JP3766422B2 - Linear light source device and image reading device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce costs of an illuminator and to improve illumination energy efficiency by eliminating dispersion of lightness over the full length of an illumination area as much as possible with simple configuration and decreasing the number of light sources when configuring a mechanism for illuminating the linear area. <P>SOLUTION: The illuminator is provided with a light transmission member 10 including a long transparent member 11 having a first lateral side 11A and a second lateral side 11B opposed in the direction of thickness, and light sources 30R, 30G, 30B. The first lateral side 11A is provided as a light emission plane and in the intermediate portion of the second lateral side 11B in its lengthwise direction, a light incidence part 15 is formed. Light incident from the light incidence part 15 is advanced inside the transparent member 11 toward both terminals in the lengthwise direction while being fully reflected and irregularly reflected on an outer surface of the transparent member 11, and is emitted from all or approximately all the area of the light emission plane. The width of the second lateral side 11B is made longer than the width of the first lateral side 11A, and the light sources 30R, 30G, 30B are opposed to the light incidence part 15 on the second lateral side 11B. <P>COPYRIGHT: (C)2004,JPO&amp;NCIPI

Description

  The present invention relates to a linear light source device and an image reading device using the same. For example, the linear light source device according to the present invention can be suitably used for an image reading apparatus configured to read a document conveyed while being in close contact with a reading surface for each line, that is, a document illumination of a contact image sensor.

  FIG. 15 shows a conventional general configuration of a contact image sensor. The image sensor a includes an original reading surface c made of a transparent glass plate on the upper surface of a casing b, and an image of the original e conveyed while being backed up by a platen d so as to be in close contact with the original reading surface c. It is configured to 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 each having a predetermined number of light receiving elements are attached to the substrate f in one row. For example, in order to read an A4 width original at a reading density of 8 dots / mm, 1728 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. Therefore, in this case, 18 image sensor chips g are mounted in a row on the substrate f.

  The image sensor chip g is arranged at a position 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. The lens array h is for focusing the image on the reading line L onto 1728 light receiving elements arranged on the plurality of image sensor chips g at an equal magnification.

  A light source for illuminating the original on the reading line L is provided in a space formed below the original reading surface c in the casing b. Conventionally, an LED chip j is often used as the light source, and a plurality of LED chips j are used to illuminate the entire length of the reading line L having a length corresponding to the width of the document. It arrange | positions by the favor mounted on the board | substrate k in the space | interval.

  The conventional contact image sensor a has the following various problems particularly in the configuration for illuminating the original.

  First, since the LED chips j as point light sources are discretely arranged, the brightness at a predetermined distance from the light source periodically changes in strength in the longitudinal direction of the illumination area as shown in FIG. For this reason, the output of the light receiving element is not constant in the longitudinal direction of the reading line L. That is, for example, even when an original having the same brightness is read along the reading line L, a periodic strength change occurs in the longitudinal direction of the line L in the output as the image sensor. This leads to deterioration in reading quality, and if it is intended to compensate for such deterioration in reading quality, a complicated correction circuit is required, leading to an increase in the cost of the contact image sensor.

Second, since a plurality of LED chips j are used as a light source, reading quality is deteriorated due to variations in luminous intensity for each LED chip j. In the case of reading a black and white image, such a variation in the luminous intensity of each LED chip j is not so much a problem. However, when a contact image sensor is configured to read a color image, the quality of the read image is significantly deteriorated. Leads to. When configuring a color image reading image sensor using a common reading element, arrange light sources of three colors, R, G, and B, and read each color image for each line while switching the emission color of the light source. However, when there is variation in the luminous intensity of the LED chip j as described above, variation in color tone occurs in the width direction of the image at the stage where the image data for each color is synthesized and the color image is reproduced. Such variations in color tone are more visually emphasized than expected, and the quality of the reproduced color image is significantly reduced. Such color tone correction must be carried out through complicated adjustments while accurately measuring the brightness and color variation of each LED chip j, and can endure low-cost mass production of this type of contact image sensor. It is not a thing.

