JP2008047490A - Illumination device, and display device using this - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination device and a display device which have high brightness and in which there is no brightness uneavenness without using a prism sheet. <P>SOLUTION: A reflecting structure 6 having a reflecting face to refract or reflect light is formed on a light guide 2 in which light from LED 1 is made incident and emitted from an emitting face 2a of the upper face, and a light collecting means of collecting the light to the center part upward of the emitting face 2a is formed at least on one face of the faces on which the reflecting structure has been formed, that is, the emitting face 2a and an opposing face 2b opposed to this emitting face. Furthermore, the height of the perpendicular direction of a light-emitting face 1a of the LED 1 is made to be higher than that of the perpendicular direction of a light incident face 2c of the light guide 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a so-called sidelight type illumination device in which a light source is disposed on a side surface of a light guide, and a display device that performs display by illuminating a non-self-luminous display element using the illumination device. About.

  Conventionally, the light emitted from the LED is incident from the side surface of the light guide that guides the light, exits from the upper surface of the light guide, and this light is collected by the prism sheet to increase the brightness of the backlight. Lighting devices that improve are generally known. FIG. 7 shows a cross-sectional view of a lighting device using two conventional prism sheets. As shown in the drawing, a light guide 12 for guiding the light of the LED 10 is disposed on the side of the LED 10 that is a light source. A large number of grooves 11 are formed on a surface (hereinafter referred to as an opposing surface 12 b) opposite to a light emitting surface (hereinafter referred to as an output surface 12 a) of the light guide 12. The light incident on the light guide 12 is reflected by the groove 11 and is emitted at an angle of about 60 degrees with respect to the emission surface 12a of the light guide 12 as indicated by an arrow in FIG. In addition, a reflection sheet 13 that reflects light is disposed on the opposite surface side of the light guide 12, and a diffusion sheet 14 that diffuses light is disposed on the emission surface side of the light guide 12. Further, two prism sheets 15 that emit light while directing light in the vertical direction are stacked above the diffusion sheet 14. On the upper surface of the prism sheet 15, a large number of triangular convex portions (the convex portions are called prisms 16) having an apex angle of 90 degrees are formed in a row. The lower prism sheet 15a and the upper prism sheet 15b are arranged so that the prisms are substantially orthogonal to each other when viewed from above. Light emitted from the light guide 12 by these prism sheets 15 is directed in the vertical direction (see, for example, Patent Document 1).

FIG. 8 is a cross-sectional view of an illumination device that uses one prism sheet. As shown in the drawing, a light guide 12 having a large number of grooves 11 formed on the opposing surface 12b is disposed on the side of the LED 10. The light incident on the light guide 12 is reflected by the groove 11 and is emitted at an angle of approximately 30 degrees with respect to the emission surface 12a of the light guide 12 as indicated by an arrow in FIG. A reflection sheet 13 is disposed on the opposite surface side of the light guide 12, and an integrated prism sheet 17 that directs and emits light in the vertical direction is disposed on the emission surface side. A large number of prisms 16 having apex angles of 60 degrees are formed in a row on the lower surface of the prism sheet 17. The light emitted from the light guide 12 by the prism sheet 17 having such a configuration is directed in the vertical direction. Further, a diffusion sheet 14 is disposed on the upper surface of the prism sheet 17 (see, for example, Patent Document 2).
JP-A-8-271774 (FIG. 1) JP 2000-215719 A (FIGS. 3 and 4)

  In the illumination devices disclosed in Patent Documents 1 and 2, a prism sheet is indispensable for directing outgoing light emitted from the light guide in the vertical direction of the light guide. The thickness and weight of the device will increase. Furthermore, there is a problem that the cost of the lighting device increases due to the use of a high-cost prism sheet.

  Also, when the prism pitch of the prism sheet and the pixel pitch of the liquid crystal panel are substantially the same width or an integral multiple, the prism pitch and the pixel pitch interfere with each other, and a light and dark pattern appears when the illumination device is viewed from the front. There is a problem that it ends up.

  Therefore, an object of the present invention is to realize an illumination device and a display device that have high luminance and no luminance unevenness without using a prism sheet.

