JPH09211234A - Lighting device and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device of high uniformity which can reduce luminance unevenness with simple constitution and a liquid crystal display device which uses this lighting device. SOLUTION: The lighting device B is equipped with a light guide plate 1 which has a light emission surface 2 as at least one surface, a notched part 5 which is formed on the flank 3 of this light guide plate 1, and a reflection type lamp L composed by storing a part of a bulb L1 in the notched part 5, forming a translucent light reflecting surface L2 at the part of a thin part 4 formed by cutting opposite the light emission surface 2 and a part that is not surrounded with the light guide plate 1, and arranging an opening part L3 that does not have the light reflecting surface so that it faces in the extension direction of the light guide plate 1, and the lighting device B is built in the liquid crystal display device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device used for general lighting, a television using a liquid crystal, a backlight for a personal computer or a word processor, or a display device such as an induction lamp, and a liquid crystal incorporating the lighting device. Regarding display device.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices such as televisions, personal computers and word processors using liquid crystals, and display devices such as characters and figures have been promoted to be small in size and have high brightness and high uniformity.

There are roughly two types of backlight devices for illuminating the liquid crystal display device and the like from the back side. One is to place a fluorescent lamp inside a concave reflecting mirror, and a light diffusing plate is installed in the opening of this reflecting mirror to diffuse the light emitted from the lamp either directly or by the reflecting plate. This is a reflector system that makes a liquid crystal panel enter and emit light. The other is to arrange a fluorescent lamp on the side surface of a plate-shaped light guide plate having a reflecting means and a light diffusing means formed on one surface side, and let the light emitted from the lamp enter the light guide plate so that the other surface side There is a light guide plate type in which the light is emitted from the outside and is incident on the light diffusing plate to emit the light to the outside.

In general, a reflector system using a reflector has a high luminous efficiency, but since the backlight device becomes thick, it becomes large in size and is used by being incorporated in a large-sized device. Further, although the light guide plate method can be made thin and small, it has a drawback of low luminous efficiency.

Therefore, also in this light guide plate system, as described in, for example, Japanese Utility Model Laid-Open No. 3-119876, the lamp disposed on the side surface of the light guide plate may be a reflection type fluorescent lamp, or Japanese Patent Laid-Open No. As described in Japanese Patent No. 238490, a reflector is used so that a large amount of light is made incident on the light guide plate from the lamp to enhance the light emission efficiency.

In order to uniformly illuminate the liquid crystal panel surface as a backlight device, a light guide plate having a size corresponding to the panel surface is required, and a fluorescent lamp is arranged facing the side surface of the light guide plate. In the installed one, the width of the light guide plate and the width of the fluorescent lamp were added. That is,
The backlight device requires a larger space than the liquid crystal panel. In addition, although this backlight device has fluorescent lamps arranged along the outside of the light guide plate and is close to each other,
Except for the closest line in the bulb axis direction, there is a gradually expanding air gap between the two, and this air gap was one of the causes for reducing the intensity of light emitted from the lamp.

[0007]

On the other hand, in a backlight device, in order to reduce the gap between the above-mentioned light guide plate and the fluorescent lamps arranged along the light guide plate, the fluorescent lamps are provided along the side surface of the light guide plate. It is known, for example, from Japanese Patent Application Laid-Open No. 3-280079 to provide a recess into which a bulb is inserted and dispose a fluorescent lamp in the recess to downsize the device. With such a structure, the device can be downsized and the luminous efficiency can be improved.

However, the publication described in this publication does not mention or even suggest that the reflective surface is directly or indirectly formed on the fluorescent lamp. If a fluorescent lamp of all-light reflection type is applied instead of the fluorescent lamp that emits light from the entire peripheral surface described in this publication, high intensity light is emitted with directivity from the opening of the lamp, but the directivity is incorrect. Moreover, there is a problem that uniform brightness cannot be obtained on the light emitting surface of the light guide plate unless the thickness of the light guide plate is taken into consideration.

That is, when a fluorescent lamp which emits light almost uniformly from the entire peripheral surface of the bulb is used, the emitted light in the direction not facing the light guide plate becomes ineffective, and the concave portion is formed. Since the distance from the lamp becomes closer to the thinner plate thickness direction, the light emission intensity is high, and the edge of the light guide plate where the lamp is housed has higher brightness than other parts. The loss is large, and the unevenness of brightness occurs on the light emitting surface of the light guide plate, and the uniformity is lowered.

When an all-light reflection type fluorescent lamp is used as the lamp, the light is surely concentrated in the opening portion where the reflecting surface is not formed, and the directivity is improved. If the opening is directed in the plate thickness direction which is thinned by the formation, the edge portion of the light guide plate has higher brightness than the other parts, and uneven brightness occurs, as described above. Also, in order to avoid this, unless the opening is directed in the direction of the thin plate thickness, the edge portion of the light guide plate has a significantly lower brightness than other portions,
This is also an unfavorable result that uniform luminance cannot be obtained on the light emitting surface of the light guide plate.

