JPH11219124A - Display device - Google Patents

Abstract

(57) [Summary] [Problem] To easily form a shadow without a gap on a display image without using a complicated device. SOLUTION: A light diffusion filter 13 is arranged in parallel with a polymer-dispersed liquid crystal plate 11 at a separation distance d, and a back light source 12 is illuminated from the back with a diagonal to the normal direction of the polymer-dispersed liquid crystal plate 11. The light diffusion region (background 32) and the transparent region (display image 31) of the polymer dispersed liquid crystal plate 11 and the light incident regions Ar1 and Ar2 of the light diffusion filter 13
The display image 31 is formed with no gaps by a combination of the superimposition with the light non-incident regions Ar3 and Ar4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device such as an instrument panel used in a moving body such as an automobile, an aircraft or a ship.

[0002]

2. Description of the Related Art For mobile objects such as automobiles, operation information of accessories such as a reception frequency of a radio and a set temperature of an air conditioner is displayed on a dash on which operation units of various accessories are provided. It is displayed in the center of the board. It is desirable that such information not only ensures the safety of the driving operation by making the display contents easy to see, but also enables a comfortable information confirmation by improving the aesthetic appearance.

[0003] As one of display methods for improving the appearance of a display for displaying characters and pictures by light emission, as shown in FIG. 5, a display image 1 of characters and pictures is displayed three-dimensionally with shading 2 added thereto. There is something to do.

Here, if the display image 1 and the shadow 2 are not distinguished and recognized, a three-dimensional effect is not produced, so that it is necessary to display the display image 1 and the shadow 2 so that they can be distinguished by any method.

As one means for identification, it is conceivable that the display image 1 and the shadow 2 are composed of different segments. That is, as shown in FIG. 5, by providing a gap 3 having a slight width between the display image 1 and the shade 2, the boundary between the two is clarified.

In this case, the minimum size of the gap 3 between the segments is determined by the type of the display, and does not become smaller than a certain value. For this reason, there is a problem that a gap between the display image 1 and the shade 2 becomes too large, and a three-dimensional effect is hardly perceived.

In order to solve such a problem, a method of superimposing the display contents of two or more displays having different colors and lightness to produce characters and shades is conceivable, but the device becomes large-scale.

SUMMARY OF THE INVENTION An object of the present invention is to provide a display device capable of providing a three-dimensional display by adding a solid shadow to a display image such as a character or a picture without using a complicated device. Is to do.

[0009]

Means for Solving the Problems In order to solve the above problems,
A display element for forming a transparent area as a display image with respect to a light diffusion area as a background,
A light diffusion filter that is disposed substantially parallel to the front surface of the display element at a predetermined separation distance and transmits the light incident from behind to the front side while diffusing light, and diagonally toward the back surface of the display element. And a back light source for irradiation.

According to a second aspect of the present invention, in the display device, a predetermined transparent electrode is formed on surfaces facing each other.
A polymer having a plurality of transparent substrates and a polymer-dispersed liquid crystal layer sandwiched between the two transparent substrates, wherein a scattering state of incident light changes with a change in an applied voltage applied by the two transparent electrodes. A dispersion type liquid crystal plate is used.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The display device of the present invention provides a display image by coating a surface of a polymer-dispersed display panel with a light diffusion filter and irradiating a back light source (backlight) on the back side from an oblique direction. Is to add a shadow.

FIG. 1 is a principle view showing an outline of a display device according to an embodiment of the present invention, and FIG. 2 is a perspective view thereof. As shown in FIGS. 1 and 2, this display device has a polymer-dispersed liquid crystal plate 11 for displaying a transparent region and a light-diffusing region arbitrarily changed, and a rear end of the polymer-dispersed liquid crystal plate 11. And a light diffusion filter 13 arranged in parallel on the surface side of the polymer-dispersed liquid crystal plate 11 with a distance d therebetween.

As shown in FIG. 3, the polymer-dispersed liquid crystal plate 11
Transparent substrates 21 and 29 made of two glass substrates or transparent resin substrates having transparent electrodes 23 and 27 such as ITO (indium-tin-oxide) films formed on surfaces facing each other.
And a polymer-dispersed liquid crystal layer 25 sandwiched between the transparent substrates 21 and 29.
The polymer-dispersed liquid crystal layer 25 is switched between a transparent state and a light diffusion state (white turbid state). The transparent electrodes 23 and 27, the polymer-dispersed liquid crystal layer 25, and the transparent substrates 21 and 29 are formed to have a predetermined thickness by various vapor deposition techniques, and in particular, are metal films. The transparent electrodes 23 and 27 are formed as ultra-thin films capable of transmitting light to ensure transparency.

