JP4285412B2 - Image reading apparatus and image forming apparatus having the same - Google Patents

Description

  The present invention relates to an image reading apparatus that reads a document image and an image forming apparatus that includes the image reading apparatus.

  2. Description of the Related Art Conventionally, so-called MFPs (multifunction printers) that integrate functions such as a scanner, printer, copy, and fax have been actively developed. In such an MPF scanner unit, light corresponding to a document image is received by a line sensor (for example, CCD) through a reading lens.

  Here, with the operation of the scanner unit, the temperature of the line sensor rises. For example, when the fixing unit of the printer unit is located below the reading lens or the line sensor of the scanner unit, the heat of the printer unit is transmitted to the scanner unit. Therefore, the temperature change at the scanner section becomes severe. When there is such a temperature change in the scanner section, the reading lens changes in shape similarity, and its refractive index also changes.

  At this time, if the position of the reading lens and the line sensor is fixed, and the relative distance between them is always constant, the change of the refractive index due to the temperature change of the reading lens causes a focus shift (focus shift) with respect to the line sensor. Causes image quality degradation.

Therefore, in Patent Document 1, for example, as shown in the plan view of FIG. 11, two corrections for expanding and contracting the lens group 101 constituting the imaging optical system and the substrate 103 supporting the light receiving element 102 due to temperature change. They are connected via members 104 and 105. In this configuration, since the relative distance between the lens 101 and the light receiving element 102 changes according to the temperature change due to the expansion and contraction of the two correction members 104 and 105, the focus shift based on the temperature change generated in the entire optical system is corrected. The
Japanese Patent No. 2603849

  However, in the configuration of Patent Document 1, since the lens group 101 and the substrate 103 are connected by the two correction members 104 and 105, the optical axis direction of the substrate 103 due to the expansion and contraction of the two correction members 104 and 105 is increased. Movement is not stable. Further, if there is a difference in the amount of expansion / contraction between the correction members 104 and 105, even if there is a difference, a focus shift occurs in a part of the light receiving element 102 on the substrate 103 (for example, one end in the main direction). As a result, there arises a problem that image quality deteriorates in a part of the read image.

  The present invention has been made to solve the above-described problems, and its purpose is to stably and evenly align the entire light receiving element with respect to the lens in the direction of the optical axis even when the in-machine temperature changes. An object of the present invention is to provide an image reading apparatus that can be moved, thereby suppressing deterioration in image quality of the entire read image, and an image forming apparatus including the image reading apparatus.

An image reading apparatus according to the present invention receives reflected light obtained by irradiating a document with light by a light receiving element arranged in a line in the main direction via at least one lens, thereby producing a document image. A lens barrel that holds the lens, a holding unit that holds the light receiving element, and a coupling unit that couples the lens barrel and the holding unit. has an elastic member which expands and contracts in the optical axis direction in accordance with a temperature change, the elastic member is a cylindrical covering the optical axis, and is formed in a symmetrical shape with respect to the optical axis in the main direction The telescopic members have surfaces formed on the lens barrel side and the holding unit side so as to be orthogonal to the optical axis and to surround the optical axis, respectively. Above lens barrel and above The holding unit is fixed in the optical axis direction, and the plane portions of the first mounting member and the second mounting member respectively formed from flat plates are in contact with the respective surfaces over both ends in the main direction, The expansion member, the lens barrel, and the holding unit are fixed through the first attachment member and the second attachment member, respectively.
Further, the image reading apparatus of the present invention receives reflected light obtained by irradiating light on a document with a light receiving element arranged in a line in the main direction via at least one lens, An image reading apparatus for reading a document image, comprising: a lens barrel that holds the lens; a holding unit that holds the light receiving element; and a coupling unit that couples the lens barrel and the holding unit. The coupling unit has an expansion / contraction member that expands and contracts in the optical axis direction according to a temperature change, and the expansion / contraction member has a cylindrical shape that covers the optical axis and is symmetrical with respect to the optical axis in the main direction. A plurality of ribs formed in a direction perpendicular to the optical axis and extending in the optical axis direction, and the plurality of ribs allow the lens barrel side end of the telescopic member and the rib to be formed. Holding unit It is characterized in that the side edges are connected.
Further, the image reading apparatus of the present invention receives reflected light obtained by irradiating light on a document with a light receiving element arranged in a line in the main direction via at least one lens, An image reading apparatus for reading a document image, comprising: a lens barrel that holds the lens; a holding unit that holds the light receiving element; and a coupling unit that couples the lens barrel and the holding unit. The coupling unit has an expansion / contraction member that expands and contracts in the optical axis direction according to a temperature change, and the expansion / contraction member has a cylindrical shape that covers the optical axis and is symmetrical with respect to the optical axis in the main direction. And the coupling unit is fixed in contact with the surface of the telescopic member on the lens barrel side in the optical axis direction and fixed to an installation plate on which the lens barrel is installed. It further has a mounting member The lens barrel is installed on the installation plate so that the optical axis extends along the plane of the installation plate, and the first mounting member is a lower end of the telescopic member on the lens barrel side. The elastic member and the installation plate are fixed so that the portion abuts against the flat surface of the installation plate, and the holding unit side of the expansion member is a free end.
Further, the image reading apparatus of the present invention receives reflected light obtained by irradiating light on a document with a light receiving element arranged in a line in the main direction via at least one lens, An image reading apparatus for reading a document image, comprising: a lens barrel that holds the lens; a holding unit that holds the light receiving element; and a coupling unit that couples the lens barrel and the holding unit. The coupling unit has an expansion / contraction member that expands and contracts in the optical axis direction according to a temperature change, and the expansion / contraction member has a cylindrical shape that covers the optical axis and is symmetrical with respect to the optical axis in the main direction. The outer surfaces located on both sides in the sub direction across the optical axis of the elastic member are formed so that the distance between these surfaces is narrower on the holding unit side than on the lens barrel side. That features It is.

  According to the above configuration, the lens barrel holds at least one lens (for example, a resin lens), and the holding unit holds light receiving elements (for example, line sensors) arranged in a line shape in the main direction. is doing. The lens barrel and the holding unit are coupled via a coupling unit having an elastic member. The expansion / contraction member expands / contracts in the optical axis direction according to a temperature change.

  Here, since the expansion / contraction member is formed in a cylindrical shape covering the optical axis of the lens, a surface perpendicular to the optical axis (hereinafter also referred to as a first surface) is disposed on the lens barrel side of the expansion / contraction member. A surface perpendicular to the optical axis (hereinafter also referred to as a second surface) can be formed on the surface of the elastic member on the holding unit side so as to surround the optical axis. . The telescopic member can be fixed to the lens barrel and the optical axis direction via the first surface, and the telescopic member can be fixed to the holding unit and the optical axis direction via the second surface. As a result, the expansion / contraction member can be stably fixed to the lens barrel and the holding unit in the optical axis direction, and the light receiving element of the holding unit can be stably moved in the optical axis direction by the expansion / contraction of the expansion / contraction member.

