JP3871139B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus used as a flat bed scanner in a scanner, a facsimile machine, a copying machine or the like.

  In scanners, facsimiles, copying machines, etc., a flat bed scanner (hereinafter referred to as “FBS”) in which a reading unit of a reduction optical system such as a CCD (Charge Coupled Device) is incorporated in a reading table is used as image reading means. There is. FIG. 9 is a schematic perspective view showing the external appearance of the upper portion of a conventional copy / facsimile multifunction peripheral 900. As shown in FIG. 9, the copy / facsimile multifunction peripheral 900 has a platen glass 901 on which a document to be read is placed. And a document holding cover 903 for pressing and fixing the document on the platen glass 901 and an operation panel 904 for inputting reading start of the document. Although not shown, the main body of the copy / facsimile multifunction peripheral 900 is supplied with an image recording unit for recording an image on a recording sheet, a transmission unit for transmitting the image, and a recording sheet for recording the read image. A paper feeding cassette is provided.

  The reading table 902 incorporates an image reading unit such as a CCD. As shown in FIG. 10, the image reading unit includes a full-rate carriage 905 and a half-rate carriage 906 in which a light source for irradiating light on a document and a reflection mirror for guiding a reflection hole from the document to the CCD are appropriately disposed. Is slidably provided on a guide rail (not shown) provided in the reading table 902, and scans the original on the platen glass 901 by scanning the full-rate carriage 905 and the half-rate carriage 906. The reflected light R from the original is read as an image signal by the scanner unit 907.

  The scanner unit 907 includes an imaging lens 908 that converges reflected light from the full-rate carriage 905 and the half-rate carriage 906, and a CCD image sensor 909 for converting the converged light into an electrical signal. It is fixed to a chassis or the like (not shown) of the mounting table 902. The scanner unit 907 is generally provided with a control board for controlling the CCD image sensor 909. However, the control signal has a higher frequency as the reading speed increases and the resolution increases. There is a problem that the electromagnetic wave generated from the substrate becomes noise and affects other electronic members such as the full-rate carriage 905, causing malfunction of the image reading apparatus and deterioration of image quality. A fluorescent lamp may be used as the light source of the full-rate carriage 905. The fluorescent lamp is suitable as a light source because it has high brightness and can read an image in a short time. Since the brightness of the lamp must be stabilized, an inverter circuit (not shown) is used as a ballast. The inverter circuit may also be disposed in the vicinity of the scanner unit 907, and electromagnetic waves generated from the inverter circuit may cause a malfunction of the image reading apparatus and a decrease in image quality, as described above.

  In contrast, a configuration has been devised in which the scanner unit 907, the inverter circuit, and the like are covered with a metal cover and shielded. By shielding with the cover, there is an advantage that electromagnetic waves generated from the scanner unit 907 and the inverter circuit are blocked, and malfunction and deterioration of image quality can be prevented without affecting the electronic components outside the cover. Such a cover is screwed and fixed to a chassis to which the scanner unit 907 and the like are attached. The cover and the chassis come into contact with each other with metal screws or screwing portions, and are brought into conduction and grounded.

  In order to ensure sufficient conduction between the cover and the chassis even if cover distortion or assembly error occurs, a leaf spring made of phosphor bronze is interposed between the cover and the chassis. A configuration has been devised in which a spring is brought into pressure contact with the cover and the chassis to reliably establish conduction between the cover and the chassis (see, for example, Patent Document 1). In addition, a configuration has been devised in which the edge of the cover is bent in the shape of a letter toward the chassis and the edge and the chassis are screwed together so that the edge directly contacts the chassis (for example, Patent Document 2). Thus, the cover and the chassis can be sufficiently conducted, and the shielding effect by the cover can be sufficiently exhibited.

JP 2002-237924 A JP 2003-75938 A

  Since the scanner unit 907 reads the reflected light R from the full-rate carriage 905 and the half-rate carriage 906, the full-rate carriage 905, the half-rate carriage 906, and the scanner unit 907 are positioned on the optical path of the reflected light R. And is assembled to the chassis of the reading table 902. Therefore, the chassis maintains the positional accuracy of the full-rate carriage 905, the half-rate carriage 906, and the scanner unit 907, and plays a role of preventing dust and the like from entering the optical path.

