JP2000358130A - Image reader and light guide unit used for it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance efficiency of light emission to a read object area while preventing the entire volume of a transparent member from being increased in the case of using a transparent material for a light guide so as to lead light emitted from a light source device to the linear read object area. SOLUTION: An image reader A is provided with a light source device 8, a light guide means U that leads light emitted from the light source device 8 to a linear read object area S, and a plurality of lenses 20 that form the image of the read object areas onto a plurality of light receiving elements 6. The light guide means U consists of a 1st transparent member 4 where at lest an entire part or part of a light incident face 40A opposed to the light source device 8 or a light emission face 40B opposed thereto is formed to be a projected curved plane extended in the lengthwise direction of the read object area S and of a 2nd transparent member 5 that is formed to be a separate member from the 1st transparent member 4 and leads the light emitted from the light emission face 40B to the read object area S.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus and a light guide unit used for the same, and more particularly to an image reading apparatus for copying a figure or a character drawn on an electronic blackboard such as a whiteboard. The present invention relates to an image reading apparatus used for reading applications and other applications for reading images of various kinds of documents, and a light guide unit used for the same.

[0002]

2. Description of the Related Art As is well known, a general configuration of a line image sensor type image reading device is to illuminate a line-shaped reading target region with a light source device, and to use a plurality of lenses to reflect light reflected by the reading target region. The image of the reading target area is formed on a plurality of light receiving elements by converging with the use of. Since the plurality of light receiving elements output an image signal of an output level corresponding to the amount of received light, a read image can be obtained based on the image signal.

In the image reading apparatus having such a configuration, it is necessary to efficiently guide the light emitted from the light source device to the reading target area while making the structure of the entire apparatus as simple as possible. Therefore, conventionally, for example, Japanese Patent Application Laid-Open
By providing a transparent member (prism) for guiding light as opposed to the light source device as described in JP-A-307696, light emitted from the light source device is advanced into the transparent member. There is a means for guiding to a desired reading target area. According to such means, since the path of the light emitted from the light source device can be defined by the transparent member, for example, even if the light source device does not directly face the reading target region, the reading target region can be defined. Can guide the light to

[0004]

However, in the prior art, the transparent member for guiding the light is merely constituted as a single component, and the surface of the transparent member which receives light from the light source device ( The light incident surface) had a mere planar shape, causing the following problems.

That is, in the case where light is guided to a reading target area using a transparent member for guiding light, most of the light emitted from the light source device is transmitted in order to improve the irradiation efficiency of the light to the reading target area. It is necessary to advance inside the member.
For that purpose, the area of the light incident surface of the transparent member that receives light from the light source device must be increased.

However, conventionally, if one end of the transparent member is formed wide for the purpose of increasing the area of the light incident surface of the transparent member, most of the other region of the transparent member is accordingly formed. It had to be formed wide. The reason is that the transparent member travels toward the reading target area while totally reflecting the light that has traveled inside the transparent member through the smooth outer surface of the transparent member, and where the shape or width of the transparent member suddenly changes. Is formed, light traveling inside the transparent member leaks out of the transparent member, and it is difficult to efficiently guide the light to the reading target area. In particular, a light beam traveling from the light source device toward the transparent member is generally a non-parallel light beam, and the light beam travels at a constant spread angle even inside the transparent member. In order to guide most of the transparent member to the reading target region by the action of total reflection, it is more strongly required that the transparent member does not have a portion where the shape, width, and the like change suddenly. further,
In order to prevent the light that enters the transparent member from the light incident surface from reaching the side surface of the transparent member as it is and leaking out, it is necessary to make the width of the transparent member in the vicinity of the light incident surface considerably large. is there.

As described above, conventionally, when the light incident surface of the transparent member is to be increased, it is necessary to form the transparent member so as to be wide over substantially the entirety of the transparent member. As a result, when the distance between the light source device and the reading target area is large and the transparent member needs to be formed long,
The entire volume of the transparent member becomes very large, and the production cost becomes high.

The present invention has been conceived in view of such circumstances, and guides light emitted from a light source device to a line-shaped reading target area using a transparent member for guiding light. In this case, it is an object of the present invention to minimize the increase in the volume of the transparent member as much as possible and to increase the efficiency of light irradiation on the reading target area.

