JPH09211451A - Backlight device and liquid crystal display device using the same, liquid crystal tv and viewfinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a backlight device capable of emitting light with a high directivity and, therefore, increasing a transmission light quantity of a liquid crystal display panel when the device is used for a liquid crystal display device, etc. SOLUTION: Plural column-shaped light guiding areas 6 (for example, an area having a higher refractive index than a cavity and the light transmission plate 2) are formed in the light transmission plate 2 facing in the direction perpendicular to a light-emitting surface of the light transmission plate 2, and the upper face of the light transmission plate 2 is covered except the position where the light guiding area 6 is formed. Also, plural lenses 9a are arranged on the upper surface of the light transmission plate 2 corresponding to opening parts of the light guiding areas 6. The light guided into the light transmission plate 2 is reflected repeatedly in the light transmission plate 2 until it reaches the light guiding area 6, and the light made incident on the light guiding area 6 exits from the openings part of the light guiding area 6 as a spot light source, and is further collimated to be approximately parallel through the lenses 9a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight device, a liquid crystal display device, a liquid crystal television and a viewfinder using the device.

[0002]

2. Description of the Related Art FIG. 1 is an exploded perspective view showing a conventional backlight device 101 used together with a liquid crystal display panel. In this backlight device 101, a diffusion layer 103 is formed in a pattern on the lower surface of a light guide plate 102 made of a transparent material having a large refractive index.
A fluorescent tube (cold-cathode tube) 104 is arranged on the side end surface of the light guide plate, a reflection sheet 105 is arranged from the outer peripheral portion of the fluorescent tube 104 to the lower surface of the light guide plate 102, and a diffusion plate 106 and a prism are formed on the upper surface of the light guide plate 102. Sheets 107 are stacked. The diffusing layer 103 is for diffusing and reflecting light to reduce the uneven brightness and directivity of the backlight device 101. The diffusing layer 103 has dots printed on the lower surface of the light guide plate 102, or has a surface formed by cutting or etching. Some are processed, and the pattern changes depending on the distance from the fluorescent tube 104. The prism sheet 107 is generally formed by arranging a plurality of prisms each having an isosceles or isosceles triangular cross section in parallel.

Thus, the light emitted from the fluorescent tube 104 enters the inside of the light guide plate 102 from the side end surface. The light guided into the light guide plate 102 is confined inside the light guide plate 102, and the upper surface (light emission surface) and the lower surface (diffusion layer 103) of the light guide plate 102.
While repeating reflection by the reflection sheet 105), when the incident angle to the light emitting surface becomes smaller than the critical angle of total reflection, the light is emitted from the light emitting surface. The light emitted from the light emitting surface of the light guide plate 102 passes through the diffusion plate 106 and is emitted as uniformly diffused light (Lambertian light).

The light emitted from the diffusion plate 106 passes through the prism inclined surface of the prism sheet 107 as shown by the solid line 108 in FIG.
The light is refracted in the direction close to the normal line and is condensed. Further, the light totally reflected by the prism slopes (indicated by the one-dot chain line 109 in FIG. 2) is reflected by the adjacent prism slopes and diffused by the diffusion plate 106.
The light returning to the side, refracted by the prism slope and emitted in the horizontal direction (indicated by a chain double-dashed line 110 in FIG. 2) enters the prism sheet 107 from the adjacent prism slope and is totally reflected by the opposite prism slope. Then, the light returns to the diffuser plate 106 side, and both are reflected by the diffuser plate 106 to enter the prism sheet 107 again. As a result, the light that has entered the prism sheet 107 from the diffusion plate 106 is condensed and becomes narrow diffused light of about ± 40 °, and the prism sheet 10
It is emitted from 7.

The light emitted from the backlight device 101 in this way passes through the pixel openings of the liquid crystal display panel (not shown) arranged in front of the backlight device 101 and is generated by the liquid crystal display panel. Send the image forward.

