JP2001283622A - Illumination apparatus and reflector liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the uniformity of the light distribution of an emitted light from a planar light conductor while using a dotted light source and a linear light conductor instead of a linear light source. SOLUTION: This illumination apparatus comprises the dotted light source 2, a linear light conductor 3 for emitting a light from the dotted light source 2, injected from one end and reflected from a reflecting plane provided on the other side face opposed to one side face, from one side face, and a planar light conductor 5 formed of a transparent material for emitting a light from the linear light conductor 3, injected from one end face and reflected from the inclined faces of a plurality of grooves 7 arranged on the surface in parallel to one another, from the reverse side. An illuminated object arranged on the reverse side of the planar light conductor 5 is illuminated and its reflected light is transmitted to the surface side. The grooves 7 in the planar light conductor 5 are formed to be inclined so that the ends on the side of the dotted light source 2 can come closer to the linear light conductor 3 than the ends on the opposite side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminating device suitably used in an OA device such as a personal computer, an image display device such as a portable information terminal, and various other display devices, and a reflection type liquid crystal display device using the same. Things.

[0002]

2. Description of the Related Art In recent years, personal computers, information terminals, video tape recorders, and the like have become more portable and smaller, and reducing the power consumption of such image display devices has become an important issue.

For this reason, an image display device using a reflection type liquid crystal display device is often used. The reflection type liquid crystal display device obtains the brightness of the screen by reflecting external light such as sunlight or indoor light, so that sufficient brightness cannot be obtained on the screen where there is little external light. Therefore, when there is a lot of external light, it does not hinder the illumination by the external light,
There has been a demand for the development of a reflective liquid crystal display device with an illuminating device capable of illuminating a liquid crystal panel when there is little external light. As such an illuminating device, a device using a transparent light guide plate is disclosed, for example, in Japanese Patent Application No. 9-224992. And Japanese Patent Application 10-0449
Some proposals have been made, as disclosed in, for example, Japanese Patent Application Laid-Open No. H.60.

An example of a reflection type liquid crystal display device using a transparent light guide plate will be described with reference to FIG. In FIG. 7, the reflection type liquid crystal display device includes an illumination device 24 including a linear light source 21, a reflector 22, and a transparent light guide plate 23, and a reflection type liquid crystal display panel 25. The linear light source 21 is disposed on one side surface of the transparent light guide plate 23, and a fluorescent lamp such as a hot cathode ray tube or a cold cathode ray tube, an incandescent lamp, or the like is used. The reflector 22 is formed by adhering a material having a high reflectance on a resin sheet and adhering the resin sheet to the resin sheet. The reflector 22 is disposed so as to cover the linear light source 21.
Is fixed to the end portion with an adhesive 26. Transparent light guide plate 2
3 has a plurality of V-shaped grooves 27 formed at predetermined intervals parallel to the linear light source 21 on the front side, and a reflective liquid crystal display panel 25 on the rear side.

In the reflection type liquid crystal display device having the above structure, the light emitted from the linear light source 21 propagates while totally reflecting inside the transparent light guide plate 23, and the propagated light passes through the groove 27 formed on the front surface side. The light is totally reflected by the inclined surface and is emitted to the back side of the transparent light guide plate 23 to illuminate the reflective liquid crystal panel 25. The light passes through the light plate 23 and is visually recognized by an observer.

[0006]

However, in the above configuration, since the linear light source 21 such as a fluorescent lamp or an incandescent lamp is used, the power consumption when illuminating using the illumination device 24 is considerably large. In addition, there is a problem that the thickness of the transparent light guide plate 23 and the height of the reflector 22 having the linear light source 21 built therein are reduced even if the thickness of the transparent light guide plate 23 is reduced in order to reduce the overall thickness of the display device. Since it is desirable that the diameter is the same, the diameter of the linear light source 21 must be made extremely small, so that there is a problem that it cannot be realized.

As a means for solving such a problem, a linear light guide 3 having a point light source 2 disposed at one end as shown in FIG. The light emitted from the light source 2 propagates in the linear light guide 3, and the groove 6 formed on the other side of the linear light guide 3 opposite to the side facing the planar light guide 5. It can be considered that the light is totally reflected on the inclined surface and is radiated toward the planar light guide 3.