The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide an illumination device having a high degree of uniformity and capable of reducing the occurrence of luminance unevenness with a simple configuration, and a liquid crystal display device using this illumination device.

[0012]

According to a first aspect of the present invention, there is provided a lighting device having a plate-like light guide plate having a light emitting surface on at least one surface, a notch formed on a side surface of the light guide plate, and a light guide plate. A valve portion is housed in the notch, and a semi-transparent light-reflecting surface is formed in a portion facing the light emitting surface of the thin portion formed by the notch and a portion not surrounded by the light guide plate, and an opening having no light reflecting surface. And a reflection type lamp in which the light guide plate is arranged in the extending direction of the light guide plate.

When the lamp is housed inside the side surface of the light guide plate and the lamp is turned on, the semi-transparent reflection film forming part facing the thin part of the light guide plate does not reflect and block all light. Relatively low intensity (amount) that part of the light transmitted
Is emitted, and the reflected light reflected by the reflective film is superimposed on the directed direct light from the opening facing the thick portion where the light guide plate extends, so that high intensity ( Amount) of light is emitted. Then, the light entering the light guide plate is repeatedly reflected by the surface and the reflection surface,
Since the light is emitted from the light emitting surface of the light guide plate substantially uniformly, a substantially uniform brightness distribution with a small difference in brightness can be obtained over the entire light emitting surface.

The semi-transparent reflective film L2 referred to in the present invention has a luminous efficiency of transmitting several to several tens of percent of visible light, while the reflectance of visible light of the total light reflecting film is 100%. In general, it means a film whose back side is transparent. This semi-transparent light-reflecting film may be a metal thin film such as aluminum or silver, but it is a light-transmitting film such as titanium oxide, aluminum oxide, phosphor, etc. It may be a white film having a white property.

Further, the film thickness and the forming angle of the semi-transparent light-reflecting film to be formed can be determined according to the required characteristics such as luminance uniformity, the type of light guide plate, the size and thickness, the type of lamp and the output. Good.

An illumination device according to a second aspect of the present invention is characterized in that the cutout portion is formed in a concave groove shape along the center of the side surface of the light guide plate.

The reflection type lamp is accommodated and arranged in the concave groove-shaped notch formed in the central portion of the side surface of the light guide plate, and the operation according to claim 1 is achieved.

The illumination device according to a third aspect of the present invention is characterized in that the notch is formed in a step shape along the side corner of the light guide plate.

The reflective lamp is housed and arranged in the notch formed in the side corner of the light guide plate, and the above-mentioned operation is achieved.

According to a fourth aspect of the present invention, a light emitting surface is formed on the flat surface side connected to the thin portion formed by the notch portion of the light guide plate, and a light reflecting surface is formed on the opposite surface side. It is characterized by

Even if the lamp is housed inside the light guide plate, the space on the light emitting surface side does not change, and light can be emitted from one surface of the light guide plate with high efficiency.

The illumination device according to a fifth aspect of the present invention is characterized in that light-emitting surfaces are formed on both surfaces of the light guide plate.

Even if the lamp is housed in the light guide plate, the space on the light emitting surface side does not change, and light can be emitted from both front (front and back) surfaces of the light guide plate.

An illumination device according to a sixth aspect of the present invention is a plate-shaped light guide plate having a light emitting surface on one surface and a light reflecting surface on the other surface, and an intermediate portion between the light emitting surface side and the light reflecting surface side of the light guide plate. A cutout portion formed in the portion and a bulb portion is housed in the cutout portion, and a semitransparent light reflecting surface is provided in a portion facing the light emitting surface of the thin portion formed by the cutout and a portion not surrounded by the light guide plate. And a reflective lamp in which an opening portion having no light reflecting surface is provided so as to face the extending direction of the light guide plate.

The lamp is housed and disposed in the middle portion of the light guide plate, and the same operation as that described in the first aspect is achieved.

The illumination device according to a seventh aspect of the present invention is characterized in that a convex lens is provided between an opening portion of the reflection type lamp having no light reflecting surface and a light incident portion of the light guide plate.

Radiation light traveling from the opening of the lamp to the light guide plate is deflected through a convex lens and introduced into the light incident part of the light guide plate. In this way, the convex lens is used to allow light to be incident within a desired range and refracted within the light guide plate, and substantially uniform light emission is achieved from the entire light emitting surface, and the same operation as in claim 1 is achieved.

The illumination device according to claim 8 of the present invention is characterized in that the convex lens and the light guide plate are integrated.

Since the convex lens and the light guide plate are adjacent to each other with no space therebetween, the light loss when the light guide plate is incident is small, and the brightness of the light emitting surface can be improved.

