JP2015025928A - Reflective liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflective liquid crystal display device having good image qualities.SOLUTION: The liquid crystal display device is configured to satisfy an expression of β≤90-α relating to the following angles α and β. Angle α is an angle of an optical axis that directly connects a point on a light-exiting surface of a polarizing plate 5, the point where a main optical axis of light exiting from a light source 3 passes, and a point located at the center of an image display region in a light-reflecting surface of a reflective liquid crystal display panel 2, with respect to the normal line of the light-reflecting surface of the reflective liquid crystal display panel 2; and angle β is an angle of an end face 10a of an aperture 10 provided in a chassis 7 with respect to the light-reflecting surface of the reflective liquid crystal display panel 2. This configuration prevents a part of light reflected on the light-reflecting surface of the reflective liquid crystal display panel 2 from being incident to the end face 10a of the aperture 10 provided in the chassis 7, and thereby, prevents degradation in picture qualities due to glare on the end face 10a of the aperture 10.

Description

  The present invention relates to a reflective liquid crystal display device.

  Reflective liquid crystal display devices are often used in electronic viewfinders, head mounted displays, and the like, and in recent years, there has been a demand for reflective liquid crystal display devices capable of displaying high-definition images with high contrast and good appearance. FIG. 2 is a cross-sectional view showing a conventional reflective liquid crystal display device. In a conventional reflective liquid crystal display device, a reflective liquid crystal display panel 2 and a light source 3 are disposed on the same surface of the circuit board 1 with their light reflecting surfaces (light reflecting layers such as reflective electrodes) and light emitting surfaces facing upward. A reflector 9 is disposed above the light source 3 so as to reflect the light emitted from the light source 3 toward the reflective liquid crystal display panel 2. On the path of the light reflected by the reflecting plate 9, the diffusing plate 4 and the polarizing plate 5 are arranged in order so that the light emitting surface is perpendicular to the light reflecting surface of the reflective liquid crystal display panel 2. A curved sloped beam splitter 6 is disposed above the liquid crystal display panel 2.

  The polarizing plate 5 transmits only one linearly polarized light (hereinafter referred to as P wave) out of two linearly polarized light whose polarization axes are orthogonal to each other, and absorbs linearly polarized light (hereinafter referred to as S wave) whose polarization axis is orthogonal thereto. On the other hand, the beam splitter 6 is constituted by a so-called reflection type polarizing plate that reflects the P wave emitted from the polarizing plate 5 and transmits the S wave whose polarization axis is orthogonal thereto, The inclination angle and the curvature of the inclined surface are determined so that the P wave emitted from the polarizing plate 5 is perpendicularly incident on the light reflecting surface of the reflective liquid crystal display panel 2.

  A casing 7 is disposed on the circuit board 1 so as to cover the reflective liquid crystal display panel 2, the light source 3, the diffusion plate 4, the polarizing plate 5, and the reflecting plate 9. A rectangular opening 10 is provided in a region facing the image display surface of the reflective liquid crystal display panel 2, and a beam splitter 6 is fixed to the housing 7 so as to cover the opening 10. Here, the inclination angle β (angle with respect to the light reflection surface of the reflective liquid crystal display device 2) of the end face 10a of the opening 10 is approximately 80 °, for example.

  The reflective liquid crystal display panel 2 is configured such that the P wave passes through the liquid crystal as it is in the power-off state, and the P wave perpendicularly incident from the beam splitter 6 side passes through the liquid crystal as it is, and the reflective liquid crystal display panel The P wave reflected vertically by the light reflecting surface (reflecting electrode or the like) provided on the back side of 2 passes through the liquid crystal again and travels toward the beam splitter 6, but the P wave passes through the beam splitter 6. Since it is blocked, it does not reach the observer's eye 8.

  On the other hand, in the reflective liquid crystal display panel 2, the liquid crystal converts a P wave into an S wave in the power-on state, and the converted S wave is provided on the back side of the reflective liquid crystal display panel 2 like the P wave. The light is reflected by the light reflecting surface, travels toward the beam splitter 6, passes through the beam splitter 6, and reaches the observer's eyes 8 (see the optical path L <b> 1 in the drawing).

