JP2002260427A - Lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance display quality in a reflection liquid crystal device by preventing the light from scattering to a display direction peculiar to a point light source of a lighting device containing the point light source. SOLUTION: This lighting device is equipped with at least one point light source and a light guide plate having a reflector that reflects the illuminating light from the point light source to a lighted substrate. Then, the lighting device is equipped with a optical member 1 having micro prisms outputting the illuminating light to the light guide plate, where an output direction of the illuminating light and intensity distribution of the light are changed by refracting the illuminating light from the point light source according as its incident angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device used for a reflection type liquid crystal display device.

[0002]

2. Description of the Related Art Generally, a liquid crystal display device is provided with a lighting device so that it can be used even when the surroundings are dark. When roughly classified, there are a backlight-type lighting device that illuminates from the back side of a transmissive liquid crystal display device, and a front-light-type lighting device that illuminates from the front side of a reflective liquid crystal display device. Since small portable devices are required to be small and light and have low power consumption, reflective liquid crystal display devices are often used for display.
A front light type lighting device capable of lighting when needed is mounted.

In a conventional front light type illuminating device, a light guide plate is provided in front of a liquid crystal display screen, and illumination light is incident on the light guide plate from a lateral direction to brighten the entire screen. Therefore, it is desired that the entire screen has a uniform brightness, and a linear light source such as a fluorescent lamp is arranged on a side surface of the screen to receive illumination light.

[0004] However, when a fluorescent lamp is used, there is a problem that the thickness of the illuminating device is increased.
It has been considered to use a point light source such as ED). When this point light source is used, downsizing and low power consumption can be realized, but on the other hand, since it is a point light source, the difference in light intensity (luminance unevenness) on the display screen becomes large between near and around the light source. There is. For this reason, various attempts have been made to arrange a plurality of point light sources or to arrange a diffusion plate between the point light source and the light guide plate to alleviate the luminance peak.

[0005]

In the case of the above-described lighting device using a point light source, in the configuration in which the point light source is diffused by the diffusion plate, only the divergence angle of the light beam incident on the light guide plate is increased, and Is not changed, and the light source itself emits light from one point. Accordingly, the effect is such that the luminance unevenness of the entire screen is slightly alleviated.

The light guide plate is provided with a rib-like projection having a reflection surface for reflecting the light toward the liquid crystal display unit, and is designed to make the brightness uniform. However, when this is performed, continuous bright lines (scattered light) are generated by reflection at the protruding portions, and linear streaks appear on the screen, causing a problem in viewability. When the above-mentioned diffusion plate is used for this problem, the streak is blurred to a degree, and it cannot be said that this problem has been solved in terms of visibility.

On the other hand, for example, Japanese Patent Application Laid-Open No. 10-188
636 discloses a light guide plate 81 as shown in FIG.
A large number of columnar projections 82 are formed on the reflection surface of
There has been proposed an illumination device that diffuses incident light from No. 3 and suppresses the generation of continuous bright lines to realize uniform illumination. This technology uses bright lines (scattered light) that look like linear streaks.
This technology has the effect of suppressing the occurrence of light, but this technology, like the diffusion plate, only diffuses the illumination light at many points on the display screen and prevents the luminance unevenness from becoming linear. Since there is no function to change the direction of the incident light beam, when viewed from the entire screen, the brightness increases as the point light source is closer, and the ring spreads darker as the distance from the light source increases. There is no change.

Accordingly, the present invention provides a method of refracting illumination light from a point light source in accordance with the angle of incidence on a light guide plate, and converting the direction and light intensity distribution to make it uniform like a line light source. It is an object of the present invention to provide a lighting device that improves display quality by removing scattering in a display direction unique to a light source.

[0009]

According to the present invention, at least one point light source for irradiating light is provided.
A light guide plate having a reflecting portion for reflecting the illumination light from the point light source toward the object to be illuminated, wherein the illumination light from the point light source is refracted in accordance with an incident angle to emit the illumination light. By converting the direction and light intensity distribution,
An illumination device includes an optical member that irradiates the light guide plate, wherein the optical member is disposed between the point light source and the light guide plate.

