JP2005327608A - Lighting system, electro-optical device and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting system capable of realizing color reproduction of a light color region and high luminance; and to provide an electro-optical device and an electronic apparatus. <P>SOLUTION: This lighting system is provided with a first light source, one or more second light sources and a planar light guide plate causing light emitted from the first light source and the second light source(s) to be emitted in a planar form. The lighting system is characterized by that the light emitted from the second light source(s) has at least one peak wavelength different from that of a spectroscopic characteristic of the light emitted from the first light source. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an illumination device, an electro-optical device, and an electronic apparatus.

Since the liquid crystal display is a non-light emitting type, a method of obtaining a light source includes a reflective type using ambient light, a transmissive type using a specific light source, and a transflective type having both characteristics. Widely known. Among them, liquid crystal displays called a transmissive type and a semi-transmissive type mainly emit light by using a backlight. As a light source used for the backlight, light emitting sources such as a cold cathode tube and an LED (Light Emitting Diode) are widely used, and various backlights combined with a light guide plate or the like have been proposed. In Patent Document 1, light from a point light source such as an LED is condensed, converted into a line light source by a first light guide plate, and the converted light source is irradiated onto a liquid crystal display surface by a second light guide plate. A backlight that prevents uneven brightness due to a point light source is disclosed (for example, Patent Document 1).
JP 2001-357713 A

  However, in the backlight disclosed in the above-mentioned patent document, it is possible to avoid the occurrence of luminance unevenness due to the point light source. However, since the spectral characteristics of the color filter provided in the liquid crystal display are not considered at all, sufficient color development is possible. It was difficult to get. That is, the color finally emitted from the liquid crystal display screen is largely related to the matching between the spectral characteristics of the backlight and the spectral characteristics of the color filter. However, in the backlight disclosed in the above-mentioned patent document, there is a problem in that the brightness emitted from the liquid crystal display screen is lowered because no consideration is given to the compatibility with such a color filter. Furthermore, in the backlight disclosed in the above-mentioned patent document, color reproduction is attempted with three primary colors of R (red), G (green), and B (blue). Therefore, although a liquid crystal display device using a multi-color filter (three colors of R (red), G (green), and B (blue)) that meets the demand for a wider color gamut has been proposed recently. Therefore, there is a problem that sufficient color development cannot be obtained and color reproduction in a wide color gamut and high brightness cannot be realized.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an illumination device, an electro-optical device, and an electronic apparatus that can realize color reproduction and high brightness in a wide color gamut. .

  In order to solve the above-described problems, the present invention includes a first light source, a second light source, and a planar light guide plate that emits surface light from light emitted from the first light source and the second light source. The light emitted from the two light sources has a peak wavelength different from at least one peak wavelength of the spectral characteristics of the light emitted from the first light source.

  According to such a configuration, since the second light source having at least one peak wavelength different from the peak wavelength of the spectral characteristic of the first light source is provided, the spectral characteristic of the light emitted from the first light source is A peak wavelength of a color that does not appear can be obtained. As a result, the color reproduction gamut increases, and it is possible to achieve a wide color gamut and high luminance for color reproduction of the lighting device.

The illuminating device of the present invention is characterized in that the second light source is formed of a light emitting diode.
According to such a configuration, there are various light emitting diodes (hereinafter referred to as LEDs (Light Emitting Diodes)) that emit R (red), G (green), B (blue) and other colors. Each of these LEDs has a certain peak wavelength. Therefore, by selecting the second light source having a peak wavelength different from the peak wavelength of the spectral characteristic of the light emitted from the first light source, it is possible to emit a color that cannot be expressed by the first light source. Become. As a result, color reproduction can be performed with at least four primary colors as compared with the conventional color reproduction with the three primary colors, thereby increasing the color reproduction range and widening the color reproduction range and increasing the brightness of the lighting device. Can be achieved.

Alternatively, it is also preferable that the first light source emits a line and includes a rod-shaped light guide plate having an end surface on which light emitted from the second light source is incident.
For example, when the LED described above is employed as the second light source, the light emitted from the LED is point emission. When the point emitted light emitted from the second light source is directly incident on the planar light guide plate, the point emitted light is not reflected or diffused uniformly within the planar light guide plate. It only emitted light. Thus, by providing the rod-shaped light guide plate in the vicinity of the second light source, it becomes possible to convert the point light emission emitted from the LED into the line light emission by the rod-shaped light guide plate. Therefore, it is possible to match (match) the light emitted from the main light source with the light emitted from the second light source and converted to the line light emission by the rod-shaped light guide plate, and uniformly reflected inside the planar light guide plate. It is possible to diffuse and prevent luminance unevenness.
In this embodiment, the end surface of the rod-shaped light guide plate is a surface including the short direction of the rod-shaped light guide plate, and the end surface is a surface including the longitudinal direction of the rod-shaped light guide plate.

