JPH10333141A - Liquid crystal display device and arrangement structure of lamp for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a liquid crystal display device thinner while securing the efficiency of light made incident on a light guide plate 11 from a lamp and the prescribed thickness of a case and also to enhance the using efficiency of the light made incident on the light guide plate. SOLUTION: A liquid crystal display device 5 is provided with a transmission type liquid crystal panel, a light guide plate 11 for guiding illuminating light to the liquid crystal panel and a lamp 13 arranged on one side of the light guide plate 11 and components including them are housed in a metal case 6. In this case, the light guide plate 11 is assembled along the prescribed inside wall surface of the case 6 through a reflection sheet 12 and the assembled surface of the plate 11 and the inside wall surface of the case 6 are formed in a curved shape of a prescribed curvature so that the thickness of at least the end part on the lamp side of the plate 11 and the thickness near the end part on the lamp side of the plate 11 are continuously changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liquid crystal display device and a layout structure of lamps for the liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal display device includes a transmission type liquid crystal panel, a light guide plate for guiding illumination light to the liquid crystal panel, and a lamp disposed on one side of the light guide plate. The one in which the components are housed in a metal housing is generally well known, and is commonly used as a display device such as a portable computer or a word processor. In a display device having such a structure, in general, the light guide plate is preferably as thick as possible in order to increase the incident efficiency from the lamp and secure the amount of illumination to the liquid crystal panel, and also regarding the thickness of the metal housing, Thickness is more preferable for enhancing strength and rigidity of the housing.

In recent years, in particular, portable computers such as notebook computers have been further reduced in size and weight.
In particular, there has been a demand for a reduction in thickness, and as a part of this, a display device has also been required to be thinner. When the display device is made thinner, it is necessary to limit the thickness of the light guide plate and the metal housing to a minimum as long as the necessary characteristics are not impaired.

[0004] In this regard, for example, US Pat. No. 5,489,999 (hereinafter referred to as “prior art 1”) discloses FIG. As shown in FIG. 22, the upper surface 1 of the light guide plate 111 in FIG. 22 is formed such that the thickness of the light guide plate 111 is thicker at the end (light incident portion) on the lamp 113 side and thinner on the opposite side of the lamp.
11a is disclosed as having a sloped shape. According to this configuration, since the thickness of the light guide plate 111 is set to be sufficiently thick at the light incident portion, the average thickness of the light guide plate 111 is reduced while ensuring the incidence efficiency of the illumination light from the lamp 113. It can be made somewhat thin. No. 54
No. 52385 (hereinafter referred to as Conventional Technique 2), as shown in FIG. 23, the thickness of the light guide plate 121 is increased only in the vicinity of the end (light incident portion) on the lamp 123 side, and Is disclosed in which the thickest portion of the end portion and the portion having the standard thickness are connected by an obliquely inclined plane 121a. In this case as well, the same effect as that of the above-described related art 1 can be obtained with respect to the incident efficiency of the illumination light from the lamp 123, and the average thickness of the light guide plate 121 is greater than that of the above-described related art 1. Can be thin.

Conventionally, in a color liquid crystal display device, light incident on a liquid crystal panel side from a light guide plate is usually first polarized by a polarizing plate, and then passes through a liquid crystal panel and a color filter. As the color filter, a pigment type absorption type filter is commonly used. The color filters are RGB (Red,
Green (green), Blue (blue)), and one pixel corresponds to one color of the color filter. In the case of an absorption type color filter, two colors other than the color are absorbed in each portion corresponding to one pixel, so that the incoming white light is narrowed down to 1/3 by the color filter. Will go out. Note that, as the color filters, in addition to the above-mentioned absorption type, a spectral type filter that selectively allows light components of a specific color to pass according to the wavelength of light is known. In the case of this spectral color filter, the light component of the color that does not pass is reflected by the filter.

The lamp for supplying illumination light to the liquid crystal panel via the light guide plate is generally surrounded by a substantially cylindrical reflector (a so-called reflector) having only the light guide plate side open. However, when assembling the reflector to the lamp, for example, the reflector is mounted on a ring-shaped member of a predetermined size at a plurality of locations in the longitudinal direction of the lamp, and the reflector is attached to the lamp. In general, the lamp is positioned so as to be held at equal intervals with respect to the outer periphery, that is, the lamp and the reflector are concentric.

