JP4096421B2 - Image reading device - Google Patents

Description

[0001]
【Technical field】
The present invention relates to an image reading apparatus used for reading an image of a document by being incorporated in a facsimile apparatus or various scanner apparatuses.
[0002]
[Prior art]
The applicant of the present application has previously proposed an image reading apparatus of this type described in Japanese Patent Laid-Open No. 10-173870. As shown in FIG. 11 of the present application, this conventional one emits light from a plurality of light sources 90 such as LEDs that emit light of each color of R, G, and B (red, green, and blue), and each of these light sources 90. A light guide 91 that guides the emitted light to a line-shaped image reading region Pe, a lens array 92 that focuses the light reflected from the document D arranged in the image reading region Pe and forms an image, and this lens A plurality of light receiving elements 93 that receive the light focused by the array 92 and convert the light source are provided, and each of the above components is incorporated in a case 94.
[0003]
The light guide 91 is made of a transparent member, and has a plurality of side surfaces extending in the same direction as the image reading region Pe. As shown in FIG. 12, a concave portion 95 having a substantially V shape in side view is formed at the longitudinal center of the light guide 91. The light source 90 faces the recess 95 so as to sandwich the light guide 91. Each of the plurality of side surfaces of the light guide 91 is formed in a mirror shape. However, a plurality of concave grooves 96 are provided at appropriate intervals on the second side surface 91b facing the first side surface 91a serving as the light emitting surface.
[0004]
As shown in FIG. 13, in the light guide 91, when the light emitted from the light source 90 enters the light guide 91 and reaches the inclined surfaces 95a and 95a of the recess 95, most of the light is The light is reflected toward both ends in the longitudinal direction of the light guide 91 and then reaches both ends in the longitudinal direction of the light guide 91 while repeating total reflection by a plurality of side surfaces of the light guide 91. At that time, the light reaching the respective concave grooves 96 on the second side surface 91b is reflected so that the traveling direction thereof can be rapidly changed, and a part of the light is reflected on the total reflection critical angle with respect to the first side surface 91a. The incident angle is smaller than that. Then, the light passes through the first side face 91a as it is, is emitted to the outside, and is irradiated onto the image reading region Pe.
[0005]
In the image reading apparatus, although a so-called point light source 90 is used as a light source for illuminating a document, light emitted from the light source 90 can be irradiated to various portions of the line-shaped image reading region Pe. . Therefore, there is an advantage that the total number of light sources can be reduced, and the component cost and running cost can be reduced.
[0006]
[Problems to be solved by the invention]
However, the conventional image reading apparatus has the following problems.
[0007]
That is, in the image reading device, it is difficult to make the amount of light emitted from each part in the longitudinal direction of the first side surface 91 a of the light guide 91 uniform, and the amount of light emitted from the central part in the longitudinal direction of the first side surface 91 a close to the light source 90. However, there is a tendency that the amount of light emitted from other portions is considerably larger. In this state, the illuminance at the central portion in the longitudinal direction of the image reading area Pe becomes higher than the illuminance at other portions, and the original image cannot be read faithfully. For this reason, conventionally, an opaque member is adhered to the longitudinal central portion of the first side surface 91a or a light shielding paint is applied to provide a light shielding portion 97 on the portion. The amount of light emitted from the central portion in the longitudinal direction of the side surface 91a toward the image reading region Pe is reduced. However, in such a means, the work for providing the light shielding portion 97 on the light guide 91 is complicated, and the productivity is poor.
[0008]
The present invention has been conceived under such circumstances, and it is necessary to perform complicated processing and processing on the light guide for guiding the light emitted from the light source to the line-shaped image reading region. It is an object of the present invention to improve the quality of a read image by making it possible to equalize the amount of light irradiated to each part in the longitudinal direction of the image reading region without causing the above-mentioned characteristics.
[0009]
DISCLOSURE OF THE INVENTION
In order to solve the above problems, the present invention takes the following technical means.
