JP2008269866A - LIGHTING DEVICE, LIQUID CRYSTAL DISPLAY DEVICE, AND ELECTRONIC DEVICE - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To switch emission characteristics of outgoing light while uniformly keeping the surface luminance distribution. <P>SOLUTION: The illumination device has a light guide plate 16, a first light source 17A which makes a light LA incident on a first end face 16A of this light guide plate, and a second light source 17B which makes light LB incident on a second end face 16B opposite to the first end face of the light guide plate. The first light source and the second light source are installed so that incident directions of incident light LA, LB to the light guide plate are opposite to each other. In the light guide plate, a characteristic adjusting part 40 for adjusting the emission characteristics at emitting the incident light from the light guide plate is installed at each of a first light source and a second light source, respectively. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lighting device, a liquid crystal display device, and an electronic apparatus.

In recent years, a liquid crystal display device such as a liquid crystal panel is mounted and used as an image display unit of various electronic devices. For example, a liquid crystal display device is suitably used for a display unit of a mobile device such as a mobile phone because of the advantages of being thin and light and having low power consumption.
In the backlight system used in this liquid crystal display device, an edge light structure in which a light source is arranged on one side of a light guide plate is often used, and in this structure, in order to obtain luminance and viewing angle according to specifications. In order to emit the shape of the light guide plate, particularly incident light (incident light) to the liquid crystal display panel side, prisms and dots are formed on the reflection surface and the emission surface.

For example, Patent Document 1 discloses a technique in which a linear light source is disposed on two opposing side surfaces of a light guide plate to improve luminance and reduce thickness. In Patent Document 2 and Patent Document 3, a light source is arranged on two opposite side surfaces of the light guide plate, a prism shape is formed on the reflection surface of the light guide plate, and the light source is switched to change the viewing angle characteristics (high directivity). A technique for performing control to switch emission characteristics such as a directivity and a low directivity is disclosed.
Japanese Patent Laid-Open No. 6-230228 JP 2005-243545 A JP 2006-66282 A

However, the following problems exist in the conventional technology as described above.
Although it is possible to switch the viewing angle characteristics by switching the light source, the shape and position of the prisms etc. formed on the light guide plate are fixed and constant, so the in-plane luminance distribution is likely to be non-uniform . In other words, since the amount of light that normally enters the light guide plate from the light source decreases in the direction of travel, the arrangement density of the prisms formed for launching the light beam is set from coarse to dense from the light source side. Even if the coarse / dense pattern of the prism is formed corresponding to one of the opposing light sources, when the light source is switched to the other light source, the dense / rough pattern is formed from the light source side, and the in-plane of light emitted from the light guide plate It is considered that the luminance distribution becomes uneven.

  The present invention has been made in consideration of the above points, and an illumination device, a liquid crystal display device, and an electronic apparatus that can switch the emission characteristics of emitted light such as viewing angle characteristics while maintaining a uniform distribution of in-plane luminance The purpose is to provide.

In order to achieve the above object, the present invention employs the following configuration.
The illumination device of the present invention causes light to be incident on a light guide plate, a first light source that causes light to enter the first end surface of the light guide plate, and a second end surface that faces the first end surface of the light guide plate. The first light source and the second light source are provided with incident light incident on the light guide plate in opposite directions, and the incident light is incident on the light guide plate. A characteristic adjusting unit that adjusts an emission characteristic when the light is emitted from the light guide plate is provided for each of the first light source and the second light source.
Therefore, in the illumination device of the present invention, the light incident on the light guide plate from the first light source and the light incident on the light guide plate from the second light source have the emission characteristics when emitted from the light guide plate respectively by the characteristic adjustment unit. Since it is possible to adjust, it is possible to emit with desired emission characteristics while maintaining a uniform distribution of in-plane luminance regardless of which light source is used.

As the first light source and the second light source, a configuration in which a plurality of at least one are arranged with the incident light incident directions adjacent to each other on the light guide plate being opposite to each other can be suitably employed.
Thereby, in this invention, it can suppress that the incident light from a 1st light source or a 2nd light source injects with the distribution unevenly in a light-guide plate, and is radiate | emitted as an emitted light.

