JP2003203515A - Luminaire, its designing method, its manufacturing method, display device, and light guiding body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a luminaire capable of emitting uniform illuminating light. <P>SOLUTION: This luminaire has a light source and a light guiding body. The light guiding body has a first side face to receive light from the light source, a second side face facing the first side face, a light emitting face almost perpendicular to the first side face, and a confronting face facing the light emitting face. The confronting face of the light guiding body is provided along a first direction perpendicular to the first side face in a prescribed period, and has a plurality of grooves extending in a second direction crossing the first direction. Each groove is composed of a plurality of faces, and the face closest to the first side face is an inclined face inclined relative to the first direction. An angle α made by the inclined face to the first direction, the refractive index n of the light guiding body, the thickness T of the light guiding body along the direction of the normal line of the light emitting face, the length L of the light guiding body along the first direction, the depth h of a plurality of grooves and the period p of a plurality of grooves satisfy n sinä90-α-tan<SP>-1</SP>(2 T/L)}≥1 and 2T/L≤h/p≤tan α. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device, a lighting device designing method, a lighting device manufacturing method, a display device, and a light guide. In particular, the present invention relates to a lighting device that is preferably used as a backlight or a front light of a liquid crystal display device.

[0002]

2. Description of the Related Art A liquid crystal display device is a CRT (Cathod).
e Ray Tube), PDP (Plasma Di)
spray Panel) or EL (Electr)
Unlike self-luminous displays such as o Luminescence, characters and images are displayed by controlling the amount of reflected or transmitted light emitted from the outside, so it is roughly classified into a reflective type and a transmissive type. .

The transmissive liquid crystal display device is provided with, for example, polarizing plates arranged on the light incident side and the light emitting side, and the polarization state of light incident through the incident side polarizing plate is modulated by the liquid crystal layer. Then, an image is displayed by controlling the amount of light transmitted through the polarizing plate on the emission side. In general, an illumination device called a backlight that illuminates a transmissive liquid crystal display element from the rear side (back side) is arranged on the incident side.

On the other hand, the reflection type liquid crystal display device is provided with, for example, one polarizing plate and a reflecting plate, and light incident through the polarizing plate is reflected by the reflecting plate and reaches the polarizing plate again.
An image is displayed by modulating the polarization state of light with a liquid crystal layer and controlling the amount of light transmitted through a polarizing plate on the exit side. Therefore, although the display using ambient light is possible, the display brightness is highly dependent on the surrounding environment, and the display may not be recognized at all in the darkness such as at night. Therefore, an illuminating device called a front light that illuminates the reflective liquid crystal display element from the front side (observer side) is required in case that sufficient ambient light cannot be obtained.

Illumination devices called back lights and front lights described above have been proposed in the past, and, for example, in Japanese Laid-Open Patent Publication No. 10-208529, FIG.
An illumination device (planar light source device) 700 as shown in (a) and (b) is disclosed. 11A is a side view schematically showing the lighting device 700, and FIG.
FIG. 6 is a side view schematically showing a resin substrate 720 of the lighting device 700 in an enlarged manner.

As shown in FIG. 11A, the lighting device 700 includes a linear light source 710 and a resin substrate 72 as a light guide.
It has 0 and. The resin substrate 720 is a linear light source 710.
An incident surface 721 on which light from is incident, and substantially orthogonal to this,
It has an emission surface 723 through which light is emitted and a facing surface 724 that faces the emission surface 723.

The facing surface 724 of the resin substrate 720 is shown in FIG.
As shown in (b), the flat portion 724b and the plurality of grooves 72 are formed.
4a and 4a. Each groove 724a faces the incident surface 721 and is inclined with respect to the flat portion 724b.
1 and an inclined surface 724a2 that does not face the incident surface 721 and is inclined with respect to the flat portion 724b. Groove 7
The angle α formed by the inclined surface 724a1 of 24a with respect to the flat portion 724b is 40 ° to 55 °, and the inclined surface 724a2
The angle α ′ formed by the flat portion 724b is 60 ° to 9 °.
It is 0 °.

In the illuminating device 700 having the above-described structure, the light incident from the linear light source 710 into the inside of the resin substrate 720 via the incident surface 721 is repeatedly totally reflected by the emitting surface 723 and the facing surface 724. It propagates inside the resin substrate 720. A part of the light propagating inside the resin substrate 720 is reflected by the inclined surface 724a1 of the facing surface 724 and emitted from the emission surface 723.

The groove 724 is located farther from the linear light source 710.
By reducing the period p of a, increasing the depth h of the groove 724 as the distance from the linear light source 710 increases, or combining these configurations, the illumination light is uniformly emitted from the entire emission surface 723. Can be made.

Further, Japanese Patent Laid-Open No. 2001-14921 discloses an illuminating device 800 as shown in FIGS. 12, 13A and 13B. FIG. 12 shows a lighting device 8.
00 is a perspective view schematically showing 00, FIG. 13 (a) is a top view schematically showing the point light source 810 and the first light guide 820 included in the lighting device 800, and FIG. 13 (b) is ,
It is a top view which expands and shows the 1st light guide 820 typically.

Illumination device 800, as shown in FIG.
Point light source 810, first light guide 820, and second light guide 8
30 and 30.

As shown in FIG. 13A, the first light guide 820 has an incident surface 82 on which light from the point light source 810 is incident.
1 and an emission surface 823 that is substantially orthogonal to this and emits light,
It has a facing surface 824 facing the emitting surface 823.

The facing surface of the first light guide 820 is shown in FIG.
As shown in (b), the flat portion 824b and the plurality of grooves 82 are formed.
4a and 4a. Each groove 824a faces the incident surface 821 and is inclined with respect to the flat portion 824b.
1 and an inclined surface 824a2 that does not face the incident surface 821 and is inclined with respect to the flat portion 824b.