Alternatively, it is also preferable that the first light source and the rod-shaped light guide plate are disposed on the same end surface of the planar light guide plate.
According to such a configuration, the light emitted from the first light source and the light emitted from the LED and converted from the point light emission to the line light emission by the rod-shaped light guide plate are arranged in parallel to the first light source and the rod-shaped light guide plate. Can be incident on the planar light guide plate. For this reason, the light incident on the planar light guide plate is repeatedly reflected and diffused, so that the line emission can be converted into the surface emission. As a result, each of the light emitted from the first light source and the second light source can be uniformly surface-emitted, and luminance unevenness can be prevented.

Or it is also preferable that the side surface of the rod-shaped light guide plate is formed with a plurality of grooves for emitting light guiding the inside of the rod-shaped light guide plate from the other side surface.
According to such a configuration, when the second light source is provided in the vicinity of the rod-shaped light guide plate, when light emitted from the second light source enters the rod-shaped light guide plate, the total reflection repeats straight, The reflection angle is changed by the light traveling straight colliding with the groove. Thereby, the light whose incident angle is reduced by colliding with the groove is emitted to the outside of the rod-shaped light guide plate. As a result, the point light emitted from the second light source can be converted into line light emission and uniformly emitted onto the planar light guide plate.

Or it is also preferable that the diffusion sheet is arrange | positioned between the said rod-shaped light-guide plate and a 1st light source, and the said planar light-guide plate.
According to such a structure, the light inject | emitted from a 1st light source and a rod-shaped light-guide plate injects into a diffusion sheet, Therefore The said light can be diffused inside a diffusion sheet, and can enter into a planar light-guide plate. Thereby, the light emitted from the first light source and the second light source can be uniformly incident on the planar light guide plate, and uneven brightness can be prevented.

Further, the present invention is characterized in that the first light source is composed of a plurality of white light emitting diodes, and the second light source is disposed between the first light sources.
Usually, the spectral characteristic of light emitted from a white LED has blue and yellow peak wavelengths, and red and green wavelengths are weaker than blue and yellow wavelengths. Therefore, for example, by arranging a second light source having red and green wavelength characteristics not included in the first light source between the first light sources, a red peak wavelength that was lacking in the spectral characteristics of the first light source is added. be able to. Moreover, since the 2nd light source is arrange | positioned between 1st light sources, the light inject | emitted from a 1st light source and a 2nd light source can be mixed uniformly. As a result, the first light source and the second light source can emit R (red), G (green), and B (blue) colors in a well-balanced manner, and luminance unevenness can be prevented.

Alternatively, it is also preferable that the first light source is configured as a set of red, green, and blue light emitting diodes, and the second light source is disposed between the set of light emitting diodes.
The spectral characteristics of light emitted from the red, green, and blue light emitting diodes include red, green, and blue wavelengths in a balanced manner. Therefore, a fourth color is added in addition to the three primary colors of red, blue and green by arranging a second light source having a wavelength characteristic of cyan, for example, which is not included in the first light source, between the first light sources. can do. Moreover, since the 2nd light source is arrange | positioned between 1st light sources, the light inject | emitted from a 1st light source and a 2nd light source can be mixed uniformly. Thereby, compared with the conventional color reproduction with three primary colors, color reproduction can be performed with at least four primary colors. Therefore, the color reproduction range is increased, and the wide color gamut and high brightness of the color reproduction of the lighting device are achieved. It becomes possible.

Or it is also preferable that the diffusion sheet is arrange | positioned between the said 1st light source and the said 2nd light source, and the said planar light-guide plate.
According to such a structure, the light inject | emitted from a 1st light source and a 2nd light source is diffused in the inside of a diffusion sheet when it injects into a diffusion sheet, and can be made to inject into a planar light-guide plate. Thereby, the light emitted from the first light source and the second light source can be uniformly incident on the planar light guide plate, and uneven brightness can be prevented.

According to another aspect of the invention, there is provided an electro-optical device that includes the illumination device and displays a color image by irradiating a color filter with light emitted from the first light source and the second light source. A plurality of peak wavelengths of spectral characteristics of light emitted from the second light source and a plurality of peak wavelengths of spectral characteristics of the color filter are matched to reproduce a predetermined color.
The color reproduction range of the electro-optical device is determined by matching the spectral characteristics of the illumination device and the spectral characteristics of the color filter. Therefore, according to this, the plurality of peak wavelengths of the spectral characteristics of the light emitted from the first light source and the second light source are matched with the plurality of peak wavelengths of the spectral characteristics of the color filter. The bandwidth of the spectral characteristics of light emitted corresponding to each pixel can be narrowed. As a result, the color reproducibility and the luminance of the electro-optical device can be improved due to the narrow band spectral characteristics.

