Image forming apparatus

An image forming apparatus includes a first frame member and a second frame member which are aligned in a direction of a rotation axis of an image bearing member and faces each other across an image forming unit and a stacking unit. The first frame member includes a first portion including a first side surface facing the image forming unit and a second portion, which is fixed to the first portion, including a second side surface facing the stacking unit. The second frame member includes a third side surface facing the image forming unit and the stacking unit, and at least a part of the second side surface is provided in a position different from a position of the first side surface in the direction of the rotation axis of the image bearing member.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an image forming apparatus using an electrophotographic method, such as a laser beam printer (LBP), a copying machine, a facsimile machine, and the like.

Description of the Related Art

A frame structure of an image forming apparatus that uses two side plates facing each other across a photosensitive member is known, as discussed in Japanese Patent Application Laid-Open No. 2009-128506. In an image forming apparatus having the frame structure including two side plates, an image forming unit including a photosensitive member and a stacking unit (sheet feeding cassette) that is attachable to and detachable from a main body of the image forming apparatus and on which sheets to be conveyed to the image forming unit are stacked are provided between the two side plates.

Meanwhile, the distance between the two side plates is generally determined by a length of the widest object among members provided between the two side plates.

For example, in a case of a configuration in which a tray supporting a cartridge is provided and the tray can be inserted and removed as discussed in Japanese Patent Application Laid-Open No. 2009-128506, the tray and a tray insertion/removal mechanism need to be provided between the two side plates. However, the smallest width of the sheet feeding cassette is not always the same as the smallest width of the tray and the tray insertion/removal mechanism. Thus, if the distance between the two side plates is set to allow the tray, the tray insertion/removal mechanism, and the sheet feeding cassette to fit in the space between the two side plates, an empty space is formed in a portion between the two side plates and the tray and the tray insertion/removal mechanism or in a portion between the two side plates and the sheet feeding cassette. The empty space causes an excessive increase in the volume of the image forming apparatus, whereby it becomes difficult to reduce the size of the image forming apparatus.

SUMMARY OF THE INVENTION

The present invention is directed to providing an image forming apparatus that enables effective use of a space within the image forming apparatus in response to the above issue.

According to an aspect of the present invention, an image forming apparatus includes an image forming unit configured to transfer a toner image formed on an image bearing member onto a recording medium, a stacking unit on which a recording medium to be conveyed to the image forming unit is stacked, and, a first frame member and a second frame member which are aligned in a direction of a rotation axis of the image bearing member and face each other across the image forming unit and the stacking unit, wherein the first frame member includes a first portion and a second portion, the first portion including a first side surface facing the image forming unit, the second portion being provided separately from the first portion and including a second side surface facing the stacking unit, and the second portion is fixed to the first portion, wherein the second frame member includes a third side surface facing the image forming unit and the stacking unit, and the second frame member is an integrally-formed frame member, and wherein at least a part of the second side surface is provided in a position different from a position of the first side surface, in the direction of the rotation axis of the image bearing member.

According to another aspect of the present invention, an image forming apparatus includes an image forming unit configured to transfer a toner image formed on an image bearing member onto a recording medium, a stacking unit on which a recording medium to be conveyed to the image forming unit is stacked, and a first frame member and a second frame member which are aligned in a direction of a rotation axis of the image bearing member and face each other across the image forming unit and the stacking unit, wherein the first frame member includes a first portion and a second portion, the first portion including a first side surface facing the image forming unit, the second portion being provided separately from the first portion and including a second side surface facing the stacking unit, and the second portion is fixed to the first portion, wherein the second frame member includes a third side surface facing the image forming unit and the stacking unit, the first portion is formed of a metal, and the second portion is formed of a resin, and wherein at least a part of the second side surface is provided in a position different from a position of the first side surface in the direction of the rotation axis of the image bearing member.

DESCRIPTION OF THE EMBODIMENTS

(Entire Schematic Structure of Image Forming Apparatus)

An entire schematic structure of an image forming apparatus will be described.FIG. 1is an external perspective view illustrating an image forming apparatus100, andFIG. 2is a schematic cross sectional view illustrating the image forming apparatus100, viewed along a direction of a rotation axis of photosensitive drums1.

The image forming apparatus100is a full-color electrophotographic laser printer using four colors. The image forming apparatus100forms a toner image on a recording medium having a sheet shape (sheet) based on image signals input from an external host device (not illustrated), such as a personal computer, an image reader, a sender facsimile machine, and the like.

