JP6157330B2 - Illumination device and image sensor - Google Patents

Description

  The present invention relates to an illuminating device that is mounted on a copying machine, a facsimile machine, a scanner, or the like and that irradiates an object to be irradiated such as a document, and an image sensor using the same.

  As a conventional document illumination device, a discharge tube such as a fluorescent tube or LED array illumination in which a large number of point light sources such as LEDs are arranged in an array is used. In addition, an illumination device having a configuration in which an LED light source is disposed at an end of a rod-shaped light guide, light is incident from the end face, and a region in which light is reflected in the long axis direction of the light guide is provided. .

  In the latter illuminating device, the illuminance characteristic in the vicinity of the LED light source, that is, the end of the light guide, and the illuminance characteristic in the center of the light guide are different. A factor that deteriorates the uniformity of the illuminance distribution is a deviation in the reflection angle within the light guide. When light that travels in the long axis direction while being totally reflected inside the light guide (guided light) reaches the reflection pattern provided on the side of the light guide with an arbitrary angle and spread, the light is guided by the reflection. The light is emitted outside the light guide and becomes illumination light. Since the emission angle of the illumination light depends on the reflection angle at the light guide reflection part, suppressing the reflection angle deviation at the light guide reflection part leads to improvement in the uniformity of the illuminance distribution.

  As a method for improving the uniformity of the illuminance distribution, for example, a method disclosed in Patent Document 1 can be cited. Patent Document 1 proposes a configuration in which the reflection patterns 4 are provided at equal intervals on the surface portion of the light guide 3 along the long axis direction of the light guide 3, as shown in FIG. The reflection pattern 4 has a cutout portion in which the width in the major axis direction gradually decreases as the distance from the surface portion of the light guide 3 is increased in the depth direction. A circular arc pattern having a constant radius of curvature from a predetermined position in the direction to the deep part of the light guide or an elliptical arc pattern having a constant curvature radius and a linear inclined pattern extending from the surface part of the light guide are continuously formed. . Then, the guided light regularly reflected by the reflection pattern 4 is emitted from the portion facing the reflection pattern 4 and irradiates the document surface. In such a configuration, light directly reflected by the arc shape of the notch is used, so that the light use efficiency is high and the reflection angle varies, so that illumination with a uniform illuminance distribution can be obtained.

JP 2012-74857 A

  For example, when reading an uneven reading object such as a book document, the document surface distance varies depending on the document reading position. In a copying machine or the like, a correction value for the amount of incident light is determined so that the white level of each pixel of the image sensor becomes equal at the position (reference position) where the document is in close contact with the cover glass. Therefore, the illuminance ratio (= illuminance after changing the document surface distance / illuminance at the reference position) when the document surface distance is changed with respect to the illuminance distribution in the long axis direction of the light guide at the reference position is the long axis direction. Is desired to be constant. If the distribution of the illuminance ratio in the major axis direction of the light guide is not constant, the white level of each pixel of the image sensor when the document surface distance changes cannot be made equal, and the quality of the acquired image is It will deteriorate.

  In the configuration proposed in Patent Document 1, as shown in FIG. 17, when the distance of the document surface changes, there is a problem that the illuminance ratio at the end of the light guide changes with respect to the center of the light guide. . There is a demand for miniaturization of an illuminating device in order to make the length in the long axis direction as short as possible. Therefore, since it is necessary to use the whole light guide as an illumination area, an illuminating device in which the illuminance ratio at the end of the light guide does not change with respect to the center is desired. Since the guided light propagating through the central portion of the light guide is totally reflected in the light guide in a random direction, the incident angle to the reflection pattern is also random, and the angle of the reflected light is also random with respect to the document surface. Become. Therefore, a uniform illuminance distribution is obtained, and the illuminance ratio in the major axis direction of the light guide does not change even if the document surface distance changes. On the other hand, at the end portion of the light guide, light emitted from the light source and incident on the light guide directly enters the reflection pattern without propagating through the light guide. The light that is directly incident on the reflection pattern from the light source is incident on the reflection pattern at a biased angle depending on the positional relationship with the light source, so that it is reflected in the biased direction and irradiates a certain point on the document surface. Therefore, when the document surface distance changes, the irradiation position in the major axis direction and the minor axis direction changes, and the shape of the illuminance distribution changes. Therefore, when the document surface distance changes, the illuminance ratio at the end portion changes with respect to the illuminance ratio at the central portion of the light guide.

  The present invention has been made to solve the above-described problems, and the illuminance ratio at the end of the light guide does not change much with respect to the center of the light guide even when the document surface distance changes. It is an object of the present invention to provide an illumination device that can acquire a high-quality image and an image sensor using the same.