However, when light is introduced from one end of the linear light guide 3, the light emitted from one side of the linear light guide 3 has its main direction 30 directed to one side of the linear light guide 3. With respect to the direction perpendicular to the direction, the light is inclined toward the side opposite to the side on which the point light source 2 is disposed, and therefore, a groove formed on the surface of the planar light guide 5 in parallel with the linear light guide 3. The distribution of the outgoing light reflected on the inclined surface 7 is a point light source partitioned by oblique lines 10a parallel to the main direction 30 of the outgoing light from the corner of the planar light guide 5 on the side where the point light source 2 is disposed. There is a problem that the triangular region 10 on the two sides becomes dark, and the light amount distribution over the entire surface of the planar light guide 5 is not uniform.

In view of the above problems, the present invention can ensure uniformity of the light quantity distribution of light emitted from a planar light guide while using a point light source and a linear light guide instead of a linear light source. It is an object to provide a lighting device and a reflective liquid crystal display device.

[0010]

According to the lighting device of the present invention, a point light source and light from the point light source incident from one end are reflected by a reflection surface provided on the other side opposite to one side. A linear light guide that radiates from one side, and a transparent light that reflects light from the linear light guide that is incident from one end surface on the slopes of a plurality of grooves arranged parallel to each other on the front surface and radiates from the back surface A planar light guide made of a body, and illuminates an object to be illuminated disposed on the back side of the planar light guide, and transmits reflected light thereof to the front side, comprising: The groove of the linear light guide is formed so that the end on the side of the point light source is closer to the linear light guide than the end on the opposite side.

According to such a configuration, since the point light source is used as the light source, the power consumption can be reduced, and the thickness of the linear light guide can be easily made the same as that of the planar light guide.
The thickness of the illuminating device can be reduced, and the main direction of the light emitted from the linear light guide toward the planar light guide is point-like with respect to the direction perpendicular to the linear light guide. Even if inclined to the opposite side to the light source, the direction of the highest reflection efficiency due to the slope of the groove of the planar light guide, that is, the direction orthogonal to the groove of the planar light guide is inclined to the point light source side. Therefore, the oblique line parallel to the main direction of the light emitted from the linear light guide and the base point of the planar light guide on the side of the point light source arrangement side is directed toward the triangular area on the point light source side. The reflection efficiency of the distributed light in the direction is high, the amount of light in that direction is increased, and the luminous intensity of the triangular area, which has been darkened conventionally, is improved, while the reflection efficiency of the emitted light in the main direction is relatively low. Since the amount of light is reduced, the uniformity of the amount of light emitted from the entire surface of the planar light guide can be ensured.

Further, when the point light source is an LED, the required light quantity can be obtained with small components, the thickness of the illuminating device can be reduced, and the cost is reduced because it is inexpensive. Can be.

When the point light source is bonded to one end of the linear light guide, light transmission efficiency is high, the arrangement is simple, and the cost can be reduced.

Further, when the distance d between the point light source and the side end face of the planar light guide is 0.5 mm or more, light from the point light source is prevented from directly entering the planar light guide. Thus, it is possible to prevent bright lines from being generated in the light emitted to the rear surface side of the planar light guide due to the directly incident light.

Further, when the linear light guide is formed of a rod-shaped transparent body having a substantially rectangular cross section, and the reflecting surface is constituted by arranging a plurality of V-shaped grooves parallel to each other in a direction substantially orthogonal to the longitudinal direction, Light transmission efficiency is high, and a single component can be made compact, lightweight and inexpensive.

Further, when the linear light guide is formed of a wedge-shaped rod-shaped transparent body having a smaller sectional area from one end to the other end,
The closer to the point light source, the more the light quantity can be prevented, and the more uniform the light quantity distribution of the emitted light in the longitudinal direction of the linear light guide.

Further, when the periphery of the linear light guide other than the surface facing the planar light guide is covered with a reflector, the utilization efficiency of light from the point light source can be improved, and the illumination efficiency can be improved.

The distance D between the side edge of the reflector covering the surface of the planar light guide and the illuminated area illuminated with light from the planar light guide is 0.5 mm or more. Then
The light reflected on the end side edge of the reflector does not adversely affect the illuminated area, and it is possible to prevent luminance unevenness from occurring in the illuminated area.

When the reflector is formed of a metal plate and is engaged with and fixed to the linear light guide or the planar light guide, the edge of the reflector is fixed to the planar light guide with an adhesive or the like. In this way, it is possible to prevent light from being irregularly reflected by the adhesive and adversely affecting the illuminated area.

Further, when another linear light guide having the same configuration is provided on the other side of the linear light guide opposite to the one side facing the planar light guide, another line is provided. The light emitted from the planar light guide enters the linear light guide disposed in contact with the planar light guide as scattered light from the opposite side to the planar light guide, and the planar light guide Therefore, the luminous intensity can be improved by increasing the amount of light emitted from the planar light guide as a whole.

