JP2014007641A - Light guide body, illumination device, and image forming apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light guide body that easily improves a spreading manner of illumination light in a direction orthogonal to a longitudinal direction and uniformity of brightness of the illumination light at a position in the longitudinal direction of the light guide body without largely changing a cross-sectional shape of the light guide body depending on the position in the longitudinal direction.SOLUTION: A light guide body 52 includes a reflection surface 57 that has a plurality of groove pattern surfaces 61 and deflection pattern surfaces 62 that are alternately formed along a main scanning direction on a flat surface 57a. The groove pattern surface 61 has a function to reflect illumination light toward an emission surface 56, and includes reflection groove parts 611 extending in a sub-scanning direction in the flat surface 57a; and the deflection pattern surface 62 has a function to reflect the illumination light toward the emission surface 56, and includes minute reflection concave parts 621 having a deflection surface that deflects to reflect the illumination light in a direction where a reflection angle spreads when viewed from a cross-section in the sub-scanning direction.

Description

  The present invention relates to a light guide for guiding illumination light emitted from a light source, an illumination device using the light guide, and an image forming apparatus using the same.

  2. Description of the Related Art In an image forming apparatus such as a scanner or a copying machine, an illumination device that irradiates light on a document sheet is used to optically read an image on the document sheet. In recent years, a white LED (Light Emitting Diode) having an advantage of high luminous efficiency has been adopted as a light source of the lighting device. In this type of illumination device, it is necessary to illuminate the original sheet in a line shape, but since the LED is a point light source, a linear illumination light is generated by combining a bar-shaped light guide and the white LED. . The light guide is disposed at one end of the light guide and is incident on which illumination light emitted by a white LED is incident, and a strip-shaped exit surface that extends along the longitudinal direction of the light guide and emits the illumination light And a strip-shaped reflecting surface that is formed on a surface facing the emitting surface and reflects the illumination light.

  Illumination light incident from the incident surface exits from the exit surface to the outside while propagating through the light guide. The emitted light is directed directly from the white LED to the reflection surface, and the illumination light (direct light) reflected by the reflection surface and the reflection after being totally reflected at least once by the peripheral surface of the light guide. Illuminating light (indirect light) reflected toward the surface and reflected by the reflecting surface is included. The direct light is emitted exclusively from a portion close to the incident surface. Direct light has a narrower light distribution angle in a direction (sub-scanning direction) perpendicular to the longitudinal direction of the light guide than indirect light.

  Further, when the illumination light incident from the incident surface is incident on the reflecting surface, the angle formed with the axial direction of the light guide becomes smaller as the distance from the incident surface becomes smaller, that is, closer to parallel to the axial direction. As a result, the way in which the illumination light emitted from the light guide spreads in the direction orthogonal to the longitudinal direction of the light guide (sub-scanning direction) decreases as the distance from the incident surface increases. For this reason, there is a disadvantage in that the way in which the illumination light spreads in the direction orthogonal to the longitudinal direction of the light guide becomes uneven in the longitudinal direction of the light guide.

  On the other hand, as a technique for making the illuminance in the longitudinal direction of the light guide uniform, an illumination device of Patent Document 1 is known. In the illumination device of Patent Document 1, the cross-sectional shape of the light guide is polygonal so that the direct light is not emitted from the emission surface. Furthermore, the reflecting surface, which is the bottom surface of the light guide, is inclined in the longitudinal direction, and the cross-sectional shape of the light guide is greatly changed depending on the position in the longitudinal direction.

  In addition, the side surface of the light guide is inclined in the longitudinal direction of the light guide, and the amount of light reflected by the side surface is made different depending on the position in the longitudinal direction, so that the direction is perpendicular to the longitudinal direction of the light guide. There is also known a light guide that makes the spread of the illumination light uniform in the longitudinal direction (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 10-241432 JP 2010-277940 A

  However, in the light guides described in Patent Documents 1 and 2, the cross-sectional shape of the light guide greatly varies depending on the position in the longitudinal direction. When manufacturing an elongated member like a light guide by resin molding, if the cross-sectional shape is greatly different in the position in the longitudinal direction, there is a disadvantage that warpage tends to occur when the light guide is molded. .

  The present invention has been made in view of the above circumstances, and does not greatly change the cross-sectional shape of the light guide depending on the position in the longitudinal direction, and the direction orthogonal to the longitudinal direction at the longitudinal position of the light guide. An object of the present invention is to provide a light guide that can easily improve the way in which the illumination light spreads and the uniformity of the brightness of the illumination light, an illumination device including the same, and an image forming apparatus using the illumination device. To do.

  A light guide according to the present invention is a light guide used in combination with a light source that emits illumination light, and has a main body portion that has a long rod shape in a first direction and guides the illumination light, and the main body. An incident surface on which the illumination light is incident, which is one end surface of the unit, a strip-shaped emission surface that extends along the first direction on the surface of the main body, and emits the illumination light; and A strip-shaped reflecting surface that extends along the first direction and reflects the illumination light on a surface facing the emission surface, and the reflection surface has a function of reflecting the illumination light toward the emission surface; A groove pattern surface in which a reflection groove portion extending in a second direction orthogonal to the first direction is formed on a flat surface, and a function of reflecting the illumination light toward the emission surface, and the illumination light, Deflection in a direction in which the reflection angle widens in a cross-sectional view in the second direction And a deflection pattern surface deflection surface is formed that reflects Te, and the groove pattern surface and the deflection pattern surface, are arranged along the first direction.

  According to this configuration, the light incident from the incident surface is reflected toward the emission surface by the groove pattern surface and the deflection pattern surface included in the reflection surface, and is emitted from the emission surface. The groove pattern surface includes a reflective groove portion. The reflection groove extends in a second direction orthogonal to the first direction, that is, a direction crossing the light incident from the incident surface. Therefore, since the area of the light reflecting surface (interface between the light guide material and air) is increased, the groove pattern surface including the reflecting groove portion can effectively emit a large amount of light from the emitting surface. is there. The groove pattern surface can emit a lot of light from the exit surface. The groove pattern surface has a large room for adjusting the brightness of the illumination light emitted from the exit surface. It means that it is easy to adjust the brightness.

  On the other hand, the deflection pattern surface reflects the illumination light by deflecting the illumination light in a direction in which the reflection angle is widened in a cross-sectional view in the second direction. Therefore, it is easy to adjust how the illumination light spreads in a direction (second direction) orthogonal to the longitudinal direction of the light guide by the deflection pattern surface.

