JP2007134852A - Image reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reader which can generate a suitable image even if an internal temperature rises by preventing the significant displacement of an imaging element thereby suppressing the deviation of a focus. <P>SOLUTION: In the image reader 1, light irradiated on the document surface and reflected therefrom passes through an image formation lens 32 and is irradiated on an imaging element, i. e. a CCD 33, where the document image is read out. On the front side of its light receiving section 33a, the CCD 33 is held by an imaging element holding member 36 which is held by an intermediate holding member 37. Consequently, the CCD 33 is provided on a fixing base 31 by the imaging element holding member 36 and the intermediate holding member 37. Since such a structure that the CCD 33 is not held directly by the intermediate holding member 37 is employed, an effect of the thermal deformation of the intermediate holding member 37 caused by an internal temperature rise during the operation of the image reader 1 can be suppressed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image reading apparatus used for a copying machine, an image scanner, and the like.

  In general, an image reading apparatus used for a copying machine, an image scanner, or the like irradiates light on a document placed on a document table, and receives the reflected light to read image information on a document surface. The document table is made of transparent glass and is provided on the upper part of the apparatus main body. Inside the apparatus body below the document table, there is a light source that emits light toward the document surface, a mirror that guides the reflected light in a predetermined direction, an imaging lens, and a CCD (Charge Coupled Device). Etc. are provided.

  The focus adjustment of the image reading apparatus as described above is performed by reading a predetermined pattern image placed on the document surface. Irradiate this pattern and reflect the reflected light into the CCD, which is the image sensor, through the imaging lens, and move the imaging lens and CCD in the optical axis direction to obtain a good focus. Change the position and adjust the focus.

In general, the image forming lens and the CCD are usually provided in the image reading apparatus main body via a mounting base. An example of such a CCD mounting structure of an image reading apparatus can be seen in Japanese Patent Application Laid-Open No. 2005-228561. In the CCD (solid-state imaging device) mounting structure described in Patent Document 1, the CCD is mounted on the mounting base (solid-state imaging device holding member) via an intermediate holding member. This intermediate holding member is a light-transmissive member that covers the front side of the light receiving unit of the CCD.
JP 2001-326789 A (page 4-6, FIG. 2)

  Here, the focus adjustment of the image reading apparatus is performed by opening a portion where the imaging lens and the CCD are provided at the time of assembly before product shipment. This focus adjustment is performed at the same time as the position adjustment for focusing the CCD. However, when the product is shipped, the part where the imaging lens and the CCD are provided is closed by the frame or the transparent glass of the document table. Therefore, if the image reading apparatus is operated for a long time, the temperature inside the apparatus may increase sharply. . As a result, when the CCD is directly held by the intermediate holding member as in the CCD mounting structure described in Patent Document 1, the intermediate holding member is greatly affected by deformation due to heat, and the focus adjusted during product assembly is adjusted. However, there is a possibility that it will shift significantly during operation.

  Further, as in the CCD mounting structure described in Patent Document 1, if the intermediate holding member becomes a member having a relatively large volume in order to provide a recess in the intermediate holding member, the influence of deformation due to heat is further increased. . The intermediate holding member is provided with a step, and a thick portion and a thin portion are mixed, so the deformation direction in these portions is different and the deformation direction is also three-dimensional. There is a risk that the focus will increase dramatically. Therefore, even when the temperature in the apparatus rises during operation of the image reading apparatus, it is possible to suppress the deformation of the CCD holding member as much as possible, or to suppress a large focus shift even if the CCD holding member is deformed. It is necessary to devise the design.

  The present invention has been made in view of the above points. In an image reading apparatus that reads a document image with an image pickup device, even when the temperature in the apparatus rises, the image pickup device is prevented from being greatly displaced and focused. An object of the present invention is to provide an image reading apparatus capable of suppressing a shift of the image and obtaining a suitable image.

  In order to solve the above problems, the present invention provides an image reading apparatus in which light irradiated and reflected toward a document surface is incident on an image sensor through an imaging lens, and an image of the document is read by the image sensor. An image sensor holding member that holds the image sensor at a location in the vicinity of the light receiving portion of the image sensor, and an intermediate holding member that holds the image sensor holding member and is provided on a mounting base. The image sensor is held by the image sensor The mounting base is provided via the member and the intermediate holding member.

  In the image reading apparatus having the above-described configuration, the imaging element holding member is a light-transmissive member that covers the front side of the light receiving unit of the imaging element, and is on the same plane as the surface that holds the imaging element. The intermediate holding member is coupled and held.

