JP2011087290A - Linearly-aligned illuminating device and image reader using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linearly-aligned illuminating device capable of uniforming an illuminance even though a lighting source is disposed at only one end side of a light-guide body. <P>SOLUTION: The linearly-aligned illuminating device includes: a light source 10 having a light-emitting element; and a light-guide body 11 illuminating a lighted object in linearly aligned state by guiding the light from the light source 10. The light-guide body 11 includes: a light entering surface 101 provided at one side end surface in a longitudinal direction; a light-outgoing surface 102 provided at one surface along a longitudinal direction; a reflective surface 103 provided at a surface facing the light-outgoing surface 102; and a light diffusion pattern 104<SB>m</SB>having a pattern shape 105 diffusing the light while residing on the reflective surface 103 and comprising at least two rows. The light diffusion pattern 104<SB>m</SB>is composed so that a flat surface C on which a light axis A of the light-emitting element provided to the light source 10 intersects with a normal line B to the reflective surface 103 is provided to deviate from a line-of-intersection D intersecting at the reflective surface 103, and a distribution density of the pattern shape 105 varies in response to the distance from the light source 10. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a line illuminating device used in an image reading apparatus such as a copying machine, an image scanner, or a facsimile, and more particularly to an image sensor unit that irradiates light on a reading surface of a document and reads the reflected light. The present invention relates to a line illumination device and an image reading device using the same.

  In general, as an image reading apparatus, a flat bed type image reading apparatus using a contact image sensor unit (CIS; Contact Image Sensor) is known. Further, in this contact image sensor unit, a line illumination device using LEDs as an illumination device is used.

  This is because one end surface of a rod-shaped light guide extending in the longitudinal direction is used as a light incident surface, and a light source composed of an LED or the like is disposed in the vicinity thereof so that light can pass through the light guide in the longitudinal direction of the light guide. The light is emitted in the direction of the original from the emission surface provided along the line. The light reflected from the document is imaged on the light receiving element by the lens array and converted into an electric signal. At this time, the light guide is designed so that the illuminance of the light emitted from the emission surface is substantially uniform.

In addition, the light guide is provided with a light diffusion pattern in order to generate diffused light and make the illuminance of the emitted light uniform. Generally, the pattern shape constituting the light diffusion pattern is a portion close to the light source. It is formed so that it becomes denser as the distance from the light source increases.
Further, in the gazette described in Patent Document 1, in the vicinity of the light source 20, the normal line 23 passing through the center of the width of the reflection part 22 provided in the light guide 21 is deviated from the center of the side including the reflection part 22. Proposals of light guides for devices have been made. (See Figure 14)

Incidentally, in general, the light guide is formed by injection molding a transparent resin such as acrylic. At this time, the end surface that is the surface on which the light from the LED is incident can be formed into a mirror surface (flat surface), but the other end that is the surface opposite to the light incident surface is a gate portion. Therefore, it becomes necessary to perform cutting processing, resulting in a rough surface.
For this reason, in the gazette described in Patent Document 2, a line illumination device using a rod-shaped transparent light guide 32 in which a mirror surface facing a light source which is one end in the longitudinal direction is a light incident surface 30 and the other end 31 is a rough surface. Proposals have been made. (See Figure 15)

  In the line illumination device disclosed in this publication, a light source is disposed only at one end of a rod-shaped transparent light guide 32. Further, in order to obtain uniform illuminance along the longitudinal direction, the area of the light scattering pattern 33 formed on the surface of the rod-shaped transparent light guide 32 gradually increases from the light incident surface 30 toward the other end 31. It is.

Japanese Patent Laid-Open No. 2001-223852 Japanese Patent Laid-Open No. 10-126581

  However, in the configuration described in Patent Document 1, in the vicinity of the light source 20, a distance is generated between the reflection unit 22 as the reflection unit and the light source 20, and the reflection unit 22 diffuses and / or reflects. There was a problem that the light to be darkened.

