Image reader

An image reader is provided, which includes a housing including a base, and a reading unit including a holder, the base including a bottom wall, a first guide disposed at a first-side portion of the bottom wall in a first direction, and a second guide disposed at a second-side portion of the bottom wall in the first direction, and the reading unit further including a third guide disposed at a first-side portion of the holder in the first direction, the third guide configured to come into sliding contact with the first guide when the reading unit moves, and a fourth guide disposed at a second-side portion of the holder in the first direction, the fourth guide configured to come into sliding contact with the second guide when the reading unit moves.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119 from Japanese Patent Application No. 2013-005837 filed on Jan. 17, 2013. The entire subject matter of the application is incorporated herein by reference.

BACKGROUND

1. Technical Field

The following description relates to one or more techniques for an image reader configured to read an image formed on a document sheet.

2. Related Art

An image reader has been known that includes a housing and an image reading unit. The housing includes a document table and a resin base configured to support the document table from beneath. The image reading unit includes an image sensor configured to extend in a first direction and read an image of a document sheet placed on the document table, a holder configured to hold the image sensor, and an urging unit provided at the holder and configured to urge the image sensor toward the document table. The image reading unit is movable along a second direction perpendicular to the first direction.

The resin base has a bottom wall disposed below the document table. The bottom wall includes a guiderail disposed at a center thereof in the first direction. The guiderail extends in the second direction, and protrudes from the bottom wall toward the document table in a third direction perpendicular to the first and second directions.

The image reading unit includes a reader-side guide portion disposed at a center of the holder in the first direction. The reader-side guide portion is recessed toward the document table from the bottom wall in the third direction, and contacts the guiderail. When the image reading unit moves, the reader-side guide portion and the resin guiderail are brought into sliding contact with each other.

Thus, according to the known image reader employing the resin guiderail instead of a metal guiderail that has been used so far, it is possible to achieve a low cost for manufacturing the image reader.

SUMMARY

Nonetheless, in the known image reader, a reaction force, generated when the urging unit urges the image sensor toward the document table, is applied to the resin guiderail and the bottom wall via the holder at which the urging unit is provided and the reader-side guide portion included in the holder. Further, the resin guiderail is disposed at the center of the bottom wall in the first direction, and has a lower stiffness than the stiffness of the metal guiderail. Therefore, there might be a case where the resin guiderail is creep-deformed in such a manner that the center of the bottom wall in the first direction is farther away from the document table in the third direction, in response to the reaction force being applied to the bottom wall for a long period of time. By such creep deformation of the bottom wall, the holder, of which the reader-side guide portion comes into sliding contact with the guiderail, is rendered farther away from the document table toward the bottom wall in the third direction. In this situation, it is difficult for the urging unit to urge the image sensor toward the document table in a favorable manner. It might result in a lowered accuracy for positioning the image sensor relative to the document table in the third direction and a lowered level of quality in image reading by the image reader.

Aspects of the present invention are advantageous to provide one or more improved techniques, for an image reader, which make it possible to achieve a low cost for manufacturing the image reader and reduce deterioration of the quality in image reading by the image reader.

According to aspects of the present invention, an image reader is provided, which includes a housing including a document table, and a base configured to support the document table from beneath, and a reading unit including an image sensor extending in a first direction and configured to read an image of a document sheet on the document table, a holder configured to hold the image sensor, and an urging unit disposed at the holder and configured to urge the image sensor toward the document table, the reading unit configured to move along a second direction perpendicular to the first direction, the base including a bottom wall disposed below the document table, a first guide disposed at a first-side portion of the bottom wall in the first direction, the first guide extending in the second direction and formed in one shape of a shape protruding from the bottom wall toward the document table and a shape recessed from the document table toward the bottom wall in a third direction perpendicular to the first direction and the second direction, and a second guide disposed at a second-side portion of the bottom wall in the first direction, the second guide extending in the second direction and formed in one shape of a shape protruding from the bottom wall toward the document table and a shape recessed from the document table toward the bottom wall in the third direction, the reading unit further including a third guide disposed at a first-side portion of the holder in the first direction, the third guide formed in one shape of a shape protruding from the document table toward the bottom wall and a shape recessed from the bottom wall toward the document table in the third direction, the third guide configured to come into sliding contact with the first guide when the reading unit moves, and a fourth guide disposed at a second-side portion of the holder in the first direction, the fourth guide formed in one shape of a shape protruding from the document table toward the bottom wall and a shape recessed from the bottom wall toward the document table in the third direction, the fourth guide configured to come into sliding contact with the second guide when the reading unit moves.

