JP3952859B2 - Light guide sheet and display illumination device using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of an illuminating device for uniformly irradiating illumination light from a built-in light source in a display using a display screen such as a transmissive image display element within the display screen, and more particularly to a liquid crystal display device (LCD). The present invention relates to a display illumination device using a thin light guide sheet that employs a method of transmitting irradiation light from a light source in a light guide.
[0002]
[Prior art]
Among display devices (displays) equipped with a built-in illumination light source, the spread of liquid crystal displays (LCD) is remarkable, and illumination light from a light source (backlight or edge light) for generating display light is used. Further, the spread of a device of a type including a light guide unit for making the luminance and the irradiation direction uniform in the display screen is also remarkable.
[0003]
In this specification, the illumination means of the type that directly illuminates the display screen from the back side (the side opposite to the observer) of the display screen is “direct-type backlight”, from the light source arranged outside the display screen (side surface, etc.) The illumination means that illuminates the display screen after passing the illumination light through a light guide unit disposed on the back of the display screen is referred to as an “edge-light type backlight (hereinafter simply referred to as an edge light)”. I will do it.
[0004]
An edge light system is often used for a backlight for a liquid crystal display. A light guide plate made of a light-transmitting material, a line light source made of a cold cathode tube or the like provided at the end of the side surface, a lower surface of the light guide plate, A light guide unit composed of a light reflection film disposed to cover the line light source and a light diffusion film or lens sheet disposed on the upper surface of the light guide plate serving as a light output surface is representative.
[0005]
In order to improve non-uniformity in the amount of light emitted due to the distance from the light source, there is a technique such as a dot-like pattern made of light diffusing ink printed on the back surface of the light guide plate so as to become larger as the distance from the light source increases. Adopted.
The light diffusion film is disposed mainly for the purpose of diffusing light uniformly and making the dot pattern printed on the back surface of the light guide plate invisible, and the lens sheet efficiently transmits the light emitted from the light guide plate. In order to condense in the front direction, one or two sheets are arranged on the upper surface of the light diffusion film or between the light diffusion film and the light guide plate.
[0006]
As the lens sheet, a lens sheet (prism sheet) in which a large number of triangular prism unit lens units are arranged in parallel is used in order to diffuse the isotropic light uniformly and isotropically within a desired angle range. It is called BEF (Brightness Enhancement Film: trade name manufactured by Sumitomo 3M).
[0007]
Also, various methods using an optical fiber are known as other light guide units in the edge light system or the like.
The advantage of using an optical fiber is that the illumination light from the light source can be transmitted to the illumination target with little loss, and the optical path from the light source to the illumination target can be bent. The degree of freedom is to improve.
References describing a light guide unit using an optical fiber are exemplified below.
[0008]
JP-A- 6-222362
An illumination device for illuminating a liquid crystal display device from behind, wherein the liquid crystal display device comprises a minute convergence lens array and a minute secondary light source arranged at the focal point of each minute convergence lens, and irradiates substantially parallel light. Lighting equipment.
[0009]
JP-A- 9-252825
An LCD panel provided with pixels corresponding to the three primary colors of red, green, and blue, a backlight light source unit that illuminates the LCD panel with transmitted light from the back, and only primary colors corresponding to the pixels of the LCD panel. In the full color LCD display device provided with wavelength selection means for transmitting, the backlight light source unit has a light emitting surface divided into red, green and blue light emitting blocks corresponding to the pixels of the LCD panel, and the wavelength. A full-color LCD display device characterized by being a selection means.
[0010]
JP-A-10 - 288 782
An optical fiber backlight module for a color display, which is connected to the light source and arranged in parallel, transmits light emitted from the light source, and emits light from a side surface to form a first-layer optical fiber. An optical fiber battenite module for a color display, comprising: a plurality of side-emitting optical fibers; and a plurality of column isolation parts provided between adjacent side-emitting optical fibers.
[0011]
JP 2000 - 231816
At least one LED, a plurality of optical fibers in which the emission ends are arranged substantially linearly and the incidence ends are arranged to face the LEDs, and optical coupling means for optically coupling the LEDs and the incidence ends of the optical fibers A light source device.
[0012]
In any of the light guide units exemplified above, the optical fiber as the light guide has a configuration in which light is incident from one end and illumination light is emitted from the other end toward the illumination target.