[0006]

In the viewfinder of a video camera among liquid crystal display devices, it is required to increase the front luminance in order to improve the visibility. For this reason, in the conventional backlight device, the light emitted from the light guide plate is efficiently condensed forward by the prism sheet as described above, thereby providing directivity and reducing light leaking in the lateral direction. However, the front brightness of the backlight device is improved.

On the other hand, in a liquid crystal display device used in a liquid crystal television or the like, since a plurality of people watch images, it is required to widen the viewing angle of the liquid crystal display device. Even a conventional liquid crystal display device has a vertical viewing angle of 35 ° and a horizontal viewing angle of about 45 to 60 °, but there is a demand to expand this viewing angle to a viewing angle of about CRT (CRT).

However, there is a trade-off between increasing the front brightness of the liquid crystal display device to make it easier to see from the front and making the viewing angle wider to make it easier to see from an oblique direction. When the front brightness of the emitted light is increased, the viewing angle of the liquid crystal display device is narrowed.

Further, the viewing angle of light can be widened by scattering the light after passing through the liquid crystal display panel by using a diffusion sheet or the like. However, as in the conventional backlight device, a light source of random light quality is used. However, since it is difficult to increase the absolute transmitted light amount, there is a problem that the contrast of an image is significantly deteriorated when the light after passing is scattered.

The present invention has been made in view of the drawbacks of the above-mentioned conventional examples, and an object of the present invention is to emit light with high directivity, and therefore, the present invention was used in a liquid crystal display device or the like. In some cases, it is to provide a backlight device capable of increasing the amount of transmitted light of a liquid crystal display panel.

[0011]

DISCLOSURE OF THE INVENTION The backlight device according to claim 1 is
In a backlight device in which light generated by a light source is guided to the inside of the light guide plate, and the light inside the light guide plate is emitted to the outside from the light emission surface of the light guide plate, the light inside the light guide plate is captured and the light is emitted from the light emission surface. It is characterized in that a plurality of light guide regions for emitting light are provided dispersed inside the light guide plate.

In the backlight device of the present invention, since a plurality of light guide regions for catching the light inside the light guide plate and emitting it from the light emitting surface of the light guide plate are provided dispersedly in the light guide plate, The light emitted from the light source and incident on the light guide plate is captured in the light guide region inside the light guide plate, is transmitted through the light guide region, and is emitted to the outside from the end (light emission surface) of the light guide region. As a result, the light inside the light guide plate is not emitted from the entire light emission surface of the light guide plate, but is emitted to the outside mainly as spot-like light aligned with the portion where the light guide region is formed. Therefore, according to the present invention, the surface light source can be made into a point light source.

According to a second aspect of the present invention, in the backlight device according to the first aspect, the light guide region is a plurality of columnar regions having one end connected to the light emitting surface of the light guide plate. It has a feature.

By making the light guide region a columnar region, light can be captured by the thin columnar region and emitted as a thin light beam from the light guide plate.

According to a third aspect of the present invention, in the backlight device according to the second aspect, the light guide region is formed of a material having a refractive index higher than that of the light guide plate.

By forming the light guide region with a material having a refractive index higher than that of the light guide plate, the light incident from one end of the light guide region is totally reflected in the light guide region and is confined in the light guide region while the other end is contained. Can be transmitted to the outside through the other end of the light guide region.

According to a fourth aspect of the present invention, in the backlight device according to the second aspect, the light guide region has an outer peripheral surface formed of a light reflection layer.

By forming the outer peripheral surface of the light guide region by the light reflecting layer, the light incident from one end of the light guide region is reflected in the light guide region and propagates to the other end, and from the other end of the light guide region. It can be emitted to the outside.

According to a fifth aspect of the present invention, in the backlight device according to the second aspect, the light guide region is longer as it is provided at a position distant from the light source. .

At a position away from the light source, the intensity of light incident on the light guide region decreases. Therefore, if the light guide region is lengthened to increase the surface area for allowing light to enter the light guide plate, the intensity of light emitted from the light guide region can be made uniform throughout the light guide plate.

According to a sixth aspect of the present invention, in the backlight device according to the second aspect, the light guide region has a tapered shape.

