JP2008123847A - Planar light source device and liquid crystal display device assembly - Google Patents

Abstract

An object of the present invention is to reliably prevent the occurrence of problems such as color unevenness and luminance unevenness with little variation in the position of an area illuminated by light emitted from a plurality of light emitting element assemblies constituting a light emitting element assembly group. Provided is a planar light source device having a possible configuration and structure.
A planar light source device includes a light emitting element assembly group including a plurality of light emitting element assemblies including a light emitting element and a lens as a light source, and is formed into a two-dimensional matrix by white light. A transmissive liquid crystal display device having a display area composed of arranged pixels is illuminated from the back, and emitted from each light emitting element assembly 100 in a plurality of light emitting element assemblies 100 constituting the light emitting element assembly group. Then, the lens shape 102 in each light emitting element assembly 100 is determined so that the regions of light passing through the light emitting surface of the planar light source device are substantially matched.
[Selection] Figure 1

Description

  The present invention relates to a planar light source device (so-called backlight) that illuminates a transmissive liquid crystal display device having a display area composed of pixels arranged in a two-dimensional matrix from the back, and the planar light source device. The present invention relates to a liquid crystal display device assembly incorporating the above.

  In the liquid crystal display device, the liquid crystal material itself does not emit light. Therefore, for example, a direct type planar light source device (backlight) that illuminates the display area of the liquid crystal display device is disposed on the back surface of the display area composed of a plurality of pixels. In the color liquid crystal display device, one pixel includes, for example, three types of sub-pixels: a red light-emitting subpixel, a green light-emitting subpixel, and a blue light-emitting subpixel. Then, by operating the liquid crystal cell constituting each pixel or each sub-pixel as a kind of light shutter (light valve), that is, controlling the light transmittance (aperture ratio) of each pixel or each sub-pixel, An image is displayed by controlling the light transmittance of illumination light (for example, white light) emitted from the planar light source device.

  Conventionally, a planar light source device in a liquid crystal display device assembly illuminates the entire display area with uniform and constant brightness. However, the planar light source device has a configuration different from such a planar light source device, that is, a plurality of planar light source devices. A planar light source device (partial drive type or split drive type planar light source device) having a configuration that changes the distribution of illuminance in a plurality of display area units is disclosed in, for example, 258403 is known. By controlling the planar light source device (also referred to as partial driving or divided driving of the planar light source device), it is possible to increase the white level and increase the contrast ratio due to the black level decrease in the liquid crystal display device. As a result, the quality of image display can be improved and the power consumption of the planar light source device can be reduced.

  A light emitting diode (LED) assembly is often used as a light source constituting the planar light source device. Here, the light emitting diode assembly includes a light emitting diode and a lens through which light emitted from the light emitting diode passes. The light that has passed through the lens has a radiation angle characteristic (for example, Lambertian distribution) based on the characteristic of the lens. Then, the red light emitting diode, the green light emitting diode, and the blue light emitting diode emit light, and the obtained red light, green light, and blue light are mixed to obtain white light, and the display area of the liquid crystal display device is illuminated with the white light. To do. The planar light source device includes a plurality of light emitting diode assembly groups each including a red light emitting diode assembly, a green light emitting diode assembly, and a blue light emitting diode assembly. The number of red light emitting diode assemblies in one light emitting diode assembly group, the number of green light emitting diode assemblies, the number of blue light emitting diode assemblies, and the arrangement pattern of these light emitting diode assemblies are usually It is determined based on the specifications of the planar light source device. In order to prevent the occurrence of color unevenness and luminance unevenness, these light emitting diode assemblies are often collected at one place.

JP-A-2005-258403

  By the way, in the case where white light is obtained by causing the red light emitting diode, the green light emitting diode, and the blue light emitting diode in the light emitting diode assembly group to emit light and mixing the obtained red light, green light, and blue light as described above. Schematic view of one red light emitting diode assembly (R), one green light emitting diode assembly (G), and one blue light emitting diode assembly (B) constituting one light emitting diode assembly group as viewed from above. Is shown in FIG. 12A, and is emitted from the red light emitting diode assembly (R), the green light emitting diode assembly (G), and the blue light emitting diode assembly (B), and constitutes the light emitting surface of the planar light source device. A region of light for illuminating the light diffusing plate is schematically shown in FIG. Each light emitting diode assembly (R), (G), (B) is assumed to be located at the apex of the virtual equilateral triangle.

  Normally, lenses having the same shape are used in all light emitting diode assemblies. However, the material constituting the light emitting diode, the chip size and chip thickness of the light emitting diode, and the chip shape are often different depending on the red light emitting diode, the green light emitting diode, and the blue light emitting diode. Therefore, the direction and radiation intensity distribution of the light emitted from each of the red light emitting diode assembly (R), the green light emitting diode assembly (G), and the blue light emitting diode assembly (B) are different. Therefore, almost desired white light is obtained in the region of the light diffusing plate immediately above the light emitting diode assembly group, but the region where red light and green light are mixed in the periphery, red light and blue light. There is a region where light is mixed, and a region where green light and blue light are mixed (see FIG. 12B). That is, color unevenness and brightness unevenness occur. In particular, in a partially-driven planar light source device, when one planar light source unit is turned on, the influence of light emission from the other planar light source units is eliminated, so that uneven color and uneven brightness are easily noticeable.

  Accordingly, an object of the present invention is to cause a problem that unevenness of color and luminance unevenness occur with little variation in the position of the area illuminated by the light emitted from the plurality of light emitting element assemblies constituting the light emitting element assembly group. It is an object of the present invention to provide a planar light source device having a configuration and structure capable of reliably preventing generation, and a liquid crystal display device assembly incorporating such a planar light source device.

To achieve the above object, the planar light source device of the present invention comprises:
A light-emitting element assembly group composed of a plurality of light-emitting element assemblies each including a light-emitting element and a lens through which light emitted from the light-emitting element passes;
A display region composed of pixels arranged in a two-dimensional matrix by white light obtained by mixing light of a plurality of colors emitted from a plurality of light emitting element assemblies constituting a light emitting element assembly group A planar light source device for illuminating a transmissive liquid crystal display device having a back surface,
In each of the plurality of light emitting element assemblies constituting the light emitting element assembly group, each light emitting element is arranged so that the distribution of the amount of light emitted from each light emitting element assembly and passing through the light emitting surface of the planar light source device is substantially the same. The lens shape in the assembly is determined.

In order to achieve the above object, the liquid crystal display device assembly of the present invention comprises:
(A) a transmissive liquid crystal display device having a display region composed of pixels arranged in a two-dimensional matrix, and
(B) A light emitting element assembly group including a plurality of light emitting element assemblies each including a light emitting element and a lens through which light emitted from the light emitting element passes is provided as a light source. A planar light source device that illuminates the liquid crystal display device from the back side with white light obtained by mixing light of a plurality of types of colors emitted from a plurality of light emitting element assemblies that constitutes;
With
In each of the plurality of light emitting element assemblies constituting the light emitting element assembly group, each light emitting element is arranged so that the distribution of the amount of light emitted from each light emitting element assembly and passing through the light emitting surface of the planar light source device is substantially the same. The lens shape in the assembly is determined.

In the planar light source device or the liquid crystal display device assembly of the present invention, the distribution of the amount of light passing through the light exit surface of the planar light source device can be defined as follows. That is, for example, one light emitting element assembly group includes a red light emitting element assembly that emits red light, a green light emitting element assembly that emits green light, and a blue light emitting element assembly that emits blue light. It is assumed that the light source device includes a plurality of light emitting element assembly groups. In this case, only the red light emitting element assembly (for example, one or a plurality of red light emitting element assemblies) in one light emitting element assembly group is operated, and the red light passing through the light emitting surface of the planar light source device. Is measured to obtain a red light luminance profile on the light exit surface. Similarly, only the green light emitting element assembly (for example, one or a plurality of green light emitting element assemblies) in the same light emitting element assembly group is operated, and the green light region that passes through the light emitting surface of the planar light source device. And measuring only the blue light emitting element assembly (for example, one or a plurality of blue light emitting element assemblies) in the same light emitting element assembly group. Then, the luminance of the blue light region passing through the light emitting surface of the planar light source device is measured, and the luminance profile of the blue light on the light emitting surface is obtained. And
(A) and the region RG _R surrounded by contours of certain luminance value BR _R in the red light intensity profile of the same luminance value BR _G region RG _G and portions overlap surrounded by contours of the intensity profile of the green light The area of OL _RG is 95% or more of the average value of the area of region RG _{R and} the area of region RG _G.
(B) A portion OL where the region RG _R surrounded by the contour line of the luminance value BR _R in the luminance profile of red light and the region RG _B surrounded by the contour line of the same luminance value BR _B in the luminance profile of blue light overlap. area of _RB is less than 95% of the average value of areas of the area and the region RG _B region RG _R.
(C) A portion OL where the region RG _G surrounded by the contour line of the luminance value BR _G in the luminance profile of green light and the region RG _B surrounded by the contour line of the same luminance value BR _B in the luminance profile of blue light overlap. area of _GB is not less than 95% of the average value of areas of the area and the region RG _B region RG _G.
That satisfies the following three conditions:
OL _RG ≧ 0.95 × (RG _R + RG _G ) / 2
OL _RB ≧ 0.95 × (RG _R + RG _B ) / 2
OL _GB ≧ 0.95 × (RG _G + RG _B ) / 2
When the above three conditions are satisfied, it is assumed that the distribution of the amount of light passing through the light exit surface of the planar light source device is substantially the same. Note that the certain luminance value BR _R , luminance value BR _G , and luminance value BR _B described above may be determined in advance when the planar light source device or the liquid crystal display device assembly is designed.