At this time, it is preferable that a plurality of grooves inclined at an appropriate angle with respect to the longitudinal direction are formed on one side surface of at least one of the linear light guides facing the planar light guide. The light emitted toward the planar light guide is diffused by these grooves, so that the contrast of the moire fringes generated by the grooves forming the reflection surfaces of the linear light guides is reduced, and the moire fringes are reduced. Shadow can be reduced. When the inclination angle is about 15 °, the decrease in luminance is small and the shadow of the moire fringes can be eliminated.

Alternatively, even if one side surface of at least one of the two linear light guides which faces the planar light guide is formed in a matte texture, the light emitted toward the planar light guide is obtained. Is diffused, so that shadows due to moiré fringes can be eliminated. When the satin finish is formed by sandpaper processing using particles of # 2000 or less, a decrease in luminance can be reduced. Moreover, it is possible to process a satin finish which can obtain the same effect by sandblasting.

If the radius of curvature of at least the edge of the planar light guide opposite to the point light source, of the two end edges of the end face facing the linear light guide, is 0.1 mm or less, It is possible to prevent the generation of a bright line due to the reflection at the edge of the light guide.

Further, the reflection type liquid crystal display device of the present invention has a reflection type liquid crystal panel disposed on the back side of the illumination device, and the entire surface of the reflection type liquid crystal panel is uniform by the illumination device as described above. , High display quality can be ensured with a compact configuration.

Further, a protective sheet, a planar light guide and a reflective liquid crystal panel are fitted and arranged in a laminated state in a rectangular frame, and a linear light guide is inserted into a concave portion formed on one side of the frame. And a point-like light source are inserted and arranged, and the opening of the recess is covered and fixed with a reflector that covers the linear light guide, so that a reflective liquid crystal display device with a lighting device can be assembled very easily, and productivity is improved. It is possible to improve the cost and reduce the cost.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an illumination device according to an embodiment of the present invention will be described with reference to FIG. Reference numeral 1 denotes an illuminating device which illuminates an object to be illuminated disposed on the back side and allows the reflected light to pass through to the front side to be visually recognized. The point light source 2, the linear light guide 3, the reflector 4, the planar light guide It is composed of an optical body 5.

As the point light source 2, an LED or a small fluorescent lamp can be used. Among them, LEDs can obtain a required amount of light at a small size, light weight, and inexpensively, so that the thickness of the lighting device can be reduced and the cost can be reduced because they are inexpensive. . The point light source 2 is attached to one end of the linear light guide 3. By bonding the point light sources 2 in this manner, the light transmission efficiency can be increased and the arrangement configuration can be simplified,
Cost can be reduced.

The linear light guide 3 reflects light from the point light source 2 incident from one end on a reflection surface provided on the other side opposite to one side, and emits the light from one side. In this embodiment, the cross-sectional area is made of a wedge-shaped rod-shaped transparent body having a substantially rectangular cross-section and a cross-sectional area decreasing from one end where the point light source 2 is disposed to the other end, and the reflecting surface is formed by defining a V-shaped groove 6 with the longitudinal direction. They are formed at predetermined intervals in parallel with each other in a direction orthogonal to each other.

The rod-shaped transparent body is preferably made of a molded article of an acrylic resin or a polycarbonate resin because the production cost can be reduced, but it can also be made of glass or the like. Further, the rod-shaped transparent body may have a constant cross section, but in this case, the light amount decreases as the distance from the point light source 2 increases, so that a uniform light amount distribution can be obtained in the longitudinal direction of the linear light guide 3. It is preferable to use a wedge-shaped rod. Further, by forming the reflecting surface with the V-shaped groove 6, the reflecting surface can be made compact, lightweight and inexpensive with a single component, and high light transmission efficiency can be secured.

However, the linear light guide 3 is not limited to the above configuration as long as it emits the light from the point light source 2 from one side. However, by forming grooves or recesses of various shapes instead of the V-shaped grooves 6 forming the reflection surface, it is possible to devise an arbitrary light amount distribution. Or forming a reflective surface made of a material with high reflectivity such as silver or aluminum without using it,
It may be formed by attaching a reflection sheet having a reflection surface.

The reflector 4 covers the periphery of the linear light guide 3 made of a transparent rod other than the surface facing the planar light guide 5 and returns the light leaking to the periphery to the transparent rod. The use of a metal plate with a mirror-finished inner surface or a metal plate with a highly reflective material such as silver or aluminum adhered to the inner surface of the metal plate, etc. Used.