In the optical member, a microprism is formed on one of a light incident surface and a light exit surface to function to refract light rays. In the lighting device, the refractive angle of the microprism is α, the distance between the optical member on which the microprism is formed and the point light source is L,
When the pitch between the plurality of point light sources is P, and the effective spread half angle of the point light source is β, α = β, P / 2 = L · tan
The refraction angle of the microprism is set so as to be β.

Further, in an illumination apparatus comprising a point light source for irradiating light, and a light guide plate having a reflecting portion for reflecting illumination light from the point light source toward an object to be illuminated, the light incident surface of the light guide plate includes Provided is an illumination device in which a microprism for converting the traveling direction of the illumination light and the light intensity distribution is formed by refracting illumination light from a point light source according to an incident angle.

In the illuminating device having the above-described structure, the optical member having the microprism formed on one surface refracts the illuminating light emitted from the point light source in accordance with the incident angle to change the incident direction and emit the light. By arranging the optical member in front of the light guide plate, light rays are incident on the light guide plate in various directions to prevent bright lines (hereinafter, referred to as bright lines) that appear as straight streaks due to scattered light. Illuminate the liquid crystal display uniformly.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. The present invention relates to a lighting device equipped with a prism-shaped (microprism) optical member that converts the angle of incidence on a light guide plate by refracting the light spread from a point light source in accordance with the angle of incidence. It is arranged in front of the surface to make the intensity distribution of the light source flatter. FIG. 1 shows a first example of the lighting device of the present invention.
The optical member according to the embodiment is shown and conceptually described.
In this example, a lighting device including two point light sources will be described as an example for simplification of description. The arrows in the figure indicate the traveling direction of each light beam.

The optical member 1 shown in FIG. 1 (a) shows a state viewed from above, and includes a flat entrance surface 1a and an exit surface 1b formed with a prism shape in which a plurality of triangular prisms to be described later are formed. , And is formed of a transparent resin, glass, or the like. In this figure, the arrow indicates the path of the light beam serving as the illumination light, and the prism apex angle γ is assumed to be 90 degrees, but is variously changed according to the design as described later.

Further, on the incident surface 1a side of the optical member 1, two point light sources 2, 3 are arranged at a distance L and at a pitch P. As shown in FIG. 1B, the refraction angle α of the optical member 1 is represented by a relative angle between a vertically incident light beam and an emitted light beam.

A description will be given of the change of the traveling direction and the light intensity distribution of the illumination light (light beam) in the optical member 1. For example, the effective half angle of the light beam emitted from the point light source 2 is β
And the light ray 10 in that direction, the light ray 10 is refracted by the entrance surface 1a and the exit surface 1b of the optical member 1, respectively, and is converted into substantially the Z direction to be emitted. Set. The Z direction is a direction perpendicular to the incident surface of the light guide plate (not shown). That is, the prism vertex angle γ is set so that α = β. Ray 11 is similar to ray 10. On the other hand, among the light beams emitted from the light source 2 in the substantially Z direction, the light beam 13 is totally reflected on the emission surface 1b side and then returns to the light source 2 side again, so that it does not enter the light guide plate. However, near the apex of the prism, there is also a microscopically partially flat surface that can be manufactured with accuracy, and the light beam 14 incident on that surface is not totally reflected but transmitted and proceeds to the light guide plate.

Therefore, when viewed from the light guide plate side, it behaves as if it is emitted as a linear light beam having a width extending over the same light beams 10, 11, and 14 traveling in the same Z direction. Similarly, the light beams 15 and 16 and the light beam 17 emitted from the adjacent point light source 3 are also emitted as illumination light having a width ranging from the light beam 15 to the light beam 17 although the irradiation directions are different.

The interval P between the point light sources 2 and 3 may be determined so that the light beam 11 and the light beam 18 substantially overlap each other when the effective spread half angle is β. P / 2 = L · tan β (1) ). When the effective spread half angle β of the light source is made wider, for example, the above formula (1) may be set so that the light beams 17 and 19 substantially overlap on the emission surface of the optical member 1. The optical member 1 can have a refractive index distribution to obtain an effect equivalent to the refraction effect of the prism.

