JP2004047358A - Light guide and light guide plate unit, display device, and electronic device - Google Patents

Abstract

A light guide plate can be illuminated over a wide area without increasing the number of light sources.
A light guide (13) for guiding light emitted from a light source (11) to a light guide plate, wherein a light incident surface (13a) on which light from the light source (11) is incident and a part of light incident from the light incident surface (13a) are emitted. A first reflecting surface 13d that reflects light in a direction other than the first direction, a second reflecting surface 13e that reflects light reflected by the first reflecting surface 13d in the emitting direction, and a position facing the light incident surface 13a. A light guide 13 having an emission surface 13b having at least a part of the light that has arrived after being reflected by the second reflection surface 13e and the light that has arrived directly from the light entrance surface 13a, and exits from different regions. It is arranged between the light guide.
[Selection] Fig. 2

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light guide and a light guide plate unit, a display device, and an electronic device, and more particularly to a technique that is effective when applied to extend the irradiation range of a light guide plate.
[0002]
[Prior art]
2. Description of the Related Art Today, a display unit such as an LCD (Liquid Crystal Display) used as a display unit in an electronic device employs a backlight system in which the LCD is illuminated from the back and a front light system in which the LCD is illuminated from the front. .
[0003]
In order to realize such an irradiation method, light emitted from an LED (Light Emitting Diode) as a light source is taken in from a light incident end face, and a planar light guide plate for illuminating the LCD is used. I have.
[0004]
Here, a conventional light guide plate will be described.
[0005]
FIG. 19 is an explanatory diagram showing a conventional light guide plate together with a path of incident light.
[0006]
In FIG. 19, a light source 11 such as an LED is attached to a light incident end surface of a light guide plate 12 made of a transparent resin or a glass plate, and the light guide plate 12 is illuminated by light from the LED. ing.
[0007]
[Problems to be solved by the invention]
Here, the light emitted from the LED, which is the light source, is radial light having high directivity, and the light from the LED that has entered the light guide plate is not sufficiently diffused. Therefore, as shown in FIG. 19, the light incident on the light guide plate becomes a fan-shaped illumination having a relatively narrow angle. Then, a shadow portion that is not illuminated occurs on the light guide plate.
[0008]
In order to eliminate the shadow, a large number of LEDs serving as light sources may be provided. However, an increase in the number of installed LEDs is not preferable because the cost increases accordingly.
[0009]
Therefore, an object of the present invention is to provide a technique capable of irradiating a light guide plate over a wide area without increasing the number of light sources.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, a light guide according to the present invention is a light guide that guides light emitted from a light source to a light guide plate, and includes a light incident surface on which light from the light source is incident, and a light incident surface from the light incident surface. A first reflecting surface that reflects part of the reflected light in a direction other than the emission direction, a second reflection surface that reflects the light reflected by the first reflecting surface in the emission direction, and a position facing the light incident surface. And at least a part of light reflected by the second reflecting surface and arriving at the light incident surface and at least a part of light arriving directly from the light incident surface has an emission surface from different regions.
[0011]
According to this, since the light is emitted from almost the entire area on the emission surface of the light guide, it is possible to irradiate the light guide plate over a wide area without increasing the number of light sources.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described more specifically with reference to the drawings. Here, in the attached drawings, the same members are denoted by the same reference numerals, and duplicate description is omitted. The embodiment of the present invention is a particularly useful embodiment in which the present invention is implemented, and the present invention is not limited to the embodiment.
