KR20030013323A - Illumination panel and display device mounted with the same - Google Patents

Abstract

PURPOSE: To improve utilization efficiency of light, and increase luminance, of the illumination panel as a back light that is arranged on the back face side of the liquid crystal panel. CONSTITUTION: The surface of the light guide plate 32 of the illumination panel is made a light-exit face 33 and the back face is made an optical face 35. The optical face 35 has a structure in which a set of optical elements that are provided with a curvature face 35a, a flat face 35b, and a slanted face 35c continuously in order from the light-entrance face side (left side in the figure 3) toward the opposite side is provided continuously in many sets. The flat face 35b is made in parallel with the light-exit face 35. The height H of the slanted face 35c to the flat face 35b within the same set becomes gradually taller from the light-entrance face 34 side toward the opposite side. And the lights that are shown by the arrow A, B and C as a representative are irradiated finally in the direction nearly perpendicular from the light-exit face 33 after reflected by either of the slanted faces 35c.

Description

ILLUMINATION PANEL AND DISPLAY DEVICE MOUNTED WITH THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting panel and a display device using the same, and more particularly, to a lighting panel having a light collecting function for condensing and emitting incident light introduced from a light source or the outside.

For example, in a liquid crystal display device, since the liquid crystal display panel itself does not have self-luminous ability, an illumination panel is disposed as a backlight on the back side of the liquid crystal display panel. 24 shows a side view of a part of an example of the conventional liquid crystal display. This liquid crystal display device is provided with the liquid crystal display panel 1 and the illumination panel 11 arrange | positioned at the back surface on the opposite side to the surface of the side observed.

In the liquid crystal display panel 1, the glass substrate 2 on the front side and the glass substrate 3 on the back side are bonded together through a seal member (not shown) in a substantially rectangular frame, and both glass substrates 2 and 3 and the sealing member are bonded together. The liquid crystal (not shown) is enclosed in the space surrounded by the surface, and the surface side polarizing plate 4 is attached to the surface of the surface side glass substrate 2, and the back side polarizing plate 5 is attached to the rear surface of the back side glass substrate 3. ) Is attached.

The lighting panel 11 is provided with the light guide plate 12 provided in the back surface side of the liquid crystal display panel 1. The light guide plate 12 has a planar square shape and is an exit surface 13 through which light exits a surface facing the liquid crystal display panel 1, and an incident surface on which light enters a predetermined one surface (left end surface in FIG. 24). (14), the light guide plate 12 of the light guide plate 12 is directed from the incident surface 14 side toward the end side edge 12a side of the side opposite to the incident surface 14 with respect to the exit surface 13. It is structured as the inclined surface 15 inclined so that thickness may become thin gradually.

The reflecting plate 16 is attached to the inclined surface 15 of the light guide plate 12. A cold cathode tube (light source) 17 is provided at a position facing the incident surface 14 of the light guide plate 12. One end of the reflective sheet 18 covering the cold cathode tube 17 is attached to the surface on the incident surface 14 side of the light guide plate 12, and the other end is attached to the back surface on the incident surface 14 side of the reflecting plate 16. It is.

The light emitted from the cold cathode tube 17 and the light reflected by the reflective sheet 18 are incident on the incident surface 14 of the light guide plate 12. This incident light travels (guided) in the light guide plate 12 from the incident surface 14 side to the end edge 12a side, is reflected by the reflecting plate 16, and is emitted from the exit surface 13 of the light guide plate 12. It exits and injects into the back surface of the liquid crystal display panel 1, and irradiates the liquid crystal display panel 1 from its back surface side. Then, image light corresponding to the display driving of the liquid crystal display panel 1 is emitted from the surface of the liquid crystal display panel 1.

By the way, in the conventional liquid crystal display device, the amount of light emitted from the exit surface 13 of the light guide plate 12 is equalized so that the luminance distribution emitted from the surface of the liquid crystal display panel 1 can be equalized. Next, this is explained. In the inclined surface 15 of the light guide plate 12, a plurality of spot-shaped dimming patterns due to black ink gradually become smaller as the dot-shaped black ink density is farther from the incident surface 14. The absorption rate of incident light is provided in proportion to the distance from the incident surface 14.

That is, in the vicinity of the cold cathode tube 17, the light reflected from the reflecting plate 16 of the light guide plate 12 and emitted from the exit surface 13 toward the liquid crystal display panel 1 is high. The black pattern density formed on the inclined surface 15 of the light guide plate 12 is increased in order to increase the absorption rate of the light, and as the distance from the cold cathode tube 17 increases, the intensity of light reflected from the reflector plate 16 decreases. The black pattern density formed on the inclined surface 15 of the light guide plate 12 is gradually reduced so that its absorption rate gradually decreases, so that the intensity of light emitted from the exit surface 13 of the light guide plate 12 is reduced to its entire surface. It is because it makes it uniform throughout.

However, in the conventional liquid crystal display device, since a plurality of point-shaped dimming patterns due to black ink are provided on the inclined surface 15 of the light guide plate 12, light is absorbed by the dimming pattern, resulting in poor light utilization efficiency and high luminance. There was a problem of deterioration.

Therefore, an object of the present invention is to provide an illumination panel and a display device using the same that can improve light utilization efficiency.

According to a first aspect of the present invention, an optical surface composed of a plurality of optical elements is provided on a light guide plate, and each optical element is a surface parallel to the exit surface with a part of the light introduced from the incident surface toward the end side edge facing the incident surface. It has a curved surface that is refracted at a low angle as follows, and the inclined surface that refracts the light refracted from the curved surface toward the exit surface side.

According to a second aspect of the present invention, an inclined surface extending in a direction substantially parallel to the incidence surface is formed in a light guide plate having an incidence surface into which light emitted from a point light source is introduced.

According to a third aspect of the present invention, an optical sheet is disposed on the emission surface side of the light guide plate, and the optical sheet passes through the light emitted from the emission surface of the light guide plate in a direction substantially perpendicular to the emission surface, and is edged from the emission surface of the light guide plate. The light emitted in an oblique direction toward the side is converted into light emitted from the surface of the optical sheet in a direction substantially perpendicular to the emission surface of the light guide plate.

According to the first aspect of the invention, since the light introduced from the incident surface is sufficiently refracted to the exit surface side of the light guide plate by the optical surface having the curved surface and the inclined surface formed on the light guide plate, the light utilization efficiency can be improved. have.

According to the second invention, since the light introduced from the point light source is refracted in the direction parallel to the incident surface by the inclined surface extending in a direction substantially parallel to the incident surface, the light utilization efficiency can be improved.

According to the third aspect of the present invention, since light emitted in an oblique direction from the exit surface of the light guide plate toward the end side side is converted by the optical sheet into a direction substantially perpendicular to the exit surface of the light guide plate, the light utilization efficiency can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS The main part side view of the liquid crystal display device as a 1st Embodiment of this invention.

FIG. 2 is a diagram for explaining the optical surface of the light guide plate shown in FIG. 1. FIG.

FIG. 3 is a diagram for explaining the refractive action of light incident from the incident surface of the light guide plate having the optical surface shown in FIG. 2. FIG.

FIG. 4 is a diagram for explaining the reflection effect on the optical surface of the light guide plate having the optical surface shown in FIG. 2. FIG.

FIG. 5 is a view for explaining the transmissive action of light in which light perpendicular to the transmissive and diffuser plate is applied as a substitute for the diffuser plate shown in FIG. 1; FIG.

FIG. 6 is a view for explaining the light transmission effect when oblique light is incident on the transmission and diffusion plate as a substitute for the diffusion plate shown in FIG. 1. FIG.

FIG. 7 is a view for explaining the outgoing light from the emitting surface of the light guide plate having the optical surface shown in FIG. 2; FIG.

Fig. 8 is a side view of the main portion of a liquid crystal display device according to a second embodiment of the present invention.

9 is an enlarged side view illustrating a first modification of the optical sheet shown in FIG. 8.

10 is an enlarged side view illustrating a second modification of the optical sheet shown in FIG. 8.

FIG. 11 is an enlarged side view showing a third modification of the optical sheet shown in FIG. 8. FIG.

12 is an enlarged side view illustrating a fourth modification of the optical sheet shown in FIG. 8.

