JP2004301822A - Lighting system for display for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a bright line and a dark line generated in illumination light inconspicuous to enhance an appearance of a display for a vehicle. <P>SOLUTION: This lighting system for the vehicular display is provided with a light source 40, and a light guide panel 20 having an incident face 22a for making light from the light source 40 get incident. In the lighting system, a light diffusing face 21a for diffusing light is formed in the whole area of a visible range confirmed visibly by a vehicular occupant on at least one face out of a surface and a reverse face of the light guide panel 20, and the light incident from the incident face 22a to be guided to an inside of the light guide panel 20 is diffused in the diffusing face 21a to be emitted from the surface of the light guide panel 20 as the illumination light. In the lighting system, a plurality of dots 21b for diffusing the light is formed in a prescribed area 20b of the visible range on the one face out of the surface and the reverse face of the light guide panel 20, and is formed to reduce a light diffusion degree in each of the dots 21b in a portion where incident light energy incident from the inside of the light guide panel 20 is great, according to a level of the incident light energy, out of the respective dots 21b. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an illuminating device for illuminating a display such as a vehicle instrument.

2. Description of the Related Art Conventionally, there has been known a lighting device for a vehicle display device that guides light from a light source into a light guide plate and then emits the light from the surface of the light guide plate in a planar shape as illumination light. Patent Documents 1 to 3 and the like have conventionally suggested that a diffusion surface is formed on the back surface of the light guide plate to prevent luminance unevenness from occurring in the illumination light.
Japanese Patent No. 33133577 JP-A-3-144690 JP-A-4-76593

  Here, the present inventors are studying a lighting device similar to each of the above-mentioned patent documents on a trial basis, and FIG. 8 is a front view of the lighting device on the trial study as viewed from the surface side of the light guide plate 20. On the entire back surface 20r of the light guide plate 20, a diffusion surface 21a for diffusing light is formed by graining or the like over the entire visible range (range surrounded by a dotted line in FIG. 8) visible to vehicle occupants. I have. In addition, the code | symbol K0 of FIG. 8 has shown the part facing a light source.

  FIG. 9 is a diagram showing a simulation result showing a trajectory of light from the light source 40 provided on the printed wiring board 30 in a state where the diffusion surface 21 a is removed from the light guide plate 20. As shown in this figure, the lighting device includes a liquid crystal panel 10, a light guide plate 20, a printed wiring board 30, and a light source 40. A symbol K indicates a portion of the back surface 20r of the light guide plate 20 where light is concentrated and the amount of light is large.

  As described above, the amount of light incident on the back surface 20r of the light guide plate 20 from inside the light guide plate 20 differs depending on the position. Then, if the diffusion surface 21a is simply formed as described above, the portion with a large amount of light is visually recognized as a bright line, and the portion with a small amount of light is visually recognized as a dark line, and the appearance of the display is deteriorated.

  In addition, in the illumination device of the above-described study of the prototype, the diffusion surface 21a is formed on the back surface 20r of the light guide plate 20, but the same problem occurs even when the diffusion surface 21a is formed on the front surface 20f of the light guide plate 20. .

  In view of the above, it is an object of the present invention to improve the appearance of a vehicle display device by making bright lines and dark lines generated in illumination light inconspicuous.

In order to achieve the above object, the invention according to claim 1 includes a light source (40) and a light guide plate (20) having an incident surface (22a) through which light from the light source (40) is incident. In at least one of the front surface (20f) and the back surface (20r) of (20), a diffusion surface (21a) for diffusing light is formed in a visible range (20a) visible to a vehicle occupant. A display for a vehicle, in which light incident from (22a) and guided into the light guide plate (20) is diffused by a diffusion surface (21a) and emitted from the surface of the light guide plate (20) as illumination light in a planar manner. Lighting equipment,
A plurality of dots (21b) for diffusing light are provided in a predetermined region (20b) in the visible range of at least one of the front surface and the back surface of the light guide plate (20), and the light guide plate (20) in the predetermined region is provided. It is characterized in that the light diffusion degree of the dot (21b) decreases as the light concentration in () increases.

  Here, as the dot (21b) has a larger light diffusion degree, the dot (21b) portion looks brighter, and as the dot (21b) has a smaller light diffusion degree, the dot (21b) has a higher light diffusion degree. Part looks dark.