  In addition, since the expansion / contraction member is formed in a symmetric shape with respect to the optical axis in the main direction, the expansion / contraction method of the expansion / contraction member is the same on both sides in the main direction with respect to the optical axis. A difference in the amount of expansion / contraction in the optical axis direction between the expansion / contraction members on both sides in the main direction can be eliminated. Thereby, the difference in the movement amount in the optical axis direction at both ends in the main direction of the light receiving element can be eliminated, and the light receiving element can be moved uniformly in the optical axis direction. As a result, it is possible to suppress a focus shift (one-sided blur) at one end portion in the main direction of the light receiving element, and it is possible to suppress image quality deterioration of the entire read image.

  Here, the expandable member has surfaces (first surface and second surface) orthogonal to the optical axis on the lens barrel side and the holding unit side, and the lens is interposed through these surfaces. It is desirable that the lens barrel and the holding unit are fixed in the optical axis direction.

  In the case of this configuration, the elastic member can be stably fixed to the lens barrel via the first surface and can be stably fixed to the holding unit via the second surface. Further, the entire holding unit can be stably moved in the optical axis direction via the second surface when the elastic member expands and contracts in the optical axis direction.

  Moreover, it is desirable that the expandable member is formed in a shape symmetric with respect to the optical axis in the sub direction. In this case, the expansion / contraction member has the same expansion / contraction method on both sides in the sub-direction with respect to the optical axis, so that the difference in expansion / contraction amount of the expansion / contraction member on the both sides in the sub-direction with respect to the optical axis can be eliminated. it can. Thereby, it is possible to prevent the light receiving element of the holding unit coupled to the coupling unit having the telescopic member from tilting in the sub direction, and to reliably guide the light incident through the lens of the lens barrel to the light receiving element. Can do.

  Further, it is desirable that the expansion / contraction member also serves as a light shielding member that blocks stray light from entering the optical path between the lens barrel and the holding unit. In this case, the expansion / contraction member can prevent the stray light from entering the optical path without newly providing a light shielding member. As a result, it is possible to avoid the deterioration of the image quality of the read image due to the stray light with a simple configuration.

  The lens barrel may hold at least one resin lens. Resin lenses are likely to change in shape and change in refractive index more easily than glass lenses due to temperature changes. However, according to the present invention, even when the lens barrel holds such a resin lens, both ends in the main direction of the light receiving element are formed by expansion and contraction in the optical axis direction of the expansion and contraction member according to temperature change. The amount of movement in the optical axis direction can be made uniform, and the effects described above can be obtained.

  Further, the coupling unit includes a first attachment member fixed in contact with the surface on the lens barrel side of the telescopic member in the optical axis direction and fixed to an installation plate on which the lens barrel is installed. It is desirable to have more.

  In this configuration, the telescopic member is fixed to the installation plate on which the lens barrel is installed via the first mounting member that is in contact with and fixed to the lens barrel side surface in the optical axis direction. That is, the telescopic member is fixed to the installation plate via the first mounting member on the lens barrel side. Thereby, the holding unit side of the telescopic member becomes a free end, and the holding unit side of the telescopic member can be made telescopic.

  The first mounting member is preferably fixed to the telescopic member and the installation plate so that a lower end portion of the telescopic member on the lens barrel side contacts the installation plate.

  If a gap is formed between the lower end of the expansion / contraction member and the installation plate, vibration when the device is driven is transmitted to the expansion / contraction member via the first mounting member, and is amplified there. In some cases, the light receiving element of the held unit is further shaken, which adversely affects image reading. However, in the above configuration, since the lower end portion of the expansion / contraction member on the lens barrel side is in contact with the installation plate, the expansion / contraction member is prevented from shaking due to vibration when the apparatus is driven while the holding unit side of the expansion / contraction member can be expanded / contracted. It is possible to suppress as much as possible and to prevent the light receiving element from greatly shaking, and to avoid the inconvenience described above.

  The first mounting member is fixed to the expansion member and the installation plate so that the expansion member (the lower end portion thereof) and the installation plate face each other with a gap (in the sub direction) interposed therebetween. The urging member that urges the elastic member in the direction of the installation plate may be fixed to the installation plate.

  Since there is a gap in the sub direction between the expansion member and the installation plate, for example, an adjustment member that adjusts the inclination in the sub direction with respect to the optical axis of the expansion member can be positioned in the gap. As such an adjusting member, for example, a bolt that is screwed with an installation plate and advances and retracts in the sub-direction while coming into contact with the elastic member can be considered. Thereby, it is possible to finely adjust the position in the sub direction of the light receiving element of the holding unit coupled to the coupling unit having the elastic member and the tilt in the sub direction with respect to the optical axis.

  In addition, when a gap is formed between the expansion / contraction member (the lower end portion thereof) and the installation plate, the vibration at the time of driving the device is transmitted to the expansion / contraction member via the first attachment member as described above, and is amplified there. As a result, the light receiving element of the holding unit coupled to the coupling unit may be further shaken to adversely affect image reading. However, in the above configuration, since the elastic member is urged in the direction of the installation plate by the urging member, it is possible to suppress the elastic member from swaying as much as possible due to vibration during driving of the device, and to greatly sway the light receiving element as much as possible. It is possible to suppress the above disadvantages.

  The adjusting plate adjusts the inclination of the expansion / contraction member in the sub direction with respect to the optical axis by moving forward / backward with respect to the installation plate while contacting the expansion / contraction member through the gap. (For example, a bolt that is screwed to the installation plate) may be provided. In this case, since the inclination of the sub-direction with respect to the optical axis of the expansion / contraction member can be finely adjusted by the advance / retreat of the adjustment member in the sub-direction, the position in the sub-direction of the light receiving element of the holding unit coupled to the coupling unit having the expansion / contraction member And the tilt in the sub direction with respect to the optical axis can be finely adjusted.

  The coupling unit further includes a second attachment member that is in contact with and fixed to the surface of the elastic member on the holding unit side, and the holding unit includes a fixed substrate to which the light receiving element is fixed. And a third mounting member for coupling the second mounting member of the coupling unit and the fixed substrate, wherein the third mounting member has a coupling position with the second mounting member. In addition, each of the both ends in the main direction may have a coupling position adjusting unit for adjusting in the optical axis direction.

  In this case, the coupling position adjusting unit adjusts the coupling position of the third mounting member of the holding unit and the second mounting member of the coupling unit in the optical axis direction at each of both ends in the main direction. Due to the mounting error between the mounting member and the third mounting member, a focus shift (single blur) occurs at one end in the main direction of the light receiving element on the fixed substrate fixed to the third mounting member in advance. It can be lost.