The planar light guide 5 reflects the light incident from the linear light guide 3 disposed opposite to one end face thereof on the front surface and emits the light from the rear surface. Like the body 3, it is composed of a transparent plate made of a transparent resin such as acrylic resin or polycarbonate, glass, or the like, and has a plurality of V-shaped grooves 7 formed on the surface thereof at predetermined intervals in parallel with each other. Thus, light propagating from one end of the planar light guide 5 is reflected by the slope of the V-shaped groove 7 on the front surface and emitted from the back surface.

In the case of the conventional example using a linear light source, the V-shaped groove 7 is formed in parallel with one end of the planar light guide 5 as shown in FIG. In this embodiment, as shown in FIG. 1 and FIG. 3C, the end on the point light source 2 side in the direction 8 parallel to one end surface of the planar light guide 5 is more line than the end on the opposite side. It is formed to be inclined by an angle β ° so as to approach the light guide 3. This is because the point light source 2 is arranged at one end of the linear light guide 3 so that the main direction 30 of light emitted from the linear light guide 3 to the planar light guide 5 is linear. An angle α ° (0 °) with respect to a direction 9 orthogonal to the longitudinal direction of the light guide 3
(Approximately 10 ° to 10 °), which corresponds to the inclination to the side opposite to the point light source 2, which will be described in detail later. The inclination angle β is preferably set to about 3 ° to 20 °, and optimally around 10 ° (for example, 10 ° ± 4 °).

A distance d of 0.5 mm or more is provided between the point light source 2 and the side end face of the planar light guide 5 on the point light source 2 side. This prevents the light from the point light source 2 from directly entering the planar light guide 5, and the light emitted to the back side of the planar light guide 5 by the direct incident light from the point light source 2. The generation of bright lines is prevented. Also, both end edges 5a, 5b of the end face of the planar light guide 5 facing the linear light guide 3
Among them, at least an edge 5b opposite to the point light source 2 side;
Alternatively, the radius of curvature of both edges 5a, 5b is set to 0.1 mm or less. Thereby, the edges 5b and 5 of the planar light guide 5 are
The generation of a bright line due to reflection at a is prevented.

The planar light guide 5 also preferably has a wedge-shaped cross section in which the thickness at the other end is smaller than the thickness at the one end where the linear light guide 3 is disposed. It is formed so that a uniform light amount can be obtained from one end to the other end. The V-shaped groove 7 is, for example, 250 μm
By setting the pitch to the following, and setting the length of the slope of the groove 7 to 50 μm or less, the groove streak caused by the groove 7 is not conspicuous when the light reflected by the illuminated object is viewed, and does not hinder the visual recognition.

According to the illuminating device 1 having the above configuration, the point light source 2 is used as the light source, so that the power consumption can be reduced, and the thickness of the linear light guide 3 is made the same as that of the planar light guide 5. As a result, the thickness of the lighting device 1 can be reduced.

Further, a point light source 2 is used instead of the conventional linear light source.
By using the linear light guide 3 and the linear light guide 3, the main direction 30 of light emitted from the linear light guide 3 toward the planar light guide 5 is changed as shown by an arrow in FIG. Although it is inclined by α ° to the opposite side to the point light source 2 with respect to the direction 9 perpendicular to the light body 3, the groove 7 on the surface of the planar light guide 5 is located on the side far from the point light source 2. Are formed at an angle of β ° so as to be away from the linear light guide 3, so that the point of the plane light guide 5 is parallel to the main direction 30 of the light emitted from the linear light guide 3. The triangular region 10 on the side of the point light source 2 can be illuminated with uniform illuminance as a whole without becoming darker than the oblique line 10a starting from the edge 5a on the side where the shape light source 2 is disposed.

This will be described with reference to FIG. 3. The reflection efficiency of the inclined surface of the groove 7 of the planar light guide 5 is determined by the groove 7
Is highest for light in the direction 7a orthogonal to
The reflection efficiency decreases depending on the degree of deflection with respect to a. 1 and 3, the linear light guide 3
The main direction 30 of light emitted from is indicated by an arrow,
The main direction 30 indicates the direction of the maximum light intensity. Actually, in the case of the main direction 30 indicated by an arrow in FIG.
As shown in FIG. 2B, the light intensity is distributed in an appropriate angle range on both sides of the main direction 30.

Therefore, when the conventional planar light guide 5 is applied, the direction 7a at which the maximum reflection efficiency is obtained is orthogonal to the linear light guide 3, as shown in FIG. On the other hand, since the main direction 30 of the light emitted from the linear light guide 3 is inclined to the opposite side to the point light source 2, the triangular shape having the vertex at the edge 5 a of the planar light guide 5 is used. Since the distribution of light intensity toward the region 10 is small and the reflection efficiency is small, the region is a dark region.