  Moreover, the structure of patent document 2 makes this rough surface turn into a light-diffusion surface by leaving the end surface 31 which opposes the light-incidence surface 30 as a rough surface. For this reason, the diffused light diffused from the rough surface is diffused by the light scattering pattern 33 and emitted from the rod-shaped transparent light guide 32, and the illuminance near the other end 31 is not long in the longitudinal direction (main scanning direction). There was a problem of uniformity.

  The present invention has been made in view of such circumstances, and even when a light source is disposed only on one end side of the light guide, the illuminance is uniform in the width direction (sub-scanning direction) and the longitudinal direction (main scanning direction). It is an object of the present invention to provide a linear illumination device that can be realized and an image reading device using the same.

  A line-shaped illumination device according to claim 1, comprising: a light source having a light-emitting element; and a rod-shaped light guide that guides light from the light source and illuminates the illuminated body in a line. In the illuminating device, the light guide body includes a light incident surface that receives light from the light source provided on one side end surface in the longitudinal direction and a light incident surface that is provided on one surface along the longitudinal direction. It consists of at least two rows provided on the reflecting surface, an emitting surface for emitting light in the direction of the object to be illuminated, a reflecting surface for reflecting light from the light source provided on the surface facing the emitting surface, and the reflecting surface. A light diffusing pattern having a pattern shape for diffusing light, wherein the light diffusing pattern has a plane where an optical axis of the light emitting element and a normal to the reflecting surface intersect each other at the reflecting surface. It is provided so as to be shifted with respect to the intersection Depending on the distance from the light source, wherein the distribution density of the pattern shape changes.

  The line-shaped illumination device according to claim 2 includes: a light source having a plurality of light-emitting elements; and a rod-shaped light guide that guides light from the light source and illuminates the object to be illuminated in a line. In the line-shaped illumination device, the light guide has a light incident surface that receives light from the light source provided on one side end surface in the longitudinal direction, and the light source that is provided on one surface along the longitudinal direction. An emission surface for emitting light from the direction of the object to be illuminated, a reflection surface for reflecting light from the light source provided on a surface facing the emission surface, and at least the light emission provided on the reflection surface A light diffusion pattern having a pattern shape for diffusing light consisting of a number of elements plus one, and the light diffusion pattern has an optical axis of the light emitting element and a normal to the reflection surface. The intersecting plane is the intersection line intersecting at the reflecting surface And, together with the provided so as to be offset in accordance with the distance from the light source, wherein the distribution density of the pattern shape changes.

  The line illuminating device according to claim 3 is the line illuminating device according to claim 1 or 2, wherein the light guide emits light from the light source provided to face the light incident surface. A rough surface that diffuses is provided, and the light diffusion pattern has at least a region in which the pattern shape is not provided in the vicinity of the rough surface.

  The image reading apparatus according to claim 4, comprising: a light source having a light emitting element; and a rod-shaped light guide that guides light from the light source and illuminates the illuminated body in a line shape. In the image reading apparatus using an illuminating device, the light guide is provided on a light incident surface that receives light from the light source provided on one side end surface in the longitudinal direction and a surface along the longitudinal direction. In addition, an emission surface that emits light from the light source in the direction of the object to be illuminated, a reflection surface that reflects light from the light source provided on a surface opposite to the emission surface, and a reflection surface, A light diffusing pattern having a pattern shape for diffusing light, comprising at least two rows, and the light diffusing pattern has a plane in which an optical axis of the light emitting element intersects with a normal to the reflecting surface, To deviate from the intersecting line intersecting on the reflective surface Together kicked in accordance with the distance from the light source, wherein the distribution density of the pattern shape changes.

  The image reading apparatus according to claim 5 includes a light source having a plurality of light emitting elements, and a rod-shaped light guide that guides light from the light source and illuminates the illumination target in a line. In the image reading apparatus using a line-shaped illumination device, the light guide is formed on a light incident surface that receives light from the light source provided on one side end surface in the longitudinal direction and a surface along the longitudinal direction. An exit surface that emits light from the provided light source in the direction of the object to be illuminated, a reflective surface that reflects light from the light source provided on a surface facing the exit surface, and the reflective surface. A light diffusing pattern having a pattern shape for diffusing light consisting of at least the number of the light emitting elements plus one, and the light diffusing pattern with respect to the optical axis of the light emitting element and the reflecting surface. The plane that intersects the normal is the reflective surface. Against the intersection line of the difference, with provided so as to be offset in accordance with the distance from the light source, wherein the distribution density of the pattern shape changes.