[0010]
The image reading device provided by the present invention is composed of a transparent member for guiding the light emitted from the light source to irradiate the line-shaped image reading region. Longitudinal A light guide, a lens array for focusing the light reflected from the image reading area to form an image, and a plurality of light receiving elements that receive the light focused by the lens array and perform photoelectric conversion And a case forming a housing portion for housing the light guide, and the light guide guides light that has entered the light guide from the light source into the light guide. Multiple of the body Extending in a longitudinal direction The light is reflected by the side surface In the longitudinal direction An image reading device configured to emit from a fixed length region of the first side surface of the plurality of side surfaces while being advanced, wherein the light guide is The first side surface is provided with a second side surface facing the first side surface in the thickness direction and having a light scattering portion, and the first side surface is a convex surface having a larger dimension in the width direction than the second side surface. The light guide is The plurality of side surfaces have substantially the same overall length as the length in the direction in which the side surfaces extend, and are open to one side. While extending longitudinally For the reflector formed with the groove, 1 side A face faces the opening, and the first of the plurality of side faces is 1 side The side surface other than the surface is accommodated in the accommodating portion in a state of being fitted so as to be opposed to the wall surface portion of the groove portion, and the case includes the light emitted from the first side surface of the light guide. , In the longitudinal direction There is a light-blocking part that blocks the light where the amount of emitted light is larger than the others. , So as to partially face the first side surface It is characterized by being provided.
[0011]
In the present invention, a groove portion for accommodating the lens array is formed in the case, and a part of a partition wall partitioning the groove portion and the accommodating portion is the light shielding portion. be able to. Moreover, in this invention, while the said light source is an LED light source provided facing the longitudinal direction edge part of the said light guide, the said light guide is emitted from the said LED light source, and this light guide It is also possible to adopt a configuration in which light incident on the end portion in the longitudinal direction is emitted from the fixed length region of the first side surface while traveling in the longitudinal direction of the light guide.
[0012]
In the present invention, when light is emitted from the fixed length region of the first side surface of the light guide, the light of the portion where the amount of emitted light increases may be blocked by the light shielding portion provided in the case. It is possible to prevent the image reading area from being irradiated while the light amount is extremely large. For this reason, the amount of light applied to the image reading region through the portion of the first side surface of the light guide through which the amount of emitted light increases and the amount of light applied to the image reading region through the other portion are determined. It is possible to equalize the amount of light irradiated to each part in the longitudinal direction of the image reading area and obtain a high quality read image. On the other hand, in the present invention, a means for providing a light shielding part in the case is employed as a means for making the amount of light irradiated to the image reading region uniform. Unlike the conventional case, the light guiding part is provided with a light shielding part. This eliminates the need for special processing and processing. In addition, the light shielding portion of the case can be formed by resin molding when the case is resin-molded, for example, and can be easily formed without requiring a special processing operation. Therefore, in the present invention, the productivity of the image reading apparatus can be increased and the manufacturing cost can be reduced.
[0013]
In preferable embodiment of this invention, the said light-shielding part is provided so that the light radiate | emitted from the part close | similar to the said light source among the 1st side surfaces of the said light guide may be interrupted | blocked.
[0014]
When light is emitted from the first side surface of the light guide, the amount of light emitted from a portion close to the light source tends to be maximized among the longitudinal portions of the first side surface. According to the above configuration, it is possible to block the light of the portion where the amount of emitted light is maximum by the light shielding portion, and it is possible to equalize the amount of light irradiated to each portion in the longitudinal direction of the image reading region.
[0015]
In another preferred embodiment of the present invention, the light-shielding portion is provided to face a portion where the amount of emitted light is maximized and a portion other than the portion in the longitudinal direction of the first side surface of the light guide. In this case, the light emitted from the portion having a larger amount of emitted light is configured such that the amount of light blocked by the light shielding portion increases.
[0016]
According to such a configuration, when the amount of light emitted from each part in the longitudinal direction of the first side surface of the light guide varies in various stages, the light shielding portion is used for the light of the portion where the amount of emitted light is maximum. The amount of light shielded by the light-shielding part is slightly reduced for light with a smaller amount of emitted light, and the amount of light shielded by the light-shielded part is further reduced for light with a smaller amount of emitted light. It can be said. Therefore, it is possible to make the distribution of the irradiation light amount to the image reading area finer and more uniform.