The polymer-dispersed liquid crystal layer 25 is composed of a composite film (composite) of a predetermined polymer and liquid crystal, and is provided with NCAP.
(Nematic curvilinear alig
Need phase) type or PN (polymer ne)
2) type liquid crystal is used. In the polymer-dispersed liquid crystal layer 25, when no voltage is applied, the liquid crystal in the liquid crystal layer 25 is oriented in a random direction, causing a difference in the refractive index between the polymer and the liquid crystal. Due to the large decrease, the film has a cloudy appearance. On the other hand, when a voltage is applied, the liquid crystal is arranged in the direction of the electric field, the refractive indices of the polymer and the liquid crystal match, and the incident light is transmitted without being scattered, so that it has a transparent appearance.

The polymer-dispersed liquid crystal layer 2
In order to display predetermined visual information, a plurality of pixel portions arranged in a matrix for image formation, a predetermined shape and a predetermined arrangement state are provided on the polymer-dispersed liquid crystal plate 11 having The liquid crystal layer 25 and the transparent electrodes 23 and 27 sandwiching the liquid crystal layer 25 form a plurality of segment portions provided or a display cell portion formed in the shape of a figure or symbol associated with predetermined information. .

Here, as the material of the transparent electrodes 23 and 27, a material having a high electron injection efficiency to the polymer dispersed liquid crystal layer 25, such as Mg / Ag, Al / Li, or Al / LiF, is selected.

The display of the polymer-dispersed liquid crystal panel 11 is controlled by a predetermined control unit 15. This control unit 15
Is an image processing circuit using a general CPU, which operates according to a predetermined display driver program (software program) pre-recorded in a predetermined recording device. Both transparent electrodes 23, 2 in the pixel portion, each segment portion, or the display cell portion
The scattered state of light in the liquid crystal layer 25 is controlled by controlling the DC voltage applied between the layers 7 to form a partially transparent region in the polymer-dispersed liquid crystal layer 25 having an opaque light-diffusing property. It has become.

As shown in FIG. 1, a general daylight white light bulb or the like is used for the back light source 12, and the back light source 12 is inclined at an angle φ from the normal L1 of the polymer-dispersed liquid crystal panel 11 (ie, as shown in FIG. 1). It is displaced by a first angle φ1 (> 0 °) in the horizontal direction and by a second angle φ2 (> 0 °) in the vertical direction. In particular, a straight line from the back light source 12 as viewed from the viewer Po. In order to prevent light from being transmitted through the polymer dispersed liquid crystal panel 11 and reflected,
The rear light source 12 is disposed so as to be shifted outward from the display effective surface Ra (FIG. 2) of the polymer dispersed liquid crystal panel 11. Specifically, the back light source 12 is a polymer-dispersed liquid crystal plate 11.
Is desirably housed in a holding frame (not shown) or the like. The light emission of the back light source 12 is independent of the control of the application of the polymer dispersed liquid crystal layer 25 by the control unit 15,
At least during operation of the display device, light emission is always performed.

The light-diffusing filter 13 is a cloudy light-transmitting plate having a light-transmitting property and having a light-diffusing property by arranging internal molecular arrangements in various directions. In order to maintain parallelism with the polymer-dispersed liquid crystal plate 11 at a distance d, a hard material such as translucent hard resin such as translucent glass or epoxy is used.

In the display device having the above configuration, the control unit 1
5 operates in accordance with a predetermined display driver program (software program) pre-recorded in a predetermined recording device, and displays both transparent portions for each pixel portion, each segment portion, or each display cell portion of the polymer dispersed liquid crystal panel 11. Electrodes 23, 2
7 to control the light scattering state of the liquid crystal layer 25. As shown in FIGS. 3 and 4, a transparent region is formed in the voltage application region in the polymer dispersed liquid crystal layer 25. While this portion is used as a display image 31 such as a character or a picture, a cloudy light diffusion region is held in a non-voltage region, and such a portion is used as a display background 32.