  In the planar light source device or the liquid crystal display device assembly of the present invention, the lens shape in each light emitting element assembly is determined so that the radiation angle distribution of the light emitted from the light emitting element assembly becomes a desired distribution. It can be set as a structure. Alternatively, the lens shape is selected from a lens characteristic group consisting of the inclination of the lens optical axis with respect to the light emitting element axis (perpendicular through the center of the light emitting element), the degree of eccentricity of the lens optical axis with respect to the light emitting element axis, and the curvature of the lens surface. It can be set as the structure determined based on the at least 1 lens characteristic made. Here, the curvature of the lens surface includes both the curvature in the XZ plane and the curvature in the YZ plane, assuming that the lens optical axis is the Z axis and the X axis and the Y axis extending perpendicularly from the Z axis. Furthermore, as parameters for determining the lens shape, the emission solid angle of the emitted light from the light emitting element assembly, the luminance profile of the emitted light, the radiation angle distribution of the emitted light from the light emitting element, the light emitted from the light emitting element assembly The size of the liquid crystal display device (or display area unit) to be illuminated, the required luminance profile on the liquid crystal display device (or on the display area unit), the chip size and chip thickness of the light emitting element, the chip shape, etc. The lens characteristics may be determined in consideration of these parameters. Or it can be set as the structure by which the lens shape in a light emitting element assembly is determined depending on the arrangement position of the light emitting element assembly in a planar light source device. Specifically, in the light-emitting element assembly positioned close to the side surface of the casing of the planar light source device, the light emitted from the light-emitting element assembly is transmitted to the side surface of the casing of the planar light source device. Since it is strongly affected, the lens shape in the light emitting element assembly may be determined so that the influence is reduced.

  In the planar light source device or the liquid crystal display assembly of the present invention including the above-described preferred configuration, the light emitting surface of the planar light source device can be configured as a light diffusing plate.

  Furthermore, in the planar light source device or the liquid crystal display device assembly of the present invention including the preferred configurations and forms described above, a plurality of light sources may be driven simultaneously under the same driving conditions. Alternatively, a plurality of light sources may be partially driven. That is, when the planar light source device is assumed to divide the display area of the liquid crystal display device into P × Q virtual display area units, P × Q pieces corresponding to these P × Q display area units are used. The planar light source units are individually controlled in the light emission state of the P × Q planar light source units, and the light source provided in each planar light source unit is composed of one light emitting element assembly group. Also good.

  In the planar light source device or liquid crystal display device assembly of the present invention including the preferred configurations and forms described above (hereinafter, these may be collectively referred to simply as the present invention), the lens is an optical glass, Alternatively, it may be made from plastic. Here, as plastic constituting the plastic lens, acrylic resin, polycarbonate resin, polymethyl methacrylate (PMMA) resin, polyolefin resin, polyester resin, polyurethane resin, polysulfone resin, polystyrene resin, vinyl resin Thermosetting resins such as thermoplastic resins such as resins and halogen resins, epoxy resins, polyimide resins, urea resins, phenol resins, and silicone resins can be given. Although the plastic lens depends on the material, it can be molded by, for example, an injection molding method. The lens may be fixed by an appropriate method so as to cover the light emitting element, or the lens and the light emitting element may be integrally manufactured. That is, in the latter case, a hemispherical (dome-shaped) lens may be formed on the light emitting element using, for example, a potting resin, or a lens may be formed based on a combination of a lithography technique and an etching technique.

  In the present invention, a light emitting diode (LED) can be exemplified as the light emitting element. When the light source is composed of a light emitting diode, for example, a red light emitting diode that emits red with a wavelength of 640 nm, for example, a green light emitting diode that emits green with a wavelength of 530 nm, and a blue light emitting diode that emits blue with a wavelength of 450 nm, for example, By doing so, white light can be obtained. Depending on the case, a light emitting diode that emits a fourth color other than red, green, blue, fifth color,... May be further provided. A light source composed of a light emitting diode is preferable because it occupies a small volume.

  Here, as a combination of the light emitting element assemblies constituting the light source, more specifically, (one red light emitting element assembly, one green light emitting element assembly, one blue light emitting element assembly), (one Red light emitting device assembly, two green light emitting device assemblies, one blue light emitting device assembly), (two red light emitting device assemblies, two green light emitting device assemblies, one blue light emitting device assembly), etc. Combinations can be illustrated. Alternatively, one light emitting element assembly group can be configured by a plurality of light emitting element assemblies positioned at the apexes of one or more virtual equilateral triangles, or one or more. One light emitting element assembly group can be configured by a plurality of light emitting element assemblies positioned at the apex of the virtual square. More specifically, for example, three light emitting element assemblies positioned at the apex of one virtual equilateral triangle, that is, (one red light emitting element assembly, one green light emitting element assembly, one blue light emitting element set) A configuration in which one light emitting element assembly group is configured by three-dimensional) can be given, and four light emitting element assemblies positioned at the apex of one virtual square, that is, (one red light emitting element assembly, One green light-emitting element assembly group may be formed by two green light-emitting element assemblies and one blue light-emitting element assembly, and five light-emitting elements located at the vertices of two virtual equilateral triangles. There may be mentioned a form in which one light emitting element assembly group is constituted by element assemblies, that is, (two red light emitting element assemblies, two green light emitting element assemblies, one blue light emitting element assembly).

  The light-emitting diode that constitutes the light source may have a so-called face-up structure or a flip-chip structure. That is, the light-emitting diode includes a substrate and a light-emitting layer formed on the substrate, and may have a structure in which light is emitted from the light-emitting layer to the outside, or light from the light-emitting layer passes through the substrate. It is good also as a structure radiate | emitted outside. More specifically, the light emitting diode (LED) includes, for example, a first compound semiconductor layer having a first conductivity type (for example, n-type) formed on a substrate, and an active layer formed on the first compound semiconductor layer. A first electrode having a stacked structure of a second compound semiconductor layer having a second conductivity type (for example, p-type) formed on the active layer and electrically connected to the first compound semiconductor layer; A second electrode electrically connected to the two-compound semiconductor layer is provided. The layer constituting the light emitting diode may be made of a known compound semiconductor material depending on the emission wavelength.

  The light-emitting diode may further have a structure in which a shell-type or dome-type cap is provided in a portion where light is emitted from the light-emitting layer to the outside. By the way, when an air layer exists between the light emitting layer and the cap, the light emitted from the light emitting layer may not enter the cap immediately and may be totally reflected by the inner surface of the cap. When such a phenomenon occurs, since the totally reflected light is reabsorbed by the light emitting layer, there arises a problem that the light extraction efficiency is reduced. Therefore, it is desirable to fill a filler between the light emitting layer and the cap. The filler is made of a gel material, fluorene acrylic resin, silicone rubber, or silicone oil compound, and the refractive index is preferably 1.40 or more. More specifically, as the gel material, for example, trade name OCK-451 (refractive index: 1.51) and trade name OCK-433 (refractive index: 1.46) of Nye can be exemplified. An oil compound material such as silicone rubber or silicone oil compound [for example, trade name TSK5353 (refractive index: 1.45) of Toshiba Silicone Co., Ltd.] can be exemplified. In addition, when a shell-type or dome-shaped cap functions as a lens and it is not necessary to arrange a lens separately, the cap can be regarded as a lens.

  The planar light source device may include a light diffusing plate, and may further include an optical function sheet group such as a diffusing sheet, a prism sheet, and a polarization conversion sheet, and a reflecting sheet. The optical function sheet group may be configured from various sheets that are spaced apart from each other, or may be stacked and integrated. The light diffusing plate and the optical function sheet group are disposed between the planar light source device and the liquid crystal display device. Examples of the material constituting the light diffusion plate include polycarbonate resin (PC), polystyrene resin (PS), and methacrylic resin.

  A partition may be provided between the planar light source unit and the planar light source unit. Specific examples of the material constituting the partition include materials that are opaque to light emitted from a light source provided in a planar light source unit, such as acrylic resin, polycarbonate resin, and ABS resin. Illustrate PMMA resin, polycarbonate resin (PC), polyarylate resin (PAR), polyethylene terephthalate resin (PET), glass as a material transparent to light emitted from the light source provided in the planar light source unit Can do. A light diffusion reflection function may be imparted to the partition wall surface, or a specular reflection function may be imparted. In order to impart a light diffusing and reflecting function to the partition wall surface, irregularities may be formed on the partition wall surface based on a sandblasting method, or a film (light diffusion film) having irregularities may be attached to the partition wall surface. In addition, in order to impart a specular reflection function to the partition wall surface, a light reflection film may be attached to the partition wall surface, or a light reflection layer may be formed on the partition wall surface by plating, for example.

  The transmissive liquid crystal display device includes, for example, a front panel having a transparent first electrode, a rear panel having a transparent second electrode, and a liquid crystal material disposed between the front panel and the rear panel. Consists of. The liquid crystal display device may be a monochrome liquid crystal display device or a color liquid crystal display device.

