JP2008096555A - Sidelight type backlight for dual-screen liquid crystal display device, and dual-screen liquid crystal display device equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sidelight type backlight for a dual-screen liquid crystal display device with which favorable display quality is maintained for each observation region when used for the dual-screen liquid crystal display device, and the dual-screen liquid crystal display device equipped with the sidelight type backlight. <P>SOLUTION: The sidelight type backlight 3 for the dual-screen liquid crystal display device is used for the dual-screen liquid crystal display device 1 with which mutually different image displays are conducted on mutually different two observation regions, and comprises first and second light sources 13A, 13B mounted on two side walls of a rectangular light guide plate 14 placed opposite to each other, wherein light emitted from the first light source 13A has directivity to predominantly irradiate one observation region imparted thereto, and light emitted from the second light source 13B has directivity to predominantly irradiate the other observation region imparted thereto, and the first and second light sources 13A, 13B are provided with characteristics different from each other. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a sidelight-type backlight for a two-screen liquid crystal display device and a two-screen liquid crystal display device including the same, and in particular, provides a first image in a first observation area and a second in a second observation area.
In a so-called two-screen liquid crystal display device that provides an image of the above, a sidelight type backlight capable of realizing a display suitable for each of the first and second observation regions, and a two-screen liquid crystal display device provided with the sidelight type backlight About.

Conventionally, a liquid crystal display device using a liquid crystal panel for display (LCD; Liquid Crystal Display, hereinafter abbreviated as “LCD”) or the like is known as a display device mounted on a television receiver or information equipment. Yes. With respect to display devices such as liquid crystal display devices, two screens that provide a first image in a first observation area and a second image in a second observation area with the recent diversification of information equipment and the like Display devices are known.

A two-screen display device according to this conventional example will be described with reference to the drawings. FIG. 4 is a cross-sectional view illustrating a display device according to a conventional example. As shown in FIG. 4, the display device according to the conventional example includes
A display panel 52 is disposed in which first pixel columns 51a for displaying a first image and second pixel columns 51b for displaying a second image are alternately arranged. Here, the first and second pixel columns 51a and 51b are formed of pixels including a liquid crystal layer, for example. Also, a so-called black matrix 53 is formed between the pixels of the first and second pixel columns 51a and 51b. A light shielding plate 54 made of metal or resin having a light shielding function is disposed above the display panel 52 via a transparent substrate such as a glass substrate (not shown). The light shielding plate 54 is the first
The pixel rows 51a and the second pixel rows 51b are provided with light shielding portions 55 and openings 56 that alternately extend in parallel.

Next, a mechanism for realizing two-screen display with the above configuration will be described. As shown in FIG. 4, the first image from the first pixel row 51 a passes through the opening 56 of the light shielding plate 54 in the first observation region A that is leftward from the position C in front of the display panel 52. Provided. At this time, the second image of the second pixel column 51b is not provided to the first observation area A because it is blocked by the light blocking portion 55 of the light blocking plate 54.

On the other hand, a second image is provided from the second pixel row 51 b through the opening 56 of the light shielding plate 54 to the second observation region B that is separated from the position C in front of the display panel 52 in the right direction. At this time, since the first image of the first pixel row 51a is blocked by the light blocking portion 55 of the light blocking plate 54,
It is not provided for the second observation region B. In this way, a two-screen display is performed in which the first image is provided in the first observation area A and the second image is provided in the second observation area B. In addition, the following patent document 1 is mentioned as a technical document relevant to this application.

Further, as a two-screen display device as described above, a technique for controlling display / non-display of two observation areas by giving a backlight a predetermined directivity is also introduced in the patent literature (
For example, see Patent Document 2 below). FIG. 5 is a cross-sectional view showing a side light type surface light source device disclosed in Patent Document 2 shown below together with a peripheral configuration.