By forming the light guide region in a tapered shape, it becomes easier to capture light from the light guide plate to the light guide region, and the intensity of light emitted from the light guide region can be increased.

According to a seventh aspect of the present invention, in the backlight device according to the second aspect, the end surface of the light guide region is inclined with respect to a plane perpendicular to the axis of the light guide region. Is characterized by.

According to an eighth aspect of the present invention, in the backlight device according to the second aspect, the light guide region of the light guide plate is arranged so that the inner end thereof approaches in the direction of the light source located closest to the light guide region. It is characterized in that it is inclined with respect to the direction perpendicular to the light emitting surface.

By inclining the light guide region or the end face of the light guide region, the light in the light guide plate can be easily incident on the light guide region, and the intensity of light emitted from the backlight device can be increased.

According to a ninth aspect of the present invention, in the backlight device according to the second aspect, a lens is arranged corresponding to each end face of the light guide region facing the light emission surface. There is.

When a lens is arranged on the end surface of the light guide area, the light emitted from the light guide area is collimated into parallel collimated light by the lens or is condensed.

The backlight device according to claim 10 is
In a backlight device in which light generated by a light source is guided to the inside of the light guide plate and the light inside the light guide plate is emitted to the outside from the light emission surface of the light guide plate, a plurality of light reflection surfaces are formed on the surface of the light guide plate. The transparent windows are opened, and lenses are arranged corresponding to the respective transparent windows.

In this backlight device, since the light is reflected by the light reflecting surface except the light-transmitting window on the surface of the light guide plate, the light is emitted only from the light-transmitting window, and the light emitted from the light-transmitting window is reflected by the lens. The collimated lights are aligned or condensed into substantially parallel light.

An eleventh aspect of the liquid crystal display device is provided with the backlight device of the first or tenth aspect and a liquid crystal display panel for displaying an image.

A liquid crystal television set forth in claim 12 is characterized by including the backlight device set forth in claim 1 or 10, a liquid crystal display panel for displaying an image, and an image receiving circuit.

The viewfinder according to claim 13 is
A backlight device according to claim 1 or 10, a liquid crystal display panel for displaying an image, and an eyepiece lens.

In the liquid crystal display device, the liquid crystal television, the viewfinder, etc., the uniform light emitted from the backlight device according to the present invention can be incident on the liquid crystal display panel, so that the absolute light in the liquid crystal display device can be obtained. The amount of transmitted light can be increased. Therefore, the front luminance can be increased according to the application, or the viewing angle can be widened without reducing the contrast by diffusing the light that has passed through the liquid crystal display panel.

BEST MODE FOR CARRYING OUT THE INVENTION

(Backlight Device) FIG. 3 is a sectional view showing an edge light type backlight device 1 according to an embodiment of the present invention. The light guide plate 2 is formed in a plate shape by a transparent material (for example, acrylic resin) having a high refractive index (n ₁ > 1), and the back surface reflection layer 3 is formed on the lower surface of the light guide plate 2. The back reflection layer 3 is formed by dot-printing a diffusive paint on the lower surface of the light guide plate 2, roughened the surface by machining, etching, or the like, and is diffused and reflected by wedge-shaped irregularities. Fluorescent tubes (cold cathode tubes) 4 are arranged on both end surfaces of the light guide plate 2,
A reflection sheet 5 is provided from the outer peripheral portion of the fluorescent tube 4 to the lower surface of the light guide plate 2 (the back reflection layer 3 may be formed by a specular reflection layer having a reflectance different from that of the reflection sheet 5). Further, a plurality of columnar light guide regions 6 are vertically formed from the upper surface of the light guide plate 2 to the inside of the light guide plate 2. A light reflecting surface (mirror surface) 7 is formed on the upper surface (light emitting surface) of the light guide plate 2, and the light guiding area 6 is formed on the light reflecting surface 7.
The translucent window 8 opens in a fixed pattern so as to face the upper end surface of the. Further, on the upper surface of the light guide plate 2, a lens array 9 including a plurality of lenses 9 a arranged corresponding to the upper end of the light guide region 6 is provided. Although not shown,
A reflection sheet is provided on the side end surface of the light guide plate 2 where the fluorescent tube 4 is not provided.