As the characteristic adjusting unit, it is possible to suitably employ a configuration in which the characteristic adjusting unit is arranged with a distribution corresponding to the incident direction of the incident light.
As a result, in the present invention, the characteristic adjustment unit is roughly arranged from the incident direction side and the traveling direction side is arranged densely, so that it is possible to use either the first light source or the second light source. The luminance distribution can be kept uniform.

As the characteristic adjusting unit, a configuration in which a prism extending in a direction substantially orthogonal to the incident direction of the incident light or a configuration formed by a pattern of a plurality of dots can be suitably employed.
Thus, in the present invention, the emission characteristics can be easily adjusted by adjusting the arrangement density of the prisms and dots.

Moreover, in this invention, the structure by which the said characteristic adjustment part is provided with a different radiation | emission characteristic for every said 1st light source and said 2nd light source can be employ | adopted suitably.
In this configuration, the characteristic adjusting unit is provided according to the first light source and provided according to the second light source and the first characteristic adjusting unit that specularly reflects incident light from the first light source. And a second characteristic adjusting unit that diffusely reflects incident light from the second light source.
Thereby, in this invention, the light which injected into the light-guide plate from the 1st light source is radiate | emitted from a light-guide plate with high directivity by carrying out specular reflection in the 1st adjustment part. Therefore, by making light incident from the first light source, the emitted light can be emitted with high luminance, and the viewing angle can be limited so that the display is difficult to read by anyone other than the user. On the other hand, in the present invention, light incident on the light guide plate from the second light source is diffused and reflected by the second adjustment unit, and is emitted from the light guide plate with low directivity. Therefore, it becomes possible to emit the emitted light with a wide viewing angle by making the light incident from the second light source. Furthermore, in the present invention, high luminance and a wide viewing angle can be achieved by making light incident on the light guide plate from both the first light source and the second light source.

In the above configuration, the first characteristic adjustment unit includes a specular reflection surface provided facing the first light source and a diffuse reflection surface provided facing the second light source. It can be suitably employed.
As a result, in the present invention, it is possible to suppress the light incident from the second light source from being specularly reflected and emitted from the light guide plate in the first characteristic adjustment unit, and to diffuse the diffuse reflection surface, thereby widening the viewing angle. It is also possible to increase the luminance while ensuring it.

In the above configuration, the second characteristic adjustment unit includes a second diffuse reflection surface provided facing the second light source, and a third diffuse reflection surface provided facing the first light source. A configuration having the above can be suitably employed.
Accordingly, in the present invention, it is possible to suppress the light incident from the first light source from being specularly reflected and emitted as stray light (or re-reflected) in the second characteristic adjustment unit, and to be diffused by the diffuse reflection surface. Thus, it is possible to increase the luminance while ensuring a wide viewing angle.

Moreover, in this invention, the structure provided with the light source control apparatus which selectively lights at least one of a said 1st light source and a said 2nd light source can also be employ | adopted suitably.
Thus, in the present invention, a high luminance (high directivity) mode with a limited viewing angle, a wide viewing angle (low directivity) mode, and a high luminance and wide viewing angle mode can be easily selected and switched. Is possible.

A liquid crystal display device according to the present invention includes the above-described illumination device and a liquid crystal cell into which illumination light emitted from the illumination device is incident.
In addition, an electronic apparatus according to the present invention includes the liquid crystal display device described above.
Therefore, according to the liquid crystal display device and the electronic apparatus of the present invention, since the illumination device of the present invention described above is provided, the surface can be obtained even when either the first light source or the second light source is used. It is possible to emit with desired emission characteristics while keeping the inner luminance distribution uniform. Therefore, according to the present invention, it is possible to obtain a high-quality and high-functional liquid crystal display device and electronic apparatus that can switch the visual field range of display with a uniform luminance distribution as necessary.

