JPH10190960A - Linear light source device and image reader using the linear light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost of the lighting device and to markedly improve lighting energy efficiency by eliminating dispersion in the lightness over the entire lighting region to the utmost with a simple configuration, so as to reduce the number of light sources in the case of configuring the device lighting a linear region. SOLUTION: A linear light source device 10 is provided with a light- transmitting member 20 that uses a side face at one side of a long transparent member in a broadwise direction as a light emission face 21 and where a light incidence section is formed to a middle part of other side faces than the light- emitting face 21 in the lengthwise direction, and with a light source placed to a light incidence section 23 of the light-transmitting member 20, in which the light made incident from the light incidence section 23 to the light- transmitting member 20 is propagated into the inside of the light-transmitting member 20 in the lengthwise direction and emitted from the entire region or almost the entire region of the light-emitting face 21, and all or part of other the faces of the light-conducting member 20 other than the light-emitting face 21 is covered by a reflection face.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear light source device and an image reading apparatus using the linear light source device. For example, the linear light source device of the present invention can be suitably used for an image reading apparatus configured to read a document conveyed while being brought into close contact with a reading surface line by line, that is, a document illumination of a contact type image sensor. It is.

[0002]

2. Description of the Related Art FIG. 21 shows a conventional general structure of a contact image sensor. This image sensor a has an original reading surface c made of a transparent glass plate on an upper surface of a casing b.
The document e is backed up by the platen d and conveyed while being brought into close contact with the document reading surface c so that an image is read line by line.

A substrate f is mounted on the lower surface of the casing b, and a plurality of image sensor chips g each having a predetermined number of light receiving elements are mounted on the substrate f in a row. For example, in order to read an A4 width document at a reading density of 8 dots / mm, 1,728 light receiving elements are arranged at a pitch of 125 μm. For example, 96 light receiving elements are integrally formed in one image sensor chip g, and in this case, 18 image sensor chips g are mounted in one row on the substrate f.

The image sensor chips g are arranged vertically below the read line L set on the document reading surface c, and a lens array h is provided between the read line L and the image sensor chip g. Is arranged. The lens array h focuses the image on the reading line L on the 1728 light-receiving elements arranged on the plurality of image sensor chips g at the same magnification as the erect image.

A light source for illuminating the original on the reading line L is provided in a space formed below the reading surface c in the casing b. Conventionally, an LED chip j is often used as this light source, and
In order to illuminate the entire length of the read line L having a length corresponding to the width of the document, a plurality of LED chips j are arranged on the board k at equal intervals.

[0006]

However, the conventional contact type image sensor a having the above configuration has the following various problems, particularly in relation to the configuration for document illumination.

First, an LED chip j which is a point light source
Are discretely arranged, so that the brightness at a predetermined distance from the light source periodically changes in the longitudinal direction of the illumination area, so that the output of the light receiving element is not constant in the longitudinal direction of the read line L. That is, for example, even if a document having the same brightness is read along the reading line L, the output as the image sensor periodically and dynamically changes in the longitudinal direction of the line L. This leads to the deterioration of the reading quality. To compensate for such deterioration of the reading quality, a complicated correction circuit is required, which leads to an increase in the cost of this type of contact image sensor.

Second, since a plurality of LED chips j are used as a light source, the reading quality is degraded due to variations in the luminous intensity of each LED chip j. When reading a black-and-white image, such variation in the luminosity of each LED chip does not cause much problem.However, when a contact-type image sensor is configured to read a color image, the quality of the read image is significantly deteriorated. Connect. When an image sensor for reading a color image is configured using a common reading element, light sources of three colors of R, G, and B are arranged, and an image of each color is read line by line while switching the color light emitted from the light source. However, when the luminous intensity of the LED chips varies as described above, the color tone varies in the width direction of the image at the stage where the image data for each color is configured and the color image is reproduced. Such a variation in color tone is visually emphasized more than expected, so that the quality of the reproduced color image is significantly reduced. Such color tone correction must be performed through complicated adjustments while accurately measuring the luminous intensity and color variation of each LED chip, and this type of contact image sensor can withstand low-cost mass production. Not something.

Third, when a single image sensor is formed, a plurality of LED chips j are required as a light source for illumination, so that the manufacturing cost increases accordingly. In particular, in order to minimize the change in illumination brightness on the document reading surface c, it is necessary to set the distance from the document reading surface to the LED chip to be relatively long. However, in that case, only a small amount of light emitted from the light source can be substantially used as illumination light, and much light is wasted. Therefore, the lighting energy efficiency is extremely poor.

The present invention has been conceived under such circumstances, and solves each of the problems of the prior art as described above and provides a mechanism for illuminating a linear area. In addition, it is possible to reduce the variation in brightness over the entire length of the illumination area as much as possible with a simple configuration, reduce the number of light sources and reduce the cost of the illumination device,
It is an object to remarkably improve the illumination energy efficiency.

[0011]

DISCLOSURE OF THE INVENTION In order to solve the above problems, the present invention employs the following technical means.