  In the image reading apparatus having the above configuration, the imaging element holding member is made of glass.

  In the image reading apparatus having the above-described configuration, the intermediate holding member is a metal flat plate member.

  According to the configuration of the present invention, in an image reading apparatus that reads an original image with an image sensor, an image sensor holding member that holds the image sensor at a location near the light receiving portion of the image sensor, and the image sensor holding member that is held and attached An intermediate holding member provided on the base, and the imaging element is provided on the mounting base via the imaging element holding member and the intermediate holding member, so that the image pickup element is directly held by the intermediate holding member. There can be no structure. Thereby, even if the temperature in the apparatus rises during the operation of the image reading apparatus and the intermediate holding member is deformed by heat, the influence can be reduced. Therefore, a large displacement of the image sensor can be prevented, and a focus shift can be suppressed. As a result, it is possible to provide an image reading apparatus capable of obtaining a suitable image even when the temperature in the apparatus rises.

  The image sensor holding member is a light transmissive member that covers the front side of the light receiving unit of the image sensor, and is coupled to and held by the intermediate holding member on the same surface as the surface that holds the image sensor. As a result, even if the image sensor holding member is deformed by heat, the influence on the displacement of the image sensor can be reduced. In addition, the front surface of the light receiving unit of the image sensor and the one surface of the intermediate holding member can be on the same surface. For these reasons, it is possible to easily perform positioning of the image sensor by the intermediate holding member in addition to preventing the image sensor from being largely displaced when the temperature in the apparatus rises. Therefore, the focus shift of the image sensor is further improved, and the action for obtaining a suitable image is enhanced.

  In addition, since the imaging element holding member is made of glass, deformation of the imaging element holding member due to heat can be further suppressed. Thereby, the factor which displaces an image pick-up element can be reduced, and the effect | action which suppresses a focus shift | offset improves.

  In addition, since the intermediate holding member is a flat plate member made of metal, deformation of the intermediate holding member due to heat can be suppressed. Thereby, the factor which displaces an image pick-up element can further be reduced, and the effect | action which suppresses the focus shift | offset | difference further improves.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  First, an outline of the structure of an image reading apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic vertical sectional front view of the image reading apparatus, and FIG. 2 is a partial perspective view of the image reading apparatus as viewed from above. The image reading apparatus according to the embodiment of the present invention is designed as an image reading apparatus mounted on the upper side of a copying machine that is an image forming apparatus or a multifunction machine having functions such as a copying machine and a facsimile machine. To do.

  As shown in FIG. 1, the image reading apparatus 1 is mounted on an upper part of a copying machine or a multifunction machine that is an image forming apparatus. A main body 2 of the image reading apparatus 1 is composed of an outer cover 3 and an inner frame 4. The image reading apparatus 1 includes a document table 5 on the upper surface of the main body 2. The document table 5 is made of transparent glass, and the document is placed on the surface of the transparent glass with the reading surface (document surface) facing down.

  As shown in FIGS. 1 and 2, an optical system component for irradiating light toward the document surface is provided below the document table 5 and inside the inner frame 4 of the main body 2. Yes. The optical system components include a first optical system unit 10, a second optical system unit 20, and an imaging unit 30.

  As shown in FIG. 1, the first optical system unit 10 includes a light source 11 and a first mirror 12. The light source 11 emits light toward the document surface. The first mirror 12 receives light reflected from the light source 11 toward the document surface and reflected by the document surface, and changes the direction at an angle of 90 degrees. The light source 11 and the first mirror 12 are fixed to a first optical system support member (not shown).

  The second optical system unit 20 includes a second mirror 21 and a third mirror 22. The second mirror 21 receives the light reflected by the first mirror 12 of the first optical system unit 10 and changes the direction at an angle of 90 degrees. The third mirror 22 receives the light reflected by the second mirror 21 and changes the direction at an angle of 90 degrees. The second mirror 21 and the third mirror 22 are fixed to a second optical system support member (not shown).

  The image pickup unit 30 includes an imaging lens 32 and a CCD 33 as an image pickup element on the top of the mounting base 31. The reflected light from the document surface reflected by the third mirror 22 of the second optical system unit 20 enters the imaging lens 32. The imaging lens 32 forms an image of the reflected light on the surface of the CCD 33 provided on the downstream side of the optical path. Thus, the original image can be read by the CCD 33.

