JPH08221013A - Plane display device and backlight device for the plane display device - Google Patents

Abstract

PURPOSE: To provide a transmission type plane display device and its backlight device, capable of controlling the angular distribution of outgoing light with a good utilizing effect of light and enhancing brightness. CONSTITUTION: This is the transmission type liquid crystal display device having a liquid crystal panel 16 and the backlight device disposed on the back surface side of the liquid crystal panel 16. The backlight device is equipped with a 1st light transmission plate 13 having a refractive index n1 , disposed parallel to the liquid crystal panel 16, a linear light source 12 disposed to be adjacent to at least one side end surface of the 1st light transmission plate 13 and a 2nd light transmission plate 17 having a refractive index which is nearly equivalent to n1 , disposed on the 1st light transmission plate 13 on the side of the liquid crystal panel 16. The surface of the 2nd light transmission plate 17 on the side of the 1st light transmission plate 13 is formed with a collimation coutour 18 for directing light from the light source 12 to be led by repeating total reflection in the 1st light transmission plate 13 toward the liquid crystal panel 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light-transmissive flat panel display device, and more particularly to a flat panel display device of the type in which a light source for a backlight is guided by a light guide plate.

[0002]

2. Description of the Related Art Generally, a liquid crystal display device is known as a light transmission type flat display device having a backlight light source. The liquid crystal display device is characterized by a flat structure and low power consumption, and has been put to practical use and spread to not only calculators and watches but also vehicle-mounted panels, measurement display panels, OA equipment, television receivers, and the like. The display panel itself of the liquid crystal display device is
Since it is non-luminous, it is desired to improve the backlight means for uniformly back illuminating the display panel.

The brightness of the transmissive liquid crystal display device depends on the light from the backlight means for back lighting. Therefore, when the light utilization efficiency of the backlight means is poor,
The liquid crystal display device becomes dark, and a large amount of power is consumed to maintain a predetermined brightness, and the low power consumption feature of the liquid crystal display device is diminished.

On the other hand, the liquid crystal display device has various operation modes related to the alignment of liquid crystal molecules in the liquid crystal panel. In the widely used twisted nematic mode (TN), super twisted nematic mode (STN) or birefringence mode (ECB), it is known that the light transmittance has a viewing angle dependency.

When the liquid crystal panel is illuminated by the backlight means, incident light travels substantially straight through the liquid crystal panel and is emitted.
Therefore, if the angle of the incident light is not controlled, in a liquid crystal display device that has a viewing angle dependency, the brightness decreases when the display surface is observed obliquely, and the display looks black like a negative film or whitish. However, there is a problem that visibility is extremely deteriorated. Therefore, it is desirable to be able to control the angle of light from the backlight means.

FIG. 16 shows the structure of a conventional liquid crystal display device. In this figure, the human is seen from above. Hereinafter, in this specification, when specifying the front and back surfaces of each member, the direction in which a person is located is defined as the “front surface side”, and the opposite direction is defined as the “back surface side”.

The liquid crystal display device comprises a liquid crystal panel, liquid crystal panel driving means (not shown) and backlight means. The liquid crystal panel 106 includes, for example, a liquid crystal layer 109, glass substrates 108 and 108 'located on both sides thereof, and polarizing plates 107 and 107' located on both sides thereof. Although not shown, the glass substrate 10
8, 108 'have electrodes for driving the liquid crystal and /
Alternatively, a switching element such as a TFT is formed.

On the back side of the liquid crystal panel 106, a backlight means called an edge light type is arranged. The structure of the backlight means includes a fluorescent tube 102 which is a linear light source,
102 ', a lamp house 101, 101' which surrounds them and functions as a reflecting mirror, an end face portion adjacent to the fluorescent tube, a light guide plate 103 made of an acrylic resin for transmitting light from the fluorescent tube, and a light guide plate 103. And a reflecting plate 105 arranged on the back surface side of the substrate with a predetermined gap.

A diffusing portion 104 having a dot pattern is formed on the light guide plate 103 on the back side. This diffusion unit 104
Is made of, for example, a white pigment and has a function of disturbing the total reflection of light guided in the light guide plate 103. In the transmissive liquid crystal display device having such a structure, the fluorescent tubes 102, 10
The light emitted from 2'is incident from the end face portion of the light guide plate 103. Since the light guide plate 103 is made of acrylic resin having a refractive index (n ₁ ) of about 1.5, while the refractive index (n ₂ ) of air surrounding the light guide plate 103 is 1.0, θc = COS
Total reflection occurs in a range exceeding the critical angle θc represented by ⁻¹ (n ₁ / n ₂ ). For this reason, the light incident from the end face portion repeatedly propagates inside the light guide plate 103 by being totally reflected.

FIG. 17 is a partially enlarged view of the light guide plate 103. When the light that repeatedly repeats the total reflection in the light guide plate 103 enters the diffusion unit 104, the total reflection is disturbed and is directed toward the liquid crystal panel 106. That is, as shown by the arrows a and b, the air is directed from the light guide plate 103 to the front surface side toward the liquid crystal panel 106, or as shown by the arrow c, the air is directed from the light guide plate 103 toward the rear surface toward the reflection plate 105. Then, the light is reflected by the reflection plate 105, enters the light guide plate 103 again toward the front side, passes through the light guide plate 103, and is directed to the liquid crystal panel 106.

The rear surface of the liquid crystal panel 106 is illuminated by the light directed to the liquid crystal panel 106.

[0012]

However, in the liquid crystal display device as shown in FIGS. 16 and 17, the diffusing section 10 is used.
4, the light is uncontrolledly diffused, and a part of the light reflected by the reflection plate 105 is absorbed and attenuated as indicated by the arrow c, and the light reaching the liquid crystal panel 106 is not efficiently used.

In addition, in such a structure, when the light which repeatedly repeats the total reflection enters the diffusion section 104, the total reflection is simply disturbed, and the liquid crystal panel 106 is moved straight ahead. It is difficult to control the angular distribution of the light emitted from the front surface of the. Therefore, it is an object of the present invention to provide a backlight device for a transmissive display device with good light utilization efficiency. Another object of the present invention is to provide a transmissive display device capable of controlling the angular distribution of light emitted from the backlight device. Another object of the present invention is to provide a flat display device in which the brightness is less likely to decrease due to the influence of the aperture ratio on the display panel side.

[0014]

A backlight device according to the present invention is a backlight device for supplying light which is transmitted through a display panel for displaying a two-dimensional image, in which light incident from an end is planarized. A first light guide plate for sending in a direction, a second light guide plate arranged on the surface of the first light guide plate, a top surface joined to the surface of the first light guide plate, and a bottom surface for the second light guide plate. And a plurality of convex portions that are joined to each other, form a collimation contour on the side surface, and direct the light from the first light guide plate in the transmission direction of the second light guide plate.

It is preferable that the plurality of protrusions having the collimation are formed integrally with the second light guide plate. Alternatively, if it can be manufactured, the convex portion may be integrally formed with the first light guide plate. Furthermore, the first light guide plate, the second light guide plate, and the protrusions may all be integrally formed.

The refractive index between the convex portion and the first light guide plate is
It is preferable that they are substantially equal. It is preferable that the area of the top surface of the convex portion joined to the first light guide plate is smaller than the area of the bottom surface of the convex portion joined to the second light guide plate. The gap between the plurality of convex portions arranged between the first light guide plate and the second light guide plate is a void or is filled with a material having a refractive index different from that of the material forming the convex portions. You can open it.

