JP6264280B2 - Light guide, illumination device, and image forming apparatus - Google Patents

Description

  The present invention relates to an illuminating device, an image forming apparatus, and an image reading apparatus using a light guide, and more particularly to a technique for diffusing light incident on the inside of a light guide.

  In an image forming apparatus, the surface of a photoconductor (image carrier) is uniformly charged, the surface of the photoconductor is exposed to form an electrostatic latent image on the surface of the photoconductor, and the surface of the photoconductor is developed with toner (developer). The electrostatic latent image is developed to form a toner image (visible image) on the surface of the photoconductor, the toner image is transferred from the surface of the photoconductor to the recording paper (recording medium), and the toner image on the recording paper is thermocompression bonded. To fix.

  Here, if the potential difference of the electrostatic latent image previously formed on the surface of the photosensitive member remains, so-called drum ghost is generated, and the image quality is deteriorated. In order to prevent this, it is effective to irradiate the surface of the photosensitive member with light before the charging step for charging the surface of the photosensitive member to neutralize the surface of the photosensitive member, and an illumination device for this purpose is provided.

  For example, as a lighting device, a light source composed of a light emitting element such as an LED (Light Emitting Diode) and a light-transmitting rod-shaped light guide are combined, and light from the light source is incident on the light guide to guide the light. Some employ a line light source that emits light to the side of the light guide.

  Patent Document 1 discloses an illumination device having such a configuration. Here, a plurality of reflective grooves having a triangular cross-sectional shape are formed side by side on one side of the light guide, and the light inside the light guide is diffused by each of the reflective grooves, and the light guide is opposed to the one side. Light is emitted from the other side surface of the document, and the original is illuminated by this light.

  The illumination device of Patent Document 1 is used to illuminate a document, but can also be applied to charge removal on the surface of a photoreceptor.

JP 2003-295717 A

  By the way, the light guide is generally molded by injection injection of a synthetic resin (for example, PMMA; Polymethly methacrylate, ABS; Acrylonitrile butadiene styrene, etc.) heated and melted in the space of the mold.

  On the other hand, in order to uniformly illuminate the surface of the photosensitive member with the light emitted from the light guide, light must be diffused well by a plurality of reflection grooves formed on the side surface of the light guide. A minute reflection groove is provided, or the inclination angle of the inner wall of the reflection groove is appropriately adjusted.

  However, when forming a minute reflection groove with a mold, a minute unevenness for forming the minute reflection groove is provided inside the mold, but inside the mold, it is synthesized at every corner of the minute unevenness. In some cases, the resin was not filled, and a defective molding of the reflective groove occurred. Specifically, the edge of the reflection groove becomes round, and the light diffusion state by the reflection groove varies and becomes unstable.

  If such a variation in the light diffusion state due to the reflection groove occurs, the light diffusion state is as designed even if the shape of the reflection groove is properly set using optical simulation at the light guide design stage. As a result, even if the light emitted from the light guide is irradiated on the surface of the photoconductor, the surface of the photoconductor is not uniformly illuminated, and the charge on the surface of the photoconductor is uneven. The quality has deteriorated.

  The illumination device disclosed in Patent Document 1 also causes unevenness in illumination of the document by the light emitted from the light guide due to a defective molding of the reflection groove due to the mold not being filled with synthetic resin, and the image reading device reads the illumination device. There is a possibility that density unevenness occurs in the image of the original document and unevenness occurs in the image printed on the recording paper, leading to deterioration of image quality.

  The present invention has been made in view of the above circumstances, and although it has a simple configuration, the light diffusion state inside the light guide can be stably reproduced as designed, resulting in degradation of image quality. It aims to reduce the risk of incurring.

The light guide according to one aspect of the present invention is a light-transmitting rod-shaped light guide that receives light from a light source disposed at an end in a longitudinal direction,
A diffusion side portion for diffusing light incident on the inside of the light guide through the end from the light source, and an emission side portion for emitting the light to the outside of the light guide,
The diffusion side portion has a plurality of reflection grooves formed side by side in the longitudinal direction of the light guide,
One of both opposing inner walls of the reflection groove is bent in the depth direction of the reflection groove at a first corner between the valley and the edge of the reflection groove, and a second corner of the edge. Bent in the depth direction at a portion, and formed by a first inclined surface from the valley portion to the first corner portion, and a second inclined surface from the first corner portion to the second corner portion. And
The other of the inner walls on both sides is formed by a third inclined surface from the valley to the edge of the reflection groove .