Here, in FIG. 1, the polymer-dispersed liquid crystal plate 11 has an inclination of θ with respect to the vertical direction. Further, as described above, the light diffusion filter 13 is disposed in parallel with the polymer-dispersed liquid crystal plate 11 at a distance d. Further, the light from the rear light source 12 is inclined at an angle φ with respect to the normal L1 of the polymer-dispersed liquid crystal panel 11 (that is,
Irradiation is performed in a direction shifted by a first angle φ1 (> 0 °) in the horizontal direction and by a second angle φ2 (> 0 °) in the vertical direction. Here, for simplicity, the description will be made assuming that the irradiation light from the back light source 12 is parallel.

Now, as shown in FIG.
The width of the transparent display image 31 formed in No. 1 is L. Then, it is assumed that the polymer-dispersed liquid crystal plate 11 is observed from a point Po located in the horizontal direction. For example, L = 6 mm,
θ = 30 °, φ1 = φ2 = 60 °, and d = 0.5 mm.

In this case, first, in the polymer-dispersed liquid crystal panel 11, the display image 31 is transparent, so that the light from the back light source 12 passes through the display image 31 as it is and the light diffusion filter 13 Will be reached.

On the other hand, in the portion of the background 32, the light from the back light source 12 is diffused inside the polymer dispersed liquid crystal plate 11, so that the light is visually recognized as cloudy bright.

Next, in the light diffusion filter 13, the light is diffused inside the light diffusion filter 13 in the regions Ar 1 and Ar 2 where the linear light is incident from the back light source 12 via the transparent display image 31. , And are visually recognized as cloudy. Conversely, regions Ar3 and Ar where linear light emitted from the rear light source 12 and passing through the transparent display image 31 are not incident
About No. 4, it will be visually recognized relatively dark.

However, the viewing point Po is located in the horizontal direction with respect to the polymer dispersed liquid crystal plate 11 and the light diffusion filter 13 and in the oblique direction with respect to the linear light from the back light source 12. Further, since the polymer dispersed liquid crystal plate 11 and the light diffusion filter 13 are inclined at an angle θ from the vertical direction, the portion of the display image 31 on the polymer dispersed liquid crystal plate 11 and the straight line The light incident regions Ar1 and Ar2 are visually recognized with their outlines shifted.

Specifically, in FIG. 1, the upper end points of the linear light incident areas Ar1 and Ar2 in the light diffusion filter 13 are visually recognized above the upper end points of the display image 31 on the polymer dispersed liquid crystal panel 11. . Therefore, A in FIG.
In the region of r1, the relatively bright background 32 portion in the polymer dispersed liquid crystal plate 11 and the relatively bright linear light incident region in the light diffusion filter 13 are overlapped and finally visible. It will appear as the brightest area when viewed from the point Po.

Although the region of Ar2 in FIG. 1 is a relatively bright linear light incident region in the light diffusion filter 13, it is transparent (has no brightness, that is, the most Since the display image 31 in a dark state) appears to overlap, it is visually recognized relatively darker than the area of Ar1 when viewed from the visual recognition point Po.

Further, the region of Ar3 is a portion of the transparent display image 31 where no linear light is incident on the light diffusion filter 13 and the polymer dispersed type liquid crystal plate 11 superposed thereon is also. The light from the rear light source 12 hardly enters the Ar3 region, and appears as the darkest region.

Further, in the Ar4 region, although no linear light is incident on the light diffusion filter 13, the polymer dispersed liquid crystal plate 11 superimposed on the Ar4 region becomes bright in a cloudy state. Since the bright portion is transmitted and appears at the visual recognition point Po, it is finally slightly brighter than the Ar2 region and is brighter than the Ar3 region.

The above can be summarized as follows.

Area Ar1: Appears as the brightest area where the bright background 32 of the polymer dispersed liquid crystal plate 11 and the bright light incident area of the light diffusion filter 13 overlap.

Area Ar2: Appears as a medium bright area where the dark display image 31 of the polymer dispersed liquid crystal plate 11 and the bright light incident area of the light diffusion filter 13 overlap.

Area Ar3: Appears as the darkest area where the dark display image 31 portion of the polymer-dispersed liquid crystal plate 11 and the dark light non-incident area of the light diffusion filter 13 overlap.