[0007]

As described above, in order to reduce the thickness of the display device, it is important to make the light guide plate as thin as possible while ensuring the efficiency of incidence of illumination light from the lamp. However, in the case of the above-described prior art 1, the light guide plate has one surface 111 over the entire length in the longitudinal direction.
Since a is formed in a slope shape (in a cross section, it is formed in a linearly tapered shape), the portions other than the lamp side end portion (light incident portion) necessary for securing the incident efficiency need to be thinned. Will be inadequate. Also, in the case of the above-mentioned conventional technology 2,
Although it can be made thinner than the prior art 1,
Since the thickest part of the lamp side end part (light incident part) and the part of the standard thickness are connected by the inclined plane 121a (in a cross section, as an oblique straight line), the plane of the part of the standard thickness and the inclined part are inclined. It is conceivable that a fold is formed at the coupling portion 121b with the flat surface 121a, and the luminance locally increases in this portion, and the corresponding display appears to shine on the display. In order to allow the light entering the light guide plate to enter the liquid crystal panel side, it is necessary to provide a reflection sheet on the light guide plate on the side opposite to the liquid crystal panel.

The components of the display device including the liquid crystal panel, the light guide plate, the lamp, and the like are housed in a metal housing. The thickness of the housing is allowable from the viewpoint of reducing the thickness of the entire display device. In order to ensure the required strength and rigidity within the specified range, and particularly to ensure castability when the housing is formed as a cast product of a light alloy or the like, the thickness is preferably as large as possible.

Further, as described above, it is important to increase the incidence efficiency from the lamp to the light guide plate, and it is also important to effectively use the light that has entered the light guide plate. However, in this regard, in the case of the conventional color filter, the color filter is provided on the exit side of the liquid crystal panel with respect to the path of light, and as described above, is usually an absorption type, and the white color that passes through the color filter through the liquid crystal panel The light will be narrowed down to 1/3 by the color filter and go out,
Light use efficiency was inevitably low.

On the other hand, the inventor of the present application has conducted intensive studies in order to further effectively use the light emitted from the lamp.
By devising the positional relationship between the lamp and the reflector surrounding the lamp, it has been found that the efficiency of light incidence from the lamp to the light guide plate can be increased.

Accordingly, the present invention can achieve a reduction in thickness while ensuring the efficiency of light incidence from the lamp to the light guide plate and the required thickness of the housing, and can also reduce the light incident on the light guide plate. An object of the present invention is to provide a liquid crystal display device and an arrangement structure of a lamp for the device, which can enhance the use efficiency of the device.

[0012]

Therefore, a first aspect of the present invention provides a transmission type liquid crystal panel, a light guide plate for guiding illumination light to the liquid crystal panel, and a light guide plate disposed on one side of the light guide plate. In a liquid crystal display device comprising a lamp and containing these components in a metal housing, the light guide plate is assembled along a predetermined inner wall surface of the housing via a reflection sheet, The mounting surface of the light guide plate and the inner wall surface of the housing are formed in a curved shape having a predetermined curvature so that the thickness of the light guide plate at least at the end on the lamp side and the vicinity thereof is continuously changed. It was made.

According to a second aspect of the present invention, in the first aspect, the tangent angle of the light guide plate at the lamp-side end with respect to the mounting surface is set in a range of 87 to 89 degrees. is there. Here, the lower limit of the tangent angle is 87
When the tangent angle is 86 degrees or less, when the assembling surface of the light guide plate and the inner wall surface of the lid housing are formed in a curved shape on the light incident side of the light guide plate, a good condition on the display is obtained. This is because it is difficult to stably secure a proper display uniformity. The reason why the upper limit of the tangent angle is set to 89 degrees is to allow manufacturing accuracy by allowing a variation in processing accuracy within a certain range with respect to a critical value of 90 degrees.

Further, a third invention of the present application is directed to a transmissive liquid crystal panel having a color filter, a light guide plate for guiding illumination light to the liquid crystal panel, and a lamp disposed on at least one side of the light guide plate. Wherein the color filter is arranged between the liquid crystal panel and the light guide plate, and the color filter is of a spectral type.

Still further, according to a fourth aspect of the present invention, there is provided a lamp for a liquid crystal display device which is arranged on at least one side of a light guide plate of a transmission type liquid crystal panel and supplies illumination light to the liquid crystal panel via the light guide plate. The lamp is surrounded by a substantially cylindrical reflector that is open only on the light guide plate side, and the center position of the lamp is eccentric from the center of the reflector. Is set to.

[0016]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a perspective view showing an example of the computer according to the embodiment of the present invention. As shown in FIG. 1, the computer 1 is, for example, a portable notebook type. A lid 4 is provided to be openable and closable with respect to a main body 2 in which a key input device 3 is incorporated. A display device 5 having a liquid crystal panel is incorporated. FIG. 2 is an exploded perspective view schematically showing a basic structure of the liquid crystal display device 5. As can be clearly understood from this figure, the liquid crystal display device 5
Basically, the backlight unit 10 and the liquid crystal panel unit 20 are sequentially stacked and arranged on the inner surface side (the upper side in FIG. 2) of the metal lid housing 6, and the mask frame 7 is mounted on the upper side. Above, a plurality of screws 8 are screwed in from the outer surface side on the mask frame 7 side and fastened to be integrated. In the present embodiment, the lid housing 6 is formed as a cast product by a die casting method using, for example, magnesium (Mg) or a light alloy of Mg system as a material.