13 is an enlarged side view illustrating a fifth modification of the optical sheet shown in FIG. 8;

Fig. 14 is a side view of the main portion of a liquid crystal display device according to a third embodiment of the present invention.

Fig. 15 is a side view of main parts of a liquid crystal display device according to a fourth embodiment of the present invention.

FIG. 16 is a diagram for explaining a state emitted from the virtual surface Q of light incident on the light guide plate from a point light source. FIG.

17 is a schematic perspective view of a part shown for explaining a liquid crystal display device according to a fifth embodiment of the present invention.

FIG. 18 is a view for explaining a state emitted from the virtual surface Q of light incident on the light guide plate from the point light source in the embodiment shown in FIG. 17. FIG.

Fig. 19 is a side view of main parts of a liquid crystal display device according to a sixth embodiment of the present invention;

FIG. 20 is a view for explaining the action of the light collecting sheet shown in FIG. 19; FIG.

FIG. 21 shows a first modification of the lighting panel shown in FIG. 19; FIG.

FIG. 22 shows a second modification of the lighting panel shown in FIG. 19; FIG.

Fig. 23 is a schematic perspective view of a part shown for explaining a liquid crystal display device as a fifth embodiment of the present invention.

24 is a partial side view of an example of a conventional liquid crystal display device.

※ Explanation of symbols for main parts of drawing

21 liquid crystal display panel 31 lighting panel

32: Light guide plate 33: exit surface

34: incident surface 35: optical surface

35a: curved surface 35b: flat surface

35c: slope 36: reflective layer

37: cold cathode tube 38: reflective sheet

41: diffusion plate 42: transmission and diffusion plate

51: optical sheet 52: plane

53: optical surface 54: reflector

61: optical diode 62: light collecting sheet

64: convex lens grandfather

<1st embodiment>

Fig. 1 shows a main part side view of a liquid crystal display device as a first embodiment of the present invention. The liquid crystal display device comprises a liquid crystal display panel 21, an illumination panel 31 disposed on the rear surface opposite to the surface of the viewing side thereof, and a diffusion plate 41 disposed between both panels 21 and 31. FIG. ).

In the liquid crystal display panel 21, the glass substrate 22 on the front side and the glass substrate 23 on the back surface are bonded together through a seal member (not shown) in a substantially rectangular frame, and both glass substrates 22, 23 and the seal member are bonded together. The liquid crystal (not shown) is enclosed in the space surrounded by the surface, and the surface side polarizing plate 24 is attached to the surface of the surface side glass substrate 22, and the back side polarizing plate ( 25) is attached.

The liquid crystal display panel 21 may be any of an active matrix type, a simple matrix type, a segment type, and the like, and the display method thereof may also be a TN (twist nematic) method, STN (super twisted nematic) method, or ECB (birefringence). Any method may be used as long as it controls the light transmittance such as an effect) method, a dynamic scattering effect method, or a method using ferroelectric liquid crystal.

The lighting panel 31 includes a light guide plate 32 provided on the rear surface side of the liquid crystal display panel 21. The light guide plate 32 has a planar square shape and is an exit surface 33 through which light exits a surface facing the liquid crystal display panel 21, and an incident surface on which light enters a predetermined one surface (left end surface in FIG. 1). It becomes 34 and the surface opposing the exit surface 33 becomes the optical surface 35. As shown in FIG. Moreover, the surface facing the incident surface 34 is the end edge 32a. As shown in FIG. 1, the optical surface 35 generally has the rear surface side of the light guide plate 32 toward the end edge 32a side from the incident surface 34 side as a whole with respect to the exit surface 33. It has the so-called bottom-shaped profile curved so that it may become thin gradually after thickness becomes thick gradually, The shape of this optical surface is the biggest feature of this invention, The detail is mentioned later.

The reflective layer 36 is formed on the optical surface 35 of the light guide plate 32. The cold cathode tube 37 which is a light source is provided in the position which opposes the incident surface 34 of the light guide plate 32. As shown in FIG. One end of the reflective sheet 38 covering the cold cathode tube 37 is attached to the surface on the incident surface 34 side of the light guide plate 32, and the other end is attached to the back surface on the incident surface 34 side of the reflector plate 36. It is.

Next, the optical surface 35 of the light guide plate 32 will be described with reference to FIG. 2. The optical surface 35 is a pair of optically arranged in the order of the curved surface 35a, the flat surface 35b, and the inclined surface 35c from the incident surface 34 side (left side in FIG. 2) toward the end edge 32a side. It is a surface with many elements installed in succession. The plane 35b is a surface parallel to the emission surface 33.

The length of the pair of optical elements consisting of the curved surface 35a, the plane 35b and the inclined surface 35c is about 20 to 500 µm, and the greater the distance from the incident surface 34, the better the transmission efficiency. The same effect can be obtained by setting the same dimension.

The plane 35b is a surface parallel to the emission surface 33. The inclination angle with respect to the plane 35b of the inclined surface 35c is the same, and is set at the appropriate angle within the range of about 40-50 degrees. The height H with respect to the plane 35b of the inclined surface 35c becomes gradually larger as it moves away from the incident surface 34. The height H of the inclined surface 35c is typically about 20 to 50 µm at maximum. It is set to an appropriate value by the plane size of the light guide plate 32, and is not limited to this value.

The length of the curved surface 35a is the same. The length of the plane 35b is gradually shortened as it moves away from the incident surface 34. That is, the height H of the inclined surface 35c increases in proportion to the distance from the incident surface 34, and the length of the plane 35b is shortened in proportion to the distance from the incident surface 34. As a result, the amount of light reflected (refractive) on the inclined surface 35c and directed toward the exit surface 33 increases exponentially in proportion to the distance from the incident surface 34.

Each optical element is arranged in the order of the curved surface 35a, the plane 35b and the inclined surface 35c from the incident surface 34 side of the light guide plate 32, and its curved surface 35a is its incident surface 34 It is provided continuously to the inclined surface 35c of the optical element of the neighbor of the side (left side of FIG. 2). The curved surface 35a is not intended to be limiting. Typically, its cross section is arcuate, and its radius of curvature is, for example, 0.01-2. It is about 0 mm. In this manner, the curved surface 35a is turned down to the right in FIG. 2.

Here, as an example, the height H with respect to the plane 35b of the nth inclined surface 35c from the incident surface 34 side is an (n + 1) / 2 (where a is any number, n is a natural number and the incident surface ( The first inclined surface 35c on the 34) side is 1). Thus, by raising the height H with respect to the plane 35b of the inclined surface 35c gradually away from the incident surface 34, it becomes possible to aim at the uniformity of the brightness in the emission surface 33, Further, as described above, as the optical surface 35 is directed from the incident surface 34 side to the end edge 32a side as shown in FIG. 1, the bottom of the light guide plate 32 gradually becomes thicker and then curved to become thinner gradually. It is also in order to further improve the uniformity of brightness on the emission surface 33.

In addition, in FIG. 1, the angle with respect to the exit surface 33 of the incident surface 34 may be 90 degrees normally. However, in order to make light incidence efficiency better, this angle may be made slightly smaller than 90 degrees. That is, when the light incident on the light guide plate 32 from the incident surface 34 goes straight and is directly reflected (refractive) on the inclined surface 35c of the optical surface 35 on the opposite side to the incident surface 34, only its region is bright. Since the other area becomes dark, the incident surface 34 is directed to the exit surface 33 so that the incident light proceeds while repeating the reflection on the curved surface 35a and the plane 35b of the exit surface 33 and the optical surface 35. When the angle is slightly increased, the light incidence efficiency is improved. Usually, this angle is 80 degrees or more and less than 90 degrees, On the contrary, 100 degrees or less may be less than 90 degrees, In other words, the light incident on the light guide plate 32 from the cold cathode tube 37 is inclined surface 35c of the light guide plate 32. It is good to reduce the probability of being reflected directly at.

The light guide plate 32 having the above structure can be manufactured by injection compression molding using a transparent resin having a high light transmittance such as acrylic resin. In addition, the reflective layer 36 shown in FIG. 1 is made of Al. The metal foil made of Ag, Cr, or the like may be bent to the optical surface 35 of the light guide plate 32 in a shape conforming to its profile, but Al. The metal foil may be formed on the optical surface 35 of the light guide plate 32 by sputtering or vapor deposition. You may form Ag, Cr, etc. by the metal film which formed into a film. The end edge 32a of the light guide plate 32 is preferably as thin as possible to prevent light leakage from excitation, and a reflective layer may be formed on the outer surface as necessary.

