JP3495202B2 - Linear light source device, light guide member used for the same, and image reading device including linear light source using this light guide member - Google Patents

Description

Detailed Description of the Invention

The present invention relates to a linear light source device, a light guide member used for the linear light source device, and an image reading device having a linear light source using the light guide member. For example, the linear light source device of the present invention can be suitably used for an image reading device configured to read a document conveyed while being brought into close contact with the reading surface line by line, that is, for document illumination of a contact image sensor.

[0002]

2. Description of the Related Art A conventional general structure of a contact image sensor is shown in FIG. This image sensor a has an original reading surface c made of a transparent glass plate on the upper surface of a casing b.
The image of the document e conveyed while being backed up by the platen d so as to be in close contact with the document reading surface c is read line by line.

A substrate f is attached to the lower surface of the casing b, and a plurality of image sensor chips g having a predetermined number of light receiving elements are attached to the substrate f in a row. For example, in order to read a document of A4 width at a reading density of 8 dots / mm, the light receiving element is
1728 pieces are arranged at a pitch of 5 μm. For example, 96 light receiving elements are integrally formed in one image sensor chip g. Therefore, in this case, 18 image sensor chips g are mounted in a line on the substrate f.

The image sensor chip g is arranged vertically below the reading line L set on the original reading surface c, and a lens array h is arranged between the reading line L and the image sensor chip g. To be done.
This lens array h converts the image on the reading line L into
This is for focusing on 1728 light receiving elements arranged on the plurality of image sensor chips g in an upright size.

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 a region of the entire length of the reading line L having a length corresponding to the width of the document, a plurality of LED chips j are mounted on the substrate k at equal intervals and are preferably arranged.

[0006]

By the way, the conventional contact type image sensor a having the above-mentioned structure has various problems as described below, particularly in the structure for illuminating the original.

First, the LED chip j which is a point light source.
16 are discretely arranged, the brightness at a predetermined distance from the light source periodically changes in intensity in the longitudinal direction of the illumination area, so that the output of the light receiving element is in the longitudinal direction of the reading line L. Not constant. That is, for example, even if a document having the same lightness is read along the reading line L, the output of the image sensor will have a periodic strength change in the longitudinal direction of the line L. This leads to deterioration of the reading quality, and if it is attempted to compensate for such deterioration of the reading quality,
A complicated correction circuit is required, which leads to an increase in cost of this contact image sensor.

Secondly, since a plurality of LED chips j are used as a light source, the reading quality is deteriorated due to the variation of the luminous intensity among the LED chips j. When reading a black-and-white image, such a variation in luminous intensity of each LED chip does not pose a problem so much, but when a contact image sensor is configured to read a color image, the read image quality is significantly deteriorated. Connect When an image sensor for reading a color image is configured by using a common reading element, light sources of three colors R, G, and B are arranged, and the image of each color is read line by line while switching the light emission color of the light source. However, as described above, the LED
When the luminosity of the chip varies, the color tone varies in the width direction of the image when the color image is reproduced by synthesizing the image data of each color. Such variations in color tone are visually emphasized more than expected, so that the quality of the reproduced color image is significantly deteriorated. This kind of color tone correction must be performed through complicated adjustments while precisely measuring the light intensity and color variation of each LED chip, and it is extremely resistant to low-cost mass production of this type of contact image sensor. is not.

Thirdly, in the case of constructing one image sensor, a plurality of LED chips j are required as a light source for illumination, which increases the manufacturing cost accordingly. In particular, in order to minimize the change in illumination brightness on the document reading surface c as shown in FIG. 16, it is necessary to set the distance from the document reading surface to the LED chip relatively long. However, in that case, only a small amount of light emitted from the light source can be substantially used as illumination light,
A lot of light is wasted. Therefore, the illumination energy efficiency is extremely poor.

The present invention has been devised under such circumstances, and in the case where a mechanism for illuminating a linear area is constructed by solving each of the problems of the conventional example as described above. It is an object of the present invention to eliminate the variation in brightness over the entire length of the illumination area as much as possible by a simple configuration, reduce the number of light sources to reduce the cost of the illumination device, and significantly improve the efficiency of illumination energy.

[0011]

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

According to the first aspect of the present invention, there is provided a light guide member for use in a linear light source device. This light guide member basically has a first side surface on one side in the thickness direction of a long transparent member as a light emitting surface, and a second side surface opposed to the light emitting surface in the thickness direction is provided at an intermediate portion in the longitudinal direction. A light incident portion is formed, and a cavity is formed in a portion of the transparent member corresponding to the light incident portion, and the light incident on the transparent member from the light incident portion is the cavity portion. It is characterized in that it is configured so as to be reflected by the boundary surface of (1) and travel in the transparent member toward the end thereof.

When the surface of the transparent member is a smooth mirror-finished surface, the light incident on the surface from the inside is a critical incident angle defined by the refractive index of the transparent member (the incident angle is relative to the surface normal). When the incident angle is larger than the angle, the light is totally reflected on the surface and returns to the inside of the transparent member, and when the incident angle is smaller than the critical incident angle, the light penetrates the surface and is emitted to the outside. In the light guide member having the above configuration, the light introduced into the transparent member from the light incident portion set at the longitudinally intermediate portion of the second side surface is reflected by the boundary surface of the cavity portion to change the direction. It is changed and advances in the longitudinal direction of the transparent member while reflecting on the first side surface and the second side surface.