  More specifically, the front panel includes, for example, a first substrate made of, for example, a glass substrate or a silicon substrate, and a transparent first electrode (also called a common electrode, for example, ITO provided on the inner surface of the first substrate. And a polarizing film provided on the outer surface of the first substrate. Further, in the transmissive color liquid crystal display device, a color filter covered with an overcoat layer made of acrylic resin or epoxy resin is provided on the inner surface of the first substrate. Examples of the color filter arrangement pattern include a delta arrangement, a stripe arrangement, a diagonal arrangement, and a rectangle arrangement. The front panel further has a configuration in which a transparent first electrode is formed on the overcoat layer. An alignment film is formed on the transparent first electrode. On the other hand, the rear panel more specifically includes, for example, a second substrate made of a glass substrate or a silicon substrate, a switching element formed on the inner surface of the second substrate, and conduction / non-conduction by the switching element. A transparent second electrode to be controlled (also called a pixel electrode, which is made of, for example, ITO) and a polarizing film provided on the outer surface of the second substrate. An alignment film is formed on the entire surface including the transparent second electrode. Various members and liquid crystal materials constituting the liquid crystal display device including these transmissive color liquid crystal display devices can be formed of known members and materials. Examples of the switching element include a three-terminal element such as a MOS type FET and a thin film transistor (TFT) formed on a single crystal silicon semiconductor substrate, and a two-terminal element such as an MIM element, a varistor element, and a diode.

  An area where the transparent first electrode and the transparent second electrode overlap and includes a liquid crystal cell corresponds to one pixel (pixel) or one sub-pixel (sub-pixel). In the transmissive color liquid crystal display device, the red light emitting sub-pixel (which may be referred to as sub-pixel [R]) constituting each pixel (pixel) transmits red light with the liquid crystal cell constituting the region. The green light emitting subpixel (sometimes referred to as subpixel [G]) is composed of a combination of a liquid crystal cell constituting the region and a color filter that transmits green light. The blue light-emitting subpixel (sometimes referred to as subpixel [B]) is composed of a combination of a liquid crystal cell that forms the region and a color filter that transmits blue light. The arrangement pattern of the sub-pixel [R], sub-pixel [G], and sub-pixel [B] matches the arrangement pattern of the color filter described above. The pixel is not limited to a configuration in which three types of sub-pixels [R, G, B], which are a sub-pixel [R], a sub-pixel [G], and a sub-pixel [B], are configured as one set. For example, a set of these three types of sub-pixels [R, G, B] plus one or more types of sub-pixels (for example, one sub-pixel that emits white light to improve brightness) To expand the color reproduction range, one set including sub-pixels that emit complementary colors to expand the color reproduction range, one set including sub-pixels that emit yellow to expand the color reproduction range It can also be composed of a set of subpixels that emit yellow and cyan.

  Here, the light transmittance (also referred to as aperture ratio) Lt of the pixel or sub-pixel, the luminance (display luminance) y of the display area corresponding to the pixel or sub-pixel, and the luminance (light source luminance) of the planar light source unit Y is defined as follows:

Y ₁ ... Is the maximum luminance of the light source luminance, for example, and may be hereinafter referred to as the light source luminance and the first specified value.
Lt ₁ ... Is the maximum value of the light transmittance (aperture ratio) of the pixels or sub-pixels in the display area unit, for example, and may be hereinafter referred to as light transmittance / first specified value.
Lt ₂ ... In the display area unit / input signal maximum value x _U-max that is the maximum value of the values of the input signals input to the drive circuit for driving all the pixels constituting the display area unit. This is the light transmittance (aperture ratio) of the pixel or sub-pixel when it is assumed that a control signal corresponding to an input signal having the same value is supplied to the pixel or sub-pixel. Sometimes called. In addition, 0 ≦ Lt ₂ ≦ Lt ₁
y ₂ ... When the light source luminance is the light source luminance and the first specified value Y ₁ and the light transmittance (aperture ratio) of the pixel or sub-pixel is assumed to be the light transmittance and the second specified value Lt ₂ The display brightness obtained in the following is sometimes referred to as “display brightness / second prescribed value”.
Y ₂ ... ・ In the display area unit ・ Assuming that a control signal corresponding to an input signal having a value equal to the input signal maximum value x _U-max is supplied to the pixel or sub-pixel, Assuming that the light transmittance (aperture ratio) of the sub-pixel is corrected to the light transmittance / first prescribed value Lt ₁ , the luminance of the pixel or the sub-pixel is set to the display luminance / second prescribed value (y ₂ ). The light source brightness of the planar light source unit. However, the light source luminance Y ₂ may be corrected in consideration of the influence of the light source luminance of each planar light source unit on the light source luminance of other planar light source units.

When the planar light source device is partially driven, it is assumed that a control signal corresponding to an input signal having a value equal to the input signal maximum value x _U-max in the display area unit is supplied to the pixel. The luminance of the light source constituting the planar light source unit corresponding to the display area unit is controlled by the drive circuit so that the ratio, the display luminance at the first specified value Lt _1, and the second specified value y ₂ ) are obtained. Specifically, for example, the light source luminance Y ₂ is set so that the display luminance y ₂ can be obtained when the light transmittance (aperture ratio) of the pixel or sub-pixel is, for example, the light transmittance · the first specified value Lt _1. What is necessary is just to control (for example, to reduce). That is, for example, the light source luminance Y ₂ of the planar light source unit may be controlled for each image display frame so as to satisfy the following expression (1). Note that Y ₂ ≦ Y ₁ .

Y ₂ · Lt ₁ = Y ₁ · Lt ₂ (1)

When expressed in pixels arranged in a two-dimensional matrix the number M ₀ × N ₀ of _{(pixels) (M 0, N 0)} , the value of (M _0, N _0), specifically, VGA ( 640,480), S-VGA (800,600), XGA (1024,768), APRC (1152,900), S-XGA (1280,1024), U-XGA (1600,1200), HD-TV ( 1920, 1080), Q-XGA (2048, 1536), (1920, 1035), (720, 480), (1280, 960), etc. It is not limited to these values. Further, the relationship between the value of (M ₀ , N ₀ ) and the value of (P, Q) is not limited, but can be exemplified in Table 1 below. Examples of the number of pixels constituting one display area unit include 20 × 20 to 320 × 240, preferably 50 × 50 to 200 × 200. The number of pixels in the display area unit may be constant or different.

  The driving circuit for driving the liquid crystal display device and the planar light source device includes, for example, a planar light source device control circuit and a planar light source configured from a light emitting diode (LED) driving circuit, an arithmetic circuit, a storage device (memory), and the like. A unit drive circuit and a liquid crystal display device drive circuit including a known circuit such as a timing controller are provided. The luminance of the display area (display luminance) and the luminance of the planar light source unit (light source luminance) are controlled for each image display frame. Note that the number of image information (images per second) sent to the drive circuit as electrical signals per second is the frame frequency (frame rate), and the inverse of the frame frequency is the frame time (unit: seconds).

  In the present invention, in the plurality of light emitting element assemblies constituting the light emitting element assembly group, the distribution of the amount of light emitted from each light emitting element assembly and passing through the light emitting surface of the planar light source device is substantially the same. Thus, the lens shape in each light emitting element assembly is determined. Accordingly, it is difficult for color unevenness and brightness unevenness to be recognized in the white light emitted from the light emitting surface of the planar light source device, and it is possible to provide a liquid crystal display device assembly having high image display quality.

  Further, when the partial drive method (divided drive method) is adopted in the present invention, the luminance distribution when only one display area unit is turned on is made more uniform, so that the performance is improved (contrast ratio is increased, power consumption is reduced). Design for reduction, etc.). Furthermore, the luminance distribution when the plurality of display area units are simultaneously turned on is further uniformized.

Furthermore, in the present invention, a partial drive method (divided drive method) is adopted, and a control signal corresponding to an input signal having a value equal to the maximum value x _U-max in the display area unit is supplied to the pixel. In order to obtain the assumed pixel brightness (light transmittance, display brightness at the first specified value Lt ₁ , second specified value y ₂ ), the light source constituting the planar light source unit corresponding to the display area unit is obtained. If the luminance is controlled by the drive circuit, not only can the power consumption of the planar light source device be reduced, but also the white level can be increased and the black level can be reduced, and a high contrast ratio (on the screen surface of the liquid crystal display device, The brightness ratio of the all-black display part and all-white display part without external light reflection etc. can be obtained and the brightness of the desired display area can be emphasized, so that the image display quality is improved. Can be Kill.

  Hereinafter, the present invention will be described based on embodiments with reference to the drawings. Prior to this, a transmissive liquid crystal display device suitable for use in the embodiments (specifically, a transmissive color liquid crystal display device) will be described. An outline of the planar light source device will be described with reference to FIGS. 5, 6, 7 (A) and (B), and FIG. 8.

  The planar light source device in the following description corresponds to these P × Q display area units when it is assumed that the display area of the liquid crystal display device is divided into P × Q virtual display area units. The planar light source unit is composed of P × Q planar light source units, the light emission states of the P × Q planar light source units are individually controlled, and the light source provided in each planar light source unit is a single light emitting element assembly group. A so-called partial drive type (divided drive type) planar light source device. However, the present invention is not limited to such a planar light source device, and a method of driving a plurality of light sources simultaneously under the same driving conditions may be adopted.