Here, since the liquid crystal display device of the present embodiment is a transmission and reflection type, first, the operation of the light guide plate 32 in the case of using it as a transmission type will be described with reference to FIG. 3. In FIG. 3, the thickness of the light guide plate 32 is appropriately set, and the reflection layer 36 shown in FIG. 1 is omitted.

In the case where the liquid crystal display device of the present embodiment is used as a transmissive type, as shown by arrows A, B, and C as a representative in FIG. 3, light incident on the incident surface 34 shown in FIG. 1 passes through the light guide plate 32. Proceed. The light indicated by the arrow A in the middle is reflected at the inclined surface 35c and is angularly converted in the direction substantially perpendicular to the exit surface 33, and is emitted from the exit surface 33 in the direction substantially perpendicular thereto.

Light indicated by the arrow B is reflected at the emission surface 33 and is incident on the curved surface 35a. In this case, since the curved surface 35a is not parallel to the exit surface 33 and is moved downward on the right side in FIG. 3, the light incident on the curved surface 35a is reflected to be at an angle shallower than the direction of incidence, and the plane of the same pair Proceed in the direction parallel to 35b. For this reason, the light shown by the arrow B is incident on the inclined surface 35c of the same pair as the reflected curved surface 35a.

In this way, the curved surface 35a descending toward the opposite side to the incident surface 34 is provided on each optical element so that the traveling direction of the light of arrow B reflected from the curved surface 35a of each optical element is the same pair of planes ( This is to ensure incidence of the same pair of inclined surfaces 35c close to the direction parallel to 35b). Then, the light incident on the inclined surface 35c is reflected by the inclined surface 35c and is angularly converted in a direction substantially perpendicular to the output surface 33 to be emitted from the output surface 33 in its approximately vertical direction.

The light represented by the arrow C travels in the light guide plate 32 from the incident surface 34 side to the end edge 32a side by repetition of the reflection in the plane 35b and the reflection in the exit surface 33, ie In FIG. 3, the flow proceeds to the right direction. Finally, the advancing light is reflected on the inclined surface 35c as in the case of the light indicated by arrow A and emitted from the exit surface 33 in its approximately vertical direction, or in the case of light indicated by arrow B. Similarly, after being reflected on the curved surface 35a, it is reflected on the same pair of inclined surfaces 35c and emitted from the exit surface 33 in its approximately vertical direction.

In this way, the light indicated by the arrows A, B, and C is finally reflected on any of the inclined surfaces 35c and emitted from the emitting surface 33 in its approximately vertical direction. In this case, the height H with respect to the plane 35b of the inclined surface 35c of each optical element is gradually increased toward the end edge 32a side from the incident surface 34 side shown in FIG. Therefore, the area of the inclined surface 35c gradually increases from the incidence surface 34 side toward the end edge 32a side. As a result, the area of the inclined surface 35c becomes large even if the amount of light decreases as it moves away from the incident surface 34, so that the amount of light emitted from the output surface 33 becomes uniform.

Next, the operation of the illumination panel 31 in the case of using the liquid crystal display device shown in FIG. 1 as a reflection type will be described.

As shown by arrows D, E, and F as representatives in FIG. 4, external light is incident on the emission surface 33. In this case, however, the deflection at the exit surface 33 is ignored. In addition, the external light shown by the arrows D, E, and F is light parallel to each other, and is the light which inclines with respect to the emission surface 33 toward the left to upper left in FIG.

Incidentally, the external light indicated by the arrow D is reflected on the plane 35b (actually, the portion corresponding to this position of the reflective layer 36), but for the sake of simplicity, the light guide plate 32 will be described. ), And is emitted from the exit surface 33. In this case, the reflection in the plane 35b is positive reflection. Therefore, the external light indicated by the arrow D is incident at the incident angle d with respect to the plane 35b, and is reflected at the reflection angle d, and its reflection angle is 2d.

The external light indicated by the arrow E is reflected from the right side in FIG. 4 among the curved surfaces 35a and exits from the exit surface 33. In this case, since the curved surface 35a is lowered to the right in FIG. 4, the reflection angle k on the curved surface 35a becomes smaller than the reflection angle 2d on the plane 35b.

Light indicated by the arrow F is reflected from the left side in FIG. 4 among the curved surfaces 35a and exits from the exit surface 33. Also in this case, the curved surface 35a is downwardly depressed in FIG. 4, but the angle with respect to the plane 35b of the tangential line at each point of the curved surface 35a gradually increases as it goes to the left side in FIG. 4. The reflection angle f on the left side of the curved surface 35a is smaller than the reflection angle e on the right side of the curved surface 35a.

As described above, in FIG. 4, the external light represented by the arrows D, E, and F incident on the emission surface 33 from the upper right to the lower left in parallel with each other is reflected at a reflection angle smaller than the reflection angle at the time of specular reflection or this reflection. It exits from the surface 33. In this case, the angle of reflection on the curved surface 35a gradually decreases toward the left side in FIG. 4, so that the angle with respect to the normal of the emission surface 33 of the external light reflected from the curved surface 35a and emitted from the emission surface 33 is reflected. Gradually decreases toward the left side in FIG.

Therefore, even if the eddy lights represented by arrows D, E, and F incident on the exit surface 33 are parallel to each other, the external light represented by arrows D, E, and F emitted from the exit surface 33 is in a direction perpendicular to the exit surface 33. 4 is collected on the left side of FIG.

Next, the case where the liquid crystal display shown in FIG. 1 is used as a transmissive type is demonstrated. When the cold cathode tube 37 is turned on, the light emitted from the cold cathode tube 37 and the light reflected by the reflective sheet 38 are incident on the incident surface 34 of the light guide plate 32. This incident light propagates in the light guide plate 32 as indicated by arrows A, B, and C as a representative in FIG.

The light represented by arrows A, B, and C is finally reflected on the inclined surface 35c of any of the above, and exits from the exit surface 33 in its approximately vertical direction. Therefore, almost all of the light incident on the incident surface 34 is finally reflected on the inclined surface 35c of which is emitted from the exit surface 33 in its approximately vertical direction.

In addition, in this case, as shown in FIG. 2, the height H with respect to the same pair of plane 35b of the inclined surface 35c becomes gradually high toward the end edge 32a side from the incident surface 34 side. Therefore, the area of the inclined surface 35c gradually increases from the incidence surface 34 side toward the end edge 32a side.

As a result, as the distance from the cold cathode tube 37 decreases, the area of the inclined surface 35c increases even though the amount of light decreases, so that the amount of light emitted from the exit surface 33 becomes uniform. In addition, in this case, almost all of the light incident on the incident surface 34 is reflected at the inclined surface 35c of the one and is emitted from the exit surface 33 in a substantially perpendicular direction thereof, thereby improving the light utilization efficiency and increasing the brightness. Can be.

Light emitted from the exit face 33 of the light guide plate 32 in a direction substantially perpendicular to the light guide plate 32 is diffused while passing through the diffuser plate 41, and then enters the rear surface of the liquid crystal display panel 21. ) From the back side of it. Then, image light corresponding to the display driving of the liquid crystal display panel 21 is emitted from the surface of the liquid crystal display panel 21.

As described above, when the liquid crystal display device shown in Fig. 1 is used as the transmission type, the light utilization efficiency of the illumination panel 31 can be improved, the luminance can be increased, and the luminance can be made uniform, so that the display quality can be improved.

On the other hand, when this liquid crystal display device is used as a reflection type, external light is used without turning on the cold cathode tube 37. That is, external light incident on the surface of the liquid crystal display panel 21 from the surface side thereof is transmitted through the liquid crystal display panel 21 and diffused while passing through the diffusion plate 41, and the exit surface 33 of the light guide plate 32 is exposed. Is incident on and reflected by the reflecting plate 36.

On the contrary, the reflected light is emitted from the exit surface 33 of the light guide plate 32, diffuses while passing through the diffusion plate 41, is incident on the rear surface of the liquid crystal display panel 21, and the liquid crystal display panel 21 Is examined from its back side. Then, image light corresponding to the display driving of the liquid crystal display panel 21 is emitted from the surface of the liquid crystal display panel 21.