More specifically, in the light guide member having the above structure, a boundary surface on the second side surface side is formed in the cavity formed in the transparent member. The light that has entered the transparent member from the light incident portion is reflected at the boundary surface without going out of the transparent member, and travels in the longitudinal direction of the transparent member. Then, while advancing in the longitudinal direction of the transparent member in this manner, this light is irradiated to the outside from the light emitting surface when the incident angle on the light emitting surface of the first side surface is smaller than the critical incident angle. It In this way, for example, when a light source device is formed using the light guide member having the above-described configuration, one light incident portion is provided at the intermediate portion in the longitudinal direction of the light guide member, and light from the light source is introduced. Thereby, light can be evenly emitted from the entire area of the light emitting surface formed linearly in the longitudinal direction on the first side surface of the light guide member.

In a preferred embodiment, the hollow portion has an opening on the second side surface of the transparent member, has an inner portion wider than the width of the opening, and has a widthwise direction of the transparent member. Although it is formed by a groove extending in the direction of the arrow, it may be in the form of a hole having no groove and penetrating in the short direction of the transparent member.

In a preferred embodiment, among the boundary surfaces of the cavity of the transparent member, at least the boundary surface on the second side surface side includes an inclined total reflection surface.

With this structure, the light incident from the light incident surface in the thickness direction of the transparent member can be changed in direction by total reflection and can be made to travel in the longitudinal direction of the transparent member.

In a preferred embodiment, among the boundary surfaces of the cavity, the boundary surface on the side of the first side surface includes a diffuse reflection surface.

With this configuration, when the light traveling in the transparent member reaches the boundary surface on the first side surface side of the boundary surfaces of the cavity, the light is diffused in a non-directional manner. The amount of light emitted from the light emitting surface at the longitudinal position corresponding to the light incident portion of the light guide member can be conveniently ensured.

In a preferred embodiment, the total reflection surface of the cavity is formed by forming a metal layer on the mirror-finished inner surface of the cavity. Further, the irregular reflection surface to be formed on the boundary on the first side surface side of the boundary surface of the cavity is formed by applying light reflecting coating to the inner surface of the cavity.

In another preferred embodiment,
The irregular reflection surface to be formed on the boundary on the first side surface side of the boundary surface of the cavity is formed by forming irregularities on the inner surface of the cavity.

In the above description, the total reflection surface and / or the irregular reflection surface formed on the boundary surface of the cavity is formed on the inner surface itself of the cavity, but the light reflecting member is fitted in the cavity. Mounted on the surface of this light reflecting member and / or
Alternatively, by forming the irregular reflection surface, it is possible to expect substantially the same action as that of the total reflection surface and / or the irregular reflection surface. In this case, a total reflection surface is formed by providing, for example, a metal layer on the surface of the light reflecting member, and a diffuse reflection surface is formed by applying light reflecting coating or forming fine irregularities. In this case, it is preferable that the inner surface of the hollow portion into which the light reflecting member is fitted and mounted is a smooth mirror-finished surface.

In a preferred embodiment, the light emitting surface which is the first side surface of the light guide member is a mirror-finished flat surface.

By doing so, it is possible to prevent the light emission efficiency from decreasing due to diffused reflection, and to improve the efficiency of the light guide member as a whole.

Further, in a preferred embodiment, a mirror finish area and a diffuse reflection area are provided in a mixed manner on the second side surface where the light incident portion is formed.

Light incident on the boundary surface of the mirror-finished region from the inside of the transparent member at an angle larger than the critical incident angle of total reflection is:
Totally reflects. On the other hand, the light incident on the boundary surface of the irregular reflection region from the inside of the transparent member is irregularly reflected in no direction and returns to the inside of the transparent member. Then, a part of the light diffusely reflected in this way reaches the first side surface, that is, the light emitting surface at an incident angle equal to or less than the critical incident angle, and is irradiated to the outside. Therefore, the amount of light emitted from the light emitting surface can be adjusted by adjusting the area of the irregular reflection region.

In a preferred embodiment, the area ratio of the irregular reflection region to the mirror-finished region on the second side surface on which the light incident portion is formed is increased as the distance from the light incident portion increases.

The amount of light that travels inside the light guide member in the longitudinal direction to reach the light guide member decreases toward the end of the light guide member, that is, as the distance from the light incident portion increases.
In other words, the light is stronger as it is closer to the light incident portion, but the light is weaker as it is farther from it. In the above-described embodiment, the proportion of the irregular reflection area formed on the second side surface is reduced at a position close to the light incident portion, while the proportion of the irregular reflection area is increased as the distance from the light incident portion increases, so that The amount of light emitted from the light emitting surface can be averaged in the longitudinal direction of the light guide member by compensating for the difference in the amount of light in the light guide member depending on the distance.

