JP2007027002A - Display device, and light guide plate used for display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device having a light guide plate contributing to reduction of thickness of a liquid crystal display device, capable of preventing uncontrollable leakage light from being emitted from a part between a principal surface for emitting illumination light and a side end for entering light even if the size of a frame thereof is reduced and thereby improving display quality. <P>SOLUTION: A crank part 30 bent in the thickness direction is formed between a side end of the light guide plate 15 for entering light from a light source 20 and a main body part having a principal surface for emitting illumination light; and, when it is assumed that angles of the upper and lower surfaces of the crank part 30 are θ<SB>1</SB>and θ<SB>2</SB>, respectively, and the refraction index of the light guide plate 15, and the number of times of reflection on a surface on the principal surface side in the crank part 30 of the light guide plate 15 are (n) and (m), respectively, a relationship of 2mθ<SB>1</SB>-2(m-1)θ<SB>2</SB><90-2arcsin(1/n) is satisfied. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides a display device in which a light guide plate is disposed on the back side or the front side of the display panel, and is illuminated by light emitted from the main surface of the light guide plate, and illuminates such a display device. It is related with the light-guide plate which guides the illumination light for.

  For example, as disclosed in JP-A-8-286043 and JP-A-9-160507, as an illuminating means of a liquid crystal display device, a light guide plate and a light source disposed on a side end of the light guide plate are used. The lighting device is widely used. In this type of display device, the light guide plate has a bottom surface that is inclined so that light from the light source is guided away from the light source and is emitted from the main surface orthogonal to the side end surface facing the light source. Yes.

  A liquid crystal display device using another conventional illumination device is shown in FIG. 1, for example. Here, the light source 1 is arranged to face the side end surface of the light guide plate 3 having the reflection plate 2 on the lower surface. The light guide plate 3 guides light from the light source to the far side with respect to the light source, and has an upper surface as an inclined surface 4 only in the vicinity of the light source 1 in order to reduce the thickness. The surface of the light guide plate 3 is a flat surface.

  A polarizing plate 5, a liquid crystal display panel 6, and a polarizing plate 7 are arranged on top of each other on the upper surface of the light guide plate 3 where the inclined surface 4 is not formed. The polarizing plates 5 and 7 and the liquid crystal display panel 6 constitute a liquid crystal display device, and the light guide plate 3 constitutes a back-illuminated backlight for the liquid crystal display device.

  Such a conventional light guide plate 3, in particular, the light guide plate 3 in which the upper surface on the light source 1 side is composed of the inclined surface 4 generates leakage light 8, which has a drawback in that the light use efficiency is lowered.

  As shown in FIG. 1B, when light from the light source 1 strikes the inclined surface 4 from a direction parallel to the bottom surface of the light guide plate 3, the light is totally reflected by the inclined surface 4. Then, the light totally reflected thereafter is totally reflected on the bottom surface of the light guide plate 3. However, since the angle with respect to the inclined surface 4 is totally reflected at the incident angle θ, the bottom surface is totally reflected at the incident angle of 2θ, so that the incident light stands in the normal direction by an angle corresponding to 2θ. Go up.

On the other hand, light traveling in the light guide plate 3 and reaching the inclined surface 4 or the main surface of the light guide plate 3 is emitted from the main surface when the angle is equal to or smaller than the critical angle of the inclined surface 4 or the main surface. On the other hand, when the critical angle is exceeded, total reflection is performed on the inclined surface 4 or the main surface. And when the material which comprises the light-guide plate 3 is an acrylic resin, since the refractive index is 1.492, when the angle with respect to the normal of the inclined surface 4 or a main surface is set to a,
sina = 1 / 1.492
Accordingly, light that has hit the inclined surface 4 or the main surface at an angle a within 42.09 degrees is emitted from the main surface. On the other hand, light hitting the main surface at an angle larger than 42.09 degrees is totally reflected by the inclined surface 4 or the main surface and further travels away from the light source 1.