An illumination device according to one aspect of the present invention includes the light guide body,
And a light source disposed at an end portion in the longitudinal direction of the light guide.

An image forming apparatus according to one aspect of the present invention includes the above-described illumination device,
An image carrier that is neutralized by light emitted from the light exit side of the light guide of the illumination device, forms a latent image on the surface of the image carrier, and develops the latent image into a visible image; And an image forming section for recording the visible image on a recording medium.

  According to the present invention described above, the light diffusion state inside the light guide can be stably reproduced as designed, with a simple structure, and image quality is not deteriorated.

1 is a front sectional view showing a structure of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is an internal side view illustrating a schematic configuration of an image reading device in the image forming apparatus of FIG. 1. FIG. 2 is a perspective view schematically showing an illumination device provided in an image forming unit in the image forming apparatus of FIG. 1. It is sectional drawing which shows the illuminating device of FIG. 3 roughly. It is a perspective view which expands and shows a part of light guide in the illuminating device of FIG. It is sectional drawing which shows the reflective groove of the light guide of a comparative example. It is sectional drawing which shows the shaping | molding defect of the reflective groove of the light guide of FIG. It is sectional drawing which expands and shows the reflective groove of the light guide in the illuminating device of FIG. It is the figure used in order to demonstrate the reflective groove of the light guide in the illuminating device of FIG.

  Hereinafter, a light guide, an illumination device, and an image forming apparatus according to embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a front sectional view showing the structure of an image forming apparatus according to an embodiment of the present invention. An image forming apparatus 1 according to an embodiment of the present invention is a multifunction machine having a plurality of functions such as a copy function, a printer function, a scanner function, and a facsimile function. The image forming apparatus 1 includes an operation unit 47, an image forming unit 120, a fixing unit 13, a paper feeding unit 14, a document feeding unit 6, an image reading unit (ISU; Image scanner unit) 5 and the like in the apparatus main body 2. Configured.

  The operation unit 47 receives instructions such as an image forming operation execution instruction and an image reading operation execution instruction from the operator regarding various operations and processes that can be executed by the image forming apparatus 1. The operation unit 47 includes a display unit 473 that displays operation guidance to the operator.

  When the image forming apparatus 1 performs an image reading operation, the image reading apparatus 5 displays an image of a document fed by the document feeding unit 6 or a document placed on a contact glass (document placing glass) 161. Optically read to generate image data. Image data generated by the image reading device 5 is stored in a built-in HDD or a computer connected to a network.

  When the image forming apparatus 1 performs an image forming operation, the image data generated by the image reading operation described above, image data received from a user terminal device such as a network-connected computer or smartphone, or the built-in HDD is stored. The image forming unit 120 forms a toner image on a recording paper P as a recording medium fed from the paper feeding unit 14 based on the image data and the like.

  The image forming units 12M, 12C, 12Y, and 12Bk of the image forming unit 120 are a photosensitive drum 122, an illumination device that irradiates light on the surface of the photosensitive drum 122, and neutralizes the surface, and the photosensitive drum 122. A charging device that uniformly charges the surface of the photosensitive drum 122, an exposure device that exposes the surface of the photosensitive drum 122 to form an electrostatic latent image on the surface, and a surface of the photosensitive drum 122. A developing device that supplies toner and develops the electrostatic latent image into a toner image, a toner cartridge (not shown) that contains the toner, and a primary transfer roller 126 are provided.

  When performing color printing, in the magenta image forming unit 12M, the cyan image forming unit 12C, the yellow image forming unit 12Y, and the black image forming unit 12Bk of the image forming unit 120, the photosensitive drum 122 is used. The surface of the photosensitive drum 122 is once charged and then uniformly charged, and the surface of the photosensitive drum 122 is exposed to form an electrostatic latent image corresponding to the color component image on the surface. The electrostatic latent image is developed with toner of the color component to form a toner image on the photosensitive drum 122, and the toner image is stretched between the driving roller 125A and the driven roller 125B by the primary transfer roller 126. The image is transferred onto the intermediate transfer belt 125.

