WO2012147594A1

WO2012147594A1 - Backlight system, display device, and backlight control method

Info

Publication number: WO2012147594A1
Application number: PCT/JP2012/060502
Authority: WO
Inventors: 内田　龍男; 鈴木　芳人; 川上　徹; 一雄関家; 真裕西澤; 石鍋　隆宏; 片桐　麦; 江原　克典; 佳拡橋本; 伊藤　康尚; 石井　裕
Original assignee: シャープ株式会社; 国立大学法人東北大学
Priority date: 2011-04-25
Filing date: 2012-04-18
Publication date: 2012-11-01

Abstract

In a light source unit (3) comprising a plurality of light emission points (R, G, B) which are arrayed in a first direction (X) and a second direction (Y) which are directions of the width and length of sub-pixels which have an elongated shape, the light discharge state varies in the first direction (X) and the second direction (Y) such that the light quantity distribution shapes of light beams which are collected by light collection units (5) and discharged from sub-pixels (1) depict an elongated shape similar to that of one sub-pixel.

Description

Backlight system, display device, and backlight control method

The present invention relates to a display device that performs full-color display without using a color filter while using a backlight as a light source for image display, and in particular, each of a plurality of sub-pixels constituting a pixel of the display device is different from the back side. The present invention relates to a backlight control method for collecting colored light, and a backlight system for realizing the control method.

Conventional liquid crystal display devices that perform full color display use red (R), green (G), and blue (B) color filters. Specifically, one pixel of the transmissive liquid crystal display element is divided into three sub-pixels, and a color filter of a color corresponding to the display color is attached to each sub-pixel. The backlight emits white light from the back surface of each sub-pixel. The transmittance when the white light is transmitted through each sub-pixel is controlled by a voltage signal applied to the liquid crystal cell of each sub-pixel.

However, since the color filter transmits light in the wavelength band corresponding to each RGB and absorbs other light, about 2/3 of the light is lost. That is, in the liquid crystal display device using the color filter, there is a problem that the light use efficiency is lowered.

Therefore, for example, Patent Document 1 listed below proposes a technique for improving the light utilization efficiency by arranging a microlens array on the backlight side of the liquid crystal panel and condensing light of each RGB color in the corresponding subpixel. Has been.

FIG. 18 is a cross-sectional view showing a schematic configuration of the image display device described in Patent Document 1. The image display device 51 includes a backlight source 52, a diffraction grating 53, a first microlens array 54, a liquid crystal panel 55, a second microlens array 56, and a diffusion plate 57 in this order. A substantially parallel white light W is emitted from the backlight source 52. The parallel light forms a small angle with the light exit surface 59 of the light guide plate. When the parallel light enters the diffraction grating 53, it is diffracted by the diffraction grating 53. Of the diffracted light diffracted by the diffraction grating 53, the first-order diffracted light is emitted in a direction substantially perpendicular to the diffraction grating 53. At this time, since light having different wavelengths has different diffraction angles, the first-order diffracted light is separated into red light R, green light G, and blue light B.

The first microlens array 54 is arranged such that one microlens 54a corresponds to a set of pixels 60 of the liquid crystal panel 55, that is, three adjacent subpixels. Therefore, the red light R, the green light G, and the blue light B emitted from the diffraction grating 53 in different optical axis directions are condensed by the microlens 54a on different sub-pixels in the set of pixels 60, respectively. . Therefore, by controlling on / off of these sub-pixels, transmission or blocking of the red light R, the green light G, and the blue light B can be controlled independently, and the image display device 51 performs color display. be able to.

Furthermore, the second microlens array 56 is arranged so that each microlens 56 a corresponds to the microlens 54 a of the first microlens array 54. Further, the distance L between the main plane of the first microlens array 54 and the main plane of the second microlens array 56 is equal to the focal length of the second microlens array 56. Therefore, the red light R, the green light G, and the blue light B that have passed through the pixel 60 have different optical axis directions, but the red light R, the green light G, and the blue light B pass through the micro lens 56a. The optical axes are aligned in parallel.

Thus, the second micro lens array 56 the red light R passing through the, the green light G and blue light B is diffused by the diffusion plate 57, as shown in FIG. 18, the directivity characteristics of the respective diffused light T _R , _T G, is _{T B} equal. The observer visually recognizes the image information by the light that has passed through the diffusion plate 57 disposed on the viewer side from the liquid crystal panel 55. Therefore, Patent Document 1 describes that color misregistration that occurs when an observer views the image display device 51 from different directions can be suppressed, and light use efficiency and viewing angle characteristics can be improved. .

Japanese Patent Publication “Japanese Patent Laid-Open No. 11-258604 (published September 24, 1999)”

However, in the configuration disclosed in Patent Document 1, the light spot formed on the diffusion plate 57 corresponding to each sub pixel after the light is condensed on each sub pixel has an elongated shape of the sub pixel. Therefore, there is a problem that high display quality cannot be obtained.

That is, in a general liquid crystal display device, since one pixel is constituted by three subpixels of each color of RGB, each subpixel has an elongated shape. FIG. 4 is an explanatory diagram schematically showing how the light emitted from the sub-pixels spreads. In the configuration in which the color filter of the color corresponding to the display color is attached to the sub-pixel, the shape of the elongated sub-pixel is observed as it is as shown in [1] of FIG.

On the other hand, in the configuration as shown in FIG. 18 in which no color filter is used, the shape of the light spot formed on the diffusion plate 57 corresponding to each sub-pixel is substantially circular. This is because, in an illumination system used for a backlight or the like, the way in which the light emitted from the light emitting portion spreads, that is, the irradiation angle distribution is isotropic (concentric). For this reason, even after the light condensed on each sub-pixel passes through the liquid crystal layer, the light spreads in an isotropic manner, so that the shape of the light spot on the diffusion plate 6 is substantially circular.

Then, in FIG. 18, when the distance between the liquid crystal panel 55 and the diffusion plate 57 is increased, the circular light spots overlap on the diffusion plate 57 as shown in [2] of FIG. The image information is mixed and the resolution is also lowered.

On the contrary, when the distance between the liquid crystal panel 55 and the diffusion plate 57 is reduced, as shown in [3] of FIG. 4, there is no overlap between the circular light spots, and thus no color mixing of the image information occurs. However, since a large dark portion is generated between the sub-pixels of the same color, the image quality is also deteriorated.

The present invention has been made in view of the above problems, and an object of the present invention is to use a backlight system capable of improving the display quality of a transmissive display device that does not use a color filter, and the backlight system. The object is to provide a high-quality display device.

In order to solve the above problems, the backlight system of the present invention
(1) One pixel is composed of a plurality of sub-pixels, each of the plurality of sub-pixels has an elongated shape having a different width and length, and a plurality of pixels including the one pixel are extended in the width direction. And a second direction which is an extension direction of the length, and the amount of light passing through each of the plurality of sub-pixels is modulated based on image information. A backlight system provided as a light source for a display device that displays image information,
(2) a light source unit including a plurality of light emitting points arranged two-dimensionally along the first direction and the second direction;
(3) a condensing unit that individually condenses the first light emitted from at least one of the plurality of light emitting points on the corresponding subpixel;
(4) The shape of the light quantity distribution on the plane perpendicular to the light traveling direction with respect to the light beam emitted from one of the sub-pixels while spreading after the first light is condensed on one of the sub-pixels. However, regardless of the number of condensing points collected on one of the sub-pixels, the light source unit emits light along the first direction so as to have an elongated shape similar to that of one of the sub-pixels. The emission state is different from the light emission state along the second direction.

According to the above configuration, a plurality of pixels are two-dimensionally arranged on the display unit that displays image information, and one pixel is composed of a plurality of sub-pixels. Each sub-pixel has a width and a length, and has an elongated shape extending in the second direction.

Note that the display colors of the plurality of sub-pixels constituting one pixel may be different from each other or the same color. When the display colors are different from each other, multicolor display can be performed. In the case of the same color, finer gradation expression can be provided by making the light transmittances of the plurality of sub-pixels different from each other.

The first light emitted from at least one of the plurality of light emitting points arranged in a two-dimensional manner is condensed on a plurality of subpixels for each subpixel by the light collecting unit. In each subpixel, the amount of light passing through the subpixel is modulated based on the image information.

Here, in the light source unit, the light emission state along the first direction in which the width of the sub-pixel is extended is different from the light emission state in the second direction in which the length of the sub-pixel is extended. . The light emission state includes the degree of spread of the light beam of the first light emitted from each of the plurality of light emitting points, or the interval between the plurality of light emitting points.

In the former case, the degree of spread of the light beam means the flatness of the shape of the light quantity distribution in the plane perpendicular to the light traveling direction. In the latter case, if the interval between the plurality of light emitting points changes, the degree of overlapping of the first light beams emitted from the adjacent light emitting points changes, and the condensing position in the corresponding subpixel also changes.

The light emission state in the first direction and the second direction in such a light source unit is set to a specific state corresponding to one of the sub-pixels. That is, the specific state means that the shape of the light amount distribution on a plane perpendicular to the light traveling direction is the same as that of one of the sub-pixels regardless of the number of light spots collected on one of the sub-pixels. It is a state of showing the shape.

The elongated shape of the light amount distribution is, for example, the shape of a light irradiation range (light spot) formed by a light beam emitted from one of the sub-pixels on a diffusion plate provided on the viewer side with respect to the display unit. This can be easily confirmed.

Explain the meaning of “regardless of the number of condensing points”. When the number of condensing points for one of the sub-pixels is one, the light beam emitted from one of the sub-pixels is a light beam that spreads from one condensing point. On the other hand, when there are a plurality of condensing points for one of the sub-pixels, the light beam emitted from one of the sub-pixels is composed of a plurality of light beams spreading from the plurality of condensing points. In short, the number of condensing points collected on one of the sub-pixels is arbitrary.

In a display device using such a backlight system as a light source, an observer visually recognizes a light beam emitted from one subpixel as a light beam having an elongated shape like one subpixel. Therefore, the display device can display high-quality image information to the same extent as when a color filter is provided for each sub-pixel without providing a color filter for each sub-pixel. In addition, when a plurality of sub-pixels constituting one pixel correspond to different display colors, the display device can display high-quality color image information.

In order to solve the above problems, the backlight control method of the present invention
(1) One pixel is composed of a plurality of sub-pixels, each of the plurality of sub-pixels has an elongated shape having a different width and length, and a plurality of pixels including the one pixel are extended in the width direction. Are modulated two-dimensionally along the first direction and the second direction, which is the extension direction of the length, and modulate the amount of light passing through each of the plurality of sub-pixels based on image information A control method of a backlight that irradiates the light with respect to a display device that displays image information,
(2) After the light is condensed on one of the sub-pixels, the shape of the light amount distribution on the surface perpendicular to the light traveling direction is about the luminous flux emitted from one of the sub-pixels while spreading. The optical system of the backlight is set so as to show an elongated shape similar to that of one of the sub-pixels regardless of the number of light spots condensed on one of the sub-pixels.

In the display device to which the above backlight control method is applied, the observer can visually recognize high-quality image information as described above.

Note that the optical system of the backlight includes a light source and an optical system that guides and collects light emitted from the light source to each of the plurality of sub-pixels.

A display device including any one of the backlight systems described above also belongs to the category of the present invention.

According to the present invention, a transmissive display device with high display quality can be provided without using a color filter.

Moreover, in order to solve the above problems, the display device of the present invention provides
(1) a light source that emits light with different display colors;
(2) One pixel is composed of a plurality of sub-pixels corresponding to the different display colors, each of the plurality of sub-pixels having an elongated shape having a different width and length, and a plurality of pixels including the one pixel Are two-dimensionally arranged along a first direction that is the extending direction of the width and a second direction that is the extending direction of the length, and the second light that passes through each of the plurality of sub-pixels. A display unit that displays the image information by modulating the amount of light based on the image information;
(3) a condensing unit that individually condenses the light emitted from the light source unit on the corresponding sub-pixels of the display color of the display unit;
(4) a diffusing plate that is disposed on the viewer side with respect to the display unit and diffuses the second light that has passed through the display unit;
(5) Passing through a condensing region of the condensing unit that collects part of the light emitted by the light source unit with respect to one of the sub-pixels, and corresponding to one of the sub-pixels, The shape of the light irradiation range formed on the surface of the diffusing plate does not depend on the number of light spots condensed on one of the sub-pixels, and exhibits the same elongated shape as that of one of the sub-pixels. The light source unit is characterized in that a light emission state along the first direction is different from a light emission state along the second direction.