According to aspects of the present invention, further provided is an image reader that includes a housing including a document table, and a base configured to support the document table from beneath, and a reading unit including an image sensor extending in a first direction and configured to read an image of a document sheet on the document table, a holder configured to hold the image sensor, and an urging unit disposed at the holder and configured to urge the image sensor toward the document table, the reading unit configured to move along a second direction perpendicular to the first direction, the base including a bottom wall disposed below the document table, a first guide disposed at a first-side portion of the bottom wall in the first direction, the first guide extending in the second direction, and a second guide disposed at a second-side portion of the bottom wall in the first direction, the second guide extending in the second direction, the reading unit including a third guide disposed at a first-side portion of the holder in the first direction, and a fourth guide disposed at a second-side portion of the holder in the first direction, the reading unit being further configured to move along the second direction while being positioned relative to the housing with the third guide being guided by the first guide and the fourth guide being guided by the second guide in response to movement of the reading unit along the second direction.

According to aspects of the present invention, further provided is an image reader that includes a housing including a document table, and a base including a bottom wall disposed below the document table, and a side wall extending upward from the bottom wall and configured to support a fringe of the document table from beneath, and a reading unit including an image sensor extending in a first direction and configured to read an image of a document sheet on the document table, and a holder configured to hold the image sensor, the reading unit configured to move along a second direction perpendicular to the first direction, the base further including a first guide disposed adjacent to the side wall at a first-side portion of the bottom wall in the first direction, the first guide extending in the second direction, and a second guide disposed adjacent to the side wall at a second-side portion of the bottom wall in the first direction, the second guide extending in the second direction, the reading unit further including a third guide disposed at a first-side portion of the holder in the first direction, the third guide configured to be guided by the first guide of the base while sliding in contact with the first guide during movement of the reading unit along the second direction, and a fourth guide disposed at a second-side portion of the holder in the first direction, the fourth guide configured to be guided by the second guide of the base while sliding in contact with the second guide during the movement of the reading unit along the second direction.

DETAILED DESCRIPTION

Hereinafter, an embodiment according to aspects of the present invention will be described with reference to the accompanying drawings.

FIG. 1shows an image reader1of an embodiment according to aspects of the present invention. In the embodiment, a front side, a rear side, a left side, a right side, an upside, and the downside of the image reader1will be defined as shown inFIG. 1and the other accompanying drawings. Hereinafter, referring toFIG. 1and relevant drawings, a general configuration of the image reader1will be described. Thereafter, specific configurations of a housing5and a reading unit9will be described in detail.

As shown inFIGS. 1 to 3, the image reader1includes a housing5, a case3disposed below the housing5, and an opening-closing unit6disposed above the housing5.

As shown inFIGS. 1 to 3, the housing5is formed substantially in a box shape flattened in a vertical direction. As shown inFIGS. 4 and 5, the housing5includes a base10, a document table17, and a top cover19. The base10is a resin member formed substantially in an upward-open box shape. The document table17is a rectangular transparent glass plate. The top cover19is a frame-shaped resin member. When the base10supports a fringe17E of the document table17from beneath, and the top cover19comes into contact with the fringe17E from above, the document table17is pinched between the base10and the top cover19. Thereby, the document table17is fixed, in an exposed state, to an upper face of the housing. The document table17is configured to support a document sheet placed thereon to be read in a static state. The document sheet may include sheet-shaped objects such as a paper and a transparency (an OHP sheet), and a page of a book.