  Thirdly, when one image sensor is configured, a plurality of LED chips j are required as the illumination light source, so that the manufacturing cost is increased 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 part of the light emitted from the light source can be used as illumination light, and much light is wasted. Therefore, the illumination energy efficiency is extremely poor.

JP-A-8-184825 JP-A-5-316296 JP-A-6-295002 Japanese Utility Model Publication No. 6-21940 Japanese Utility Model Publication No. 1-77065 JP-A-7-143289 Japanese Unexamined Patent Publication No. 63-182963

  The present invention has been conceived under such circumstances, and solves the problems of the prior art as described above, and constitutes a mechanism for illuminating a linear region. The problem is to reduce the variation in brightness over the entire length of the lighting device as much as possible with a simple configuration, to reduce the number of light sources, to reduce the cost of the lighting device, and to improve the illumination energy efficiency.

  In order to solve the above problems, the present invention takes the following technical means.

According to the first aspect of the present invention, a linear light source device is provided. The linear light source device includes a light guide member including a long transparent member having a first side surface and a second side surface facing in the thickness direction, and a light source, and the first side surface is is a light emitting surface, and with the longitudinally intermediate portion of the second side has a light incident portion is formed, the light source is closely worn on the light incident portion, light incident from the light incident portion Is configured to emit from the entire or almost entire area of the light emitting surface while proceeding toward the both ends in the longitudinal direction while totally reflecting and irregularly reflecting on the outer surface of the transparent member . A substantially V-shaped recessed portion having two inclined surfaces and a bottom surface connecting between the bottom end portions of these inclined surfaces is formed at a portion facing one side of the light incident portion, and the bottom surface Is a light diffusing surface or light reflecting surface. , The width of the second aspect is the above-described first aspect elongated than the width of said light source is characterized in that it is opposed to the light incident portion of the second side. For example, the LED may be attached to the light incident portion of the light guide member by bonding or the LED mounted on the substrate may be adjacent to the light incident portion of the light guide member. .

When the surface of the transparent member is a smooth mirror-finished surface, the light incident on the surface from the inside is from the critical incident angle defined by the refractive index of the transparent member (the incident angle is the angle relative to the normal of the surface) In the case of a large incident angle, the light is totally reflected on the surface and returns to the inside of the transparent member. In the light guide member having the above-described configuration, the light introduced into the transparent member from the light incident portion set at the intermediate portion in the longitudinal direction of the second side surface is reflected in the longitudinal direction of the transparent member while being reflected on the outer surface of the transparent member. proceed. In the process of proceeding in the longitudinal direction of the transparent member in this way, when the incident angle of the first side surface to the light emitting surface is smaller than the critical incident angle, the light is emitted from the light emitting surface to the outside. The For this reason, for example, by providing one light incident portion at the longitudinal intermediate portion of the light guide member and introducing light from a single light source into the light incident portion, the first side surface of the light guide member is provided. In this case, light can be evenly emitted from the entire light emitting surface formed linearly in the longitudinal direction. According to the present invention, compared to the arrangement of the light source adjacent to the end of the light guide member, the overall length of the linear light source device is shortened, and the downsizing of the device using the light source device in the longitudinal direction is reduced. Can be planned. The configuration of the recessed portion 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 is emitted to the outside as it is. That is, when the central portion in the longitudinal direction of the first side surface not forming the recessed portion is mirror-finished, the light incident angle to the first side surface near the light incident portion is smaller than the critical incident angle, and the inner side of the first side surface Most of the light that has arrived from the light exits as it is without being reflected at the boundary surface of the first side surface. In such a case, when viewed from the outside, a bright spot appears in the middle portion in the longitudinal direction of the light emitting surface of the light guide member, and as a linear light source device, uniform light emission from the light emitting surface is obstructed. . In the above configuration, by forming the V-shaped recessed portion, the incident angle of light from the inside of the transparent member with respect to the inclined surface is increased to promote total reflection of light, and the appearance of the bright spot as described above is effective. Can be avoided. In order to use the bottom of the recessed portion as a light reflecting surface, for example, a metal layer is vapor deposited. Thereby, coupled with the fact that the inclined surface of the recessed portion promotes total reflection of light, it is possible to effectively avoid the appearance of bright spots in the intermediate portion in the longitudinal direction of the light guide member due to direct transmission of light. Further, when the bottom surface of the recessed portion is an uneven light diffusing surface, light is emitted from the bottom surface in a diffusing manner, and light is transmitted through the inclined surface of the substantially V-shaped recessed portion inside the light guide member. It is possible to compensate for a decrease in the amount of light emitted from the central portion of the light guide member due to total reflection, and to ensure uniform light irradiation from the entire light exit surface of the light guide member.