The light guide region 6 has a refractive index n in this embodiment.
= 1, an air layer, that is, a cavity, and is formed perpendicular to the upper surface of the light guide plate 2. Furthermore, the fluorescent tube 4
The light guide area 6 in the center farthest from is the deepest,
The light guide region 6 is formed to be gradually shallower as it approaches the fluorescent tube 4. However, in the direction perpendicular to the paper surface of FIG. 3, the light guide regions 6 have the same depth. The light guide region 6 may be formed when the light guide plate 2 is formed, or may be formed by machining after the light guide plate 2 is formed.

Then, the light R emitted from the fluorescent tube 4
As shown in FIG. 3, the light enters the inside of the light guide plate 2 from the side end face thereof, and the lower surface of the light guide plate 2 (the back reflection layer 3 and the reflection sheet 5).
And, the reflection is repeated on the upper surface (light reflecting surface 7). The light R inside the light guide plate 2 is repeatedly reflected inside the light guide plate 2 until it enters the light guide region 6, and the light R entering the light guide region 6 from the outer peripheral surface and the lower surface of the light guide region 6 is shown in FIG. In this way, the light is emitted from the opening (light transmitting window 8) of the light guide region 6. Light incident on the surface of the upper surface of the light guide plate 2 on which the light reflection surface 7 is formed is reflected by the light reflection surface 7, and therefore, from the upper surface of the light guide plate 2 only through the translucent window 8 having the light guide region 6. Spot-shaped light is emitted and made into a point light source. Here, if the focus of each lens 9a forming the lens array 9 is substantially coincident with the upper end of the corresponding light guide region 6, the light R emitted from the light guide region 6 is obtained.
Is collimated light that is substantially parallel and is emitted upward as shown in FIG.

Further, although the light intensity becomes weaker in the central portion of the light guide plate 2 which is distant from the fluorescent tube 4, the light guide region 6 is gradually deepened toward the central portion of the light guide plate 2 to provide a surface area for capturing light. Since it is made large, the brightness in the opening of each light guide region 6 is uniform. That is, the depth of each light guide region 6 is adjusted so that the brightness in the opening of each light guide region 6 becomes uniform.

In the embodiment shown in FIG. 3, the two-lamp type backlight device 1 having the fluorescent tubes 4 at both ends is shown, but the one-lamp type backlight device 1 and the L-shaped fluorescent tube 4 and the like. A U-shaped fluorescent tube 4 may be used. Even in these cases, the depth of each light guide region 6 is adjusted so that the brightness in the opening of each light guide region 6 is uniform (for example, in the case of a one-lamp type, the depth of each light guide region 6 is closer to the fluorescent tube 4). The light guide region 6 at the end is the shallowest, and the light guide region 6 at the end farthest from the fluorescent tube 4 is the deepest).

Further, in the back surface reflection layer 3 formed on the lower surface of the light guide plate 2, the light R emitted from the fluorescent tube 4 is guided.
Among them, the efficiency of incidence on the light guide region 6 is maximized,
The emission brightness distribution is adjusted so that the brightness at the opening of the is maximized. For example, as shown in FIG. 6, it is conceivable to arrange the back reflection layer 3 so that the light guide region 6 is located in the direction of the maximum intensity of the light reflected by the back reflection layer 3.