As the second light guide 830, the above-mentioned Japanese Patent Laid-Open No.
A resin substrate such as that disclosed in JP-A-0-208529 can be used.

In the illumination device 800 having the above-mentioned structure, the light incident from the point light source 810 into the inside of the first light guide 820 through the incident surface 821 is totally reflected by the emitting surface 823 and the facing surface 824. Repeating the above, the first light guide 820
Propagate inside. A part of the light propagating inside the first light guide 820 is reflected by the inclined surface 824a1 of the facing surface 824, is emitted from the emission surface 823, and is incident on the second light guide 830.

When the depth h of the groove 824a of the facing surface 824 is constant and the period p of the groove 824a is made smaller as it goes away from the point light source 810, the illumination light can be uniformly emitted from the entire emission surface 823. . The minimum value of the period p of the groove 824a is 0.01 considering the processing accuracy of the groove 824a.
mm, on the other hand, the maximum value of the cycle p is not visually observed bright and dark (the groove 824a is not visually observed due to separation)
For this, it is 0.2 mm. In the first light guide 820 exemplified in the above publication, the depth h of the groove 824a is 0.
It is 01 mm, and the angle α formed by the inclined surfaces 824a1 and 824a2 of the groove 824a with respect to the flat portion 824b of the facing surface 824 is 54 °.

[0017]

However, the above-mentioned JP-A-10-208529 and JP-A-2001-149.
The inventor of the present application has found that the illumination device disclosed in Japanese Patent Publication No. 21 has the following problems.

In the illumination device 700 disclosed in Japanese Unexamined Patent Publication No. 10-208529, the optimum value of the angle α formed by the groove 724a formed in the facing surface 724 of the resin substrate 720 as a light guide and the flat portion 724b is: Since it varies depending on the size of the resin substrate 720, it is necessary to find the optimum value of α within the range of 40 ° to 55 °.

In order to emit uniform illumination light from the entire emission surface 723 of the resin substrate 720, the linear light source 7
It is necessary to reduce the period p of the groove 724a as it is farther away from 10, or to make the depth h of the groove 724a deeper as it is farther from the linear light source 710, or to combine these configurations. Groove 724a at
It is necessary to consider various combinations of the depth h and the value of the period p. Furthermore, based on the studied design values, the resin substrate 7
When processing 20 as well, since the depth h of the groove 724a and the period p change within the surface of the facing surface 724, complicated processing is required.

Also, in the illumination device 800 disclosed in Japanese Patent Laid-Open No. 2001-14921, the groove 824a of the facing surface 824 of the first light guide 820 has the flat portion 82.
Since the optimum value of the angle α formed with 4b changes depending on the size of the first light guide 820, it is necessary to find the optimum value of α. Further, the groove 824 becomes farther away from the point light source 810.
In order to reduce the cycle p of a, it is necessary to study the optimum cycle p according to the size of the first light guide 820 and the depth h of the groove, which requires complicated design and processing.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a simple designing method and manufacturing method of an illuminating device, and to provide a uniform illuminating light. An object of the present invention is to provide a light body, a lighting device, and a display device including the same.

[0022]

An illumination device according to the present invention includes a light source, a first side surface for receiving light from the light source, a second side surface facing the first side surface, the first side surface and the first side surface. Illumination including a light guide body that is located between two side surfaces and that is substantially orthogonal to the first side surface, and has a facing surface that faces the exit surface via the first and second side surfaces. In the device, the facing surface of the light guide body is a plurality of grooves provided at a predetermined cycle along a first direction orthogonal to the first side surface, and the groove intersects the first direction. It has a plurality of grooves extending in two directions, each of the plurality of grooves is composed of a plurality of surfaces, and among the plurality of surfaces forming each of the plurality of grooves, the first side surface is the most The near surface is an inclined surface inclined with respect to the first direction, and the inclined surface is the first surface. An angle α with the direction, a refractive index n of the light guide, a thickness T of the light guide along the normal direction of the exit surface, a length L of the light guide along the first direction, The depth h of the plurality of grooves and the period p of the plurality of grooves are n ·
It has a configuration satisfying the relationships of sin {90-α-tan ⁻¹ (2T / L)} ≧ 1 and 2T / L ≦ h / p ≦ tan α, and thereby the above object is achieved.

An angle α formed by the inclined surface and the first direction,
The depth h of the plurality of grooves and the period p of the plurality of grooves are
It is preferable that it is constant within the surface of the facing surface.

Of the plurality of surfaces forming each of the plurality of grooves, the surface closest to the second side surface has the further light source provided on the second side surface side of the light guide body, and The tilted surface may be inclined with respect to the first direction at the same angle as the tilted surface closest to the first side surface. In the case of having such a structure, the tilted surface forms an angle with the first direction. α, the depths h of the plurality of grooves, the period p of the plurality of grooves, the thickness T of the light guide along the normal direction of the emission surface, and the light guide of the light guide along the first direction. It is preferable that the length L satisfies the relationship of 2T / L ≦ h / p ≦ tan α / 2.

The display device according to the present invention comprises the illuminating device having the above-mentioned structure and the reflection type display panel provided on the opposite side of the illuminating device from the observer. Is achieved.

Alternatively, the display device according to the present invention comprises the illuminating device having the above-mentioned structure and the transmissive display panel provided on the observer side with respect to the illuminating device. To be achieved.