In the electro-optical device according to the aspect of the invention, the color filter has at least four colors of red, green, blue, and other colors, and the peak wavelength of the spectral characteristic of the first light source is set to the spectral wavelength of the color filter. It is characterized by matching with the red, green and blue peak wavelengths of the characteristics, and matching the peak wavelength of the spectral characteristics of the second light source with the peak wavelengths other than the red, green and blue spectral characteristics of the color filter.
According to such a configuration, for example, by arranging a second light source having a wavelength characteristic of cyan that is not included in the first light source between the first light sources, in addition to the three primary colors of red, blue, and green, Furthermore, a fourth color can be added. Thereby, since the illumination device having the same peak wavelength as the spectral characteristic of the color filter is used, the wavelengths of the illumination device and the color filter can be matched, and at least 4 colors compared with the conventional color reproduction of the three primary colors. Color reproduction can be performed with more than primary colors. As a result, the color gamut of the electro-optical device is increased, and it is possible to achieve a wide color gamut and high luminance for color reproduction of the illumination device.

According to another aspect of the invention, there is provided an electronic apparatus comprising the electro-optical device.
According to the present invention, by providing the electro-optical device, it is possible to realize an electronic apparatus capable of wide color gamut and high luminance.

  Embodiments of the present invention will be described below with reference to the drawings. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size.

[First Embodiment]
Fig.1 (a) is a schematic block diagram of the backlight 22 (illuminating device) in this Embodiment, FIG.1 (b) is sectional drawing along the AA of (a).
As shown in FIG. 1A, a backlight 22 is emitted from a cold cathode tube 10 (first light source) used as a main light source, an LED 14 (second light source) used as an auxiliary light source, and the LED. The rod-shaped light guide plate 16 for linearly emitting light to be emitted and the diffusion sheet 18 for diffusing the light emitted linearly from the rod-shaped light guide plate 16 are provided. Further, the backlight 22 includes a planar light guide plate 12 that emits light from the cold cathode tube 10 and the light emitted from the rod-shaped light guide plate 16.

  The cold cathode tube 10 used as the main light source in the present embodiment has a rod-like columnar shape, and the diameter of this circle is, for example, about 1.8 mmφ. In the spectral characteristics of light emitted from the cold cathode tube 10, peak wavelengths generally appear in the wavelength bands of R (red), G (green), and B (blue). In addition, electrodes formed of nickel, tantalum, or the like are provided at both ends inside the cold cathode tube 10, respectively. In the cold cathode tube 10, electrons emitted from the electrodes excite mercury vapor in the cold cathode tube 10 to emit ultraviolet rays, collide with phosphors on the wall of the cold cathode tube 10, and exit the cold cathode tube 10. Emits light. In the present embodiment, the cold cathode tube 10 is used as the main light source, but instead of the cold cathode tube 10, a hot cathode tube, an organic EL (Electroluminescence), an Xe discharge tube (Xe discharge lamp), an electrodeless It is also preferable to use a lamp or the like.

  The rod-shaped light guide plate 16 has a rod-like prismatic shape and is disposed along the lower portion of the cold cathode tube 10. And the light emission part of LED14 mentioned later is arrange | positioned facing each of the both end surfaces 16a side of this rod-shaped light-guide plate 16 side. The rod-shaped light guide plate 16 has a function of converting the point emission light emitted from the LED 14 into line light emission and emitting it to the planar light guide plate 12. In addition, a plurality of grooves (not shown) are formed on the side surface 16b of the rod-shaped light guide plate 16 opposite to the side surface on which the planar light guide plate 12 described later is disposed. The plurality of grooves are formed by providing a plurality of fine inclined surfaces on the side surface 16 b of the rod-shaped light guide plate 16. Moreover, the groove | channel formed in the rod-shaped light-guide plate 16 is coarse when formed in the area | region close | similar to LED14, and forms densely when forming in the area | region far from LED14. The light emitted from the LED 14 can be reflected by the groove, and the light emitted from the LED 14 can be uniformly incident on the planar light guide plate 12. Instead of forming the plurality of grooves in the rod-shaped light guide plate 16, a plurality of reflective dots are formed, and the incident angle of light emitted from the LED 14 is changed to emit uniform light to the planar light guide plate 12. It is also preferable to do.

  The LED 14 is used as an auxiliary light source in the present embodiment, and is disposed on both ends of the rod-shaped light guide plate 16 with the light emitting portions of the respective LEDs 14 facing each other. The LED 14 has a peak wavelength different from the peak wavelength of the spectral characteristics of the cold cathode tube 10. For example, as described above, the spectral characteristics of the cold cathode tube 10 have the peak wavelengths of the three primary colors of R (red), G (green), and B (blue). Use those with different peak wavelengths, for example cyan.