  Therefore, according to the first aspect of the present invention, the dots (21b) where the light in the light guide plate (20) is concentrated and the amount of light is large are formed with a small light diffusion degree. The bright line due to the large number of light can be made to look a little dark. Similarly, in the dots (21b) where the light in the light guide plate (20) is not so concentrated and the amount of light is small, the degree of light diffusion is formed large, so that the dark lines due to the small amount of light appear slightly bright. I can do it. As described above, the bright and dark lines generated in the illumination light can be made inconspicuous, and the appearance of the vehicle display device can be improved.

  Further, since a plurality of dots (21b) are formed, the bright lines which have conventionally been viewed as a line extending continuously and connected to one line are visually recognized as bright lines which appear intermittently bright by the dots (21b). Similarly, the dark line which has conventionally been visually recognized as a linear line extending in a line is now visually recognized as a dark line which appears intermittently dark by the dot (21b). Therefore, the bright line and the dark line can be made less noticeable.

In the invention described in claim 2, the light source (40) and the light guide plate (20) having the incident surface (22a) for receiving the light from the light source (40) are provided, and the surface (20f) of the light guide plate (20) is provided. ) And a back surface (20r), a diffusion surface (21a) for diffusing light is formed in a visible range (20a) visible to a vehicle occupant, and the light is diffused from an incident surface (22a). In a lighting device for a vehicle display, the light guided into the light guide plate (20) is diffused by a diffusion surface (21a) and emitted from the surface of the light guide plate (20) as illumination light in a plane.
A predetermined region (20b) in the visible range of at least one of the front surface and the rear surface of the light guide plate (20) is provided with a plurality of dots (21b) for diffusing light. It is characterized in that the density of dots decreases as the location where more light is concentrated.

  Here, of the illumination light, the portion where the dot (21b) and the diffusion surface (21a) overlap in the line of sight has a greater degree of diffusion than the portion of only the diffusion surface (21a) and looks bright. Therefore, the higher the dot density of the illumination light, the brighter it looks, and the lower the dot density, the darker it looks.

  Therefore, according to the second aspect of the present invention, in a place where a large amount of light is concentrated in the light guide plate (20) and a large amount of light is formed, the dot density is formed to be low. Can be made to look even darker. Similarly, in the light guide plate (20) where light is not concentrated so much and the amount of light is small, the dot density is formed to be high, so that the dark line due to the small amount of light can be made to look a little brighter. . As described above, the bright and dark lines generated in the illumination light can be made inconspicuous, and the appearance of the vehicle display device can be improved.

  Further, since a plurality of dots (21b) are formed, the bright line which has conventionally been visually recognized as a line extending continuously and connected to a single line is visually recognized as a bright line which appears intermittently bright by the dots (21b). Similarly, the dark line which has conventionally been visually recognized as a linear line extending in a line is now visually recognized as a dark line which appears intermittently dark by the dot (21b). Therefore, the bright line and the dark line can be made less noticeable.

  According to the third aspect of the present invention, among the dots (21b), the dots (21b) having a longer optical path distance from the light source (40) are formed so that the degree of light diffusion increases. It is characterized by. Thereby, in addition to the bright line and the dark line, the change in the light amount due to the difference in the optical path distance is canceled by the change in the degree of diffusion of the dots (21b). Thus, it is possible to suppress unevenness in brightness.

  According to the fourth aspect of the present invention, the dots (21b) are formed such that the dot density is higher as the dot (21b) has a longer optical path distance from the light source (40). Features. Thereby, in addition to the bright line and the dark line, the change in the light amount due to the difference in the optical path distance is canceled out by the change in the dot density. The occurrence of unevenness can be suppressed.

  Here, since the bright line and the dark line are generally generated so as to extend substantially parallel to the incident surface (22a), the predetermined region is defined with respect to the incident surface (22a). It is desirable to set a belt shape extending substantially in parallel.

  Incidentally, of the light diffused by the dots (21b), the light diffused toward the inside of the light guide plate (20) has a larger amount of light than the light diffused toward the outside of the light guide plate (20). Therefore, when the dots (21b) are formed on the back surface of the light guide plate (20) as in the invention described in claim 6, the illumination in the predetermined region is more intensive than when the dots (21b) are formed on the front surface. The light amount of the entire light can be increased, and the luminance of the entire illumination light in a predetermined area can be improved.