[0009]

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

[0010] According to a first aspect of the present invention, there is provided an image reading apparatus. The image reading device includes a light source device, a light guiding unit for guiding light emitted from the light source device to a linear read target region, and forms an image of the read target region on a plurality of light receiving elements. An image reading device comprising a plurality of lenses for, the light guide means has a light incident surface that receives light from the light source device and a light exit surface that faces the light incident surface, A first transparent member in which at least one of the light incident surface and the light exit surface is a convex curved surface extending in the longitudinal direction of the read target region, and a first transparent member separate from the first transparent member; And a second transparent member provided so as to guide the light emitted from the light emitting surface of the first transparent member to the reading target area. .

In the image reading device provided by the present invention, the light emitted from the light source device passes through the light entrance surface and the light exit surface of the first transparent member and then passes through the second light transmission device.
And is guided to the reading target area. Even if the light emitted from the light source device travels at a constant spread angle toward the first transparent member, this light is refracted when passing through the convex curved surface of the first transparent member, so that the refraction action Reduces the spread angle of light,
The light can be made into a parallel light beam or a light beam close thereto, for example, and can be advanced into the second transparent member. Therefore, unlike the case where the light travels inside the second transparent member at a certain spread angle, even if the entirety is formed to have a relatively narrow size, the light traveling inside the second transparent member is kept in the second transparent member. Can be efficiently reflected by the outer surface of the transparent member and guided to the reading target area. On the other hand, the first transparent member may be formed in a size that can secure a light incident surface of a desired area, and the formation can be performed separately from the second transparent member. As a result, in the present invention, unlike the related art, since the area of the light incident surface for receiving the light from the light source device is increased, the entire transparent member, that is, the first transparent member and the second transparent member are used. It is no longer necessary to form the entire structure in a wide size, and the manufacturing cost can be reduced.

Further, in the present invention, since the first transparent member and the second transparent member are separate bodies,
Alternatively, it is also possible to easily adjust the light amount distribution of the light guided to the reading target area by using the surfaces facing each other, for example, as described later.

In a preferred embodiment of the present invention, each of the light entrance surface and the light exit surface of the first transparent member has the convex curved surface.

According to such a configuration, since the light can be refracted by each of the light incident surface and the light exit surface of the first transparent member, the total amount of light refraction can be increased. . Therefore, it is possible to accurately convert a light beam that has traveled from the refraction amount light source device toward the first transparent member with a certain spread angle into a parallel light beam or to approach it.

[0015] In another preferred embodiment of the present invention, each of the lenses forms a reduced image of the reading target area on the plurality of light receiving elements, and the first transparent member and The second transparent member is configured such that the illuminance of a portion far from the optical axis of each of the lenses in the read target area can be higher than the illuminance of a portion near each of the optical axes. The light received by one of the transparent members is guided to the above-mentioned reading target area with a light amount distribution different from that.

According to such a configuration, it is possible to obtain a reduced image that is faithful to the density of the image in the reading target area.
That is, in the above configuration, for example, a convex lens is used as each lens, and a reduced image of the reading target area is formed on a plurality of light receiving elements. In such a case,
Even if the density and illuminance of each part of the reading target area are uniform, the image formed on the plurality of light receiving elements is closer to the optical axis of each lens due to the characteristics of each lens. A peculiar phenomenon of becoming brighter than the part away from the optical axis occurs. This is because when each lens forms a reduced image, light passing through each lens is focused so as to approach the optical axis. However, in the above configuration,
Since it is possible to reduce the illuminance of the portion near the optical axis of each lens in the reading target area, the reduced images formed on the plurality of light receiving elements are caused by the characteristics of each lens. The portion near the optical axis of the lens can be prevented from being brighter than other portions. Therefore, on each light receiving element, it is possible to form a reduced image accurately corresponding to the density of the actual image of the reading target area.

In another preferred embodiment of the present invention, the second transparent member has a light incident surface facing the light emitting surface of the first transparent member, and a light emitting surface facing the reading target area. And at least one of the light incident surface of the second transparent member and the light emitting surface of the first transparent member, or between them, the inside of the second transparent member. The light amount distribution changing means is provided to make the light amount distribution of the light traveling through the first transparent member different from the light amount distribution of the light traveling inside the first transparent member.

According to such a configuration, since the light amount distribution can be changed at a position distant from the reading target area, the illuminance of the reading target area can be easily adjusted. That is, unlike the above configuration, when the light amount distribution is changed at a location close to the reading target area, if there is a location where the light quantity changes suddenly, the illuminance suddenly changes in the reading target area correspondingly. Are likely to occur. On the other hand, if the light amount distribution is changed at a location distant from the reading target area, the reading target area is separated from that point even if there is a sudden change in the light amount at that part. This makes it less likely to be directly affected by the influence, and it becomes easy to gradually change the illuminance of the reading target area.