As shown in FIG. 5, the sidelight type surface light source device 60 disclosed in the following Patent Document 2 receives the first illumination light 62 emitted from the first light source 61 from the end face 63A. A first light guide plate 63 that bends the illumination light 62 and emits the light from the exit surface 63 </ b> B, and a second illumination light 65 emitted from the second light source 64. While entering from the end surface 66A, the first illumination light 62 emitted from the first light guide plate 63 is incident from the back surface 66B facing the emission surface 66C, and the first and second illumination lights 62 and 65 are emitted from the emission surface. A second light guide plate 66 that emits light from 66C, and is directed in a first emission direction by the first illumination light 62 and in a second emission direction by the second illumination light 65 different from the first emission direction. It has sex.
The first and second light guide plates 63 and 66 are each formed of a plate-like member having a wedge-shaped cross section, and are overlapped so that the end surfaces 63A and 66A face each other, whereby the first and second light sources 6 are arranged.
Desirable directivity can be obtained for the first and second illumination lights 62 and 65 emitted from the first and second illumination lights 64. A prism sheet, a diffusion plate, and the like are placed on the upper surface of the sidelight type surface light source device 60, and then a liquid crystal display panel is placed to assemble a liquid crystal display device. In this liquid crystal display device, if one of the first and second light sources 61 and 64 is turned off, a display image from the corresponding emission direction cannot be obtained, and display / non-display control can be performed depending on the observation region. Become.
JP 2005-258016 A JP 11-273438 A (Claim 1, paragraphs [0023] and [0026], FIG. 2)

By the way, when the conventional two-screen display device is mounted on a vehicle as an in-vehicle car navigation device, for example, the navigation screen is displayed with one observation area of the display screen facing the driver's seat side, It is conceivable to use such a manner that a TV image, a DVD image or the like is displayed with the observation area facing the passenger seat side. In such a case, a difference may occur in the quality of the light source required depending on the observation area. That is, the driver's seat side has a higher demand for high luminance characteristics than color reproduction characteristics in order to display a navigation screen. In addition, when a warning is displayed to the driver on the navigation screen, there is a demand for red display in order to emphasize the warning. On the other hand, in order to display a DVD image such as a movie on the passenger seat side, it is preferable that the color reproduction characteristic is as good as possible over the high luminance characteristic.

However, the first and second light sources 61 and 64 of the sidelight type surface light source device 60 disclosed in Patent Document 2 both use cold cathode fluorescent tubes and have different display quality for each of the two observation regions. No consideration is given to display.

In view of the above problems, the present inventors have studied various backlights that can obtain different demands depending on two observation areas, that is, high brightness and high red display, or high color reproduction characteristics. The present inventors have found that the above-described problems can be solved by using a backlight using a light source, and have reached the present invention.

That is, an object of the present invention is to provide a sidelight-type backlight for a two-screen liquid crystal display device capable of maintaining a suitable display quality for each observation region when used in a two-screen liquid crystal display device, and the sidelight-type backlight. It is to provide a two-screen liquid crystal display device provided.

In order to achieve the above object, the invention of a sidelight type backlight for a two-screen liquid crystal display device according to claim 1 of the present invention is a two-screen liquid crystal capable of displaying different images in two different observation areas. Used in the display device, first and second on two opposing side walls of the rectangular light guide plate
A sidelight type backlight provided with a light source of
The emitted light from the first light source is provided with directivity so as to irradiate light around one observation region,
The emitted light from the second light source is given directivity so as to irradiate light around the other observation area,
The first and second light sources each have different characteristics.

According to a second aspect of the present invention, in the sidelight type backlight for a two-screen liquid crystal display device according to the first aspect, the first light source has higher luminance characteristics than the second light source. And the second light source has a higher color reproduction characteristic than the first light source.

According to a third aspect of the present invention, in the sidelight type backlight for a two-screen liquid crystal display device according to the second aspect, the first light source is a pseudo white LED.

According to a fourth aspect of the present invention, in the sidelight-type backlight for a two-screen liquid crystal display device according to the second aspect, the first light source includes a pseudo white LED and a red LED. To do.

According to a fifth aspect of the present invention, in the sidelight-type backlight for a two-screen liquid crystal display device according to the second aspect, the second light source is a blue color using a red light-emitting phosphor and a green light-emitting phosphor. It consists of LED or a cold cathode fluorescent tube.

Further, the invention of the two-screen liquid crystal display device according to claim 6 is a sidelight type backlight for the two-screen liquid crystal display device according to any one of the first to fifth aspects,
A liquid crystal display panel on which two images are displayed in order to display different images in two different observation areas;
A light-shielding means that shields an image other than the corresponding region of the two images displayed on the liquid crystal display panel so that only different images are observed in the two different observation regions. To do.

By providing the above configuration, the present invention has the following excellent effects. That is, according to the invention of the sidelight type backlight for the two-screen liquid crystal display device of the present invention, the light is emitted around one of the two different observation regions existing along the incident direction. A first light source having directivity and a second light source having directivity so as to be emitted around the other observation region are used, and characteristics (spectrums) are used as the first and second light sources, respectively. By using different ones, it is possible to display the display quality that meets the needs in each of the two observation regions by appropriately changing the light source according to different needs in each observation region.