  The chassis of the reading stage 902 is generally configured by assembling a plurality of members obtained by pressing a sheet metal or the like. However, if the positional accuracy of the scanner unit 907 and the like is maintained throughout the chassis, each member has a desired rigidity. As a result, the thickness of the sheet metal is increased, the weight is increased, and the cost is increased. In addition, in assembling each member, it is difficult to perform assembly with high dimensional accuracy in a configuration in which each member is assembled by screwing a screw into a screw hole drilled in a sheet metal by pressing or the like. However, if all the members are fixed by welding, the processing cost becomes high. On the other hand, a configuration has been devised in which a highly rigid scanner frame is assembled with high precision at the mounting portion of the scanner unit 907 that requires positional accuracy, and the scanner unit 907 is fixed to the scanner frame. However, in order to increase the dimensional accuracy, the fixed position of the scanner frame is limited, so the contact area between the scanner frame and other components of the chassis is reduced, and the scanner frame cannot be grounded sufficiently. There arises a problem that the shield effect of the cover grounded via the scanner frame is not sufficiently exhibited.

  The present invention has been made to solve such a problem. In an image reading apparatus that irradiates light on a document and reads reflected light from the document as image data, the scanner frame can be reliably grounded with a simple configuration. It aims to provide a means.

The present invention relates to an image reading apparatus that irradiates a document with light and reads reflected light from the document as image data, a frame constituting an outer frame of a chassis of the apparatus body, and a scanner fixed to a predetermined position of the frame A frame, a scanner unit that is fixed to the scanner frame, converts the reflected light into image data by a photoelectric element and reads the image data, a cover that shields the scanner unit and is electrically connected to the scanner frame, and a desired area. A bulging portion having a contact surface is formed, and includes a bottom chassis that constitutes a bottom of the chassis by abutting the contact surface of the bulging portion on the scanner frame and being fixed to the frame. It is characterized by that.
The scanner frame and the bulging portion of the bottom chassis are preferably fixed by a fixing tool.

  According to the image reading apparatus of the present invention, it is easy to form a bulging portion having a contact surface of a desired area on a bottom chassis that does not require strength for maintaining positional accuracy, and the bulging portion is a scanner. By abutting against the frame, sufficient conduction between the scanner frame and the chassis can be ensured with a simple configuration. As a result, the cover can be sufficiently grounded, and the electromagnetic waves generated from the scanner unit or the like can be reliably shielded. Further, by fixing the scanner frame and the bulging portion of the bottom chassis, the scanner frame and the bulging portion can be reliably brought into contact even when the bottom chassis is distorted.

  FIG. 1 is a diagram showing a cross section of an upper part of a copy / facsimile multifunction peripheral 100 which is an image reading apparatus according to an embodiment of the present invention. As shown in the figure, the copy / facsimile multifunction peripheral 100 is a document having an auto document feeder (hereinafter referred to as “ADF”) 1 with respect to a reading table (apparatus body) 101 functioning as an FBS. A presser cover 102 is attached to be freely opened and closed. Further, although not shown in the figure, the copy / facsimile multifunction peripheral 100 records an image on a recording sheet and an operation panel for inputting a reading start of a document. It also has a well-known configuration such as an image recording unit for transmitting, a transmission unit for transmitting images, and a paper feed cassette for supplying recording paper for recording the read image. One example and any.

  As shown in FIG. 1, the reading table 101 is configured such that a platen glass 11 is disposed on the top surface of a substantially rectangular parallelepiped housing 10 and a CCD reading unit 12 is built in the housing 10. The original placed on the platen glass 11 is fixed by closing the original pressing cover 102 and the CCD reading unit 12 reads the image. On the other hand, the document presser cover 102 includes a document tray 2 that holds a plurality of documents in a stacked state, a laterally U-shaped transport path 3, and a paper discharge tray that supports the transported documents in a stacked state. 4, a pickup roller 5 and a paper feed roller 6 for feeding the original on the original tray 2 to the conveyance path 3, a conveyance roller 7 for nipping and conveying the original in the conveyance path 3, and an exit near the conveyance path 3. An ADF 1 including a paper discharge roller 8 and a CIS reading unit 9 for reading an image of a document at a reading position P2 is provided. According to the ADF 1, the original fed from the original tray 2 to the conveyance path 3 is reversed so as to make a U-turn from the upper side to the lower side along the horizontal U-shaped conveyance path 3, and reaches the reading position P 1. An image on the surface of the original is read by the CCD reading unit 12 when passing through the reading position P1, and a contact image sensor (hereinafter referred to as Contact Image Sensor) when passing through the conveying path 3 and passing through the reading position P2. An image on the back side of the document is read by a CIS reading unit 9 having “CIS”), and is then discharged to a discharge tray 4 below the document tray 2. In the copy / facsimile multifunction peripheral 100, the ADF 1 has an arbitrary configuration.