  As described above, on the reflection surface, it is easy to adjust the groove pattern surface on which the brightness of the illumination light can be easily adjusted, and how the illumination light spreads in the direction orthogonal to the longitudinal direction of the light guide. Since the concave patterns are arranged along the longitudinal direction (first direction) of the light guide, the way in which the illumination light spreads in the direction perpendicular to the longitudinal direction and the illumination light at the longitudinal position of the light guide It is easy to improve the uniformity of brightness. In addition, by forming grooves and deflection surfaces on the reflecting surface, it becomes possible to improve the way in which the illumination light spreads in the direction orthogonal to the longitudinal direction and the uniformity of the brightness of the illumination light. There is no need to greatly change the cross-sectional shape depending on the position in the longitudinal direction.

  The plurality of groove pattern surfaces and the plurality of deflection pattern surfaces are mixed along the first direction, and are reflected by the groove pattern surfaces and the deflection pattern surfaces in the vicinity of the incident surface. It is preferable that the ratio of light to be reflected by the deflection pattern surface is larger than the ratio in the vicinity of the other end face of the main body.

  According to this configuration, the ratio of the light reflected by the deflection pattern surface, that is, the light deflected in the direction orthogonal to the longitudinal direction of the light guide (second direction) is increased in the vicinity of the incident surface where much direct light is present. . As a result, it is possible to improve the uniformity of how the illumination light spreads in the direction orthogonal to the longitudinal direction.

  In addition, each of the plurality of groove pattern surfaces includes a plurality of the reflection groove portions formed in parallel with a predetermined interval, and the interval in the groove pattern surface formed in the vicinity of the incident surface is the main body portion. It is preferable that it is wider than the said space | interval in the said groove | channel pattern surface formed in the other end surface vicinity.

  According to this configuration, the density of the reflection groove portion on the groove pattern surface is reduced in the vicinity of the incident surface where much direct light is present, and the ratio of light reflected by the deflection pattern surface is relatively increased. As a result, the ratio of light deflected in the direction (second direction) orthogonal to the longitudinal direction of the light guide increases in the vicinity of the incident surface where there is much direct light. Therefore, it is possible to improve the uniformity of how the illumination light spreads in the direction orthogonal to the longitudinal direction.

  Moreover, it is preferable that the said deflection | deviation pattern surface contains the minute reflective recessed part which has the said deflection surface.

  According to this configuration, the reflection recess has the deflection surface that reflects the illumination light by deflecting the illumination light in a direction in which the reflection angle is widened in the cross-sectional view in the second direction. According to the reflective concave portion, the illumination light can be deflected in the second direction, that is, in a direction in which the reflection angle is widened in a cross-sectional view perpendicular to the longitudinal direction, so that the light guide is formed by the deflection pattern surface including the reflective concave portion. It is easy to adjust how the illumination light spreads in a direction (second direction) orthogonal to the longitudinal direction of the light. In addition, since a reflective recess having a deflecting surface can be obtained by forming a minute recess on the reflecting surface, it is not necessary to greatly change the cross-sectional shape of the light guide depending on the position in the longitudinal direction.

  The reflective recess has a shape in which the flat surface of the reflective surface is recessed in a triangular pyramid shape, and one of the three apexes of the triangular pyramid included in the flat surface is the other two It is preferable to be positioned closer to the incident surface than the apex.

  According to this configuration, at least one of the triangular pyramid surfaces (interface between the light guide material and air) is a deflection surface disposed obliquely with respect to the longitudinal direction of the light guide. The triangular pyramid surface that is the deflection surface can reflect and diffuse light emitted from the light source in a direction perpendicular to the longitudinal direction. As a result, the reflection recess can reflect the illumination light by deflecting it in a direction in which the reflection angle is widened in the cross-sectional view in the second direction.

  Further, the reflection concave portion has a vertex of the triangular pyramid that is not included in the flat surface, is located at a substantially center of the other two vertices in a plan view as viewed from the exit surface side, and the flat surface It is preferable that a side connecting the vertex not included in the first vertex and the one vertex is along the first direction in a plan view seen from the emission surface side.

  According to this configuration, since the surfaces on both sides of the side become the deflection surfaces arranged obliquely with respect to the longitudinal direction of the light guide, the reflection concave portion is the light emitted from the light source by the two deflection surfaces. Can be efficiently reflected and diffused in the sub-scanning direction. In addition, since the angle between the two deflection surfaces with respect to the longitudinal direction is substantially bilaterally symmetrical with respect to the main scanning direction, the illumination light can be spread in a balanced manner in a direction orthogonal to the longitudinal direction.

  Moreover, it is preferable that the said reflective recessed part has a semi-ellipsoid shape, and the major axis direction is extended in the said 2nd direction.

  According to this configuration, the elliptical major axis direction extends in a direction crossing the light emitted from the light source. Therefore, the reflection concave portion effectively deflects the illumination light in the direction in which the reflection angle is widened in a cross-sectional view in the second direction, as a result of an increase in the area for reflecting light, compared to the case where the minor axis direction extends in the second direction. Can be reflected.

  Moreover, it is preferable that the said light guide consists of a member obtained by mold-molding translucent resin material.

  According to this structure, since it is not necessary to change the cross-sectional shape of the main-body part of a light guide largely by the position of a longitudinal direction, when a light guide is shape-molded, it is hard to generate | occur | produce a curvature. Therefore, a member obtained by molding a translucent resin material is suitable as a light guide.

  Moreover, the illuminating device which concerns on this invention is equipped with the light source which emits illumination light, and the above-mentioned light guide.

  In addition, an image forming apparatus according to the present invention includes the above-described illumination device that irradiates the original sheet with illumination light, a light receiving device that receives reflected light from the original sheet and converts it into an electrical signal, and an output from the light receiving device. And an image carrier on which an electrostatic latent image is formed based on the image data, the first direction is the main scanning direction, and the second direction is the sub-scanning direction.

  According to the present invention, it is possible to adjust the groove pattern surface on which the brightness of the illumination light can be easily adjusted on the reflection surface and the manner in which the illumination light spreads in the direction orthogonal to the longitudinal direction of the light guide. Since easy concave patterns are alternately formed, it is possible to improve how the illumination light spreads in the direction perpendicular to the longitudinal direction and the brightness uniformity of the illumination light at the longitudinal position of the light guide. Is easy. In addition, by forming grooves and minute recesses on the reflective surface, it is possible to improve the way in which illumination light spreads in the direction orthogonal to the longitudinal direction and the uniformity of the brightness of the illumination light. It is not necessary to greatly change the cross-sectional shape of the body depending on the position in the longitudinal direction.