As used herein, the “front” of the image forming apparatus (also referred to as “main body”)100is a side on which a door31of the main body100is provided. The “back” is a side that is opposite to the “front.” The “left” is a left hand side of the main body100, viewed from the “front” side of the main body100, and the “right” is a right hand side of the main body100, viewed from the “front” side of the main body100.

In the main body100, four cartridges P (PY, PM, PC, PK) are aligned and attached in a substantially horizontal direction from the back to the front. The cartridges P have a similar structure each other, except that colors of contained toner are different from each other, and operate similarly. Each of the cartridges P includes a photosensitive drum (photosensitive member)1as a first image bearing member, a charging unit2, a development unit3, a cleaning unit4, and a frame5. The charging unit2, the development unit3, and the cleaning unit4are processing units that perform operations on the photosensitive drum1, and the frame5supports the photosensitive drum1and the processing units. When the cartridge P is attached to the main body100, the photosensitive drum1in the cartridge P is rotatably supported. The charging unit2includes a charging roller. The development unit3includes a development roller3a, and a developer agent (toner) is contained in the development unit3. The cleaning unit4includes a cleaning blade that is in contact with the photosensitive drum1.

The first cartridge PY contains yellow (Y) toner in the development unit3and forms a yellow toner image on a surface of the photosensitive drum1. The second cartridge PM contains magenta (M) toner in the development unit3and forms a magenta toner image on a surface of the photosensitive drum1. The third cartridge PC contains cyan (C) toner in the development unit3and forms a cyan toner image on a surface of the photosensitive drum1. The fourth cartridge PK contains black (K) toner in the development unit3and forms a black toner image on a surface of the photosensitive drum1.

Above the four cartridges P (PY, PM, PC, PK), there is provided a laser scanner unit11. The laser scanner unit11emits to each photosensitive drum1a laser light beam L modulated based on image information about each color that is input from an external host device. Each laser light beam L passes through an opening6formed in an upper surface of the frame5of each of the cartridges P and reaches the surface of the photosensitive drum1, and the surface of the photosensitive drum1is scanned and exposed with the laser light beams L.

Below the four cartridges P (PY, PM, PC, PK), there is provided a belt unit12. The belt unit12includes a belt13, which has flexibility and an endless shape as an intermediate transfer member (second image bearing member), a driving roller14, and a tension roller15. The belt13is wound and stretched tightly around the driving roller14and the tension roller15, and the driving roller14and the tension roller15circulate (rotate) the belt13. The driving roller14is provided in the back side of the main body100. The tension roller15is provided in the front side of the main body100. A rotation axis of the belt13, which is circulated (rotated), is a rotation axis of the driving roller14or the tension roller15. The rotation axes of the driving roller14and the tension roller15are parallel to a rotation axis of the photosensitive drum1.

A lower surface of the photosensitive drum1of each of the cartridges P is in contact with an upper surface of an upper path side of the belt13. On the inner side of the belt13, there are provided four primary transfer rollers17each facing the photosensitive drum1of corresponding cartridge P via the upper path side belt portion. The driving roller14is in contact with a secondary transfer roller22via the belt13.

Below the belt unit12, a sheet feeding unit18is provided. The sheet feeding unit18includes a sheet feeding cassette19, a sheet feeding roller60, a conveyor roller20, and a separation roller21. The sheet feeding cassette19is a stacking unit for storing and stacking recording mediums (sheets) S. The sheet feeding cassette19can be attached to or removed from the main body100by inserting or removing the sheet feeding cassette19into or from the front side of the main body100. The sheet feeding roller60and the conveyor roller20are conveying members for conveying a recording medium from the sheet feeding cassette19.

A fixing device23and a sheet discharge roller pair24are provided in an upper portion of the back side of the main body100. An upper surface of the main body100is a sheet discharge unit25. A fixing device23includes a fixing film assembly23aand a pressing roller23b. The sheet discharge roller pair24includes sheet discharge rollers24aand24b.

When the cartridges P are attached to the main body100, the frame5and the photosensitive drum1of each of the cartridges P are positioned in predetermined positions by a positioning unit (not illustrated) included in the main body100. In this state, a driving input unit of each of the cartridges P is joined to a driving mechanism52(refer toFIGS. 6A and 6B) included in the main body100, and an electrical contact of each of the cartridges P is electrically connected to a high-voltage power supply unit53(refer toFIGS. 6A and 6B). Thus, the photosensitive drum1and the processing units are ready to operate.

