JP2008078855A - Light guide, lighting system, reading device, and image processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light guide which can emit the light from an incident plane through a projection plane efficiently. <P>SOLUTION: The light guide countering an incident plane and a projection plane comprises: a first inner plane arranged so as to incline; a second inner plane arranged so as to be directed reversely to the first inner plane; and a prism which leads light from the incident plane to the projection plane. The angle of gradient to the projection plane of the first inner plane is smaller than the angle of gradient to the projection plane of the second inner plane. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light guide, an illumination device, a reading device, and an image processing device.

In an image processing apparatus such as a facsimile, a copying machine, and a scanner apparatus, an original is illuminated in an elongated illumination area using an illuminating device provided with a rod-shaped light guide. The following patent document discloses an example of a technique related to a rod-shaped light guide.
Japanese Patent No. 2693098 Japanese Patent No. 3176346

  In the light guide, it is desired that light incident from the incident surface can be emitted from the emission surface with high intensity. In the light guide, when the light from the incident surface is guided to the emission surface via the prism, the intensity of the light emitted from the emission surface may be lowered depending on the shape of the prism.

  This invention is made | formed in view of the said situation, Comprising: It aims at providing the light guide which can inject | emit the light from an entrance plane efficiently from an exit surface. It is another object of the present invention to provide an illuminating device that can satisfactorily illuminate an object such as a document using a light guide that can emit light efficiently, a reading device including the illuminating device, and an image processing apparatus.

  In order to solve the above problems, the present invention adopts the following configuration.

  According to the first aspect of the present invention, there is provided a rod-shaped light guide that emits light from an incident surface from an exit surface extending in a predetermined direction so as to be opposed to and inclined with respect to the incident surface and the exit surface. A first inner surface disposed; and a second inner surface disposed so as to face the first inner surface; and a prism that guides light from the incident surface to the exit surface. A light guide having a smaller inclination angle with respect to the emission surface than the inclination angle of the second inner surface with respect to the emission surface is provided.

  According to the first aspect of the present invention, the inclination angle of the first inner surface of the prism disposed so as to face the entrance surface and the exit surface with respect to the exit surface is disposed so as to face the first inner surface. Since the inclination angle of the two inner surfaces with respect to the emission surface is smaller, the first inner surface can be enlarged in a predetermined space. The first inner surface is irradiated with light from the incident surface, but the second inner surface is hardly irradiated with light from the incident surface. By increasing the first inner surface, the light from the incident surface is It is efficiently supplied to the exit surface via the inner surface. Therefore, the light guide can emit light incident from the incident surface from the exit surface with high intensity, and can efficiently emit light from the incident surface from the exit surface.

  Here, the inclination angle of the first inner surface and the second inner surface includes an angle formed with the exit surface substantially parallel to the predetermined axis along the predetermined direction.

  In the light guide body of the above aspect, a configuration in which the inclination angle of the second inner surface is approximately 90 degrees can be employed.

  According to this, the first inner surface can be made sufficiently large, and light from the incident surface can be guided to the exit surface with high efficiency.

  In the light guide of the above aspect, a configuration in which a plurality of the prisms are provided in the predetermined direction, and an inclination angle of the second inner surface of the prism changes according to a position in the predetermined direction can be employed.

  According to this, light in a desired state can be emitted from the emission surface.

  In the light guide body according to the aspect described above, a configuration in which the inclination angle of the second inner surface of each of the plurality of prisms increases as the distance from the incident surface increases.

  According to this, the illuminance distribution of the light emitted from the emission surface in the predetermined direction can be made uniform.

  The light guide of the said aspect WHEREIN: The structure by which the inclination angle of the said 2nd inner surface of each of these prisms is set at random regarding the said predetermined direction is employable.

  According to this, the light emitted from the emission surface is diffused, and by irradiating the light with the object, it is possible to suppress the occurrence of defects such as the formation of a light stripe pattern on the object.

  In the light guide body of the above aspect, a configuration in which a curved surface is formed between the first inner surface of the first prism and the second inner surface of the second prism adjacent in the predetermined direction can be employed.

  According to this, since the manufacturing accuracy when forming the prism can be made relatively rough, the manufacturing process can be facilitated.

  In the light guide body of the above aspect, a configuration that becomes narrower from the incident surface toward the opposite side to the incident surface can be adopted.

  According to this, the illuminance distribution of the light emitted from the emission surface in the predetermined direction can be made uniform.

  According to a second aspect of the present invention, there is provided a light guide body according to the above aspect and a light source device that irradiates light on an incident surface of the light guide body, and an object using light emitted from an emission surface of the light guide body. A lighting device is provided for illuminating.