The illumination device according to claim 9 of the present invention is characterized in that a display plate is provided on the light emitting surface side of the light guide plate.

Characters, figures, etc. can be displayed by using the light emitting surface of the light guide plate, which emits light uniformly over almost the entire surface, as a light source.

An illumination device according to claim 10 of the present invention comprises:
The light-reflecting surface of the reflective lamp is characterized by transmitting part of visible light.

When the light-reflecting surface reflects all the light, all the light is reflected and shielded by the reflecting surface, and the light-reflecting surface of the present invention is visible in order to prevent a large difference in brightness from other light-emitting surfaces. Part of the light is transmitted to be dimmed to reduce the difference in brightness between the other light emitting surface and the light emitting surface, thereby making the luminance distribution uniform over the entire light emitting surface.

A liquid crystal display device according to an eleventh aspect of the present invention is a lighting device according to any one of the first to tenth aspects, and a light provided on a light emitting surface side of a light guide plate of the lighting device. It is characterized by including a diffuser and a liquid crystal panel provided so as to face the light diffuser.

By using the illuminating device having the operation described in any one of claims 1 to 10, the uneven brightness on the display surface of the liquid crystal panel is reduced.

[0036]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described with reference to FIG. FIG. 1 shows a liquid crystal display device E.
2 is a side sectional view showing a part of the sidelight type backlight device (illumination device) B in FIG. 1 in an enlarged manner.

The liquid crystal display device E has a form in which a backlight device (illumination device) B is provided on the back surface of the liquid crystal panel P via a light diffusion plate K so as to overlap with each other. This backlight device (illumination device) B is, for example, a synthetic resin such as translucent acrylic resin or polycarbonate resin, or a flat plate-like plate made of quartz glass and extending with a predetermined wall thickness in the shape of a quadrangle or an oblong quadrangle. The light guide plate 1 is provided. A flat light emitting surface 2 is formed on a surface of the light guide plate 1 facing the liquid crystal panel P, and a thin portion 4 and a cut portion 5 are formed by cutting one side surface 3 in a step shape along a corner. Also, the back surface and the notch 5
On the other side surfaces 3, 3, 3 are formed reflective surfaces 6 coated with white metal paste or attached with aluminum foil. Further, it is preferable that the reflecting surface 6 is not smooth but has an uneven surface or the like and has a light diffusing effect. Also,
A straight tubular reflection type fluorescent lamp L is provided in the stepped notch 5.
Is housed.

As shown in the cross section of FIG. 2, this fluorescent lamp L has a circular glass bulb L1 having an inner diameter of about 27 mm.
A semi-transparent reflection film L2 made of titanium oxide, aluminum oxide or the like is formed over a range of 0 degree.
A phosphor film L4 is formed on the surfaces of the second portion and the remaining opening L3 of the bulb L1 portion. Also, the valve L1
A discharge electrode (not shown) and a discharge medium such as a rare gas or mercury are enclosed inside. The semi-transparent reflection film L2 referred to in the present invention means that the total light reflection film has a visible light reflectance of 100%, while a visible light that transmits only a few to several tens of visible light. Means a film whose back side is transparent.

In this reflection type fluorescent lamp L, the semitransparent reflection film L2 is formed in a portion not surrounded by the light guide plate 1 and in a portion which becomes a thin portion 4 due to a notch, and serves as a main light emission window. When the opening angle θ of the opening L3 is about 90 degrees, the light incident portion 11 between the stepped notch edge 5b and the notch inner part 5a of the light guide plate 1 is almost directed.

When the backlight device (illuminating device) B of the liquid crystal display device E is energized through a lighting circuit device (not shown), the lamp L of the lamp L excites the phosphor film L4 due to the discharge between the discharge electrodes. Light is emitted from the entire circumference through the phosphor film L4. At this time, the semi-transparent reflection film L2 formation portion does not reflect and shield all the light, but a part of the light is transmitted and radiated, and the reflected light reflected by the reflection film L2 is radiated from the opening L3. To be done. Therefore,
Since the reflected light is emitted from the opening L3 so as to be superimposed on the direct light, a high intensity (amount) of light is emitted.

Since the opening L3 of the lamp L is substantially directed to and close to the light incident portion 11 between the notch edge 5a of the notch 5 of the light guide plate 1 and the notch depth 5b, The light intensity (amount) incident on the part is high. The light incident between the notch edge 5a and the notch back 5b of the light guide plate 1 is formed by the extension of the light guide plate 1 while being repeatedly reflected by the upper and lower surfaces 2 and the reflecting surface 6 of the light guide plate 1. Further, the thick portion 8 advances toward the thick portion 8 and a part thereof is radiated from the surface side forming the light emitting surface 2 and gradually attenuates and reaches the side surface 3 on the opposite surface side.