The cartridges P and the belt unit12correspond to the image forming unit for transferring toner images held on the photosensitive drums1and the belt13onto a recording medium. A recording medium stacked in the sheet feeding cassette19is conveyed to a secondary transfer unit (secondary transfer nip portion) between the secondary transfer roller22and the belt13in the image forming unit.

An image forming operation for forming a full-color image will be described. The photosensitive drums1of the first to fourth cartridges PY, PM, PC, and PK are rotated and driven at a predetermined control speed. The belt13is also rotated and driven at a speed corresponding to the speed of the photosensitive drums1. The laser scanner unit11is also driven. In synchronization with the driving, the charging roller2uniformly charges the surface of the photosensitive drum1in each of the cartridges P to a predetermined polarity/potential at predetermined control timing. The laser scanner unit11scans and exposes the surface of each photosensitive drum1with a laser light beam L modulated according to an image signal of each color. Consequently, an electrostatic latent image corresponding to the image signal of the corresponding color is formed on the surface of each photosensitive drum1. Then, the development roller3aattaches toner to the electrostatic latent image to form a toner image on the photosensitive drum1.

As a result of the foregoing electrophotographic image formation process operations, a toner image corresponding to a yellow component of a full-color image is formed on the photosensitive drum1of the cartridge PY, and the toner image is primary-transferred onto the belt13. Similarly, a magenta toner image corresponding to a magenta component of the full-color image is formed on the photosensitive drum1of the cartridge PM, and the magenta toner image is primary-transferred onto the belt13in such a manner that the magenta toner image is superimposed on the already-transferred yellow toner image. Similarly, a cyan toner image corresponding to a cyan component of the full-color image is formed on the photosensitive drum1of the cartridge PC, and the cyan toner image is primary-transferred onto the belt13in such a manner that the cyan toner image is superimposed on the already-transferred yellow and magenta toner images. Similarly, a black toner image corresponding to a black component of the full-color image is formed on the photosensitive drum1of the cartridge PC, and the black toner image is primary-transferred onto the belt13in such a manner that the black toner image is superimposed on the already-transferred yellow, magenta, and cyan toner images. Consequently, a full-color toner image of yellow, magenta, cyan, and black is formed on the belt13. The primary transfer of each toner image is caused by a primary transfer bias voltage applied to the corresponding primary transfer rollers17.

The toner remaining on the surface of the photosensitive drum1of each of the cartridges P after the primary transfer is removed from the surface of the photosensitive drum1by the cleaning unit4.

Meanwhile, the sheet feeding roller60is driven at predetermined control timing. This causes a sheet S, which is a recording medium, stacked on the sheet feeding cassette19to be separated from other sheets S, conveyed through the conveyor roller20, the separation roller21, and the pair of conveyor rollers61aand61b, and then introduced to a nip portion (secondary transfer nip portion) of the secondary transfer roller22and the belt13. Since a secondary transfer bias voltage is applied to the secondary transfer roller22, the four-color superimposed toner images on the belt13are collectively transferred onto a surface of the sheet S while the sheet S is nipped and conveyed through the nip portion.

The sheet S is separated from the surface of the belt13, introduced to the fixing device23, and heated and pressed by a fixing nip portion, whereby the toner image is fixed to the sheet S. Then, the sheet S exits the fixing device23and is discharged onto the sheet discharge unit25by the sheet discharge roller pair24.

The toner remaining on the surface of the belt13after the secondary transfer electrostatically adheres to the surface of the photosensitive drum1in a primary transfer portion of the cartridge PY and is removed by the cleaning unit4.

Replacement of each of the cartridges P will be described.FIGS. 3 and 4are perspective views each illustrating the image forming apparatus100. When each of the cartridges P is removed from the main body100, a door is opened first, and a handle35aof a tray35is exposed, as illustrated inFIG. 3. The tray35is a moving member movable while supporting each of the cartridges P. In the state illustrated inFIG. 3, the tray35is positioned inside the main body100, and then a user grips the handle35ato pull out the tray35so that the tray35is moved to a position outside the main body100, as illustrated inFIG. 4. When the tray35is positioned outside the main body100, each of the cartridges P can be removed from the tray35and replaced. When each of the cartridges P is attached to the main body100, the reverse operations of the foregoing operations may be performed.