  In the invention according to claim 7, a light source (40), a light guide plate (20) having an incident surface (22a) for receiving light from the light source (40), and a holder for installing the light guide plate (20). A light-diffusing portion for diffusing light in at least one of the front surface (20f) and the rear surface (20r) of the light guide plate (20) in a visible range (20a) visible to a vehicle occupant. A surface (21a) is formed, and light incident from the incident surface (22a) and guided into the light guide plate (20) is diffused by the diffusion surface (21a), and illumination light is emitted from the surface of the light guide plate (20). In the illuminating device for a vehicle display which emits light in a plane, the holder portion (50) has a plurality of dots (21d) on a surface on which the light guide plate (20) is installed and a plurality of dots (21d) on a back surface of the light guide plate. And a plurality of convex portions (21c), They are interspersed in a direction parallel to the incident surface of the light guided in the optical plate, is characterized in that the light diffusing degree is arranged so as to alternately change in that direction.

  As described above, by forming the plurality of protrusions (21c) on the holder part (50), the degree of light diffusion differs between a part where the protrusions are arranged and a part where the protrusions are not arranged. That is, since the portions where the convex portions are arranged and the portions where the convex portions are not arranged are alternated, the light diffusion degree changes alternately. Therefore, since one bright line is intermittently bright due to the convex portion, one bright line can be made inconspicuous. In addition, dark lines appearing at portions where light does not concentrate become inconspicuous because light is diffused on the diffusion surface (21a) formed on the light guide plate (20). In this way, bright lines and dark lines can be made inconspicuous.

  According to an eighth aspect of the present invention, the plurality of protrusions (21c) are colored. As described above, the degree of light diffusion can be changed by coloring the protrusions. Specifically, for example, when the color of the dot is black, the degree of light diffusion can be further reduced.

  Similarly, when the diffusing surface (21a) is formed on the back surface of the light guide plate (20) as in the ninth aspect of the present invention, compared with the case where the diffusing surface (21a) is formed on the front surface, the entirety of the illumination light is reduced. The amount of light can be increased, and the luminance of the entire illumination light can be improved.

  According to the tenth aspect of the present invention, the plurality of protrusions (21c) are arranged in a predetermined area (50b) of the holder portion (50) on the surface on which the light guide plate (20) is installed, and the plurality of protrusions are provided. The top portion of (21c) is in contact with the back surface of the light guide plate (20), and the contact portion forms a plurality of dots (21d) on the back surface of the light guide plate. .

  As described above, by forming the dots (21d) by contacting the tops of the protrusions (21c) with the back surface of the light guide plate, the unevenness of the diffusion surface (21a) at the portion where the tops of the protrusions are in contact is eliminated. be able to. As a result, light is not diffused at the portion of the rear surface of the light guide plate (20) where the apex of the convex portion contacts, so that the degree of light diffusion is reduced. Therefore, one bright bright line becomes an intermittent line, so that the bright line can be made inconspicuous.

  According to the eleventh aspect, the light guide plate (20) is provided with the reflecting surface (22b) inclined with respect to the diffusing surface (21a), and the light incident from the incident surface (22a) is reflected. It is characterized by being guided to the diffusion surface (21a) after being reflected by the surface (22b). When such a reflection surface (22b) is provided, it is exemplified in FIG. As described above, the variation in the amount of light incident on the diffusion surface (21a) from inside the light guide plate (20) is further increased, and bright lines and dark lines are more likely to be generated. Therefore, in such a case, it is preferable to adopt the invention described in any one of the first to tenth aspects.

  In addition, specific examples of the light source (40) of the present invention include light-emitting diodes, lamps, cold-cathode tubes, light-emitting elements such as electroluminescent elements. In the case of light-emitting diodes, the light-emitting diodes are point light sources. Since light incident on the light guide plate (20) is easily collected, bright lines and dark lines are particularly likely to occur. Therefore, it is desirable to apply the invention according to any one of claims 1 to 11 when a light emitting diode is employed as described in claim 12.

  In addition, the code | symbol in the parenthesis of each said means shows the correspondence with the concrete means described in embodiment mentioned later.

(1st Embodiment)
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following, the same members as those shown in FIGS. 8 and 9 are denoted by the same reference numerals.