As shown inFIGS. 2 and 4to7, the housing5contains a reading unit9disposed therein. As shown inFIGS. 5 to 7, the reading unit9includes an image sensor79. As the image sensor79, known image reading sensors may be exemplified such as a contact image sensor (CIS) and a charge coupled device (CCD). The image sensor79extends in a front-to-rear direction. A length of the image sensor79in the front-to-rear direction is larger than a length in the front-to-rear direction of a maximum-size document sheet supportable on the document table17.

As shown inFIG. 2, the reading unit9is configured to be reciprocated along a left-to-right direction inside the housing5by a scanning mechanism7shown inFIGS. 6 and 7.

As shown inFIGS. 1 to 3, the housing3is formed substantially in a box shape. A front side of the case3protrudes upward so as to cover a front end of the housing5. As shown inFIG. 1, an operation panel4and a catch tray3A are disposed on the front side of the case3. As shown inFIG. 2, the case3contains an image forming unit8disposed therein. The image forming unit8is configured to form an image on a sheet in an image forming method such as a laser printing method and an inkjet printing method, and eject onto the catch tray3A the sheet with the image formed thereon.

As shown inFIGS. 1,3, and5, the housing5is supported by the case3so as to be swingable around an axis X5extending in the left-to-right direction at a rear end10B of the base10. When the housing5is swung around the axis X5such that the front end thereof moves toward an upper rear side from a closed state as shown by a solid line inFIG. 3to an open state as shown by a long dashed double-short dashed line inFIG. 3, an upper side of the catch tray3A is opened. Thereby, it is possible to do maintenance on the image forming unit8or remove a sheet jammed in the image forming unit8.

As shown inFIG. 1, the opening-closing unit6is supported by the housing5(more specifically, by a hinge (not shown) disposed at an upper end of a rear face of the housing5) so as to be swingable around an axis X6extending in the left-to-right direction. As shown by a solid line inFIG. 1, the opening-closing unit6, in a closed state, covers the document table17from above. Meanwhile, as shown by a long dashed double-short dashed line inFIG. 1, when the opening-closing unit6is swung around the axis X6such that a front end thereof moves toward an upper rear side, an upper side of the document table17is opened. Thereby, a user is allowed to place on the document table17an intended document sheet to be read.

As shown inFIGS. 1 and 2, a feed tray6A is provided at an upper portion of the opening-closing unit6so as to be openable and closable. As shown inFIG. 2, an automatic document feeder (ADF)6B is disposed in the opening-closing unit6. The ADF6B is configured to separate sheets placed on the feed tray6A in an open state on a sheet-by-sheet basis, and sequentially feed the sheets on a sheet-by-sheet basis along a conveyance path P1.

In the image reader1, as shown inFIG. 2, the reading unit9is moved from a left end to a right end inside the housing5to read a document sheet placed on the document table17is read. Thereby, the image sensor79moves from the left end to the right end under the sheet on the document table17, and reads out an image formed on the document sheet. After completion of the reading operation by the image sensor79, the reading unit9returns to the original position.

Further, in the image reader1, as shown inFIG. 2, the reading unit9moves to a statically-reading position at a left end inside the housing5, so as to read document sheets placed on the feed tray6A. When the reading unit9is in the statically-reading position, the image sensor79is in a position under a reading window17W shown inFIG. 4. Then, when the ADF6B sequentially feeds the document sheets placed on the feed tray6A along the conveyance path P1, the sequentially-fed document sheets pass over the reading window17W. Therefore, the image sensor79is allowed to read images of the sequentially-fed document sheets through the reading window17W.

Thus, the image reader1is allowed to read an image of a document sheet placed on the document table17, and read images of document sheets placed on the feed tray6A.