The irregular reflection area can be formed by applying a coating to a selected area on the second side surface, or can be formed by forming unevenness on the selected area on the second side surface. In the case of applying the coating to form the irregular reflection area, it is desirable to use a white coating from the viewpoint of reflection efficiency. When the diffuse reflection area is formed by applying a coating, it is desirable to form a rough surface on the second side surface in advance and apply the coating on the rough surface in order to improve the adhesion of the coating. Further, when a diffused reflection surface is formed by forming irregularities, a glossy metal such as Al, Cr, or Ag is vapor-deposited from the mirror finish area to the diffused reflection area to prevent unnecessary light leakage from the diffused reflection area. The efficiency can be improved.

Furthermore, in a preferred embodiment, both ends of the transparent member are total reflection surfaces. The formation of the total reflection surface is performed, for example, by forming a metal layer by vapor deposition.

As described above, in the light guide member according to the present invention, the light introduced into the transparent member from the light incident portion provided on the second side surface of the intermediate portion in the longitudinal direction is directed toward the end portion in the longitudinal direction. The light is made to proceed so that the light is evenly emitted from the light emitting surface of the first side surface. A part of the light traveling toward the end in the longitudinal direction reaches the end surface of the transparent member, but if this end surface is a mirror-finished surface or a smooth boundary surface close to this, it penetrates this boundary surface. Irradiated to the outside in vain. In this embodiment, by making the end of the transparent member a total reflection surface, the light that has reached the end surface of the transparent member is returned to the inside of the transparent member as described above to improve efficiency.

[0032] In a preferred embodiment, the light incident portion is formed at one location in the longitudinal center portion of the second side surface.

When a monochromatic linear light source device is constructed by using this light guide member, for example, 1 is provided adjacent to the light incident portion.
It is only necessary to arrange the LEDs. Therefore,
As seen in the light source of the conventional contact image sensor,
Compared with the arrangement of a plurality of light sources, cost reduction due to the reduction in the number of LEDs and the prevention of variations in illuminance with respect to the linear illumination area can be effectively realized. The LED emission color is not limited, and a white LED may be adopted in some cases.

In another embodiment, the light incident portion is formed at a plurality of positions in the longitudinal direction on the second side surface.

By doing so, it is possible to realize a light source device capable of enlarging the total extension of the linear light exit surface and illuminating the linear illumination area by averaging the linear illumination area. .

In a preferred embodiment, the second side surface is inclined or convexly curved so that the distance from the first side surface decreases as the distance from the light incident portion increases.

That is, in this embodiment, the thickness of the light guide member is made thinner toward the end portion from the position where the light incident portion is provided. This also compensates for the fact that the amount of light in the transparent member decreases as the distance from the light incident part where the light source is arranged increases, that is, the density of the light trapped in the transparent member is averaged. The amount of light emitted from the light emitting surface can be averaged in the longitudinal direction of the light guide member.

In a preferred embodiment, the width dimension of the first side surface of the transparent member is shorter than the width dimension of the second side surface.

As a result, a sufficient amount of light can be applied in the longitudinal direction to the linear irradiation area having a limited width dimension.

According to a second aspect of the present invention, there is provided a linear light source device using the light guide member according to the first aspect of the present invention. This linear light source device is characterized in that any one of the above-described light guide members is used, and a light source is arranged adjacent to the light incident portion of the light guide member. Such a light source can be configured, for example, by disposing the LED mounted on the substrate toward the light incident portion of the light guide member.

The advantages of this linear light source device are apparent from the above description of the light guide member used therefor. In addition to this, for example, the light source is arranged adjacent to the end of the light guide member. Compared with the above, the total length of the linear light source device is shortened, and it is possible to reduce the size of the device using the light source device in the longitudinal direction.

In a preferred embodiment, as the light source, L of three colors of red (R), green (G) and blue (B) is used.
The EDs are arranged adjacent to the light incident portion of the light guide member in the width direction thereof.

That is, the light source device according to this embodiment can be suitably used as a light source device for a contact image sensor configured to read a color image. For each color, in addition to the uneven distribution of illumination intensity in the longitudinal direction of the reading area, since the LEDs of each color are arranged in the width direction of the light guide member, the position of the light source of each color with respect to the linear illumination area is in the longitudinal direction. It becomes the same, and uneven distribution of the illumination intensity among the colors can be avoided.

According to the third aspect of the present invention, there is provided an image reading apparatus using the linear light source device according to the second aspect of the present invention. This image reading device irradiates a document, which is contacted and conveyed on an image reading surface formed on one surface of a casing, with light from a light source device provided in the casing, and reads the document set on the image reading surface. An image reading device in which reflected light from a document on a line is received by a plurality of light receiving elements arranged in the casing in the reading line direction, wherein the light source device is a light source device according to the second aspect. The linear light source device is used, and the light emitted from the light emitting surface illuminates the original on the reading line.

The advantages of such an image reading device will be apparent from the description of the light guide member provided by the first aspect of the present invention and the linear light source device provided by the second aspect.