[0017]
In another preferred embodiment of the present invention, the light guide is opposed to the first side surface in the thickness direction of the light guide and the width direction of the light guide. The second side surface includes a third side surface and a fourth side surface, and the second side surface has a surface capable of scattering and reflecting light traveling in the light guide, and the third side surface and the fourth side surface. Is a curved surface that reflects the light traveling from the direction of the second side surface so as to make the light bundles of light rays substantially parallel to each other and travel toward the first side surface.
[0018]
According to such a configuration, when the light emitted from the light source and incident on the light guide is caused to travel inside the light guide, the light reaching the second side surface of the light guide is scattered and reflected. As a result, part of the light can be advanced toward the third side surface or the fourth side surface. Then, by reflecting the light by the third side surface and the fourth side surface, the light is made to travel toward the first side surface as a bundle of light rays that are substantially parallel to each other. The light can be emitted to the outside. Accordingly, the light emitted from the first side surface is prevented from traveling so as to spread in various directions, and the light irradiation efficiency is increased by irradiating the light on the image reading area in a concentrated manner. be able to.
[0019]
Other features and advantages of the present invention will become more apparent from the following description of embodiments of the invention.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be specifically described with reference to the drawings.
[0021]
FIG. 1 is a cross-sectional view of an essential part showing an example of an image reading apparatus according to the present invention. 2 is a cross-sectional view taken along the line II-II in FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. FIG. 5 is an exploded perspective view of the image reading apparatus shown in FIGS.
[0022]
The image reading apparatus A according to the present embodiment is configured as a so-called contact image sensor. As clearly shown in FIG. 5, the image reading apparatus A includes a case 1, a substrate 4, a plurality of sensor IC chips 2 mounted on the substrate 4, a single LED light source 3, a document guide plate 5, a lens. An array 6, a reflector 7, a light guide 8, and one or a plurality of attachments 59 are provided. As will be described later, the sensor IC chip 2 has a plurality of light receiving elements 20.
[0023]
The case 1 is made of a synthetic resin, and is formed in an elongated box shape in which a housing portion 10 having an upper surface opening shape is formed. In the case 1, the above-described components of the image reading apparatus A are assembled. The document guide plate 5 is for placing the document oppositely, and is made of, for example, transparent glass or synthetic resin. As shown in FIGS. 2 and 3, the document guide plate 5 is mounted on the upper surface of the case 1 so as to close the upper portion of the housing portion 10 of the case 1. Of the upper surface of the document guide plate 5, the portion directly above the lens array 6 is an image reading region P, and this image reading region P extends in a line shape in the longitudinal direction of the case 1 and the document guide plate 5. For example, a platen roller 58 is disposed on the upper surface of the document guide plate 5, and the document D is transferred in the sub-scanning direction by the platen roller 58.
[0024]
FIG. 6 is a partially broken perspective view showing the light guide 8. 7 is a cross-sectional view taken along the line VII-VII in FIG. FIG. 8 is an explanatory view showing the operation of the light guide 8.
[0025]
The light guide 8 is for efficiently guiding the light emitted from the LED light source 3 to the entire length of the image reading region P. The light guide 8 is made of, for example, an acrylic transparent resin such as PMMA or other highly transparent members, and the surfaces of the light guide 8 are all mirror surfaces. If the surface of the transparent member is made into a mirror surface, when light is guided to the inside of the transparent member, the light incident on the surface of the transparent member at an angle larger than the total reflection critical angle specified by the material of the transparent member It can be totally reflected. On the other hand, a light beam incident at an angle smaller than the total reflection critical angle can be transmitted as it is to the outside of the transparent member. The mirror surface is not necessarily a surface whose surface is actively polished. For example, when the light guide 8 is resin-molded using a mold, it may be a relatively smooth surface obtained by the resin molding.
[0026]
The light guide 8 can be divided into an auxiliary region Sb at one end in the longitudinal direction of the light guide 8 and other main regions Sa. The auxiliary area Sb is a part that plays a role of causing the light emitted from the LED light source 3 to travel into the main area Sa. The auxiliary region Sb is provided with a downward protruding portion 81, a downward bottom surface 82, two tapered surfaces 86a, 86b connected to the end surface 85, and the like. The bottom surface 82 is a portion that becomes a light incident surface that receives light from the LED light source 3, and the light emitted from the LED light source 3 passes through the bottom surface 82 and enters the auxiliary region Sb. As shown in FIG. 7, the tapered surfaces 86a and 86b are flat surfaces or curved surfaces that can totally reflect the light that has entered the auxiliary region Sb through the bottom surface 82 toward the main region Sa. The protrusion 81 serves to secure a space for disposing the LED light source 3 below the bottom surface 82.
