JP2002131739A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image having excellent visibility by removing an influence by external light and reflection light, in a liquid crystal display device. SOLUTION: An optical element (12) changing the state of polarized light is disposed on the surface of the liquid crystal display device (11) and a polarizing element (13) having a light transmission axis in the same direction as the direction of the polarized light of the image transmitted through the optical element is disposed directly in front of an observer (19).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, particularly a liquid crystal display device (LC) utilizing the electro-optical characteristics of liquid crystal.
Regarding D), the present invention relates to a display device which cuts external light and reflected light to improve visibility and achieve high display quality.

[0002]

2. Description of the Related Art LCDs have the advantages of small size, thin shape, low power consumption, and the like, and are being put to practical use in the fields of OA equipment, AV equipment, and the like. In particular, an active matrix type using a thin film transistor (hereinafter abbreviated as TFT) as a switching element has high display quality and is widely used as a monitor of a computer, a video camera, or the like. The liquid crystal modes used for the LCD include a TN mode and an STN mode.
In addition, TFT-type LCDs in which a TFT is disposed in each display pixel have become widespread. Most of these LCDs are provided with a polarizing plate, and the displayed image has polarized light.

FIGS. 3 and 4 illustrate the principle of a conventional LCD. FIG. 4 is a sectional view taken along line AA of FIG. Here, the TN method will be described. In the conventional LCD, a liquid crystal layer (34) in which the orientation direction of the liquid crystal is twisted by 90 degrees is sandwiched between two glass substrates (33) and (36). Plates (32) and (37) are arranged. Light transmitted through the first polarizing plate (32) becomes linearly polarized light, and its polarization state changes depending on whether or not a voltage is applied to the liquid crystal layer (34). And depending on the polarization state, the second
The amount of light transmitted through the polarizing plate (37) is determined, whereby an image is displayed. In such an LCD, the light transmission axis of the polarizing plate on the emission side is arranged at an angle of 45 degrees or 135 degrees from the horizontal direction in order to make the viewing angle characteristics of the left and right symmetrical.

[0004]

In such a conventional liquid crystal display device, in a place where there is a lot of external light, such as outdoors, the external light is secondly emitted.
There is a problem that the light is reflected on the surface of the second polarizing plate (37) and the image becomes difficult to see. The inventors of the present invention have intensively studied to solve this problem.

[0005]

As a result, the present inventor has reached the following invention. That is, the present invention relates to a display device system including a display device in which an image to be projected has polarized light, and a polarizing element having a light transmission axis in the same direction as the polarization direction of the image on the front surface of the display device. Also,
An optical element that changes the state of polarization is arranged on the surface of a display device in which an image to be projected has polarized light, and the display device includes a polarizing element having a light transmission axis in the same direction as the polarization direction of the image transmitted through the optical element. System, the display device is a liquid crystal display device, the polarizing element is a polarizing plate, the optical device is a retardation plate, the display device system, wherein the polarizing element is glasses. A display device system, wherein the direction of polarized light incident on the polarizing element is a vertical direction, and the direction of a light transmission axis of the polarizing element is also a vertical direction. A transmission type liquid crystal display device having some light source, wherein the polarization direction of the image is approximately θ1 with respect to the horizontal direction, the optical element is a λ / 2 plate, and the retardation of the λ / 2 plate is The display device system is characterized in that the angle θ2 substantially satisfies the following formula: θ2 = θ1 / 2 + π / 4 [radian], and the display device is a reflective liquid crystal display device, and the polarization of the image is The direction is approximately θ1 with respect to the horizontal direction, the optical element is a λ / 2 plate, and the angle θ2 of the slow axis of the λ / 2 plate approximately satisfies the following expression. Display system θ2 = θ1 / 2 + π / 4 [radian].