Further, the radiated light of relatively low intensity (amount) transmitted through the semi-transparent reflection film L2 forming portion of the bulb L1 is incident on the thin portion 4 of the light guide plate 1 and is transmitted through the thin portion 4 or After being repeatedly reflected on the upper and lower surface portions, the light is emitted from the upper and lower surfaces of the thin portion 4.

Backlight device (illumination device) of this configuration
Since B accommodates the lamp L in the light guide plate 1, the device B can be downsized for the lamp L. Further, in terms of light emission characteristics, light of high intensity (amount) is incident in the direction in which the light guide plate 1 which is separated from the lamp L extends to form the thick portion 8, and to the thin portion 4 near the lamp L. Since light of a relatively low intensity (amount) that does not transmit all light is made incident, the brightness of the entire light emitting surface 2 on the surface of the light guide plate 1 is high, and since no light is shielded at all, there is little difference in brightness and brightness. The uneven distribution can be reduced,
Uniform light emission can be achieved.

Since the liquid crystal display device E is provided with the light diffusion plate K facing the light emitting surface 2 of the light guide plate 1 of the backlight device (illumination device) B, the uneven brightness is further improved. Light can be incident on the liquid crystal panel P. Therefore, it is possible to provide the liquid crystal display device E having high brightness, high brightness, uniform brightness, and improved visibility.

In the reflection type fluorescent lamp L, a semitransparent reflection film L2 is formed on the inner surface of the bulb L1.
As shown in (a), the reflective film L2 may be formed on the outer surface of the bulb L1, and the same operation and effect as those of the above-described embodiment can be obtained. Further, as shown in FIG. 3B, the opening L3
The fluorescent lamp L of the aperture type in which the phosphor film L4 is not formed on the surface of the bulb L1 may be collectively referred to as a reflection type lamp in the present invention. This aperture-shaped fluorescent lamp L can obtain light emission with a higher light intensity (quantity) from the opening L3 as compared with the above-mentioned one in which the phosphor film L4 is formed in the opening L3 of the bulb L1.

4 and 5 are front sectional views showing another embodiment of a sidelight type backlight device (illumination device) B according to the present invention, in which the same parts as in FIGS. 1 to 3 are shown. The same reference numerals are given and the description thereof is omitted.

In this case, a concave groove-shaped cutout portion 5 is formed along the side surface 3 at the center of one side surface 3 of the light guide plate 1, and a straight tubular reflection type fluorescent lamp L is housed in the cutout portion 5. ing. Further, the light guide plate 1 has a taper shape in which the side on which the fluorescent lamp L is disposed is thick and the opposite side is thin, and the light emitting surface 2 is on the flat surface of the light guide plate 1 and the light is on the opposite surface. The reflective film 6 is formed.

The fluorescent lamp L is provided on the inner surface of the bulb L1 facing the light emitting surface 2 side of the thin portions 4 and 4 formed by forming the cutouts 5 and the opening of the cutouts 5.
A semi-transparent light reflecting film L2 similar to the above is formed. At this time, the opening angle θ of the opening L3 where the light reflection film L2 is not formed is about 140 degrees, and the light incident portion 11 of the concave groove portion 5 is formed.
Is directed in the direction of the thick portion 8 in the bottom direction and the radiation width and the bottom width are substantially the same.

When the fluorescent lamp L of the backlight device (illumination device) B is turned on, the semitransparent reflective film L
Part of the light is transmitted and radiated from the portion 2 formed, and the reflected light reflected by the reflective film L2 is radiated from the opening L3. Therefore, the reflected light is emitted from the opening L3 so as to be superimposed on the direct light, and the light emission is directed to the light incident portion 11 in the bottom direction of the cutout portion 5, so that the light guide plate 1 extends. Light with high intensity (amount) is emitted in the direction of the thick portion 8 formed by.

The light that has entered the light guide plate 1 from the bottom of the cutout 5 travels in the direction of the thick portion 8 while being repeatedly reflected by the front and back surfaces of the light guide plate 1 and the reflection surface 6, and a part of the light is passed through the front surface 2. It is emitted from and gradually attenuates and reaches the side surface 3 at the end. Further, the emitted light of relatively low intensity (amount) transmitted through the semi-transparent reflective film L2 forming portion of the bulb L1 is incident on the thin portions 4 and 4 of the light guide plate 1 and is transmitted as it is or repeatedly reflected on the surface portion. Then, it is radiated from the surface 2 of the thin portion 4.