As shown in the conceptual diagram of FIG. 5, the transmissive color liquid crystal display device 10 in the embodiment has a total of M ₀ ×, which is M ₀ along the first direction and N ₀ along the second direction. A display area 11 in which N ₀ pixels are arranged in a two-dimensional matrix is provided. Here, it is assumed that the display area 11 is divided into P × Q virtual display area units 12. Each display area unit 12 is composed of a plurality of pixels. Specifically, for example, the image display resolution satisfies the HD-TV standard, and the number M ₀ × N ₀ of pixels (pixels) arranged in a two-dimensional matrix is expressed as (M ₀ , N ₀ ). For example, (1920, 1080). In addition, a display area 11 (indicated by a one-dot chain line in FIG. 5) composed of pixels arranged in a two-dimensional matrix is divided into P × Q virtual display area units 12 (the boundary is indicated by a dotted line). ing. The value of (P, Q) is (19, 12), for example. However, in order to simplify the drawing, the number of display area units 12 (and a planar light source unit 42 described later) in FIG. 5 is different from this value. Each display area unit 12 is composed of a plurality of (M × N) pixels, and the number of pixels constituting one display area unit 12 is, for example, about 10,000. Each pixel is configured as a set of a plurality of sub-pixels that emit different colors. More specifically, each pixel has three types of red light emitting subpixel (subpixel [R]), green light emitting subpixel (subpixel [G]), and blue light emitting subpixel (subpixel [B]). Of sub-pixels (sub-pixels). The transmissive color liquid crystal display device 10 is line-sequentially driven. More specifically, the color liquid crystal display device 10 includes scan electrodes (extending along the first direction) and data electrodes (extending along the second direction) that intersect in a matrix. Then, a scanning signal is input to the scanning electrode to select and scan the scanning electrode, and an image is displayed based on the data signal (a signal based on the control signal) input to the data electrode to constitute one screen.

  The color liquid crystal display device 10 includes a front panel 20 provided with a transparent first electrode 24, a rear panel 30 provided with a transparent second electrode 34, and a schematic partial sectional view shown in FIG. The liquid crystal material 13 is disposed between the front panel 20 and the rear panel 30.

  The front panel 20 includes, for example, a first substrate 21 made of a glass substrate and a polarizing film 26 provided on the outer surface of the first substrate 21. A color filter 22 covered with an overcoat layer 23 made of acrylic resin or epoxy resin is provided on the inner surface of the first substrate 21, and a transparent first electrode (also called a common electrode) is provided on the overcoat layer 23. (For example, made of ITO) 24 is formed, and an alignment film 25 is formed on the transparent first electrode 24. On the other hand, the rear panel 30 more specifically includes, for example, a second substrate 31 made of a glass substrate, and switching elements (specifically, thin film transistors and TFTs) formed on the inner surface of the second substrate 31. 32, a transparent second electrode (also referred to as a pixel electrode, made of, for example, ITO) 34 whose conduction / non-conduction is controlled by the switching element 32, and a polarizing film 36 provided on the outer surface of the second substrate 31, It is composed of An alignment film 35 is formed on the entire surface including the transparent second electrode 34. The front panel 20 and the rear panel 30 are joined via a sealing material (not shown) at their outer peripheral portions. Note that the switching element 32 is not limited to a TFT, and may be composed of, for example, an MIM element. Reference numeral 37 in the drawing is an insulating layer provided between the switching element 32 and the switching element 32.

  Since various members and liquid crystal materials constituting these transmissive color liquid crystal display devices can be composed of well-known members and materials, detailed description thereof is omitted.

  The direct-type planar light source device (backlight) 40 includes P × Q planar light source units 42 corresponding to the P × Q virtual display area units 12. The display area unit 12 corresponding to the light source unit 42 is illuminated from the back. The light sources provided in the planar light source unit 42 are individually controlled. However, the light source luminance of the planar light source unit 42 is not affected by the light emission state of the light sources provided in the other planar light source units 42. In addition, although the planar light source device 40 is located below the color liquid crystal display device 10, the color liquid crystal display device 10 and the planar light source device 40 are separately displayed in FIG. FIG. 7A schematically shows the arrangement and arrangement of the light-emitting element assemblies and the like in the planar light source device 40, and schematically shows a liquid crystal display device assembly including the color liquid crystal display device 10 and the planar light source device 40. A partial cross-sectional view is shown in FIG. The light source includes a light emitting element assembly 100 driven based on a pulse width modulation (PWM) control method. The luminance of the planar light source unit 42 is increased / decreased by increasing / decreasing the duty ratio in the pulse width modulation control of the light emitting element assembly 100 constituting the planar light source unit 42.

  As shown in a schematic partial cross-sectional view of the liquid crystal display device assembly in FIG. 7B, the planar light source device 40 includes a casing 51 having an outer frame 53 and an inner frame 54. Yes. The end of the transmissive color liquid crystal display device 10 is held by the outer frame 53 and the inner frame 54 so as to be sandwiched between the spacers 55A and 55B. A guide member 56 is disposed between the outer frame 53 and the inner frame 54 so that the color liquid crystal display device 10 sandwiched between the outer frame 53 and the inner frame 54 does not shift. Details of the planar light source unit 42 will be described later. A light diffusion plate 61 is attached to the inner frame 54 via a spacer 55 </ b> C and a bracket member 57 in the upper portion of the housing 51. On the light diffusion plate 61, an optical function sheet group such as a diffusion sheet 62, a prism sheet 63, and a polarization conversion sheet 64 is laminated. A reflection sheet 65 is provided inside and below the housing 51. Here, the reflection sheet 65 is disposed so that the reflection surface thereof faces the light diffusion plate 61, and is attached to the bottom surface 52 </ b> A of the housing 51 via an attachment member (not shown). The reflection sheet 65 can be composed of, for example, a silver-enhanced reflection film having a structure in which a silver reflection film, a low refractive index film, and a high refractive index film are sequentially laminated on a sheet base material. The reflection sheet 65 reflects the light emitted from the plurality of light emitting element assemblies 100 and the light reflected by the side surface 52B of the housing 51 or the partition wall 41 shown in FIG. Thus, red light, green light, and blue light emitted from the red light emitting element assembly 100R that emits red light, the green light emitting element assembly 100G that emits green light, and the blue light emitting element assembly 100B that emits blue light are mixed. Thus, white light with high color purity can be obtained as illumination light. The illumination light is emitted from the planar light source unit 42 through the light diffusion plate 61, passes through the optical function sheet group such as the diffusion sheet 62, the prism sheet 63, and the polarization conversion sheet 64, and the color liquid crystal display device 10 is viewed from the back side. Illuminate.

  In the vicinity of the bottom surface 52A of the housing 51, photodiodes 43R, 43G, and 43B, which are optical sensors, are arranged. The photodiode 43R is a photodiode with a red filter attached to measure the light intensity of red light, and the photodiode 43G is a photo diode with a green filter attached to measure the light intensity of green light. The photodiode 43B is a photodiode to which a blue filter is attached in order to measure the light intensity of blue light. Here, one set of photosensors (photodiodes 43R, 43G, 43B) is arranged in one planar light source unit 42. The luminance and chromaticity of the light emitting diodes 101R, 101G, and 101B are measured by the photodiodes 43R, 43G, and 43B that are optical sensors.

  As shown in FIGS. 5 and 6, the driving circuit for driving the planar light source device 40 and the color liquid crystal display device 10 based on an input signal from the outside (display circuit) is based on the pulse width modulation control method. Red light emitting diode 101R constituting the red light emitting element assembly 100R constituting the light source device 40, green light emitting diode 101G constituting the green light emitting element assembly 100G, and blue light emitting diode 101B constituting the blue light emitting element assembly 100B. It comprises a planar light source device control circuit 70, a planar light source unit drive circuit 80, and a liquid crystal display device drive circuit 90 that perform on / off control.

  The planar light source device control circuit 70 includes an arithmetic circuit 71 and a storage device (memory) 72. On the other hand, the planar light source unit driving circuit 80 includes an arithmetic circuit 81, a storage device (memory) 82, an LED driving circuit 83, a photodiode control circuit 84, switching elements 85R, 85G, and 85B composed of FETs, and a light emitting diode driving power source (constant). Current source) 86. These circuits constituting the planar light source device control circuit 70 and the planar light source unit drive circuit 80 can be known circuits. On the other hand, a liquid crystal display device driving circuit 90 for driving the color liquid crystal display device 10 includes a known circuit such as a timing controller 91. The color liquid crystal display device 10 is provided with a gate driver, a source driver, and the like (not shown) for driving the switching element 32 formed of a TFT constituting the liquid crystal cell.

  The light emitting states of the light emitting diodes 101R, 101G, and 101B in an image display frame are measured by the photodiodes 43R, 43G, and 43B, and the outputs from the photodiodes 43R, 43G, and 43B are input to the photodiode control circuit 84. In the photodiode control circuit 84 and the arithmetic circuit 81, for example, data (signals) as the luminance and chromaticity of the light emitting diodes 101R, 101G, and 101B are sent to the LED drive circuit 83, and the next image display frame A feedback mechanism is formed in which the light emitting states of the light emitting diodes 101R, 101G, and 101B are controlled.

Also, current detection resistors r _R , r _G , r _B are inserted in series with the light emitting diodes 101R, 101G, 101B downstream of the light emitting diodes 101R, 101G, 101B, and the resistors r _R , r The operation of the light-emitting diode drive power supply 86 is controlled under the control of the LED drive circuit 83 so that the currents flowing through _{G 1} and r _B are converted into voltages, and the voltage drops in the resistors r _R , r _G and r _B have predetermined values. Is controlled. Here, FIG. 6 shows a single light emitting diode driving power source (constant current source) 86, but actually, the light emitting diode driving power source for driving each of the light emitting diodes 101R, 101G, and 101B. 86 is arranged.