In the case of the above configuration, in order to illuminate the entire display screen, the larger the screen size, the more optical fibers are required, which not only increases the cost of the light guide unit, but also the fibers from the incident side to the emission side. Depending on the length and the number of fiber bundles, the light guide unit has a large structure, and the influence on the increase in the thickness and weight of the entire display device is large.
[0013]
[Problems to be solved by the invention]
The present invention uses a light guide that can transmit illumination light from a light source to an illumination target with little loss, and can freely form an optical path from the light source to the illumination target. The main object is to provide a light guide unit that not only improves the degree of freedom but also has a compact structure.
[0014]
[Means for Solving the Problems]
The display illumination device according to the present invention comprises:
A light guide sheet having a configuration in which a linear light guide is arranged by patterning on a substrate surface substantially parallel to the display screen, and an illumination light source,
The light incident from the end of the light guide is emitted as illumination light toward an illumination target at a plurality of locations of the light guide.
[0015]
As a pattern in which the light guide is arranged in the light guide sheet in the display illumination device,
(1) A structure in which a single light guide repeats reciprocation over substantially the entire surface of the base material. (2) A structure in which a single light guide is repeatedly turned over almost the entire surface of the substrate. (3) A structure in which the light guide is branched across a plurality of locations so as to extend almost entirely on the substrate surface.
(4) The structure formed by combining at least one pattern described in the above (1) to (3) on the surface of the same substrate.
Etc. are adopted.
[0016]
Moreover, it is good also as one sheet of light guide sheet | seat by superimposing two or more separate light guide sheets each arrange | positioned by patterning a light guide on the surface of a different base material.
[0017]
The illumination light emission locations are preferably arranged at equal intervals in the display screen in view of illumination with uniform luminance in the screen.
[0018]
Moreover, when arrange | positioning a light guide on the flat base material surface, you may arrange | position in a pattern shape in the state embedded at the base-material surface vicinity.
[0019]
As a material constituting the light guide, a cured product of a radiation curable resin having a refractive index larger than that of the substrate may be used.
[0020]
Moreover, as a usage pattern of the display illumination device, the illumination light source receives light of a selective wavelength width that defines different display colors depending on the light guide from each end of the plurality of light guides. It is good also as a structure which transmits.
As light of a selective wavelength width that defines the display color, three primary colors of R, G, and B are generally used.
[0021]
As a display device equipped with the display illumination device described above, the emission point of the illumination light corresponds to the pixel of the display screen in which the display pattern is determined by selectively specifying transmission / non-transmission in pixel units. An LCD is generally used as the display screen.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
<Embodiment 1>
FIG. 1 is an explanatory diagram showing an outline according to an embodiment of a display illumination device 10 according to the present invention.
The light guide sheet 11 has a configuration in which the light guide 3 is patterned on the surface of the base material 2, and the light from the illumination light source 1 is incident from the end of the light guide 3 and transmitted. In addition, the light guide body 3 functions so as to be emitted from a plurality of exit ports 4 and become illumination light toward the display screen.
[0023]
As a pattern in which the light guide 3 in this embodiment shown in the figure is formed, one light guide 3 is configured to repeat reciprocation over almost the entire surface of the substrate 2, By arranging the injection port 4 as shown in the figure, the illumination light is uniformly irradiated over the entire surface of the display screen (not shown).
[0024]
FIG. 2 is an explanatory view showing, in an enlarged manner, the state in which the light guide 3 is formed on the surface of the base material 2. The case where the light guide 3 is formed on the surface of the flat base material 2 is introduced into a). The case where the surface of the base material 2 where the light body 3 is formed is processed into a groove shape and the light guide 3 is embedded in the groove portion is shown in b).
[0025]
When both the base material 2 and the light guide 3 are translucent, it is necessary that they be made of materials having different refractive indexes in order to transmit light while repeating total reflection at the interface between them. The one where the refractive index of the body 3 is large is preferable.
In order to prevent the loss of light transmitted inside the light guide 3 from other than the exit 4, a method such as coating a part other than the exit 4 with a highly light-reflective material is also appropriately employed. In this case, there is no need for a difference in refractive index between the substrate 2 and the light guide 3.
[0026]
As the characteristics required for the light guide 3,
(1) Incident light from the light source is transmitted with little loss.