  The intermediate transfer belt 125 is driven by a driving roller 125 </ b> A in a state where an image carrying surface on which a toner image is transferred is set on the outer circumferential surface thereof and in contact with the circumferential surface of the photosensitive drum 122. The intermediate transfer belt 125 runs endlessly between the driving roller 125A and the driven roller 125B while being synchronized with each photosensitive drum 122.

  The toner images of the respective color components transferred onto the intermediate transfer belt 125 are superimposed on the intermediate transfer belt 125 with the transfer timing adjusted to become a color toner image. The secondary transfer roller 210 conveys the color toner image formed on the surface of the intermediate transfer belt 125 from the sheet feeding unit 14 through the conveyance path 190 at the nip N between the intermediate transfer belt 125 and the driving roller 125A. The recording sheet P is transferred. Thereafter, the fixing unit 13 fixes the toner image on the recording paper P to the recording paper P by thermocompression bonding. The recording paper P on which the color image has been formed after completion of the fixing process is discharged to a discharge tray 151.

  The paper feed unit 14 includes a plurality of paper feed cassettes. The control unit (not shown) rotates the pickup roller 145 of the paper feed cassette in which the recording paper P of the size specified by the instruction from the operator is rotated, and the recording paper P contained in each paper feed cassette. Is conveyed toward the nip portion N.

  Next, the configuration of the image reading apparatus will be described. FIG. 2 is an internal side view showing a schematic configuration of the image reading device 5.

  The image reading device 5 includes an optical scanning device 7 and an imaging unit 8 as shown in FIG.

  The optical scanning device 7 includes a first optical system unit 71 and a second optical system unit 72. The first optical system unit 71 includes the illumination device 10 and a first mirror 711. The illuminating device 10 is disposed below and facing the contact glass 161 so as to irradiate the reading surface of the original, that is, upward.

  The first mirror 711 receives the reflected light from the image reading surface of the light irradiated by the illumination device 10 on the document placed on the contact glass 161 and changes the direction in the horizontal direction. The first mirror 711 is disposed below the contact glass 161. The illumination device 10 and the first mirror 711 are attached to a support member (not shown).

  The second optical system unit 72 includes a second mirror 721 and a third mirror 722. The second mirror 721 receives the light reflected by the first mirror 711 of the first optical system unit 71 and further changes the direction downward substantially vertically. The third mirror 722 further changes the direction of the light reflected by the second mirror 721 substantially horizontally and guides the light toward the imaging unit 8. The second mirror 721 and the third mirror 722 are attached to a support member (not shown).

  The illumination device 10 and each of the mirrors provided in the first optical system unit 71 and the second optical system unit 72 have an elongated shape extending in the main scanning direction with substantially the same length as the contact glass 161.

  Inside the image reading device 5, a movement rail (not shown) for guiding the movement of the optical scanning device 7 in the direction of the arrow in the figure is provided. As a result, the optical scanning device 7 including the first optical system unit 71 and the second optical system unit 72 is parallel to the surface of the contact glass 161 so as to read image information on the entire reading surface of the document placed on the contact glass 161. In addition, it is possible to reciprocate in the sub-scanning direction (direction orthogonal to the main scanning direction), that is, in the direction of the arrow in the figure.

  The imaging unit 8 is fixed to the inside lower part of the image reading device 5. The imaging unit 8 includes an imaging lens 81 that is an optical member, and an image sensor 82 that includes a light receiving element. Reflected light from the reading surface of the document reflected by the third mirror 722 of the second optical system unit 72 is incident on the imaging lens 81. The imaging lens 81 forms an image of the reflected light on the surface of the image sensor 82 provided on the downstream side of the optical path. The image sensor 82 generates a signal indicating the amount of light according to the amount of light received by the light receiving element for each color component of the document color, and outputs the signal to a control unit (not shown). When the signal from the image sensor 82 is input, the control unit generates image data indicating an image of each color component and outputs the image data to the exposure devices of the image forming units 12M, 12C, 12Y, and 12Bk of the image forming apparatus 1. .

  In the image forming units 12M, 12C, 12Y, and 12Bk, the surface of the photosensitive drum 122 is exposed by the exposure device according to the image data, and the electrostatic latent image corresponding to the image of the color component of the original color is exposed on the surface. An image is formed and development and transfer as described above are performed.