  In the present embodiment, the present invention is applied to a lighting device of a display installed on an instrument panel of a vehicle, and the lighting device of the present embodiment functions as a backlight of a liquid crystal panel 10 described later. is there. Specific examples of the display include an instrument such as a speedometer and a tachometer, and a display of a navigation device.

  FIG. 1 is a view showing the display device according to the present embodiment, and is a cross-sectional view as seen from a direction perpendicular to a viewing direction of a vehicle occupant. FIG. 1 is a diagram simulating a trajectory of light when the diffusion surface 21a of the back surface 20r of the light guide plate 20 is removed, and a symbol K indicates a portion where light is concentrated.

  The display includes a liquid crystal panel 10, a light guide plate 20, a printed wiring board 30, and a light source 40. The lighting device includes at least a light guide plate 20, a printed wiring board 30, and a light source 40. Further, the light guide plate 20 and the printed wiring board 30 are sequentially stacked and arranged on the rear surface side (the lower side in FIG. 1) of the liquid crystal panel 10.

  The light source 40 mounted on the printed wiring board 30 employs a light emitting diode, and more specifically, a vertical light emitting diode that emits light in a direction perpendicular to the mounting surface on the printed wiring board 30. Has been adopted.

  The light guide plate 20 is formed of a translucent resin such as acrylic, and has an L-shaped cross section as shown in FIG. That is, the light guide plate 20 includes a light emitting unit 21 that extends in a plate shape substantially parallel to the liquid crystal panel 10, and an incident light guide unit that extends in a plate shape so as to be inclined with respect to the liquid crystal panel 10 from a side end of the light emitting unit 21. 22 to form an L-shape.

  Then, of the incident light guide 22, the lower end of the incident light guide 22 has an incident surface 22 a through which light from the light source 40 is incident, and the upper end of the incident light guide 22 receives light incident from the incident surface 22 a. A reflection surface 22b that reflects toward the light emitting unit 21 is formed. The incident surface 22a and the reflecting surface 22b have a shape extending in a direction perpendicular to the plane of FIG.

  FIG. 2 is a diagram showing the light guide plate 20 and the light source 40 as viewed from an arrow A in FIG. The area surrounded by the dotted line in FIG. 2 indicates a visible range 20 a that can be visually recognized by a vehicle occupant, and corresponds to the display surface of the liquid crystal panel 10. Further, a diffusion surface 21a for diffusing light is formed in the visible range 20a of the back surface 20r of the light guide plate 20. The diffusion surface 21a is formed by roughening the surface roughness of the back surface 20r of the light guide plate 20, and can be easily formed by, for example, graining. Note that the surface roughness referred to here refers to a height difference from the back surface 20r of the light guide plate 20, that is, a degree of unevenness. Therefore, the greater the difference between the highest position and the lowest position in the vertical direction of the back surface 20r, the greater the surface roughness.

  The light reflected by the reflection surface 22b and guided to the light emitting unit 21 while being totally reflected by the front surface 20f and the back surface 20r of the light guide plate 20 is incident on the diffusion surface 21a and diffused, and the total reflection angle is reduced. Collapsed. Of the diffused light, light reflected toward the surface 20f of the light guide plate 20 is emitted from the surface 20f toward the liquid crystal panel 10. That is, the illumination light is emitted from the surface 20f of the light guide plate 20 in a planar shape. Then, the illumination light passes through the liquid crystal panel 10 and is emitted from the liquid crystal panel 10 as predetermined display image light.

  A plurality of dots 21b for diffusing light are formed in a predetermined region 20b of the visible range 20a on the back surface 20r of the light guide plate 20. The dots 21b are formed by roughening the surface roughness of the back surface of the light guide plate 20, similarly to the diffusion surface 21a, and are easily formed by, for example, graining.

  The predetermined region 20b is a band-like region extending substantially parallel to the incident surface 22a, and thus extends in a direction perpendicular to the plane of FIG.

  FIG. 3 is an enlarged view of a portion B in FIG. As shown in this figure, the dots 21b are formed in a square. When the dots 21b are formed in a square shape, it is desirable to set the length of one side of the dots 21b to 0.1 mm to 1.0 mm and the dot density to 10% to 70%. Here, the dot density is the ratio of the area occupied by the dots 21b per unit area of the predetermined area 20b.

  The dots 21b are formed such that the degree of light diffusion, that is, the surface roughness, becomes smaller as the dots 21b are located at locations where the amount of light incident from inside the light guide plate 20 is larger.