  In the present invention, the width dimension of the first side surface of the transparent member is shorter than the width dimension of the second side surface. Thereby, it is possible to irradiate a sufficient amount of light in the longitudinal direction with respect to the linear irradiation region whose width dimension is limited. On the other hand, since the second side surface is wide, for example, it is suitable for arranging a plurality of light sources at the same position in the longitudinal direction of the light guide member.

  In a preferred embodiment, as the light source, LEDs of three colors R, G, and B are arranged in the width direction adjacent to the light incident portion of the light guide member. The light source device according to this embodiment can be suitably used as a light source device of a contact image sensor configured to read a color image. For each color, in addition to the absence of uneven illumination intensity in the longitudinal direction of the reading area, the LEDs of each color are arranged in the width direction of the light guide member, so 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 between each color can also be avoided. Further, although the blue (B) light emitting LED has been put into practical use, it is several times to several tens of times the price of the green (G) light emitting or red (R) light emitting LED. According to the above, it is possible to expect a significant cost reduction that a light source device for reading a color image can be configured by using one LED of each color of R, G, and B.

  In a preferred embodiment, the light exit surface which is the first side surface of the light guide member is a flat surface having a mirror finish. If it does in this way, the fall of the light emission efficiency by irregular reflection can be prevented, and the efficiency of a light guide member can be improved more as a whole.

  In a preferred embodiment, a mirror finish region and an irregular reflection region are mixed and provided on the second side surface where the light incident portion is formed. Light incident on the boundary surface of the mirror finish region from the inside of the transparent member at an angle larger than the critical incident angle is totally reflected. 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 the non-direction and returns to the inside of the transparent member. Then, part of the light irregularly reflected in this way reaches the first side surface, that is, the light exit surface at an incident angle equal to or smaller than the critical incident angle, and is irradiated to the outside. Therefore, by adjusting the area of the irregular reflection region, the amount of light emitted from the light exit surface can be adjusted.

  In a preferred embodiment, in the second side surface where the light incident portion is formed, the area ratio of the irregular reflection region to the mirror finish region is increased as the distance from the light incident portion increases. The amount of light that travels in the longitudinal direction and reaches the inside of 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 closer to the light incident portion, the stronger the light, but the farther away, the weaker the light. In the above embodiment, the ratio of the irregular reflection region formed on the second side surface is reduced at a position close to the light incident portion, while the proportion of the irregular reflection region is increased as the distance from the light incident portion increases. Thus, the amount of light emitted from the light exit surface can be averaged in the longitudinal direction of the light guide member. The irregular reflection region can be formed by painting a selected region on the second side surface, or by forming fine irregularities on the selected region on the second side surface. When the above-described irregular reflection region is formed by coating, it is desirable to use white coating in terms of reflection efficiency. In the case of forming the irregular reflection region by coating, it is desirable to form a rough surface in advance on the second side surface and to apply the coating on the rough surface in order to improve the adhesion of the coating. In this case, if a metal such as Al, Cr, Ag, etc. is vapor-deposited in the mirror finish region and the irregular reflection region, useless light leakage from the irregular reflection region can be prevented and efficiency can be improved.