  The above process is performed for each pixel of the reflective liquid crystal display panel 2, and only the S wave transmitted through the beam splitter 6 reaches the viewer's eyes 8 and is visually recognized as an image. (For example, see Patent Documents 1 and 2)

JP 2009-294403 A JP 2009-192594 A

  In the P wave emitted from the polarizing plate 5, there is a component that goes directly to the reflective liquid crystal display panel 2 in addition to the component that goes to the beam splitter 6, but the conventional reflective liquid crystal display shown in FIG. In the apparatus, the incident angle α of light directly incident on the point located at the center of the image display area in the light reflection surface of the reflection type liquid crystal display panel 2 from the center of the light emission surface of the polarizing plate 5 (of the reflection type liquid crystal display panel 2). An angle represented by β> 90−α is defined by an angle formed with the normal line of the light reflecting surface and an inclination angle β of the end surface 10a of the opening 10 (an angle formed with the light reflecting surface of the reflective liquid crystal display panel 2). Therefore, a part of the light directly incident on the light reflecting surface of the reflective liquid crystal display panel 2 from the polarizing plate 5 is reflected as an S wave on the light reflecting surface of the reflective liquid crystal display panel 2, The reflected S wave passes through the beam splitter 6 and passes through the opening 10. Incident on surface 10a. The S wave incident on the end face 10a of the opening 10 is reflected to the observer side on the surface, and depending on the position of the observer, the end face 10a of the opening 10 appears to shine, and the appearance and contrast of the image are reduced. It occurs (see optical path L2 in the figure).

  The present invention has been made in view of the above problems, and an object thereof is to provide a reflective liquid crystal display device with good image quality.

  A light source, a reflective liquid crystal display panel, a casing disposed so as to cover the image display surface of the reflective liquid crystal display panel, and an opening provided in a region facing the image display surface; A polarizing plate that transmits only one of the two linearly polarized light whose polarization axes are orthogonal to each other, and the polarizing plate is disposed so as to cover the opening provided in the housing. The one linearly polarized light transmitted through the reflective liquid crystal display panel is reflected toward the image display surface of the reflective liquid crystal display panel, and the one linearly polarized light emitted from the image display surface of the reflective liquid crystal display panel is polarized. And a beam splitter that transmits the other linearly polarized light whose axes are orthogonal to each other. The main optical axis of the light emitted from the light source among the light exit surfaces of the polarizing plate passes through the reflective liquid crystal display device. An angle formed by an optical axis directly connecting a point located at the center of the image display area in the light reflection surface of the reflection type liquid crystal display panel and a normal line of the light reflection surface of the reflection type liquid crystal display panel is α. When the angle of inclination of the end surface of the opening provided in the housing is β with respect to the light reflecting surface of the reflective liquid crystal display panel, α and β are β ≦ 90−α. The reflective liquid crystal display device is configured to satisfy the expression expressed.

  The light emitting surface of the polarizing plate is disposed so as to be perpendicular to the light reflecting surface of the reflective liquid crystal display panel, the α is set to 45 °, and the β is set to 45 ° or less. A reflective liquid crystal display device.

  According to the present invention, since part of the light reflected by the reflective liquid crystal display panel does not enter the end face of the opening provided in the housing, it is possible to prevent the image quality from being deteriorated due to the end face of the opening shining. Can do.

Sectional drawing which shows one Embodiment of the reflection type liquid crystal display device by this invention Sectional view showing a conventional reflective liquid crystal display device

  FIG. 1 is a cross-sectional view showing an embodiment of a reflective liquid crystal display device according to the present invention. One embodiment of a reflective liquid crystal display device according to the present invention has the following basic configuration, as in a conventional reflective liquid crystal display device. On the same surface of the circuit board 1, the reflective liquid crystal display panel 2 and the light source 3 are arranged with the light reflecting surface (light reflecting layer such as a reflective electrode) and the light emitting surface facing upward, respectively, and above the light source 3. The reflector 9 is arranged so as to reflect the light emitted from the light source 3 toward the reflective liquid crystal display panel 2. On the path of the light reflected by the reflecting plate 9, the diffusing plate 4 and the polarizing plate 5 are arranged in order so that the light emitting surface is perpendicular to the light reflecting surface of the reflective liquid crystal display panel 2. A curved sloped beam splitter 6 is disposed above the liquid crystal display panel 2.

  The polarizing plate 5 transmits only one linearly polarized light (hereinafter referred to as P wave) out of two linearly polarized light whose polarization axes are orthogonal to each other, and absorbs linearly polarized light (hereinafter referred to as S wave) whose polarization axis is orthogonal thereto. On the other hand, the beam splitter 6 is constituted by a so-called reflection type polarizing plate that reflects the P wave emitted from the polarizing plate 5 and transmits the S wave whose polarization axis is orthogonal thereto, The inclination angle and the curvature of the inclined surface are determined so that the P wave emitted from the polarizing plate 5 is perpendicularly incident on the light reflecting surface of the reflective liquid crystal display panel 2.

  A casing 7 is disposed on the circuit board 1 so as to cover the reflective liquid crystal display panel 2, the light source 3, the diffusion plate 4, the polarizing plate 5, and the reflecting plate 9. A rectangular opening 10 is provided in a region facing the image display surface of the reflective liquid crystal display panel 2, and a beam splitter 6 is fixed to the housing 7 so as to cover the opening 10.