  More specifically, a plurality of lines shown in the light guide plate 20 of FIG. 1 are simulation results showing the trajectory of light from the light source 40 in a state where the diffusion surface 21a and the dots 21b are removed. 3 shows a portion of the back surface 20r of the light guide plate 20 where light is concentrated and the amount of light is large. Therefore, in the portion indicated by the symbol K, the surface roughness of the dots 21b is reduced, and the light diffusion intensity is increased. Here, the light diffusion intensity refers to the intensity of the light diffusion degree.

  FIG. 4 is a diagram showing a change in the diffusion intensity on the line CC ′ in FIG. 3. Since the diffusion surface 21 a is formed as a whole, a predetermined value can be obtained at any point on the line CC ′. (See Y1 in FIG. 4). In addition, in the portion on the CC ′ line where the dot 21b is formed, in addition to the diffusion by the diffusion surface 21a, the diffusion is also performed by the dot 21b, so that the diffusion intensity is higher than other portions ( (See Y2 in FIG. 4).

  As described above, according to the present embodiment, in each of the dots 21b, at the portion where the light indicated by the symbol K is concentrated, the dots 21b are formed so that the surface roughness of the dots 21b is reduced to reduce the degree of light diffusion. Therefore, the bright line caused by the concentration of light can be made to look a little dark.

  On the other hand, in the portions other than the portion indicated by the reference character K, the dots 21b are formed so as to increase the surface roughness and increase the degree of light diffusion, so that dark lines in portions where light is not concentrated can be seen as bright as possible. it can.

  Therefore, the difference in brightness between a bright part where light concentrates and a dark part where light does not concentrate can be reduced, and bright lines and dark lines generated in the illumination light can be made inconspicuous. The appearance of the displayed display image light can be improved.

  Furthermore, since the surface on which the degree of light diffusion is changed in accordance with the amount of incident light is constituted by a plurality of dots 21b, the bright lines and dark lines which have conventionally been viewed as a continuous line extending in a single line are intermittent by the dots 21b. This will be visually recognized as a line that extends in a horizontal direction. Therefore, the bright line and the dark line can be made less noticeable.

  In the present embodiment, among the dots 21b, as the dots 21b are located at positions where the optical path distance from the light source 40 is longer, that is, as the dots 21b are located at positions farther from the incident light guide unit 22 of the light emitting unit 21, It is formed so that the degree of light diffusion is increased independently of whether or not it is the light concentration point K. Accordingly, in addition to the bright line and the dark line, a change in light amount due to a difference in optical path distance is canceled out by a change in the degree of diffusion of the dots 21b. In addition, the occurrence of unevenness in brightness can be suppressed.

  By the way, of the light diffused in the dots 21 b and the diffusion surface 21 a, the light diffused inward of the light guide plate 20 has a larger light amount than the light diffused outward of the light guide plate 20. Therefore, in the present embodiment, the dots 21b and the diffusing surface 21a are formed on the back surface 20r of the light guide plate 20, whereby the luminance of the entire illumination light can be improved.

(2nd Embodiment)
In the present embodiment, only parts different from the first embodiment will be described. In the first embodiment, the plurality of dots 21b for diffusing the light are formed on the surface (back surface 20r) of the light guide plate 20 opposite to the surface that is viewed, but in the present embodiment, the light guide plate 20 Is different from the first embodiment in that the convex portion 21c is formed in the case where the is installed.

  FIG. 5 is a cross-sectional view of a cross section parallel to the viewing direction in the lighting device of the present embodiment. As shown in this figure, the present embodiment has a configuration in which a case 50 is added to the configuration of the lighting device shown in the first embodiment. FIG. 6 is a view of the light source 40 and the light guide plate 20 of FIG. 5 as viewed from an arrow D, and FIG. 7 is a view of the light source 40 and the case 50 of FIG.

  As shown in FIG. 6, a diffusion surface 21a is formed on the back surface 20r of the light guide plate 20 in the visible range 20a. This diffusion surface 21a is for diffusing light, as in the first embodiment. That is, the light incident on the diffusion surface 21a breaks the total reflection angle and is scattered in various directions, so that the light reflected on the diffusion surface 21a looks bright. Such a diffusion surface 21a is easily formed on the light guide plate 20 by graining or the like. The diffusion surface 21a is formed on either the front surface 20f or the back surface 20r of the light guide plate 20, but in the present embodiment, the diffusion surface 21a is formed on the back surface 20r of the light guide plate 20.