[0013]
FIG. 1 is a perspective view showing a display device using the light guide of the present invention, FIG. 2 is a perspective view showing a light guide according to an embodiment of the present invention together with a light source from an emission surface side, and FIG. 2 is a perspective view showing the light guide from the light incident surface side, FIG. 4 is a sectional view taken along line AA in FIG. 3, and FIG. 5 is a light guide according to an embodiment of the present invention. FIG. 6 is an explanatory view showing a path of light directly reaching a light exit surface from a light entrance surface in a light guide according to an embodiment of the present invention, and FIG. 7 is an embodiment of the present invention. FIG. 8 is an explanatory view showing a path of light that has been reflected from a light incident surface to a first reflecting surface and a second reflecting surface and has reached an outgoing surface in a light guide according to an embodiment of the present invention. FIG. 8 is an embodiment of the present invention. In the light guide, the light directly reaches the light-emitting surface from the light-entering surface and is reflected from the light-entering surface by the first reflecting surface and the second reflecting surface to reach the light-emitting surface. FIG. 9 is an explanatory view showing a combined path with light, FIG. 9 is an explanatory view showing a light guide plate unit using a light guide according to an embodiment of the present invention together with a light path, and FIG. FIG. 11 is a plan view showing a light guide according to an embodiment of the present invention, FIG. 11 is an explanatory view showing a light guide according to another embodiment of the present invention from an emission surface side, and FIG. 12 is an embodiment of the present invention. FIG. 13 is a perspective view showing a light guide plate unit, FIG. 13 is an explanatory view showing a light guide plate unit according to an embodiment of the present invention together with a light path, and FIG. 14 is a light guide plate unit according to another embodiment of the present invention. FIG. 15 is an explanatory view showing a light guide plate unit according to another embodiment of the present invention together with light paths, and FIG. 16 is a perspective view showing a main part of a light guide plate unit according to still another embodiment of the present invention. FIG. 17 is a perspective view showing a light guide plate unit according to still another embodiment of the present invention. Explanatory view showing a path of light in the main part of FIG. 18 is an explanatory view showing with still another embodiment of the light guide plate unit of the light path in the form of the present invention.
[0014]
As shown in FIG. 1, a display device 10 according to the present embodiment is used for displaying an electronic device such as a mobile phone, for example, and includes a light source 11 such as an LED and a light guide plate 12 for transmitting light emitted from the light source 11. , A planar light guide plate 12 illuminated by light incident from the light incident end face through the light guide 13, and an LCD (display unit) 15 illuminated by light emitted by the light guide plate 12 And The light guide 13 and the light guide 12 constitute a light guide plate unit.
[0015]
In the present embodiment, an LED is used as the light source 11, but a light source other than the LED may be used. Further, the electronic device in which the display device 10 is used may be other than the mobile phone.
[0016]
In such a display device 10, as shown in FIGS. 2 and 3, the light guide 13 is formed at a light incident surface 13 a on which light from the light source 11 is incident and at a position facing the light incident surface 13 a. And an emission surface 13b. As shown in FIGS. 3 and 4, valley lines 13 a ₁ and ridge lines 13 a ₂ are formed on the light incident surface 13 a at concentric circles at a constant interval, and the divergence lines reduce the diffusion angle of light from the light source 11. An optical prism is formed.
[0017]
The light guide 13 has a recessed and substantially triangular step portion 13c formed on two main surfaces located in the thickness direction, and a pair of left and right symmetrical side surfaces forming the step portion 13c receive light. The first reflection surface 13d reflects a part of the light incident from the surface 13a in two directions that are away from each other. The light guide 13 has a pair of second reflection surfaces 13e that reflect the light reflected by the first reflection surface 13d in the emission direction in correspondence with the light reflected in these two directions. .
[0018]
In the present embodiment, the first reflection surface 13d reflects light in a direction orthogonal to the incident light (see FIG. 7), but reflects light in a direction other than the emission direction if the direction is other than the emission direction. It may be something.
[0019]
As shown in detail in FIG. 2, T the thickness of the light guide 13, the length of the first reflecting surface 13d in the thickness direction of the light guide 13 when the T _1, the length T ₁ from the thickness T there are long _{T 2 (= T-T 1} ) not only a first reflecting surface 13d is present the region minus. Therefore, part of the light incident from the light incident surface 13a is reflected by the first reflection surface 13d, but the other light is directed toward the emission surface 13b without being reflected by the first reflection surface 13d.