The collimation contour is not particularly limited, but any shape selected from the group consisting of a one-dimensional elliptical shape, a parabolic shape and a trapezoidal shape can be adopted. Further, the collimation contour may have any one shape selected from the group consisting of a two-dimensional elliptical shape, a parabolic shape, and a trapezoidal shape.

As the elliptical shape forming the collimation contour, the ratio of the short axis to the long axis is about 1: 4 or about 1: 2.
The elliptical shape can be adopted. The first light guide plate and the second light guide plate are not particularly limited, but can be made of acrylic resin.

The top surface of the convex portion and the surface of the first light guide plate are bonded by fusion or an adhesive. The refractive index of the adhesive is preferably substantially equal to the refractive index of the first light guide plate. The light source that supplies light from the end of the first light guide plate,
For example, a linear light source such as a fluorescent tube.

When a point light source is used, a plurality of convex portions having collimation contours on the side surfaces are formed at the end portion of the first light guide plate, and the top surfaces of the convex portions are rod-shaped light guide members. It is preferable that the point light source is arranged so as to be joined to the side surface of the light guide member so that light is incident from the end portion of the light guide member.

It is preferable that the refractive index of the light guide member is substantially equal to the refractive index of the first light guide plate. A flat panel display device according to the present invention includes the above-described backlight device and a display panel mounted on the entire surface thereof.

It is preferable that the second light guide plate of the backlight device and the display panel are bonded to each other by an optical coupling layer. The refractive index of the optical coupling layer is substantially equal to that of the second light guide plate. It is preferable that the pixels of the display panel and the collimation contour are aligned so that the light reflected by the one collimation contour is directed to one or more pixels of the display panel.

Alternatively, one pixel on one of the display panels has one
It is preferable that the pixels of the display panel and the collimation contour are aligned so that the light reflected by the collimation contour is directed. More preferably, the light reflected by the collimation contour passes through the opening which is a portion having no light blocking member disposed in each pixel of the display panel, and the collimation contour. And are aligned.

The display panel is not particularly limited, but a liquid crystal display panel can be exemplified. As a flat display device using a liquid crystal panel as a display panel,
A liquid crystal display device that scans each pixel using a simple matrix type electrode, a liquid crystal display device that scans each pixel using a switching element such as a TFT (thin film transistor), a plasma addressed liquid crystal display that uses a discharge channel where plasma discharge occurs as switching. A device etc. can be illustrated. Further, as the flat display device, other than the flat display device using a liquid crystal panel as a display panel, a panel using an electro-optical material other than liquid crystal as an optical switch material may be used as the display panel.

Further, the backlight device is not limited to one having the linear light sources on both sides of the first light guide plate, and may be a type having the linear light sources only on one side of the first light guide plate. Further, the light source is not limited to a line light source, and may be a point light source.

[0026]

According to the flat panel display device of the present invention, the light from the light source travels in the first light guide plate by repeating total reflection, and
The light enters the convex portion from the connection surface with the light guide plate, and enters the second light guide plate as emitted light at a predetermined angle due to the collimation contour formed on the side surface of the convex portion, toward the display panel such as a liquid crystal panel. move on. Therefore, it is possible to provide a liquid crystal display device having a backlight device with good light utilization efficiency.

Further, the angular distribution of the light emitted from the backlight means can be controlled by appropriately selecting the shape of the collimation contour from an ellipse, a parabola, a trapezoid or the like according to the application of the flat panel display device. Further, by adjusting the pitch of the collimation contour of the backlight device according to the pixel pitch of the flat display panel, the light emitted from the backlight device can be selectively transmitted through the openings of the pixels. As a result, the light emitted from the backlight can be efficiently used, and the brightness of the display panel can be increased.

[0028]

Embodiments of the transmission type liquid crystal display device according to the present invention will be described below with reference to the drawings. First Embodiment FIG. 1A shows the structure of the flat panel display device according to the first embodiment. In this figure, a human being views the flat panel display device from above.

The flat panel display device according to this embodiment is a liquid crystal display device, and has a liquid crystal panel (broken line) 16 and an edge light type backlight device arranged on the back surface side thereof. The backlight device is a fluorescent tube 1 which is a linear light source.
2, 12 ', the lamp houses 11 and 11' which surround the lamp houses 11 and 11 ', and the end faces of which are made of an acrylic resin which contacts the fluorescent tubes and transmits the light from the fluorescent tubes.
The light guide plate 13 and the second acrylic resin second light guide plate 17 arranged on the front surface side of the first light guide plate 13 are included.

The back surface of the second light guide plate 17, that is, the surface in contact with the first light guide plate 13, receives light from the liquid crystal panel 16 on the front surface side.
A collimation contour 18 is formed which is directed toward. The first light guide plate 13 and the second light guide plate 17 are fixed to each other by, for example, thermocompression bonding, or are connected by using an appropriate adhesive (not shown). Further, as shown in FIG. 1, the fluorescent tubes do not have to be provided on the opposite two side positions of the first light guide plate 13, but may be provided on one side or on two or more sides as desired.

The liquid crystal display device shown in FIG. 1 is different from the conventional liquid crystal display device shown in FIG.
5 and there is a second light guide plate 17 newly provided. In the liquid crystal display device having such a structure, the light emitted from the fluorescent tubes 12 and 12 ′ is emitted from the first light guide plate 13.
Is incident on the inside from the end face portion adjacent to. The first light guide plate 13 is
Since the refractive index (n ₁ ) is made of acrylic resin of about 1.5, and the refractive index (n ₂ ) of the air surrounding the first light guide plate 103 is 1.0, in the range exceeding the critical angle θc. Total internal reflection occurs. For this reason, the light incident from the end face portion repeatedly propagates inside the first light guide plate 13 by being totally reflected.

FIG. 2 is a partially enlarged view of the first light guide plate 13 and the second light guide plate 17 shown in FIG. The first light guide plate 13 and the second light guide plate 17 are fixed or connected by an appropriate adhesive (not shown), and the refractive index of this adhesive is the refractive index (n of the first light guide plate and the second light guide plate. It is preferably approximately equal to ₁ ).

The surface of the second light guide plate 17 connected to the first light guide plate 13 (the back surface side) is not entirely connected to the first light guide plate 13, but the second light guide plate 17 is formed with a convex portion 19. Yes,
The top surface of the convex portion 19 serves as a connection surface and is partially connected.
Collimation contours 18 are formed on the slopes of the protrusions 19, and spaces 20 are formed between the protrusions 19. In addition,
A layer of a material having a refractive index different from that of the first and second light guide plates 13 and 17 may be embedded in the space 20.

The formation of the collimation contour 18 is performed by a conventional molding process. In this specification and drawings, the term "collimation contour" means a shape or an interface that reflects incident light into emitted light having a predetermined angle (for example, parallel light or diffused light controlled to a predetermined angle). Then, specific examples thereof are illustrated in FIGS.

Light which propagates in the first light guide plate 13 by repeating total reflection is transmitted from the top surface (the connection surface between the first light guide plate 13 and the second light guide plate 17) or via an appropriate adhesive layer. The light is incident on the second light guide plate 17 from the top surface. The first light guide plate 13, the adhesive layer, and the second light guide plate 17 have substantially the same refractive index n ₁ , and therefore, light disturbance, interference, reflection, etc. do not substantially occur at this connection surface. The light that has entered the second light guide plate 17 travels inside the convex portion 19 and enters the collimation contour 18. The second light guide plate 17 forming the convex portion 19 is made of an acrylic resin having a refractive index n ₁ (= 1.5), while the air surrounding the convex portion 19 is
The refractive index is n ₂ (= 1.0), and light is totally reflected similarly to the inside of the first light guide plate 13, and goes to the liquid crystal panel 16 with a predetermined emission angle according to the shape characteristic of the collimation contour 18.