1 is a cross-sectional view illustrating a schematic configuration of an image reading apparatus and an image forming apparatus according to an embodiment of the present invention. It is a perspective view which shows the illuminating device which concerns on one Embodiment of this invention. It is the III-III sectional view taken on the line of FIG. It is a schematic diagram which shows the reflection state of the illumination light in a light guide. It is a graph which shows angle distribution of the light intensity in the subscanning direction of the direct light and indirect light which radiate | emit from a light guide. It is a figure which shows typically the outgoing condition from the light guide of direct light and indirect light. It is a perspective view which shows the entrance plane vicinity of a light guide. It is the expansion perspective view which expanded a part of reflective surface shown in FIG. (A) is sectional drawing which cut | disconnected the reflective groove part in the main scanning direction. (B) is the front view which looked at the reflective recessed part from the entrance plane side. (C) is the top view which looked at the reflective recessed part from the output surface side. (A) is explanatory drawing for demonstrating the reflection state of the illumination light by the reflective groove part which consists of a V-shaped concave groove. (B) is explanatory drawing for demonstrating the reflection state of the illumination light by the reflective groove part which consists of a semicircular concave groove. (A) is explanatory drawing for demonstrating the reflection state of the illumination light by the reflective recessed part of the shape dented in the shape of a triangular pyramid. (B) is explanatory drawing for demonstrating the reflection state of the illumination light by the reflective recessed part of the shape dented in the semi-elliptical shape. FIG. 8 is a graph showing measurement results of illuminance distribution in the sub-scanning direction of illumination light emitted from the emission surface in the illumination device shown in FIG. 7. It is a graph which shows the illumination intensity distribution by the comparative example at the time of not providing a deflection pattern surface.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view showing an internal structure of an image forming apparatus 1 according to an embodiment of the present invention. Here, as the image forming apparatus 1, a so-called in-body discharge type copier is illustrated. The apparatus to which the illumination apparatus according to the present invention is applied is not limited to a copying machine, and may be, for example, a scanner apparatus, a facsimile apparatus, or a multifunction machine.

  The image forming apparatus 1 includes a housing 2 having a substantially rectangular parallelepiped housing structure and having an in-cylinder space (in-cylinder discharge unit 24). The housing 2 includes a lower housing (device main body 21) that accommodates various devices for image formation, an upper housing (image reading device 22) disposed above the device main body 21, and the device main body 21. And a connecting housing 23 that connects the image reading device 22. The image reading device 22 optically reads an image on a document sheet and generates image data corresponding to the document image. The apparatus main body 21 performs a process of forming a toner image on the sheet based on the image data. Between the apparatus main body 21 and the image reading apparatus 22, an in-body discharge unit 24 that discharges a sheet after image formation is provided. The connection housing 23 is disposed on the right side surface of the housing 2 and is provided with a discharge port 961 for discharging the sheet to the in-body discharge unit 24.

  In the apparatus main body 21, toner containers 99Y, 99M, 99C, and 99K, an intermediate transfer unit 92, an image forming unit 93, an exposure unit 94, and a paper feed cassette 211 are accommodated in this order from the top.

  The image forming unit 93 forms four image forming units 10Y and 10M that form yellow (Y), magenta (M), cyan (C), and black (Bk) toner images in order to form a full-color toner image. 10C, 10Bk. Each of the image forming units 10Y, 10M, 10C, and 10Bk includes a photosensitive drum 11 and a charger 12, a developing device 13, a primary transfer roller 14, and a cleaning device 15 that are disposed around the photosensitive drum 11. .

  The photosensitive drum 11 rotates about its axis, and an electrostatic latent image and a toner image are formed on its peripheral surface. As the photoreceptor drum 11, a photoreceptor drum using an amorphous silicon (a-Si) material can be used. The charger 12 uniformly charges the surface of the photosensitive drum 11. The peripheral surface of the photosensitive drum 11 after charging is exposed by the exposure unit 94 to form an electrostatic latent image.

  The developing device 13 supplies toner to the peripheral surface of the photosensitive drum 11 in order to develop the electrostatic latent image formed on the photosensitive drum 11. The developing device 13 is for a two-component developer and includes stirring rollers 16 and 17, a magnetic roller 18, and a developing roller 19. The stirring rollers 16 and 17 charge the toner by circulating and conveying the two-component developer while stirring. A two-component developer layer is carried on the peripheral surface of the magnetic roller 18, and toner formed by transferring toner to the peripheral surface of the developing roller 19 due to a potential difference between the magnetic roller 18 and the developing roller 19. The layer is supported. The toner on the developing roller 19 is supplied to the peripheral surface of the photosensitive drum 11 and the electrostatic latent image is developed.

  The primary transfer roller 14 forms a nip portion with the photosensitive drum 11 across the intermediate transfer belt 921 provided in the intermediate transfer unit 92, and the toner image on the photosensitive drum 11 is primary transferred onto the intermediate transfer belt 921. To do. The cleaning device 15 cleans the peripheral surface of the photosensitive drum 11 after the toner image is transferred.

  The yellow toner container 99Y, the magenta toner container 99M, the cyan toner container 99C, and the black toner container 99Bk each store toner of each color, and image forming units 10Y, 10M, and 10C corresponding to the respective colors of YMCBk. Each color toner is supplied to the 10 Bk developing device 13 through a supply path (not shown).

  The exposure unit 94 includes various optical system devices such as a light source, a polygon mirror, a reflection mirror, and a deflection mirror, and is provided on the peripheral surface of the photosensitive drum 11 provided in each of the image forming units 10Y, 10M, 10C, and 10Bk. The electrostatic latent image is formed by irradiating light based on the image data of the document image.

  The intermediate transfer unit 92 includes an intermediate transfer belt 921, a driving roller 922, and a driven roller 923. On the intermediate transfer belt 921, toner images are overcoated from the plurality of photosensitive drums 11 (primary transfer). The overcoated toner image is secondarily transferred to the sheet supplied from the paper feed cassette 211 or the paper feed tray 30 by the secondary transfer unit 98. A driving roller 922 and a driven roller 923 that rotate the intermediate transfer belt 921 are rotatably supported by the apparatus main body 21.

  The paper feed cassette 211 stores a sheet bundle in which a plurality of sheets are stacked. A pickup roller 212 is disposed at the upper right side of the paper feed cassette 211. By driving the pickup roller 212, the uppermost sheet of the sheet bundle in the sheet feeding cassette 211 is fed out one by one and carried into the carry-in conveyance path 26. Note that a paper feed unit 40 including a paper feed tray 30 for manual paper feed is provided on the right side surface of the apparatus main body 21. The sheet placed on the paper feed tray 30 is carried into the carry-in conveyance path 26 by driving the paper feed roller 41 of the paper feed unit 40.