According to the invention of claim 2, for example, when this sidelight-type backlight is used in a vehicle-mounted two-screen liquid crystal display device, the driver seat side that often displays a navigation screen has directivity. The light source has higher luminance characteristics than the second light source, and DV
Display that matches the displayed contents by providing a second light source having directivity on the passenger side, which often displays images of D, etc., with higher color reproduction characteristics than the first light source. Quality can be maintained.

According to the third aspect of the present invention, when a pseudo white LED is used as the first light source, particularly high luminance characteristics can be obtained, so that a display suitable for particularly bright display is possible.

According to the invention of claim 4, high luminance characteristics can be obtained by using a package of a pseudo white LED and a red LED as the first light source, and a warning display to the driver in the navigation screen, etc. Red display which is often used can be displayed clearly.

According to the invention of claim 5, if a blue LED using a red light emitting phosphor and a green light emitting phosphor is used as the second light source, red (R), green (G), blue (B) Therefore, a particularly high color reproduction characteristic can be obtained. If a cold cathode fluorescent tube is used, a display with a high color reproduction characteristic can be achieved.

According to the invention of the two-screen liquid crystal display device of claim 6, the two-screen liquid crystal display device which can obtain the above-described effect by combining the above-mentioned side light type backlight with the two-screen liquid crystal display panel is provided. Will be able to.

Hereinafter, the best embodiment of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies a sidelight type backlight for a two-screen liquid crystal display device and a two-screen liquid crystal display device including the same for embodying the technical idea of the present invention. The invention is not intended to be specific to these, and other embodiments within the scope of the claims are equally applicable.

FIG. 1 is a plan view showing a two-screen liquid crystal display device according to an embodiment of the present invention, and FIG.
It is the schematic sectional drawing cut | disconnected by A line.
As shown in FIGS. 1 and 2, the two-screen liquid crystal display device 1 of the present invention is disposed on the back of the two-screen liquid crystal display panel 2 and a two-screen liquid crystal display panel 2 that displays different images on the left and right. It is comprised from the sidelight type backlight 3 and the front frame 4 which hold | maintains these integrally. In the two-screen liquid crystal display device 1, as shown in FIG. 4 of the conventional example, two different observation areas are set in the left-right direction in FIG. 1, and different image displays are made in the two observation areas. It has become so. The two-screen liquid crystal display device 1 need not always display different images in two different observation areas, and may display the same image in two observation areas. That is, the two-screen liquid crystal display device 1 can be switched by selecting whether to display the same image or to display different images in two different observation areas.

Among these, as shown in FIG. 2, the sidelight-type backlight 3 is disposed on the inner surface of the outer case 11 and the outer case 11 having a rectangular bottom surface and having side walls with a predetermined height at the four ends. The reflection sheet 12 and the light sources 13A and 13B provided along the inner surfaces of a pair of opposite side walls of the side wall of the outer case 11, and the light source 13A in the outer case 11
13B, a rectangular light guide plate 14 disposed between 13B, a rectangular prism sheet 15 disposed on the upper surface of the light guide plate 14, and a rectangular diffusion disposed on the upper surface of the prism sheet 15. Board 1
6 and an intermediate frame 17 for fixing each of the above-described members in the exterior case 11.

The outer case 11 is made of a thin metal material, and the reflection sheet 12 is made of a sheet material having a high light reflectance made of a PET film or the like attached over the entire inner surface of the outer case 11. Further, the prism sheet 15 is irradiated with light 1 irradiated through the light guide plate 14.
The diffusing plate 16 is made of a light diffusing sheet material, and the intermediate frame 17 is a frame-shaped member made of synthetic resin or the like, and has a diffusing plate on its inner surface. 1
6 is provided with a projection 17a for supporting the outer peripheral portion of the upper surface, and a step portion 17b on which the outer peripheral edge of the two-screen liquid crystal display panel 2 is placed is provided on the inner upper surface.

Each of the light sources 13A and 13B has a plurality of light emitting diodes (Light Emitting Diodes, hereinafter simply referred to as LEDs) having different characteristics, that is, emission spectrums, arranged along the opposing side walls of the outer case 11, and the irradiation surfaces thereof are respectively It arrange | positions in the exterior case 11 so that it may go to the one side end surface of the light-guide plate 14. As shown in FIG. Then, among these two LEDs 13A and 13B, a pseudo-white LED (a white LED that performs white display with a blue LED chip and a yellow phosphor excited thereby) is used as the LED 13A that illuminates one observation region, and the other observation is performed. It is preferable to use a blue LED using a red light-emitting phosphor and a green light-emitting phosphor as the LED 13B that illuminates the region. It is known that the pseudo white LED has a significantly higher intensity in the blue wavelength range than that in the green or red wavelength range, and has high luminous efficiency and high luminance characteristics. On the other hand, a blue LED using a red light emitting phosphor and a green light emitting phosphor has a substantially uniform intensity in each of the red, blue, and green wavelength regions and emits light using three colors of R, G, and B. It is known that the color reproduction characteristics are close.