In order to achieve the above object, the present invention comprises a light source,
A rod-shaped light guide that propagates while the light incident inside from the light source is reflected in the long axis direction;
A reflection pattern periodically provided along the major axis direction between one end and the other end of the light guide on the surface of the light guide;
In the process of light propagating through the light guide, light is applied to the reflection pattern from the inside of the light guide, and the light reflected by the reflection pattern is lined on the side facing the reflection pattern through the light guide. A lighting device for forming a light emitting region,
The reflective pattern has a protrusion that gradually decreases in width in the major axis direction as it is farther from the surface of the light guide.
A cross-sectional shape of the protrusion in the major axis direction is formed such that a plurality of curved portions are continuous, and is asymmetric with respect to a center line passing through the top of the protrusion.

  According to the present invention, the illuminance ratio at the edge of the light guide is changed even when the document surface distance is changed due to the asymmetrical cross-sectional shape of the protrusion in the major axis direction with respect to the center line passing through the top of the protrusion. It does not change much with respect to the central part of the light guide. As a result, it is possible to acquire a high-quality image.

1 is a configuration development view of an image sensor according to Embodiment 1 of the present invention. It is a partial expanded sectional view of the illuminating device by Embodiment 1 of this invention. It is explanatory drawing which shows the curvature shape formed in a reflective pattern. It is sectional drawing of the short axis direction of the light guide 3 explaining the shape of the reflective pattern 4 of the illuminating device by Embodiment 1 of this invention. It is explanatory drawing which shows an example of the arrangement | sequence of a reflection pattern. It is the elements on larger scale explaining the shape of the reflective pattern by Embodiment 1 of this invention. It is a partial enlarged view for demonstrating the reflectance about the various shapes of a reflective pattern. It is explanatory drawing about illuminance distribution when a document surface distance changes. It is the elements on larger scale explaining the function of the reflective pattern in the entrance plane vicinity of a light guide. It is a partial expanded sectional view explaining the basic composition of Embodiment 2 of this invention. It is the elements on larger scale explaining the arrangement density of a reflective pattern. It is a partial expanded sectional view explaining the basic composition of Embodiment 3 of this invention. It is the elements on larger scale explaining the arrangement | sequence of a reflection pattern. It is explanatory drawing about the array distribution of the reflective pattern of Embodiment 4 of this invention. It is explanatory drawing about the shape change of a reflective pattern. It is sectional drawing explaining the structure of the illuminating device proposed by patent document 1. FIG. It is explanatory drawing of operation | movement of the illuminating device proposed by patent document 1. FIG.

Embodiment 1 FIG.
FIG. 1 is a configuration development view of an image sensor according to Embodiment 1 of the present invention. In FIG. 1, a light source 1 is composed of a white light or RGB light emitting LED, for example, an LED composed of a resin LED-molded package LED or a bare chip, or a high-intensity light source such as an organic EL. A plurality of light emitting elements may be included. The light source 1 is installed on the substrate 2 and is supplied with power via a lead wire 2a such as a flexible cable.

  The light guide 3 is made of a transparent material such as acrylic resin or glass, has a rod-like shape along the major axis direction (X direction), and a cross section in the minor axis direction (Y direction) perpendicular to the major axis direction. The shape is provided with a curvature in part or all, and is configured by, for example, a circle, an ellipse, a polygon, or a combination thereof. One end surface of the light guide 3 is configured as an incident surface 3 a for introducing light from the light source 1 into the light guide 3. The light source 1 is installed in the vicinity of the incident surface 3a. The other end surface of the light guide 3 is configured as a reflection surface 3b for reflecting light propagating through the light guide 3 toward the inside again. On the reflection surface 3b, a reflection member 5, for example, a mirror surface member such as a mirror tape, a light scattering material such as a white resin, an optical reflection film, or the like is installed. On the surface of the light guide 3, projection-like reflection patterns 4 are periodically provided between one end and the other end of the light guide 3 along the long axis direction (X direction). The light guides 3 having such a configuration are installed in the vicinity of the optical axis of the reading optical system, preferably on both sides of the optical axis.

  As shown in FIG. 2, the holder 6 is a rectangular parallelepiped member having a hollow portion connectable to the end portion of the light guide 3, and has a function of fixing the relative position between the light guide 3 and the light source 1. . One end of the holder 6 holds the end portion of the light guide 3 including the incident surface 3 a, and the light source 1 is inserted into the hollow portion on the other surface of the holder 6 so as to face the incident surface 3 a. A substrate 2 is mounted.

  The transmissive body 7 is made of a plate-like transparent member as a cover glass, and has a function of allowing the passage of light and supporting the irradiated body 12 such as a document or banknote. The rod lens 8 functions as a reading optical system that focuses the reflected light from the irradiated body 12 and forms an optical image of the irradiated body 12. The sensor IC 9 is mounted on the sensor substrate 10 and functions as a light receiving element that converts an image formed by the rod lens 8 into an electric signal. The housing 11 has a function of housing and holding the light guide 3, the rod lens 8, the sensor substrate 10, and the like.