  According to the second aspect of the present invention, it is possible to satisfactorily illuminate an object such as a document using a light guide that can emit light efficiently.

  In the illumination device of the above aspect, a configuration having a bent light guide member that connects the light source device and the incident surface of the light guide can be employed.

  According to this, the freedom degree of arrangement | positioning of a light source device is improved.

  According to a third aspect of the present invention, there is provided a reading apparatus including the illumination device according to the above aspect and an optical device that reads an image of an object illuminated with light from the illumination device.

  According to the third aspect of the present invention, an object such as a document can be illuminated well, and an image of the illuminated object can be satisfactorily read.

  In the reading device of the above aspect, the optical device may include a configuration including an optical system that collects light from the object, and a photoelectric conversion element that receives light via the optical system.

  According to this, the light from an object can be favorably guided to the photoelectric conversion element via the optical system.

  According to a fourth aspect of the present invention, there is provided an image processing apparatus comprising: the reading apparatus according to the above aspect; and a processing apparatus that processes image information of the object read by the reading apparatus.

  According to the fourth aspect of the present invention, it is possible to smoothly process an image of an object that is satisfactorily read by the reading device.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, an XYZ orthogonal coordinate system is set, and the positional relationship of each member will be described with reference to this XYZ orthogonal coordinate system. The predetermined direction in the horizontal plane is the X-axis direction, the direction orthogonal to the X-axis direction in the horizontal plane is the Y-axis direction, and the direction orthogonal to each of the X-axis direction and the Y-axis direction (that is, the vertical direction) is the Z-axis direction. To do. Furthermore, the rotation directions around the X, Y, and Z axes are the θX, θY, and θZ directions, respectively.

<First Embodiment>
A first embodiment will be described. FIG. 1 is a schematic configuration diagram illustrating an illumination device 2 including a light guide 1 according to the first embodiment, and FIG. 2 is an enlarged view of a part of the light guide 1. 1 and 2, the illumination device 2 includes a light guide 1 and a light source device 4 that irradiates light to the incident surface 3 of the light guide 1.

  The light source device 4 includes LED light sources of three primary colors (red, green, and blue). In the present embodiment, the light source device 4 lights the LED light sources of the three primary colors in a time-sharing manner, but the light source device also includes any single color light source (red, green, blue, white, yellow).

  The light guide 1 is formed of, for example, a material having translucency, such as acrylic resin, and emits light incident on the incident surface 3 on which light is incident and propagated through the interior. And an exit surface 5. The light guide 1 is formed in a rod shape having a predetermined direction as a longitudinal direction, and has an emission surface 5 extending in the predetermined direction. In the present embodiment, the emission surface 5 is formed so as to extend in the X-axis direction in the drawing. The incident surface 3 is disposed so as to intersect with the exit surface 5, and in the present embodiment, is disposed on the end surface on the −X side in the drawing.

  Light incident from the incident surface 3 is emitted from the emission surface 5 through the inside of the light guide 1. The illumination device 2 illuminates the illuminated surface 6 of the object with light emitted from the emission surface 5 of the light guide 1. In this embodiment, the illuminating device 2 illuminates the illuminated surface 6 with a linear (slit-shaped) illumination region that is elongated in the X-axis direction.

  In the present embodiment, a reflection surface 8 that reflects light propagated through the light guide 1 is disposed on the end surface 7 opposite to the incident surface 3. In the present embodiment, a reflecting member 9 having a reflecting surface 8 different from the light guide 1 is disposed so as to face the reflecting surface 8 and the end surface 7 of the light guide 1. Note that a metal such as aluminum is vapor-deposited on the reflection surface 8 of the reflection member 9, thereby giving a function of reflecting light. In addition, you may provide the function which reflects light to the end surface 7 by vapor-depositing metals, such as aluminum, to the end surface 7 of the light guide 1, or apply | coating the material which has the function to reflect light.

  The light guide 1 includes a first inner surface 11 disposed so as to be inclined and opposed to the incident surface 3 and the exit surface 5, and a second inner surface 12 disposed so as to face the first inner surface 11. A prism 10 is provided. The first inner surface 11 is disposed so as to face the incident surface 3, and is inclined to the opposite side (end surface 7 side) with respect to the incident surface 3. The second inner surface 12 is disposed so as to face the side opposite to the incident surface 3 (the end surface 7 side). Each of the first inner surface 11 and the second inner surface 12 functions as a reflecting surface that reflects incident light, and the prism 10 having the first inner surface 11 and the second inner surface 12 receives the light from the incident surface 3 as the first. At least one of the inner surface 11 and the second inner surface 12 is reflected and guided to the exit surface 5.

