JPH117014A - Illuminator and liquid crystal display device and electric equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance visibility in both of an illumination lighting time and a non-lighting time by forming a light transmission plate so that intensities of outgoing lights in a direction vertical with respect to the surface of the light transmission plate emitting lights from a light source become smaller than intensities of outgoing lights in a direction oblique with respect to the surface of the light transmission plate. SOLUTION: Protrusions 5 are provided on the surface of a light transmission plate 1 at whose end face 7a point light source 2 is arranged which is in a side opposite to the counter surface of a body to be illuminated 3. Each surface of the protrusions 5 is made to be a face roughly forming the angle of not larger than 30 degrees with respect to a surface parallel with the light transmission plate 1 consisting of transparent material whose refractive index is not smaller than 1.4. Then, when luminous fluxes made incident from the end face 7 form angles of not larger than 45 degrees with respect to the surface parallel with the plate 1, after they repeat total reflections in the plate 1 like light beams 6a, 6b, when the light beams reflected on the respective protrusions 5 become to form angles roughly exceeding 45 degrees with respect to the surface parallel with the plate 1, the plate 1 emits outgoing lights 8 to a direction having an angle θ with respect to a direction vertical with respect to the surface of the plate 1. At this time, intensities of outgoing lights to a direction vertical with respect to the surface of the light transmission plate 1 become smaller than intensities of outgoing lights to a direction oblique with respect to the surface of the light transmission plate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device, a liquid crystal display device having a lighting function, and an electronic apparatus equipped with the liquid crystal display device having a lighting function.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal display device used for illumination with external light has a reflection function, and a reflection plate 102 is arranged on the back surface of a liquid crystal display panel 101 as shown in FIG. In addition, as shown in FIG. 23, a liquid crystal display device using a lighting device has a surface lighting device 103 disposed as a backlight on the back surface of a liquid crystal display panel 101, which is an object to be illuminated, and constantly turns on illumination from the back surface. . Further, when the outside is bright, external light is used. When the outside is dark, the backlight is turned on. The liquid crystal display device used is, as shown in FIG. The lighting device 103 was arranged. (For example, see JP-A-57-
49271, JP-A-57-054926,
JP-A-58-95780, etc.).

[0003]

However, the conventional liquid crystal display device having only an illumination function has a problem that it consumes a large amount of power because the light source is always turned on, and cannot be used for a long time when it is mounted on a cellular phone, for example. Had. Further, a conventional liquid crystal display device having only a reflection function has a problem that it is not necessary to turn on a light source, so that it can be used for a long time when mounted on a mobile phone, for example, but cannot be used in a dark place outside. Furthermore, a conventional liquid crystal display device that can be used in both bright and dark environments by using a back-side illumination device and a semi-transmissive reflection plate has a problem that the display when using external light is dark. Was.

Therefore, the present invention solves the above-mentioned conventional problems, and provides an illuminating device which does not reduce the reflection function of the liquid crystal display device, a liquid crystal display device having an illuminating function, and a liquid crystal display device having an illuminating function. The present invention relates to an electronic device equipped with.

[0005]

According to a first aspect of the present invention, there is provided an illuminating device comprising a light source and a light guide plate, wherein the light source emits light from the light source in a direction perpendicular to a surface of the light guide plate. The light guide plate is formed such that the intensity of the emitted light is smaller than the intensity of the emitted light obliquely to the surface of the light guide plate. With reference to a direction perpendicular to the surface of the light guide plate that emits light from the light source, the intensity of emitted light emitted in the perpendicular direction is approximately 45 degrees with respect to the perpendicular direction. It is 1/5 or less of the intensity of the emitted light. In addition, when a direction perpendicular to a surface of the light guide plate that emits light from the light source is used as a reference, output light intensities at angles having absolute values equal to each other with respect to the perpendicular direction are different. . Furthermore, the intensity of emitted light emitted toward the side on which the light source is arranged is small with respect to a direction perpendicular to the surface of the light guide plate that emits light from the light source.

[0006] With this configuration, the light spreads in the direction opposite to the light source, and bright light can be emitted from the entire light guide plate.

[0007] The light source is disposed on opposite end faces of the light guide plate. The light source is preferably a point light source or a bar light source.

Further, the light diffusing portion is formed on the light emitting surface of the light guide plate, so that the light can be emitted from the light diffusing portion.

On the other hand, since the light diffusing portion is formed on the surface of the light guide plate opposite to the surface from which the light is emitted, light can be reflected by the conical slope which is the light diffusing portion. , Light can be reflected to the exit surface.