  In order to solve the above-described problems, the illumination device of the present invention is configured such that a reflection structure having a reflection surface that refracts or reflects light is formed on at least one of the exit surface and the opposing surface of the light guide, Condensing means for collecting light was formed in the vicinity of the surface above the center of the exit surface. An inclined surface formed on at least one of the exit surface and the opposing surface of the light guide is used as the light collecting means. This inclined surface was formed on the outer periphery of the light guide. Alternatively, the inclined surface is formed on the light incident surface side. The height of the light incident surface of the light guide is lower than the height of the light emitting surface of the light source.

  In addition, since the display device of the present invention includes the illumination device having any of the above-described structures and a non-self-luminous display element, a display device with high luminance and no luminance unevenness can be realized without using a prism sheet. can do.

  According to the present invention, a display device with high luminance and no luminance unevenness can be realized without using a prism sheet.

  The illuminating device of the present invention includes a light incident surface on which light from a light source is incident, an emission surface that guides the light and emits light, and a light guide that has a facing surface facing the emission surface, A plurality of reflecting structures having reflecting surfaces that refract or reflect light are formed on at least one of the exit surface and the opposing surface. Then, at least one of the exit surface and the opposing surface in the vicinity of the light entrance surface is formed with a condensing means for condensing the light above the central portion of the exit surface. According to such a configuration, the luminance can be set to be optimal according to the viewpoint of the observer of the illumination device or the display device without using a prism sheet. Here, as the light condensing means, an inclined surface was formed on at least one of the exit surface and the opposing surface. This inclined surface is formed in contact with the light incident surface. In such a configuration, it is not necessary to separately prepare a condensing part, so that the man-hour and cost can be reduced. Moreover, this inclined surface may be formed on the opposite side of the light incident surface of the light guide, or may be formed over the outer periphery of the light guide. If the range of the inclination angle of the inclined surface is about 0.1 to 30 degrees, the light can be condensed at the center. The inclined surface on the light incident surface side and the inclined surface on the opposite side to the light incident surface may be configured to have different angles with respect to the exit surface. Depending on the size of the light guide and the position of the viewpoint, it may be better to configure the angles different from each other.

  Further, the light emitting surface of the light source is configured to be higher than the height of the light incident surface of the light guide. According to such a configuration, since the angle at which the light emitted from the light emitting surface enters the inclined surface can be increased, the light can be refracted more greatly. Therefore, the light condensing ability to the upper part of the emission surface central portion can be enhanced. Furthermore, since the light collecting ability can be increased without increasing the thickness of the light guide, the lighting device can be made thinner.

  Alternatively, the center line in the height direction of the incident surface and the center line in the height direction of the light emitting surface of the light source are configured to substantially coincide. According to such a configuration, since high-intensity light emitted from the central portion of the light emitting surface can be efficiently incident on the incident surface, the ability to collect light toward the upper central portion of the outgoing surface can be increased. .

  Further, a point light source is used as the light source, and a plurality of reflecting structures are arranged so that the reflecting surface of the reflecting structure faces the light emitting surface of the light source. For example, the reflection structure is arranged on a concentric circle centering on the point light source. According to such an arrangement, it is possible to make the reflection efficiency uniform on the light emitting surface and reduce unevenness in the light emitting surface.

  In addition, the display device of the present invention includes a non-self-luminous display element on the exit surface side of the illumination device having the above-described configuration. According to such a configuration, a display device having high luminance and no luminance unevenness can be realized without using a prism sheet.

  Embodiments of a lighting device and a display device according to the present invention will be described below with reference to the drawings. Here, a configuration using an LED element as a light source and a liquid crystal panel as a non-self-luminous display element will be described.

  FIG. 1 schematically shows a cross-sectional configuration of a display device having the illumination device of this embodiment. As shown in the drawing, a light guide 2 that guides light emitted from the LED 1 is disposed on the side of the LED 1 that emits light. The light guide 2 has a surface that emits light (this surface is referred to as an output surface 2a) and a surface that faces the output surface 2a (this surface is referred to as an opposing surface 2b). A number of concave reflecting structures 6 that refract and reflect light are formed. The reflecting structure 6 includes a reflecting surface that refracts or reflects light. An inclined surface 7 was formed on the LED1 side portion of the light exit surface 2a of the light guide 2. That is, the cross-sectional shape of the exit surface 2a of the light guide 2 is a trapezoid. Here, the light guide 2 is configured such that the angle formed between the inclined surface 7 and the exit surface 2a is within a range of 0.1 degrees to 30 degrees. Further, as shown in the drawing, a reflection sheet 3 that reflects light is disposed on the opposite surface side of the light guide 2, and a diffusion sheet 4 that diffuses light is disposed on the exit surface side of the light guide 2. . Further, a liquid crystal panel 5 that is a non-self-luminous display element is disposed above the diffusion sheet 4. Here, although LED1 was used as a light source, you may use a cold cathode tube etc. as a light source besides this.