  The CCD reading unit 12 scans the document with two scanning carriages, irradiates the document with light, guides the reflected light from the document to a predetermined position where the image sensor is provided, and electrically transmits the reflected light. As shown in FIG. 1, it is composed of a full-rate carriage 120 and a half-rate carriage 121 that are scanned in parallel with the platen glass 11, and a scanner unit 122. The full-rate carriage 120 reflects a light source 124 for irradiating a document with light and a reflected light R from the document in the scanning direction on a carriage main body 123 moving on the guide rail 18 (see FIG. 3), and is a half-rate carriage. The half-rate carriage 121 is provided with two reflecting mirrors 125 for guiding the reflected light from the full-rate carriage 120 to the scanner unit 122 to the carriage main body 126 moving on the guide rail. A reflection mirror 125 is provided.

  Further, as shown in the figure, the scanner unit 122 converges the reflected light R from the half-rate carriage 121 and an optical image formed by the converged light into image data that is an electrical signal. A CCD image sensor (photoelectric element) 128 is provided, and the CCD image sensor 128 is adjusted and disposed so as to be positioned on the optical axis of the imaging lens 127.

  When reading an image of a document as an FBS, the full-rate carriage 120 moves in parallel to the document on the platen glass 11 while emitting light from the light source 124, so that the light of the light source 124 is incident on the reading surface of the document. The light is sequentially irradiated in the scanning direction, and the reflected light R of the light is reflected by the reflection mirror 125 to the half-rate carriage 121. The half-rate carriage 121 also moves simultaneously with the full-rate carriage 120, and the reflected light R from the full-rate carriage 120 is reflected by the two reflecting mirrors 125 and guided to the scanner unit 122. The reflected light R is modified by the CCD image sensor 128 and read by the imaging lens 127 and output as an electrical signal. A recording unit or a transmission unit (not shown) receives the electric signal and records an image of a document on a recording sheet or transmits an image by facsimile. Since the recording unit and the transmission unit are publicly known and have arbitrary configurations, detailed description thereof is omitted. On the other hand, when reading an image of a document using the ADF 1, the full-rate carriage 120 moves below the platen glass 12 and irradiates the light from the light source 124 to the document sequentially conveyed by the ADF 1 from that position. As described above, the reflected light R from the original is read by the CCD image sensor 128.

  On the other hand, the full-rate carriage 120 and the half-rate carriage 121 slidably supported by guide rails 18 (not shown) are scanned by a pair of belt drive mechanisms 130 disposed on both sides thereof. . FIG. 1 shows one of a pair of belt drive mechanisms 130. The belt drive mechanism 130 is driven by belts 135 and 136 wound between drive pulleys 131 and 132 and driven pulleys 133 and 134, respectively. The belt 135 is configured to rotate around the shaft 137, and the full rate carriage 120 is fixed to the belt 135 and the half rate carriage 121 is fixed to the belt 136. The drive pulleys 131 and 132 are both fixed to the drive shaft 137, and the scanning ranges of the full rate carriage 120 and the half rate carriage 121 are set by the gear ratio of the drive pulleys 131 and 132, and drive the full rate carriage 120. In order to drive the half-rate carriage 121 with respect to the driving pulley 131, the gear ratio of the driving pulley 132 is approximately ½. As a result, the full rate carriage 120 and the half rate carriage 121 scanned by the belts 135 and 136 wound around the drive pulleys 131 and 132, respectively, are half rate at a speed approximately half the scanning speed of the full rate carriage 120. The carriage 121 is scanned, and the scanning distance of the half-rate carriage 121 is halved with respect to the scanning distance of the full-rate carriage 120. The full-rate carriage 120 and the half-rate carriage 121 configured as described above move below the platen glass 11 in parallel with the original placed on the platen glass 11 to scan the image of the original, and the light source 124 of the full-rate carriage 120. The original is irradiated with light, and the reflected light R from the original is sequentially reflected by the reflection mirror 125 and guided to the scanner unit 122.