  On the other hand, when the flat light guide plate 3 is used as the illumination means of the liquid crystal display device, light incident from the end of the light guide plate 3 is critical on the upper and lower surfaces of the light guide plate 3 as shown in FIG. Since the angle cannot be exceeded, as a result, the incident light propagates through the light guide plate 3 while repeating total reflection. Therefore, by applying surface treatment to form microstructures such as blasts, prisms and dots at predetermined positions on the upper and lower surfaces of the light guide plate 3, light exceeding the critical angle is created and guided at the site where the surface treatment is performed. By emitting from the light plate 3, it can be used as a surface light source. Therefore, by controlling the surface treatment of the light guide plate 3, the distribution of the emitted light from the light guide plate can be freely adjusted.

  On the other hand, there is a tendency for further thinning of the liquid crystal display device. In order to cope with this, for example, the light guide plate 3 is formed into a crank shape as shown in FIG. 3, and the crank portion 3a is formed between the main portion having the main surface and the side end portion on which the light from the light source 1 is incident. It is considered. With such a configuration, by disposing the flexible wiring board 9 and the like in the lower space generated by the crank portion 3a, the thickness of the display device can be reduced by the thickness of the wiring material 9. Become.

However, as shown in FIG. 4A, according to the crank portion 3a the upper surface inclination angle theta ₁ and the lower surface of the inclined bevel theta ₂ of angle equal to crank portion light guide plate 3 formed of the, even without surface treatment, Light that exceeds the critical angle may be generated. This is because the light incident on the light guide plate 3, the inclination angle theta ₁ of the inclined surface of the crank portion 3a, the angle at which propagates in the light guide plate 3 will rise by 2 [Theta] _1, As a result, 4A As shown in FIG. 4, when the end of the crank portion 3a is passed, the light exceeds the critical angle, and leakage light 8 emitted from the upper surface of the light guide plate 3 is generated. This becomes the emitted light that cannot be controlled by the surface treatment of the light guide plate 3, thereby causing the display quality of the liquid crystal display device to deteriorate significantly.

  Therefore, conventionally, the distance from the light source 1 to the display area shown in FIG. 3 is increased so that the emitted light does not affect the display quality. Alternatively, in order to eliminate such emitted light, as shown in FIG. 4B, the length of the crank portion 3a is sufficiently long.

  However, according to such a configuration, it is necessary to sufficiently increase the distance from the light incident portion of the light source 1 to the display area, and thus it is necessary to increase the outer shape of the liquid crystal display panel. On the other hand, in recent liquid crystal display devices, the distance from the light source 1 composed of LEDs to the display area tends to be shortened or a request to be shortened has arisen along with the narrowing of the frame. Accordingly, the length of the crank portion 3 in the length direction must be shortened.

Generally, when the length of the crank part 3 is shortened,
θ ₁ > 90−2 arcsin (1 / n), and the light is emitted from the upper surface of the crank portion 3, resulting in deterioration of display quality. For example, when the light guide plate is formed of polycarbonate resin, its refractive index n = 1.59.
θ ₁ = 13 °> 90-2 arcsin (1 / 1.59) = 12.1 °
The light is emitted from the slope of the crank portion 3. Accordingly, in the liquid crystal display device of the narrow frame module, non-uniform light is generated in the vicinity of the incident portion of the light source composed of LEDs (see FIG. 11A), which causes the display quality to deteriorate.
JP-A-8-286043 JP-A-9-160507

  The subject of this invention is providing the display apparatus excellent in the display quality, and the light-guide plate used for such a display apparatus.

  Another object of the present invention is to provide a display device that can be reduced in thickness without impairing display quality, and a light guide plate used in such a display device.

  Still another problem of the present invention is that the display device emits light only from a predetermined position of the main surface, and in particular, does not emit light in the portion between the side edge where light enters and the main surface, And it is providing the light-guide plate used for such a display apparatus.

  Still another object of the present invention is to increase the display quality by sufficiently reducing the distance from the side edge where the light from the light source is incident to the display area, and preventing emission of uncontrollable light in the meantime. And providing a light guide plate used in the display device.

  The above-described problems and other problems of the present invention will be made clear by the technical idea of the present invention described below and the embodiments thereof.