  A display area 11 composed of pixels arranged in a two-dimensional matrix is divided into P × Q display area units. When this state is expressed by “row” and “column”, Q rows × It can be said that the display area unit is divided into P columns. The display area unit 12 is composed of a plurality of (M × N) pixels. When this state is expressed by “row” and “column”, it is composed of pixels of N rows × M columns. I can say. Further, the red light emitting subpixel (subpixel [R]), the green light emitting subpixel (subpixel [G]), and the blue light emitting subpixel (subpixel [B]) are collectively collected as “subpixel [ R, G, B] ”and may be referred to as“ sub-pixel ”for controlling the operation of the sub-pixel [R, G, B] (specifically, for example, controlling the light transmittance (aperture ratio)). The red light emitting subpixel / control signal, the green light emitting subpixel / control signal, and the blue light emitting subpixel / control signal input to [R, G, B] are collectively referred to as “control signal [R, G, B] ”and may be referred to as a red light-emitting subpixel / input signal or a green light-emitting subpixel that is input to the drive circuit from the outside in order to drive the subpixels [R, G, B] constituting the display area unit. The input signal and the blue light emitting subpixel / input signal may be collectively referred to as “input signal [R, G, B]”.

As described above, each pixel includes a red light emitting subpixel (red light emitting subpixel, subpixel [R]), a green light emitting subpixel (green light emitting subpixel, subpixel [G]), and a blue light emitting subpixel ( The blue light emitting subpixel and the subpixel [B]) are configured as a set of three subpixels (subpixels). In the following description of the embodiments, it is assumed that the luminance control (gradation control) of each of the sub-pixels [R, G, B] is 8-bit control and is performed in 2 ⁸ steps from 0 to 255. Therefore, the value of the input signal [R, G, B] input to the liquid crystal display device driving circuit 90 to drive each of the sub-pixels [R, G, B] in each pixel constituting each display area unit 12. x _R, x _G, each x _B, takes a value of 2 ⁸ steps. Also, the pulse width modulation output signal values S _R , for controlling the light emission times of the red light emitting element assembly 100R, the green light emitting element assembly 100G, and the blue light emitting element assembly 100B constituting each planar light source unit. S _G and S _B also have values of 2 ⁸ steps from 0 to 255. However, the present invention is not limited to this. For example, 10-bit control can be performed in 2 ¹⁰ stages from 0 to 1023. In this case, if an 8-bit numerical expression is multiplied by, for example, 4 times Good.

A control signal for controlling the light transmittance Lt of each pixel is supplied from the drive circuit to each pixel. Specifically, a control signal [R, G, B] for controlling the light transmittance Lt of each of the sub-pixels [R, G, B] is transmitted to each of the sub-pixels [R, G, B]. Supplied from the drive circuit 90. That is, in the liquid crystal display device driving circuit 90, a control signal [R, G, B] is generated from the input signal [R, G, B] that is input, and the control signal [R, G, B] is subpixel. [R, G, B] are supplied (output). Since the light source luminance Y ₂ that is the luminance of the planar light source unit 42 is changed for each image display frame, the control signal [R, G, B] is, for example, the value of the input signal [R, G, B]. Values X _R-corr , X _G-corr , and X _B-corr obtained by performing correction (compensation) based on the change in the light source luminance Y _{2 with} respect to the values obtained by raising x _R , x _G , and x _B to the power of 2.2. Have. Then, the control signal [R, G, B] is sent from the timing controller 91 constituting the liquid crystal display device driving circuit 90 to the gate driver and the source driver of the color liquid crystal display device 10 by a known method. Based on [R, G, B], the switching element 32 constituting each subpixel is driven, and a desired voltage is applied to the transparent first electrode 24 and the transparent second electrode 34 constituting the liquid crystal cell. The light transmittance (aperture ratio) Lt of the sub-pixel is controlled. Here, the larger the values X _R-corr , X _G-corr , and X _B-corr of the control signal [R, G, B], the light transmittance (aperture ratio) Lt of the sub-pixel [R, G, B]. And the value of the luminance (display luminance y) of the display area corresponding to the sub-pixel [R, G, B] increases. That is, an image composed of light passing through the sub-pixels [R, G, B] (usually a kind of dot) is bright.

The display brightness y and the light source brightness Y ₂ are controlled for each image display frame, each display area unit, and each planar light source unit in the image display of the color liquid crystal display device 10. Further, the operation of the color liquid crystal display device 10 and the operation of the planar light source device 40 within one image display frame are synchronized. Note that the number of image information (images per second) sent to the drive circuit as electrical signals per second is the frame frequency (frame rate), and the inverse of the frame frequency is the frame time (unit: seconds).

  Example 1 relates to the planar light source device and the liquid crystal display device assembly of the present invention. A schematic view of a planar light source unit 42 constituting the planar light source device 40 of Example 1 as viewed from above is shown in FIG. 1A, and three light emitting element assemblies constituting one light emitting element assembly group are shown. The state of the light emitted from is schematically shown in FIG.

  As described above, the planar light source device 40 includes P × Q planar light source units 42. Here, each planar light source unit 42 includes a light emitting element assembly 100R, 100G, and 100B that includes a light emitting element (light emitting diode 101) and a lens 102 through which light emitted from the light emitting element (light emitting diode 101) passes. The light-emitting element assembly group composed of a plurality of light-emitting element assemblies is provided as a light source, and as described above, a plurality of types of colors emitted from the plurality of light-emitting element assemblies 100R, 100G, and 100B constituting the light-emitting element assembly group. The color liquid crystal display device 10 is illuminated from the back by white light obtained by mixing light (specifically, red, green and blue). In the first embodiment, a plurality of light emitting element assemblies (specifically, one red light emitting element assembly 100R, one green light emitting element assembly 100G, and One blue light emitting element assembly 100B) constitutes one light emitting element assembly group.

  Then, in the plurality of light emitting element assemblies 100R, 100G, and 100B constituting the light emitting element assembly group, the light is emitted from the respective light emitting element assemblies 100R, 100G, and 100B and passes through the light emitting surface of the planar light source device 40. The lens shapes of the light emitting element assemblies 100R, 100G, and 100B are determined so that the distribution of the amount of light (specifically, illuminating the light diffusing plate 61) substantially matches.

Specifically, only the red light emitting element assembly 100R in one light emitting element assembly group is operated to measure the luminance of the red light region that illuminates the light diffusing plate 61, and the light emitting surface (light diffusing plate 61). The luminance profile of red light at is obtained. Similarly, only the green light emitting element assembly 100G in the same light emitting element assembly group is operated, the luminance measurement of the green light region illuminating the light diffusing plate 61 is performed, and the green color on the light emitting surface (light diffusing plate 61) is measured. A luminance profile of light is obtained, and only the blue light emitting element assembly 100B in the same light emitting element assembly group is operated to measure the luminance of the blue light region that illuminates the light diffusing plate 61. A luminance profile of blue light in the plate 61) is obtained. Then, (shown in solid lines in FIGS. 1 (B)) certain luminance value BR region surrounded by the contour line of _R RG _R in the luminance profile of the red light, with contour lines of the same luminance value BR _G in the luminance profile of the green light enclosed area RG _G (indicated by the dotted line in the FIG. 1 (B)), by a one-dot chain line in the same luminance value BR region RG _B surrounded by contours of _B in the luminance profile of the blue light (shown in FIG. 1 (B) However, the lens shapes of the light emitting element assemblies 100R, 100G, and 100B are determined so as to satisfy the following conditions.
(A) The area of the portion OL _RG where the region RG _R and the region RG _G overlap is 95% or more of the average value of the area of the region RG _{R and} the area of the region RG _G. That is,
OL _RG ≧ 0.95 × (RG _R + RG _G ) / 2
(B) The area of the partial OL _RB where the region RG _R and the region RG _B overlap is 95% or more of the average value of the area of the region RG _{R and} the area of the region RG _B. That is,
OL _RB ≧ 0.95 × (RG _R + RG _B ) / 2
(C) The area of the partial OL _GB where the region RG _G and the region RG _B overlap is 95% or more of the average value of the area of the region RG _{G and} the area of the region RG _B. That is,
OL _GB ≧ 0.95 × (RG _G + RG _B ) / 2

  The lens 102 is manufactured from an acrylic resin based on an injection molding method, and is designed so as to obtain a light emitting element assembly having a radiation angle distribution close to Lambertian. In FIG. 1A, or in FIGS. 3A and 3B described later, the light emitting element assemblies 100R, 100G, and 100B are indicated by circles with “R”, “G”. "And a circle with" B ".

  The light emitting element assemblies 100R, 100G, and 100B are fixed to the bottom surface 52A of the housing 51 by an appropriate method. The lens 102 is fixed using, for example, an adhesive so as to cover the light emitting element (the light emitting diode 101). As described above, the red light emitting diode 101R, the green light emitting diode 101G, and the blue light emitting diode 101B are driven based on the pulse width modulation (PWM) control method, and the red light emitting diode 101R emits red light (for example, wavelength 640 nm). The green light emitting diode 101G emits green light (for example, wavelength 530 nm), and the blue light emitting diode 101B emits blue light (for example, wavelength 450 nm).