  Plural prisms 10 having the first inner surface 11 and the second inner surface 12 are provided in the longitudinal direction (X-axis direction) of the exit surface 5. In other words, the light guide 1 of the present embodiment has a sawtooth reflection surface formed by a plurality of prisms 10. The prism 10 is disposed at a position facing the exit surface 5. In the present embodiment, the exit surface 5 is disposed on the + Z side surface of the light guide 1 in the drawing, and the prism 10 including the first inner surface 11 and the second inner surface 12 is the −Z side of the light guide 5. It is arranged on the surface.

  In the present embodiment, the inclination angle θ1 of the first inner surface 11 is smaller than the inclination angle θ2 of the second inner surface 12. Note that the inclination angle θ1 of the first inner surface 11 and the inclination angle θ2 of the second inner surface 12 are parallel to the exit surface 5 and are formed with the X axis along the longitudinal direction of the exit surface 5 (arrangement direction of the prisms 10). It is. In the following description, the inclination angles θ1 and θ2 of the first and second inner surfaces 11 and 12 will be described using the X axis substantially parallel to the longitudinal direction of the exit surface 5 (arrangement direction of the prisms 10) as a reference axis. .

  The inclination angle θ1 of the first inner surface 11 is determined by the refractive index of the light guide 1 (for example, acrylic resin) and the refractive index of an external medium (for example, air) as disclosed in Japanese Patent No. 2693098, for example. The optimum value is set according to the critical angle to be set, for example, 25 ° to 40 °. In the present embodiment, the inclination angle θ1 of the first inner surface 11 is set to 35 °.

  The inclination angle θ2 of the second inner surface 12 is larger than the inclination angle θ1 of the first inner surface 11, and is set to 90 ° in the present embodiment.

  The first inner surface 11 and the second inner surface 12 of the prism 10 are integrally formed with the light guide 1. Further, the first inner surface 11 and the second inner surface 12 can be formed by a predetermined processing method such as cutting. Alternatively, a member having a plurality of prisms 10 may be prepared separately, and the other member may be bonded to the side surface of the light guide 1 by an adhesive, ultrasonic bonding, or the like. Further, a metal such as aluminum or silver may be deposited on the first inner surface 11 and the second inner surface 12 to enhance the function of reflecting light.

  Next, operation | movement of the illuminating device 2 is demonstrated. Light emitted from the light source device 4 is applied to the incident surface 3 of the light guide 1. Light that has entered the light guide 1 from the incident surface 3 propagates while being repeatedly reflected inside the light guide 1.

  At least a part of the light incident on the inside of the light guide 1 from the incident surface 3 enters the first inner surface 11, is reflected by the first inner surface 11, and is guided to the exit surface 5. The light guided to the exit surface 5 exits from the exit surface 5 and illuminates the illuminated surface 6 of the object.

  That is, the light from the light source device 4 enters the first inner surface 11 of the prism 10 arranged in the X-axis direction, is reflected by the first inner surface 11, and is extracted outside the light guide 1.

  On the other hand, the second inner surface 12 is disposed so as to face the side opposite to the incident surface 3, and the light irradiated on the second inner surface 12 among the light incident on the light guide 1 from the incident surface 3. There are few ingredients. In addition, at least a part of the light incident on the inside of the light guide 1 from the incident surface 3 may propagate to the end surface 7 of the light guide 1, be reflected by the reflecting surface 8, and enter the second inner surface 12. However, since there is a possibility that the light is not reflected by the reflecting surface 8 and is emitted to the outside, the light component incident on the second inner surface 12 from the reflecting surface 8 is considered to be small. That is, most of the function of guiding the light from the incident surface 3 to the exit surface 5 of the prism 10 is performed by the first inner surface 11, and the second inner surface 12 transmits the light from the incident surface 3 to the exit surface 5. Little contribution to guiding.

  Therefore, in order to increase the light use efficiency of the light guide 1 (light extraction efficiency from the exit surface 5), it is effective to increase the total area of the first inner surface 11 facing the entrance surface 3. In the present embodiment, the inclination angle θ2 of the first inner surface 11 is set to an optimum value (for example, 25 ° to 40 °) by making the inclination angle θ2 of the second inner surface 12 larger than the inclination angle θ1 of the first inner surface 11. ), The total area of the first inner surface 11 can be increased.

