Optical device and document reading device

Abstract

An optical device and a document reading apparatus are provided, the optical device including: a light guide that scatters light incident from an end surface on a scatterer disposed in a direction in which a side surface extends and emits the light; a specular reflection plate which specularly reflects the light emitted from the light guide body; a light receiving unit that receives the light reflected by the mirror reflection plate; and a diffusion plate that diffuses and transmits light emitted from the light guide so that the light enters the mirror reflection plate, and that diffuses and transmits light reflected by the mirror reflection plate so that the light enters the light receiving unit.

Description

Technical Field

[0001] The invention relates to an optical device and a manuscript reading device. Background Art

[0002] Patent document 1 describes a document reading device, in which a reading guide component provided with a background reflection component is installed so that the rear end portion on the downstream side of the document conveying direction is lifted up and may become inclined to a certain angle when it contacts the document being conveyed, and the light guide has an emission surface that guides light from a light source to emit in a direction irradiated on the background reflection component, and the width of the emission surface in the sub-scanning direction is set to a size that can reflect the light emitted on the background reflection component when the reading guide component is in an inclined state so that the light receiving portion receives the light.

[0003] Patent document 2 describes a document reading device including a background reflecting portion, which is configured in a light receiving state so that light from a light source is reflected after passing through a reading position in a light receiving portion, and reflects reflected light of a larger amount than the document reflected light reflected on the document when no document is present, and the background reflecting portion is constructed by processing a mirror surface so as to reflect reflected light of a smaller amount than the mirror reflected light reflected on the mirror surface.

[0004] Patent document 3 describes a document reading device, which comprises: a light source, which irradiates light to a document passing through a reading position; a background portion, which clamps the document passing through the reading position and is located on the opposite side of the light source; a first detection portion, which is located upstream of the reading position in the conveying direction of the document and detects the front end of the document; a second detection portion, which detects the end of the document based on the difference in light amount between light reflected by the light source at the background portion and light reflected on the document; and a processing portion, which performs front end processing based on the result of the first detection portion and performs tilt processing based on the result of the second detection portion.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2015-019213

[0006] Patent Document 2: Japanese Patent Application Publication No. 2015-012347

[0007] Patent Document 3: Japanese Patent Application Publication No. 2015-023428

[0008] When the light guide scatters and emits light incident from the end face on a scatterer arranged in a direction extending from the side face, the amount of light received by the light receiving portion decreases. On the other hand, if the amount of light is to be increased, uneven light is generated in the light received by the light receiving portion. Summary of the invention

[0009] The object of the present invention is to suppress both a decrease in the amount of light received by a light receiving portion and generation of uneven light amount in the light received by the light receiving portion when a light guide scatters and emits light incident from an end face on a scatterer arranged in a direction extending from a side surface.

[0010] The invention described in Scheme 1 is an optical device, which comprises: a light guide, which scatters and emits light incident from an end face on a scatterer arranged in a direction extending from a side face; a mirror reflection plate, which mirror-reflects the light emitted from the light guide; a light receiving unit, which receives the light reflected on the mirror reflection plate; and a diffuser, which diffuses and transmits the light emitted from the light guide to be incident on the mirror reflection plate, and diffuses and transmits the light reflected on the mirror reflection plate to be incident on the light receiving unit.

[0011] The invention described in claim 2 is the optical device described in claim 1, wherein the diffuser includes a first layer having a first regular reflectance and a second layer having a second regular reflectance lower than the first regular reflectance, and the second layer is arranged toward the light receiving portion.

[0012] The invention described in claim 3 is the optical device described in claim 2, wherein the first layer is a primer layer, and the second layer is a light diffusion layer.

[0013] The invention described in claim 4 is the optical device described in claim 1, further comprising a lens unit that guides the light reflected by the mirror reflection plate to the light receiving unit, and the mirror reflection plate has a characteristic that the light receiving unit is not located within the focal depth of the lens unit.

[0014] The invention described in claim 5 is the optical device described in claim 4, wherein the mirror reflection plate has the above characteristics by arranging a concave shape in the direction in which the side surface of the light guide extends.