[0006]

Next, an embodiment of the present invention will be described in detail. 1 and 2 show an embodiment of the present invention. 1 is a side view, and FIG. 2 is a top view. LCD (1
A λ / 2 plate (12) is arranged on the surface of 1), and the observer (1)
A polarizing element (13), which is spectacles, is disposed in front of the eye 9). The light transmission axis (21) of the second polarizer on the viewer side of the LCD (11) is oriented in the 45-degree direction in the slow axis (2) of the λ / 2 plate.
2) is arranged to be in the direction of 67.5 degrees, and the light transmission axis (27) of the polarizing element (13) is arranged to be in the vertical direction. Image (14) displayed on LCD (11)
Has a polarization direction of 45 degrees and is transmitted through the λ / 2 plate (12), so that the polarization direction (15) of the image is in the vertical direction (9).
0 degrees). The polarization transmission axis (27) of the polarizing element (13) arranged immediately before the observer (19) has a vertical direction (90 degrees).
Therefore, the image (15) transmitted through the λ / 2 plate (12)
Reaches the observer (19) with little attenuation by the polarizing element (13). At this time, the ambient light (17) is reduced to 以下 or less by the polarizing element (13), but the luminance of the image is hardly attenuated. Further, the reflected light (18) reflected on the surface of the λ / 2 plate (12) can be cut by the polarizing element (13), so that a better display can be obtained.

[0007]

As described above, the ambient light is reduced to half or less, but the luminance of the image is hardly reduced, so that the perceived luminance is improved. Further, since the reflected light reflected on the surface of the λ / 2 plate can be cut, a better display can be obtained.

[Brief description of the drawings]

FIG. 1 is a side view according to an embodiment of a liquid crystal display system of the present invention.

FIG. 2 is a top view according to the embodiment of the liquid crystal display system of the present invention.

FIG. 3 is an enlarged plan view of a conventional liquid crystal display device.

FIG. 4 is a sectional view taken along line AA of FIG. 3;

[Explanation of symbols]

 Reference Signs List 11 LCD 12 λ / 2 plate 13 Polarizing element 14 Polarized image from LCD 15 Image after transmission through λ / 2 plate 16 Image after transmission through polarizing element 17 External light 18 Reflected light 19 Observer 20 Light transmission through first polarizing element Axis 21 Light transmission axis of second polarizing element 22 Slow axis of λ / 2 plate 23 Polarization direction of polarized image from LCD 24 Polarization direction of image after transmission through λ / 2 plate 25 Polarization direction of reflected light 26 External light (Natural light) 27 Light transmission axis of polarizing element 31 Display electrode 32 First polarizing plate 33 First glass substrate 34 Liquid crystal layer 35 Common electrode 36 Second glass substrate 37 Second polarizing plate 38 Incident light

Claims (7)

[Claims] 1. A display device system comprising: a display device in which an image to be projected has polarized light; and a polarizing element having a light transmission axis on the front surface of the display device in the same direction as the polarization direction of the image. 2. An optical element for changing a state of polarized light is disposed on a surface of a display device in which an image to be projected has polarized light,
A display device system comprising a polarizing element having a light transmission axis in the same direction as the polarization direction of an image transmitted through the optical element. 3. The display device system according to claim 1, wherein said display element is a liquid crystal display, said polarizing element is a polarizing plate, and said optical element is a retardation plate. 4. A display system according to claim 1, wherein said polarizing element is spectacles. 5. A display system according to claim 1, wherein the direction of polarized light incident on said polarizing element is a vertical direction, and the direction of a light transmission axis of said polarizing element is also a vertical direction. 6. The display device according to claim 1, wherein the display device is a transmissive liquid crystal display device having a light source on a rear surface thereof, and a polarization direction of the image is approximately θ1 with respect to a horizontal direction. The optical element is a λ / 2 plate,
A display device system characterized in that the angle θ2 of the slow axis of the half plate approximately satisfies the following expression. θ2 = θ1 / 2 + π / 4 [radian] 7. The display device according to claim 1, wherein the display device is a reflective liquid crystal display device, and the polarization direction of the image is
A display device system, wherein the angle is approximately θ1 with respect to the horizontal direction, the optical element is a λ / 2 plate, and the angle θ2 of the slow axis of the λ / 2 plate approximately satisfies the following expression: . θ2 = θ1 / 2 + π / 4 [radian]