JP2012123958A - Light guide plate and lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light guide plate and a lighting system capable of achieving downsizing (thinning) while optical characteristics are satisfied.SOLUTION: The light guide plate is structured, in a shape of a staircase, of: a plurality of inclined faces 9 of which a rear face part 7 inclines to approach nearer a surface part 6 side as it comes nearer a reflection face part 5 side from an incident face part 4 side; and connection faces 15 for connecting an end part of the reflection face part 5 side of the inclined face 9 located on the incident face part 4 side and an end part of the incident face part 4 side of the neighboring inclined face 10 located on the reflection face part 5 side. Inclining angles of the inclined faces 9 are made larger on the side of the inclined face 14 more separated from the incident face part 4. Further, the lighting system includes the light guide plate and a light source for emitting light to the light guide plate.

Description

  The present invention relates to a light guide plate for emitting light from a light source, and an illumination device including the light guide plate and a light source.

  2. Description of the Related Art Conventionally, a light guide plate used in an illumination device or the like is located between a front surface portion from which light from a light source is emitted, a back surface portion located on the opposite side facing the front surface portion, and the front surface portion and the back surface portion. A plurality of side surface portions, and these side surface portions include an incident surface portion on which light to be emitted from the surface portion is incident, and a reflection surface portion that is located on the opposite side opposite to the incident surface portion and reflects light. .

  Then, the back surface portion is formed in a staircase pattern by alternately connecting a gentle first inclined surface portion facing downward from the incident surface portion toward the reflecting surface portion and a downward second inclined surface portion having a larger angle than this. (See, for example, Patent Document 1).

JP 2007-273288 A (see FIG. 9)

  The light guide plate of Patent Document 1 is shown in FIG. As shown in FIG. 5, the first inclined surface portion 51 constituting the back surface portion 50 is not only configured to be inclined downward so as to be separated from the front surface portion 54 side as it approaches the reflecting surface portion 53 from the incident surface portion 52. Since the first inclined surface portion 51 is largely separated from the front surface portion 54 side by the downwardly inclined second inclined surface portion 55 constituting the back surface portion 50, the first inclined surface 51 located on the reflecting surface portion 53 side is larger. , And away from the surface portion 54 side. As a result, the thickness of the light guide plate becomes thicker toward the reflecting surface side. Therefore, there is a disadvantage that the light guide plate cannot be reduced in size (thinned).

  Therefore, in view of such circumstances, it is an object of the present invention to provide a light guide plate and a lighting device that can be downsized (thinned) while satisfying optical characteristics.

  The light guide plate according to the present invention includes a surface portion from which light from the light source is emitted, a back surface portion located on the opposite side opposite to the surface portion, and a plurality of side surface portions positioned between the surface portion and the back surface portion. These light guide plates are provided with an incident surface portion on which light to be emitted from the surface portion is incident and a reflection surface portion that is located on the opposite side opposite to the incident surface portion and reflects light. A plurality of inclined surfaces that incline so as to approach the surface portion side as the back surface portion approaches the reflecting surface portion side from the incident surface portion side, and an end of the inclined surface located on the incident surface portion side on the reflecting surface portion side And a connecting surface that connects the end of the inclined surface located on the side of the reflecting surface adjacent thereto and the end of the incident surface on the side of the incident surface. The inclined angle of the inclined surface is separated from the incident surface. The inclined surface on the side has a larger angle. To.

  According to such a configuration, the back surface portion includes a plurality of inclined surfaces that are inclined so as to approach the surface portion side as approaching from the incident surface portion to the reflecting surface portion, and the inclination angle of the inclined surface is inclined on the side away from the incident surface portion. Since the surface is configured to have a larger angle, the inclined surface on the reflecting surface portion side can be brought closer to the surface portion side or the same as that near the center of the reflecting surface portion from the incident surface portion. As a result, an increase in the thickness of the light guide plate can be avoided. In addition, the light incident from the incident surface portion can be reflected by the inclined surface and the coupling surface, and can be reliably and uniformly emitted from the surface portion.

  Moreover, in the invention according to claim 2, it is preferable that the connection surface is an inclined surface that is farther from the surface portion toward the end portion on the reflection surface portion side.

  According to such a configuration, it is possible to reliably guide the light, which has been reflected by the reflecting surface portion and returned to the incident surface portion side, to the connecting surface formed on the inclined surface and to the surface portion side.

