JP5209818B2 - Image sensor unit and image reading apparatus - Google Patents

Description

  The present invention relates to an image sensor unit and an image reading apparatus using the image sensor unit.

In an image sensor unit in which a light source is installed in the vicinity of the end surface on the longitudinal direction (main scanning direction) side of the light guide, if light leaks from the gap between the light source and the light guide, the illuminance distribution is uniform in the main scanning direction. There was a possibility that it could not be kept.

  Therefore, an image sensor described in Patent Document 1 has been proposed by the present applicant.

International Publication No. 2008/013234 Pamphlet

  The image sensor unit described in Patent Document 1 has an opening for covering the light guide and allowing light emitted from the light exit surface of the light guide to pass therethrough, and emits light beyond the end face of the light guide. It has a light guide cover fitted to the element. Thereby, the emitted light from the light emitting element can be efficiently incident on the light guide.

  On the other hand, the invention provides a sliding member that slides on the document placement portion, and the above-described placement without entering the light guide body among the light emitted from the light source provided on the sliding member. A light shielding portion that blocks light traveling toward the portion. Accordingly, an object of the present invention is to provide an image sensor unit and an image reading apparatus that can obtain a uniform illuminance distribution of light traveling toward the document placing portion.

The image sensor unit according to the present invention is an image sensor unit used in an image reading apparatus having a document placement portion on which a document is placed, and a light source and light emitted from the light source disposed at a longitudinal end portion of the document. A light guide that guides the document placed on the placement unit; a light source; a support that supports the light guide; and the document placement supported by a longitudinal end of the support. A sliding member that slides on the part, and a light-shielding part that is provided on the sliding member and shields light directed from the light source toward the document placement part without entering the light guide, out of the light emitted from the light source And a locking portion provided on the sliding member, and a locked portion that is provided on the support and is locked with the locking portion, and the sliding member includes the locking portion. Is attached to the support by locking the portion and the locked portion, and the sliding Member, characterized in that it is removed from the support by said locking portion and the locked portion is disengaged.

  ADVANTAGE OF THE INVENTION According to this invention, the image sensor unit which can obtain the uniform illumination intensity distribution of the light which goes to a document mounting part, and an image reading apparatus can be provided.

FIG. 1 is a perspective view showing the structure of an image scanner to which the present invention can be applied. FIG. 2 is a schematic view showing the image sensor unit 4. FIG. 3 is a cross-sectional view of the light guide 11 in the sub-scanning direction. FIG. 4 is a perspective view of the spacer 16 to which the present invention can be applied. FIG. 5 is a perspective view showing the structure of the image sensor unit 4. FIG. 6 is a perspective view showing the detailed shape of the spacer 16. FIG. 7 is a cross-sectional view in the main scanning direction showing the structure of the image sensor unit 4. FIG. 8 is a diagram showing the illuminance distribution when the light emitting element 10r having the R emission wavelength emits light. FIG. 9 is a diagram showing an illuminance distribution when the light emitting element 10b having the emission wavelength of B emits light. FIG. 10 is a diagram showing an illuminance distribution when the light emitting element 10g having the G emission wavelength emits light. FIG. 11 is a partially enlarged view showing the illuminance distribution when the light emitting element 10r having the R emission wavelength emits light. FIG. 12 is a partially enlarged view showing the illuminance distribution when the light emitting element 10b having the emission wavelength of B emits light. FIG. 13 is a partially enlarged view showing the illuminance distribution when the light emitting element 10g having the G emission wavelength is caused to emit light. FIG. 14 is a diagram illustrating a measurement result at a position of 1 PIX at the time of independent light emission of each of RGB. FIG. 15 is a schematic diagram illustrating a state of reflected light in a state where the light-shielding roof 20 is not used. FIG. 16 is a schematic diagram illustrating a state of reflected light in a state in which the light-shielding roof 20 having the back surface as an absorption surface is provided. FIG. 17 is a schematic diagram illustrating a state of reflected light in a state in which the light-shielding roof 20 having the back surface as a reflection surface is provided. FIG. 18 is a diagram illustrating a positional relationship between the light guide 11 and the light emitting elements 10r, 10b, and 10g.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing the structure of a flatbed scanner (image reading apparatus) to which the present invention can be applied.
Reference numeral 1 denotes a housing. The housing 1 can be opened and closed so as to cover a platen glass 2 made of a glass transparent plate as a document placement portion and a document (not shown) placed on the platen glass 2. A provided platen cover 3 is provided.