  Next, an illuminating device for neutralizing the surface of the photosensitive drum 122 in the image forming units 12M, 12C, 12Y, and 12Bk will be described.

  FIG. 3 is a perspective view schematically showing an illumination device provided in the image forming units 12M, 12C, 12Y, and 12Bk. 4 is a cross-sectional view schematically showing the lighting device, and FIG. 5 is an enlarged perspective view showing a part of the light guide in the lighting device.

  As shown in FIGS. 3 to 5, the lighting device 51 includes a light-transmitting rod-shaped light guide 52 and a light source 53 disposed at the incident end 54 in the longitudinal direction of the light guide 52. The light guide 52 is disposed in parallel with the photosensitive drum 122. Light from the light source 53 enters the light guide 52 from the incident end 54 of the light guide 52 and is guided, and is irradiated on the surface of the photosensitive drum 122 from the emission side 55 of the light guide 52. The As a result, the surface of the photosensitive drum 122 is neutralized, and the previously formed electrostatic latent image is erased.

  The light guide 52 is disposed in parallel with the photosensitive drum 122 and extends in the main scanning direction. In addition, the longitudinal direction of the light guide 52 matches the optical axis direction of the light emitted from the light source 53. Accordingly, the longitudinal direction and the optical axis direction of the light guide 52 coincide with the main scanning direction. The light guide 52 is made of, for example, a light-transmitting synthetic resin (PMMA, ABS, etc.), and has an incident end portion 54, an emission side portion 55, and a diffusion side portion (reflection surface) 56. . The light guide 52 is molded by, for example, injecting and injecting a heat-melted synthetic resin into a mold (so-called injection molding).

  The incident end portion 54 is an end surface of the light guide 52 on which light emitted from the light source 53 is incident, and at least one end surface of both side end surfaces in the longitudinal direction of the light guide 52 is the incident end portion. In the present embodiment, a mode in which only one end surface of both side end surfaces is the incident end portion 54 will be described.

  The emission side portion 55 forms a side surface of the light guide 52 that extends in the longitudinal direction (main scanning direction) of the light guide 52. Light that has entered the light guide 52 from the incident end portion 54 is diffused by the diffusion side portion 56, and the diffused light is emitted from the emission side portion 55 to the outside of the light guide 52.

  The diffusion side portion 56 is provided on another side surface of the light guide 52 facing the emission side portion 55, and extends in the longitudinal direction (main scanning direction) of the light guide 52. The diffusion side portion 56 has a plurality of reflection grooves 57 formed side by side in the longitudinal direction, and each reflection groove 57 extends in a direction intersecting the longitudinal direction. The diffusion side portion 56 diffuses the light incident from the incident end portion 54 into the light guide 52 through the respective reflection grooves 57. The diffused light is applied to the surface of the photosensitive drum 122 from the emission side portion 55. The height and width of the reflection groove 57 in the depth direction are, for example, about 20 μm and 25 μm.

  The light source 53 is made of, for example, an LED, and is attached to the surface of the incident end portion 54 of the light guide 52.

  By the way, the light guide is for illuminating the surface of the photosensitive drum to remove the charge on the surface of the photosensitive drum, but conventionally, the surface is not necessarily uniformly discharged and unevenness occurs. The image quality sometimes deteriorated.

  Therefore, the inventors of the present application have investigated the cause of such unevenness of static elimination, and there is unevenness in the illumination by the light guide, and this unevenness in illumination is a variation in the light diffusion state by the reflection groove of the lightguide. It has been found that the problem is caused by defective molding of the reflection groove.

  In other words, the mold is provided with minute irregularities for molding the reflection grooves, but if the corners (corners, etc.) of the minute irregularities are not filled with synthetic resin, the molding of the reflection grooves is poor. As a result, the light diffusion state varies due to the reflection grooves, and the illumination on the surface of the photosensitive drum is also uneven.

  FIG. 6 is a cross-sectional view showing the reflection groove 202 of the light guide 201 of the comparative example. The cross-sectional shape of the reflection groove 202 of this comparative example is set to a simple triangle. Therefore, in order to widen the inner wall of the reflection groove 202 and improve the light diffusion state, the angle of the opposite corners 203 and 204 of the reflection groove 202 is decreased, and the height of the triangle is increased. Need to be high. Here, the angle is set to 135 ° or less.