  In the first embodiment, the lens shape in each of the light emitting element assemblies 100R, 100G, and 100B is determined so that the radiation angle distribution of the light emitted from the lens 102 becomes a desired distribution. Here, in the first embodiment, more specifically, the lens shape is determined based on lens characteristics such as the curvature of the lens surface. Here, the curvature of the lens surface means both the curvature in the XZ plane and the curvature in the YZ plane, assuming that the lens optical axis is the Z axis and the X axis and the Y axis extending perpendicularly from the Z axis are assumed. Specifically, since each of the light emitting element assemblies 100R, 100G, and 100B is located at the apex of the virtual equilateral triangle (see FIG. 1A), the lens optical axis is the Z axis, and the center of the virtual equilateral triangle. The coordinate axis extending perpendicularly from the Z axis through the X axis is indicated by an imaginary equilateral triangle on the surface of the lens 102 cut along the XZ plane. The curvature value on the center side is made smaller than the curvature value on the surface of the lens 102 on the opposite side. In FIG. 1B, the surface of the lens 102 opposite to the center of the virtual equilateral triangle is indicated by a solid line, and the surface of the lens 102 on the center side of the virtual equilateral triangle is indicated by a dotted line. As a result, the center of the radiation angle distribution of the light emitted from each light emitting element assembly is shifted from the lens optical axis to the center side of the virtual equilateral triangle. As a result, a plurality of light emitting elements constituting the light emitting element assembly group In the assemblies 100R, 100G, and 100B, the distribution of the amount of light emitted from each of the light emitting element assemblies 100R, 100G, and 100B and passing through the light emitting surface (illuminating the light diffusing plate 61) can be substantially matched. .

  As schematically shown in FIG. 2A, the lens shape may be determined based on lens characteristics such as the inclination of the lens optical axis with respect to the light emitting element axis (perpendicular line passing through the center of the light emitting element). In FIG. 2A, the lens shape before tilting the lens optical axis is indicated by a dotted line, and the lens shape after tilting the lens optical axis is indicated by a solid line. Alternatively, as schematically shown in FIG. 2B, the lens shape is the degree of eccentricity of the lens optical axis with respect to the light emitting element axis (the distance between the light emitting element axis extending parallel to each other and the lens optical axis). You may determine based on a lens characteristic. In FIG. 2B, the light emitting diode 101 located inside the light emitting element assembly 100 is schematically illustrated. Furthermore, it may be determined based on any combination of the various lens characteristics described above. Furthermore, as parameters for determining the lens shape, the emission solid angle of the emitted light from the light emitting element assembly, the luminance profile of the emitted light, the radiation angle distribution of the emitted light from the light emitting element, the light emitted from the light emitting element assembly The size of the liquid crystal display device (or display area unit) to be illuminated, the required luminance profile on the liquid crystal display device (or on the display area unit), the chip size and chip thickness of the light emitting element, the chip shape, etc. The lens characteristics may be determined in consideration of these parameters.

  A schematic cross-sectional view of the light emitting diode 101 is shown in FIG. The light emitting diode 101 includes a light emitting layer 110 fixed to a support and a plastic cap 116. Specifically, a cap 116 is put on the light emitting portion of the light emitting layer 110. Further, the cap 116 covers the light emitting layer 110 through the space 117. Specifically, the light emitting layer 110 is fixed to the submount 111, and the light emitting layer 110 is connected to the external electrodes 115A and 115B via wiring (not shown) provided on the submount 111 and gold wires 114A and 114B. The external electrodes 115A and 115B are electrically connected to a drive circuit (not shown). The submount 111 is attached to the heat sink 112 via an adhesive, and the heat sink 112 is attached to the support member 113. A space 117 between the cap 116 and the light emitting diode 101 is filled with a filler 118 that is transparent to the light emitted from the light emitting layer 110. The cap 116 is made of an acrylic resin and is formed by an injection molding method. The support is made of PMMA resin, and includes a support member 113 molded by an injection molding method and a heat sink 112 bonded to the support member 113 with an adhesive. The filler 118 is made of a gel material, a fluorene acrylic resin, a silicone rubber, or a silicone oil compound, and has a refractive index of 1.40 or more. Specifically, as the gel material, for example, trade name OCK-451 (refractive index: 1.51) and trade name OCK-433 (refractive index: 1.46) of Nye can be exemplified, Examples include oil compound materials such as silicone rubber and silicone oil compound [for example, trade name TSK5353 (refractive index: 1.45) of Toshiba Silicone Co., Ltd.]. By filling the space 117 with such a filler 118, the light emitted from the light emitting layer 110 can surely enter the cap 116 without being totally reflected by the cap 116. That is, when the light emitted from the light emitting layer 110 is totally reflected by the cap 116, the totally reflected light is reabsorbed by the light emitting layer 110, which causes a problem that the light extraction efficiency decreases. By filling the space 117 with the filler 118, it is possible to reliably avoid such a problem.

  The second embodiment is a modification of the first embodiment. In the second embodiment, the lens shape of the light emitting element assembly is determined depending on the arrangement position of the light emitting element assembly in the planar light source device. Specifically, the light emitting element assembly positioned close to the two side surfaces 52B of the housing of the planar light source device (indicated by the symbol “A” in the planar light source device 40 illustrated in FIG. 5) In the light emitting element assembly (indicated by the symbol “B” in the planar light source device 40 shown in FIG. 5) positioned close to one side surface 52B of the casing of the planar light source device The light emitted from the light emitting element assembly is a light emitting element assembly positioned away from the side surface 52B of the casing of the planar light source device (in the planar light source device 40 shown in FIG. The position of the lens in the light emitting element assembly may be determined so as to reduce the influence of the side surface 52B of the housing of the planar light source device 40. Specifically, in the light emitting element assembly positioned close to the side surface 52B of the casing of the planar light source device, the center of the radiation angle distribution of the light emitted from each light emitting element assembly is the planar light source device. What is necessary is just to determine the lens shape in a light emitting element assembly so that it may leave | separate further from the side surface 52B of this housing | casing. Except for this point, the configuration and structure of the planar light source device 40 or the color liquid crystal display device 10 of the second embodiment are the same as the configuration and structure of the planar light source device 40 or the color liquid crystal display device 10 of the first embodiment. Therefore, detailed description is omitted.

  The third embodiment is a modification of the first embodiment. 3A and 3B are schematic views of the planar light source unit 42 constituting the planar light source device 40 of Example 3 as viewed from above. Here, in the example shown in FIG. 3A, a plurality of light emitting element assemblies (specifically, one red light emitting element assembly 100R and two green light emitting elements located at the apex of one virtual square) The assembly 100G and one blue light emitting element assembly 100B) constitute one light emitting element assembly group. In the example shown in FIG. 3B, a plurality of light emitting element assemblies (specifically, one red light emitting element assembly 100R and two green light emitting elements positioned at the vertices of two virtual equilateral triangles). The assembly 100G and the two blue light emitting element assemblies 100B) constitute one light emitting element assembly group. Except for these points, the configuration and structure of the planar light source device 40 or the color liquid crystal display device 10 of the third embodiment are the same as those of the planar light source device 40 or the color liquid crystal display device 10 of the first embodiment. Detailed description will be omitted.

  Hereinafter, a driving method of the liquid crystal display device assembly in the embodiment will be described with reference to FIGS. In addition, FIG. 9 is a flowchart for demonstrating the drive method of the liquid crystal display device assembly in an Example.

In the embodiment, a control signal for controlling the light transmittance Lt of each pixel is supplied from the drive circuit to each pixel. More specifically, a control signal [R, G, B] that controls the light transmittance Lt of each of the sub-pixels [R, G, B] is supplied to each of the sub-pixels [R, G, B] constituting each pixel. B] is supplied from the drive circuit 90. Then, in each of the planar light source units 42, inputs input to the drive circuits 70, 80, 90 to drive all the pixels (subpixels [R, G, B]) constituting each display area unit 12. A control signal corresponding to an input signal having a value equal to the maximum value x _U-max in the display area unit that is the maximum value x _R , x _G , x _B of the signals [R, G, B]. Of the pixel (sub-pixel [R, G, B]) (light transmittance, display luminance at the first specified value Lt ₁ , second specified value y ₂ ) is obtained. Further, the luminance of the light source constituting the planar light source unit 42 corresponding to the display area unit 12 is controlled by the planar light source device control circuit 70 and the planar light source unit drive circuit 80. Specifically, for example, the light source luminance Y ₂ is obtained so that the display luminance y ₂ can be obtained when the light transmittance (aperture ratio) of the pixel or the sub-pixel is, for example, the light transmittance · the first specified value Lt _1. May be controlled (for example, decreased). That is, for example, the light source luminance Y ₂ of the planar light source unit 42 may be controlled for each image display frame so as to satisfy the following expression (1). Note that Y ₂ ≦ Y ₁ .

Y ₂ · Lt ₁ = Y ₁ · Lt ₂ (1)

[Step-100]
An input signal [R, G, B] and a clock signal CLK for one image display frame sent from a known display circuit such as a scan converter are input to the planar light source device control circuit 70 and the liquid crystal display device driving circuit 90. (See FIG. 5). Note that the input signals [R, G, B] are output signals from the image pickup tube, for example, when the input light quantity to the image pickup tube is y ′, and are output from, for example, a broadcasting station and the light transmittance Lt of the pixel. Is an input signal that is also input to the liquid crystal display device driving circuit 90 to control the above, and can be expressed by a function of the input light quantity y ′ to the 0.45th power. The values x _R , x _G , x _B of the input signals [R, G, B] for one image display frame input to the planar light source device control circuit 70 constitute the planar light source device control circuit 70. The data is temporarily stored in the storage device (memory) 72. Further, the values x _R , x _G , x _B of the input signals [R, G, B] for one image display frame inputted to the liquid crystal display device driving circuit 90 are also stored in the liquid crystal display device driving circuit 90. (Not shown) once stored.