The direction in which the tray35is moved is a direction that is orthogonal to the rotation axis direction (longitudinal direction of cartridge P) of the photosensitive drum1. Further, the tray35is only required to directly or indirectly support the photosensitive drums1. Specifically, the tray35may be configured to indirectly support the photosensitive drums1via the frames5of the cartridges P, or the tray35may be configured to directly support the photosensitive drums1.

FIG. 5is a perspective view illustrating a frame structure of the image forming apparatus100. Hereinafter, the axial direction (longitudinal direction of cartridge P) of the photosensitive drum1will be referred to as an X direction, and the vertical direction as a Z direction. The image forming apparatus100includes a first frame F1and a second frame F2as members included in a frame structure. The first frame F1is a first frame member on the right side of the main body100, and the second frame F2is a second frame member on the left side of the main body100. The image forming apparatus100further includes two stay members connecting the first and second frames F1and F2together. The first frame F1includes a right side plate (first portion)40aand a sheet feeding unit frame (second portion)40b, and the second frame F2includes a left side plate41. The two stay members are a basal plate42and a scanner stay43. Each of the right side plate40a, the sheet feeding unit frame40b, the left side plate41, the basal plate42, and the scanner stay43is a plate-shaped metallic member. The sheet feeding unit frame40bis a resin member. The right side plate40ais provided in a portion of the first frame F1facing the image forming unit (each of the cartridges P, belt unit12) in the X direction. The sheet feeding unit frame40bis provided in a portion of the first frame F1facing the sheet feeding cassette19in the X direction below the image forming unit.

In a state where the right side plate40aand the left side plate41are butted to the basal plate42and the scanner stay43in the X direction, the right side plate40aand the left side plate41are fixed to the basal plate42and the scanner stay43. The right side plate40aand the left side plate41are butted to the basal plate42and the scanner stay43in this way to determine the distance between the right side plate40aand the left side plate41in the X direction.

Positioning of the right side plate40aand the sheet feeding unit frame40bwill be described. The right side plate40aincludes two through holes44ain the X direction. The two holes44aare formed on the right side plate40aby stamping in the X direction. Further, the sheet feeding unit frame40bincludes two protruded portions (bosses)44bprotruding in the X direction toward the right side plate40a. The two protruded portions44bare respectively inserted in the two holes44ato determine the position of the sheet feeding unit frame40b, and the sheet feeding unit frame40bis fixed to the right side plate40a. The two protruded portions44bare respectively butted to inner surfaces of the two holes44ato determine the position of the sheet feeding unit frame40bwith respect to the right side plate40ain the Z direction and a direction orthogonal to the Z and X directions. As to the X direction, a butting portion (not illustrated) provided to the sheet feeding unit frame40bis butted to the right side plate40ato determine the position.

FIGS. 6A and 6Bare diagrams each illustrating the frame structure of the image forming apparatus100and members supported by the frame structure.FIG. 6Ais a front view, andFIG. 6Bis a top view. The cartridge P, the belt unit12, and the tray35are provided between the right side plate40aand the left side plate41. Further, the sheet feeding cassette19is provided between the sheet feeding unit frame40band the left side plate41.

The right side plate40aincludes a first side surface S1orthogonal to the X direction, and the driving mechanism52of the cartridge P is supported on a side (outer side) of the first side surface S1that is opposite to the cartridge P. The driving mechanism52is an image bearing member driving unit including a motor, a gear train, and the like, for rotating and driving the photosensitive drum1and the belt13.

The sheet feeding unit frame40bincludes two second side surfaces S2aand S2b, which are orthogonal to the X direction. The two second side surfaces S2aand S2bare provided in different positions in the X direction. The second side surface S2ais provided closer to the sheet feeding cassette19than the first side surface S1, and the second side surface S2bis provided on a side opposite to the sheet feeding cassette19, in the X-direction.

The sheet feeding unit frame40bsupports the sheet feeding cassette19in such a manner that the sheet feeding cassette19is movable to the side (inner side) of the second side surface S2athat faces the sheet feeding cassette19, and the sheet feeding unit frame40bsupports a guide unit (support unit)54aconfigured to guide the movement of the sheet feeding cassette19. A sheet feeding driving unit (conveying member driving unit)50is supported on the side (inner side) of the second side surface S2bthat faces the sheet feeding cassette19. The sheet feeding driving unit50includes a motor, a gear train, and the like, for driving conveying members (sheet feeding roller60and conveyor roller20), and the like, to cause the sheet feeding unit18to operate. Further, a power supply unit51is supported on the side (outer sides) of the second side surfaces S2aand S2bthat is opposite to the sheet feeding cassette19. The power supply unit51functions as a low-voltage power supply unit (primary power supply unit) configured to supply power to the image forming apparatus100.