(2) A desired light beam (amount of light, wavelength, direction, etc.) is appropriately emitted from each outlet 4.
(3) As a result, the luminance distribution of illumination light over the entire display screen becomes uniform.
Etc.
[0027]
As an example of a pattern forming unit using the light guide 3, a photolithographic method is used in which a photosensitive resin layer is formed on the entire surface of the base material 2 using a photoresist or the like, and the photosensitive resin layer is patterned into a desired pattern. Alternatively, a method of stretching the fiber-shaped light guide 3 in a pattern on the surface of the base material can be considered. As another method of forming a pattern using a resin, a method may be considered in which a groove corresponding to a pattern is formed in advance on the surface of the base material, and a resin that becomes the light guide 3 is embedded only in the groove.
The cross-sectional shape of the light guide 3 is not limited to a rectangle as shown in FIG.
[0028]
FIG. 3 is an explanatory diagram showing optical paths such as a light beam transmitted through the light guide 3 and a light beam emitted from the side surface of the light guide 3 corresponding to the emission port 4.
In the process in which a light ray incident from one end (left side of the figure) of the light guide 3 propagates toward the other end (right side of the figure), the light ray is reflected at the interface with the surroundings in the light guide body 3 (mainly , Total reflection).
[0029]
At this time, if the light guide 3 is homogeneous, incident light from one end of the light guide 3 is emitted from the other end with almost no loss. In order to form 4, the illumination light 5 is transmitted while being emitted from a part of the light guide 3 corresponding to the exit 4.
If there is an inhomogeneous portion in the light guide 3, the exit port 4 functions so that total reflection does not occur in that portion, leaks from the inside of the light guide 3, and exits to the display screen.
The component light that has not been emitted continues to be transmitted through the light guide 3 thereafter.
[0030]
As a form of the inhomogeneous part for generating the emission light from the inside of the light guide 3,
1) Change the size (width, thickness, etc.) of the part.
2) Change the refractive index of the part.
3) The portion is subjected to mechanical processing such as fine unevenness so that light scattering and diffraction according to the unevenness occur.
And so on.
[0031]
In the above pattern, in order to transmit incident light from the incident end to the other end of the light guide 3 without loss, light that does not become illumination light for display is displayed at the corner for repeating reciprocation. It is necessary to have a configuration that does not emit light from inside 3 and a configuration in which transmitted light does not return in reverse, and it is necessary to perform a reflection process for preventing light from leaking to the light guide 3 at the corner portion. .
[0032]
<Embodiment 2>
FIG. 4 is an explanatory diagram showing an outline according to the second embodiment of the display illumination device 10 according to the present invention.
In the figure, the same constituent elements are denoted by the same reference numerals, and their functions and formation methods are also common, and thus the description thereof is omitted. However, the difference from the first embodiment is different from the first embodiment. One light guide 3 has a configuration in which the rotation is repeated substantially over the entire surface of the base material 2.
Even in the configuration shown in the figure, in order to transmit incident light from the incident end to the other end of the light guide 3 without loss, light that does not become illumination light for display is in the light guide 3 at the corner. It is necessary to have a configuration that does not emit light and a configuration in which transmitted light does not return.
[0033]
<Embodiment 3>
FIG. 5 is an explanatory diagram showing an outline according to the third embodiment of the display illumination device 10 according to the present invention.
As shown in FIG. 5 a), the present embodiment is characterized in that the light guide 3 extends at almost the entire surface of the base material 2 by branching at a plurality of locations.
Even in the configuration shown in the figure, in order to transmit incident light to each end branched from the incident end of the light guide 3 without loss, light that does not become illumination light for display is guided at the corner. It is necessary to have a configuration that does not emit light from the inside of the light body 3 and a configuration that does not return the transmitted light.
[0034]
<Embodiment 4>
In the present embodiment (fourth embodiment), as shown in FIG. 5b), the pattern of the light guide 3 is comb-like as shown in FIG. 5a) and has a large number of ends (non-incident side). Rather, it is characterized in that it has no open end.
As shown in the figure, the distribution of luminance due to illumination light in the display screen by making light rays not only enter from one end of the pattern of the light guide 3 but also from the other end at the farthest position in the display screen. A uniform improvement is also preferable.
