JP5783110B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus.

  2. Description of the Related Art Conventionally, there has been known a flat bed type image reading apparatus including an image sensor including a plurality of light receiving elements arranged along the main scanning direction and a carriage mounted with the image sensor and moving in the sub scanning direction together with the image sensor. (For example, refer to Patent Document 1). In the case of the image reading apparatus described in Patent Document 1, a metal guide shaft is disposed in the apparatus, and the above-described carriage is supported by the guide shaft and reciprocates along the guide shaft in the sub-scanning direction. It has a possible structure.

  In the case of the image reading apparatus described in Patent Document 1, the guide shaft is supported by the apparatus housing in a state in which it can move up and down, and is biased upward by a coil spring. The carriage (image sensor) supported by the guide shaft is biased upward by the bias of the coil spring. A contact glass on which a document to be read is set is disposed above the image sensor. In the vicinity of both ends of the image sensor in the main scanning direction, rollers that are in contact with the back surface of the contact glass are provided. With such a structure, when reading an image of a document, the image sensor can be moved in the sub-scanning direction while maintaining the contact between the roller and the contact glass. Thereby, the distance between the document and the image sensor can be kept constant.

  Further, there is an image reading apparatus in which the guide shaft is fixed and the image sensor can be moved up and down relatively with respect to the carriage, instead of the guide shaft having a structure capable of moving up and down as described above. In such an image reading apparatus, a convex portion that fits into the concave portion on the image sensor side is provided on the carriage side, and the convex portion that fits into the concave portion is fitted into the concave portion, so that the image sensor is attached to the carriage. On the other hand, relative displacement in the main scanning direction is restricted. With such a structure, even if the image sensor moves up and down within a range where the convex part does not come out of the concave part, the image sensor is not displaced in the main scanning direction, and the image sensor is held at an appropriate position on the carriage. can do.

JP 2007-178506 A

By the way, since the metal guide shaft as described above causes an increase in cost, the present inventor is considering replacing the guide shaft equivalent with a resin part.
However, when the guide shaft equivalent is formed of a resin material, the rigidity is inevitably lower than that of a metal guide shaft, so the guide shaft equivalent is likely to be deformed depending on the unevenness or inclination of the installation location, temperature conditions, etc. . Therefore, when the guide shaft equivalent is deformed, the distance between the carriage that moves along the guide shaft equivalent and the contact glass varies considerably. In this case, if the image sensor cannot maintain the proper position, the read quality of the image may be deteriorated.

  In particular, when the image sensor can be moved up and down relatively with respect to the carriage, even if a convex portion that fits into the concave portion on the image sensor side is provided on the carriage side, the convex portion is moved from the concave portion when the image sensor moves up and down greatly. There is a risk of falling out. In this case, the image sensor may be displaced in the main scanning direction, and the image sensor may not be held at an appropriate position on the carriage.

  As a method of preventing the convex portion from coming out of the concave portion even when the image sensor moves up and down more greatly, the concave portion is made deeper, the convex portion is made longer, and the stroke length in the vertical direction is secured. There is also a method. However, since the image sensor is a precision part having an optical mechanism and an electric mechanism, unlike a resin molded product, it is difficult to change the shape so as to make the recess deeper.

  The present invention has been made in order to solve the above-described problem, and the object thereof is to make the position where the image sensor moves an appropriate position even when the carriage moves along a resin guide. An object of the present invention is to provide an image reading apparatus that can be maintained.