Hereinafter, embodiments of an illumination device, a liquid crystal display device, and an electronic apparatus according to the present invention will be described with reference to FIGS.
(Liquid crystal display device)
The liquid crystal display device (electro-optical device) of this embodiment is an example of an active matrix type transmissive liquid crystal display device using a thin film transistor (hereinafter abbreviated as TFT) as a switching element. Back light (illumination device). 1A is a perspective view showing the overall configuration of the liquid crystal display device, FIG. 1B is an enlarged view of one pixel in FIG. 1A, FIG. 2 is a sectional view of the liquid crystal display device, and FIG. It is a perspective view which shows the structure of the backlight used for a liquid crystal display device equally.
In all the following drawings, the ratio of dimensions of each component is appropriately changed for easy understanding of the drawings. In FIG. 2, illustration of wiring on the inner surface side of each substrate, switching elements, electrodes, alignment films, and the like is omitted.

  As shown in FIG. 1A, the liquid crystal display device 1 according to the present embodiment includes a liquid crystal cell 15, a light guide plate 16, an LED (first light source) 17A, and an LED (second light source) disposed on the outer surface thereof. The backlight 18 (illuminating device) having a light source 17B (not shown in FIG. 1, see FIG. 2).

In the liquid crystal cell 15, the element substrate 2 on the side where the TFT is formed and the counter substrate 3 are arranged to face each other, and a liquid crystal layer (not shown) is sealed between the substrates 2 and 3.
On the inner surface side of the element substrate 2, a large number of source lines 4 and a large number of gate lines 5 are provided in a lattice shape so as to intersect each other. A TFT 6 is formed in the vicinity of the intersection of each source line 4 and each gate line 5, and a pixel electrode 7 is connected to each other through each TFT 6. That is, one TFT 6 and pixel electrode 7 are provided for each pixel arranged in a matrix. On the other hand, a common electrode 8 is formed on the entire inner surface of the counter substrate 3 over the entire display region in which a large number of pixels are arranged in a matrix.

  In this specification, the surface on the liquid crystal layer side of each substrate constituting the liquid crystal cell 15 is referred to as an “inner surface”, and the opposite surface is referred to as an “outer surface”. In this specification, the direction in which the source line 4 extends is referred to as the Y-axis direction, the direction in which the gate line 5 extends is referred to as the X-axis direction, and the direction perpendicular to the Y-axis and X-axis is referred to as the Z-axis direction.

  As shown in FIG. 1B, the TFT 6 includes a gate electrode 10 extending from the gate line 5, an insulating film (not shown) covering the gate electrode 10, and polycrystalline silicon, amorphous silicon, etc. formed on the insulating film. A semiconductor layer 11, a source electrode 12 extending from a source line 4 electrically connected to a source region in the semiconductor layer 11, and a drain electrode 13 electrically connected to a drain region in the semiconductor layer 11. Have. The drain electrode 13 of the TFT 6 is electrically connected to the pixel electrode 7. The pixel electrode 7 is formed of a transparent conductive film such as ITO, and the common electrode 8 on the counter substrate 3 side is also formed of a transparent conductive film such as ITO.

  Looking at the cross-sectional structure of the liquid crystal display device 1, as shown in FIG. 2, an upper polarizing plate 20 is provided on the outer surface of the upper glass substrate 19 constituting the counter substrate 3, and R (red) and G (green) are provided on the inner surface side. ), B (blue) color filter 21 having each color material layer is provided. Although not shown, a common electrode and an alignment film are formed on the color filter 21. On the other hand, a lower polarizing plate 23 is provided on the outer surface of the lower glass substrate 22 constituting the element substrate 2. Although not shown, the gate line 5, the source line 4, the TFT 6, and the pixel electrode 7 are formed on the inner surface side of the lower glass substrate 22, and an alignment film is formed. A liquid crystal layer 27 made of TN liquid crystal having a positive dielectric anisotropy is sealed between the substrates 2 and 3.