The light guide according to the present invention has a first side surface for receiving light from a light source, and a second side surface facing the first side surface.
Located between the first side surface and the second side surface, and
A light guide body having an emission surface that is substantially orthogonal to a side surface, and an opposed surface that opposes the emission surface via the first and second side surfaces, wherein the opposed surface is a first surface that is orthogonal to the first side surface. A plurality of grooves provided in a predetermined cycle along one direction,
A plurality of grooves extending in a second direction intersecting the first direction, each of the plurality of grooves is formed of a plurality of surfaces, and a plurality of surfaces of the plurality of surfaces forming each of the plurality of grooves are formed. Of these, the surface closest to the first side surface is the first
An inclined surface inclined with respect to the direction, an angle α formed by the inclined surface with the first direction, a refractive index n, a thickness T along the normal line direction of the emission surface, and a length along the first direction. Is L, the depth h of the plurality of grooves and the period p of the plurality of grooves are n ·
It has a configuration satisfying the relationships of sin {90-α-tan ⁻¹ (2T / L)} ≧ 1 and 2T / L ≦ h / p ≦ tan α, and thereby the above object is achieved.

An angle α formed by the inclined surface and the first direction,
The depth h of the plurality of grooves and the period p of the plurality of grooves are
It is preferable that it is constant within the surface of the facing surface.

Of the plurality of surfaces forming each of the plurality of grooves, the surface closest to the second side surface is at the same angle as the inclined surface closest to the first side surface with respect to the first direction. The structure may be inclined, and in the case of having such a structure, the angle α formed by the inclined surface with the first direction, the depth h of the plurality of grooves, the cycle p of the plurality of grooves, The thickness T along the normal line direction of the emission surface and the length L along the first direction are 2T / L ≦ h / p ≦ ta.
It is preferable to satisfy the relationship of nα / 2.

A method of designing an illuminating device according to the present invention includes a light source, a first side surface for receiving light from the light source, a second side surface facing the first side surface, the first side surface and the second side surface. An emission surface located between the first side surface and substantially orthogonal to the first side surface,
A light guide body having a facing surface facing the emitting surface via the first and second side surfaces, wherein the facing surface of the light guide body is in a first direction orthogonal to the first side surface. A plurality of grooves provided along a predetermined cycle, the plurality of grooves extending in a second direction intersecting the first direction, and each of the plurality of grooves includes a plurality of surfaces. Of the plurality of surfaces forming each of the plurality of grooves, a surface closest to the first side surface is a method for designing an illumination device, which is an inclined surface inclined with respect to the first direction, The angle α formed by the inclined surface with the first direction, the refractive index n of the light guide, the thickness T of the light guide along the normal direction of the emission surface, and the guide along the first direction. At least 1 of the length L of the light body and the emission angle θ at which the most light is emitted from the emission surface. And a numerical value other than at least one of the above-mentioned decided at least 2α +
tan ⁻¹ (2T / L) + sin ⁻¹ (sin θ / n) = 9
Determining to satisfy the relationship of 0, thereby achieving the above object.

In the step of determining a numerical value other than the determined at least one, the determined at least one
Numerical values other than two are n · sin {90-α-tan ^-1 (2
It is preferable to determine such that the relationship of (T / L)} ≧ 1 is also satisfied.

In the step of determining a numerical value other than the determined at least one, the determined at least one
2T / L ≦ h / p ≦ tanα, where the numerical values other than two and the numerical values of the depth h of the plurality of grooves and the period p of the plurality of grooves are
It is preferable to determine so as to satisfy the relationship of.

A method of manufacturing an illumination device according to the present invention uses the above-described illumination device design method to design the illumination device, and based on each numerical value determined in the process of designing the illumination device, Producing a light guide, whereby the above object is achieved.

[0034]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to the embodiments below.

First, a method of designing an illumination device according to the present invention will be described with reference to FIGS. 1 (a) and 1 (b). FIG. 1A shows a light guide 20 having a groove 24 a in the facing surface 24.
It is a side view which shows typically the illuminating device 100 provided with.
FIG. 1B is a side view schematically showing the light guide 20 included in the lighting device 100 in an enlarged manner.

As shown in FIG. 1A, the lighting device 100 includes a light source 10 and a light guide 20.

The light guide body 20 includes a first side surface (incident side surface) 21 for receiving light from the light source 10, a second side surface 22 facing the first side surface 21, a first side surface 21 and a second side surface 22. It has an emission surface 23 that is located in between and is substantially orthogonal to the first side surface 21, and an opposing surface 24 that faces the emission surface 23 via the first side surface 21 and the second side surface 22.

As shown in FIG. 1B, the facing surface 24 of the light guide 20 has a plurality of grooves 24a provided in a predetermined cycle along a direction orthogonal to the first side surface 21. The plurality of grooves 24a extend in a direction intersecting the direction orthogonal to the first side surface 21. The facing surface 24 has a flat portion 24b located between the grooves 24a and substantially parallel to the direction orthogonal to the first side surface 21 (that is, substantially parallel to the emission surface 23).

Each of the plurality of grooves 24a has a plurality of surfaces 2
4a1 and 24a2. Multiple grooves 2
A plurality of surfaces 24a1 and 24 constituting each of 4a
Of a2, the surface 24a1 closest to the first side surface 21
Is inclined with respect to the direction orthogonal to the first side surface 21 (that is, inclined with respect to the flat portion 24b of the facing surface 24).
It is the inclined surface 24a1.

Of the light that enters the light guide 20 from the light source 10 through the first side surface 21, if the light that uniformly reaches the entire facing surface 24 is the principal ray, then FIG. As shown in (b), the principal ray PR is a ray inclined by an angle β (°) from the optical axes A1-A2 (shown by broken lines in the figure) of the light source 10 and the light guide 20. Here, the exit surface 2
3, where T is the thickness of the light guide body 20 along the normal direction and L is the length of the light guide body 20 along the direction orthogonal to the first side face 21, the chief ray PR with respect to the optical axis A1-A2 is shown. Inclination angle β of
Is represented by the following formula (1).