As a comparative example, as shown in FIG.
When the groove 7 of the planar light guide 5 is inclined such that the end near the point light source 2 is farther from the linear light guide 3, the main direction 30
3a substantially coincides with the direction 7a at which the maximum reflection efficiency is obtained, so that the amount of light is larger than in the case of FIG. 3A. However, the reflection efficiency is further reduced in the direction toward the triangular region 10, so that It becomes a darker area.

On the other hand, in the present embodiment, FIG.
As shown in the figure, the direction 7a at which the maximum reflection efficiency is orthogonal to the groove 7 is inclined toward the point light source 2, and the triangular region 10
, The reflection efficiency of the distributed light in the direction toward the area 10 is high, and the amount of light in that direction is large. Therefore, the illuminance of the triangular area 10 which has been darkened conventionally is improved, and The reflection efficiency of the light guide 30 is relatively low, and the light quantity is reduced, so that the uniformity of the light quantity distribution of the emitted light on the entire surface of the planar light guide 5 can be secured. Thus, when the inclination angle β of the groove 7 is set small, the overall illumination becomes bright, but the shadow of the triangular region 10 becomes strong. When the inclination angle β is set large, the overall illumination becomes dark but the illumination becomes uniform. Therefore, the inclination angle β of the groove 7 may be selected so that an optimal illumination state is obtained according to the use condition.

Next, a reflection type liquid crystal display device with an illumination device according to another embodiment of the present invention will be described with reference to FIGS. The reflection type liquid crystal display device 11 of the present embodiment includes:
The reflection type liquid crystal panel 12 is provided on the back surface side of the lighting device 1 described in the above embodiment. The description of the lighting device 1 itself uses the description of the above embodiment, and the same reference numerals denote the same components. And the description is omitted.

4 and 5, a reflective liquid crystal display device 11 includes a protective sheet 14, a planar light guide 5 of the lighting device 1, and a liquid crystal panel 12 in a space surrounded by a rectangular frame 13. The linear light guide 3 and the point light source 2 of the illuminating device 1 are inserted and arranged in a concave portion 15 formed on one side of the frame body 13 in a stacked state. A side opening 15a opened at the side end surface of the body 13 is covered with a reflector 4, and the linear light guide 3 is engaged and fixed by the reflector 4. Reference numerals 13a and 13b denote engagement protrusions provided on the front and back surfaces of the frame 13 so as to partially protrude into the space inside the frame 13, and are provided on the front surface of the protection sheet 14 and the peripheral portion of the back surface of the liquid crystal panel 12. To hold the laminate.

In the illuminating device 1 of the reflection type liquid crystal display device 11, another identical side surface of the linear light guide 3 opposite to the side facing the planar light guide 5 is provided with another identical light guide. The linear light guide 3 having the above configuration is provided, and the concave portion 15 is configured so that the pair of linear light guides 3 and the point light sources 2 can be housed and arranged. The reflector 4 covers the front surface side of the linear light guide 3 and the side surface opposite to the planar light guide 5 and is formed in a U-shaped cross section so as to engage with the back surface of the frame 13. Further, an engagement protrusion 3a is appropriately provided on the surface side of the linear light guide 3, and an engagement slit 4a is formed in the reflector 4 so that the engagement protrusion 3a is fitted into the reflector. As a result, the reflector 4 engages and fixes the linear light guide 3 housed and held in the recess 15 of the frame 13 and
It is also engaged and fixed.

Also, as shown by a virtual line in FIG.
A side edge on the front side of the reflector 4 is covered on the surface of one end of the planar light guide 5, and the side edge and the liquid crystal panel 12 illuminated with light from the planar light guide 5 are provided. The distance D from the illuminated area 16 is set to 0.5 mm or more.

According to the reflection type liquid crystal display device 11 having the above-described configuration, the reflection type liquid crystal panel 12 is provided on the back surface side of the illumination device 1. Uniform illumination ensures high display quality with a compact configuration. Moreover, the protective sheet 14, the planar light guide 5 and the liquid crystal panel 12 are fitted into the frame 13 in a stacked state, and the linear light guide 3 and the point light source 2 in the recess 15 are inserted and arranged, and the reflector 4 The assembly can be completed simply by covering the assembly, the assembly can be manufactured with high productivity, and the cost can be reduced.

