Example 3 of the present invention will be described below.

  FIG. 6 is a schematic cross-sectional view showing the scanner unit and the frame of this embodiment. In the present embodiment, the different components from the first embodiment will be described, and the description of the same components as those in the first embodiment will be omitted.

  In the above-described first embodiment, when the printer A is further reduced in size, it is conceivable to move the electric board 44 arranged on the lower side of the scanner unit 3. As a place where the electric board 44 is moved, the side surface side of the left frame 32a or the right frame 32b can be considered in order to reduce the height of the printer body.

  However, considering the electrical connection with the scanner unit 3, it is desirable to move to the left frame 32a side where the connection length of the bundled wires can be shortened.

  Therefore, in this embodiment, as shown in FIG. 6, the electric board 44 is disposed on the left frame 32a side.

  With such a configuration, the printer A can be made smaller than in the first and second embodiments.

  In the present embodiment, the electric board 44 is disposed on the left frame 32a side, but the connector (connection portion) of the electric board 44 is provided in the vicinity of the left frame 32a (near the first frame). If it is. Thereby, the connection length of the bundled wire between the electric board | substrate 44 and the scanner unit 3 can be shortened.

1 is a schematic cross-sectional view showing an overall configuration of an image forming apparatus to which the present invention can be applied. Schematic for demonstrating attachment to the flame | frame of the scanner unit in Example 1 of this invention. Schematic which shows the state which reduced the scanner unit and flame | frame shown in FIG. FIG. 4 is a schematic sectional view showing a scanner unit and a frame shown in FIG. 3. FIG. 5 is a schematic cross-sectional view illustrating a scanner unit and a frame according to a second embodiment of the present invention. FIG. 6 is a schematic cross-sectional view showing a scanner unit and a frame according to a third embodiment of the present invention. Schematic which shows a comparative example in Example 1. FIG. Schematic which shows a prior art example.

Explanation of symbols

1a, 1b, 1c, 1d Photosensitive drum (image carrier)
3a, 3b, 3c, 3d Scanner unit (exposure unit)
31 Left side wall 32a Left frame (first frame)
32b Right frame (second frame)
35a, 35b, 35c, 35d Hole (first hole)
35e, 35f, 35g, 35h Hole (second hole)
38a Protrusion (first protrusion)
38b Protrusion (second protrusion)
40 Scanner board A Image forming device

Claims (4)

An exposure unit for exposing a rotatable image carrier;
A first frame and a second frame which are provided opposite to each other and hold the exposure unit;
With
A first protrusion provided to protrude from the main body of the exposure unit toward the first frame body and a first hole provided in the first frame body are engaged,
By engaging a second protrusion provided to protrude from the main body of the exposure unit toward the second frame, and a second hole provided in the second frame,
In the image forming apparatus in which the exposure unit is held by the first frame and the second frame,
Of the main body of the exposure unit, a portion facing the first frame body is provided with a connection portion for electrical connection with the exposure unit,
The sum of the length of the main body of the exposure unit and the length of the second protrusion in the rotation axis direction of the image carrier is the distance between the first hole and the second hole in the rotation axis direction. An image forming apparatus characterized in that it is longer.   2. The control unit according to claim 1, wherein at least one of the first protrusion and the second protrusion includes a restricting portion that restricts the movement of the exposure unit toward the second frame. Image forming apparatus.   3. The image forming apparatus according to claim 1, wherein a connection portion of an electric substrate that is electrically connected to the exposure unit is provided in the vicinity of the first frame body. A plurality of the image carriers are provided,
4. The exposure unit according to claim 1, wherein a plurality of the exposure units are provided on the first frame and the second frame corresponding to the plurality of image carriers. The image forming apparatus described in 1.

Images