  Moreover, it is desirable that the expansion / contraction member has a rib (convex portion) protruding in a direction orthogonal to the optical axis (for example, a sub direction). Since the elastic member has such ribs, it is possible to suppress the bias of (thermal) deformation of the elastic member due to temperature change, and the elastic member can be stably kept in the optical axis direction in any part of the main direction. Can be expanded and contracted.

  At this time, if the rib is formed to extend in at least one of the main direction and the optical axis direction on the outer surface exposed in the sub-direction of the elastic member, the above effect can be obtained. It can be obtained more reliably.

  An image forming apparatus of the present invention includes the above-described image reading apparatus of the present invention and an image forming unit that forms the image on a recording medium based on image data read by the image reading apparatus. It is characterized by that.

  According to the configuration of the image reading apparatus, it is possible to suppress deterioration in image quality of the entire read image due to a temperature change in the apparatus. Therefore, based on image data read by such an image reading apparatus, an image forming unit When the above image is formed on the recording medium, a good quality image can be obtained on the recording medium.

  According to the present invention, the expansion / contraction member of the coupling unit is formed in a cylindrical shape that covers the optical axis and is symmetrical with respect to the optical axis in the main direction. By extending and contracting in the optical axis direction, the movement amounts in the optical axis direction of both ends in the main direction of the light receiving element can be made uniform. As a result, it is possible to suppress a focus shift at one end portion in the main direction of the light receiving element, and it is possible to suppress deterioration in image quality of the entire read image.

[Embodiment 1]
An embodiment of the present invention will be described below with reference to the drawings. In each drawing, of three directions perpendicular to each other, the main direction is the X direction, the sub direction is the Y direction, and the optical axis direction is the Z direction. Here, the main direction refers to the direction in which a later-described line sensor 32 (see FIG. 1) extends, and the sub direction refers to the direction perpendicular to the ZX plane.

(1. About image forming apparatus)
FIG. 2 is a perspective view showing a schematic configuration of the image forming apparatus of the present embodiment. This image forming apparatus is an MFP in which functions such as a scanner, a printer, a copy, and a FAX are integrated, and includes at least a scanner unit 1, a printer unit 2, a paper feed unit 3, and a discharge unit 4.

  The scanner unit 1 is an image reading device that reads a document image by receiving reflected light obtained by irradiating light on the document with a line sensor 32 (see FIG. 1) via at least one lens. . The detailed configuration of the scanner unit 1 will be described later.

  The printer unit 2 is an image forming unit that forms the image on a recording medium such as paper based on image data read by the scanner unit 1. The image forming unit includes an exposure unit, a developing unit, a transfer unit, a fixing unit, and the like (not shown), and forms an image on a sheet by a known electrophotographic process.

  The paper feed unit 3 supplies paper to the transfer unit of the printer unit 2. The discharge unit 4 discharges the sheet from the fixing unit of the printer unit 2.

  In other words, in the image forming apparatus, the document image read by the scanner unit 1 is printed on the paper fed from the paper feeding unit 3 by the printer unit 2. Then, the paper on which the document image is formed is discharged from the discharge unit 4.

(2. Detailed configuration of the scanner unit)
Next, a detailed configuration of the scanner unit 1 will be described. FIG. 3 is a cross-sectional view taken along the line AA ′ when the scanner unit 1 of FIG. 2 is cut along a cross section including the lens optical axis L. The scanner unit 1 includes a document placing table 5, a first scanning unit 6, a second scanning unit 7, a light receiving unit 8, and a sheet through reading unit 9.

  The document placing table 5 is a table on which a document to be read is placed, and is made of, for example, glass. Note that a belt-type ADF (automatic document feeder) may be attached to the document table 5.

  The first scanning unit 6 includes an illumination lamp 10, a sub-reflecting mirror 11, and a first folding mirror 12. The illumination lamp 10 directly irradiates light on the document placed on the document table 5 and also irradiates the document through the sub-reflecting mirror 11. For example, at the time of reading a book document, there is a portion where the light directly radiated from the illumination lamp 10 does not reach, but the above portion can be obtained by irradiating the document with the light from the illumination lamp 10 also through the sub-reflector 11. Further, it is possible to irradiate light, and it is possible to avoid a shadow on the read image. The first folding mirror 12 reflects the reflected light from the document and guides it to the second scanning unit 7.

  The second scanning unit 7 includes a second folding mirror 13 and a third folding mirror 14, and the light from the first scanning unit 6 is sequentially reflected by these folding mirrors 8 to receive the light receiving unit 8. Lead to.

  The light receiving unit 8 includes a lens unit 15, a coupling unit 16, and a holding unit 17. The lens unit 15 holds at least one lens. The coupling unit 16 couples the lens unit 15 and the holding unit 17 in the optical axis direction. The holding unit 17 holds a line sensor 32 (see FIG. 1). The detailed configuration of the light receiving unit 8 will be described later.

  The sheet-through reading unit 9 is a part that reads a document image simultaneously with conveyance, and is configured by, for example, ADF.

  In the above configuration, when reading an image of a book document placed on the document placement table 5 or a document conveyed to the document placement table 5 with a belt-type ADF, an image reading signal is turned on by pressing a start button (not shown). Thus, the first scanning unit 6 and the second scanning unit 7 move to initial positions B and C corresponding to the leading edge of the document image, respectively.

  From this state, when the illumination lamp 10 of the first scanning unit 6 is turned on, the light from the illumination lamp 10 is applied to the document on the document table 5. Then, the reflected light of the document image is reflected by the first folding mirror 12 and guided to the second scanning unit 7.

  The reflected light of the document image incident on the second scanning unit 7 is sequentially reflected by the second folding mirror 13 and the second folding mirror 14 and guided to the light receiving unit 8. The light incident on the light receiving unit 8 is received by the line sensor 32 of the holding unit 17 through the lens unit 15 and the coupling unit 16. Thereby, one line of the document image is read.

  The first scanning unit 6 scans the document image from the leading edge to the trailing edge by moving from the initial position B corresponding to the leading edge of the document image to the final position B ′ corresponding to the trailing edge of the document image. . At this time, the second scanning unit 7 moves from the initial position C corresponding to the leading edge of the document image to the final position C ′ corresponding to the trailing edge of the document image as the first scanning unit 6 moves. . By such an operation, the document image is read by the line sensor 32 of the light receiving unit 8 for each line, and finally the entire document image is read.

  On the other hand, when the original image is read by the sheet through reading unit 9, the first scanning unit 6 and the second scanning unit 7 move to the reading position in the sheet through and stop at that position from the start of reading to the end of reading. Keep the state. In this state, the document image is conveyed by the sheet through reading unit 9 and at the same time, the document is irradiated with light from the illumination lamp 10. Thereby, the reflected light for each line of the document image is received by the line sensor 32 of the light receiving unit 8 via the first scanning unit 6 and the second scanning unit 7, and finally the entire document image is read. .