Hereinafter, the configuration employed in the present invention will be described.
An image reading apparatus according to the present invention has a first surface and a second surface that are in a positional relationship on the front and back sides, a document placement table on which a document is placed on the first surface side, and the first of the document placement table Two directions parallel to one surface and perpendicular to each other are defined as a main scanning direction and a sub-scanning direction, and along the sub-scanning direction at a position facing the second surface of the document table with a predetermined interval. A resin-made guide portion that extends, a movable portion that moves in the sub-scanning direction along the guide portion while maintaining contact with the guide portion, and is attached to the movable portion, together with the movable portion A reading unit that reads an image of a document placed on the first surface of the document placing table with a plurality of light receiving elements arranged along the main scanning direction while moving in the sub-scanning direction; The reading unit is urged toward the second surface of the document table. An urging portion and attached to the reading portion, and sandwiched between the reading portion and the second surface of the document placing table by a force from the urging portion, and the reading portion and the document placing table An interval maintaining unit that maintains a constant interval with the second surface, and the reading unit has a mounting structure for the movable unit that is perpendicular to both the main scanning direction and the sub-scanning direction with respect to the movable unit. The distance maintaining unit is relatively displaceable in the sub-scanning direction and the interval maintaining unit is attached to the reading unit with respect to the reading unit in the main scanning direction and A structure that is relatively non-displaceable in the sub-scanning direction, and that the distance maintaining unit is relatively non-displaceable in the main-scanning direction relative to the movable part by contacting the movable part; It is characterized by being.

  In the image reading apparatus configured as described above, since the guide portion is made of resin, depending on the installation state of the device, the guide portion is more bent than the conventional product in which the guide portion is made of metal. It becomes easy. When the deflection of the guide portion increases, the movable portion that moves in the sub-scanning direction along the guide portion may be farther from the document placement table side than the conventional product. On the other hand, the reading unit and the interval maintaining unit can be displaced relative to the movable unit in a direction orthogonal to both the main scanning direction and the sub-scanning direction, and are urged toward the document placement table by the urging unit. ing. Therefore, as described above, even if the movable unit is separated from the document placing table side more than the conventional product, the reading unit and the interval maintaining unit are not separated from the document placing table side along the second surface of the document placing table. Move in the sub-scanning direction.

  Here, in a conventional product in which the reading unit is displaced in a direction orthogonal to both the main scanning direction and the sub-scanning direction relative to the movable unit, the reading unit fits into the recess in accordance with the recess on the reading unit side. The convex portion to be inserted is provided on the movable portion side, and the convex portion is fitted into the concave portion, thereby restricting the reading portion from being displaced relative to the movable portion in the main scanning direction. Therefore, as described above, when the reading unit and the interval maintaining unit are not separated from the document placing table side, but the movable unit is separated from the document placing table side more than the conventional product, the convex portion is removed from the recessed portion. In this case, the displacement of the reading unit cannot be properly regulated.

  In order to prevent such a protrusion from coming off, there is also a method in which the recess is made deeper and the protrusion is made longer to ensure a stroke length in a direction perpendicular to both the main scanning direction and the sub-scanning direction. . However, since the reading unit is a precision component having an optical mechanism and an electric mechanism, unlike a resin molded product, it is difficult to change the shape to make the recess deeper.

  In this regard, in the image reading apparatus of the present invention, the interval maintaining unit abuts on the movable unit, thereby restricting the interval maintaining unit from being displaced relative to the movable unit in the main scanning direction. Unlike the reading unit, the interval maintaining unit and the movable unit are not precision parts having an optical mechanism, and therefore the shape and the like can be designed relatively freely as compared with the reading unit.

  Therefore, even when the movable part is farther from the document placement table than the conventional product, it is much easier to design a shape that can maintain the contact between the distance maintaining part and the movable part than changing the shape of the reading part. Since it is easy to secure the stroke length as described above, the displacement of the reading unit can be appropriately regulated. Therefore, although the resin guide portion that is more easily deformed than the metal guide portion is employed, the displacement of the reading portion can be appropriately regulated, so that the image reading quality can be improved.

  By the way, in the image reading apparatus of the present invention, one of the interval maintaining unit and the reading unit is provided with a convex portion protruding toward the other, and the other is a concave portion into which the convex portion is fitted. It is preferable that the distance maintaining unit be relatively undisplaceable in the main scanning direction and the sub-scanning direction with respect to the reading unit by fitting the convex portion into the concave portion.

  According to the image reading apparatus configured as described above, the interval maintaining unit can be attached to the reading unit by fitting the convex portion into the recessed portion, and the interval maintaining unit and the reading unit are prevented from being relatively displaced. can do.