[0027]
The main region Sa is a portion that plays a role of causing light traveling from the auxiliary region Sb to travel in the longitudinal direction of the main region Sa and emitting the light from the full length region of the first side surface 80A of the main region Sa. It is. That is, the main region Sa has a substantially uniform cross-sectional shape in each part in the longitudinal direction, and the first side surface 80A and the second side surface 80B opposed to the light guide 8 in the vertical thickness direction, and the light guide 8 The third side surface 80C and the fourth side surface 80D are opposed to each other in the left-right width direction. These side surfaces 80 </ b> A to 80 </ b> D all extend in the longitudinal direction of the light guide 8.
[0028]
As clearly shown in FIG. 8, the first side surface 80 </ b> A is formed as an aspherical convex surface having a central portion in the width direction bulging from the side edge portion. Each of the third side surface 80C and the fourth side surface 80D is formed as a parabolic surface (secondary curved surface) having a common main axis at the width direction center line C in the main region Sa of the light guide 8. As clearly shown in FIG. 6, the center line C is inclined with respect to the width direction center line C1 in the auxiliary region Sb. As will be described later, for the auxiliary area Sb, the bottom surface 82 of the auxiliary area Sb needs to face the LED light source 3, whereas for the main area Sa, the first side face 80A needs to face the image reading area P. Because there is. As clearly shown in FIG. 8, the second side surface 80B is formed as a plane passing through the common focal point O1 of the paraboloids of the third side surface 80C and the fourth side surface 80D or the vicinity thereof. . As clearly shown in FIG. 7, the second side surface 80B is provided with a plurality of concave portions 84 at appropriate intervals. The region between the plurality of recesses 84, 84 is a mirror-like plane. The plurality of recesses 84 are portions that play a role of changing the traveling direction abruptly by scattering and reflecting light in the light guide 8, and have a circular arc shape, for example. However, as other means for rapidly changing the traveling direction of the light guide 8 by scattering and reflecting light, for example, means for providing a plurality of convex portions on the second side surface 80B at appropriate intervals, light It is possible to employ means for applying a coating material that can be scattered and reflected to the second side surface 80B, or means for making the entire surface or part of the second side surface 80B a rough surface with minute irregularities.
[0029]
In the light guide 8, when the light emitted from the LED light source 3 enters the auxiliary region Sb and then travels toward the main region Sa, the light is transmitted through the first side surface 80 </ b> A and the third side surface 80 </ b> C. In addition, the light travels toward the end face 80E at one end in the longitudinal direction of the light guide 8 while repeating total reflection at various points on the fourth side face 80D and at the plane portion of the second side face 80B. Since the light incident on the concave portion 84 of the second side surface 80B is scattered and reflected in various directions and its path is changed abruptly, most of the light, as shown in FIG. It progresses toward the side surface 80D and is totally reflected by these side surfaces. However, as described above, the third side surface 80C and the fourth side surface 80D are paraboloids, and the second side surface 80B is located at or near the focal point O1 of the paraboloids. A large number of light beams reflected by the third side surface 80C and the fourth side surface 80D travel toward the first side surface 80A as light bundles substantially parallel to the main axes of their paraboloids, and this first side surface 80A. To the outside. Further, since the first side surface 80A is convex, the light emitted from the first side surface 80A travels so as to be focused on a predetermined focal point O2. Such light emission is performed in the entire length region of the first side surface 80A.
[0030]
In FIG. 5, the reflector 7 is for supporting the light guide 8. The reflector 7 has an overall length that is substantially the same as the overall length of the light guide 8, and a groove portion 70 opened on one side surface of the reflector 7 extends in the longitudinal direction of the reflector 7 and is formed in a series. ing. 2 and 3, the light guide 8 is supported by the reflector 7 in a fixed posture by being fitted into the groove 70. The reflector 7 is fitted in the housing portion 10 of the case 1, whereby the first side surface 80 </ b> A of the light guide 8 extends in the same direction as the image reading region P and faces the image reading region P. Yes. The reflector 7 is positioned so as not to move inadvertently above the accommodating portion 10 by engaging with a locking rib 19 provided in the case 1, for example.