The light guide plate 14 is formed of a plate-like body having a wall thickness that can be accommodated in the outer case 11. For example, in a matrix made of polymethyl methacrylate (PMMA), translucent fine particles having a refractive index different from that are uniformly distributed. It is formed by being dispersed and mixed in. And on the bottom surface is a reflection sheet 12
LED13A and 13B are arranged so that the irradiation surface is in contact with one opposing side wall surface. The light emitted from the LEDs 13A and 13B may be provided with directivity so that it can be emitted to different regions by using two light guide plates having a wedge-shaped cross section as in the prior art of Patent Document 2 above. Directivity may be imparted so that light can be emitted to different regions by changing the shape of the bottom surface of the light guide plate with one light guide plate. Moreover, directivity may be imparted to the light emitted from the LEDs 13A and 13B by devising the pattern of the reflection sheet 12. It is not necessary to provide directivity so that all the light emitted from the LEDs 13A and 13B goes to different areas, and directivity so that most of the light emitted from one light source goes to one area. And directivity should be given so that most of the light emitted from the other light source goes to the other region. This is because a part of the light emitted from one light source inevitably exists toward the other region by being reflected by a member constituting the backlight.

The two-screen liquid crystal display panel 2 included in the two-screen liquid crystal display device 1 of the present invention has a first pixel column for displaying the first image and a second image for displaying the second image, as in the conventional example described above. Above the liquid crystal display panel in which the pixel columns are alternately arranged, the first pixel column and the second pixel are made of a metal or resin having a light shielding function via a transparent substrate such as a glass substrate (not shown). A light-shielding plate having light-shielding portions and openings extending alternately and in parallel to the pixel columns is used. The light-shielding plate shields the other pixel column in one observation region so that only one pixel column is visible, and the other observation region shields one pixel column so that only the other pixel column is visible. For example, a display panel different from the liquid crystal display panel may be prepared, and a portion that blocks light and a portion that transmits light may be realized depending on the display state. In other words, any device having means capable of shielding light other than the image in the corresponding region can be applied so that only the image in the corresponding region is observed. Since the two-screen display method is the same as that of the conventional example described above, description thereof is omitted.

When assembling the above-described two-screen liquid crystal display device 1 composed of each component, first, the reflection sheet 12 is disposed on the inner surface of the outer case 11, and then on one opposing side wall surface in the outer case 11. The light sources 13A and 13B are disposed so as to be in contact with each other, and the light guide plate 14 is disposed between the light sources 13A and 13B. Next, the prism sheet 15 and the diffusion plate 16 are sequentially placed on the upper surface of the light guide plate 14, and the intermediate frame 17 is attached so as to cover the upper surface of the outer case 11, and the above-described components are fixed. Then, the two-screen liquid crystal display panel 2 is fixed so that the outer edge portion is placed on the step portion 17 b of the intermediate frame 17, and finally the front frame 4 is attached for assembly.

In the two-screen liquid crystal display device 1 assembled in this way, the irradiation light 18A emitted from one light source 13A enters the light guide plate 14 and is reflected by the reflection sheet 12,
The prism sheet 15 is adjusted in its directing direction and is emitted in the right direction in FIG. 2. On the contrary, the irradiation light 18B emitted from the other light source 13B enters the light guide plate 14 and is reflected. After being reflected by the sheet 12, the direction of the direction is adjusted by the prism sheet 15, and the light is emitted in the left direction in FIG. As a result, the irradiation direction is different for each of the two light sources 13A and 13B.

Two irradiation lights 18A, 18 having different directions emitted from the two-screen liquid crystal display panel 2 are used.
B has a predetermined angle, for example, 30 °, with respect to a perpendicular (not shown) whose emission direction extends perpendicularly to the front direction of the two-screen liquid crystal display panel 2. This is an angle at which the highest luminance characteristic can be obtained when viewed from two observation areas, and this angle can be arbitrarily changed in accordance with the use application.

