JP4711541B2 - Lighting panel, liquid crystal display device and portable terminal or display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an illumination panel including a light guide made of a transparent material, and relates to an illumination panel called a backlight used for a display device such as a liquid crystal display device. Furthermore, the present invention relates to a liquid crystal display device using this illumination panel. The present invention also relates to a portable terminal or a display device provided with this liquid crystal display device.
[0002]
[Prior art]
A liquid crystal display device widely used in a mobile terminal typified by a mobile phone uses a so-called backlight to illuminate a display unit (liquid crystal display device) that performs image display.
[0003]
According to this portable terminal, miniaturization and low power consumption are demanded. For this reason, further miniaturization and low power consumption are required for the liquid crystal display device.
[0004]
As a backlight for a liquid crystal display device that meets such a demand, an edge light type backlight system using a light emitting diode (hereinafter abbreviated as LED) is generally used.
[0005]
An illumination panel (backlight) using such an edge light system will be described with reference to FIGS.
[0006]
FIG. 5 is a schematic plan view of the backlight 1 (however, the casing and the light shielding plate are omitted), and FIG. 6 is a schematic cross-sectional view of the liquid crystal display device 2 on which the backlight 1 is mounted.
[0007]
According to the backlight 1, the light guide plate 3 made of a transparent material, the LED 4 disposed on the end surface of the light guide plate 3, the light shielding plate 5 for preventing the light of the LED 4 from leaking to the outside, and the LED 4 for mounting It comprises a substrate 6 and a diffusion plate 7 disposed on the light exit surface side of the light guide plate 3 in order to diffuse the light that has entered the light guide plate 3.
[0008]
Furthermore, as a condensing sheet for condensing the light emitted from the diffusion plate 7, for example, at least one lens sheet 8 is disposed on the diffusion plate 7, and the surface facing the light emission surface of the light guide plate 3 Is provided with a reflection plate 9.
[0009]
The liquid crystal display panel 10 is disposed on the backlight 1 having such a configuration, and the backlight unit 1 and the liquid crystal display panel 10 are supported and fixed by a housing 11.
[0010]
When the liquid crystal display device 2 having the above configuration is used for a portable terminal, it is required to reduce the power consumption and to reduce the size of the terminal. Along with such a size reduction, the liquid crystal display device 2 has similar characteristics. Required.
[0011]
That is, the liquid crystal display device 2 is required to have a narrow frame, and the distance between the effective display area 12 of the liquid crystal display panel 10 and the LED 4 (displayed as “l” in FIG. 6) is increased as compared with the prior art. Close to each other.
[0012]
As described above, due to the proximity of the effective display area 12 of the liquid crystal display panel 10 and the LED 4, the luminance in the vicinity of the LED 4 becomes extremely high, and luminance unevenness occurs in the effective display area 12 in the vicinity of the LED 4 of the liquid crystal display panel 10. Was.
[0013]
The brightness unevenness also occurred at the following points.
[0014]
In this point, the light emitted from the LED 4 is incident on the light guide plate 3 at a certain angle θ. For this reason, the distance between the LED 4 and the effective display area 12 is close as shown in FIG. A low luminance portion 13 is present inside.
[0015]
In addition, since the luminance is extremely high in the vicinity of the LED 4, the difference between the low luminance portion and the high luminance portion becomes luminance unevenness, which is one of the factors that impair the display quality of the liquid crystal display panel 10.
[0016]
FIG. 7 shows the state of occurrence of luminance unevenness.
This figure shows the relationship between the distance from the LED 4 and the luminance in the lines x3 and x4 shown in FIG. 5, the horizontal axis represents the distance from the LED 4, and the vertical axis represents the luminance.
[0017]
As shown in FIG. 7, according to the x3 line, the luminance of the effective display area 12 near the LED 4 is high, and in the other x4 line, the luminance of the effective display area 12 near the LED 4 is low. Further, as the difference between the luminance along the x3 line and the luminance along the x4 line in the effective display area 12 becomes larger, the luminance unevenness becomes more prominent. However, as shown in FIG. The difference Δx (3-4) tends to stand out.