  In a preferred embodiment, both ends of the transparent member are light reflecting surfaces. The light reflecting surface is formed by evaporating a metal layer, for example. As described above, the light guide member according to the present invention causes the light introduced to the transparent member from the light incident portion provided on the second side surface in the longitudinal direction thereof to be totally reflected and diffusely reflected at the boundary surface of the transparent member. However, the light travels toward the end in the longitudinal direction so that light is evenly emitted from the light exit surface of the first side surface. A part of the light traveling toward the end in the longitudinal direction eventually 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 passes through this boundary surface. Irradiated to the outside in vain. In this embodiment, the end of the transparent member is used as a light reflecting surface, so that the light that has reached the end surface of the transparent member as described above is returned again into the transparent member to improve efficiency.

  In a preferred embodiment, the light incident portion is formed at one place in the central portion in the longitudinal direction on the second side surface. When a monochromatic linear light source device is configured using this light guide member, for example, one LED may be disposed adjacent to the light incident portion. Therefore, as seen in the light source of the conventional contact type image sensor, compared with the arrangement of a plurality of light sources, the cost reduction due to the reduction in the number of LEDs and the prevention of variations in illuminance with respect to the linear illumination region are effective. realizable. The emission color of the LED is not limited, and a white LED may be employed.

  In another embodiment, the light incident portion is formed at a plurality of locations in the longitudinal direction on the second side surface. By doing so, it is possible to realize a light source device that expands the total extension of the linear light exit surface and can illuminate by averaging the longer linear illumination areas.

  In a preferred embodiment, the second side surface is inclined or curved so that the distance from the first side surface decreases as the distance from the light incident portion increases. 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 a decrease in the amount of light in the transparent member as the distance from the light incident portion where the light source is arranged increases, that is, the average density of light confined in the transparent member. Thus, the amount of light emitted from the light exit surface can be averaged in the longitudinal direction of the light guide member.

  According to the second aspect of the present invention, there is provided an image reading apparatus using the linear light source device according to the first aspect of the present invention. The image reading apparatus irradiates a document conveyed on a document reading surface formed on one surface of the casing with light from a light source device provided in the casing, and sets a reading line set on the document reading surface. An image reading apparatus in which reflected light from a document in a sheet is received by a plurality of light receiving elements arranged in the reading line direction in the casing, wherein the light source device is any one of the first side surface. 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 linear light source device provided by the first aspect of the present invention.

  Other features and advantages of the present invention will become more apparent from the following description of embodiments of the invention.

  Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

1 to 9 show reference examples of the light guide member. Figure 1 is a positive plane view of the light guide member 10, FIG. 2 is a bottom view, FIG. 3 is an enlarged front view of a longitudinal center portion of the light guide member 10, FIG. 4 is a progression state of the light guide member 10 described 5 is an enlarged front view of the longitudinal end portion of the light guide member 10. FIG.

  The light guide member 10 occupies the main part thereof, for example, 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 is opposed to the first side surface 11A in the vertical thickness direction and the first side surface 11A. The second side surface 11B, the third and fourth side surfaces 11C and 11D in the left-right width direction, and both longitudinal end surfaces 11E and 11F are provided.

  The first side surface 11 </ b> A is preferably a mirror-finished flat surface, and the first side surface functions as the light emitting surface 12 as will be described later. The second side surface 11B is a flat inclined surface in which the distance from the first side surface 11A is gradually reduced from the central portion in the longitudinal direction toward the end portion, and the surface thereof is a mirror-finished region 13. And the irregular reflection region 14 are mixed. In this embodiment, the central portion in the longitudinal direction of the second side surface 11 </ b> B is set as the light incident portion 15.