  The planar light guide plate 12 is disposed adjacent to the cold cathode tube 10 and the rod-shaped light guide plate 16 disposed below the cold cathode tube 10 with a certain distance therebetween. The planar light guide plate 12 is made of, for example, a transparent acrylic resin, and light emitted from the cold cathode tube 10 and the LED 14 is incident from the side surface of the planar light guide plate 12, and the acrylic inside the planar light guide plate 12. The plate repeats total reflection and goes straight. A plurality of grooves are formed on the lower main surface of the planar light guide plate 12 in the same manner as the rod-shaped light guide plate 16. The plurality of grooves are formed by providing a plurality of fine inclined surfaces on the lower main surface of the planar light guide plate 12. Further, the groove formed in the planar light guide plate 12 is rough when formed in a region near the incident end face of the cold cathode tube 10 and the LED 14 in order to emit light uniformly from the planar light guide plate 12. When it is formed in a far region, it is formed densely. By this groove, the incident angle of light emitted from the cold cathode fluorescent lamp 10 and the LED 14 can be changed, and light can be emitted uniformly from the planar light guide plate 12. Instead of forming the plurality of grooves in the rod-shaped light guide plate 16, a plurality of reflective dots are formed, and the incident angle of the light emitted from the LED 14 is changed, so that uniform light is applied to the planar light guide plate 12. It is also preferable to inject. As described above, the light emitted linearly from the cold cathode fluorescent lamp 10 and from the rod-shaped light guide plate 16 can be surface-emitted by the planar light guide plate 12.

  The diffusion sheet 18 is formed so that the long side of the plate-shaped diffusion sheet 18 is substantially equal to the longitudinal side of the cold cathode tube 10 and the rod-shaped light guide plate 16, and the short side is the cold cathode tube 10 and the rod-shaped guide. It is formed so as to be substantially equal to the height of the optical plate 16 in the thickness direction. The diffusion sheet 18 has a function of scattering and diffusing light converted from point light emission to line light emission by the rod-shaped light guide plate 16 in the thickness direction of the planar light guide plate 12 and uniformly emitting light to the planar light guide plate 12. Have The diffusion sheet 18 is also preferably disposed so as to contact at least one of the cold cathode tube 10 and the rod-shaped light guide plate 16.

  The reflector 20 is formed so as to cover the cold cathode tube 10, the rod-shaped light guide plate 16 and the diffusion sheet 18. That is, the cross section of the reflector 20 is formed in a U-shape, and the cold cathode tube 10, the rod-shaped light guide plate 16, and the diffusion sheet 18 are disposed inside the reflector 20. The bar-shaped light guide plate 16 and the diffusion sheet 18 are attached and fixed to the lower part of the U-shaped inner side of the reflector 20. With such a structure, the reflector 20 reflects the light emitted from the cold cathode tube 10 as a main light source and the rod-shaped light guide plate 16 as an auxiliary light source inside the reflector 20 and guides it in the direction of the planar light guide plate 12. it can.

Subsequently, the optical path of light emitted from the cold cathode tube 10 and the LED 14 and the spectral characteristics when this light is emitted from the planar light guide plate 12 will be described in detail below.
First, light is emitted from the cold cathode fluorescent lamp 10 which is a main light source and the LED 14 which is an auxiliary light source. The light emitted from the LED 14 enters the rod-shaped light guide plate 16. In the rod-shaped light guide plate 16, the light emitted from the LED 14 repeats total reflection and goes straight (multiple reflection). On the other hand, a plurality of grooves are formed on the side surface opposite to the side surface on which the planar light guide plate 12 is disposed, and light incident on the rod-shaped light guide plate 16 collides with the grooves, thereby causing total reflection. The light that has been repeatedly traveling straight is changed in incident angle and emitted from the rod-shaped light guide plate 16. In this manner, the light emitted from the LED 14 passes through the rod-shaped light guide plate 16, whereby the point light emitted from the LED 14 is converted into linear light emission.

Then, the light emitted from the LED 14 and converted into the line emission by passing through the rod-shaped light guide plate 16 is uniformly mixed with the line emission light emitted from the cold cathode tube 10 and enters the diffusion sheet 18. The light incident on the diffusion sheet 18 is diffused and uniformly incident on the entire incident end face of the planar light guide plate 12. Similar to the rod-shaped light guide plate 16 described above, the light incident on the planar light guide plate 12 repeats total reflection and travels straight ahead. On the other hand, a plurality of grooves are formed on the lower main surface of the planar light guide plate 12, and the incident angle is changed by colliding with the grooves when the light traveling straight with repeated total reflections is changed, and the observer side Is injected into. In this way, the light emitted from the cold cathode tube 10 and the LED 14 passes through the inside of the planar light guide plate 12, thereby converting the line-emitting light into the surface emission.
It is also preferable to dispose a diffusion sheet, a lens sheet, a polarization separation sheet, an electromagnetic shielding sheet, or a combination thereof on the planar light guide plate 12. It is also preferable to arrange a reflective sheet below the planar light guide plate 12.