  However, when the angles of the opposite corners 203 and 204 of the reflection groove 202 are set to 135 ° or less, a mold 205 for molding the corners 203 and 204 as shown in FIG. The recesses 206 and 207 are not easily filled with synthetic resin, and a gap with a height of about 1 μ and a width of about 15 to 20 μ is formed in the vicinity of the recesses 206 and 207, and the corners 203 and 204 are rounded. The inclined surface of the reflection groove 202 becomes narrow, the amount of light reflected by the reflection groove 202 is reduced, and the light diffusion state by the reflection groove 202 varies and becomes unstable. As a result, the surface of the photosensitive drum 122 is non-uniformly discharged, and the image quality is deteriorated. In FIG. 7, the height and width are not shown in the numerical values for the sake of simplicity.

  Therefore, as a result of earnest research, the inventor of the present application devised the cross-sectional shape of the reflection groove 57 of the light guide 52 to prevent the formation of the reflection groove 57 in advance. Thereby, the diffusion state of the light by the reflection groove 57 can be stably reproduced, and the surface of the photosensitive drum 122 can be uniformly neutralized to reduce image quality deterioration.

  In addition, it is possible to reduce the molding defects of the reflective grooves by increasing the amount of synthetic resin injected and injected into the mold or lengthening the molding time. It will not be.

  Next, the reflection groove 57 of the diffusion side portion 56 of the light guide 52 in the present embodiment will be described in detail. FIG. 8 is an enlarged cross-sectional view showing one reflection groove 57.

  The reflection groove 57 is formed on the side surface 59 of the light guide 52, and has a V-shaped valley portion 57a, a first edge portion 57b, and a second edge portion 57c.

  One inner wall from the trough portion 57a to the first edge portion 57b is bent in the depth direction of the reflection groove 57 at the first corner portion 57d between the trough portion 57a and the first edge portion 57b. The second corner portion 57e of the edge portion 57b is also bent in the depth direction, the valley portion 57a to the first corner portion 57d become the first inclined surface 57f, and the first corner portion 57d to the second corner portion 57e. It becomes the 2nd inclined surface 57g. The first inclined surface 57f and the second inclined surface 57g are prism surfaces that reflect and diffuse light in the direction from the inside of the light guide 52 to the outside.

  The other inner wall from the valley portion 57a to the second edge portion 57c is bent in the depth direction only at the third corner portion 57h of the second edge portion 57c to form a flat third inclined surface 57i. Similar to the first inclined surface 57f and the second inclined surface 57g, it is a prism surface that reflects and diffuses light in the direction from the inside of the light guide 52 to the outside.

  In the reflection groove 57 having such a configuration, the valley 57a reaches the first edge 57b via the first corner 57d and the second corner 57e. That is, the inner wall of the reflection groove 57 is formed from the valley 57a to the first edge 57b. Since the two corners are bent twice by one edge 57b, the angle of the first corner 57d and the angle of the second corner 57e are set large (an angle exceeding 135 °), and the reflection groove 57 By increasing the height (depth), the width of the inner wall (prism surface) of the reflection groove 57 can be maintained, and the light diffusion state is improved.

  In addition, the inclination of the third inclined surface 57i is adjusted as appropriate so that the angle of the third corner 57h of the second edge 57c does not become too small (an angle exceeding 135 °).

In the present embodiment, for example, all the angles of the first corner 57d, the second corner 57e, and the third corner 57h are set to an angle exceeding 135 °, and more preferably set to an angle exceeding 150 °. ing.

  Here, as described above, the light guide 52 is formed by injecting and injecting a heat-melted synthetic resin into a mold, and the inside of the mold has corners (corners) of the reflection grooves 57. Part) is formed, the corners of the minute unevenness tend to be difficult to be filled with synthetic resin.

  However, in the present embodiment, since all the angles of the first corner 57d, the second corner 57e, and the third corner 57h are set to an angle exceeding 135 °, these corners 57d, 57e, The recesses inside the mold for molding 57h are easily filled with synthetic resin, and no voids are formed in the recesses, and these corners 57d, 57e, 57h can be formed satisfactorily.