According to the above configuration, a plurality of pixels are two-dimensionally arranged in the display unit that displays image information, and one pixel is configured by a plurality of sub-pixels corresponding to different display colors. Each sub-pixel has an elongated shape having a different width and length.

The light of a certain display color emitted from the light source unit is condensed by the condensing unit onto the sub pixel having the corresponding display color, and the amount of light passing through the sub pixel is modulated based on the image information. The

The light that has passed through the sub-pixel is projected onto a diffusion plate arranged on the viewer side.

Here, in the light source unit, the light emission state along the first direction in which the width of the sub-pixel is extended is different from the light emission state in the second direction in which the length of the sub-pixel is extended. . The light emission state refers to the degree of spread of the first light beam of a certain display color emitted from the light source unit or the interval between a plurality of emission points of light emitted from the light source unit for a certain display color. Contains.

In the former case, the degree of spread of the light beam means the flatness of the cross-sectional shape perpendicular to the traveling direction of the light beam. In the latter case, if the interval between the plurality of emission points is changed, the degree of overlapping of the first light beams emitted from the adjacent emission points is changed, and the condensing position in the corresponding sub-pixel is also changed.

The light emission state in the first direction and the second direction in such a light source unit is set to a specific state corresponding to one of the sub-pixels. That is, the specific state means that the shape of the light irradiation range formed on the surface of the diffusion plate is the same as that of one of the sub-pixels regardless of the number of light spots collected on one of the sub-pixels. It shows a state of showing an elongated shape.

Explain the meaning of “regardless of the number of light spots”. When the number of light spots focused on one of the sub-pixels is one, one light irradiation range is formed on the surface of the diffusion plate by the one light spot. Moreover, when the number of light spots is plural, one light irradiation range is formed on the surface of the diffusion plate by the plural light spots. In short, the number of light spots forming one light irradiation range is arbitrary.

Thus, the observer visually recognizes the shape of one light irradiation range formed on the surface of the diffusion plate as the light emission shape of one sub-pixel. Therefore, since the shape of the one light irradiation range is elongated like the shape of one sub-pixel, the observer has the same degree as when observing a display unit provided with a color filter in each sub-pixel. In addition, high-quality color image information can be visually recognized.

A combination of a configuration described in a certain claim and a configuration described in another claim is limited to a combination of the configuration described in the claim cited in the claim. However, as long as the object of the present invention can be achieved, combinations with configurations described in the claims not cited in the focused claims are possible.

In the backlight system, the display device, and the backlight control method of the present invention, the light from the light source is condensed on one of the sub-pixels, and then spreads with respect to the light beam emitted from one of the sub-pixels. The shape of the light amount distribution on the surface perpendicular to the traveling direction is characterized by showing an elongated shape similar to that of one of the sub-pixels, regardless of the number of condensing points that are condensed on one of the sub-pixels. .

Therefore, the present invention has the effect that even if a color filter is not provided for each sub-pixel, high-quality image information can be displayed to the same extent as when a color filter is provided for each sub-pixel.

It is a schematic block diagram which shows the backlight system of one Embodiment of this invention, and a display apparatus provided with the backlight system, and shows the arrangement | positioning relationship of each component along a 1st direction (RGB alignment direction). ing. It is a schematic block diagram which shows the said backlight system and a display apparatus, and has shown the arrangement | positioning relationship of each component along a 2nd direction (same color arrangement direction). It is a top view which shows the structure of 1 pixel. It is explanatory drawing which shows typically the spreading | diffusion condition of the light radiate | emitted from a sub pixel. It is a conceptual diagram which shows the definition of an effective light emission point. It is explanatory drawing which shows typically the appearance of the light beam before and behind passing through a sub pixel by enlarging a condensing part and a display panel in a 1st direction. It is explanatory drawing which shows typically the appearance of the light beam before and behind passing through a sub pixel by enlarging a condensing part and a display panel in a 2nd direction. It is a schematic block diagram which shows the backlight system of other embodiment of this invention, and a display apparatus provided with the backlight system, The arrangement | positioning relationship of each component along a 1st direction (RGB alignment direction) is shown. Show. It is a schematic block diagram which shows the said backlight system and a display apparatus, and has shown the arrangement | positioning relationship of each component along a 2nd direction (same color arrangement direction). FIG. 9 is an explanatory diagram schematically illustrating the appearance of light beams before and after passing through a sub-pixel by enlarging a light collecting unit and a display panel illustrated in FIG. 8 in a first direction X. It is explanatory drawing which shows typically the appearance of the light beam before and behind passing a sub pixel by enlarging the condensing part and display panel which are shown in FIG. 8 to a 2nd direction. It is the schematic which shows one structural example of the backlight system which concerns on other embodiment. It is explanatory drawing which shows the preferable setting conditions among the pitch of several light emission point of the same color, the pitch of several micro lens, and the pitch of the sub pixel of the same color. It is explanatory drawing which shows the other structural example of a light source part typically. It is explanatory drawing which shows the other structural example of a light source part typically. It is explanatory drawing which shows the other structural example of a light source part typically. It is a figure which shows the external appearance of a micro lens array typically, (c) has shown the cross section which follows the A line or B line of (a), or the C line of (c). 10 is a cross-sectional view illustrating a schematic configuration of an image display device described in Patent Literature 1. FIG. It is explanatory drawing which shows the other structural example of 1 pixel. It is explanatory drawing which shows the modification of explanatory drawing shown in FIG. It is explanatory drawing which shows the modification of explanatory drawing shown in FIG. It is explanatory drawing which shows the further another modification of explanatory drawing shown in FIG. It is explanatory drawing which shows the other modification of explanatory drawing shown in FIG.

[Outline of the Invention]
FIG. 1 is a schematic configuration diagram showing a backlight system according to an embodiment of the present invention and a display device including the backlight system, and shows an arrangement relationship of each component along a first direction. Reference numeral 2 denotes an arrangement relationship of each component along the second direction. FIG. 3 is a plan view showing the configuration of one pixel.

As shown in FIG. 1, when the sub-pixels corresponding to red (R), green (G), and blue (B) are arranged in the first direction, the first direction is referred to as an RGB arrangement direction. You can also Further, as shown in FIG. 2, when sub-pixels of the same color (for example, R) are arranged in the second direction, the second direction can also be referred to as the same color arrangement direction.

The backlight system of the present invention, the display device including the backlight system, and the backlight control method have the following preconditions and features in common. The display device is a transmissive display device that displays image information by modulating the amount of light passing through each of the plurality of sub-pixels arranged in the display unit based on the image information.

<Prerequisite configuration>
As shown in FIG. 3, one pixel 1 includes a plurality of sub-pixels (picture elements) 1a, 1b, 1c, and the like. Each of the sub-pixels 1a, 1b, and 1c has an elongated shape having different widths W1 and W2 as shown in FIGS. A plurality of pixels having the same configuration as the pixel 1 are two-dimensionally arranged in a first direction X that is an extension direction of the width W1 and a second direction Y that is an extension direction of the length W2. ing.

In the present embodiment, an example of a display device that performs full color display by assigning different display colors of red, green, and blue to each of the sub-pixels 1a, 1b, and 1c is shown. However, high-definition monochrome images may be displayed by condensing white light on all the sub-pixels 1a, 1b, and 1c and controlling the luminance of each sub-pixel 1a, 1b, and 1c.

As shown in FIG. 19, M sub-pixels having different display colors are arranged in the second direction Y, and combined with N sub-pixels having different display colors arranged in the first direction X, for a total of M × One pixel may be constituted by N sub-pixels. When the shape of one pixel is a square, since the shape of each sub-pixel is elongated along the second direction Y, M <N.

In the example shown in FIG. 19, one pixel includes six sub-pixels of six colors of red (R), green (G), blue (B), cyan (C), yellow (Y), and magenta (M). They are arranged in 2 rows and 3 columns.

Note that the display colors of the M × N sub-pixels constituting one pixel may be all different, or at least part or all may be the same color, and is not particularly limited.

<Features>
The light emitted from the light source unit 3 is condensed on one of the plurality of sub-pixels (for example, the sub-pixel 1a), and then the light beam emitted from the sub-pixel 1a while spreading is a surface perpendicular to the light traveling direction. The optical system of the backlight is set so that the shape of the light quantity distribution in FIG. 1 shows an elongated shape similar to that of the sub-pixel 1a regardless of the number of light spots condensed on the sub-pixel 1a.

The point that the shape of the light amount distribution described in the above <feature point> is an elongated shape is that the shape of the light spot (light irradiation range) formed on the surface of the diffusion plate 46 disposed on the viewer side of the display panel 4. This is reflected in the fact that becomes an elongated shape.

That is, as shown in FIG. 1, the width in the first direction X of the light spot formed on the surface of the diffusion plate 46 by the light beam emitted from the sub-pixel 1a is L (X), which is shown in FIG. Thus, the length of the same light spot in the second direction Y is L (Y). The magnitude relationship between L (X) and L (Y) is L (X) <L (Y), and the relational expression L (X) / L (Y) ≈W1 / W2 holds.

Thereby, when the observer observes the diffusion plate 46, as shown in [4] of FIG. 4, a high-quality display reflecting the elongated shape of each sub-pixel can be visually recognized. The display state shown in [4] in FIG. 4 is not inferior to the display state in the case where the color filter shown in [1] in FIG. Rather, since a color filter is not provided for each sub-pixel, light quantity loss due to the color filter can be avoided, resulting in a bright display state.

[Embodiment 1]
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in the embodiments of the present specification are not intended to limit the scope of the present invention to that unless otherwise specified. It is merely an illustrative example.

(Emission characteristics of the light source)
One form of setting in the optical system of the backlight described in <Feature Point> above may be referred to as an irradiation angle (a degree of light spread or an emission angle distribution) of a plurality of light emitting points arranged two-dimensionally in the light source unit 3. ) In the first direction X and the second direction Y. Thereby, in the light source part 3, the light emission state along the 1st direction X and the light emission state along the 2nd direction Y differ.

As an example, as shown in FIG. 1, the light source unit 3 includes a plurality of light emitting points R, G, and B. The light emitting point R is, for example, an LED (Light Emitting Diode) that emits red light, and the light emitting points G and B are LEDs that emit green light and blue light, respectively. However, it is possible to consider a display device that performs only monochrome display as described above, assuming that the light emitting points R, G, and B are all LEDs that emit white light.

Hereinafter, since the respective configurations relating to the light emitting points R, G, and B are the same for the three parties, the configuration relating to the light emitting point R will be described representatively, except for the case where the description relating to the light emitting points G, B is necessary.

The plurality of light emitting points R are two-dimensionally arranged along the first direction X and the second direction Y. The interval (arrangement interval or pitch) between the light emitting points R is P1 in the first direction X and P1 in the second direction Y.

As shown in FIGS. 1 and 2, the irradiation angle of light emitted from each of the plurality of light emitting points R is along the second direction Y from the irradiation angle φ (X) spreading along the first direction X. The spread irradiation angle φ (Y) is larger. Each of the light emitting points R has such emission characteristics.

Due to this emission characteristic, in the light source unit 3, the light emission state along the first direction X and the light emission state along the second direction Y are different. As a result, a display device that performs high-quality display without using a color filter can be realized.

In a display device that performs full-color display, the light source unit 3 has predetermined light emission points R (red), light emission points G (green), and light emission points B (blue) as a plurality of light emission points that emit different color lights. Are arranged two-dimensionally at a pitch of The interval (pitch) between the light emitting points of the same color is P1 in the first direction X and P1 in the second direction Y as described above.

In FIG. 1, the sub-pixels that display red, green, and blue in one pixel are arranged along the first direction X in the order of RBG, so that the light emitting points of the same color are adjacent to each other along the first direction X. The light emitting points R, B, and G of different colors are arranged along the first direction X so as not to be present.