Further, another linear light guide 3 having the same configuration is disposed on the other side of the linear light guide 3 opposite to the one side facing the planar light guide 5. Therefore, the light emitted from the separately provided linear light guide 3 enters the linear light guide 3 disposed in contact with the planar light guide 5 as scattered light, and Therefore, the amount of light emitted from the planar light guide 5 can be increased as a whole, and the illuminance of the illumination device 1 can be improved.

The reflector 4 made of a metal plate is engaged with and fixed to the linear light guide 3 or the planar light guide 5.
Since the side end covers the side end of the planar light guide 5, the edge of the reflector 4 is fixed to the planar light guide 5 with an adhesive as in the case where the edge of the reflector 4 is fixed to the planar light guide 5 with an adhesive or the like. There is no possibility that light is irregularly reflected and adversely affects the illuminated area 16. Also,
Since the distance D between the side edge of the reflector 4 and the illuminated area 16 of the liquid crystal panel 12 is set to 0.5 mm or more, light reflected on the end side edge of the reflector 4 adversely affects the illuminated area 16. And the occurrence of uneven brightness in the illuminated area 16 can be prevented.

In the above-described embodiment, another linear light guide 3 having the same configuration is provided on the other side of the linear light guide 3 opposite to the side facing the planar light guide 5. Is applied, but in this type of lighting device 1, FIG.
As shown in (a), the illumination light from the planar light guide 5 may have streak-like bright and dark stripes 16 extending from the linear light guide 3 in the perspective direction. This is because, as shown in FIG. 6B, moire fringes 17 are generated due to interference of light from the grooves 6, 6 provided on the other side surfaces of the pair of linear light guides 3, 3. It is considered that the light is reflected by the illumination light from the planar light guide 5.

As shown in FIG. 6 (c), as a means for eliminating the streak-like light and dark stripes 16, the planar light guides in both the linear light guides 3 or at least one of the linear light guides 3 are used. Body 5
A plurality of parallel grooves 18 inclined at an inclination angle θ with respect to the longitudinal direction of the linear light guide 3 are formed on one side surface facing the It is conceivable that the light emitted toward No. 5 is diffused to lower the contrast of the shadow caused by the moire fringes.

At this time, if the inclination angle θ is small, the reduction in luminance is small but the effect of eliminating moiré fringes is small, and if the inclination angle θ is large, moiré fringes can be eliminated but the decrease in luminance is large, so an appropriate angle is selected. There is a need.

[0052]

[Table 1] Table 1 shows changes in luminance and moiré elimination effect when the inclination angle θ (°) is changed. In the table, the double circle indicates the best, the circle indicates good, the triangle indicates acceptable, and the X indicates poor. As is evident from Table 1, when θ is around 15 °, the decrease in luminance is small and the moiré elimination effect can be sufficiently obtained.

As shown in FIG. 6D, instead of the groove 18, one side face of both linear light guides 3 or at least one of the linear light guides 3 facing the planar light guide 5. Is formed on the satin finish 19 by sandpaper processing or the like, whereby light is diffused to lower the contrast of shadows due to moiré fringes. In that case, Nashiji 19
If the roughness of the surface is large, the luminance is greatly reduced.

[0054]

[Table 2] Table 2 shows the luminance and the moiré elimination effect when the size of the particles is changed in sandpaper processing. From Table 2, it can be seen that even when particles of any size of # 600 to # 2000 are used, the moiré elimination effect can be sufficiently obtained and the luminance is # 2000.
Therefore, it is preferable to perform sandpaper processing using particles of # 2000 or less.

When a pair of linear light guides 3 is used in this manner, by forming an appropriate groove 18 or satin surface 19 on one side surface of one or both linear light guides 3, a reduction in luminance occurs. Without this, it is possible to prevent the generation of streaky light and dark fringes 16 due to moiré fringes.

[0056]

According to the illumination device of the present invention, the point light source, the linear light guide, and the planar light guide are provided as described above, and the object disposed on the back side of the planar light guide is provided. In a lighting device that illuminates an illuminating object and transmits the reflected light to the surface side,
A plurality of light guides are arranged on the surface of the planar light guide in parallel to each other so that light incident from one end surface of the planar light guide is emitted from the back surface of the planar light guide from the linear light guide. Since the groove is formed so that the end on the side of the point light source is closer to the linear light guide than the end on the opposite side, light emitted from the linear light guide toward the planar light guide is formed. Even if the main direction is inclined to the opposite side to the point light source with respect to the direction perpendicular to the linear light guide, the direction with the highest reflection efficiency in the direction perpendicular to the groove is the point light source side. Because the main direction of the light emitted from the linear light guide is tilted in the past, the amount of light is small, and the corner portion on the point light source arrangement side of the planar light guide, which has become a dark area due to the small light amount, The amount of light in the triangular region at the apex increases, and the uniformity of the amount of light emitted from the entire surface of the planar light guide can be ensured. In addition, since the point light source is used as the light source, power consumption can be reduced, and the thickness of the linear light guide can be easily made the same as that of the planar light guide, so that the thickness of the lighting device can be reduced. it can.

