JP2014235882A - Transparent material and lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To equalize illumination distribution of a direct light and an indirect light in a vertical scanning direction in irradiation to a manuscript copy in each position of a main scanning direction without altering an outer shape of a transparent material.SOLUTION: A transparent material 11 comprises: an entrance plane 18 which light irradiated from a light source 12 enters; an emission plane 17 extending to a main scanning direction and emitting the entered light; and a reflective plane 15 extending to the main scanning direction in a position facing to the emission plane 17 and being formed multiple light reflex patterns 16 making the entered light reflect to the emission plane 17. In the light reflex pattern 16, a vertical scanning direction first diameter has a length not less than a second diameter in the main scanning direction. The light reflex pattern 16 is a semiellipse-shape projecting to the emission plane 17, and a ratio of the first diameter for a height of the semiellipse-shape is formed to be different on the basis of an arrangement position in the main scanning direction on the reflective plane 15.

Description

  The present invention relates to a light guide and an illumination device, and more particularly to a technique for reflecting light incident on a light guide toward an exit surface.

  In an image forming apparatus such as a multifunction machine, as a light source unit of an image reading apparatus such as a scanner, a rod-shaped resin light guide and an LED that emits light from the side in the length direction of the light guide to the inside of the light guide Some use a line light source that combines the above. The light source unit needs to illuminate the document to be read in a line in accordance with the reading of the line sensor. For this purpose, a light reflection or light scattering pattern is provided on the surface facing the exit surface for emitting light from the light guide, and the light incident on the light guide toward the exit surface is deflected by the pattern, Line-shaped illumination light is emitted in a direction toward the document.

  Here, in the combination of the rod-shaped light guide and the LED, the direct light directly reflected from the LED by the light reflecting or diffusing pattern surface and the light reflecting or diffusing pattern surface by being totally reflected at the outer periphery of the light guiding body at least once. Since the illumination intensity is different from that of the indirect light deflected at, the illumination light emitted from each position in the length direction of the light guide and the emission surface cannot be obtained. Therefore, as shown in Patent Document 1, by making the cross-sectional shape of the light guide from a circular shape to a polygonal shape and an irregular shape in the main scanning direction, direct light from the LED is not incident on the light reflection or diffusion pattern surface. Lighting units have been proposed.

  Further, when considering only indirect light, an angled light beam is more likely to be totally reflected on the outer peripheral surface of the light guide, and is likely to enter the light reflection or scattering pattern and exit from the light guide. For this reason, the angle does not increase as the distance from the LED incident surface of the light guide increases in the main scanning direction (the optical axis direction of light incident on the light guide from the light source unit). There is a problem that the illumination distribution of indirect light in a direction orthogonal to the direction becomes narrower. For this, as shown in Patent Document 2 below, the outer peripheral shape of the light guide is changed entirely or locally in the longitudinal direction, the angular distribution of light rays incident on the light reflection or scattering pattern is changed, An illumination unit that makes the illumination distribution of the indirect light in the sub-scanning direction uniform in the main scanning direction has been proposed.

Japanese Patent No. 3176317 JP 2010-277940 A

  However, in the illumination system using only indirect light as shown in Patent Document 1, it is necessary to totally reflect the incident light at the outer periphery of the light guide at least once, so that the illumination light obtained in the vicinity of the LED incident surface is There will be almost nothing. For this reason, in order to obtain the necessary illumination light, a distance from the vicinity of the LED incident surface is necessary, and it becomes necessary to lengthen the light guide relative to the size of the document to be read, which hinders downsizing of the apparatus. Become.

  In addition, as shown in Patent Document 2, when the outer peripheral shape of the light guide is changed entirely or locally in the longitudinal direction, the shape of the light guide itself needs to be atypical. There is a problem that the mold becomes complicated and warpage is likely to occur during molding, and it is difficult to maintain the posture after being incorporated in the apparatus.

  The present invention has been made to solve the above-described problem, and it is possible to change the illumination distribution of direct light and indirect light in the sub-scanning direction during document irradiation without changing the external shape of the light guide. The purpose is to make it uniform at each position in the direction.

  A light guide according to an aspect of the present invention is a light guide that includes a light transmitting member that extends in an optical axis direction of light incident therein and reflects incident light in a certain direction. An exit surface that is provided on at least one of the both end portions and is formed with an incident surface on which light emitted from the light source is incident and one side surface portion that extends in the optical axis direction of the light incident from the incident surface, and emits the incident light. A light reflecting pattern formed with a plurality of light reflecting patterns extending in the optical axis direction at a position facing the light emitting surface and reflecting the incident light toward the light emitting surface. Is a semi-ellipsoidal shape having a first diameter in a direction orthogonal to the optical axis direction that is equal to or longer than a second diameter in the optical axis direction and protruding toward the exit surface, Position in the optical axis direction at Correspondingly, the formed by varying the ratio of the first diameter to the height of the semi-elliptical shape.

  According to the present invention, the illumination distribution of direct light and indirect light in the sub-scanning direction during document irradiation can be made uniform at each position in the main scanning direction without changing the outer shape of the light guide. become.

1 is a front cross-sectional view showing a structure of an image forming apparatus having an illuminating device according to an embodiment of the present invention in an image reading apparatus. It is an internal side view which shows schematic structure of an image reading apparatus. It is the perspective view which shows an illuminating device, and is the figure which showed the internal structure. It is a perspective view which shows the light reflection pattern formed in the output surface inside a light guide. It is a perspective view which expands and shows the light reflection pattern formed in the output surface. It is a figure which shows the light guide which has a flat light reflection pattern which does not have a semi-ellipsoid shape. It is a figure which shows the spreading | diffusion distribution of the reflected light in the subscanning direction by the flat light reflection pattern which does not have a semi-ellipsoid shape by a graph. It is a figure which shows the illumination intensity distribution in the subscanning direction of the indirect light with respect to the distance from the light source in the main scanning direction of a light guide. It is a figure which shows the sub-scanning direction angle distribution of the emitted light by each light reflection pattern which varied the ratio of the height of a semi-ellipsoid shape, and the 1st diameter. It is a perspective view which shows each light reflection pattern which varied the ratio of the height of a semi-ellipsoid shape, and a 1st diameter. It is a perspective view which shows each light reflection pattern which varied the ratio of the height of a semi-ellipsoid shape, and a 1st diameter. It is a perspective view which shows the light guide which has the light reflection pattern which concerns on other embodiment.

  Hereinafter, a light guide according to an embodiment of the present invention and a lighting device including the light guide will be described with reference to the drawings. FIG. 1 is a front cross-sectional view showing the structure of an image forming apparatus having an illuminating apparatus according to an embodiment of the present invention in an image reading apparatus.

  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 is configured by including an operation unit 47, an image forming unit 12, a fixing unit 13, a paper feeding unit 14, a document feeding unit 6, an image reading device 5, and the like in an apparatus main body 11A.