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

[0047]

1 is a front view of a first embodiment of a light guide member 10 according to the present invention or a linear light source device 35 using the same, FIG. 2 is a bottom view, and FIG. 3 is a main part. Exploded view of
4 is an enlarged side view of the central portion of the light guide member 10 in the longitudinal direction, FIG. 5 is an enlarged side view of the end portion of the light guide member 10 in the longitudinal direction, and FIG. 6 is a sectional view taken along line VI-VI of FIG. , Fig. 7 of Fig. 4
FIG. 7 is a sectional view taken along line VII-VII.

The light guide member 10 according to the present invention has, as its main part, a transparent member 11 obtained by molding an acrylic transparent resin such as PMMA. As shown in FIGS. 1 and 2, the transparent member 11 is a long member having a predetermined longitudinal dimension, and has a first side face 11A in the vertical thickness direction and a first side face 11A facing the first side face 11A. Second side surface 11B and third and fourth side surfaces 1 in the lateral direction
It has 1C and 11D, and both longitudinal end faces 11E and 11F.

The first side surface 11A is preferably a mirror-finished flat surface, which will be described later.
The side surface 11A functions as the light emitting surface 12. Second above
The side surface 11B is a flat inclined surface in which the distance between the side surface 11B and the first side surface 11A gradually decreases from the central portion in the longitudinal direction toward the end portion. , And the irregular reflection area 14 are mixed. Further, in this embodiment, the central portion in the longitudinal direction of the second side surface 11B is set as the light incident portion 15. Further, as shown in FIGS. 6 and 7, the third and fourth side faces 11C, 1 of the transparent member 11 are formed.
1D is an inclined flat surface in which the distance between them decreases as it goes toward the first side surface 11A, and is preferably a mirror-finished smooth surface. As a result, the first side surface 11A, which is the light emitting surface 12, has a narrow constant width in the longitudinal direction, while the width of the second side surface 11B is wider than the width of the first side surface 11A, and the light incident portion 15 sets the width. The center part in the longitudinal direction has the maximum width.

The mirror finishing area 13 is formed on the second side surface 11B.
As a method for mixing the irregular reflection area 14 and the irregular reflection area 14, for example, the entire second side surface 11B is made a mirror-finished surface, and a selected area of the second side surface 11B is painted in white, for example. In the illustrated embodiment, as shown in FIG.
A plurality of strip-shaped white coatings 14A extending in the left-right width direction are applied to the side surface 11B at a plurality of positions in the longitudinal direction of the transparent member 11, and the inner surfaces of these white coatings 14A function as the irregular reflection regions 14. In addition, paint 14A like this
When the coating 14A is applied with the selected surface to be coated as a rough surface, the coating 14 for the second side surface 11B is applied.
It is desirable because the adhesive force of A is improved. Further, in the embodiment shown in the drawings, the strip-shaped white coating 14A is configured such that the coating width in the transparent member longitudinal direction becomes wider toward the end of the transparent member 11, and the second side surface 11B has a mirror finish. The area ratio of the irregular reflection area 14 to the area 13 is set to increase toward the end of the transparent member 11. In addition, in order to form the irregular reflection region 14,
In addition to the white coating as described above, as shown in FIG. 14, fine irregularities 14B may be provided at the stage of molding the transparent member 11 or by processing. Also,
When the diffused reflection area is formed by painting, as in the embodiment shown in the figure, in addition to band-like painting, dot-like painting is performed, and the density of the dots is increased toward the end of the transparent member 11. May be. In addition, the irregular reflection area 14
And in addition to this, Al from the upper layer of the mirror-finished area 13
The second side surface 11B by vapor-depositing a bright metal such as Cr, Ag, or the like.
You may make it prevent the leak of the light from.

Both end faces 11 in the longitudinal direction of the transparent member 11
As shown in FIG. 4, E and 11F are preferably made into total reflection surfaces by, for example, vapor-depositing the metal layer 16.

As described above, the transparent member 11
The third and fourth side faces 11C, 11 in the left-right width direction at
It is desirable that D is a mirror-finished flat surface, but in addition to this, total reflection is performed by evaporating a metal layer (not shown) on the entire surfaces of these third and fourth side surfaces. It may be a surface.

In the present invention, the cavity 18 is formed in the transparent member 11 at a portion corresponding to the light incident portion 15.
The boundary surface 181 of the cavity 18 reflects the light that has entered the transparent member 11 from the light entrance portion 15 and travels to the end of the transparent member 11 in the longitudinal direction. As well shown in FIG. 4, in the present embodiment, the cavity portion 18 has an opening 18 in the second side surface 11B.
3 is formed, communicates with the opening 183, has a substantially rhombic shape wider than the opening width of the opening 183, and is formed in a groove shape extending in the lateral direction of the transparent member 11.

At least the inclined boundary surface 181 on the second side surface 11B side (light incident portion 15 side) of the boundary surface of the cavity 18 is a total reflection surface 18A for totally reflecting the light reaching from the inside of the transparent member 11. It is said that In addition, the cavity portion 18
The first side surface 11A side (light emission surface 12 side) in the boundary surface of
The boundary surface 182 of is a total reflection surface or a diffuse reflection surface.
As described above, in order to form a total reflection surface or a diffuse reflection surface on the boundary surface of the cavity portion 18, as described later, the inner surface of the cavity portion 18 itself is a total reflection surface or a diffuse reflection surface. In addition to the surface, it can be realized by forming a total reflection surface or a diffuse reflection surface on the surface of the light reflection member 19 fitted in the cavity portion 18 as described below.