The liquid crystal panel 16 is illuminated from the back surface by the light directed to the liquid crystal panel 16 as described above, and a predetermined image can be obtained by the optical switching action of each pixel in the liquid crystal panel 16. According to the backlight device used in the liquid crystal display device of FIGS. 1 and 2,
Unlike the liquid crystal display device according to the conventional example shown in FIG. 16, there is no uncontrolled diffusion by the diffusing section, and the first light guide plate is once emitted, reflected by the reflection plate, and again passed through the first light guide plate to pass through the liquid crystal display. There is no light that goes to the panel, and the utilization efficiency of the amount of light from the light source is improved. Further, by appropriately selecting the shape of the collimation contour 18, the angular distribution of the light emitted from the backlight device can be controlled. The liquid crystal panel 1
It is also possible to improve the viewing angle by providing an appropriate diffusion mechanism (not shown) after passing through the liquid crystal layer 6 and controlling the diffusion of the emitted light to a predetermined angle.

The first light guide plate 13 and the second light guide plate 1
The material of _No. 7 was described as an acrylic resin having a refractive index n ₁ = 1.5, but this is merely an example, and it is in air (refractive index n
_{In 2} ), a transparent material (for example, other plastic material etc.) in which the light traveling inside is totally reflected can be used. Further, as described above, if desired, some space (refractive index n ₃ ) can be filled in the space 20 between the second light guide plate 17 and the first light guide plate 13 other than the convex portion 19. . In this case, the material of the second light guide plate 17 is changed to have a refractive index of n ₁ ′, and the filling material into the space 20 and the second
At the interface between the light guide plate ^{17, θc = cos - 1 (} n 1 '/ n 3
The condition of total reflection of) should be satisfied. If the manufacturing problem can be solved, the first light guide plate 13 and the second light guide plate 17 can be solved.
And may be integrally formed of the same material. These changes can be made in the same way for all the embodiments described below.

FIGS. 3 to 6 show the results of computer simulation of the angular distribution of emitted light when the shape of the collimation contour 18 of the second light guide plate 17 is elliptical, elliptical, parabolic and trapezoidal, respectively. It should be noted that the coordinates on the drawings and the numbers described below are all dimensionless numbers (no unit), and are phenomena that are established when all numbers have the same unit, for example, millimeters.

FIG. 3 shows the results of a computer simulation of the angular distribution of the emitted light when the collimation contour 28 has an elliptical shape. This ellipse shows the length of the right end portion in the drawing (the base portion of the convex portion 19). D = 50, the length of the left end portion (corresponding to the width of the surface where the top surface of the convex portion 19 connects to the first light guide plate 13) d = 5, the major axis A of the ellipse = 200, and the ellipse This is the case where the short axis B = 50. Such a collimation contour 28 is characterized in that the emitted light is made into a substantially parallel light.

FIG. 4 shows the result of a computer simulation of the angular distribution of the emitted light when the collimation contour 48 has an elliptical shape. This ellipse is the length of the right end portion in the drawing (the base portion of the convex portion 19). D = 50, length of the left end (corresponding to the width of the surface where the top surface of the convex portion 19 connects to the first light guide plate 13) d = 5, ellipse major axis A = 100, ellipse short This is the case for axis B = 50. Compared with FIG. 3, the feature is that the emitted light is considerably diffused by shortening the length of the major axis A.

FIG. 5 shows the result of a computer simulation of the angular distribution of the emitted light when the collimation contour 58 has a parabolic shape. This parabola is the length of the right end in the drawing (the base portion of the convex portion 19). Equivalent to the width of) D = 50,
This is a case where the length of the left end portion (corresponding to the width of the surface where the top surface of the convex portion 19 is connected to the first light guide plate 13) d = 5 and the focal length f = 2. It is characterized in that the emitted light is evenly directed in the opening direction.

FIG. 6 shows the results of a computer simulation of the angular distribution of the emitted light when the collimation contour 68 has a trapezoidal shape. This trapezoid has the length of the left end (the top surface of the convex portion 19 is the first This corresponds to the case where d = 5 and the width e = 70 of the base of the trapezoid, which corresponds to the width of the surface connected to the light guide plate 13. The feature is that the emitted light is largely diffused.

The above collimation contours are examples,
Which of the above-mentioned collimation contours or ellipses having different shapes, or a parabolic or trapezoidal collimation contour is adopted is determined depending on the type and application of the display panel. Second Embodiment In FIGS. 1 and 2, the collimation contour 18 of the second light guide plate 17 is shown only by a cut surface, and the shape in the depth direction is not mentioned at all. Next, this point will be described with reference to FIGS. 7 and 8.

FIG. 7 shows a backlight device having a one-dimensional collimation contour, and FIG. 8 shows a backlight means having a two-dimensional collimation contour. Figure 7
(A) shows the structure of the liquid crystal display device according to the present embodiment,
This figure shows the positional relationship seen by a person from above.

The liquid crystal display device according to this embodiment has a liquid crystal panel (broken line) 76 and a backlight device arranged on the back side thereof. The backlight device includes fluorescent tubes 72, 72 'which are linear light sources, lamp houses 71, 71' which surround the fluorescent tubes 72 and 72 'and which function as reflecting mirrors, and end faces of which are arranged in contact with the fluorescent tubes. It is composed of a first light guide plate 73 made of acrylic resin that transmits light, and a second light guide plate 77 made of the same acrylic resin that is arranged on the surface side of the first light guide plate 73.

On the back side of the second light guide plate 77, that is, the surface in contact with the first light guide plate 73, a collimation contour 78 for directing light to the liquid crystal panel 76 on the front side is formed in a one-dimensional structure. FIG. 7B is a detailed view of a state in which only the second light guide plate 77 is turned upside down. The convex portions 79 extend in the depth direction and are arranged parallel to each other. The collimation contour 78 extends in the depth direction,
The top surface has an elongated rectangular shape.

The first light guide plate 73 and the second light guide plate 77 are fixed to each other by, for example, thermocompression bonding, or are connected by using an appropriate adhesive (not shown). It should be noted that, as shown in FIG.
It need not be provided on one side, and may be provided on one side or on two or more sides as desired.

In the transmissive liquid crystal display device having the backlight device having such a structure, the light emitted from the fluorescent tubes 72, 72 ′ enters the inside from the adjacent end face portion of the first light guide plate 73. The first light guide plate 73 is made of an acrylic resin having a refractive index (n ₁ ) of about 1.5, while the air surrounding the first light guide plate 73 has a refractive index (n ₂ ) of 1.0.
Total reflection occurs in a range exceeding the critical angle θc. For this reason, the light incident from the end face portion repeatedly propagates inside the first light guide plate 73 by being totally reflected.

The first light guide plate 73 and the second light guide plate 77 are fixed or connected by an appropriate adhesive (not shown), and the refractive index of this adhesive is the same as that of the first light guide plate and the second light guide plate. It is preferable that the refractive index is substantially equal to n ₁ . First of the second light guide plate 77
Regarding the surface (rear surface side) connected to the light guide plate 73, the entire surface is not connected to the first light guide plate 73, but the rectangular top surface of the convex portion 79 extending in the depth direction serves as a connection surface and is partially connected. However, the collimation contour 7 is formed on the slope of the convex portion 79.
8 is formed extending in the depth direction. In addition, a space is formed between the two adjacent convex portions 79.