  The operation unit 47 receives instructions such as an image forming operation execution instruction and a document 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 original reading operation, the image reading apparatus 5 optically processes an original fed by the original feeding unit 6 or an image of an original placed on contact glass (original placing glass) 161. Read and 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 document reading operation, the image data received from a user terminal device such as a computer or a smartphone connected to a network, or stored in a built-in HDD. The image forming unit 12 forms a toner image on a recording sheet P as a recording medium fed from the sheet 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 12 include a photosensitive drum, a developing device that supplies toner to the photosensitive drum, a toner cartridge (not shown) that stores toner, and a charging device. And an exposure device and a primary transfer roller 126, respectively.

  When performing color printing, 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 12 each receive image data. A toner image is formed on the photosensitive drum 121 by charging, exposure, and development processes based on the image composed of each color component, and the toner image is driven by the primary transfer roller 126 by the driving roller 125a and the driven roller 125b. The image is transferred onto the intermediate transfer belt 125 that is stretched around the belt.

  The intermediate transfer belt 125 is driven by a driving roller 125 a in a state where an image carrying surface on which a toner image is transferred is set on the outer peripheral surface thereof and in contact with the peripheral surface of the photosensitive drum 121. The intermediate transfer belt 125 travels endlessly between the driving roller 125a and the driven roller 125b while being synchronized with each photosensitive drum 121.

  The toner images of the respective colors 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 of the size specified by the instruction from the operator is rotated, so that the recording paper P stored in each paper feed cassette is loaded. It 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.

  As shown in FIG. 2, the image reading device 5 includes an optical scanning device 7 and an imaging unit 8.

  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 illuminating device 10 includes a rod-shaped light guide and a light source disposed at an end portion in the length direction of the light guide (details will be described later). The illuminating device 10 extends in the depth direction in FIG. 2, and the extending direction of the illuminating device 10 is the main scanning direction during document reading.

  The first mirror 711 receives the reflected light from the original reading surface of the light irradiated by the illuminating device 10 on the original 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, an unillustrated moving rail for guiding the movement of the optical scanning device 7 in the direction of the arrow 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, the arrow direction shown in FIG.

  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 a line sensor 82 that is an imaging 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 line sensor 82 provided on the downstream side of the optical path. The line sensor 82 generates a voltage indicating the amount of light according to the amount of received light, that is, converts the optical information obtained by the light receiving element into an electrical signal and outputs it to a control unit (not shown). In this manner, the line sensor 82 reads an image of a document to be read by the image reading device 5.

  Next, the illumination device 10 provided in the image reading device 5 will be described. FIG. 3 is a perspective view showing the lighting apparatus 10 and shows the internal configuration.

  The illumination device 10 includes a light guide 11 and a light source 12.

  The light guide 11 extends in the optical axis direction of light incident from the light source 12 into the light guide 11. Since the light guide 11 extends in the main scanning direction as described above, the optical axis direction coincides with the main scanning direction. The light guide 11 is made of, for example, a resin light transmissive member, and reflects light incident from the light source 12 toward a certain direction (a direction toward the reflection surface 15) by the reflection surface 15.

  The light guide 11 is formed by an incident surface 18, an exit surface 17, and a reflective surface 15.

  The incident surface 18 has at least one side surface of both end portions in the longitudinal direction of the light guide 11 as the incident surface. In the present embodiment, a mode in which only one side surface of both end portions is the incident surface 18 will be described. A light source 12 is attached to the incident surface 18. Light emitted from the light source 12 enters the light guide 11 from the incident surface 18.

  The emission surface 17 extends in the main scanning direction and forms one side surface of the light guide 11. In the present embodiment, the emission surface 17 forms the upper surface portion of the light guide 11. Light that has entered the light guide 11 from the incident surface 18 is reflected by the reflecting surface 15 and is emitted from the light emitting surface 17 to the outside of the light guide 11.

  The reflection surface 15 extends in the sub-scanning direction at a position facing the emission surface 17. In the present embodiment, the reflecting surface 15 forms the lower surface portion of the light guide 11. A plurality of light reflection patterns 16 that reflect incident light toward the emission surface 17 are formed on the reflection surface 15. The reflection surface 15 reflects the light incident on the inside of the light guide 11 from the incident surface 18 toward the emission surface 17 by the light reflection pattern 16. The light reflection pattern 16 is integrally formed of the same material as the light guide 11.

  The light source 12 includes, for example, an LED 121. The light source 12 is attached to the outer surface of the incident surface 18 of the light guide 11. In the present embodiment, an example in which six LEDs 121 are provided as the light source 12 is shown. The irradiation direction (optical axis direction) of the light that the light source 12 irradiates from the incident surface 18 toward the inside of the light guide 11 is the length direction of the light guide 11, that is, the main scanning direction.

  Next, the light reflection pattern 16 will be described. FIG. 4 is a perspective view showing the light reflection pattern 16 formed on the emission surface 17 inside the light guide 11. FIG. 5 is an enlarged perspective view showing the light reflection pattern 16 formed on the emission surface 17.

  The light reflection pattern 16 is a shape pattern that reflects and scatters light incident on itself. On the reflection surface 15, a plurality of light reflection patterns 16 are arranged in a row in the sub-scanning direction, and a plurality of rows made of the plurality of light reflection patterns 16 are arranged in the main scanning direction. The row of the light reflection patterns 16 is formed in the main scanning direction from the position of the incident surface 18 of the reflecting surface 15 to the position of the side surface that is the end opposite to the incident surface 18.

  When the light incident on the light guide 11 from the incident surface 18 has no light reflection or scattering pattern, the light is incident on the light guide 11 and then totally reflected on the outer peripheral surface of the light guide 11. The light travels in the main scanning direction and is guided to the end opposite to the incident surface 18 without leakage. In this case, since the original cannot be illuminated with the light from the light source 12 installed on the incident surface 18, the incident light is transmitted in the sub-scanning direction by forming the light reflecting pattern 16 on the reflecting surface 15 facing the emission surface 17. It is to be reflected.

  As shown in FIG. 5, each light reflection pattern 16 has a semi-ellipsoidal shape that protrudes toward the emission surface 17. The light reflection pattern 16 is formed such that the first diameter A in the sub-scanning direction (direction orthogonal to the optical axis direction) is longer than the second diameter B in the main scanning direction (optical axis direction). When the light reflecting pattern 16 has the semi-ellipsoidal shape, when the light incident on the light guide 11 from the incident surface 18 is reflected by the light reflecting pattern 16, the reflected light toward the emission surface 17 and the light exiting surface 17 are directed. Thus, reflected light scattered in the sub-scanning direction is obtained. In the present embodiment, the semi-ellipsoidal shape includes a semicircular shape.

  Further, when the ratio of the first diameter A to the height h of the semi-elliptical shape is changed, the sub-scanning in which the reflected light is scattered according to the change of the ratio. The range of directional angles changes. Note that the height of the semi-ellipsoidal shape is the height at the highest portion of the semi-ellipsoidal shape.