(3. Detailed configuration of the light receiving unit)
Next, a detailed configuration of the light receiving unit 8 will be described. FIG. 4 is a perspective view showing a schematic configuration of the light receiving unit 8, and FIG. 5 is an exploded perspective view of the light receiving unit 8. FIG. 1 is an exploded perspective view when the main part of the light receiving unit 8 is viewed obliquely from above, and FIG. 6 is an exploded perspective view when the main part of the light receiving unit 8 is viewed obliquely from below. As illustrated in FIG. 4, the light receiving unit 8 includes the lens unit 15, the coupling unit 16, and the holding unit 17 as described above.

(3-1. Lens part)
As shown in FIG. 5, the lens unit 15 includes a front group 15F and a rear group 15R. The front group 15 </ b> F has lenses 18, 19, 20, and 21 and a ball frame 22. The lenses 18, 19, 20, and 21 are provided in this order from the light incident side along the optical axis, and are fixed in the ball frame 22 by a holding member (not shown). On the other hand, the rear group 15R includes a lens 23, a leaf spring 24, and a lens barrel 25. The lens 23 is fixed in the lens barrel 25 by a leaf spring 24.

  In the present embodiment, from the viewpoint of suppressing chromatic aberration, the lenses 19 and 20 of the front group 15F are made of glass lenses. Further, from the viewpoint of cost reduction, the other lenses 18 and 21 of the front group 15F and the lens 23 of the rear group 15R are made of resin lenses.

The lens frame 22 and the lens barrel 25 are made of resin. In the present embodiment, the lens frame 22 and the lens barrel 25 are made of a resin material having a linear expansion coefficient of 3 to 4 × 10 ⁻⁵ in consideration of the characteristics of the lens unit 15 due to temperature changes in the machine and the lens ball holding performance. It is formed with.

  The lens barrel 25 includes a ball frame holding portion 26 and a main body 27, which are integrally formed in the optical axis direction. The lens 23 of the rear group 15R is disposed in the main body 27.

  The ball frame holding portion 26 holds the ball frame 22 of the front group 15F, and is formed in a substantially cylindrical shape. Two screw holes 26 a are formed in the outer wall of the ball frame holding portion 26. A fitting hole 26 b into which the ball frame 22 is fitted is formed on the light incident side of the ball frame holding portion 26. Accordingly, the front frame 15F and the rear group 15R are connected by fitting the ball frame 22 into the fitting hole 26b and fastening the ball frame 22 to the ball frame holding portion 26 with screws through the two screw holes 26a. It can be handled as one lens unit. From such a configuration, it can be said that the lens barrel 25 holds at least one lens (including a resin lens).

  Further, the front group 15F can be marked with an angle at which an optimum MTF (Modulation Transfer Function) can be obtained with respect to the rear group 15R around the optical axis when the single unit is completed. By defining the angle around the optical axis when fitting the rear group 15F to the rear group 15R in this way, the lens unit 15 with better optical characteristics can be obtained.

  In addition, two fixing auxiliary members 26 c for fixing the lens barrel 25 to the installation plate 28 are provided on the outer wall of the lens frame holding portion 26, and the fixing auxiliary member 26 c is screwed to the installation plate 28. As a result, the lens barrel 25 is positioned and fixed with respect to the installation plate 28.

(3-2. Coupling unit)
As shown in FIGS. 1 and 5, the coupling unit 16 includes a telescopic member 29, a first attachment member 30, and a second attachment member 31.

The expansion / contraction member 29 expands and contracts in the optical axis direction according to a temperature change, and is made of, for example, resin. The expansion / contraction member 29 is formed of a resin material having a linear expansion coefficient of 6 to 7 × 10 ⁻⁵ in consideration of a focus correction amount due to a temperature change.

  The elastic member 29 is formed in a cylindrical shape that covers the optical axis. As such a shape, the shape of the opening of the expansion / contraction member 29 on the lens barrel 25 side can be considered to be, for example, a polygon including a substantially square, a circle, or an ellipse. In the embodiment, the opening has a shape that is substantially square. Thus, since the expansion / contraction member 29 is formed in a cylindrical shape, light (stray light) outside the light receiving unit 8 does not enter the optical path between the lens barrel 25 and the holding unit 17. That is, entry of stray light into the optical path is blocked by the elastic member 29. Therefore, the elastic member 29 also has a function as a light shielding cover (light shielding member) that blocks stray light from entering the optical path.

  In addition, the outer surfaces located on both sides in the main direction across the optical axis of the telescopic member 29 are a single plane along the optical axis, but the outer surfaces located on both sides in the sub direction across the optical axis are The distance between these surfaces is formed so as to be narrowed stepwise from the light incident side toward the light emitting side. As a result, the expansion / contraction member 29 has a symmetrical shape with respect to the optical axis in both the main direction and the sub direction. In addition, the external appearance of the expansion-contraction member 29 may be a substantially rectangular parallelepiped shape as a whole.

  The surfaces of the telescopic member 29 on the lens barrel 25 side and the holding unit 17 side are surfaces orthogonal to the optical axis. For convenience of explanation below, the surface of the expansion / contraction member 29 on the lens barrel 25 side, which is perpendicular to the optical axis, is referred to as a first surface 29a, and the surface of the expansion / contraction member 29 on the holding unit 17 side. Therefore, a surface orthogonal to the optical axis is referred to as a second surface 29b. The first surface 29a and the second surface 29b of the expansion / contraction member 29 are formed in a cylindrical shape covering the optical axis, so that the expansion member 29 itself surrounds the optical axis, that is, an opening through which a light beam passes. It is formed to have a part inside. The telescopic member 29 is fixed in the optical axis direction with the lens barrel 25 through the first surface 29a, and is fixed in the optical axis direction with the holding unit 17 through the second surface 29b. .

  Further, on the first surface 29a of the elastic member 29, bosses 29c into which screws for screwing to the first mounting member 30 are fitted are formed in the vicinity of both ends in the main direction. On the other hand, on the second surface 29b of the expansion / contraction member 29, bosses 29d (see FIG. 6) into which screws for screwing to the second attachment member 31 are formed are formed in the vicinity of both ends in the main direction. Yes.

  The elastic member 29 has a rib 29e that protrudes in a direction (for example, the sub direction) perpendicular to the direction of expansion (optical axis direction) on the outer surface exposed in the sub direction. In the present embodiment, the rib 29e is formed on the outer surface so as to extend in both the main direction and the optical axis direction. When the expansion / contraction member 29 has such a rib 29e, when the expansion / contraction member 29 expands / contracts in the optical axis direction due to a temperature change, the thermal deformation is biased, for example, bulges in the center portion. Can be suppressed. Thereby, the elastic member 29 can be stably expanded and contracted in the optical axis direction at any part in the main direction.

  If the rib 29e is formed on the outer surface so as to extend in at least one of the main direction and the optical axis direction, the above effect can be obtained, but the main direction as in the present embodiment. If it is formed extending in both the optical axis direction and the optical axis direction, the effect can be ensured. Further, the provision of the rib 29e has an effect that the strength of the elastic member 29 can be secured to some extent.