Here, a case where the liquid crystal display device is actually used as a reflection type will be described. In an actual use state, when the upper end side of the screen of the liquid crystal display panel 21 is the right end side of FIG. 1, the liquid crystal display panel 21 is generally inclined so as to mainly enter the outside light from the upper right side of FIG. The screen is often visually viewed from the front direction of the screen of the liquid crystal display panel 21, that is, the direction perpendicular to the screen or slightly lower (left in FIG. 1).

Therefore, when the liquid crystal display panel 21 is tilted so as to mainly enter the external light coming from the upper right to the lower left of FIG. 1, the external light that has passed through the liquid crystal display panel 21 and the diffusion plate 41 as it is is represented in FIG. 4. As indicated by arrows D, E, and F, the light enters the exit surface 33 of the light guide plate 32. In this case, however, the deflection at the exit surface 33 is ignored. In addition, the external light shown by arrows D, E, and F is light parallel to each other.

The external light indicated by arrows D, E, and F incident on the exit surface 33 of the light guide plate 32 is specularly reflected as described above, or is reflected at a reflection angle smaller than the reflection angle at the time of the specular reflection, thereby exiting from the exit surface 33. It is emitted. In this case, since the angle of reflection on the curved surface 35a gradually decreases toward the left side in FIG. 4, the angle with respect to the normal of the emission surface 33 of the external light reflected from the curved surface 35a and emitted from the emission surface 33 is reflected. Gradually decreases toward the left side in FIG.

Therefore, even if the external light represented by the arrows D, E, F incident on the exit surface 33 is parallel to each other, the external light represented by the arrows D, E, F emitted from the exit surface 33 is in a direction perpendicular to the exit surface 33. 4 is collected on the left side of FIG. When the external light passes through the diffusion plate 41 and the liquid crystal display panel 21 as it is, the liquid crystal display panel 21 is slightly lower (left side in FIG. 1) than the front direction of the screen, that is, the direction perpendicular to the screen. Image light is focused and emitted.

As described above, when the liquid crystal display is actually used as a reflective type, the front direction of the screen of the liquid crystal display panel 21 is slightly lower than the vertical direction of the screen based on the external light coming from the upper right to the lower left of FIG. In this case, the image light can be emitted by condensing the image light in the direction of the left side. The emission direction of the image light in this case is the visual direction, so that a bright image is obtained.

By the way, the diffusion plate 41 is intended to improve the in-plane uniformity of transmitted light and reflected light when used as a transmission type or as a reflection type, to adjust the reagent angle accordingly, and to reduce double reflecting when used as a reflection type.

In addition, when the surface of the diffuser plate 41 is formed into an uneven shape by a pillar material or the like, the incident angle and incidence range of incidence of external light by this uneven shape are widened in the whole direction, and the double reflecting can be further reduced from high diffusivity. can do.

In addition, in the adhesive for attaching the back side polarizing plate 25 of the liquid crystal display panel 21 to the back side glass substrate 23 without using the diffusion plate 41, a pillar having a different refractive index from the adhesive is mixed and diffused into the adhesive. It may have a function. In addition, the pressure-sensitive adhesive having such a diffusion function may be used and the diffusion plate 41 may be used.

Instead of the general diffuser plate 41, the transmission and diffusion plate 42 as shown in FIG. 5 may be used. The transmission and diffusion plate 42 is formed by alternately arranging a transmission layer 43 made of colorless transparent resin or the like and a diffusion layer 44 made of white transparent resin or the like.

In this case, the thickness of the transmission and diffusion plate 42 is constant, but the transmission layer 43 and the diffusion layer 44 are together in the same direction with respect to the plate surface of the transmission and diffusion plate 42 (in this case, the upper right side in FIG. 5). Inclined to the lower left). In FIG. 5, the upper right side of the diffusion layer 44 and the lower left side of the diffusion layer 44 on the right side are in contact with each other in the horizontal direction.

3, when used as a transmissive type, the light emitted from the exit surface 33 of the light guide plate 32 in its approximately vertical direction is indicated by an arrow in FIG. The refracting on the surface of the () is ignored.) The light is diffused from the diffusion layer 44 of the transmission and diffusion plate 42 and exits from the surface of the transmission and diffusion plate 42.

In this case, in FIG. 5, the upper right side of the diffusion layer 44 and the lower left side of the diffusion layer 44 on the right side are in contact with each other in the left and right direction and overlap each other, and thus the direction substantially perpendicular to the exit surface 33 of the light guide plate 32. All of the light emitted by the light is reliably diffused in the diffusion layer 44 of any of the transmission and diffusion plates 42.

On the other hand, when used as a reflection type, as shown by the solid arrows in FIG. 6 (refractions on the front and back surfaces of the transmission and diffusion plate 42 are ignored), the external light propagated from the upper right to the lower left is transmitted and diffused. The permeable layer 43 of the plate 42 is permeated.

This transmitted light is reflected by the optical surface 35 of the light guide plate 32, as shown by the arrow in FIG. This reflected light is diffused and transmitted through the diffusion layer 44 of the transmission and diffusion plate 42 as indicated by the dotted arrow in FIG. 6 (ignoring the refraction at the back and the surface of the transmission and diffusion plate 42). It exits from the surface of the cumulus diffusion plate 42.

Also in this case, in FIG. 6, the upper right side of the diffusion layer 44 and the lower left side of the diffusion layer 44 on the right side are in contact with each other in the left and right directions, and thus all of the light emitted from the exit surface 33 of the light guide plate 32 is overlapped. Is reliably diffused in the diffusion layer 44 of any of the transmission and diffusion plates 42.

Here, the optical surface 35 of the light guide plate 32 is not limited to what is shown in FIG. For example, with reference to FIG. 2, the inclination angle with respect to the plane 35b of the inclined surface 35c of each optical element is in the range of about 40-50 degrees from the incident surface 34 side to the end edge 32a side. You may make it become large gradually as it heads.

Moreover, the length of each optical element which consists of the curved surface 35a, the plane 35b, and the inclined surface 35c may vary. For example, the length of the curved surface 35a and the plane 35b is made constant, and the height H of the inclined surface 35c is changed so that a pair of optical elements composed of the curved surface 35a, the plane 35b and the inclined surface 35c. The length of may vary. In this case, however, the length of the pair of optical elements composed of the curved surface 35a, the flat surface 35b, and the inclined surface 35c is in the range of about 20 to 500 mu m.

By the way, like the light indicated by arrows A, B, and C, the light finally reflected from the inclined surface 35c and emitted from the exit surface 33 in its approximately vertical direction is incident surface 34 shown in FIG. Almost not all of the light incident on it is part of it. In other words, part of the light reflected by the curved surface 35a or the plane 35b is emitted from the emission surface 33 as it is.

For this reason, as shown by the dashed-dotted line in FIG. 7, in the virtual surface P which is perpendicular to the exit surface 33 and the incident surface 34 of the light guide plate 32, the light reflected from the inclined surface 35c is a solid arrow. As shown by the figure, it exits from the exit surface 33 in the substantially perpendicular direction, and as the part of the light reflected by the curved surface 35a or the plane 35b is represented by the dotted line arrow, the exit surface of the light guide plate 32 is shown. The light exits in an oblique direction from side 33 toward the side away from its entrance face 34.

Therefore, almost all of the light incident on the incident surface 34 can be emitted from the emission surface 33, so that the light utilization efficiency can be improved, and the reflection on the inclined surface 35c due to the difference in the area of the inclined surface 35c. Thus, the amount of light emitted from the exit surface 33 can be made uniform. However, in FIG. 7, there is light emitted in an oblique direction from the exit face 33 of the light guide plate 32 toward the side away from its entrance face 34 as shown by the arrow of dotted line, so as to focus the light. The lower the peak luminance at the front of the liquid crystal display panel 21 is, the more it becomes possible to further improve the light utilization efficiency. Next, an embodiment capable of condensing light emitted in an oblique direction toward the side away from the exit surface 33 of the light guide plate 32 with respect to its entrance surface 34 is shown.