[0018]
In order to eliminate such luminance unevenness, the following techniques have been proposed.
There has been proposed a technique for adjusting the distribution density of the pattern on the back surface of the light guide plate formed by cylindrical projections according to the amount of light of the LED to make the emitted light on the light guide plate surface uniform (see JP-A-11-72787). ).
[0019]
Alternatively, in a backlight using a linear light source such as a fluorescent tube, a technique for making the emitted light on the surface of the light guide plate uniform by applying a light absorbing layer to a diffusion plate or a reflector near the light source has been proposed. (See JP-A-8-240720 and JP-A-10-161119).
[0020]
[Problems to be solved by the invention]
However, the following problems have arisen in the above-described prior art.
[0021]
In order to meet market needs for downsizing and low power consumption of portable devices in recent years, the distance between the effective display area 12 of the liquid crystal display panel 10 and the light source is closer than ever. An LED is generally used as a light source for a backlight of a portable device.
[0022]
Therefore, when a point light source such as an LED is close to the effective display area 12 of the liquid crystal display panel 10, the above-described conventional technology can relax strong light near the light source and provide good display quality. The current situation is very difficult.
[0023]
The present invention has been completed in view of the above description, and its purpose is to provide a point light source, which reduces brightness unevenness on the light exit surface, or provides a high-performance lighting panel that eliminates such unevenness. It is to provide.
[0024]
Another object of the present invention is to provide a liquid crystal display device using the illumination panel of the present invention as a backlight.
[0025]
Still another object of the present invention is to provide a portable terminal or a display device that achieves miniaturization and high display performance using the liquid crystal display device of the present invention.
[0026]
[Means for Solving the Problems]
An illumination panel of the present invention is made of a transparent material, and has a light guide plate having a light incident surface and a light output surface, a plurality of point light sources arranged to face the light incident surface of the light guide plate, and light from the light guide plate A diffusing plate disposed opposite to the emission surface, and the diffusing plate is formed with a dot pattern whose light hiding property decreases as the distance from the point light source increases.In plan view, the dot pattern is: When the perpendicular line is drawn from the point light source to the light incident surface of the light guide plate, the adjacent point is located on the perpendicular line and exists corresponding to each of the plurality of point light sources. When the perpendicular line is drawn from the center between the light sources to the light incident surface of the light guide plate, the minimal part is located on the perpendicular line, and the maximal part and the minimal part are connected by an arcuate curve. In this case, the dot pattern Emissions is, the arc-shaped curve, along the arrangement direction of the point light source, a pattern formed by a plurality continuously.
[0027]
The liquid crystal display device of the present invention includes the illumination panel according to the present invention, and a liquid crystal display panel that is disposed opposite to the illumination panel and has an effective display area, and the maximum portion and the minimum portion are the Located in the effective display area .
[0028]
The portable terminal of the present invention includes the liquid crystal display device according to the present invention .
[0029]
The display device of the present invention includes the liquid crystal display device according to the present invention .
[0030]
Therefore, according to a liquid crystal display device used in a device such as a portable terminal, particularly a miniaturized liquid crystal display device, luminance unevenness in a liquid crystal display device with a narrow frame is alleviated, and the display uniformity in the display region is improved. As a result, a liquid crystal display device with high display quality, a portable terminal, and a display device can be obtained.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a light-absorbing dot pattern diagram arranged on a light reflecting member arranged on one main surface of the light guide plate, or a pattern of light-shielding dots arranged on a light diffusion member arranged on the other main surface. FIG. 2 is a schematic plan view of the illumination panel (backlight 14) of the present invention, and FIG. 3 is a schematic cross-sectional view of a liquid crystal display device 15 on which the backlight 14 is mounted. In these drawings, the same members are denoted by the same reference numerals in FIGS.