  Next, the operation of the image sensor will be described. The light emitted from the light source 1 is incident on the incident surface 3a, propagates through the light guide 3 toward the reflecting surface 3b, and then is reflected by the reflecting member 5 and propagates toward the incident surface 3a. . At this time, a part of the light incident on the reflection pattern 4 is reflected, a line-shaped emission region is formed on the side facing the reflection pattern 4, and the irradiated body 12 is irradiated through the transmission body 7. The reflected light from the irradiated body 12 is imaged by the rod lens 8 and converted into an image signal by the sensor IC 9.

  FIG. 2 is a partially enlarged cross-sectional view of the lighting apparatus according to Embodiment 1 of the present invention. The light source 1 is disposed facing the incident surface 3a of the light guide 3, and the distance between the light source 1 and the incident surface 3a is appropriately maintained by the holder 6. The light incident on the incident surface 3 a of the light guide 3 from the light source 1 propagates in the X direction while being totally reflected in the light guide, and a part of the light guided enters the reflection pattern 4 of the light guide 3. To do. The reflection pattern 4 is optically integrated with the light guide 3, and a part of the light reflected or transmitted by the reflection pattern 4 crosses the inside of the light guide 3 and is at a position facing the reflection pattern 4. The light is emitted from the light emitting portion 3c of the light guide 3 to irradiate the irradiated body 12. Further, the light that totally reflects inside the light guide 3 and reaches the reflecting surface 3b facing the incident surface 3a is reflected or scattered by the reflecting member 5 and propagates in the −X direction.

3A and 3B are explanatory views showing the curvature shape formed in the reflection pattern 4, FIG. 3A shows a general triangular asymmetric reflection pattern, and FIG. 3B shows a plurality of curved portions. A continuous asymmetric reflection pattern is shown. In the triangular reflection pattern, when light propagating from the + X direction is incident at the same incident angle, the reflection angles of the light beams reflected at different reflection positions are equal (θ ₁ = θ ₂ = θ ₃ ). On the other hand, as shown in FIG. 3B, in the reflection pattern 4 using a curvature shape in which a plurality of curved portions are continuous, regular reflection light in the curvature shape is used, so even if the incident angle to the reflection pattern is the same, The reflection angle varies depending on the reflection position (θ ₁ <θ ₂ <θ ₃ ). For this reason, the angle of the light beam incident on the irradiated body 12 varies, and the uniformity of the illuminance distribution can be improved.

  FIG. 4 is a cross-sectional view in the minor axis direction of the light guide 3 for explaining the shape of the reflection pattern 4 of the illumination device according to Embodiment 1 of the present invention. The width w in the minor axis direction of the reflective pattern 4 is uniform over the major axis direction of the light guide 3 and is, for example, w = 1 mm. The depth h of the reflection pattern 4 is the distance from the surface of the light guide 3 to the top of the reflection pattern, and for example, h = 60 μm. The light reflected by the reflection pattern 4 crosses the light guide 3 and is emitted from the emission part 3c, and illuminates the transmission body 7 and the irradiated body 12 from an oblique direction.

  FIG. 5A is a cross-sectional view showing an example of the arrangement of the reflection patterns 4. In an illuminating device used for an image sensor, uniformity of illuminance distribution in the long axis direction is desired. The light emitted from the light source 1 enters from the incident portion 3a of the light guide 3 and is reflected by the reflection pattern 4 sequentially through the emission portion 3c of the light guide 3 while being totally reflected along the major axis direction. Irradiate. At that time, when the distance d between the adjacent reflection patterns is equal, the illuminance on the side close to the light source 1 is large, and the illuminance decreases toward the + X direction (see the broken line in FIG. 5B). Therefore, the illuminance distribution in the major axis direction of the illumination light emitted from the emitting portion 3 c of the light guide 3 is changed by changing the interval d between the adjacent reflection patterns 4 with respect to the position in the major axis direction of the light guide 3. It can be made uniform (see the solid line in FIG. 5B). Here, a distance d between adjacent reflection patterns, for example, d = 200 μm in the vicinity of the light source 1 and d = 100 μm in the vicinity of the reflection surface 3b of the light guide 3, and inside the light guide, for example, as shown in FIG. As shown, the distance d is changed so that the illuminance distribution is uniform as a function of the position in the X direction.

  FIG. 6 is a partially enlarged view for explaining the shape of the reflection pattern according to the first embodiment of the present invention. The reflection pattern 4 is configured by periodically providing protrusions protruding in the depth direction on the surface of the light guide 3 along the long axis direction. The protrusion, which is a unit shape of the reflective pattern 4, has a shape in which the width in the major axis direction gradually decreases as the distance from the surface of the light guide 3 increases. The surface 4 a including the surface of the light guide 3 and the light guide It includes a surface 4b that includes the top of the protruding portion that protrudes toward the outside (-Z direction) of the body 3, and a surface 4a and an inclined surface 4c that connects the surface 4b.