When the point light source is constituted by an LED,
The required amount of light can be obtained with small components, the thickness of the lighting device can be reduced, and the cost can be reduced because it is inexpensive.

When the point light source is bonded to one end of the linear light guide, light transmission efficiency is high, the arrangement is simple, and the cost can be reduced.

When the distance d between the point light source and the side end surface of the planar light guide is 0.5 mm or more, light from the point light source is prevented from directly entering the planar light guide. Thus, it is possible to prevent bright lines from being generated in the light emitted to the rear surface side of the planar light guide due to the directly incident light.

Further, when the linear light guide is formed of a rod-shaped transparent body having a substantially rectangular cross section, and the reflecting surface is constituted by arranging a plurality of V-shaped grooves parallel to each other in a direction substantially perpendicular to the longitudinal direction, Light transmission efficiency is high, and a single component can be made compact, lightweight and inexpensive.

Further, when the linear light guide is made of a wedge-shaped rod-shaped transparent body having a smaller sectional area from one end to the other end,
The closer to the point light source, the more the light quantity can be prevented, and the more uniform the light quantity distribution of the emitted light in the longitudinal direction of the linear light guide.

Further, if the periphery of the linear light guide other than the surface facing the planar light guide is covered with a reflector, the utilization of light from the point light source can be improved, and the illumination efficiency can be improved.

The distance D between the side edge of the reflector that covers the surface of the planar light guide and the area to be illuminated by the light from the planar light guide is 0.5 mm or more. Then
The light reflected on the end side edge of the reflector does not adversely affect the illuminated area, and it is possible to prevent luminance unevenness from occurring in the illuminated area.

When the reflector is formed of a metal plate and is engaged and fixed to the linear light guide or the planar light guide, the edge of the reflector is fixed to the planar light guide with an adhesive or the like. In this way, it is possible to prevent light from being irregularly reflected by the adhesive and adversely affecting the illuminated area.

Further, when another linear light guide having the same configuration is provided on the other side of the linear light guide opposite to the one side facing the planar light guide, another line is provided. The light emitted from the planar light guide enters the linear light guide disposed in contact with the planar light guide as scattered light from the opposite side to the planar light guide, and the planar light guide Therefore, the luminous intensity can be improved by increasing the amount of light emitted from the planar light guide as a whole.

At this time, a plurality of grooves inclined at an appropriate angle with respect to the longitudinal direction are formed on one side surface of at least one of the two linear light guides facing the planar light guide. When formed on the matte surface, the light emitted toward the planar light guide is diffused by the groove or matte surface, and is generated by the groove forming the reflection surface of both linear light guides. The contrast of the moire fringes is reduced, and the shadows of the moire fringes can be reduced.

If the radius of curvature of at least the end edge of the planar light guide opposite to the point light source among the end edges of the end face facing the linear light guide is 0.1 mm or less, It is possible to prevent the generation of a bright line due to the reflection at the edge of the light guide.

Further, the reflection type liquid crystal display device of the present invention has a reflection type liquid crystal panel disposed on the back side of the above-mentioned illumination device, and the entire surface of the reflection type liquid crystal panel is made uniform by the illumination device as described above. , High display quality can be ensured with a compact configuration.

Further, the protective sheet, the planar light guide and the reflective liquid crystal panel are fitted and arranged in a laminated state in a rectangular frame, and the linear light guide is inserted into a recess formed on one side of the frame. And a point-like light source are inserted and arranged, and the opening of the recess is covered and fixed with a reflector that covers the linear light guide, so that a reflective liquid crystal display device with a lighting device can be assembled very easily, and productivity is improved. It is possible to improve the cost and reduce the cost.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a schematic configuration of a lighting device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a display of a main direction of emitted light and its light distribution.

FIG. 3 is an explanatory diagram of a light amount distribution in a conventional example, a comparative example, and the illumination device of the present invention.

4A and 4B show a reflection type liquid crystal display device according to another embodiment of the present invention, wherein FIG. 4A is a partial cross-sectional plan view, and FIG.
FIG. 3 is a cross-sectional view taken along the arrow A, and FIG.