As a method of mixing the mirror-finished region 13 and the irregular reflection region 14 on the second side surface 11B, for example, the entire second side surface 11B is used as a mirror-finished surface, and, for example, white paint is applied to the selected region. As shown in FIGS. 2 and 3, a plurality of strip-shaped white coatings 14 </ b> A extending in the left-right width direction are applied to the second side surface 11 </ b> B in the longitudinal direction of the transparent member 11, and the inner surfaces of these white coatings 14 </ b> A are irregular reflection regions 14. To function as. In the embodiment shown in the figure, the strip-shaped white coating 14A has a coating width in the longitudinal direction of the transparent member that increases toward the end of the transparent member 11, and the mirror finish region 13 is formed on the second side surface 11B. The area ratio of the irregular reflection region 14 to the surface of the transparent member 11 is increased toward the end of the transparent member 11. When the white coating 14A is applied in this way, the coating adhesion is enhanced by forming the rough surface and then applying the coating. In addition to the white coating as described above, the irregular reflection region 14 may be formed by providing fine irregularities 14B in the forming step of the transparent member 11 or by processing as shown in FIG. . In this case, by evaporating a glossy metal such as Al, Cr, Ag or the like on the second side surface 11B, light can be prevented from leaking from the unevenness 14B and the efficiency can be increased. Further, when the irregular reflection region 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 increases toward the end of the transparent member 11. You may do it.

  As shown in FIG. 5, the longitudinal end surfaces 11E and 11F of the transparent member 11 are preferably light reflecting surfaces, for example, by vapor-depositing a metal layer 16, for example. The third and fourth side surfaces 11C and 11D in the left-right width direction of the transparent member 11 are preferably mirror-finished flat surfaces, but in addition to these, the third and fourth side surfaces A light reflecting surface may be formed by evaporating a metal layer (not shown) on the entire surface of 11C and 11D.

  As shown in FIG. 1, FIG. 3 and FIG. Is formed with a substantially V-shaped recessed portion 20. In the embodiment shown in the figure, the substantially V-shaped recessed portion 20 has two inclined surfaces 21 and 21 and a horizontal bottom surface 22 connecting the bottom ends of these inclined surfaces 21 and 21. It is formed in this way. It is desirable that the width of the bottom surface 22 be as small as possible.

In the reference example shown in the figure, the two inclined surfaces 21 and 21 in the recessed portion 20 are mirror-finished surfaces, while the bottom surface 22 is a light diffusing surface having irregularities as shown well in FIG. 22A. The light diffusion surface 22A may be formed when the transparent member 11 is molded, or a diffusion sheet may be attached to the mirror-finished surface. As will be described later, the reason why the bottom surface 22 of the substantially V-shaped recessed portion 20 is a light diffusing surface is that light incident into the transparent member 11 from the light incident portion 15 on the second side surface 11B side is directly In order to avoid the appearance of the bright spot through the first side surface 11A, the bottom surface of the recessed portion 20 can be prevented from the viewpoint of avoiding the appearance of the bright spot as shown in FIG. The light reflection surface 22 may be formed by evaporating the metal layer 22B.

  A light source 30 is disposed adjacent to the light incident portion 15 in the light guide member 10. In the present embodiment, one LED 30 </ b> A is attached so as to be attached to the light incident portion 15. In this case, it goes without saying that the light emitting portion of the LED 30 </ b> A faces the light incident portion 15 of the light guide member 10. As described above, the light emitting surface 12 including the entire area of the first side surface 11A of the light guiding member 10 having a certain longitudinal dimension is provided by the light guiding member 10 and the LED 30A disposed adjacent to the light incident portion 15. A linear light source device 35 that emits light from is configured. Hereinafter, the operation of the linear light source device 35 will be specifically described.

FIG. 4 shows the LED 30A disposed in the light incident portion 15 when it is assumed that the first side surface 11A, the second side surface 11B of the transparent member 11 and the inclined surfaces 21 and 21 of the recessed portion 20 are all mirror-finished surfaces. A traveling path of light incident on the transparent member 11 is schematically shown. Since the recessed portion 20 having the inclined surfaces 21 and 21 as described above is formed in a fixed region facing the light incident portion 15 in the first side surface 11A, the light emitted from the LED 30A is inclined to the inclined surfaces 21 and 21. 21 is incident at an angle larger than the total reflection critical angle, and also incident on the first side surface 11A at an angle larger than the total reflection critical angle. Therefore, the light is totally reflected on the inclined surfaces 21 and 21 of the recessed portion 20 and also totally reflected on the first side surface 11A. The light once totally reflected by the inclined surfaces 21 and 21 is also totally reflected because it is incident on the first side surface 11A at an angle larger than the total reflection critical angle. Furthermore, the light once totally reflected by the first side surface 11A is also totally reflected because it is incident on the second side surface 11B at an angle larger than the total reflection critical angle. In this way, most of the light emitted from the LED 30A travels toward the longitudinal end of the transparent member 11 while repeating total reflection on the first side surface 11A and the second side surface 11B.