[0020]
Therefore, the light exiting surface 13b receives the light incident from the light incident surface 13a and sequentially reflected by the first reflection surface 13d and the second reflection surface 13e, and the light incident from the light incident surface 13a. The light that directly arrives without being reflected by 13d and 13e is emitted.
[0021]
Then, as described later, the first reflection surface 13d and the first reflection surface 13d are arranged such that light arriving from the second reflection surface 13e and light arriving directly from the light entrance surface 13a exit from mutually different regions of the emission surface 13b. The angle of the second reflection surface 13e is set.
[0022]
The first reflecting surface 13d may be formed on any one of the two main surfaces, and may be formed on one side instead of a pair. When the first reflection surface 13d is formed on only one side, the second reflection surface 13e only needs to be formed on only one side corresponding thereto.
[0023]
Here, the direction orthogonal to the thickness direction of the light guide 13 on the first reflection surface 13d may be formed in a straight line, but may be formed in a curved or arcuate shape.
[0024]
As shown in FIG. 5, the first reflection surface 13 d has an inclination angle θ of 5 to 15 ° with respect to a perpendicular to the thickness direction of the light guide 13, It is desirable that it be in the direction toward the center in the vertical direction. By doing so, the amount of light entering the light guide plate 13 increases, so that the LCD can be illuminated more brightly.
[0025]
Next, a light path in the light guide 13 having the above structure will be described.
[0026]
As shown in FIG. 6, the light that has directly reached the light-emitting surface 13b from the light-entering surface 13a is emitted from the region of the light-emitting surface 13b where the width is reduced due to the formation of the step 13c, that is, the first reflecting surface 13d. I do. Further, the light reflected from the light incident surface 13a on the first reflection surface 13d and the second reflection surface 13e and reaching the light exit surface 13b exits from a wide area on the light exit surface 13b as shown in FIG. I do. Therefore, as shown in FIG. 8 which combines and expresses these lights, light is emitted from almost the entire area of the emission surface 13 b of the light guide 13.
[0027]
Therefore, in the light guide plate unit using such a light guide 13, as shown in FIG. 9, it is possible to irradiate the light guide plate 12 over a wide range without increasing the number of light sources 11. That is, an illumination width that one light source 11 covers for the light guide plate 12 is determined, a light guide 13 having an emission surface 13 b corresponding to the illumination width is created, and the light guide 13 is attached to the light guide plate 12, thereby making it necessary and necessary. A light guide plate unit that can be illuminated by a sufficient number of light sources 11 is obtained.
[0028]
In the present embodiment, light that directly reaches light-emitting surface 13b from light-entering surface 13a is diffused (FIGS. 6 and 8), and light that reaches light-emitting surface 13b after being reflected by second reflecting surface 13e. Is not diffused (FIGS. 7 and 8), but the diffusion angle can be freely set and is not limited to the one shown in the present embodiment.
[0029]
Further, in the present embodiment, the light directly reaching light emitting surface 13b from light incident surface 13a and light reaching light emitting surface 13b after being reflected by second reflecting surface 13e are not overlapped with light from light emitting surface 13b. Although light is emitted from mutually different regions, a part of both lights may be emitted from mutually overlapping regions. That is, it is only necessary that at least a part of both lights is emitted from mutually different areas on the emission surface 13b.
[0030]
Here, when there is a difference in light amount between the light directly reaching the light exit surface 13b from the light incident surface 13a and the light reaching the light exit surface 13b after being reflected by the second reflection surface 13e, luminance unevenness occurs. The luminance balance of the light guide plate 12 will be lost. To achieve the luminance balance, the area S1 of the _first reflection surface 13d that reflects the incident light and the direction perpendicular to the traveling direction of the incident light that directly reaches the emission surface 13b from the light entrance surface 13a are set. the ratio between the area S ₂ may be adjusted. This can be easily performed by changing the height of the step 13c.