[0031]
The wall surface portions 70b to 70d of the groove portion 70 of the reflector 7 are opposed to and contacted with the second side surface 80B, the third side surface 80C, and the fourth side surface 80D of the light guide body 8, respectively. The traveling light plays a role of preventing leakage of light to the outside of the light guide 8. As shown well in FIGS. 1 and 5, the reflector 7 has a longitudinal end portion 7 a formed in a shape capable of covering the outer surface of the auxiliary region Sb of the light guide 8, and the longitudinal direction thereof. A wall surface 70e capable of covering the end surface 80E of the light guide 8 is formed on the other end 7b. Therefore, as shown in FIG. 1, the light emitted from the LED light source 3 and traveling into the auxiliary region Sb of the light guide 8 leaks to the outside of the auxiliary region Sb. The reflector 7 can also prevent the light reaching the end face 80E from leaking outside as it is. The reflector 7 is made of, for example, white synthetic resin, and the surface facing the light guide 8 has a white light reflectance. In the present embodiment, the reflector 7 is a single member, but in the present invention, instead, for example, the main region Sa and the auxiliary region Sb of the light guide 8 are individually covered by two reflectors formed separately. It doesn't matter if you do.
[0032]
2 and 3, the lens array 6 focuses the light irradiated from the first side face 80 </ b> A of the light guide 8 to the image reading region P and reflected by the document D onto the surfaces of the plurality of light receiving elements 20. This is for image formation. As this lens array 6, for example, a structure in which a plurality of Selfoc lenses for forming an original image at an equal magnification is arranged in a line and held in a holder made of synthetic resin or the like is applied. The lens array 6 is disposed directly below the document guide plate 5 by being fitted into a groove 12 formed in the case 1.
[0033]
A partition wall 13 ′ that partitions them is formed between the groove 12 of the case 1 and the housing 10. As shown in FIG. 2, a part of the partition wall 13 ′ is a light shielding part 13 that faces a part of the first side surface 80 </ b> A of the light guide 8. More specifically, although the partition wall 13 ′ is formed so as to extend in series in the same direction as the image reading region P, the height thereof is not uniform everywhere, as shown in FIG. In the portion close to the light source 3, the light guide 8 is formed at a height facing a relatively wide area of the first side surface 80 </ b> A. Of the partition wall portion 13 ′, the portion facing the first side surface 80 </ b> A corresponds to the light shielding portion 13. On the other hand, as shown in FIG. 3, in the portion relatively far from the LED light source 3, the partition wall portion 13 ′ is formed at a lower height than the portion shown in FIG. The light-shielding portion facing the first side surface 80A is not provided, or even if the light-shielding portion is provided, the area facing the first side surface 80A is very small.
[0034]
The plurality of sensor IC chips 2 are obtained by integrally forming a plurality of light receiving elements 20 on one surface of a long and narrow rectangular semiconductor chip, and the light collected by the lens array 6 is received by the light receiving elements 20. Thus, the photoelectric conversion is performed, and an image signal having an output level corresponding to the amount of received light is output. The plurality of sensor IC chips 2 are mounted in a row in the longitudinal direction of the substrate 4.
[0035]
The LED light source 3 is, for example, a resin package in which three types of LED chips that emit light of each color of R, G, and B are collected together, and can cope with reading of a color original. Of course, in order to cope with reading of a monochrome document, an LED light source that emits white light or another single color light may be used. The LED light source 3 is mounted on the same surface as the surface on which the sensor IC chip 2 of the substrate 4 is mounted.
[0036]
The substrate 4 is assembled to the bottom of the case 1 so that the plurality of light receiving elements 20 are located immediately below the lens array 6 and the LED light source 3 faces the bottom surface 82 of the light guide 8. The substrate 4 is assembled by hooking the upper ends of the attachment 59 to the locking projections 14 and 14 formed on both side surfaces of the case 1, and attaching the bottom central portion of the attachment 59 to the substrate 4. This is done by contacting the back surface. Conductive wiring patterns (not shown) for inputting and outputting signals to the plurality of sensor IC chips 2 and the LED light source 3 and supplying power are formed on the surface of the substrate 4. The connection is made through the connector 40.