  FIG. 2 shows the spectral characteristics of light emitted from the planar light guide plate 12. As shown in FIG. 2, four peak wavelengths appear in the spectral characteristics of the light emitted from the planar light guide plate 12. Specifically, the first peak wavelength appears in the vicinity of 440 nm, and this peak wavelength indicates the wavelength band of B (blue). The second peak wavelength appears in the vicinity of 490 nm, and this peak wavelength indicates the C (cyan) wavelength band. The third peak wavelength appears in the vicinity of 540 nm, and this peak wavelength is the wavelength band of G (green). The fourth peak wavelength appears in the vicinity of 640 nm, and this peak wavelength indicates the wavelength band of R (red). Here, the peak wavelengths of R (red), G (green), and B (blue) are spectral characteristics of light emitted from the cold cathode tube 10, and the peak wavelength of C (cyan) is emitted from the LED 14. Is the spectral characteristic of the light.

  Thus, according to the present embodiment, the peak different from the peak wavelength (R (red), G (green), (blue)) of the spectral characteristics of the light emitted from the cold cathode tube 10 as the main light source. By arranging the LED 14 that is the auxiliary light source 10 having the wavelength (C (cyan)), a peak wavelength of a color that does not appear in the spectral characteristics of the light emitted from the cold cathode tube 10 can be obtained. As a result, compared with the conventional color reproduction with the three primary colors, the color reproduction with the four primary colors can be performed, so that the color reproduction gamut increases, and the backlight 20 has a wide color gamut and high brightness. It becomes possible to plan.

[Second Embodiment]
In the first embodiment, the cold cathode tube 10 is disposed as the main light source. Then, an auxiliary LED 34 is disposed as an auxiliary light source, which is converted from point light emission to line light emission using the rod-shaped light guide plate 16 and emitted to the planar light guide plate 12. In contrast, in the present embodiment, a plurality of white LEDs 30 are arranged as a main light source, and an auxiliary LED 34 having a peak wavelength different from that of the main light source is arranged as an auxiliary light source between the plurality of white LEDs arranged. Is different. Hereinafter, the present embodiment will be described in detail with reference to the drawings. Note that the same configuration as the first embodiment will be omitted or simplified.

  In the backlight 40 according to the present embodiment, white LEDs 30 that are main light sources and LEDs 34 that are auxiliary light sources are alternately arranged, and a diffusion sheet that diffuses light emitted from the alternately arranged main light sources and auxiliary light sources. 36 and a planar light guide plate 32 that emits surface light of the light diffused by the diffusion sheet 36.

  As shown in FIG. 3, two white LEDs 30 are arranged adjacent to each other as a light source, and a plurality of white LEDs 30 that are a pair of the two white LEDs 30 are arranged with an auxiliary LED 34 serving as an auxiliary light source interposed therebetween. . That is, in the present embodiment, a pair of white LEDs 30 as a main light source and auxiliary LEDs 34 as an auxiliary light source are alternately arranged in a line and the light emitting surface is arranged on the incident end face side of the planar light guide plate 12. A diffusion sheet 36 is disposed on the light emitting surface side of the white LEDs 30 and the auxiliary LEDs 34 arranged in a row, and the light emitted from the white LEDs 30 and the auxiliary LEDs 34 is scattered and diffused uniformly by the diffusion sheet 18. Injected into the planar light guide plate 32. The planar light guide plate 32 converts the line emission diffused by the diffusion sheet 36 into the plane emission, and emits the light converted into the plane emission toward the viewer. Since other configurations are the same as those of the first embodiment described above, description thereof is omitted.

  Hereinafter, when only the white LED 30 is used as the light source of the backlight 40, only when the auxiliary LED 34 is used, or when the white LED 30 and the auxiliary LED 34 in the present embodiment are used in combination, the spectral characteristics, etc. Will be described with reference to FIGS.

  First, the case where white LED30 is used as a light source of the backlight 40 is demonstrated. The white LED 30 used as the main light source described above uses an LED that emits blue or ultraviolet light as an excitation light source of the light emitter, and obtains white colored light by combining the LED emitting blue light and the color of the light emitter. ing. FIG. 4A is a diagram illustrating the spectral characteristics of the white LED 30 when only the white LED 30 is used as the light source of the backlight 40. As shown in FIG. 4A, first, a peak wavelength appears in the vicinity of 470 nm, and this peak wavelength indicates a wavelength band of B (blue). Next, a peak wavelength appears in the vicinity of 570 nm, indicating the wavelength band of Y (yellow). On the other hand, among the spectral characteristics of light emitted from the white LED 30, there is a characteristic that the wavelength of R (red) which is the three primary colors is weaker than the wavelengths of G (green) and B (blue). . As described above, when the white LED 30 is used as the main light source of the backlight 40, the wavelength characteristics of B (blue) which are the three primary colors are obtained, but the wavelength characteristics of R (red) and G (green) are obtained. Is difficult to obtain, and it can be seen that the color reproducibility of R (red) is particularly poor.