  An image sensor unit 4 is housed inside the housing 1, and the image sensor unit 4 is, for example, a contact image sensor (CIS) unit. 5 is a slide shaft provided so that the image sensor unit 4 can be moved along the platen glass 2, 6 is a drive motor, and 7 is a wire. Reference numeral 8 denotes an electrical wiring such as a flexible cable, which electrically connects the image sensor unit 4 and the signal processing unit 9 by the electrical wiring 8.

  With this configuration, the image sensor unit 4 is moved along the slide shaft 5 in the reading direction (sub-scanning direction) by driving the drive motor 6 and mechanically moving the wire 7 attached to the image sensor unit 4. Is.

FIG. 2 is a schematic view showing the structure of the image sensor unit 4.
Reference numeral 10 denotes a light source for illuminating a document. The light source 10 includes light emitting elements 10r, 10g, and 10b made of LEDs having light emission wavelengths of three colors of red, green, and blue (hereinafter abbreviated as RGB). In this configuration, the elements 10r, 10g, and 10b are sequentially turned on to emit light.
The light source 10 may be a white light source.

Reference numeral 11 denotes a long light guide that guides the light emitted from the light source 10 to the document. The light source 10 is disposed near one end face in the longitudinal direction of the light guide 11 with a gap A therebetween. .
Reference numeral 12 denotes a rod lens array as an imaging element. The rod lens array 12 has a configuration in which a plurality of erecting equal-magnification imaging lens elements are arranged.
Reference numeral 13 denotes a photoelectric conversion element that converts reflected light (original image) imaged by the rod lens array 12 into an electric signal, and reference numeral 14 denotes a sensor on which a photoelectric conversion element 13k (k is a natural number from 1 to 11) is mounted. It is a substrate.
In the present embodiment, the number of photoelectric conversion elements 13k is 11, but the number of photoelectric conversion elements 13k is not particularly limited.

  With the above configuration, the image sensor unit 4 emits light at the reading position immediately below the platen glass 2 by sequentially driving the light emitting elements 10r, 10g, and 10b provided in the light source 10 to light. Irradiation light from the light source 10 is irradiated obliquely upward through the light guide 11 to illuminate the surface of the original in a line shape substantially uniformly in the main scanning direction. Irradiated light from the light source 10 is reflected by the original, and this reflected light is focused on a photoelectric conversion element 13 k provided on the sensor substrate 14 by the rod lens array 12. The reflected light is converted into an electric signal by the photoelectric conversion element 13 k and processed by the signal processing unit 9.

  In this way, the reading operation of one scanning line in the main scanning direction of the document is completed by reading all reflected light of RGB for one scanning line.

  After the scanning operation for one scanning line is completed, the image sensor unit 4 further moves in the sub-scanning direction by one scanning line and similarly performs the scanning operation for one scanning line while irradiating the original with irradiation light. By repeating this reading operation, the entire surface of the document is scanned.

FIG. 3 is a side view showing the structure of the light guide 11.
The light guide 11 is formed from, for example, a transparent synthetic resin such as acrylic.
Reference numeral 101 denotes a light incident surface provided on one side end surface in the longitudinal direction (main scanning direction), and the light source 10 is disposed in the vicinity of the light incident surface 101 with a gap A therebetween. Irradiation light is incident.