In another preferred embodiment of the present invention, the light amount distribution changing means is provided alternately on the light incident surface of the second transparent member so that the light incident surface is uneven. There are a plurality of concave curved portions and a plurality of convex curved portions.

According to such a configuration, when the light emitted from the light emitting surface of the first transparent member enters the light incident surface of the second transparent member, the light of the concave curved surface portion or the convex curved surface portion is not changed. By refracting the light by the action, it is possible to set the light amount distribution of the light applied to the reading target region to a desired state. When changing the light amount distribution, it is not necessary to provide a special member for the second transparent member.

In another preferred embodiment of the present invention, the light source device comprises a plurality of LED light sources arranged in a row at intervals, and each of the LED light sources is connected to a corresponding one of the lenses. It is offset from the position of the optical axis in the longitudinal direction of the reading target area.

According to such a configuration, it is possible to reduce the amount of light applied to the portion near the optical axis of each lens in the reading target area by the amount that each LED light source is offset from the optical axis of each lens. Become. Therefore, it is easy and reliable to make the illuminance of the portion near the optical axis of each lens in the reading target area lower than that of the portion far from the optical axis.

In another preferred embodiment of the present invention, the first transparent member and the second transparent member are formed such that a part thereof fits with each other.

According to such a configuration, the operation of aligning and combining the first transparent member and the second transparent member with each other is facilitated.

In another preferred embodiment of the present invention, the light source device, the lenses, the light receiving elements,
A case in which each of the first transparent member and the second transparent member is incorporated;
A part of the transparent member near the light exit surface protrudes outward from the case.

According to such a configuration, even when the case in which the predetermined component group is incorporated is set at a position distant from the read target area, the light emitting surface of the second transparent member is not read. The area can be approached. Therefore, it is possible to improve the light irradiation efficiency to the reading target area. Further, the illuminance of the reading target area can be made to accurately correspond to the emission light amount distribution on the light emission surface of the second transparent member.

According to a second aspect of the present invention, there is provided a light guiding unit. This light guide unit is a light guide unit including a first transparent member and a second transparent member formed separately from each other, wherein the first transparent member extends in a predetermined direction. Having a light incident surface for receiving external light and a light exit surface facing the light incident surface, and a whole or a part of at least one of the light incident surface and the light exit surface Are convex curved surfaces extending in the same direction as those surfaces, and the second transparent member is emitted from the light emitting surface of the first transparent member as a plurality of side surfaces extending in a certain direction. It is characterized by having a light incident surface for receiving light, and a light emitting surface for emitting light that has traveled into the second transparent member from the light incident surface to the outside.

In the light guide unit having such a configuration, when a light beam having a certain spread angle is advanced from the light incident surface into the first transparent member, at least one of the light incident surface and the light output surface is formed. The spread angle of the light beam can be reduced by the action of the convex curved surface. Then, the light can travel from the light incident surface of the second transparent member to the inside thereof, and can be emitted from the light emitting surface of the second transparent member toward a desired linear region.
Therefore, as a means for guiding the light emitted from the light source device of the image reading device to a linear reading target area,
This light guiding unit can be suitably used, and the same effect as obtained by the first aspect of the present invention can be expected.

[0029] Other features and advantages of the present invention will become more apparent from the following description of embodiments of the present invention.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a sectional view showing an example of an image reading apparatus according to the present invention. FIG. 2 is a sectional view taken along line II-II of FIG. FIG. 3 is a sectional view taken along line III-III of FIG. FIG. 4 is a partially sectional perspective view showing an example of the first transparent member. FIG. 5A is a front view illustrating an example of the second transparent member, and FIG. 5B is a right side view thereof.

The image reading apparatus A of the present embodiment shown in FIGS. 1 to 3 has a white board WB as an electronic blackboard.
1 is configured as an image reading device for taking reduced copies of figures, characters, and the like described in FIG. In general, the whiteboard WB has a posture in which the surface spreads in a substantially vertical direction. However, in the present embodiment, unlike the above, the surface of the whiteboard WB is drawn horizontally, and the whiteboard WB is positioned vertically. The relationship will be described with reference to the drawings. In the figure, the direction of arrow N1 is the main scanning direction, and the direction of arrow N2 perpendicular thereto is the sub-scanning direction.