[0032]
According to the backlight 14, the LED 4 as the point light source is arranged on the end face of the light guide plate 3 made of a transparent material, and the light shielding plate 5 for preventing the light of the LED 4 from leaking to the outside, and the LED 4 for mounting. A substrate 6 is provided.
[0033]
In order to diffuse the light that has entered the light guide plate 3, a diffusion plate 7 that is the light diffusion member is provided on the light exit surface side of the light guide plate 3 that is the other main surface. As a condensing sheet for condensing light, for example, at least one lens sheet 8 is disposed on the diffusion plate 7.
[0034]
A reflecting plate 9 serving as the light reflecting means is provided on a surface facing the light emitting surface of the light guide plate 3 serving as the one main surface.
[0035]
The liquid crystal display panel 10 is disposed on the backlight 14 having such a configuration, and the backlight 14 and the liquid crystal display panel 10 are supported and fixed by the housing 11.
[0036]
In the present invention, the light-absorbing dots are arranged on the reflection plate 9 arranged on one main surface of the light guide plate 3, and the light-shielding dots are arranged on the diffusion plate 7 arranged on the other main surface. In this example, the light shielding layer 16 is formed on the lower surface of the diffusion plate 7.
[0037]
FIG. 1 shows a dot pattern of the light shielding layer 16 in terms of an arrangement relationship with the LED 4. In the figure, each dot 17 is printed in a circle with, for example, a UV curable white ink, and the light hiding ratio is changed by changing the diameter size. If the size is increased, the light concealing property is increased.
[0038]
In the present invention, as the distance from the vicinity of the LED 4 increases, the area of the dots 17 gradually decreases, so that the light concealment rate per unit area decreases, and a so-called gradation shape is obtained.
[0039]
The light shielding layer 16 is mainly intended to block the emitted light from the exit surface of the light guide plate 3, but a part of the emitted light is absorbed by the light shielding layer 16. However, its absorption rate is very low.
[0040]
Therefore, most of the light emitted from the light guide plate 3 is reflected inside the light guide plate 3 by the light concealing layer 16 and is recycled. As a result, it can be said that there is little light loss.
[0041]
FIG. 4 shows the occurrence of uneven brightness.
This figure shows the relationship between the distance from the LED 4 and the luminance along the lines x1 and x2 shown in FIG. 2, the horizontal axis represents the distance from the LED 4, and the vertical axis represents the luminance.
[0042]
As shown in FIG. 4, according to the x1 line, the brightness of the effective display area 12 near the LED 4 is lowered by the light shielding layer 16. Further, the luminance difference Δx (1-2) from the end of the effective display area 12 near the LED 4 in the x2 line becomes smaller, and the luminance unevenness is reduced as the luminance difference Δx (1-2) becomes smaller.
[0043]
According to an experiment conducted by the present inventor, when NSCW 215 (light emission angle θ: 115 °) manufactured by Nichia Chemical is used for the LED 4 and the distance t between the LEDs 4 is 18 mm, the light shielding layer 16 is not required. The distance l for obtaining the display quality was 5.7 mm.
[0044]
That is, in the model used in this experiment, when the distance 1 between the LED 4 and the effective display area 12 is smaller than 5.7 mm, the display quality of the liquid crystal display device is impaired.
[0045]
On the other hand, in a liquid crystal display device with a narrow frame having a distance l <5.7 mm as in the present invention, the provision of the light concealing layer 16 can suppress strong light in the vicinity of the LED 4, which is favorable. Display quality was obtained.
[0046]
This point will be described with reference to FIG. 11 for reference.
A good display can be obtained without the need for the light shielding layer 16 when the low luminance portion 13 shown in FIG. 5 does not exist.
[0047]
As shown in FIG. 11, assuming that the distance between the LED 4 and the effective display area 12 is l, the intersection of the emitted light of the adjacent LEDs 4 is a, and the vertical distance between the LED 4 and the intersection a is l ′, low when l = l ′. The luminance part 13 does not exist.