In the linear light source device provided by the first aspect of the present invention, the first side face in the thickness direction of the long transparent member is used as the light emission face, and the side face other than the light emission face is used. A light guide member having a light incident portion formed at a longitudinal middle portion thereof, and a light source disposed at the light incident portion of the light guide member, and light incident on the light guide member from the light incident portion. A linear light source device that is advanced in the longitudinal direction inside the light guide member and emits light from the entire area or substantially the entire area of the light emission surface, wherein the light guide member has a surface other than the light emission surface. It is characterized by being entirely or partially covered with a reflective surface.

In a preferred embodiment, the first side surface of the light guide member forming the light exit surface is a mirror-finished surface. The light incident portion is formed at a longitudinally intermediate portion of the second side surface facing the mirror-finished first side surface.

Light incident on the mirror-finished surface of the light guide member from the inside thereof is larger than a critical incident angle (the incident angle is an angle with respect to the normal of the boundary surface) defined by the refractive index of the light guide member. In the case of the incident angle, the light is totally reflected on the surface and returns to the inside of the light guide member. In the light guide member having the above configuration, the light incident from the light incident portion travels in the longitudinal direction of the light guide member while being reflected on the mirror-finished boundary surface. When the incident angle on the light exit surface of the first side surface is smaller than the critical incident angle while the light travels in the longitudinal direction of the light guide member, the light is emitted from the light exit surface to the outside. Is done. In this manner, for example, one light incident portion is provided at the middle portion in the longitudinal direction of the light guide member, and light from the light incident portion light source is introduced, so that the first light guide member has a longitudinal side. Light can be uniformly emitted from the entire area of the light emission surface formed linearly in the direction.

In the invention of the present application, in particular, all or a part of the light guide member other than the light exit surface is covered with a reflection surface. As described above, the light incident into the light guide member from the light incident portion travels in the longitudinal direction of the light guide member while repeating total reflection on the surface of the light guide member, but the light emission portion is formed. Light may enter the surface other than the first side surface at an angle smaller than the critical incident angle. In this case, light is radiated from the outer surface of the light guide member, and the illumination efficiency is reduced accordingly. However, in the present invention, all or a part of the surface of the light guide member other than the light exit surface, more specifically, incidence from the inside of the light guide member at an angle smaller than the critical incident angle as described above. The reflection surface is arranged so as to cover the assumed side surface. Therefore, even if light is emitted from a surface other than the light exit surface of the light guide member,
This light is returned to the light guide member again by the reflection surface, and waste of light from the light source is suppressed as much as possible. As a result, the illumination efficiency of the linear light source device can be significantly improved as a whole.

In a preferred embodiment, a portion of the first side surface facing the light incident portion has a mirror-finished surface, a total reflection surface, or a composite surface thereof.
A V-shaped or substantially V-shaped concave portion having two inclined surfaces is formed, and the light incident from the light incident portion is totally reflected by the inclined surface, and is directed toward the longitudinal end of the light guide member. It is configured to proceed. The configuration of such a recess is
This is a configuration for effectively avoiding that much of the light introduced into the light guide member from the light incident portion passes through the light guide member and exits as it is. That is, when the concave portion is not formed, the angle of incidence on the first side near the light incident portion becomes smaller than the critical angle of incidence, and most of the light reaching the first side from the inside is directly reflected on the first side. And it is emitted outside. In such a case, it appears from the outside as a luminescent spot in the longitudinal middle part of the light emitting surface of the light guide member, and as a linear light source device, uneven emission of light from the light emitting surface is hindered. . In the above configuration, by forming the V-shaped concave portion, the incident angle of light from the inside of the light guide member to the inclined surface is increased to promote total reflection of light, and the appearance of the bright spot as described above Can be effectively avoided. This recessed part may be entirely mirror-finished,
A total reflection surface formed by partially depositing a glossy metal or the like may be used. By selecting the formation region of the total reflection surface, the variation in the amount of light emitted from the light emission surface of the first side surface is adjusted, and the amount of light from the linear light emission surface is made as uniform as possible. be able to.

According to the linear light source device provided by the second aspect of the present invention, the first transparent member on one side in the thickness direction of the elongated transparent member is provided.
A light guide member having a light exit surface having a mirror-finished surface over substantially the entire side surface, a light entrance portion formed at a longitudinal middle portion of a second side surface facing the light exit surface in the thickness direction, and A light source disposed at the light incident portion of the member, the light incident on the light guide member from the light incident portion travels in the longitudinal direction inside the light guide member, the entire area of the light exit surface or A linear light source device configured to emit light from substantially the entire area, wherein a means for preventing light emitted from a light emitting surface of the light guide member from spreading in a width direction of the light guide member is provided. I have.

In a preferred embodiment, the lens member is disposed along the light exit surface so as to prevent the light emitted from the light exit surface from spreading in the width direction of the light guide member. I have.

In another preferred embodiment, the lens portion is integrally formed on the light emitting surface to prevent light emitted from the light emitting surface from spreading in the width direction of the light guide member.

In yet another preferred embodiment,
By arranging the reflecting surface along the light emitting surface, the light emitted from the light emitting surface is prevented from spreading in the width direction of the light guide member.

A linear light source device according to the present invention illuminates a linear illumination area such as a reading line set on a document reading surface of an image sensor. Therefore, it is desirable that the light emitted from the light emission surface of the light guide member efficiently illuminates the band-shaped linear region having the predetermined width. Such a request is realized by the configuration of the second aspect of the present invention. The lens member disposed on the light exit surface or the lens unit integrally formed on the light exit surface has a convex lens form in its cross section. Thus, light emitted from the light exit surface of the light guide member with a spread can be focused on the linear illumination region, and more efficient illumination can be achieved.