In the second direction Y, since the sub-pixels of the same color are arranged, the light emitting points of the same color are arranged along the second direction Y.

In addition, since the arrangement of the colors of the light emitting points depends on the optical design of the condensing unit 5, as long as there is periodicity in order to facilitate the optical design of the condensing unit 5, in order of RGB or RBG, Other orders are also acceptable. In the second direction Y, a plurality of light emitting points that emit different colored lights may be arranged.

Also, the number of colors is not limited to three, and for example, four colors including yellow may be added, or other colors may be added. One pixel is divided into sub-pixels corresponding to the number of colors.

(Supplementary information on luminous points)
Here, the light emission point referred to in the present invention means an effective light emission point 100A as shown in FIG. FIG. 5 is a conceptual diagram showing the definition of the effective light emission point. The effective light emission point 100 </ b> A is defined as a virtual image of the light emission point 102 by the condenser lens system 101. In the case of the light source 100 without the condenser lens system 101, the effective light emission point 100A coincides with the light emission point 102.

The pitch P1 is a point interval between the effective light emitting points 100A.
As will be described later with reference to FIGS. 14 to 16 (variation examples of the light source unit), the number of light sources can be reduced by applying a light emitting device using a light source and a light guide instead of the light source unit 3. A significant cost reduction effect can be obtained. This is because many pseudo light sources can be created and taken out from spatially different positions. Each of the pseudo light sources at this time also corresponds to an effective light emission point.

(Construction of light condensing part)
The condensing part 5 which condenses the light which the light source part 3 radiate | emits on the display panel 4 can be comprised, for example using a micro lens array (MLA). The MLAs are arranged at substantially the same intervals for each of a plurality of (for example, three) sub-pixels constituting one pixel (however, detailed intervals will be described later in Embodiment 3). .

Note that the light source unit 3 and the light collecting unit 5 constitute a backlight system according to the present invention.

FIG. 17 is a diagram schematically showing the appearance of the MLA, and (c) shows a cross section along the A line or B line in (a) or the C line in (c). The MLA is an assembly of lenses whose surface shape or refractive index distribution is changed. An example of an assembly of lenses whose surface shape is changed is, for example, a fly in which microlenses are arranged in two orthogonal directions of a first direction X and a second direction Y, as shown in FIGS. Eye lens. In addition, as shown in FIGS. 17B and 17C, a lenticular lens in which microcylindrical lenses are arranged in one direction orthogonal to the longitudinal direction may be employed, or a fly-eye lens and a lenticular lens. A combination with may be adopted.

When attention is paid to one microlens surface constituting the MLA, light respectively emitted from a plurality of light emitting points enters one microlens surface at different principal ray angles. Since light incident at different principal ray angles is condensed at spatially different positions by one microlens surface, the light emitted from a plurality of light emitting points is spatially different after passing through the MLA. It will be focused on the position.

However, since a plurality of microlens surfaces correspond to condensing with respect to one subpixel, a plurality of light emitting points are involved in condensing with respect to one subpixel.

In FIGS. 1 and 2, only the path of light (red light) from the light emitting point R to the corresponding red sub-pixel is shown, and the paths of green light and blue light are omitted.

Here, when the arrangement position of a plurality of light emitting points, the lens pitch of the MLA, and the pixel pitch are applied to a certain relational expression, the light emitted from each light emitting point can be condensed on the corresponding subpixel (details). A detailed interval will be described later in Embodiment 3).

The condensing function of a fly-eye lens having a convex surface as shown in FIG. 1 is a method of deflecting the optical path according to the surface shape, and by utilizing the refractive index difference at the interface on the lens surface, The light path is deflected according to the law.

The surface shape of the imaging optical system is preferably designed so that the radius of curvature of the lens surface is 0.5 to 2 mm. The radius of curvature is determined by the distance from the fly-eye lens surface to the light transmission part (liquid crystal layer), the refractive index of the lens array, and the condensing range condition in the liquid crystal layer. Therefore, it is necessary to use a surface shape having an optimum curvature according to the light source size to be used, the liquid crystal panel, and the required thickness of the backlight portion. Further, the surface shape becomes a convex surface in order to have a light collecting action.

Here, in order to best perform the spatial separation of light from the plurality of light emitting points, the arrangement direction of the plurality of light emitting points may be as follows.

(A) When a fly-eye lens is used alone as the lens array, as shown in FIG. 17A, the arrangement direction of the plurality of light emitting points is two orthogonal directions (vertical and horizontal directions) (FIG. 17). (A direction and B direction shown in (a)).

(B) When a lenticular lens is used alone or in combination with a fly-eye lens as the lens array, as shown in FIG. 17B, the arrangement direction of the plurality of light emitting points is the longitudinal direction of the micro cylindrical lens (FIG. It is taken in a direction orthogonal to the C direction shown in 17 (b).

When forming an imaging optical system by arranging a plurality of microlens arrays along the light traveling direction, the curvature of the surface shape of each of the plurality of microlens arrays is compared to the case of using a single microlens array. Can be suppressed. By suppressing the curvature, the generation of stray light can be suppressed.

On the other hand, instead of the method of deflecting the optical path by the surface shape, a method of deflecting the optical path by the refractive index distribution may be adopted. In this method, the optical path is deflected by giving a distribution to the refractive index in the lens. That is, by changing the refractive index between the central portion and the peripheral portion of the lens, a gradient of the refractive index is given inside the lens, and light is deflected by this gradient of refractive index.

Also, in the method of deflecting the optical path by the refractive index distribution, the surface shape of the lens is flat. For this reason, it becomes possible to bond a polarizer, an optical film, etc. directly on a lens array, and space maintenance with them becomes easy.

(Configuration of display device)
In the display device 10, a plurality of pixels including the pixel 1 including the light source unit 3 that emits light in different display colors and the sub-pixels 1 a, 1 b, and 1 c corresponding to the different display colors are arranged in a first direction X. The display panel 4 arranged two-dimensionally in the second direction Y, and the light condensing part for individually condensing the light emitted from the light source part 3 on the sub-pixels 1a, 1b, and 1c of the corresponding display color. And 5. More specifically, the display device 10 is configured as a transmissive liquid crystal display device using a backlight.

The light source unit 3 and the light collecting unit 5 correspond to the backlight system of the present invention.

The display panel 4 includes, in order from the light incident side of the light source unit 3, a polarizer 41, a glass substrate 42 on which a TFT driving unit is formed, a liquid crystal layer 43, a glass substrate 44, and an analyzer 45. A diffusion plate (diffusion element) 46 is disposed on the viewer side of the display panel 4.

Although the LED array which is an array of point light sources is illustrated as the light source unit 3, the present invention is not limited to this, and any of a linear light source such as CCFL (Cold Cathode Fluorescent Lamp) or a surface light source may be adopted. it can. Further, as the point light source, an organic EL lamp in which the light emitting point 102 (FIG. 5) is filled with an organic EL light emitting unit may be used instead of the LED.

(Necessity of diffusion plate)
In the transmissive display device according to the present invention, the light from the light source is condensed on the sub-pixels constituting the pixel, so that the light that passes through the liquid crystal layer 43 and exits from the analyzer 45 is directed to the front. It is in a state of being condensed to some extent. For this reason, when the screen of this transmissive display device is observed at a different viewing angle (from an oblique direction), light does not reach much and it is difficult to see the display on the screen as compared with the case where the screen is observed from the front.

Therefore, in order to solve this problem, it is preferable to dispose the diffusion plate 46 on the exit surface of the analyzer 45. Further, when the diffusion plate 46 further has an incident angle independent diffusion characteristic, the light that has passed through each of the sub-pixels that spatially divide the transmissive display device by color has the same diffusion characteristic, so that the display quality is improved. Is more preferable. The incident angle-independent diffusion characteristic is a property that the diffusion intensity distribution when passing through the diffusion plate is constant regardless of the incident angle of the incident light to the diffusion plate.

(Like the light flux before and after passing through the sub-pixel)
FIG. 6 is an explanatory diagram schematically showing the appearance of the light flux before and after passing through the sub-pixels by enlarging the light collecting unit 5 and the display panel 4 in the first direction X. FIG. 7 is an explanatory diagram schematically showing the appearance of light beams before and after passing through the sub-pixels by enlarging the light collecting unit 5 and the display panel 4 in the second direction Y.

As shown in FIG. 6, let us consider a light beam included in a light beam that is emitted from the light emitting point R and collected on one corresponding sub-pixel. The maximum angle of the angle at which this light ray enters one of the sub-pixels in the plane including the normal direction of the plane including the first direction X and the second direction Y and the first direction X is defined as θa. . Note that the maximum angle θa can be said to be the maximum angle of the inclination angle of the light beam inclined in the first direction X with reference to the normal direction.

Further, as shown in FIG. 7, a light beam included in a light beam collected from the light emitting point R and focused on one corresponding sub-pixel is considered. The maximum angle of the angle at which this light ray enters one of the sub-pixels in a plane including the normal direction and the second direction Y is defined as θb. Note that the maximum angle θb can be said to be the maximum angle of the inclination angle of the light beam inclined in the second direction Y with respect to the normal direction.

Note that the plane including the first direction X and the second direction Y is synonymous with a plane in which a plurality of pixels are two-dimensionally arranged, and may be synonymous with a display plane. The normal of this surface is shown by broken lines in FIGS.

The above-mentioned maximum angle θa defines the extent of spreading of the luminous flux in the first direction X after the light emitted from the light emitting point R is collected on one corresponding sub-pixel. Similarly, the maximum angle θb defines the degree of spread of the light flux in the second direction Y.

In the backlight system of the present embodiment, with respect to the irradiation angle of the light emitting point R, the irradiation angle φ (X) that spreads along the first direction X is made smaller than the irradiation angle φ (Y) that spreads along the second direction Y. Thus, the maximum angle θa is smaller than the maximum angle θb.

Thus, the light source unit 3 and the light condensing unit 5 are designed so that the relationship θa <θb is established with respect to the maximum angle θa and the maximum angle θb. As a result, the luminous flux emitted from one sub-pixel can have an elongated light amount distribution similar to the shape of one of the sub-pixels.

(Significance of preventing color mixing)
The light emitted from the light emitting point R has the elongated light amount distribution as described above, and is condensed on one corresponding sub-pixel and then reaches the diffusion plate 46 to reflect the light amount distribution. A light irradiation range, that is, a light spot is formed on the diffusion plate 46.

When the display light whose luminance is modulated by each sub-pixel of the liquid crystal layer 43 is mixed in the diffusion plate 46, the observer of the display panel 4 recognizes the mixed image information. That is, the observer cannot see a clear image and recognizes a blurred image.

Here, in the liquid crystal layer 43 disposed between the MLA and the diffusion plate 46, the traveling direction of light cannot be deflected. In addition, the diffuser plate 46 cannot diffuse the position of the light beam only by diffusing the angle of the light beam that has reached.

For these reasons, it is necessary to control the light angle distribution after passing through the MLA in order to prevent color mixing of the image information with the diffusion plate 46. Here, the parameter that most affects the light beam angle distribution after passing through the MLA is the light beam output angle distribution in the light source unit 3.

Hereinafter, the light emission angle distribution will be described in more detail.

(Color mixing prevention condition-first direction)
In FIG. 6, when the distance from the liquid crystal layer 43 to the diffusion plate 46 is h, the spreading width in the first direction X (hereinafter referred to as the first diffusion element) when the light beam that has passed through one sub-pixel reaches the diffusion plate 46. La (referred to as a reach width) is expressed by the following equation using the distance h and the maximum angle θa.

La = 2 × h × tan θa (Formula 1)
Here, as shown in FIGS. 1 and 2, when the pixel pitch is P0 in both the first direction X and the second direction Y, each subpixel corresponding to RGB in the first direction X (RGB alignment direction). The width of is P0 / 3.

Therefore, when the display device 10 is designed under the condition that the first diffusion element arrival width La and the width (P0 / 3) of one subpixel satisfy the following (Formula 2), the subpixels adjacent to each other corresponding to RGB Therefore, the observer can visually recognize clear image information.

La <P0 / 3 (Formula 2)
From (Expression 1) and (Expression 2), the following (Expression 3) is derived.