  Here, the diffusion in the sub-scanning direction when light incident from the incident surface of a general light guide is reflected by the reflecting surface and emitted from the emitting surface will be described. FIG. 6 is a diagram showing a light guide 110 having a flat light reflection pattern that does not have a semi-ellipsoidal shape. FIG. 7 is a graph showing the diffusion distribution of reflected light in the sub-scanning direction by a flat light reflection pattern having no semi-ellipsoidal shape.

  As shown in FIG. 6, a light guide body 110 is generally known in which a light reflection pattern 160 made of an inverted V-shaped prism protruding toward an emission surface 170 is formed on a reflection surface 150. The light reflection pattern 160 is integrally formed of the same material as the light guide 110. In such a light guide 110, the reflection pattern surface 1601 of the light reflection pattern 160 is changed to the emission surface 170 by changing the pitch in the main scanning direction between the light reflection patterns 160, the height and width of the light reflection pattern 160, and the like. The amount of light reflected in the direction can be adjusted. Therefore, it is possible to make the illumination light emitted from each position in the main scanning direction uniform by adjusting the pitch, height, width, etc. of the light reflection pattern 160 arranged at each position in the main scanning direction. It is.

  However, the light source 120 having an LED emits light in the entire circumferential direction of the light guide 110. Therefore, the direct light directly incident on the light reflection pattern surface 1601 from the light source 120 and the indirect light incident on the light reflection pattern surface 1601 after being totally reflected from the light source 120 by the outer peripheral surface of the light guide 110 at least once. Occur. These direct light and indirect light have different light beam angles in the sub-scanning direction that are incident on the light reflection pattern surface 1601. Since direct light is light directly incident on the light reflection pattern surface 1601 from the LED, the angle with respect to the light reflection pattern surface 1601 is shallow, and the light angle distribution in the sub-scanning direction emitted from the emission surface becomes narrow. On the other hand, indirect light is light that enters the light reflection pattern surface 1601 from the entire circumferential direction of the outer circumferential surface of the light guide 110 by total reflection. The light reflection pattern 160 made of the above inverted V-shaped prism reflects and emits light at the same angle as the incident ray angle with respect to the sub-scanning direction, and has no deflection component. Therefore, the light beam angle distribution in the sub-scanning direction after emission differs between direct light and indirect light as shown in FIG. 7 according to the incident angles of the direct light and indirect light with respect to the light reflection pattern surface 1601.

  Here, since the ratio of direct light and indirect light is different at each position in the main scanning direction within the light guide 110, the light emitted from the light guide 110 is sub-scanning at each position in the main scanning direction. The illumination distribution at will be different. For this reason, if the document reading position is shifted due to the reading operation or the document is lifted off the surface of the contact glass 161, the reading position is shifted in the sub-scanning direction. The deviation from the reference data is not uniform throughout the main scanning direction, and there is a possibility that uneven reading density occurs in the main scanning direction of the image when the original is read.

  FIG. 8 is a graph showing the illuminance distribution in the sub-scanning direction of indirect light with respect to the distance from the light source 120 in the main scanning direction of the light guide 110. In the main scanning direction, the area near the light source 120 and the incident surface 130 has a lot of direct light and little indirect light, the center area mainly contains indirect light, and the indirect light becomes more toward the end portion of the light guide 110. The angular distribution of light rays incident on the light reflection pattern 16 is reduced. For this reason, the illumination distribution in the sub-scanning direction of the light emitted from the light guide 110 at the time of document irradiation, as shown in FIG. 8, depends on the amount of indirect light at each position in the main scanning direction. It will be different at each position.

From the above, in order to make the illuminance distribution of the emitted light in the sub-scanning direction, including direct light and indirect light, uniform over the entire area in the main scanning direction, the light diffusing power by the light reflection pattern is It can be seen that fine control is required according to the position in the main scanning direction.
In the present embodiment, each of the light reflection patterns 16 formed on the reflection surface 15 of the light guide 11 corresponds to the height h of the semi-ellipsoidal shape according to the arrangement position on the reflection surface 15 in the main scanning direction. It is formed by changing the ratio of one diameter A. This makes it possible to adjust the light diffusing power and obtain a uniform illumination distribution in the sub-scanning direction over the entire main scanning direction.

  The adjustment of the ratio of the first diameter A to the height h of the semi-ellipsoidal shape of the light reflection pattern 16 necessary for obtaining a uniform illumination distribution in the sub-scanning direction over the entire main scanning direction will be described. FIG. 9 is a graph showing the sub-scanning direction angular distribution of the emitted light by the respective light reflection patterns 16 in which the ratio of the first diameter A to the height h of the semi-ellipsoidal shape is different. FIG. 9 shows the results obtained by the inventors through experiments. 10 and 11 are perspective views showing examples of the light reflection patterns 16 in which the ratio of the first diameter A to the height h of the semi-ellipsoidal shape is different.

  10 and 11 merely conceptually show the difference in the ratio of the first diameter A to the angle of the light reflection pattern 16 and the height h at each position in the main scanning direction. 10 and 11 show the light reflection on the reflection surface 15 by a number different from the number of the light reflection patterns 16 applied to the actual light guide 11 in order to clearly show the configuration of the light guide 11. The arrangement of the pattern 16 is shown.

  As shown in FIG. 9, in the semi-ellipsoidal light reflection pattern 16 described above, the ratio of the first diameter A to the height h of the semi-ellipsoidal shape decreases, and the closer to the perfect circle, the closer to the sub-scanning direction. The light diffusing power increases, and the emission angle distribution widens.

  Here, based on the illuminance distribution in the sub-scanning direction at each position in the main scanning direction shown in FIG. 8 above, the light emitted from the light guide 11 at each position in the main scanning direction is diffused in the sub-scanning direction. In order to make the range uniform, it is necessary to increase the light diffusion force in the sub-scanning direction by the light reflection pattern 16 in the region near the light source 12 and the incident surface 18 in the main scanning direction on the reflecting surface 15 as compared with other regions. There is.

  Further, in the reflection surface 15, in the vicinity of the central region of the reflection surface 15 in the main scanning direction, the light diffusion force in the sub-scanning direction by the light reflection pattern 16 needs to be smaller than that in other regions.

  Further, in the vicinity of the side surface of the reflecting surface 15 that is the end opposite to the incident surface 18 in the main scanning direction, it is necessary to increase the light diffusion force in the sub-scanning direction by the light reflecting pattern 16 rather than the central region. There is.

  Therefore, for example, as shown in FIGS. 10 and 11, in the main scanning direction of the reflecting surface 15, the area D <b> 1 in the vicinity of the incident surface 18 is set to have a small ratio of the first diameter A to the height h. The ratio is gradually increased as the position approaches the central region position, and the semi-ellipsoidal shape of each light reflection pattern 16 so that the angular component of light irradiation in the sub-scanning direction is the same at each position in the main scanning direction. Form.