  Further, in the invention according to claim 3, it is preferable that a plurality of the connection surfaces are provided, and the connection length of the connection surfaces connecting the two inclined surfaces is made shorter as the connection surface on the reflection surface portion side.

  According to such a configuration, if the connection length of the connection surface is configured to be shorter as the connection surface on the reflection surface portion side, the inclined surface can be made closer to the surface portion side as the reflection surface portion side, and as a result. Further, it is possible to more reliably avoid an increase in the thickness of the light guide plate.

  The illumination device according to the present invention includes the light guide plate and a light source for emitting light to the light guide plate.

  As described above, according to the light guide plate and the illumination device according to the present invention, the light guide plate and the illumination device include a plurality of inclined surfaces that are inclined so as to approach the surface portion side as the incident surface portion approaches the reflecting surface portion, and the inclination angle of the inclined surface is incident. By configuring the angle so as to be farther from the surface portion, it is possible to provide a light guide plate and a lighting device that can be downsized (thinned) while satisfying optical characteristics (for example, uniformity of luminance).

1 is an overall side view of a lighting apparatus according to an embodiment of the present invention. Enlarged schematic side view of the light guide plate according to the embodiment Explanatory drawing which shows the inclination-angle of the lower surface by the side of the entrance plane part of the light-guide plate which concerns on the embodiment Explanatory drawing which shows the inclination-angle of the lower surface by the side of the reflective surface part of the light-guide plate which concerns on the same embodiment. Side view of conventional light guide plate

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of a lighting device according to the present invention and a light guide plate used in the lighting device will be described with reference to FIGS.

  The illumination device according to the present embodiment is used, for example, for a backlight of a liquid crystal screen of a mobile phone or for a backlight of a liquid crystal screen of a handset of a stationary phone. As shown in FIG. 1, the illuminating device includes a light source 1 composed of a linear light source such as a cold cathode tube for irradiating light, and light emitted from the light source 1 on the liquid crystal screen (not shown) side. And a light guide plate 2 for emitting light toward the screen.

  The light source 1 is surrounded by a reflector 3 having a reflecting surface formed in a concave curved surface, and light from the light source 1 is incident on the light guide plate 2 together with the reflected light from the reflector 3.

  The light guide plate 2 is formed of, for example, a transparent acrylic resin or polycarbonate, and has a thin plate shape and a rectangular shape.

  As shown in FIG. 1, the light guide plate 2 is positioned on an incident surface portion 4 on which light from the light source 1 is incident (formed on the surface located on the left side in FIG. 1) and on the opposite side facing the incident surface portion 4. The reflection surface portion 5 that reflects light (formed on the right side surface in FIG. 1) and the upper surface that connects the upper surfaces of the incidence surface portion 4 and the reflection surface portion 5 are emitted and the light from the light source 1 is emitted. And a back surface portion 7 that is located on the opposite side of the surface portion 6 and that connects the lower ends of the incident surface portion 4 and the reflecting surface portion 5 and reflects light.

  Further, the incident surface portion 4 and the reflective surface portion 5 constitute two opposing surfaces of the four side surfaces located between the front surface portion 6 and the back surface portion 7, and the remaining two side surface portions 8, 8 is formed in opposition between the incident surface portion 4 and the reflecting surface portion 5 (in FIG. 1, only the near side is provided with a reference numeral). Therefore, the light incident on the incident surface portion 4 is reflected by the reflecting surface portion 5, the back surface portion 7, and the side surface portions 8, 8 and is emitted from the front surface portion 6. In addition, it is preferable that the reflective surface portion 5 and the back surface portion 7 and the side surface portions 8 and 8 serving as the reflective surfaces are mirror-finished, painted white, or subjected to metal vapor deposition to increase the reflection efficiency. .

  Further, a diffusion means such as a diffusion sheet is laminated on the surface (upper surface) of the surface portion 6 of the light guide plate 2, or fine unevenness processing or polishing processing is performed on the surface of the surface portion 6 so as to produce a diffusion effect. Thus, the uniformity of luminance (improvement of optical characteristics) may be achieved.

  As the back surface portion 7 approaches the reflecting surface portion 5 from the incident surface portion 4, a large number of inclined surfaces are inclined upward so as to approach the surface portion 6 side (since there are many inclined surfaces, they are not shown in FIG. Connecting the end portion of the inclined surface located on the incident surface portion 4 side to the reflecting surface portion 5 side and the end portion of the inclined surface located on the reflecting surface portion 5 side adjacent thereto to the incident surface portion 4 side. Since there are a large number of surfaces (similar to the inclined surfaces, they are not shown in FIG. 1 and are not provided with reference numerals), and are configured in a staircase shape. Further, the inclination angle of the inclined surface is configured to be larger as the inclined surface is farther from the incident surface portion 4.