When the reflecting surface is arranged along the light emitting surface of the light guide member, the reflecting surface has a shape like a concave mirror in a cross section. Even with such a configuration, it is possible to achieve the same improvement in illumination efficiency as described above.

Of course, the linear light source device can be configured by combining the configuration of the first aspect and the configuration of the second aspect of the present invention. In this case, the lighting efficiency is further improved.

In a preferred embodiment which is common to the first and second aspects of the present invention, R, G and B LEDs of three colors are used as the light source disposed at the light incident portion. Are arranged in the width direction.

That is, the light source device having such a configuration can be suitably used as a light source device of a contact type image sensor configured to read a color image. In each color, the uneven distribution of the illumination intensity in the longitudinal direction of the reading area is eliminated, and since the LEDs of each color are arranged in the width direction of the light guide member, the position of the light source device of each color with respect to the linear illumination area in the longitudinal direction. At the same position, uneven distribution of the illumination intensity between the colors can be avoided.

Further, blue (B) color and green (Pure G)
reen) LEDs that emit color are practically used, but in view of the price that is several times to several tens times that of an LED that emits yellow-green or red (R), according to the present invention, R , G, and B can be used to configure a light source device for reading a color image by using one LED of each color. This means that remarkable cost reduction of the contact type color image sensor can be expected.

In the linear light source device provided by the third aspect of the present invention, substantially the entire area of the first side face on one side in the thickness direction of the long transparent member is formed as a mirror-finished light emitting surface, A light guide member having a light incident portion formed on an end face in a longitudinal direction; and a light source disposed at the light incident portion of the light guide member, wherein the light incident from the light incident portion into the light guide member is guided by the light guide member. A linear light source device that travels in the longitudinal direction inside the light member and emits light from the entire area or substantially the entire area of the light emitting surface, and all or all of the light guide member other than the light emitting surface. It is characterized in that a part is covered with a reflective surface.

While the above-described linear light source device provided by the first aspect of the present invention has the light incident part and the light source arranged at the longitudinal middle part of the light guide member, the line according to the second aspect is provided. The light source device is a light source device in which an end face of the light guide member is a light incident portion and a light source is disposed in the light incident portion. Other configurations of the light guide member are provided by the first side surface. It is similar to the configuration of the light guide member used for (1). That is, the light incident on the light guide member from the light incident portion travels in the longitudinal direction of the light guide member while repeating total reflection at the boundary surface of the light guide member, and the critical incident angle is incident on the first side surface which is the exit surface. Light incident at an angle smaller than that is emitted to the outside of the first side surface, so that light is emitted from the entire area of the linear emission surface. Also in this case, by arranging the reflection surface covering the surface other than the emission surface of the light guide member, the light emitted from the outer surface of the light guide member can be returned to the light guide member again, and the illumination energy efficiency is significantly increased. You can do it.

The image reading device provided by the fourth aspect of the present invention is a device for transmitting light from a light source device provided in the casing to a document conveyed in contact with a document reading surface formed on one surface of the casing. Irradiating, the image reading device to receive the reflected light from the document in the reading line set on the document reading surface to a plurality of light receiving elements arranged in the reading line direction in the casing, As the light source device, a linear light source device having the above-described configuration is used, and light emitted from the light emission surface illuminates the original on the reading line.

The advantages of such an image reading apparatus will be apparent from the above description of the linear light source apparatus.

In a preferred embodiment of the image reading apparatus, a reflection surface covering all or a part of the light guide member other than the light exit surface can be formed by utilizing the inner surface of the casing.

That is, the reflective surface is formed by using a member having a glossy surface formed by depositing a glossy metal on the surface of a plate material such as a glossy metal plate or a resin plate, or a plate material coated with white. However, by using a selected area of the inner surface of the casing as a reflective surface formed of a glossy surface or a white painted surface without using such a separate member, it is possible to reduce the number of members, The effect of the linear light source device of the invention can be expected.

[0033] Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a partial sectional side view of a first embodiment of a linear light source device 10 according to the present invention, FIG. 2 is a plan view, and FIG. 4 of FIG.
FIG. 5 is an enlarged sectional view taken along line VV of FIG. 1, and FIG. 6 is an exploded perspective view.

The linear light source device 10 includes, for example, a PM
The light guide member 20 obtained by molding an acrylic transparent resin such as MA occupies the main part. This light guide member 20
Is a long member having a predetermined longitudinal dimension,
A first side surface 20A in the vertical thickness direction, and the first side surface 20A
20B, a third side surface 20C and a fourth side surface 20D facing each other in the left-right width direction, and a longitudinal end surface 2
0E and 20E.