FIG. 2 shows a configuration example of a lighting device in which the optical member of the present embodiment is mounted on a light guide plate. Here, FIG. 2A shows a configuration viewed from above, and FIG.
3A illustrates a cross-sectional configuration taken along line AA. The arrows in the figure indicate the traveling directions of the respective light beams. This illuminating device includes, for example, three light emitting diodes (LEDs) 4a, 4b, and 4c serving as point light sources 4, and accommodates these point light sources 4 and arranges them in a straight line. And a U-shaped casing 5 in which the optical member 1 is disposed. The number of the point light sources 4 is an arbitrary number in consideration of a required luminance value and power consumption, and the point light sources 4 are driven by a drive circuit (not shown) through an electrical connection to emit light.
The housing 5 also functions as a reflector for efficiently causing the illuminating light having the spread of the point light source 4 to enter the light guide plate 6, and has aluminum or white Teflon (registered trademark), barium sulfate on the inner surface thereof. And a light reflectance member made of a powder such as magnesium oxide. Further, these light reflectance members may be formed in a sheet shape and attached to the inner wall of the housing 5.

The material of the light guide plate 6 is made of, for example, an acrylic, polycarbonate or polyolefin material and has a refractive index of about 1.5. Light rays having an incident angle equal to or greater than the critical angle among the light rays incident on the light guide plate 6 propagate through the light guide plate while totally reflecting the flat portion 6a and the opposing surface 6b. The critical angle is determined by sin (1 / 1.5) from the refractive index of the material, and is about 42 degrees. A part of the light beam having an incident angle greater than the critical angle propagating in the light guide plate is reflected toward the liquid crystal display unit 7 by the minute reflecting surface 6c, and is reflected again to the observer side B according to the reflectivity of the liquid crystal. By doing so, an image displayed on the liquid crystal is observed.

As described above, the illumination device of the present embodiment uses an optical member having a microprism formed on one surface, thereby refracting the illumination light emitted by the LED, which is a point light source, according to the incident angle. In addition, the direction of incidence of the illumination light on the light guide plate can be changed to prevent bright lines due to scattered light, thereby uniformly illuminating the liquid crystal display unit.

Next, a lighting device according to a second embodiment will be described. FIG. 3 shows an example of the light intensity distribution by the optical member 1 of the first embodiment described above. As shown in the figure, the light intensity distribution at the time of light emission of the LED 4 as a point light source is characterized in that the light intensity becomes the highest peak in front of the light emitting source, and decreases toward the periphery. On the other hand, the light intensity distribution (solid line m) of the illumination light transmitted through the optical member 1 is L
Compared to the light intensity distribution of the ED4, two peaks are formed on both sides slightly away from the front on the light emitting side to the peripheral side, and the front has a weaker intensity distribution. This is because the illumination light emitted from the front of the point light source includes the light beam 13 reflected by the prism of the optical member 1 and returned as shown in FIG. Occurs because the amount transmitted is small.

Therefore, in this embodiment, the diffusion plate 8 is provided between the point light source 4 and the optical member 1 in the first embodiment.
Are arranged to make the light intensity distribution transmitted through the optical part 1 flat. Here, FIG. 4A illustrates a configuration viewed from above, and FIG. 4B illustrates a cross-sectional configuration taken along line CC of FIG. 4A. By transmitting the illumination light through the diffusion plate 8, as shown in FIG. 5, light beams having various emission angles are incident on the optical member 1 from almost the same place.
When viewed from the light guide plate 6 side, the light is emitted in various directions like the light rays 20 and 21, and is diffused in various directions from each point, as shown by the light intensity of the illumination light indicated by the dotted line n in FIG. become,
It can be closer to line lighting or area lighting.

Next, a third embodiment will be described.

In the above-described embodiment, the diffusion plate is used to
Although the light intensity distribution is flattened, the present embodiment is an example in which the optical member is improved to realize the flattened light intensity distribution. The optical member of the present embodiment is provided with a prism-deficient portion that increases the transmission of illumination light in the front portion facing the point light source.

As shown in FIGS. 6A and 6B, the optical member 31 is positioned at a position facing the point light source according to the intensity distribution.
There is provided a prism-deficient portion 32 composed of two holes. Of course, the four holes are merely an example, and one to a plurality of holes can be provided, and the arrangement is also made to flatten the light intensity distribution. The above-described refraction angle α of the optical member, the distance L between the optical member and the point light source, the pitch P between the plurality of point light sources,
If the combination of the effective divergence half angles β of the point light source is not always equal to that of the linear light source, the prism deficient portion 32 is provided, and the intensity of the point light source is usually the strongest. Can be converted to a flatter linear light source.