Light which propagates in the first light guide plate 73 by repeating total reflection is transmitted from the top surface (connection surface) of the convex portion 79 or from the top surface (connection surface) via the adhesive layer to the second light guide plate 73. It is incident on 77. First light guide plate 73, adhesive layer and second light guide plate 7
_No. 7 has substantially the same refractive index (n ₁ ), and light disturbance, interference, reflection, etc. at this connection surface do not substantially occur. The light that has entered the second light guide plate 77 travels inside the convex portion 79 and enters the collimation contour 78. Second light guide plate 7 forming the convex portion 79
7 is made of acrylic resin having a refractive index n ₁ (= 1.5),
On the other hand, the air surrounding the convex portion 79 has a refractive index n ₂ (= 1.0).
As with the inside of the first light guide plate 73, the light is totally reflected, travels with a predetermined emission angle according to the shape characteristic of the collimation contour 78, and travels toward the liquid crystal panel 76.

The liquid crystal panel 76 is illuminated from the back side by the light directed to the liquid crystal panel 76. According to the second light guide plate 77 used in the liquid crystal display device shown in FIG. 7, unlike the liquid crystal display device according to the conventional example of FIG. 16, there is no unlimited diffusion by the diffusing section, and the light guide plate is once emitted and reflected. There is no light reflected by the plate and again passing through the light guide plate toward the liquid crystal panel, and the utilization efficiency of the light from the light source is improved. Further, by appropriately selecting the collimation contour 78, it becomes possible to control the angular distribution of the light emitted from the backlight unit.

FIG. 8A shows the structure of the liquid crystal display device according to the modified example of FIG. 7, and this figure shows the positional relationship as seen by a person from above. The liquid crystal display device according to the present embodiment,
It has a liquid crystal panel (broken line) 86 and a backlight device arranged on the back surface side thereof. The backlight device includes fluorescent tubes 82 and 82 'which are line light sources, lamp houses 81 and 81' which surround the fluorescent tubes 82 and 82 ', and end faces of which are arranged in contact with the fluorescent tubes. A first light guide plate 83 made of acrylic resin for transmitting light, and the first light guide plate 83
And a second light guide plate 88 made of the same acrylic resin and arranged on the front surface side of the.

On the back side of the second light guide plate 88, that is, the surface in contact with the first light guide plate 83, a collimation contour 88 for directing light to the liquid crystal panel 86 on the front side is formed in a two-dimensional structure. FIG. 8B is a detailed view of a state where only the second light guide plate 88 is turned upside down. A large number of embossed convex portions 89 exist in the matrix direction, and the embossed convex portions 89 have inclined surfaces. Has a collimation contour 88, and the top surface of the protrusion has a small circular shape. The arrangement of the embossed convex portions 89 can be a regular lattice shape, a scattered point shape, or any other desired arrangement.

The first light guide plate 83 and the second light guide plate 87 are fixed to each other by, for example, thermocompression bonding, or are connected by using an appropriate adhesive. The fluorescent tube as the light source is shown in FIG.
As shown in (A), it need not be provided on two sides of the first light guide plate 83, and may be provided on one side or on two or more sides as desired.

In the liquid crystal display device having the backlight device having such a structure, the light emitted from the fluorescent tubes 82 and 82 ′ enters the inside from the adjacent end face portion of the first light guide plate 83. The first light guide plate 83 has a refractive index (n ₁ ) of about 1.
Since the refractive index (n ₂ ) of the air surrounding the first light guide plate 83 is 1.0, the total reflection occurs in a range exceeding the critical angle θc. For this reason, the light incident from the end face portion repeatedly propagates inside the first light guide plate 83 by being totally reflected.

The first light guide plate 83 and the second light guide plate 88 are fixed or connected by an appropriate adhesive (not shown), and the refractive index of this adhesive is the refractive index of the first light guide plate and the second light guide plate. Rate n
It is preferably approximately equal to ₁ . The surface (back surface side) of the second light guide plate 87 connected to the first light guide plate 83 is not entirely connected to the first light guide plate 83, but is formed by a small circular portion which is the top surface of the embossed convex portion 89. And the collimation contour 88 is formed on the slope portion of the convex portion 89. In addition, between the second light guide plate 87 and the first light guide plate 83, a portion other than the convex portion 89 is a space.

The light that propagates in the first light guide plate 83 by repeating total reflection is secondly emitted from the small circular top surface (connection surface) or from the small circular top surface (connection surface) via the adhesive layer. Light guide plate 8
It is incident on 8. The first light guide plate 83, the adhesive layer, and the second light guide plate 87 have substantially the same refractive index (n ₁ ), and light disturbance, interference, reflection, etc. do not substantially occur. Second light guide plate 87
The entering light travels inside the convex portion 89 and collimation contour 8
It is incident on 8. The second light guide plate 87 forming the convex portion 89 is
Made of acrylic resin with refractive index n ₁ (= 1.5),
The air surrounding the convex portion 89 has a refractive index n ₂ (= 1.0), and the light is totally reflected in the same manner as in the light guide plate 83, and proceeds with a predetermined emission angle according to the shape characteristic of the collimation contour 88, Heading to the liquid crystal panel 86.

The back surface of the liquid crystal panel 86 is illuminated by the light directed to the liquid crystal panel 86. According to the back panel device used for the liquid crystal display device of FIG. 8, unlike the liquid crystal display device according to the conventional example shown in FIG. There is no light that is reflected by the light source and goes through the light guide plate to the liquid crystal panel again, and the effect of using the light from the light source is improved. Further, by appropriately selecting the collimation contour 88, it becomes possible to control the angular distribution of the light emitted from the backlight device.

Third Embodiment FIG. 9 shows a structure of a liquid crystal display device having a backlight device of a composite structure in which the collimation contour having the one-dimensional structure shown in FIG. 7 and the collimation contour having the two-dimensional structure shown in FIG. 8 are incorporated. This figure shows the positional relationship that humans can see from above.

The liquid crystal display device according to this embodiment has a liquid crystal panel (broken line) 96 and a backlight device arranged on the back side thereof. In this backlight device, a lamp house (not shown) that functions as a reflecting mirror, a metal halide lamp 92 that is a point light source disposed therein, and an end surface portion of the metal halide lamp 92 are in contact with the metal halide lamp 92. A light guide member 94 made of an acrylic resin, which is generally a rod-shaped member, for transmitting light from
A first light guide plate 93 made of the same acrylic resin that transmits light from the metal halide lamps that are arranged adjacent to each other along
And a second light guide plate 97 made of the same acrylic resin and arranged on the front surface side of the first light guide plate 93.

In the liquid crystal display device shown in FIG. 9, compared with the structure of the liquid crystal display device shown in FIG.
2 and is different in that the first light guide plate 13 is replaced with the first light guide plate 93 and a light guide member 94 is newly provided. The light guide member 94 and the first light guide plate 93 are fixed to each other by, for example, thermocompression bonding, or are connected to each other by using an appropriate adhesive (not shown). The combination of the metal halide lamp 12 which is a point light source and the light guide member 94 is
As shown in FIG. 9A, it need not be provided on one side of the first light guide plate 93, and may be provided on two or more sides of the first light guide plate 93 as desired. Further, the halide lamp 12 may be mounted on both sides of the light guide member 94.

As shown in FIG. 9, the end surface of the first light guide plate 93, that is, the surface in contact with the light guide member 94, has a projection 99 having a first collimation contour 98 that directs light to the first light guide plate 93. Have. The first collimation contour 98 is a one-dimensional structure collimation contour as shown in FIG. 7B, for example. Regarding the other configurations, the first light guide plate 93 is the same as the first light guide plate 7 shown in FIG.
3 or the first light guide plate 83 shown in FIG. 8A.