  FIG. 2 is a schematic perspective view showing a detailed configuration of the scanner unit 122. As shown in the figure, the scanner unit 122 includes an imaging lens 127 that converges the reflected light R from the half-rate carriage 121, and A CCD image sensor 128 for converting the convergent light into an electrical signal, and the CCD image sensor 128 is adjusted to be positioned on the optical axis of the imaging lens 127 and fixed to the frame. Yes. The scanner unit 122 configured as described above is converted into image data by the optical image CCD image sensor 128 based on the reflected light R from the original and output. A control board 129 of the CCD image sensor 128 is fixed to the back side of the CCD image sensor 128 by soldering or the like.

  3 and 4 show a chassis 13 and the like constituting the casing 10 of the reading mounting table 101, and the casing 10 has a resin cover (not shown) attached to the chassis 13 as appropriate. . As shown in the figure, the chassis 13 includes a frame 14 in which four side wall members 14 a, 14 b, 14 c, and 14 d are assembled to form an outer frame of the chassis 13, and a chassis 13 that is disposed below the frame 14. The bottom chassis 15 constituting the bottom of the frame 14 and the scanner frame 16 fixed at a predetermined position of the frame 14 are configured. A scanner unit 122 and an inverter circuit 19 constituting the CCD reading unit 12 are fixed to the scanner frame 16, and the scanner unit 122 and the inverter circuit 19 are covered with a cover 17. Although not shown in the figure, other components of the CCD reading unit 12 such as the full rate carriage 120 and the half rate carriage 121 are also disposed in the chassis 13 surrounded by the frame 14. A platen glass 11 is disposed on the top. Therefore, the chassis 13 is a framework of the housing 10 of the reading table 102 and also plays a role of preventing dust from entering the CCD reading unit 12 and its optical path.

  As described above, the chassis 13 includes the frame 14, the bottom chassis 15, and the scanner frame 16. The bottom chassis 13 is mainly intended to prevent dust and the like from entering the chassis 13. The frame 14 also serves as a framework of the housing 10 of the reading table 102. The bottom chassis 15 is formed by pressing a relatively thin sheet metal in consideration of weight reduction and cost of the apparatus, and has a screw hole for attaching various members in the reading table 102. Although formed, the processing accuracy of the bottom chassis 15 is not high, so members that do not require high positional accuracy are mainly attached. On the other hand, those that require high positional accuracy such as various members constituting the CCD reading unit 12 are attached to the frame 14 and the scanner frame 16. The four side wall members 14a, 14b, 14c, and 14d constituting the frame 14 and the scanner frame 16 are formed by pressing a relatively thick sheet metal or the like, and have higher rigidity than the bottom chassis 15. The four side wall members 14a, 14b, 14c, 14d and the scanner frame 16 are assembled by positioning the side wall members 14a, 14b, 14c, 14d and the scanner frame 16 using an unillustrated assembling jig, The side wall members 14a, 14b, 14c, 14d and the scanner frame 16 are fixed by welding. Thereby, desired rigidity is ensured in the frame 14 as a framework of the housing 10, and the accuracy of the attachment positions of various members is maintained together with the scanner frame 16.

  Each of the side wall members 14a, 14b, 14c, and 14d has a sheet metal whose upper end is bent inward in an L-shaped cross section, and supports the platen glass 11 at the upper end. Each of the side wall members 14a, 14b, 14c, and 14d has a lower end portion bent inward in an L-shaped cross section, and is connected and fixed to the bottom chassis 15 with screws at the lower end portion. Further, the side wall member 14a on the back and back side of the reading table 101 and the side wall member 14b on the front side have a predetermined height and are bent substantially inwardly in the horizontal direction to form a horizontal plane. The horizontal plane becomes a guide rail 18 that slidably carries a full rate carriage 120 and a half rate carriage 121 (not shown) constituting the CCD reading unit 12. A resin sliding tape is affixed to the guide rail 18 for the purpose of reducing friction when the full rate carriage 120 and the half rate carriage 121 slide. Although not shown in detail in the drawing, each side wall member 14a, 14b, 14c, 14d is fixed to each member such as a support bracket for supporting the driven pulleys 133, 134 of the belt drive mechanism 130 with screws. And a bearing hole through which the drive shaft 137 of the belt drive mechanism 130 is inserted. As described above, the full-rate carriage 120, the half-rate carriage 121, and the belt driving mechanism 130 that constitute the CCD reading unit 12 are positioned by the frame 14, and the frame 14 needs to be rigid enough to maintain the positional accuracy. The thickness of the sheet metal of each side wall member 14a, 14b, 14c, 14d is also set in consideration of the rigidity. The screw holes and the like for attaching the components of the CCD reading unit 12 are appropriately designed according to the configuration of the reading table 101.