  In FIG. 1, the back surface portion 7 has substantially the same thickness from the first region D1 where the thickness gradually increases from a specific position on the incident surface portion 4 side to the central portion, and a position slightly ahead of the reflecting surface portion 5 on the right end from the central portion. And a third region D3 whose thickness gradually decreases from a position before the reflective surface portion 5 to the reflective surface portion 5. These three regions are determined by setting the inclination angles of the inclined surfaces 9, 10, 11, 12, 13, and 14 to be described later.

  FIG. 2 is an enlarged view showing a large number of inclined surfaces of the back surface portion 7 not shown in FIG. In short, the characteristic configuration of the invention is shown in FIG. Accordingly, since FIG. 2 is a simplified diagram, the first region D1 to the third region D3, which are the three regions in FIG. 1, cannot be easily distinguished.

  As shown in FIG. 2, the back surface portion 7 is inclined so as to approach the surface portion 6 side as it approaches the reflecting surface portion 5 from the incident surface portion 4, that is, a plurality of inclinations (six in FIG. 2) that are upward. Surfaces 9, 10, 11, 12, 13, 14 and the inclined surface 9 or 10 or 11 or 12 or 13 located on the incident surface 4 side end on the reflective surface 5 side and the reflective surface 5 side adjacent thereto It is provided with connecting surfaces 15 or 16 or 17 or 18 or 19 (five in FIG. 2) for connecting the inclined surface 10 or 11 or 12 or 13 or 14 located on the incident surface portion 4 side. It is configured.

  In addition, the inclination angles of the inclined surfaces 9, 10, 11, 12, 13, 14 are configured to be larger as the inclined surface is away from the incident surface portion 4. That is, the inclination angle of the inclined surface 9 located at the left end in the drawing is the smallest, and the inclination angle gradually increases from the inclined surface 9 toward the inclined surface closer to the reflecting surface portion 5, and the inclination angle gradually increases toward the reflecting surface portion 5. The inclination angle of the closest inclined surface 14 at the right end is the largest.

  The connecting surfaces 15, 16, 17, 18, and 19 are inclined surfaces that are farther from the surface portion 6 toward the reflecting surface portion 5 side end portion. In other words, the connecting surfaces 15, 16, 17, 18, 19 are downward inclined surfaces whose upper ends are inclined to the incident surface portion 4 side with respect to the vertical direction (vertical direction connecting the front surface portion 6 and the back surface portion 7). ing.

  The inclined surfaces 9, 10, 11, 12, 13, 14 and the connecting surfaces 15, 16, 17, 18, 19 are preferably configured as flat surfaces. However, in some cases, the curved surfaces are convex or concave outward. You may comprise by a plane.

  Further, in FIG. 2, of the inclined surfaces 9, 10, 11, 12, 13, and 14, the inclined surface 9 located on the incident surface portion 4 side has the longest length and the inclined surface 13 located on the reflective surface portion 5 side. The other inclined surfaces 9, 10, 11, and 12 are configured to have the same length, but the inclined surface located from the incident surface portion 4 side to the reflecting surface portion 5 side has a longer length. On the contrary, the inclined surface located from the incident surface portion 4 side to the reflecting surface portion 5 side may be shortened. Furthermore, all the inclined surfaces may have the same length, or some or all of the inclined surfaces may have different lengths at random.

  3 shows a part of the back surface 7 of the first region D1 shown in FIG. 1 on the incident surface 4 side, and FIG. 4 shows the reflection surface 5 side of the third region D3 shown in FIG. A part is shown. Specifically, in FIG. 3, the inclination angle of the inclined surface 20 on the incident surface portion 4 side of the two inclined surfaces 20 and 21 with respect to the horizontal plane X1 is θ1, and the inclined surface 21 on the reflective surface portion 5 side is relative to the horizontal plane X2. The inclination angle is θ2, and the lengths of the two connecting surfaces 22 and 23 are L1 and L2. In FIG. 4, the inclination angle of the inclined surface 24 on the incident surface portion 4 side of the two inclined surfaces 24, 25 with respect to the horizontal plane X 3 is θn−1, and the inclined surface 25 on the reflective surface portion 5 side is inclined with respect to the horizontal plane X 4. The angle is θn, and the lengths of the coupling surfaces 26 and 27 are Ln−1 and Ln.