  In the image reading apparatus according to the aspect of the invention, one of the movable unit and the interval maintaining unit may have a portion protruding toward the other in a direction orthogonal to both the main scanning direction and the sub-scanning direction. The ribs extending in the shape of the ribs are formed, and the leading ends of the ribs in the protruding direction are in contact with the other, so that the interval maintaining part cannot be displaced relative to the movable part in the main scanning direction. It is preferable that

  According to the image reading apparatus configured as described above, the movable portion and the interval maintaining portion are brought into contact with the other end in the protruding direction of the rib formed on one of the movable portion and the interval maintaining portion. Can be positioned in the main scanning direction. In addition, since the rib has a shape extending in a direction orthogonal to both the main scanning direction and the sub-scanning direction, the movable part and the interval maintaining part are relatively orthogonal to both the main scanning direction and the sub-scanning direction. Even if it is displaced in the direction to do, both can be maintained in a positioned state. In addition, if the positioning is performed at the leading end of the rib in the protruding direction, the contact area of the contact portion can be reduced as compared with the case where the surface is in contact with the surface. In addition, it is possible to reduce the frictional resistance generated when displacing in the direction orthogonal to both the sub-scanning direction and the sub-scanning direction.

  In the image reading apparatus of the present invention, the movable portion protrudes toward the document table at each of two positions spaced in the main scanning direction and is sandwiched between the protruding portions. A pair of holding portions capable of holding the reading portion, wherein the rib is formed at one of the holding portion and the interval maintaining portion and protrudes toward the other at the other end in the protruding direction. It is preferable to be in contact with.

  According to the image reading apparatus configured as described above, the holding unit can hold the reading unit, and the holding unit can also be used for positioning with the interval maintaining unit, so that a positioning portion is provided separately from the holding unit. It is possible to make the structure compact by reducing the necessary configuration.

2A and 2B are perspective views of a multifunction machine including an image reading device, in which FIG. 1A is a perspective view showing a state where a document cover is closed, and FIG. 2B is a perspective view showing a state where the document cover is opened. FIG. 3 is a perspective view showing a schematic structure inside a reading unit. The perspective view which shows the drive mechanism of a carriage. A carriage, an image sensor, and a roller holder are shown, (a) is a plan view thereof, (b) is a right side view thereof, (c) is a rear view thereof, and (d) is a cut surface indicated by an AA line thereof. Sectional drawing which expands and is shown, (e) is sectional drawing which expands and shows a part of cut surface shown by a BB line. The perspective view which shows a carriage, an image sensor, and a roller holder. It is a figure which shows the rib provided in the roller holder, (a) is explanatory drawing which planarly viewed the rib, (b) is explanatory drawing which looked at the rib from the cut surface which shows an AA line. Explanatory drawing which shows the vertical movement state of a carriage.

  Next, an embodiment of the present invention will be described with an example. In the following description, for the sake of simplicity of explaining the structure of the apparatus, the directions of up, down, left, and right, front and back, which are also shown in the drawing, are used. However, each of these directions is only a direction defined for convenience in order to explain the relative positional relationship of each part of the apparatus, and which direction is defined as left and right and which direction is defined as front and back is arbitrary. is there.

[Machine structure]
As shown in FIG. 1A and FIG. 1B, a multifunction machine 1 includes a main unit 2 and a reading unit 3 mounted on the upper side of the main unit 2 (corresponding to an example of an image reading apparatus in the present invention). .)

  The main unit 2 includes an image forming unit, a control unit, a power supply unit, and the like, and various mechanisms arranged in the main unit 2 and the reading unit 3 are controlled by a control unit included in the main unit 2. .

  The reading unit 3 is configured to be rotatable with respect to the main unit 2 about an axis extending in the left-right direction near the rear ends of the main unit 2 and the reading unit 3. When the reading unit 3 is rotated to displace the front end side of the reading unit 3 upward, the opening on the upper surface of the main unit 2 is opened, and each unit (image forming unit, control unit, and It becomes possible to carry out maintenance work etc. of the power supply unit etc.