The second light guide plate 97 is the second light guide plate 97 shown in FIG.
It may be the same as either the light guide plate 87 or the second light guide plate 87 shown in FIG. Therefore, the relationship between the first light guide plate 93 and the second light guide plate 97 shown in FIG. 9A is the relationship between the first light guide plate 73 and the second light guide plate 77 in FIG.
This is the same as the relationship between the first light guide plate 83 and the second light guide plate 87 in (A).

In the liquid crystal display device having such a backlight device, the light emitted from the metal halide lamp 92 enters inside from the adjacent end portion of the light guide member 94. The light guide member 94 is made of acrylic resin having a refractive index (n ₁ ) of about 1.5. On the other hand, the air surrounding the light guide member 94 has a refractive index n ₂ = 1.0. Total reflection occurs in the range over. For this reason, the light incident from the end portion travels in the light guide member 94 by repeating total reflection.

FIG. 9B shows the first light guide plate 9 of FIG. 9A.
3 is an enlarged view of FIG. In order to make the drawing easier to see, the light guide member 94
Although the first light guide plate 93 and the first light guide plate 93 are separated from each other, in practice, the light guide member 94 and the first light guide plate 93 are partially fixed to each other by the top surface (connection surface) of the convex portion 99 or an appropriate adhesive. Partially connected. Similarly, the first light guide plate 93 and the second light guide plate 92 are also partially fixed by the top surface (connection surface) of the convex portion 99 ′ or partially connected by an appropriate adhesive. The refractive index of these adhesives is preferably substantially equal to the refractive index n ₁ of the first light guide plate 93 and the second light guide plate 97.

Light that repeatedly propagates in the light guide member 94 is incident on the inside of the protrusion 99 from the top surface of the protrusion 99 of the first light guide plate 93 or from the top surface via the adhesive layer. However, due to the reflection at the collimation contour 98 of the convex portion 99, the first
It enters the light guide plate 93. Next, the light that travels in the first light guide plate 93 by repeating total reflection is the convex portion 9 of the second light guide plate 97.
The light is incident on the second light guide plate 97 from the top surface formed on 9'or via the adhesive layer.

Light guide member 94, adhesive layer, first light guide plate 93
The second light guide plate 97 and the second light guide plate 97 have substantially the same refractive index (n ₁ ), and light disturbance, interference, reflection, etc. do not substantially occur. Second
The light entering the light guide plate 97 travels at a predetermined emission angle according to the characteristics of the collimation contour and travels toward the liquid crystal panel 96, as in the case described with reference to FIGS. 7 and 8.

The rear surface of the liquid crystal panel 96 is illuminated by the light directed to the liquid crystal panel 96. According to the backlight device used for the liquid crystal display device shown in FIG. 9, unlike the liquid crystal display device according to the conventional example shown in FIG. 16, there is no unlimited diffusion by the diffusing section, and the first light guide plate is provided once. There is no light that goes out, is reflected by the reflection plate, passes through the first light guide plate, and goes toward the liquid crystal panel again, so that the utilization efficiency of the light from the light source is improved. Also, the collimation contour 9
By appropriately selecting 8 ', the angular distribution of the light emitted from the backlight device can be controlled.

Furthermore, by using the light guide member 94, it becomes possible to change the point light source into a line light source. Therefore, in FIG. 9, the structure excluding the liquid crystal panel 96 is
An illumination structure that converts a point light source into a surface light source is provided. Fourth Embodiment A flat panel display device according to an embodiment shown in FIG. 10 is a plasma addressed liquid crystal display panel with a backlight device, and a discharge channel 212 in which plasma discharge is generated in the display panel.
Have.

First, the plasma addressed display panel excluding the backlight device will be described with reference to FIGS. As shown in FIG. 11, the plasma addressed display panel 200 includes an electro-optical display cell 201, a plasma cell 202, and a dielectric sheet 20 interposed therebetween.
It has a flat panel structure in which 3 and 3 are laminated. The dielectric sheet 203 is made of thin glass plate or the like. The dielectric sheet 203 needs to be as thin as possible in order to drive the display cell 201, and is formed of, for example, thin glass plate having a plate thickness of about 50 μm.

The display cell 201 is constructed by using an upper transparent glass substrate (upper substrate) 204. Upper substrate 2
A plurality of row electrodes (data electrodes) 2 made of a transparent conductive material and extending in the row direction (vertical direction) 2 are provided on the inner main surface of 04.
05 are formed in parallel in the column direction (horizontal direction) while maintaining a predetermined interval along the row direction. The upper substrate 204 is bonded to the dielectric sheet 203 with a predetermined gap maintained by a spacer (not shown). Upper substrate 204
Liquid crystal as an electro-optical material is filled in the gap between the dielectric sheet 203 and the liquid crystal layer 207. Here, the size of the gap between the upper substrate 204 and the dielectric sheet 203 is, for example, 4 to 10 μm, and is kept uniform over the entire display surface.

On the other hand, the plasma cell 202 is constructed by using a lower transparent glass substrate (lower substrate) 208.
On the inner main surface of the lower substrate 208, a plurality of anode electrodes 209 and cathode electrodes 211 that form plasma electrodes and extend in the column direction are formed in parallel in the row direction while alternately maintaining a predetermined interval. In addition, a partition wall 210 having a predetermined width is formed at substantially the center of each upper surface of the anode electrode 209 so as to extend along the electrode. The top of each partition 210 is brought into contact with the lower surface of the dielectric sheet 203,
The size of the gap between the lower substrate 208 and the dielectric sheet 203 is kept constant. The partition wall 210 is formed in a stripe shape by screen printing, for example, and is made of a material containing glass as a main component. The positional relationship between the anode electrode 209 and the cathode electrode 211 can be modified in various ways, and may be the opposite of that shown in FIG.

Further, a frit seal material (not shown) made of low melting point glass or the like is arranged along the peripheral portion of the lower substrate 208, and the lower substrate 208 and the dielectric sheet 203 are connected to each other. Are joined airtightly. Lower substrate 208
The ionizable (dischargeable) gas is filled in the gap between the dielectric sheet 203. As the gas to be sealed, for example, helium, neon, argon, or a mixed gas thereof is used.

Lower substrate 208 and dielectric sheet 203
In the gap, a plurality of discharge channels (spaces) 212 extending in the column direction and separated by the barrier ribs 210 are formed in parallel in the row direction. That is, the discharge channel 212 is formed so as to be orthogonal to the data electrode 205. Each data electrode 2
05 is a column drive unit. Further, as will be described later, since the anode electrodes 209 are commonly connected and the anode voltage is supplied, the discharge channel 12 in which the cathode electrodes 211 are located serves as a row driving unit. Pixels 13 are defined at the intersections of the two, as shown in FIG.

In the above structure, when a predetermined voltage is applied between the anode electrode 209 and the cathode electrode 211 corresponding to the predetermined pair of discharge channels 212, the gas in the pair of discharge channels 212 is selectively selected. Are ionized to generate plasma discharge, and the inside thereof is maintained at substantially the anode potential. When a data voltage is sequentially applied to the data electrode 205 in this state, the dielectric sheet 203 is formed on the liquid crystal layer 7 of the plurality of pixels 213 arranged in the column direction corresponding to the pair of discharge channels 212 in which plasma discharge has occurred. The data voltage is written via. When the plasma discharge ends, the discharge channel 212 becomes a floating potential, and each pixel 21
The data voltage written in the liquid crystal layer 207 of No. 3 is held by the action of the dielectric sheet 203 until the next writing period (for example, after one frame). In this case, the discharge channel 212 functions as a sampling switch, and the liquid crystal layer 207 and / or the dielectric sheet 203 of each pixel 213 functions as a sampling capacitor.