  The image reading device according to claim 6 is the image reading device according to claim 4 or 5, wherein the light guide diffuses light from the light source provided to face the light incident surface. A rough surface is provided, and the light diffusion pattern has a region where the pattern shape is not provided at least in the vicinity of the rough surface.

  As described above, the light diffusion pattern is shifted with respect to the intersecting line where the plane where the optical axis of the light emitting element intersects with the normal to the reflecting surface intersects with the reflecting surface of the light guide. Furthermore, by forming at least two rows of light diffusion patterns, the peak of diffused light from the light diffusion patterns can be reduced. For this reason, the illuminance of the outgoing light from the outgoing surface can be made uniform in the width direction (sub-scanning direction).

  In addition, the light diffusion pattern is shifted on the reflection surface of the light guide with respect to each intersection line intersecting at the reflection surface with the plane where the optical axis of the plurality of light emitting elements intersects with the normal line to the reflection surface. Further, by forming at least four rows of light diffusion patterns, the peak of diffused light from the light diffusion patterns in each light emitting element can be reduced. For this reason, the illuminance shift due to the position of the light source can be alleviated, and the illuminance of the emitted light from the exit surface can be made uniform in the width direction (sub-scanning direction).

  In addition, at least in the vicinity of the light diffusing surface, by having a configuration in which a pattern shape is not provided, even if the end surface facing the light incident surface remains a rough surface, in the vicinity of the light diffusing surface (rough surface) Diffused light from the light diffusion pattern can be reduced. For this reason, it becomes possible to reduce the peak of the outgoing light from the outgoing face, and it is possible to increase the uniformity of illuminance in the longitudinal direction (main scanning direction).

FIG. 1 is a perspective view showing the structure of a copying machine to which the present invention can be applied. FIG. 2 is a schematic diagram showing the structure of the reading unit of the copying machine. FIG. 3 is a side view showing the structure of the light guide 11. FIG. 4 is an example of a light diffusion pattern 104 _m provided on the reflecting surface 102 to which the present invention can be applied. Figure 5a is a cross-sectional view in the width direction of a conventional light diffusion pattern 104 _m of the light guide 11 showing a shape (sub-scanning direction). Figure 5b is a graph showing the relationship between the diffusion light diffused by conventional light diffusion pattern 104 _m. Figure 6a is a cross-sectional view in the width direction of the light guide 11 showing the shape of the light diffusion pattern 104 _m to which the present invention can be applied (the sub-scanning direction). Figure 6b is a diagram showing the relationship between the diffusion light diffused by the light diffusion pattern 104 _m to which the present invention can be applied. FIG. 7 is a perspective view showing an example of the relationship between the optical axis A, the normal B, the plane C, and the intersection line D in the light guide 11 to which the present invention can be applied. FIG. 8 shows another example of the light diffusion pattern 104 _m provided on the reflecting surface 102 to which the present invention can be applied. Figure 9a is a cross-sectional view in the width direction of a conventional light diffusion pattern 104 _m of the light guide 11 showing a shape (sub-scanning direction). Figure 9b is another diagram showing the relationship between the diffusion light diffused by conventional light diffusion pattern 104 _m. Figure 10a is a cross-sectional view in the width direction of the light guide 11 showing another light diffusion pattern 104 _m shape to which the present invention can be applied (the sub-scanning direction). Figure 10b is another diagram showing the relationship between the diffusion light diffused by the other light diffusion pattern 104 _m to which the present invention can be applied. FIG. 11 is a perspective view showing another example of the relationship between the optical axis A, the normal B, the plane C, and the intersecting line D in the light guide 11 to which the present invention can be applied. FIG. 12 shows another example of the light diffusion pattern 104 _m provided on the reflecting surface 102 to which the present invention can be applied. FIG. 13 is a graph showing a comparative example of emitted light depending on the presence or absence of a region E to which the present invention can be applied. FIG. 14 is a diagram showing a light guide described in Patent Document 1. As shown in FIG. FIG. 15 is a diagram showing a light guide described in Patent Document 2. As shown in FIG.