FIG. 5 is an exploded perspective view of the reflective liquid crystal display device of the embodiment.

FIGS. 6A and 6B are explanatory diagrams of an improved configuration of the lighting device according to the embodiment, wherein FIG. 6A is a plan view and FIG.
FIG. 3C is a view similar to FIG. 2B showing an example of the improved configuration, and FIG. 3D is a view similar to FIG. 2B showing another example of the improved example.

FIG. 7 is a schematic vertical sectional view showing a schematic configuration of a conventional illumination device.

[Explanation of symbols]

 Reference Signs List 1 lighting device 2 point light source 3 linear light guide 4 reflector 5 planar light guide 5a, 5b edge 6 groove 7 groove 11 reflective liquid crystal display device 12 liquid crystal panel 13 frame body 14 protective sheet 15 concave part 16 illumination area

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09F 9/00 336 F21Y 101: 02 // F21Y 101: 02 G02F 1/1335 530 (72) Inventor Taishi Uehara 2-9-95 Nagaragahigashi, Kita-ku, Osaka West Electric Co., Ltd. (72) Inventor Kenji Takamoto 1006 Ojidoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Koji Hiramoto Osaka 1006 Kadoma Kadoma, Matsushita Electric Industrial Co., Ltd. FB08 LA11 LA12 LA16 LA18 LA30 5G435 AA03 AA17 AA18 BB12 BB16 EE02 EE22 FF03 FF08 FF11 FF12 GG23 LL07

Claims (15)

[Claims] A point light source; and a linear light guide that reflects light from the point light source incident from one end on a reflection surface provided on another side opposite to one side and emits the light from one side. A planar light guide made of a transparent body that reflects light from the linear light guide incident from one end surface on the slopes of the plurality of grooves disposed parallel to each other on the front surface and radiates from the back surface. An illumination device configured to illuminate an object to be illuminated disposed on a back surface side of a planar light guide and transmit reflected light thereof to a front surface side, wherein a groove of the planar light guide is formed by a point light source. A lighting device characterized in that an end on one side is inclined so as to be closer to a linear light guide than an end on the opposite side. 2. The lighting device according to claim 1, wherein the point light source comprises an LED. 3. The lighting device according to claim 1, wherein the point light source is adhered to one end of the linear light guide. 4. The lighting device according to claim 1, wherein a distance d between the point light source and the side end surface of the planar light guide is 0.5 mm or more. 5. The linear light guide is formed of a rod-shaped transparent body having a substantially rectangular cross section, and the reflecting surface is formed by arranging a plurality of V-shaped grooves parallel to each other in a direction substantially orthogonal to the longitudinal direction. The lighting device according to claim 1, wherein: 6. The illuminating device according to claim 5, wherein the linear light guide is formed of a wedge-shaped rod-shaped transparent body having a smaller sectional area from one end to the other end. 7. The periphery of the linear light guide other than the surface facing the planar light guide is covered with a reflector.
Or the lighting device according to 6. 8. A distance D between a side edge of the reflector that covers the surface of the planar light guide and an illuminated area illuminated with light from the planar light guide is 0.5 mm or more. The lighting device according to claim 7, wherein: 9. The lighting device according to claim 7, wherein the reflector is formed of a metal plate, and is engaged with and fixed to the linear light guide or the planar light guide. 10. A linear light guide, wherein another linear light guide having the same configuration is provided on the other side of the linear light guide opposite to the one side facing the planar light guide. The lighting device according to claim 5. 11. A plurality of grooves which are inclined at an appropriate angle with respect to the longitudinal direction on one side surface of at least one of the two linear light guides which faces the planar light guide. The lighting device according to claim 10, wherein: 12. The illuminating device according to claim 10, wherein at least one of the two linear light guides, one side of the linear light guide facing the planar light guide, is formed in a satin finish. 13. The curvature radius of at least the end edge of the planar light guide opposite to the point light source side, of the two end edges of the end surface facing the linear light guide, is set to 0.1 mm or less. The lighting device according to claim 1, wherein: 14. A reflection type liquid crystal display device, wherein a reflection type liquid crystal panel is disposed on the back side of the lighting device according to claim 1. 15. A protective sheet, a planar light guide, and a reflective liquid crystal panel are fitted and arranged in a rectangular frame body in a stacked state, and a linear light guide and a point light source are provided in a recess formed in the frame body. 15. The reflection type liquid crystal display device according to claim 14, wherein the reflection type liquid crystal display device is inserted and arranged, and the opening of the concave portion is engaged and fixed by covering with a reflector covering the linear light guide.