[0010] A reflecting member is provided on an end face of the light guide plate. With this configuration, light can be used efficiently, and the intensity of light emitted from the light guide plate increases.

Further, since the lighting device is arranged on the liquid crystal panel, it can be used as a liquid crystal display device.
Further, the liquid crystal display device can be mounted on an electronic device.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIGS. 1, 2 and 3 show a first embodiment of a lighting device according to the present invention. In FIG. 1, a light guide plate 1 having a plurality of point light sources 2 disposed on an end face is disposed on a front surface of an illuminated body 3. The objects to be illuminated are various display objects such as a liquid crystal panel, and paintings. In the case of a liquid crystal panel, a simple matrix type liquid crystal panel, TFT or M
A liquid crystal panel using an active element such as an IM can be used.

As shown in FIG. 1, the light guide plate 1 is provided with a projection 5 having a convex shape as a light diffusing portion on a surface different from the surface facing the illuminated body 3 made of a transparent flat plate. Each of the surfaces is formed of a surface that is approximately 30 degrees or less with respect to a surface parallel to the light guide plate 1. The light guide plate 1 is formed of a transparent material having a refractive index of about 1.4 or more. For example, when the refractive index is 1.4, the critical angle becomes 45 degrees, and the light guide plate 1 is moved from the end face 7 of the light guide plate.
Is approximately 45 with respect to a plane parallel to the light guide plate 1.
When it is below the degree, as shown in the light rays 6a and 6b,
Total reflection is repeated in the light guide plate 1.

After that, when the light reaches the convex protrusion 5, the light reflected by each surface of the convex protrusion 5 becomes at an angle exceeding approximately 45 degrees with respect to a plane parallel to the light guide plate 1, and the light from the light guide plate 1 is turned off. Emit. In this way, the emitted light 8 is emitted from the light guide plate 1 in the direction of the angle θ with respect to the direction perpendicular to the surface of the light guide plate 1. Thereby, the illuminated body 3 can be illuminated.

Here, a bottom surface having a diameter of 50 mm as shown in FIG. 4 is formed on a 1 mm thick flat plate made of an acrylic resin having a refractive index of 1.49.
The light guide plate 1 was formed by forming conical convex protrusions 5a having a height of 11.6 μm and an apex angle of about 130 degrees adjacent to each other at intervals of 150 μm as shown in FIGS. At this time, the ratio of the area of the convex protrusion to the area of the illumination part of the light guide plate is about 10%. Further, a light emitting diode (LED) was used as the point light source 2.

FIG. 5 shows the intensity I of the outgoing light 8 in the direction θ at an angle to the direction perpendicular to the surface of the light guide plate 1 at this time. FIG.
As shown in the figure, the intensity of the emitted light in the direction perpendicular to the surface of the light guide plate 1 is smaller than the intensity of the emitted light in the direction of the angle θ with respect to the direction perpendicular to the surface of the light guide plate 1 (θ = 0 °). The intensity of the emitted light in the direction perpendicular to the surface of the light plate 1 was 1/5 or less of the intensity of the emitted light in the direction of θ = 45 °. In addition, as shown in FIG. 1, θ is the angle between the direction perpendicular to the light emitting surface of the light guide plate and the light emitting direction, and the direction emitting in the direction opposite to the light source is positive. I do.

When the illuminating device of the present invention is used for an illuminated body 3 whose illumination light is reflected on the surface because the surface is flat, most of the light applied to the illuminated body 3 is oblique. Since the illumination light from the vertical direction (the front direction of the illuminated body 3) is small, when the illuminated body 3 is viewed from the front, there is almost no reflection of the illuminating light due to the reflection on the surface of the illuminated body. Display was obtained.

As the transparent material forming the light guide plate 1, other than acrylic resin, a transparent resin such as polycarbonate resin and amorphous polyolefin resin, an inorganic transparent material such as glass, or a composite thereof may be used. Examples of the method of forming the convex protrusions 5 include injection molding, thermosetting resin, photocurable resin, etching, and joining a film or resin layer on a transparent resin or a glass flat plate.

With the above arrangement, the present illuminating device is arranged on the front surface of the illuminated body 3 and turns off the illumination when the external light is sufficiently bright to observe the illuminated body 3. It is possible to realize part-time illumination in which the illumination can be turned on and the object to be illuminated can be observed.

However, the intersection line between the surface of the light guide plate 1 and the convex protrusion 5a shown in FIG. 4 (specifically, the intersection between the plane of the light guide plate and the slope of the protrusion) and the apex of the cone are minute. Due to the curved surface, some reflected light leaks to the observer side and is observed as a bright spot for the observer.