[Step-110]
Next, in the arithmetic circuit 71 constituting the surface light source device control circuit 70, the value of the input signal [R, G, B] stored in the storage device 72 is read, and the (p, q) th [however, first , P = 1, q = 1] for driving the sub-pixels [R, G, B] in all the pixels constituting the (p, q) -th display region unit 12 The arithmetic circuit 71 obtains the display area unit input signal maximum value x _U-max that is the maximum value of the values x _R , x _G , x _B of the input signals [R, G, B]. Then, the in-display area unit / input signal maximum value x _U-max is stored in the storage device 72. This step is executed for all of m = 1, 2,..., M, n = 1, 2,..., N, that is, for M × N pixels.

For example, when x _R is a value corresponding to “110”, x _G is a value corresponding to “150”, and x _B is a value corresponding to “50”, x _U-max is “150”. Is a value corresponding to.

This operation is repeated from (p, q) = (1, 1) to (P, Q), and the display area unit internal input signal maximum value x _U-max in all the display area units 12 is stored in the storage device 72. Remember.

[Step-120]
Then, the control signal [R, G, B] corresponding to the input signal [R, G, B] having a value equal to the maximum value x _U-max in the display area unit is sub-pixel [R, G, B]. ] Corresponding to the display area unit 12 so that the brightness (light transmittance, display brightness at the first specified value Lt ₁ , second specified value y ₂ ) is obtained by the planar light source unit 42. The light source luminance Y ₂ of the planar light source unit 42 is increased or decreased under the control of the planar light source unit drive circuit 80. Specifically, the light source luminance Y ₂ may be controlled for each image display frame and for each planar light source unit so as to satisfy the following expression (1). More specifically, the luminance of the light source (light emitting element assembly 100) is controlled based on the equation (2) which is the light source luminance control function g (x _nol-max ), and the equation (1) is satisfied. The light source luminance Y ₂ may be controlled. A conceptual diagram of such control is shown in FIGS. 11 (A) and 11 (B). However, as will be described later, correction based on the influence of the other planar light source unit 42 is performed on the light source luminance Y ₂ as necessary. It should be noted that these relations regarding the control of the light source luminance Y ₂ , that is, the value of the control signal corresponding to the input signal having a value equal to the maximum value x _U-max in the display area unit and the input signal maximum value x _U-max . , The display luminance when assuming that such a control signal is supplied to the pixel (sub-pixel), the second specified value y ₂ , the light transmittance (aperture ratio) of each sub-pixel at this time [light transmittance / first 2 specified value Lt ₂ ], and a planar light source that provides display luminance and second specified value y ₂ when the light transmittance (aperture ratio) of each sub-pixel is set to light transmittance and first specified value Lt _1. The relationship of the brightness control parameters in the unit 42 may be obtained in advance and stored in the storage device 72 or the like.

Y ₂ · Lt ₁ = Y ₁ · Lt ₂ (1)
g (x _nol-max ) = a ₁ · (x _nol-max ) ^2.2 + a ₀ (2)

Here, input signals (input signals [R, G, B]) that are input to the liquid crystal display driving circuit 90 to drive the pixels (or the sub-pixels [R, G, B] constituting the pixels). ) _Is the maximum value x _max
x _nol-max ≡ x _U-max / x _max
And a ₁ and a ₀ are constants,
a ₁ + a ₀ = 1
0 <a ₀ <1, 0 <a ₁ <1
Can be expressed as For example,
a ₁ = 0.99
a ₀ = 0.01
And it is sufficient. The value x _R, x _G of the input signal [R, G, B], each x _B, and takes a value of 2 ⁸ steps, the value of x _max is a value corresponding to "255".

  By the way, in the planar light source device 40, for example, assuming brightness control of the planar light source unit 42 of (p, q) = (1, 1), other P × Q planar light source units. 42 may need to be taken into account. Since the influence of such a planar light source unit 42 from other planar light source units 42 is known in advance by the light emission profile of each planar light source unit 42, the difference can be calculated by back calculation, and as a result, the correction is Is possible. The basic form of calculation will be described below.

The luminance (light source luminance Y ₂ ) required for the P × Q planar light source units 42 based on the requirements of the equations (1) and (2) is represented by a matrix [L _PxQ ]. In addition, the luminance of a certain planar light source unit obtained when only a certain planar light source unit is driven and the other planar light source units are not driven is compared with P × Q planar light source units 42. Obtain in advance. Such luminance is represented by a matrix [L ′ _PxQ ]. Further, the correction coefficient is represented by a matrix [α _PxQ ]. Then, the relationship between these matrices can be expressed by the following equation (3-1). The correction coefficient matrix [α _PxQ ] can be obtained in advance.
[L _PxQ ] = [L ′ _PxQ ] · [α _PxQ ] (3-1)
Therefore, the matrix [L ′ _PxQ ] may be obtained from Expression (3-1). The matrix [L ′ _PxQ ] can be obtained from the inverse matrix operation. That is,
[L ′ _PxQ ] = [L _PxQ ] · [α _PxQ ] ⁻¹ (3-2)
Should be calculated. Then, the light source provided in each planar light source unit 42 may be controlled so that the luminance represented by the matrix [L ′ _PxQ ] is obtained. Specifically, the operation and processing are performed by the storage device ( The information (data table) stored in the (memory) 82 may be used. In the control of the light emitting element assembly 100, since the value of the matrix [L ′ _PxQ ] cannot take a negative value, it goes without saying that the calculation result needs to be kept in a positive region. Therefore, the solution of equation (3-2) may not be an exact solution but an approximate solution.

As described above, the matrix [L _PxQ ] obtained based on the values of the equations (1) and (2) obtained in the arithmetic circuit 71 constituting the surface light source device control circuit 70, and the correction coefficient matrix [α _PxQ ], As described above, a luminance matrix [L ′ _PxQ ] when it is assumed that the planar light source unit is driven alone is obtained. Further, based on the conversion table stored in the storage device 72, 0 to 0 is obtained. Convert to a corresponding integer (value of the pulse width modulation output signal) in the range of 255. In this way, in the arithmetic circuit 71 constituting the planar light source device control circuit 70, the value S _R of the pulse width modulation output signal for controlling the light emission time of the red light emitting diode 101R in the planar light source unit 42, the green light emitting diode 101G The value S _G of the pulse width modulation output signal for controlling the light emission time and the value S _B of the pulse width modulation output signal for controlling the light emission time of the blue light emitting diode 101B can be obtained.

[Step-130]
Next, the values S _R , S _G , and S _B of the pulse width modulation output signal obtained in the arithmetic circuit 71 constituting the surface light source device control circuit 70 are the surfaces provided corresponding to the surface light source unit 42. Is sent to the storage device 82 of the light source unit driving circuit 80 and stored in the storage device 82. The clock signal CLK is also sent to the planar light source unit drive circuit 80 (see FIG. 6).

[Step-140]
Based on the values S _R , S _G , and S _B of the pulse width modulation output signal, the on time t _R-ON and the off time t _{R-OFF of} the red light emitting diode 101R constituting the planar light source unit 42, the green light emitting diode. The arithmetic circuit 81 determines an _ON time t _G-ON and an OFF time t _{G-OFF of} 101G, and an ON time t _B-ON and an OFF time t _B-OFF of the blue light emitting diode 101B. still,
t _R-ON + t _R-OFF = t _G-ON + t _G-OFF = t _B-ON + t _B-OFF = constant value t _Const
It is. The duty ratio in driving based on pulse width modulation of the light emitting diode is
t _ON / (t _ON + t _OFF ) = t _ON / t _Const
Can be expressed as

The signals corresponding to the on times t _R-ON , t _G-ON , t _B-ON of the red light emitting diode 101R, the green light emitting diode 101G, and the blue light emitting diode 101B constituting the planar light source unit 42 are LED driving circuits. 83, and from the LED drive circuit 83, the switching elements 85R, 85G, 85B turn on the time t _R based on the signal values corresponding to the on times t _R-ON , t _G-ON , t _B-ON. Only _-ON , _{tG -ON} , and _{tB -ON} are turned on, and the LED driving current from the light emitting diode driving power supply 86 is caused to flow to each of the light emitting diodes 101R, 101G, and 101B. As a result, each of the light emitting diodes 101R, 101G, and 101B emits light for the on times t _R-ON , t _G-ON , and t _B-ON in one image display frame. Thus, each display area unit 12 is illuminated at a predetermined illuminance.

The states thus obtained are indicated by solid lines in FIGS. 10A and 10B, and FIG. 10A shows an input signal input to the liquid crystal display device driving circuit 90 to drive the sub-pixels. 10 is a diagram schematically showing a relationship between a value obtained by raising the value of x to the power of 2 (x′≡x ^2.2 ) and a duty ratio (= t _ON / t _Const ). FIG. It is a figure which shows typically the relationship between the value X of the control signal for controlling the light transmittance Lt, and the display brightness | luminance y.

