JP2008091194A - Light guide body, and lighting system equipped with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light guide body capable of uniformly irradiating an illuminating object without irregularity; and a lighting system equipped with the light guide body. <P>SOLUTION: This light guide body 2 is composed by forming, on a main body part formed in a nearly-flat shape, incident surfaces 2a introducing light from point-like light sources 1, reflecting surfaces 2b reflecting the light introduced from the incident surfaces 2a, and an emitting surface 2c emitting the light reflected on the reflecting surfaces 2b to a light entering end surface 3c of the illuminating object 3. The reflecting surface 2b comprises a plurality of prisms P continuously continued in a recessed form with respect to the emitting surface 2c so that luminous flux can be emitted from the emitting surface 2c vertically to the surface at uniform intervals. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light guide suitable for uniformly irradiating a planar illuminated body such as a liquid crystal panel, for example, and a lighting device including the light guide.

  In an illuminating device for illuminating a liquid crystal panel, conventionally, a point light source such as an LED is used as a light source, and as a means for converting light emitted from the point light source into planar illumination light, PC, PMMA, A linear (or plate-like) light guide made of a transparent material such as an olefin resin is used, and the liquid crystal panel is illuminated through the light guide (see, for example, Patent Document 1).

For example, as shown in FIG. 5A, the point light sources 1 and 1 are arranged on both sides of the light guide 2, and the light emitted from the point light sources 1 and 1 is guided from the incident surfaces 2a and 2a. The light is converted into planar illumination light by being taken into the body 2 and reflected by the reflection surface 2b of the light guide 2, and the liquid crystal panel 3 adjacent to the exit surface 2c of the light guide 2 is illuminated by the illumination light. Such a configuration is adopted.
JP 2003-115209 A

  However, in the illuminating device using the conventional linear light guide 2 as described above, uneven brightness tends to occur in the liquid crystal panel 3. FIG. 5 (b) is a graph showing the luminance distribution in the long side direction of the conventional light guide 2. As shown in this graph, the closer to the two-point light sources 1, 1, the higher the luminance. In the central part farthest from the light sources 1 and 1, there was a tendency for the luminance to decrease.

  This is because, since the reflecting surface 2b of the light guide 2 is formed in a flat plate shape, the light flux density of the reflected light becomes dense at a position close to both the point light sources 1 and 1, whereas both points This is presumably because the density of the reflected light beam becomes coarser as the distance from the light sources 1 and 1 increases. In addition, the vertical axis | shaft of FIG.5 (b) shows a brightness | luminance.

  This invention is made | formed in view of such a situation, and it aims at providing the illuminating device using the light guide which can irradiate a to-be-illuminated body uniformly, and the light guide.

(1) The light guide of the present invention comprises a main body formed in a substantially flat plate shape, an incident surface that takes in light from a point light source, a reflective surface that reflects light taken from the incident surface, and the reflective surface. A light guide that is formed with an exit surface that emits the reflected light to the light incident end surface of the illuminated body,
The reflecting surface is formed by continuously forming a prism that emits light from the point light source directly from the emitting surface, and the reflecting surface is formed by emitting light from the prisms to the emitting surface. It is formed in the curved surface which inject | emits at equal intervals from.

According to such a configuration, the prism is formed such that the reflected light from the prism is emitted in a plane, and the reflecting surface formed by connecting the plurality of prisms reflects the reflected light from the prisms. Since it is formed in a curved surface that is emitted at equal intervals from the emission surface, if the reflected light emitted in this way is incident on the light incident end surface of the illuminated object, the light incident on the illuminated object The luminance distribution in the long side direction along the end face can be made uniform, and the illuminated body can be irradiated evenly.
(2) The position of the point light source is an origin, an X axis is set in a direction along the exit surface from the origin, and a Y axis is orthogonal to the X axis from the origin and away from the illuminated body. Is set to a point P _n at which a ray adjacent to a predetermined angle α is reflected at a predetermined interval a with respect to an arbitrary reference point P _n (x _n , y _n ) on the XY plane forming the reflection surface. The coordinates of ₊₁ (x _{n + 1} , y _{n + 1} )
(X _n + a) × tan (θ−α) = y _{n + 1} ---------- (A)
x _n + a = x _{n + 1} ---------------------------------------- (B )
It may be given by the above formulas (A) and (B). Here, θ is an angle formed by the straight line OP _n and the X axis.