Accordingly, the size of the projection 5 having a convex shape is desirably 300 μm or less, since it is a size that does not matter to the naked eye. Further, the thickness is required to be 5 μm or more so that the influence of diffraction of visible light does not occur. Further, the size is desirably about 10 μm or more and 100 μm or less from the viewpoint of manufacturing convenience.

The efficiency of illumination increases as the area ratio of the projections to the area of the illuminating section of the light guide plate increases, but the parallel light transmittance in the direction perpendicular to the light guide plate decreases. Becomes worse and is not practical at 50% or more. Also, if it is too small, the lighting efficiency will decrease, so 5%
The above is necessary. Therefore, it is desirable that the area ratio of the convex protrusion to the area of the illumination part of the light guide plate is 5% to 50%. More preferably, by setting it in the range of 10% to 35%, the illumination efficiency is the best, and there is no influence by diffraction of visible light.

The convex protrusion may be a hemispherical convex shape as shown in FIG. 15 in addition to the conical shape as shown in FIG.

(Embodiment 2) FIGS. 6, 7 and 8 are views showing a second embodiment of the illumination device of the present invention. In the same manner as in FIG. 3 or the first embodiment, two light emitting diodes (LEDs) are provided on the end surface of a light guide plate 1 which is a flat plate made of an acrylic resin and has a refractive index of 1.49 and a thickness of 1 mm disposed on the front surface of the illuminated body 3. It is arranged as a point light source 2 and a reflection member 4 is arranged on the opposite end face. The light guide plate 1 has a bottom diameter of 50 as shown in FIG.
Conical protrusions 5 having a height of 11.6 μm and a vertex angle of about 130 degrees are formed adjacent to each other at intervals of 150 μm as shown in FIGS.

At this time, the ratio of the area of the convex projection to the area of the illumination section of the light guide plate is about 10%.

The reflection member 4 reflects light emitted from the end face of the light guide plate 1 on the side opposite to the light source and makes the light enter the light guide plate again, so that the illumination efficiency can be increased.

As the reflection member, a material obtained by depositing a thin film of aluminum or the like or a material obtained by attaching a thin plate of aluminum or the like via a double-sided tape or an adhesive can be used. When an air layer is provided between the reflecting member 4 and the end surface of the light guide plate 1, a scattering plate may be used as the reflecting member.

At this time, the direction perpendicular to the surface of the light guide plate 1 (θ
= 0 °), the intensity I of the emitted light 8 in the direction of the angle θ and −
FIG. 9 shows the intensity I of the emitted light 9 in the θ direction. As shown in FIG. 9, the intensity of the emitted light in a direction perpendicular to the surface of the light guide plate 1 is smaller than the intensity of the emitted light in both the directions θ and −θ with respect to the direction perpendicular to the surface of the light guide plate 1. The intensity of the emitted light in the direction perpendicular to the surface of the light guide plate 1 is 1/5 or less of the intensity of the emitted light in the direction of θ = 45 °, and is １ ／ of the intensity of the emitted light in the direction of θ = −45 °. It is as follows.

When the illuminating device of the present invention is used for an illuminated object 3 whose surface is flat and illumination light is reflected on the surface, most of the light applied to the illuminated object 3 is oblique. Since the illumination light from the vertical direction (the front direction of the illuminated object 3) is small, when the illuminated object 3 is viewed from the front, there is almost no reflection of the illuminating light due to reflection on the surface of the illuminated object. The display was obtained.

At an angle having the same absolute value, the intensity of the emitted light emitted to the opposite side (ie, + θ) is higher than the intensity of the emitted light emitted to the side where the light source is arranged (−θ).
A light guide plate having characteristics was used. By using such a light guide plate, light can be uniformly emitted to, for example, a liquid crystal panel even from a light guide plate far from the light source.

(Embodiment 3) FIG. 10 is a view showing a third embodiment of the lighting apparatus of the present invention. As shown in FIG. 10, a reflection member 4 is arranged on a part of an end face of a light guide plate 1 in which two LEDs are arranged as a point light source 2 and on an end face on the opposite side.

The reflecting member 4 reflects the light emitted from the end face of the light guide plate 1 and makes the light enter the light guide plate again, so that the illumination efficiency can be increased.

Further, as shown in FIG. 11, when the reflecting member 4 is arranged on the end face of the light guide plate 1 other than the portion where the two LEDs are arranged as the point light source 2, the illumination efficiency can be further increased.