The main invention of the present application is that a light guide plate is arranged on the back side or the front side of the display panel, a light source is arranged on the side edge of the light guide plate, and light from the light source passes through the inside of the light guide plate. In a display device that emits light from the main surface and illuminates the display panel,
The light guide plate has a crank portion between a main portion having a main surface and a side end, and is bent in the thickness direction by the crank portion, and the crank portion is a surface opposite to the inclination angle of the main surface side. The present invention relates to a display device having a large inclination angle.

  Here, the display panel may be a liquid crystal display panel. The light guide plate may be a transparent or translucent synthetic resin molding. The light source disposed on the side edge of the light guide plate may be a light emitting diode. A wiring member may be disposed in a space below the crank portion of the light guide plate.

Another main invention of the present application is that a light guide plate is arranged on the back side or front side of the display panel, and a light source is arranged on the side end of the light guide plate, and the light from the light source is mainly passed through the inside. In a display device that emits light from a surface and illuminates the display panel,
The light guide plate has a crank part between a main part having a main surface and a side end, and is bent in the thickness direction by the crank part,
The inclination angle of the main surface side of the crank portion is θ ₁ , the inclination angle of the opposite surface is θ ₂ , the refractive index of the light guide plate is n, and the propagating light from the light source is on the main surface side of the crank portion. When m is the number of reflections on the inclined surface,
2mθ ₁ -2 (m-1) θ ₂ <90-2 arcsin (1 / n)
The present invention relates to a display panel characterized by satisfying the above relationship.

Here, the inclination angle of the inclined surface of the main surface side of the crank portion when the theta _1,
θ ₁ <90-2 arcsin (1 / n)
It may be. When the inclination angle of the inclined surface on the main surface side of the crank portion of the light guide plate is θ ₁ ,
θ ₁ <(90-2arcsin (1 / n)) / 2
It may be.

The main invention related to the light guide plate is a light guide plate arranged on the back side or the front side of the display panel, wherein the light guide plate illuminates the display panel with light emitted from the main surface thereof,
The surface has a crank portion between the main portion constituting the main surface and the side end on which light from the light source is incident, and is bent in the thickness direction by the crank portion, and the crank portion is on the main surface side. The present invention relates to a light guide plate characterized in that the angle of inclination of the opposite surface is larger than the angle of inclination. Here, the light guide plate may be a transparent or translucent synthetic resin molding.

Another main invention related to the light guide plate is a light guide plate arranged on the back side or the front side of the display panel, wherein the light guide plate illuminates the display panel with light emitted from the main surface.
The surface has a crank portion between a main portion constituting the main surface and a side end on which light from a light source is incident, and is bent in the thickness direction by the crank portion,
The inclination angle of the main surface side of the crank portion is θ ₁ , the inclination angle of the opposite surface is θ ₂ , the refractive index of the light guide plate is n, and the propagating light from the light source is on the main surface side of the crank portion. When m is the number of reflections on the inclined surface,
2mθ ₁ -2 (m-1) θ ₂ <90-2 arcsin (1 / n)
It is related with the light-guide plate characterized by satisfy | filling these relationships.

Here, the inclination angle of the inclined surface of the main surface side of the crank portion when the theta _1,
θ ₁ <90-2 arcsin (1 / n)
It may be. The inclination angle of the inclined surface of the main surface side of the crank portion when the theta _1,
θ ₁ <(90-2arcsin (1 / n)) / 2
It may be.

  In the main invention of the present application, a light guide plate is arranged on the back side or front side of the display panel, a light source is arranged on the side edge of the light guide plate, and light from the light source is mainly passed through the inside of the light guide plate. In a display device that emits light from a surface to illuminate a display panel, the light guide plate has a crank portion between a main portion having a main surface and a side end, and is bent in the thickness direction by the crank portion. The inclination angle of the surface on the opposite side is larger than the inclination angle on the main surface side.

  Therefore, according to such a display device, the light incident on the side end from the light source is emitted from the main surface through the light guide plate. Since the crank portion has a larger inclination angle on the opposite side than the inclination angle on the main surface side, no light is emitted to the outside from the surface on the main surface side of the crank portion, thereby improving the quality of the display device. Deterioration is prevented.