Incidentally, in the light guide member 10, the bottom surface 22 of the concave portion 20, and a light diffusing surface 22A. If the bottom surface 22 is a mirror-finished surface, the incident angle of light from the LED 30A with respect to the bottom surface is smaller than the total reflection critical angle, so that the bottom surface 22 is transmitted through the bottom surface and irradiated to the outside. Light appears as a bright spot from the outside. However, in the light guide member 10 configured as described above, the bottom surface 22 of the recessed portion 20 is the light diffusion surface 22A. Therefore, as shown in FIG. 6, the light reaching the bottom surface 22 from the inside is diffused in a non-directional direction. Irradiated outside. Therefore, there is no appearance of a bright spot as described above, and light is totally reflected on the inclined surfaces 21 and 21 of the recessed portion 20, so that the light irradiated to the outside near the central portion in the longitudinal direction of the light guide member is reduced. The amount of light emitted from the central portion in the longitudinal direction as the linear light source device 35 is ensured.

Further, in the light guide member 10, the second side surface 11B, are provided diffuse reflection region 14 made of white painted 14A as described above. The light reaching the irregular reflection region 14 from the inside is irregularly reflected in the non-direction toward the inside of the transparent member 11. Of the light thus irregularly reflected, the light that has reached the first side surface 11A at an angle smaller than the total reflection critical angle passes through the first side surface 11A and is irradiated outside as illumination light.

The closer to the light incident part 15 where the LED 30A is arranged, the stronger the light traveling in the transparent member 11, but in the above reference example , the closer to the light incident part 15, the smaller the area ratio of the irregular reflection region 14 is. Therefore, the amount of light emitted through the first side surface 11A is suppressed. On the other hand, the light traveling in the transparent member 11 becomes weaker as the distance from the light incident portion 15 is increased. However, in the reference example , the area ratio of the irregular reflection region 14 is increased as the distance from the light incident portion 15 is increased. The weakening of the light in the transparent member 11 is compensated, and the amount of light transmitted through the first side surface 11A in the end region is ensured. In this way, the amount of light emitted from the first side surface 11 </ b> A of the light guide member 10 and illuminating the linear illumination region can be made uniform in the longitudinal direction of the light guide member 10.

In the reference example shown in the figure, the second side surface 11B of the light guide member 10 is inclined so as to approach the first side surface 11A toward the end portion, and the vertical thickness dimension of the light guide member 10 increases toward the end portion. The reduction also compensates for the light traveling in the transparent member 11 becoming weaker toward the end, and contributes to emitting light of uniform intensity over the entire length in the longitudinal direction. Furthermore, in the above reference example , the light reflecting surfaces 16 by metal vapor deposition are provided on the both end surfaces 11E and 11F of the transparent member 11, so that the light that travels through the transparent member 11 and reaches the end portion is wasted. It is possible to avoid being released.

9 to 11 show the first embodiment of the light guide member 10 and the linear light source device 35 using the same. In this embodiment, the difference from the reference example described above is that, as shown in FIGS. 10 and 11, the lateral width surface of the transparent member 11 forming the light guide member 10 is changed from the second side surface 11B to the first side surface 11A. As the light travels toward the point, and the light incident portion 15 at the center in the longitudinal direction of the second side surface 11B, red (R) light emitting LED 30R, green (G) light emitting LED 30G, and blue ( B) Three LEDs of the light emitting LED 30 </ b> B are arranged in the width direction of the light guide member 10. These LEDs 30R, 30G, and 30B do not protrude laterally from the region facing the second side surface 11B.