Since the liquid crystal is operated by the data voltage written in the liquid crystal layer 207 of each pixel 213, display is performed in pixel units. Therefore, as described above, the pair of discharge channels 212 for writing the data voltage to the liquid crystal layer 207 of the plurality of pixels 213 arranged in the column direction by generating the plasma discharge are sequentially scanned in the row direction to thereby form the two-dimensional image. The display can be done.

FIG. 13 shows a circuit configuration of the plasma addressed display panel 200 described above. 13, parts corresponding to those in FIGS. 11 and 12 are designated by the same reference numerals. A liquid crystal driver 221 is supplied with video data (DATA). From the liquid crystal driver 221, data voltages DS _{1 to} D of a plurality of pixels forming respective lines are provided for each horizontal period.
S _m are output at the same time, and the data voltages DS of the plurality of pixels are output.
₁ to DS _m are supplied to a plurality of data electrodes 205 ₁ to 205 _m via the buffer 222 ₁ to 222 _m, respectively.

The operation of the liquid crystal driver 21 is controlled by the control circuit 223. The horizontal synchronizing signal HD and the vertical synchronizing signal VD corresponding to the video data (DATA) are supplied to the control circuit 223 as synchronizing reference signals. The control circuit 223 also controls the operations of an anode driver 224 and a cathode driver 225, which will be described later.

Reference numeral 224 is an anode driver. The anode voltage VA as a reference voltage is supplied from the anode driver 224 to the plurality of commonly connected anode electrodes 209 _{1 to} 209 _n . 225 is a cathode driver. For each horizontal period, the cathode driver 225 sequentially applies a plurality of cathode electrodes 211 _{1 to} 211 _n-1 to the cathode voltages VK _{1 to} VK _n-1 having a predetermined potential difference from the anode potential.
Is supplied. Discharge channels 212 Thus, corresponding to the cathode electrode 211 ₁ ~211 _n-1 every horizontal period
A plasma discharge is sequentially generated in the pair of discharge channels 21 for writing the data voltages DS _{1 to} DS _m to the liquid crystal layer 207 of the plurality of pixels 213 arranged in the column direction (horizontal direction).
2 is sequentially scanned in the row direction (vertical direction).

Here, the cathode voltage applied to the cathode electrode 211 and the data voltage DS applied to the data electrode 205 will be described. 14 (A) to (D)
Shows a cathode voltage VK _a ~VK _{a + 3} which are respectively applied to the cathode electrode 211 _a ~211 _{a + 3} consecutive, the data voltage FIG (E) is applied to predetermined data electrodes 205 DS Is shown. Cathode electrode 211 _a
To 211a _{+ 3} , cathode voltages VKa to VKa _{+ 3} having _a predetermined potential difference from the anode potential are applied in each one horizontal period (1H) continuous for each frame. As a result, the discharge channels 212 that generate plasma discharge are sequentially scanned in the row direction (vertical direction). The polarity of the data voltage DS is inverted with respect to the anode potential every horizontal period and every frame, and the liquid crystal layer 207 is AC-driven. The reason why the liquid crystal layer 207 is driven by alternating current is to prevent deterioration of the liquid crystal.

As shown in FIG. 1, deflection plates (deflection sheets) 246 and 244 having different deflection angles are attached to the front surface of the upper substrate 204 and the back surface of the lower substrate 208, respectively. Light is deflected by the deflecting plate 244, the deflected light is deflected again according to the voltage applied to the liquid crystal layer 207 in each pixel, or is transmitted without being deflected, and the light is emitted from the deflecting plate 246. By doing so, an optical shutter function is generated for each pixel, and a two-dimensional image is obtained.

Next, a backlight device mounted on such a plasma addressed display panel will be described.
As shown in FIG. 10, in the backlight device according to the present embodiment, the lower substrate 208 of the plasma addressed display panel (actually, via the optical coupling layer 242,
It is adhered to the deflection plate 244). The optical coupling layer 242 is composed of an adhesive or the like having a refractive index n ₂ that is substantially equal to that of the second light guide plate 237 described later. The use of such an optical coupling layer 242 is to prevent reflection at the interface between the backlight device and the display panel and prevent a decrease in brightness.

The backlight device according to this embodiment is the first
It has a light guide plate 233, a second light guide plate 237, and a light source (not shown). As the light source, the fluorescent tubes 12, 12 'as the linear light source as shown in FIG. 1 or the halide lamp 92 as the point light source as shown in FIG. 9 can be used. When using a point light source such as a halide lamp 92, it is preferable to use a light guide member 94 as shown in FIG.

The first light guide plate 233 shown in FIG.
This is the same as the first light guide plate 13, 73, 83, 93 of any one of the first to third embodiments shown in FIG. The second light guide plate 237 shown in FIG. 10 is the same as the second light guide plates 17, 77, 87, 9 shown in the above embodiment except for the configuration shown below.
It is the same as any one of 7.

In this embodiment, as shown in FIG. 10, a plurality of convex portions 2 formed on the back surface of the second light guide plate 237.
The formation pitch of 39 is set to the discharge channel 212 of the display panel.
It matches the formation pitch of. Collimation contours 238 are formed on both side surfaces of the convex portion 239. That is, the pitch of the collimation contour 238 is set to be twice the pitch of the discharge channel 212. Moreover, the direction of the light emitted from the collimation contour 238 and the position of the gap between the electrodes 211 and 209 arranged in the discharge channel 212 are aligned.

In this embodiment, the collimation contour 238 shown in FIG. 10 is formed along the one-dimensional direction as shown in FIG. 7, and the longitudinal direction thereof is the discharge channel 21.
2 is preferably formed along the longitudinal direction. However, the collimation contour 238 shown in FIG. 10 may be formed in a matrix in the two-dimensional direction as shown in FIG. In that case, the alignment is performed so that one pixel of the display panel is positioned between the embossed convex portions where the collimation contour is formed and the embossed convex portions.

In this embodiment, from the light source to the first light guide plate 233.
The light incident on the light propagates in the first light guide plate 233 while repeatedly undergoing total reflection in the same manner as in the above-described embodiment, and the convex portion 239
At the joint portion with, it moves from the first light guide plate 233 into the convex portion 239 of the second light guide plate 237. Light does not leak from the inside of the first light guide plate 233 except for the joint portion with the convex portion 239. The light that has entered the convex portion 239 is reflected by the collimation contour 238, and becomes parallel light that is uniform toward the display panel side.

Since the collimation contour 238 and the gap (opening) between the electrodes 209 and 211 of the display panel are aligned as described above, the light incident on the display panel side is reflected by the electrodes 209 and 211. The light is efficiently emitted from the deflector 246 without being shielded by the light shield.

In the example shown in FIG. 10, by adjusting the width b of the collimation contour 238, the width of the light flux reflected from the collimation contour 238 toward the display panel can be adjusted. Further, by adjusting the distance a between the collimation contours 238, the pitch of the emitted light can be matched with the gap between the electrodes of the display panel.

In this embodiment, the spacing a between the collimation contours 238 is adjusted to the size of the opening on the display panel side.
By appropriately selecting the width b of the collimation contour 238, the light emitted from the backlight device is not blocked by the electrodes on the display panel side and the backlight light is used with an efficiency close to about 100%. be able to.