1, the image reading apparatus A includes a case 1, a lens array 2, a lens array cover 3, a light guiding unit U, a light source device 8, a plurality of light receiving elements 6, and a substrate 7 It is comprised including. The light guide unit U includes a first transparent member 4 and a second transparent member 5.

The case 1 is made of a synthetic resin, and has a roughly elongated block shape extending in a certain direction as a whole. In the case 1, through-hole-shaped spaces 10 and 11 for incorporating the above-described components are formed extending in the longitudinal direction of the case 1. Case 1 extends in the main scanning direction, and is supported by support means (not shown) such that its surface (upper surface) faces the surface of whiteboard WB at a predetermined interval, and is supported in the sub-scanning direction. It is provided movably.

The lens array 2 has a plurality of convex lenses 20 held in a synthetic resin holder 21 and is set at a predetermined height by being fitted in the space 10 of the case 1. The plurality of convex lenses 20 are arranged at regular intervals in a row extending in the main scanning direction. It is also possible to use a lens array in which a plurality of convex lenses and a holder for holding the convex lenses are integrally formed of synthetic resin. On the surface of the whiteboard WB, a region that intersects with the optical axes C of the plurality of convex lenses 20 and extends linearly in the main scanning direction is a reading target region S. In the present invention, it is not always necessary to use a lens configured as a lens array. For example, in the present invention, a structure may be used in which a case is formed with a portion instead of a holder, and a plurality of lenses are arranged in a row in this portion and individually mounted.

The lens array cover 3 is made of, for example, a black synthetic resin, and is fitted over the space 10 and disposed above the lens array 2. The lens array cover 3 also serves to hold down the lens array 2 to fix it. The lens array cover 3 is provided with a plurality of light transmitting holes 30 as apertures for defining the amount of light incident on each convex lens 20. The center of each light transmitting hole 30 is aligned with the optical axis C of each convex lens 20, and in this embodiment, the inner diameter d1 of each light transmitting hole 30 is smaller than the diameter d2 of each convex lens 20. In this way, since light can be prevented from being incident on the vicinity of the outer peripheral edge of each convex lens 20 from the outside, aberration can be reduced and the image formed by each convex lens 20 can be sharpened. Can be If the inner diameter of each light-transmitting hole 30 is increased, the image can be brightened, but the sharpness of the image decreases.

The plurality of light receiving elements 6 have a photoelectric conversion function, and are mounted on the surface of the substrate 7. Substrate 7
Is attached to the bottom of the case 1 so as to close the bottom openings of the spaces 10 and 11. By assembling the substrate 7, each light receiving element 6 faces each convex lens 20, and an inverted reduced image of the reading target area S can be formed on each light receiving element 6 by using each convex lens 20. . 3, the plurality of light receiving elements 6 are formed into one chip as one sensor IC chip 60 for each of a fixed number of light receiving elements corresponding to each of the plurality of convex lenses 20. Since the sensor IC chips 60 are arranged in the main scanning direction at appropriate intervals, the plurality of light receiving elements 6 are also arranged in the same direction. Case 1
Is provided with a partition wall 19 that partitions the space 10 into a plurality of chambers each provided with one convex lens 20 and one sensor IC chip 60 so that light does not interfere with each other between the chambers. Considered.

The light source device 8 includes a plurality of LEs on the surface of the substrate 7.
The D light source 80 is configured by being arranged at a constant interval in the main scanning direction, and is arranged at the bottom of the space 11 of the case 1. However, each LED light source 80 is offset from the optical axis C of each convex lens 20 by an appropriate dimension L in the main scanning direction, as best seen in FIG. L
As the ED light source 80, for example, a green LED and a red LE
A combination of D and D is used. With this configuration, when only the red LED emits light, the red portion of the reading target area S does not reflect the light.
Image reading for the red portion is not performed. On the other hand, when only the green LED emits light, the entire image can be read regardless of the color of the reading target area S. Therefore, by comparing these two types of read images, it is possible to distinguish between a red portion and a non-red portion, and to perform so-called two-color reading. Such reading is most suitable for use in copying a whiteboard WB that uses a lot of red in addition to black. However,
The present invention is not limited to this, and it goes without saying that the light source device 8 may be configured to emit only monochromatic light such as white or green.