  As described above, the configuration in which the lateral width of the light guide member 10 is reduced toward the first side surface 11A suppresses the width direction dimension of the first side surface 11A within a certain range, so that the linear light source is limited in the width direction. While it is possible to irradiate light efficiently to the area, the three LEDs 30R, 30G, and 30B are not protruded to the side of the light guide member 10 as described above on the second side surface 11B. They are suitable for arranging them at the same position in the longitudinal direction of the light guide member 10.

The light emitted from the LEDs 30R, 30G, and 30B of the respective colors is radiated in a uniform manner from the light emitting surface 12 of the full length region of the first side surface 11A of the light guide member 10 as described in the above reference example. . By adjusting the outputs of the LEDs 30R, 30G, and 30B for each color, full color can be developed. As will be described later, by sequentially switching the LEDs 30R, 30G, and 30B for each color to emit light, it is possible to function as a light source device for a contact type color image sensor that commonly uses a light receiving element.

  12 and 13 show a contact type color image sensor 40 using the light guide member 10 and the linear light source device 35 shown in FIGS. 9 to 11. The image sensor 40 includes an image reading surface 42 made of a transparent glass plate on an 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 line by line.

  A substrate 44 is attached to the lower surface of the casing 41, and a plurality of image sensor chips 45 in which a predetermined number of light receiving elements are formed are attached to the substrate 44 in a row. For example, in order to read an A4 width original at a reading density of 8 dots / mm, 1728 light receiving elements are arranged at a 125 μm pitch. For example, 96 light receiving elements are integrally formed in one image sensor chip 45. Accordingly, in this case, 18 image sensor chips 45 are arranged on the substrate.

  A plurality of image sensor chips 45 are arranged at a position vertically below the reading line L set on the image reading surface 42, and a lens array 46 is disposed between the reading line L and the image sensor chip 45. The The lens array 46 focuses the image on the reading line L onto 1728 light receiving elements arranged on the plurality of image sensor chips 45 at an equal magnification.

A linear light source device 35 having the form shown in FIGS. 9 to 11 is arranged in a space set on the side of the lens array 46 below the image reading surface 42 in the casing 41. In this case, the light guide member 10 is arranged so that the left-right width direction center line L ₁ faces the reading line L of the image reading surface 42. The three LEDs 30R, 30G, and 30B that emit light of R, G, and B colors 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 are guided. The members 10 are arranged in the left-right width 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, while feeding the document D by a predetermined pitch, image data for each color R, G, B of the document image on the reading line L is switched by the image sensor chip 45 while switching the LEDs 30R, 30G, 30B of each color. Read sequentially.

In the contact-type color image sensor 40, the linear light source device 35 has one LED 3 for each color.
Since the light emitted from 0R, 30G, and 30B is uniformly spread over the illumination area of a predetermined length and irradiated, the uneven distribution of the light amount in the reading width direction assumed when using a plurality of LEDs, It is possible to effectively eliminate factors that degrade image reading quality, such as deviations in the color tone of the read image due to subtle differences in the colored light of each LED. Further, since the LEDs 30R, 30G, and 30B of the respective colors are arranged at the same position in the longitudinal direction of the light guide member 10, the deviation of the color tone of the read image that is assumed when the LEDs of the respective colors are arranged in the reading width direction. Can be effectively avoided. Furthermore, since the light traveling in the light guide member 10 is concentratedly irradiated from the first side surface 11A of the light guide member 10, the illumination efficiency is very good, and each LED 30R, 30G, 30B of each color is Despite the use, a sufficient amount of illumination light can be secured. Furthermore, since the LEDs 30R, 30G, and 30B that are light sources are disposed in the middle portion in the longitudinal direction of the light guide member 10, for example, compared to the case where the LEDs that are light sources are disposed at the end of the light guide member 10, The longitudinal dimension of the casing 41 is saved, and downsizing of this type of contact type color image sensor 40 is promoted.