  The reading unit 3 includes a reading unit main body 3A and a document cover 3B. The document cover 3B is configured to be rotatable with respect to the reading unit main body 3A with an axis extending in the left-right direction near the rear end of the reading unit 3 as a rotation center. With this rotation, the document cover 3B is displaced to a closed position (see FIG. 1A) and an open position (see FIG. 1B).

  When the document cover 3B is displaced to the open position, the contact glass 4 (corresponding to an example of the document placing table in the present invention) on the upper surface of the reading unit main body 3A is exposed. Further, when the document cover 3B is displaced to the closed position, the document cover 3B covers the contact glass 4. A document feeder (ADF; Automatic Document Feeder) is incorporated in the document cover 3B.

  An operation panel 7 operated by a user is provided on the upper front side of the main unit 2. In the main unit 2, a recording medium outlet 8 for taking out the recording medium after printing is formed below the operation panel 7. Further below that, paper feed cassettes 9A and 9B for storing the recording medium before printing are mounted.

[Details of reading unit]
As shown in FIG. 2, a guide rail 11, a carriage 13, an image sensor 15, and interval maintaining members 17 and 18 are provided inside the reading unit main body 3 </ b> A. Of these, the guide rail 11 corresponds to an example of a guide portion referred to in the present invention, and the carriage 13 corresponds to an example of a movable portion referred to in the present invention. The image sensor 15 corresponds to an example of a reading unit referred to in the present invention, and the interval maintaining members 17 and 18 correspond to an example of an interval maintaining unit referred to in the present invention.

  2 and 3, the guide rail 11 is integrally formed of a resin material on the upper surface of the bottom of the casing 21 of the reading unit main body 3A, and has a shape extending in the left-right direction below the contact glass 4. ing.

  As shown in FIG. 3, the carriage 13 includes a sliding member 23 on the lower surface side, and the sliding member 23 has a recess 23 a that is recessed upward. The concave portion 23 a of the sliding member 23 is placed on the upper end with the upper end of the guide rail 11 interposed therebetween, and the carriage 13 is supported on the guide rail 11. As a result, the carriage 13 can slide along the guide rail 11.

  A timing belt 25 extending in the left-right direction is installed below the carriage 13, and the carriage 13 is coupled to the timing belt 25. Power is transmitted to the timing belt 25 from the stepping motor 29 via the gear mechanism 27, whereby the timing belt 25 is circulated and driven in both forward and reverse directions.

  When the timing belt 25 is driven, the carriage 13 moves following the timing belt 25, whereby the carriage 13 reciprocates in the left-right direction while being guided by the guide rail 11. The moving direction of the carriage 13 is the sub-scanning direction referred to in the present invention, and in the present embodiment, the left-right direction shown in the drawing corresponds to the sub-scanning direction referred to in the present invention. In the following description, the left-right direction shown in the drawing is also referred to as a sub-scanning direction.

  In this embodiment, the image sensor 15 employs a contact image sensor (CIS) and includes a plurality of light receiving elements arranged along the front-rear direction. The arrangement direction of the light receiving elements included in the image sensor 15 is the main scanning direction in the present invention, and in this embodiment, the front-rear direction shown in the drawing corresponds to the main scanning direction in the present invention. In the following description, the front-rear direction shown in the drawing is also referred to as a main scanning direction.

  When the image of the document placed on the contact glass 4 is read by the image sensor 15, the image sensor 15 repeatedly reads pixels aligned in the main scanning direction while moving the carriage 13 in the sub-scanning direction. The whole can be read.

  The spacing maintaining member 17 is attached to the upper front end of the image sensor 15 as shown in FIGS. The distance maintaining member 17 is composed of two rollers 17A and 17A and a roller holder 17B that holds them in a rotatable state.

  As shown in FIGS. 2 and 4A to 4E, the interval maintaining member 18 is attached to the upper rear end of the image sensor 15. Like the interval maintaining member 17, the interval maintaining member 18 also includes two rollers 18A and 18A and a roller holder 18B that holds them in a rotatable state.