  On the downstream side of the carry-in conveyance path 26, a sheet conveyance path 28 that extends to the discharge port 961 through the secondary transfer unit 98, a fixing unit 97 and a paper discharge unit 96 described later is provided. The upstream portion of the sheet conveyance path 28 is formed between an inner wall formed in the apparatus main body 21 and an inner wall that forms the inner surface of the reverse conveyance unit 29. The outer surface of the reverse conveyance unit 29 constitutes one side of a reverse conveyance path 291 that reversely conveys the sheet during duplex printing. A registration roller pair 27 is disposed on the upstream side of the sheet transfer path 28 from the secondary transfer unit 98. After the sheet is temporarily stopped by the registration roller pair 27 and skew correction is performed, the sheet is sent to the secondary transfer unit 98 at a predetermined timing for image transfer.

  A fixing unit 97 and a paper discharge unit 96 are accommodated in the connection housing 23. The fixing unit 97 includes a fixing roller and a pressure roller, and performs a fixing process by heating and pressing the sheet on which the toner image is secondarily transferred in the secondary transfer unit 98. The sheet with the color image that has been subjected to the fixing process is discharged from the discharge port 961 toward the in-body discharge unit 24 by the discharge unit 96 disposed downstream of the fixing unit 97.

  The image reading device 22 includes a first contact glass 222 and a second contact glass 223 that are fitted into the upper surface 221 of the upper casing. The first contact glass 222 is provided for reading a document sheet automatically fed from the ADF when an automatic document feeder (ADF; not shown) is arranged on the image reading device 22. The second contact glass 223 is provided for reading a manually placed document sheet.

  The image reading device 22 includes a first moving carriage 224, a second moving carriage 225, a condenser lens unit 228, and an image sensor 229 (light receiving device) housed in the upper housing. The first moving carriage 224 is mounted with the illumination device 50 according to the embodiment of the present invention and the first reflection mirror 226. A second reflecting mirror 227A and a third reflecting mirror 227B are mounted on the second moving carriage 225 in order to reverse the optical path.

  The first moving carriage 224 reciprocates in the left-right direction along the lower surfaces of the first contact glass 222 and the second contact glass 223. The second moving carriage 225 reciprocates in the left-right direction with a movement amount ½ that of the first moving carriage 224. The first moving carriage 224 moves immediately below the first contact glass 222 and becomes stationary when in an automatic feeding mode in which the document sheet is automatically fed from an unillustrated automatic document feeder. In this stationary state, light is emitted from the illumination device 50 toward the document sheet. On the other hand, in the manual placement mode in which the document sheet is placed on the second contact glass 223, the first moving carriage 224 moves to the right according to the size of the document sheet from directly below the left end of the second contact glass 223. . During this movement, light is emitted from the illumination device 50 toward the document sheet. The second moving carriage 225 moves to the right following the first moving carriage 224 with a movement amount ½ of the first moving carriage 224.

  The illumination device 50 irradiates the original sheet with illumination light having a line shape that is long in the main scanning direction. Specifically, the illuminating device 50 directs an original sheet image toward an automatically fed original sheet passing over the first contact glass 222 or a manually placed original sheet placed on the second contact glass 223. Illumination light is emitted for optical reading. The first reflection mirror 226 reflects the reflected light of the illumination light emitted from the illumination device 50 toward the document sheet so as to be directed toward the second reflection mirror 227A of the second movable carriage 225.

  The second reflecting mirror 227A reflects the reflected light reflected by the first reflecting mirror 226 toward the third reflecting mirror 227B. The third reflection mirror 227 </ b> B reflects the reflected light toward the condenser lens unit 228. The condenser lens unit 228 forms an optical image of the reflected light reflected by the third reflecting mirror 227B on the imaging surface of the imaging element 229. The image sensor 229 is composed of a CCD (charge coupled device) or the like, and photoelectrically converts the reflected light into an analog electric signal. This analog electrical signal is converted into a digital electrical signal by an A / D conversion circuit (not shown), and then input to the exposure unit 94 as image data.

  A white reference plate (not shown) for determining a white reference for reading density is disposed on the left end side of the second contact glass 223. Before the image reading operation, the white reference plate is irradiated with illumination light, and the reflected light is received by the image sensor 229, and a correction value is obtained in advance so that the image data at this time becomes a uniform output in the main scanning direction. (Shading correction).

  Next, details of the lighting device 50 will be described. 2 is a perspective view of the lighting device 50, and FIG. 3 is a cross-sectional view taken along line III-III in FIG. The illuminating device 50 includes a light source 51 that emits illumination light, and a light guide 52 that propagates the illumination light emitted from the light source 51, converts the illumination light into a linear illumination light, and emits the light.

  The light source 51 has a thin disk shape and includes a white LED (Light Emitting Diode) 51L that emits white light. As the white LED 51L, for example, an LED package in which a GaN-based or InGaN-based semiconductor light emitting element that emits blue light or ultraviolet light is sealed with a transparent resin containing a phosphor can be used. 2 shows one white LED 51L, the light source 51 actually includes a plurality of modular white LEDs 51L as shown in FIG.

  As the light source 51, a white LED that generates white light by combining three LEDs each emitting light of the three primary colors may be used. Moreover, you may employ | adopt light sources other than LED as the light source 51, and the light source 51 may not be a white light source.

  The light guide 52 is formed of a translucent resin material, has a long bar shape in the main scanning direction (first direction), and a main body 53 that guides illumination light emitted from the light source 51; It includes an incident surface 54 that is one end surface of the main body 53 and on which the illumination light is incident, and a far end surface 55 that is an end surface opposite to the incident surface 54. The light emitting surface of the light source 51 is in contact with the incident surface 54. The far end surface 55 is provided with a reflective coating layer that prevents the illumination light from leaking from the far end surface 55. Hereinafter, the longitudinal direction of the light guide 52 is referred to as a main scanning direction, and the direction orthogonal to the longitudinal direction of the light guide 52 is referred to as a sub-scanning direction.

  The light guide 52 is further provided with an emission surface 56 disposed on the upper surface side of the main body 53 (side facing the first and second contact glasses 222 and 223), and the main body 53 facing the emission surface 56. And a reflecting surface 57 disposed on the lower surface side of the. The emission surface 56 is a band-like surface extending in the main scanning direction, and is a surface that emits the illumination light toward the first and second contact glasses 222 and 223 (original sheet). Similarly, the reflection surface 57 is a band-like surface extending in the main scanning direction, and reflects the illumination light propagating in the main body 53 toward the emission surface 56.