FIG. 7 and FIG. 8 respectively show the relation between the emission angle and the relative intensity of the light emitted from the left fluorescent tube 4 and reflected by the back surface reflection layer 3 of the light guide plate 2 and emitted to the light guide region 6. 10
And the rear surface reflection layer 3 of the light guide plate 2 emitted from the right fluorescent tube 4.
The relation 11 between the emission angle and the relative intensity of the light reflected by and emitted to the light guide region 6 is shown. In the center of the light guide plate 2,
As shown in FIG. 7, since the intensity of light from the left fluorescent tube 4 and the intensity of light from the right fluorescent tube 4 are equal, the synthesis of the two light intensities is emitted as shown by the broken line 12 in FIG. The angle becomes maximum in the direction of 0 °. Therefore, in the center of the light guide plate 2, the back surface reflection layer 3 may be arranged directly below the light guide region 6. On the other hand, in the left side area of the light guide plate 2, as shown in FIG. 8, the intensity of light from the left fluorescent tube 4 becomes larger than the intensity of light from the right fluorescent tube 4, so that two light intensities are obtained. The maximum is the maximum of the angles of radiating in the upper right direction as shown by the broken line 13 in FIG. Therefore, in the left side area of the light guide plate 2, the back surface reflection layer 3 is formed.
As shown in FIG. 6, the light guide region 6 may be shifted to the left of the light guide region 6 so that the light guide region 6 is located in the direction extending from the back surface reflection layer 3 to the maximum emission angle direction. Similarly, the light guide plate 2
In the right side region of the above, it may be arranged symmetrically with this.

(Liquid Crystal Display Device) FIG. 9 is a schematic sectional view showing a liquid crystal display device 15 constructed by disposing a liquid crystal display panel 14 above the backlight device 1 of the above. The liquid crystal display device 15 is configured by disposing a liquid crystal display panel 14 on the front surface of the backlight device 1 and providing an optical low-pass filter 16 in front of the liquid crystal display panel 14. Further, a front surface of the optical low-pass filter 16 is used for a purpose. Accordingly, the diffusion plate 17 is arranged.

In the liquid crystal display panel 14, for example, liquid crystal is sealed between glass plates 18 on which drive circuits such as TFTs (thin film transistors) and transparent electrodes are formed, and polarizing plates 19 are placed outside the upper and lower glass plates 18. The wiring part 21
The pixel opening 20 is formed by the opening.

The optical low-pass filter 16 has a diffraction grating pattern formed on the surface thereof to make the wiring portion (black matrix) 21 of the liquid crystal display panel 14 inconspicuous.

Here, the center of the opening of the light guide region 6 of the backlight device 1, the center of the lens 9a, and the center of the pixel opening 20 of the liquid crystal display panel 14 are designed to coincide on the same axis. It is arranged.

In the backlight device 1 of the present invention, however, the light R emitted from the opening of the light guide region 6 is converted into substantially parallel collimated light by the lens 9a. The light R emitted from the light guide region 6 of No. 1 becomes collimated light and becomes the pixel opening 20 of the liquid crystal display panel 14.
And a large amount of transmitted light can be obtained.

In particular, as shown in FIG. 10, when the collimated light after passing through the lens 9a is thinner than the size of the pixel opening 20 of the liquid crystal display panel 14,
Light is not blocked by the wiring portion 21 of the liquid crystal display panel 14, and a large amount of transmitted light can be obtained.

Further, as shown in FIG. 11, the light emitted from the light guide region 6 is passed through the lens 9a to the liquid crystal display panel 14.
High transmission efficiency can be achieved even if the light is focused on the pixel opening 20 of FIG. Further, when the collimated light formed by the lens 9a has a larger spread than the pixel opening 20, another condenser lens array may be inserted between the backlight device 1 and the liquid crystal display panel 14. . However, as shown in FIG. 10, the liquid crystal display panel 1 is better if the collimated light is transmitted through the pixel openings 20.
Since the spread of light after passing four times is small, the configuration as shown in FIG. 10 is preferable for the purpose of increasing the front luminance.

Further, by disposing the diffusion plate 17 on the front surface of the optical low-pass filter 16, it is possible to scatter light having high front luminance, so that the liquid crystal display device 15 can have a wide viewing angle without lowering the contrast. Can be achieved.

(Constitution of Lens Array) The lens shape and the arrangement pattern of the lens array 9 formed on the upper surface of the light guide plate 2 are designed according to the arrangement pattern of the light guide region 6. For example, the light guide area 6 is the liquid crystal display panel 1.
When the delta arrangement is formed as shown in FIG. 12 in accordance with the delta arrangement of the 4 pixels, the lens array 9 has a structure in which hexagonal cut spherical lenses are arranged. When the light guide region 6 has a rectangular arrangement as shown in FIG. 13 in accordance with the rectangular arrangement of the pixels of the liquid crystal display panel 14,
The lens array 9 also has a structure in which rectangular cut spherical lenses are arranged.