The above-described two-screen liquid crystal display device 1 is most effective particularly when used as a liquid crystal display device including an in-vehicle navigation device. That is, when a navigation screen is displayed on the driver's seat side and a TV image or a DVD image is displayed on the passenger seat side, the navigation screen displayed on the driver's seat side has a clearer display than the high color reproduction characteristics. Therefore, the brightness of the display screen is increased by using a pseudo white LED like the light source 13A, and the DVD image displayed on the passenger seat side, specifically, a movie or the like has a high color. Since reproduction characteristics are required, a display that meets the needs of each observation region, such as using a blue LED using a red light-emitting phosphor and a green light-emitting phosphor as in the light source 13B, enhances the color reproduction characteristics. The quality can be adjusted.

In the above embodiment, a pseudo white LED is used as the LED 13A and a blue LED using a red light emitting phosphor and a green light emitting phosphor is used as the LED 13B. However, the present invention is not limited to this. Accordingly, as a modification of the above-described embodiment, a light source 13 in which a red LED is packaged in addition to a pseudo white LED is used as one light source.
An example in which A ′ is used and a cold cathode fluorescent tube is used as the other light source 13B ′ will be described. FIG. 3 is a sectional view of a two-screen liquid crystal display device according to a modification of the present invention. Further, since the two-screen liquid crystal display device 1 ′ of the present modification has only the light source of the two-screen liquid crystal display device 1 of the above-described embodiment changed, the same components are denoted by the same reference numerals and the description thereof is omitted. Omitted.

As shown in FIG. 3, the two-screen liquid crystal display device 1 ′ according to this modification uses a side light type backlight 3 ′ having a package of pseudo white LED and red LED as one light source 13A ′. The other light source 13B ′ uses a cold cathode fluorescent tube 19A. The other light source 13B ′ is composed of a cold cathode fluorescent tube 19A and a reflector 19B disposed so as to surround the periphery excluding its irradiation surface. By adopting such a configuration, as one of the light sources 13A ′, usually, a pseudo white LED is used for display, and in an emergency situation, a red LED is used in addition to a white LED, or only a red LED is used. Thus, the red display can be performed clearly. For example, when red is used as a warning display when displaying a navigation screen, a clear display is possible, and the driver's recognition can be further enhanced. Further, as the other light source 13B ′, the cold cathode fluorescent tube 19A is provided without arranging a plurality of LEDs.
By using, it is possible to realize a screen display having high color reproduction characteristics.

FIG. 1 is a plan view showing a two-screen liquid crystal display device according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view taken along line AA in FIG. FIG. 3 is a sectional view of a two-screen liquid crystal display device according to a modification of the present invention. FIG. 4 is a cross-sectional view illustrating a display device according to a conventional example. FIG. 5 is a cross-sectional view showing a conventional sidelight type surface light source device together with peripheral components.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 2 screen liquid crystal display device 2 2 screen liquid crystal display panel 3 Sidelight type backlight 4 Front frame 11 Exterior case 12 Reflection sheet 13A, 13A ', 13B, 13B' Light source (LED)
14 Light guide plate 15 Prism sheet 16 Diffusion plate 17 Intermediate frames 18A, 18B Irradiation light 19A Cold cathode fluorescent tube 19B Reflector

Claims (6)

A sidelight that is used in a two-screen liquid crystal display device capable of displaying different images in two different observation areas, and in which first and second light sources are disposed on two opposing side walls of a rectangular light guide plate Mold backlight,
The emitted light from the first light source is provided with directivity so as to irradiate light around one observation region,
The emitted light from the second light source is given directivity so as to irradiate light around the other observation area,
The sidelight backlight for a two-screen liquid crystal display device, wherein the first and second light sources have different characteristics. The first light source has higher luminance characteristics than the second light source, and the second light source has higher color reproduction characteristics than the first light source. Item 2. A sidelight-type backlight for a two-screen liquid crystal display device according to Item 1. The side light backlight for a two-screen liquid crystal display device according to claim 2, wherein the first light source is a pseudo white LED. 3. The first light source includes a pseudo white LED and a red LED.
A side-light type backlight for a two-screen liquid crystal display device as described in 1. The side light type backlight for a two-screen liquid crystal display device according to claim 2, wherein the second light source comprises a blue LED or a cold cathode fluorescent tube using a red light emitting phosphor and a green light emitting phosphor. . A sidelight type backlight for a two-screen liquid crystal display device according to any one of claims 1 to 5,
A liquid crystal display panel on which two images are displayed in order to display different images in two different observation areas;
A light-shielding means that shields an image other than the corresponding region of the two images displayed on the liquid crystal display panel so that only different images are observed in the two different observation regions. Two-screen liquid crystal display device.

Images