  The exit surface 56 has a relatively gentle convex curved surface in the sub-scanning direction. As will be described in detail later, the reflective surface 57 includes a groove pattern surface 61 including a reflective groove portion 611 extending in a direction orthogonal to the longitudinal direction of the light guide 52 (sub-scanning direction, second direction), and a minute reflective concave portion. For example, the deflection pattern surfaces 62 provided with a large number of 621 are alternately provided (see FIG. 7).

  FIG. 4 is an explanatory diagram schematically showing a propagation state of illumination light in the light guide 52. Hereinafter, if the deflection pattern surface 62 is not provided, the way in which the illumination light spreads in the direction orthogonal to the longitudinal direction of the light guide 52 (sub-scanning direction) is the position of the light guide 52 in the longitudinal direction. The principle of non-uniformity due to the above will be described with reference to FIG.

  Illumination light enters the main body 53 from the light source 51 through the incident surface 54. Since the light source 51 is a point light source, the illumination light has a diffused light property. The incident illumination light basically proceeds in the direction of the far end surface 55 while repeating total reflection on the peripheral surface of the main body 53 based on the refractive index difference between the constituent material of the light guide 52 and air. However, illumination light is emitted from the emission surface 56 by providing the reflection surface 57 provided with a reflection pattern surface made of a V-shaped groove like the groove pattern surface 61 so as to face the emission surface 56. . Since the main body 53 has a bar shape that is long in the main scanning direction, the illumination light emitted from the light guide 52 becomes linear illumination light that is long in the main scanning direction.

  As described above, the illumination light emitted from the light guide 52 includes the direct light DL and the indirect light IL. The direct light DL is illumination light L1 that goes directly from the light source 51 to the reflection surface 57 and is emitted from the emission surface 56 when the illumination light L1 is reflected by the reflection surface 57. On the other hand, the indirect light IL is illumination light L <b> 2 that travels toward the reflection surface 57 after being totally reflected once or more on the peripheral surface of the main body 53, and is emitted by reflecting the illumination light L <b> 2 on the reflection surface 57. Light emitted from the light source 56. The direct light DL is emitted exclusively from the portion of the exit surface 56 close to the entrance surface 54.

  Conventionally, a reflection pattern surface formed on the reflection surface 57 is generally used as a V-shaped concave groove extending in the sub-scanning direction, similar to the reflection groove portion 611 (see FIG. 7). It is a minute groove that fulfills the same function. A reflection pattern in which a large number of such V-shaped groove prisms are arranged in the main scanning direction is widely used at present. However, a V-shaped groove prism such as the reflective groove 611 has a property of reflecting the light incident on the V-shaped groove prism as it is without deflecting in the sub-scanning direction. Therefore, when only the reflection groove portion 611 is formed on the reflection surface 57, the direct light DL and the indirect light IL are emitted light intensity distributions in the sub-scanning direction (light having a small change angle in the sub-scanning direction and light having a large change amount). The component ratio will be different.

  FIG. 5 is a graph showing the angular distribution of the light intensity in the sub-scanning direction of the direct light DL and the indirect light IL emitted from the light guide having the reflection pattern surface of the V-shaped prism. As is clear from FIG. 5, the direct light DL has sharper characteristics than the indirect light IL. FIG. 6 is a diagram schematically showing the intensity distributions of the direct light DL and the indirect light IL shown in the graph of FIG.

  When the direct light DL is viewed in the sub-scanning direction, the illumination light L1 directly directed from the light source 51 to the reflecting surface 57 (V-shaped groove prism) at a predetermined limited incident angle is directly unchanged by the V-shaped groove prism. Because it is reflected at the angle of, it does not diffuse so much. This is the reason why the intensity distribution of the direct light DL is sharp. On the other hand, the indirect light IL is light that is produced when the illumination light L2 having any incident angle by being totally reflected by the peripheral surface of the main body 53 is reflected by the V-shaped groove prism. Therefore, the intensity distribution of the indirect light IL is relatively broad and broad.

  Such a difference in the intensity distribution between the direct light DL and the indirect light IL causes a problem that the uniformity of the illumination light cannot be obtained in the longitudinal direction of the light guide 52. This is because the direct light DL is emitted exclusively from the portion close to the incident surface 54 as described above. If the intensity distribution of the illumination light is different in the main scanning direction, the amount of change in the amount of reflected light from the original sheet differs when the original sheet reading position is misaligned or when the original sheet is lifted off the contact glass. This causes reading density unevenness in the main scanning direction.

  In view of such a problem, in the present invention, the shape of the reflection pattern formed on the reflection surface 57 is devised. The reflection pattern is formed by alternately providing a groove pattern surface 61 including a reflection groove 611 recessed in a flat reflection surface 57 and a deflection pattern surface 62 provided with a large number of minute reflection recesses 621. (See FIG. 7). The reflective recess 621 includes a deflection surface 622 (see FIG. 9B) that reflects light by deflecting it in the direction in which the reflection angle increases.

  By providing such a deflection pattern surface 62, the illumination light incident on the reflective recess 621 is deflected and reflected by the deflection surface 622 in a direction in which the reflection angle is widened. For this reason, the reflection angle in the cross-sectional view of the direct light DL in the sub-scanning direction can be widened. Thereby, the property of the direct light DL can be brought close to the property of the indirect light IL, and the uniformity of the illumination light emitted from the emission surface 56 in the main scanning direction can be ensured.

  On the other hand, the deflection pattern surface 62 provided with a large number of reflection concave portions 621 can increase the reflected light in the sub-scanning direction. On the other hand, a gap is formed between the reflective recess 621 and the reflective recess 621, and light is not deflected in the direction of the emission surface 56 between the reflective recess 621 and the reflective recess 621. Therefore, it is not easy to emit a sufficient amount of illumination light from the emission surface 56 with only the deflection pattern surface 62.

  As described above, a sufficient amount of light cannot be obtained on the deflection pattern surface 62, so that it is not easy to adjust the amount of illumination light emitted from the emission surface 56 using the deflection pattern surface 62. As a result, it is not easy to make the brightness of the illumination light uniform in the longitudinal direction while securing the necessary light quantity.