[0048]
At this time, the following relational expression holds.
tan (θ / 2) = (t / 2) / l ′
l ′ = (t / 2) / tan (θ / 2)
Then, when applying the numerical values of this embodiment (t = 18, θ = 115)
l '= (18/2) / tan (115/2) = 5.7 mm
Therefore, if l ′ = 5.7 mm, the low luminance portion 13 does not exist and a good display can be obtained.
[0049]
On the other hand, when l <l ′ (= 5.7), the low luminance portion 13 exists, and thus the light hiding layer 16 is necessary.
[0050]
Next, when the distance between the LEDs 4 is further increased and t = 24 mm, the distance l at which good display quality is obtained is 7.6 mm. When the distance l is further reduced, the light shielding layer 16 is required.
[0051]
That is, when t = 24 and θ = 115 are applied, l ′ = (24/2) / tan (115/2) = 7.6 mm
Therefore, in the case of l <l ′ (= 7.6), the low brightness portion 13 exists, and thus the light hiding layer 16 is necessary.
[0052]
Thus, according to the present invention, the condition for obtaining a good display quality by disposing the light concealing layer 16 differs depending on the type of LED to be used (light emission angle θ) and the interval t between adjacent LEDs. In the liquid crystal display device 15 in which the distance l between the LED 4 and the effective display area 12 of the liquid crystal display panel 10 is close, if the relationship satisfies l <(t / 2) / tan (θ / 2), the light hiding layer 16 By disposing, it is possible to obtain a particularly effective effect, alleviate the luminance unevenness of the liquid crystal display panel 10, and obtain a good display quality.
[0053]
Such a range definition means that the low-luminance portion 13 exists, but when the low-luminance portion 13 is present, the light non-uniformity of the liquid crystal display panel is alleviated by providing the light-shielding layer 16, which is favorable. A display is obtained.
[0054]
According to the present invention, as another embodiment, for example, a light absorbing layer having the same shape as the dot pattern described above is provided on the reflector 9 instead of providing a light concealing layer on the diffusion plate 7. May be. Alternatively, a light hiding layer may be formed on the diffusion plate 7 and a light absorption layer may be formed on the reflection plate 9 at the same time.
[0055]
Further, when the light absorbing layer is disposed on the reflecting plate side, a good effect can be obtained if it is dark brown such as black or gray. That is, in order to control the light from the light source on the reflecting plate side, a means for partially absorbing the reflected light is adopted, but at that time, dark brown such as black or gray is easy to absorb the light and is more effective. Demonstrated.
[0056]
Furthermore, instead of the dot pattern having the shape and arrangement as shown in FIG. 1, the dot pattern is optimally controlled and adjusted according to the level of luminance unevenness of the liquid crystal display. May be used.
[0057]
8 is an enlarged cross-sectional view of a main part of the liquid crystal display panel 10 of the present invention, FIG. 9 is a schematic view of a mobile phone 18 as an example of the mobile terminal of the present invention, and FIG. 10 is a schematic view of another mobile terminal 19. is there.
[0058]
Liquid crystal display panel 10 of the present invention
The liquid crystal display panel 10 shown in FIG. 8 will be described in detail.
A phase difference plate 21 made of polycarbonate or the like and an iodine type polarizing plate 22 are sequentially stacked on one main surface of the liquid crystal panel 20, and a phase difference plate 23 made of polycarbonate or the like and an iodine type polarizing plate 24 on the other main surface. Are stacked one after another. These are attached using an adhesive material made of an acrylic material.
[0059]
Further, a backlight 14 is disposed on the polarizing plate 24 side.
[0060]
In the liquid crystal panel 20, reference numerals 25 and 26 denote a segment-side glass substrate and a common-side glass substrate, and a transparent electrode made of ITO arranged in parallel as a striped electrode group on the glass substrate 25. 27 and an alignment film (not shown) made of polyimide resin rubbed in a certain direction are sequentially formed. An insulating layer made of SiO ₂ or the like may be interposed between the transparent electrode 27 and the alignment film.