  Further, in the main scanning direction, from the region D3 past the central region D2, toward the end opposite to the incident surface 18 (the end of the light guide 11 viewed from the incident surface 18 in the main scanning direction). The ratio of the first diameter A to the height h is gradually reduced. Thereby, the phenomenon that the angle incident on the light reflection pattern 16 becomes smaller toward the end of the light guide 11 and the angular distribution of the emitted light becomes narrower is corrected.

  In the central region D2, the ratio of the first diameter A to the height h of the light reflecting pattern 16 is set so that the other region, that is, the region in the vicinity of the incident surface 18 and the side opposite to the incident surface 18 with respect to the central region. The ratio is larger than the ratio of the light reflection pattern 16 to the end region.

  FIG. 10 shows an example in which the ratio of the first diameter A to the height h is made different by changing the first diameter A by making the height h of the semi-ellipsoidal shape of the light reflection pattern 16 in each of the above regions the same. Is shown. On the other hand, FIG. 11 shows that the ratio of the first diameter A to the height h is varied by making the first diameter A of the semi-ellipsoidal shape of the light reflection pattern 16 in each region the same and changing the height h. An example is shown.

  In addition, the light guide 11 is produced by, for example, injection molding in which molten resin is injected and injected into a mold.

  As described above, according to this embodiment, the semi-elliptical light reflection pattern 16 is formed on the reflection surface 15 facing the emission surface 17, and the first diameter in the sub-scanning direction with respect to the height h of the semi-ellipsoid. By changing the ratio of A at each position in the main scanning direction, it is possible to make the emission angle distribution of the direct light and the indirect light by the light reflection pattern 16 the same. Further, by controlling the reflection angle by the light reflection pattern 16 with respect to the light incident on the light reflection pattern 16 as described above, the reading position shift during the document reading operation and the state where the document is lifted from the surface of the contact glass 161 It is possible to make the amount of change in the amount of reflected light uniform in the main scanning direction. Therefore, in the light guide 11 according to this embodiment, the direct light and indirect light illumination distribution in the sub-scanning direction during document irradiation is changed in the main scanning direction without changing the outer shape of the light guide 11. It is possible to make it uniform at each position.

  Furthermore, in the present embodiment, the light reflecting pattern 16 disposed at each position in the main scanning direction on the reflecting surface 15 is a light whose ratio of the first diameter A to the height h is formed in the vicinity of the central region. A region closer to the incident surface 18 with respect to the central region than the ratio of the reflective pattern 16, and a region on the terminal end side of the light guide 11 that is opposite to the incident surface 18 when viewed from the central region The ratio of the light reflection pattern 16 formed in the above is reduced. According to this, in the main scanning direction, the area in the vicinity of the light source 12 and the incident surface 18 has a lot of direct light and little indirect light, and the central area mainly contains indirect light, and also goes to the end portion of the light guide 11. Corresponding to the phenomenon that the angle distribution of the light beam of the indirect light incident on the light reflection pattern 16 becomes smaller, the angle distribution in the sub-scanning direction is uniform for the light beam emitted from the light guide 11 at each position in the main scanning direction. It is possible to

  The present invention is not limited to the configuration of the above embodiment, and various modifications can be made. For example, if the total length of the light guide 11 is formed short, it is necessary to control the angular distribution in the sub-scanning direction in the vicinity of the incident surface 18 where there is a lot of direct light and little indirect light. There is a case where it is not necessary to control the angular distribution in the sub-scanning direction for the region at the position in the main scanning direction where light is mainly used. In this case, as shown in FIG. 12, in the region D where there is a lot of direct light from the incident surface 18 until the indirect light reaches the main region D7, it extends from the start position to the end position of the region D in the main scanning direction. The ratio of the first diameter A to the height h of the light reflecting pattern 16 is gradually increased. In the region D7, the above-described inverted V-shaped light reflection pattern VP having no deflection component in the sub-scanning direction and having higher emission efficiency than the light reflection pattern 16 is formed. Thereby, the illumination device 10 enables illumination with high emission efficiency. Although not shown, the light reflection pattern VP may be a cylindrical shape, an elliptical shape, an aspherical shape, or the like.

  Further, in each of the above embodiments, only one end portion of the light guide 11 in the main scanning direction is the incident surface 18, and the configuration in which the light source 12 illuminates only from one side of the side surface of the light guide 11 has been described. Instead, the side surfaces of both ends of the light guide 11 in the main scanning direction are made incident surfaces 18, and a configuration is adopted in which light enters the light guide 11 from the both ends of the light guide 11 by the light source 12. Similarly to the case where the light source 12 is provided only on one side in the longitudinal direction of the light guide 11, the distribution of direct light or indirect light at each position in the main scanning direction on the reflection surface 15, or the light reflection pattern The ratio of the first diameter A to the height h of the light reflecting pattern 16 may be changed in each region in the main scanning direction on the reflecting surface 15 in accordance with the angular distribution of the light rays incident on the reflecting surface 15.

  As described above, in the light guide 11 including the incident surfaces 18 and the light sources 12 at both ends, the angular distribution of light rays in which the direct light near the incident surfaces 18 at both ends of the light guide 11 enters the light reflection pattern 16 is small. The angle distribution of light rays incident on the light reflection pattern 16 increases toward the center in the main scanning direction, and the ratio of the first diameter A to the height h of the light reflection pattern 16 is set as described above. Thus, the angular distribution in the sub-scanning direction of the light emitted from the light guide 11 at each position in the main scanning direction can be made uniform.

  In each of the above embodiments, the light source 12 including the LED 121 is shown. However, light can be emitted from the side surface serving as the end of the light guide 11 toward the inside of the light guide 11 in the main scanning direction. If it is a thing, it will not be limited to LED.

  Moreover, the configuration and processing shown in each of the above embodiments using FIGS. 1 to 12 are only one embodiment of the present invention, and the configuration and processing of the present invention are not limited to this.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 5 Image reader 10 Illuminating device 11 Light guide 12 Light source 15 Reflecting surface 16 Light reflecting pattern 17 Output surface 18 Incident surface VP Light reflecting pattern

  The present invention relates to a light guide and an illumination device, and more particularly to a technique for reflecting light incident on a light guide toward an exit surface.

  In an image forming apparatus such as a multifunction machine, as a light source unit of an image reading apparatus such as a scanner, a rod-shaped resin light guide and an LED that emits light from the side in the length direction of the light guide to the inside of the light guide Some use a line light source that combines the above. The light source unit needs to illuminate the document to be read in a line in accordance with the reading of the line sensor. For this purpose, a light reflection or light scattering pattern is provided on the surface facing the exit surface for emitting light from the light guide, and the light incident on the light guide toward the exit surface is deflected by the pattern, Line-shaped illumination light is emitted in a direction toward the document.