  Therefore, the groove pattern surface 61 including the reflection groove portion 611 and the deflection pattern surface 62 are alternately arranged. The reflection groove 611 included in the groove pattern surface 61 is formed to extend across the light guide 52 in the sub-scanning direction. Therefore, the reflection groove 611 does not have a gap generated between the reflection recess 621 and the reflection recess 621, and light can be deflected in the direction of the emission surface 56 without leaking. Therefore, the groove pattern surface 61 can easily emit a sufficient amount of illumination light from the emission surface 56. The fact that a sufficient (large) amount of light can be easily emitted from the emission surface 56 means that there is a large room for adjusting the brightness of the illumination light emitted from the emission surface 56. .

  Therefore, according to the groove pattern surface 61, it is easy to adjust the brightness of the illumination light emitted from the emission surface 56 by the groove pattern surface 61 while ensuring the necessary light amount. As a result, the brightness of the illumination light It becomes easy to improve the uniformity of thickness.

  Hereinafter, a specific example of the reflection surface 57 will be described. FIG. 7 is a perspective view showing the vicinity of the incident surface 54 of the light guide 52 according to the present embodiment. Here, as an example of the reflection groove portion, a reflection groove portion 611 having a V-shaped recess is illustrated. Further, as an example of the reflective concave portion having the above-described deflection surface, a reflective concave portion 621 having a shape recessed in a triangular pyramid shape is illustrated.

  As described above with reference to FIG. 2, the illumination device 50 includes the light source 51 and the light guide 52. The light emitting surface of the light source 51 is opposed to the incident surface 54 of the light guide 52 in a contact state. FIG. 7 illustrates the light source 51 in a form in which six white LEDs 51L are arranged in a 2 × 3 matrix. The rod-shaped main body 53 of the light guide 52 includes an emission surface 56 that emits line-shaped illumination light toward the document sheet, and a reflection surface 57 that faces the emission surface 56.

  The reflection surface 57 is a flat surface, and has a plurality of groove pattern surfaces 61 and a plurality of deflection patterns having a function of reflecting the illumination light incident from the light source 51 into the light guide 52 toward the emission surface 56. Surface 62. The groove pattern surface 61 and the deflection pattern surface 62 are alternately arranged.

  FIG. 8 is an enlarged perspective view in which a part of the reflecting surface 57 shown in FIG. 7 is enlarged. The groove pattern surface 61 includes a plurality of, for example, three reflection groove portions 611. The reflection groove 611 is a recessed groove that is recessed in a V shape on the flat surface 57 a of the reflection surface 57. The groove pattern surface 61 includes a plurality of reflective groove portions 611 arranged in parallel at a pitch P1 interval.

  FIG. 9A is a cross-sectional view of the reflection groove 611 cut along the main scanning direction. As shown in FIG. 9A, the reflection groove 611 is a V-shaped groove having a width d1 and a depth h1. FIG. 10 is an explanatory diagram for explaining a light reflection state by the reflection groove portion 611.

  As shown in FIG. 10A, according to the reflection groove portion 611 formed of a V-shaped concave groove, the light beam emitted from the light source 51 can be efficiently reflected toward the emission surface 56. The reflection groove 611 may be a groove that extends in the sub-scanning direction and has a function of reflecting the illumination light toward the emission surface 56, and is not necessarily a V-shaped groove. For example, as shown in FIG. 10B, the reflection groove 611 may be configured by a semicircular concave groove, or may be a groove having another shape such as a semi-ellipse or an aspherical surface. .

  Since the reflecting groove 611 having a concave groove shape extending in the sub-scanning direction has a large reflecting surface area and can be easily arranged densely, it reflects the light beam emitted from the light source 51 toward the emitting surface 56 efficiently. Is easy.

  Referring to FIG. 8, the deflection pattern surface 62 includes a large number of reflective recesses 621. The reflective recesses 621 are arranged in one or more rows in the sub-scanning direction, for example, at a pitch P2.

  FIG. 9B is a front view of the reflective concave portion 621 viewed from the incident surface 54 side. FIG. 9C is a plan view of the reflective recess 621 viewed from the exit surface 56 side. The reflective recess 621 has a shape in which the flat surface 57a of the reflective surface 57 is recessed in a triangular pyramid shape. The width of the reflective recess 621 in the sub-scanning direction is d2, the length of the reflective recess 621 in the main scanning direction is a, and the depth of the reflective recess 621 from the flat surface 57a is h2.

  The vertex 621a, which is one of the three vertices of the triangular pyramid included in the flat surface 57a, is located closer to the incident surface 54 than the other two vertices 621b and 621c. As a result, at least one of the surfaces of the triangular pyramid becomes a deflection surface 622 arranged obliquely with respect to the main scanning direction, and the light emitted from the light source 51 is reflected and diffused in the sub scanning direction by the deflection surface 622. Can do.

  Further, the apex 621d of the triangular pyramid that is not included in the flat surface 57a is located at the approximate center of the apexes 621b and 621c in a plan view viewed from the exit surface 56 side, and a side 621e that connects the apex 621a and the apex 621d is provided. It is desirable to arrange them along the main scanning direction.

  When the reflective concave portion 621 is arranged in such a direction, the surfaces on both sides of the side 621e become the deflection surfaces 622 arranged obliquely with respect to the main scanning direction as shown in FIG. The two deflecting surfaces 622 can efficiently reflect and diffuse the light emitted from the light source 51 in the sub-scanning direction. In addition, the angle between the two deflection surfaces 622 with respect to the main scanning direction is substantially bilaterally symmetric with respect to the main scanning direction, so that the illumination light can be spread in a balanced manner in the sub-scanning direction.

  Note that the reflection recess 621 only needs to have a deflection surface that reflects and reflects the illumination light in a direction in which the reflection angle is widened in a cross-sectional view in the sub-scanning direction, and is not necessarily a triangular pyramid recess. Good. For example, as shown in FIG. 11B, the reflective concave portion 621 may have a shape in which the flat surface 57a of the reflective surface 57 is recessed in a semi-elliptical shape, or a concave portion having another shape such as a circular shape or an aspherical surface. There may be. A curved surface such as a semi-elliptical shape serves as a deflection surface because the illumination light is deflected and reflected in a direction in which the reflection angle is widened in a cross-sectional view in the sub-scanning direction.

  When the reflective recess 621 has a shape in which the flat surface 57a of the reflective surface 57 is recessed in a semi-elliptical shape as shown in FIG. 11B, it is desirable that the major axis direction extends in the sub-scanning direction. When the reflective recess 621 has a semi-elliptical shape, if the major axis direction extends in the sub-scanning direction, the light is emitted from the light source 51 by the wall surface (interface between the resin of the light guide 52 and the air) extending in the major axis direction of the ellipse. Can be taken to cross the light.