  The reflection structure 6 formed on the light guide 2 is not attached as a separate member, but is formed by a concave portion recessed inward on the facing surface 2 b of the light guide 2. In this embodiment, since the light guide 2 is formed by molding a resin, it is easy to form the reflection structure 6 at the same time when the light guide 2 is molded. Here, the light guide 2 is made of polycarbonate, and the refractive index of the light guide 2 is about 1.58. The light guide 2 may be formed using other materials such as acrylic.

  In the above description, the configuration in which the reflective structure 6 is formed on the opposing surface 2b of the light guide 2 is taken as an example, but the formation position of the reflective structure 6 is not limited thereto. FIG. 2 is a schematic view illustrating another formation site and the like of the reflection structure 6. That is, FIG. 2A shows a configuration in which the reflecting structure 6 is formed on the exit surface 2a, and FIG. 2B shows a configuration in which the reflecting structure 6 is formed on both the opposing surface 2b and the exit surface 2a. The reflection structure 6 is not limited to a concave shape, and may be a convex reflection structure 6. In addition, it will be apparent to those skilled in the art that various combinations other than the above-described reflection structure 6 are possible.

  Next, the positional relationship between the light incident portion of the light guide and the LED in this embodiment will be described with reference to the drawings. The appearance of the LED 1 is schematically shown in FIG. The LED 1 emits light from a specific surface. This surface is referred to as a light emitting surface 1a. The LED 1 has a configuration in which the light emitting element is covered with a resin containing a phosphor. Therefore, the light of the light emitting element is scattered by the phosphor in the resin and emitted from the light emitting surface 1a. Although scattered in this way, the luminance of the central portion of the light emitting surface 1a is slightly higher than that of the outer peripheral portion. FIG. 4 is a cross-sectional view illustrating the positional relationship between the light incident portion of the light guide and the light emitting surface of the LED. As illustrated, the inclined surface 7 is formed on the light incident surface side of the light guide 2, and the height h of the light incident surface 2 c of the light guide 2 is lower than the height H of the light emitting surface 1 a of the LED 1. ing. By increasing the angle formed by the inclined surface 7 and the exit surface 2a of the light guide 2, light can be refracted more greatly.

  Further, FIG. 4A shows a configuration in which the center line in the height direction of the light incident surface 2c of the light guide 2 and the center line in the height direction of the light emitting surface 1a of the LED 1 are aligned. Thereby, the high-intensity light radiate | emitted from the center part of the light emission surface 1a can be efficiently entered in the light-incidence surface 2c. 4B, the lower end of the light incident surface 2c of the light guide 2 and the lower end of the light emitting surface 1a of the LED 1 may be aligned with each other. In this case, it is desirable to provide the inclined surface 7 on the opposing surface. Or you may arrange | position so that the upper end of the light-incidence surface 2c of the light guide 2 and the upper end of the light emission surface 1a of LED1 may correspond, as shown in FIG.4 (c). In this case, it is desirable to provide the inclined surface 7 on the exit surface. Moreover, in the structure shown in FIG.4 (b) and FIG.4 (c), since the light guide 2 can be installed on the basis of LED1, positioning of LED1 and the light guide 2 becomes easy.