<Specific Configurations of Housing and Reading Unit>

As shown inFIGS. 5 to 9, the base10, included in the housing5, is a part integrally molded by injection molding of thermoplastic resin. The base10includes a bottom wall13, a first side wall11, a second side wall12, a left wall14L, and a right wall14R.

The bottom wall13is located lower than the document table17. The bottom wall13is formed in a flat plate shape extending horizontally. It is noted that “a flat plate shape” means a substantially flat plate shape, which may contain concavity-convexity portions, curved portions, and bent portions.

As shown inFIGS. 5 to 8, the first side wall11extends upward from a front end13A of the bottom wall13. Further, the first side wall11extends in a flat plate shape along the left-to-right direction. As shown inFIG. 8, an upper end of the first side wall11contacts a front end17A of the document table17from beneath, and pinches the front end17A with the top cover19that contacts the front end17A from above. Thus, the first side wall11supports the front end17A of the document table17from beneath.

As shown inFIGS. 5 to 7, and9, the second side wall12extends upward from a rear end13B of the bottom wall13. Further, the second side wall12extends in a flat plate shape along the left-to-right direction. As shown inFIG. 9, an upper end of the second side wall12contacts a rear end17B of the document table17from beneath, and pinches the rear end17B with the top cover19that contacts the rear end17B from above. Thus, the second side wall12supports the rear end17B of the document table17from beneath.

As shown inFIGS. 6 and 7, the left wall14L extends upward from a left end of the bottom wall13. Further, the left wall14L extends in a flat plate shape along the front-to-rear direction. As shown inFIG. 6, the right wall14R extends upward from a right end of the bottom wall13. Further, the right wall14R extends in a flat plate shape along the front-to-rear direction. Although it is not shown in any drawing, an upper end of the left wall14L contacts a left end of the document table17from beneath, and pinches the left end with the top cover19that contacts the left end from above. Thus, the left wall14L supports the left end of the document table17from beneath. Moreover, although it is not shown in any drawing, an upper end of the right wall14R contacts a right end of the document table17from beneath, and pinches the right end with the top cover19that contacts the right end from above. Thus, the right wall14R supports the right end of the document table17from beneath.

As shown inFIG. 5, in a middle section of the bottom wall13in the front-to-rear direction, a bent portion13is formed. The bent portion13C, after shortly extending upward from a portion extending in the front-to-rear direction, is bent and again oriented in the front-to-rear direction. Thereby, in the bottom wall13, a front portion thereof relative to the bent portion13C is closer to the document table17than a rear portion thereof. In other words, a portion of the base10on a side close to the first side wall11is thinner in the vertical direction than a portion of the base10on a side close to the second side wall12.

As shown inFIGS. 6 and 7, the scanning mechanism7is disposed in the housing5. The scanning mechanism7includes a driving source7M, a driving pulley7A, a driven pulley7B, and a timing belt7C.

The driving source7M includes an electric motor, and a group of gears configured to engage with the electric motor. The driving source7M is disposed adjacent to a middle section of the left wall14L in the front-to-rear direction, on a right side of the left wall14L. The driving source7M is controlled by a controller (not shown) to rotate.

The driving pulley7A is disposed close to the driving source7M. The driving pulley7A is supported by the bottom wall13so as to be rotatable around an axis extending in the vertical direction. The driving pulley7A is formed integrally with a gear configured to the group of gears of the driving source7M.

When the electric motor of the driving source7M is controlled by the controller (not shown) to rotate, the driving pulley7A is driven to rotate. When the controller switches a rotational direction of the electric motor, the driving pulley7A rotates forward or reversely.

As shown inFIG. 6, the driven pulley7B is disposed adjacent to a middle section of the right wall14R in the front-to-rear direction, on a left side of the right wall14R. The driven pulley7B is supported by the bottom wall13so as to be rotatable around an axis extending in the vertical direction.