The first side surface 20A is preferably a mirror-finished flat surface. As will be described later, the first side surface 20A functions as a linear light emitting surface 21 having a predetermined width. The second side surface 20B is an inclined surface whose distance from the first side surface 20A is gradually reduced from the center in the longitudinal direction toward the end portion, and the surface of the second side surface 20B has the width of the light guide member 20. Groove 2 with a circular cross section extending in the direction
2 are formed over the entire length.
In this embodiment, the second side surface 20B
Is set as the light incident part 23 in the longitudinal direction. Further, as is best seen in FIGS. 4 and 6,
Third side surface 20C and fourth side surface 20D opposed in the width direction
The distance between them is reduced toward the first side surface 20A which is the light exit surface 21. As a result, the light guide member 20 is moved from the second side surface 20B where the light incident portion 23 is formed to the light exit surface. 21 is a trapezoidal cross section, the width of which is reduced toward the first side surface 20A.

The first side surface 20 of the light guide member 20
A, that is, the second side surface 2
A substantially V-shaped concave portion 24 formed by two inclined surfaces 24a and 24b is formed at a portion facing the light incident portion 23 set to 0B in the vertical thickness direction.

The light guide member 20 having the above-described structure can have a mirror-finished surface on all outer surfaces. The mirror-finished surface is a concept that includes not only obtaining a mirror surface by polishing but also obtaining a smooth surface by molding with a mold. However, a selected region of the outer surface of the light guide member 20 can function as a total reflection surface by, for example, attaching a glossy metal. In the embodiment shown in the drawings, the substantially V-shaped recess 2 of the first side surface is used.
4 selected area, that is, the V-shaped recess 2
The valley bottom and the portion connecting the inclined surfaces 24a and 24b and the flat first side surface 20A are defined as the total reflection surface as described above.

The light incident portion 23 formed at the central portion in the longitudinal direction of the second side surface 20B is formed by a groove 23a extending in the width direction of the light guide member 20, as is well shown in FIG. The light incident portion 23 has an LE as a light source 30.
D is arranged. In the embodiment shown in the figure, as best seen in FIG.
The three LEDs 30R, 30G, and 30B of G and B are arranged in the width direction of the light guide member 20. The light incident part 23
The groove 23a forming the LED is provided with the LEDs 30R, 30G,
30B has a width capable of fitting properly, and therefore, the concave groove 23a is provided with the LEDs 30R, 30G, 30B.
Of the light guide plate in the longitudinal direction.

The linear light source device 10 further includes most of the outer surface except for the first side surface 20A which is the light exit surface 21 of the light guide member 20, that is, the second side surface 20B and the third side surface 20C.
And a reflection surface 40 that covers the fourth side surface 20D.
The reflection surface 40 can be obtained by bending a thin metal plate having a glossy surface into a channel shape corresponding to the cross-sectional shape of the light guide member 20, as best seen in FIGS. That is, the member 41 forming the reflection surface 40 in the illustrated embodiment includes a bottom surface portion 41a along the second side surface 20B, and rises from both sides of the bottom surface portion 41a to form the third portion of the light guide member 20. A side surface portion 41b extending along each of the side surface 20C and the fourth side surface 20D,
41c. On the bottom surface portion 41a, three LEDs 30R, 30G of R, G, and B carried on the substrate 31 are provided.
A window hole 42 facing 30B is formed. As shown in FIG. 6, the light guide member 20 is slid into the reflection surface forming member 41, and the light guide member 20 is inserted through the window hole 42 provided in the bottom surface 41 a of the reflection surface formation member 41.
By fitting the LEDs 30 </ b> R, 30 </ b> G, and 30 </ b> B into the light incident portion 23 of the light guide member 20,
0 can be easily assembled. The reflection surface forming member 41 may be formed by bending a glossy metal thin plate, or by using a glossy metal foil attached to the inner surface of a resinous thin plate. Those coated with white paint can also be used.

Most of the outer surface of the light guide member 20 made of a transparent member is a so-called mirror-finished surface.
The light that reaches this mirror-finished surface from inside the light guide member 20 proceeds as follows depending on the incident angle. That is, the light that has entered the boundary surface at an angle larger than the so-called critical incidence angle is totally reflected without being emitted to the outside. The light incident at an angle smaller than the critical incident angle is transmitted through the boundary surface and emitted to the outside. The total reflection on such a mirror-finished surface is 100% total reflection, and there is almost no loss. On the other hand, light that reaches from the inside to the total reflection surface 40 formed by deposition of a glossy metal or the like is totally reflected regardless of the incident angle. However, such reflection by the total reflection surface causes some loss.

Referring to FIG. 3, LED 3 as light source 30
Light incident from the light guides 0R, 30G, and 30B is incident on the inside of the light guide member 20 with a radiation angle of approximately 180 ° in a side view. In the present embodiment, two inclined surfaces 24 are provided at portions opposed to the light incident portion 23 in the thickness direction of the light guide plate.
A substantially V-shaped concave portion 24 composed of a and 24b is formed. Therefore, the angle of incidence of the light traveling from the light source 30 in the thickness direction of the light guide plate member 20 to the inclined surfaces 24a and 24b can be made larger than the critical incidence angle, and thus, the light can be guided from the light source 30 as described above. Most of the light traveling in the thickness direction of the optical member 20 is formed on the inclined surfaces 24a and 24b forming the V-shaped recess 24.
The traveling direction is changed by total reflection, and the light is guided toward both ends in the longitudinal direction of the light guide member 20. In the present embodiment, in particular, near the valley bottom of the concave portion 24, the inclined surfaces 24a and 24b forming the concave portion 24, and the first side surface 2
Since the total reflection surface 25 is formed at the boundary with 0A, it is possible to effectively prevent the light from the light source 30 from transmitting from these portions to form a bright spot.