  As shown in FIG. 4D, an urging member 30 (corresponding to an example of an urging portion in the present invention, which is a coil spring in this embodiment) is interposed between the carriage 13 and the image sensor 15. ing. The urging member 30 is a member that urges the image sensor 15 toward the lower surface of the contact glass 4.

  As shown in FIGS. 4 (a) to 4 (e) and FIG. 5, bearing portions 31A and 31B projecting upward (in the holding portion referred to in the present invention) are located at the right corners near both ends of the carriage 13 in the front-rear direction. Equivalent to an example).

  On the other hand, as shown in FIGS. 4A, 4B, and 5, the image sensor 15 includes protrusions 33A and 33B that protrude rightward in the vicinity of both ends in the front-rear direction. Each of the projecting portions 33A and 33B is provided with shaft portions 35A and 35B projecting rearward.

  When the image sensor 15 is attached to the carriage 13, the shaft portions 35A and 35B of the image sensor 15 are both inserted into the bearing portions 31A and 31B of the carriage 13 from the front as shown in FIG. .

  Here, the gaps on the bearing portions 31A and 31B side into which the shaft portions 35A and 35B are inserted are longer in the vertical dimension than the diameter of the shaft portions 35A and 35B, and the longitudinal dimension is the same as the diameter of the shaft portions 35A and 35B. It is almost the same. Therefore, if the shaft portions 35A and 35B are inserted into the bearing portions 31A and 31B, the image sensor 15 can be relatively displaced in the vertical direction with respect to the carriage 13 and relatively in the sub-scanning direction (front-rear direction). Cannot be displaced.

  When the image sensor 15 is attached to the carriage 13, the interval maintaining member 18 is attached to the image sensor 15 as shown in FIG. In the interval maintaining member 18, the roller holder 18B is provided with convex portions 37A and 37B protruding downward, while the image sensor 15 is provided with concave portions 39A and 39B into which the convex portions 37A and 37B are fitted. .

  When the interval maintaining member 18 is attached to the image sensor 15, both the convex portions 37A and 37B of the interval maintaining member 18 (roller holder 18B) are fitted into the concave portions 39A and 39B of the image sensor 15 from above. As a result, the interval maintaining member 18 cannot be displaced relative to the image sensor 15 in the main scanning direction and the sub-scanning direction.

  Further, since the image sensor 15 is urged toward the contact glass 4 by the urging member 30, the gap maintaining member 18 is interposed between the image sensor 15 and the lower surface of the contact glass 4 by the force from the urging member 30. It will be caught. Therefore, the interval maintaining member 18 is in a state in which it cannot be displaced relative to the image sensor 15 in the vertical direction.

  The interval maintaining member 17 also has a convex portion, and the convex portion is fitted into the concave portion on the image sensor 15 side, so that it cannot be displaced relative to the image sensor 15 in the main scanning direction and the sub scanning direction. However, since the structure is substantially the same as that of the interval maintaining member 18, the illustration is omitted.

  On the other hand, the interval maintaining member 18 is also provided with a structure not provided on the interval maintaining member 17 side. Specifically, in the gap maintaining member 18, the roller holder 18B has a bearing 31B as shown in FIG. 4 (d), FIG. 4 (e), FIG. 6 (a), and FIG. A gap 41 into which the tip enters is secured. Of the wall surfaces 43A and 43B on both sides in the front-rear direction across the gap 41, one wall surface 43B is formed with a rib 45 that contacts the bearing portion 31B. As shown in FIG. 5E, the rib 45 has a shape extending in the vertical direction.

  In a state where the interval maintaining member 18 is attached to the image sensor 15, the rib 45 of the interval maintaining member 18 abuts on the bearing portion 31B of the carriage 13 at the tip in the protruding direction, and the bearing portion 31B is interposed between the wall surface 43A. Sandwich. As a result, the interval maintaining member 18 cannot be displaced relative to the carriage 13 in the main scanning direction.

[Action and effect]
In the reading unit 3 provided in the multifunction device 1, since the guide rail 11 is made of resin, depending on the installation state of the apparatus, the guide rail 11 may be more than the conventional product that employs a metal guide shaft. The bending tends to increase.