  The first attachment member 30 is a component for attaching the elastic member 29 to the lens barrel 25, and is configured by bending a flat plate. More specifically, the first mounting member 30 has a substantially inverted U-shaped flat plate that is positioned perpendicular to the optical axis and outside the optical path, and that both ends in the main direction of the flat plate are parallel to the optical axis. It is formed by bending toward the lens barrel 25 side.

  Two holes 30a are formed at positions corresponding to the two bosses 29c formed on the first surface 29a of the elastic member 29 on the surface perpendicular to the optical axis of the first mounting member 30. . Thereby, the expansion-contraction member 29 and the 1st attachment member 30 can be fastened to an optical axis direction by inserting a screw in the boss | hub 29c through the hole 30a. As a result, the first attachment member 30 is fixed in contact with the first surface 29a of the elastic member 29 in the optical axis direction.

  The first mounting member 30 is also fixed to the lens barrel 25 in the optical axis direction by coming into contact with the upper edge 27a of the main body 27 of the lens barrel 25. Accordingly, the telescopic member 29 is coupled (fixed) to the lens barrel 25 in the optical axis direction via the first mounting member 30. The first mounting member 30 is also fixed to the installation plate 28 on which the lens barrel 25 is installed via the bent main direction both ends.

  As described above, since the coupling unit 16 includes the first mounting member 30, the telescopic member 29 is fixed to the installation plate 28 on the lens barrel 25 side via the first mounting member 30. Can do. As a result, the holding unit 17 side of the extendable member 29 can be a free end that is extendable in the optical axis direction.

  The second attachment member 31 is a component for attaching the holding unit 17 to the expansion / contraction member 29, and is configured by bending a flat plate. More specifically, the second mounting member 31 has a flat plate formed therein with an opening through which a light beam passes, and is positioned perpendicular to the optical axis, and one end portion (for example, the upper portion) of the flat plate is parallel to the optical axis. In this way, it is formed by bending toward the elastic member 29 side.

  Two holes 31a are formed at positions corresponding to the two bosses 29d formed on the second surface 29b of the extendable member 29 on the surface perpendicular to the optical axis of the second mounting member 31. . Thereby, the expansion-contraction member 29 and the 2nd attachment member 31 can be fastened to an optical axis direction by inserting a screw in the boss | hub 29d through the hole 31a. As a result, the second mounting member 31 is fixed in contact with the second surface 29b of the elastic member 29 in the optical axis direction.

  Further, as a result of bending a bent surface of the second mounting member 31, that is, a flat plate perpendicular to the optical axis, it is held at both ends in the main direction of the upper surface (hereinafter also referred to as the surface 31b) parallel to the optical axis. Holes 31c for screwing the third mounting member 34 of the unit 17 are formed.

(3-3. Holding unit)
The holding unit 17 includes a line sensor 32, a fixed substrate 33, and a third attachment member 34.

  The line sensor 32 includes a plurality of light receiving elements (for example, CCDs) arranged in the main direction, and reads a document image by receiving light corresponding to the document image for each scanning line. The fixed substrate 33 is formed of a flat plate perpendicular to the optical axis, and the line sensor 32 is fixed to the fixed substrate 33.

  The third attachment member 34 is a component that couples the second attachment member 31 of the coupling unit 16 and the fixed substrate 33, and is configured by bending a flat plate. More specifically, the third attachment member 34 has a flat plate formed therein with an opening through which a light beam passes, and is positioned perpendicular to the optical axis, and one end portion (for example, the upper portion) of the flat plate is parallel to the optical axis. In this way, it is formed by bending toward the elastic member 29 side. The third mounting member 34 is screwed to the fixed substrate 33 at the four corners of the surface perpendicular to the optical axis.

  Further, as a result of bending the bent surface of the third mounting member 34, that is, a flat plate perpendicular to the optical axis, both ends in the main direction of the upper surface (hereinafter also referred to as a surface 34a) parallel to the optical axis, Holes 34 b are formed at positions corresponding to the holes 31 c of the second mounting member 31 of the coupling unit 16. Thereby, if the surface 34a and the surface 31b are made to oppose and a screw is inserted in the hole 34b and the hole 31c, the 3rd attachment member 34 and the 2nd attachment member 31 can be fastened.

  Further, the two holes 34b formed in the surface 34a of the third mounting member 34 are long holes whose openings are long in the optical axis direction. As a result, when the second mounting member 31 and the third mounting member 34 are screwed together, the mounting position (coupling position) of the third mounting member 34 with respect to the second mounting member 31 is set to both ends in the main direction. In each of these, the adjustment can be made by shifting in the optical axis direction while observing the output of the line sensor 32. As a result, the one-side blur in the line sensor 32 can be eliminated beforehand. That is, the two holes 34b of the third mounting member 34 function as a coupling position adjusting unit for adjusting the coupling position in the optical axis direction at each of both ends in the main direction.

  When assembling the light receiving unit 8 having the above-described configuration, the front group 15F is fixed to the rear group 15R, and the lens unit 15 is completed. In addition, the line sensor 32 is fixed to the fixed substrate 33, and the fixed substrate 33 and the third attachment member 34 are fixed to complete the holding unit 17. The elastic member 29 is abutted and fixed in the optical axis direction with the first mounting member 30 on the first surface 29a, and the second mounting member 31 and the optical axis direction on the second surface 29b. Abut and fix. Then, the first mounting member 30 is fixed to the lens barrel 25 in the optical axis direction, and the lens barrel 25 and the first mounting member 30 are fixed to the installation plate 28. Further, the second attachment member 31 is fixed to the third attachment member 34 of the holding unit 17. Thereby, the light receiving unit 8 is completed.

  Here, when the first attachment member 30 is fixed to the installation plate 28, the lower end portion of the telescopic member 29 on the lens barrel 25 side is brought into contact with the installation plate 28. This not only determines the default position in the sub-direction of the line sensor 32 of the holding unit 17 integrated with the expansion and contraction member 29, but the line sensor 32 is greatly shaken by vibration during driving of the apparatus, resulting in trouble in image reading. This is to avoid this.

  That is, when the lower end portion of the expansion / contraction member 29 is lifted from the installation plate 28, vibration when the apparatus is driven is transmitted to the expansion / contraction member 29 via the first attachment member 30 and amplified there. As a result, the line sensor 32 of the holding unit 17 coupled to the coupling unit 16 is greatly shaken. However, if the lower end of the expansion / contraction member 29 is in contact with the installation plate 28, it is possible to suppress the expansion / contraction member 29 from greatly shaking when the apparatus is driven. It is possible to avoid troubles in reading.