In the conventional backlight device, in order to uniformly illuminate the entire surface of the display panel, the brightness of the display screen is affected by the aperture ratio due to the arrangement of electrodes on the display panel side. For example, in a plasma addressed display panel, the aperture ratio is usually 30 to 50%. For this reason,
The brightness of the display screen was reduced to 30 to 50% of the backlight brightness only due to the influence of the aperture ratio of the discharge channel.

The backlight device according to this embodiment is shown in FIG.
Not only the plasma address display panel shown in FIG. 0, but also the plasma address display panel having another electrode structure, the other liquid crystal panel, or the other display panel can be mounted.

Fifth Embodiment A flat panel display device according to the embodiment shown in FIG. 15 is a plasma addressed liquid crystal display panel with a backlight device, and a discharge channel 312 in which plasma discharge is generated in the display panel.
10 is similar to the fourth embodiment shown in FIG.

The flat panel display device according to the embodiment shown in FIG. 15 is a modification of the flat panel display device according to the fourth embodiment shown in FIG. 10, and in the following description, some of the common parts will not be described. . First, the plasma addressed display panel excluding the backlight device will be briefly described.

The plasma addressed display panel 300 according to this embodiment has a flat panel structure in which an electro-optical display cell, a plasma cell, and a dielectric sheet 303 interposed therebetween are laminated. The display cell has an upper substrate 304, and the upper substrate 304 is a spacer (not shown).
The dielectric sheet 30 with a predetermined gap maintained by
It is joined to 3. Upper substrate 304 and dielectric sheet 3
Liquid crystal as an electro-optical material is filled in the gap 03 to form a liquid crystal layer 307.

The plasma cell is constructed using the lower substrate 308. On the inner main surface of the lower substrate 308, a plurality of anode electrodes 30 forming a plasma electrode and extending in the column direction are formed.
9 and the cathode electrodes 311 are alternately formed at predetermined intervals and are formed in parallel in the row direction. Further, a partition 310 having a predetermined width is formed adjacent to the anode electrode 309 so as to extend along the electrode. And each partition 3
The top of 10 is brought into contact with the lower surface of the dielectric sheet 303, and the size of the gap between the lower substrate 308 and the dielectric sheet 303 is kept constant.

The surface of the upper substrate 304 and the lower substrate 308.
Deflection plate (deflection sheet) with different deflection angle from the back side of
346 and 344 are attached. The other structure of the display panel is similar to that of the embodiment shown in FIGS. Next, the backlight device according to the present embodiment will be described.

The backlight device according to this embodiment is the first
It has a light guide plate 333, a second light guide plate 337, and a light source (not shown). As the light source, the fluorescent tubes 12, 12 'as the linear light source as shown in FIG. 1 or the halide lamp 92 as the point light source as shown in FIG. 9 can be used. When using a point light source such as a halide lamp 92, it is preferable to use a light guide member 94 as shown in FIG.

The first light guide plate 333 shown in FIG.
This is the same as the first light guide plate 13, 73, 83, 93 of any one of the first to third embodiments shown in FIG. The second light guide plate 337 shown in FIG. 15 is the same as the second light guide plates 17, 77, 87, 9 shown in the above embodiment except for the configuration described below.
It is the same as any one of 7.

In this embodiment, as shown in FIG. 15, a plurality of convex portions 3 formed on the back surface of the second light guide plate 337.
The formation pitch of 39 is set to the discharge channel 312 of the display panel.
It is adjusted to 1/2 of the formation pitch. Collimation contours 338 are formed on both side surfaces of the convex portion 339. That is, the pitch of the collimation contour 338 is set to the same pitch as the pitch of the discharge channels 312.
Moreover, the direction of the light emitted from the collimation contour 338 and the opening (electrode 311) in the discharge channel 312.
309 and the portion not shielded from light) are aligned.

In this embodiment, the collimation contour 338 shown in FIG. 15 is formed along the one-dimensional direction as shown in FIG. 7, and the longitudinal direction thereof is the discharge channel 21.
2 is preferably formed along the longitudinal direction. However, the collimation contour 338 shown in FIG. 15 may be formed in a matrix in the two-dimensional direction as shown in FIG. In that case, alignment is performed so that a part of the collimation contour 338 and one pixel of the display panel are positioned.

In this embodiment, from the light source to the first light guide plate 333.
The light incident on the light propagates in the first light guide plate 333 while repeatedly undergoing total reflection in the same manner as in the above-described embodiment, and the convex portion 339
At the joint portion with, the first light guide plate 333 moves into the convex portion 339 of the second light guide plate 337. Light does not leak from the inside of the first light guide plate 333 except for the joint portion with the convex portion 339. The light that has entered the convex portion 339 is reflected by the collimation contour 338, and becomes parallel light that is uniform toward the display panel side.

Since the collimation contour 338 and the gap (opening) between the electrodes 309 and 311 of the display panel are aligned as described above, the light incident on the side of the display panel receives the light from the electrodes 309 and 311. The light is efficiently emitted from the deflector 346 without being shielded by the light shield.

The backlight device according to this embodiment has the same operation as the backlight device according to the embodiment shown in FIG. The backlight device according to this embodiment is shown in FIG.
It is not only mounted on the plasma address display panel shown in (1), but can be mounted on the plasma address display panel having other electrode structure, other liquid crystal panel, or other display panel.

Although the embodiments of the flat panel display device and the backlight device according to the present invention have been described above, the above embodiments are merely examples and do not limit the present invention in any way. Therefore, changes and the like that can be easily made by those skilled in the art are included in the technical scope of the present invention.

[0106]

As described above, according to the present invention, it is possible to provide a transmissive liquid crystal display device provided with a backlight means having high light utilization efficiency. Further, according to the present invention, it is possible to provide a transmissive liquid crystal display device capable of controlling the angular distribution of light emitted from the backlight means.

Further, according to the present invention, by adjusting the pitch of the collimation contour of the backlight device in accordance with the pixel pitch of the flat display panel, the light emitted from the backlight device is selected for the opening of each pixel. Can be transparently transmitted. As a result, the light emitted from the backlight can be efficiently used, and the brightness of the display panel can be increased without increasing the power consumption.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a liquid crystal display device according to the present invention.

FIG. 2 is a diagram illustrating details of a first light guide plate and a second light guide plate of the liquid crystal display device according to the present invention shown in FIG.

FIG. 3 is a diagram showing a result of simulation of an angular distribution of emitted light when the collimation contour of the liquid crystal display device according to the present invention shown in FIG. 1 has an elliptical shape.

FIG. 4 is a diagram showing a result of simulation of an angular distribution of emitted light when the collimation contour of the liquid crystal display device according to the present invention shown in FIG. 1 has an elliptical shape.

FIG. 5 is a diagram showing a result of a simulation of angular distribution of emitted light when the collimation contour of the liquid crystal display device according to the present invention shown in FIG. 1 has a parabolic shape.

FIG. 6 is a diagram showing a result of simulation of an angular distribution of emitted light when the collimation contour of the liquid crystal display device according to the present invention shown in FIG. 1 has a trapezoidal shape.

7 is a diagram showing a case where the collimation contour of the liquid crystal display device according to the present invention shown in FIG. 1 has a one-dimensional structure.

8 is a diagram showing a case where the collimation contour of the liquid crystal display device according to the present invention shown in FIG. 1 has a two-dimensional structure.

FIG. 9 is a diagram showing a liquid crystal display device having a backlight device of a composite structure having a one-dimensional structure collimation contour and a two-dimensional structure collimation contour.

FIG. 10 is a cross-sectional view of main parts of a flat panel display device according to another embodiment of the present invention.