  The backlight 18 is disposed on the light guide plate 16, the LED 17 </ b> A disposed on the −X side end surface (first end surface) 16 </ b> A, and the + X side end surface (second end surface) 16 </ b> B facing the end surface 16 </ b> A. A reflection sheet 29 having a mirror surface is provided on the outer surface side (−Z side) of the light guide plate 16. A diffusion sheet 30 and two prism sheets 31 and 32 are sequentially provided from the inner surface side (+ Z side) of the light guide plate 16, that is, between the light guide plate 16 and the element substrate 2 of the liquid crystal cell 15 from the light guide plate 16 side. Yes.

  The diffusion sheet 30 has a function of uniformly diffusing light emitted from the light guide plate 16 in order to eliminate luminance unevenness. Each of the prism sheets 31 and 32 is formed by arranging a plurality of ridges having a triangular cross section extending in one direction in a stripe shape, and collects light in a direction (cross sectional direction) orthogonal to the extending direction of the convex shape. It has a function to shine. Each of the prism sheets 31 and 32 is arranged so that the peak of the ridges having a triangular cross section faces upward, and the apex angle of the triangle is set to about 80 ° to 110 °. The two prism sheets 31 and 32 are arranged so that the light collecting directions are orthogonal to each other.

  As shown in FIGS. 3 and 4, a plurality of LEDs 17 </ b> A are arranged along the end face 16 </ b> A of the light guide plate 16 at intervals. Similarly, a plurality of LEDs 17 </ b> B are arranged along the end surface 16 </ b> B of the light guide plate 16 at intervals. More specifically, the four LEDs 17A are arranged at equal intervals including the positions facing both ends of the end face 16A of the light guide plate 16, and each emits light LA in the + X direction, and the end face 16A. To the light guide plate 16. The three LEDs 17B are arranged so as to be positioned between the LEDs 17A to 17A with respect to the Y-axis direction along the end faces 16A and 16B, respectively, so that the LEDs 17A are opposite to each other with respect to the light LA emitted by the LEDs 17A. Emits light LB in the −X direction and enters the light guide plate 16 from the end face 16B.

That is, the LEDs 17 </ b> A and 17 </ b> B are provided with incident light LA and LB that are adjacent in the Y-axis direction on the light guide plate 16 in opposite directions.
The LEDs 17A and 17B are turned on and off individually by the control device (light source control device) CONT shown in FIG.

  As shown in FIGS. 2 and 3, a groove-like recess 40 extending in the Y-axis direction substantially orthogonal to the incident direction of the light LA and LB is formed on the bottom surface 16D located on the −Z side of the light guide plate 16. It is formed as a characteristic adjustment unit that adjusts the emission characteristics when the incident lights LA and LB are emitted from the light guide plate 16. As shown in FIG. 4, a plurality of the concave portions 40 are spaced apart from each other along the traveling directions (X-axis direction) of the light LA and LB emitted by the LEDs 17A and 17B, corresponding to the LEDs 17A and 17B. Arranged recess rows are formed.

  Specifically, among the recesses 40, the recess rows 40A provided corresponding to the LEDs 17A are arranged in a density distribution that gradually increases from coarse to dense as the recesses 40 move in the traveling direction of the light LA (+ X direction). Has been. Similarly, in the recesses 40, the recess rows 40B provided corresponding to the LEDs 17B are arranged in a density distribution that gradually increases from coarse to dense as the recesses 40 move in the traveling direction of the light LB (the -X direction). ing. That is, in the recess rows 40A and 40B, the adjacent recesses are provided at a density opposite to each other and separated according to the incident directions of the light LA and LB.

FIG. 5A is an enlarged cross-sectional view of the recesses 40 arranged in the recess row 40A, and FIG. 5B is an enlarged cross-sectional view of the recesses 40 arranged in the recess row 40B.
As shown in FIG. 5A, the recess 40 of the recess array 40A as the first characteristic adjustment unit corresponding to the LED 17A includes two inclined surfaces 41A and 41B, and the inclined surfaces 41A and 41B form a prism. . The inclined surface 41A formed facing the LED 17A is mirror-finished here by turning or grinding, and constitutes a mirror-reflecting surface that regularly reflects incident light. The inclination angle αA of the inclined surface 41A with respect to the bottom surface 16C is set in the range of 30 to 75 degrees, more preferably in the range of 45 degrees ± 15 degrees, in order to efficiently emit light toward the liquid crystal cell 15, and this embodiment Is set to 50 degrees.