Further, FIGS. 14 and 15 are a plan view and a sectional view showing the structure of still another lens array 9. If the aperture pitch of the light guide region 6 is narrowed to increase the light quantity, the pitch between the lenses 9a is correspondingly narrowed, and if the aperture diameter of the light guide region 6 is increased, the lens diameter becomes large, which conflicts with each other. Need to meet demand. In such a case, as shown in FIGS. 14 and 15, it is advisable to dispose on the light guide plate 2 a lens array 9 having a laminated structure having a structure in which two single-layer lens arrays are shifted and overlapped.

(Various Embodiments of Backlight Device) FIG. 16 is a view showing another shape of the light guide region 6, in which each light guide region 6 is formed in a tapered shape having a large inner diameter on the opening side. . When the taper shape that widens on the opening side is formed in this way, upward light is less likely to be totally reflected at the boundary between the light guide plate 2 and the outer peripheral surface of the light guide region 6, so that the light is guided. It becomes easier for the light to enter the inside, so that the light converging property can be improved and the brightness at the opening of the light guide region 6 can be increased.

FIG. 17 is a diagram showing still another structure of the light guide region 6, in which the inside of the light guide region 6 has a refractive index n of the light guide plate 2.
It is filled with a material 22 having a refractive index higher than ₁ (the refractive index is n ₂ ). Since the light guide region 6 has a higher refractive index than that of the light guide plate 2, the light incident on the light guide region 6 from the lower surface of the light guide region 6 will not be reflected at the boundary between the light guide region 6 and the light guide plate 2. The light propagates inside the light guide region 6 while repeating total reflection, and is emitted from the upper surface thereof. In addition, it is possible to reduce the total reflection on the outer peripheral surface of the light guide region 6 and improve the light condensing characteristics. Note that, as shown in FIG. 18, a coating layer 23 made of a high refractive index material may be formed only on the outer peripheral surface of the light guide region 6 made of an air layer (cavity).

FIG. 19 is a view showing still another structure of the light guide region 6, in which the light reflection layer 24 is formed on the outer peripheral surface of the light guide region 6. The light that has entered the light guide region 6 from the lower surface of the light guide region 6 propagates inside the light guide region 6 while being repeatedly reflected by the light reflection layer 24, and exits from the upper face thereof.

As described with reference to FIGS. 7 and 8, in the case of, for example, a two-lamp type, the right half of the light guide plate 2 has the light guide plate 2 at the right half.
The intensity of light reflected from the lower surface of the light guide plate 2 toward the upper left increases, and the intensity of light reflected from the lower surface of the light guide plate 2 toward the upper right light increases in the left half of the light guide plate 2. Therefore, FIG.
21, the lower surface 25 of the light guide region 6 is formed obliquely so as to be substantially perpendicular to the incident direction of the light of high intensity, or as shown in FIG. By inclining the light guide region 6 so that the lower end of the light guide region 6 approaches the near side of the fluorescent tube 4,
The brightness in the opening of the light guide region 6 can be increased.

FIG. 22 is a sectional view of a backlight device 1 according to another embodiment of the present invention. In this backlight device 1, the light guide area 2 is not provided in the light guide plate 2. The light emitted from the fluorescent tube 4 enters the light guide plate 2, is repeatedly reflected inside the light guide plate 2 and is emitted from the transparent window 8 of the light reflection surface 7, and each lens 9 of the lens array 9 is reflected.
The collimated light is almost parallel with a.

(Liquid Crystal Television) FIG. 23 is a schematic perspective view showing a liquid crystal television 26 according to the present invention, and FIG. 24 is a schematic sectional view showing the structure of its display portion. The liquid crystal television 26 has a liquid crystal display device serving as a display portion and an image receiving circuit (not shown) built therein, and has a receiving antenna 27 on its upper surface.