2 × h × tan θa <P0 / 3 (Formula 3)
Furthermore, (Formula 3) is transformed into the following (Formula 4).

θa <arctan {P0 / (6 × h)} (Formula 4)
That is, if the maximum angle θa in the first direction X of the light emitted from each light emitting point can satisfy the inequality condition shown in (Expression 4), the subpixels in the first direction X (RGB alignment direction) Color mixing can be prevented.

(Color mixing prevention condition-second direction)
On the other hand, as shown in FIG. 7, when the light beam that has passed through one sub-pixel reaches the diffusion plate 46, the spread width in the second direction Y (hereinafter referred to as the second diffusion element arrival width) Lb is the above distance. Using h and the maximum angle θb, it is expressed by the following equation.

Lb = 2 × h × tan θb (Formula 5)
In the case of FIG. 7, when the pixel pitch is P0, only the subpixels of the same color are arranged in the second direction Y (same color arrangement direction), so the length of each subpixel is P0. .

Therefore, when the display device 10 is designed under the condition that the second diffusion element arrival width Lb and the length (P0) of one subpixel satisfy the following (Equation 6), the display information of adjacent subpixels of the same color is displayed. Since no overlap occurs, the observer can visually recognize clear image information.

Lb <P0 (Formula 6)
From (Expression 5) and (Expression 6), the following (Expression 7) is derived.

2 × h × tan θb <P0 (Formula 7)
Further, (Equation 7) is transformed into (Equation 8) below.

θb <arctan {P0 / (2 × h)} (Formula 8)
In other words, if the maximum angle θb in the second direction Y of the light emitted from each light emitting point can satisfy the inequality condition shown in (Expression 8) above, it is adjacent along the second direction Y (same color arrangement direction). It is possible to prevent display information of matching sub-pixels of the same color from overlapping. In addition, when sub-pixels of different colors are arrayed along the second direction Y, it is possible to prevent color mixing between the sub-pixels in the second direction Y.

When comparing the inequality conditions of the maximum angles θa and θb, θb is about three times wider. This is because, in the display device 10 shown in FIGS. 1 and 2, one pixel is configured with three types of subpixels in the first direction X and one type of subpixel is configured in the second direction Y. This is because the shape of one subpixel is vertically long.

Assuming that θa = θb≈arctan {P0 / (2 × h)}, in the second direction Y (same color arrangement direction), display information is not overlapped or mixed between pixels, but the first direction X In (RGB alignment direction), the display colors of the sub-pixels are mixed. That is, the state shown in [2] of FIG. 4 occurs.

When θa = θb≈arctan {P0 / (6 × h)}, no color mixture occurs in the first direction X, but a large dark region occurs between pixels in the second direction Y. That is, the state shown in [3] of FIG. 4 occurs.

Thus, in a color filterless system using a condensing unit such as MLA, the irradiation angle of the light source unit is made anisotropic, that is, the irradiation angle is changed between the first direction X and the second direction Y. By making it different, it becomes possible to bring the display quality close to that of a color filter type display device.

The maximum angle θa in the first direction X and the maximum angle θb in the second direction Y preferably satisfy (Equation 4) and (Equation 8) simultaneously. Also,
θa≈arctan {P0 / (6 × h)} (Formula 9)
θb≈arctan {P0 / (2 × h)} (Formula 10)
4 can be satisfied at the same time, the state shown in [4] of FIG. 4 occurs, preventing color mixing between the sub-pixels in the first direction X (RGB alignment direction), and display information of adjacent sub-pixels of the same color. Since no overlap occurs, the observer can visually recognize clearer image information.

(Universal condition 1 to prevent color mixing)
As a condition for imparting universality to (Equation 9) and (Equation 10), it is more preferable that the maximum angle θb in the second direction Y and the maximum angle θa in the first direction X satisfy the relationship of the following equation.

M × tan θb≈N × tan θa (Formula 11)
Here, N is the number of sub-pixels constituting one pixel arranged in the first direction X within one pixel. M is the number of sub-pixels arranged in the second direction Y within the one pixel, and is an integer of 1 or more. There is a relationship of M <N between M and N. In the example of FIGS. 1 and 2, N = 3 and M = 1, respectively, and in the example of FIG. 19, N = 3 and M = 2.

As described above, the display colors of the M × N sub-pixels constituting one pixel may be all different, or at least part or all may be the same color, and is not particularly limited. .

Hereinafter, the derivation of (Equation 11) will be described in more detail with reference to FIG. 20 and FIG.

In FIG. 20, when the distance from the liquid crystal layer 43 to the diffusion plate 46 is h, the spreading width in the first direction X when the light beam that has passed through one sub-pixel reaches the diffusion plate 46 (hereinafter referred to as the first diffusion element). La (referred to as an arrival width) is expressed by the above-described equation 1 using the distance h and the maximum angle θa.

La = 2 × h × tan θa (Formula 1)
Here, as shown in FIGS. 20 and 21, when the pixel pitch is P0 in both the first direction X and the second direction Y, the width of each sub-pixel in the first direction X (RGB alignment direction) is P0. / N.

Therefore, when the display device 10 is designed under the condition that the first diffusion element arrival width La and the width (P0 / N) of one subpixel satisfy the following (formula 12), the state shown in [4] of FIG. And the display colors of the adjacent sub-pixels corresponding to RGB do not cause color mixing, so that the observer can view clearer image information.

La≈P0 / N (Formula 12)
The following (Expression 13) is derived from (Expression 1) and (Expression 12).

2 × h × tan θa≈P0 / N (Formula 13)
Furthermore, (Formula 13) is transformed into the following (Formula 14).

2 × h × N × tan θa≈P0 (Formula 14)
On the other hand, as shown in FIG. 21, the spread width in the second direction Y (hereinafter referred to as the second diffusion element arrival width) Lb when the light beam that has passed through one sub-pixel reaches the diffusion plate 46 is the above distance. Using h and the maximum angle θb, it is expressed by Equation 5 above.

Lb = 2 × h × tan θb (Formula 5)
In the case of FIG. 21, when the pixel pitch is P0, the length of each sub-pixel in the second direction Y (same color arrangement direction) is P0 / M.

Therefore, when the display device 10 is designed under the condition that the second diffusion element arrival width Lb and the length (P0 / M) of one subpixel satisfy the following (Equation 15), the display device 10 is shown in [4] in FIG. Since the state is generated and the display information of the adjacent sub-pixels of the same color does not overlap, the observer can view clearer image information.

Lb≈P0 / M (Formula 15)
From (Expression 5) and (Expression 15), the following (Expression 16) is derived.

2 × h × tan θb≈P0 / M (Formula 16)
Further, (Equation 13) is transformed into (Equation 17) below.

2 × h × M × tan θb≈P0 (Expression 17)
Here, since the pixel pitch in both the first direction X and the second direction Y is equal to P0, (Equation 18) holds.

2 × h × M × tan θb≈2 × h × N × tan θa (Formula 18)
Further, (Equation 18) is transformed into (Equation 11) shown below.
M × tan θb≈N × tan θa (Formula 11)
In the examples of FIGS. 20 and 21, N = 4 and M = 2, respectively.

(Universal condition 2 to prevent color mixing)
Further, with reference to FIGS. 22 and 23, the derivation of the universal condition for preventing color mixture when the vertical / horizontal size ratio of one pixel is not 1: 1 and the vertical / horizontal size ratio of one pixel is Pa: Pb. explain in detail.

Assuming that the distance from the liquid crystal layer 43 to the diffusion plate 46 is h, the first diffusion element arrival width La is expressed by the above formula 1 using the distance h and the maximum angle θa.

La = 2 × h × tan θa (Formula 1)
Here, as shown in FIG. 22, when the pixel pitch is Pa in the first direction X, the width of each sub-pixel in the first direction X (RGB alignment direction) is Pa / N.

Therefore, when the display device 10 is designed under the condition that the first diffusion element arrival width La and the width (Pa / N) of one subpixel satisfy the following (formula 19), the state shown in [4] of FIG. And the display colors of the adjacent sub-pixels corresponding to RGB do not cause color mixing, so that the observer can view clearer image information.

La≈Pa / N (Formula 19)
The following (Expression 20) is derived from (Expression 1) and (Expression 19).

2 × h × tan θa≈Pa / N (Formula 20)
Furthermore, (Equation 20) is transformed into (Equation 21) below.

2 × h × N × tan θa≈Pa (Formula 21)
On the other hand, as shown in FIG. 23, the second diffusion element reach width Lb is expressed by the above-described Expression 5 using the distance h and the maximum angle θb.

Lb = 2 × h × tan θb (Formula 5)
In the case of FIG. 23, when the pixel pitch is Pb, the width of each sub-pixel in the second direction Y (same color arrangement direction) is Pb / M.

Therefore, when the display device 10 is designed under the condition that the second diffusion element arrival width Lb and the width (Pb / M) of one subpixel satisfy the following (formula 22), the state shown in [4] of FIG. And the display information of adjacent sub-pixels of the same color does not overlap, so that the observer can view clearer image information.

Lb≈Pb / M (Formula 22)
From (Expression 5) and (Expression 22), the following (Expression 23) is derived.

2 × h × tan θb≈Pb / M (Formula 23)
Further, (Equation 23) is transformed into (Equation 24) below.

2 × h × M × tan θb≈Pb (Equation 24)
Here, with respect to the first direction X and the second direction Y, the pixel pitch is Pa and Pb, and (Expression 25) holds from (Expression 21) and (Expression 24).

Pa / Pb≈ (2 × h × N × tan θa) / (2 × h × M × tan θb) (Formula 25)
Further, (Equation 25) is transformed into the following (Equation 26).

(M / Pb) × tan θb≈ (N / Pa) × tan θa (Formula 26)
Thus, as a universal condition for preventing color mixture when the vertical / horizontal size ratio of one pixel is Pa: Pb, the maximum angle θb in the second direction Y and the maximum angle θa in the first direction X are the above (formula 26). It is preferable to satisfy the relationship.

(Effect of this embodiment)
According to the setting of the light beam emission angle distribution in the light source unit 3 described in the present embodiment, each light emitted from the light emitting points RGB passes through the MLA and is irradiated into each sub pixel corresponding to RGB of the display panel 4. It is possible to

This makes it possible to perform full color display without using a color filter, and it is possible to improve the light utilization efficiency (about 3 times) corresponding to the amount of light absorbed by the color filter. Therefore, in the case of performing display with the same luminance as the conventional one, the power consumption required for the light source of the display device can theoretically be reduced to about 1/3.

In addition, the emission angles in the first direction X (RGB arrangement direction) and the second direction Y (same color arrangement direction) are made different so that the emission angle distribution has anisotropy, thereby corresponding to each sub-pixel. The shape of the light irradiation range formed on the diffusing plate 46 can be made substantially similar to the current color filter type liquid crystal display. As a result, the resolution is comparable to that of the current liquid crystal display.

Furthermore, in this embodiment, when attention is paid to the pitch of the light emitting points of the same color among the light emitting points R, G, B, the pitch in the first direction X and the pitch in the second direction Y are equal to each other. . For this reason, the number of light emitting points involved in the light collection of one subpixel is greater in the second direction Y than in the first direction X. Specifically, in the case of FIG. 1, light emitted from two or three light emitting points R is collected on one subpixel corresponding to R, whereas in the case of FIG. Light emitted from three to five light emitting points R is collected on one subpixel.

An increase in the number of light emitting points involved in condensing light onto one sub-pixel can be expected to average out the individual difference variation of the light emitting points and to further reduce luminance unevenness and color unevenness. Alternatively, if the pitch of the light emitting points in the second direction Y can be increased to the extent that the effect equivalent to the effect of averaging the individual differences obtained in the first direction X can be maintained, the second direction Y can be expanded. The number of light emitting points to be arranged can be reduced. As a result, an effect of cost reduction of the display device can be expected.

When a fly-eye lens is used as the MLA, the pitch of each lens constituting the fly-eye lens is 2 if the pitches of the same color light emitting points in both the first direction X and the second direction Y are equal to each other. The two directions X and Y are preferably equal to each other. Thereby, when the vertical / horizontal size ratio of the pixels is 1: 1, the condensing points are easily gathered at one point. Note that setting the vertical / horizontal size ratio of pixels to 1: 1 is common in almost all types of image display devices (LCD, plasma display, organic EL display, etc.).