A wall surface portion W is formed on the side of the second side surfaces S2aand S2bthat is opposite to the sheet feeding cassette19. The wall surface portion W protrudes in the X direction from the second side surfaces S2aand S2bto the side (outer side) that is opposite to the sheet feeding cassette19. The wall surface portion W is provided to surround the power supply unit51as viewed in the X direction, and the sheet feeding unit frame40bis a non-flammable resin member, whereby the wall surface portion W and the second side surfaces S2aand S2bfunction as a fireproof enclosure.

The left side plate41includes a third side surface S3orthogonal to the X direction and supports a high-voltage power supply unit (secondary power supply)53on the side (outer side) of the third side surface S3that is opposite to the cartridge P. The high-voltage power supply unit53converts low-voltage power supplied from the power supply unit51to high-voltage power by boosting a voltage and supplies a bias voltage to the cartridge P, the belt unit12, and the like. The left side plate41supports a rail (support unit)54bon the side (inner side) of the third side surface S3that faces the sheet feeding cassette19. The rail54bmovably supports the sheet feeding cassette19.

The basal plate42supports the belt unit12, and the scanner stay43supports the laser scanner unit11.

In the frame structure according to the present exemplary embodiment, the right side plate40ais provided in a portion A, which is a portion overlapping the image forming unit in the Z direction, and the sheet feeding unit frame40bis provided in a portion B, which is a portion overlapping the sheet feeding cassette19in the Z direction. Further, the positions of the second side surfaces S2aand S2bof the sheet feeding unit frame40bin the X direction are different from the position of the first side surface S1of the right side plate40a. In this structure, the width of a space between the first frame F1(right side plate40aand sheet feeding unit frame40b) and the second frame F2(left side plate41) in the X direction in the portion A can be set differently from the width in the portion B. Further, the second side surfaces S2aand S2bare provided in different positions in the X direction. In this structure, the width of the space between the first frame F1(right side plate40aand sheet feeding unit frame40b) and the second frame F2(left side plate41) in the X direction can be set differently also in the portion B.

As described above, the first frame F1includes a plurality of members (right side plate40aand sheet feeding unit frame40b) so that the first side surface S1and the second side surfaces S2aand S2bcan be provided in appropriate positions according to the widths of the members provided between the first frame F1and the second frame F2and the widths of the members supported by the first frame F1. Thus, each member can be provided in such a manner that a wasted space is less likely to be formed. Therefore, an excessive increase in the entire volume of the image forming apparatus100can be prevented.

A comparison between the present exemplary embodiment and comparative examples will be described.FIG. 7Ais a front view illustrating a frame structure and members supported by the frame structure according to a first comparative example.FIG. 7Bis a front view illustrating a frame structure and members supported by the frame structure according to a second comparative example.FIG. 8is a top view of the frame structure and the members supported by the frame structure according to the first comparative example.

According to the first and second comparative examples, a single right side plate40is provided as a first frame F1, and the right side plate40includes a single first side surface S1. In the structures according to the first and second comparative examples, the distance between the first side surface S1of the right side plate40and a third side surface S3of a left side plate41is determined by the width in the X direction of a portion A in which a tray35is provided. According to the first comparative example, since the width of a power supply unit in the X direction is wide, the width of the image forming apparatus in the X direction may become wide because the power supply unit51protrudes in the X direction.

Further, according to the second comparative example, for example, even if the width of a sheet feeding driving unit50in the X direction can be decreased, the distance between the first side surface S1and the third side surface S3is determined by the width of the portion A in the X direction. Therefore, a space C is formed between the first side surface S1and the sheet feeding driving unit50. Thus, it is difficult to reduce the size of the entire body of the image forming apparatus.

Furthermore, as in the first comparative example illustrated inFIG. 8, in also a case where the sheet feeding cassette19and the sheet feeding driving unit50have different widths from each other in the X direction, a space may be formed between the sheet feeding cassette19and the first side surface S1.