The first transparent member 4 is a resin molded product,
As a specific material, PMMA (polymethyl methacrylate (methacrylic resin)) or PC (polycarbonate) having excellent transparency and mechanical strength is used. As is clearly shown in FIG. 4, the first transparent member 4 has a substantially bar shape extending in a certain direction.
Are respectively defined as surfaces extending in the longitudinal direction of the transparent member 4.
There is a downward light incident surface 40A wider than the ED light source 80 and an upward light exit surface 40B opposed thereto. Each of the light incident surface 40A and the light emitting surface 40B is a mirror-like surface, and the whole or substantially the whole thereof is directed downward or upward extending uniformly in the longitudinal direction of the first transparent member 4 in cross section. It is a convex curved surface. The mirror surface in the present invention does not need to be a surface that has been positively polished. For example, a surface that is smoothly formed by die molding is also included in the mirror surface. In the present embodiment, the light incident surface 40
The light exit surface 40B is a convex curved surface having a larger curvature than A.

On both sides in the width direction of the first transparent member 4, a pair of legs 41 projecting below the light incident surface 40A and extending in the longitudinal direction of the first transparent member 4 are provided. ing. As clearly shown in FIG. 1, the first transparent member 4 is mounted on the substrate 7 such that the pair of legs 41 abut on the surface of the substrate 7 in a state where the first transparent member 4 is fitted in the space 11 of the case 1. 7 so that the light incident surface 40 </ b> A is close to and opposed to each LED light source 80. The first transparent member 4 has a posture in which the light incident surface 40A and the light exit surface 40B extend in the main scanning direction.

The second transparent member 5, like the first transparent member 4, is a resin molded product made of, for example, PMMA or PC. The second transparent member 5 has a substantially plate shape extending in a certain direction. The plurality of side surfaces extending in the longitudinal direction of the second transparent member 5 include a light incident surface 50A, a light emitting surface 50B, and a light emitting surface 50B. Light incident surface 50A and light emitting surface 5
0B and two side surfaces 50 facing each other in the thickness direction to connect
C and 50D. These surfaces 50A to 50D are all mirror-like. As described above, when the side surfaces of the respective portions of the second transparent member 5 are made mirror-like, the critical angle of total reflection (for example, about 45 °) specified by the material of the second transparent member 5 with respect to each surface is provided. Light rays incident at an angle of incidence larger than ()) can be totally reflected. On the other hand, light rays incident at an incident angle smaller than the critical angle for total reflection can be transmitted through the surface as it is.

In the vicinity of the light incident surface 50A of the second transparent member 5, a plurality of legs 51 projecting downward from the light incident surface 50A are continuously provided. The plurality of legs 51 are
The transparent member 5 is provided so as to be branched into right and left branches in a side view of the transparent member 5. As shown in FIG. 5A, the transparent member 5 is provided at an appropriate distance in the longitudinal direction of the second transparent member 5. I have. However, these legs 51 are connected to the first transparent member 4.
Like the leg portion 41, the second transparent member 5 may be formed in a form extending continuously in the longitudinal direction. Multiple legs 5
When a plurality of 1s are provided at appropriate intervals, it is preferable that the leg portions 51 provided on the side surface 50C and the leg portions 51 provided on the side surface 50D are arranged differently from each other. By doing so, the die-cutting step when the second transparent member 5 is molded can be facilitated.

As can be seen in FIG. 1, the second transparent member 5 has a portion close to the light exit surface 50 B protruding outside the case 1, and the other portions being the same. It is housed in the space 11. Each tip of the plurality of legs 51 is fitted into a concave portion 41a formed above each leg 41 of the first transparent member 4, whereby the first transparent member 4 and the second transparent member 4 are fitted. Positioning with the member 5 in the width direction is achieved. The middle part of the second transparent member 5 in the vertical direction is the upper end edge 11 of the space 11 of the case 1.
a, the positioning and holding of the second transparent member 5 with respect to the case 1 are achieved. FIG.
As shown in (a) and (b), a convex portion 52 or a concave portion instead of the convex portion 52 is provided on the end surface of each of the two longitudinal end portions of the second transparent member 5. The concave portion is also used for positioning when attaching the second transparent member 5 to the case 1.