[Embodiment 2]
Another embodiment of the present invention will be described with reference to the drawings. For convenience of explanation, the same reference numerals are given to the same components as those explained in the previous embodiment, and duplicate explanations are omitted.

FIG. 8 is a schematic configuration diagram showing a backlight system according to another embodiment of the present invention and a display device including the backlight system, and each component along the first direction (RGB alignment direction). The arrangement relationship is shown. FIG. 9 is a schematic configuration diagram showing the backlight system and the display device, and shows an arrangement relationship of each component along the second direction (same color arrangement direction).

(Differences from Embodiment 1)
The backlight system of the present embodiment shown in FIGS. 8 and 9 is different from the first embodiment in the following two points.
(1) Light emitting point arrangement interval in the second direction Y (same color arrangement direction) (2) The irradiation angle of each light emitting point in the light source unit 3 ′ will be described in more detail below.

Regarding the difference (1), in the light source unit 3 ′, if the light emission state along the first direction X is different from the light emission state along the second direction Y, the light emission point R is The pitch along the second direction Y (FIG. 9) is narrower than the pitch along the first direction X (FIG. 8). As an example, the pitch along the second direction Y is set to half the pitch P1 along the first direction X, that is, (P1) / 2. The pitch P1 along the first direction X is the same value as in the first embodiment.

Therefore, when the light emitted from the light emitting points R arranged along the first direction X is condensed on the liquid crystal layer 43 after passing through the MLA as in the first embodiment, one light is emitted to one corresponding sub-pixel. A condensing point is formed. On the other hand, the light emitted from the light emitting points R arranged along the second direction Y forms a plurality (two in FIG. 9) of condensing points in one corresponding sub pixel.

Regarding the difference (2), in the present embodiment, the irradiation angle φ (X) spreading along the first direction X and the second direction Y are related to the irradiation angle of the light emitted from each of the plurality of light emitting points. The irradiation angle φ (Y) that spreads out is equal. Therefore, the way in which the light beam spreads from the liquid crystal layer 43 to the diffusion plate 46 is equal in the first direction X and the second direction Y.

(Like the light flux before and after passing through the sub-pixel)
FIG. 10 is an explanatory diagram schematically showing the appearance of light beams before and after passing through the sub-pixels by enlarging the light collecting unit 5 and the display panel 4 in the first direction X. Moreover, FIG. 11 is explanatory drawing which shows typically the appearance of the light beam before and behind passing a sub pixel by enlarging the condensing part 5 and the display panel 4 to a 2nd direction.

Here, with respect to the first direction X, the definition of the maximum angle θa that is incident on one of the sub-pixels, and the definition of the maximum angle θb that is incident on one of the sub-pixels with respect to the second direction Y, Is as described in the first embodiment.

In the backlight system of the present embodiment, with respect to the irradiation angle of the light emitting point R, the irradiation angle φ (X) extending along the first direction X is equal to the irradiation angle φ (Y) extending along the second direction Y. As a result, the maximum angle θa and the maximum angle θb are equal.

As described above, the relationship θa = θb holds for the maximum angle θa and the maximum angle θb, while the pitch of the light emitting points along the second direction Y is 1 of the pitch of the light emitting points along the first direction X. / M (m is a natural number), so that m light condensing points are formed along the longitudinal direction (second direction Y) of one subpixel. 5 can be designed. As a result, the total luminous flux emitted from one subpixel can have an elongated light amount distribution, similar to the shape of one of the subpixels.

(Color mixing prevention condition-first direction)
In FIG. 10, when the distance from the liquid crystal layer 43 to the diffusion plate 46 is h, the condition for preventing the color mixture between the sub-pixels in the first direction X (RGB alignment direction) is the same as that in the first embodiment (Formula 4). This is as described above.

(Color mixing prevention condition-second direction)
On the other hand, in FIG. 11, the maximum angle θb and the maximum angle θa are equal, but the condensing points in the liquid crystal layer 43 are not confined to one point, but are condensing in a plurality of places. The diffusion element arrival width Lb in the same color arrangement direction is expressed by the following equation.

Lb = α + 2 × h × tan θb = α + 2 × h × tan θa = α + La (Formula 27)
Here, α is the length of the passage region when the light emitted from the light source unit 3 ′ passes through the liquid crystal layer 43. In other words, the length of the passing region means an interval between the condensing positions at both ends among the plurality of condensing positions arranged in the second direction Y within one subpixel.

That is, the influence of the maximum angle θb (= θa) occurs in the diffusion element arrival width Lb in the second direction Y shown in FIG. On the other hand, since the arrangement interval of the light emission points of the same color in the first direction X is different from the arrangement interval of the light emission points of the same color in the second direction Y, the diffusion element arrival width Lb has a concentration in the liquid crystal layer 43. The effect of the light region is also added.

In other words, even when the maximum angles in the first direction X and the second direction Y are equal, the arrangement intervals of the same color light emitting points in the first direction X and the second direction Y are made different, so that the same as in the first embodiment An effect can be obtained.

Here, in FIG. 11, the condition for preventing color mixture between adjacent sub-pixels of the same color in the second direction Y (same color arrangement direction) is the same as (Formula 6) of the first embodiment.

Lb <P0 (Formula 6)
The following (Expression 28) is derived from (Expression 6) and (Expression 27).

α + 2 × h × tan θa <P0 (Formula 28)
Further, (Equation 28) is transformed into the following (Equation 29).

α <P0-2 × h × tan θa (Formula 29)
That is, even in the case of the second embodiment, if the length α of the passage region satisfies the inequality condition shown in (Expression 29), the same color adjacent in the second direction Y (same color arrangement direction). It is possible to prevent the display information of the sub-pixels from overlapping. In addition, when sub-pixels of different colors are arrayed along the second direction Y, it is possible to prevent color mixing between the sub-pixels in the second direction Y.

Thereby, also in the case of Embodiment 2, in the color filterless system using MLA, similarly to Embodiment 1, in the light source part 3 ′, the light emission state along the first direction X and the second direction Y By making the light emission state along the same, display quality equivalent to that of the color filter type display device can be realized.

In addition, it is preferable that the maximum angle θa in the first direction X and the length α of the passage region satisfy (Equation 4) and (Equation 29) at the same time. Also,
θa≈arctan {P0 / (6 × h)} (Formula 9)
α ≒ P0-2 × h × tanθa (Formula 30)
4 can be satisfied at the same time, the state shown in [4] of FIG. 4 occurs. That is, color mixing between sub-pixels in the first direction X (RGB alignment direction) is prevented, and display information of adjacent sub-pixels of the same color does not overlap, so that an observer can visually recognize clearer image information. Is possible.

(Universal conditions for preventing color mixing)
As a condition for imparting universality to (Equation 9) and (Equation 30), the length α of the passing region and the maximum angle θa in the first direction X (RGB alignment direction) satisfy the relationship of the following equation: It is more preferable.

α≈ {(NM) / M} × 2 × h × tan θa (Formula 31)
Here, N is the number of sub-pixels constituting one pixel arranged in the first direction X within one pixel. M is the number of sub-pixels arranged in the second direction Y within the one pixel, and is an integer of 1 or more. There is a relationship of M <N between M and N. In the examples of FIGS. 8 and 9, N = 3 and M = 1, respectively.

Hereinafter, the derivation of (Equation 31) will be described in more detail with reference to FIGS. 11 and 20.

In FIG. 20, when the distance from the liquid crystal layer 43 to the diffusion plate 46 is h, the spreading width in the first direction X when the light beam that has passed through one sub-pixel reaches the diffusion plate 46 (hereinafter referred to as the first diffusion element). As described above, La is referred to as the following equation using the distance h and the maximum angle θa.

La = 2 × h × tan θa (Formula 1)
Here, as shown in FIGS. 11 and 20, when the pixel pitch is P0 in both the first direction X and the second direction Y, the width of each sub-pixel in the first direction X (RGB alignment direction) is P0. / N.

Therefore, as described above, when the display device 10 is designed under the condition that the first diffusion element arrival width La and the width (P0 / N) of one subpixel satisfy the following (formula 12), FIG. 4] occurs. That is, since the display colors of adjacent sub-pixels corresponding to RGB do not cause color mixing, the observer can view clearer image information.

2 × h × N × tan θa≈P0 (Formula 14)
On the other hand, in FIG. 11, the maximum angle θb and the maximum angle θa are equal, but the condensing points in the liquid crystal layer 43 are not confined to one point, but are condensing in a plurality of places. The diffusion element arrival width Lb in the same color arrangement direction is expressed by the following equation.

Lb = α + 2 × h × tan θb = α + 2 × h × tan θa = α + La (Formula 27)
In the case of FIG. 11, when the pixel pitch is P0, the width of each sub-pixel in the second direction Y (same color arrangement direction) is P0 / M.

Therefore, when the display device 10 is designed under the condition that the second diffusion element arrival width Lb and the width (P0 / M) of one subpixel satisfy the following (Formula 15), the state shown in [4] in FIG. Occurs. That is, since the display information of adjacent sub-pixels of the same color does not overlap, the observer can view clearer image information.

Lb≈P0 / M (Formula 15)
The following (Expression 32) is derived from (Expression 15) and (Expression 27).

α + 2 × h × tan θa≈P0 / M (Formula 32)
Further, (Expression 32) is transformed into (Expression 33) below.

M × (α + 2 × h × tan θa) ≈P0 (Formula 33)
Here, since the pixel pitch in both the first direction X and the second direction Y is equal to P0, (Expression 34) is established from (Expression 14) and (Expression 33).

2 × h × N × tan θa≈M × (α + 2 × h × tan θa) (Formula 34)
Further, (Expression 34) is transformed into (Expression 35) below.

M × α≈ (NM) × 2 × h × tan θa (Formula 35)
Further, (Expression 35) is transformed into (Expression 31) shown below.
α≈ {(NM) / M} × 2 × h × tan θa (Formula 31)
In the examples of FIGS. 11 and 20, N = 4 and M = 1, respectively.

(Effect of this embodiment)
As described above, according to the setting of the pitch of the light emitting points in the light source unit 3 ′, each light emitted from the light emitting points RGB passes through the MLA and then corresponds to the RGB of the display panel 4 as in the first embodiment. Each of the sub-pixels can be irradiated.

This makes it possible to perform full color display without using a color filter, and it is possible to improve the light utilization efficiency (about 3 times) corresponding to the amount of light absorbed by the color filter. In addition, it corresponds to each sub pixel by making each light emitting point pitch different in the first direction X (RGB alignment direction) and the second direction Y (same color alignment direction) and making the light emission state anisotropic. Thus, the shape of the light irradiation range formed on the diffusion plate 46 can be made almost similar to that of the current color filter type liquid crystal display. As a result, the resolution is comparable to that of the current liquid crystal display.

Furthermore, in this embodiment, the irradiation angle of each light emitting point in the first direction X and the second direction Y is equal, and the pitch of the same color light emitting points is narrower in the second direction Y (same color arrangement direction). For this reason, the number of light emitting points involved in condensing one subpixel of the liquid crystal layer 43 is larger in the number in the second direction Y than in the first direction X.

An increase in the number of light emitting points involved in condensing light onto one sub-pixel can be expected to average out the individual difference variation of the light emitting points and to further reduce luminance unevenness and color unevenness.

[Embodiment 3]
Still another embodiment of the present invention will be described with reference to the drawings. For convenience of explanation, the same reference numerals are given to the same components as those explained in the previous embodiment, and duplicate explanations are omitted.

In the present embodiment, with respect to the display devices 10 and 20, a preferable relationship and a preferable setting between the pitch of the light emitting points and the pitch of the plurality of microlenses constituting the MLA will be described in detail.

(Configuration in which multiple light beams overlap one subpixel)
FIG. 12 is a schematic diagram illustrating one configuration example of the backlight system according to the present embodiment. In this example, as the

light source units

3 and 3 ′, an array of a plurality of light emitting points R, G, and B that emit different color lights is used. The light emitting points R, G, and B are arranged in order of RGB colors from the right side to the left side in FIG.