  Next, the case where the auxiliary LED 34 is used as the light source of the backlight 40 will be described. FIG. 4B is a diagram showing the spectral characteristics of the auxiliary LED 34 when only the auxiliary LED 34 is used as the light source of the backlight 40. In the present embodiment, the auxiliary LED 34 of the auxiliary light source uses, for example, an LED having a peak wavelength of R (red). As shown in FIG. 4B, the peak wavelength appears in the spectral characteristics of the auxiliary LED 34 in the vicinity of 630 nm. Thus, it can be seen that when the auxiliary LED 34 is used as an auxiliary light source, the wavelength characteristics of R (red), which is the three primary colors, can be obtained.

  Next, a case where the white LED 30 and the auxiliary LED 34 are used in combination as a light source of the backlight 40 will be described. In the present embodiment, the backlight 40 in which the white LEDs 30 and the auxiliary LEDs 34 having the spectral characteristics as shown in FIGS. 4A and 4B are alternately arranged is used. FIG. 4C is a diagram showing the spectral characteristics of both light sources when both the white LED 30 as the main light source and the auxiliary LED 34 as the auxiliary light source are used as light sources. As shown in FIG. 4C, peak wavelengths appear in the vicinity of 470 nm, 570 nm, and 630 nm, and these wavelengths indicate the wavelength bands of B (blue), G (green), and R (red) in this order. Yes.

  As described above, the peak wavelength of B (blue) appears in the spectral characteristics of the light emitted from the white LED, and the wavelengths of R (red) and G (green) are compared with the wavelength of B (blue). There is a characteristic that the wavelength of R (red) is weak. Therefore, according to the present embodiment, by arranging the auxiliary LED 34 having the wavelength characteristic of R (red) not in the white LED 30 between the white LEDs 30, the R (red) of the white LED 30 lacking in the spectral characteristics is arranged. A peak wavelength can be added. In addition, since the auxiliary LED 34 is disposed between the white LEDs 30, it is easy to mix light emitted from the white LED 30 and the auxiliary LED 34 uniformly. As a result, the white LED 30 and the auxiliary LED 34 can emit light of R (red), G (green), and B (blue), which are the three primary colors, in a balanced manner, and can prevent uneven brightness. .

As the main light source of the backlight, in addition to the white LED 30, a near-ultraviolet LED, a separate package RGB color LED in which packages are separately provided for each RGB color, a single package RGB color LED in which each RGB color is packaged, and the like It is also preferred to use
Near-UV LEDs emit white light by combining LEDs that emit near-ultraviolet light and phosphors that convert near-ultraviolet light into RGB colors. In this near-ultraviolet LED, R (red), G (green), and B (blue) emit light in a balanced manner as compared with the spectral characteristics of the white LED 30 used as the main light source in the second embodiment. Therefore, in this case, it is also preferable to use an LED having a characteristic of a weak wavelength portion, for example, an LED having a cyan peak wavelength, as the auxiliary light source.
In addition, the separate package RGB color LED and the one package RGB color LED use RGB emission colors as they are without using a phosphor, such as a white LED and a near ultraviolet LED, so that R (red) and G (green) are used. And B (blue) emit light well. Therefore, according to the separate package RGB color LED and the single package RGB color LED, high color reproducibility can be realized. In this case, it is also preferable to use an auxiliary LED having a peak wavelength different from the peak wavelength of the spectral characteristics of the RGB color LED, for example, an LED having a cyan peak wavelength.
In this way, by arranging, for example, an LED having a wavelength characteristic of cyan, which is not included in the RGB LED, between the near-ultraviolet LED or the RGB color LED, R (blue), G (green), and B (blue) 3 In addition to the primary color, a fourth cyan can be added. As a result, the color reproduction can be performed with at least four primary colors as compared with the conventional color reproduction with the three primary colors, so that the color reproduction gamut increases and the backlight color reproduction has a wide color gamut and high brightness. It becomes possible.

[Third Embodiment]
In the first and second embodiments described above, a light source is disposed on the side surface of the planar light guide plate, light emitted from the light source is incident from the side surface of the planar light guide plate, and reflection and diffusion inside the light guide plate. A method of making a surface light source by multiply reflecting light on the surface, that is, a side light method has been adopted. On the other hand, in the present embodiment, a light source is arranged inside a casing composed of a reflecting plate and a diffusing plate, and light emitted from the light source is reflected and diffused inside the casing to form a surface light source. The difference is that the method, that is, the direct type is adopted. Hereinafter, the present embodiment will be described. Note that the same configurations as those in the first and second embodiments are omitted or simplified in the description.