Reference numeral 102 denotes an emission surface provided along the longitudinal direction of the light guide 11, which emits irradiation light from the light source 10 reflected and diffused in the light guide 11 in the direction of the document. The exit surface 102 is formed in a convex shape for the light collecting effect.
Reference numeral 103 denotes a reflecting surface provided on a surface facing the emission surface 102. On the reflecting surface 103, a light diffusion pattern (not shown) made of a light-reflective paint by, for example, silk printing is formed. The distribution density of the light diffusion pattern is a configuration in which a portion close to the light source 10 is disposed at a low density and a distant portion is disposed at a high density according to the distance from the light source 10.
The other surfaces are reflecting surfaces (not shown).

  With this configuration, irradiation light from the light source 10 that has entered the light guide 11 from the light entrance surface 101 provided on the light guide 11 is reflected in the light guide 11 by the reflection surface 103 and a reflection (not shown). The light is emitted from the emission surface 102 while propagating through the light guide while being totally reflected by the surface. At the same time, the light is emitted from the light emission surface 102 while being diffused by the light diffusion pattern provided on the reflection surface 103 in the light guide 11, thereby irradiating the original substantially uniformly in a line shape in the main scanning direction. is there.

At this time, irradiation light from the light source 10 enters the light guide 11 from the light incident surface 101 provided on the light guide 11 and the gap A without entering the light guide 11. And light that irradiates directly in the direction of the document.
For this reason, light that directly irradiates in the document direction without entering the light guide 11 becomes leakage light.

4 is a perspective view of the spacer 16 to which the present invention can be applied, FIG. 5 is a perspective view showing the structure of the image sensor unit 4, and FIG. 6 is a perspective view showing a detailed shape of the spacer 16.
Reference numeral 15 denotes a frame as a support for supporting the constituent members. On the frame 15, constituent members such as the sensor substrate 14 on which the light source 10, the light guide 11, the rod lens array 12, and the photoelectric conversion element 13k are mounted are predetermined. It is the structure each attached and supported by the positional relationship.
Reference numeral 16 denotes a spacer, which is formed in a substantially U-shape as a whole. This spacer 16 is provided as a first spacer 16a and a second spacer 16b, which will be described later, at positions covering both ends in the longitudinal direction of the image sensor unit 4, respectively.

Support portions 17 are provided at both ends of the spacer 16, and hook-like locking portions 18 are provided at the support portions 17, respectively.
The locking portions 18 are provided so as to face each other, and are attached to the frame 15 by being locked with the respective locked portions 19 provided on the frame 15.
Further, when the support portion 17 is locked with the locked portion 19 provided on the frame 15, the support portion 17 is configured to have a certain amount of elastic force in order to maintain the locked state.
The tip of the support portion 17 has a length that protrudes from the lower surface of the frame 15 when the spacer 16 is attached to the frame 15, and the tip of the support portion 17 is the case when the image sensor unit 4 is attached to the case 1. It is located near the bottom face in 1.

  As a result, when the image sensor unit 4 is moved, the tips of the support portions 17 protruding from both ends of the image sensor unit 4 act as stoppers for the electric wires 8, so that the electric wires 8 move in the main scanning direction. The range can be regulated. For this reason, the electric wiring 8 can be stably positioned within the width of the image sensor unit 4, and the load on the electric wiring 8 caused by being sandwiched between the image sensor unit 4 and other components can be reduced. .

Reference numeral 20 denotes a light-shielding roof as a light-shielding portion extending from the spacer 16. When the light-shielding roof 20 is assembled to the image sensor unit 4, the upper part of the light source 10 (and the end of the light guide 11) is used. It is formed in a shape that covers it.
Reference numeral 21 denotes a protrusion, which is provided at two locations on the upper surface of the spacer 16.