  FIG. 3 is a schematic diagram showing a light guide 1R as a comparative example. As shown in FIG. 3, when the inclination angle θ1R of the first inner surface 11R and the inclination angle θ2R of the second inner surface 12R are substantially the same, the number of the first inner surfaces 11R per unit length in the X-axis direction is as shown in FIG. The number of the first inner surfaces 11 in the light guide 1 according to the present embodiment as shown is smaller. For example, in the range of the unit length AR in the X-axis direction, in the light guide 1 according to this embodiment as shown in FIG. 2, the number of the first inner surfaces 11 is eight, but as shown in FIG. In the light guide 1R in the comparative example, the number of the first inner surface 11R is four. That is, the light guide 1 of the present embodiment can increase the total area of the first inner surface 11 per unit length about twice as compared with the light guide 1R of the comparative example. Therefore, it is possible to guide light having an illuminance (light quantity) of about twice to the exit surface 5.

  2 and 3, the inclination angle θ1 (θ1R) of the first inner surface 11 (11R) is the same, and the height of the first inner surface 11 (11R) (Z axis of the first inner surface with respect to the reference axis). The direction height is the same. That is, in FIG.2 and FIG.3, each area of the 1st inner surface 11 (11R) is the same.

  Thus, in this embodiment, the number of the 1st inner surfaces 11 can be increased, maintaining the area (inclination angle, height) of one 1st inner surface 11 at a desired value. Therefore, the total area of the first inner surface 11 per unit length in the light guide 1 can be increased. Therefore, the light from the incident surface 3 can be favorably reflected and efficiently guided to the exit surface 5.

  FIG. 4 shows the light emitted from the emission surfaces 5 and 5R by the light guide 1 according to this embodiment as shown in FIG. 2 and the light guide 1R according to the comparative example as shown in FIG. It is a figure which shows the result of having measured illuminance (luminance). The horizontal axis in FIG. 4 indicates the position of the emission surfaces 5 and 5R in the X-axis direction, and the vertical axis indicates the illuminance (luminance) of the light emitted from each position of the emission surfaces 5 and 5R in the X-axis direction. In FIG. 4, a line L1 indicates an illuminance distribution (luminance distribution) of light obtained by the light guide 1 according to the present embodiment, and a line L2 indicates an illuminance distribution of light obtained by the light guide 1R according to the comparative example. (Luminance distribution) is shown. In the experiment, light having the same intensity is irradiated onto each of the incident surface 3 of the light guide 1 according to the present embodiment and the incident surface of the light guide 1R according to the comparative example, and is emitted from the emission surfaces 5 and 5R. The illuminance (luminance) of light was measured at each of a plurality of positions in the X-axis direction. As can be seen from FIG. 4, the light guide 1 according to the present embodiment can emit light having an illuminance (luminance) approximately twice that of the light guide 1 </ b> R according to the comparative example. That is, the utilization efficiency of the light guide 1 according to the present embodiment is about twice that of the light guide 1R according to the comparative example, and the utilization efficiency is improved.

  5 and 6 irradiate the irradiated surface 6 using each of the illumination device 2 including the light guide 1 according to the present embodiment and the illumination device 2R including the light guide 1R according to the comparative example. It is a figure which shows the experimental result which measured the reading time when the image of the to-be-irradiated surface 6 was read with the image reader containing photoelectric conversion elements, such as CCD. FIG. 5 is a diagram showing a relationship between light components emitted from each of the three primary color (red, green, and blue) LED light sources of the light source device 4 and a reading time corresponding to the image reading device (CCD). FIG. 6 is a diagram illustrating average values of reading times corresponding to the respective light components of the three primary colors. In this experiment, the light irradiation conditions (irradiation time and illuminance) on the respective incident surfaces of the light guides 1 and 1R by the light source device (LED) are the same.

  Here, in the image reading apparatus, the optimum amount of light (exposure amount) applied to the CCD is predetermined according to the characteristics of the CCD, such as light storage sensitivity. Therefore, the reading time can be shortened by increasing the illuminance of the light incident on the CCD (the brightness of the light emitted from the exit surface).

  As shown in FIG. 5, with respect to each of the light components of the three primary colors (red, green, and blue), the line when the illumination device 2 including the light guide 1 according to the present embodiment indicated by the line L3 is used is a line. It can be seen that the reading time by the image reading device (CCD) can be shortened as compared with the case where the illumination device 2R including the light guide 1R according to the comparative example indicated by L4 is used. In addition, as shown in FIG. 6, the average value of the reading times corresponding to the respective light components of the three primary colors is also a comparative example when the illumination device 2 including the light guide 1 according to the present embodiment is used. It can be seen that the illumination device 2R including the light guide 1R can be shortened as compared with the case where the illumination device 2R is used. That is, the light from the incident surface 3 is better when the illumination device 2 including the light guide 1 according to the present embodiment is used than when the illumination device 2R including the light guide 1R according to the comparative example is used. Can be ejected from the ejection surface 5 with high utilization efficiency. As described above, the reading time is shortened when the illumination device 2 including the light guide 1 according to the present embodiment is used as compared with the illumination device 2R including the light guide 1R according to the comparative example. Processing efficiency can be improved.