[0061]
A semi-transmissive film 28 is formed on the inner surface of the glass substrate 26, and a colored portion 29 that forms a color filter is provided on the semi-transmissive film 28. Further, a thin film made of a metal such as aluminum or chromium or a black matrix that is a light shielding film formed of a photosensitive resist may be formed between the colored portions 29.
[0062]
Then, an overcoat layer 30 made of SiO ₂ or resin is coated on the colored portion 29, and a transparent electrode 31 made of ITO arranged in parallel as a striped electrode group on the overcoat layer 30, and fixed An alignment film (not shown) made of polyimide resin rubbed in the direction is sequentially formed. The transparent electrode 31 is orthogonal to the transparent electrode 27. An insulating layer made of SiO ₂ or the like may be provided between the transparent electrode 31 and the alignment film.
[0063]
The semi-transmissive film 28 has both light-transmitting properties and light-reflecting properties, and prevents a phase difference from occurring when sandwiched between two polarizing plates. Further, the semi-transmissive film 28 may be specular or may have a scattering property. In order to produce the translucent film 28 having scattering properties, it is only necessary to form a concavo-convex shape with a resin and to form a semipermeable film thereon.
[0064]
The colored portion 29, which is the color filter, is formed by photolithography by applying a photosensitive resist previously prepared by a pigment dispersion method, that is, a pigment (red, green, blue, etc.) on a substrate.
[0065]
The glass substrates 25 and 26 thus formed, for example, are bonded together with a sealant 33 through a liquid crystal layer 32 made of chiral nematic liquid crystal twisted at an angle of 200 to 270 °. Further, a large number of spacers 34 are arranged between the glass substrates 25 and 26 in order to make the thickness of the liquid crystal layer 32 constant.
[0066]
In the liquid crystal display device 15 having the semi-transmissive film 28 arranged as described above, when used as a reflection type (reflection mode), the irradiation light by external illumination such as sunlight or fluorescent lamp is not polarized. 22, the phase difference plate 21, and the liquid crystal panel 20 sequentially pass, but the light incident on the liquid crystal panel 20 passes through the colored portion 29 that is a color filter and reaches the semi-transmissive film 28, and then semi-transmissive The light is reflected by the film 28, passes through the liquid crystal panel 20, passes through the phase difference plate 21 and the polarizing plate 22, and is emitted.
[0067]
On the other hand, when the liquid crystal display device 15 is set to the transmission mode, the irradiation light of the backlight 14 sequentially passes through the polarizing plate 24, the phase difference plate 23, and the glass substrate 26 of the liquid crystal panel 20, and the semi-transmissive film 28. , Passes through the colored portion 29, which is a color filter, passes through the liquid crystal panel 20, passes through the retardation plate 21 and the polarizing plate 22, and is emitted.
[0068]
Such a semi-transmissive film 28 is, for example, a metal thin film such as aluminum, chromium, SUS, or Ag. When the film thickness increases, the light transmittance decreases and the light reflectivity increases. The thickness of such a metal thin film has a different light absorption coefficient depending on the type of metal, and is also defined by which of the applications of the reflection mode and the transmission mode is required to improve performance. Usually, it is good to make it 50-500cm, preferably 100-400cm. As a result, the transflective liquid crystal display device having a reflectance of 30 to 70% and a transmittance of 5 to 50% can be obtained.
[0069]
For example, when the semi-transmissive film 28 is formed of an aluminum metal thin film having a thickness of 250 mm, the reflectance is 65% and the transmittance is 15%.
[0070]
The semi-transmissive film 28 may be formed by a dielectric half mirror instead of the metal thin film. That is, a laminated structure in which the low refractive index layer and the high refractive index layer are alternately laminated may be formed, whereby a part of the light incident through the liquid crystal 32 is reflected by the high refractive index layer and other high refractive indexes. The light transmitted through the layer is reflected by the low refractive index layer, and these reflected lights interfere with each other, so that the reflection performance is remarkably enhanced and so-called increased reflection occurs.