The spacer 16 is made of a synthetic resin having self-lubricating properties, and is made of, for example, ultrahigh molecular weight polyethylene, polyacetal, polyamide, polybutylene terephthalate, or the like. Or it is formed from the synthetic resin containing the solid lubricant which has self-lubricating property, for example, is formed from the synthetic resin which coated fluororesin, molybdenum disulfide etc., for example.
Here, the self-lubricating property refers to a property that the friction and wear can be reduced without using any other lubricant or the like by itself having lubricity.

In this configuration, the spacer 16 is provided at a position covering both ends in the longitudinal direction of the image sensor unit 4 (frame 15). In other words, the first spacer 16a as the first sliding member is detachably assembled to one end, and the second spacer 16b as the second sliding member is detachably assembled to the other end. is there.
For this reason, when the image sensor unit 4 is housed in the housing 1, the first spacer 16 a and the second spacer 16 b are respectively inserted between the platen glass 2 and the image sensor unit 4.
At this time, the image sensor unit 4 is in contact with the lower surface of the platen glass 2 through the projections 21 provided on the first spacer 16a and the second spacer 16b at both ends of the upper surface.

In the present embodiment, the first spacer 16a and the second spacer 16b are commonly used by inverting and using the same shape, but they may have different shapes.
Further, the number and shape of the protrusions 21 are not limited to the present embodiment.

FIG. 7 is a sectional view showing the structure of the image sensor unit 4 in the main scanning direction.
A gap A is provided between the light source 10 and the light guide 11, and an air layer B is provided between the light shielding roof 20 provided on the first spacer 16 a and the end of the light guide 11. Yes.
8 to 10 are diagrams in which the illuminance distribution in the reading range of the image sensor unit 4 according to the present embodiment is measured. In the presence or absence of the light-shielding roof 20 and the difference in reflectance on the back surface of the light-shielding roof 20, RGB is shown. The illuminance distribution during each single emission is shown. 11 to 13 are partially enlarged views of FIGS. 8 to 10.

That is, FIG. 8 and FIG. 11 are diagrams showing the illuminance distribution when the light emitting element 10r having the R emission wavelength emits light. In the figure, 200 is a line indicating the illuminance distribution in a state where the light-shielding roof 20 is not used, 201 is an illuminance distribution in the state including the light-shielding roof 20 with the back surface as an absorption surface, and 202 is a light-shielding roof with the back surface as a reflection surface. 20 is an illuminance distribution in a state with 20.
FIGS. 9 and 12 are diagrams showing the illuminance distribution when the light emitting element 10b having the emission wavelength B emits light. In the figure, 300 is a line showing the illuminance distribution in a state where the light-shielding roof 20 is not used, 301 is an illuminance distribution in the state having the light-shielding roof 20 with the back surface as an absorption surface, and 302 is a light-shielding roof with the back surface as a reflection surface. 20 is an illuminance distribution in a state with 20.
FIGS. 10 and 13 are diagrams showing the illuminance distribution when the light emitting element 10g having the emission wavelength G emits light. In the figure, 400 is a line indicating the illuminance distribution in the state where the light-shielding roof 20 is not used, 401 is the illuminance distribution in the state provided with the light-shielding roof 20 with the back surface as the absorption surface, and 402 is the light-shielding roof with the back surface as the reflection surface. 20 is an illuminance distribution in a state with 20.

  The absorption surface means that the back surface of the light-shielding roof 20 is made of, for example, a synthetic resin kneaded with a black pigment having low light reflectance, and / or absorbs light such as matte black paint. It is shown that the surface treatment was performed. Further, the reflecting surface indicates that the back surface of the light-shielding roof 20 is a surface having a metallic luster (mirror surface), for example, having a coating with high light reflectance.