  Here, in the image reading apparatus 1 configured as described above, the imaging unit 30 is fixed to the internal frame 4 of the main body 2, but the first optical system unit 10 and the second optical system unit 20 are image information of the entire document surface. Can be reciprocated in parallel with the document surface to read the image. Therefore, a moving rail (not shown) extending in the left-right direction in FIG. 1 is provided inside the inner frame 4. The first optical system unit 10 and the second optical system unit 20 can move along the rails and read image information on the entire document surface.

  Next, a detailed configuration of the imaging unit 30 of the image reading apparatus 1 will be described with reference to FIGS. 3 is a perspective view of the imaging unit, FIG. 4 is a schematic partial front view of the imaging unit, FIG. 5 is an enlarged schematic vertical sectional view of a CCD portion of the imaging unit, and FIG. 6 is a perspective view of the CCD portion. The state which removed the element holding member is shown. The arrows in the figure indicate the incident direction of the reflected light from the document surface.

  As shown in FIGS. 3 and 4, the imaging unit 30 includes a mounting base 31 that serves as a base thereof. The mounting base 31 includes an engaging portion 34 with the inner frame 4 (see FIGS. 1 and 2) of the main body 2 at the lower part thereof. The engaging portions 34 are provided at two locations on the front side and the back side of the mounting base 31. The engaging portion 34 is provided with a plurality of round holes 34a and elongated holes 34b. The round hole 34a and the long hole 34b are used for position and angle adjustment when the imaging unit 30 is attached to the internal frame 4. The position in the optical axis direction is determined by selecting one of the plurality of round holes 34a and engaging with a pin (not shown) provided in the internal frame 4. Further, the angle of the optical axis is adjusted by selecting any one of the plurality of elongated holes 34b and engaging with the pin.

  An imaging lens 32 is provided on the upper surface of the mounting base 31. The imaging lens 32 is attached so as to receive reflected light from the document surface and guide it to a CCD 33 provided on the downstream side of the optical path (see FIG. 4).

  As shown in FIG. 4, a CCD 33 is provided on the downstream side of the optical path with respect to the imaging lens 32 on the upper surface of the mounting base 31. The CCD 33 is fixed to the control board 35 as shown in FIG. Further, the CCD 33 is held by the imaging element holding member 36 on the front side of the light receiving portion 33a. As shown in FIG. 6, the image sensor holding member 36 is formed of a glass flat plate having a light transmissivity of 2 mm. The image sensor holding member 36 is provided so as to cover the front side of the light receiving portion 33 a of the CCD 33.

  As shown in FIGS. 4 and 5, the image sensor holding member 36 is held by an intermediate holding member 37. As shown in FIGS. 5 and 6, an opening 37 a is provided at a location corresponding to the CCD 33 of the intermediate holding member 37. The opening 37a is large enough to receive the light receiving portion 33a of the CCD 33. The image sensor holding member 36 is large enough to cover the opening 37a. The image sensor holding member 36 is coupled to and held by the intermediate holding member 37 on the same surface as the surface that holds the CCD 33, that is, the surface on the downstream side of the optical path. The intermediate holding member 37 is a flat plate member made of metal and has a L-shaped cross-section when viewed from the front, and the mounting base 31 so that the surface of the image sensor holding member 36 faces the imaging lens 32. Is provided. In this way, the CCD 33 that is an image sensor is provided on the mounting base 31 via the image sensor holding member 36 and the intermediate holding member 37.

  In addition, when attaching the image sensor holding member 36 to the CCD 33 and the intermediate holding member 37, an adhesive 38 was used as shown in FIGS. As this adhesive 38, a UV curable adhesive (NOA81) manufactured by NORLAND was used. The adhesive 38 was applied with care so as not to block incident light reaching the CCD 33. Since the adhesive 38 is not cured unless UV irradiation is performed, the position of the CCD 33 with respect to the image sensor holding member 36 and the intermediate holding member 37 is adjusted and then UV irradiation is performed to cure the adhesive 33 in units of several seconds. Positioning can be performed.

  Further, as shown in FIG. 5, the adhesive 38 was used when the intermediate holding member 37 was attached to the attachment base 31. Accordingly, the intermediate holding member 37 can be attached without using a screw and further without performing a hole processing or the like necessary for screwing. Therefore, it is possible to adjust the position of the CCD 33 for focusing by a method that further reduces the cost.