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 is provided with a platen glass 2 made of a glass transparent plate as a document placement portion and a document that can be opened and closed so as to cover the document placed on the platen glass 2. A platen cover 3 is provided.
In addition, an image sensor unit 4 is stored in the housing 1, and the image sensor unit 4 is, for example, a contact image sensor (CIS) unit. Reference numeral 5 denotes a holding member that holds the image sensor unit 4 so as to surround the image sensor unit 4. Reference numeral 6 denotes a slide shaft provided so as to be movable along the platen glass 2. Reference numeral 7 denotes a drive motor. Reference numeral 8 denotes a wire. It is a processing unit.

  With this configuration, the image sensor unit 4 is moved in the reading direction (sub-scanning direction) along the slide shaft 6 by driving the drive motor 7 and mechanically moving the wire 8 attached to the holding member 5. It is.

FIG. 2 is a schematic diagram showing the structure of the image sensor unit 4.
Reference numeral 10 denotes a light source for illuminating a document. The light source 10 is provided with a light emitting element composed of an LED, and is configured to emit light from the light emitting element.
Reference numeral 11 denotes a rod-shaped light guide that guides light emitted from the light source 10 to the document. The light source 10 is disposed in the vicinity of one end face of the light guide 11 in the longitudinal direction.
Reference numeral 12 denotes a rod lens array as an imaging element, and this rod lens array 12 is formed by arranging a plurality of erecting equal-magnification imaging lens elements.
13 is a photoelectric conversion element that converts the reflected light (original image) imaged by the rod lens array 12 into an electrical signal, and 14 is a photoelectric conversion element 13 _k (k is a natural number from 1 to 11). It is a sensor 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 from the light emitting element provided in the light source 10 at a reading position directly below the platen glass 2. The irradiated light is emitted through the light guide 11 and is irradiated substantially uniformly in a line shape on the surface of the document (not shown) in the main scanning direction. The irradiated light is reflected by the original, and this reflected light is focused by the rod lens array 12 onto the photoelectric conversion element 13 _k provided on the sensor substrate 14. The reflected light is converted into an electrical signal by the photoelectric conversion element 13 _k , and this electrical signal is processed by the signal processing unit 9 via the sensor substrate 14.

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

  After the scanning operation for one scanning line, the image sensor unit 4 further performs the scanning operation for one scanning line while irradiating the original with light while moving in the sub scanning direction by one scanning line. 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 a transparent resin such as acrylic by injection molding.
In the injection molding, a molded product is molded by injecting molten resin from a nozzle into a hollow portion that becomes a molded product through an inlet (gate).

By the way, when the light guide is formed by the above-described injection molding, an end surface that is a surface on which light from the light source 10 is incident can be formed into a flat surface, but the other end that is a surface facing the light incident surface is a gate portion. Therefore, since it becomes necessary to perform cutting with a jig such as a nipper, it is formed into a rough surface.
For this reason, the light guide 11 is formed from one rough surface and another flat surface, and this rough surface is used as a light diffusion surface as it is.

That is, 100 is a light diffusion surface (rough surface) provided on one side end surface in the longitudinal direction (main scanning direction), and 101 is a light incident surface provided to face the light diffusion surface 100.
By arranging the light source 10 in the vicinity of the light incident surface 101, light from the light source 10 enters.

Reference numeral 102 denotes an emission surface provided along the longitudinal direction of the light guide 11, which emits light from the light source 10 reflected and diffused in the light guide 11 in the direction of an original as an illuminated body. is there. The exit surface 102 is formed in a convex shape for the light collecting effect.
Reference numeral 103 denotes a reflection surface provided on a surface facing the emission surface 102, and the reflection surface 103 is provided with a light diffusion pattern 104 _m (m is a natural number).