  Further, the curvature radius of the curvature shape 4d (curved portion convex in the traveling direction of the light beam emitted from the light source) of the surface 4a rounded in the + X direction is R1, for example, R1 = 30 μm. Further, the curvature radius of the curvature shape 4e in the −X direction of the surface 4a (a curved portion convex in a direction opposite to the traveling direction of the light emitted from the light source) is R2, and R2 <R1, for example, R2 = 0 (acute angle) ). Further, the curvature radius of the curvature shape 4f in the −X direction and the curvature shape 4g in the + X direction from the top of the protrusion is R3, for example, R3 = 10 μm. Here, although the curvature radii of the curvature shapes 4f and 4g are described as the same R3, they may be different from each other. In this way, the left-right asymmetrical reflection pattern 4 in which the curvature radius R2 of the curvature shape 4e is smaller than the curvature radius R1 of the curvature shape 4d is referred to as a reflection pattern 41. Here, “asymmetric” means asymmetric with respect to a center line passing through the top of the protrusion in the Z direction.

  Next, the behavior of light inside the light guide 3 will be described. As shown in FIG. 6, the behavior of light inside the light guide 3 can be roughly classified into five. 1) First, the light ray A is a light ray that propagates inside the light guide 3 while being totally reflected by the surface of the light guide 3. The angle of the light beam that enters the light guide 3 from the light source 1 through the incident surface 3 a is designed to satisfy the total reflection condition on the surface of the light guide 3. 2) Next, the light beam B propagates through the light guide 3, then reflects off the reflective surface 3 b and propagates in the −X direction, enters the curvature shape 4 d of the reflective pattern 41, and is totally reflected and guided. It is a light beam that traverses the inside of the light body 3 and is emitted from the emission part 3 c facing the reflection pattern 41 and irradiated on the irradiated object 12. 3) The light ray C propagating through the light guide 3 is incident on the inclined portion 4c of the reflection pattern 41, refracts because the total reflection condition is not satisfied, and enters the adjacent reflection pattern 41 again, and has a curvature shape. It is a light beam that is totally reflected by 4 g, traverses the inside of the light guide 3, is emitted from the emission part 3 c facing the reflection pattern 41, and is irradiated on the irradiated object 12. 4) In addition, the light ray D propagating through the light guide 3 is incident on the inclined portion 4c of the reflection pattern 41, refracts because it does not satisfy the total reflection condition, and passes through the reflection pattern 41 adjacent a plurality of times. In this case, the light beam is transmitted through the light guide 3 again through the light guide 3 after being emitted from the emission portion 3 c or totally reflected on the surface of the light guide. 5) Finally, the light ray E is incident on the reflection pattern 41, is refracted without satisfying the total reflection condition, and is not incident on the adjacent reflection pattern 41 (loss light).

FIG. 7 is a partially enlarged view for explaining the reflectance R for various shapes of the reflection pattern 4. FIG. 7A shows a left-right asymmetric reflection pattern 41 in which the curvature radius R2 of the curvature shape 4e is an acute angle (R2 <R1). FIG. 7B shows a left-right asymmetric reflection pattern 43 in which the curvature radius R1 of the curvature shape 4d is an acute angle (R1 <R2). FIG. 7C shows a symmetrical reflection pattern 42 in which the curvature radius R2 of the curvature shape 4e and the curvature radius R1 of the curvature shape 4d are equal. Here, only light propagating from the −X direction (amount of light I _Left ) is considered, and the amount of light reflected by the reflection pattern 4 and applied to the irradiated object 12 is _defined as I _{Left_Out} . Then, Ra represents the efficiency (reflectance) of light reflected by one reflection pattern 41 and emitted to the outside of the light guide, Rb represents the reflectance of the reflection pattern 43, and Rc represents the reflectance of the reflection pattern 42.

  As shown in FIG. 7A, in the reflection pattern 41, the curvature shape 4e has an acute angle, so that the light propagating from the −X direction is incident on the reflection pattern 41 and then transmitted and refracted to the adjacent reflection pattern. Incident. That is, the reflectance Ra of the reflective pattern 41 is small.

  Next, as shown in FIG. 7B, since the curvature radius R2 of the curvature shape 4e is, for example, 30 μm, the reflection pattern 43 is reflected by the curvature shape 4e when light propagating from the −X direction is incident. And it radiates | emits from the output part 3c of a light guide. That is, the reflectance Rb of the reflective pattern 43 is larger than the reflectance Ra of the reflective pattern 41 having a sharp curvature 4e, and Ra <Rb.

  Further, the reflectivity Rc of the reflection pattern 42 shown in FIG. 7C is equivalent to the reflection pattern 43 because only the light propagating from the −X direction is considered now, and the reflection of the three reflection patterns. The relationship of the rate is Ra <Rb≈Rc. For example, Rb≈Rc = 2 × Ra is calculated by simulation.

FIG. 8 is an explanatory diagram of the illuminance distribution when the document surface distance changes. The amount of light propagating from the −X direction to the + X direction of the light guide 3 is I _Left , the amount of light irradiated to the irradiated body 12 is I _{Left_Out,} and the amount of light propagating from the + X direction is I _Left . _Right , the amount of light irradiated on the irradiated body 12 is I _{Right_Out} . That is, the amount of light I irradiated to the irradiated object 12 from one reflection pattern is I = I _{Left_Out} + I _{Right_Out} .