FIG. 14 is a diagram showing measurement results at a position of 1 PIX at the time of single light emission of each of RGB in the presence / absence of the light-shielding roof 20 and the difference in reflectance on the back surface of the light-shielding roof 20.
FIG. 15 is a schematic diagram showing a state of reflected light in a state where the light-shielding roof 20 is not used, FIG. 16 is a schematic diagram showing a state of reflected light in a state where the light-shielding roof 20 having the back surface as an absorption surface is provided, and FIG. It is a schematic diagram which shows the state of the reflected light in the state provided with the light-shielding roof 20 which used as the reflecting surface.

  As shown in the figure, when RGB is made to emit light alone, a reduction rate of 29.4 to 31.9% compared to a state where the light-shielding roof 20 is not used by making the back surface of the light-shielding roof 20 as an absorption surface. Was confirmed. Similarly, a reduction rate of 4.5 to 8.9% was confirmed by using the back surface of the light-shielding roof 20 as a reflective surface.

  Thereby, the surface treatment of the rear surface of the light-shielding roof 20 has a high reduction rate in a low reflectance state, and for example, it is shown that matte black that exhibits low reflectance is suitable. As a result, the back surface of the light-shielding roof 20 is used as an absorption surface, and effective light shielding is possible by absorbing leakage light.

The difference in illuminance generated in RGB at the 1PIX position is due to the difference in the mounting positions of the light emitting elements 10r, 10g, and 10b.
That is, if the distances from the light emitting elements 10r, 10b, 10g to the emission surface 102 between the light emitting elements 10r, 10b, 10g and the reading position of the document are C, D, E, respectively, “C <D <E”. It becomes. At this time, since the gap A is constant, the shorter the distance, the larger the opening angle with respect to the gap A from the light emitting elements 10r, 10b, 10g side. For this reason, leakage light increases as the distance from the light emitting elements 10r, 10b, and 10g to the emission surface 102 is shorter.
In addition, if the distances from the emission surface 102 to the document reading position between the light emitting elements 10r, 10b, and 10g and the document reading position are F, G, and H, respectively, “(C + F) <(D + G) < (E + H) ". This is because the illuminance is inversely proportional to the square of the distance from the light emitting elements 10r, 10b, and 10g, and therefore the illuminance of leaking light increases as the distance from the light emitting elements 10r, 10b, and 10g to the document reading position decreases. (See Figure 18)
In the present embodiment, a first spacer 16a and a second spacer 16b are detachably provided on the upper surface of the image sensor unit 4 (frame 15), and the first spacer 16a includes the light source 10 and the light guide. 11 is provided with a light-shielding roof 20 that extends so as to cover the end of 11.
As a result, leakage light from the gap A can be shielded without adding new parts, and the illuminance distribution in the vicinity of the light incident surface 101 can be stabilized, so that the illuminance distribution is kept substantially constant over the entire region in the main scanning direction. Therefore, stable image quality can be obtained.

  In addition, the section from the light incident surface 101 to the photoelectric conversion element 13k can be shortened, and the total length of the image sensor unit 4 can be shortened.

  Further, by making the spacer 16 detachable, the light guide 11 need not be slid and attached, and can be attached by fitting. For this reason, the attachment work of the light guide 11 is facilitated, and the friction range generated between the light guide 11 and the frame 15 when the light guide 11 is attached can be reduced. Etc. can be prevented.

  Further, since the spacer 16 has a structure in which the light source 10 and the light-shielding roof 20 extending so as to cover the end of the light guide 11 are provided, the LED used in the light source 10 is a commercially available product that is inexpensive in terms of cost. Can be used, and the cost can be reduced.

  Further, by providing the protrusions 21 on the upper surface of the spacer 16, by reducing the contact area with the lower surface of the platen glass 2, it is possible to reduce the frictional resistance and fix the contact position. Thereby, not only can the operation of the image sensor unit 4 be stabilized, but also the distance between the lower surface of the platen glass 2 and the image sensor unit 4 can be made constant.

  Further, since the air layer B is provided between the light-shielding roof 20 and the end of the light guide 11, even when the light guide 11 expands due to thermal expansion or moisture absorption, it does not come into direct contact and is guided. It is possible to prevent scratches and wear generated on the light body 11.