Β = tan ⁻¹ (2T / L) (1) In addition, the principal ray PR reaching the entire surface of the facing surface 24 is the groove 2
The light enters and is reflected by the inclined surface 24a1 of 4a, and the incident / reflection angle γ (°) at that time is expressed by the following equation (2). Note that α (°) in the equation (2) is the inclined surface 24a of the groove 24a.
1 is an inclination angle formed with respect to the direction orthogonal to the first side surface 21 (here, an inclination angle formed with respect to the flat portion 24b).

Γ = 90−α−β = 90−α−tan ⁻¹ (2T / L) (2) The light reflected at the incident / reflection angle γ at the inclined surface 24 a 1 of the groove 24 a travels toward the emission surface 23. However, the incident angle θ ′ of this light on the emission surface 23 and the emission angle θ from the emission surface 23 are expressed by the following equations (3) and (4), where n is the refractive index of the light guide 20. Meet

Β + 2γ−θ ′ = 90 (3) n · sin θ ′ = sin θ (4) From the above equations (1), (2), (3) and (4),
The angle α formed between the inclined surface 24a1 of the facing surface 24 and the direction orthogonal to the first side surface 21, the refractive index n of the light guide 20, the exit surface 23
The thickness T of the light guide 20 along the normal direction of the first side surface 21
It can be seen that the length L of the light guide 20 along the direction orthogonal to and the emission angle θ at which most light is emitted from the emission surface 23 satisfy the relationship of the following expression (5).

2α + tan ⁻¹ (2T / L) + sin ⁻¹ (sin θ / n) = 90 (5) Therefore, the inclination angle α of the inclined surface 24 a 1, the refractive index n of the light guide body 20, and the light guide body 20 After determining at least one of the thickness T, the length L of the light guide body 20, and the emission angle θ of the light from the emission surface 23 to a desired numerical value, the remaining values satisfy the relationship of the expression (5). By determining the numerical value of, the lighting device 100 can be easily designed.

That is, in the method of designing the lighting device according to the present invention, the inclination angle α of the inclined surface 24a1, the refractive index n of the light guide 20, the thickness T of the light guide 20, the length L of the light guide 20, and At least one of the outgoing angles θ of the light from the outgoing surface 23
To determine a desired numerical value and to determine a numerical value other than at least one of the determined numerical values so as to satisfy the relationship of the equation (5), thereby designing the lighting device. It can be performed easily.

For example, if the thickness T, the length L and the refractive index n of the light guide body 20 and the emission angle θ of the light from the emission surface 23 are set to desired values, the inclination angle α of the inclined surface 24a1 is determined. Can be uniquely determined based on the equation (5), and it is not necessary to repeat the complicated design and processing to study the optimum numerical value.

Further, the inclination angle α of the inclined surface 24a1, the thickness T, the length L and the refractive index n of the light guide 20 are expressed by the following equation (6).
Is satisfied, the chief ray P reaching the inclined surface 24a1
R can be totally reflected.

N · sin γ = n · sin {90−α−tan ⁻¹ (2T / L)} ≧ 1 (6) That is, a numerical value other than the one determined to have a desired numerical value should satisfy Expression (5). In the deciding step, by deciding so that the relation of equation (6) is also satisfied,
The principal ray PR can be totally reflected by the inclined surface 24a1 of the groove 24a.

Further, the depth h and the period p of the groove 24a are
When the following expression (7) is satisfied, it becomes possible for all the principal rays PR to reach the inclined surface 24a1 of the groove 24a.

Tan β = 2T / L ≦ h / p (7) Here, the ratio h / p between the depth h of the groove 24 a and the period p is t
Since it cannot be more than an α, the following equation (8) is derived from the equation (7).

2T / L ≦ h / p ≦ tan α (8) Therefore, the depth h of the groove 24a, the period p of the groove 24a, the thickness T of the light guide 20 and the length L of the light guide 20 are expressed by the following equations. When (8) is satisfied, all the principal rays PR reach the inclined surface 24a1 of the groove 24a.

That is, in the step of determining a numerical value other than the desired numerical value so as to satisfy the expression (5), the depth h and the period p of the groove 24a are set so as to satisfy the relationship of the expression (8). Therefore, all the principal rays PR can reach the inclined surface 24a1 of the groove 24a.

As described above, according to the method of designing an illumination device of the present invention, the inclination angle α of the inclined surface 24a1 and the light guide 20 are used.
, The thickness T of the light guide 20, the length L of the light guide 20
Since at least one of the output angles θ of the light from the output surface 23 is determined to be a desired numerical value, numerical values other than the determined at least one are determined so as to satisfy the relationship of the expression (5). It is possible to easily design the lighting device.

When the illuminating device is designed so as to satisfy the relation of the equation (6), the principal ray PR is directed to the inclined surface 2 of the groove 24a.
4a1 can be used for total reflection, and by designing to satisfy the relationship of the expression (8), all principal rays PR can reach the inclined surface 24a1 of the groove 24a.

By designing to satisfy both the equations (6) and (8), all the principal rays PR reach the inclined surface 24a1 of the groove 24a uniformly and are totally reflected by the inclined surface 24a1. Since the light is emitted from 23 at a constant emission angle θ, uniform illumination light can be obtained. Further, even if the depth h and the period p of the groove 24 are constant in the plane of the facing surface 24, uniform illumination light can be obtained. Therefore, by making the depth h and the period p constant in the plane, Compared to the case where the depth h and the period p change in the plane, the design of the illumination device and the processing of the light guide can be performed easily.

In the above description, the light guide 20
Although the case where the light source 10 is provided only on the first side surface 21 side of the above is described, the method of designing the lighting device according to the present invention is not limited to this, and the lighting device 200 shown in FIGS. As described above, the light guide body 20 can be used even when the light source 10 ′ is provided on the second side surface 22 side.

As shown in FIG. 2A, the illumination device 200 includes light sources 10 and 10 'and a light guide 20.