  As described above, the inclination angle θ1 of the first inner surface 11 of the prism 10 disposed so as to face the incident surface 3 is set to the second inner surface 12 disposed so as to face the end surface 7 side opposite to the incident surface 3. Therefore, the total area of the first inner surface 11 can be increased in a limited space. As described above, the first inner surface 11 is irradiated with the light from the incident surface 3, but the second inner surface 12 is hardly irradiated with the light from the incident surface 3, so that the first inner surface 11 is enlarged. The light from the incident surface 3 can be efficiently supplied to the exit surface 5 via the first inner surface 11. Therefore, the light guide 1 can emit light incident from the incident surface 3 from the exit surface with high intensity.

<Second Embodiment>
Next, a second embodiment will be described. In the following description, the same or equivalent components as those of the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

  7 and 8 are enlarged views of a part of the light guide 1 according to the second embodiment. As shown in FIGS. 7 and 8, the inclination angle θ2 of the second inner surface 12 does not have to be 90 °, and can be arbitrarily set within a range larger than the inclination angle θ1 of the first inner surface 11. In FIG. 7, the inclination angle θ2 of the second inner surface 12 is smaller than 90 °, and in FIG. 8, the inclination angle θ2 of the second inner surface 12 is set larger than 90 °. By doing so, the light use efficiency can be increased as in the first embodiment.

<Third Embodiment>
Next, a third embodiment will be described. FIG. 9 is a schematic diagram illustrating the illumination device 2 including the light guide 1 according to the third embodiment. The characteristic part of the third embodiment is that the inclination angle θ2 of the second inner surface 12 of the prism 10 changes according to the position of the prism 10 in the arrangement direction (X-axis direction).

  As shown in FIG. 9, in the light guide 1 according to this embodiment, the inclination angle θ <b> 2 of the second inner surface 12 of the prism 10 changes according to the position of the prism 10 in the arrangement direction (X-axis direction). . In the present embodiment, the inclination angle θ2 of the second inner surface 12 of each of the plurality of prisms 10 increases as the distance from the incident surface 3 increases. For example, the inclination angle θ2 of the second inner surface 12 closest to the incident surface 3 is substantially the same as the inclination angle θ1 (for example, 35 °) of the first inner surface 11 and the inclination angle θ2 of the second inner surface 12 closest to the end surface 7. Is, for example, 100 °, and the inclination angle θ2 of the plurality of second inner surfaces 12 therebetween gradually increases from the incident surface 3 toward the end surface 7. On the other hand, the inclination angle θ1 of the first inner surface 11 of each of the plurality of prisms 10 is substantially constant (for example, 35 °).

  Light emitted from the light source device 4 and incident on the incident surface 3 of the light guide 1 propagates while being repeatedly reflected inside the light guide 1, but as the light propagates, the illuminance of the light decreases. Therefore, the illuminance of light incident on the first inner surface 11 also decreases as the distance from the incident surface 3 increases. Then, the illuminance of light emitted from the emission surface 5 at a position away from the incident surface 3 is reduced, and the illuminance of light emitted from the emission surface 5 is distributed. That is, the illuminance in the X-axis direction of the light emitted from the emission surface 5 becomes nonuniform.

  In the present embodiment, the inclination angle θ2 of the second inner surface 12 is gradually increased as the distance from the incident surface 3 is increased while the size (inclination angle, height) of each of the plurality of first inner surfaces 11 is constant. Therefore, the reflection efficiency of the prism 10 at a position away from the incident surface 3 can be higher than the reflection efficiency of the prism 10 at a position close to the incident surface 3. Therefore, the illuminance of light emitted from the emission surface 5 in the X-axis direction can be made uniform.

<Fourth embodiment>
Next, a fourth embodiment will be described. FIG. 10 is a schematic view showing an illumination device including a light guide according to the fourth embodiment. The characteristic part of the fourth embodiment is that the inclination angle θ2 of the second inner surface 12 of each of the plurality of prisms 10 is set randomly with respect to the arrangement direction (X-axis direction) of the prisms 10.