  When the deflection of the guide rail 11 increases, the carriage 13 that moves in the sub-scanning direction along the guide rail 11 is positioned farther from the contact glass 4 side than the standard position (see the right side in FIG. 7) (see FIG. 7). (See the left side of 7). The amount of displacement at this time is larger than that of a conventional product that employs a metal guide shaft.

  On the other hand, the image sensor 15 and the interval maintaining members 17 and 18 can be displaced in the vertical direction relative to the carriage 13 and are urged toward the contact glass 4 by the urging member 30. Therefore, even if the carriage 13 is separated from the contact glass 4 side as described above (see the left side of FIG. 7), the image sensor 15 and the spacing maintaining members 17 and 18 are not separated from the contact glass 4 side. 4 moves in the sub-scanning direction along the lower surface. In this state, the gap maintaining members 17 and 18 function as spacers that keep the gap between the image sensor 15 and the lower surface of the contact glass 4 constant.

  Here, in the conventional product in which the image sensor 15 moves up and down relatively with respect to the carriage 13, a convex portion that fits into the concave portion is provided on the carriage 13 side in accordance with the concave portion on the image sensor 15 side. By fitting the convex portion into the concave portion, the image sensor 15 is restricted from being displaced relative to the carriage 13 in the main scanning direction.

  Therefore, even if the image sensor 15 and the distance maintaining member 18 are not separated from the contact glass 4 side as described above, when the carriage 13 is separated from the contact glass 4 side more than the conventional product, the convex portion is removed from the concave portion. In this case, the displacement of the image sensor 15 cannot be properly regulated.

  As a method of preventing the convex portion from coming out of the concave portion even when the image sensor 15 moves up and down more greatly, the concave portion is deepened, the convex portion is lengthened, and the stroke length in the vertical direction is secured. There is also a method. However, since the image sensor 15 is a precision component having an optical mechanism and an electrical mechanism, it is difficult to change the shape so as to make the recess deeper, unlike a resin molded product.

  In this respect, in the reading unit 3 exemplified in the present embodiment, the interval maintaining member 18 contacts the bearing portion 31B of the carriage 13 so that the interval maintaining member 18 is displaced relative to the carriage 13 in the main scanning direction. Is regulated. Unlike the image sensor 15, the gap maintaining member 18 and the carriage 13 are not precision parts having an optical mechanism or an electric mechanism, but are parts that can be manufactured by molding resin. Can be designed relatively freely.

  Therefore, even when the carriage 13 is more distant from the contact glass 4 than the conventional product, designing the shape so as to maintain the contact between the distance maintaining member 18 and the carriage 13 is much more than changing the shape of the image sensor 15. This makes it possible to secure a stroke length that can maintain the contact with the distance maintaining member 18 even when the carriage 13 is displaced more greatly, and the displacement of the image sensor 15 can be appropriately regulated.

  Accordingly, the displacement of the image sensor 15 can be appropriately regulated despite the use of the resin guide rail 11 that is more easily deformed than the metal guide shaft, so that the image reading quality can be improved. it can.

  In the present embodiment, the interval maintaining member 18 can be attached to the upper surface side of the image sensor 15 by fitting the protrusions 37A and 37B into the recesses 39A and 39B. It is possible to prevent relative displacement.

  Further, in the present embodiment, the relative positional relationship between the carriage 13 and the distance maintaining member 18 is determined by bringing the tip end of the rib 45 formed in the distance maintaining member 18 into contact with the bearing portion 31B. Positioning can be performed in the scanning direction. In addition, since the rib 45 has a shape extending in the vertical direction, even if the carriage 13 and the interval maintaining member 18 are relatively displaced in the vertical direction, the rib 45 can be maintained in a positioned state. . Further, if the positioning is performed at the leading end of the rib 45 in the protruding direction, the contact area of the contact portion can be reduced as compared with the case where the ribs 45 are in contact with each other. The frictional resistance generated when displacing in the direction can be reduced.