The light guide body 20 faces the first side surface (incident side surface) 21 for receiving light from the light source 10 and the first side surface 21,
Second side surface (incident side surface) 22 that receives light from the light source 10 '
Is located between the first side surface 21 and the second side surface 22,
Emission surface 23 substantially orthogonal to the side surface 21 and the second side surface 22
And a facing surface 24 facing the emitting surface 23 via the first side surface 21 and the second side surface 22.

As shown in FIG. 2B, the facing surface 24 of the light guide body 20 has a plurality of grooves provided in a predetermined cycle along a direction orthogonal to the first side surface 21 (second side surface 22). 24a. The plurality of grooves 24a are formed on the first side surface 21 (second side surface 2).
It extends in a direction intersecting the direction orthogonal to 2). Further, the facing surface 24 is located between the grooves 24 a, and the first side surface 21
It has a flat portion 24b that is substantially parallel to the direction orthogonal to the (second side surface 22) (that is, substantially parallel to the emission surface 23).

Each of the plurality of grooves 24a has a plurality of surfaces 2
4a1 and 24a2. Multiple grooves 2
A plurality of surfaces 24a1 and 24 constituting each of 4a
a2 is inclined with respect to the direction orthogonal to the first side surface 21 (that is, with respect to the flat portion 24b of the facing surface 24). The inclined surface 24a1 close to the first side surface 21 and the surface 24a2 close to the second side surface 22 are both inclined at the same inclination angle α.

Also when designing the illumination device 200 shown in FIGS. 2A and 2B, the inclined surfaces 24a1 and 24a are provided.
a2, inclination angle α, refractive index n of light guide 20, light guide 20
Of the thickness T, the length L of the light guide 20 and the emission angle θ of the light from the emission surface 23, at least one of them is determined to a desired value, and the other values than the determined values are given by the formula (5). By deciding so as to satisfy the relationship, it becomes possible to easily design the lighting device.

When the design is made so as to satisfy the relation of the expression (6), the principal ray PR can be totally reflected by the inclined surface 24a1 of the groove 24a.

In the illumination device 200, the second side surface 22
The inclined surface 24a2 close to the inclined surface 2a close to the first side surface 21
Since it is inclined at the same inclination angle α as 4a1, the groove 24a
The ratio h / p between the depth h and the period p cannot exceed tan α / 2. Therefore, if the illumination device is designed to satisfy the relationship of the following expression (8 ′), it becomes possible to cause all the principal rays PR to reach the inclined surface 24a1 of the groove 24a.

2T / L ≦ h / p ≦ tan α / 2 (8 ′) When the design is performed so as to satisfy the relationships of both Expression (6) and Expression (8 ′), all the principal rays PR of the groove 24a. The inclined surfaces 24a1 and 24a2 are uniformly reached to reach the inclined surface 24a.
Since the light is totally reflected at 1 and 24a2 and is emitted from the emission surface 23 at a constant emission angle θ, uniform illumination light can be obtained. Further, even if the depth h and the period p of the groove 24 are constant in the plane of the facing surface 24, uniform illumination light can be obtained. Therefore, by making the depth h and the period p constant in the plane, Compared to the case where the depth h and the period p change in the plane, the design of the illumination device and the processing of the light guide can be performed easily.

The method for manufacturing a lighting device according to the present invention includes the step of designing a lighting device using the above-described designing method for a lighting device.

More specifically, the method for manufacturing a lighting device according to the present invention is based on the step of designing a lighting device using the above-described designing method for a lighting device and the numerical values determined in the step of designing the lighting device. And the step of producing the light guide body 20. The process of making the light guide 20 is performed using a known method. Therefore, according to the method for manufacturing a lighting device of the present invention, the lighting device can be simply and efficiently manufactured.

Next, an illuminating device according to an embodiment of the present invention will be described.

(Embodiment 1) An illumination device 300 according to Embodiment 1 of the present invention is shown in FIGS. 3, 4 (a) and 4 (b). FIG. 3 is a perspective view schematically showing the lighting device 300 according to the first embodiment, FIG. 4A is a side view schematically showing the lighting device 300, and FIG. 4B is a lighting device. 300
It is a side view which expands and shows the light guide 20 which this has typically.

The illumination device 300 is shown in FIGS. 3 and 4 (a).
As shown in, the light sources 10 and 10 ′ and the light guide 20 are provided. In the present embodiment, the light sources 10 and 10 '.
As the light source, an LED (light emitting diode) which is a point light source is used.

The light guide body 20 faces the first side surface (incident side surface) 21 for receiving light from the light source 10 and the first side surface 21,
Second side surface (incident side surface) 22 that receives light from the light source 10 '
Is located between the first side surface 21 and the second side surface 22,
Emission surface 23 substantially orthogonal to the side surface 21 and the second side surface 22
And a facing surface 24 facing the emitting surface 23 via the first side surface 21 and the second side surface 22. In this embodiment,
The light guide body 20 has a third side surface 25 and a fourth side surface 26 which are located between the first side surface 21 and the second side surface 22 and face each other, and the first side surface 21, the second side surface 22, and the second side surface 22. 3 side 2
5 and the fourth side surface 26, and the exit surface 23 and the facing surface 2
4 and 4 face each other.

As shown in FIG. 4B, the facing surface 24 of the light guide body 20 has a plurality of grooves provided at a predetermined cycle along a direction orthogonal to the first side surface 21 (second side surface 22). 24a. The plurality of grooves 24a are formed on the first side surface 21 (second side surface 2).
It extends in a direction intersecting the direction orthogonal to 2). Further, the facing surface 24 is located between the grooves 24 a, and the first side surface 21
It has a flat portion 24b that is substantially parallel to the direction orthogonal to the (second side surface 22) (that is, substantially parallel to the emission surface 23).