[0015] The invention described in Scheme 6 is a document reading device, which comprises: a light source, which is arranged on the end face side of a light guide and irradiates light; a reading window portion, through which a document passes; and an optical device described in any one of Schemes 1 to 5, wherein the light receiving portion receives light emitted from the light guide and reflected on the document when the document passes through the reading window portion, and receives light reflected on the mirror reflection plate when the document does not pass through the reading window portion.

[0016] Effects of the Invention

[0017] According to the first scheme of the present invention, when the light guide scatters and emits light incident from the end face on a scatterer arranged in a direction extending from the side face, both a decrease in the amount of light received by the light receiving portion and generation of uneven light amount in the light received by the light receiving portion can be suppressed.

[0018] According to the second aspect of the present invention, the possibility that the amount of light received by the light receiving section will decrease can be further reduced.

[0019] According to the third aspect of the present invention, the possibility that the amount of light received by the light receiving section will decrease can be easily reduced.

[0020] According to the fourth aspect of the present invention, the possibility of uneven light quantity occurring in the light received by the light receiving section can be further reduced.

[0021] According to the fifth aspect of the present invention, the possibility of uneven light quantity occurring in the light received by the light receiving section can be easily reduced.

[0022] According to the sixth scheme of the present invention, when the light guide scatters and emits light incident from the end face on a scatterer arranged in a direction extending from the side face, both a decrease in the amount of light received by the light receiving portion and generation of uneven light amount in the light received by the light receiving portion can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Embodiments of the present invention will be described in detail with reference to the following drawings.

[0024] Figure 1 is a diagram showing a configuration example of an image reading device in this embodiment;

[0025] Figure 2 is a perspective view showing an image reading unit in this embodiment;

[0026] Figure 3 is an exploded perspective view showing an image reading unit in this embodiment;

[0027] Figure 4 is a cross-sectional view showing the image reading section in this embodiment ( Figure 5 IV-IV cross-sectional view);

[0028] Figure 5 is a cross-sectional view showing the image reading section in this embodiment ( Figure 4 VV section view of the

[0029] Figure 6 is an explanatory diagram for explaining a diffusion pattern and light emitted from a light emitting element in this embodiment;

[0030] Figure 7 is a first graph showing an output value of reflected light based on a mirror reflection plate;

[0031] Figure 8 is a second graph showing the output value of the reflected light based on the specular reflection plate;

[0032] Fig. 9 is a diagram for explaining the dust detection correction function;

[0033] Fig.10 is a diagram showing a structural example of a mirror reflection plate in this embodiment;

[0034] Fig.11 is a graph showing output values ​​of reflected light based on a specular reflector when a diffuser is disposed on the specular reflector;

[0035] Fig.12 is a graph showing the output value of reflected light based on the mirror reflection plate when the bottom coating layer is arranged on the image reading unit side;

[0036] Fig.13 It is a partial enlargement. Fig.12 a graph of a graph of a graph of;

[0037] Fig.14 is a graph showing the output value of reflected light from the mirror reflector when the light diffusion layer is arranged on the image reading unit side;

[0038] Fig.15 It is a partial enlargement. Fig.14 a graph of a graph of a graph of;

[0039] Fig.16 (a) Fig.16 (b) is a diagram for explaining a modified example of the mirror reflection plate in this embodiment.

[0040] Explanation of symbols

[0041] 60-image reading device, 100-image reading unit, 110-light guide, 110A-end face, 110B-side face, 111-diffusion pattern, 112-rod lens array, 125-light receiving unit, 128-light emitting element, 220-mirror reflection plate, 230-diffusion plate, 232-substrate, 234-light diffusion layer, 236-bottom coating layer. DETAILED DESCRIPTION

[0042] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0043] [Image reading device]

[0044] Figure 1 1 is a diagram showing a configuration example of an image reading device 60 in the present embodiment. In the diagram, the vertical direction is indicated by H, and the device width direction is indicated by W.

[0045] As shown in the figure, the image reading device 60 includes a first transparent plate 62 (so-called platen glass) on which the original G is placed when reading an image of an original G, and a second transparent plate 72 disposed on one side (left side in the figure) in the device width direction of the first transparent plate 62. The first transparent plate 62 and the second transparent plate 72 are embedded in the upper part of the frame 60A of the image reading device 60.