As will be described in more detail later, the backlight unit 10 includes a light guide plate 11 for guiding illumination light toward the liquid crystal panel unit 20 and a columnar lamp 13 disposed on one side of the light guide plate 11. For example, silver (Ag) is provided on the back side (the lower side in FIG. 2) of the light guide plate 11.
A reflection sheet 12 made of a resin film coated with a. The outer periphery of the lamp 13 is surrounded by a reflector 14 (corresponding to a reflector described in claim 4 of the present application), which is substantially cylindrical and has only the light guide plate 11 side open. The reflector 14 has an inner surface formed of, for example, a thin brass plate plated with silver. The lamp 13 is connected to an inverter 15 as a high frequency power supply. A lens sheet 17 is disposed above the light guide plate 11 via a diffusion sheet 16. Then, based on the light guide plate 11, each of the sheets 16, 17
Is attached by, for example, an adhesive tape to assemble the backlight unit 10. On the other hand, the liquid crystal panel unit 20 basically includes a color TFT (thin film transistor) liquid crystal panel 21 as a transmissive liquid crystal panel, a source substrate 22, and a gate COB integrated substrate 23. It is assembled integrally by the machine. As will be described in detail later, in the present embodiment, a spectral color filter is disposed between the liquid crystal panel unit 20 and the backlight unit 10.

In the present embodiment, as shown in detail in FIG. 3, the light guide plate 11 is assembled along the inner wall surface of the lid housing 6 via a reflection sheet 12. By assembling the light guide plate 11 in this manner, the reflection sheet 12 is held between the back surface of the light guide plate 11 and the inner wall surface of the lid housing 6 while being pressed by the light guide plate 11. . That is, the reflection sheet 12 can be assembled on the back surface side (the opposite side to the liquid crystal panel) of the light guide plate 11 with a very simple configuration without using any special assembling means.

Further, in the present embodiment, as shown in more detail in FIG. 4, the thickness of the light guide plate 11 at least at the end on the lamp side (that is, the light incident portion) and the vicinity thereof is continuously changed. The mounting surface of the light guide plate 11 and the inner wall surface of the lid housing 6 are formed into a curved surface having a predetermined curvature (radius of curvature Rg). Assembly surface of light guide plate 11 and lid housing 6
By forming the inner wall surface of the light guide plate 11 in this manner,
After ensuring the thickness of the lamp-side end (light-entering portion) of the light guide plate 11 as thick as possible, the thickest portion of the light-guide plate 11 at the lamp-side end and the standard thickness portion or the end opposite to the lamp are inclined by an inclined plane. The average thickness of the light guide plate 11 can be reduced as compared with the related art in which the light guide plate 11 is tied. In addition, in FIG.
1 is displayed as a solid curve (radius Rg), whereas the thickest portion (light incident portion) of the light guide plate 11 on the lamp side and a portion having a standard thickness are temporarily connected. In this case, the inclined plane is indicated by a dashed straight line as a virtual line.

That is, under the condition that the thickness of the light guide plate 11 and the lid housing 6 is added and the thickness is limited to a certain value or less, the efficiency of light incidence from the lamp 13 to the light guide plate 11 is ensured, and The average thickness of the housing 6 can be set thicker, and the strength and rigidity of the lid housing 6 can be increased. That is, it is possible to achieve a reduction in thickness while securing the incident efficiency of light from the lamp 13 to the light guide plate 11 and the required thickness of the lid housing 6. According to the present embodiment, the entire thickness of the display device 5 can be reduced to, for example, about 7 mm. Moreover, in this case, the mounting surface of the light guide plate 11 and the inner wall surface of the lid housing 6 are formed in a curved shape, so that the light guide plate 11 has the thickest portion at the lamp side end and the standard thickness. Unlike the related art in which the portion or the end opposite to the lamp is connected by an inclined plane, no break occurs in the middle of the light guide plate 11, and there is a concern that the display on the display may have an adverse effect such as a bright line. Can be eliminated. In the present embodiment, more preferably, a predetermined processing is performed on a mold surface of the mold when the light guide plate 11 is formed so that its mounting surface is curved, so that the back surface of the light guide plate 11 is formed. Reflection dots are formed on the (assembly surface) side so that scattered light can be emitted toward the liquid crystal panel 21 side.