Each of the plurality of grooves 24a has a plurality of surfaces 2
4a1 and 24a2. Multiple grooves 2
A plurality of surfaces 24a1 and 24 constituting each of 4a
a2 is inclined with respect to the direction orthogonal to the first side surface 21 (that is, with respect to the flat portion 24b of the facing surface 24). The inclined surface 24a1 close to the first side surface 21 and the surface 24a2 close to the second side surface 22 are both inclined at the same inclination angle α.

In the illumination device 300 of this embodiment, for example, as the light guide 20, the length L along the direction orthogonal to the first side face 21 is 65 mm, and the length L is parallel to the emission face 123 and the first side face 21. A light guide body 20 having a length L ′ of 85 mm and a thickness T of 1 mm along the normal line direction of the emission surface 23.
And the main emission direction of the illumination light is the normal direction of the emission surface 23 (that is, the emission angle θ of the illumination light is 0 °), the above equations (5), (6) and (8 ′) are used. ), The inclined surfaces 24a1 and 2a forming the groove 24a
The inclination angle α of 4a2, the depth h of the groove 24a, the period p of the groove 24a, and the refractive index n of the light guide 20 may satisfy the following expression (9). In addition, here, the period p of the groove 24a is
The upper limit of 0.2 mm is set so that the groove 24a is not separated and is not visible.

Α = 44.1 (°) n ≧ 1.44 0.0062 (mm) ≦ h ≦ 0.097 (mm) p = 0.2 (mm) (9) To satisfy the above formula (9) In this example, the light guide 20
Is formed using an acrylic resin having a refractive index of 1.49,
The depth h of the groove 24a is 0.03 mm in consideration of processing accuracy.
And That is, the design value of the light guide 20 is set as in the following expression (9 ′).

Α = 44.1 (°) n = 1.49 h = 0.03 (mm) p = 0.2 (mm) (9 ′) Illumination created based on the value of the above formula (9 ′) Device 300
FIG. 5 shows the result of measurement of the emission angle characteristic of the illumination light at the point of, in FIG. FIG. 5 is a graph showing the relationship between the emission angle (°) of the illumination light emitted from the emission surface 23 of the illumination device 300 and the relative luminance (au).

From FIG. 5, in the illumination device 300 of this embodiment, the emission angle is 0 within the emission surface 23 of the light guide 20.
It can be seen that the illumination light is emitted almost uniformly in the direction of °.

As described above, the first embodiment according to the present invention
The illumination device 300 can output uniform illumination light. Further, the light guide 20 included in the lighting device 300 is easy to form because the depth h and the period p of the groove 24a are constant within the plane of the facing surface 24, and therefore the lighting device 30 is provided.
0 can be easily manufactured by a simple process.

(Embodiment 2) An illumination device 400 according to Embodiment 2 of the present invention is shown in FIGS. 6, 7 (a) and 7 (b). FIG. 6 is a perspective view schematically showing the lighting device 400 of the second embodiment, FIG. 7A is a side view schematically showing the lighting device 400, and FIG. 7B is a lighting device. 400
It is a side view which expands and shows the light guide 20 which this has typically.

As shown in FIG. 6, the illumination device 400 includes light sources 10 and 10 ', a light guide (first light guide) 20, and
And a further light guide body (second light guide body) 30. In this embodiment, LEDs (light emitting diodes) that are point light sources are used as the light sources 10 and 10 ′.

The light guide (first light guide) 20 is shown in FIG.
As shown in FIG. 1, a first side surface (incident side surface) 21 that receives light from the light source 10, a second side surface (incident side surface) 22 that faces the first side surface 21 and receives light from the light source 10 ′, and a first side surface (incident side surface) 22. An emission surface 23 located between the side surface 21 and the second side surface 22 and substantially orthogonal to the first side surface 21 and the second side surface 22, and an emission surface 23.
And a facing surface 24 facing each other through the first side surface 21 and the second side surface 22.

As shown in FIG. 7B, the facing surface 24 of the light guide body 20 has a plurality of grooves provided in a predetermined cycle along a direction orthogonal to the first side surface 21 (second side surface 22). 24a. The plurality of grooves 24a are formed on the first side surface 21 (second side surface 2).
It extends in a direction intersecting the direction orthogonal to 2). Further, the facing surface 24 is located between the grooves 24 a, and the first side surface 21
It has a flat portion 24b that is substantially parallel to the direction orthogonal to the (second side surface 22) (that is, substantially parallel to the emission surface 23).

Each of the plurality of grooves 24a has a plurality of surfaces 2
4a1 and 24a2. Multiple grooves 2
A plurality of surfaces 24a1 and 24 constituting each of 4a
a2 is inclined with respect to the direction orthogonal to the first side surface 21 (that is, with respect to the flat portion 24b of the facing surface 24). The inclined surface 24a1 close to the first side surface 21 and the surface 24a2 close to the second side surface 22 are both inclined at the same inclination angle α.

Various known light guides can be used as the second light guide 30 provided on the exit surface 23 side of the light guide (first light guide) 20. In the present embodiment, as the second light guide body 30, the length L1 in the direction orthogonal to the first side surface 21 of the light guide body 20 is 35 mm, and the length along the normal direction of the emission surface 23 of the light guide body 20. A light guide body having L1 ′ of 50 mm is used.

In the lighting device 400 having the above structure,
Light from the point-shaped light sources 10 and 10 ′ is emitted from the first side surface 21.
Is incident on the inside of the light guide body (first light guide body) 20 via and is reflected by the inclined surfaces 24a1 and 24a2 of the facing surface 24,
The light is emitted from the emission surface 23. The second light guide body 30 receives the light emitted from the emission surface 23 of the light guide body (first light guide body) 20, and emits illumination light.