In this way, as shown in FIG. 3, first, the reference point P _n is arbitrarily determined. For example, if P _n (1,1), (1 + a) × tan (45 ° −α) = y _{n + 1} from equation (A), x _{n + 1} = 1 + a from equation (B), where Thus, x _{n + 1} and y _{n + 1} are determined by setting appropriate a and α. Similarly, the coordinates of the point P _n-1 can be obtained. By connecting these points, a curve that forms a required reflecting surface can be obtained.
(3) The reflecting surfaces may be formed symmetrically on the main body, and a pair of the incident surfaces may be formed on both left and right ends of the main body. In this way, since light can be incident from the left and right ends of the light guide by the two point light sources, the irradiation width to the illuminated body can be expanded compared to the single point light source, An illuminated body having a wider width can be irradiated evenly.
(4) An illumination device of the present invention includes the light guide according to any one of (1) to (3), a point light source that makes light incident on an incident surface of the light guide, and the light guide. And an illuminated body having a light incident end face facing the exit surface of the light body.

  According to such a configuration, since the light guide having the reflection surface composed of a plurality of prisms continuously connected to the emission surface is provided, the reflected light reflected by the reflection surface is evenly spaced from the emission surface. Since the light is emitted in a plane as light with a light beam, if the light incident end face is faced to the light emission surface and the illuminated body is connected, the illuminated body can be irradiated evenly with a uniform luminance distribution. . The illuminated body may be formed, for example, in a flat plate shape having a constant thickness, or may be formed so that the thickness is reduced in a direction away from the light incident end face.

  According to the light guide of the present invention, the reflected light reflected by the reflecting surface composed of a plurality of prisms continuously connected to the illuminated body is emitted as light of a light beam having an equal interval from the emitting surface. Therefore, if this is made incident on the light incident end face of the illuminated body, the luminance distribution in the long side direction along the light incident end face of the illuminated body can be made uniform, and the illuminated body can be irradiated evenly. it can.

  According to the illuminating device of the present invention, the illuminated body is evenly irradiated with light of a light beam having an equal interval through the light guide having a reflecting surface composed of a plurality of prisms continuously connected to the exit surface. Therefore, the illuminated body can be irradiated evenly.

  Below, the light guide which concerns on embodiment of this invention, and the illuminating device provided with the light guide are demonstrated in detail.

  1A is a plan view of the illumination device, FIG. 1B is a graph showing the luminance distribution in the long side direction of the light guide, and FIG. 2A is an explanatory view of a reflected light path of irradiation light from a point light source, (B) is explanatory drawing of the optical path reflected by a prism. First, as shown in FIG. 1 (a), the light guide 2 includes an incident surface 2a for capturing light from the point light source 1 into a main body formed in a substantially flat plate shape, and the incident surface 2a. A reflection surface 2b for reflecting the light and an emission surface 2c for emitting the light reflected by the reflection surface 2b to the light incident end surface 3c of the illuminated body 3 made of a liquid crystal panel or the like. 2b is formed of a plurality of prisms P that are continuously connected in a concave shape with respect to the exit surface 2c so that the light beam can be emitted straight from the exit surface 2c at equal intervals.

  As shown in FIGS. 2 (a) and 2 (b), the prism P is arranged so that the light reflected by each prism P is incident on the light incident end surface 3c of the illuminated body 3 in a plane. The inclination angle of the slope of P is set individually. Each prism P is continuously formed by changing the angle (inclination) of each slope one by one using a cutting tool having a predetermined angle by a machine tool in which a control program is set. As shown in FIG. 1B, the luminance distribution in the long side direction on the exit surface 2c of the light guide 2 provided with the reflecting surface 2b composed of such a plurality of continuous prisms P is substantially uniform. Accordingly, if the light incident end surface 3c of the illuminated body 3 is connected to the exit surface 2c so as to face the connected surface, the illuminated body 3 can be illuminated uniformly. Note that the luminance distribution in FIG. 1B is a result of measurement at an intermediate position in the thickness direction of the light guide 2.

  As described above, the specific shape of the reflecting surface 2b such that the luminance distribution on the exit surface 2c is substantially uniform is obtained as follows.

FIG. 3 is an explanatory diagram of a curve forming the reflecting surface 2b of the light guide 2, and this curve is formed so as to satisfy the following expressions (1) and (2). That is, the position of the point light source 1 is set as the origin, the X axis is set in the direction along the emission surface from the origin, and the Y axis is set in the direction away from the illuminated body perpendicular to the X axis from the origin. Then, the point P _{n + 1} (x _{n + 1} , y _{n + 1} ) where the light beam adjacent to the predetermined angle α is reflected at a predetermined interval a with respect to the reference point P _n (x _n , y _n ) on the curve. Coordinates are
(X _n + a) × tan (θ−α) = y _{n + 1} ---------- (A)
x _n + a = x _{n + 1} ---------------------------------------- (B )
It is given by the above equations (A) and (B). Here, θ is an angle formed by the straight line OP _n and the X axis.