In the present embodiment, an experiment and a simulation calculation for examining the effect of the thickness of the light incident portion of the light guide plate 11 on the incident efficiency when the light emitted from the lamp 13 enters the light guide plate 11 are performed. Was. This simulation calculation was performed for the case where the lamp 13 was arranged coaxially with the reflector 14 whose general shape is shown in FIG. Typical simulation conditions and calculation examples are shown below.

<Simulation conditions>-Radius of reflector: 1.375 mm-Inner / outer diameter of lamp: 1.4 mm / 2.0 mm-Specular reflectance of reflector: 98%-Refractive index of lamp material: 1.49 Lamp scattering reflectance / scattering transmittance: 65% / 25%
(0.65 / 0.25)-Re-incident light loss of the lamp: 10% Fluorescent paint is applied to the wall surface of the lamp 13,
Light traveling from the inside of the lamp 13 to the outside may be reflected internally or transmitted outside. In this simulation, the ratio (scattered reflectance / scattered transmittance) is set as described above.

Based on the above conditions, the following results were obtained by performing a simulation for tracing each optical path for 100,000 rays using a predetermined calculation formula. FIG. 6 schematically shows the optical path trajectory of each light beam in this simulation.・ Average number of passes through the surface: 15.828860 ・ Average number of re-incidents of the lamp: 4.380950 ・ Right end loss: 0.0000810 ・ Left end loss: 0.00007930 ・ Loss inside the lamp: 0.437010 ・ Reflection loss: 0.0554530 The number of light reaching the light guide plate (to the end face 11f of the light guide plate 11): 48972 (incidence efficiency to the light guide plate: 0.48972) That is, in this example, the lamp 13 and the reflector 14 are coaxially arranged as before. Under the arrangement, the incidence efficiency on the light guide plate 11 is about 0.49 (49%).

In a similar manner, the scattering reflectance of the lamp /
Simulation calculations were performed with various changes in the scattered transmittance, and the results were compared with experimental examples, and the effect of the thickness of the light guide plate 11 at the light incident portion (light guide plate thickness) on the incident efficiency was examined. The results are shown in the graph of FIG. In FIG.
Two numerical values described on the right side of each calculation example indicate the scattering reflectance / scattering transmittance of the lamp in each calculation example. For example, “Calculation Example 5 (0.65 / 0.30)” is calculated as Calculation Example 5
The scattering reflectance / scattering transmittance of the lamp at 0.65 was 0.65.
/0.30 (65% / 30%). Further, in FIG. 7, the incident efficiency in each case is represented by a ratio (incident efficiency ratio) to a reference value based on the incident efficiency when the thickness of the light guide plate is 1.5 mm.
From the graph of FIG. 7, it was confirmed that as the thickness of the light guide plate (the thickness of the light guide plate 11 at the light incident portion) increases, the (incident) efficiency ratio increases. In addition, it can be seen that the above-described simulation calculation relatively agrees with the experimental result (indicated by a circle in FIG. 7).

Further, in this embodiment, since the average thickness of the lid housing 6 can be set to be larger, the flow of molten metal in die casting of the lid housing 6 is improved, and castability can be improved. . FIG. 8 shows that the plane size is approximately A
4 sizes (Japanese Industrial Standard A row No.4: 21cm wide x 2 vertical)
When casting the lid housing 6 (9.7 cm) by the Mg die casting method, the yield (%) and plate thickness (mm) of non-defective products without casting defects such as "hot water wrinkle", "hike" and "nest" 6 is a graph showing an example of the relationship with. As can be seen from this graph, the yield greatly depends on the plate thickness. As the average thickness of the lid housing 6 increases, the castability improves, and the yield of the casting material can be increased.

Next, the specific setting of the curved surface shape of the mounting surface of the light guide plate 11 and the inner wall surface of the lid housing 6 will be described. In the present embodiment, when this curved surface shape is determined, as shown in FIGS. 9 to 12, the tangent angle α to the assembly surface at the lamp-side end (light incident portion) of the light guide plate 11,
Four types of samples are set by changing the thickness (Ta + Tb) of the light incident portion of the light guide plate 11 and the radius of curvature Rg of the inner wall surface of the lid housing 6 to calculate the effect on display characteristics on the display. , The numerical range of the tangent angle α is set.
Table 1 shows the simulation conditions for each sample (Sample 1 to Sample 4). These samples 1
Sample 4 corresponds to FIGS. 9 to 12, respectively.

[0027]

[Table 1]

Also, in the above simulation, an example of the optical path of each light ray when light incident on the light guide plate 11 from the lamp 13 is reflected by the curved surface portion of the light guide plate 11 and emitted to the outside of the light guide plate 11 will be described. FIG. Thereby, the distribution of the amount of light emitted to the outside of the light guide plate 11 can be known. In the present embodiment, a graph is obtained by obtaining the light emission amount according to the longitudinal position of the light guide plate 11 for the light guide plate 11 having a different tangent angle α to the assembly surface at the lamp-side end (light entrance portion). The effect of the difference in the tangent angle α on the display characteristics on the display was examined. The results are shown in FIGS.