  On the other hand, the inclined surface 41B formed facing the LED 17B is formed with a predetermined roughness by cutting or the like, and constitutes a diffuse reflection surface that diffuses incident light. The roughness of the inclined surface 41B is preferably, for example, 2 to 3 μm in Ra in order to efficiently diffuse and reflect. Further, as the inclination angle βA of the inclined surface 41B with respect to the bottom surface 16C, in order to suppress the directivity of the emitted light emitted toward the liquid crystal cell 15, the inclination angle βA is 20 degrees in this range, which is outside the inclination angle αA of the inclined surface 41A. Is set to about.

  Similarly, as shown in FIG. 5B, the concave portion 40 of the concave portion row 40B as the second characteristic adjusting portion corresponding to the LED 17B is composed of two inclined surfaces 42A and 42B, and the prisms are formed by these inclined surfaces 42A and 42B. There is no. The inclined surface 42B formed facing the LED 17B is formed with a predetermined roughness by cutting or the like, and constitutes a diffuse reflection surface (second diffuse reflection surface) that diffuses incident light. The roughness of the inclined surface 42B is preferably equal to that of the inclined surface 41B in order to efficiently diffuse and reflect. The inclination angle αB of the inclined surface 42B with respect to the bottom surface 16C is the same as the inclination angle αA of the inclined surface 41A in order to obtain a certain level of brightness while suppressing the directivity of the emitted light emitted toward the liquid crystal cell 15. Further, it is set in the range of 30 to 75 degrees, more preferably in the range of 45 degrees ± 15 degrees, and in this embodiment, it is set to 40 degrees.

  On the other hand, the inclined surface 42A formed facing the LED 17A is formed with a predetermined roughness by cutting or the like, similar to the inclined surface 42B, and diffuses and reflects the incident light (third diffuse reflection). The surface). The roughness of the inclined surface 42A and the inclination angle βB with respect to the bottom surface 16C are set to be equivalent to the inclined surface 41B.

  In addition, the depth (height) of the recesses 40 is preferably about 1 to 30 μm, and is set to 5 μm in the present embodiment. Further, the length of each recess 40 extending in the Y-axis direction is preferably about 1/7 to 1/8 of the length of the light guide plate 16 (end surfaces 16A, 16B), and is set to 2/15 in this embodiment. Has been.

Next, the operation of the liquid crystal display device 1 having the above configuration will be described.
First, when the LED 17A is turned on with the LED 17B turned off, the light LA incident on the light guide plate 16 from the LED 17A via the end face 16A is regularly reflected by the inclined surface 41A in the recess row 40A and is highly directed. The light is emitted from the upper surface (emission surface) 16 </ b> D of the light guide plate 16 and enters the liquid crystal cell 15 as illumination light through the diffusion sheet 30 and the prism sheets 31 and 32. At this time, since the recesses 40 in the recess row 40A are arranged in a density distribution that gradually increases from coarse to dense in the direction of travel of the light LA, even when the light quantity of the light LA decreases in the direction of travel. Since the amount of light reflected on the far side in the traveling direction increases from the near side, the in-plane luminance distribution of the light emitted from the light guide plate 16, that is, the in-plane luminance distribution of the incident light to the liquid crystal cell 15 can be made uniform. it can.
Further, a part of the light LA incident on the light guide plate 16 is incident on the inclined surface 42A of the concave portion 40 in the concave portion row 40B. However, since these surfaces are diffuse reflection surfaces, they are incident on the inclined surface 42A. The light LA diffuses and the adverse effect on the high directivity of the light LA emitted from the light guide plate 16 is suppressed.