In the illuminating device 400 of this embodiment, for example, as the light guide 20, the length L along the direction orthogonal to the first side surface 21 is 38 mm, and the length L is parallel to the emission surface 123 and the first side surface 21. A light guide 20 having a length L ′ of 1 mm and a thickness T of 3 mm along the normal direction of the emission surface 23 is used, and the main emission direction of the illumination light is the normal direction of the emission surface 23 ( That is, in the case where the emission angle θ of the illumination light is 0 °), in order to satisfy the above formulas (5), (6) and (8 ′), the inclined surfaces 24a1 and 2a forming the groove 24a are formed.
The inclination angle α of 4a2, the depth h of the groove 24a, the period p of the groove 24a, and the refractive index n of the light guide 20 are expressed by the following formula (10).
Should be satisfied. In addition, here, the period p of the groove 24a is p.
Is the upper limit of 0.2 mm at which the groove 24a is separated and not visually observed.
I am trying.

Α = 40.5 (°) n ≧ 1.54 0.032 (mm) ≦ h ≦ 0.171 (mm) p = 0.2 (mm) (10) To satisfy the above formula (10) In this example, the light guide 20
Is formed using a polycarbonate resin having a refractive index of 1.59, and the depth h of the groove 24a is set to 0.
It is set to 05 mm. That is, the design value of the light guide 20 is set as in the following formula (10 ′).

Α = 40.5 (°) n = 1.59 h = 0.05 (mm) p = 0.2 (mm) (10 ′) Illumination created based on the value of the above formula (10 ′). Device 40
The emission angle characteristic of the illumination light of 0 is shown in FIG.
The results measured at the points are shown in FIG. FIG. 8 is a graph showing the relationship between the emission angle (°) of the illumination light emitted from the emission surface 23 of the light guide 20 of the illumination device 400 and the relative luminance (au).

From FIG. 8, in the illumination device 400 of this embodiment, the emission angle is 0 within the emission surface 23 of the light guide 20.
It can be seen that the illumination light is emitted almost uniformly in the direction of °.

As described above, the second embodiment according to the present invention
The illuminating device 400 can emit uniform illumination light. Further, the light guide 20 included in the lighting device 400 is easy to form because the depth h and the period p of the groove 24a are constant within the surface of the facing surface 24, and therefore the lighting device 40 is provided.
0 can be easily manufactured by a simple process.

The illumination device according to the present invention described above can be suitably used as a front light or a back light included in a display device. 9 and 10 show liquid crystal display devices 500 and 600, which are display devices according to embodiments of the present invention.

The liquid crystal display device 500 shown in FIG. 9 is the illuminating device 300 of the first embodiment, and the reflection type liquid crystal display panel 40 provided on the opposite side of the illuminating device 300 from the observer side (above the paper surface). It is a reflection type liquid crystal display device including.

The liquid crystal display device 600 shown in FIG.
Is a transmissive liquid crystal display device including the illuminating device 300 of the first embodiment and a transmissive liquid crystal display panel 50 provided on the observer side (upper surface of the drawing) with respect to the illuminating device 300.

[0093]

According to the present invention, a simple designing method and manufacturing method of a lighting device are provided. Further, according to the present invention, there are provided a light guide and an illuminating device capable of emitting uniform illumination light, and a display device including the same.

Since the illuminating device according to the present invention emits uniform illumination light, it is preferably used as a front light and a back light of a liquid crystal display device.

[Brief description of drawings]

FIG. 1A is a side view schematically showing a lighting device 100 including a light guide body 20 having a groove 24a in a facing surface 24, and FIG. 1B is a light guide body included in the lighting device 100. It is a side view which expands and shows 20 typically.

2A is a side view schematically showing a lighting device 200 having a further light source 10 ′ provided on the second side surface 22 side of the light guide 20, and FIG. 2B is a lighting device 200. It is a side view which expands and shows the light guide 20 which this has typically.

FIG. 3 is a perspective view schematically showing the lighting device 300 according to the first embodiment of the present invention.

FIG. 4A is a side view schematically showing the lighting device 300 according to the first embodiment of the present invention, and FIG. 4B is a schematic enlarged view of the light guide 20 included in the lighting device 300. It is a side view shown.

5 is a graph showing the relationship between the emission angle (°) of illumination light emitted from the emission surface 23 of the illumination device 300 and the relative luminance (au).

FIG. 6 is a lighting device 4 according to a second embodiment of the present invention.
It is a perspective view which shows 00 normally.

7A is a side view schematically showing an illuminating device 400 of a second embodiment according to the present invention, and FIG. 7B is a schematic enlarged view of a light guide 20 included in the illuminating device 400. It is a side view shown.

FIG. 8 shows an emission angle (°) of illumination light emitted from an emission surface 23 of a light guide 20 of a lighting device 400 and a relative luminance (a.
u. ) Is a graph showing the relationship with.

FIG. 9 is a side view schematically showing a liquid crystal display device 500 which is a display device according to an embodiment of the present invention.

FIG. 10 is a side view schematically showing a liquid crystal display device 600 which is a display device according to an embodiment of the present invention.

11A is a side view schematically showing a conventional lighting device 700, and FIG. 11B is a side view schematically showing a resin substrate 720 of the lighting device 700 in an enlarged manner.

FIG. 12 is a perspective view schematically showing a conventional lighting device 800.

13A is a top view schematically showing a point light source 810 and a first light guide 820 included in the lighting device 800, and FIG. 13B is a schematic view of the first light guide 820. It is an enlarged top view.