FIG. 14 is a front view showing a second embodiment of the light guide member 10 or the linear light source device 35. 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 FIG. 9 to FIG. 11 as one unit, and is continuous for two units in the longitudinal direction. It is a thing. Since the light guide member 10 or the linear light source device 35 is provided with the light incident portion on the second side surface 11B of the intermediate portion in the longitudinal direction of the transparent member 11, it is possible to extend the linear illumination range in the longitudinal direction. Become.

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

It is a front view of the reference example of a light guide member or a linear light source device using the same. It is a bottom view of the light guide member thru | or linear light source device shown in FIG. It is an enlarged front view of the longitudinal direction center part of the light guide member thru | or linear light source device shown in FIG. It is explanatory drawing of the advancing condition of the light in the transparent member in the light guide member thru | or linear light source device shown in FIG. It is an enlarged front view of the edge part of the light guide member thru | or linear light source device shown in FIG. It is an enlarged view of the substantially V-shaped recessed part formed in the 1st side surface of a transparent member in the light guide member thru | or linear light source device shown in FIG. It is an enlarged view of the modification of a substantially V-shaped recessed part. In the light guide member or linear light source device shown in FIG. 1, it is explanatory drawing of the modification of the irregular reflection area | region formed in the 2nd side surface of a transparent member. It is a principal part front view of 1st Embodiment of a light guide member thru | or a linear light source device using the same. It is an expanded sectional view which follows the XX line of FIG. It is an expanded sectional view which follows the XI-XI line of FIG. FIG. 12 is a central cross-sectional view of a contact color image sensor using the light guide member or the linear light source device shown in FIGS. 9 to 11. It is sectional drawing which follows the XIII-XIII line | wire of FIG. It is a front view of 2nd Embodiment of a light guide member thru | or a linear light source device using the same. It is sectional drawing which shows the general structure of the conventional contact type image sensor. It is sectional drawing which follows the XVI-XVI line | wire of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Light guide member 11 Transparent member 11A 1st side surface 11B 2nd side surface 12 Light-emitting surface 15 Light incident part 20 Recessed part 21 Inclined surface 20 Light source 30A LED
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 Document

Claims (6)

A light guide member configured to include a long transparent member having a first side surface and a second side surface facing in the thickness direction, and a light source,
The first aspect is the light emitting surface, and with which the light incident portion is formed in the longitudinally intermediate portion of the second side surface, the light source is closely worn on the light incident portion, the light incident The light incident from the portion is configured to be emitted from the entire or almost entire region of the light emitting surface while traveling toward the both ends in the longitudinal direction while totally reflecting and irregularly reflecting on the outer surface of the transparent member. And
A substantially V-shaped recessed portion having two inclined surfaces and a bottom surface connecting the bottom end portions of these inclined surfaces is formed at a portion facing the light incident portion on the first side surface.
The bottom surface is a light diffusing surface or a light reflecting surface,
The linear light source device according to claim 1, wherein a width of the second side surface is longer than a width of the first side surface, and the light source faces a light incident portion on the second side surface.   The said light source has three LED of R, G, B, these are located in the width direction of the said 2nd side surface, and are arrange | positioned in the longitudinal direction same position of the said light guide member. Linear light source device.   3. The linear light source device according to claim 2, wherein the width of the second side surface is a width that does not protrude from a region where the three LEDs face the second side surface. 4. The linear light source device according to claim 1 , wherein the light incident portion is formed at one place in a longitudinal central portion of the second side surface. The light entrance portion, the longitudinal direction of the second side surface are a plurality of locations forming linear light source device according to any one of claims 1 to 3. Light from a light source device provided in the casing is irradiated onto a document conveyed on a document reading surface formed on one surface of the casing, and reflected light from the document on a reading line set on the document reading surface. A linear light source device according to any one of claims 1 to 5, wherein the light source device receives light from a plurality of light receiving elements arranged in the reading line direction in the casing. An image reading apparatus, wherein the light emitted from the light emitting surface is configured to illuminate the original on the reading line.

Images