[0035]
<Embodiment 5>
In this embodiment (fifth embodiment), as shown in FIG. 6, a light guide pattern having a structure in which one light guide as described in the third embodiment branches in a comb-like shape. This is an explanation relating to the case where the surface of the same base material 2 has a pattern of a combination of two types (3a and 3b).
In each of the light guide patterns 3a and 3b, exit ports 4a and 4b are respectively formed at a plurality of locations.
[0036]
A method of combining a plurality of types of light guide patterns on the surface of the same base material 2 is a pattern in which a single light guide as described in the third embodiment is branched, as in this embodiment. Not limited to this, a configuration in which at least one pattern selected from the first, second, and third embodiments is combined in two or more types (1-1, 1-2, 1-3, 2-2, 2-3, etc.). 3 types of combinations such as 1-1-2, 1-1-3, and 1-2-3 are also possible.
[0037]
According to this embodiment, as a usage pattern of the display illumination device, the illumination light source has a selective wavelength width that defines different display colors depending on the light guide from the end of each of the plurality of light guides. It is possible to adopt a configuration in which light is incident and transmitted.
For example, in the case of FIG. 6, a red light beam is incident from the light source 1a that emits a light beam having a wavelength corresponding to red from the start end of the pattern 3a, and red illumination light is emitted from the emission port 4a. The pixel corresponding to the exit 4a has a configuration in which pixels for displaying red in the full-color image are arranged, and a light beam having a wavelength corresponding to another color (blue or green) is transmitted from the start end of the pattern 3b. It is a usage form.
A revolutionary display that does not require a color filter on the display of a full-color image when there are three types of light guide patterns and the exit from each corresponds to a pixel representing the three primary colors of the display screen. Is realized. (See Figure 7)
[0038]
<Embodiment 6>
In this embodiment (sixth embodiment), as shown in FIG. 8a), a light guide pattern having a structure in which one light guide as described in the first embodiment is reciprocated is different. This is an explanation relating to a case where one light guide sheet is formed by superimposing different light guide sheets 11 and 12 respectively arranged on the surface of the base material.
Thus, by laminating a plurality of light guide sheets, it is difficult to increase the formation density of the light guide pattern (and the arrangement density of the injection ports 4) with only one base material. However, by superimposing the light guide patterns (and the injection ports 4) arranged on different base materials, it becomes easy to cope with high density.
As illustrated in FIG. 8b), the light guide pattern 3a and the exit 4a (rectangle) on the light guide sheet 11 and the light guide pattern 3b and the exit 4b (cross shape) on the light guide sheet 12 are formed. The combined illumination device corresponds to one display screen, and is suitable for use in illuminating different colors of illumination light to corresponding pixels, for example, 4a corresponds to red pixels and 4b corresponds to blue pixels. is there.
In the present embodiment, it is preferable to superimpose three light guide sheets corresponding to red, green, and blue, respectively, instead of two light guide sheets, for full color image display.
[0039]
FIG. 9 conceptually shows a state in which the illumination device having the light guide sheet according to any one of the above embodiments is applied to the illumination unit of the liquid crystal display device.
As shown in FIG. 9 a), the light guide sheet 11 of the lighting device is disposed on the back surface of the liquid crystal display element (liquid crystal panel) 30.
At this time, when the number of illumination light exit points (emission ports 4) from the light guide sheet 11 and the pixels of the liquid crystal panel 30 are equal to 1: 1, the latter is large. It is desirable to arrange them so as to correspond evenly at 1: n.
[0040]
FIG. 9B) is a plan view showing a correspondence relationship between the pixels 33 (rectangular) of the liquid crystal panel 30 and the outlet 4 (cross shape) of the light guide sheet 1.
In the figure, the case where the pixel arrangement of the LCD is arranged in a matrix is illustrated, but as shown in FIG.
There are various forms such as a) stripe b) matrix c) delta and the like.
[0041]
When each pixel is divided into pixels corresponding to the three primary colors R, G, and B and a full-color image is displayed, the stripe pattern of a) is an array of colors corresponding to the three primary colors, Illumination with a wavelength corresponding to each color is performed in stripe units, and a plurality of pixels arranged in one stripe are displayed in the same color.
[0042]
In FIG. 9, the LCD is exemplified as the display. However, the present invention is not limited to this. The transmissive image display element in which the display pattern is determined by selectively defining transmission / non-transmission in units of pixels is shown in FIG. The lighting device according to the invention can be applied.