  In this manner, in the image reading apparatus 1 that reads an original image with the CCD 33 that is an image sensor, the image sensor holding member 36 that holds the CCD 33 at a location near the light receiving portion 33a of the CCD 33, and the image sensor holding member 36 are held. Since the CCD 33 is provided on the mounting base 31 via the image sensor holding member 36 and the intermediate holding member 37, the CCD 33 is directly held by the intermediate holding member 37. It can be set as the structure which is not done. Thereby, even if the temperature inside the apparatus rises during the operation of the image reading apparatus 1 and the intermediate holding member 37 is deformed by heat, the influence can be reduced. Therefore, a large displacement of the CCD 33 can be prevented, and a focus shift can be suppressed. As a result, it is possible to provide the image reading apparatus 1 capable of obtaining a suitable image even when the temperature in the apparatus rises.

  The image pickup element holding member 36 is a light-transmitting member that covers the front side of the light receiving portion 33a of the CCD 33, and is coupled to and held by the intermediate holding member 37 on the same surface as the surface that holds the CCD 33. Therefore, even if the image sensor holding member 36 is deformed by heat, the influence on the displacement of the CCD 33 can be reduced. Further, the front surface of the light receiving portion 33a of the CCD 33 and one surface of the intermediate holding member 37 can be on the same surface. As a result, the CCD 33 can be easily positioned by the intermediate holding member 37 in addition to preventing a large displacement of the CCD 33 when the temperature in the apparatus rises. Accordingly, the focus shift of the CCD 33 is further improved, and the action for obtaining a suitable image is enhanced.

  And since the image pick-up element holding member 36 is comprised with glass, the deformation | transformation by the heat | fever of the image pick-up element holding member 36 can further be suppressed. Thereby, the factor which displaces CCD33 can be reduced and the effect | action which suppresses the focus shift | offset | difference improves.

For example, when the imaging element holding member 36 is exemplified by a transparent acrylic resin which is another light transmitting member, the acrylic resin has a linear expansion coefficient of about 7.0 × 10 ⁻⁵ / ° C. On the other hand, the linear expansion coefficient of glass is about 8.0 × 10 ⁻⁶ / ° C. Therefore, when the image sensor holding member 36 is made of glass, the amount of expansion can be reduced by an order of magnitude as compared with acrylic resin.

  More specifically, when the resolution in the main scanning direction of the image reading apparatus 1 is 600 dpi, if the image reading range is 300 mm on the original, it is about 7087 pixels. Here, it is assumed that the temperature in the apparatus is increased by 35 ° C. from the room temperature of 25 ° C. to 60 ° C. When the image sensor holding member 36 is made of an acrylic resin, an elongation of about 0.25% occurs, which affects the expansion of about 18 pixels in the image reading range. On the other hand, when the image sensor holding member 36 is made of glass, the elongation can be suppressed to about 0.028%, and it is possible to keep the elongation of about 2 pixels in the image reading range.

  Further, since the intermediate holding member 37 is a metal flat plate-like member, deformation of the intermediate holding member 37 due to heat can be suppressed. As a result, the factor for displacing the CCD 33 can be further reduced, and the effect of suppressing focus deviation is further improved.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  The present invention can be used in all image reading apparatuses using an image sensor such as a CCD.

1 is a schematic vertical sectional front view of an image reading apparatus according to an embodiment of the present invention. FIG. 2 is a partial perspective view of the image reading apparatus of FIG. 1 viewed from above. It is a perspective view of an imaging unit. It is a model partial front view of an imaging unit. It is a model vertical cross-section part enlarged view of the CCD part of an imaging unit. FIG. 2 is a perspective view of a CCD unit, showing a state where an image sensor holding member is removed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image reader 2 Main body 4 Internal frame 10 1st optical system unit 20 2nd optical system unit 30 Imaging unit 31 Mounting stand 32 Imaging lens 33 CCD (imaging element)
33a Light-receiving part 35 Control board 36 Image pick-up element holding member 37 Intermediate holding member 37a Opening part 38 Adhesive

Claims (4)

In an image reading apparatus in which light irradiated and reflected toward a document surface is incident on an image sensor through an imaging lens, and an image of the document is read by the image sensor.
An image sensor holding member that holds the image sensor at a location in the vicinity of the light receiving portion of the image sensor, and an intermediate holding member that holds the image sensor holding member and is provided on a mounting base. The image sensor is held by the image sensor An image reading apparatus provided on a mounting base via a member and an intermediate holding member.   The image sensor holding member is a light transmissive member that covers the front side of the light receiving unit of the image sensor, and is coupled to and held by the intermediate holding member on the same surface as the surface that holds the image sensor. The image reading apparatus according to claim 1.   The image reading apparatus according to claim 1, wherein the imaging element holding member is made of glass.   The image reading apparatus according to claim 1, wherein the intermediate holding member is a flat plate member made of metal.

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