The light diffusion pattern 104 _m is configured by forming a pattern shape 105 made of a light-reflective paint by silk printing or the like on the reflection surface 103, for example.
The other surfaces are reflecting surfaces (not shown).

With this configuration, 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 reflection surface 103 in the light guide 11 and not shown. The light is emitted from the emission surface 102 while propagating through the light guide while being totally reflected by the inner surface. At the same time, the light diffusing surface 100 in the light guide 11, and, while diffused by the light diffusion patterns 104 _m provided on the reflective surface 103, by output from the output surface 102, a main scanning direction with respect to the original (not shown) In FIG. 1, the light is irradiated substantially uniformly in a line shape.
Example 1

It shows an example of the light diffusion pattern 104 _m provided on the reflecting surface 103 of the light guide 11 to which the present invention is applicable FIG.
At least two rows of light diffusion patterns 104 _m are provided on the reflecting surface 103.
The light diffusion pattern 104 _m is configured by, for example, a pattern shape 105 including dots (points), and the distribution density of the pattern shape 105 gradually increases from the light incident surface 101 toward the light diffusion surface 100. It is.
That is, according to the distance from the light source 10, the part close | similar to the light source 10 is low density, and it is the structure arrange | positioned with high density far away.
The pattern shape 105 may be any shape such as a circle or a polygon. Moreover, it is not limited to the same shape, You may change a diameter, a shape, etc. according to a density.

With this configuration, the proportion of the pattern shape 105 constituting the light diffusion pattern 104 _m gradually increases from one end where light from the light source 10 enters to the other end. For this reason, the diffusivity of the part close to the light source 10 can be lowered, and the diffusivity can be gradually increased toward the distant place. Even if there is only one light source 10, it is substantially uniform along the longitudinal direction (main scanning direction). It is possible to obtain a high illuminance.

Further, FIGS. 5a and cross-sectional shape in the width direction (sub-scanning direction) of the light guide 11 in Figure 6a, Figure 5b and, diffused by the light diffusion patterns 104 _m in the width direction (sub-scanning direction) in FIG. 6b The distribution of illuminance of diffused light (hereinafter referred to as illuminance distribution) is shown.
Reference numeral 200 is a line showing the illuminance distribution of the conventional outgoing light, and 201 is a line showing the illuminance distribution of the outgoing light to which the present invention can be applied.
The conventional light diffusion pattern 104 _m shown in FIG. 5 a is configured to be provided over the entire surface of the reflection surface 103.

FIG. 7 is a perspective view showing an example of the relationship between the optical axis A, the normal B, the plane C, and the intersecting line D in the light guide 11 to which the present invention can be applied.
That is, A is the optical axis of the light emitting element provided in the light source 10, B is the normal to the reflecting surface 103, C is the plane where the optical axis A and the normal B intersect, and D is the plane C is the reflecting surface. The intersection line intersects on 103.
In addition, the plane C shall be shown with a broken line as a cross section in the light guide 11 in the figure.

In this configuration, the diffusion light diffused by the light diffusion patterns 104 _m, in the illuminance distribution in the width direction (sub-scanning direction), resulting in a peak along the line of intersection D.
Since the outgoing light emitted from the outgoing surface 102 is composed of reflected light from the reflective surface 103 (and a reflective surface not shown) and diffused light diffused by the light diffusion pattern 104 _m , the outgoing light is emitted from the outgoing surface 102. The illuminance of the emitted light becomes nonuniform.

On the other hand, the light diffusion pattern 104 _m showing an example to which the present invention shown in FIG. 6A can be applied has a configuration in which the light diffusion pattern 104 _m is shifted with respect to the intersection line D.
That is, at least two rows of the light diffusion patterns 104 _m are provided along the intersection line D with the gap 106 _n (n is a natural number that is m−1 when m is a natural number of 2 or more).