  The case 50 is for mounting the light guide plate 20, and is formed of, for example, a plastic resin. In addition, on the surface of the case 50 where the light guide plate 20 is installed, as shown in FIG. 7, a plurality of convex portions 21c are formed in a predetermined region 50b. The size, shape, and arrangement of the plurality of protrusions 21c are the same as those of the dots 21b of the first embodiment. The case 50 corresponds to a holder in the present invention.

  The position of the predetermined area 50b of the case 50 corresponds to the position of the predetermined area 20b of the visible area 20a in the first embodiment. That is, the predetermined region 50b is provided so as to cover the light concentration point K shown in FIG.

  The convex portion 21c as described above is formed in a predetermined region 50b of the case 50 by, for example, a printing process.

  The printing process is a method of directly printing a dot pattern on a predetermined area 50b of the case 50 using a printing machine or the like. In the printing method as described above, since the printing paint adheres to the case 50, the convex portion 21c of the printing paint is formed in the predetermined region 50b of the case 50. In this manner, the projection 21c made of the printing paint can be formed on the case 50.

  At this time, the degree of light diffusion can be controlled by using a printing paint of a desired color. For example, when a dark color such as black is used, the degree of light diffusion can be reduced. That is, the portion other than the protrusion 21c looks bright, and the portion of the protrusion 21c looks dark.

  As described above, instead of forming the dots 21b on the back surface 20r of the light guide plate 20, a plurality of convex portions 21c can be formed on the case 50 on which the light guide plate 20 is installed.

  After the projections 21 c are formed on the case 50, the light guide plate 20 is set on the case 50. That is, the rear surface 20r of the light guide plate 20 is installed so as to contact the top of the convex portion 21c formed in the predetermined region 50b of the case 50. At this time, when the top of the projection 21c is pressed against the diffusion surface 21a of the light guide plate 20, the top of the projection 21c comes into close contact with the diffusion surface 21a.

  That is, the top portion of the convex portion 21c pressed against the diffusion surface 21a is integrated with the diffusion surface 21a by the close contact of the top portion of the convex portion 21c with the diffusion surface 21a. This integrated portion becomes the dot 21d. Then, the unevenness on the diffusion surface 21a at the portion where the top portion of the protrusion 21a is in close contact disappears, and the portion of the dot 21d becomes a mirror surface, so that light is reflected without being diffused. Therefore, since the light is not diffused at the position of the top of the convex portion 21c closely contacted with the diffusion surface 21a of the light guide plate 20, that is, at the position of the dot 21d, it looks dark, and the light is diffused by the diffusion surface 21a at a position other than the dot 21d. Looks bright.

  Therefore, a straight luminescent line that appears on the light guide plate 20 in the viewing direction is a place where light is diffused due to the top portion of the convex portion 21c arranged at a predetermined interval being in close contact with the diffusion surface 21a of the light guide plate 20, Light is diffused alternately, such as where light does not diffuse, and where light diffuses. Therefore, the straight bright line looks like a broken line. In this manner, a bright portion of the light guide plate 20 where light is concentrated can be made inconspicuous.

  That is, a plurality of protrusions 21c are formed in a predetermined region 50b of the case 50 so that the protrusions 21c are arranged at the positions of K shown in FIG. 1, and the back surface 20r of the light guide plate 20 is further connected to the top portion of the protrusion 21c. , The light is prevented from being diffused at the convex portion 21c, that is, the degree of light diffusion can be reduced. Further, the light is totally reflected at the position of the dot 21 d without being diffused, so that the light can reach the tip of the light guide plate 20.

  In this way, by making the bright line look like an intermittent line such as a broken line, the bright line can be made inconspicuous. In addition, in a portion where a dark line appears in FIG. 1, light is diffused by the diffusion surface 21a, so that the dark line can be made slightly brighter.

  Therefore, even if a plurality of convex portions 21c are formed in the predetermined region 50b of the case 50 in which the light guide plate 20 is installed as in the present embodiment, the bright lines and the dark lines can be made inconspicuous as in the first embodiment. it can.