(4. Operation and effect of light receiving unit)
When reading a book document or an image using a belt-type ADF, the temperature of the line sensor 32 rises, but heat generated in the fixing unit of the printer unit 2 below the scanner unit 1 is transmitted to the scanner unit 1. Thus, the temperature of the scanner unit 1 is more likely to rise. Furthermore, the heat generated during the moving scanning of the first scanning unit 6 and the second scanning unit 7 is agitated, and the temperature around the lens unit 15 rises in a complicated manner. Further, since the first scanning unit 6 and the second scanning unit 7 are stopped when the image is read by the sheet through type ADF, the first scanning unit 6 is also affected by heat generated by the illumination lamp 10 of the first scanning unit 6. Thus, the temperature around the lens unit 15 is different from that during the moving scanning of the first scanning unit 6 and the second scanning unit 7. Further, the temperature around the lens unit 15 varies depending on the use environment, the document size, and the like.

  On the other hand, in this embodiment, in order to realize the lens configuration at low cost, as described above, the lenses 18 and 21 of the front group 15F and the lens 23 of the rear group 15R are made of resin. Along with the temperature change, not only the similar deformation occurs, but also the refractive index changes. As a result, the line sensor 32 easily defocuses.

  If the temperature change around the lens unit 15 is simple, the line sensor 32 is shifted in advance in the optical axis direction, or multiple stages of settings are prepared depending on the image reading mode and usage conditions. Actually, however, since the temperature change around the lens unit 15 is various and complicated as described above, it is necessary to move the line sensor 32 to a position corresponding to the temperature at that time. .

  Therefore, in the present embodiment, a configuration is adopted in which the coupling unit 16 that couples the holding unit 17 that holds the line sensor 32 and the lens barrel 25 includes an expansion / contraction member 29 that expands and contracts in the optical axis direction according to a temperature change. ing. According to this configuration, since the expansion / contraction member 29 expands / contracts in the optical axis direction according to the temperature change, the relative distance between the lens unit 15 held by the lens barrel 25 and the line sensor 32 corresponds to the temperature change. Change. As a result, even if the lens of the lens unit 15 is similarly deformed due to a temperature change or the refractive index changes, the focus shift in the line sensor 32 can be eliminated to some extent.

  At this time, in this embodiment, the elastic member 29 is formed in a cylindrical shape covering the optical axis. As a result, a first surface 29a perpendicular to the optical axis can be formed on the lens barrel 25 side of the elastic member 29, and a second surface perpendicular to the optical axis can be formed on the holding unit 17 side of the elastic member 29. 29b can be formed. In addition, since the expandable member 29 has a cylindrical shape covering the optical axis, the first surface 29a and the second surface 29b are formed so as to surround the optical axis. Therefore, on the surface of the lens barrel 25 on the side of the telescopic member 29, the telescopic member 29 is moved in the optical axis direction via the first surface 29a at a part away from the optical axis and along the outer periphery around the optical axis. Can be fixed. Similarly, on the surface of the holding unit 17 on the side of the expansion / contraction member 29, the expansion / contraction member 29 is disposed in the optical axis direction via the second surface 29b at a part away from the optical axis and along the outer periphery around the optical axis. Can be fixed.

  As a result, the expansion / contraction member 29 can be stably fixed to the lens barrel 25 and the holding unit 17 in the optical axis direction, and the holding unit 17 and the line sensor 32 are expanded when the expansion / contraction member 29 expands / contracts in the optical axis direction due to a temperature change. Can be stably moved in the optical axis direction.

  Further, when the relative distance between the lens unit 15 and the line sensor 32 is changed due to the expansion / contraction of the expansion / contraction member 29, a difference occurs in the expansion / contraction amount in the optical axis direction at both ends in the main direction of the expansion / contraction member 29. If this is the case, since the correction amount for the focus shift differs between both ends in the main direction, the positional relationship between the lens unit 15 adjusted in advance and the line sensor 32 shifts, resulting in unnecessary image degradation. . Further, if the expansion / contraction (thermal deformation) is different at both ends in the main direction of the expansion / contraction member 29b, or if the first surface 29a and the second surface 29b of the expansion / contraction member 29 are significantly expanded due to thermal deformation, the surface contact This is a factor that causes excessive image degradation.

  However, in the present embodiment, since the expansion / contraction member 29 is formed in a shape symmetrical to the optical axis in the main direction, the deformation method of the expansion / contraction member 29 and the expansion / contraction in the optical axis direction are performed at both ends in the main direction. You can make the same way. Thereby, the difference in the movement amount in the optical axis direction at both ends in the main direction of the line sensor 32 can be reliably eliminated, and the line sensor 32 can be moved uniformly and reliably in the optical axis direction. Therefore, it is possible to reliably avoid the occurrence of excessive image degradation.

  That is, by forming the expansion / contraction member 29 in a cylindrical shape covering the optical axis and in a shape symmetrical to the main direction with respect to the optical axis, the holding unit 17 and the line sensor 32 can stably and uniformly emit light. It can be moved in the axial direction, and deterioration of the image quality of the entire read image can be suppressed.

  Moreover, in this embodiment, the expansion-contraction member 29 is formed in the shape symmetrical with respect to the optical axis also in the sub direction. In this case, the deformation of the expansion / contraction member 29 and the expansion / contraction in the optical axis direction can be made the same on both sides in the sub-direction with respect to the optical axis. Thereby, it is possible to prevent the line sensor 32 from being inclined in the sub direction, and light incident through the lens barrel 25 can be reliably guided to the line sensor 32.

  As described above, the extendable member 29 has the above-described shape, and the contact of the expandable member 29 with the lens barrel 25 in the optical axis direction is per surface through the first surface 29a. 17 is set in contact with the surface through the second surface 29b, and the lower end portion of the expansion / contraction member 29 is brought into contact with the installation plate 28, so that the one-blind adjustment is performed in advance. It is possible to correct a focus shift in the line sensor 32 due to a temperature change in the apparatus while maintaining a state in which the expansion and contraction member 29 is not affected by vibration during driving of the apparatus in a stable state without breaking. .

  Moreover, even if the lens unit 15 has a resin lens as in the present embodiment, correction of the focus shift with respect to the temperature change in the vicinity thereof, control for feeding back the temperature sensor and its signal, and feedback information are also provided. In addition, it can be performed without the need for moving means for moving the line sensor 32. That is, according to the present invention, it is possible to correct focus deviation with a low-cost and simple configuration by changing the shape and mounting method of the light-shielding cover, which is conventionally required, and utilizing the thermal deformation, and stable image reading. Is possible.

  In this embodiment, the lens frame 22 and the lens barrel 25 are made of resin, but may be made of a metal such as aluminum or brass, for example. Even in this case, if the material of the expansion / contraction member 29 is selected so that the lens characteristics and holding performance due to temperature changes and the amount of correction of focus deviation are appropriate, the same effects as in this embodiment can be obtained.

  In the present embodiment, a resin lens is used for a part of the lens unit 15, but all the lenses of the lens unit 15 may be glass lenses as long as the cost is not limited.