(Embodiment 4) FIGS. 12 and 13 are views showing a fourth embodiment of the illumination device of the present invention. As shown in the figure, LEDs are arranged as point light sources 2 on both sides of the light guide plate 1,
The reflection member 4 is arranged on an end surface other than the portion where the LED is arranged.

By disposing the light sources on both sides of the light guide plate 1, the asymmetry of the illumination light due to the light source being on one side is eliminated, and uniform illumination can be obtained.

(Embodiment 5) FIG. 14 is a view showing the configuration of a fifth embodiment of the lighting apparatus of the present invention. As shown in FIG. 14, a cold-cathode tube is arranged as a rod-shaped light source 2 on the end surface of the light guide plate 1, and a reflection member 9 is arranged so as to cover the end surface of the light guide plate and the cold-cathode tube. Further, bright illumination light can be obtained by arranging the reflection member 4 on an end surface other than the portion where the cold cathode tube is arranged.

(Embodiment 6) In the present invention, the light diffusing portion of the light guide plate on the surface different from the surface facing the illuminated body 3 is not a convex protrusion but a conical concave shape as shown in FIG. Even when the light guide plate has a hemispherical concave shape such as 17, the intensity of the emitted light in the direction perpendicular to the surface of the light guide plate is made smaller than the intensity of the emitted light in the direction oblique to the direction perpendicular to the surface of the light guide plate 1. Can be.

(Embodiment 7) In the present invention, as a light diffusing portion of a light guide plate, a cylindrical convex shape as shown in FIG. 18 or a convex shape as shown in FIG. By forming the cylindrical concave shape, the intensity of the emitted light in the direction perpendicular to the surface of the light guide plate can be made smaller than the intensity of the emitted light in the direction oblique to the direction perpendicular to the surface of the light guide plate. In such a configuration, light can be uniformly emitted to a liquid crystal panel or the like by emitting light from the light diffusion portion having a projection shape. Conversely, it is also possible to emit light from a flat portion instead of from a convex protrusion.

(Embodiment 8) FIG. 20 shows a liquid crystal display device in which an object to be illuminated is a liquid crystal display device and the lighting device used in Example 1 is disposed on the front surface thereof. The liquid crystal display device includes a liquid crystal panel including upper and lower substrates 12 and 13 sandwiching a liquid crystal layer 11,
It comprises a pair of polarizing plates 14 and 15 disposed outside thereof, at least one phase difference plate 16 sandwiched between one polarizing plate and the liquid crystal layer, and a reflecting plate 17 disposed outside the polarizing plate. This is a reflection type liquid crystal display device using external light. It is possible to provide a plurality of retardation plates, and they may be arranged one on another or at least one layer on both sides of the liquid crystal panel. Further, the reflection layer can be disposed on the surface of the substrate on the liquid crystal layer side. In this case, the configuration can be made by disposing a polarizing plate only on the side where light is incident. Since there is only one polarizing plate, the liquid crystal panel has a characteristic that the display becomes bright.

Further, since the light guide plate is a transparent plate, when there is sufficient external light, even if the light source 2 is turned off, the external light can be used in the same manner as in the related art, and the display quality is hardly affected.
When there is not enough external light, the light source 2 is turned on to use the illumination light from the light guide plate. At this time, the brightness of the display of the liquid crystal display device depends on the brightness of the light source, but the same contrast as when external light is used can be obtained. Moreover, despite the illumination from the front of the liquid crystal display device, an extremely good display was obtained in which the display quality did not deteriorate due to the light reflected on the surface of the liquid crystal display device when viewed from the front.

By using the illuminating device of the present invention, the display is dark and the visibility is poor even when there is sufficient external light. A liquid crystal display device which has solved the drawbacks of a conventional liquid crystal display device using a transflective plate and a backlight has been obtained. It goes without saying that the liquid crystal display device is not limited to the structure used in this embodiment.

(Embodiment 9) FIG. 21 shows an example in which the liquid crystal display device of the present invention is used in a mobile phone. As the display unit 20 of the mobile phone 40, the liquid crystal display devices described in the above-described Examples 1 to 8 were used.

When external light was used, a brighter display than before was obtained. In addition, even when the lighting device is turned on, the same contrast as when using external light can be obtained, so that the mobile phone can be used without trouble even in a dark environment where external light is not sufficient.

Even when the liquid crystal display device of the present invention is used not only for a mobile phone but also for an electronic device such as a portable electronic device such as an electronic organizer or a measuring device, a bright display can be obtained when external light is used. An electronic device that can obtain the same contrast as when using external light even when is turned on. Furthermore, the electronic device can be used for a wristwatch, and a bright and low power consumption electronic device can be obtained with a reflective liquid crystal display device.