With this configuration, the diffused light from the light diffusion pattern 104 _m can be reduced by the gap 106 _n in the vicinity of the peak of the diffused light generated along the intersection line D, so that the light diffusion in the illuminance distribution in the width direction (sub-scanning direction). The peak of diffused light from the pattern 104 _m decreases. For this reason, the illuminance of outgoing light emitted from the outgoing surface 102 can be made uniform.

Note that the frame line indicating the gap 106 _n is added to improve the visibility, and does not indicate the light diffusion pattern 104 _m and the pattern shape 105.
(Example 2)

FIG. 8 shows another example of the light diffusion pattern 104 _m provided on the reflection surface 103 of the light guide 11 to which the present invention can be applied.
Reference numeral 10 denotes a light source for illuminating a document. The light source 10 is provided with light emitting elements 10r, 10g, and 10b composed of LEDs having emission wavelengths of red (r), green (g), and blue (b). The light emitting elements 10r, 10g, and 10b are sequentially lit and driven to emit light.

At least four rows of light diffusion patterns 104 _m are provided on the reflective surface 103.
The light diffusion pattern 104 _m is configured by, for example, a pattern shape 105 including dots (points), and the distribution density of the pattern shape 105 gradually increases from the light incident surface 101 toward the light diffusion surface 100. It is.
That is, according to the distance from the light source 10, the part close | similar to the light source 10 is low density, and it is the structure arrange | positioned with high density far away.
The pattern shape 105 may be any shape such as a circle or a polygon. Moreover, it is not limited to the same shape, You may change a diameter, a shape, etc. according to a density.

With this configuration, the proportion of the pattern shape 105 constituting the light diffusion pattern 104 _m gradually increases from one end where light from the light source 10 enters to the other end. For this reason, the diffusivity of the part close to the light source 10 can be lowered, and the diffusivity can be gradually increased toward the distant place. Even if there is only one light source 10, it is substantially uniform along the longitudinal direction (main scanning direction). It is possible to obtain a high illuminance.

Further, FIGS. 9a and cross-sectional shape in the width direction (sub-scanning direction) of the light guide 11 in Figure 10a, Figure 9b and, diffused by the light diffusion patterns 104 _m in the width direction (sub-scanning direction) in FIG. 10b The distribution of illuminance of diffused light (hereinafter referred to as illuminance distribution) is shown.
202r, 202g and 202b are lines indicating the illuminance distribution of the conventional outgoing light, and 203r, 203g and 203b are lines indicating the illuminance distribution of the outgoing light to which the present invention can be applied.
The conventional light diffusion pattern 104 _m shown in FIG. 9 a has a configuration provided over the entire surface of the reflective surface 103.

FIG. 11 is a perspective view showing another example of the relationship between the optical axis A, the normal B, the plane C, and the intersecting line D in the light guide 11 to which the present invention can be applied.
That is, A is the optical axis of the light emitting element provided in the light source 10, B is the normal to the reflecting surface 103, C is the plane where the optical axis A and the normal B intersect, and D is the plane C is the reflecting surface. The intersection line intersects on 103.
In addition, the plane C shall be shown with a broken line as a cross section in the light guide 11 in the figure.

In this configuration, the diffusion light diffused by the light diffusion patterns 104 _m, in the illuminance distribution in the width direction (sub-scanning direction), the light-emitting elements 10r, 10 g, the peak along the line of intersection D each corresponding to 10b Arise.
The light beam emitted from the output surface 102, a reflecting surface 103 (and not shown reflection surface) to be composed of diffused light diffused by the reflected light and the light diffusion pattern 104 _m from, the respective light emitting elements 10r, 10 g When each of 10b is turned on, the light shift due to the difference in the installation position becomes remarkable, and the illuminance of the emitted light emitted from the emission surface 102 becomes non-uniform.

In contrast, the light diffusing pattern 104 _m showing another example of the present invention can be applied as shown in Figure 10a, with respect to the intersection line D each, so that the light diffusion pattern 104 _m each is shifted, at least four rows a configuration where the light diffusion pattern 104 _m is provided.