14 to 16, the horizontal axis indicates the position from the center of the lamp 13, and the vertical axis indicates the amount of light emitted from the light guide plate 11 to the display side at each position (the emitted light is a particle). Is the number counted as). If this light emission exceeds the relative average light emission of the display panel to which it is applied, it appears as a bright line on the display panel corresponding to the location where the light is emitted. The greater the extent exceeding the relative average light emission, the more the display uniformity is impaired. In the present embodiment, 12'1 "(about 3
The display uniformity was evaluated based on the relative average light emission amount (approximately 56) of a display panel having a size of about 07 mm) and the presence or absence of a region exceeding the range.

As shown in FIG. 14, the tangent angle α to the assembly surface at the lamp-side end (light entrance) of the light guide plate 11
Is about 86 degrees (86.2 degrees), the area exceeding the above relative average light emission amount is very large, and the degree of exceeding is also large. Therefore, the display uniformity on the display is considerably deteriorated. On the other hand, as shown in FIG.
When the tangent angle α is 89 degrees (89.0 degrees), there is no region exceeding the relative average light emission amount, and good display uniformity is secured. Further, as shown in FIG. 15, when the tangent angle α is about 88 degrees (88.1 degrees), the area exceeding the relative average light emission amount exists but is only a small part. The extent to which it exceeds is also slight.
In such a case, for example, the back surface side of the light guide plate 11 (housing 6
By applying a conventionally known method, such as devising the arrangement of the reflection dots provided on the side of the mounting surface to the surface (e.g., the surface to be assembled), the luminance can be made uniform and good display uniformity can be secured. It is quite possible to do so.

In the present embodiment, based on the above results, the lower limit of the tangent angle α to the assembly surface at the lamp-side end of the light guide plate 11 is set to 87 degrees. By setting the lower limit in this way, good display uniformity on the display can be ensured. On the other hand, the upper limit value of the tangent angle α is set to 89 degrees with respect to the critical value of 90 degrees from the viewpoint of permitting variation in processing accuracy within a certain range and securing manufacturability. That is, by setting the tangent angle α in the range of 87 ° to 89 °, the mounting surface of the light guide plate 11 and the inner wall surface of the lid housing 6 are formed in a curved shape on the light incident side of the light guide plate 11. In this case, good display uniformity on the display can be ensured, and the ease of manufacture is not impaired.

In the color liquid crystal display device 5, RGB (Red (Red), Green (Green), Blue (Blue)) are used.
A color filter composed of colors and configured so that one pixel corresponds to one color of the color filter is incorporated. In the present embodiment, a spectral type color filter is used as the color filter. Hereinafter, this color filter and its arrangement structure will be described. FIG.
FIG. 2 is an explanatory view schematically showing a cross-sectional structure of the color liquid crystal display device 5. As shown in FIG. 3, the above-described guide having a reflective sheet 12 disposed on the back side (the lower side in the figure) is shown in FIG. A lens sheet 17 is disposed between the light plate 12 and the liquid crystal panel unit 20. The liquid crystal panel unit 20 includes a liquid crystal panel 21 (TFT array substrate) having a gap portion 21c for enclosing liquid crystal between two glass substrates 21a and 21b, and a TFT array substrate 21.
Polarizing plates 26A, 2 arranged so as to sandwich
6B, and the polarizing plates 26A and 26B are bonded and fixed to the corresponding glass substrates 21a and 21b, respectively.

In this embodiment, a color filter 28 having a filter substrate 28a is arranged between the TFT array substrate 21 and the light guide plate 11 (specifically, between the lens sheet 17). A so-called spectral type is used. As is well known, the spectral type color filter 28 selectively passes a light component of a specific color in accordance with the wavelength of light, and a light component of a color that does not pass is reflected by the filter 28. ing. Therefore, two colors other than the color concerned are absorbed in each part corresponding to one pixel, and the incoming white light is filtered by a color filter, such as a generally used pigment type of absorption type. It is not greatly (1/3) narrowed down.

As described above, in the present embodiment, the color filter 28 is provided between the liquid crystal panel 21 and the light guide plate 11.
And the color filter 28 is of a spectral type, so that light (white light: white light) traveling from the light guide plate 11 through the lens sheet 17 to the liquid crystal panel 21 side.
(Refer to the solid arrow in the figure) first enter the spectral filter 28. In the spectral filter 28, as described above, the light components other than the color passing through the filter 28 in each part corresponding to one pixel. Is reflected. Then, the reflected light component is reversely reflected (to the liquid crystal panel 21 side) by the reflection sheet 12 disposed on the back surface side (the opposite side to the liquid crystal panel side) of the light guide plate 11 and again returned to the spectral filter 2.
8, at this time, when the light enters a filter portion that transmits the light component, the light passes through the filter 28.