[0031]
When the area S ₁ is smaller than the area S _2, the light amount of the light that directly reaches the light exit surface 13 b from the light incident surface 13 a is reflected by the second reflection surface 13 e and reaches the light exit surface 13 b. Therefore, the fan-shaped light beam becomes stronger, and a shadow portion that is not illuminated on the light guide plate 12 is generated. When the area S ₁ is larger than the area S ₂ , the amount of light reflected by the second reflection surface 13 e and reaching the emission surface 13 b is equal to the amount of light directly reaching the emission surface 13 b from the light incident surface 13 a. , The light in the light guide plate 12 near the light source 11 becomes darker.
[0032]
In the above description, the side surface forming the step portion 13c is the first reflection surface 13d. For example, as shown in FIGS. 10 and 11, the side surface forming the groove portion 13f formed on the main surface is referred to as the first reflection surface 13d. The first reflection surface 13d may be used.
[0033]
Further, the light guide 13 and the light guide plate 12 may be formed integrally with each other. Here, FIG. 12 shows a light guide plate unit in which the light guide 13 and the light guide 12 shown in FIG. 2 are integrally formed, and FIG. 13 shows a light path in the light guide plate unit. Further, FIG. 14 shows a light guide plate unit in which the light guide 13 and the light guide 12 shown in FIG. 10 are integrally formed, and FIG. 15 shows a light path in the light guide plate unit.
[0034]
Further, as a light guide plate unit having a planar light guide plate 14 illuminated by incident light, as shown in FIGS. 16 to 18, a light incident end face 14 a on which light from the light source 11 is incident, and a light incident end face 14 a A third reflecting surface 14b formed with a prism that reflects a part of the light incident from the light guide plate 14 in a direction in which the light spreads in the light guide plate 14 and allows the other light to pass through the third reflecting surface 14b; A fourth reflecting surface 14d on which a prism that reflects light in the direction of light passing through the reflecting surface 14b may be formed.
[0035]
As shown in the drawing, the third reflecting surface 14b is formed as a part of a wall surface forming a through hole 14c penetrating in the thickness direction, and is formed on the third reflecting surface 14b and the fourth reflecting surface 14d. The prism is an aggregate of valleys and ridges extending at regular intervals along the thickness direction.
[0036]
According to such a light guide plate unit, the light that has passed through the third reflecting surface 14b, exited into the through-hole 14c, which is a space, and entered again, and sequentially on the third reflecting surface 14b and the fourth reflecting surface 14d. The light guide plate unit 14 is illuminated over a wide area by the reflected light.
[0037]
【The invention's effect】
As described above, according to the present invention, since light is emitted from almost the entire area of the light emitting surface of the light guide, it is possible to irradiate the light guide plate over a wide area without increasing the number of light sources. Is obtained.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a display device using the light guide of the present invention.
FIG. 2 is a perspective view showing a light guide according to an embodiment of the present invention together with a light source from an emission surface side.
FIG. 3 is a perspective view showing the light guide of FIG. 2 from the light incident surface side.
FIG. 4 is a sectional view taken along the line AA of FIG. 3;
FIG. 5 is a side view showing a light guide according to an embodiment of the present invention in an enlarged manner from an emission surface side.
FIG. 6 is an explanatory diagram showing a path of light directly reaching a light exit surface from a light entrance surface in the light guide according to one embodiment of the present invention.
FIG. 7 is an explanatory diagram showing a path of light that has been reflected by a first reflection surface and a second reflection surface from a light entrance surface to reach a light exit surface in a light guide according to an embodiment of the present invention. .
FIG. 8 shows a light guide according to an embodiment of the present invention, in which light directly reaches a light-emitting surface from a light-entering surface and is reflected from the light-entering surface by a first reflecting surface and a second reflecting surface. FIG. 4 is an explanatory diagram showing a combined path with light that has reached the point.
FIG. 9 is an explanatory diagram showing a light guide plate unit using a light guide according to an embodiment of the present invention, together with a light path.
FIG. 10 is a plan view showing a light guide according to another embodiment of the present invention.
FIG. 11 is an explanatory view showing a light guide according to another embodiment of the present invention from an emission surface side.