On the contrary, according to the present exemplary embodiment, since the first frame F1includes the right side plate40aand the sheet feeding unit frame40b, the second side surfaces S2aand S2bare provided in positions that are different from the position of the first side surface S1. Especially, the second side surface S2ais provided further inside than the first side surface S1(on the side closer to the sheet feeding cassette19), and the portion of the power supply unit51in which a relatively large component, such as a transformer, is provided is provided in the position facing the second side surface S2a, whereby the power supply unit51is prevented from protruding in the X direction. Further, the second side surface S2bis provided further outside than the first side surface S1(on the side opposite to the sheet feeding cassette19), and the sheet feeding driving unit50is provided in the position facing the second side surface S2b, whereby formation of an unnecessary space between the second side surface S2aand the sheet feeding cassette19is prevented. Accordingly, in the frame structure according to the present exemplary embodiment, formation of an unnecessary space is prevented and effective use of the space in the apparatus is enabled. The foregoing effect can be obtained, as long as at least a part of the second side surfaces (S2aand/or S2b) of the sheet feeding unit frame40bis provided in a position different from the first side surface S1in the X direction (a position closer to or farther from the third side surface S3than the position of the first side surface S1).

Further, according to the present exemplary embodiment, the left side plate41is a single integrally-formed member, and the third side surface S3of the left side plate41is used as a positioning reference for the basal plate42, the scanner stay43, the cartridges P, the belt unit12, and the sheet feeding unit18. Thus, the positioning of each member can be conducted with certain accuracy. Especially, it is possible to decrease the effect on the positioning accuracy in the X direction b the structure of the first frame F1which is divided in the right side plate40aand the sheet feeding unit frame40b.

Further, according to the first and second comparative examples, a member70including, for example, a shaft70aand a guide70bfor the sheet feeding cassette is attached to the right side plate40, as illustrated in the partial perspective view of the frame structure illustrated inFIG. 10. On the contrary, according to the present exemplary embodiment, the sheet feeding unit frame40bis made of resin so that a shaft56and a guide54for supporting gears of the sheet feeding driving unit50are integrated with the sheet feeding unit frame40b, as illustrated in the partial perspective view of the frame structure of the image forming apparatus illustrated inFIG. 9. Further, the wall surface portion W, which functions as a fireproof enclosure, is integrated with the sheet feeding unit frame40b. Therefore, the number of components can be decreased and assembly costs can be reduced.

A second exemplary embodiment will be described. The present exemplary embodiment is different from the first exemplary embodiment only in a part of the frame structure and the like, and the main structure of the image forming apparatus is similar to that of the first exemplary embodiment. Thus, components similar to those of the first exemplary embodiment are given the same reference numerals, and description of the components is omitted.FIG. 11is a front view illustrating a frame structure and members supported by the frame structure according to the present exemplary embodiment. According to the present exemplary embodiment, a first frame F1includes a right side plate40aand a first sheet feeding unit frame40b. The right side plate40aincludes a first side surface S1and the first sheet feeding unit frame40bincludes a second side surface S2. Further, a second frame F2includes a left side plate41aand a second sheet feeding unit frame41b. The left side plate41aincludes a third side surface S3and the second sheet feeding unit frame41bincludes a fourth side surface S4. Each of the right side plate40aand the left side plate41ais a metal member, and each of the first sheet feeding unit frame40band the second sheet feeding unit frame41bis a resin member.

A power supply unit55is provided outside the third side surface S3and the fourth side surface S4(the side opposite to the cartridge P and the sheet feeding cassette19). The power supply unit55is an integrally-formed power supply unit having the functions of the power supply unit (low voltage power supply unit)51and the high voltage power supply unit53according to the first exemplary embodiment. Further, the fourth side surface S4is provided further inside than the third side surface S3(closer to the sheet feeding cassette19), and a relatively large component of the power supply unit55, such as a transformer, is provided in a position facing the fourth side surface S4. In this way, the power supply unit55can be prevented from protruding.

According to the present exemplary embodiment, a similar effect to an effect obtained by the first exemplary embodiment can be obtained. Specifically, formation of an unnecessary space can be prevented and effective use of the space in the apparatus is enabled.

The foregoing effect can be obtained, as long as at least a part of the second side surfaces is provided in a position different from the position of the first side surface S1in the X direction and at least a part of the fourth side surfaces is provided in a position different from the position of the third side surface S3in the X direction.

This application claims the benefit of Japanese Patent Application No. 2014-143515, filed Jul. 11, 2014, which is hereby incorporated by reference herein in its entirety.