  The bottom chassis 15 has a shape in which a peripheral edge of a substantially rectangular sheet metal is bent upward, and is fixed to the frame 14 to constitute the bottom of the chassis 13. The position accuracy with which the chassis 13 supports each component of the CCD reading unit 12 is ensured mainly by the frame 14, and the bottom chassis 15 is provided mainly for dust prevention, and the rigidity similar to that of the frame 14 is assured. A sheet metal having a thickness that is not necessary and can be easily processed can be used. As shown in FIG. 4, a bulging portion 150 is formed at a position corresponding to the scanner frame 16 of the bottom chassis 15 by bulging the sheet metal upward by drawing. The upper surface of the bulging portion 150 is a flat surface serving as a contact surface 15a for contacting the bottom surface of the scanner frame 16, and the width of the contact surface 150a takes into consideration the conduction with the scanner frame 16 and the width of the bottom surface. It is preferable to design such that it is as wide as possible. A screw hole 151 for tightening the scanner frame 16 is appropriately formed in the contact surface 150a of the bulging portion 150. Further, the bottom chassis 15 is appropriately formed with an attachment portion 152 for fixing wiring or the like, but these are for attaching a member that does not require positional accuracy.

  The scanner frame 16 is made of a substantially rectangular sheet metal, and both end portions 160 in the optical axis direction are bent upward in order to increase rigidity. The scanner frame 16 is fixed to the frame 14 and supports the scanner unit 122. As shown in FIG. 4, fitting projections 161 are formed at the four corners at both ends, and the fitting projections. 161 is fitted and fixed in a fitting hole 140 formed in the side wall members 14a and 14b. The full-rate carriage 120, the half-rate carriage 121, and the scanner unit 122 constituting the CCD reading unit 12 are required to be attached with predetermined accuracy. The positional accuracy is mainly maintained by the frame 14 and the scanner frame 16. Therefore, the thickness of the sheet metal is set so that the scanner frame 16 also has the same rigidity as the frame 14, and the frame 14 and the scanner frame 16 are positioned and assembled at a predetermined position using an assembly jig or the like, It is fixed by welding or the like. As shown in the figure, the scanner unit 122 and the inverter circuit 19 are fixed to a predetermined position on the scanner frame 16 configured as described above by screws or the like. The scanner frame 16 is provided with a through hole 162 having a slightly larger diameter at a position corresponding to the screw hole 151 of the bulging portion 150. Although not shown in detail in the drawing, Screw holes for screwing the unit 122 and the inverter circuit 19 are also appropriately formed.

  The cover 17 covers the scanner unit 122 fixed to the scanner frame 16 and shields the upper side of the inverter circuit 19. The cover 17 has a bottom that surrounds the fixed space by the ceiling 170 and the side wall 171. It is. The cover 17 is formed by bending a sheet metal, which is a conductive member, and a side wall 171 is continuously formed on four sides of the rectangular ceiling 170, and the space surrounded by the ceiling 170 and the side wall 171. Inside, the scanner unit 122 fixed to the scanner frame 16 is accommodated in a non-contact manner. Further, an opening 172 is formed in the side wall portion 171 on which the reflected light R from the half-rate carriage 121 is incident, and the reflected light R is incident on the imaging lens 127 of the scanner unit 122 through the opening 172. In addition, a fixing collar 173 is provided at the lower end of the side wall 171 located on both sides of the side wall 171 in which the opening 172 is formed. Although not shown in detail in the figure, the fixing collar 173 has a positioning through hole and a screw hole, and the positioning through hole is fitted to a dowel formed in the scanner frame 16. The cover 17 is positioned, and the fixing flange 173 is fastened to the scanner frame 16 by screws communicating with the screw holes and the screw holes formed in the scanner frame 16, whereby the cover 17 is attached to the scanner frame 16. Fixed. Thereby, the scanner unit 122 is shielded.