In order to obtain a curve from the above two equations, first, the reference point P _n is arbitrarily determined. For example, if P _n (1, 1), (1 + a) × tan (45 ° −α) = y _{n + 1} from equation (A), x _{n + 1} = 1 + a from equation (B), where Thus, x _{n + 1} and y _{n + 1} are determined by setting appropriate a and α. Similarly, the coordinates of the point P _n-1 can be obtained. By connecting these points, the required curved shape (curved surface shape) of the reflecting surface 2b can be obtained.

  FIG. 4A shows a light guide 2 having a concave reflecting surface 2b formed as described above, a single point light source 1 provided on the incident surface 2a of the light guide 2, and a liquid crystal panel. FIG. 4B is a perspective view of an illuminating device provided with a flat plate-like illuminated body 3 made of, for example, and FIG. 4B shows a concave reflecting surface 2b formed symmetrically on the main body of the light guide 2. The perspective view of the illuminating device provided with the two point light sources 1 and 1 on the incident surfaces 2a and 2a is shown (corresponding to FIG. 1A). In this way, by making light incident from the left and right ends of the light guide 2 by the two point light sources 1, 1, the irradiation width to the illuminated body 3 can be expanded as compared with the single point light source 1. Therefore, the illuminated body 3 having a wider width can be irradiated evenly.

  Note that the present invention is not limited to the embodiment, and can be freely modified and improved as necessary, for example, as long as it does not depart from the gist of the invention. May not necessarily be formed in a flat plate shape but may be formed in a tapered shape (wedge shape) in the irradiation direction.

Further, in consideration of the directivity of the light source 1, that is, the characteristic that the luminance is attenuated every time the emitted light from the light source 1 is shifted by a predetermined angle, the interval of the emitted light by each prism P may be appropriately adjusted. For example, in FIG. 3, when the luminance attenuation rate for each predetermined angle of the light source 1 is ½, for each X coordinate of the points P _n , P _{n + 1} , and P _n−1 , | X _{n + 1} − It is set so that | X _n −X _n−1 | = a / 2 holds for X _n | = a.

  The light guide of the present invention can irradiate the illuminated body evenly by converting the illumination light from the point light source into a planar shape, so that it can be used for illumination of various planar illuminated bodies such as liquid crystal panels. Can be used.

  Since the illuminating device of the present invention includes an illuminated body that is uniformly illuminated, it can be suitably used for various display devices.

(A) is planar explanatory drawing of the illuminating device which concerns on embodiment of this invention, (b) is explanatory drawing which shows the luminance distribution of the long side direction of a light guide. (A) is explanatory drawing of the reflected optical path of the irradiation light of the illumination device, (b) is explanatory drawing of the optical path reflected by the prism Explanatory drawing of the curve that forms the reflection surface (A) is a perspective view of the illuminating device provided with the single point light source, (b) is a perspective view of the illuminating device provided with two point light sources. (A) is explanatory drawing of the illuminating device provided with the light guide with which the conventional reflective surface was formed in flat form, (b) is explanatory drawing which shows the luminance distribution of the long side direction of the light guide.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Point light source 2 Light guide 2a Incident surface 2b Reflecting surface 2c Outgoing surface 3 Illuminated body 3c Light incident end surface P Prism

Claims (4)

An incident surface for capturing light from a point light source, a reflecting surface for reflecting light captured from the incident surface, and a light incident end surface of the illuminated body that reflects the light reflected by the reflecting surface on a main body formed in a substantially flat plate shape A light guide body formed with an exit surface that emits to
The reflecting surface is formed by continuously forming a prism that emits light from the point light source directly from the emitting surface, and the reflecting surface is formed by emitting light from the prisms to the emitting surface. It is formed in the curved surface which inject | emits at equal intervals from the light guide. The position of the point light source is the origin, the X axis is set in the direction along the exit surface from the origin, and the Y axis is set in the direction away from the illuminated body perpendicular to the X axis from the origin. For example, with respect to an arbitrary reference point P _n (x _n , y _n ) on the XY plane that forms the reflection surface, a point P _{n + 1} ( _where a ray adjacent to the predetermined angle α is reflected at a predetermined interval a. x _{n + 1} , y _{n + 1} )
(X _n + a) × tan (θ−α) = y _{n + 1} ---------- (A)
x _n + a = x _{n + 1} --------------------------------------- (B )
The light guide according to claim 1, which is given by the expressions (A) and (B).
Here, θ is an angle formed by the straight line OP _n and the X axis.   3. The light guide according to claim 1, wherein the reflecting surfaces are formed symmetrically on the main body, and a pair of the incident surfaces are formed on both left and right ends of the main body. 4. The light guide according to any one of claims 1 to 3, a point light source that makes light incident on an incident surface of the light guide, and a light-receiving end face that faces an exit surface of the light guide. And an illuminating body.

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