The light incident surface 50A of the second transparent member 5 is disposed so as to face the light emitting surface 40A of the first transparent member 4. 5A, the light incident surface 50A is formed as a smooth uneven surface in which a plurality of curved concave curved portions 53 and a plurality of convex curved portions 54 are alternately connected to each other. Have been. The concave curved surface portion 53 and the convex curved surface portion 54 correspond to an example of a light amount distribution changing unit according to the present invention. The pitch P of the plurality of concave curved surface portions 53 is the same as the pitch of each convex lens 20 of the lens array 2, and as shown in FIG.
The center in the width direction of 3 is a position overlapping with the optical axis C of each convex lens 20. The plurality of LED light sources 80 are
0 is offset from the optical axis C by an appropriate dimension L in the main scanning direction, and is provided so as to face the vicinity of both ends of the plurality of concave curved surface portions 53 with the first transparent member 4 interposed therebetween. I have.

Side surfaces 50C, 50D of second transparent member 5
Is a curved surface. As a result, the second transparent member 5 is bent in a side view, as shown in FIG. 1, and the LED light source 80 distant from the optical axis C of each convex lens 20 has a light incident surface 50A. Are opposed to each other, and the light emission surface 50B is opposed to the reading target region S coinciding with the optical axis C.

Next, the operation of the image reading apparatus A having the above configuration will be described.

First, in FIG. 1, when each LED light source 80 emits light, the light is transmitted from the first light incident surface 40A to the first light incident surface 40A.
And exits from the light exit surface 40B. However, the light incident surface 40A and the light exit surface 4A
Since 0B is a convex curved surface, a light refraction effect similar to that of a convex lens occurs. For this reason, the light beam traveling from each LED light source 80 at a certain spread angle can be converted into a parallel light beam or a light beam close thereto. For example, FIG.
As shown in (2), when the width Lc of the convex curved surface portion 49 of the first transparent member 4 is narrow, if there is a displacement of the LED light source 80 with respect to the center line Ca of the convex curved surface portion 49, Even if the displacement amount La is small, it is difficult to convert many of the light beams emitted from the LED light source 80 into parallel light beams. On the other hand, as in the image reading apparatus A of the present embodiment, if the first transparent member 4 is formed to be wide and the width of the convex curved surface is increased, the LED light source 80 is slightly positioned from the center of the convex curved surface. Even if it is shifted, the light emitted from the LED light source 80 can be appropriately converted into a parallel light or a light close thereto. Further, if the light incident surface 40A is made wider, the amount of light received by the first transparent member 4 can be increased accordingly, so that the amount of light emitted from the light emitting surface 40B can be increased.

The light emitted from the light emitting surface 40B travels from the light incident surface 50A to the inside of the second transparent member 5. In this case, some of the light traveling in the second transparent member 5 includes light that reaches the side surfaces 50C and 50D. However, since these lights are formed as parallel light beams or light beams close thereto,
Even when the entire width Lb of the second transparent member 5 is relatively thin, the angle of incidence of the light on each of the side surfaces 50C and 50D can be increased. Therefore,
The amount of light that passes through the side surfaces 50C and 50D and leaks to the outside as it is is reduced, and most of the light that has traveled into the second transparent member 5 is guided to the light emitting surface 50B while being totally reflected by the side surfaces 50C and 50D. Can be. As a result, it is possible to efficiently irradiate light from the light emitting surface 50B to the entire length of the line-shaped read target region S while reducing the thickness of the entire second transparent member 5.

On the other hand, when the course of the light emitted from the LED light source 80 is observed in the cross section shown in FIG.
Light traveling at a constant spread angle from the ED light source 80 passes through the first transparent member 4 with some refraction, and then enters the light incident surface 50A of the second transparent member 5 at various angles. Each LED light source 80 has a light incident surface 50A.
Of the convex curved surface portion 54 sandwiching the concave curved surface portion 53, the convex curved surface portion 54 efficiently receives a light beam having a high luminous flux density, and receives the received light. Are refracted so as to proceed in a direction away from the optical axis C of each convex lens 20. Light emitting surface 50
Light emitted from the plurality of LED light sources 80 arrives at B in an overlapping state, but each convex curved surface portion 54 increases the degree of overlapping of light in the vicinity of the central portion between the optical axes C adjacent to each other. In this way, light is refracted. Each concave curved surface portion 53 also receives light, but the light is refracted so as to travel while being dispersed toward the light emitting surface 50B.
Since each LED light source 80 is offset from the optical axis C of each convex lens 20 by an appropriate amount L, each LED light source 8
A light beam having a high luminous flux emitted from the light exit surface 50
There is no straight forward movement toward the portion near the optical axis C in B.