[0046] Above the first transparent plate 62 and the second transparent plate 72, an opening / closing cover 66 for opening or closing the first transparent plate 62 and the second transparent plate 72 is disposed. In addition, inside the opening / closing cover 66, there is a conveying unit 64 (so-called ADF) for conveying a plurality of originals G along a conveying path 70 in the opening / closing cover 66 and passing through an original reading position R above the second transparent plate 72. The conveying unit 64 is provided with a reading guide member 210 for guiding the originals G being conveyed along the conveying path 70 to the original reading position R and guiding them to a discharge direction after passing through the original reading position R. A mirror reflection plate 220 is provided on a part of the lower surface of the reading guide member 210 that faces the original reading position R.

[0047] The internal space of the housing 60A is provided with an image reading unit 100 that reads an image of the document G placed on the first transparent plate 62 and an image of the document G transported by the transport unit 64 to the document reading position R. The image reading device 60 also includes a drive unit 74 that drives the image reading unit 100 in the device width direction.

[0048] The driving unit 74 includes a shaft 76 extending in the device width direction (moving direction of the image reading unit 100 ) and a sliding member 78 attached to the lower surface of the frame 114 of the image reading unit 100 and slidably supported by the shaft 76 .

[0049] The driving unit 74 includes a motor (not shown), a driving pulley 84 that is rotationally driven by the motor through a driving force transmitted therefrom, a driven pulley 86 that rotates therefrom, and an endless belt 82 that is wound around the driving pulley 84 and the driven pulley 86. The driving pulley 84 is mounted on one end of the shaft 76, and the driven pulley 86 is mounted on the other end of the shaft 76.

[0050] The image reading unit 100 will be described in detail later.

[0051] In the image reading device 60, the image reading unit 100 reads the image of the original document G as follows. Specifically, when reading the image of the original document G conveyed by the conveying unit 64, as shown in the figure, the image reading unit 100 is moved to the conveying reading position on the other side of the device width direction by the driving force of the motor (not shown) transmitted via the endless belt 82 and stops. Then, the image reading unit 100 arranged at the conveying reading position reads the image of the original document G conveyed by the conveying unit 64.

[0052] Furthermore, when reading the image of the original G placed on the first transparent plate 62, although not shown in the figure, the image reading unit 100 reads the image of the original G from the reading start position while moving in the device width direction along the first transparent plate 62 toward the reading end position through the driving unit 74.

[0053] Here, the image reading device 60 is an example of a document reading device.

[0054] [Image reading unit]

[0055] Figure 2 It is a perspective view showing the image reading unit 100 in this embodiment.

[0056] Figure 3 It is an exploded perspective view showing the image reading unit 100 in this embodiment.

[0057] Figure 4 2 is a cross-sectional view showing the image reading unit 100 in this embodiment. Specifically, Figure 4 yes Figure 5 IV-IV section view. In addition, Figure 4 In FIG. 1 , although strictly speaking, they are not components of the image reading unit 100 , the second transparent plate 72 and the mirror reflection plate 220 are also shown.

[0058] Figure 5 2 is a cross-sectional view showing the image reading unit 100 in this embodiment. Specifically, Figure 5 yes Figure 4 VV cross-sectional view.

[0059] Figure 6 It is an explanatory diagram for explaining the diffusion pattern and the light emitted from the light emitting element in this embodiment.

[0060] In these drawings, the up-down direction is indicated by H, the width direction of the device is indicated by W, and the depth direction of the device is indicated by D.

[0061] like Figure 2 to Figure 6As shown, the image reading unit 100 includes a light emitting unit 124 for irradiating light toward the original G, a light receiving unit 125 for receiving the light, a rod lens array 112 for guiding the light to the light receiving unit 125, and a glass plate 122. Then, the image reading unit 100 reads the image formed on the original G using a known CIS (Contact Image Sensor) method.

[0062] Furthermore, when the image reading unit 100 reads the image of the document G conveyed by the conveying unit 64, Figure 4 As shown in FIG. 2 , the mirror reflector 220 is arranged upward below the second transparent plate 72 and is arranged directly below the mirror reflector 220. In this case, the document G conveyed by the conveying unit 64 passes through the document reading position R on the second transparent plate 72. Then, when the document G passes through the document reading position R on the second transparent plate 72, the document G reflects the light emitted from the side surface 110B of the light guide 110 described later. On the other hand, when the document G does not pass through the document reading position R on the second transparent plate 72, the mirror reflector 220 reflects the light emitted from the side surface 110B of the light guide 110 described later.