  In the present embodiment, the configuration in which the cylindrical expansion / contraction member 29 also serves as a light shielding cover has been described. However, the cylindrical expansion / contraction member 29 and the light shielding cover may be configured separately and provided separately. .

[Embodiment 2]
The following will describe another embodiment of the present invention with reference to the drawings. For convenience of explanation below, the same components as those in the first embodiment are denoted by the same member numbers, and description thereof is omitted.

  The image forming apparatus according to the present embodiment has the same configuration as that of the first embodiment except that a light receiving unit 8 '(see FIG. 7) is used instead of the light receiving unit 8 of the first embodiment. Hereinafter, the light receiving unit 8 'will be mainly described.

  FIG. 7 is a perspective view showing a schematic configuration of the light receiving unit 8 ′, and FIG. 8 is a side view of the light receiving unit 8 ′. FIG. 9 is an exploded perspective view when the main part of the light receiving unit 8 ′ is viewed obliquely from above. FIG. 10 is an exploded perspective view when the main part of the light receiving unit 8 ′ is viewed obliquely from below. is there. As shown in FIG. 7, the light receiving unit 8 ′ includes a lens unit 15, a coupling unit 16 ′, and a holding unit 17. The coupling unit 16 ′ has an elastic member 29 ′ (see FIGS. 8 to 10) instead of the elastic member 29.

The expansion / contraction member 29 ′ is different from the expansion / contraction member 29 in that the lower end portion of the expansion / contraction member 29 is a plane parallel to the installation plate 28 and is symmetrical only in the main direction, but other configurations and functions are expansion / contraction. The same as the member 29. The first attachment member 30 is fixed to the expansion / contraction member 29 ′ and the installation plate 28 so that the expansion / contraction member 29 ′ and the installation plate 28 face each other with a gap t in the sub direction.

Two leaf springs 35 (see FIG. 9) are fixed to the installation plate 28, and two stud bolts 36 (see FIG. 10) are screwed together. The leaf spring 35 is a biasing member that biases the holding unit 17 side of the elastic member 29 ′ toward the installation plate 28, and is provided on both sides in the main direction with respect to the optical axis. In FIG. 8, illustration of the leaf spring 35 on one side in the main direction is omitted for convenience. The implantation bolt 36 advances and retracts in the sub-direction with respect to the installation plate 28 while contacting the expansion / contraction member 29 'through the gap t between the expansion / contraction member 29' and the installation plate 28, whereby the light of the expansion / contraction member 29 ' It is an adjustment member that adjusts the inclination in the sub direction with respect to the shaft.

  In such a light receiving unit 8 ′, since there is a sub-direction gap t between the telescopic member 29 ′ and the installation plate 28, the stud bolt 36 can be positioned in the gap t ′. Therefore, if the implant bolt 36 is advanced and retracted in the sub direction, the position of the telescopic member 29 'in the sub direction can be finely adjusted, and thereby the position of the holding unit 17 in the sub direction of the line sensor 32 and the optical axis can be adjusted. The tilt in the sub direction can be finely adjusted.

  Further, if a gap t is formed between the expansion / contraction member 29 ′ and the installation plate 28, vibration when the apparatus is driven is transmitted to the expansion / contraction member 29 ′ via the first attachment member 30 and amplified there. As a result, the line sensor 32 of the holding unit 17 may be further shaken to adversely affect image reading. However, in this embodiment, since the expansion / contraction member 29 'is urged in the direction of the installation plate 28 by the leaf spring 35, it is possible to suppress the expansion / contraction member 29' from shaking due to vibration during driving of the apparatus as much as possible. It is possible to suppress the shaking of 32 as much as possible, and to avoid the above disadvantages.

  Further, like the expansion / contraction member 29 of the first embodiment, the expansion / contraction member 29 ′ is formed in a cylindrical shape covering the optical axis, and is formed in a shape symmetrical to the main direction with respect to the optical axis. There is no change, and since it is biased by the leaf spring 35 in the direction of the installation plate 28, the state in which the one-sided blur adjustment has been adjusted in advance is stable and the elastic member 29 ' Needless to say, it is possible to correct a focus shift in the main direction caused by a temperature change in the apparatus while being hardly affected by vibration.

  In the present embodiment, the leaf spring 35 is used as a biasing member that biases the expansion / contraction member 29 ′ in the direction of the installation plate 28, and the position of the expansion / contraction member 29 ′ in the sub-direction is adjusted by inserting and removing the stud bolt 36. However, for example, the position in the sub-direction of the elastic member 29 ′ may be adjusted by using a wedge or a cam.

FIG. 2 is an exploded perspective view of the main part of the light receiving unit included in the scanner unit of the image forming apparatus according to the embodiment of the present invention when viewed obliquely from above. FIG. 2 is a perspective view illustrating a schematic configuration of the image forming apparatus. FIG. 3 is a cross-sectional view taken along line A-A ′ in FIG. 2. It is a perspective view which shows the schematic structure of the said light reception unit. It is a disassembled perspective view of the said light reception unit. It is a disassembled perspective view when the principal part of the said light reception unit is seen from diagonally downward. It is a perspective view which shows the schematic structure of the light-receiving unit of the scanner part of the image forming apparatus which concerns on other embodiment of this invention. It is a side view of the light receiving unit. It is a disassembled perspective view when the principal part of the said light reception unit is seen from diagonally upward. It is a disassembled perspective view when the principal part of the said light reception unit is seen from diagonally downward. It is a top view which shows the schematic structure of the conventional imaging optical apparatus.

Explanation of symbols

1 Scanner unit (image reading device)
2 Printer section (image forming section)
16 coupling unit 16 'coupling unit 17 holding unit 18 lens (resin lens)
19 lens 20 lens 21 lens (resin lens)
23 Lens (resin lens)
25 Lens barrel 28 Installation plate 29 Stretchable member 29 'Stretchable member 29a Surface (first surface)
29b surface (second surface)
29e rib 30 first mounting member 31 second mounting member 32 line sensor (light receiving element)
33 Fixed substrate 34 Third mounting member 34b Hole (coupling position adjusting portion)
35 Leaf spring (biasing member)
36 Stud bolt (Adjustment member)
t clearance

Claims (20)