FIG. 8 shows one form of the light reflecting member 19. As shown in the figure, the light reflecting member 19 has a substantially diamond-shaped outer shape in correspondence with the substantially diamond-shaped cavity portion 18 formed in the transparent member 11, and a space on the transparent member 11 side. A protrusion 193 is integrally formed in correspondence with the opening 183 of the cavity 18, and is formed by molding an acrylic resin, for example, like the transparent member 11. The light reflecting member 19 is fitted into the hollow portion 18 formed in a groove by sliding it from the side.

The inclined outer surface 191 of the light reflecting member 19 on the side of the second side surface 11B has, for example, Al or C.
The total reflection surface 19A is formed by vapor-depositing a glossy metal layer such as r or Ag. A total reflection surface 19A is also formed on the outer surface 192 of the light reflection member 19 on the first side surface 11A side.

FIG. 9 shows another form of the light reflecting member 19. The light reflecting member 19 of this form is similar to that of FIG. 8 in that the total reflection surface 19A is formed on the inclined outer surface 191 on the second side surface 11B side, but the first side surface 11A.
The outer surface 192 on the side is provided with a diffuse reflection surface by applying, for example, white coating 19B.

FIG. 10 shows still another form of the light reflecting member 19. In the light reflecting member 19 of this form,
The total reflection surface 19A is formed on the inclined outer surface 191 on the second side surface 11B side as in the case shown in FIGS. 8 and 9, but the outer surface 192 on the first side surface 11A side has fine unevenness 19B. To give a diffuse reflection surface.

As described above, when the light reflecting member 19 is fitted in the cavity 18 of the transparent member 11, the inner surface of the cavity 18 itself is a mirror-finished smooth surface. Is desirable.

11 to 13 are explanatory views of the case where a total reflection surface or an irregular reflection surface is formed on the inner surface of the cavity 18 itself of the transparent member 11.

In the embodiment shown in FIG. 11, a glossy metal such as Al, Cr, or Ag is vapor-deposited on the inclined inner surface 181 on the second side surface 11B side of the cavity portion 18 to the inner surface on the first side surface A side. Then, the total reflection surface 18A is formed.

In the embodiment shown in FIG. 12, a total reflection surface 18 similar to the above is formed on the inclined inner surface 181 on the second side surface 11B side.
While forming A, the inner surface 182 on the first side surface 11A side is provided with a white coating 18B to form an irregular reflection surface.

In the embodiment shown in FIG. 13, a total reflection surface 18A similar to the above is formed on the inclined inner surface 181 of the cavity portion 18 on the second side surface 11B side, while the first side surface 11 is formed.
On the A-side inner surface 182, a diffused reflection surface is formed by forming a fine uneven surface 18C.

The light source 30 is arranged so as to be adjacent to the light incident portion 15 in the light guide member 10 configured as described above, but in the embodiment shown in the drawings, it is well shown in FIGS. The opening 1 of the cavity 18
LEs of red (R) emission on both sides of 83
Three LEDs, D30R, green (G) emitting LED 30G, and blue (B) emitting LED 30B, are included in the light guide member 1.
They are arranged in the lateral direction of 0. in this way,
By the light guide member 10 and the LEDs 30R, 30G, and 30B arranged adjacent to the light incident portion 15, from the light emission surface 12 formed by the entire first side surface 11A of the light guide member 10 having a constant longitudinal dimension. Linear light source device 35 for emitting light
Is configured. The operation of the linear light source device 35 will be specifically described below.

As shown in FIG. 4, the LED 30 which is a light source.
The light that has entered the transparent member 11 from the R, 30G, and 30B through the second side surface 11B is the second light of the cavity portion 18.
The light is totally reflected by the total reflection surface (18A or 19A) formed on the side surface B-side inclined interface (181 or 191), and is allowed to travel in the transparent member 11 toward its end portion.
Then, when the light having a larger angle than the critical angle for total reflection is incident on the mirror-finished region 13 on the first side surface 11A and the second side surface B of the transparent member 11, the light is totally reflected and further proceeds toward the end portion.

In the light guide member 10 according to the above embodiment, the diffused reflection area 14 formed of, for example, the white coating 14A or the fine irregularities 14B is provided on the second side surface 11B as described above. The light reaching the irregular reflection area 14 from the inside is irregularly reflected toward the inside of the transparent member 11 in a non-directional manner. Of the light diffusely reflected in this way, the light that reaches the first side surface 11A at an angle smaller than the critical angle for total reflection is transmitted through the first side surface 11A and is emitted to the outside as illumination light.