  Fig.5 (a) is a figure which shows schematic structure of the backlight in this Embodiment, FIG.5 (b) is sectional drawing along CC line of (a). As shown in FIGS. 5A and 5B, the backlight 80 includes a casing 70 composed of a reflecting plate 72 and a diffusion sheet 74, and a cold light source that is a main light source disposed inside the casing 70. A cathode tube 76 and an LED 78 as an auxiliary light source are provided.

The casing 70 has a trapezoidal cross section, and the upper side surface of the casing 70 that is disposed opposite and parallel to the casing 70 is configured by a diffusion sheet 74, and the other surface is configured by a reflecting plate 72.
A plurality of cold cathode fluorescent lamps 76 as main light sources are arranged in parallel with each other at a predetermined interval in the housing 70. Further, the LED 78 as an auxiliary light source is arranged between each of the plurality of cold cathode tubes 76 arranged at a predetermined interval. Specifically, a plurality of LEDs 78 are arranged between the cold cathode tubes 76 so as to be substantially parallel to the rod-shaped cold cathode tubes 76 and spaced apart in a row. As the auxiliary light source, the LED 78 has an LED 78 having a peak wavelength different from the peak wavelength of the spectral characteristics of the light emitted from the cold cathode tube 76 as in the above-described embodiment, for example, one having a peak wavelength of cyan. doing.

Thus, by arranging the LED 78 as an auxiliary light source between the cold cathode tubes 76, a peak wavelength different from the peak wavelength of the spectral characteristics of the cold cathode tubes 76 can be obtained. Therefore, compared with the conventional color reproduction with three primary colors, color reproduction can be performed with at least four primary colors, the color reproduction gamut can be increased, and the wide color gamut and high brightness of the color reproduction of the backlight 80 can be achieved. Can be planned.
[Electro-optical device]

Hereinafter, a schematic configuration of the liquid crystal display device 68 in the present embodiment will be briefly described with reference to FIG.
FIG. 6 is an exploded perspective view of the liquid crystal display device 68 manufactured using the above-described backlight. The liquid crystal display device 68 shown in FIG. 6 is an active matrix type using a thin film diode (hereinafter referred to as TFD) as a switching element.

As shown in FIG. 6, in the liquid crystal display device 68, the array substrate 54 and the counter substrate 64 arranged to face the substrate are bonded together with a sealing material, and the liquid crystal (non-display) is formed in a region partitioned by the sealing material. Is enclosed and held.
On the counter substrate 64 side (inner side) of the array substrate 54, a plurality of scanning lines and a plurality of data lines are formed so as to intersect in a matrix, and switching elements are respectively provided at the intersections of the scanning lines and the data lines. A TFD is formed, and this TFD is connected to the pixel electrode. Thus, the pixel 56 is composed of the TFD and the pixel electrode, and one pixel 56 is composed of three sub-pixels.

A color filter 62 is formed on the array substrate 54 side (inside) of the counter substrate 64. The color filter is composed of three colors of R (red), G (green), and B (blue) corresponding to each sub-pixel described above. A protective film is formed on the color filter, and a transparent common electrode 60 (ITO: Indium Tin Oxide) is formed on the protective film.
A polarizing plate 52 is disposed outside the array substrate 54, and a polarizing plate 66 is disposed outside the counter substrate 64 so as to be orthogonal to the polarizing plate 52. The backlight 50 described in the above embodiment is disposed below the polarizing plate 52 disposed outside the array substrate 54.

  The color reproduction range of the liquid crystal display device 68 is determined by matching (matching) the spectral characteristics of the backlight 50 and the spectral characteristics of the color filter 62. Therefore, since the liquid crystal display device 68 in the present embodiment is equipped with the backlight including the auxiliary light source as described above, a plurality of peak wavelengths of the spectral characteristics of the light emitted from the main light source and the auxiliary light source, A plurality of peak wavelengths of the spectral characteristics of the color filter can be matched (matched), and the bandwidth of the spectral characteristics of light emitted corresponding to each pixel 56 during light emission can be narrowed. As a result, it is possible to improve the color reproducibility and increase the brightness of the liquid crystal display device 68 due to the narrow band spectral characteristics.

  In the first embodiment, a fourth color different from the three primary colors is obtained by using an auxiliary light source having a peak wavelength different from that of the main light source in the backlight. For example, cyan is reproduced, and the color reproduction of the wide color of the liquid crystal display device 68 is realized. Therefore, in order to correspond to the fourth color emitted from the backlight, the pixel 56 composed of three subpixels formed on the array substrate 54 of the liquid crystal display device 68 is composed of four subpixels. It is also preferable. Further, when the one pixel 56 is composed of four sub-pixels, it is also preferable to form a colored portion corresponding to the fourth color for the color filter 62. For example, it is also preferable to form the color filter 62 from four colors of R (red), G (green), B (blue), and C (cyan) corresponding to the four sub-pixels described above.