[0037]
Next, the operation of the image reading apparatus A will be described.
[0038]
In the image reading apparatus A, when the LED light source 3 is driven to be lit, as described above, the light emitted from the LED light source 3 enters the light guide 8 from the bottom surface 82 of the light guide 8 and is guided. It proceeds in the longitudinal direction in the main region Sa of the light body 8. Then, the light is emitted from the full length region of the first side surface 80A and is irradiated on the surface of the document D positioned in the line-shaped image reading region P. In this case, since light is incident on the light guide 8 only from one end portion in the longitudinal direction, portions of the first side surface 80A in the longitudinal direction that are close to the LED light source 3, that is, The amount of light emitted from the portion indicated by the symbol N of 1 is greater than the amount of light emitted from the other portions. However, in this image reading apparatus A, as shown in FIG. 2, the light shielding portion 13 is provided so as to face the portion where the amount of emitted light is large, and a part of the light emitted from the portion is image reading region P. Can be prevented from being irradiated. For this reason, it is possible to avoid the local increase in the amount of irradiation light to the image reading area P, and to make the amount of irradiation light uniform in the longitudinal direction of the image reading area P. As a result, it is possible to eliminate the deterioration of the image quality of the read image due to the variation in the amount of irradiation light.
[0039]
In the image reading apparatus A, the light that travels in the light guide 8 can be prevented by the reflector 7 from leaking to the outside through a side surface different from the first side surface 80A. In addition, since most of the light traveling from the first side surface 80A toward the image reading area P can be focused on the predetermined focal point O2, the light is focused on the image reading area P. You can also Therefore, the light irradiation efficiency to the image reading area P can also be increased.
[0040]
The specific configuration of each part of the image reading apparatus according to the present invention is not limited to the above-described embodiment.
[0041]
In the present invention, in the first side surface 80A of the light guide 8, only the light emitted from the portion where the amount of emitted light is maximum is not blocked by the light shielding portion, but also part of the light emitted from other portions. You may comprise so that it may be interrupted | blocked by the light-shielding part. That is, the amount of light emitted from each part in the longitudinal direction of the first side surface 80 </ b> A of the light guide 8 is extremely large only in a portion close to the LED light source 3 as compared with other portions. When the emitted light quantity gradually increases, the light shielding part is provided so as to face a relatively long size region in the longitudinal direction of the first side surface 80A, and the light shielding part is closer to the LED light source 3. The amount of light blocked by the part may be increased.
[0042]
In the present invention, the specific configuration of the light guide is not limited to that of the above-described embodiment. For example, the light guide shown in the conventional example may be used, as shown in FIGS. 9 and 10. The structure shown may be used. In the structure shown in FIG. 9, the LED light source 3 is opposed to the bottom surfaces 82 and 82 at both ends in the longitudinal direction of the light guide 8A so that light can enter the light guide 8A from these two locations. Yes. According to such a configuration, the amount of light incident on the light guide 8A can be increased, which is more preferable in increasing the illuminance of the image reading area. In the structure shown in FIG. 10, the LED light source 3 is opposed to the end face 80H at the end in the longitudinal direction of the light guide 8B. With such a configuration, most of the light emitted from the LED light source 3 and transmitted through the end face 80H can be directly advanced in the longitudinal direction of the light guide 8B. Light can be appropriately emitted from various places. Thus, in the present invention, it does not matter from which part of the light guide the light emitted from the light source is incident, and the specific shape of the light guide is not limited.
[0043]
In addition, in the present invention, the light source can be a different type of light source from the LED light source. Further, the image reading apparatus according to the present invention may be configured as a contact image sensor of a type used as a handy scanner, for example, instead of being configured as a contact image sensor of a type in which platen rollers are arranged to face each other. Good. Furthermore, it may be configured as a so-called flatbed type image sensor in which a case in which a light source, a light guide, and the like are assembled is provided below the document placement plate so as to be movable in the sub-scanning direction.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an essential part showing an example of an image reading apparatus according to the present invention.