Another main invention of the present application is that a light guide plate is arranged on the back side or front side of the display panel, and a light source is arranged on the side end of the light guide plate, and the light from the light source is mainly passed through the inside. In a display device that emits light from a surface to illuminate a display panel, the light guide plate has a crank portion between a main portion having a main surface and a side end, and is bent in the thickness direction by the crank portion. the inclination angle of the main surface side and theta _1, the inclination angle of the surface opposite to the theta _2, the refractive index of the light guide plate is n, propagating light from the light source is reflected by the inclined surface of the main surface side of the crank portion When the number of times is m,
2mθ ₁ −2 (m−1) θ ₂ <90−2 arcsin (1 / n) is satisfied.

  Therefore, according to such a display panel, the light incident from the side end is totally reflected at the crank portion and is not emitted to the outside as leaked light, and the deterioration of the quality of the display device is avoided.

A main invention related to a light guide plate is a light guide plate arranged on the back side or the front side of the display panel, and the surface of the light guide plate illuminates the display panel with light emitted from the main surface of the light guide plate. A crank portion is provided between the main body portion and a side end on which light from the light source is incident. The crank portion is bent in the thickness direction, and an inclination angle on the main surface side of the crank portion is θ ₁ , When the angle of inclination of the surface is θ ₂ , the refractive index of the light guide plate is n, and the number of times the propagating light from the light source is reflected by the inclined surface on the main surface side of the crank portion is m,
2mθ ₁ −2 (m−1) θ ₂ <90−2 arcsin (1 / n) is satisfied.

  Therefore, according to such a light guide plate, light incident from the side end is not emitted to the outside as leakage light at the crank portion, but is propagated to the main portion side while being totally reflected on the upper and lower surfaces of the crank portion. The light can be effectively emitted from the main surface.

  The present invention will be described below with reference to embodiments shown in the drawings. FIG. 5A shows a back-illuminated liquid crystal display device, in which a liquid crystal display panel 10 in which liquid crystal is sealed between a pair of glass plates is provided, and polarizing plates 11 and 12 are arranged on both sides of the liquid crystal display panel 10. Is done. In addition, a lens sheet 13 having a protrusion with a mountain-shaped cross section is disposed so as to face the lower polarizing plate 12. In the illustrated configuration, a single lens sheet 13 is used, but two lens sheets may be used. A diffusion plate 14 is disposed below the lens sheet 13, and a light guide plate 15 constituting a backlight is disposed below the diffusion plate 14. A reflection plate 16 is further disposed below the light guide plate 15 to reflect light leaked downward. A light source 20 made of a light emitting diode (LED) is disposed on the side end side of the light guide plate 15. A flexible substrate 17 is disposed in a space formed by the crank portion 30 of the light guide plate 15.

  Therefore, according to such a liquid crystal display device, the light from the light source 20 is introduced into the liquid crystal display device 10 from the side end of the light guide plate 15 and emitted upward on the main surface of the light guide plate 15. The light is incident on the liquid crystal display panel 10 through the lens sheet 13, thereby illuminating from the back side and performing a display operation.

  FIG. 5B shows a front-illuminated liquid crystal display device, in which a reflective liquid crystal display panel 10 in which liquid crystal is sealed and a reflective layer 24 is formed on the inner surface of one glass plate is used. A retardation plate 23 is disposed on the upper surface of the liquid crystal display panel 10, and a polarizing plate 11 is disposed thereon. A light guide plate 15 is disposed above the polarizing plate 11. Here too, a light source 20 made of LEDs is arranged on the side edge of the light guide plate 15. A flexible substrate 17 is disposed in the upper space formed by the crank portion 30 of the light guide plate 15. Therefore, when the light source 20 is turned on, the light is incident on the liquid crystal display panel 10 through the polarizing plate 11 and the phase difference plate 23 by the light guide plate 15, reflected by the inner surface reflection layer 24 of the liquid crystal display panel 10, and upward. Exit. The emitted light can be seen from the outside through the transparent light guide plate 15, and a display operation is performed.