  Further, when the rib 45 is brought into contact with the bearing portion 31B in this way, the bearing portion 31B can be used as a member for holding the image sensor 15 and a member for positioning with the interval maintaining member 18, and therefore the bearing portion 31B. Apart from the case where a positioning portion is provided separately, a required structure can be reduced and a compact structure can be achieved.

[Other Embodiments]
As mentioned above, although embodiment of this invention was described, this invention is not limited to said specific one Embodiment, In addition, it can implement with a various form.

  For example, in the above embodiment, the rib 45 is formed on the spacing maintaining member 18 side, but the rib is formed on the carriage 13 side (for example, the bearing portion 31B), and the leading end of the rib in the protruding direction is maintained. You may contact | abut to the member 18 side.

  In the above-described embodiment, the image reading apparatus configured as a multifunction machine is illustrated as an example of the image reading apparatus of the present invention. However, whether or not the image reading apparatus is configured as a multifunction machine is arbitrary, and single-function image reading is performed. The configuration of the present invention may be employed in an apparatus, a copier, a facsimile machine, and the like.

  DESCRIPTION OF SYMBOLS 1 ... MFP, 2 ... Main unit, 3 ... Reading unit, 3A ... Reading unit main body, 3B ... Document cover, 4 ... Contact glass, 7 ... Operation panel, 8 ... Recording medium outlet, 9A, 9B ... Paper feed cassette, 11 ... Guide rail, 13 ... Carriage, 15 ... Image sensor, 17, 18 ... Space maintenance member, 17A, 18A ... roller, 17B, 18B ... roller holder, 21 ... housing, 23 ... sliding member, 25 ... timing belt, 27 ... gear mechanism, 29 ... Stepping motor, 30 ... biasing member, 31A, 31B ... bearing, 33A, 33B ... projection, 35A, 35B ... shaft, 37A, 37B ... convex, 39A, 39B ... Recesses, 41 ... Gap 43A, 43B ··· wall, 45 ... ribs.

Claims (3)

A document placement table having a first surface and a second surface in a positional relationship on the front and back, and a document placed on the first surface side;
Two directions parallel to and perpendicular to the first surface of the document table are defined as a main scanning direction and a sub-scanning direction at a position facing the second surface of the document table with a predetermined interval. A resin guide portion extending along the sub-scanning direction;
A movable part that moves in the sub-scanning direction along the guide part while maintaining contact with the guide part;
A plurality of light receiving elements that are attached to the movable portion and move in the sub-scanning direction together with the movable portion, and are placed on the first surface of the document placement table by a plurality of light receiving elements arranged along the main scanning direction. A reading unit that reads an image of a scanned document;
An urging unit that urges the reading unit toward the second surface of the document table;
The reading unit and the second surface of the document table are attached to the reading unit and sandwiched between the reading unit and the second surface of the document table by the force from the biasing unit. An interval maintaining unit that keeps the interval of
The reading unit can be relatively displaced in a direction perpendicular to both the main scanning direction and the sub-scanning direction and relatively movable in the sub-scanning direction with respect to the movable unit. It has an undisplaceable structure,
The interval maintaining unit is structured such that the mounting structure for the reading unit is relatively undisplaceable relative to the reading unit in the main scanning direction and the sub-scanning direction, and is in contact with the movable unit. Thus, the image forming apparatus is characterized in that the distance maintaining unit is configured not to be relatively displaceable in the main scanning direction with respect to the movable unit. One of the interval maintaining unit and the reading unit is provided with a convex portion protruding toward the other, the other is provided with a concave portion into which the convex portion is fitted, and the convex portion is the concave portion. 2. The image reading apparatus according to claim 1, wherein the gap maintaining unit is relatively undisplaceable relative to the reading unit in the main scanning direction and the sub-scanning direction. Either one of the movable portion and the interval maintaining portion is formed with a rib having a shape in which a portion protruding toward the other extends in a direction orthogonal to both the main scanning direction and the sub-scanning direction. In addition, when the leading end of the rib in the protruding direction is in contact with the other, the distance maintaining portion is relatively undisplaceable in the main scanning direction with respect to the movable portion. Item 3. The image reading apparatus according to Item 2.

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