[0063] Here, the second transparent plate 72 is an example of a reading window portion through which a document passes, and the mirror reflection plate 220 is an example of a mirror reflection plate that specularly reflects light emitted from the light guide.

[0064] The light receiving unit 125 includes a light receiving substrate 102 and a plurality of light receiving elements 126 arranged along the depth direction of the device. Figure 3 As shown, the thickness direction of the light receiving substrate 102 is set as the vertical direction. When viewed from above, the light receiving substrate 102 is set to a rectangular shape extending in the depth direction of the device and is arranged below the frame 114. In addition, a plurality of light receiving elements 126 are mounted on the upper surface of the light receiving substrate 102.

[0065] Furthermore, when the document G passes through the document reading position R on the second transparent plate 72, the light receiving unit 125 receives light emitted from a side surface 110B of the light guide 110 described later and reflected on the document G. On the other hand, when the document G does not pass through the document reading position R on the second transparent plate 72, the light receiving unit 125 receives light emitted from a side surface 110B of the light guide 110 described later and reflected on the mirror reflection plate 220.

[0066] Here, the light receiving unit 125 is an example of a light receiving unit that receives light reflected by the mirror reflector. Furthermore, the light receiving unit 125 is an example of a light receiving unit that receives light emitted from the light guide and reflected by the original when the original passes through the reading window, and receives light reflected by the mirror reflector when the original does not pass through the reading window.

[0067] The rod lens array 112 is made of a transparent material (eg, glass) and is formed into a rectangular parallelepiped shape extending in the depth direction of the device. Figure 4 As shown, the rod lens array 112 is accommodated in the lens accommodation portion 114B of the frame 114. The rod lens array 112 is configured to focus light emitted from the side surface 110B of the light guide 110 described later and reflected on the document G, to the light receiving element 126, when the document G passes through the document reading position R on the second transparent plate 72. On the other hand, the rod lens array 112 is configured to focus light emitted from the side surface 110B of the light guide 110 described later and reflected on the mirror reflection plate 220, to the light receiving element 126, when the document G does not pass through the document reading position R on the second transparent plate 72.

[0068] Here, the rod lens array 112 is an example of a lens unit that guides light reflected by the mirror reflection plate to the light receiving unit.

[0069] like Figure 3 As shown, the glass plate 122 has its thickness direction set to the vertical direction, and when viewed from above, it is set to a rectangular shape extending in the depth direction of the device. Figure 4 As shown, the glass plate 122 is fixed to the frame 114 by a fixing means (not shown) in a state where the edge of the glass plate 122 contacts the step portion 115 of the frame 114 , and is arranged to cover the upper surface of the frame 114 .

[0070] like Figure 3 and Figure 4 As shown, the light emitting unit 124 includes a light guide 110, an irradiation unit 103, and a frame 114 constituting the device body. The light emitting unit 124 includes two light guides 110, but the light guides 110 are arranged in parallel symmetrically with respect to the center of the frame 114 in the device width direction.

[0071] like Figure 3 As shown, the light guide 110 is formed into a cylindrical shape using a transparent material (e.g., acrylic resin) and extends in the longitudinal direction with the depth direction of the device. The light guide 110 is accommodated in a light guide accommodating portion 114A of a frame 114. The light guide 110 allows light incident on one end surface 110A to travel in the longitudinal direction, and irradiates the original G with light emitted from the side surface 110B.

[0072] And, if Figures 4 to 6 As shown, a diffusion pattern 111 is provided in the light guide 110, and the diffusion pattern 111 diffuses the light incident from the end surface 110A of the light guide 110 and travels along the long side direction, and directs the light toward the top of the rod lens array 112 (towards Figure 4 In the direction of arrow B, Figure 4As shown in FIG. 1 , the diffusion pattern 111 is arranged on the side 110B of the light guide 110 that is opposite to the document G. More specifically, the diffusion pattern 111 is arranged on the side 110B of the two light guides 110 that is opposite to the document G and away from the other light guides 110. That is, the diffusion pattern 111 is not arranged on the lower surface of the light guide 110 in the device lower direction, but is arranged on the lower surface of the light guide 110 in the device lower direction. Figure 4 The center of the fan-shaped diffusion pattern 111 in the device width direction passes through the center of the light guide 110 and is offset toward the document reading position R. Figure 6 As shown, the diffusion pattern 111 is provided at predetermined intervals throughout the long side direction of the light guide 110. Here, as an example, the diffusion pattern 111 is made of a cured white paint, and diffuses the light traveling inside the light guide 110 and directs it toward the upper surface side (the original G side) of the light guide 110. Alternatively, a prism may be used as the diffusion pattern 111.