The liquid crystal television 26, as shown in FIG.
The backlight device 1 of the present invention is inserted into the holder 28, the spacer 29 is housed in the holder 28 from the above, and the liquid crystal display panel 14, the optical low-pass filter 16 and the diffusion plate 17 are inserted into the spacer 29. Then, the holder cover 32 having the display window 31 on the opening side of the holder 28 is covered via the cushion material 30 and the locking claw 33 of the holder cover 32 is fitted into the locking groove 34 of the holder 28. , Holder 28 and holder cover 32
The backlight device 1, the liquid crystal display panel 14, the optical low-pass filter 16 and the diffuser plate 17 are held between and.

Thus, the light emitted from the backlight device 1 is transmitted through the liquid crystal display panel 14 and displayed as a moving image, and the observer can see the image through the optical low pass filter 16 and the diffusion plate 17. In the liquid crystal television 26, since the light having the high transmitted light amount that has passed through the liquid crystal display panel 14 is scattered by the diffusion plate 17, it is possible to widen the viewing angle without lowering the contrast of the image.

(Liquid Crystal Viewfinder) FIG. 25 is a sectional view showing a liquid crystal viewfinder 35 according to the present invention.
The cushion material 37 is inserted into the cylindrical holder 36, the spacer 38 accommodating the optical low-pass filter 16 and the liquid crystal display panel 14 is then inserted, and then the backlight device 1 is inserted into the holder 36, The bottom lid 39 is covered from the back surface of the light device 1, and the bottom lid 39 is engaged with the holder 36 by the snap fit 40. In addition, the cylindrical lens barrel portion 4 holding the eyepiece lens 41
The end of 2 is put on the holder 36, and the locking claw 4 of the lens barrel 42 is
3 is engaged with the locking groove 44 of the holder 36.

Then, this liquid crystal viewfinder 35
In, because a large amount of transmitted light can be obtained,
An image with large front luminance can be obtained.

[0060]

According to the backlight device of the present invention, since the light guided to the inside of the light guide plate can be emitted from the light guide region, the opening of the light guide region can be made into a high brightness point light source. Therefore, the surface light source type backlight device can be made into a point light source.

Further, by arranging the lens corresponding to the light guide region, the light emitted from the light guide region can be emitted as collimated light whose emission directions are aligned.

Therefore, when a liquid crystal display device is constructed by combining the liquid crystal display panel with the liquid crystal display panel, the arrangement of the pixel openings in the liquid crystal display panel and the arrangement of the light guide regions in the light guide plate are made to coincide with each other, so that the backlight device is obtained. Light emitted from the liquid crystal display panel can be collected and transmitted through the pixel openings of the liquid crystal display panel, and the liquid crystal display device can have a large absolute transmitted light amount to increase the front luminance and improve the image contrast.

Furthermore, by scattering the light that has passed through the liquid crystal display panel using a diffusion plate or the like, a wide viewing angle can be realized without lowering the contrast.

[Brief description of drawings]

FIG. 1 is a perspective view showing a conventional backlight device.

FIG. 2 is a diagram illustrating an operation of a prism sheet used in the above backlight device.

FIG. 3 is a cross-sectional view showing a structure of a backlight device according to an exemplary embodiment of the present invention.

FIG. 4 is a diagram showing how light is emitted from a light guide region in the above backlight device.

FIG. 5 is a diagram showing how light emitted from a light guide region is collimated into substantially parallel light by a lens.

FIG. 6 is a diagram illustrating a configuration for making the distribution of the brightness of light emitted from the light emitting surface of the light guide plate uniform.

FIG. 7 is a diagram showing the relationship between the emission angle and the relative intensity of light reflected by the back surface reflection layer in the central portion of the light guide plate.

FIG. 8 is a diagram showing a relationship between an emission angle and relative intensity of light reflected by the back surface reflection layer at a position deviated from the center of the light guide plate.

FIG. 9 is a schematic cross-sectional view showing a liquid crystal display device including the above backlight device.