The timing belt7C is an endless belt wound around the driving pulley7A and the driven pulley7B. Although it is not shown in any drawing, one of two linear sections extending parallel to each other from the driving pulley7A to the driven pulley7B is connected with a holder71of the reading unit9. Thereby, a movement of the timing belt7C in response to the forward rotation or the reverse rotation of the driving pulley7A is transmitted to the holder71of the reading unit9, and therefore, the reading unit9is allowed to reciprocate along the left-to-right direction.

As shown inFIGS. 5 to 12, the base10includes a first convex portion110and a second convex portion120.

As shown inFIGS. 5,6,8,10, and12, the first convex portion110is disposed at the front end13A of the bottom wall13. The first convex portion110is located adjacent to the first side wall11, behind the first side wall11. The first convex portion110extends along the first side wall11in the left-to-right direction. The first convex portion110protrudes up toward the document table17from the bottom wall13in the vertical direction.

As shown inFIGS. 8 and 12, the first convex portion110bulges upward in a rectangular shape in a cross-sectional view taken along a plane perpendicular to the left-to-right direction. The first convex portion110has a distal end surface111that is a flat surface perpendicular to the vertical direction.

As shown inFIGS. 5 to 7,9,11, and12, the second convex portion120is disposed at the rear end13B of the bottom wall13. The second convex portion120is located adjacent to the second side wall12, on a front side of the second side wall12. The second convex portion120extends along the second side wall12in the left-to-right direction. The second convex portion120protrudes up toward the document table17from the bottom wall13in the vertical direction.

As shown inFIGS. 9 and 12, the second convex portion120includes an arc section121that bulges upward in an arc shape in a cross-sectional view taken along a plane perpendicular to the left-to-right direction.

As shown inFIGS. 7 to 11, the reading unit9includes the image sensor79, the holder71, a third convex portion130, fourth concave portions140, a first urging member77A, and a second urging member77B.

As shown inFIGS. 7,10, and11, the image sensor79includes a sensor device79A, and a sensor case78incorporating the sensor device79A. The sensor case78has two rollers78A disposed at each of a front end and a rear end thereof. Each roller78A is configured to contact the document table17from beneath.

The holder71is a resin member formed substantially in an upward-open box shape. The holder71extends in the front-to-rear direction, and contains the image sensor79therein. Although it is not shown in any drawing, the holder71is configured to engage with a front end and a rear end of the sensor case78and hold the image sensor79while tolerating displacement of the image sensor79in the vertical direction.

As shown inFIGS. 8,10, and12, the third convex portion130is disposed at one location of a front end71A of the holder71. The third convex portion130is formed integrally with the holder71. The third convex portion130protrudes, in a rectangular column shape, down toward the bottom wall13from the document table17in the vertical direction. The third convex portion130has a distal end surface131that is a flat surface perpendicular to the vertical direction.

The distal end surface111of the first convex portion110contacts the distal end surface131of the third convex portion130. When the movement of the timing belt7C is transmitted to the holder71, and the reading unit9reciprocates along the left-to-right direction, the third convex portion130slides, at one location, relative to and in contact with the first convex portion110.

As shown inFIGS. 9,11, and12, the fourth concave portions140are provided at a rear end71B of the holder71. Further, as shown inFIG. 11, the fourth concave portions140are disposed at two locations such as to position the image sensor79at the middle between the two locations in the left-to-right direction. The fourth concave portions140are formed integrally with the holder71. As shown inFIGS. 9 and 12, each fourth concave portion140is recessed up toward the document table17from the bottom wall13in the vertical direction.

Each fourth concave portion140has two slanted surfaces141A and141B. The two slanted surfaces141A and141B are slanted so as to be closer to each other from the bottom wall13toward the document table17in the vertical direction in a cross-sectional view taken along a plane perpendicular to the left-to-right direction.