[0073] Here, the diffusion pattern 111 is an example of a scatterer arranged in the direction in which the side surface extends, and the light guide 110 is an example of a light guide that scatters light incident from an end surface on the scatterer and emits the light.

[0074] like Figure 3 As shown, the irradiation unit 103 includes a wiring substrate 104, a device substrate 106, and an LED light emitting element 128 (hereinafter, “light emitting element 128”).

[0075] The wiring substrate 104 is a so-called flexible flat cable such as Figure 3 As shown, a pair is provided. The base end of one wiring substrate 104 is connected to the end of the inner side (left side of the figure) of the device depth direction of the light receiving substrate 102, and the base end of the other wiring substrate 104 is connected to the end of the near front side (right side of the figure) of the device depth direction of the light receiving substrate 102.

[0076] The component substrate 106 is a so-called flexible printed circuit, and the thickness direction is set as the depth direction of the device. The component substrate 106 is a substrate in a rectangular shape when viewed from the depth direction of the device, such as Figure 3As shown, a pair of substrate accommodating portions 114C accommodated in the frame 114 are provided. One element substrate 106 is connected to the front end of one wiring substrate 104, and the other element substrate 106 is connected to the front end of the other wiring substrate 104. In addition, light-emitting elements 128 arranged in the width direction of the device are mounted on one surface of each element substrate 106. The light-emitting element 128 is an example of a light source that is arranged on the end surface side of the light guide and irradiates light. Here, the element substrate 106 may have flexibility. Flexibility means that, for example, a substrate with a width of 10 mm is supported in a single-arm support state, and a portion 10 mm away from the support end is pressed from above with a force of 9.8 N, and the deflection amount is more than 1 mm.

[0077] like Figure 5 As shown, the light emitting elements 128 are arranged on the surface of the element substrate 106 on the light guide 110 side, facing the end surface 110A of the light guide 110 for every two light guides 110. The light emitting elements 128 emit light and irradiate the end surface 110A with the light.

[0078] [Background of the present embodiment]

[0079] In such an image reading device 60, when the conveying unit 64 conveys the document G along the conveying path 70, the document G may be tilted. In order to cope with this situation, the image reading device 60 may have a function of mechanically correcting the tilt of the document G (hereinafter, "mechanical deflection correction function"). The mechanical deflection correction function causes the document G to touch a stopped roller to generate a loop, thereby correcting the tilt of the front end of the document G and suppressing the deviation of the time when each part of the front end of the document G reaches the document reading position R. However, in this mechanical deflection correction function, there are problems such as the impact sound generated when the front end of the document G collides with the roller, and the impact sound when the loop of the document G is made or eliminated.

[0080] In order to solve this problem, the image reading device 60 may have a function of detecting and correcting the tilt angle of the document G by image processing. However, if there is no difference of a predetermined reference or more between the output value of the reflected light of the document G when the document G passes through the document reading position R and the output value of the reflected light of the mirror reflection plate 220 when the document G does not pass through the document reading position R, the tilt angle of the document G cannot be detected. Specifically, when the output value of the reflected light of the white document G is, for example, an 8-bit 256-grayscale output, it is a value close to 240 LSB, so the output value of the reflected light of the mirror reflection plate 220 needs to be a value higher than that.

[0081] However, when a lighting system is used in which the light emitting element 128 irradiates light from the end surface 110A of the light guide 110 as in the above-mentioned image reading device 60, the output of light from the light guide 110 is reduced, and therefore the output of reflected light from the mirror reflection plate 220 is also reduced. Furthermore, in order to speed up image reading or deepen the depth of focus, it is required to increase the output of reflected light, but the above-mentioned image reading device 60 cannot meet such a requirement.

[0082] In the above example, the final output is shown in the form of 256 grayscale output, but in the previous stage of the final output, sometimes it is processed with a grayscale number higher than that, for example, 10-bit 1024 grayscale, rounded to 8-bit 256 grayscale, and set as the final output. In the following, for the sake of convenience, it is also explained with 10-bit output.