Backlight device (illumination device) of this configuration
As for B, the device B can be miniaturized in the same manner as described above. Further, light of high intensity (amount) is incident in the direction in which the light guide plate 1 which is separated from the lamp L extends to form a thick portion, and the thin portion 4 near the lamp L receives all the light. Since the light of a relatively low intensity (amount) that has not been transmitted is made incident, that is, the directed light intensity (amount) is changed according to the thickness of the light guide plate 1, the light emitting surface 2 on the surface of the light guide plate 1 is changed. The brightness of the entire surface is high,
Since the light is not shielded at all, the difference in brightness is small, the unevenness of the luminance distribution can be reduced, the uniformity can be enhanced, and uniform light emission can be performed. Further, the light intensity (quantity) of the light emitting surface 2 of the light guide plate 1 decreases as the distance from the lamp L increases, but since the thickness of the light guide plate 1 is gradually reduced, the attenuation of the light from the lamp L can be covered.

Further, FIG. 5 is provided with a light guide plate 1 and a reflection type fluorescent lamp L similar to those in FIG. 4, but the light guide plate 1 is provided with a reflection surface 6 only on the upper side surface and both surfaces are light emitting surfaces 2. The illumination device B is suitable as a display device, etc.

That is, this illuminating device B has a fluorescent lamp L.
When the light is turned on, the opening L3 is formed in the same manner as the lighting device B described above.
The reflected light is emitted from the light superimposing on the direct light, and the light emission is directed to the light incident portion 11 in the bottom direction of the cutout portion 5, so that the high intensity (quantity) in the thick portion 8 direction of the light guide plate 1 is obtained. ) Is emitted.

The light entering the light guide plate 1 from the bottom of the notch 5 is repeatedly reflected by the front and back surfaces of the light guide plate 1, and a part of the light is radiated from both surfaces 2 and 2 and is gradually attenuated. Reach the side 3 of the end. Further, the emitted light of relatively low intensity (amount) transmitted through the semi-transparent reflective film L2 forming portion of the bulb L1 is incident on the thin portions 4 and 4 of the light guide plate 1 and is transmitted as it is or repeatedly reflected on the surface portion. After that thin part 4,4
Emitted almost equally from both surfaces 2, 2.

The illuminating device B having this structure has the same effects as those described above, and the brightness of the entire light emitting surfaces 2 and 2 on both the front and back sides of the light guide plate 1 is high, and the difference in brightness is small and the brightness distribution is uneven. It is possible to reduce the degree of uniformity and increase the uniformity, so that uniform light emission can be performed, and characters and figures can be displayed directly on the light emitting surface 2 on the surface of the light guide plate 1. It should be noted that a separate display plate may be superimposed on the light guide plate 1 for display. Further, in the case of the illuminating device B that emits light from both surfaces 2 and 2 of the light guide plate 1, by interposing a means such as a reflection sheet or a reflection plate that reflects or diffuses light in the center of the light guide plate 1 divided into two, the surface 2 The radiated light from can be made more uniform.

FIGS. 6 and 7 are a front sectional view (a) and a side view (b) of a center light type illumination device B showing another embodiment of the present invention, which are the same as FIGS. 1 to 5. The same reference numerals are given to the parts, and the description thereof will be omitted. In FIG. 6, the light guide plate 1 made of translucent acrylic resin is
The thickness is the same in the −Y direction, the central portion is thick in the XX direction, and becomes thinner toward the end, and the concave portion for accommodating the lamp L is formed in the central portion in the YY direction. A groove-shaped notch portion 5 and a thin portion 4 are formed.

A straight tubular reflection type fluorescent lamp L is housed in the recessed groove-shaped notch 5 of the light guide plate 1, and the lower surface and side surface 3 of the light guide plate 1 including the tapered portion of the lower surface of the light guide plate 1. …
A reflecting surface 6 such as a reflecting sheet is formed on the.
The cross-section of the reflective fluorescent lamp L is shown in FIG.
As shown in the enlarged view, translucent reflective films L2 and L2 are formed on the upper and lower surface portions of the bulb L1, and the remaining left and right surface portions are formed with the cutout edge 5b of the cutout portion 5 of the light guide plate 1. Openings L3 and L3 are formed so as to be directed to the interior of the notch 5a. Further, a phosphor film L4 is formed on the reflection films L2 and L2 and the openings L3 and L3 of the bulb L1.
(As described above, the reflective fluorescent lamp L has the opening L3,
It does not matter even if it is an aperture type in which the phosphor film L4 is not formed on L3. ) When the above fluorescent lamp L is turned on, a semitransparent reflective film L
Part of the light is transmitted and radiated from the portions where the L2 and L2 are formed, and the reflected light reflected by the reflective films L2 and L2 is radiated from the openings L3 and L3. Therefore, since the reflected light is emitted from the openings L3 and L3 so as to be superimposed on the direct light, the high-intensity (quantity) light is emitted in the direction of the thick portion 8 which is the extending direction of the light guide plate 1. It Since each opening L3 of the lamp L is directed substantially between the notch edge 5b of the notch 5 of the light guide plate 1 and the notch inner part 5a, and is close to each other, the intensity of the light incident on this portion. (Quantity) is high. The light incident between the cutout edge 5b and the cutout depth 5a of the light guide plate 1 is repeatedly reflected by the front and back surfaces and the reflection surface 6 of the light guide plate 1, and a part of the light is gradually emitted from the front surface 2. To reach the side surface 3 at the end.