The arc section121of the second convex portion120contacts the two slanted surfaces141A and141B of each fourth concave portion140. When the movement of the timing belt7C is transmitted to the holder71, and the reading unit9reciprocates along the left-to-right direction, the fourth concave portions140slide relative to and in contact with the second convex portion120, at the two locations such as to position the image sensor79at the middle between the two locations in the left-to-right direction.

As shown inFIGS. 10 and 11, the first urging member77A and the second urging member77B are compression coil springs. The first urging member77A is disposed at the front end71A of the holder71. The second urging member77B is disposed at the rear end71B of the holder71.

As shown inFIG. 10, the first urging member77A is located closer to the document table17than the third convex portion130in the vertical direction. A lower end of the first urging member77A contacts a bottom of the holder71from above. An upper end of the first urging member77A contacts a bottom of the sensor case78from beneath.

As shown inFIG. 11, the second urging member77B is located closer to the document table17than the fourth concave portions140in the vertical direction. A lower end of the second urging member77B contacts the bottom of the holder71from above. An upper end of the second urging member77B contacts the bottom of the sensor case78from beneath.

Thus, the first urging member77A and the second urging member77B are configured to apply urging forces to urge the image sensor79toward document table17. When the image sensor79is moved upward by the urging forces, each roller78A contacts the document table17from beneath. Consequently, maintained is a constant distance in the vertical direction between the sensor device79A and the document table17.

In the image reader1configured as above, when the scanning mechanism7operates and causes the reading unit9to move along the left-to-right direction, the first convex portion110and the third convex portion130come into sliding contact with each other, and the second convex portion120and the fourth concave portions140come into sliding contact with each other.

In this case, as shown inFIG. 12, the holder71is positioned in the vertical direction as the distal end surface111of the first convex portion110contacts the distal end surface131of the third convex portion130on the front end of the holder71, and the arc section121of the second convex portion120contacts the slanted surfaces141A and141B of each fourth concave portion140on the rear end of the holder71.

Further, the holder71is positioned in the front-to-rear direction and positioned around a rotational axis X71extending in the vertical direction as the arc section121of the second convex portion120contacts the slanted surfaces141A and141B of each fourth concave portion140.

In other words, in the image reader1, as, when the reading unit9moves, the third convex portion130is guided by the first convex portion110, and the fourth concave portions140are guided by the second convex portion120, the reading unit9is allowed to move along the left-to-right direction while being positioned relative to the housing5.

In the image reader1of the embodiment, the resin base10includes the first convex portion110disposed at the front end13A of the bottom wall13, and the second convex portion120disposed at the rear end13B of the bottom wall13. Further, the first convex portion110and the third convex portion130of the holder71come into sliding contact with each other. Moreover, the second convex portion120and the fourth concave portions140of the holder71come into sliding contact with each other. Thus, according to the image reader1, it is possible to achieve a low cost for manufacturing the image reader1by employing the first convex portion110made of resin and the second convex portion120made of resin instead of known metal guiderails.

Further, in the image reader1, as shown inFIGS. 10 and 11, a reaction force R1A generated when the first urging member77A urges the image sensor79toward the document table17is applied to the first convex portion110and the front end13A of the bottom wall13via the holder71(at which the first urging member77A and the second urging member77B are provided) and the third convex portion130of the holder71. Further, a reaction force R1B generated when the second urging member77B urges the image sensor79toward the document table17is applied to the second convex portion120and the rear end13B of the bottom wall13via the holder71(at which the first urging member77A and the second urging member77B are provided) and the fourth concave portions140of the holder71.