<2nd embodiment>

Fig. 8 shows a main part side view of the liquid crystal display device according to the second embodiment of the present invention. Also in this liquid crystal display device, the liquid crystal display panel 21 and the illumination panel 31 arrange | positioned at the back surface on the opposite side to the surface on the side which observes it are provided similarly to 1st Embodiment. However, an optical sheet 51 is disposed between the liquid crystal display panel 21 and the illumination panel 31 in this embodiment instead of the diffusion plate 41 in the first embodiment. The characteristic in this embodiment is the function of this optical sheet 51, and demonstrates the point which makes this characteristic the following. In addition, in the following description, the same code | symbol is attached | subjected to the same component as 1st Embodiment, and the description is abbreviate | omitted suitably.

The optical sheet 51 has a planar square shape, the surface of which faces the liquid crystal display panel 21 as the plane 52, and the rear surface opposite to the plane 52 as the optical plane 53. The optical surface 53 is composed of both inclined surfaces 53b and 53d of a substantially trapezoidal groove having a cross section formed at a constant pitch, and a plane 53c between the upper surface 53a and both grooves. That is, the optical surface 53 is continuous in the order of the plane 53a, the inclined surface 53b, the plane 53c, and the inclined surface 53d from the incidence surface 34 side of the light guide plate 32 toward the end edge 32a side. A pair of optical elements arranged in a row has a surface provided in succession. The shape of this optical surface 53 is the same in the perpendicular direction with respect to the bottom face of FIG. In other words, all of the grooves having a substantially trapezoidal shape in cross section extend and extend over the entire width thereof perpendicularly to both side surfaces of the optical sheet 51 in the width direction.

The planes 52, 53a, 53c are surfaces parallel to the exit surface 33 of the light guide plate 32. The inclination angle with respect to the plane 52 (surface parallel to the exit surface 33 of the light guide plate 32) of the inclined surface 53b is the same, and is a surface substantially perpendicular to the plane 52 or an inclined surface close thereto. . The inclination angle with respect to the plane 52 of the inclined surface 53d is the same, and is set at the appropriate angle within the range of about 30-50 degrees.

The length of the pair of optical elements consisting of the flat surface 53a, the inclined surface 53b, the flat surface 53c, and the inclined surface 53d is approximately equal to the pixel pitch of the liquid crystal display panel 21, or an integral fraction of the same pixel pitch. It is 1. The optical sheet 51 having the above structure can be produced by injection compression molding using a transparent resin having a high light transmittance such as an acrylic resin.

The optical sheet 51 has a function of condensing light emitted in an oblique direction from the exit surface 33 of the light guide plate 32 toward the end edge 32a side to the front side of the liquid crystal display panel 21. The operation of the optical sheet 51 will be described with reference to FIG. 9. As represented by arrows J, K, and L in FIG. 9, light emitted from the exit surface 33 of the light guide plate 32 shown in FIG. 8 passes through the optical sheet 51. As shown by the solid arrows in FIG. 7, the light is emitted from the exit surface 33 of the light guide plate 32 in a substantially perpendicular direction thereof and enters the planes 53a and 53c of the optical sheet 51. The light is transmitted through the optical sheet 51 as it is, and is emitted from the plane 52 of the optical sheet 51 in a direction substantially perpendicular thereto.

The light indicated by the arrow L is emitted in an oblique direction from the exit face 33 of the light guide plate 32 toward the end edge 32a side from the exit face 33 of the light guide plate 32, as indicated by the dotted arrows in FIG. Incident on the inclined surface 53b of the optical sheet 51, reflected from the inclined surface 53d, and angularly converted in a direction substantially perpendicular to the plane 52 of the optical sheet 51, and the plane 52 of the optical sheet 51. Is emitted in its approximately vertical direction.

In this way, the light indicated by arrows J, K, L is emitted from the plane 52 of the optical sheet 51 in its approximately vertical direction. Therefore, almost all of the light incident on the incident surface 34 of the light guide plate 32 is finally emitted from the plane 52 of the optical sheet 51 in its approximately perpendicular direction. As a result, the peak luminance at the front of the liquid crystal display panel 21 can be increased, and the light utilization efficiency can be sufficiently improved.

9, the optical surface 53 of the optical sheet 51 has planes 53a and 53c for transmitting the light indicated by arrows J and K as it is, and an inclined surface for allowing the light indicated by arrow L to enter. 53b and the inclined surface 53d for reflecting the light represented by this incident arrow L may be sufficient. Therefore, the optical surface 53 of the optical sheet 51 may be, for example, a surface having a flat surface 53a, an inclined surface 53b, and an inclined surface 53d, as shown in FIG. As shown, it is good also as a surface which has the inclined surface 53b, the plane 53c, and the inclined surface 53d.

For example, as shown in FIG. 12, the inclined surface 53d for reflecting light incident on the inclined surface 53b may be a curved arc shape. In this case, since the light reflected from the inclined surface 53d can be collected and emitted from the plane 52 in a substantially vertical direction, the peak luminance at the front of the liquid crystal display panel 21 can be further increased. .

For example, as shown in FIG. 13, the surface shown by the code | symbol "53a" is an inclined surface whose inclination angle with respect to the plane 53c (surface parallel to the exit surface 33 of the light guide plate 32) is about 20 degrees or less. You may also For example, when the inclination angle of the inclined surface 53a with respect to the plane 53c is set to 20 °, and the refractive index of the optical sheet 51 (acrylic resin as its material) is set to 1.49, it is indicated by an arrow in FIG. As described above, light emitted from the emitting surface 33 of the light guide plate 32 in its vertical direction and incident on the inclined surface 53a is emitted from the plane 52 at an angle θ (10.06 °) with respect to its vertical line. do. If the angle θ = ± 10 ° or less is defined in a substantially vertical direction, the inclination angle with respect to the plane 53c of the inclined surface 53a may be about 20 ° or less.

Next, the case where the liquid crystal display shown in FIG. 9 is used as a transmission type is demonstrated. When the cold cathode tube 37 is turned on, the light emitted from the cold cathode tube 37 and the light reflected by the reflective sheet 38 are incident on the incident surface 34 of the light guide plate 32, and the light guide plate 32 travels in the light guide plate 32. Reflected at the optical surface 35 of (32).

A part of the reflected light reflected by the optical surface 35 of the light guide plate 32 is emitted from the exit surface 33 in its approximately vertical direction as indicated by the solid arrow in FIG. 7, and is represented as a representative in FIG. 9. As indicated by arrows J and K, the light is transmitted through portions of the planes 53a and 53c of the optical sheet 51 and exits from the plane 52 of the optical sheet 51 in a direction substantially perpendicular thereto.

Almost all of the remaining portions of the reflected light reflected from the optical surface 35 of the light guide plate 32 are directed from the exit surface 33 of the light guide plate 32 to its incidence surface 34, as indicated by the dotted arrows in FIG. 7. The light exits in an oblique direction toward the farthest side, and is incident on the inclined surface 53b of the optical sheet 51 and reflected by the inclined surface 53d, as indicated by arrow L in FIG. 9. It exits from the plane 52 in its approximately vertical direction.

Also in this second embodiment, almost all of the light exiting from the cold cathode tube 37 and incident on the incident surface 34 of the light guide plate 32 is finally removed from the plane 52 of the optical sheet 51. The light exits in a substantially vertical direction. In this case, as shown in FIG. 2, the height H of the inclined surface 35c increases in proportion to the distance from the incident surface 34, and the length of the plane 35b is short in proportion to the distance from the incident surface 34. Therefore, the amount of light reflected by the inclined surface 35c and directed toward the exit surface 33 increases exponentially in proportion to the distance from the incident surface 34. As a result, even if the amount of light decreases as it moves away from the cold cathode tube 37, the amount of light emitted from the exit surface 33 becomes uniform, so that the light utilization efficiency can be improved, and the luminance can be made uniform.

Light emitted from the plane 52 of the optical sheet 51 in a substantially perpendicular direction thereof is incident on the rear surface of the liquid crystal display panel 21 and irradiates the liquid crystal display panel 21 from its rear surface side. Then, image light corresponding to the display driving of the liquid crystal display panel 21 is emitted from the surface of the liquid crystal display panel 21.

As described above, when the liquid crystal display device shown in Fig. 8 is used as a transmission type, the light utilization efficiency of the illumination panel 31 can be improved to increase the luminance, and the luminance can be made uniform, so that the display quality can be improved.

On the other hand, when this liquid crystal display device is used as a reflection type, external light is used without turning on the cold cathode tube 37. That is, external light incident on the surface of the liquid crystal display panel 21 from its surface side passes through the liquid crystal display panel 21, passes through the optical sheet 51, and enters the exit surface 33 of the light guide plate 32. And is reflected by the reflective layer 36. In this case, external light such as natural light or room light passes through portions corresponding to the planes 53a and 53c of the optical sheet 41 with almost no angle conversion.