[0071]
The high refractive index layer and the low refractive index layer may be made of any material as long as there is a difference in refractive index between them. For example, the refractive index range of the high refractive index layer is 2 0.0 to 2.8 is preferable, and TiO ₂ , ZrO ₂ , SnO ₂ or the like is preferable. Range of the refractive index of the low refractive index layer is 1.3 to 1.6 selfishness to this, for example _{SiO 2, AlF 3, CaF 2} , may be configured MgF ₂ or the like.
[0072]
When the thickness range of the high refractive index layer is 25 to 2000 mm and the thickness range of the low refractive index layer is 25 to 2000 mm, the above-described increased reflection becomes most remarkable. By laminating them and making the thickness range of the semi-transmissive film 28 be 50 to 14,000 mm, this increased reflection becomes remarkable.
[0073]
Further, the semi-transmissive film 28 has a laminated structure in which a high refractive index layer and a low refractive index layer are alternately and sequentially laminated, so that the total number of each layer is 2, 4, 6, 8 or 10 layers or more. The number of layers is configured.
[0074]
Furthermore, in the case of such a stacked structure, the reflectance and transmittance can be set as required by changing the number of stacked layers, and the design becomes easy.
[0075]
For example, in the case of a laminated structure sequentially laminating alternately the low refractive index layer made of SiO ₂ and (200~1500Å) high refractive index layer made of TiO ₂ and (200~1000Å), was the total number 16 layers The reflectance is 75% and the transmittance is 25%.
[0076]
Mobile phone 18 of the present invention
The mobile phone 18 equipped with the liquid crystal display device 15 will be described with reference to FIG.
[0077]
According to the cellular phone 18, the liquid crystal display device 15 is disposed in a small casing 35. Further, an antenna 36 for transmission / reception is provided on the top of the casing 35, and a receiver is provided on the surface. 37 and a microphone 38 are formed.
[0078]
Portable terminal 19 of the present invention
The portable terminal 19 provided with the liquid crystal display device 15 will be described with reference to FIG. The mobile terminal 19 is shown as various information terminals other than the mobile phone 18. For example, there are clocks, calculators, game machines, pedometers, GPS, POS, handy terminals, industrial instruments, and the like, but are not limited to these.
[0079]
Also in the portable terminal 19, the liquid crystal display device 15 is disposed in a small casing 39.
[0080]
It should be noted that the present invention is not limited to the above embodiment, and various modifications and improvements can be made without departing from the scope of the present invention. For example, in the above-described embodiment, the STN type simple matrix type color liquid crystal display device is described. However, other than the bistable type simple matrix type color and monochrome liquid crystal display device and monochrome type STN type simple matrix. The same operation and effect can be obtained even when the liquid crystal display device is a TN type simple matrix type liquid crystal display device.
[0081]
Furthermore, the following modifications may be possible.
(1) In the liquid crystal display device 15, the phase difference plate 21 and the phase difference plate 23 are provided on both surfaces of the liquid crystal panel 10, but the phase difference plate 21 or the phase difference plate 23 is provided only on one of the surfaces. It may be provided.
(2) In the liquid crystal display device 15, the semi-transmissive film 28 is formed and used for the transmissive mode and the reflective mode. However, the transmissive liquid crystal display device in the transmissive mode may be used without forming the semi-transmissive film 28. .
(3) The device provided with the liquid crystal display device of the present invention is exemplified by a portable terminal, but can be applied to various devices using the liquid crystal display device as a display device. For example, it may be used for display boards of various display devices such as sewing machines, stereos, musical instruments, videos, ATMs, copying machines, facsimiles, stations, restaurants, and display panels in factories.