  At this time, the inclination angles θ1, θ2, θn−1, θn of the inclined surfaces 20, 21, 24, 25 and the lengths L1, L2, Ln−1, Ln of the connecting surfaces 22, 23, 26, 27 are expressed by the following equations. It is set so as to satisfy the conditions shown in.

θ1 <θ2 <θn-1 <θn, L1>L2>Ln-1> Ln
By configuring the light guide plate that satisfies the above conditions, as shown in FIG. 2, for example, as a comparative example, the inclined surfaces are horizontal planes 28, 29, 30, 31, 32, 33 indicated by broken lines, When the lengths of the connecting surfaces 34, 35, 36, 37, and 38 indicated by broken lines are the same as those of the connecting surfaces 15, 16, 17, 18, and 19 indicated by solid lines, the thickness of the light guide plate is the reflecting surface portion. The thickness of the light guide plate of the present invention indicated by a solid line can be reduced while the thickness of the light guide plate 5 is increased, and the light guide plate can be made thinner. In FIG. 2, the horizontal planes 28, 29, 30, 31, 32, 33 are shown. However, when the horizontal planes 28, 29, 30, 31, 32, 33 are inclined downward, the light guide plate The thickness increases, and the difference from the thickness of the light guide plate of the present invention indicated by the solid line in FIG. 2 becomes more prominent.

  In addition, the light guide plate and the illumination device according to the present invention are not limited to the above-described embodiments, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

  For example, the back surface part 7 can also be comprised by at least 1 area | region among the 1st area | region D1- 3rd area | region D3.

  Further, in the light guide plate according to the present invention, the first region D1 is configured to gradually increase in thickness from a specific position on the incident surface portion 4 side to the central portion, but this specific position is also an intersection with the incident surface portion 4. Good.

  In the light guide plate according to the present invention, the lengths of the connecting surfaces 15, 16, 17, 18, and 19 are configured to be shorter toward the reflecting surface portion 5, but all the connecting surfaces 15, 16, 17, and 18 are configured. , 19 may be configured to have the same length, or may be configured such that the length of some of the coupling surfaces is shorter than the length of the other coupling surfaces.

  In the light guide plate according to the present invention, the number of inclined surfaces is large, but any number may be provided as long as there are a plurality of inclined surfaces. In this case, the number of connecting surfaces is preferably one less than the number of inclined surfaces.

  Moreover, as a light source which comprises the illuminating device which concerns on the said embodiment, a point light source like a light emitting diode other than a linear light source may be sufficient. The number of the point light sources may be one or plural.

  The light guide plate and the illumination device according to the present invention have an effect of being able to achieve a reduction in size (thinning) while satisfying optical characteristics (for example, uniformity of luminance), and are used for backlights of various liquid crystal screens. Useful.

DESCRIPTION OF SYMBOLS 1 Light source 2 Light guide plate 3 Reflector 4 Incident surface part 5 Reflecting surface part 6 Front surface part 7 Back surface part 8 Side surface part 9-14 Inclined surface 15-19 Connection surface

Claims (4)

A front surface portion from which light from the light source is emitted, a back surface portion located on the opposite side opposite to the front surface portion, and a plurality of side surface portions positioned between the front surface portion and the back surface portion, and these side surface portions, A light guide plate comprising an incident surface portion on which light for exiting from the surface portion is incident, and a reflective surface portion that is positioned opposite to the incident surface portion and reflects light;
A plurality of inclined surfaces that are inclined so as to approach the surface portion side as the back surface portion approaches the reflecting surface portion side from the incident surface portion side, and an end portion of the inclined surface located on the incident surface portion side on the reflecting surface portion side And a connecting surface that connects an end of the inclined surface located on the side of the reflecting surface adjacent to the incident surface, and is configured in a staircase shape, and the inclination angle of the inclined surface is set on the side away from the incident surface. A light guide plate characterized in that the inclined surface has a larger angle. The light guide plate according to claim 1, wherein the connection surface is an inclined surface that is farther from the surface portion toward an end portion on a reflection surface portion side. The connection surface of a plurality of the connection surfaces is provided, and the connection surface connecting the two inclined surfaces is configured to be shorter as the connection surface on the reflection surface portion side. Light guide plate. The illuminating device provided with the light guide plate of any one of Claim 1 thru | or 3, and the light source for radiate | emitting light to this light guide plate.

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