On the other hand, when the LED 17B is turned on while the LED 17A is turned off, the light LB incident on the light guide plate 16 from the LED 17B through the end face 16B is mainly diffusely reflected by the inclined surface 42B in the recess row 40B and has a low directivity. The light is emitted from the upper surface (exiting surface) 16D of the light guide plate 16 with a characteristic (wide viewing angle), and enters the liquid crystal cell 15 as illumination light through the diffusion sheet 30 and the prism sheets 31 and 32. Also in this case, since the concave portions 40 in the concave row 40B are arranged in a density distribution that gradually increases from coarse to dense as the light LB travels, the light amount of the light LB decreases as it travels. However, since the amount of light reflected at the far side in the traveling direction increases from the near side, the in-plane luminance distribution of the emitted light from the light guide plate 16, that is, the in-plane luminance distribution of the incident light to the liquid crystal cell 15 is made uniform. Can do.
A part of the light LB incident on the light guide plate 16 is incident on the inclined surface 41B of the concave portion 40 in the concave portion row 40A. However, since these surfaces are diffuse reflection surfaces, the light LB is incident on the inclined surface 41B. The light LB diffuses and the adverse effect on the low directivity (wide viewing angle) of the light LA emitted from the light guide plate 16 is suppressed.

  FIG. 6 is a graph showing the luminance distribution of illumination light (emitted light) emitted from the backlight 18 shown in FIGS. In FIG. 6, the horizontal axis represents the angle from the normal line of the exit surface 16D, and the vertical axis represents the luminance of the emitted illumination light. The solid line, the alternate long and short dash line, and the alternate long and two short dashes line in the figure all indicate the luminance distribution with respect to the angle of the illumination light, and the distribution RA indicated by the solid line is that of the illumination light of the highly directional light LA, The distribution RB indicated is that of the light LB with low directivity, and the distribution RAB indicated by the two-dot chain line is that of the combined illumination light obtained by integrating the light LA and the light LB. The light LA having the luminance distribution RA indicated by the solid line has a narrow peak shape, and the luminance rapidly decreases when the angle from the normal line of the exit surface 16D exceeds 20 °. Has high directivity. On the other hand, the light LB having the luminance distribution RB indicated by the one-dot chain line has a gentle and wide peak shape, and the luminance hardly changes even if the angle from the normal line from the emission surface 16D exceeds 60 °. The directivity in the angular direction of the peak position is low. Furthermore, the combined illumination light having the luminance distribution RAB indicated by the two-dot chain line is obtained by integrating the solid line and the one-dot chain line, and becomes bright with wide directivity.

In the case of the light LA having high directivity, the luminance is drastically lowered when the light LA deviates from the peak position direction, and the illumination light can be observed only within a limited angle range. If such illumination light is used for a display device, the luminance is suddenly lowered at an angle deviated from the peak position, so that the visual field range of display is narrowed. On the other hand, the light LB with low directivity has a wide peak shape of the luminance distribution, so that the luminance of the illumination light does not decrease from any angle. When such illumination light is used for a display device, the visual field range of display is widened.
Therefore, if the light LA having a high directivity is emitted by turning on the LED 17A and the light LB having a low directivity is emitted by turning on the LED 17B by the control of the control device CONT, the light source is turned on and off easily and reliably. The directivity of the illumination light emitted from the backlight 18, that is, the visual field range can be switched. Furthermore, if both light sources are turned on at the same time, illumination light having high directivity and extremely high luminance can be obtained as shown by a two-dot broken line.

  As described above, in the present embodiment, the concave columns 40A and 40B are provided corresponding to the LEDs 17A and 17B whose incident directions to the light guide plate 16 are opposite to each other. By setting the density distribution of the recesses 40 in accordance with the incident direction of the incident light, the emission characteristics of the emitted light, such as a high directivity mode, a high viewing angle mode, etc. with high brightness, while keeping the in-plane luminance distribution always uniform. Can be switched. In particular, in the present embodiment, since the recesses 40 that exhibit different emission characteristics are provided for each of the recess rows 40A and 40B, the characteristic mode of the emitted light can be easily switched by switching the lighting of the LEDs 17A and 17B. It is.