As described above, the distribution of the amount of emitted light on the light exit surface 50 B of the second transparent member 5 is
A is different from the light amount distribution of the light received by A, and the light amount of the portion corresponding to the optical axis C of each convex lens 20 is the smallest and the further away from that portion, that is, the central part of the optical axes C adjacent to each other The closer the distance is, the more the light amount gradually increases. Therefore, the illuminance distribution in the longitudinal direction of the line-shaped read target area S also corresponds to the light quantity distribution of the light exit surface 50B.

When light is applied to the reading target area S,
As shown in FIG. 3, the reflected light from the reading target area S is focused by each convex lens 20, so that an inverted reduced image of the reading target area S is formed on each light receiving element 6. Each light receiving element 6 outputs an image signal of an output level corresponding to the amount of received light. Each convex lens 20 itself has a characteristic of forming an inverted reduced image that becomes brighter in the vicinity of the optical axis C. However, in the image reading device A, the illuminance in the vicinity of each optical axis C in the reading target area S is lower than that in the other parts. Therefore, by such a total action, it is possible to prevent a phenomenon that the inverted reduced image formed on each light receiving element 6 becomes brighter in the vicinity of the optical axis C. As a result, in this image reading device A,
It is possible to obtain a reduced read image of good image quality faithful to the density of the image of the read target area S.

FIG. 7 is a sectional view showing another example of the light guide unit.

In the light guide unit Ua shown in FIG. 7, an opaque or translucent light-shielding member 55 or a light-shielding material having a low light transmittance is provided on a light incident surface 50A of the second transparent member 5 at a predetermined distance. Are provided at multiple locations. According to such a configuration, when light travels from the light emitting surface 40B of the first transparent member 4 toward the second transparent member 5, many portions are provided in the portion where the light shielding member 55 is provided. Light can be prevented from traveling into the second transparent member 5. Therefore, even with such a configuration, it is possible to set the light emitted from the light emitting surface 50B of the second transparent member 5 to a desired light amount distribution. If the light transmittance of the light shielding member 55 is changed steplessly, the amount of light transmitted through the part or the amount of light blocked by the part can be changed steplessly, so that the illuminance is not It is possible to prevent a sudden change from occurring.

As described above, in the present invention, the light amount distribution may be changed by providing the light-shielding member or the light-shielding substance on the light incident surface of the second transparent member. Further, the light-shielding member or the light-shielding substance may be provided on the light emitting surface of the first transparent member, or may be provided between the first transparent member and the second transparent member. . However, if the light amount distribution is changed by forming the light incident surface 50A of the second transparent member 5 in an uneven shape as in the light guide unit U described above,
There is no need to provide a light-blocking member or the like on a transparent member,
The advantage is obtained that each transparent member constituting the light guide unit can be easily and inexpensively manufactured only by the resin molding process.

The specific configuration of the present invention is not limited to the above-described embodiment, and various design changes can be made.

In the above-described embodiment, an example in which the image reading apparatus is configured to take a reduced copy of a whiteboard has been described as an example. However, the present invention is not limited to this. Can be configured as Therefore, for example, when an original image is read at the same size, the image forming lens is configured by combining a plurality of selfoc lenses capable of obtaining an erect equal size image, a plurality of convex lenses, and the like. A combination lens may be used. When forming an original image on multiple light receiving elements at the same magnification,
Unlike the case where a reduced image of a document is formed using a convex lens, the phenomenon that the optical axis of the lens becomes brighter than other portions due to the characteristics of the lens does not occur. Therefore, in such a case, it is not necessary to provide the light amount distribution changing means, and the light guide unit may be formed as a simple planar light emitting surface of the second transparent member. Of course, by changing the uneven shape of the light emitting surface of the second transparent member to a shape different from the shape of the above-described embodiment,
It is also possible to uniformly set the illuminance at various points in the reading target area.

Further, in the above-described embodiment, the entirety or substantially the entirety of the light incident surface and the light emitting surface of the first transparent member is a convex curved surface, but the present invention is not limited to this. In the present invention, at least one of the light entrance surface and the light exit surface of the first transparent member may be a convex curved surface. Further, as is apparent from the contents described with reference to FIG. 6, although the convex curved surface formed on the first transparent member is preferably formed as wide as possible, as shown in FIG. Only a part of the light incidence surface or light emission surface of the transparent member may be a convex curved surface.