  In the central portion of the light guide 3, the light propagating from the −X direction of the light guide 3 and the light propagating from the + X direction are totally reflected inside the light guide 3 a plurality of times. There is no bias in the incident angle of the pattern 4, and the reflection angle is also random. Therefore, as shown in FIG. 8B, when the illuminance distribution when the document surface is at the reference position (position z = 0 in close contact with the transmission body 7) and the document surface distance change, for example, z = + 4 mm. The illumination distribution does not change.

However, in the vicinity of the incident surface 3 a of the light guide 3, the light propagating from the −X direction to the + X direction of the light guide 3 is emitted from the light source 1 from the incident surface 3 a, and the light guide 3. Since the light is directly incident on the reflection pattern 4 without being totally reflected on the surface, the incident angle to the reflection pattern is deviated depending on the positional relationship with the light source 1, and the angle of reflection and irradiation to the document surface is also deviated. . Therefore, the illuminance distribution when the document surface is at the reference position and the illuminance distribution when the distance is long are changed, and the illuminance ratio at the end of the light guide 3 is the center as shown in FIG. It will change with respect to the part. However, the light propagating from the + X direction is incident on the reflection pattern 4 because the light beam totally reflected several times on the surface of the light guide 3 is incident on the reflection pattern 4, and the reflection angle is also random. The illuminance distribution when the document surface is at the reference position and the illuminance distribution when the document surface distance changes do not change. That is, if the ratio of the light quantity I _{Left_Out} of the light propagating from the −X direction to the + X direction of the light guide in the total light quantity I irradiated to the irradiated body 12 can be reduced and the ratio of I _{Right_Out} can be increased, The illuminance ratio in the vicinity of the incident surface 3a of the light guide 3 (the ratio of the illuminance when the height of the irradiated body changes with respect to the illuminance when the irradiated body 12 is at the reference position) is the central portion of the light guide 3 An illumination device that does not change with respect to the illuminance ratio can be obtained.

FIG. 9 is a partially enlarged view for explaining the function of the reflection pattern 4 in the vicinity of the incident surface 3 a of the light guide 3. FIG. 9A shows a case where a symmetrical reflection pattern 42 is formed in the vicinity of the incident surface 3 a of the light guide 3. Of the light propagating from the −X direction, the light amount I _{Left_Out} of the light emitted to the outside of the light guide 3 is I _{Left_Out} = I _Left × Rc. On the other hand, of the light propagating from the + X direction, the light amount I _{Right_Out} of the light emitted to the outside of the light guide 3 is I _{Right_Out} = I _Right × Rc. That is, the ratio Pa of I _{Right_Out} to I _{Right_Out} is expressed by the following formula (1).

Next, FIG. 9B shows a case where a left-right asymmetric reflection pattern 41 is formed in the vicinity of the incident surface 3 a of the light guide 3. Of the light propagating from the −X direction, the light amount I _{Left_Out} of the light emitted to the outside of the light guide 3 is I _{Left_Out} = I _Left × Ra. On the other hand, of the light propagating from the + X direction, the light amount I _{Right_Out} of the light emitted to the outside of the light guide 3 is I _{Right_Out} = I _Right × Rb. That is, the ratio Pb of I _{Right_Out with} respect to I _{Right_Out} is expressed by the following equation (2).

  Here, when Ra / Rb = 0.5, the ratio Pb is expressed by the following formula (3).

  That is, Pb = Pa / 2, and by forming the asymmetrical reflection pattern 41, the ratio of the biased light to the light whose incident angle to the reflection pattern is not biased can be reduced, and the document surface distance changes. The change in the illuminance distribution can be suppressed. That is, it is possible to obtain an illumination device in which the illuminance ratio in the vicinity of the incident surface 3a of the light guide 3 does not change with respect to the central portion of the light guide 3.

  Thus, by providing the asymmetrical reflection pattern 41 in which the curvature radius R2 of the curvature shape 4e of the reflection pattern 4 formed on the light guide 3 is smaller than the curvature shape R1, the illuminance ratio in the region near the light source 1 is guided. An illumination device that does not change with respect to the central portion of the body 3 can be obtained.

  Here, although the curvature radius R2 of the curvature shape 4e of the reflection pattern 41 has been described as an acute angle in the present embodiment, it is not necessarily strictly an acute angle and is a curvature radius that can be created, and the curvature radius of the curvature shape 4d. It is sufficient if it is smaller than R1, for example, R2 = 10 μm.

Embodiment 2. FIG.
In the first embodiment, the example in which the left-right asymmetric reflection pattern 41 is formed along the long axis direction of the light guide 3 has been described. However, in the second embodiment, only the vicinity of the incident surface 3a of the light guide 3 is left-right asymmetric. The reflection pattern 41 is formed, and a symmetrical reflection pattern 42 is formed in a region away from the light source 1, thereby increasing the illuminance irradiated on the irradiated object 12.