LEDs 30R, 30G, 3 which are the above light sources
The closer to the light incident portion 15 where 0B is arranged, the transparent member 1
Although the light traveling in 1 is strong, in the above embodiment,
Since the area ratio of the irregular reflection region 14 is made smaller as it is closer to the light incident portion 15, the amount of light emitted through the first side surface 11A is suppressed. On the other hand, as the distance from the light incident portion 15 increases, the light traveling through the transparent member 11 weakens,
In the above-described embodiment, since the area ratio of the irregular reflection region 14 is increased as the distance from the light incident portion 15 increases, the weakening of light in the transparent member 11 is compensated and the first side surface 11A is formed in the end region. The amount of light transmitted and emitted is secured. In this way, the amount of light emitted from the first side surface 11A of the light guide member 10 to illuminate the linear illumination area can be made uniform in the longitudinal direction of the light guide member 10.

Further, in the embodiment shown in the drawings, the second side surface 11B of the light guide member 10 is inclined toward the first side surface 11A toward the end, and the vertical thickness dimension of the light guide member 10 is equal to the end portion. The fact that the light is reduced toward the end also compensates for the weakening of the light traveling in the transparent member 11 toward the end, and contributes to the emission of light of uniform intensity over the entire length in the longitudinal direction. ing.

Further, in the present embodiment, the transparent member 1
Total reflection surface 1 by metal deposition on both end surfaces 11E and 11F of 1
Since 6 is provided, it is possible to avoid wasteful emission of light that has traveled through the transparent member 11 and reached the end.

Further, in the present embodiment, as described above, the lateral width of the light guide member 10 is reduced toward the first side surface 11A, so that the widthwise dimension of the first side surface 11A is suppressed within a certain range. As a linear light source, while being able to efficiently irradiate a limited area in the width direction, the three LEDs 30R, as described above, on the second side surface 11B,
This is suitable for arranging 30G and 30B at the same position in the longitudinal direction of the light guide member 10.

As described above, the diffuse reflection is performed in the irregular reflection area 14 of the second side face 11B, or the both end faces 1
The light that has reached the first side surface side interface 182 of the cavity portion 18 due to reflection from the total reflection surface 16 of 1E and 11F,
Total reflection surface (18A or 19A) or irregular reflection surface (1
8B, 18C or 19B, 19C), and a part of the first side surface 11 is below the critical angle for total reflection.
After reaching A, the light is emitted from the light emitting surface 12 to the outside, thereby compensating for the decrease in the amount of emitted light at the central portion in the longitudinal direction.

As described above, the LEDs 30R, 3 of each color are
The lights emitted from 0G and 30B are respectively guided by the light guide member 10
The light is uniformly emitted from the light emitting surface 12 in the entire length region of the first side surface 11A. LEDs 30R, 30G, 3 of each color
By adjusting the output of 0B, full-color coloring is possible. In addition, as will be described later, each color LED 30
By sequentially switching R, 30G, and 30B to emit light, it is possible to function as a light source device of a contact type color image sensor in which a light receiving element is commonly used.

FIG. 15 shows a second embodiment of the light guide member 10 according to the present invention or a light source device 35 using the same. The difference from the first embodiment of this embodiment is that the second side surface 11B is a flat inclined surface in the first embodiment, but in the second embodiment, the second side surface 11B is loose. That is, it has a convex curved inclined surface. In this embodiment as well, similar effects can be expected, but by making the second side surface 11B convexly curved, the density of the luminous flux decreases as it goes toward the end portion of the light guide member 10. The tendency can be eased.

FIG. 16 shows a third embodiment of the light guide member 10 according to the present invention or a light source device 35 using the same. The light guide member 10 or the linear light source device 35 according to this embodiment has the light guide member 10 or the linear light source device 35 shown in FIGS. 1 to 7 as one unit, and this is made continuous for two units in the longitudinal direction. It is a thing. In the light guide member 10 or the linear light source device 35 according to the present invention, the light incident portion 1 is basically provided on the second side surface 11B of the transparent member 11 in the longitudinal middle portion.
Since 5 is provided, such a linear illumination range can be extended in the longitudinal direction.

17 and 18 show a contact type color image sensor 40 using the light guide member 10 and the linear light source device 35 shown in FIGS. The image sensor 40 has an image reading surface 42 made of a transparent glass plate on the upper surface of a casing 41, and an image of a document D conveyed while being backed up by a platen 43 so as to be in close contact with the image reading surface 42,
It is configured to read every line.

A substrate 44 is attached to the lower surface of the casing 41, and a plurality of image sensor chips 45 having a predetermined number of light receiving elements are attached to the substrate 44 in a row. For example, a document of A4 width is 8 dots /
In order to read with a reading density of mm, 1728 of the 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 45. Therefore, in this case, 18
The individual image sensor chips 45 are arranged on the substrate.

The plurality of image sensor chips 45 are arranged vertically below the reading line L set on the image reading surface 42, and a lens array is arranged between the reading line L and the image sensor chip 45. Four
6 is arranged. The lens array 46 focuses the image on the reading line L on the 1728 light receiving elements arranged on the plurality of image sensor chips 45 in an erecting equal size.