[Step-150]
On the other hand, the values x _R , x _G , x _B of the input signals [R, G, B] input to the liquid crystal display device driving circuit 90 are sent to the timing controller 91, and the timing controller 91 receives the input signals A control signal [R, G, B] corresponding to the input signal [R, G, B] is supplied (output) to the sub-pixel [R, G, B]. The values X _R and X _{G of the} control signal [R, G, B] generated by the timing controller 91 of the liquid crystal display device driving circuit 90 and supplied from the liquid crystal display device driving circuit 90 to the sub-pixels [R, G, B]. , X _B and the values x _R , x _G , x _{B of} the input signals [R, G, B] are expressed by the following equations (4-1), (4-2), and (4-3): There is a relationship. However, _{b1_R} , _{b0_R} , _{b1_G} , _{b0_G} , _{b1_B} , _{b0_B} are constants. Further, since the light source luminance Y ₂ of the planar light source unit 42 is changed for each image display frame, the control signal [R, G, B] basically sets the value of the input signal [R, G, B] to 2. A value obtained by performing correction (compensation) based on a change in the light source luminance Y _{2 with} respect to the squared value. That is, in the embodiment, since the light source luminance Y ₂ changes for each image display frame, the control signal is obtained so that the display luminance and the second specified value y ₂ can be obtained at the light source luminance Y ₂ (≦ Y ₁ ). The values X _R , X _G , and X _B of [R, G, B] are determined and corrected (compensated) to control the light transmittance (aperture ratio) Lt of the pixel or sub-pixel. Here, the functions f _R , f _G , and f _B in the equations (4-1), (4-2), and (4-3) are functions obtained in advance for performing such correction (compensation). is there.

X _R = f _R (b 1 _—R · x _R ^2.2 + b 0 _—R ) (4-1)
X _G = f _G (b 1 _—G · x _G ^2.2 + b 0 _—G ) (4-2)
X _B = f _B (b 1 _—B · x _B ^2.2 + b 0 _—B ) (4-3)

  Thus, the image display operation in one image display frame is completed.

  As mentioned above, although this invention was demonstrated based on the preferable Example, this invention is not limited to these Examples. The configurations and structures of the transmissive color liquid crystal display device, the planar light source device, the planar light source unit, the liquid crystal display device assembly, and the drive circuit described in the embodiments are examples, and members, materials, and the like constituting these are also examples. This is an example, and can be changed as appropriate. In the embodiment, the light emitting device assembly 100 including the lens 102 and the cap 116 has been described. However, when the cap 116 functions sufficiently as the lens 102 and the lens 102 does not need to be provided separately, The cap 116 can be regarded as a lens, and the lens above the cap 116 can be omitted.

  Luminance compensation (correction) and temperature control of the planar light source unit may be performed by monitoring the temperature of the light emitting diode with a temperature sensor and feeding back the result to the planar light source unit drive circuit. In the embodiments, the description has been made on the assumption that the display area of the liquid crystal display device is divided into P × Q virtual display area units. However, in some cases, the transmissive liquid crystal display device has P × Q. You may have the structure divided | segmented into the actual display area unit.

1A and 1B are a schematic view of a planar light source unit constituting the planar light source device of Example 1 as viewed from above, and 3 constituting one light emitting element assembly group. It is a figure which shows typically the state of the light radiate | emitted from one light emitting element assembly. 2A and 2B are schematic views of a modification of the light emitting element assembly in the planar light source unit constituting the planar light source device of Example 1. FIG. FIGS. 3A and 3B are schematic views of the planar light source unit constituting the planar light source device of Example 3 as viewed from above. FIG. 4 is a schematic cross-sectional view of a light emitting diode. FIG. 5 is a conceptual diagram of a liquid crystal display device assembly including a color liquid crystal display device and a planar light source device suitable for use in the embodiment. FIG. 6 is a conceptual diagram of a portion of a drive circuit suitable for use in the embodiment. FIG. 7A is a diagram schematically showing the arrangement and arrangement state of light emitting element assemblies and the like in the surface light source device of the example, and FIG. 7B is a color liquid crystal display device of the example. FIG. 2 is a schematic partial cross-sectional view of a liquid crystal display device assembly including a planar light source device. FIG. 8 is a schematic partial cross-sectional view of a color liquid crystal display device. FIG. 9 is a flowchart for explaining a driving method of the liquid crystal display device assembly in the embodiment. FIG. 10A shows a value (x′≡x ^2.2 ) obtained by multiplying the value of the input signal inputted to the liquid crystal display driving circuit to drive the sub-pixel by the power of ^2.2 and the duty ratio (= t _ON / t _Const ) is a diagram schematically showing the relationship between the control signal value X for controlling the light transmittance of the sub-pixel and the display luminance y. FIG. FIG. (A) and (B) of FIG. 11 show the display luminance when assuming that a control signal corresponding to an input signal having a value equal to the input signal maximum value x _U-max is supplied to the pixel. as second predetermined value y ₂ is obtained by the planar light source unit, the light source luminance Y ₂ of the planar light source unit is the conceptual view for describing under the control of the planar light source unit drive circuit, a state of increasing or decreasing . FIGS. 12A and 12B are a schematic view of a red light emitting diode assembly and a green light emitting diode assembly constituting a conventional light emitting diode assembly group, respectively, and a red light emitting diode assembly. FIG. 3 is a diagram schematically showing a region of light emitted from a green light emitting diode assembly and a blue light emitting diode assembly and illuminating a light emitting surface of the planar light source device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Color liquid crystal display device, 11 ... Display area, 12 ... Display area unit, 13 ... Liquid crystal material, 20 ... Front panel, 21 ... 1st board | substrate, 22. ··· Color filter, 23 ... Overcoat layer, 24 ... Transparent first electrode (common electrode), 25 ... Alignment film, 26 ... Polarizing film, 30 ... Rear panel, 31 ..Second substrate 32 ... Switching element 34 ... Transparent second electrode 35 ... Alignment film 36 ... Polarization film 37 ... Insulating layer 40 ... Surface shape Light source device (backlight), 41 ... partition, 42 ... planar light source unit, 43, 43R, 43G, 43B ... photodiode (light sensor), 51 ... housing, 52A ... Bottom of housing, 52B ... side of housing, 53 ... outside Frame, 54 ... inner frame, 55A, 55B, 55C ... spacer, 56 ... guide member, 57 ... bracket member, 61 ... light diffusion plate, 62 ... diffusion sheet, 63 ..Prism sheet, 64... Polarization conversion sheet, 65 .. reflection sheet, 70... Planar light source device control circuit, 71... Arithmetic circuit, 72. ..Surface light source unit drive circuit, 81... Arithmetic circuit, 82... Storage device (memory), 83... LED drive circuit, 84 .. photodiode control circuit, 85R, 85G, 85B. Switching element, 86... Light emitting diode driving power source (constant current source), 90... Liquid crystal display device driving circuit, 91... Timing controller, 100, 100R, 100G, 100B. Light emitting element assembly, 101, 101R, 101G, 101B ... Light emitting diode, 102 ... Lens, 110 ... Light emitting layer, 111 ... Submount, 112 ... Heat sink, 113 ... Support member 114A, 114B ... gold wire, 115A, 115B ... external electrode, 116 ... cap, 117 ... space, 118 ... filler

Claims (7)

A light-emitting element assembly group composed of a plurality of light-emitting element assemblies each including a light-emitting element and a lens through which light emitted from the light-emitting element passes;
A display region composed of pixels arranged in a two-dimensional matrix by white light obtained by mixing light of a plurality of colors emitted from a plurality of light emitting element assemblies constituting a light emitting element assembly group A planar light source device for illuminating a transmissive liquid crystal display device having a back surface,
In each of the plurality of light emitting element assemblies constituting the light emitting element assembly group, each light emitting element is arranged so that the distribution of the amount of light emitted from each light emitting element assembly and passing through the light emitting surface of the planar light source device is substantially the same. A planar light source device, wherein a lens shape in an assembly is determined.   2. The planar light source device according to claim 1, wherein a lens shape in each light emitting element assembly is determined so that a radiation angle distribution of light emitted from the light emitting element assembly becomes a desired distribution. .   The lens shape is determined based on at least one lens characteristic selected from a lens characteristic group consisting of the inclination of the lens optical axis with respect to the light emitting element axis, the eccentricity of the lens optical axis with respect to the light emitting element axis, and the curvature of the lens surface. The planar light source device according to claim 1, wherein:   2. The planar light source device according to claim 1, wherein a lens shape of the light emitting element assembly is determined depending on an arrangement position of the light emitting element assembly in the planar light source device.   The planar light source device according to claim 1, wherein the light emitting surface of the planar light source device is formed of a light diffusing plate. It is composed of P × Q planar light source units corresponding to the P × Q display area units when assuming that the display area of the liquid crystal display device is divided into P × Q virtual display area units,
The light emission states of the P × Q planar light source units are individually controlled,
2. The planar light source device according to claim 1, wherein the light source provided in each planar light source unit includes one light emitting element assembly group. (A) a transmissive liquid crystal display device having a display region composed of pixels arranged in a two-dimensional matrix, and
(B) A light emitting element assembly group including a plurality of light emitting element assemblies each including a light emitting element and a lens through which light emitted from the light emitting element passes is provided as a light source. A planar light source device that illuminates the liquid crystal display device from the back side with white light obtained by mixing light of a plurality of kinds of colors emitted from a plurality of light emitting element assemblies that constitutes;
With
In each of the plurality of light emitting element assemblies constituting the light emitting element assembly group, each light emitting element is arranged so that the distribution of the amount of light emitted from each light emitting element assembly and passing through the light emitting surface of the planar light source device is substantially the same. A liquid crystal display device assembly, wherein a lens shape in the assembly is determined.

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