  FIG. 10 is a partial enlarged cross-sectional view for explaining the basic configuration of the second embodiment of the present invention. The asymmetrical reflection pattern 41 as described above is formed in the vicinity of the incident surface 3a near the light source 1 of the light guide 3. A region that is separated from the incident surface 3a by a distance L or more that is not affected by light rays that are incident on the light guide 3 from the light source 1 and are not directly reflected in the light guide but directly incident on the reflection pattern is left-right symmetric. The reflection pattern 42 is formed.

  FIG. 11 is a partially enlarged view for explaining the arrangement density of the reflection patterns 41 and 42. In the configuration in which the left-right asymmetric reflection pattern 41 described in the first embodiment is formed along the long axis direction of the light guide, as shown in FIG. 5A, in the vicinity of the reflection surface 3b of the light guide 3. Since the reflection pattern is arranged most densely, the distance d between adjacent areas is made small, and the vicinity of the incident surface 3a is arranged most coarsely, the illuminance distribution along the long axis direction is matched to the illuminance near the reflection surface 3b. The light use efficiency tends to be low (see the broken line in FIG. 11B).

  On the other hand, in the configuration shown in the second embodiment, the symmetrical reflection pattern 42 is provided in a region away from the incident surface 3a where the intensity of the light emitted from the emitting portion 3c is low. The reflection pattern 42 has a curvature radius R2 = R1 of the curvature shape 4e, for example, 30 μm, so that the curvature radius in the direction facing the traveling direction of the guided light is increased, and the extraction efficiency of the guided light is increased. it can. For this reason, the light extraction efficiency is increased and the intensity extracted by the left-right asymmetric reflection pattern near the incident surface 3a is increased. Therefore, the adjacent reflection patterns of the left-right asymmetric reflection pattern 41 formed in the vicinity of the incident surface 3a. The distance d can be made small and densely arranged. Then, the symmetrical reflection patterns 42 in a region away from the incident surface 3a are arranged densely toward the reflecting surface 3b of the light guide 3 so as to be equal to the amount of light in the vicinity of the incident surface 3a. As a result, the light intensity of the illuminance distribution in the major axis direction extracted from the emitting portion 3c can be matched with the light intensity extracted by the left-right asymmetric reflection pattern 41 disposed in the vicinity of the incident surface 3a. Efficiency is improved (see solid line in FIG. 11B). In the light guide, for example, as shown in FIG. 11C, the distance d is changed so that the illuminance distribution becomes uniform as a function of the position in the X direction.

  As described above, in the second embodiment, the asymmetrical reflection pattern 41 is densely arranged in the vicinity of the incident surface 3a of the light guide 3, and the symmetrical reflection pattern 42 is provided in a region away from the incident surface 3a. Thus, even when the document surface distance changes, the illuminance ratio in the vicinity of the incident surface 3a with respect to the central portion of the light guide 3 does not change, and an illumination device with high light use efficiency can be obtained.

Embodiment 3 FIG.
FIG. 12 is a partial enlarged cross-sectional view illustrating the basic configuration of the third embodiment of the present invention. In the first and second embodiments, the example in which the light source 1 is provided at one end of the light guide 3 has been described. In the third embodiment, an example in which the light source 1 is provided at both ends of the light guide 3 is described. To do. Other configurations are the same as those in the first and second embodiments, and the same reference numerals indicate the same or corresponding parts, and redundant descriptions are omitted.

  When the light source 1 is provided at both ends of the light guide 3, both ends are configured as the incident surface 3 a. In this case, in order to reduce the influence of the case where the light from the light source 1 enters the light guide 3 and directly enters the reflection pattern 4 without being totally reflected, the end of the light guide 3 in the + X direction is reduced. A laterally asymmetric reflection pattern 43 is provided. The basic configuration of the reflective pattern 43 is the same as that of the reflective pattern 41. However, as shown in FIG. 12B, the curvature radius of the curvature shape 4e on the + X direction side is R1, and the curvature shape on the -X direction side. Let the radius of curvature of 4d be R2 (<R1). This is because the influence of the directly reflected light is reduced by reducing the radius of curvature in the direction facing the light source 1.

  Next, the arrangement of the reflection patterns 41 and 43 will be described. The light emitted from the light source 1 on the −X direction side in the long axis direction will be described, but the light emitted from the light source 1 on the + X direction side is symmetrical and shows the same behavior. When the arrangement of the reflection patterns 41 and 43 is equally spaced, the light emitted from the light source 1 enters from the incident surface 3a of the light guide 3 and propagates by totally reflecting the inside of the light guide 3. In the region close to the incident surface 3a, the curvature shape 4e on the + X direction side of the reflection pattern 41 has an acute angle, so that the amount of light emitted to the outside of the light guide 3 is small. However, since the reflection pattern 43 is formed in the region on the + X direction side from the central portion of the light guide 3, the light beam reflected by the curvature shape 4 e on the + X direction side is emitted from the emission portion 3 c of the light guide 3. It is taken out. As a result, as shown by the broken line in FIG. 13B, the illuminance distribution in the long axis direction due to the light emitted from the light source 1 on the −X direction side gradually decreases from the −X direction end of the light guide 3. It increases near the center of the light guide 3 and decreases again toward the end in the + X direction. Accordingly, the illuminance distribution by the sum of the light emitted from the two light sources 1 has a shape in which the central portion is raised as shown by the solid line in FIG.