According to such a configuration, by arranging an auxiliary light source having a cyan wavelength characteristic not included in the main light source between the main light sources, three primary colors of R (red), G (green), and B (blue) are arranged. In addition, a fourth C (cyan) color can be added. Accordingly, since the backlight 50 having the same peak wavelength as the spectral characteristic of the color filter 62 is used, the wavelengths of the backlight 50 and the color filter 62 can be matched, and color reproduction with the conventional three primary colors can be achieved. In comparison, color reproduction can be performed with at least four primary colors. As a result, the color gamut of the liquid crystal display device 68 is increased, and the wide color gamut and high brightness of the color reproduction of the backlight 50 can be achieved.
[Electronics]
Next, an example of an electronic device including the above-described liquid crystal display device 68 will be described with reference to FIG. FIG. 7 is a perspective view of the mobile phone. The backlight described above is arranged inside the casing of the mobile phone 1000.

  Note that the above-described liquid crystal display device 68 can be applied to various electronic devices other than the mobile phone. For example, LCD projectors, multimedia-compatible personal computers (PCs) and engineering workstations (EWS), pagers, word processors, TVs, viewfinder type or monitor direct view type video tape recorders, electronic notebooks, electronic desk calculators, car navigation systems The present invention can be applied to electronic devices such as a device, a POS terminal, and a device provided with a touch panel.

  It should be noted that the technical scope of the present invention is not limited to the above-described embodiment, and includes those in which various modifications are made to the above-described embodiment without departing from the spirit of the present invention.

It is a schematic block diagram which shows the backlight of 1st Embodiment. It is a figure which shows the spectral characteristic of a backlight similarly. It is a schematic block diagram which shows the backlight of 2nd Embodiment. It is a figure which shows the spectral characteristic of a backlight similarly. It is a schematic block diagram which shows the backlight of 2nd Embodiment. It is a disassembled perspective view which shows the liquid crystal display device of this invention. It is a perspective view which shows an example of the electronic device of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Cold cathode tube (1st light source) 12, 32 ... Planar light guide plate 14, 34 ... Auxiliary LED (2nd light source), 16 ... Rod-shaped light guide plate 18, 36 ... Diffusion sheet 20, 38 ... Reflector, 22, 40, ... Backlight (illumination device), 30 ... White LED (first light source), 68 ... Liquid crystal display device (electro-optical device)

Claims (12)

A first light source, a second light source, and a planar light guide plate for emitting light emitted from the first light source and the second light source,
The illumination device, wherein the light emitted from the second light source has a peak wavelength different from at least one peak wavelength of spectral characteristics of the light emitted from the first light source.   The lighting device according to claim 1, wherein the second light source includes a light emitting diode.   The lighting device according to claim 2, wherein the first light source emits light and includes a rod-shaped light guide plate having an end surface on which light emitted from the second light source is incident.   4. The lighting device according to claim 1, wherein the first light source and the rod-shaped light guide plate are arranged on the same end surface of the planar light guide plate. 5.   5. The groove according to claim 1, wherein a plurality of grooves are formed on a side surface of the rod-shaped light guide plate to emit light that guides the light inside the rod-shaped light guide plate from another side surface. The lighting device described.   The illuminating device according to any one of claims 1 to 5, wherein a diffusion sheet is disposed between the rod-shaped light guide plate and the planar light guide plate.   The lighting device according to claim 1, wherein the first light source includes a plurality of white light emitting diodes, and the second light source is disposed between the first light sources.   The first light source is configured as a set of red, green, and blue light emitting diodes, and the second light source is disposed between the set of light emitting diodes. Lighting equipment.   The illumination device according to claim 1, wherein a diffusion sheet is disposed between the first light source and the second light source and the planar light guide plate. An electro-optical device that includes the illumination device according to claim 1 and that irradiates a color filter with light emitted from the first light source and the second light source, and displays a color image.
A plurality of peak wavelengths of spectral characteristics of light emitted from the first light source and the second light source and a plurality of peak wavelengths of spectral characteristics of the color filter are respectively matched to reproduce a predetermined color. An electro-optical device.   The color filter has at least four colors of red, green, blue and other colors, and the peak wavelength of the spectral characteristic of the first light source is set to the red, green and blue peaks of the spectral characteristic of the color filter. 11. The electro-optical device according to claim 10, wherein the peak wavelength of the spectral characteristic of the second light source is matched with a peak wavelength other than red, green, and blue of the spectral characteristic of the color filter.   An electronic apparatus comprising the electro-optical device according to claim 11.

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