[0083] Figure 7 2 is a first graph showing the output value of the reflected light based on the mirror reflection plate 220. Here, the output value of the reflected light is measured using the mirror reflection plate 220 of the prior art. In order to detect the tilt angle of the original G, the output value of the reflected light based on the mirror reflection plate 220 needs to be about 400 LSB, but it can be seen from the first graph that it does not reach about 400 LSB, and the output of the reflected light is insufficient.

[0084] Figure 8 2 is a second graph showing the output value of the reflected light based on the mirror reflection plate 220. Here, the output value of the reflected light is measured using a mirror reflection plate having a higher reflectivity than the conventional mirror reflection plate 220. As can be seen from the second graph, the output value of the reflected light based on the mirror reflection plate 220 reaches about 400 LSB, but the light amount is uneven (hereinafter also referred to as "uneven") (regions M1 and M2) due to the projection of the diffusion pattern 111.

[0085] That is, among the conventional mirror reflection plates 220 , there is no mirror reflection plate that does not cause insufficient output of reflected light and does not cause unevenness.

[0086] In recent years, the image reading device 60 may have a function of detecting dust on the second transparent plate 72 and performing correction (hereinafter referred to as a “dust detection correction function”).

[0087] Fig. 9 1 is a diagram for explaining the dust detection and correction function. When dust exists on the second transparent plate 72, as shown in the figure, stripes S appear in the same position in the width direction of the image of the original G along the conveying direction. In this case, the dust detection and correction function determines that the stripes S are caused by the dust on the second transparent plate 72, and removes them through image processing.

[0088] On the other hand, if the reflectivity of the mirror reflection plate 220 is increased so as to generate an uneven area ( Figure 8 If the lower limit of the area M1, M2) exceeds the target value, the inclination of the original G can be detected, but the unevenness and Fig. 9 If the image has streaks S, dust cannot be detected by the dust detection correction function.

[0089] [Mirror Reflection Plate of the Present Embodiment]

[0090] Fig.10 2 is a diagram showing a structural example of the mirror reflection plate 220 in this embodiment. As shown in the figure, a diffuser plate 230 is arranged on the image reading unit 100 side of the lower surface of the mirror reflection plate 220 in this embodiment. In addition, in the diffuser plate 230, a light diffusion layer 234 is provided on the image reading unit 100 side of the substrate 232, and a bottom coating layer 236 is provided on the mirror reflection plate 220 side of the substrate 232.

[0091] When the mirror reflector 220 and the diffuser 230 are combined in this manner, light emitted from the light guide 110 passes through the diffuser 230, and light reflected by the mirror reflector 220 passes through the diffuser 230 again. That is, the light passes through the diffuser 230 twice. Thus, the output of the reflected light by the mirror reflector 220 can be increased, and unevenness by the reflected light can be reduced.

[0092] Here, the diffuser 230 is an example of a diffuser that diffuses and transmits light emitted from the light guide so as to be incident on the mirror reflector, and diffuses and transmits light reflected on the mirror reflector so as to be incident on the light receiving unit. The portion including the light guide 110, the mirror reflector 220, the diffuser 230, and the light receiving unit 125 is an example of an optical device.

[0093] Fig.11 2 is a graph showing the output value of the reflected light from the mirror reflector 220 when the diffuser 230 is disposed on the mirror reflector 220. It can be seen from the graph that the output value of the reflected light from the mirror reflector 220 reaches the target value of about 400 LSB.

[0094] exist Fig.10 In the embodiment, it is also conceivable to arrange the light diffusion layer 234 on both sides of the base material 232 , but in this case, the output of the reflected light by the mirror reflection plate 220 is insufficient.

[0095] And, in Fig.10 It is also possible to consider configuring the bottom coating layer 236 on the image reading unit 100 side of the substrate 232 and configuring the light diffusion layer 234 on the mirror reflection plate 220 side of the substrate 232, but in this case, the output of the reflected light based on the mirror reflection plate 220 is insufficient.

[0096] Therefore, in this embodiment, among the surfaces of the diffuser plate 230, the surface with less reflection, i.e., the surface with low regular reflectivity, is arranged on the image reading unit 100 side. Specifically, the light diffusion layer 234 is arranged on the image reading unit 100 side of the substrate 232, and the bottom coating layer 236 is arranged on the mirror reflection plate 220 side of the substrate 232.