[Explanation of symbols]

10, 10 'light source 20 Light guide, first light guide 21 First side (incident side) 22 Second side 23 exit surface 24 Opposing surface 24a groove 24a1 inclined surface 24b flat part 30 Further light guide (second light guide) 40 reflective liquid crystal display panel 50 transmissive liquid crystal display panel 100,200 Lighting device 300,400 Lighting device 500,600 Liquid crystal display device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // F21Y 101: 02 F21Y 101: 02

Claims (14)

[Claims] 1. A light source, a first side surface that receives light from the light source, a second side surface facing the first side surface, a first side surface and a second side surface, and the first side surface and the second side surface. A light guide having an emission surface that is substantially orthogonal to one side surface, and an opposing surface that faces the emission surface via the first and second side surfaces, the illumination device comprising: The facing surface is a plurality of grooves provided at a predetermined cycle along a first direction orthogonal to the first side surface, and has a plurality of grooves extending in a second direction intersecting the first direction, Each of the plurality of grooves is composed of a plurality of surfaces, and among the plurality of surfaces forming each of the plurality of grooves, a surface closest to the first side surface is with respect to the first direction. An inclined surface that is inclined, an angle α formed by the inclined surface with the first direction, and a refractive index of the light guide. A thickness T of the light guide along the normal direction of the emission surface, a length L of the light guide along the first direction, a depth h of the plurality of grooves, and a depth of the plurality of grooves. A lighting device in which a period p satisfies the relations of n · sin {90-α-tan ⁻¹ (2T / L)} ≧ 1 and 2T / L ≦ h / p ≦ tanα. 2. The angle α formed by the inclined surface with the first direction, the depth h of the plurality of grooves, and the period p of the plurality of grooves.
Is constant within the surface of the said opposing surface, The illuminating device of Claim 1. 3. The light source further includes a light source provided on the second side surface side, and of the plurality of surfaces forming each of the plurality of grooves, a surface closest to the second side surface is The lighting device according to claim 1 or 2, wherein the lighting device is inclined with respect to the first direction at the same angle as the inclined surface closest to the first side surface. 4. The angle α formed by the inclined surface with respect to the first direction, the depths h of the plurality of grooves, the period p of the plurality of grooves, and the light guide along the normal direction of the emission surface. The thickness T and the length L of the light guide along the first direction are 2T / L.
The lighting device according to claim 3, which satisfies a relationship of ≦ h / p ≦ tan α / 2. 5. A display device comprising: the illuminating device according to claim 1; and a reflective display panel provided on a side of the illuminating device opposite to an observer. 6. A display device comprising: the illuminating device according to claim 1; and a transmissive display panel provided on an observer side of the illuminating device. 7. A first side surface that receives light from a light source, a second side surface that faces the first side surface, a first side surface, and a second side surface that is located between the first side surface and the second side surface. It is a light guide which has an exit surface which intersects perpendicularly, and the facing surface which opposes the exit surface via the 1st and 2nd side faces, The above-mentioned facing face is the 1st direction orthogonal to the 1st side face. A plurality of grooves provided at a predetermined cycle along the first groove.
Having a plurality of grooves extending in a second direction intersecting the direction, each of the plurality of grooves is composed of a plurality of surfaces, among the plurality of surfaces constituting each of the plurality of grooves, The surface close to the first side surface is an inclined surface inclined with respect to the first direction, and an angle α formed by the inclined surface with the first direction, a refractive index n, and a direction normal to the emission surface are set. The thickness T, the length L along the first direction, the depth h of the plurality of grooves and the period p of the plurality of grooves are n · sin {90-α-tan ^-1 (2T / L)}. A light guide satisfying the relations of ≧ 1 and 2T / L ≦ h / p ≦ tan α. 8. The angle α formed by the inclined surface with the first direction, the depth h of the plurality of grooves, and the period p of the plurality of grooves.
Is constant within the surface of the said opposing surface, The light guide of Claim 7. 9. Of the plurality of surfaces forming each of the plurality of grooves, a surface closest to the second side surface is in the first direction at the same angle as the inclined surface closest to the first side surface. The light guide according to claim 7, which is inclined with respect to the light guide. 10. The angle α formed by the inclined surface with the first direction, the depth h of the plurality of grooves, the period p of the plurality of grooves, the thickness T of the emitting surface along the normal direction, and the The light guide according to claim 9, wherein the length L along the first direction satisfies the relationship of 2T / L ≦ h / p ≦ tan α / 2. 11. A light source, a first side surface that receives light from the light source, a second side surface facing the first side surface, a first side surface and a second side surface, and the first side surface and the second side surface. A light guide body having an emission surface substantially orthogonal to one side surface and an opposed surface opposed to the emission surface via the first and second side surfaces; and the opposed surface of the light guide body, A plurality of grooves provided in a predetermined cycle along a first direction orthogonal to the first side surface, the plurality of grooves extending in a second direction intersecting the first direction, Each is composed of a plurality of surfaces, and among the plurality of surfaces forming each of the plurality of grooves, a surface closest to the first side surface is an inclined surface inclined with respect to the first direction. A method for designing an illumination device, comprising: an angle α formed by the inclined surface with the first direction; The refractive index n, the thickness T of the light guide along the normal to the exit surface, the length L of the light guide along the first direction, and the most exit of light from the exit surface. Output angle θ
Of at least one of the determined numerical values and the determined numerical values other than at least one of 2α + tan ⁻¹ (2T / L) + sin ⁻¹ (sin θ /
n) = 90 3 is determined so as to satisfy the relationship. 12. In the step of determining the numerical value other than the determined at least one, the numerical value other than the determined at least one is expressed by n.sin {90-α-tan ⁻¹ (2T / L)} ≧ 1. 12. The method for designing a lighting device according to claim 11, wherein the determination is made so as to satisfy the relationship. 13. In the step of determining the determined numerical value other than at least one, the determined numerical value other than at least one, and the numerical values of the depths h of the plurality of grooves and the periods p of the plurality of grooves. Is determined so as to satisfy the relationship of 2T / L ≦ h / p ≦ tan α.
A method for designing a lighting device according to. 14. A method of designing a lighting device using the method for designing a lighting device according to claim 11, based on each numerical value determined in the step of designing the lighting device, The manufacturing method of the illuminating device including the process of producing the said light guide.