[0043]
【The invention's effect】
According to the present invention, it is possible not only to transmit the illumination light from the light source to the illumination target with a small loss and to freely form an optical path from the light source to the illumination target, but also on the configuration of the light guide unit. There is provided a light guide unit that has a high degree of freedom, a compact structure, and does not increase the cost of the display device.
In addition, since illumination light can be emitted in accordance with the pixels of the display screen, the use efficiency of light from the light source is high, and display with high luminance is possible.
Furthermore, the illumination device according to the present invention can be applied to a configuration suitable for full-color image display by selectively using light (e.g., three primary colors of red, green, and blue) for each light guide. This also leads to the realization of a new full color display that does not require a color filter.
[0044]
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an outline according to an embodiment of a display illumination device 10 according to the present invention.
FIG. 2 is an explanatory view showing, in an enlarged manner, a state in which a light guide 3 is formed on the surface of a base material 2;
FIG. 3 is an explanatory diagram showing light paths such as a light beam transmitted through the light guide 3 and a light beam emitted from a part of the light guide 3 corresponding to the exit port 4;
FIG. 4 is an explanatory diagram showing an outline according to a second embodiment of a display illumination device according to the present invention.
FIG. 5 is an explanatory diagram showing an outline according to third and fourth embodiments of a display illumination device 10 according to the present invention.
FIG. 6 is an explanatory view showing an outline according to a fifth embodiment of a display illumination device 10 according to the present invention.
FIG. 7 is an explanatory diagram showing an example of a state in which the fifth embodiment of the display illumination device according to the present invention is applied to a display for displaying a full-color image using a combination of three primary colors.
FIG. 8 is an explanatory view showing an outline according to a sixth embodiment of a display illumination device 10 according to the present invention.
FIG. 9 is an explanatory diagram conceptually showing a state in which an illumination device having a light guide sheet according to the present invention is applied to an illumination unit of a liquid crystal display device.
10 is an explanatory diagram showing various forms of pixel arrangement in a liquid crystal panel. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Illumination light source 2 ... Base material 3 ... Light guide 3a, 3b ... Light guide pattern 4 ... Outlet
10 ... Display lighting device
11, 12 ... Light guide sheet

Claims (11)

A light guide sheet having a configuration in which a linear light guide made of a cured product of a radiation curable resin having a refractive index larger than that of a base material is patterned by a photolithographic method on the base material surface;
An illumination light source,
The light guide sheet is disposed substantially in parallel with the display screen that is the illumination target,
The display illumination device according to claim 1, wherein light incident from an end of the light guide is emitted as illumination light toward an illumination target at a plurality of locations of the light guide.   2. The display illumination device according to claim 1, wherein the light guide is configured such that one light guide repeats reciprocation over substantially the entire surface as the pattern in which the light guide is arranged. Light guide sheet used in   2. The display illumination device according to claim 1, wherein the light guide is arranged in such a manner that one light guide repeats turning substantially over the entire surface of the base material. Light guide sheet used in   2. The display illumination device according to claim 1, wherein the light guide is arranged at a plurality of locations so that the light guide is branched at a plurality of locations so as to extend substantially over the entire surface of the substrate. Light guide sheet used in   A light guide sheet comprising a plurality of light guides combined with at least one pattern described in claim 2, 3 or 4 as a pattern in which the light guide is arranged. .   A light guide sheet comprising a plurality of the light guide sheets according to any one of claims 2 to 5 having a structure in which light guides are respectively arranged on different substrate surfaces.   The light guide sheet according to any one of claims 2 to 6, wherein the illumination light emission portions are arranged at equal intervals in the display screen.   The illumination light source has a configuration in which light having a selective wavelength width that defines a different display color is incident and transmitted from an end of each of the plurality of light guides. Item 7. A display illumination device using the light guide sheet according to item 5 or 6. 9. The display illumination device according to claim 8 , wherein three primary colors of R, G, and B are used as light having a selective wavelength width that defines a display color. A display device comprising mounting the display illumination device according to claim 1, 8, 9,
The display device according to claim 1, wherein the illumination light emission portion has a configuration corresponding to a pixel of a display screen on which a display pattern is determined by selectively defining transmission / non-transmission in pixel units. The display device according to claim 10 , wherein the display screen is an LCD.

Images