  For this reason, for example, if the shape of the reflection groove 57 is appropriately set using an optical simulation at the design stage of the light guide 52, the shape of the appropriate reflection groove 57 is surely reproduced, and the reflection groove 57 The amount of reflected light is stable, and the light diffusion state by the reflection groove 57 can be made as designed. As a result, the surface of the photosensitive drum 122 can be uniformly illuminated by the light emitted from the light guide 52, and the surface of the photosensitive drum 122 can be satisfactorily discharged, thereby preventing image quality deterioration. Become.

  On the other hand, in the comparative example described above, since the angles of the opposite corners 203 and 204 of the reflection groove 202 of the light guide 201 are set to 135 ° or less, the corners 203 and 204 are It is difficult to fill the recesses 206 and 207 inside the mold 205 for molding with synthetic resin, and a gap having a height of about 1 μm and a width of about 15 to 20 μm is formed in the vicinity of the recesses 206 and 207, 203 and 204 become round, and the light diffusion state by the reflection grooves 202 varies and becomes unstable.

  The illuminating device of the present invention can be applied not only for neutralizing the surface of the photosensitive drum in the image forming unit, but also as the illuminating device 10 of the first optical system unit 71 in the image reading device 5.

That is, the lighting device 10 is provided with a light-transmitting rod-shaped light guide 52 and a light source 53 disposed at an incident end 54 in the longitudinal direction of the light guide 52, so that the length of the light guide 52 is increased. The direction is made to coincide with the main scanning direction, the light of the light source 53 is incident on the incident end portion 54 of the light guide 52 and guided, and the light is diffused by the diffusion side portion 56 of the light guide 52, Light is emitted from the emission side portion 55 of the light guide 52, the light is irradiated onto the original through the contact glass 161, the original is illuminated, and the original is read by the image sensor 82. In this case, since the original is uniformly illuminated by the light emitted from the light guide 52, density unevenness may occur in the read image of the original, and unevenness may also occur in the image printed on the recording paper. Reduced.

  Further, the present invention is not limited to the configuration of the above embodiment, and various modifications can be made.

  <Modification 1>

  In the first modification, when the height of the second inclined surface 57g in the depth direction of the reflection groove 57 is A and the width of the second inclined surface 57g in the longitudinal direction of the light guide 52 is B as shown in FIG. The height A of the second inclined surface 57g is increased and the width B of the second inclined surface 57g is increased in the reflective groove 57 located farther from the gate of the mold into which the synthetic resin is injected.

  This is because the filling pressure of the synthetic resin decreases as the distance from the gate into which the synthetic resin is injected inside the mold, and molding defects of the reflection groove 57 are likely to occur. As a result of experiments, when the height A of the second inclined surface 57g is increased and the width B of the second inclined surface 57g is set wider as the reflecting groove 57 is located farther from the gate of the mold into which the synthetic resin is injected, It was confirmed that the molding failure of the groove 57 can be prevented.

  The gate into which the synthetic resin is injected can be confirmed based on the burr of the light guide 52 or the like.

  <Modification 2>

  In the second modification, the angle of the second corner portion 57e of the reflection groove 57 is increased as the distance from the gate of the mold into which the synthetic resin is injected is increased.

  This is because, within the mold, as the distance from the gate into which the synthetic resin is injected, the filling pressure of the synthetic resin decreases and the molding of the reflective groove 57 is likely to occur, but as the distance from the mold gate increases, If the angle of the second corner portion 57e of the reflection groove 57 is set large, the synthetic resin is surely placed in the recess inside the mold for molding the second corner portion 57e even if the filling pressure of the synthetic resin is lowered. This is because it can be filled to prevent the molding failure of the reflective groove 57.

  <Modification 3>

  In the third modification, the third inclined surface 57i of the reflective groove 57 is directed toward the gate of the mold into which the synthetic resin is injected, and the first inclined surface 57f and the second inclined surface 57g of the reflective groove 57 are the gates. Turn in the opposite direction.

  This is because the angle of the third corner 57h related to the third inclined surface 57i is larger than the angle of the first corner 57d related to the first inclined surface 57f and the angle of the second corner 57e related to the second inclined surface 57g. Since it is small, molding defects tend to occur near the third corner 57h. Therefore, the third inclined surface 57i of the reflection groove 57 is directed toward the gate of the mold into which the synthetic resin is injected. In order to prevent molding defects in the vicinity of the third corner portion 57h, the filling pressure of the synthetic resin is higher in the vicinity of the corner portion 57h than in the vicinity of the first corner portion 57d and the second corner portion 57e. is there.