FIG. 11 is a cross-sectional perspective view of a main part of a plasma addressed liquid crystal display panel.

12 is a plan view showing an arrangement example of electrodes in the plasma addressed display panel shown in FIG. 11. FIG.

13 is a schematic circuit diagram showing a driving circuit of the plasma addressed display panel shown in FIG.

FIG. 14 is a diagram showing a pulse waveform in which the electrodes shown in FIG.

FIG. 15 is a cross-sectional view of essential parts of a flat panel display device according to another embodiment of the present invention.

FIG. 16 is a diagram showing a configuration of a conventional liquid crystal display device.

FIG. 17 is a diagram showing the details of the light guide plate of the conventional liquid crystal display device shown in FIG. 16 and explaining the operation of the backlight means.

[Explanation of reference signs] 11,71,81 Lamp house 12,72,82 Fluorescent tube (linear light source) 92 Halide lamp (point light source) 13,73,83 First light guide plate 93 First light guide plate 16,76,86 , 96 Liquid crystal panel 17, 77, 87, 97 Second light guide plate 18, 38, 48, 58, 68, 78, 88, 98 Collimation contour 19, 79, 89, 99 Convex portion

Claims (37)

[Claims] 1. A backlight comprising: a display panel for displaying a two-dimensional image by performing a switching action of light transmitted through each pixel; and a backlight unit for supplying light transmitted through the display panel. The means has a first light guide plate that sends light incident from an end in a planar direction, a second light guide plate disposed on a surface of the first light guide plate, and a top surface on the surface of the first light guide plate. A plurality of protrusions that are joined to each other, a bottom surface is joined to the second light guide plate, a collimation contour is formed on a side face, and light from the first light guide plate is directed in a transmission direction of the second light guide plate. And a flat panel display device. 2. The flat display device according to claim 1, wherein the plurality of convex portions on which the collimation is formed are formed integrally with the second light guide plate. 3. The flat panel display device according to claim 1, wherein the convex portions and the first light guide plate have substantially the same refractive index. 4. The area of the top surface of the convex portion joined to the first light guide plate is smaller than the area of the bottom surface of the convex portion joined to the second light guide plate. The flat display device described. 5. The gap between the plurality of convex portions arranged between the first light guide plate and the second light guide plate is a void.
The flat panel display device according to any one of 1. 6. The flat display device according to claim 1, wherein the second light guide plate and the display panel are adhered to each other by an optical coupling layer. 7. The plane display according to claim 1, wherein the collimation contour is along any one shape selected from the group consisting of a one-dimensional elliptical shape, a parabolic shape, and a trapezoidal shape. apparatus. 8. The plane display according to claim 1, wherein the collimation contour is along a shape selected from the group consisting of a two-dimensional elliptical shape, a parabolic shape, and a trapezoidal shape. apparatus. 9. The flat panel display device according to claim 7, wherein the elliptical shape forming the collimation contour is an elliptical shape having a ratio of a short axis to a long axis of about 1: 4. 10. The flat-panel display device according to claim 7, wherein the elliptical shape forming the collimation contour is an elliptical shape having a ratio of a short axis to a long axis of about 1: 2. 11. The first light guide plate and the second light guide plate,
The flat display device according to claim 1, wherein each of the flat display devices is made of an acrylic resin. 12. The flat display device according to claim 1, wherein a top surface of the convex portion and a surface of the first light guide plate are fusion-bonded to each other. 13. The top surface of the convex portion and the surface of the first light guide plate are bonded with an adhesive, and the refractive index of the adhesive is substantially equal to the refractive index of the first light guide plate. The flat display device according to any one of 1 to 12. 14. The flat display device according to claim 1, wherein the light source that supplies light from the end portion of the first light guide plate is a line light source. 15. The linear light source is a fluorescent tube.
The flat panel display device according to. 16. An end portion of the first light guide plate is formed with a plurality of protrusions having side surfaces with collimation contours, and the top surfaces of the protrusions are joined to the side surfaces of the rod-shaped light guide member. 14. The flat panel display device according to claim 1, wherein the point light source is arranged so that light is incident from an end portion of the light guide member. 17. The flat panel display according to claim 16, wherein a refractive index of the light guide member is substantially equal to a refractive index of the first light guide plate. 18. One or more pixels are provided on one or more pixels of the display panel.
18. The flat panel display device according to claim 1, wherein the pixels of the display panel are aligned with the collimation contours so that the light reflected by the collimation contours is directed. 19. The pixel of the display panel and the collimation contour are aligned so that the light reflected by one or more of the collimation contours is directed to one pixel of the display panel. The flat panel display device according to any one of 1. 20. The opening for each pixel and the collimation so that the light reflected by the collimation contour passes through the opening which is a portion without a light blocking member arranged in each pixel of the display panel. 20. The flat panel display device according to claim 19, wherein the contour is aligned with the contour. 21. The flat display device according to claim 1, wherein the display panel is a liquid crystal display panel. 22. A backlight device for supplying light transmitted through a display panel for displaying a two-dimensional image, comprising: a first light guide plate for sending light incident from an end portion in a plane direction; A top surface is joined to the surface of the first light guide plate, and a bottom surface is joined to the second light guide plate, and a collimation contour is formed on the side surface. And a plurality of convex portions that direct the light from the first light guide plate in the transmission direction of the second light guide plate. 23. The backlight device according to claim 22, wherein the plurality of convex portions on which the collimation is formed are formed integrally with the second light guide plate. 24. The backlight device according to claim 22, wherein the convex portion and the first light guide plate have substantially the same refractive index. 25. The area of the top surface of the convex portion joined to the first light guide plate is smaller than the area of the bottom surface of the convex portion joined to the second light guide plate. Backlight device described. 26. The gap between the plurality of convex portions arranged between the first light guide plate and the second light guide plate is a void.
The backlight device according to any one of to 25. 27. The collimation contour according to any one shape selected from the group consisting of a one-dimensional elliptical shape, a parabolic shape, and a trapezoidal shape.
The backlight device according to any one of 26. 28. The collimation contour is along any one shape selected from the group consisting of a two-dimensional elliptical shape, a parabolic shape and a trapezoidal shape.
The backlight device according to any one of 26. 29. The backlight device according to claim 27, wherein the elliptical shape forming the collimation contour is an elliptical shape having a ratio of a short axis to a long axis of about 1: 4. 30. The backlight device according to claim 27, wherein the elliptical shape forming the collimation contour is an elliptical shape having a ratio of a short axis to a long axis of about 1: 2. 31. The first light guide plate and the second light guide plate,
31. All of them are made of acrylic resin.
The backlight device according to any one of 1. 32. The backlight device according to claim 22, wherein a top surface of the convex portion and a surface of the first light guide plate are fusion-bonded to each other. 33. The top surface of the convex portion and the surface of the first light guide plate are bonded by an adhesive, and the refractive index of the adhesive is substantially equal to the refractive index of the first light guide plate. The backlight device according to any one of 22 to 32. 34. The backlight device according to claim 22, wherein the light source that supplies light from the end portion of the first light guide plate is a linear light source. 35. The linear light source is a fluorescent tube.
The backlight device according to. 36. A plurality of convex portions having collimation contours formed on the side surfaces are formed at the end portion of the first light guide plate, and the top surfaces of the convex portions are joined to the side surfaces of the rod-shaped light guide member. 34. The backlight device according to claim 22, wherein the point light source is arranged so that light is incident from an end portion of the light guide member. 37. The backlight device according to claim 36, wherein a refractive index of the light guide member is substantially equal to a refractive index of the first light guide plate.