  FIG. 5 schematically shows the light emission direction of the light guide 2 having a flat emission surface 2a and the light guide 2 having the inclined surface 7 as in this embodiment. Although not shown, the left end surface of the light guide 2 in the drawing is the light incident surface 2c, and the LEDs are provided so as to face the light incident surface. Here, description will be made assuming the viewpoint Vp of the observer who actually uses the light from the illumination device. FIG. 5A shows a configuration in which the light exit surface 2a of the light guide 2 is flat. In such a configuration, as indicated by an arrow in the figure, the light emitted from the emission surface 2a is emitted in a direction perpendicular to the emission surface 2a. On the other hand, FIG. 5B shows a configuration in which the exit surface 2a includes the inclined surface 7. In such a configuration, the light passing through the exit surface 2a exits in a direction perpendicular to the exit surface 2a as shown by the arrows in the figure, but the light passing through the inclined surface 7 is refracted in the direction of the viewpoint Vp. Thus, in the illuminating device of the present embodiment, the light is collected at the viewpoint Vp, and the luminance at the viewpoint Vp can be increased. In addition, the slope provided on the light incident surface side (left side slope in the figure) and the slope provided on the opposite side of the light entrance surface (right slope in the figure) are formed by the respective slopes and the exit surface. You may comprise so that an angle may differ. It is more effective to set the angle of the slope depending on the size of the light guide and the position of the viewpoint Vp. Moreover, since the inclined surface 7 formed in at least one of the output surface 2a or the opposing surface 2b of the light guide 2 is used as the condensing means, it is not necessary to prepare components for condensing, and man-hours and costs are reduced. Can be reduced.

  FIG. 6 is an external view schematically showing the light guide 2 and the LED 1 in which the inclined surface 7 is formed over the entire circumference of the emission surface 2a. It is obvious that the light condensing ability is increased by forming the inclined surface 7 as the light condensing means not only in the vicinity of the light incident surface 2c but also on the entire circumference of the light emitting surface 2a.

  As described above, according to the present invention, brightness and unevenness that do not cause a practical problem can be realized without a prism sheet. However, a prism sheet is provided on the exit surface side of the illumination device of the present invention to emit light from the viewpoint of the observer. Needless to say, it can also be collected.

  The illumination device and the display device according to the present invention can be applied to display devices such as a mobile phone, a PDA, a car navigation system, and a television.

It is sectional drawing which shows the structure of the display apparatus of this invention typically. It is sectional drawing which shows the structure of the display apparatus of this invention typically. It is a schematic diagram explaining LED used by this invention. It is a schematic diagram explaining the positional relationship of LED and a light guide used by this invention. It is a perspective view which shows typically the external appearance of the illuminating device of this invention. It is a figure which shows typically the emission direction of the light from a light guide. It is sectional drawing of the illuminating device which uses two conventional prism sheets. It is sectional drawing of the illuminating device which uses one sheet of the conventional prism sheets.

Explanation of symbols

1 LED
DESCRIPTION OF SYMBOLS 1a Light emission surface 2 Light guide 2a Output surface 2b Opposing surface 2c Light incident surface 3 Reflective sheet 4 Diffusion sheet 5 Liquid crystal panel 6 Reflective structure 7 Inclined surface

Claims (12)

A light source having a light emitting surface;
A light guide having a light incident surface on which light from the light source is incident, an emission surface that emits the light, and a facing surface that faces the emission surface;
Condensing means for condensing the light above the central portion of the exit surface, formed on at least one of the exit surface and the opposing surface in the vicinity of the light entrance surface;
A lighting device comprising: a plurality of reflecting structures formed on at least one of the emitting surface and the opposing surface and having a reflecting surface that refracts or reflects the light.   The lighting device according to claim 1, wherein a vertical direction of the light emitting surface is larger than a vertical direction of the light incident surface.   The lighting device according to claim 2, wherein the vertical center of the light emitting surface and the vertical center of the light incident surface substantially coincide with each other.   The lighting device according to claim 2, wherein the lower end of the vertical height of the light emitting surface and the lower end of the vertical height of the light incident surface are substantially aligned.   The lighting device according to claim 4, wherein the light collecting means is an inclined surface formed on the light exit surface.   The lighting device according to claim 2, wherein an upper end of a vertical height of the light emitting surface and an upper end of a vertical height of the light incident surface are substantially aligned with each other.   The lighting device according to claim 6, wherein the condensing means is an inclined surface formed on the facing surface.   The lighting device according to claim 5, wherein the inclined surface is formed so as to be in contact with the light incident surface.   The illumination device according to claim 5 or 7, wherein an angle formed by the inclined surface and the emission surface is 0.1 to 30 degrees.   The lighting device according to claim 8, wherein a second inclined surface is formed so as to be in contact with a side surface of the light guide facing the light incident surface.   The lighting device according to claim 10, wherein an angle formed between the inclined surface and the emission surface is different from an angle formed between the second inclined surface and the emission surface.   A display device comprising: the illuminating device having the structure according to claim 1; and a non-self-luminous display element provided on an emission surface side of the illuminating device.

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