By repeating this until all the light components reflected by the spectral filter 28 finally pass through the spectral filter 28, conventionally, the white light passing through the absorption type color filter is reduced to 1/3 by the filter. Compared with the case where the aperture is narrowed down, the efficiency of use of light that enters the light guide plate 11 and travels toward the liquid crystal panel 21 is greatly improved. In particular, since the spectral filter 28 is disposed not on the exit side of the liquid crystal panel 21 but on the entrance side of the liquid crystal panel 21 (between the light guide plate 11) with respect to the light path, the color reflected by the spectral filter 28 is Since the light component is immediately reflected by the reflection sheet 12 and travels to the spectral filter 28 side without passing through the liquid crystal panel 21, there is no fear that the reflected light component is absorbed by the liquid crystal panel 21, and the use of light is further improved. Efficiency can be increased.

In the present embodiment, the positional relationship between the lamp 13 and the reflector 14 surrounding the lamp 13 is set so that the center position of the lamp 13 is eccentric from the center of the reflector 14. Next, an arrangement structure of the lamp 13 with respect to the reflector 14 will be described. In the present embodiment, various simulations are performed by using the same method as the above-described simulation calculation in order to investigate the influence of the relative positional relationship between the lamp 13 and the reflector 14 on the efficiency of light incidence on the light guide plate 11. Was done.

In this simulation, as shown in FIG. 18, the lamp 13 was moved in an oblique direction at 45 degrees with respect to the reflector 14, so that both were eccentrically arranged, and the eccentric amount was changed to perform the simulation. In the drawings, the direction in which the lamp 13 is decentered outward (toward the side away from the light guide plate: obliquely upward to the left) with respect to the reflector 14 is defined as the positive direction on the horizontal axis of the graph. Further, in this graph, Example 1 indicated by a black circle (●) indicates the case where the scattering reflectance / scattering transmittance of the lamp is 0.65 / 0.25, and Example 2 indicated by the black triangle indicates the scattering of the lamp. Reflectance / scattered transmittance = 0.
The case of 65 / 0.30 is shown respectively. The simulation results are as shown in the graph of FIG.
Regardless of the value of the lamp's scattered reflection / transmission,
In any direction, the eccentric arrangement of the lamp 13 with respect to the reflector 14 is more coaxial (the lamp position: 0.0).
0 mm), it was found that higher incidence efficiency was obtained.

Further, when the lamp 13 and the reflector 14 are decentered along the longitudinal direction of the light guide plate 11, and after the reflector 14 itself is deflected along the end face 11f of the light guide plate 11, the lamp 13 is further deflected. With respect to the case where the reflector was decentered with respect to the reflector, a simulation for examining the efficiency of incidence on the light guide plate was performed. FIGS. 19 to 21 schematically show the optical path trajectories of light rays in each case of the present simulation. The first example shown in FIG. 19 and the second example shown in FIG.
In the example, the lamp 13 is connected to the light guide plate 11 with respect to the reflector 14.
In the third example shown in FIG. 21, the reflector 14 itself is deflected along the end face 11f of the light guide plate 11 and the lamp 1 is further deflected.
3 shows a case where the reflector 3 is eccentric with respect to the reflector 14.

Table 2 shows simulation conditions and results (incidence efficiency) for each of the first to third examples.
In Table 2, the “distance from the light guide plate” is the reflector 1
The distance from the center of the light guide plate 4 to the end face 11f of the light guide plate 11 and the “reflector bias height” indicate the amount of deviation of the center of the reflector 14 when the reflector 14 is biased along the end face 11f of the light guide plate 11. , Respectively. The "lamp position" is represented by (x, y) coordinates, where the longitudinal direction of the light guide plate 11 is the x direction, and the direction along the end face 11f of the light guide plate 11 is the y direction.

[0040]

[Table 2]

From the simulation results shown in Table 2, in each case, the lamp 13 was connected to the reflector 1
It has been found that the eccentric arrangement with respect to No. 4 provides higher incidence efficiency than the coaxial arrangement. Based on the above results, in the present embodiment, the center position of the lamp 13 is eccentric from the center of the reflector 14, more preferably at least in the longitudinal direction of the light guide plate 11 from the center of the reflector 14. It was set to be cored. Thereby, the lamp 1 is compared with a case where the lamp 13 is conventionally set to be coaxial with the reflector 14.
3, the efficiency of light incidence on the light guide plate 11 can be increased.