  In the present embodiment, the incident lights LA and LB from the LEDs 17A and 17B are provided adjacent to each other in the Y-axis direction in the light guide plate 16, so that even when one of the LEDs is lit, the light is biased. Therefore, it is possible to prevent the illumination light from entering with a uniform distribution and to be emitted as the outgoing light, and to emit the illumination light with less uneven luminance distribution. Furthermore, the liquid crystal display device 1 having higher luminance and excellent display characteristics can be obtained by disposing more LEDs 17A for obtaining high luminance than the LEDs 17B.

(Electronics)
FIG. 7 is a perspective view showing an example of an electronic apparatus equipped with the liquid crystal display device of the present invention. A cellular phone 1300 shown in FIG. 7 includes the liquid crystal display device of the present invention as its display unit 1301, and includes a plurality of operation buttons 1302, an earpiece 1303, and a mouthpiece 1304.
When using such a mobile phone 1300, when displaying information that other people do not want to see, use highly directional illumination light, and when multiple people see the same display, What is necessary is just to use illumination light with low directivity so that a range may spread. Switching between a wide viewing angle and a narrow viewing angle can be performed very easily by simply selecting lighting of one of the light sources. When a brighter display with a wider field of view is desired, all the light sources may be turned on.

  The electronic device of the present invention is not limited to the above-described mobile phone, but is an image display device such as an electronic book, a personal computer, a digital still camera, a liquid crystal television, a digital video camera, a car navigation device, a video phone, a POS terminal, and a touch panel. It can be suitably used as a means, and in any electronic apparatus, switching between a wide viewing angle and a narrow viewing angle can be performed very easily.

  As described above, the preferred embodiments according to the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to the examples. Various shapes, combinations, and the like of the constituent members shown in the above-described examples are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  For example, in the above-described embodiment, a plurality of LEDs 17A and 17B are provided. However, only one of the LEDs 17A and 17B may be provided. Also in this case, the incident light LA and LB from the LEDs 17A and 17B are provided adjacent to each other in the Y-axis direction in the light guide plate 16, so that even when any one of the LEDs is lit, the light is incident with a biased distribution. Moreover, since it can suppress emitting as emitted light and it becomes possible to emit illumination light with little deviation of luminance distribution, it is preferable.

Moreover, in the said embodiment, although the prism formed in the recessed part 40 was illustrated as a characteristic adjustment part which adjusts an output characteristic, it is not limited to this, For example, as shown in FIG. A dot pattern DP including a plurality of dots provided on the bottom surface 16C may be used as the characteristic adjustment unit. In FIG. 8, a plan view seen from the bottom surface 16C side is shown for easy understanding. In this configuration, the dot pattern DP corresponds to each of the LEDs 17A and 17B, and the dot array DPA having different dot density distributions along the traveling directions (X-axis direction) of the light LA and LB emitted by the LEDs 17A and 17B. , Forming DPB. In each of the dot rows DPA and DPB, the dots are arranged in a density distribution that gradually increases from coarse to dense as the light LA and LB travel. In this configuration, in order to express high luminance and high directivity, the dots in the dot row DPA have a shape having a specular reflection surface, and the dots in the dot row DPB have a shape having a diffuse reflection surface. It is possible to obtain the same operation and effect as the embodiment.
The dots can be formed, for example, by applying an ultraviolet curable resin by a droplet discharge method and then curing it by irradiating with ultraviolet rays. In this case, the contact angle of the dots is preferably in the range of 15 to 75 degrees (for example, 30 degrees), and can be appropriately selected according to the specifications of the set luminance and viewing angle.
In addition, after these dots are formed, a nickel film may be formed by sputtering, and the nickel film may be used as a conductive film for electroforming to form a mold, and the light guide plate may be formed.