As shown in FIG. 6, the light guide plate 15 used as the illuminating means of the liquid crystal display panel 10 of such a liquid crystal display device has a crank portion 30 in the vicinity of a side end where light from a light source 20 made of a light emitting diode is incident. The crank portion 30 is bent in the thickness direction. The crank portion 30 has an upper surface having an inclination angle θ ₁ and a lower surface having an inclination angle θ ₂ . Here, θ ₁ <θ ₂ is satisfied.

Moreover, the light guide plate 15 has θ ₁
θ ₁ <90-2 arcsin (1 / n)
And the inclination angle θ ₁ of the upper surface of the crank part 30 of the light guide plate 15 and the inclination angle θ _{2 of the} lower surface are
2mθ ₁ −2 (m−1) θ ₂ <90−2 arcsin (1 / n) is satisfied. here,
n: Refractive index of the light guide plate m: Number of times propagating light in the light guide plate 15 is reflected on the upper surface of the crank portion 30 The light guide plate under the above conditions emits leaked light to the outside, particularly in the vicinity of the crank portion 30. There is nothing. This will be described below.

In FIG. 8, when the incident angle of the incident light to the side edge of the light guide plate 15 is α ₁ , the light angle α ₂ in the light guide plate 15 is n = sin α ₁ / sin α ₂ according to Snell's law.
α ₂ = arcsin (1 / n · sin (α ₁ ))
Here, α ₂ is maximized when α ₁ = 90 °. In this case,
α ₂ = arcsin (1 / n) (1)
Further, when the angle when the incident light hits the upper slope of the crank portion 30 is β, as is apparent from FIG. 8, α ₂ + β + θ ₁ = 90 °.
Therefore, β = 90−α ₂ −θ ₁ (2)
here,
n · sin β> 1 (3)
If so, the incident light is totally reflected by the upper slope of the crank portion 30 and is not emitted to the outside as leakage light. Substituting Equation (2) and Equation (1) into Equation (3) above,
n · sin (90−α ₂ −θ ₁ )> 1
n · sin (90− (arcsin (1 / n) −θ ₁ )> 1
(90− (arcsin (1 / n) −θ ₁ )> arcsin (1 / n)
θ ₁ <90-2 · arcsin (1 / n) (4)
Therefore, if the theta ₁ satisfies the equation (4) would no leakage light from the inclined surface of the crank portion 30.

Further, when the angle of the reflected light from the slope of the crank portion 30 is φ as shown in FIG.
φ = 90−β + θ ₁ = α ₂ + 2θ ₁
Next, when reflected once by the inclined surface of the crank portion 30, it is seen that the angle of light rises is incremented by 2 [Theta] _1.

Further, in FIG. 9, when the incident light reflected at the angle φ on the upper slope of the crank portion 30 hits the lower slope of the crank portion 30 is ψ,
ψ + φ + (90−θ ₂ ) = 180
Therefore, ψ = 90 + θ ₂ −φ
Furthermore, assuming that the angle of the reflected light from the lower slope of the crank portion 30 is ω as shown in FIG. 9, ψ + θ ₂ + ω = 90
ω = 90−θ ₂ −ψ = φ−2θ ₂
Therefore, the light anti-Isa as up force to the upper once only 2 [Theta] ₁ by the upper surface of the crank portion 30, when reflected by the lower surface of the crank portion 30, to fall by -2Shita _2, the light guide plate 15 The propagating light is in a state where the angle is changed by an apparent amount (2θ ₁ −2θ ₂ ). For this reason, if reflection is repeated m times on the upper and lower surfaces of the crank portion 30 of the light guide plate 15, the propagation light changes its angle by (2mθ ₁ −2mθ ₂ ).

Further, as shown in FIG. 7, the light that is finally reflected on the upper surface of the crank portion 30 and thus passes through the crank portion 30 is reflected m times on the upper slope of the crank portion 30, so that the lower side of the crank portion 30 Therefore, it reaches the flat plate portion constituting the main body on the right side with the angle changed by (2mθ ₁ −2 (m−1) θ ₂ ). Here, when the inclination angles of the upper and lower surfaces of the crank portion 30 are equal and θ ₁ = θ ₂ , the above equation becomes 2θ ₁ .