A semitransparent reflective film L above the bulb L1
2 The radiated light of relatively low intensity (quantity) transmitted through the formation part is
The light enters the thin portion 4 of the light guide plate 1, is transmitted through the thin portion 4, is repeatedly reflected by the surface portion thereof, and then is emitted from the surface 2 of the thin portion 4.

Backlight device (illumination device) of this configuration
B is a high-intensity (quantity) light incident in the direction in which the light guide plate 1 which is separated from the lamp L extends to form a thick portion,
Further, the dimmed light having a relatively low intensity (amount) is made incident on the thin portion 4 near the lamp L, that is, the directed light intensity (amount) is changed according to the thickness of the light guide plate 1. The entire surface of the light-emitting surface 2 on the surface of the light guide plate 1 has a high brightness, the difference in brightness is small, the unevenness of the brightness distribution can be reduced, and the evenness can be increased to achieve uniform light emission. Further, the light intensity (amount) of the light emitting surface 2 of the light guide plate 1 decreases as the distance from the lamp L increases,
Since the wall thickness is gradually reduced, it is possible to cover the attenuation of the light from the lamp L.

Further, the light guide plate 1 of the backlight device (illumination device) B shown in FIG. 7 has substantially the same shape as that of FIG. 6, and a reflection surface 6 such as a reflection sheet is formed on the lower surface. A recessed groove-shaped notch 5 for accommodating the lamp L is formed in the central portion in the Y-Y direction on the light emitting surface 2 side. A straight reflective fluorescent lamp L is housed in the cutout 5. As shown in the cross section of the reflection type fluorescent lamp L, a semitransparent reflection film L2 is formed on the upper portion of the bulb L1 facing the opening of the cutout 5, and the remaining portion is the opening L3. Has become. That is, the lamp L
A light reflection film 6 is formed on a portion not surrounded by the light guide plate 1.

When the fluorescent lamp L is turned on, a part of the light is transmitted and emitted from the semitransparent reflective film L2 forming portion, and the reflective film of the lamp L is superposed on the direct light from the opening L3. Reflection sheet 6 that has passed through L2 and thin portion 4
Since the reflected light is emitted from, the high intensity (quantity) light emission is performed as in the embodiment of FIG. In addition, in the case of this embodiment, there is no special opening in the cutout portion 5 facing the light emitting surface 2, and the cutout portion 5 is open. But,
In this lamp L, a semitransparent reflection film L2 is formed in the upper portion facing the opening of the cutout 5, and the radiated light passing through this reflection film L2 formation portion is dimmed to a relatively low level. Strength (quantity).

Therefore, the bulb L1 at the center of the light guide plate 1
A high-luminance portion does not occur in a portion close to each other, and in this case as well, it is possible to reduce the luminance unevenness of the light-emitting surface 2 of the light guide plate 1 and obtain a uniform luminance distribution over almost the entire surface.

The ones shown in FIGS. 6 and 7 are as follows.
In addition to the backlight device B, it can be applied to ordinary lighting. Further, the lamps L incorporated in these backlight devices B are the same as those shown in FIG.
Moreover, it does not matter if the device shown in FIG. 7 is applied to the device shown in FIG.

FIG. 8 and FIG. 9 are side cross-sectional views showing an enlarged main part of an illuminating device B showing another embodiment of the present invention, and the same parts as those in FIGS. Is attached and the description thereof is omitted. What is shown in these figures is that, between the opening L3 of the lamp L and the light incident portion 11 of the light guide plate 1 facing the opening L3, along the lamp L axis, the cross section has a thick central portion. The long convex lens 9 which is thinned toward the end is provided.

In FIG. 8, the convex lens 9 has a gap of at least about 1 mm between the bulb 1 portion of the lamp L and the light incident portion 11 of the light guide plate 1. In addition, as shown in FIG. 9, the convex lens 9 is in close contact with the light incident portion 11 of the light guide plate 1.

In this way, when the elongated convex lens 9 is arranged toward the light incident portion 11 of the light guide plate 1, the radiant light traveling from the opening L3 of the lamp L toward the light guide plate 1 is deflected through the convex lens 9 and guided. It is introduced into the light incident part 11 of the light plate 1. In this way, by using the convex lens 9 to allow light to enter within a desired range, the light guide plate 1
The light is refracted inside, and almost uniform light emission can be achieved from the entire light emitting surface 2.