  As shown in FIG. 10, in the light guide 1 according to this embodiment, the inclination angle θ2 of the second inner surface 12 of the prism 10 changes according to the position of the prism 10 in the arrangement direction (X-axis direction). . In the present embodiment, the inclination angle θ2 of the second inner surface 12 of each of the plurality of prisms 10 is set at random with respect to the arrangement direction (X-axis direction) of the prisms 10. On the other hand, the inclination angle θ1 of the first inner surface 11 of each of the plurality of prisms is substantially constant (for example, 35 °).

  The light guide 1 of the present embodiment can diffuse light emitted from the emission surface 5. If the inclination angle θ2 of the second inner surface 12 is constant according to each of a plurality of positions in the X-axis direction, a light stripe pattern may occur on the irradiated surface 6. According to the present embodiment, a light stripe pattern is formed on, for example, the irradiated surface 6 by diffusing the light emitted from the emission surface 5 by randomly setting the inclination angle θ2 of the second inner surface 12 with respect to the X-axis direction. It is possible to suppress the occurrence of defects such as

<Fifth Embodiment>
Next, a fifth embodiment will be described. FIG. 11 is a schematic diagram showing an illumination device 2 including the light guide 1 according to the fifth embodiment. A characteristic part of the fifth embodiment is that the space between the first inner surface 11 of the first prism 10A and the second inner surface 12 of the second prism 10B adjacent to each other in the arrangement direction (X-axis direction) of the prisms 10 is It is a point that is curved.

  As shown in FIG. 11, in the present embodiment, between the first inner surface 11 of the first prism 10A and the second inner surface 12 of the second prism 10B adjacent to each other in the arrangement direction (X-axis direction) of the prisms 10. Is curved. In the present embodiment, the shape between the first inner surface 11 of the first prism 10A and the second inner surface 12 of the second prism 10B in the XZ plane including the arrangement direction (X-axis direction) of the prisms 10 is a circle. It is arcuate.

  According to this, since the manufacturing accuracy when forming the prism 10 can be made relatively rough, the manufacturing process can be facilitated. For example, even when the light guide 1 including the prism 10 is manufactured using a mold or the like, the accuracy of the mold can be made relatively rough. In the present embodiment, since the inclination angle θ2 of the second inner surface 12 is large and the apex angle of one prism 10 is small, the first inner surface 11 of the first prism 10A and the second inner surface 12 of the second prism 10B are During this period, it is difficult for light from the incident surface 3 to enter. Therefore, even if the shape between the first inner surface 11 of the first prism 10A and the second inner surface 12 of the second prism 10B is a curved surface, it is allowed. As described above, since the size (total area) of the first inner surface 11 is sufficiently increased by increasing the inclination angle θ2 of the second inner surface 12, the first inner surface of the first prism 10A is increased. There is no problem even if there is a portion where it is difficult for light to enter between 11 and the second inner surface 12 of the second prism 10B.

<Sixth Embodiment>
Next, a sixth embodiment will be described. FIG. 12 is a schematic diagram showing an illumination device 2 including the light guide 1 according to the sixth embodiment. A characteristic part of the sixth embodiment is that the thickness of the light guide 1 is reduced from the incident surface 3 toward the end surface 7 opposite to the incident surface 3.

  As shown in FIG. 12, in the present embodiment, the thickness of the light guide 1 becomes thinner from the incident surface 3 toward the end surface 7. The thickness of the light guide 1 is the size of the light guide 1 in the YZ plane perpendicular to the arrangement direction (X-axis direction) of the prisms 10. In FIG. 12, the prism 10 is not shown for easy viewing of the drawing.

  As described above, the light emitted from the light source device 4 and incident on the incident surface 3 of the light guide 1 propagates while being repeatedly reflected inside the light guide 1, but as the light propagates, the illuminance of the light Decrease. Therefore, the illuminance of light incident on the first inner surface 11 also decreases as the distance from the incident surface 3 increases. Then, the illuminance of light emitted from the emission surface 5 at a position away from the incident surface 3 is reduced, and the illuminance of light emitted from the emission surface 5 is distributed. That is, the illuminance in the X-axis direction of light emitted from the exit surface 5 becomes nonuniform.

  In the present embodiment, the light guide 1 is made thinner as the distance from the incident surface 3 increases. Thereby, the component of the light which injects into the 1st inner surface 11 of the position away from the entrance plane 3 among the light which propagates the inside of the light guide 1 can be increased. In other words, the probability that light is incident on the first inner surface 11 disposed at a position away from the incident surface 3 is greater than the probability that light is incident on the first inner surface 11 disposed near the incident surface 3. Can also be increased. Thereby, the illumination intensity of the light regarding the X-axis direction inject | emitted from the output surface 5 can be made uniform.