The light traveling in the longitudinal direction of the light guide member 20 as described above further travels toward the longitudinal end while repeating total reflection on each side surface of the light guide member 20, and the light exit surface 21 In the first side surface 20A, the light incident at an angle smaller than the critical incident angle is emitted to the outside. Ideally, it is desirable that the light is uniformly emitted from the entire area of the linear light emitting surface 21 having a certain dimension in the longitudinal direction. In this manner, uniform light emission from the light emitting surface 21 is realized. In order to do so, the following measures have been taken.

That is, as described above, the light guide member 20
The concave and convex surface is formed on the second side surface 20 </ b> B by forming a plurality of concave grooves 22 having a circular arc cross section extending in the width direction of the light guide member 20 in the longitudinal direction. This uneven surface may also be a mirror-finished surface achieved by molding. Light incident on the surface of the concave groove 22 in substantially the same direction from inside the light guide member 20 is radially dispersed and reflected. However, also in this case, under the condition that the incident angle is larger than the critical incident angle. In this way,
A part of the light whose traveling direction has been changed in the thickness direction of the light guide member 20 is emitted outside from the first side surface 20A which is the emission surface 21.

The light source 30 is located at the center of the light guide member 20 in the longitudinal direction.
In this embodiment where the light sources 3 are arranged,
It is considered that the light density is high when the distance is close to 0, and the light density decreases toward the end. Therefore,
It is desired that the distance between the concave grooves 22 formed on the second side surface 20 </ b> B decreases toward the end of the light guide member 20. In this way, the amount of light whose traveling direction is changed in the vertical thickness direction of the light guide member 20 by the inner surface of the concave groove 22 increases toward the end of the light guide member 20,
By compensating that the light density decreases toward the end of the light guide member 20 as described above, the light emitted from the light exit surface 21 can be made uniform.

In the present embodiment, the uneven surface is formed by a concave groove 22 extending in the width direction of the light guide member 20. Therefore, the light reflected by the inner surface of the concave groove 22 is prevented from spreading in the width direction of the light guide member 20, and wasteful light from the third side surface 20C and the fourth side surface 20D in the width direction of the light guide member 20 is externally transmitted. Outgoing to the outside as much as possible.

Part of the light incident on the uneven surface formed on the second side surface 20B from inside the light guide member is
Although the light is emitted to the outside from 0B, the light emitted to the outside is reflected by the reflection surface 40 and returned to the inside of the light guide member 20 from the second side surface 20B again. Also, some of the light incident on these side surfaces from the inside may be emitted to the outside also from the third side surface 20C and the fourth side surface 20D of the light guide member 20, and such light is also in the above-described manner. The light is reflected by the reflection surface 40 and returned inside the light guide member 20. By these things, the light source device 10
High efficiency can be achieved.

In this embodiment, the thickness of the light guide member 20 in the vertical direction is reduced from the center in the longitudinal direction to both ends. This compensates for a decrease in the density of light in the light guide member 20 as the distance from the light source 30 increases, and allows uniform emission of light from the linear light emission surface 21 having a certain length in the longitudinal direction. Can be achieved.

In the present embodiment, the light guide member 2
0 is the second side surface 2 as shown in FIG. 4 and FIG.
It has a trapezoidal cross section whose width is gradually reduced from 0B toward the first side surface 20A which is the light emitting surface 21.
Thus, the light from the light source 30 can be efficiently transmitted to the entire area of the light guide member 20, and the light having a constant density can be efficiently emitted from the linear emission surface 21.

Further, in this embodiment, LEDs 30R, 30G, and 30B of three colors of R, G, and B are used as the light source 30.
Are arranged in the width direction of the light guide member 20. LED of each color
Since the positions of the light guide members 20 in the longitudinal direction of the light guide members 30R, 30G, and 30B are the same, the LEDs 30R, 30
The distribution of the amount of light emitted from the light exit surface 21 in the lighting state of G and 30B can be made the same for each color.

The LEDs 30R, 30G, 30 of each color
By adjusting the output of B, full-color light emission becomes possible. Also, the LEDs 30R, 30G, 30B of each color
Are sequentially switched to emit light, so that the light source device 10 of the contact type color image sensor 50 in which the light receiving element is commonly used can be appropriately functioned.

FIGS. 7 and 8 show a contact type color image sensor 50 using the linear light source device 10 shown in FIGS. The image sensor 50 is provided with an image reading surface 52 made of a transparent glass plate on the upper surface of a casing 51. It is configured to read line by line. A substrate 54 is mounted on the lower surface of the casing 51, and a plurality of image sensor chips 55 in which a predetermined number of light receiving elements are built are mounted on the substrate 54 in a row. For example, in order to read an A4 width document at a reading density of 8 dots / mm, 1,728 light receiving elements are arranged at a pitch of 125 μm. For example, 96 light receiving elements are integrally formed in one image sensor chip 55. So, in this case,
Eighteen image sensor chips 55 are arranged on the substrate 54.