  Further, a shielding plate 174 protrudes from the ceiling portion 120 of the cover 17 so as to cover the upper side of the inverter circuit 19. The shielding plate 174 is also made of a sheet metal that is a conductive member, and is formed integrally with the cover 17. The size of the shielding plate 174 is larger than the shape of the inverter circuit 19 in plan view, and thus the inverter circuit 19 fixed to the scanner frame 16 is shielded. A predetermined gap C is provided between the ceiling 120 and the shielding plate 174. When fixing the cover 17 to the scanner frame 16, the fixing collar 173 is screwed from the upper side of the cover 17, so the gap C is formed for inserting a tool such as a screwdriver. Although not shown in detail, the position can be appropriately changed according to the position of the screw hole formed in the fixing collar 173. Thus, by providing the shielding plate 174 on the cover 17, the upper side of the inverter circuit 19 can be shielded. Since the shielding plate 174 is formed integrally with the cover 17, the scanner frame 16 is covered with the cover. It is not necessary to form a screw hole or the like for mounting separately from 17, and processing and assembly are easy.

  A resin insulating sheet 175 is attached to the upper surface of the shielding plate 174. In general, the inverter circuit 19 is for stabilizing the luminance of the fluorescent lamp that is the light source 124 of the full-rate carriage 120, and electromagnetic waves are also generated from the inverter circuit 19. Therefore, the shielding plate 174 is for preventing electromagnetic waves generated from the inverter circuit 19 from affecting other electronic devices, particularly the full rate carriage 120.

  As shown in FIGS. 5 and 6, wiring from the inverter circuit 19 to the light source 124 of the full rate carriage 120 is performed by a flexible harness 190. The harness 190 is a belt-like material in which a conductive material is covered with an insulating synthetic resin such as a film-like polyimide resin, and one connection end is fixed to the full-rate carriage 120 and is electrically connected to the light source 124 and the like. The other connection end is fixed to the bottom chassis 15 and is further wired from the connection end to the inverter circuit 19 (not shown). In FIG. 6, the chassis 14 and the like are partially omitted for convenience of explanation.

  The harness 190 has a play so as to be sufficiently longer than the distance from the fixed end of the bottom chassis 15 to the full rate carriage 120 when the full rate carriage 120 is scanned to the scanning end. It is in a curved state. In other words, the harness 190 extends from the full-rate carriage 120 in the scanning direction and reverses so as to curve downward, extends to the opposite side of the scanning direction, and is fixed to the bottom chassis 15. Thereby, the inverter circuit 19 and the full rate carriage 120 are electrically connected regardless of the scanning position of the full rate carriage 120.

  The harness 190 does not need to be formed in a belt-like and integrated manner as in the present embodiment as long as the play portion is flexible so that the play portion is driven by the scanning of the full-rate carriage 120. It is preferable to have an appropriate elasticity that does not hang downward or twist and become entangled. In addition, the harness 190 can include a cable for performing power supply and transmission / reception of control signals and image signals in addition to conduction between the inverter circuit 19 and the light source 124. Of course, it may be connected to a power source or a control unit for transmitting and receiving signals.

  Since the wiring from the connection end of the harness 190 on the bottom chassis 15 side to the inverter circuit 19 is also at a high voltage, a shorter one is preferable. Therefore, the inverter circuit 19 is disposed in the vicinity of the scanner unit 122 as in the present embodiment. In addition, since electromagnetic waves are also generated from the inverter circuit 19, in general, the inverter circuit 19 is disposed at a position different from the position where the harness 190 passes through the scanning of the full-rate carriage 120. As shown in FIG. The CCD image sensor 128 and the control board 129 of the unit 122 become larger with color image reading and higher image quality, and the inverter circuit 19 is installed between the scanner unit 122 and the position where the harness 190 passes (the hatched area in the figure). There is no space. Therefore, in order to make the passage position of the inverter circuit 19 and the harness 190 different from each other, the frame 14 must be enlarged, but as a result, the reading table 101 becomes larger and the apparatus itself becomes larger. In order to avoid this, the inverter circuit 19 is disposed at a position overlapping the passing position of the harness 190, the electromagnetic wave generated from the inverter circuit 19 is shielded by the shielding plate 174, and the harness 190 is shielded from a conductive member. In order to prevent leakage due to contact with the plate 174, an insulating sheet 175 is pasted on the upper surface of the shielding plate 174. Thereby, even if the scanner unit 122 is enlarged, the inverter circuit 19 can be provided without increasing the size of the image reading apparatus.