<Seventh embodiment>
Next, a seventh embodiment will be described. FIG. 13 is a schematic diagram illustrating the illumination device 2 including the light guide 1 according to the seventh embodiment. In FIG. 12, the illumination device 2 includes a bent light guide member 13 that connects the light source device 4 and the incident surface 3 of the light guide 1. The light emitted from the light source device 4 is incident on the incident surface 3 of the light guide 1 through the bent light guide member 13. Thus, by providing the light guide member 13, the degree of freedom of arrangement of the light source device 4 can be improved.

<Eighth Embodiment>
Next, an eighth embodiment will be described. In the present embodiment, a case where the illumination device 2 described in the first to seventh embodiments is mounted on an image processing apparatus 20 such as a facsimile, a copying machine, or a scanner will be described as an example.

  FIG. 14 is a schematic configuration diagram showing an image processing device 20 according to the eighth embodiment. In FIG. 14, an image processing device 20 includes an image reading device 30 that reads an image of a document surface 6 of a document, a signal processing device 40 that processes image information of the document surface 6 read by the image reading device 30, and image processing. And a control device 50 that controls the operation of the entire device 20. The image processing device 20 includes a housing 21 that houses at least the image reading device 30, the signal processing device 40, and the control device 50, and a document table 22 on which a document can be placed. The document table 22 is a plate-like member made of, for example, a transparent glass material. In the present embodiment, the upper surface (mounting surface) of the document table 22 facing the document surface 6 of the document that is the irradiated surface is substantially parallel to the XY plane. The image reading device 30 acquires the image information of the document surface 6 of the document placed on the document table 22 via the document table 22.

  Further, an output device 60 that outputs image information read by the image reading device 30 is connected to the control device 50. The output device 60 includes, for example, a display device such as a liquid crystal display and a printer device. Image information read by the image reading device 30 is processed by the signal processing device 40 and then output to the control device 50. The control device 50 outputs the image information of the document processed by the signal processing device 40 using the output device 60.

  FIG. 15 is a perspective view schematically showing the image reading device 30. 14 and 15, the image reading device 30 includes an illumination device 2 that illuminates a document with illumination light, and an optical device 31 that reads an image of the document illuminated with illumination light from the illumination device 2. The image reading apparatus 30 of the present embodiment includes a contact image sensor (CIS: Contact Image Sensor).

  The illuminating device 2 includes a light guide 1 and a light source device 2 that irradiates the incident surface 3 of the light guide 1 with light. The light guide 1 has an emission surface 5 extending in the X-axis direction, and light incident from the incident surface 3 is emitted from the emission surface 5 through the inside of the light guide 1. The illumination device 2 illuminates the document surface 6 of the document with light emitted from the exit surface 5 of the light guide 1. The illumination device 2 illuminates the document surface 6 of the document placed on the document table 22 via the document table 22.

  The optical device 31 is a photoelectric system such as an optical system 32 that collects light from the original surface 6 illuminated by the illumination light of the illumination device 2, and a CCD (Charge Coupled Devices) or the like on which light is incident via the optical system 32. A sensor unit 35 including a conversion element 33. The sensor unit 35 has a substrate 34 that supports the photoelectric conversion element 33. In the present embodiment, a plurality of photoelectric conversion elements 33 are arranged in the X-axis direction. That is, in the present embodiment, the sensor unit 35 includes a line image sensor in which a plurality of photoelectric conversion elements 33 are arranged in a one-dimensional direction.

  Illumination light from the illumination device 2 is applied to the document surface 6 via the document table 22, and reflected light of the illumination light irradiated to the document surface 6 enters the optical system 32 via the document table 22. The optical system 32 has a plurality of optical elements 32 </ b> L, and these optical elements 32 </ b> L are arranged in the XY directions substantially parallel to the document surface 6. That is, the optical system 32 of the present embodiment includes a lens array in which a plurality of optical elements (lenses) 32L are arranged in a two-dimensional direction. In the present embodiment, the optical system 32 includes a plurality of erecting equal-magnification radial direction gradient index lenses, and the lenses 32L are arranged between two FRP plates 32B. . Further, the gap between the lenses 32L is filled with black resin. The optical system 32 of this embodiment includes an SLA (Selfoc Lens Array: registered trademark).