As described above, according to the present embodiment, the mounting surface of the light guide plate 11 and the inner wall surface of the lid housing 6 are formed on the light incident side of the light guide plate 11 as curved surfaces.
The display device 5 can be made thinner while securing the efficiency of light incidence from the lamp 13 to the light guide plate 11 and the required thickness of the lid housing 6, and the liquid crystal panel 21 and the light guide plate 11 By arranging the color filter 28 of the spectral type in between, it is possible to increase the utilization efficiency of light incident on the light guide plate 11. Further, by setting the center position of the lamp 13 to be eccentric from the center of the reflector 14, the position of the lamp 13 from the lamp 13 to the light guide plate 11 is smaller than that of the related art in which the lamp is set to be coaxial with the reflection plate. The light incident efficiency can be further improved. It should be noted that the present invention is not limited to the embodiments described above, and it is needless to say that various improvements or design changes can be made without departing from the gist of the present invention.

[0043]

According to the first aspect of the present invention, since the light guide plate is assembled along a predetermined inner wall surface of the housing via the reflection sheet, the reflection sheet is
While being held down by the light guide plate, it is held between the back surface of the light guide plate and the inner wall surface of the housing. That is, the reflection sheet can be assembled on the back surface side (the side opposite to the liquid crystal panel) of the light guide plate with a very simple configuration without using any special assembling means. Also, the mounting surface of the light guide plate and the inner wall surface of the housing are formed into a curved surface with a predetermined curvature so that the thickness of the light guide plate at least at the end on the lamp side and the vicinity thereof continuously changes. Since the thickness of the end of the light guide plate on the lamp side (light incident portion) is secured, the thickest part of the light guide plate on the lamp side and the standard thickness part or the end on the opposite side of the lamp are inclined. Compared to the conventional method of connecting with a plane,
The average thickness of the light guide plate can be reduced. That is,
Under the condition that the wall thickness of the combined light guide plate and housing is limited to a certain value or less, the average thickness of the housing can be set to be thicker while ensuring the efficiency of light incidence from the lamp to the light guide plate. The strength and rigidity of the housing can be increased. That is, it is possible to achieve a reduction in thickness while ensuring the efficiency of light incidence from the lamp to the light guide plate and the required thickness of the housing. Further, when the casing is formed as a cast product, the flow of molten metal during casting is improved, and castability can be improved. In this case, since the mounting surface of the light guide plate and the inner wall surface of the housing are formed in a curved shape, the thickest portion of the light guide plate on the lamp side and the standard thickness portion or the end opposite to the lamp are provided. Unlike the related art in which the light guide plate is connected with an inclined plane, there is no possibility that the light guide plate will be broken in the middle, and there is no fear that the display on the display will have an adverse effect such as a bright line.

Further, according to the invention of claim 2 of the present application, basically the same effects as those of the invention of claim 1 can be obtained. In particular, the tangent angle of the light guide plate at the end on the lamp side with respect to the mounting surface is set to 87 to 8 degrees.
Since the angle is set to a range of 9 degrees, it is necessary to ensure good display uniformity on the display when forming the light guide plate assembling surface and the inner wall surface of the lid housing on the light incident side of the light guide plate in a curved shape. And ease of manufacture is not impaired.

Further, according to the third aspect of the present invention, the color filter is arranged between the liquid crystal panel and the light guide plate, and the color filter is of a spectral type. Light traveling toward the liquid crystal panel first enters the spectral filter. In this filter, light components other than the color passing through the filter in each portion corresponding to one pixel are reflected. Then, the reflected light component is applied to the back side of the light guide plate (the side opposite to the liquid crystal panel).
(Refer to the LCD panel side)
The light is reflected and travels again to the spectral filter. At this time, when the light enters the filter portion that transmits the light component, the light passes through the filter. By repeating this until all the light components reflected by the spectral filter finally pass through the spectral filter, the white light passing through the absorption type color filter is conventionally narrowed down to 1/3 by the filter. As compared with the above, the use efficiency of light incident on the light guide plate and traveling toward the liquid crystal panel can be greatly increased. In particular, the spectral filter
Since the light path is arranged not at the exit side of the liquid crystal panel but at the entrance side of the liquid crystal panel (between the light guide plate), the light component of the color reflected by the spectral filter is immediately reflected without passing through the liquid crystal panel. Since the light is reflected by the sheet and travels toward the spectral filter, there is no concern that the reflected light component is absorbed by the liquid crystal panel, and the light use efficiency can be further improved.

Further, according to the invention of claim 4 of the present application, since the center position of the lamp is set to be eccentric from the center of the reflector, the lamp is conventionally concentric with the reflector. The efficiency of light incidence from the lamp to the light guide plate can be increased as compared with the case where the position is set to be as follows.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a computer according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view schematically showing a basic structure of a display device of the computer.