That is, the light diffusion pattern 104 _m is provided along the intersection line D with the gap 106 _n (n is a natural number that is m−1 when m is a natural number of 2 or more), respectively.

With this configuration, the diffused light from the light diffusion pattern 104 _m can be reduced by the gap 106 _n in the vicinity of the peak of the diffused light generated along each intersection line D. Therefore, in the illuminance distribution in the width direction (sub-scanning direction), The peak of diffused light from the light diffusion pattern 104 _m is reduced. For this reason, when each of the light emitting elements 10r, 10g, and 10b provided in the light source 10 is turned on, the light shift due to the difference in installation position can be alleviated, and the illuminance of the emitted light emitted from the emission surface 102 can be made uniform. Is.
Note that the frame line indicating the gap 106 _n is added to improve the visibility, and does not indicate the light diffusion pattern 104 _m and the pattern shape 105.

In addition, an example in which the light source 10 includes the light emitting elements 10r, 10g, and 10b made of LEDs having emission wavelengths of red (r), green (g), and blue (b) has been shown. However, there are three light emitting elements. Not limited to. In that case, the light diffusion pattern 104 _m is arranged in a sequence of at least the number of light emitting elements plus one, and the same effect can be obtained by providing each light diffusion pattern 104 _m so as to be shifted with respect to the intersection line D. It is what you play.
(Example 3)

FIG. 12 shows another example of the light diffusion pattern 104 _m provided on the reflection surface 103 of the light guide 11 to which the present invention can be applied.
FIG. 13 shows a comparative example based on the presence or absence of the region E of the illuminance distribution (hereinafter referred to as illuminance distribution) of the emitted light in the longitudinal direction (main scanning direction) of the light guide 11.
Reference numeral 204 denotes a line indicating the illuminance distribution of the conventional outgoing light, and reference numeral 205 denotes a line indicating the illuminance distribution of the outgoing light to which the present invention can be applied.

At least two rows of light diffusion patterns 104 _m are provided on the reflective surface 103 (in this embodiment, the number of light diffusion patterns 104 _m is four rows).
For example, the light diffusion pattern 104 _m is configured by a pattern shape 105 including dots (points), and the distribution density of the pattern shape 105 gradually increases from the light incident surface 101 toward the light diffusion surface 100. At least in the vicinity of the light diffusing surface 100 which is a rough surface, the region E where the pattern shape 105 is not provided is provided.
That is, according to the distance from the light source 10, except the vicinity of the light-diffusion surface 100, the part close | similar to the light source 10 is arrange | positioned at low density, and it is the structure arrange | positioned with high density far away.
The pattern shape 105 may be any shape such as a circle or a polygon. Moreover, it is not limited to the same shape, You may change a diameter, a shape, etc. according to a density.

With this configuration, the proportion of the pattern shape 105 constituting the light diffusion pattern 104 _m gradually increases from one end where light from the light source 10 enters to the other end. For this reason, the diffusivity of the part close to the light source 10 can be lowered, and the diffusivity can be gradually increased toward the distant place. Even if there is only one light source 10, it is substantially uniform along the longitudinal direction (main scanning direction). It is possible to obtain a high illuminance.
Further, since the diffused light from the light diffusion pattern 104 _m can be reduced by the region E, the illuminance distribution in the longitudinal direction (main scanning direction) occurs in the vicinity of the light diffusion surface 100 even if the light diffusion surface 100 is left rough. The peak of diffused light is reduced. For this reason, it is possible to increase the uniformity of the illuminance of the outgoing light emitted from the outgoing surface 102.

Incidentally, without providing an area E in the light diffusion pattern 104 _m, from the end of the light diffusion pattern 104 _m pattern 105 disposed at a high density in, a low-density gradually toward the portion closer to the light diffusing surface 100 It doesn't matter if you do.

  The line illumination device of the present invention is an effective technique as an image reading device such as an image scanner, a facsimile machine, a copying machine or the like.