[0097] Fig.12 2 is a graph showing the output value of the reflected light from the mirror reflection plate 220 when the base coating layer 236 is disposed on the image reading unit 100 side. Fig.13 It is a partial enlargement. Fig.12 As can be seen from these graphs, if the bottom coating layer 236 is located on the image reading unit 100 side, some unevenness remains.

[0098] Fig.14 It is a graph showing the output value of the reflected light by the mirror reflection plate 220 when the light diffusion layer 234 is arranged on the image reading unit 100 side. Fig.15 It is a partial enlargement. Fig.14 These graphs show that when the light diffusion layer 234 is located on the image reading unit 100 side, almost no unevenness remains.

[0099] In the above, the surface of the bottom coating 236 is used as the surface with more reflection, and the surface of the light diffusion layer 234 is used as the surface with less reflection, and the light diffusion layer 234 is arranged to face the light receiving portion 125 side, but it is not limited to this. More generally, the surface of the first layer having the first regular reflectivity is used as the surface with more reflection, and the surface of the second layer having the second regular reflectivity lower than the first regular reflectivity is used as the surface with less reflection, and the second layer can be arranged to face the light receiving portion side. In this case, the bottom coating 236 is an example of the first layer, and the light diffusion layer 234 is an example of the second layer.

[0100] [Modification of Specular Reflection Plate]

[0101] In the modified example of the mirror reflector 220 in this embodiment, a recess is provided along the long side of the light guide 110 on the image reading unit 100 side of the mirror reflector 220. That is, the modified example of the mirror reflector 220 blurs at an apparent distance by the recess, thereby eliminating the occurrence of unevenness.

[0102] Fig.16 (a), Fig.16 (b) is a diagram for explaining a modified example of the mirror reflection plate 220 in the present embodiment.

[0103] Fig.16(a) is a diagram when no recess is provided on the image reading unit 100 side of the mirror reflection plate 220. In this case, the focus is concentrated on the light receiving unit 125, resulting in unevenness.

[0104] Fig.16 (b) is a diagram in which a recess is provided on the image reading unit 100 side of the mirror reflection plate 220. In this case, the distance from the mirror reflection plate 220 to the rod lens array 112 becomes longer, the light on the light receiving unit 125 spreads, and the unevenness becomes smaller.

[0105] In addition, Fig.16 (a), Fig.16 In (b), the mirror reflection plate 220 is arranged at the same position in the vertical direction. Fig.16 Compared with (a), Fig.16 (b) is to emphasize that the distance from the mirror reflection plate 220 to the rod lens array 112 becomes longer. Fig.16 The mirror reflection plate 220 of (b) is arranged at a ratio Fig.16 The vertical position of the mirror reflection plate 220 in (a) is higher.

[0106] In the above, a recess is provided on the image reading unit 100 side of the mirror reflector 220 along the long side direction of the light guide 110, but the present invention is not limited thereto. The mirror reflector 220 only needs to have a characteristic that the light receiving unit 125 is not located within the focal depth of the rod lens array 112. In the above, as an example of a method for providing the mirror reflector 220 with such a characteristic, a method of arranging a recess shape in the direction in which the side surface of the light guide 110 extends is used.

[0107] In a modified example of the mirror reflection plate 220 , for example, a sheet-like diffusion plate 230 may be attached along the concave portion of the mirror reflection plate 220 .

[0108] Even if the mirror reflector 220 is not provided with a recess, for example, a recess may be provided on the reading guide member 210 to which the mirror reflector 220 is mounted, and the sheet-like mirror reflector 220 and the diffuser 230 may be attached along the recess of the reading guide member 210 .

[0109] [Note]

[0110] (1) An optical device comprising:

[0111] A light guide body, which scatters the light incident from the end face on the scattering body arranged in the direction in which the side face extends and emits the light;

[0112] a specular reflection plate for specularly reflecting the light emitted from the light guide;

[0113] A light receiving part, receiving light reflected from the mirror reflection plate; and

[0114] The diffuser diffuses the light emitted from the light guide and transmits the light to enter the mirror reflector, and diffuses the light reflected by the mirror reflector and transmits the light to enter the light receiving unit.