Here, in the combination of the rod-shaped light guide and the LED, the direct light directly reflected from the LED by the light reflecting or diffusing pattern surface and the light reflecting or diffusing pattern surface by being totally reflected at the outer periphery of the light guiding body at least once. Since the illumination intensity is different from that of the indirect light deflected at, the illumination light emitted from each position in the length direction of the light guide and the emission surface cannot be obtained. Therefore, as shown in Patent Document 1, by making the cross-sectional shape of the light guide from a circular shape to a polygonal shape and an irregular shape in the main scanning direction, direct light from the LED is not incident on the light reflection or diffusion pattern surface. Lighting units have been proposed.

  Further, when considering only indirect light, an angled light beam is more likely to be totally reflected on the outer peripheral surface of the light guide, and is likely to enter the light reflection or scattering pattern and exit from the light guide. For this reason, the angle does not increase as the distance from the LED incident surface of the light guide increases in the main scanning direction (the optical axis direction of light incident on the light guide from the light source unit). There is a problem that the illumination distribution of indirect light in a direction orthogonal to the direction becomes narrower. For this, as shown in Patent Document 2 below, the outer peripheral shape of the light guide is changed entirely or locally in the longitudinal direction, the angular distribution of light rays incident on the light reflection or scattering pattern is changed, An illumination unit that makes the illumination distribution of the indirect light in the sub-scanning direction uniform in the main scanning direction has been proposed.

Japanese Patent No. 3176317 JP 2010-277940 A

  However, in the illumination system using only indirect light as shown in Patent Document 1, it is necessary to totally reflect the incident light at the outer periphery of the light guide at least once, so that the illumination light obtained in the vicinity of the LED incident surface is There will be almost nothing. For this reason, in order to obtain the necessary illumination light, a distance from the vicinity of the LED incident surface is necessary, and it becomes necessary to lengthen the light guide relative to the size of the document to be read, which hinders downsizing of the apparatus. Become.

  In addition, as shown in Patent Document 2, when the outer peripheral shape of the light guide is changed entirely or locally in the longitudinal direction, the shape of the light guide itself needs to be atypical. There is a problem that the mold becomes complicated and warpage is likely to occur during molding, and it is difficult to maintain the posture after being incorporated in the apparatus.

  The present invention has been made to solve the above-described problem, and it is possible to change the illumination distribution of direct light and indirect light in the sub-scanning direction during document irradiation without changing the external shape of the light guide. The purpose is to make it uniform at each position in the direction.

  A light guide according to an aspect of the present invention is a light guide that includes a light transmitting member that extends in an optical axis direction of light incident therein and reflects incident light in a certain direction. An exit surface that is provided on at least one of the both end portions and is formed with an incident surface on which light emitted from the light source is incident and one side surface portion that extends in the optical axis direction of the light incident from the incident surface, and emits the incident light. A light reflecting pattern formed with a plurality of light reflecting patterns extending in the optical axis direction at a position facing the light emitting surface and reflecting the incident light toward the light emitting surface. Is a semi-ellipsoidal shape having a first diameter in a direction orthogonal to the optical axis direction that is equal to or longer than a second diameter in the optical axis direction and protruding toward the exit surface, Position in the optical axis direction at Correspondingly, the formed by varying the ratio of the first diameter to the height of the semi-elliptical shape.

  According to the present invention, the illumination distribution of direct light and indirect light in the sub-scanning direction during document irradiation can be made uniform at each position in the main scanning direction without changing the outer shape of the light guide. become.

1 is a front cross-sectional view showing a structure of an image forming apparatus having an illuminating device according to an embodiment of the present invention in an image reading apparatus. It is an internal side view which shows schematic structure of an image reading apparatus. It is the perspective view which shows an illuminating device, and is the figure which showed the internal structure. It is a perspective view which shows the light reflection pattern formed in the reflective surface inside a light guide. It is a perspective view which expands and shows the light reflection pattern formed in the reflective surface . It is a figure which shows the light guide which has a flat light reflection pattern which does not have a semi-ellipsoid shape. It is a figure which shows the spreading | diffusion distribution of the reflected light in the subscanning direction by the flat light reflection pattern which does not have a semi-ellipsoid shape by a graph. It is a figure which shows the illumination intensity distribution in the subscanning direction of the indirect light with respect to the distance from the light source in the main scanning direction of a light guide. It is a figure which shows the sub-scanning direction angle distribution of the emitted light by each light reflection pattern which varied the ratio of the height of a semi-ellipsoid shape, and the 1st diameter. It is a perspective view which shows each light reflection pattern which varied the ratio of the height of a semi-ellipsoid shape, and a 1st diameter. It is a perspective view which shows each light reflection pattern which varied the ratio of the height of a semi-ellipsoid shape, and a 1st diameter. It is a perspective view which shows the light guide which has the light reflection pattern which concerns on other embodiment.

  Hereinafter, a light guide according to an embodiment of the present invention and a lighting device including the light guide will be described with reference to the drawings. FIG. 1 is a front cross-sectional view showing the structure of an image forming apparatus having an illuminating apparatus according to an embodiment of the present invention in an image reading apparatus.

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 apparatus main body 11A including an operation unit 47, an image forming unit 12A , a fixing unit 13, a paper feeding unit 14, a document feeding unit 6, an image reading device 5, and the like.

  The operation unit 47 receives instructions such as an image forming operation execution instruction and a document 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 original reading operation, the image reading apparatus 5 optically processes an original fed by the original feeding unit 6 or an image of an original placed on contact glass (original placing glass) 161. Read and 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 document reading operation, the image data received from a user terminal device such as a computer or a smartphone connected to a network, or stored in a built-in HDD. Based on the image data and the like, the image forming unit 12A forms a toner image on the recording paper P as a recording medium fed from the paper feeding unit. The image forming units 12M, 12C, 12Y, and 12Bk of the image forming unit 12A include a photosensitive drum, a developing device that supplies toner to the photosensitive drum, a toner cartridge (not shown) that stores toner, and a charging device. And an exposure device and a primary transfer roller 126, respectively.

When performing color printing, the image forming unit 12M for magenta image forming unit 12A, the image forming unit 12C for cyan, an image forming unit 12Bk for the image forming unit 12Y and black for yellow are each, image data A toner image is formed on the photosensitive drum 121 by charging, exposure, and development processes based on the image composed of each color component, and the toner image is driven by the primary transfer roller 126 by the driving roller 125a and the driven roller 125b. The image is transferred onto the intermediate transfer belt 125 that is stretched around the belt.

  The intermediate transfer belt 125 is driven by a driving roller 125 a in a state where an image carrying surface on which a toner image is transferred is set on the outer peripheral surface thereof and in contact with the peripheral surface of the photosensitive drum 121. The intermediate transfer belt 125 travels endlessly between the driving roller 125a and the driven roller 125b while being synchronized with each photosensitive drum 121.

  The toner images of the respective colors 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 of the size specified by the instruction from the operator is rotated, so that the recording paper P stored in each paper feed cassette is loaded. It 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.