Hereinafter, conduction between the cover 17 and the scanner frame 16 and conduction between the scanner frame 16 and the bottom chassis 15 will be described.
As described above, since the cover 17 shields the scanner unit 122 and the inverter circuit 19, it needs to be grounded. In the copy / facsimile multifunction peripheral 100, the cover 17 is grounded from the scanner frame 16 through the frame 14 and the bottom chassis 15. is doing.

  As shown in FIG. 3, the cover 17 fixed to the scanner frame 16 has a side wall portion 171 in which an opening 172 is formed and a lower end of the side wall portion 171 facing the side wall portion 171 as a contact plate and contacts the end portion 160 of the scanner frame 16. The fixing collar 173 contacts the upper surface of the scanner frame 16 as a contact plate. More specifically, strip-shaped contact pieces 176 are arranged in a row at the lower end of the side wall portion 171 that contacts the scanner frame 16 as a contact plate and the fixing flange portion 173. As shown in FIGS. 4 and 7, the contact piece 176 is formed by providing notches at predetermined intervals in the vertical direction from the lower end of the side wall portion 171 or in the horizontal direction from the side end of the fixing flange portion 173. The contact pieces 176 having a predetermined width are arranged in the vertical direction or the horizontal direction, respectively. The width of the contact piece 176 is set so that the contact piece 176 can be elastically moved toward and away from the scanner frame 16 and the reaction force by the contact piece 176 does not become an excessive lifting force when the cover 17 is screwed. The reaction force can be reduced by narrowing the width of the contact piece 176.

  Each contact piece 176 is formed with a curved portion 177 whose contact surface bulges toward the scanner frame 16. Since the curved portion 177 bulges toward the scanner frame 16 from the surface of the side wall portion 171 on which the contact pieces 176 are arranged or the bottom surface of the fixing flange portion 173, as shown in FIG. Even when a slight gap d is formed between the cover 17 and the scanner frame 16 due to distortion or assembly error of the cover 17 when attached to the frame 16, the curved portion 177 reliably contacts the scanner frame 16. And it will be in a conduction state. Further, by screwing the cover 17 to the scanner frame 16, each contact piece 176 is elastically deformed in a direction away from the scanner frame 16, and the elastic force is adjusted by the width of each contact piece 176. In addition, even when the gap d changes due to distortion or looseness in the attachment of the cover 17 over time, the contact piece 176 follows the change due to the elastic force of the contact piece 176. Thus, the contact between the curved portion 177 and the scanner frame 16 is maintained. In this way, the cover 17 and the scanner frame 16 can be reliably connected with a simple configuration without providing another member such as a leaf spring made of phosphor bronze.

  From the viewpoint of maintaining the contact by elastically deforming the contact piece 176 and always urging the curved portion 177 to the scanner frame 16, the fixing collar portion tightened by screwing the cover 17 to the scanner frame 16. It is preferable to form the contact piece 176 on the 173. However, it is also possible to form the contact piece 176 on the lower end of the side wall portion 171 for the purpose of easy processing and further increasing the contact portion. If there is, the part which forms the contact piece 176 is not limited.