In contrast to the above, the reflected light is emitted from the exit surface 33 of the light guide plate 32, passes through the optical sheet 51, is incident on the rear surface of the liquid crystal display panel 21, and the liquid crystal display panel 21 is connected to the same. We check from the back side of. Then, image light corresponding to the display driving of the liquid crystal display panel 21 is emitted from the surface of the liquid crystal display panel 21. In this case, the double glazing can be reduced by the optical sheet 51.

Third Embodiment

In the first and second embodiments described above, the case where the illumination panel 31 is arranged on the rear surface side of the liquid crystal display panel 21 as illustrated in FIGS. 1 and 8 has been described. As in the third embodiment of the present invention, the illumination panel 31 may be arranged on the surface side of the liquid crystal display panel 21.

In this case, the emission surface 33 of the light guide plate 32 of the illumination panel 31 is on the rear surface side, and the optical surface 35 is on the surface side. The reflective layer 36 is not provided on the optical surface 35 of the light guide plate 32. An optical sheet 51 similar to that of the second embodiment is disposed between the liquid crystal display panel 21 and the illumination panel 31. In the optical sheet 51, the plane 52 thereof faces the liquid crystal display panel 21. Further, a flat reflective plate 55 is provided on the rear surface side of the liquid crystal display panel 21.

Next, the case where the liquid crystal display shown in FIG. 14 is used as a transmission type is demonstrated. When the cold cathode tube 37 is turned on, the light emitted from the cold cathode tube 37 and the light reflected by the reflective sheet 38 are incident on the incident surface 34 of the light guide plate 32. Almost all of the incident light is emitted from the exit surface 33 of the light guide plate 32 as in the case of the second embodiment, and then exits from the plane 52 of the optical sheet 51 in its approximately perpendicular direction.

The emitted light passes through the liquid crystal display panel 21 and is reflected by the reflector plate 55. This reflected light is incident on the rear surface of the liquid crystal display panel 21 and irradiates the liquid crystal display panel 21 from its rear surface side. Then, image light corresponding to the display driving of the liquid crystal display panel 21 is emitted from the surface of the liquid crystal display panel 21. This image light passes through the optical sheet 51 and then passes through the light guide plate 32. And this transmitted image light is visually seen.

On the other hand, when the liquid crystal display shown in Fig. 14 is used as a reflection type, external light is used without turning on the cold cathode tube 37. That is, external light incident on the optical surface 35 of the light guide plate 32 from its surface side passes through the light guide plate 32, passes through the optical sheet 41, passes through the liquid crystal display panel 21, 55).

This reflected light is incident on the rear surface of the liquid crystal display panel 21 and irradiates the liquid crystal display panel 21 from its rear surface side. Then, image light corresponding to the display driving of the liquid crystal display panel 21 is emitted from the surface of the liquid crystal display panel 21. This image light passes through the optical sheet 51 and then passes through the light guide plate 32. And this transmitted image light is visually seen.

By the way, in the liquid crystal display device shown in FIG. 14, since the light penetrates the liquid crystal display panel 21 twice even when used as a transmissive type or as a reflective type, the polarizing plate may be either one of the front side or the back side. It is also possible to form an electrode for display pixels provided on the inner surface of the back side glass substrate 23 by a reflective metal without using the reflecting plate 55.

Fourth Embodiment

In each of the above embodiments, a case where a linear light source such as a cold cathode tube is used as a light source has been described. However, without limitation, a point light source such as a light emitting diode may be used. FIG. 15 shows one light emitting diode 61 disposed at a position opposite to the central portion of the light guide plate 32 of the liquid crystal display device in the longitudinal direction of the incident surface 34. By juxtaposing a plurality of light emitting diodes 61 along the longitudinal direction of the incident surface 34, the same luminance as in the case of a linear light source can be obtained.

By the way, in the case of the cold cathode tube 37 which is a linear light source, the whole incident surface 34 of the light guide plate 32 can be irradiated uniformly by the light emitted from the cold cathode tube 37. On the other hand, in the case of the light emitting diode 61 which is a point light source, the light incident from the light emitting diode 61 cannot irradiate the incident surface 34 of the light guide plate 32 uniformly.

For this reason, when the light emitting diode 61 is used, the light emitting diode in the imaginary plane Q that is parallel to the incident surface 34 perpendicular to the exit surface 33 of the light guide plate 32 indicated by a dashed line in FIG. 16. Among the lights emitted from 61, only light incident perpendicularly to the flat incident surface 34 is emitted in a direction perpendicular to the exit surface 33, as indicated by the solid arrow, and the other light is an imaginary plane Q. Irradiation at an inclined angle with respect to That is, among the light emitted from the point light source, light other than that which is incident on the incident surface 34 perpendicularly is emitted in the left and right beveled directions in the plane of the virtual surface Q, as indicated by the dotted arrow.

Therefore, as shown in FIG. 15, the brightness | luminance of the area | region shown by the code | symbol "N" in the both sides of the area | region shown by the code | symbol "M" substantially opposite to the light emitting diode 51 among the exit surfaces 34 of the light guide plate 32 is large. It is lowered and the light utilization efficiency is bad, and a luminance stain occurs. As a result, display stains occur on the liquid crystal display panel.

Therefore, a fifth embodiment of the present invention which can prevent such luminance spots from occurring is described next.

Fifth Embodiment

17 is a schematic plan view of a part shown for explaining the liquid crystal display device according to the fifth embodiment of the present invention.

In the liquid crystal display device of the present embodiment, one light emitting diode 61 is basically disposed at a position opposite to the central portion in the longitudinal direction of the incident surface 34 of the light guide plate 32 as in the case shown in FIG. 15. In this case, however, the inclined surface 35c of each optical element forming the optical surface of the light guide plate 32 is a surface that is irregularly corrugated in its longitudinal direction (direction parallel to the incident surface 34). . As an example, the waveform of the inclined surface 35c of each optical element is preferably an sine curve of 2aπ when the amplitude is a, but the wavelength λ is not limited to about 1 to 10 times the amplitude a. can do.

Thus, when the inclined surface 35c of each optical element has a wave shape, the virtual surface Q shown by the dashed-dotted line in FIG. 18 (one surface parallel to the incident surface 34 in the emission side of the emission surface 33) The light emitted from the light emitting diode 61 is not only light incident perpendicularly to the incident surface 34, as indicated by the solid arrow, but part of the light obliquely incident on the incident surface 34 is also a waveform of each optical element. It is incident perpendicularly to the inclined surface 35c of the shape. Since light incident on the inclined surface 35c perpendicularly is reflected in the direction perpendicular to the exit surface 33 of the light guide plate 32, the intensity of the emitted light in the viewing direction is increased, and the light guide plate 32 is also increased. The intensity of the exit light emitted from the exit surface 33 of the?

In the embodiment shown in FIG. 17, the corrugated inclined surface 35c formed in the light guide plate 32 is formed in a straight line in which the center line thereof is parallel to the incident surface 34. The profile can be appropriately modified such that the center line of the inclined surface 35c is in the shape of an arc or an ellipse centered on the light source 61. In addition, each inclined surface 34 may be out of phase of the wave in the width direction of the light guide plate 34, or may have a different pitch of the wave.

Here, in more detail in FIG. 18, another part of the light reflected by the inclined surface 35c of each optical element of the wave shape, as indicated by the dotted arrow, is inclined to the left and right in the plane of the virtual surface Q. As it progresses in the direction, the light intensity is uneven by this amount.

Then, 6th Embodiment of this invention which can emit more uniformly light from the emitting surface 34 of the light guide plate 32 is demonstrated.

Sixth Embodiment

Fig. 16 shows a perspective view of main parts of an illumination panel 31 as a sixth embodiment of the present invention. In this lighting panel 31, a light collecting sheet 62 is disposed between the light guide plate 32 and the optical sheet 51, and is positioned at a position opposite to the central portion in the longitudinal direction of the incident surface 34 of the light guide plate 32. Light emitting diodes 61 are arranged.