  As shown in FIG. 2, the image reading device 5 includes an optical scanning device 7 and an imaging unit 8.

  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 illuminating device 10 includes a rod-shaped light guide and a light source disposed at an end portion in the length direction of the light guide (details will be described later). The illuminating device 10 extends in the depth direction in FIG. 2, and the extending direction of the illuminating device 10 is the main scanning direction during document reading.

  The first mirror 711 receives the reflected light from the original reading surface of the light irradiated by the illuminating device 10 on the original 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. These second mirror 721 and third mirror 722 are attach 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, an unillustrated moving rail for guiding the movement of the optical scanning device 7 in the direction of the arrow 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, the arrow direction shown in FIG.

  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 a line sensor 82 that is an imaging 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 line sensor 82 provided on the downstream side of the optical path. The line sensor 82 generates a voltage indicating the amount of light according to the amount of received light, that is, converts the optical information obtained by the light receiving element into an electrical signal and outputs it to a control unit (not shown). In this manner, the line sensor 82 reads an image of a document to be read by the image reading device 5.

  Next, the illumination device 10 provided in the image reading device 5 will be described. FIG. 3 is a perspective view showing the lighting apparatus 10 and shows the internal configuration.

  The illumination device 10 includes a light guide 11 and a light source 12.

The light guide 11 extends in the optical axis direction of light incident from the light source 12 into the light guide 11. Since the light guide 11 extends in the main scanning direction as described above, the optical axis direction coincides with the main scanning direction. The light guide 11 is made of, for example, a resin light transmissive member, and reflects light incident from the light source 12 toward a certain direction (a direction toward the emission surface 17 ) by the reflection surface 15.

  The light guide 11 is formed by an incident surface 18, an exit surface 17, and a reflective surface 15.

  The incident surface 18 has at least one side surface of both end portions in the longitudinal direction of the light guide 11 as the incident surface. In the present embodiment, a mode in which only one side surface of both end portions is the incident surface 18 will be described. A light source 12 is attached to the incident surface 18. Light emitted from the light source 12 enters the light guide 11 from the incident surface 18.

  The emission surface 17 extends in the main scanning direction and forms one side surface of the light guide 11. In the present embodiment, the emission surface 17 forms the upper surface portion of the light guide 11. Light that has entered the light guide 11 from the incident surface 18 is reflected by the reflecting surface 15 and is emitted from the light emitting surface 17 to the outside of the light guide 11.

The reflection surface 15 extends in the main scanning direction at a position facing the emission surface 17. In the present embodiment, the reflecting surface 15 forms the lower surface portion of the light guide 11. A plurality of light reflection patterns 16 that reflect incident light toward the emission surface 17 are formed on the reflection surface 15. The reflection surface 15 reflects the light incident on the inside of the light guide 11 from the incident surface 18 toward the emission surface 17 by the light reflection pattern 16. The light reflection pattern 16 is integrally formed of the same material as the light guide 11.

The light source 12 includes, for example, an LED 1210 . The light source 12 is attached to the outer surface of the incident surface 18 of the light guide 11. In the present embodiment, an example in which six LEDs 1210 are provided as the light source 12 is shown. The irradiation direction (optical axis direction) of light that the light source 12 irradiates from the incident surface 18 toward the inside of the light guide 11 is the length direction of the light guide 11, that is, the main scanning direction.

Next, the light reflection pattern 16 will be described. FIG. 4 is a perspective view showing the light reflection pattern 16 formed on the reflection surface 15 inside the light guide 11. FIG. 5 is an enlarged perspective view showing the light reflection pattern 16 formed on the reflection surface 15 .

  The light reflection pattern 16 is a shape pattern that reflects and scatters light incident on itself. On the reflection surface 15, a plurality of light reflection patterns 16 are arranged in a row in the sub-scanning direction, and a plurality of rows made of the plurality of light reflection patterns 16 are arranged in the main scanning direction. The row of the light reflection patterns 16 is formed in the main scanning direction from the position of the incident surface 18 of the reflecting surface 15 to the position of the side surface that is the end opposite to the incident surface 18.

  When the light incident on the light guide 11 from the incident surface 18 has no light reflection or scattering pattern, the light is incident on the light guide 11 and then totally reflected on the outer peripheral surface of the light guide 11. The light travels in the main scanning direction and is guided to the end opposite to the incident surface 18 without leakage. In this case, since the original cannot be illuminated with the light from the light source 12 installed on the incident surface 18, the incident light is transmitted in the sub-scanning direction by forming the light reflecting pattern 16 on the reflecting surface 15 facing the emission surface 17. It is to be reflected.

  As shown in FIG. 5, each light reflection pattern 16 has a semi-ellipsoidal shape that protrudes toward the emission surface 17. The light reflection pattern 16 is formed such that the first diameter A in the sub-scanning direction (direction orthogonal to the optical axis direction) is longer than the second diameter B in the main scanning direction (optical axis direction). When the light reflecting pattern 16 has the semi-ellipsoidal shape, when the light incident on the light guide 11 from the incident surface 18 is reflected by the light reflecting pattern 16, the reflected light toward the emission surface 17 and the light exiting surface 17 are directed. Thus, reflected light scattered in the sub-scanning direction is obtained. In the present embodiment, the semi-ellipsoidal shape includes a semicircular shape.

  Further, when the ratio of the first diameter A to the height h of the semi-elliptical shape is changed, the sub-scanning in which the reflected light is scattered according to the change of the ratio. The range of directional angles changes. Note that the height of the semi-ellipsoidal shape is the height at the highest portion of the semi-ellipsoidal shape.

  Here, the diffusion in the sub-scanning direction when light incident from the incident surface of a general light guide is reflected by the reflecting surface and emitted from the emitting surface will be described. FIG. 6 is a diagram showing a light guide 110 having a flat light reflection pattern that does not have a semi-ellipsoidal shape. FIG. 7 is a graph showing the diffusion distribution of reflected light in the sub-scanning direction by a flat light reflection pattern having no semi-ellipsoidal shape.

  As shown in FIG. 6, a light guide body 110 is generally known in which a light reflection pattern 160 made of an inverted V-shaped prism protruding toward an emission surface 170 is formed on a reflection surface 150. The light reflection pattern 160 is integrally formed of the same material as the light guide 110. In such a light guide 110, the reflection pattern surface 1601 of the light reflection pattern 160 is changed to the emission surface 170 by changing the pitch in the main scanning direction between the light reflection patterns 160, the height and width of the light reflection pattern 160, and the like. The amount of light reflected in the direction can be adjusted. Therefore, it is possible to make the illumination light emitted from each position in the main scanning direction uniform by adjusting the pitch, height, width, etc. of the light reflection pattern 160 arranged at each position in the main scanning direction. It is.