  As a result, the area for reflecting light is increased as compared with the case where the reflective concave portion 621 is arranged in the direction in which the minor axis direction extends in the sub-scanning direction, so that the light is effectively reflected and diffused by the reflective concave portion 621. be able to. Therefore, it is possible to reflect the illumination light by deflecting it in a direction in which the reflection angle increases in the cross-sectional view in the sub-scanning direction, and to increase the light component having a large reflection angle in the cross-sectional view in the sub-scanning direction. Become.

  Referring to FIG. 8, the thus configured deflection pattern surface 62 is disposed adjacent to groove pattern surface 61 in the main scanning direction, and the set of groove pattern surface 61 and deflection pattern surface 62 is a reflective surface. In 57, it arranges repeatedly for every predetermined interval P3.

  The greater the number of reflection groove portions 611 included in the groove pattern surface 61, the smaller the pitch P1, the wider the width d1 and the deeper the depth h1, the more light flux deflected by the groove pattern surface 61 toward the exit surface 56. The illumination light emitted from the emission surface 56 becomes brighter.

  On the other hand, the greater the number of reflective recesses 621 included in the deflection pattern surface 62, the smaller the pitch P2, the longer the length a, and the greater the depth h2 (if the width d2 is constant), the greater the deflection pattern surface. The reflection angle of the light deflected by 62 in the cross-sectional view in the sub-scanning direction is increased, and the light component having a large reflection angle in the cross-sectional view in the sub-scanning direction can be increased.

  Therefore, the number, the pitch P2, the width d2, the length a, and the depth h2 of the reflective recesses 621 included in the deflection pattern surface 62 are obtained experimentally, for example, at each position in the main scanning direction of the light guide 52. By appropriately setting, it is possible to make the way in which the illumination light spreads in the sub-scanning direction at the position of the light guide in the longitudinal direction uniform.

  Further, at each position in the main scanning direction of the light guide 52, the number, the pitch P1, the width d1, and the depth h1 of the reflection groove portions 611 included in the groove pattern surface 61 are obtained, for example, experimentally and set as appropriate. Thus, the brightness of the illumination light at the position in the longitudinal direction of the light guide can be made uniform.

  For example, it is difficult to make the illumination light spread in the sub-scanning direction uniform only by the groove pattern surface 61, and it is difficult to make the brightness of the illumination light uniform only by the deflection pattern surface 62. The light guide 52 shown in FIG. 7 includes a groove pattern surface 61 and a deflection pattern surface 62, thereby spreading and illuminating the illumination light in the sub-scanning direction at each position of the light guide 52 in the main scanning direction. It becomes easy to improve the uniformity of light brightness.

  Moreover, the groove pattern surface 61 and the deflection pattern surface 62 can be formed by performing fine processing of, for example, a depth of about 10 to 100 μm on the reflection surface 57 of the light guide 52. Therefore, the groove pattern surface 61 and the deflection pattern surface 62 can be formed without greatly changing the cross-sectional shape of the light guide 52 depending on the position in the main scanning direction. Therefore, the uniformity of how the illumination light spreads in the direction perpendicular to the longitudinal direction at the longitudinal position of the light guide is improved without greatly changing the cross-sectional shape of the light guide 52 depending on the position in the main scanning direction. Easy to do.

  Here, as described above, in the conventional light guide, the light closer to the incident surface has more direct light, and therefore the emitted illumination light is emitted in the sub-scanning direction than the position far from the incident surface. The ratio of light components having a narrow light distribution angle is increased. Therefore, in the light guide 52 according to the present embodiment, the light reflected by the reflective concave portion 621 and the reflective groove 611 are reflected closer to the incident surface 54, that is, near the incident surface 54 than near the far end surface 55. The ratio of the light reflected by the reflective recess 621 is increased. As a result, the uniformity of how the illumination light spreads in the direction orthogonal to the longitudinal direction of the light guide 52 can be improved.

  Specifically, for example, the closer to the incident surface 54, that is, in the vicinity of the incident surface 54 than in the vicinity of the far end surface 55, the number of the reflective groove portions 611 included in the groove pattern surface 61 is small, the pitch P 1 is wide, and the width d 1. By forming the groove pattern surface 61 so that the depth h1 is small and the depth h1 is shallow, the ratio of the light reflected by the reflective recess 621 and the light reflected by the reflective groove 611 is closer to the incident surface 54. The ratio of the light reflected by the reflective recess 621 can be increased.

  In particular, when the reflection groove portion 611 is formed so that the pitch P1 of the reflection groove portion 611 is wider near the incident surface 54, that is, in the vicinity of the incident surface 54 than in the vicinity of the far end surface 55, the reflection groove portion 611 in the vicinity of the incident surface 54 is formed. Density decreases. As a result, the closer to the incident surface 54, the higher the ratio of the light reflected by the reflective recess 621, so that the uniformity of how the illumination light spreads in the direction orthogonal to the longitudinal direction of the light guide 52 is improved. It is effective in improving.

  The light guide 52 can be obtained by injection molding using a translucent resin material, melting the resin material, and injecting it into a mold. In this case, the reflection groove 611 (groove pattern surface 61) and the reflection recess 621 (deflection pattern surface 62) described above correspond to the reflection groove 611 and the reflection recess 621 at portions corresponding to the reflection surface 57 of the mold, respectively. By providing a convex portion having a shape, it can be easily formed.

  FIG. 12 is a graph showing the measurement result of the illuminance distribution in the sub-scanning direction of the illumination light emitted from the emission surface 56 in the illumination device 50 shown in FIG. In FIG. 12, the horizontal axis indicates the distance in the sub-scanning direction from the center position when the center position in the sub-scanning direction of the emission surface 56 is zero. The vertical axis indicates the illuminance ratio when the illuminance peak value at the position where the illuminance is maximum is 1 among the positions.

  A graph indicated by a triangular mark indicates the illuminance of the illumination light emitted from the exit surface 56 at a position 90 mm from the entrance surface 54. The graph indicated by the square mark indicates the illuminance of the illumination light emitted from the exit surface 56 at a position 180 mm from the entrance surface 54. The graph indicated by the X mark indicates the illuminance of the illumination light emitted from the exit surface 56 at a position 240 mm from the entrance surface 54.