The light collecting sheet 62 has a planar square shape, and the surface facing the light guide plate 32 becomes the plane 63, and extends in the direction perpendicular to the incident surface 34 of the light guide plate 32 on the plane 63. The one side convex lens bath 64 has a structure provided in parallel. The surface of the single-sided convex lens jaw portion 64 may be in the shape of a cross section or may be in the shape of a cross section ellipse. The light collecting sheet 62 having such a structure can be produced by injection compression molding using a transparent resin having a high light transmittance such as acrylic resin. The light collecting sheet 62 may attach the plane 63 to the exit surface 33 of the light guide plate 32.

As shown by the solid arrow in FIG. 18, the light emitted from the exit surface 33 of the light guide plate 32 in an oblique direction to the left and right of the light guide plate 32 in the virtual plane Q is shown in FIG. 20. As shown by the solid arrows in the graph, the light is collected at the central side of each convex lens bath 64 by the one-sided convex lens bath 64 of the light collecting sheet 62 to the plane 63 of the light collecting sheet 62. The light exits in a substantially vertical direction. That is, as shown by arrows of solid and dashed lines in FIG. 18, light emitted from the exit surface 33 of the light guide plate 32 in a direction parallel to the incident surface 34 thereof is collected by the light collecting sheet 62. In the plane of the virtual surface Q, the light is refracted toward the direction substantially perpendicular to the plane 63 of the light condensing sheet 62 (direction parallel to the solid arrow) and emitted.

Therefore, even if the incident surface 34 of the light guide plate 32 cannot be uniformly irradiated by the light emitted from the light emitting diode 61, the light is emitted more uniformly from the plane 63 of the light collecting sheet 62, so that the light utilization efficiency is improved. This is good and the luminance is also uniform. As a result, display stains may be prevented from occurring in the liquid crystal display panel. In addition, in the above, the incident surface 34 of the light guide plate 32 can also have the same waveform shape as the inclined surface 35c. It is necessary to take care that denseness does not occur in the amount of light incident on the light guide plate 32.

On the other hand, when the liquid crystal display device having the illumination panel 31 shown in Fig. 19 is used as a reflection type, since the surface of the single-sided convex lens jaw portion 64 of the light collecting sheet 62 has no vertex angle, external light incident efficiency can be improved. have.

21 shows a modification of the sixth embodiment. In this embodiment, the light condensing part 62 having the same structure as that of the light collecting sheet 62 shown in FIG. 19 is integrally formed on the surface of the light guide plate 32. 22 shows another modification of the sixth embodiment. In this modification, the optical sheet 51 is disposed between the light guide plate 32 and the light collecting sheet 62. The light collecting sheet 62 and the optical sheet 51 are the same as those shown in FIG. 19, respectively.

Although not shown, the optical sheet 51 has a function, that is, light emitted in an oblique direction from the exit surface 33 of the light guide plate 32 toward the end edge 32a, is substantially perpendicular to the exit surface 33. The exit surface of the light guide plate 32 in the function of converting in the phosphorus direction and in the plane (parallel of the virtual surface Q) parallel to the incident surface 34 of the light guide plate 32. It is good also as an optical film which has the function to convert the light radiate | emitted obliquely from (33) to the direction substantially perpendicular to the emission surface 33 in total. Such an optical film is not the reason for limiting the embodiment. For example, the optical film 51 and the light condensing sheet 62 in FIG. 22 are obtained by integrating each plane so as to be in close contact with each other.

19, 21, and 22, a cold cathode tube (line light source) may be used instead of the light emitting diode 61. As shown in FIG. In this case, the luminance can be further increased by the light condensing action in a direction parallel to the incident surface 34 of the light guide plate 32 by the light collecting sheet 62.

In addition, when using a light emitting diode as a light source, not only one but you may arrange more than one. In this case, even if there is color scattering in the light emitting diode itself, it may be difficult to recognize it by the waveform shape of the inclined surface 35c of the light guide plate 32. In this case, when the light emitting diode emits light of each of the three primary colors, white or full color display can be performed. The seventh embodiment is such an example.

Seventh Embodiment

Fig. 23 shows three light emitting diodes 61R, 61G and 61B of a plurality of different light emitting colors, for example, red light, green light and blue light, along the longitudinal direction of the incident surface 34 of the light guide plate 32; It is placed. In this case, by appropriately flashing the three light emitting diodes 61R, 61G, and 61B, colors other than the light emitting color of the light emitting diode alone can be obtained by mixing.

In this embodiment, the field sequential driving in which full color display is performed without using a color filter is shown. The controller 71 generates a horizontal control signal or a vertical control signal to control the data line driver 72, the scan line driver 73, and the field sequential drive control unit 74. This field sequential driving is divided into three subfield periods in which one field period consists of first to third subfield periods. In the first sub-field period, the gray line data is supplied from the data line driver 72 to each data line while scanning the scan line of the liquid crystal display panel by the scan line driver 73 in time. The liquid crystal is driven, and the lighting signal is supplied from the field sequential drive control unit 74 to the light emitting diode 61R in synchronization with the driving of the liquid crystal. In the second subfield period, the scanning line driver 73 scans the scanning lines of the liquid crystal display panel, supplies green gradation data to each data line from the data line driver 72 at the timing of scanning each scanning line, and drives the liquid crystal. The sequential drive control unit 74 supplies the lighting signal to the light emitting diode 61G in synchronization with the driving of the liquid crystal. In the third subfield period, the scan line driver 73 scans the scan line of the liquid crystal display panel, supplies blue grayscale data from the data line driver 72 to each data line to drive the liquid crystal at the same time as the scan of each scan line. The sequential drive control unit 74 supplies the lighting signal to the light emitting diode 61B in synchronization with driving of the liquid crystal. In such field sequential driving, the luminance can be further increased by the light condensing action in a direction parallel to the incident surface 34 of the light guide plate 32 by the light collecting sheet 62.

As described above, according to the first aspect of the present invention, since the light introduced from the incident surface is sufficiently refracted to the exit surface side of the light guide plate by the optical surface having the curved surface and the inclined surface formed on the light guide plate, the light utilization efficiency Can improve.

According to the second invention, since the light introduced from the point light source is refracted in the direction parallel to the incident surface by the inclined surface extending in a direction substantially parallel to the incident surface, the light utilization efficiency can be improved.

According to the third aspect of the present invention, since light emitted in an oblique direction from the exit surface of the light guide plate toward the end side side is converted by the optical sheet into a direction substantially perpendicular to the exit surface of the light guide plate, the light utilization efficiency can be improved.

Claims (28)