The first side wall11extends upward from the front end13A of the bottom wall13. The second side wall12extends upward from the rear end13B of the bottom wall13. The first side wall11has such a high stiffness as to support the front end17A of the document table17. Further, the second side wall12has such a high stiffness as to support the rear end17B of the document table17. Therefore, the first convex portion110and the front end13A of the bottom wall13are reinforced by the first side wall11having the high stiffness, so as to bear the reaction force R1A in a favorable manner. Further, the second convex portion120and the rear end13B of the bottom wall13are reinforced by the second side wall12having the high stiffness, so as to bear the reaction force R1B in a favorable manner. Hence, even though the reaction forces R1A and R1B are applied to the bottom wall13for a long time period, the bottom wall13is not likely to be creep-deformed such that the center thereof in the front-to-rear direction is rendered farther from the document table17in the vertical direction. Thus, the holder71, of which the third convex portion130and the fourth concave portions140come into sliding contact with the first convex portion110and the second convex portion120, respectively, is not likely to be rendered farther from the document table17toward the bottom wall13in the vertical direction. Thereby, it is possible to maintain, for a long time period, a situation where the first urging member77A and the second urging member77B urge the image sensor79toward the document table17in a favorable manner. Consequently, according to the image reader1, it is possible to maintain, for a long time period, a high accuracy for positioning the image sensor79relative to the document table17in the vertical direction.

Thus, according to the image reader1of the embodiment, it is possible to achieve a low cost for manufacturing the image reader1and reduce deterioration of the quality in image reading by the image reader1.

Further, in the image reader1, as shown inFIG. 12, the holder71is positioned in the vertical direction as the distal end surface111of the first convex portion110contacts the distal end surface131of the third convex portion130on the front end of the holder71, and the arc section121of the second convex portion120contacts the slanted surfaces141A and141B of each fourth concave portion140on the rear end of the holder71. Therefore, the accuracy for positioning the holder71in the vertical direction is less likely to be lowered. Further, the holder71is positioned in the front-to-rear direction and positioned around the rotational axis X71extending in the vertical direction as the arc section121of the second convex portion120contacts the slanted surfaces141A and141B of each fourth concave portion140. Therefore, it is possible to omit a configuration for positioning the holder71in the front-to-rear direction and around the rotational axis X71with the first convex portion110and the third convex portion130. Further, since the first convex portion110, the second convex portion120, the third convex portion130, and the fourth concave portions140are formed as above, it is possible to achieve low contact-sliding resistances between the first convex portion110and the third convex portion130and between the second convex portion120and the fourth concave portions140. Thus, it is possible to smoothly move the holder71along the left-to-right direction.

Further, according to the image reader1, the third convex portion130slides, at one location, in contact with the first convex portion110. In addition, the fourth concave portions140slide in contact with the second convex portion120, at two locations such as to position the image sensor79at the middle between the two locations in the left-to-right direction. Thereby, the holder71is supported by the three points, and therefore, the first convex portion110, the second convex portion120, the third convex portion130, and the fourth concave portions140are allowed to certainly come into sliding contact with their respective corresponding portions. Consequently, in the image reader1, it is possible to achieve a high accuracy for positioning the holder71.

Further, in the image reader1, the housing5is supported by the case3so as to be swingable around the axis X5at the rear end10B of the base10. Therefore, the first side wall11, the first convex portion110, and the third convex portion130are far from the axis X5. Meanwhile, the second side wall12, the second convex portion120, and the fourth concave portions140are close to the axis X5. Additionally, in the image reader1, it is assumed that, in most cases, the user holds the front end of the base10that is close to the first side wall11and far from the axis X5. Therefore, it is preferable to thin a portion of the base10on the side close to the first side wall11. In this respect, near the first side wall11, disposed are the first convex portion110and the third convex portion130that contribute to positioning the holder71only in the vertical direction. Therefore, the first convex portion110and the third convex portion130are less likely to be voluminous than the second convex portion120and the fourth concave portions140that contribute to three kinds of positioning of the holder71(i.e., positioning the holder71in the vertical direction, positioning the holder71in the front-to-rear direction, and positioning the holder71around the rotational axis X71extending in the vertical direction). Hence, it is possible to easily thin a portion of the base10on the side close to the first side wall11, as shown inFIG. 5. Further, a portion of the base10on the side close to the second side wall12and the axis X5is formed thick in the vertical direction, so as to allow hinges (not shown) for swingably supporting the housing5to be attached thereto and secure a large space inside the base10. Therefore, the second convex portion120and the fourth concave portions140disposed near the second side wall12are allowed to attain the three kinds of positioning of the holder71by effectively utilizing the large space. Further, the portion of the base10on the side close to the second side wall12and the axis X5is configured to have a high stiffness so as to allow hinges to be attached thereto. Thus, the second convex portion120and the fourth concave portions140are certainly reinforced by the second side wall12, and thereby, it is possible to position the holder71with a further higher accuracy.