(Other embodiments)
In the above-described first embodiment, among the dots 21b, the dots 21b in the portion where the amount of light incident from the inside of the light guide plate 20 is large are formed so that the degree of light diffusion becomes smaller. The same effect as in the above embodiment can be obtained even if the dots 21b are formed so that the dot density is lower as the dots 21b are located at locations where the amount of light incident from inside the light guide plate 20 is larger. Note that specific examples of reducing the dot density include reducing the size of the dots 21b and increasing the dot pitch.

  In the second embodiment, a plurality of protrusions 21c are formed in a predetermined region 50b of the case 50. However, similar to the first embodiment, the protrusions 21c are portions where a large amount of light enters from inside the light guide plate 20. As the light diffusion degree decreases, the light diffusion degree may decrease. Further, the protrusions 21c may be formed such that the density of the protrusions 21c is lower as the protrusions 21c are located at locations where the amount of light incident from inside the light guide plate 20 is larger.

  In the first and second embodiments, the lighting device of the present invention is applied as a backlight of the liquid crystal panel 10. However, the present invention is not limited to this. For example, printing is performed on a light-transmitting plate. The lighting device of the present invention may be applied as a backlight of an instrument panel or other display panel formed by forming a light-transmitting portion and an opaque portion.

  Further, in the first embodiment, the dots 21b are formed only in the predetermined area 20b in the visible range 20a. In this case, when the dots 21b are molded with resin, masking is performed on a portion other than the predetermined area 20b. This necessitates the application, and the workability in the resin molding operation is poor. Therefore, in implementing the present invention, the dots 21b may be formed over the entire visible range 20a to eliminate the masking.

  In the first embodiment, the diffusing surface 21a and the dots 21b are formed by roughening the surface of the light guide plate 20 with a grain or the like. However, similar to the second embodiment, the light diffusing ink is used. It may be formed by printing on the light guide plate 20.

  In the second embodiment, the projection 21c can be formed in the predetermined region 50b of the case 50 by a coating process or a hot stamping process, in addition to the method of forming the projection 21c by the printing process.

  The coating process is a method in which a dot pattern mold is set in a predetermined area 50b of the case 50, and a paint is applied from the mold. The mold used for the coating process has a hole in a portion where the projection 21c is to be formed, and the paint enters the hole. In other words, the mold is set in the case 50, and the paint is applied on the mold, so that the paint enters the portion where the hole of the mold is opened and the convex portion 21c is formed by solidifying the paint portion. Has become. In this coating process, similarly to the printing process, the color of the paint can be changed, so that the degree of light diffusion can be controlled.

  On the other hand, hot stamping is a method in which a convex portion forming sheet is provided in a predetermined area 50b, and heat is applied from above the dot forming sheet to form the convex portions 21c. The protruding portion forming sheet used for forming the protruding portions 21 c is such that only the portion to which heat is applied melts and adheres to the case 50. That is, by pressing a large number of electric heating rods arranged in a dot pattern against the convex forming sheet, the portion of the convex forming sheet hit by the electric heating rod is attached to the case 50 to form the convex 21c. I have.

  Even when the above-described forming method is adopted, the plurality of convex portions 21c can be formed in the predetermined region 50b of the case 50.

  In the first and second embodiments, the dots 21b and 21d are square in shape, but another example is a circle.

It is a figure which shows the indicator which concerns on one Embodiment of this invention, Comprising: It is sectional drawing of the cross section in the direction parallel to the visual recognition direction of a vehicle occupant. FIG. 2 is a view showing the light guide plate and the light source in FIG. FIG. 3 is an enlarged view of a portion B in FIG. 2. FIG. 4 is a diagram showing a change in diffusion intensity on line C-C ′ in FIG. 3. It is the figure which showed the illumination device of 2nd Embodiment of this invention, and is sectional drawing of the cross section in the direction parallel to the visual recognition direction. FIG. 6 is a view as seen from an arrow D of the light source and the light guide plate shown in FIG. 5. FIG. 6 is a view as seen from an arrow E of the light source and the case shown in FIG. 5. It is sectional drawing of the cross section of the direction parallel to a visual recognition direction in a light guide plate, and is the figure which simulated the optical path of the light guide | induced to a light guide plate. It is the figure which looked at the light-guide plate by the present inventors' trial manufacture examination from the surface side.