  In addition, by performing surface treatment for absorbing light on the back surface of the light shielding roof 20, it is possible to effectively shield light by absorbing leakage light.

  In addition, by providing the air layer B between the light shielding roof 20 and the light guide 11, the emission surface 102 at the end of the light guide 11 covered with the light shielding roof 20 can be used as a reflection surface. For this reason, even when surface treatment for absorbing light is performed on the back surface of the light shielding roof 20, light absorption at the contact surface that occurs when the light shielding roof 20 and the light guide 11 are in close contact with each other is eliminated, and light guide is performed. Since the light can be reflected inside the body 11, the light from the light source 10 can be guided efficiently.

  Furthermore, by forming the spacer 16 from a synthetic resin having a self-lubricating property such as ultrahigh molecular weight polyethylene, polyacetal, polyamide, polybutylene terephthalate, the integrally formed protrusion 21 is formed with the back surface of the platen glass 2. It can reduce friction and wear. Thereby, the damage | wound, abrasion, etc. which arise on the lower surface of the platen glass 2 can be prevented.

  Further, by forming the spacer 16 from a synthetic resin containing a solid lubricant by coating a fluororesin, molybdenum disulfide, or the like, for example, scratches or wear generated on the lower surface of the platen glass 2 while reducing costs. Can be prevented.

  The present invention is a technique effective as an image reading apparatus such as an image scanner, a facsimile machine, and a copying machine.

2 platen glass 4 image sensor unit 10 light source 11 light guide 12 rod lens array 13 photoelectric conversion element 14 sensor substrate 16 spacer 16a first spacer 16b second spacer 20 light-shielding roof 21 projection A gap B air layer

Claims (6)

In an image sensor unit used in an image reading apparatus having a document placement portion for placing a document,
A light source;
A light guide that guides the light emitted from the light source disposed at the longitudinal end to the document placed on the document placement unit;
A support for supporting the light source and the light guide;
A sliding member that is supported by a longitudinal end portion of the support and slides with the document placing portion;
A light-shielding portion that is provided on the sliding member, and blocks light directed toward the document placement portion without entering the light guide among the light emitted from the light source;
A locking portion provided on the sliding member;
A locked portion that locks with the locking portion provided on the support;
Have
The sliding member is attached to the support by the locking portion and the locked portion being locked,
The sliding member is detached from the support body when the locking portion and the locked portion are released.
An image sensor unit characterized by that . Before SL sliding member has a projection to reduce the contact area between the document tray, the protrusions, and characterized by being configured so as to protrude in a direction that is provided with the document tray The image sensor unit according to claim 1. When using a pre-Symbol image sensor unit in the image reading apparatus,
The image according to claim 2, wherein the sliding member is configured to have the protrusion and the light-shielding portion on a side where the document placement portion is provided with respect to the light guide. Sensor unit. An air layer is provided between the light shielding part and the light guide, and the light shielding part and the light guide are not in contact with each other when the light guide is expanded by the air layer. The image sensor unit according to claim 1, wherein: Supporting said sliding member provided at both ends in the longitudinal direction of the support are identical in shape, and wherein the said document tray in the widthwise direction end portions of the support projecting toward the opposite direction and parts, wherein the said document tray in the widthwise direction end portion and a support portion projecting toward the opposite direction,
The image sensor unit is electrically connected with the support portion protruding from one end portion of the sliding member provided at both longitudinal ends of the support body and the support portion protruding from the other end portion. The image sensor unit according to any one of claims 1 to 4, wherein the image sensor unit is configured to regulate a moving range of the electric wiring to be connected. An image sensor unit;
A document placement section for placing a document;
An image reading apparatus comprising:
The image sensor unit according to claim 1, wherein the image sensor unit is an image sensor unit according to claim 1.

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