Further, in the image reader1, the first urging member77A and the second urging member77B are configured to urge the image sensor79toward the document table17near the front end71A and the rear end71B of the holder71, respectively. Hence, according to the image reader1, it is possible to urge the image sensor79toward the document table17in a more stable manner (a less rickety manner) than, e.g., when a single urging member is provided at a center in the front-to-rear direction.

Further, in the image reader1, the document table17is a glass plate having a high stiffness. In addition, such a configuration that the document table17is pinched between the base10and the top cover19heightens an overall stiffness of the housing5. Thus, according to the image reader1, since the stiffness properties of the first side wall11and the second side wall12are further heightened, the first convex portion110and the front end13A of the bottom wall13are effectively reinforced by the first side wall11, and the second convex portion120and the rear end13B of the bottom wall13are effectively reinforced by the second side wall12.

Only an exemplary embodiment of the present invention and but a few examples of their versatility are shown and described in the present disclosure. It is to be understood that the present invention is capable of use in various other combinations and environments and is capable of changes or modifications within the scope of the inventive concept as expressed herein. For example, the following modifications are possible. It is noted that, in the following modifications, explanations of the same configurations as exemplified in the aforementioned embodiments will be omitted.

For example, the respective shapes of the first convex portion110, the second convex portion120, the third convex portion130, and the fourth concave portions140are not limited to the shapes exemplified in the aforementioned embodiment. The first convex portion110, the second convex portion120, the third convex portion130, and the fourth concave portions140may be formed in any shapes as far as the first convex portion110and the third convex portion130are allowed to come into sliding contact with each other, and the second convex portion120and the fourth concave portions140are allowed to come into sliding contact with each other. For instance, the concave shape may include various shapes such as shapes of a hole having a bottom, a through hole, a groove, and a notch. Further, the cross-sectional shape of the second convex portion120exemplified in the aforementioned embodiment may be replaced with the cross-sectional shape of the fourth concave portions140exemplified in the aforementioned embodiment. Likewise, the cross-sectional shape of the fourth concave portions140exemplified in the aforementioned embodiment may be replaced with the cross-sectional shape of the second convex portion120exemplified in the aforementioned embodiment.

The first convex portion110of the aforementioned embodiment may be replaced with a portion configured to be recessed down toward the bottom wall13from the document table17, instead of protruding up toward the document table17from the bottom wall13. The second convex portion120of the aforementioned embodiment may be replaced with a portion configured to be recessed down toward the bottom wall13from the document table17, instead of protruding up toward the document table17from the bottom wall13. The third convex portion130of the aforementioned embodiment may be replaced with a portion configured to be recessed up toward the document table17from the bottom wall13, instead of protruding down toward the bottom wall13from the document table17. The fourth concave portions140of the aforementioned embodiment may be replaced with portions configured to protrude down toward the bottom wall13from the document table17, instead of being recessed up toward the document table17from the bottom wall13.

Further, for instance, another combination of guide portions may be added between the combination of the first convex portion110and the third convex portion130and the combination of the second convex portion120and the fourth concave portions140in the front-to-rear direction. The first side wall11and the second side wall12may be configured to indirectly support the document table17. The first convex portion110and the second convex portion120may be formed integrally with the base10, or may be separate from the base10and attached to the base10.