Here, as shown in FIG. 8, when the angle of light when reaching the flat plate portion constituting the main body portion is γ,
γ = 90−φ = 90− (α ₂ + 2θ ₁ ) = 90−arcsin (1 / n) −2θ ₁ <arcsin (1 / n)
That is, θ ₁ > (90-2 arcsin (1 / n)) / 2
Then, the critical angle is exceeded, and light is emitted from the light guide plate 15.

Conversely, the relationship between θ ₁ and θ ₂ is
(2m [theta] _1-2 (m-1) [theta] ₂ ) <(90-2arcsin (1 / n))
When the above equation is satisfied, the upper and lower surfaces of the light guide plate 15 never exceed the critical angle, and the propagation light in the light guide plate 15 is apparently in the same state as the flat light guide plate shown in FIG. Therefore, inadvertent emission from the light guide plate 15 does not occur. Therefore, even the light guide plate 15 having the crank portion 30 can emit light only by the surface treatment of the light guide plate 15 as long as the above conditions are satisfied. As a result, the length of the crank portion 30 is increased. In addition, good display quality can be obtained.

FIG. 10A shows the calculation result when θ ₁ = θ ₂ and (90−2 arcsin (1 / n)) / 2> θ ₁ , and non-uniform light is emitted from the light guide plate 15. On the other hand, FIG. 10B shows that (2mθ ₁ −2 (m−1) θ ₂ ) <(90-2arcsin (1 / n)) and (90-2arcsin (1 / n)) / 2>. in the case of theta _1, not seen exiting the non-uniform light from the light guide plate 15 at this time.

An example of a liquid crystal display device using the light guide plate 15 actually manufactured based on the above theory is shown in FIG. FIG. 11A shows a case where θ ₁ = θ ₂ = 6.4 °> (90−2 arcsin (1 / 1.59)) / 2 = 6.0 °, and the light-emitting diodes on the side edges of the light guide plate 15 In the vicinity of 20, uneven light is emitted to the light guide plate 15, which indicates that the display quality is inferior.

In contrast, FIG. 11B shows a case where θ ₁ = 6.4 °, θ ₂ = 8.2 °, and m = 2,
2 × 3 × 6.4-2 × (3-1) × 8.2 = 9.2 ° <(90-2 × arcsin (1 / 1.59)) = 21.2 °
Therefore, non-uniform light emission is not seen at the light source 20 portion of the light guide plate 15 made of light-emitting diodes, indicating that a uniform display quality is obtained. Therefore, it was confirmed that the inclination conditions of the upper and lower surfaces of the crank portion 30 of the light guide plate 15 have a high effect on display quality.

  Therefore, according to the liquid crystal display device using the light guide plate 15 according to the above embodiment, by setting the shape of the crank portion 30 of the light guide plate 15 to the above-described conditions, the display quality can be made uniform while being a narrow frame. A maintained liquid crystal display device can be manufactured.

  Although the present invention has been described above with reference to the illustrated embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea of the present invention. For example, various changes can be made to the material, specific shape, dimensions, and the like of the light guide plate 15 having the crank portion 30 in the above-described embodiment according to the purpose of use. The light guide plate is not necessarily used only for a liquid crystal display device, but can be used as an illumination means for other panel-type display devices.

  The present invention can be used in a liquid crystal display device.

It is a side view of the conventional liquid crystal display device and its light guide plate. It is a side view of the conventional flat type light-guide plate. It is a side view of the illumination means using a crank-shaped light-guide plate. It is a side view which shows the propagation of the light in the crank part of a light-guide plate. It is a longitudinal cross-sectional view which shows the whole structure of a liquid crystal display device. It is a side view of the light-guide plate used for this liquid crystal display device. It is a side view which shows the propagation of the light in a light-guide plate. It is a side view which shows the state of the reflection of the light in the upper surface of the crank part of a light-guide plate. It is a side view which shows reflection of the light in the lower surface of the crank part of a light-guide plate. It is a side view of a light guide plate from which non-uniform light is emitted and a light guide plate from which non-uniform light is not emitted. It is a top view which shows the light-guide plate which a non-uniform leak produces, and the light-guide plate which a non-uniform leak does not produce.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Light source, 2 ... Reflection plate, 3 ... Light guide plate, 3a ... Crank part, 4 ... Inclined surface, 5 ... Polarizing plate, 6 ... LCD, 7 ... Light guide plate, 8 ... Light leakage, 9 ... Flexible wiring board, 10 Liquid crystal display panel 11, 12 ... Polarizing plate, 13 ... Lens sheet, 14 ... Diffuser plate, 15 ... Light guide plate, 16 ... Reflector plate, 17 ... Flexible substrate, 20 ... Light source (light emitting diode), 23 ... Phase plate , 24 ... inner reflection layer, 30 ... crank part