The image reading surface 4 in the casing 41
The linear light source device 35 of the present invention having the configuration shown in FIGS. 1 to 7 is arranged in the space below the lens array 46 on the side of the lens array 46. In this case, the center line L _{1 in} the left-right width direction of the light guide member 10 is arranged so as to face the reading line L of the image reading surface 42.
Then, the LEDs 30R, 30G, 30B for emitting R, G, B colors are mounted on the substrate 47 so as to be adjacent to the light incident portion 15 on the second side surface 11B of the light guide member 10.
On both sides of the cavity opening 183 of the light guide member 10,
The light guide members 10 are arranged in the lateral direction.

The light emitted from the first side surface 11A of the light guide member 10 efficiently illuminates the document on the reading line L. Then, the image data for each color R, G, B of the image of the document on the reading line L is switched by the image sensor chip 45 while switching the LEDs 30R, 30G, 30B for each color while feeding the document D by a predetermined pitch. Read sequentially.

In the contact type color image sensor 40, the linear light source device 35 includes the LEDs 30R, 30G,
Since the light emitted from 30B is evenly spread and radiated to the illumination region of a predetermined length, that is, the two LEDs of each color are close to the central portion of the linear light source governor 35 in the longitudinal direction of the light guide member. Since the LEDs are provided separately, the color tone of the read image caused by uneven distribution of the amount of light in the reading width direction and subtle differences in the colored light of each LED, etc. It is possible to effectively eliminate the factors such as the deviation of the image reading quality that are deteriorated. Also,
The LEDs 30R, 30G, and 30B of the respective colors are connected to the light guide member 10
Since they are arranged at the same position in the longitudinal direction, the deviation of the color tone of the read image, which is supposed when the LEDs of each color are arranged in the reading width direction, can be effectively avoided. Further, since the light traveling in the light guide member 10 is intensively emitted from the first side surface 11A of the light guide member 10, the illumination efficiency is very good, and the LED 30 having only two of each color is used.
Despite using R, 30G, and 30B, it is possible to secure a sufficient amount of illumination light. Further, LEDs 30R and 30 which are light sources are provided at intermediate portions in the longitudinal direction of the light guide member 10.
Since G and 30B are arranged, for example, the light guide member 1
Compared with arranging an LED or the like as a light source at the end portion of 0, the size of the casing 41 in the longitudinal direction is saved, and miniaturization of this type of contact color image sensor 40 is promoted.

Of course, the scope of the present invention is not limited to the above embodiments. In particular, the light guide member or the linear light source device using the light guide member is used as a light source of a contact type color image sensor as described above, and is also used as various illumination light sources such as interior lighting, vehicle interior lighting, and decorative lighting. Is possible. In this case, the optimum size and light source of the light guide member are selected.

Further, in the embodiment, the transparent member 11
The cavity portion 18 to be formed in the second side surface 11B is formed in the shape of a groove, and R, G, and
B Two LEDs 30R, 30G, 30B for each color are arranged, but if the shape of the cavity 18 is, for example, a closed rhombus shape in a front view without a groove opening to the second side surface 11B, one for each color , A total of 3 LEDs 30R, 3
It is sufficient if 0G and 30B are arranged in the lateral direction of the light guide member 10.

Further, in the embodiment shown in the figure, the contact type color image sensor is configured for the illumination light source, but it goes without saying that the type of the light source and the emission color are not limited at all.

[Brief description of drawings]

FIG. 1 is a front view of a first embodiment of a light guide member or a linear light source device using the same according to the present invention.

FIG. 2 is a bottom view of the light guide member or the linear light source device shown in FIG.

FIG. 3 is an exploded view of a main part of the light guide member or the linear light source device shown in FIG.

4 is an enlarged front view of a central portion in the longitudinal direction of the light guide member or the linear light source device shown in FIG.

5 is an enlarged front view of an end portion of the light guide member or the linear light source device shown in FIG.

6 is a sectional view taken along line VI-VI of FIG.

7 is a sectional view taken along line VII-VII of FIG.

FIG. 8 is an explanatory diagram of one form of a light reflecting member to be fitted and mounted in the cavity of the light guide member.

FIG. 9 is an explanatory diagram of another mode of the light reflecting member.

FIG. 10 is an explanatory diagram of still another mode of the light reflecting member.

FIG. 11 is an explanatory diagram of one form of the cavity portion of the light guide member.

FIG. 12 is an explanatory view of another form of the cavity portion of the light guide member.

FIG. 13 is an explanatory view of still another form of the cavity of the light guide member.

FIG. 14 is an explanatory diagram of a modification of the light guide member or the linear light source device according to the first embodiment.

FIG. 15 is a front view of a second embodiment of a light guide member or a linear light source device according to the present invention.

FIG. 16 is a front view of a third embodiment of a light guide member or a linear light source device according to the present invention.

FIG. 17 is a central cross-sectional view of a contact type color image sensor using the light guide member or the linear light source device according to the first embodiment of the present invention shown in FIGS. 1 to 7.

18 is a sectional view taken along line XVIII-XVIII in FIG.

FIG. 19 is a cross-sectional view showing a general configuration of a conventional contact image sensor.

20 is a cross-sectional view taken along the line XX-XX in FIG.