Further, as the light condensing unit 5 constituting the imaging optical system, an MLA having an imaging magnification (1 / n) in which a plurality of microlenses 5A are two-dimensionally arranged is used.

The pixel pitch in the first direction X is P as in the first and second embodiments, and the pitch P1 between the light emitting points of the same color is P1≈n × P (Expression 37)
And the pitch P2 between the microlenses 5A is P2≈ (n / (n + 1)) × P (Equation 38)
And

Thus, for example, as shown in FIG. 12, the distance b from the MLA to the pixel of the liquid crystal layer 43 is set to b = ((n + 1) / n) × f (Equation 39) according to the focal length f of the MLA.
And the principal ray path length a from one light emitting point to the MLA is a = n × b (formula 40)
Then a, b and f are
(1 / a) + (1 / b) = (1 / f)
Therefore, the light from each light emitting point R, G, B can be condensed on each subpixel corresponding to RGB. In other words, a real image 1 / n times as large as one light emitting point can be formed on one corresponding sub-pixel.

In addition, how to derive the above (formula 37) and (formula 38) will be described later.

In one subpixel, image formation by light beams from a plurality of light emitting points that emit colored light corresponding to the color of the subpixel overlap each other, whereby a light spot is irradiated to the one subpixel.

As a result, spatial uniformity of the light beams emitted from a plurality of light emitting points is realized, luminance unevenness and color unevenness between areas in the display screen are effectively reduced, and higher image quality can be displayed.

In FIG. 12, only the light (R light) path to the sub-pixel corresponding to the light emitting point R is shown, and the G light and B light paths are not shown.

(Optical principle that achieves both overlap of multiple light beams and color separation)
Condensing the light from these light emitting points R, G, and B onto each subpixel corresponding to RGB (color separation), and overlapping the light from a plurality of light emitting points with the same color onto the same subpixel; The principle of the optical system that achieves both is mathematically explained with reference to FIG.

FIG. 13 is an explanatory diagram showing preferable setting conditions among a pitch of a plurality of light emission points of the same color, a pitch of a plurality of microlenses, and a pitch of subpixels of the same color.

In FIG. 13, only the principal ray path passing through the center of the microlens 5A among the light (R light) from the light emitting point R to the corresponding sub-pixel is illustrated, and the paths of the G light and the B light are illustrated. Omitted. Further, the refraction phenomenon due to the difference in refractive index at the interface of the microlens 5A was also excluded.

Here, the positions of the light emitting points R adjacent along the first direction X (RGB alignment direction) in FIG. 13 are denoted by L1 and L2, respectively, and similarly the centers of the microlenses 5A adjacent along the first direction X. Are represented by M1 and M2, and the positions of sub-pixels adjacent to each other along the first direction X corresponding to R are represented by S1 and S2.

First, in order to condense light from one light emitting point R on each of the subpixels S1 and S2, it is necessary that ΔL1S1S2 and ΔL1M1M2 have a similar relationship from FIG. To satisfy this, the following equation must hold.
Line segment M1M2 / Line segment L1M1 = Line segment S1S2 / Line segment L1S1
Transforming the above equation,
Line segment M1M2 = Line segment L1M1 × Line segment S1S2 / Line segment L1S1
It becomes.

Here, the line segment L1M1 = a = n × b, the line segment S1S2 = P (pixel pitch), and the line segment L1S1 = a + b = (n + 1) × b.
The line segment M1M2, that is, the lens pitch P2 of the MLA is
P2 = (n / (n + 1)) × P
This equation is derived.

In consideration of the refraction phenomenon due to the difference in refractive index at the interface of the microlens 5A, P2 is
P2≈ (n / (n + 1)) × P
(Expression 38) is derived.

Therefore, when the lens pitch P2 of the MLA is substantially equal to (n / (n + 1)) × P, the light from the light emitting point R can be condensed on each of the subpixels adjacent along the first direction X. .

Next, in order to condense light from a plurality of light sources of the same color (here, light from two adjacent light emitting points R) onto one sub-pixel corresponding to R, from FIG. 13, ΔL1L2S1 ΔM1M2S1 needs to be similar to each other. In order to satisfy this, the following formula must be established.
Line segment L1L2 / Line segment L1S1 = Line segment M1M2 / Line segment M1S1
Transforming the above equation,
Line segment L1L2 = Line segment L1S1 × Line segment M1M2 / Line segment M1S1
It becomes.

Here, since the line segment L1S1 = a + b = (n + 1) × b and the line segment M1S1 are b, the line segment L1L2, That is, the pitch P1 between the light emitting points of the same color is
P1 = n × P
Is calculated.

Similarly to P2, considering the refraction phenomenon due to the difference in refractive index at the interface of the micro lens 5A, P1 is
P1≈n × P
Therefore, the above (Equation 37) is derived.

Therefore, when the pitch P1 between the light emitting points of the same color is substantially equal to n × P, the light from the light emitting points of the same color adjacent along the first direction X (here, the light from the two light emitting points R) corresponds to R. The light can be condensed on one sub-pixel.

From these two results, the pitch P1 between the light emitting points of the same color is equal to or approximately equal to n × P, and the lens pitch P2 of the MLA is equal to or approximately equal to (n / (n + 1)) × P. Thus, it can be seen that the overlap of the plurality of light fluxes and the color separation can be made compatible. That is, the light from one light emitting point R is condensed on adjacent subpixels corresponding to R, and at the same time, the light from a plurality of light emitting points R is overlaid on one subpixel corresponding to R. It can wrap and collect light. This is the same when G or B is substituted for R.

The above description based on FIG. 13 is the same color emission points (for example, emission point R) arranged along the first direction X (RGB alignment direction) shown in FIG. 1 and the second direction Y (same color alignment direction) shown in FIG. ) Can be applied as it is.

On the other hand, in the case of light emission points of the same color arranged along the second direction Y (same color arrangement direction) shown in FIG. 9, another light emission point is provided between L1 and L2 indicating each light emission point R in FIG. The same explanation can be made assuming L3 indicating R.

Here, since the heights of the plurality of light emitting points are all the same, L3 always exists on the line segment from L1 to L2. From FIG. 13, since a similar relationship is established between ΔL1L2M2 and ΔS1S2M2, the light emitted from L3 existing on the line segment from L1 to L2 is on the line segment from S1 to S2. Be sure to collect light. Here, on the line segment from S1 to S2 corresponding to the pixel pitch P, it may be considered that only one subpixel corresponding to one color (R) exists as shown in FIG. Therefore, the R light emitted from L3 is also condensed in the one sub-pixel. Thereby, a plurality of (for example, two) condensing points are formed in one sub-pixel.

(Effect of this embodiment)
While satisfying the effects of the first and second embodiments, even when a light source such as an LED having a very large individual difference is used as the light emitting point, the individual difference variation of the light source light can be averaged. As a result, it is possible to provide a backlight system that can reduce luminance unevenness and color unevenness.

[Supplementary explanation common to Embodiments 1 to 3]
(Maximum angle limit)
The maximum angles θa and θb described with reference to FIGS. 6, 7, 10 and 11 are more preferably within 40 °. When the irradiation angle from the

light source units

3 and 3 ′ is increased, the incident angle of the light beam incident on the MLA with respect to the optical axis direction of the MLA is increased. In this case, the aberration including the field curvature is so large that it cannot be ignored.

In order to eliminate this aberration, a correction method using an optical system in which a plurality of lenses are combined is generally used, but it is not realistic from the viewpoint of manufacturing cost. Although it is possible to correct the aberration by making the lens aspherical, the improvement effect is limited when there is only one lens interface. Therefore, the maximum angles θa and θb are preferably 40 degrees or less.

Since the maximum angle θa is set smaller than the maximum angle θb, the maximum angle θa naturally becomes 40 degrees or less if the condition that the maximum angle θb is 40 degrees or less is satisfied.

Further, in order to collect light on each sub-pixel of the liquid crystal layer 43 using a spherical lens without making each lens of MLA aspherical, it is more preferable that the maximum angles θa and θb are within 30 °.

(About using color filters)
As shown in FIG. 1, what is important in the configuration in which a display device performs full color display without providing a color filter is that each subpixel that is a light-transmitting portion corresponds to a light emission corresponding to each subpixel. That is, only light emitted from points R, G, and B passes. In this state, by applying a voltage based on image information through a driving element corresponding to each sub-pixel, a color filter-less display device can be realized ideally.

However, in reality, due to manufacturing variations, optical components cannot be manufactured as designed, or optical components cannot be assembled, or optical components that are slightly out of design must be manufactured in consideration of manufacturing costs. Due to such problems, it may be difficult to focus only the corresponding light on the sub-pixels forming the pixel array with the liquid crystal layer.

In that case, in the worst case, the display quality may be degraded. In order to avoid such a situation, the present invention does not prohibit the provision of a color filter layer. However, when a color filter layer is used, the transmittance is about 90% even at a wavelength at which light is transmitted, and it is difficult to avoid light loss.

(Measures against external light of diffusion elements)
Furthermore, in order to improve the display quality, it is possible to take measures to suppress “backscattering with respect to external light” generated in the diffusion plate 46 disposed on the surface of the display panel 4.

As a function of the diffusing plate 46, the light irradiated from the back side of the display panel 4 is emitted as diffused light to the viewer side, while the light irradiated to the diffusing plate 46 from the viewer side is transmitted to the display panel 4 side. While diffusing as light, it is also diffused as reflected light on the observer side. This reflection action is called backscattering with respect to external light. When this reflected diffused light is observed together with the normal light for image display transmitted through the display panel 4, the image floats white and the image quality is degraded.

As a method of suppressing backscattering, there is a method of disposing functional films, for example, circularly polarizing plates, above and below the diffusion plate 46. A circularly polarizing plate is a polarizing plate that combines a polarizer and a quarter-wave plate. Specifically, from the light source side, the (first) polarizer 41, the glass substrate 42 on which the TFT driving unit is formed, the liquid crystal layer 43, the glass substrate 44, the analyzer 45, and the first quarter-wave plate , A diffusion plate 46, a second quarter-wave plate, and a second polarizer. The absorption axes of the polarizer 41 and the analyzer 45 are orthogonal to each other, and the absorption axes of the analyzer 45 and the second polarizer are parallel to each other. Further, the slow axes of the first quarter-wave plate and the second quarter-wave plate are arranged so as to be orthogonal to each other, and the absorption axis of the analyzer 45 and the first quarter-wavelength. Each slow axis of the plate is arranged to be inclined 45 degrees.

(Modification of light source)
Instead of the

light source units

3 and 3 ′, a light emitting device using a light source and a light guide can be applied.

The light source used in the present invention requires a plurality of light sources that emit light having different principal wavelengths. Such a light source may be any one of an LED light source, a laser light source, and an organic EL light source, or may be a light emitting device including the light source and a light guide.

In the present invention, when a light emitting device including a light source and a light guide as shown in FIGS. 14 to 16 is used, a significant cost reduction effect of reducing the number of light sources is achieved. The light emitting device will be described in detail below.

As shown in FIG. 14, the light emitting device 311 includes a light source 312 (R light source, G light source, B light source) and a light guide 313, and introduces light emitted from the light source 312 into the light guide 313. The light is emitted from a plurality of emission parts (tip parts). This emission part can be regarded as a pseudo light source.

For example, as shown in FIG. 14, each light of a set of RGB light sources 312 is divided into three backlight units (light guides 313) and guided. Each backlight unit (light guide 313) forms a pseudo light source 314, which is an R ′ light source, a G ′ light source, and a B ′ light source, and condenses light from each light source 314 on each sub-pixel by MLA. As a result, the same effects as those of the light emitting points R, G, and B in FIG.

Further, a white light source may be used as the light source. When using a white light source, it is desirable to emit RGB light in a spatially or angularly different state. As a method of emitting RGB light in a spatially different state, there is a light emitting device using a white light source 321 and a light guide 323 incorporating a dichroic filter 322 that reflects RGB light, respectively, as shown in FIG. The dichroic filter 322 is a filter that reflects only light in a specific wavelength range and transmits light in the remaining wavelength range. By spatially disposing dichroic filters 322 that respectively reflect R, G, and B light, the R, G, and B light can be extracted from different positions.