  As a countermeasure, the reflection patterns 41 and 43 are arranged densely by reducing the distance d between adjacent reflection patterns in the vicinity of both end portions of the light guide 3, while the distance d between the reflection patterns adjacent in the vicinity of the center portion. By increasing the size, it is preferable to arrange the reflection patterns 41 and 43 roughly so that the illuminance distribution can be made uniform.

  Thus, by providing the light source 1 at both ends of the light guide 3, the amount of irradiation light can be increased. The reflection pattern 41 is provided in the −X direction area from the center of the light guide 3 and the + X direction. By providing the reflection pattern 43 in the side region, it is possible to obtain an illuminating device in which the illuminance ratio in the vicinity of the incident surface 3a does not change with respect to the central portion of the light guide 3 even when the document surface distance changes.

  In this embodiment, the light guide 3 has a structure in which the asymmetrical reflection pattern 41 is provided in the region on the −X direction side from the central portion and the reflection pattern 43 is provided in the region on the + X direction side. A reflection pattern 41 is formed in a region near the light source 1 on the −X direction side of the body 3, a reflection pattern 43 is formed in a region near the light source 1 on the + X direction side, and a symmetrical reflection pattern 42 near the center of the remaining light guide. May be provided.

Embodiment 4 FIG.
The basic configuration of the fourth embodiment is the same as that of the second and third embodiments, but the arrangement method of the reflection pattern 4 or the radius of curvature of the curvature shape is different from that of the second and third embodiments. For example, in the second embodiment, the right and left asymmetrical reflection pattern 41 formed in the vicinity of the incident surface 3a of the light guide 3 and the left and right symmetrical reflection pattern 42 formed in the other region have different curvature shapes. The reflection characteristics of the wave light are different, and the illuminance of the outgoing light emitted from the light guide 3 is also different. Therefore, the illuminance changes suddenly at the position in the long axis direction where the shape of the reflection pattern 4 changes from the reflection pattern 41 to the reflection pattern Even if the interval d between the adjacent reflection patterns 4 is optimally designed, a change in illuminance tends to occur due to an error in forming the reflection pattern. Therefore, in the fourth embodiment, an arrangement or shape of the reflection pattern 4 that prevents a sudden change in illuminance even when a molding error or the like of the reflection pattern 4 occurs will be described. In addition, although the case where the light source 1 is provided at one end of the light guide 3 is illustrated here, the same effect can be obtained when the light source 1 is provided at both ends of the light guide 3, respectively.

  FIG. 14 is an explanatory diagram of the array distribution of the reflection patterns 4 according to the fourth embodiment of the present invention. In the region where the reflection pattern 41 and the reflection pattern 42 are switched, the two reflection patterns are mixed and the ratio thereof is gradually changed. For example, when the ratio of the reflection patterns 41 within the unit length T in the major axis direction is m and the ratio of the reflection patterns 42 is n (m + n = 1), as shown in FIG. M = 1 and n = 0 at the end on the −X direction side, and m = 0 and n = 1 in the region from the center to the end on the + X direction side, and the ratio is gradually changed in the middle. Yes. As a result, the illuminance with respect to the major axis direction of the light guide 3 is gradually changed, and a sudden change in illuminance can be prevented. Further, by appropriately setting the distance d between the adjacent reflection patterns, a uniform illuminance distribution in which the illuminance distribution in the major axis direction does not change with respect to a reflection pattern forming error can be obtained.

  FIG. 15 is an explanatory diagram of a change in the shape of the reflection pattern. For example, the curvature radius of the curvature shape 4e on the + X direction side of the reflection pattern 41 in the vicinity of the incident surface 3a of the light guide 3 is set to R2 = 0 (acute angle), and the region is not affected by the direct reflected light from the light source 1. The curvature radius of the curvature shape 4e on the + X direction side of the left-right symmetric reflection pattern 42 is R2 = R1. Then, the curvature radius R2 of the curvature shape 4e of the reflection pattern 4 is gradually increased as it proceeds in the + X direction along the major axis direction from the vicinity of the incident surface 3a of the light guide 3. That is, the curvature radius R3 of the curvature shape 4e of the reflection pattern 44 formed between the vicinity of the incident surface 3a and the region where the symmetrical reflection pattern 42 is formed is, as shown in FIG. R3 <R1 is satisfied, and it increases as it proceeds in the + X direction. As a result, the illuminance with respect to the major axis direction of the light guide 3 gradually changes, and no rapid illuminance change occurs. Furthermore, by appropriately setting the distance d between adjacent reflection patterns, a uniform illuminance distribution in which the illuminance distribution in the major axis direction does not change with respect to the reflection pattern forming error can be obtained.