  <Modification 4>

  In the modification 4, instead of the third inclined surface 57i of the reflection groove 57, a first inclined surface 57f and a second inclined surface 57g are provided. That is, the first inclined surface 57f and the second inclined surface 57g are provided on both inner walls of the reflecting groove 57 facing each other. In this case, the first corner portion 57d and the second corner portion 57e having an angle larger than that of the third corner portion 57h can be provided on any of the inner walls on both sides, and the molding failure of the reflection groove 57 is less likely to occur. .

  <Modification 5>

  In the modified example 5, the inner wall of the reflection groove 57 is formed by three or more similar inclined surfaces, and three or more similar corner portions that are bent in the depth direction are provided. Thereby, each corner | angular part becomes larger and it becomes difficult to produce the shaping | molding defect of the reflective groove 57 more.

  In addition, this invention is not restricted to the structure of the said embodiment and modification. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are of course within the technical scope of the present invention. Is done.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 5 Image reading apparatus 10, 51 Illumination device 52 Light guide 53 Light source 54 Incident end 55 Emission side 56 Diffusion side 57 Reflection groove 57a Valley 57b First edge 57c Second edge 57d First Corner 57e Second corner 57f First inclined surface 57g Second inclined surface 57h Third corner 57i Third inclined surface 59 Side surface

Claims (8)

It is a light guide that has a light-transmitting rod shape and receives light from a light source disposed at an end in the longitudinal direction,
A diffusion side portion for diffusing light incident on the inside of the light guide through the end from the light source, and an emission side portion for emitting the light to the outside of the light guide,
The diffusion side portion has a plurality of reflection grooves formed side by side in the longitudinal direction of the light guide,
One of both opposing inner walls of the reflection groove is bent in the depth direction of the reflection groove at a first corner between the valley and the edge of the reflection groove, and a second corner of the edge. Bent in the depth direction at a portion, and formed by a first inclined surface from the valley portion to the first corner portion, and a second inclined surface from the first corner portion to the second corner portion. And
The other of the inner walls on both sides is a light guide formed by a third inclined surface from a valley portion to an edge portion of the reflection groove . It is a light guide that has a light-transmitting rod shape and receives light from a light source disposed at an end in the longitudinal direction,
It is a molded product of synthetic resin with a mold,
A diffusion side portion for diffusing light incident on the inside of the light guide through the end from the light source, and an emission side portion for emitting the light to the outside of the light guide,
The diffusion side portion has a plurality of reflection grooves formed side by side in the longitudinal direction of the light guide,
One of both opposing inner walls of the reflection groove is bent in the depth direction of the reflection groove at a first corner between the valley and the edge of the reflection groove, and a second corner of the edge. Is bent in the depth direction at the portion,
The angle of the first corner and the angle of the second corner both are angles exceeding 135 °. The trough portion of the reflection groove has a V-shaped cross-sectional shape,
One of both opposing inner walls of the reflection groove is formed by a first inclined surface from the valley portion to the first corner portion, and a second inclined surface from the first corner portion to the second corner portion. The light guide according to claim 2 . It is a molded product of synthetic resin with a mold,
The higher the synthetic resin is separated from the gate of the mold to be injected, the height of the second inclined surface is high, according to claim 1 or claim 3 width of the second inclined surface is wider Light guide. It is a molded product of synthetic resin with a mold,
The light guide according to claim 1 or 3 , wherein an angle of the second corner portion is increased as the distance from the gate of the mold into which the synthetic resin is injected is increased. It is a molded product of synthetic resin with a mold,
One of both opposing inner walls of the reflection groove is formed by the first inclined surface and the second inclined surface, and the other of the both inner walls is a third inclined surface from a valley portion to an edge portion of the reflection groove. Formed,
The light guide according to claim 1, wherein the third inclined surface faces the gate side of the mold. A light guide according to any one of claims 1 to 6 ,
An illumination device comprising: a light source disposed at an end portion in a longitudinal direction of the light guide. A lighting device according to claim 7 ;
An image carrier that is neutralized by light emitted from the light exit side of the light guide of the illumination device, forms a latent image on the surface of the image carrier, and develops the latent image into a visible image; An image forming apparatus comprising: an image forming unit that records the visible image on a recording medium.