[0082]
【The invention's effect】
As described above, in the illumination panel of the present invention , a light guide plate made of a transparent material and having a light incident surface and a light output surface, and a plurality of point light sources arranged to face the light incident surface of the light guide plate, A diffusion plate disposed opposite to the light exit surface of the light guide plate, and the diffusion plate is formed with a dot pattern whose light concealing property decreases as the distance from the point light source increases. The dot pattern is located on the vertical line when a perpendicular line is drawn from the point light source to the light incident surface of the light guide plate, and a maximum portion exists corresponding to each of the plurality of point light sources. A minimum portion located on the perpendicular when a perpendicular is drawn from the center between the adjacent point light sources to the light incident surface of the light guide plate, and the maximum and the minimum are circular. When tied with an arcuate curve There are, the dot pattern, the arc-shaped curve, along the arrangement direction of the point light source, than a pattern formed by a plurality continuously, the brightness becomes extremely high in the vicinity a point light source As a result, the difference between the low-luminance portion and the high-luminance portion is eliminated. As a result, uniform luminance is obtained over the effective display area, and the display device is also narrowed.
[0083]
Further, in the present invention, according to a liquid crystal display device used in a device such as a portable terminal, particularly a miniaturized liquid crystal display device, luminance unevenness in a narrow frame liquid crystal display device is alleviated and display uniformity in the display region is achieved. As a result, a downsized liquid crystal display device with high display quality was obtained.
[0084]
Furthermore, according to the present invention, by using the liquid crystal display device of the present invention, a portable terminal and a display device having a small size and a high display quality can be provided.
[Brief description of the drawings]
FIG. 1 is a light-absorbing dot pattern diagram arranged on a light reflecting member or a light diffusing member disposed on a light guide plate.
FIG. 2 is a schematic plan view of a lighting panel according to the present invention.
FIG. 3 is a schematic cross-sectional view of a liquid crystal display device of the present invention.
FIG. 4 is a diagram showing a relationship between an effective display area and luminance in the lighting panel of the present invention.
FIG. 5 is a schematic plan view of a conventional lighting panel.
FIG. 6 is a schematic cross-sectional view of a conventional liquid crystal display device.
FIG. 7 is a diagram showing a relationship between an effective display area and luminance in a conventional lighting panel.
FIG. 8 is an enlarged cross-sectional view of a main part of the liquid crystal display device according to the present invention.
FIG. 9 is a schematic view of a mobile phone according to the present invention.
FIG. 10 is a schematic view of a mobile terminal according to the present invention.
FIG. 11 is an enlarged schematic plan view of a main part of the illumination panel of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Backlight 2 ... Liquid crystal display device 3 ... Light guide plate 4 ... LED
7 ... Diffuser 9 ... Reflector 10 ... Liquid crystal display panel 12 ... Effective display area 13 ... Low luminance part 14 ... Backlight 16 ... Light hiding layer 17 ... Dot 18 ... mobile phone 19 ... mobile terminal

Claims (3)

A light guide plate made of a transparent material and having a light incident surface and a light output surface;
A plurality of point light sources arranged to face the light incident surface of the light guide plate;
A diffusion plate disposed opposite to the light exit surface of the light guide plate,
The diffusing plate is formed with a dot pattern whose light hiding property decreases as the distance from the point light source increases.
In a plan view, the dot pattern is located on the perpendicular line when the perpendicular line is drawn from the point light source to the light incident surface of the light guide plate, and exists corresponding to each of the plurality of point light sources. And a local minimum located on the perpendicular when a perpendicular is drawn to the light incident surface of the light guide plate from the center between the adjacent point light sources,
In the case where the maximum portion and the minimum portion are connected by an arc-shaped curve, the dot pattern is a pattern in which a plurality of the arc-shaped curves are continuously formed along the arrangement direction of the point light sources. The lighting panel characterized by being. A lighting panel according to claim 1;
A liquid crystal display panel disposed opposite to the illumination panel and having an effective display area,
The maximum part and the minimum part are liquid crystal display devices located in the effective display area.   A portable terminal or display device comprising the liquid crystal display device according to claim 2.

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