Further, as shown in FIG. 9, when the convex lens 9 is fitted into the light incident portion 11 of the light guide plate 1 to be in close contact with and integrated with each other, there is no gap between the convex lens 9 and the light guide plate 1 and they are adjacent to each other. Therefore, the loss of the incident light on the light guide plate 1 is small, and the brightness of the light emitting surface 2 can be improved.

In these cases, if the distance between the convex lens 9 and the bulb 1 portion of the lamp L and the distance between the convex lens 9 and the light incident portion 11 of the light guide plate 1 are wide, the light loss upon incidence becomes large. Therefore, the maximum approach distance is about 1
It is preferable that the distance is less than or equal to mm (the convex lens 9 prevents the same distance over the entire surface).

The present invention is not limited to the above embodiment. For example, one light guide plate is not limited to one lamp, but in the case of a side light type as shown in FIG. 10, the notch 5, formed on the opposite side surfaces 3, 3 of the light guide plate 1. The lamps L and L are respectively arranged in 5 (if the shape of the light guide plate is a polygon such as a quadrangle, the lamps may be arranged on each side). A plurality of lamps may be arranged to be separated from each other. The shape of the light guide plate is not limited to the rectangular shape or the rectangular shape, and may be a circular shape or the like.

Further, the shape of the notch formed in the light guide plate is preferably such that the gap with the bulb portion of the lamp is small and the two are accommodated closely. 1
As shown in 0, it may be a curved shape such as a U-shape that matches the outer shape of the lamp L.

Further, the lamp is not limited to a fluorescent lamp, and may be a discharge lamp using rare gas emission or a tube-shaped incandescent light bulb of filament light emission in consideration of the heat resistance of the light guide plate. The shape may be a letter shape, a ring shape, a semicircular shape, or the like, in short, as long as the bulb is housed in the notch formed on the side surface of the light guide plate.

The semi-transparent light reflecting film formed on the surface of the bulb of the lamp is not limited to titanium oxide or aluminum oxide, but may be a white film such as a phosphor or a metal thin film such as aluminum or silver. Good. Further, the formation angle range of the light reflection film (as viewed from the cross-sectional direction of the bulb L1) depends on the relationship with the light incident portion 11 of the light guide plate 1, but is about 180 to 3.
00 degrees (about 60-180 degrees for the openings) were preferred.

The light reflecting surface formed on the light guide plate side is formed by applying or sticking a reflecting material on the surface of the light guide plate, and in addition to the sawtooth shape 6a, the dot shape, the conical shape or the like on the surface as shown in FIG. Providing an uneven light diffusing means, this light diffusing means is also formed by changing the roughness in the vicinity of the lamp and the distant portion, or as a separate body made of synthetic resin or a metal plate in the vicinity of the light guide plate. You may provide a reflector etc.

Further, the light diffusing plate is not essential, and when it is provided, it may be formed by directly engraving it on the surface of the light guiding plate, or by mixing particles in the light guiding plate, or by a separate member. It doesn't matter.

Further, the use as a lighting device is a television,
It can be applied to various things such as a backlight device of a liquid crystal display device such as an office automation equipment, a display such as an advertisement or a guide light, and general lighting.

[0076]

EXAMPLES For example, the following results were obtained in the backlight device B having the structure shown in FIG.

Light guide plate material Transparent acrylic resin (visible light transmittance 92%) Length × width 210 mm × 160 mm Maximum thickness (center portion) 4.0 mm Minimum thickness (side surface portion) 2.0 mm Notch depth 3. 0mm Notch width 3.0mm Thin thickness 1.0mm Reflective fluorescent lamp (Rated 2W) Bulb length 224mm Bulb outer diameter 2.6mm Visible light transmittance of light reflection film 10% Light reflection film formation angle (× 2) 120 degrees each, opening angle (× 2) 60 degrees each With the above configuration, the luminance uniformity (minimum luminance / maximum luminance) of the entire light emitting surface 2 of the light guide plate 1 becomes about 80%, which is a normal value. It was confirmed that the target level of 75% was improved by about 6.5%. (The brightness uniformity of the entire light emitting surface of the light guide plate using the conventional fluorescent lamp is about 50%.)

[0078]

According to the first to fourth aspects of the present invention, since the lamp is housed in the light guide plate, it is possible to reduce the size of the illumination device such as a backlight device for almost the lamp. In terms of light emission characteristics, the lamp and the light guide plate are close to each other and the brightness of the entire light emitting surface of the light guide plate surface is high. Moreover, since no light is shielded at all, there is little difference in brightness and brightness, and unevenness in the brightness distribution can be reduced, improving uniformity. As a result, uniform light emission can be achieved.

According to the structure of claim 5 of the present invention, since both surfaces emit light, it is applied to general lighting, display such as a display, guide light, etc. The effect of claim 4 is achieved.