FIG. 3 is an explanatory longitudinal sectional view showing a state where the light guide plate and the lamp of the display device are assembled to a lid housing.

FIG. 4 is an explanatory vertical cross-sectional view showing, on an enlarged scale, a state in which a lamp-side end of the light guide plate is assembled to a lid housing.

FIG. 5 is a diagram illustrating a typical example of a simulation calculation of the incident efficiency to the light guide plate.

FIG. 6 is an explanatory diagram schematically showing an optical path trajectory in a typical example of a simulation calculation of the incident efficiency to the light guide plate.

FIG. 7 is a graph showing the effect of the thickness of the light guide plate on the ratio of incidence efficiency to the light guide plate.

FIG. 8 is a graph showing the relationship between the yield of a cast product by the Mg die casting method and the plate thickness.

FIG. 9 is an explanatory longitudinal sectional view of a light guide plate of Sample 1 and a curved surface portion of a lid housing.

FIG. 10 is an explanatory vertical sectional view of a curved portion of a light guide plate and a lid housing of a sample 2;

FIG. 11 is an explanatory longitudinal sectional view of a curved surface portion of a light guide plate and a lid housing of a sample 3;

FIG. 12 is an explanatory vertical sectional view of a curved portion of a light guide plate and a lid housing of a sample 4;

FIG. 13 is an explanatory diagram schematically showing an example of an optical path of each light ray reflected on a curved surface portion of the light guide plate and emitted to the outside.

FIG. 14 is a graph showing a light emission amount distribution when a tangent angle is 86 degrees.

FIG. 15 is a graph showing a light emission amount distribution when the tangent angle is 88 degrees.

FIG. 16 is a graph showing a light emission distribution when a tangent angle is 89 degrees.

FIG. 17 is an explanatory diagram schematically showing a cross-sectional structure of the color liquid crystal display device 5 according to the present embodiment.

FIG. 18 is a graph showing the effect of the lamp position on the efficiency of light incidence on the light guide plate.

FIG. 19 is an explanatory diagram schematically showing an eccentric state and an optical path trajectory in a first example of a simulation in which a lamp and a reflector are eccentrically arranged.

FIG. 20 is an explanatory diagram schematically showing an eccentric state and an optical path trajectory in a second example of a simulation in which a lamp and a reflector are eccentrically arranged.

FIG. 21 is an explanatory view schematically showing an eccentric state and an optical path trajectory in a third example of a simulation in which a lamp and a reflector are eccentrically arranged.

FIG. 22 is an explanatory sectional view of a light guide plate according to Conventional Example 1.

FIG. 23 is an explanatory side view of a light guide plate according to Conventional Example 2.

[Explanation of symbols]

5 liquid crystal display device, 6 lid housing, 11 light guide plate, 12 reflection sheet, 13 lamp, 14 reflector (reflection plate), 21 liquid crystal panel, 28 color filter, α tangent angle.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tomohiro Sasakawa 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Inventor Shin Kawabe 2-3-2 Marunouchi, Chiyoda-ku, Tokyo 2-3 Rishi Electric Co., Ltd.

Claims (4)

[Claims] 1. A transmissive liquid crystal panel, a light guide plate for guiding illumination light to the liquid crystal panel, and a lamp disposed on one side of the light guide plate. In the liquid crystal display device, the light guide plate is assembled along a predetermined inner wall surface of the housing via a reflection sheet, and the light guide plate has a thickness at least at an end on the lamp side and in the vicinity thereof. A liquid crystal display device, wherein an assembling surface of the light guide plate and an inner wall surface of the housing are formed into a curved surface having a predetermined curvature so that the light guide plate continuously changes. 2. The liquid crystal display device according to claim 1, wherein a tangent angle of the light guide plate at an end on the lamp side with respect to a mounting surface is set in a range of 87 to 89 degrees. 3. A liquid crystal display device comprising: a transmission type liquid crystal panel having a color filter; a light guide plate for guiding illumination light to the liquid crystal panel; and a lamp arranged on at least one side of the light guide plate. A liquid crystal display device, wherein the color filter is arranged between the liquid crystal panel and the light guide plate, and the color filter is of a spectral type. 4. An arrangement structure of a lamp for a liquid crystal display device, which is arranged on at least one side of a light guide plate of a transmission type liquid crystal panel and supplies illumination light to the liquid crystal panel via the light guide plate, wherein the lamp is The light guide plate is surrounded by a substantially cylindrical reflector that is open only on the light guide plate side, and the center position of the lamp is set to be eccentric from the center of the reflector. Layout structure of lamp for liquid crystal display device.