Further, as a light source, there is a method using a white light source, a light guide, and a diffraction grating as shown in FIG. In this method, the light emitted from the white light source 331 is guided into the light guide 332, and the substantially parallel white light is extracted from the light guide 332 with uniform brightness in the surface. When this parallel light enters the diffraction grating 333, it is diffracted by the diffraction grating 333. Of the diffracted light diffracted by the diffraction grating 333, the first-order diffracted light is emitted in a direction substantially perpendicular to the diffraction grating 333. At this time, since light having different wavelengths has different diffraction angles, the first-order diffracted light is separated into R, G, and B light.

As the white light source 331 in FIG. 16, a white LED (such as a combination of blue LED + YG fluorescence or a combination of blue LED + GR fluorescence), a multi-color LED (a diode chip that emits a plurality of different main wavelengths is mounted in one LED). LED) and white organic EL can be used.

Also, a linear light source such as CCFL or EEFL (external electrode fluorescent tube: External Electrofluorescent Lamp) that emits RGB colors may be used as the light source.

(Local dimming drive)
In addition, in order to cope with the reduction in power consumption by local dimming drive, a means for controlling the light quantity of each light source unit is displayed with the light source area in which light sources emitting each color are collected one by one as a minimum unit unit. It can also be provided in the apparatus. If local dimming driving is applied to this embodiment, it is expected that the power consumption can be further reduced to about ½.

As described above, the backlight system according to the present invention includes the light source unit 3 and the light collecting unit 5, and the light source unit 3 has a first direction X that is an extending direction of the width of the sub-pixel having an elongated shape, A plurality of light emitting points R, G, and B arranged two-dimensionally along a second direction Y that is an extension direction of the length of the sub-pixel, and the light collecting unit 5 includes a plurality of light emitting points. The light emitted from at least one of R, G, and B is individually condensed on the corresponding sub-pixel of the display unit 4. Regarding the luminous flux emitted from one of the sub-pixels, the shape of the light amount distribution on the surface perpendicular to the light traveling direction is not dependent on the number of condensing points that are collected on one of the sub-pixels. In the light source unit 3, the light emission state along the first direction X and the light emission state along the second direction Y are different so as to show an elongated shape similar to one.

This makes it possible to improve the display quality of a transmissive display device that does not use a color filter.

In the backlight system of the present invention, each of the plurality of light emitting points emits light such that the irradiation angle extending along the second direction is larger than the irradiation angle extending along the first direction. Features.

According to the above configuration, each of the plurality of light emitting points has anisotropy in the extent of the emitted light, that is, the irradiation angle. The anisotropy is an emission characteristic that the irradiation angle that spreads along the second direction is larger than the irradiation angle that spreads along the first direction.

Due to this emission characteristic, the light emitted from each of the plurality of light emitting points is condensed on one of the sub-pixels, and then spreads as a light beam having a light amount distribution of a desired shape. As described above, the desired shape is an elongated shape similar to one of the sub-pixels.

Therefore, a display device using the backlight system having the above configuration as a light source displays high-quality image information as if a color filter is provided for each sub-pixel, without providing a color filter for each sub-pixel. can do.

In the backlight system of the present invention, the light rays contained in the light beam condensed on one of the sub-pixels are in the normal direction of the surface including the first direction and the second direction, and the first direction. The maximum angle θa of the incident angle on one of the sub-pixels in the plane that includes the light beam is such that the light beam included in the luminous flux is within the plane that includes the normal direction and the second direction. It is characterized by being smaller than the maximum angle θb of the incident angle.

In the above configuration, the irradiation angle of each of the plurality of light emitting points has a correlation with the angle of incidence on one of the sub-pixels. That is, with respect to the first direction with a relatively small irradiation angle, the angle incident on one of the sub-pixels is also relatively small, and with respect to the second direction with a relatively large irradiation angle, one of the sub-pixels. The optical relationship among the light source unit, the condensing unit, and the sub-pixels is set so that the angle at which the light enters is relatively large.

The maximum angle θa is the maximum incident angle of light incident on one of the sub-pixels obliquely along the first direction. After the light is condensed on one of the sub-pixels, It is also an angle that defines the degree of spreading of the spreading light beam in the first direction.

Similarly, the maximum angle θb is the maximum incident angle of light incident on one of the subpixels obliquely along the second direction, but after the light is condensed on one of the subpixels. It is also an angle that defines the degree of spreading of the spreading light flux in the second direction.

In this way, by designing the light source unit and the condensing unit so that the relationship θa <θb is established with respect to the maximum angle θa and the maximum angle θb, the subpixel Similarly to the one shape, a light amount distribution having an elongated shape can be provided.

In the backlight system of the present invention,
(1) Among the plurality of sub-pixels constituting the one pixel, the number of sub-pixels arranged in the first direction within the one pixel is N,
(2) Among the plurality of sub-pixels, the number of sub-pixels arranged in the second direction within the one pixel is an integer M equal to or greater than 1,
(3) Furthermore, when the pitch in the first direction of the plurality of pixels is Pa and the pitch in the second direction is Pb,
(4) A light beam included in a light beam condensed on one of the sub-pixels, and the first direction is defined with reference to a normal direction of the display surface defined by the first direction and the second direction. A light ray having a maximum angle θa of the inclination angle of the light ray inclined in one direction;
(5) With respect to the light beam having the maximum angle θb of the light beam inclined in the second direction,
(6) It is characterized by satisfying (M / Pb) × tan θb≈ (N / Pa) × tan θa.

In the above configuration, N sub-pixels are arranged in the first pixel along the first direction. On the other hand, within the one pixel, M sub-pixels are arranged along the second direction. However, since M is an integer of 1 or more, when M = 1, it means that the sub-pixels are not arranged in the second direction within the one pixel.

Note that the display colors of the M × N sub-pixels constituting one pixel may be all different, or at least part or all may be the same color, and is not particularly limited. In addition, regarding the ratio between the pitch Pa in the first direction and the pitch Pb in the second direction of the plurality of pixels, and also regarding the magnitude relationship between the number of sub-pixels M and N, the shape of the sub-pixel There is no particular limitation as long as the condition of being elongated along two directions is satisfied.

As described above, after being condensed on one of the sub-pixels, the maximum angle θa that defines the degree of spread of the luminous flux in the first direction, and the maximum angle θb that defines the degree of spread of the luminous flux in the second direction, By satisfying (M / Pb) × tan θb≈ (N / Pa) × tan θa, it is possible to prevent light beams adjacent along the first direction from overlapping in the first direction, and along the second direction. Adjacent light beams can also be prevented from overlapping in the second direction. As a result, display quality can be further improved.

In the backlight system of the present invention, the maximum angle θb is 40 degrees or less.

In the above configuration, when the maximum angle θb exceeds 40 degrees, the incident angle with respect to the optical axis direction of the light converging portion increases. In this case, the aberration including the field curvature is so large that it cannot be ignored.

In order to eliminate this aberration, a correction method using an optical system in which a plurality of lenses are combined is generally used, but it is not realistic from the viewpoint of manufacturing cost. Although it is possible to correct the aberration by making the lens aspherical, the improvement effect is limited when there is only one lens interface. For these reasons, the maximum angle θb is preferably 40 degrees or less.

On the other hand, since the maximum angle θa is set smaller than the maximum angle θb in the present invention, if the condition that the maximum angle θb is 40 degrees or less is satisfied, the maximum angle θa is also 40 degrees or less.

In order to condense the light emitted from the light source unit on the sub-pixels using a spherical lens without using an aspheric lens for the condensing unit, the maximum angle θb is more preferably 30 degrees or less. .

The light emitting points in the backlight system of the present invention are two-dimensionally arranged such that the arrangement interval along the second direction is closer than the arrangement interval along the first direction. It is characterized by being.

According to the above configuration, as described above, “the light traveling direction with respect to the light flux that is emitted from one of the sub-pixels while spreading after the first light is collected on one of the sub-pixels”. It is assumed that the shape of the light amount distribution on the plane perpendicular to the above shows the same elongated shape as that of one of the sub-pixels regardless of the number of condensing points collected on one of the sub-pixels. As one mode for embodying the premise, the arrangement interval of the plurality of light emitting points is denser in the second direction than in the first direction.

Thereby, the light emitted from each of the plurality of light emitting points corresponding to one of the sub-pixels of the plurality of light emitting points is incident on the condensing unit as a light beam having the same spread, and the light is emitted in the same state. Focused on one of the sub-pixels. That is, a plurality of condensing points are formed in one of the sub-pixels, and a plurality of light beams spread from one of the sub-pixels.

At this time, the adjacent intervals of the plurality of light beams are denser in the second direction than the first direction, similarly to the arrangement interval of the plurality of light emitting points. For example, when a diffusion plate is arranged on the viewer side of the display unit, many light spots are arranged on the surface of the diffusion plate along the second direction from the first direction.

As a result, the plurality of light beams emitted from one of the sub-pixels can have a desired amount of light distribution in total. As described above, the desired shape is an elongated shape similar to one of the sub-pixels.

In the backlight system of the present invention, a plurality of light beams that have passed through the light condensing unit are collected with respect to one of the sub-pixels, and a condensing position of the plurality of light beams in one of the sub-pixels is It is preferable to arrange along the second direction.

As described above, by setting an optical system including the light source unit and the condensing unit so that a plurality of condensing positions are arranged in a line along the second direction in one of the sub-pixels, A plurality of light beams emitted from one can appropriately have a light amount distribution having the desired shape.

In the backlight system of the present invention, the maximum angle of the angle at which a light beam, which is included in the light beam condensed on one of the sub-pixels and has a spread in the first direction, is incident on one of the sub-pixels. θa is characterized in that a light ray included in the light flux and having a spread in the second direction is equal to a maximum angle θb of an incident angle on one of the sub-pixels.

According to the above configuration, there is no anisotropy in the condensing state of one light beam incident on one of the sub-pixels. That is, the intensity distribution of the cross section of the light beam collected through the condensing region with respect to one of the sub-pixels, that is, the cross section perpendicular to the traveling direction thereof is isotropic.

Accordingly, a light beam having a circular cross section corresponding to one of the sub-pixels can be arranged densely or in a large number along the second direction. Similar light quantity distribution can be obtained appropriately.

In the backlight system of the present invention,
(1) The condensing unit is configured by a microlens array,
(2) Among the plurality of pixels, at least the pitch of the pixels arranged in the first direction is P,
(3) The interval between the plurality of light emitting points arranged along the first direction is P1,
(4) The imaging magnification of the light condensing part is (1 / n),
(5) When the pitch of the microlenses adjacent in the first direction constituting the microlens array is P2,
(6) P1≈n × P and P2≈ (n / (n + 1)) × P.

According to the above configuration, for each of the plurality of sub-pixels adjacent in the first direction, the light emitted from one of the plurality of light emitting points is spatially separated and the plurality of adjacent pixels in the first direction. Condensing light onto one subpixel in a state where the light emitted from the light emitting points overlap each other can be achieved.

In addition, even if it is a case where a some light emission point consists of the combination of the light emission point which emits the light of a several kind of color, said effect can be obtained for every color.

As a result, spatial uniformity of the light beams emitted from a plurality of light emitting points is realized, so that uneven brightness in the display screen is effectively reduced. Further, in the configuration corresponding to the color display, the color unevenness is further reduced effectively. Therefore, display with higher image quality is possible.

In the display device of the present invention,
(1) The plurality of light emitting points are two-dimensionally arranged such that the arrangement interval along the second direction is denser than the arrangement interval along the first direction,
(2) The maximum angle θa of the angle at which a light beam, which is included in the light beam condensed on one of the sub-pixels and spreads in the first direction, enters one of the sub-pixels, and the light beam Included in the second direction, and the maximum angle θb of the angles at which the light rays having the spread in the second direction are incident on one of the sub-pixels are equal to each other,
(3) The number of the plurality of sub-pixels constituting the one pixel arranged in the first direction is N,
(4) The number arranged in the second direction is an integer M of 1 or more, and M <N.
(5) Furthermore, it is assumed that the pitch in the first direction and the pitch in the second direction of the plurality of pixels are equal to each other,
(6) In one of the sub-pixels, an interval between condensing positions adjacent to each other along the second direction of the plurality of light beams is α,
(7) If the distance between the display unit and the diffusion plate is h,
(8) It is characterized by satisfying α≈ {(NM) / M} × 2 × h × tan θa.