According to the structure of claim 6 of the present invention, the lamp and the light guide plate are close to each other in terms of light emission characteristics, the brightness of the entire light emitting surface of the surface of the light guide plate is high, and the light is completely shielded. Since there is no brightness difference, uneven brightness distribution can be reduced, uniformity can be improved, and uniform light emission can be achieved.

Further, according to the seventh and eighth aspects of the present invention, since the incident light can be directed in a predetermined direction by the lens, the brightness of the entire light emitting surface of the light guide plate surface can be increased and the brightness distribution can be improved. It is possible to reduce unevenness in the light emission and improve the uniformity.

According to the ninth aspect of the present invention, the effects of the first to eighth aspects can be obtained by applying to a display such as a display or a guide light.

Further, according to the structure of the tenth aspect of the present invention, it can be manufactured in the same manner as an ordinary reflection type lamp.

Further, according to the eleventh aspect of the present invention, it is possible to further improve the brightness unevenness and obtain a clear image or display. Therefore, it is possible to provide a liquid crystal display device having high brightness and improved visibility with no uneven brightness.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a liquid crystal display device of the present invention.

FIG. 2 is a partially enlarged side sectional view showing an embodiment of a sidelight type backlight device (illumination device) in FIG.

3A to 3C are enlarged cross-sectional views showing a reflective fluorescent lamp used in the lighting device of the present invention.

FIG. 4 is a side sectional view showing another embodiment of a lighting device according to the present invention.

FIG. 5 is a side sectional view showing another embodiment of the lighting device according to the present invention.

6A and 6B show another embodiment of the illumination device according to the present invention, FIG. 6A is a side sectional view, and FIG. 6B is a front view.

7A and 7B show another embodiment of the lighting device according to the present invention, FIG. 7A is a side sectional view, and FIG. 7B is a front view.

FIG. 8 is a side sectional view showing another embodiment of the lighting device according to the present invention.

FIG. 9 is a side sectional view showing another embodiment of the lighting device according to the present invention.

FIG. 10 is a side sectional view showing another embodiment of the lighting device according to the present invention.

[Explanation of symbols]

 B: Lighting device (backlight device) 1: Light guide plate 2: Light emitting surface (front surface) 3: Side surface 4: Thin portion 5: Notch portion 6: Light reflecting surface 7: Thick portion 9: Convex lens L: Reflective lamp ( Reflective fluorescent lamp) L1: Bulb L2: Light reflection film L3: Opening part L4: Phosphor film E: Liquid crystal display device P: Liquid crystal panel K: Light diffusion plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jun Yajima 4-3-1, Higashishinagawa, Shinagawa-ku, Tokyo Inside Toshiba Lighting & Technology Corporation

Claims (11)

[Claims] 1. A plate-shaped light guide plate having a light emitting surface on at least one surface; a cutout portion formed on a side surface of the light guide plate; a valve portion housed in the cutout portion; and a thin wall portion formed by the cutout portion. A reflection type lamp in which a semi-transparent light reflecting surface is formed in a portion facing the light emitting surface and a portion not surrounded by the light guide plate, and an opening having no light reflecting surface is arranged in the extending direction of the light guide plate. A lighting device comprising: 2. The lighting device according to claim 1, wherein the notch is formed in a groove shape along the center of the side surface of the light guide plate. 3. The lighting device according to claim 1, wherein the cutout portion is formed in a step shape along a side surface corner portion of the light guide plate. 4. A light emitting surface is formed on a flat surface side connected to a thin portion formed by forming a cutout portion of the light guide plate, and a light reflecting surface is formed on the opposite surface side. The lighting device according to claim 3. 5. The lighting device according to claim 1, wherein the light guide plate has light emitting surfaces formed on both sides thereof. 6. A plate-shaped light guide plate having a light emitting surface on one surface and a light reflecting surface on the other surface; a notch formed in an intermediate portion of the light guide plate on the light emitting surface side or the light reflecting surface side; A bulb portion is housed inside the portion, and a semi-transparent light reflecting surface is formed in a portion facing the light emitting surface of the thin portion formed by the notch and a portion not surrounded by the light guide plate, and an opening portion having no light reflecting surface is formed. An illumination device, comprising: a reflection type lamp disposed in the extending direction of the light guide plate. 7. A convex lens is arranged between an opening portion having no light reflecting surface of the reflection type lamp and a light incident portion of the light guide plate, according to any one of claims 1 to 6. Lighting equipment. 8. The illumination device according to claim 7, wherein the convex lens and the light guide plate are integrated. 9. The lighting device according to claim 1, wherein a display plate is provided on the light emitting surface side of the light guide plate. 10. The light reflecting surface of the reflective lamp transmits a part of visible light.
The lighting device according to any one of 1. 11. The lighting device according to claim 1, a light diffuser provided on a light-emitting surface side of a light guide plate of the lighting device, and the light diffuser facing the light diffuser. And a liquid crystal panel provided thereon.