The plurality of image sensor chips 55 are arranged vertically below the reading line La set on the image reading surface 52, and a lens is provided between the reading line La and the image sensor chip 55. An array 56 is arranged. The lens array 56 focuses the image on the read line La on the 1728 light receiving elements on the plurality of image sensor chips 55 at the same magnification as the erect image. The image reading surface 5 in the casing 51
The linear light source device 10 of the present invention having the configuration shown in FIGS. 1 to 6 is disposed in a space set below the lens array 56 and beside the lens array 56. In this case, the light guide member 20 is arranged such that the center line Lb in the left-right width direction faces the reading line La on the image reading surface 52.

As already described, from the linear light emitting surface 21 of the light guide member 20 of the linear light source device 10, uniform light is emitted over the entire area in the longitudinal direction. The light emitted in this manner efficiently illuminates a band-shaped region of the image reading surface 52 along the reading line La. Then, while the document D is being sent at a predetermined pitch, the image data of the R, G, and B colors of the image of the document on the reading line La is turned on and off by the image sensor chip 55 while switching the LEDs 30R, 30G, and 30B of each color. Read sequentially.

In the contact type color image sensor 50, the linear light source device 10 includes one LED 30R for each color.
Since light emitted from 30G and 30B is evenly applied to an illumination area of a predetermined length, uneven distribution of light in the reading width direction, which is assumed when a plurality of LEDs are used,
It is possible to effectively eliminate a deterioration factor of image reading quality such as a change in color tone of a read image due to a subtle difference in emission color of each LED. In addition, each color LED 30
Since the R, 30G, and 30B are arranged at the same position in the longitudinal direction of the light guide member 20, a change in the color tone of the read image which is assumed when the LEDs of each color are arranged in the read width direction can be effectively avoided. can do. Further, the light guide member 2
The light that has traveled inside the light guide member 20 is the first side surface 20A of the light guide member 20.
Are intensively radiated from the light emitting surface 21 having a narrow line shape at, the illumination efficiency is very good, and one LED 30 of each color is used.
Despite using R, 30G, and 30B, a sufficient amount of illumination light can be secured. Further, LEDs 30R, 30 serving as light sources are provided in the middle portion of the light guide member 20 in the longitudinal direction.
G, 30B are arranged, for example, the light guide member 2
0 compared to placing a light source at the end of
One longitudinal dimension is saved, and the miniaturization of this type of close contact type image sensor 50 is promoted.

In each of the above-described embodiments, the reflection surface 40 covering the side surface of the light guide member 20 other than the light exit surface 21 has a slight clearance between the second side surface 20B, the third side surface 20C, and the fourth side surface 20D. Although it is configured to cover, for example, as shown in the cross section in FIG.
It may be configured so as to cover only the side surface 20D.
The third side surface 20C and the fourth side surface 2
You may comprise so that OD may be covered with the clearance which spreads upwards.

In the embodiment shown in FIG. 10, the reflection surface 41b covering the third side surface 20C and the reflection surface 41c covering the fourth side surface 20D are widened upward, so that these reflection surfaces 41b, The light 41c can not only return the light leaking out of the light guide member 20 to the light guide member but also play a role of irradiating the light toward the illumination area by reflection.

FIG. 11 shows a linear light source device 1 according to the present invention.
0 shows another embodiment in cross section. In this embodiment, the light guide member 20 itself can employ the same one as shown in FIGS.
A feature of this embodiment is that a lens member 60 for preventing light emitted from the light emitting surface 21 from spreading in the width direction of the light guide member 20 is arranged along the light emitting surface 21. That is the point. The lens member 60 includes a flat surface 60a corresponding to the flat exit surface 21 and an arc surface 60b.
In the form of a convex lens. However, the lens member 60 has a uniform cross section in the longitudinal direction of the light guide member 20. By adding such a convex lens member 60, the light emitted from the light exit surface 21 of the light guide member 20 can be radiated more intensively toward the illumination area, and a more efficient light source device can be provided. Is achieved.

FIG. 12 shows the linear light source device 1 shown in FIG.
0 is a modification example. In this case, a lens portion for suppressing the spread of the light emitted from the light exit surface 21 in the width direction of the light guide member is integrally formed on the light exit surface 21 of the light guide member 20. By doing so, it is possible to expect an effect similar to that of the above-described embodiment in that the illumination area can be more efficiently illuminated.

FIG. 15 is a sectional view showing still another embodiment of the linear light source device according to the present invention. In this embodiment, the light guide member 20 itself can employ the same one as shown in FIGS. The feature of this embodiment is that the light exit surface 21
This is a point that a reflection surface 70 for preventing the light emitted from the light emitting surface from spreading in the width direction is disposed on both sides in the width direction of the light emitting device. The reflecting surface 70 is shaped like a concave mirror in cross section, and has a uniform cross section in the longitudinal direction. With such a configuration, the light emitted from the light exit surface 21 of the light guide member 20 can be radiated intensively toward the illumination area, and a more efficient light source device is realized.

FIG. 13 is a cross-sectional view showing still another embodiment of the linear light source device 10 according to the present invention. In this embodiment, the reflection surface 40 that covers the side surface of the light guide member 20 other than the light exit surface 21 is provided.
The illumination efficiency is further increased by providing a lens member 60 similar to that shown in FIG.