  Moreover, although the recessed part and the dot pattern were illustrated as a characteristic adjustment part which adjusts an emission characteristic in the said embodiment, it is not limited to this, You may use another shape. For example, a configuration in which a prism is protruded from the light guide plate 16 instead of a groove-shaped recess provided on the light guide plate 16 may be used.

1 is a perspective view showing a liquid crystal display device according to the present invention. 2 is a cross-sectional view of the liquid crystal display device. FIG. It is a perspective view which shows the structure of the backlight used for a liquid crystal display device equally. It is a top view of a backlight same as the above. 4 is an enlarged cross-sectional view of a recess 40. FIG. It is the graph which showed the luminance distribution of illumination light. It is a perspective view which shows an example of the electronic device of this invention. It is a top view of the backlight of another form.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display device, 15 ... Liquid crystal cell, 16 ... Light guide plate, 16A ... 1st end surface, 16B ... 2nd end surface, 17A ... LED (1st light source), 17B ... LED (2nd light source), DESCRIPTION OF SYMBOLS 18 ... Backlight (illuminating device) 40 ... Concave part (characteristic adjustment part), 40A ... Concave row | line | column (1st characteristic adjustment part), 40B ... Concave row | line | column (2nd characteristic adjustment part), 41A ... Inclined surface (specular reflection surface) ), 41B ... inclined surface (diffuse reflective surface), 42A ... diffuse reflective surface (third diffuse reflective surface), 42B ... diffuse reflective surface (second diffuse reflective surface), 1300 ... mobile phone (electronic device), CONT ... control Device (light source control device), LA, LB ... Light (incident light)

Claims (12)

A light guide plate, a first light source for causing light to enter the first end face of the light guide plate,
A second light source for making light incident on a second end surface facing the first end surface of the light guide plate;
In the first light source and the second light source, incident directions of incident light on the light guide plate are provided in opposite directions,
The light guide plate is provided with a characteristic adjustment unit for adjusting an emission characteristic when the incident light is emitted from the light guide plate for each of the first light source and the second light source. . The lighting device according to claim 1.
The lighting device according to claim 1, wherein at least one of the first light source and the second light source is arranged in such a manner that incident directions of the incident light adjacent to each other in the light guide plate are opposite to each other. The lighting device according to claim 1 or 2,
The lighting device according to claim 1, wherein the characteristic adjusting units are arranged in a distribution according to an incident direction of the incident light. In the illuminating device as described in any one of Claim 1 to 3,
The illumination device according to claim 1, wherein the characteristic adjusting unit forms a prism extending in a direction substantially orthogonal to an incident direction of the incident light. In the illuminating device as described in any one of Claim 1 to 3,
The illumination device according to claim 1, wherein the characteristic adjustment unit is formed in a pattern of a plurality of dots. In the illuminating device as described in any one of Claim 1 to 5,
The illumination device according to claim 1, wherein the characteristic adjustment unit is provided with different emission characteristics for each of the first light source and the second light source. The lighting device according to claim 6.
The characteristic adjustment unit is provided according to the first light source, and is provided according to the second light source and the first characteristic adjustment unit that specularly reflects incident light from the first light source. A lighting device comprising: a second characteristic adjusting unit that diffusely reflects incident light from a light source. The lighting device according to claim 7.
The lighting device according to claim 1, wherein the first characteristic adjustment unit includes a specular reflection surface provided facing the first light source and a diffuse reflection surface provided facing the second light source. The lighting device according to claim 7 or 8,
The second characteristic adjusting unit includes a second diffuse reflection surface provided facing the second light source and a third diffuse reflection surface provided facing the first light source. Lighting device. In the illuminating device as described in any one of Claim 1 to 9,
An illumination apparatus comprising: a light source control device that selectively turns on at least one of the first light source and the second light source. The lighting device according to any one of claims 1 to 10,
A liquid crystal display device comprising: a liquid crystal cell into which illumination light emitted from the illumination device is incident.   An electronic apparatus comprising the liquid crystal display device according to claim 11.

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