The first transparent member and the second transparent member referred to in the present invention
Are not necessarily required to be transparent in their entire appearance. For example, a region other than the light entrance surface and the light exit surface is covered with an opaque member or substance, so that a part thereof may be opaque. Further, the light guiding unit according to the present invention has a configuration in which, in addition to the first transparent member and the second transparent member, another transparent member (such as a third transparent member) separate from them is added. It can also be. Further, in the present invention, the light source device may be configured to use, for example, a cold-cathode tube having a light-emitting surface extending linearly, instead of a device having a plurality of LED light sources.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of an image reading apparatus according to the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along the line III-III of FIG. 1;

FIG. 4 is a partially sectional perspective view showing an example of a first transparent member.

FIG. 5A is a front view illustrating an example of a second transparent member, and FIG. 5B is a right side view thereof.

FIG. 6 is an explanatory view of a main part showing another example of the first transparent member.

FIG. 7 is a cross-sectional view showing another example of the light guide unit.

[Explanation of symbols]

 Reference Signs List A image reading device S reading target area C optical axis (of convex lens) 1 case 4 first transparent member 5 second transparent member 6 light receiving element 8 light source device 20 convex lens (lens) 40A light incident surface (first transparent member) 40B Light emitting surface (of first transparent member) 50A Light incident surface (of second transparent member) 50B Light emitting surface (of second transparent member) 53 Concave curved surface portion 54 Convex curved surface portion 80 LED light source

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/04 101 G06F 15/64 320F 320C (72) Inventor Norihiro Imamura 21-Mizozakicho, Saiin, Ukyo-ku, Kyoto ROHM F term within the company (reference) QA12 XA01 XA02

Claims (9)

[Claims] 1. A light source device, light guide means for guiding light emitted from the light source device to a line-shaped read target area, and an image of the read target area formed on a plurality of light receiving elements. An image reading device comprising: a plurality of lenses, wherein the light guide unit has a light incident surface that receives light from the light source device and a light exit surface that faces the light incident surface, and A first transparent member having at least one of the light incident surface and the light emission surface formed as a convex curved surface extending in the longitudinal direction of the read target area; and a first transparent member separate from the first transparent member. Formed and the first
An image reading apparatus, comprising: a second transparent member provided to guide light emitted from the light emission surface of the transparent member to the reading target area. 2. The image reading device according to claim 1, wherein each of a light incident surface and a light exit surface of the first transparent member is the convex curved surface. 3. Each of said lenses forms a reduced image of said read target area on said plurality of light receiving elements, and said first transparent member and said second transparent member are In the reading target area, the light received by the first transparent member from the light source device can be set so that the illuminance of a portion far from the optical axis of each lens can be higher than the illuminance of a portion near each optical axis. 3. The image reading device according to claim 1, wherein the image reading device guides the light to the reading target region with a different light amount distribution. 4. The second transparent member has a light incident surface facing the light emitting surface of the first transparent member, and a light emitting surface facing the read target area, and At least one of the light incident surface of the second transparent member and the light emitting surface of the first transparent member, or between them,
4. The light amount distribution changing unit according to claim 3, further comprising a light amount distribution changing unit for making the light amount distribution of the light traveling in the second transparent member different from the light amount distribution of the light traveling in the first transparent member. Image reading device. 5. The light amount distribution changing means includes a plurality of concave curved surface portions and a plurality of convex portions provided alternately on the light incident surface such that the light incident surface of the second transparent member is an uneven surface. The image reading device according to claim 4, wherein the image reading device is a curved surface portion. 6. The light source device according to claim 1, wherein a plurality of LED light sources are arranged in a row at an interval, and each of the LED light sources is arranged in a region to be read from an optical axis position of each of the lenses. The image reading device according to claim 3, wherein the image reading device is offset in a longitudinal direction of the image reading device. 7. The image reading apparatus according to claim 1, wherein said first transparent member and said second transparent member are formed such that a part thereof is fitted to each other. . 8. A case in which each of the light source device, the lenses, the light receiving elements, the first transparent member, and the second transparent member is incorporated, and the second transparent member is provided. The image reading device according to claim 1, wherein a portion of the light reading surface protrudes outward from the case. 9. A light guiding unit comprising a first transparent member and a second transparent member formed separately from each other, wherein the first transparent member has a plurality of side surfaces extending in a predetermined direction. As having a light incident surface for receiving external light and a light exit surface facing the light incident surface, at least one of the light incident surface and the light exit surface has a whole or a part thereof. And the second transparent member has a plurality of side surfaces extending in a predetermined direction, the light being emitted from the light emitting surface of the first transparent member. A light incident surface for receiving light, and a light exit surface for emitting light that has traveled into the second transparent member from the light incident surface to the outside. unit.