  Thus, when the reflective pattern which has several different shape is formed in the light guide 3, in Embodiment 4, even if the shaping | molding error of a reflective pattern arises, the illuminance distribution of the major axis direction of the light guide 3 is uniform. In addition, it is possible to obtain an illuminating device in which the illuminance ratio at the end with respect to the central portion of the light guide 3 does not change even when the document surface distance changes.

  In the first to fourth embodiments, the reflection pattern has a protruding shape that protrudes outward with respect to the surface of the light guide 3. However, the reflective pattern may be formed in a cutout shape toward the inner side.

  In the first to fourth embodiments, the example in which the two light guides 3 are installed on both sides of the optical axis of the rod lens 8 has been described. However, one light guide 3 is installed only on one side of the optical axis. It is also possible.

1 light source, 2 substrate, 2a lead wire, 3 light guide, 3a incident surface,
3b reflecting surface, 3c emitting part, 4, 41, 42, 43, 44 reflecting pattern,
4a-4c surface, 4d-4g curvature shape, 5 reflective member, 6 holder,
7 Transmitter, 8 Rod lens, 9 Sensor IC, 10 Sensor substrate,
11 Case, 12 Subject to be irradiated.

Claims (7)

A light source;
A rod-shaped light guide that propagates while the light incident inside from the light source is reflected in the long axis direction;
A reflection pattern periodically provided along the major axis direction between one end and the other end of the light guide on the surface of the light guide;
In the process of light propagating through the light guide, light is applied to the reflection pattern from the inside of the light guide, and the light reflected by the reflection pattern is lined on the side facing the reflection pattern through the light guide. A lighting device for forming a light emitting region,
The reflective pattern has a protrusion that gradually decreases in width in the major axis direction as it is farther from the surface of the light guide.
The long axis of the cross-sectional shape of the protrusion portion is formed so that a plurality of curved portions are continuous, Ri asymmetric der respect to a center line through the apex of the protrusion,
In the cross-sectional shape in the major axis direction of the protrusion, the radius of curvature of the curved portion located far from the end of the light guide is larger than the radius of curvature of the curved portion located near the end of the light guide. A lighting device characterized by being small . A light source;
A rod-shaped light guide that propagates while the light incident inside from the light source is reflected in the long axis direction;
A reflection pattern periodically provided along the major axis direction between one end and the other end of the light guide on the surface of the light guide;
In the process of light propagating through the light guide, light is applied to the reflection pattern from the inside of the light guide, and the light reflected by the reflection pattern is lined on the side facing the reflection pattern through the light guide. A lighting device for forming a light emitting region,
The reflective pattern has a protrusion that gradually decreases in width in the major axis direction as it is farther from the surface of the light guide.
The long axis of the cross-sectional shape of the protrusion portion is formed so that a plurality of curved portions are continuous, Ri asymmetric der respect to a center line through the apex of the protrusion,
In the cross-sectional shape in the major axis direction of the protrusion, a symmetrical protrusion that is symmetric with respect to a center line passing through the top is disposed farther from the end of the light guide than the position of the protrusion. Lighting device. A light source;
A rod-shaped light guide that propagates while the light incident inside from the light source is reflected in the long axis direction;
A reflection pattern periodically provided along the major axis direction between one end and the other end of the light guide on the surface of the light guide;
In the process of light propagating through the light guide, light is applied to the reflection pattern from the inside of the light guide, and the light reflected by the reflection pattern is lined on the side facing the reflection pattern through the light guide. A lighting device for forming a light emitting region,
The reflective pattern has a protrusion that gradually decreases in width in the major axis direction as it is farther from the surface of the light guide.
The long axis of the cross-sectional shape of the protrusion portion is formed so that a plurality of curved portions are continuous, Ri asymmetric der respect to a center line through the apex of the protrusion,
In the long-axis cross-sectional shape of the protrusion, the radius of curvature of the curved portion located far from the end of the light guide is gradually increased from the end of the light guide toward the center. A lighting device characterized by changing . The light source is disposed at one end of the light guide,
Wherein the other end of the light guide, an illumination device according to any one of claims 1 to 3, characterized in that the reflecting member or additional light source is disposed. The lighting device according to claim 2 , wherein a ratio of the asymmetric protrusion and the symmetric protrusion is gradually changed from the end of the light guide toward the center. The distance between the reflection patterns adjacent lighting device according to any one of claims 1 to 5, characterized in that it varies according to the position from the end of the light guide. The illumination device according to any one of claims 1 to 6 , which irradiates the irradiated body with light,
A lens that focuses the reflected light from the irradiated object;
An image sensor comprising: a light receiving element that converts an image formed by the lens into an electrical signal.

Images