4 Image sensor unit 10 Light source 100 Light diffusion surface (rough surface)
102 exit surface 103 reflective surface 104 light diffusion pattern 105 pattern shape 106 gap A optical axis B normal C plane D intersection line E region

Claims (6)

A light source having a light emitting element;
A rod-shaped light guide that guides light from the light source and illuminates the illuminated body in a line; and
In the line-shaped lighting device provided with
The light guide is
A light incident surface that receives light from the light source provided on one side end surface in the longitudinal direction;
An emission surface that emits light from the light source provided on one surface along the longitudinal direction in the direction of the object to be illuminated;
A reflecting surface that reflects light from the light source provided on a surface facing the emitting surface;
A light diffusing pattern having a pattern shape for diffusing light, which is provided on the reflecting surface and is composed of at least two rows;
With
The light diffusion pattern is
A plane that intersects the optical axis of the light emitting element and the normal line to the reflection surface is provided so as to deviate from the intersection line that intersects the reflection surface,
A line-shaped illuminating device, wherein a distribution density of the pattern shape changes according to a distance from a light source. A light source having a plurality of light emitting elements;
A rod-shaped light guide that guides light from the light source and illuminates the illuminated body in a line; and
In the line-shaped lighting device provided with
The light guide is
A light incident surface that receives light from the light source provided on one side end surface in the longitudinal direction;
An emission surface that emits light from the light source provided on one surface along the longitudinal direction in the direction of the object to be illuminated;
A reflecting surface that reflects light from the light source provided on a surface facing the emitting surface;
A light diffusing pattern having a pattern shape provided on the reflecting surface for diffusing light consisting of at least the number of the light emitting elements plus one column;
With
The light diffusion pattern is
A plane that intersects the optical axis of the light emitting element and the normal line to the reflection surface is provided so as to deviate from the intersection line that intersects the reflection surface,
A line-shaped illuminating device, wherein a distribution density of the pattern shape changes according to a distance from a light source. The light guide is
A rough surface for diffusing light from the light source provided facing the light incident surface;
The light diffusion pattern is
The line illumination device according to claim 1, wherein at least a region where the pattern shape is not provided is provided in the vicinity of the rough surface. A light source having a light emitting element;
A rod-shaped light guide that guides light from the light source and illuminates the illuminated body in a line; and
In an image reading apparatus using a line illumination device comprising:
The light guide is
A light incident surface that receives light from the light source provided on one side end surface in the longitudinal direction;
An emission surface that emits light from the light source provided on one surface along the longitudinal direction in the direction of the object to be illuminated;
A reflecting surface that reflects light from the light source provided on a surface facing the emitting surface;
A light diffusing pattern having a pattern shape for diffusing light, which is provided on the reflecting surface and is composed of at least two rows;
With
The light diffusion pattern is
A plane that intersects the optical axis of the light emitting element and the normal to the reflecting surface is provided so as to deviate from the intersecting line that intersects the reflecting surface.
An image reading apparatus, wherein a distribution density of the pattern shape changes according to a distance from a light source. A light source having a plurality of light emitting elements;
A rod-shaped light guide that guides light from the light source and illuminates the illuminated body in a line; and
In an image reading apparatus using a line illumination device comprising:
The light guide is
A light incident surface that receives light from the light source provided on one side end surface in the longitudinal direction;
An emission surface that emits light from the light source provided on one surface along the longitudinal direction in the direction of the object to be illuminated;
A reflecting surface that reflects light from the light source provided on a surface facing the emitting surface;
A light diffusion pattern having a pattern shape for diffusing light consisting of a number of columns obtained by adding 1 to at least the number of the light emitting elements provided on the reflective surface;
With
The light diffusion pattern is
A plane where the optical axis of the light emitting element intersects with the normal to the reflecting surface is provided to be shifted with respect to the intersecting line intersecting the reflecting surface,
An image reading apparatus, wherein a distribution density of the pattern shape changes according to a distance from a light source. The light guide is
A rough surface for diffusing light from the light source provided facing the light incident surface;
The light diffusion pattern is
The image reading apparatus according to claim 4, wherein at least a region where the pattern shape is not provided is provided in the vicinity of the rough surface.