Suppose that M <N for the magnitude relationship between the number of sub-pixels M and N. This is because the shape of the sub-pixel is set to be elongated along the second direction, and the pitch in the first direction and the pitch in the second direction of the plurality of pixels are equal to each other. This is because the ratio is set to 1: 1.

The plurality of light emitting points are two-dimensionally arranged so that the arrangement interval along the second direction is denser than the arrangement interval along the first direction. A plurality of condensing points are formed along the second direction. At this time, since the maximum angle θa and the maximum angle θb are equal to each other, each of the plurality of light beams incident on one sub-pixel has an isotropic spread.

In such a configuration, α≈ {(N−M) / M} × 2 × h × tan θa holds, so that adjacent light beams along the first direction can be prevented from overlapping in the first direction. A plurality of condensing points arranged along the second direction are formed so as to be appropriately within the area of each sub-pixel. As a result, display quality can be further improved.

In the display device of the present invention, the maximum angle θa is 40 degrees or less.

According to the above configuration, as described above, it is possible to suppress the occurrence of aberration including curvature of field in the light condensing unit.

The display device of the present invention includes a functional film that suppresses backscattering of the diffuser plate with respect to outside light.

In the above configuration, the diffuser plate emits the light emitted from the display unit to the viewer side as diffused light, and diffuses and transmits the external light applied to the diffuser plate from the viewer side to the display unit side. At the same time, part of the external light is reflected as diffused light on the viewer side. This action of reflecting a part of the external light is called backscattering with respect to the external light. When the reflected diffused light is observed together with the display light transmitted through the display unit based on the image information, the image floats white and the image quality is deteriorated.

Therefore, by providing the above functional film, it is possible to suppress backscattering, so that the display quality can be further improved.

(Supplement of the present invention)
The following configuration can also be employed as the display device according to the present invention.

(Configuration 1) An imaging optical system that includes a light emitting unit that emits light having different principal wavelengths, an imaging optical system that focuses light emitted from the light emitting unit on a light modulation element, and a diffusion element. Is a transmissive image display device in which an image is displayed through the light modulation element and the diffusion element.
The transmissive image display device includes a plurality of pixels arranged at a predetermined pitch, each pixel including a plurality of picture elements corresponding to each color,
The imaging optical system includes a lens array in which a plurality of lenses are arranged at a predetermined pitch, and the lens separates the light emitted from the light-emitting unit according to color and separates the separated light from a pixel. Focus the light at the same pitch as the array pitch,
The transmissive image display device, wherein the light emitting unit emits light at different irradiation angles in the RGB arrangement direction and the same color arrangement direction of the transmissive image display device.

(Arrangement 2) The numbers of the RGB arrangement directions of the picture elements constituting each pixel of the transmissive image display device are the same as M and N, respectively.
When the maximum emission angles in the same color arrangement direction as the RGB arrangement direction when the light emitted from the light emitting unit passes through the transmissive image display device are θa and θb, respectively,
M * tanθb ≧ N * tanθa
The transmissive image display device according to Configuration 1, wherein:

(Configuration 3)

Configuration

1 or 2 in which the maximum passing angles θa and θb in the same color arrangement direction as the RGB arrangement direction when the light emitted from the light emitting unit passes through the transmissive image display device is within 40 ° 3. The transmission type image display device according to 2.

(Configuration 4)
Light having a light emitting unit that emits light having different main wavelengths, an imaging optical system that focuses light emitted from the light emitting unit on a light modulation element, and a diffusion element, and that has passed through the imaging optical system Is a transmissive image display device in which an image is displayed through a light modulation element and a diffusion element,
The transmissive image display device includes a plurality of pixels arranged at a predetermined pitch, each pixel including a plurality of picture elements corresponding to each color,
The imaging optical system includes a lens array in which a plurality of lenses are arranged at a predetermined pitch, and the lens separates the light emitted from the light-emitting unit according to color and separates the separated light from a pixel. Focus the light at the same pitch as the array pitch,
The transmissive image display device is characterized in that the light emitting unit has light emitting units that emit the same color in the same color arrangement direction as the RGB arrangement direction of the transmissive image display device.

(Configuration 5)
The numbers of the same color arrangement direction as the RGB arrangement direction of the picture elements constituting each pixel of the transmissive image display device are M and N, respectively.
When the maximum passage angle when the light emitted from the light emitting unit passes through the liquid crystal panel is θa, and the passage region when passing through the liquid crystal panel is α,
α ≦ {(NM) / M} * 2 * h * tanθa
The transmissive image display device according to Configuration 4, wherein:

(Configuration 6)
In the transmissive image display device, at least in the RGB alignment direction, a predetermined pitch of a plurality of pixels arranged on the pixel array surface is P, and an imaging magnification of the imaging optical system is (1 / n), Configuration 1 to 5 characterized in that the pitch P1 between the light emitting portions is approximately P1 = n × P, and the lens pitch P2 of the first lens array is approximately P2 = (n / (n + 1)) × P. The transmissive image display device according to any one of the above.

(Configuration 7)
7. The transmissive image display device according to any one of Configurations 1 to 6, further comprising a film having a function of suppressing backscattering of external light on an emission surface of the transmissive image display device.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments, respectively. Is also included in the technical scope of the present invention.

The present invention can be applied to a transmissive image display device, and in particular, can be applied to a backlight mounted on a transmissive image display device.

1 pixel 1a sub-pixel 1b sub-pixel 1c sub-pixel 3 light source section (backlight system)
4 Display panel (display section)
5 Condenser (backlight system)
10 Display device 46 Diffuser R Light emission point G Light emission point B Light emission point X First direction Y Second direction θa Maximum angle θb Maximum angle φ (X) Irradiation angle φ (Y) Irradiation angle

Claims

One pixel is composed of a plurality of sub-pixels, each of the plurality of sub-pixels has an elongated shape having a different width and length, and the plurality of pixels including the one pixel are in the extending direction of the width. Image information is obtained by modulating the amount of light that is two-dimensionally arranged in one direction and a second direction that is an extension direction of the length and that passes through each of the plurality of sub-pixels based on image information. A backlight system provided as a light source for a display device that displays
A light source unit including a plurality of light emitting points arranged two-dimensionally along the first direction and the second direction;
A light collecting section for individually collecting the first light emitted from at least one of the plurality of light emitting points on the corresponding sub-pixel,
After the first light is condensed on one of the sub-pixels, the shape of the light amount distribution on the plane perpendicular to the light traveling direction is related to the light beam emitted from one of the sub-pixels while spreading. Regardless of the number of condensing points condensed on one of the sub-pixels, the light source unit has a light emission state along the first direction so as to show an elongated shape similar to that of one of the sub-pixels. A backlight system, wherein the light emission state along the second direction is different.
2. The light emission point according to claim 1, wherein each of the plurality of light emitting points emits light such that an irradiation angle extending along the second direction is larger than an irradiation angle extending along the first direction. Backlight system.
A light beam included in a light beam condensed on one of the sub-pixels is within the plane including the normal direction of the surface including the first direction and the second direction and the first direction. The maximum angle θa at which the light beam is incident on one of the pixels is the maximum angle at which the light beam included in the light beam is incident on one of the sub-pixels in a plane including the normal direction and the second direction. The backlight system according to claim 2, wherein the backlight system is smaller than the angle θb.
Among the plurality of sub-pixels constituting the one pixel, the number of sub-pixels arranged in the first direction within the one pixel is N,
Among the plurality of sub-pixels, the number of sub-pixels arranged in the second direction within the one pixel is an integer M equal to or greater than 1,
Furthermore, when the pitch in the first direction of the plurality of pixels is Pa and the pitch in the second direction is Pb,
A light ray included in a light beam condensed on one of the sub-pixels, and is directed to the first direction with reference to a normal direction of the display surface defined by the first direction and the second direction. A light beam having a maximum inclination angle θa of the inclined light beam and a light beam having a maximum angle θb of the light beam inclined in the second direction,
(M / Pb) × tan θb≈ (N / Pa) × tan θa
The backlight system according to claim 2, wherein:
The backlight system according to claim 3 or 4, wherein the maximum angle θb is 40 degrees or less.
The plurality of light emitting points are two-dimensionally arranged such that an arrangement interval along the second direction is denser than an arrangement interval along the first direction. Item 2. The backlight system according to Item 1.
A plurality of light beams that have passed through the light condensing unit are condensed on one of the sub-pixels,
7. The backlight system according to claim 1, wherein condensing positions of the plurality of light beams in one of the sub-pixels are arranged along the second direction. 8.
The maximum angle θa of the angle at which a light beam spread in the first direction is incident on one of the sub-pixels is included in the light beam. The backlight system according to claim 6, wherein the light beam having a spread in the second direction is equal to a maximum angle θb of an incident angle on one of the sub-pixels.
The condensing unit is configured by a microlens array,
Among the plurality of pixels, P is a pitch of pixels arranged in at least the first direction,
The interval at which the plurality of light emitting points are arranged along the first direction is P1,
The imaging magnification of the light collecting part is (1 / n),
When the pitch of the microlenses adjacent in the first direction constituting the microlens array is P2,
9. The backlight system according to claim 1, wherein P1≈n × P and P2≈ (n / (n + 1)) × P are set.
A display device comprising the backlight system according to any one of claims 1 to 9.
A light source that emits light in different display colors;
One pixel includes a plurality of sub-pixels corresponding to the different display colors, each of the plurality of sub-pixels has an elongated shape having a different width and length, and the plurality of pixels including the one pixel are The amount of the second light that is two-dimensionally arranged along the first direction that is the extending direction of the width and the second direction that is the extending direction of the length, and that passes through each of the plurality of sub-pixels. A display unit that displays the image information by modulating the image information; and
A condensing unit for individually condensing the light emitted from the light source unit on the sub-pixels of the display color corresponding to the display unit;
A diffusion plate that is disposed on the viewer side with respect to the display unit and diffuses the second light that has passed through the display unit;
One of the sub-pixels passes through a condensing region of the condensing unit that condenses a part of the light emitted from the light source unit, In the light source unit, the shape of the light irradiation range formed on the surface shows an elongated shape similar to that of one of the sub-pixels, regardless of the number of light spots collected on one of the sub-pixels. The display device is characterized in that the light emission state along the first direction is different from the light emission state along the second direction.
The light emitting points are two-dimensionally arranged such that the arrangement interval along the second direction is denser than the arrangement interval along the first direction. The light beam that is included in the light flux collected and spreads in the first direction is included in the light flux and spreads in the second direction. The maximum angle θb of the angles at which the light rays are incident on one of the sub-pixels is equal to each other,
The number of the plurality of sub-pixels constituting the one pixel arranged in the first direction is N,
The number arranged in the second direction is an integer M of 1 or more, and M <N.
Furthermore, it is assumed that the pitch in the first direction and the pitch in the second direction of the plurality of pixels are equal to each other,
In one of the sub-pixels, an interval between condensing positions adjacent to each other along the second direction of the plurality of light beams is α,
When the interval between the display unit and the diffusion plate is h,
α≈ {(NM) / M} × 2 × h × tan θa
The display device according to claim 11, wherein:
The display device according to claim 12, wherein the maximum angle θa is 40 degrees or less.
The display device according to any one of claims 11 to 13, further comprising a functional film that suppresses backscattering of the diffusion plate with respect to external light.
One pixel is composed of a plurality of sub-pixels, each of the plurality of sub-pixels has an elongated shape having a different width and length, and the plurality of pixels including the one pixel are in the extending direction of the width. By two-dimensionally arranging along one direction and a second direction that is an extension direction of the length, and modulating the amount of light passing through each of the plurality of sub-pixels based on image information, A control method of a backlight that irradiates the light to a display device that displays image information,
After the light is condensed on one of the sub-pixels, the shape of the light amount distribution in a plane perpendicular to the light traveling direction of the light beam emitted from one of the sub-pixels while spreading is that of the sub-pixel. A backlight control method, wherein the backlight optical system is set so as to show an elongated shape similar to that of one of the sub-pixels, regardless of the number of light spots condensed into one.