Claims (13)

A light guide plate is disposed on the back side or the front side of the display panel, the light guide plate is provided with a light source at a side end thereof, and the light from the light source is emitted from the main surface through the inside of the light guide plate. In a display device that illuminates a display panel,
The light guide plate has a crank portion between a main portion having a main surface and a side end, and is bent in the thickness direction by the crank portion, and the crank portion is a surface opposite to the inclination angle of the main surface side. A display device characterized by having a large inclination angle.   The display device according to claim 1, wherein the display panel is a liquid crystal display panel.   The display device according to claim 1, wherein the light guide plate is a transparent or translucent synthetic resin molding.   The display device according to claim 1, wherein a light source disposed on a side end of the light guide plate is a light emitting diode.   The display device according to claim 1, wherein a wiring member is disposed in a space below a crank portion of the light guide plate. A light guide plate is disposed on the back side or the front side of the display panel, and a light source is disposed on the side edge of the light guide plate, and the light from the light source is emitted from the main surface through the inside to display the display panel. In a display device that illuminates,
The light guide plate has a crank part between a main part having a main surface and a side end, and is bent in the thickness direction by the crank part,
The inclination angle of the main surface side of the crank portion is θ ₁ , the inclination angle of the opposite surface is θ ₂ , the refractive index of the light guide plate is n, and the propagating light from the light source is on the main surface side of the crank portion. When m is the number of reflections on the inclined surface,
2mθ ₁ -2 (m-1) θ ₂ <90-2 arcsin (1 / n)
A display panel characterized by satisfying the above relationship. The inclination angle of the inclined surface of the main surface side of the crank portion when the theta _1,
θ ₁ <90-2 arcsin (1 / n)
The display panel according to claim 6, wherein the display panel is a display panel. The inclination angle of the inclined surface of the main surface side of the crank portion of the light guide plate when the theta _1,
θ ₁ <(90-2arcsin (1 / n)) / 2
The display panel according to claim 6, wherein the display panel is a display panel. In the light guide plate arranged on the back side or the front side of the display panel, and illuminating the display panel with light emitted from the main surface,
The surface has a crank portion between the main portion constituting the main surface and the side end on which light from the light source is incident, and is bent in the thickness direction by the crank portion, and the crank portion is on the main surface side. A light guide plate characterized in that the angle of inclination of the opposite surface is larger than the angle of inclination.   The light guide plate according to claim 9, wherein the light guide plate is a transparent or translucent synthetic resin molding. In the light guide plate arranged on the back side or the front side of the display panel, and illuminating the display panel with light emitted from the main surface,
The surface has a crank portion between a main portion constituting the main surface and a side end on which light from a light source is incident, and is bent in the thickness direction by the crank portion,
The inclination angle of the main surface side of the crank portion is θ ₁ , the inclination angle of the opposite surface is θ ₂ , the refractive index of the light guide plate is n, and the propagating light from the light source is on the main surface side of the crank portion. When m is the number of reflections on the inclined surface,
2mθ ₁ -2 (m-1) θ ₂ <90-2 arcsin (1 / n)
A light guide plate satisfying the relationship of The inclination angle of the inclined surface of the main surface side of the crank portion when the theta _1,
θ ₁ <90-2 arcsin (1 / n)
The light guide plate according to claim 11, wherein The inclination angle of the inclined surface of the main surface side of the crank portion when the theta _1,
θ ₁ <(90-2arcsin (1 / n)) / 2
The light guide plate according to claim 11, wherein the light guide plate is a light guide plate.

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