FIG. 14 is a sectional view showing still another embodiment of the linear light source device 10 according to the present invention. In this embodiment, the second side surface 20B and the third side surface 20B of the light guide member 20 integrated with the convex lens portion as shown in FIG.
C, and a total reflection surface 25 formed by depositing a glossy metal on the fourth side surface 20D. This also realizes a linear light source device whose illumination efficiency is significantly improved.

The present invention is not limited to the above embodiments. First, the light guide member 20 is moved from the light incident portion 23 to the light guide member 20.
Is made to travel in the longitudinal direction of the light guide member 20,
In the embodiment shown in FIGS. 1 to 6, an uneven surface is formed on the second side surface 20 </ b> B of the light guide member 20 as means for emitting the light uniformly from the light emission surface 21 in the longitudinal direction of the light guide member 20. For example, as shown in FIG. 18, the second side surface 20B which is basically a mirror-finished surface,
A plurality of coating areas 26 may be provided. In this case, white is desirable as the coating color. In the coating area 26, light from the inside of the light guide member 20 can be irregularly reflected, and a part of the light irregularly reflected in this way reaches the first side surface 20A at an angle smaller than the critical incident angle. And is emitted outside. Further, since the light source 30 is disposed at the central portion in the longitudinal direction of the light guide member 20, the coating width of the white paint is adjusted to compensate for a decrease in light density as the distance from the light source increases. While increasing toward the end of 20,
The vertical dimension of the light guide member 20 is reduced toward the end.

In addition to providing the irregular reflection area by white painting as described above, an irregular reflection area may be provided by providing fine irregularities by molding or processing, for example, as shown in FIG.

In the above description, the light source 30 is disposed at the longitudinal middle part of the light guide member 20. However, as shown in FIG. 30 may be arranged. Also in this case, providing the reflection surface 40 covering the side surface excluding the light emission surface 21 and / or arranging a lens member on the light emission surface or forming an integral lens portion is adopted. Accordingly, it is possible to expect the same operation and effect as described in each of the above-described embodiments that the illumination efficiency can be increased.

Further, the image sensor 50 shown in FIG.
In (2), a separate member 41 was used as the reflection surface 40 covering the emission surface other than the light emission surface of the light guide member 20, but as shown in FIG. The reflection surface 40 can also be formed by forming a glossy surface or a white painted surface in the region. In this case, the number of members is reduced, and cost reduction can be expected by reducing the number of assembly steps.

Further, in the embodiment shown in FIGS. 1 to 6, the light source is arranged at one central portion in the longitudinal direction when the light source is arranged at the intermediate portion in the longitudinal direction of the light guide member 20. If it is a part, the light source 30 may be arranged at two or more places.

[Brief description of the drawings]

FIG. 1 is a partial sectional side view showing an embodiment of a linear light source device according to the present invention.

FIG. 2 is a plan view of a light guide member in the linear light source device of FIG.

FIG. 3 is a partially enlarged side view of the linear light source device of FIG. 1;

FIG. 4 is an enlarged sectional view taken along the line IV-IV in FIG.

FIG. 5 is an enlarged sectional view taken along line VV of FIG.

FIG. 6 is an exploded perspective view of the linear light source device of FIG.

FIG. 7 is a sectional view showing an embodiment of the image reading apparatus according to the present invention.

8 is a sectional view taken along the line VIII-VIII in FIG.

FIG. 9 is a sectional view showing another embodiment of the linear light source device according to the present invention.

FIG. 10 is a sectional view showing still another embodiment of the linear light source device according to the present invention.

FIG. 11 is a sectional view showing still another embodiment of the linear light source device according to the present invention.

FIG. 12 is a sectional view showing still another embodiment of the linear light source device according to the present invention.

FIG. 13 is a sectional view showing still another embodiment of the linear light source device according to the present invention.

FIG. 14 is a sectional view showing still another embodiment of the linear light source device according to the present invention.

FIG. 15 is a sectional view showing still another embodiment of the linear light source device according to the present invention.

FIG. 16 is a partial sectional side view showing still another embodiment of the linear light source device according to the present invention.

FIG. 17 is a sectional view taken along the line XVII-XVII in FIG. 16;

FIG. 18 is a side view showing still another embodiment of the linear light source device according to the present invention.

FIG. 19 is a partial cross-sectional side view showing still another embodiment of the linear light source device according to the present invention.

FIG. 20 is a sectional view showing another embodiment of the image reading apparatus according to the present invention.

FIG. 21 is a sectional view showing a conventional example.