  FIG. 8 shows a contact state between the scanner frame 16 and the bottom chassis 15, and the scanner unit 122 and the like are omitted for convenience of explanation. As described above, the scanner frame 16 is assembled to the frame 14. However, since these are required to be rigid and the accuracy of the assembly position is also required, the four corners of the scanner frame 16 are fitted to the frame 14. The assembling points are limited. As a result, the contact area between the scanner frame 16 and the frame 14 is small, and sufficient conduction for grounding cannot be obtained. On the other hand, the bottom chassis 15 does not require as much rigidity as the scanner frame 16 and is relatively easy to process. Therefore, a bulging portion 150 is formed in the bottom chassis 15, and the contact surface 150a of the bulging portion 150 is formed on the scanner frame. 16 is contacted with the bottom surface to ensure sufficient conduction. The scanner frame 16 has a through hole 162 having a slightly larger diameter at a position corresponding to the screw hole 151 of the bulging portion 150, and a screw (fixing tool) is inserted into the screw hole 151 through the through hole 162. Since the scanner frame 16 and the bulging portion 150 are tightened by screwing 163, the bottom chassis 15 is distorted or assembled, and the scanner frame 16 and the bulging portion 150 do not come into contact with each other. Even when it is sufficient, the contact surface 150 a of the bulging portion 150 can be reliably brought into contact with the bottom surface of the scanner frame 16 by tightening both members with the screw 163. Further, even when the bottom chassis 15 is distorted over time, the bottom surface of the scanner frame 16 and the contact surface 150a of the bulging portion 150 are not separated. In this way, the cover 17 can be grounded reliably and sufficiently to ensure the conduction between the cover 17 and the scanner frame 16 and between the scanner frame 16 and the bottom chassis 15, and the scanner unit 122 and the inverter circuit 19 can be shielded by the cover 17. .

  In the present embodiment, one bulging portion 150 is formed in the bottom chassis 15, but the shape and number of the bulging portions are not limited to this, and the shape of the scanner frame, the shape of the chassis 13, etc. In consideration of the assembly of the constituent members, it can be divided into a plurality of parts. Further, the bulging portion is not limited to a bulging sheet metal by drawing, and for example, it is possible to cut and raise the sheet metal to make the bulging portion. In order to achieve this, it is preferable to use a drawing process in which no hole is formed in the sheet metal. The configuration of the copy / facsimile multifunction peripheral 100 shown in the present embodiment is only one aspect of the image reading apparatus according to the present invention, and it is needless to say that the design can be changed as appropriate without departing from the gist of the present invention. is there.

  The image reading apparatus according to the present invention can be used as an image reading apparatus having a scanner unit using a photoelectric element in a scanner, a facsimile, a copying machine or the like.

1 is a cross-sectional view showing a schematic configuration of an upper part of a copy / facsimile multifunction peripheral 100 according to an embodiment of the present invention. 2 is a schematic perspective view illustrating a configuration of a scanner unit 122. FIG. FIG. 3 is a perspective view showing configurations of a chassis 13 and a cover 17. FIG. 3 is an exploded perspective view showing configurations of a chassis 13 and a cover 17. 3 is a plan view showing the arrangement of an inverter circuit 19. FIG. 4 is a cross-sectional view for explaining wiring from an inverter circuit 19 to a full rate carriage 120. FIG. (A) is an enlarged sectional view showing the contact state between the contact piece 176 formed on the fixing collar 173 and the scanner frame 16, and (b) is the contact piece 176 formed on the side wall 171 and the scanner. 3 is an enlarged cross-sectional view showing a contact state with an end portion 160 of a frame 16. 2 is a cross-sectional view showing a contact state between a scanner frame 16 and a bottom chassis 15. FIG. FIG. 10 is a schematic perspective view showing an upper configuration of a conventional copy / facsimile multifunction peripheral 900. 3 is a cross-sectional view illustrating a schematic structure of a reading unit in a reading mounting table 902. FIG.

Explanation of symbols

13 Chassis 14 Frame 15 Bottom chassis 16 Scanner frame 17 Cover 100 Copy / facsimile multifunction machine (image reading device)
101 Reading table (device body)
122 Scanner unit 128 CCD image sensor (photoelectric element)
150 Swelling part 163 Screw (fixing tool)

Claims (2)

In an image reading apparatus that irradiates a document with light and reads reflected light from the document as image data.
A frame constituting the outer frame of the chassis of the device body;
A scanner frame fixed at a predetermined position of the frame;
A scanner unit that is fixed to the scanner frame, converts the reflected light into image data by a photoelectric element, and reads the image data;
A cover that shields the scanner unit and is electrically connected to the scanner frame;
A bulging portion having a contact surface of a desired area, and a bottom chassis constituting the bottom of the chassis by abutting the contact surface of the bulging portion against the scanner frame and being fixed to the frame. An image reading apparatus characterized by comprising:   The image reading apparatus according to claim 1, wherein the scanner frame and the bulging portion of the bottom chassis are fixed by a fixing tool.

Images