Explanation of reference numerals

20: light guide plate, 21a: diffusion surface, 21b, 21d: dot, 21c: convex portion,
22a: entrance surface, 40: light source.

Claims (12)

A light source (40);
A light guide plate (20) having an incident surface (22a) for receiving light from the light source (40);
In at least one of the front surface (20f) and the back surface (20r) of the light guide plate (20), a diffusion surface (21a) for diffusing light is formed in a visible range (20a) visible to a vehicle occupant. ,
The light incident from the incident surface (22a) and guided into the light guide plate (20) is diffused by the diffusion surface (21a), and is planarized as illumination light from the surface of the light guide plate (20). In a lighting device for a vehicle display,
A plurality of dots (21b) for diffusing light are provided in a predetermined region (20b) of the visible range on at least one of the front surface and the rear surface of the light guide plate (20),
A lighting device for a vehicle display, wherein the degree of light diffusion of the dots (21b) decreases as the light in the light guide plate (20) concentrates more in the predetermined area. . A light source (40);
A light guide plate (20) having an incident surface (22a) for receiving light from the light source (40);
In at least one of the front surface (20f) and the back surface (20r) of the light guide plate (20), a diffusion surface (21a) for diffusing light is formed in a visible range (20a) visible to a vehicle occupant. ,
The light incident from the incident surface (22a) and guided into the light guide plate (20) is diffused by the diffusion surface (21a), and is planarized as illumination light from the surface of the light guide plate (20). In a lighting device for a vehicle display,
A plurality of dots (21b) for diffusing light are provided in a predetermined region (20b) of the visible range on at least one of the front surface and the rear surface of the light guide plate (20),
The illumination device for a vehicle display, wherein the density of the dots is lower as the light in the light guide plate is more concentrated in the predetermined area. 2. The dot (21 b), wherein the dot (21 b) having a longer optical path distance from the light source (40) has a greater light diffusion degree. 3. Or the lighting device of the vehicle display device according to 2. The dot (21b) is formed such that a dot (21b) having a longer optical path distance from the light source (40) among the dots (21b) has a higher dot density. 3. The lighting device for a vehicle display according to any one of items 3. The lighting device for a vehicle display according to any one of claims 1 to 4, wherein the predetermined region is set in a band shape extending substantially parallel to the incident surface (22a). The lighting device for a vehicle display according to any one of claims 1 to 5, wherein the dots (21b) are formed on a back surface of the light guide plate (20). A light source (40);
A light guide plate (20) having an incident surface (22a) for receiving light from the light source (40);
A holder part (50) for installing the light guide plate (20);
In at least one of the front surface (20f) and the back surface (20r) of the light guide plate (20), a diffusion surface (21a) for diffusing light is formed in a visible range (20a) visible to a vehicle occupant. ,
The light incident from the incident surface (22a) and guided into the light guide plate (20) is diffused by the diffusion surface (21a), and is planarized as illumination light from the surface of the light guide plate (20). In a lighting device for a vehicle display,
The holder section (50) includes a plurality of protrusions (21c) on a surface on which the light guide plate (20) is installed, forming a plurality of dots (21d) on the back surface of the light guide plate,
The plurality of protrusions (21c) are scattered in a direction parallel to an incident surface of the light guided into the light guide plate, and are arranged so that the light diffusion degree changes alternately in the direction. A lighting device for a vehicle display, comprising: The lighting device according to claim 7, wherein the plurality of protrusions (21c) are colored. The lighting device for a vehicle display according to any one of claims 1 to 8, wherein the diffusion surface (21a) is formed on the back surface of the light guide plate (20). The plurality of protrusions (21c) are arranged in a predetermined region (50b) of a surface of the holder portion (50) on which the light guide plate (20) is installed,
The tops of the plurality of projections (21c) contact the back surface of the light guide plate (20), and the contacted portions constitute the plurality of dots (21d) on the back surface of the light guide plate. The lighting device for a vehicle display according to any one of claims 7 to 9, wherein: The light guide plate (20) includes a reflection surface (22b) inclined with respect to the diffusion surface (21a),
The light incident from the incident surface (22a) is reflected by the reflection surface (22b) and then guided to the diffusion surface (21a). 4. A lighting device for a vehicle instrument according to claim 1. The lighting device of a vehicle instrument according to any one of claims 1 to 11, wherein the light source (40) is a light emitting diode.

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