FIG. 12 is a perspective view showing a light guide plate unit according to an embodiment of the present invention.
FIG. 13 is an explanatory diagram showing a light guide plate unit according to an embodiment of the present invention together with a light path.
FIG. 14 is a perspective view showing a light guide plate unit according to another embodiment of the present invention.
FIG. 15 is an explanatory diagram showing a light guide plate unit according to another embodiment of the present invention together with a light path.
FIG. 16 is a perspective view showing a main part of a light guide plate unit according to still another embodiment of the present invention.
FIG. 17 is an explanatory diagram showing a light path in a main part of a light guide plate unit according to still another embodiment of the present invention.
FIG. 18 is an explanatory diagram showing a light guide plate unit according to still another embodiment of the present invention, together with a light path.
FIG. 19 is an explanatory view showing a conventional light guide plate together with a path of incident light.
[Explanation of symbols]
Reference Signs List 10 display device 11 light source 12 light guide plate 13 light guide 13a light entrance surface 13a ₁ valley line 13a ₂ ridge line 13b exit surface 13c step portion 13d first reflection surface 13e second reflection surface 13f groove portion 14 light guide plate 14a light entrance end surface 14b Third reflective surface 14c Through hole 14d Fourth reflective surface 15 LCD (display unit)
θ tilt angle

Claims (13)

A light guide for guiding light emitted from the light source to the light guide plate,
A light incident surface on which light from the light source is incident,
A first reflecting surface that reflects part of light incident from the light incident surface in a direction other than the emission direction;
A second reflecting surface that reflects light reflected by the first reflecting surface in an emission direction;
An emission surface formed at a position facing the light incident surface, wherein at least a part of light that has arrived by being reflected by the second reflection surface and light that has directly arrived from the light incident surface exits from mutually different regions; A light guide, comprising: The first reflection surface is formed as a pair on at least one of two main surfaces located in the thickness direction of the light guide, and two directions in which light incident from the light entrance surface are separated from each other. Reflected on
2. The light guide according to claim 1, wherein a pair of the second reflection surfaces is formed corresponding to the light reflected in these two directions. 3. The light guide according to claim 1, wherein the first reflection surface reflects light in a direction orthogonal to incident light. The light guide according to any one of claims 1 to 3, wherein a direction perpendicular to a thickness direction of the light guide on the first reflection surface is formed to be curved. The light guide according to claim 4, wherein a direction perpendicular to a thickness direction of the light guide on the first reflection surface is formed in an arc shape. The first reflection surface has an inclination angle of 5 to 15 ° with respect to a perpendicular to a thickness direction of the light guide, in a direction in which reflected light is directed toward a center in a thickness direction of the light guide. The light guide according to claim 1, wherein the light guide is provided. The said 1st reflection surface is a side surface which comprises the concave-shaped step part formed in the said main surface, or a side surface which comprises the groove part formed in the said main surface, The Claims 1-6 characterized by the above-mentioned. The light guide according to claim 1. The light guide according to claim 1, wherein a condensing prism that narrows a diffusion angle of light from the light source is formed on the light incident surface. A light guide according to any one of claims 1 to 8,
A planar light guide plate illuminated with light incident from a light incident end face through the light guide, and a light guide plate unit. The light guide plate unit according to claim 9, wherein the light guide and the light guide plate are formed integrally with each other. A light guide plate unit having a planar light guide plate illuminated by incident light,
A light incident end face on which light from a light source is incident,
A prism that is formed as a part of a wall surface forming a through hole penetrating in the thickness direction, reflects a part of light incident from the light incident end face in a direction in which the light guide plate spreads, and passes another prism is formed. A third reflecting surface;
A light reflecting plate having a prism formed to reflect light reflected by the third reflecting surface in a direction of light passing through the third reflecting surface. A light source,
A light guide plate unit according to any one of claims 9 to 11,
A display unit illuminated by the light guide plate unit. An electronic device comprising the display device according to claim 12.

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