  The reflected light that is illuminated by the illumination device 2 and reflected by the document surface 6 of the document is condensed on the photoelectric conversion element 33 of the sensor unit 35 via the document table 22 and the optical system 32. Light from the document surface 6 via the optical system 32 enters the photoelectric conversion element 33 of the sensor unit 35, and the photoelectric change element 33 receives light from the document surface 6 via the optical system 32. The optical system 32 forms an image of the document surface 6 on the photoelectric conversion element 33, and the photoelectric conversion element 33 acquires an optical image (image) of the document surface 6. As described above, in this embodiment, the image reading device 30 acquires the image information of the document surface 6 placed on the document table 22 via the document table 22.

  According to the present embodiment, the document surface 6 can be favorably illuminated by the illumination device 2, and the image of the illuminated document surface 6 can be favorably read by the image reading device 30. Further, according to the present embodiment, the image on the document surface 6 can be read in a short reading time.

It is a schematic block diagram which shows the illuminating device provided with the light guide which concerns on 1st Embodiment. It is the figure which expanded a part of FIG. It is a figure which shows a comparative example. It is a figure which shows the result of the experiment conducted in order to compare the effect | action of the illuminating device of this embodiment, and the illuminating device of a comparative example. It is a figure which shows the result of the experiment conducted in order to compare the effect | action of the illuminating device of this embodiment, and the illuminating device of a comparative example. It is a figure which shows the result of the experiment conducted in order to compare the effect | action of the illuminating device of this embodiment, and the illuminating device of a comparative example. It is a figure which shows a part of light guide which concerns on 2nd Embodiment. It is a figure which shows a part of light guide which concerns on 2nd Embodiment. It is a schematic block diagram which shows the illuminating device provided with the light guide which concerns on 3rd Embodiment. It is a schematic block diagram which shows the illuminating device provided with the light guide which concerns on 4th Embodiment. It is a schematic block diagram which shows the illuminating device provided with the light guide which concerns on 5th Embodiment. It is a schematic block diagram which shows the illuminating device provided with the light guide which concerns on 6th Embodiment. It is a schematic block diagram which shows the illuminating device provided with the light guide which concerns on 7th Embodiment. It is a schematic block diagram which shows the image processing apparatus provided with the reader which concerns on 8th Embodiment. It is a perspective view which shows the illuminating device and reader which concern on 8th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Light guide, 2 ... Illuminating device, 3 ... Incident surface, 4 ... Light source device, 5 ... Ejection surface, 6 ... Irradiated surface (original surface), 7 ... End surface, 10 ... Prism, 11 ... 1st inner surface, DESCRIPTION OF SYMBOLS 12 ... 2nd inner surface, 13 ... Light guide member, 20 ... Image processing apparatus, 30 ... Reading apparatus, 40 ... Signal processing apparatus, 50 ... Control apparatus

Claims (12)

A rod-shaped light guide that emits light from an incident surface from an exit surface extending in a predetermined direction,
A first inner surface disposed to be inclined and opposed to the incident surface and the exit surface; and a second inner surface disposed to face away from the first inner surface; Comprising a prism for guiding light to the exit surface;
The light guide body wherein an inclination angle of the first inner surface with respect to the emission surface is smaller than an inclination angle of the second inner surface with respect to the emission surface.   The light guide according to claim 1, wherein an inclination angle of the second inner surface is approximately 90 degrees. A plurality of the prisms are provided in the predetermined direction,
The light guide according to claim 1 or 2, wherein an inclination angle of the second inner surface of the prism changes according to a position in the predetermined direction.   The light guide according to claim 3, wherein an inclination angle of the second inner surface of each of the plurality of prisms increases as the distance from the incident surface increases.   The light guide according to claim 3, wherein an inclination angle of the second inner surface of each of the plurality of prisms is set randomly with respect to the predetermined direction.   The light guide according to any one of claims 1 to 5, wherein a space between the first inner surface of the first prism and the second inner surface of the second prism adjacent to each other in the predetermined direction is a curved surface.   The light guide according to any one of claims 1 to 6, wherein the light guide becomes thinner from the incident surface toward a side opposite to the incident surface. The light guide according to any one of claims 1 to 7,
A light source device for irradiating light to the incident surface of the light guide,
An illumination device that illuminates an object with light emitted from an emission surface of the light guide.   The lighting device according to claim 8, further comprising a bent light guide member that connects the light source device and an incident surface of the light guide. The lighting device according to claim 8 or 9,
An optical device that reads an image of an object illuminated with light from the illumination device.   The reading device according to claim 10, wherein the optical device includes an optical system that condenses light from the object, and a photoelectric conversion element on which light is incident through the optical system. A reading device according to claim 10 or 11,
An image processing apparatus comprising: a processing device that processes image information of the object read by the reading device.

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