However, the light source 120 having an LED emits light in the entire circumferential direction of the light guide 110. Therefore, the direct light directly incident on the light reflection pattern surface 1601 from the light source 120 and the indirect light incident on the light reflection pattern surface 1601 after being totally reflected from the light source 120 by the outer peripheral surface of the light guide 110 at least once. Occur. These direct light and indirect light have different light beam angles in the sub-scanning direction that are incident on the light reflection pattern surface 1601. Since direct light is light directly incident on the light reflection pattern surface 1601 from the LED, the angle with respect to the light reflection pattern surface 1601 is shallow, and the light angle distribution in the sub-scanning direction emitted from the emission surface becomes narrow. On the other hand, indirect light is light that enters the light reflection pattern surface 1601 from the entire circumferential direction of the outer circumferential surface of the light guide 110 by total reflection. The light reflection pattern 160 made of the above inverted V-shaped prism reflects and emits light at the same angle as the incident ray angle with respect to the sub-scanning direction, and has no deflection component. Therefore, the light beam angle distribution in the sub-scanning direction after emission differs between direct light and indirect light as shown in FIG. 7 according to the incident angles of the direct light and indirect light with respect to the light reflection pattern surface 1601.

  Here, since the ratio of direct light and indirect light is different at each position in the main scanning direction within the light guide 110, the light emitted from the light guide 110 is sub-scanning at each position in the main scanning direction. The illumination distribution at will be different. For this reason, if the document reading position is shifted due to the reading operation or the document is lifted off the surface of the contact glass 161, the reading position is shifted in the sub-scanning direction. The deviation from the reference data is not uniform throughout the main scanning direction, and there is a possibility that uneven reading density occurs in the main scanning direction of the image when the original is read.

FIG. 8 is a graph showing the illuminance distribution in the sub-scanning direction of indirect light with respect to the distance from the light source 120 in the main scanning direction of the light guide 110. In the main scanning direction, the area near the light source 120 and the incident surface 1 80 has a lot of direct light and little indirect light, the center area is mainly indirect light, and becomes indirect toward the end of the light guide 110. The angular distribution of light rays incident on the light reflection pattern 16 is reduced. For this reason, the illumination distribution in the sub-scanning direction of the light emitted from the light guide 110 at the time of document irradiation, as shown in FIG. 8, depends on the amount of indirect light at each position in the main scanning direction. It will be different at each position.

  From the above, in order to make the illuminance distribution of the emitted light in the sub-scanning direction, including direct light and indirect light, uniform over the entire area in the main scanning direction, the light diffusing power by the light reflection pattern is It can be seen that fine control is required according to the position in the main scanning direction. In the present embodiment, each of the light reflection patterns 16 formed on the reflection surface 15 of the light guide 11 corresponds to the height h of the semi-ellipsoidal shape according to the arrangement position on the reflection surface 15 in the main scanning direction. It is formed by changing the ratio of one diameter A. This makes it possible to adjust the light diffusing power and obtain a uniform illumination distribution in the sub-scanning direction over the entire main scanning direction.

  The adjustment of the ratio of the first diameter A to the height h of the semi-ellipsoidal shape of the light reflection pattern 16 necessary for obtaining a uniform illumination distribution in the sub-scanning direction over the entire main scanning direction will be described. FIG. 9 is a graph showing the sub-scanning direction angular distribution of the emitted light by the respective light reflection patterns 16 in which the ratio of the first diameter A to the height h of the semi-ellipsoidal shape is different. FIG. 9 shows the results obtained by the inventors through experiments. 10 and 11 are perspective views showing examples of the light reflection patterns 16 in which the ratio of the first diameter A to the height h of the semi-ellipsoidal shape is different.

  10 and 11 merely conceptually show the difference in the ratio of the first diameter A to the angle of the light reflection pattern 16 and the height h at each position in the main scanning direction. 10 and 11 show the light reflection on the reflection surface 15 by a number different from the number of the light reflection patterns 16 applied to the actual light guide 11 in order to clearly show the configuration of the light guide 11. The arrangement of the pattern 16 is shown.

  As shown in FIG. 9, in the semi-ellipsoidal light reflection pattern 16 described above, the ratio of the first diameter A to the height h of the semi-ellipsoidal shape decreases, and the closer to the perfect circle, the closer to the sub-scanning direction. The light diffusing power increases, and the emission angle distribution widens.

  Here, based on the illuminance distribution in the sub-scanning direction at each position in the main scanning direction shown in FIG. 8 above, the light emitted from the light guide 11 at each position in the main scanning direction is diffused in the sub-scanning direction. In order to make the range uniform, it is necessary to increase the light diffusion force in the sub-scanning direction by the light reflection pattern 16 in the region near the light source 12 and the incident surface 18 in the main scanning direction on the reflecting surface 15 as compared with other regions. There is.

  Further, in the reflection surface 15, in the vicinity of the central region of the reflection surface 15 in the main scanning direction, the light diffusion force in the sub-scanning direction by the light reflection pattern 16 needs to be smaller than that in other regions.

  Further, in the vicinity of the side surface of the reflecting surface 15 that is the end opposite to the incident surface 18 in the main scanning direction, it is necessary to increase the light diffusion force in the sub-scanning direction by the light reflecting pattern 16 rather than the central region. There is.

  Therefore, for example, as shown in FIGS. 10 and 11, in the main scanning direction of the reflecting surface 15, the area D <b> 1 in the vicinity of the incident surface 18 is set to have a small ratio of the first diameter A to the height h. The ratio is gradually increased as the position approaches the central region position, and the semi-ellipsoidal shape of each light reflection pattern 16 so that the angular component of light irradiation in the sub-scanning direction is the same at each position in the main scanning direction. Form.

  Further, in the main scanning direction, from the region D3 past the central region D2, toward the end opposite to the incident surface 18 (the end of the light guide 11 viewed from the incident surface 18 in the main scanning direction). The ratio of the first diameter A to the height h is gradually reduced. Thereby, the phenomenon that the angle incident on the light reflection pattern 16 becomes smaller toward the end of the light guide 11 and the angular distribution of the emitted light becomes narrower is corrected.

  In the central region D2, the ratio of the first diameter A to the height h of the light reflecting pattern 16 is set so that the other region, that is, the region in the vicinity of the incident surface 18 and the side opposite to the incident surface 18 with respect to the central region. The ratio is larger than the ratio of the light reflection pattern 16 to the end region.

  FIG. 10 shows an example in which the ratio of the first diameter A to the height h is made different by changing the first diameter A by making the height h of the semi-ellipsoidal shape of the light reflection pattern 16 in each of the above regions the same. Is shown. On the other hand, FIG. 11 shows that the ratio of the first diameter A to the height h is varied by making the first diameter A of the semi-ellipsoidal shape of the light reflection pattern 16 in each region the same and changing the height h. An example is shown.

  In addition, the light guide 11 is produced by, for example, injection molding in which molten resin is injected and injected into a mold.