An image reading apparatus that reads a document image by receiving reflected light obtained by irradiating the document with light by a light receiving element arranged in a line in the main direction via at least one lens. ,
A lens barrel for holding the lens;
A holding unit for holding the light receiving element;
A coupling unit that couples the lens barrel and the holding unit;
The coupling unit has an expansion / contraction member that expands and contracts in the optical axis direction according to a temperature change,
The expansion and contraction member has a cylindrical shape covering the optical axis, and is formed in a shape symmetrical to the optical axis in the main direction,
The elastic member has surfaces formed on the lens barrel side and the holding unit side so as to be orthogonal to the optical axis and to surround the optical axis, and the lens mirror is interposed through these surfaces. It is fixed in the optical axis direction with the barrel and the holding unit,
The flat surface portions of the first mounting member and the second mounting member, each formed from a flat plate, are in contact with each of the surfaces over both ends in the main direction,
The image reading apparatus, wherein the expansion member, the lens barrel, and the holding unit are fixed through the first attachment member and the second attachment member, respectively. An image reading apparatus that reads a document image by receiving reflected light obtained by irradiating the document with light by a light receiving element arranged in a line in the main direction via at least one lens. ,
A lens barrel for holding the lens;
A holding unit for holding the light receiving element;
A coupling unit that couples the lens barrel and the holding unit;
The coupling unit has an expansion / contraction member that expands and contracts in the optical axis direction according to a temperature change,
The expandable member has a cylindrical shape that covers the optical axis and is formed in a symmetric shape with respect to the optical axis in the main direction, and extends in a direction perpendicular to the optical axis and extends in the optical axis direction. Have multiple ribs,
The image reading apparatus, wherein the lens barrel side end and the holding unit side end of the telescopic member are connected by the plurality of ribs. An image reading apparatus that reads a document image by receiving reflected light obtained by irradiating the document with light by a light receiving element arranged in a line in the main direction via at least one lens. ,
A lens barrel for holding the lens;
A holding unit for holding the light receiving element;
A coupling unit that couples the lens barrel and the holding unit;
The coupling unit has an expansion / contraction member that expands and contracts in the optical axis direction according to a temperature change,
The expansion and contraction member has a cylindrical shape covering the optical axis, and is formed in a shape symmetrical to the optical axis in the main direction,
The coupling unit further includes a first mounting member that is fixed in contact with the surface of the telescopic member on the lens barrel side in the optical axis direction and that is fixed to an installation plate on which the lens barrel is installed. And
The lens barrel is installed on the installation plate so that the optical axis extends along the plane of the installation plate.
The first mounting member is fixed to the telescopic member and the installation plate so that a lower end portion of the telescopic member on the lens barrel side is in contact with the flat surface of the installation plate.
The image reading apparatus according to claim 1, wherein the holding unit side of the expandable member is a free end. An image reading apparatus that reads a document image by receiving reflected light obtained by irradiating the document with light by a light receiving element arranged in a line in the main direction via at least one lens. ,
A lens barrel for holding the lens;
A holding unit for holding the light receiving element;
A coupling unit that couples the lens barrel and the holding unit;
The coupling unit has an expansion / contraction member that expands and contracts in the optical axis direction according to a temperature change,
The expansion and contraction member has a cylindrical shape covering the optical axis, and is formed in a shape symmetrical to the optical axis in the main direction,
The outer surfaces located on both sides in the sub direction across the optical axis of the telescopic member are formed such that the distance between these surfaces is narrower on the holding unit side than on the lens barrel side. Image reading device. The elastic member has surfaces formed on the lens barrel side and the holding unit side so as to be orthogonal to the optical axis and to surround the optical axis, and the lens mirror is interposed through these surfaces. It is fixed in the optical axis direction with the barrel and the holding unit,
The flat surface portions of the first mounting member and the second mounting member, each formed from a flat plate, are in contact with each of the surfaces over both ends in the main direction,
5. The fixing of the telescopic member, the lens barrel, and the holding unit is performed via the first mounting member and the second mounting member, respectively. The image reading apparatus according to any one of the above. The stretchable member has a plurality of ribs formed to protrude in the direction perpendicular to the optical axis and extend in the optical axis direction,
The image reading apparatus according to claim 1, wherein the lens barrel side end and the holding unit side end of the elastic member are connected by the plurality of ribs. The coupling unit further includes a first mounting member that is fixed in contact with the surface of the telescopic member on the lens barrel side in the optical axis direction and that is fixed to an installation plate on which the lens barrel is installed. And
The lens barrel is installed on the installation plate so that the optical axis extends along the plane of the installation plate.
The first mounting member is fixed to the telescopic member and the installation plate so that a lower end portion of the telescopic member on the lens barrel side is in contact with the flat surface of the installation plate,
The image reading apparatus according to claim 1 , wherein the holding unit side of the elastic member is a free end. The outer surfaces located on both sides in the sub direction across the optical axis of the telescopic member are formed such that the distance between these surfaces is narrower on the holding unit side than on the lens barrel side. The image reading apparatus according to claim 1, 2 or 3 . The telescopic members have surfaces orthogonal to the optical axis on the lens barrel side and the holding unit side, respectively, and are fixed to the lens barrel and the holding unit in the optical axis direction through these surfaces. 5. The image reading apparatus according to claim 2, 3 or 4 .   The image reading apparatus according to claim 1, wherein the expandable member is formed in a shape symmetrical with respect to the optical axis in the sub direction.   11. The image reading apparatus according to claim 1, wherein the expandable member also serves as a light blocking member that blocks stray light from entering a light path between the lens barrel and the holding unit. .   The image reading apparatus according to claim 1, wherein the lens barrel holds at least one resin lens. The coupling unit further includes a first mounting member that is fixed in contact with the surface of the telescopic member on the lens barrel side in the optical axis direction and that is fixed to an installation plate on which the lens barrel is installed. The image reading apparatus according to claim 1 , wherein the image reading apparatus is an image reading apparatus.   The first mounting member is fixed to the telescopic member and the installation plate so that a lower end portion of the telescopic member on the lens barrel side is in contact with the installation plate. The image reading apparatus described. The first mounting member is fixed to the telescopic member and the installation plate so that the telescopic member and the installation plate face each other with a gap therebetween,
The image reading apparatus according to claim 13, wherein a biasing member that biases the telescopic member toward the installation plate is fixed to the installation plate.   The installation plate is provided with an adjustment member that adjusts the inclination of the expansion / contraction member in the sub direction with respect to the optical axis by advancing / retreating in the sub direction with respect to the installation plate while contacting the expansion / contraction member through the gap. The image reading apparatus according to claim 15, wherein the image reading apparatus is provided. The coupling unit further includes a second attachment member that is fixed in contact with the surface of the elastic member on the holding unit side,
The holding unit is
A fixed substrate to which the light receiving element is fixed;
A third attachment member for joining the second attachment member of the coupling unit and the fixed substrate;
The third mounting member has a coupling position adjusting portion for adjusting the coupling position with the second mounting member in the optical axis direction at each of both ends in the main direction. Item 17. The image reading device according to any one of Items 13 to 16. The image reading apparatus according to claim 1 , wherein the expandable member has a rib protruding in a direction orthogonal to the optical axis.   19. The rib according to claim 18, wherein the rib is formed to extend in at least one of a main direction and an optical axis direction on an outer surface exposed in a sub-direction of the elastic member. The image reading apparatus described. An image reading device according to any one of claims 1 to 19,
An image forming apparatus comprising: an image forming unit configured to form the image on a recording medium based on image data read by the image reading apparatus.

Images