[0046]

According to the present invention, as described above,
It is possible to provide a thin surface illumination suitable for a notice board, a display body, and the like using external light. Further, it is possible to provide a low-power-consumption and high-contrast liquid crystal display device in which the same contrast as when external light is used can be obtained even when the lighting device is turned on. Furthermore, in applications that require power saving, such as portable electronic devices, the display can be used with the lighting turned off in bright places, and can be used in dark environments without reducing the contrast even when the lighting is on, with low power consumption and high contrast display. An electronic device having a unit can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a plan view showing an embodiment of the present invention.

FIG. 3 is a perspective view showing an embodiment of the present invention.

FIG. 4 is an explanatory view of a protrusion having a convex shape according to the embodiment of the present invention.

FIG. 5 is an explanatory diagram showing the intensity of light emitted from a light guide plate in an example of the present invention.

FIG. 6 is a sectional view showing an embodiment of the present invention.

FIG. 7 is a plan view showing an embodiment of the present invention.

FIG. 8 is a perspective view showing an embodiment of the present invention.

FIG. 9 is an explanatory diagram showing the intensity of light emitted from the light guide plate in the example of the present invention.

FIG. 10 is a plan view showing an embodiment of the present invention.

FIG. 11 is a plan view showing an embodiment of the present invention.

FIG. 12 is a sectional view showing an embodiment of the present invention.

FIG. 13 is a plan view showing an embodiment of the present invention.

FIG. 14 is a sectional view showing an embodiment of the present invention.

FIG. 15 is an explanatory diagram of a projection having a convex shape according to the embodiment of the present invention.

FIG. 16 is an explanatory view of a concave shape in the embodiment of the present invention.

FIG. 17 is an explanatory view of a concave shape in the embodiment of the present invention.

FIG. 18 is an explanatory diagram of a projection having a convex shape according to the embodiment of the present invention.

FIG. 19 is an explanatory view of a concave shape in the embodiment of the present invention.

FIG. 20 is a sectional view showing an embodiment of the present invention.

FIG. 21 is a diagram showing an example of the present invention.

FIG. 22 is a sectional view showing a conventional technique.

FIG. 23 is a sectional view showing a conventional technique.

FIG. 24 is a sectional view showing a conventional technique.

[Explanation of symbols]

 1. Light guide plate 2. Point light source 3. Illuminated object 4. Reflective member 5. 8. convex protrusions Reflective member

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G02B 6/00 331 G02B 6/00 331

Claims (12)

[Claims] 1. An illuminating device comprising a light source and a light guide plate, wherein the intensity of light emitted in a direction perpendicular to the surface of the light guide plate that emits light from the light source is lower than that of the light guide plate. On the other hand, so as to be smaller than the output light intensity in the oblique direction,
A lighting device, wherein the light guide plate is formed. 2. The intensity of emitted light emitted in the perpendicular direction with respect to the direction perpendicular to the surface of the light guide plate that emits light from the light source is approximately 2. The lighting device according to claim 1, wherein the intensity is equal to or less than 1/5 of the intensity of light emitted in a direction of 45 degrees. 3. When the direction perpendicular to the surface of the light guide plate that emits light from the light source is used as a reference, the intensity of emitted light at an angle having an absolute value equal to the vertical direction is different. The lighting device according to claim 1, wherein: 4. The light intensity emitted from the light guide plate, on which light emitted from the light source is emitted, is small toward a side on which the light source is arranged, with respect to a direction perpendicular to a surface of the light guide plate that emits light from the light source. Item 4. The lighting device according to Item 3. 5. The lighting device according to claim 1, wherein the light source is disposed on opposite end faces of the light guide plate. 6. The lighting device according to claim 1, wherein the light source is a point light source. 7. The lighting device according to claim 1, wherein the light source is a rod-shaped light source. 8. The lighting device according to claim 1, wherein the light diffusing portion is formed on a surface of the light guide plate from which light is emitted. 9. The lighting device according to claim 1, wherein the light diffusing portion is formed on a surface of the light guide plate opposite to a surface from which light is emitted. 10. The lighting device according to claim 1, wherein a reflection member is provided on an end surface of the light guide plate. 11. A liquid crystal display device, wherein the lighting device according to claim 1 is arranged on a liquid crystal panel. 12. An electronic apparatus comprising the liquid crystal display device according to claim 11.