In this embodiment, the prism defective portion 32 composed of four holes is provided, but the shape is arbitrary.
The function can be achieved if the area of the prism shape can be changed in place.

FIGS. 7A and 7B show a first modified example of the above-described prism-deficient portion of the optical member 31. FIG. In this example, a flat region 33 is provided as a prism-deficient portion, without the prism formed on the exit surface side facing the point light source. By providing the flat region 33, an effect equivalent to that of the third embodiment can be obtained.

FIGS. 8A and 8B show a second modified example of the above-described prism-deficient portion of the optical member 31. FIG. In this example, a rectangular hole 34 is formed at a portion facing the point light source as a prism defect portion. This rectangular hole 3
By forming 4, an effect equivalent to that of the third embodiment can be obtained.

FIGS. 9A and 9B show a third modification of the above-described prism-deficient portion of the optical member 31. FIG. In this example, a concave hole 35 whose center is narrower and narrower than its end is formed in a portion facing the point light source as a prism lacking portion. By forming the concave hole 35, an effect equivalent to that of the third embodiment can be obtained.

Next, a fourth embodiment will be described.
FIG. 10 shows an example in which the prism-shaped portion of the optical member shown in FIG. 1 is arranged not on the light guide plate side but on the point light source side. Here, the illustrated arrows indicate the traveling directions of the respective light beams. As an advantage of such an optical member 41, the same effect can be obtained. However, as shown in the figure, a light source 42 of the illumination light incident on the top of the prism (convex or concave) facing the point light source and the front. Only the light transmitted through the light guide plate as it is and is incident from the vertical direction (Z direction) of the incident surface of the light guide plate, and the light beam emitted from the point light source 40 and having a divergence angle close to the refraction angle of the prism shape enters the light guide plate. Then, the light propagates substantially in the Z direction. The light beam 43 is emitted so that most of the other portions go to the outer end. As a result, of the incident light rays, the straight light rays are divided into almost two rays, and one point light source behaves as if it were two rays. Light emitted from the point light source at an angle near the spread angle of 0 ° is bent by refraction and enters the light guide plate. In this arrangement, there is almost no loss due to total reflection in the prism, and there is an effect that the amount of illumination can be improved as compared with the first embodiment.

FIG. 11 shows, as a fifth embodiment, an example of the configuration of an illumination device in which a prism-shaped portion is formed on a light guide plate. This illumination device includes an incident surface 44 of a light guide plate 44.
This is an example in which the aforementioned prism-shaped portion is formed on the a side,
The diffusion plate 8 is arranged between the three point light sources 4 and the incident surface 44a. With such a configuration, the number of components can be reduced, and the cost can be reduced. still,
In the present embodiment, the diffusing plate 8 is disposed in front of the light guide plate 44. Alternatively, the diffusing plate 8 may have a diffusing function by roughening the surface of the prism-shaped portion of the incident surface 44a. This makes it possible to further reduce the number of components.

FIG. 12 shows an example of the configuration of a lighting device according to the sixth embodiment. Here, FIG. 12A shows a configuration viewed from above, and FIG. 12B shows a configuration viewed from an incident surface from a point light source side. The illustrated arrows indicate the traveling directions of the respective light beams.

The light guide plate 51 has one side as an incident portion, and has three prismatic refraction portions 51a and 51a.
b, 51c have flat portions 52a, 52b therebetween.
Are formed. In addition, these refraction portions 51a,
A point light source 4 composed of light-emitting diodes (LEDs 4a, 4b, 4c) is arranged so as to face the central position of 51b, 51c.

In such a configuration, the light beam emitted from the point light source 4 at a divergence angle of about 0 degrees propagates in the light guide plate in a direction substantially equal to the refraction angle of the prism shape while being totally reflected inside the light guide plate. On the other hand, a light beam having a large divergence angle emitted from the point light source 4 enters the flat portion and propagates obliquely according to Snell's law. In this case, when the display is observed from a direction perpendicular to the surface of the light guide plate 51, which is the most used observation angle, the streak-like scattering pattern described in the section of the problem caused by the ray group traveling in the Z direction is not seen. .