Area Ar4: Appears as a medium bright area where the bright background 32 of the polymer dispersed liquid crystal plate 11 and the dark light non-incident area of the diffusion filter 13 overlap.

Therefore, the order of brightness is Ar1> A
r2>Ar4> Ar3.

According to such a principle, the display contents visually recognized at the visual recognition point Po are as shown in FIGS. That is,
It appears that a shade is formed on the side of the display image 31 close to the back light source 12, and a brightest band of a certain width appears on the side far from the back light source 12, and when viewed from the viewing point Po, the display image 31 It is perceived that a natural shadow is formed.

The direction and width of shading are determined by the irradiation angle φ of the back light source 12, the polymer dispersed liquid crystal
Adjustment can be performed very easily by adjusting the separation distance d between the light diffusion filter 1 and the light diffusion filter 13 and the inclination angle θ of the polymer dispersion type liquid crystal plate 11 and the light diffusion filter 13 with respect to the vertical direction.

As described above, the light diffusion filters 13 are arranged in parallel with the polymer-dispersed liquid crystal plate 11 with a distance d therebetween.
By simply illuminating the back light source 12 obliquely with respect to the normal direction of the polymer-dispersed liquid crystal panel 11, the light-diffusing area (background 32) and the transparent area (display image 31) of the polymer-dispersed liquid crystal panel 11 can be seen. ) And the light incident area Ar of the light diffusion filter 13
The combination of the superimposition with Ar1, Ar2 and the light non-incidence areas Ar3 and Ar4 allows a shadow without gaps to be easily formed on the display image 31 without using a complicated device, and facilitates a three-dimensional display. Can be done.

In general, the polymer-dispersed liquid crystal plate 11 is
Compared to FT, it is inexpensive and has the advantage of cost reduction.

In the above embodiment, the case where the polymer dispersed liquid crystal plate 11 is used as a display element has been described. However, instead of the polymer dispersed liquid crystal plate 11, a transparent region is simply provided in advance as a display image. Behind the fixedly formed light-diffusing glass plate or cloudy resin plate, the back light source 1
By switching on / off of No. 2, the presence or absence of a display image may be switched. Even in this case, by arranging the display element and the light diffusion filter 13 in parallel at equal intervals as described above, a shadow can be easily formed as in the above-described embodiment.

[0042]

According to the first aspect of the present invention, the light diffusion filter is arranged in parallel with the display element at a distance from the display element, and the back light source is simply illuminated from the back with a diagonal to the normal direction of the display element. By combining the light diffusion area (background part) and transparent area (display image part) of the display element with the light incident area and light non-incidence area of the light diffusion filter,
Shading without gaps can be easily formed on a display image without using a complicated device, and display with a three-dimensional effect can be easily performed.

According to the second aspect of the present invention, it is possible to easily form a shadow on a display image which can be arbitrarily deformed without using an expensive display element such as a TFT. There is an advantage that the cost can be reduced as compared with the case where it is used.

[Brief description of the drawings]

FIG. 1 is a principle diagram showing an outline of a display device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating an outline of a display device according to an embodiment of the present invention.

FIG. 3 is a diagram showing display contents.

FIG. 4 is a diagram showing display contents.

FIG. 5 is a diagram showing a state of image display in the related art.

[Description of Signs] 11 Polymer dispersed liquid crystal plate 12 Back light source 13 Light diffusion filter 15 Control unit 21, 29 Transparent substrate 23, 27 Transparent electrode 25 Polymer dispersed liquid crystal layer 30 Light diffusion filter 31 Display image 32 Background

Claims (2)

[Claims] A display element for forming a transparent area as a display image with respect to a light diffusion area as a background; and a display element arranged substantially parallel to a front side of the display element at a predetermined separation distance and incident from behind. A display device, comprising: a light diffusion filter that transmits the generated light to the surface side while diffusing the light; and a back light source that irradiates the light obliquely toward the back of the display element. 2. The display device according to claim 1, wherein the display element is sandwiched between two transparent substrates having predetermined transparent electrodes formed on surfaces facing each other, and the two transparent substrates. And a polymer-dispersed liquid crystal plate having a polymer-dispersed liquid crystal layer whose scattering state of incident light changes with a change in an applied voltage applied by the transparent electrodes. apparatus.