[0115] (2) The optical device according to (1), wherein:

[0116] The diffusion plate includes a first layer having a first regular reflectance and a second layer having a second regular reflectance lower than the first regular reflectance, and the second layer is arranged toward the light receiving unit.

[0117] (3) The optical device according to (2), wherein:

[0118] The first layer is a bottom coating.

[0119] The second layer is a light diffusion layer.

[0120] (4) The optical device according to (1), wherein:

[0121] It also includes a lens portion for guiding the light reflected by the mirror reflection plate to the light receiving portion,

[0122] The mirror reflection plate has a property that the light receiving portion is not located within the focal depth of the lens portion.

[0123] (5) The optical device according to (4), wherein:

[0124] The mirror reflection plate has the above characteristics by arranging a concave shape in the direction in which the side surface of the light guide extends.

[0125] (6) A document reading device comprising:

[0126] a light source, which is disposed on the end face side of the light guide and irradiates light;

[0127] A reading window for the original document to pass through; and

[0128] The optical device according to any one of (1) to (5),

[0129] The light receiving unit receives light emitted from the light guide and reflected by the document when the document passes through the reading window, and receives light reflected by the mirror reflector when the document does not pass through the reading window.

[0130] According to the invention of (1), when the light guide scatters and emits light incident from the end face on a scatterer arranged in a direction extending from the side face, both a decrease in the amount of light received by the light receiving portion and generation of uneven light amount in the light received by the light receiving portion can be suppressed.

[0131] According to the invention of (2), the possibility that the amount of light received by the light receiving unit will decrease can be further reduced.

[0132] According to the invention of (3), the possibility that the amount of light received by the light receiving unit will decrease can be easily reduced.

[0133] According to the invention of (4), the possibility of uneven light quantity occurring in the light received by the light receiving section can be further reduced.

[0134] According to the invention of (5), the possibility of uneven light quantity occurring in the light received by the light receiving section can be easily reduced.

[0135] According to the invention of (6), when the light guide scatters and emits light incident from the end face on a scatterer arranged in a direction extending from the side face, both a decrease in the amount of light received by the light receiving portion and generation of uneven light amount in the light received by the light receiving portion can be suppressed.

[0136] The above-mentioned embodiments of the present invention are provided for the purpose of illustration and description. In addition, the embodiments of the present invention do not fully and exhaustively include the present invention, and do not limit the present invention to the disclosed methods. Obviously, various modifications and changes are self-evident to those skilled in the art to which the present invention belongs. The present embodiment is selected and described in order to most easily understand the principles of the present invention and its application. Thus, other technicians in the art can understand the present invention through various variations optimized for specific uses assumed to be various embodiments. The scope of the present invention is defined by the above claims and their equivalents.

Claims

1. An optical device comprising: A light guide body, which scatters the light incident from the end face on the scattering body arranged in the direction in which the side face extends and emits the light; a specular reflection plate for specularly reflecting the light emitted from the light guide; A light receiving part, receiving light reflected from the mirror reflection plate; and The diffuser diffuses the light emitted from the light guide and transmits the light to be incident on the mirror reflector, and diffuses the light reflected on the mirror reflector and transmits the light to be incident on the light receiving unit.

2. The optical device according to claim 1, wherein: The diffuser plate includes a first layer having a first regular reflectance and a second layer having a second regular reflectance lower than the first regular reflectance, and the second layer is disposed toward the light receiving unit.

3. The optical device according to claim 2, wherein: The first layer is a bottom coating. The second layer is a light diffusion layer.

4. The optical device according to claim 1, wherein: It also includes a lens portion for guiding the light reflected by the mirror reflection plate to the light receiving portion, The mirror reflection plate has a property that the light receiving portion is not located within the focal depth of the lens portion.

5. The optical device according to claim 4, wherein: The mirror reflection plate has the above characteristics by arranging a concave shape in the direction in which the side surface of the light guide extends.

6. A manuscript reading device comprising: a light source, which is disposed on the end face side of the light guide and irradiates light; A reading window for the original document to pass through; and The optical device according to any one of claims 1 to 5, The light receiving unit receives light emitted from the light guide and reflected by the document when the document passes through the reading window, and receives light reflected by the mirror reflection plate when the document does not pass through the reading window.

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