Accordingly, by setting the directions of all the light rays propagating in the light guide plate 51 not in the Z direction but in the ZX plane, it is possible to eliminate the scattering lines seen when the display is observed almost from the front. it can. Of course,
By providing the diffused shape at the incident portion of the light guide plate 51, a more uniform distribution can be obtained.

The flat portion 52 of the incident surface of the light guide plate 51
Since a and 52b are regions where only light beams not parallel to the Z direction are incident from the point light sources 4a, 4b and 4c, it is not necessary to form the refraction portions 51a, 51b and 51c.

FIG. 13 shows flat portions 52a and 52b on the incident surface of the light guide plate 51 in the sixth embodiment.
This is a modified example in which a non-refractive area is provided by slit-shaped flat portions 53a and 53b.

FIG. 14 shows an example of the configuration of a lighting device according to the seventh embodiment and will be described. In the present embodiment, a Fresnel-shaped refraction portion 61 that converts a light beam having a divergent angle emitted from a point light source into a substantially parallel light beam is formed on the incident surface side of the optical member or the incident surface side of the light guide plate. . The width K of the Fresnel shape is made equal to the pitch P of the light source as shown in FIG. Further, in this shape, since the level of the intensity distribution by the point light source remains, as shown in FIG. 15, a prism 61b is formed by forming a central flat portion 61a of the refraction portion 61 substantially in the direction of 0 degrees from the point light source. Thus, a diffusion function may be provided. By forming a prism at the center of the Fresnel shape, parallel light beams emitted from the vicinity of the center of the point light source having the highest luminance can be reduced, and the light intensity distribution can be flattened.

Next, FIG. 16 shows an example of a mounting structure for fixing the above-mentioned optical member to the light guide plate.
In this mounting configuration example, pin-shaped projections 62a and 62b are provided on the light guide plate 63 outside the effective surface L1 and fixing holes 65a and 65b are formed at two places at both ends of the optical member 64, thereby facilitating mounting. This is an example in which a reliable positioning effect is obtained. Of course, it is also possible to fix with a tape-shaped member or to provide a protruding portion in a plane to facilitate fixing with a sheet member around the light source.

FIG. 17 shows a modification of the above-described mounting structure for fixing the optical member to the light guide plate. Two fixing holes 74a, 74b, 74c, 74 are respectively provided on the upper and lower sides of a U-shaped casing 71 for storing a point light source.
Open d. Protrusions 75a, 75b, 75c, 75d that fit into these fixing holes are formed on the optical member 72. Then, the optical member 72 is fitted into the housing 71 and attached to the light guide plate 73.

As described above, according to the lighting device of each of the above-described embodiments, it is possible to remove scattered light (bright lines) generated from the point light source from the light guide plate surface. In addition, a light emitting diode or the like having a large light emitting power per power consumption can be used as a line light source by arranging a plurality of light emitting diodes or the like as a point light source in a straight line with respect to the light incident surface of the light guide plate. At the same time, it is possible to obtain similar high-luminance illumination light.

[0043]

As described above in detail, according to the present invention, the illumination light from the point light source is refracted according to the incident angle to the light guide plate, and the direction and the light intensity distribution are converted to obtain a linear light source. By making them uniform, scattering in the display direction unique to the point light source can be removed, and an illumination device that improves display quality can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing an optical member according to a first embodiment in a lighting device of the present invention.

FIG. 2 is a diagram illustrating a configuration example of a lighting device in which the optical member according to the first embodiment is mounted on a light guide plate.

FIG. 3 is a diagram illustrating an example of a light intensity distribution by the optical member according to the first embodiment.

FIG. 4 is a diagram illustrating a configuration example of a lighting device according to a second embodiment.

FIG. 5 is a diagram illustrating an example of a traveling direction of a light beam in an optical member according to a second embodiment.

FIG. 6 is a view showing an optical member according to a third embodiment of the lighting device of the present invention.

FIG. 7 is a view showing a first modified example of the prism-deficient portion of the optical member according to the third embodiment.

FIG. 8 is a view showing a second modification of the prism-deficient portion of the optical member according to the third embodiment.