  As described above, according to this embodiment, the semi-elliptical light reflection pattern 16 is formed on the reflection surface 15 facing the emission surface 17, and the first diameter in the sub-scanning direction with respect to the height h of the semi-ellipsoid. By changing the ratio of A at each position in the main scanning direction, it is possible to make the emission angle distribution of the direct light and the indirect light by the light reflection pattern 16 the same. Further, by controlling the reflection angle by the light reflection pattern 16 with respect to the light incident on the light reflection pattern 16 as described above, the reading position shift during the document reading operation and the state where the document is lifted from the surface of the contact glass 161 It is possible to make the amount of change in the amount of reflected light uniform in the main scanning direction. Therefore, in the light guide 11 according to this embodiment, the direct light and indirect light illumination distribution in the sub-scanning direction during document irradiation is changed in the main scanning direction without changing the outer shape of the light guide 11. It is possible to make it uniform at each position.

  Furthermore, in the present embodiment, the light reflecting pattern 16 disposed at each position in the main scanning direction on the reflecting surface 15 is a light whose ratio of the first diameter A to the height h is formed in the vicinity of the central region. A region closer to the incident surface 18 with respect to the central region than the ratio of the reflective pattern 16, and a region on the terminal end side of the light guide 11 that is opposite to the incident surface 18 when viewed from the central region The ratio of the light reflection pattern 16 formed in the above is reduced. According to this, in the main scanning direction, the area in the vicinity of the light source 12 and the incident surface 18 has a lot of direct light and little indirect light, and the central area mainly contains indirect light, and also goes to the end portion of the light guide 11. Corresponding to the phenomenon that the angle distribution of the light beam of the indirect light incident on the light reflection pattern 16 becomes smaller, the angle distribution in the sub-scanning direction is uniform for the light beam emitted from the light guide 11 at each position in the main scanning direction. It is possible to

The present invention is not limited to the configuration of the above embodiment, and various modifications can be made. For example, if the total length of the light guide 11 is formed short, it is necessary to control the angular distribution in the sub-scanning direction in the vicinity of the incident surface 18 where there is a lot of direct light and little indirect light. There is a case where it is not necessary to control the angular distribution in the sub-scanning direction for the region at the position in the main scanning direction where light is mainly used. In this case, as shown in FIG. 12, in the region D where there is a lot of direct light from the incident surface 18 until the indirect light reaches the main region D7, it extends from the start position to the end position of the region D in the main scanning direction. The ratio of the first diameter A to the height h of the light reflecting pattern 16 is gradually increased. In the region D7, the above-described inverted V-shaped light reflection pattern VP having no deflection component in the sub-scanning direction and having higher emission efficiency than the light reflection pattern 16 is formed. Thereby, the illumination device 10
Thus, illumination with high emission efficiency is possible. Although not shown, the light reflection pattern VP may be a cylindrical shape, an elliptical shape, an aspherical shape, or the like.

  Further, in each of the above embodiments, only one end portion of the light guide 11 in the main scanning direction is the incident surface 18, and the configuration in which the light source 12 illuminates only from one side of the side surface of the light guide 11 has been described. Instead, the side surfaces of both ends of the light guide 11 in the main scanning direction are made incident surfaces 18, and a configuration is adopted in which light enters the light guide 11 from the both ends of the light guide 11 by the light source 12. Similarly to the case where the light source 12 is provided only on one side in the longitudinal direction of the light guide 11, the distribution of direct light or indirect light at each position in the main scanning direction on the reflection surface 15, or the light reflection pattern The ratio of the first diameter A to the height h of the light reflecting pattern 16 may be changed in each region in the main scanning direction on the reflecting surface 15 in accordance with the angular distribution of the light rays incident on the reflecting surface 15.

  As described above, in the light guide 11 including the incident surfaces 18 and the light sources 12 at both ends, the angular distribution of light rays in which the direct light near the incident surfaces 18 at both ends of the light guide 11 enters the light reflection pattern 16 is small. The angle distribution of light rays incident on the light reflection pattern 16 increases toward the center in the main scanning direction, and the ratio of the first diameter A to the height h of the light reflection pattern 16 is set as described above. Thus, the angular distribution in the sub-scanning direction of the light emitted from the light guide 11 at each position in the main scanning direction can be made uniform.

In the above embodiments, although the ones with a LED1210 as the light source 12, from the side of the said end of the light guide 11, capable of emitting light in a main scanning direction toward the inside of the light guide 11 If it is a thing, it will not be limited to LED.

  Moreover, the configuration and processing shown in each of the above embodiments using FIGS. 1 to 12 are only one embodiment of the present invention, and the configuration and processing of the present invention are not limited to this.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 5 Image reader 10 Illuminating device 11 Light guide 12 Light source 15 Reflecting surface 16 Light reflecting pattern 17 Output surface 18 Incident surface VP Light reflecting pattern

Claims (7)

A light guide that consists of a light transmissive member extending in the optical axis direction of light incident on the inside and reflects incident light in a certain direction,
An incident surface provided on at least one of both ends in the longitudinal direction, on which light emitted from the light source is incident;
Forming one side surface portion extending in the optical axis direction of light incident from the incident surface, and an exit surface for emitting the incident light;
A reflection surface formed with a plurality of light reflection patterns extending in the optical axis direction at a position facing the emission surface and reflecting the incident light toward the emission surface;
The light reflection pattern has a semi-ellipsoidal shape in which a first diameter in a direction orthogonal to the optical axis direction has a length equal to or longer than a second diameter in the optical axis direction and protrudes toward the emission surface. The light guide is formed by varying the ratio of the first diameter to the height of the semi-ellipsoidal shape according to the arrangement position in the optical axis direction on the reflection surface.   The ratio of the light reflection pattern arranged at each arrangement position on the reflection surface is higher than the ratio of the light reflection pattern formed near the center position in the optical axis direction. The ratio of the light reflection pattern formed at a surface side position and an end side position in a direction opposite to the incident surface with respect to the vicinity of the center position is formed to be smaller. Light guide.   The light reflection pattern is formed near the position on the incident surface side in the optical axis direction, and the ratio is larger as the light reflection pattern is located away from the position in the optical axis direction from the incident surface. The light guide according to claim 1.   The light guide according to claim 1, wherein side surfaces of both end portions of the light guide in the optical axis direction are the entrance surfaces.   The ratio of the light reflection pattern arranged at each arrangement position on the reflection surface is higher than the ratio of the light reflection pattern formed near the center position in the optical axis direction. The light guide according to claim 4, wherein the ratio of the light reflection patterns formed at the surface side position and the other incident surface side position is formed to be smaller.   The light reflection pattern is formed near the incident surface side position and the other incident surface side position in the optical axis direction, and the light reflection pattern is located away from each incident surface in the optical axis direction position. The light guide according to claim 4, wherein the ratio is formed to be larger. A light guide according to any one of claims 1 to 6,
A light source that irradiates light in the length direction of the light guide from the incident surface toward the inside of the light guide.