FIG. 2 is a cross-sectional view taken along the line II-II in FIG.
3 is a cross-sectional view taken along the line III-III in FIG.
4 is a cross-sectional view taken along the line IV-IV in FIG.
5 is an exploded perspective view of the image reading apparatus shown in FIGS. 1 to 4. FIG.
FIG. 6 is a partially broken perspective view showing an example of a light guide.
7 is a sectional view taken along line VII-VII in FIG.
FIG. 8 is an explanatory diagram showing the operation of the light guide.
FIG. 9 is an explanatory view showing another example of the light guide.
FIG. 10 is a cross-sectional view of a main part showing another example of the light guide.
FIG. 11 is a cross-sectional view illustrating an example of a conventional image reading apparatus.
12 is an explanatory diagram showing a combined structure of a light guide and a light source of the image reading apparatus shown in FIG.
13 is an explanatory diagram illustrating an operation of a combined structure of a light guide and a light source of the image reading apparatus illustrated in FIG.
[Explanation of symbols]
A Image reading device
P Image reading area
D Manuscript
1 case
2 Sensor IC chip
3 LED light source
4 Substrate
5 Document guide plate
6 Lens array
7 Reflector
8, 8A, 8B Light guide
10 receiving section
12 Groove
13 Shading part
13 'Bulkhead
20 Light receiving element
80A 1st side
80B 2nd side
80C 3rd side
80D 4th side

Claims (6)

A longitudinal light guide made of a transparent member for guiding the light emitted from the light source to irradiate the line-shaped image reading area, and the light reflected from the image reading area is focused to form an image. A lens array, a plurality of light receiving elements that receive light focused by the lens array and perform photoelectric conversion, and a case that forms a housing portion that houses the light guide. And
The light guide body reflects the light that has entered the light guide body from the light source by a plurality of longitudinally extending side surfaces of the light guide body, thereby causing the light beams to travel in the longitudinal direction . An image reading device configured to emit from a fixed length region of the first side surface of the side surfaces,
The light guide has a second side surface that is positioned opposite to the first side surface in the thickness direction and has a light scattering portion,
The first side surface is a convex surface having a larger dimension in the width direction than the second side surface,
Said light guide, to a reflector extending grooves longitudinally shaped with an opening formed on one side and having substantially the same overall length and overall length in the direction in which the plurality of side surfaces extending, the first side surface It faces the aforementioned opening, and is housed in the housing portion in a state where the side surface other than the first side surface of the plurality of side surfaces are fitted to face contact with the wall surface of the groove,
In the case, a light-shielding portion that blocks a portion of the light emitted from the first side surface of the light guide that has a greater amount of emitted light in the longitudinal direction than the others is partially formed on the first side surface. An image reading apparatus, which is provided so as to face each other.   The image reading apparatus according to claim 1, wherein the light shielding unit is provided to shield light emitted from a portion near the light source in the first side surface of the light guide.   The light-shielding portion is provided to face the portion where the amount of emitted light is maximized and the other portion of each portion in the longitudinal direction of the first side surface of the light guide, and is emitted from the portion where the amount of emitted light is large. 3. The image reading apparatus according to claim 1, wherein the amount of light blocked by the light blocking unit increases as the amount of light increases.   4. A groove portion for accommodating the lens array is formed inside the case, and a part of a partition wall partitioning the groove portion and the accommodating portion is the light shielding portion. The image reading apparatus according to any one of the above.   The light source is an LED light source provided facing the longitudinal end of the light guide, and the light guide is emitted from the LED light source and enters the longitudinal end of the light guide. 5. The image reading device according to claim 1, wherein the image reading device is configured to emit the light from the fixed length region of the first side surface while proceeding in the longitudinal direction of the light guide. 6.   The light guide includes a second side facing the first side in the thickness direction of the light guide, and a third side and a fourth side facing each other in the width direction of the light guide. And the second side surface has a surface capable of scattering and reflecting the light traveling in the light guide body, and the third side surface and the fourth side surface proceed from the direction of the second side surface. The image reading apparatus according to claim 1, wherein the curved surface is a curved surface that reflects the light so as to travel toward the first side surface as a bundle of light beams that are substantially parallel to each other.

Images