FIG. 9 is a view showing a third modification of the prism defect portion of the optical member according to the third embodiment.

FIG. 10 is a diagram showing an optical member according to a fourth embodiment of the lighting device of the present invention.

FIG. 11 is a diagram illustrating a configuration example of a lighting device in which an optical member according to a fifth embodiment is mounted on a light guide plate.

FIG. 12 is a diagram illustrating a configuration example of a lighting device in which an optical member according to a sixth embodiment is mounted on a light guide plate.

FIG. 13 is a view showing a modification of the light guide plate in the sixth embodiment.

FIG. 14 is a diagram illustrating optical members of a lighting device according to a seventh embodiment.

FIG. 15 is a view showing a modification of the light guide plate in the seventh embodiment.

FIG. 16 is a diagram showing an example of a mounting configuration for fixing an optical member of the lighting device of the present invention to the light guide plate.

FIG. 17 is a view showing a modification of the mounting configuration example for fixing the optical member of the lighting device of the present invention to the light guide plate.

FIG. 18 is a diagram illustrating a conventional lighting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical member 1a ... Incident surface 1b ... Outgoing surface 2, 3 ... Point light source 4, 4a, 4b, 4c ... Light emitting diode (LED) 5 ... Housing | casing 6 ... Light guide plate

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09F 9/00 336 G09F 9/00 336B // F21Y 101: 02 F21Y 101: 02

Claims (11)

[Claims] 1. A lighting device comprising: at least one point light source that irradiates light; and a light guide plate that has a reflecting portion that reflects illumination light from the point light source toward an object to be illuminated. By refracting the light according to the incident angle, the optical member includes an optical member that converts an emission direction and a light intensity distribution of the illumination light and emits the light to the light guide plate, wherein the optical member includes the point light source and the light guide plate. A lighting device characterized by being disposed between the lighting device and the lighting device. 2. The illumination device according to claim 1, wherein the optical member has a microprism formed on one of a light incident surface and a light output surface to function to refract light rays. 3. The illumination device according to claim 1, wherein a refraction angle of the microprism is α, a distance between an optical member on which the microprism is formed and a point light source is L, a pitch between the plurality of point light sources is P, 3. The lighting device according to claim 2, wherein when the effective spread half angle of the light source is β, the refraction angle of the microprism is set so that α = β and P / 2 = L · tanβ. 4. The illumination device according to claim 1, wherein a diffusion plate for diffusing light is interposed between the point light source and the optical member. 5. The illumination device according to claim 2, further comprising a function of providing minute irregularities on one of a light incident surface and a light exit surface of the optical member to diffuse light rays. The lighting device according to claim 1. 6. The illumination device according to claim 1, wherein the optical member is provided with a prism defect portion in accordance with an arrangement of a point light source and an intensity distribution. 7. A light source, comprising: a point light source for irradiating light; and a light guide plate having a reflecting portion for reflecting illumination light from the point light source toward an object to be illuminated. An illumination device, wherein a microprism is formed that refracts illumination light from a light source according to an incident angle, thereby converting a traveling direction and a light intensity distribution of the illumination light. 8. The illuminating device according to claim 7, wherein the illuminating device has a function of providing minute irregularities on a surface of a microprism formed on a light incident surface of the light guide plate to diffuse a light beam. Lighting equipment. 9. A lighting device comprising: a point light source for irradiating light; and a light guide plate having a reflecting portion for reflecting illumination light from the point light source toward an illuminated body, wherein the light incident surface of the light guide plate is A lighting device characterized in that the lighting device is formed in a Fresnel shape that converts the traveling direction and the light intensity distribution of the illumination light by refracting the illumination light from the point light source according to the incident angle. 10. The illumination device according to claim 9, wherein a prism is formed on a portion of the light incident surface where the Fresnel shape is formed, where a light beam having the highest luminance is incident from the point light source. Lighting equipment. 11. The illumination device, wherein the guide portion is provided in a region other than the effective surface on the light incident surface of the light guide plate, and is fitted to the guide portion in a region other than the effective surface on the light exit surface of the optical member. The lighting device according to claim 1, further comprising: a fixing hole that fits in the light guide plate, wherein the fixing hole is fitted into the guide portion to fix the light guide plate at a predetermined position.