FIG. 10 is a diagram showing a state of light emitted from a backlight device and entering a pixel opening of a liquid crystal display panel.

FIG. 11 is a diagram showing another state of light emitted from the backlight device and entering the pixel openings of the liquid crystal display panel.

FIG. 12 is a diagram showing an arrangement of lenses in a lens array.

FIG. 13 is a diagram showing another arrangement of lenses in the lens array.

FIG. 14 is a diagram showing still another arrangement of lenses in the lens array.

15 is a diagram showing a state of light emitted from a light guide region and collimated into substantially parallel light by the lens array in the backlight device using the lens array of FIG.

FIG. 16 is a cross-sectional view showing another structure of the light guide region.

FIG. 17 is a sectional view showing still another structure of the light guide region.

FIG. 18 is a cross-sectional view showing still another structure of the light guide region.

FIG. 19 is a cross-sectional view showing still another structure of the light guide region.

FIG. 20 is a cross-sectional view showing a structure of a backlight device according to another exemplary embodiment of the present invention.

FIG. 21 is a sectional view showing the structure of a backlight device according to another embodiment of the present invention.

FIG. 22 is a cross-sectional view showing a structure of a backlight device according to another exemplary embodiment of the present invention.

FIG. 23 is a perspective view showing a liquid crystal television according to the present invention.

FIG. 24 is a cross-sectional view showing the structure of the above liquid crystal television.

FIG. 25 is a cross-sectional view showing the structure of the above viewfinder.

[Explanation of symbols]

 1 Backlight Device 2 Light Guide Plate 3 Back Reflecting Layer 4 Fluorescent Tube 6 Light Guide Area 7 Light Reflecting Surface 8 Light Transmitting Window 9 Lens Array 9a Lens 14 Liquid Crystal Display Panel 15 Liquid Crystal Display Device 16 Optical Low Pass Filter 17 Diffusing Plate 20 Pixel Aperture 22 High Refractive Index Material 23 Coating Layer Made of High Refractive Index Material 24 Light Reflecting Layer

Claims (13)

[Claims] 1. The light generated by the light source is guided to the inside of the light guide plate,
In a backlight device in which the light inside the light guide plate is emitted to the outside from the light emission surface of the light guide plate, a plurality of light guide regions for capturing the light inside the light guide plate and emitting the light from the light emission surface are guided. A backlight device characterized by being provided dispersed inside an optical plate. 2. The backlight device according to claim 1, wherein the light guide region is a plurality of columnar regions having one end connected to the light exit surface of the light guide plate. 3. The backlight device according to claim 2, wherein the light guide region is formed of a material having a refractive index higher than that of the light guide plate. 4. The backlight device according to claim 2, wherein an outer peripheral surface of the light guide region is formed of a light reflection layer. 5. The backlight device according to claim 2, wherein the light guide region is longer as it is provided farther from the light source. 6. The backlight device of claim 2, wherein the light guide region has a tapered shape. 7. The backlight device according to claim 2, wherein the end surface of the light guide area is inclined with respect to a surface perpendicular to the axis of the light guide area. 8. The light guide region is inclined with respect to a direction perpendicular to the light exit surface of the light guide plate so that the inner end portion thereof approaches the direction of the light source located closest to the light guide region. The backlight device according to claim 2. 9. The backlight device according to claim 2, wherein a lens is arranged in each of the light guide regions corresponding to an end face facing the light emission face. 10. A backlight device in which light generated by a light source is guided to the inside of a light guide plate and the light inside the light guide plate is emitted to the outside from a light emission surface of the light guide plate. A backlight device having a plurality of light-transmissive windows opened on a light-reflecting surface, and a lens being arranged corresponding to each light-transmissive window. 11. A liquid crystal display device comprising the backlight device according to claim 1 and a liquid crystal display panel for displaying an image. 12. A backlight device according to claim 1, a liquid crystal display panel for displaying an image,
LCD TV with an image receiving circuit. 13. A backlight device according to claim 1, a liquid crystal display panel for displaying an image,
Viewfinder with eyepiece.