It is an illumination panel which consists of light sources 37 and 61 and the light guide plate 32, The light guide plate 32 includes an incidence surface 34 that receives light emitted from the light sources 37 and 61, an end side edge 32a formed on a side opposite to the incidence surface 34, and the incidence surface ( An emission surface 33 for emitting the light introduced from 34, and an optical surface 35 having a surface opposite to the emission surface 33, The optical surface 35 is composed of a plurality of optical elements in succession, Each optical element has a curved surface 35a that refracts a part of the light introduced from the incident surface 34 toward the end side edge 32a at a low angle as follows along a plane parallel to the exit surface 33. And an inclined surface (35c) for refracting the light refracted by the curved surface (35a) toward the exit surface (33). The method of claim 1, Illumination panel, characterized in that the curved surface (35a) of each optical element is gradually lowered toward the end edge (32a) side from the exit surface (33) side. The method of claim 2, Illumination panel, characterized in that the curved surface (35a) of each optical element is a cross-sectional arc shape. The method of claim 1, And each optical element has a plane (35b) between the curved surface (35a) and the inclined surface (35c). The method of claim 1, The height of the inclined surface (35c) of the optical element is larger than the position on the incident surface (34) side of the illumination panel, characterized in that located on the end edge (32a) side. The method of claim 1, And a height with respect to the plane (35b) of the inclined surface (32a) of the nth optical element from the incidence surface (34) side is an (n + 1) / 2 (where a is any number). The method of claim 1, The thickness of the end edge 32a is smaller than the thickness of the incidence surface 34, and a maximum portion of the thickness exists between the incidence surface 34 and the end side edge 32a. Lighting panel. The method of claim 1, And an inclination angle with respect to the plane (35b) of the inclined surface (35c) of each optical element is about 40 to 50 degrees. The method of claim 1, An inclination angle of the inclined surface (35c) with respect to the plane (35b) of each optical element is larger than that of the incidence surface (34) side on the end side (32a) side. The method of claim 1, And the length of each optical element is substantially equal. The method of claim 1, And the length of each of the optical elements is smaller at the end edge (32a) than at the entrance face (34). The method of claim 1, The illumination panel further includes an optical sheet 51 disposed on the exit surface 33 side of the light guide plate 32, The optical sheet 51 transmits the light emitted from the exit surface 33 of the light guide plate 32 in a direction substantially perpendicular to the exit surface 33 as it is, Light emitted in an oblique direction from the exit surface 33 of the light guide plate 32 toward the end edge 32a side is approximately from the surface of the optical sheet 51 with respect to the exit surface 33 of the light guide plate 32. Lighting panel, characterized in that converted to light emitted in a vertical direction. The method of claim 12, And a light collecting sheet 61 disposed on one of a surface side of the optical sheet 51 and between the light guide plate 32 and the optical sheet 51, The light condensing sheet 61 emits light emitted in an oblique direction from the light emitting plate 33 of the light guide plate 32 in a plane parallel to the incident surface 34 of the light guide plate 32. Illuminating panel, characterized in that converted from the light emitted in a direction substantially perpendicular to the exit surface (33) of the light guide plate (32). An incidence surface 34, an incidence surface 33, and an inclined surface 35c each of which refracts light introduced from the incidence surface 34 toward the emission surface 33, and includes a plurality of optical elements. The light guide plate 32 which has the optical surface 35 which consists of, and It is an illumination panel comprising light sources 37, 61 disposed to face the incident surface 34 of the light guide plate 32, The inclined surface (35c) of the light guide plate (32) is a lighting panel, characterized in that the waveform in the longitudinal direction. The method of claim 14, The light source 61 is a lighting panel, characterized in that the point light source. The method of claim 14, The light source (61) is an illumination panel comprising three kinds of point light sources (61R, 61G, 61B) of red light, green light and blue light. The method of claim 14, Each of the optical elements faces a part of the light incident on the incident surface 34 toward the end side edge 32a of the side opposite to the incident surface 34, and is parallel to the surface parallel to the exit surface 33. Lighting panel further comprises a curved surface (32a) reflecting at a low angle as follows. Light sources 37 and 61, An incident surface 34 for introducing the light emitted from the light source 37, an end edge 32a formed on the side opposite to the incident surface 34, and the light introduced from the incident surface 34 A light guide plate 32 having an emission surface 33, an optical surface 35 having a surface facing the emission surface 33, It is an illumination panel provided with the optical sheet 51 arrange | positioned at the emission surface side of the said light guide plate 32, The optical sheet 51 transmits the light emitted from the exit surface 33 of the light guide plate 32 in a direction substantially perpendicular to the exit surface 33 as it is, Light emitted in an oblique direction from the exit surface 33 of the light guide plate 32 toward the end edge 32a side is approximately from the surface of the optical sheet 51 with respect to the exit surface 33 of the light guide plate 32. Lighting panel, characterized in that converted to light emitted in a vertical direction. The method of claim 18, The surface of the optical sheet 51 is a plane 52 parallel to the exit surface 33 of the light guide plate 32, The rear surface of the optical sheet 51 is composed of a plurality of consecutive optical elements, Each of the optical elements may include planes 53a and 53c parallel to the exit surface 33 of the light guide plate 32; It has an inclined surface 53d that refracts light emitted in an oblique direction from the exit surface 33 of the light guide plate 32 toward the end edge 32a side to exit in the vertical direction from the surface of the optical sheet 51. A lighting panel characterized by the above-mentioned. The method of claim 18, And a light collecting sheet 61 disposed on one of a surface side of the optical sheet 51 and between the light guide plate 32 and the optical sheet 51, The light collecting sheet 61 emits light emitted in an oblique direction from the exit surface 33 of the light guide plate 32 in a plane Q parallel to the incident surface 34 of the light guide plate 32. A light panel, characterized in that for converting light from the surface of the light emitting plate in the direction substantially perpendicular to the exit surface (33) of the light guide plate (32). The method of claim 20, The light collecting sheet (61) is a lighting panel, characterized in that a plurality of convex lens jaw portions (64) extending in a direction perpendicular to the incident surface (34) of the light guide plate (32) in parallel. The surface which recognizes a display image, A display panel 21 having a rear surface opposite to the surface; It is a display device which consists of the illumination panel 31 arrange | positioned at either one of the front side and the back side of the said display panel 21, The illumination panel 31 is composed of light sources 37 and 61 and the light guide plate 32, The light guide plate 32 includes an incidence surface 34 that receives light emitted from the light sources 37 and 61, an end side edge 32a formed on a side opposite to the incidence surface 34, and the incidence surface ( An emission surface 33 for emitting the light introduced from 34, and an optical surface 35 having a surface opposite to the emission surface 33, The optical surface 35 is composed of a plurality of optical elements in succession, Each optical element has a curved surface 35a that refracts a portion of the light introduced from the incidence surface 34 toward the end side edge 32a at a low angle as follows along a plane parallel to the exit surface 33. And an inclined surface (35c) for refracting light refracted at the curved surface (35a) toward the exit surface (33). The surface to visually check the display image, A display panel 21 having a rear surface opposite to the surface; It is a display device which consists of the illumination panel 31 arrange | positioned at either one of the front side and the back side of the said display panel 21, The lighting panel 31, Light sources 37 and 61 and An incident surface 34, an exit surface 33, and an inclined surface 35c each of which refracts light introduced from the entrance surface 34 toward the exit surface 33, and includes a plurality of optical elements. It consists of a light guide plate 32 having an optical surface 35 made of, And a light source 61 disposed to face the incident surface 34 of the light guide plate 32, Each inclined surface (35c) of the light guide plate (32) has a wave shape in the longitudinal direction thereof. The surface which recognizes a display image, A display panel 21 having a rear surface opposite to the surface; It is a display device which consists of the illumination panel 31 arrange | positioned at either one of the front side and the back side of the said display panel 21, The lighting panel 31, Light sources 37 and 61, An incident surface 34 for introducing the light emitted from the light sources 37 and 61, an end side edge 32a formed on a side opposite the incident surface 34, and light introduced from the incident surface 34; A light guide plate 32 having an emission surface 33 for emitting light, an optical surface 35 having a surface facing the emission surface 33, and Comprising an optical sheet 51 disposed on the emission surface 33 side of the light guide plate 32, The optical sheet 51 transmits the light emitted from the exit surface 33 of the light guide plate 32 in a direction substantially perpendicular to the exit surface 33 as it is, Light emitted in an oblique direction from the exit surface 33 of the light guide plate 32 toward the end edge 32a side is approximately from the surface of the optical sheet 51 with respect to the exit surface 33 of the light guide plate 32. And a display device for converting light emitted in a vertical direction. The method of claim 24, The surface of the optical sheet 51 is a plane 52 parallel to the exit surface 33 of the light guide plate 32, The rear surface of the optical sheet 51 is composed of a plurality of consecutive optical elements, Each of the optical elements may include planes 53a and 53c parallel to the exit surface 33 of the light guide plate 32; It has an inclined surface 53d that refracts light emitted in an oblique direction from the exit surface 33 of the light guide plate 32 toward the end edge 32a side to exit in the vertical direction from the surface of the optical sheet 51. Display device characterized in that. The method of claim 24, A direction parallel to the incident surface 34 from the exit surface 33 of the light guide plate 32 on either the surface side of the optical sheet 51 and between the light guide plate 32 and the optical sheet 51. And a light collecting sheet 61 for collecting light emitted from the light. The method of claim 26, The light collecting sheet (61) is characterized in that the convex lens unit (64) extending in a direction perpendicular to the incident surface (34) of the light guide plate (32) is formed in parallel. The method of claim 24, The optical sheet 51 emits light emitted from the exit surface 33 of the light guide plate 32 toward the end edge 32a in an oblique direction from the surface of the optical sheet 51 to the light guide plate 32. A function of converting light emitted in a direction substantially perpendicular to the surface 33, Light emitted in an oblique direction from the exit surface 33 of the light guide plate 32 in a plane Q parallel to the incident surface 34 of the light guide plate 32 is moved from the surface of the optical sheet 51 to the light guide plate. And a function for converting the light emitted in a direction substantially perpendicular to the exit surface (33) of (32).