  The graph shown in FIG. 12 shows the number of reflection groove portions 611 included in the groove pattern surface 61, the pitch P1, the width d1, and the depth h1, the number of reflection recesses 621 included in the deflection pattern surface 62, the pitch P2, the width d2, Simulation result of illuminance distribution when length a, depth h2, and interval P3 are set as follows in the vicinity of the entrance surface 54, the vicinity of the center in the longitudinal direction of the light guide 52, and the vicinity of the far end surface 55, respectively. Is shown.

[Near incident surface 54]
Number of reflection groove portions 611 on the groove pattern surface 61: 5
・ Pitch P1: 300 μm
・ Width d1: 30 μm
-Depth h1: 15 μm
Number of reflection concave portions 621 included in the deflection pattern surface 62: 15
・ Pitch P2: 200 μm
・ Width d2: 30 μm
・ Length a: 50 μm
Depth h2: 15 μm
(On the reflection surface 57, the deflection pattern surface 62 is formed at a ratio of 1 with respect to the number 5 of the reflection groove portions 611).

[Near the center in the longitudinal direction]
Number of reflection groove portions 611 on the groove pattern surface 61: 10
・ Pitch P1: 150 μm
・ Width d1: 30 μm
-Depth h1: 15 μm
Number of reflection concave portions 621 included in the deflection pattern surface 62: 15
・ Pitch P2: 200 μm
・ Width d2: 30 μm
・ Length a: 50 μm
Depth h2: 15 μm
(On the reflection surface 57, the deflection pattern surface 62 is formed at a ratio of 1 to the number 10 of the reflection groove portions 611).

[Near the far end 55]
・ Pitch P1: 50 μm
・ Width d1: 30 μm
-Depth h1: 15 μm
-Reflective recess 621: None.

  As shown in FIG. 12, a 90 mm position (triangular mark) near the entrance surface 54, a position near the center in the longitudinal direction 180 mm from the entrance surface 54 (square mark), and a 240 mm distance from the entrance surface 54 near the far end surface 55. At the position (X mark), the illuminance of the illumination light emitted from the emission surface 56 could be made substantially the same. That is, according to the illuminating device 50 shown in FIG. 7, it was confirmed that the method of spreading the illumination light in the sub-scanning direction and the brightness of the illumination light at the longitudinal position of the light guide 52 can be made uniform.

  FIG. 13 is a graph showing the illuminance distribution according to the comparative example when the deflection pattern surface 62 is not provided. The graph shown in FIG. 13 is a simulation performed under the same conditions as the graph shown in FIG. 12 except that the light guide does not include the deflection pattern surface 62.

  As shown in FIG. 13, when the deflection pattern surface 62 is not provided, a 90 mm position (triangle mark) near the incident surface 54, a position near the center in the longitudinal direction 180 mm from the incident surface 54 (square mark), and the incident surface 54. The illuminance at a position near the far end surface 55 (X mark) of 240 mm from does not match. That is, as shown in FIG. 12, by providing the deflection pattern surface 62 in addition to the groove pattern surface 61, the illumination light is spread and illuminated in the sub-scanning direction at the longitudinal position of the light guide 52. It was confirmed that the brightness of the light could be made uniform.

1 Image forming apparatus 11 Photosensitive drum (image carrier)
22 Image reading device 229 Image sensor (light receiving device)
50 Illumination device 51 Light source 51L White LED
52 Light guide 53 Main body 54 Incident surface 55 Far end surface 56 Outgoing surface 57 Reflective surface 57a Flat surface 61 Groove pattern surface 62 Deflection pattern surface 611 Reflective groove portions 621a, 621b, 621c, 621d Vertex 621 Reflective recess 621e Side 622 Deflection Surface DL Direct light IL Indirect light P1 Pitch (interval)
P2 pitch P3 interval

Claims (10)

A light guide used in combination with a light source that emits illumination light,
A main body having a long rod shape in the first direction and guiding the illumination light;
An incident surface which is one end surface of the main body and on which the illumination light is incident;
A strip-shaped exit surface that extends along the first direction on the surface of the main body and emits the illumination light;
A strip-shaped reflecting surface that extends along the first direction on the surface of the main body portion facing the emitting surface and reflects the illumination light;
The reflective surface is
A groove pattern surface having a function of reflecting the illumination light toward the emission surface, and a reflection groove portion extending in a second direction orthogonal to the first direction is formed on a flat surface;
A deflection pattern surface having a function of reflecting the illumination light toward the exit surface, wherein a deflection surface is formed to reflect the illumination light by deflecting the illumination light in a direction in which a reflection angle is widened in a cross-sectional view in the second direction; Including
A light guide in which the groove pattern surface and the deflection pattern surface are arranged along the first direction. The plurality of groove pattern surfaces and the plurality of deflection pattern surfaces are mixed along the first direction,
The ratio of the light reflected by the groove pattern surface and the light reflected by the deflection pattern surface in the vicinity of the incident surface is reflected by the deflection pattern surface rather than the ratio in the vicinity of the other end surface of the main body. The light guide according to claim 1, wherein the light ratio is large. Each of the plurality of groove pattern surfaces includes a plurality of the reflection groove portions formed in parallel at a predetermined interval,
The light guide according to claim 2, wherein the interval in the groove pattern surface formed in the vicinity of the incident surface is wider than the interval in the groove pattern surface formed in the vicinity of the other end surface of the main body portion.   The light guide according to any one of claims 1 to 3, wherein the deflection pattern surface includes a minute reflective recess having the deflection surface.   The reflective recess has a shape in which a flat surface of the reflective surface is recessed in a triangular pyramid shape, and one of the three vertices of the triangular pyramid included in the flat surface is more than the other two vertices. The light guide body according to claim 4, which is located at a position close to the incident surface.   The reflection concave portion has a vertex of the triangular pyramid that is not included in the flat surface, is located at a substantially center of the other two vertices in a plan view as viewed from the exit surface side, and is in the flat surface. The light guide according to claim 5, wherein a side connecting the vertex that is not included and the one vertex is along the first direction in a plan view seen from the emission surface side.   The light guide according to claim 4, wherein the reflective recess has a semi-ellipsoidal shape, and a major axis direction thereof extends in the second direction.   The light guide according to any one of claims 1 to 7, wherein the light guide is made of a member obtained by molding a translucent resin material. A light source that emits illumination light;
An illumination device comprising: the light guide according to claim 1. The illumination device according to claim 9, which illuminates an original sheet with illumination light;
A light receiving device that receives reflected light from the original sheet and converts it into an electrical signal;
An image carrier on which an electrostatic latent image is formed on the peripheral surface based on image data output from the light receiving device;
An image forming apparatus in which the first direction is a main scanning direction and the second direction is a sub-scanning direction.

Images