[Explanation of symbols]

 Reference Signs List 10 linear light source device 20 light guide member 20A first side surface 20B second side surface 21 light emitting surface 22 concave groove 23 light incident portion 24 concave portion 24a, 24b inclined surface 25 total reflection surface 30 light source 30R red (R) light emitting LED 30G Green (G) light-emitting LED 30B Blue (B) light-emitting LED 40 Reflecting surface 41 Reflecting surface forming member 50 Close-contact color image sensor 51 Casing 52 Image reading surface 53 Platen 54 Substrate 55 Image sensor chip 56 Lens array La Reading line D Document

Claims (13)

[Claims] 1. A first transparent member on one side in a thickness direction of a long transparent member.
A light guide member having a side surface as a light exit surface, a light entrance portion formed at a longitudinal middle portion of the side surface other than the light exit surface, and a light source disposed at the light entrance portion of the light guide member. A linear light source device in which light that has entered the light guide member from the light incident portion travels in the longitudinal direction inside the light guide member, and is emitted from the entire or substantially entire area of the light emission surface. A linear light source device, wherein a whole or a part of the light guide member other than the light exit surface is covered with a reflective surface. 2. A first transparent member on one side in a thickness direction of a long transparent member.
A light guide member having a light exit surface having a mirror-finished surface over substantially the entire side surface, a light entrance portion formed at a longitudinal middle portion of a second side surface facing the light exit surface in the thickness direction, and A light source disposed at the light incident portion of the member, the light incident on the light guide member from the light incident portion travels in the longitudinal direction inside the light guide member, the entire area of the light exit surface or A linear light source device that emits light from substantially the entire area, wherein a whole or a part of a surface of the light guide member other than the light emission surface is covered with a reflection surface. 3. A V-shaped or substantially V-shaped surface having two inclined surfaces, which are mirror-finished surfaces, total reflection surfaces, or a composite surface thereof, at a portion of the first side surface facing the light incident portion. Is formed, the light incident from the light incident portion is configured to be totally reflected on the inclined surface and travel in the longitudinal direction end direction of the light guide member,
The linear light source device according to claim 1. 4. A first transparent member on one side in a thickness direction of a long transparent member.
A light guide member having a light exit surface having a mirror-finished surface over substantially the entire side surface, a light entrance portion formed at a longitudinal middle portion of a second side surface facing the light exit surface in the thickness direction, and A light source disposed at the light incident portion of the member, the light incident on the light guide member from the light incident portion travels in the longitudinal direction inside the light guide member, the entire area of the light exit surface or A linear light source device that emits light from substantially the entire area, along the light emission surface of the light guide member,
A linear light source device, comprising: a lens member for preventing light emitted from the light exit surface from spreading in the width direction of the light guide member. 5. The first transparent member on one side in the thickness direction of the long transparent member.
A light guide member having a light exit surface having a mirror-finished surface over substantially the entire side surface, a light entrance portion formed at a longitudinal middle portion of a second side surface facing the light exit surface in the thickness direction, and A light source disposed at the light incident portion of the member, the light incident on the light guide member from the light incident portion travels in the longitudinal direction inside the light guide member, the entire area of the light exit surface or A linear light source device configured to emit light from substantially the entire area, wherein the light exit surface of the light guide member is provided to prevent light emitted from the light exit surface from spreading in the width direction of the light guide member. A linear light source device, wherein a lens portion is integrally formed. 6. The first transparent member on one side in the thickness direction of the long transparent member.
A light guide member having a light exit surface having a mirror-finished surface over substantially the entire side surface, a light entrance portion formed at a longitudinal middle portion of a second side surface facing the light exit surface in the thickness direction, and A light source disposed at the light incident portion of the member, the light incident on the light guide member from the light incident portion travels in the longitudinal direction inside the light guide member, the entire area of the light exit surface or A linear light source device that emits light from substantially the entire area, along the light emission surface of the light guide member,
A linear light source device, comprising a reflection surface for preventing light emitted from the light emission surface from spreading in the width direction of the light guide member. 7. A V-shaped or substantially V-shaped surface having two inclined surfaces, which are a mirror-finished surface, a total reflection surface, or a composite surface thereof, at a portion of the first side surface facing the light incident portion. Is formed, the light incident from the light incident portion is configured to be totally reflected on the inclined surface and travel in the longitudinal direction end direction of the light guide member,
The linear light source device according to claim 4. 8. The linear light source device according to claim 4, wherein all or a part of the light guide member other than the light exit surface is covered with a reflection surface. A linear light source device. 9. The linear light source device according to claim 1, wherein the reflection surface is a white surface or a glossy surface. 10. A light source disposed at a light incident portion of the light guide member, the light source comprising three of R, G, and B arranged in the width direction of the light guide member.
The linear light source device according to claim 1, wherein the linear light source device is a color LED. 11. A light guide member in which substantially the entire first side surface on one side in the thickness direction of a long transparent member is a mirror-finished light exit surface, and a light incident portion is formed on a longitudinal end surface. A light source disposed at the light incident portion of the light guide member, the light emitted from the light incident portion into the light guide member travels in the longitudinal direction inside the light guide member, and the light emission A linear light source device configured to emit light from the entire area or substantially the entire area of the surface, wherein all or a part of a surface of the light guide member other than the light emission surface is covered with a reflection surface, Light source device. 12. A document conveyed in contact with a document reading surface formed on one surface of a casing is irradiated with light from a light source device provided in the casing, and a reading line set on the document reading surface is provided. 2. An image reading apparatus according to claim 1, wherein the plurality of light receiving elements arranged in the casing in the reading line direction receive reflected light from the original in the image reading apparatus.
12. An image reading apparatus, comprising the linear light source device according to claim 11, wherein light emitted from a light emitting surface illuminates a document on the reading line. 13. The image reading device according to claim 12, wherein a reflection surface that covers all or a part of a surface of the light guide member other than the light exit surface is formed using an inner surface of the casing. .