[Explanation of symbols]

10 Light guide member 11 Transparent member 11A First side 11B Second side 12 Light exit surface 13 Mirror finish area 14 Diffuse reflection area 15 Light incident part 18 cavity 18A total reflection surface 18B, 18C irregular reflection surface 19 Light reflection member 19A Total reflection surface 19B, 19C Diffuse reflection surface 30R red LED 30G green LED 30B blue LED 35 Linear light source device 40 Contact type color image sensor 41 casing 42 Image reading surface L reading line D manuscript

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI G03B 27/54 H04N 1/028 Z H04N 1/028 G02B 1/10 Z (56) Reference JP-A-7-203333 (JP, A) Actual Kaihei 1-77065 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04N 1/04 101 G02B 1/10 G02B 6/00 301 G02B 6/00 331 G03B 27 / 50 G03B 27/54 H04N 1/028

Claims (26)

(57) [Claims] 1. A first member on one side in the thickness direction of a long transparent member.
A side surface is used as a light emitting surface, and a light incident portion is formed in a longitudinal direction intermediate portion of the second side surface facing the light emitting surface in the thickness direction. The light incident portion of the transparent member corresponds to the light incident portion. A cavity is formed, and the light incident on the transparent member from the light incident part is reflected at the boundary surface of the cavity and travels in the transparent member toward the end thereof. The light guide member characterized by the above. 2. The cavity has an opening on the second side surface of the transparent member, an inner part wider than the width of the opening, and a groove extending in the lateral direction of the transparent member. The light guide member according to claim 1, which is formed. 3. The light guide member according to claim 2, wherein at least the boundary surface on the second side surface side of the boundary surface of the cavity portion includes an inclined total reflection surface. 4. The irregular reflection surface is included in the boundary surface on the side of the first side surface among the boundary surfaces of the cavity.
The light guide member according to. 5. The light guide member according to claim 3, wherein the total reflection surface of the cavity is formed by forming a metal layer on the inner surface of the cavity that is mirror-finished. 6. The light guide member according to claim 4, wherein the irregular reflection surface of the cavity is formed by applying a light reflective coating to the inner surface of the cavity. 7. The light guide member according to claim 4 or 5, wherein the irregular reflection surface of the cavity is formed by forming irregularities on the inner surface of the cavity. 8. The total reflection surface at the boundary surface of the cavity is formed by forming a metal layer on the surface of the light reflecting member fitted in the cavity. Light guide member. 9. The irregular reflection surface at the boundary surface of the cavity is formed by providing light reflecting coating or unevenness on the surface of the light reflecting member fitted in the cavity.
The light guide member according to claim 4. 10. The light guide member according to claim 1, wherein the light emitting surface is a mirror-finished flat surface. 11. The light guide member according to claim 10, wherein a mirror finish area and a diffuse reflection area are mixed on the second side surface on which the light incident portion is formed. 12. The light guide according to claim 11, wherein, on the second side surface on which the light incident portion is formed, the area ratio of the irregular reflection area to the mirror-finished area is increased as the distance from the light incident portion increases. Element. 13. The light guide member according to claim 11, wherein the irregular reflection region is formed by applying a coating to a selected region of the second side surface. 14. The light guide member according to claim 11, wherein the irregular reflection region is formed by forming unevenness in a selected region of the second side surface. 15. A glossy material such as Al, Cr, or Ag is vapor-deposited on the mirror-finished area and the irregular reflection area.
The light guide member according to claim 14. 16. The light guide member according to claim 1, wherein both ends of the transparent member are total reflection surfaces. 17. The light guide member according to claim 1, wherein the light incident portion is formed at one location at a central portion in the longitudinal direction of the second side surface. 18. The light guide member according to claim 1, wherein the light incident portion is formed at a plurality of positions on the second side surface. 19. The method according to claim 1, wherein the second side surface is inclined or convexly curved so that the distance between the second side surface and the first side surface decreases as the distance from the light incident portion increases. The light guide member according to claim 2. 20. The light guide member according to claim 1, wherein a width dimension of the first side surface of the transparent member is shorter than a width dimension of the second side surface. 21. A linear light source, wherein the light guide member according to any one of claims 1 to 20 is used, and a light source is arranged adjacent to a light incident portion of the light guide member. apparatus. 22. The light source is an LED.
1. The linear light source device according to 1. 23. The linear light source device according to claim 22, wherein the LED emits white light. 24. The linear light source device according to claim 22, wherein LEDs of three colors of R, G, and B are arranged adjacent to a light incident portion of the light guide member in the width direction thereof. 25. Two sets of LEDs of three colors of R, G and B are arranged adjacent to a light incident part of the light guide member on both sides of an opening of a groove forming the cavity. Item 24. The linear light source device according to item 24. 26. A reading line set on the document reading surface by irradiating a document conveyed in contact with the document reading surface formed on one surface of the casing with light from a light source device provided in the casing. 3. An image reading device in which reflected light from a document in claim 2 is received by a plurality of light receiving elements arranged in the casing in the reading line direction, wherein the light source device is a light source device.
An image reading apparatus, characterized in that the linear light source device according to any one of claims 1 to 25 is used, and light emitted from a light emitting surface thereof illuminates a document on the reading line. .