  Here, the present embodiment is different from the conventional configuration in that the incident angle α (the center of the light emitting surface of the polarizing plate 5 and the light reflecting surface of the reflective liquid crystal display panel 2 are located at the center of the image display region) Is an angle formed with the normal of the light reflecting surface of the reflective liquid crystal display panel 2 and an inclination angle β (the end surface 10a of the opening 10 is formed with the light reflecting surface of the reflective liquid crystal display device 2). Angle) is a relationship satisfying the expression represented by β ≦ 90−α. In this embodiment, for example, the incident angle α is set to 45 °, and the inclination angle β is set to 45 ° or less. Yes.

  In the present embodiment, the light emitted from the light source 3 is reflected by the reflecting plate 9 and enters the diffusion plate 4, then passes through the polarizing plate 5 to become a P wave, and enters the beam splitter 6. The P wave incident on the beam splitter 6 is reflected toward the reflection type liquid crystal display panel 2, enters the image display surface of the reflection type liquid crystal display panel 2 perpendicularly, and passes through the reflection type liquid crystal display panel 2. The light is a light (mixed P wave and S wave) that is reflected vertically and enters the beam splitter 6 again. Of the image light incident on the beam splitter 6, only the S wave passes through the beam splitter 6 and reaches the observer's eyes 8 and is visually recognized as an image (see optical path L <b> 1 in the figure).

  On the other hand, among the P waves emitted from the center of the polarizing plate 5, the P waves directly incident on the reflective liquid crystal display panel 2 obliquely are converted into S waves when the reflective liquid crystal display panel 2 is in the power-on state. The reflected S wave passes through the beam splitter 6 and travels toward the end face 10 a of the opening 10. However, in this embodiment, since the end surface 10a of the opening 10 is set to an angle that satisfies the expression represented by β ≦ 90−α, the S wave reflected by the light reflecting surface of the reflective liquid crystal display panel 2 is used. Is not incident on the end surface 10a of the opening 10 while maintaining an angle symmetric with respect to the incident angle α about the normal line of the light reflection surface of the reflective liquid crystal display panel 2. The light travels across the top and exits outside the housing 7 (see the optical path L3 in the figure). Since the S wave emitted to the outside of the casing 7 travels in a direction deviating from the observer's eye 8, only the S wave vertically reflected from the reflective liquid crystal display panel 2 reaches the observer's eye 8. That is, the end face 10a of the opening 10 is not illuminated, and the image quality is improved.

  In the above embodiment, the incident angle α is set to 45 ° and the inclination angle β is set to 45 ° or less. However, the inclination angle β is not limited to this, and is appropriately selected according to the incident angle α. Is.

  In the above embodiment, it is assumed that the main optical axis of the light emitted from the light source 3 passes through the center of the light exit surface of the polarizing plate 5, and the incident angle α is set to the center of the light exit surface of the polarizing plate 5 and the reflection type. It is defined as an angle based on the optical axis directly connecting the point located at the center of the image display area in the light reflecting surface of the liquid crystal display panel 2, but essentially the light emitting surface of the polarizing plate 5 Of these, it is defined as an angle with respect to the optical axis that directly connects the point through which the main optical axis of light passes and the point located at the center of the image display area of the light reflection surface of the reflective liquid crystal display panel 2 is there.

  The position and angle of each member such as the polarizing plate 5, the reflecting plate 9, and the beam splitter 6 are not limited to the above-described embodiments, and can be selected as appropriate. In particular, the diffusing plate 4 and the reflecting plate 9 can be omitted. For the light source 3, for example, the light emitting surface is disposed opposite to the light incident surface of the polarizing plate 5, or a light guide plate is used. It can also be configured as a surface light source. Further, the beam splitter 6 is not limited to a curved one, and a flat plate or the like can also be used. Moreover, although the housing | casing 7 is comprised with black resin, for example, it does not specifically limit about material and a shape, About the shape of the opening part 10 provided there, it is not restricted to a rectangular shape, Others Various shapes such as a polygon and a circle can be appropriately selected.

  In the above description, it is assumed that the light reflection surface of the reflective liquid crystal display panel 2 totally reflects light on a completely smooth surface, and the light generated inside the reflective liquid crystal display panel 2 is assumed. Although refraction and the like are ignored for the sake of convenience, the optical system is actually designed in consideration of such conditions.

DESCRIPTION OF SYMBOLS 1 Circuit board 2 Reflective type liquid crystal display panel 3 Light source 4 Diffusion plate 5 Polarizing plate 6 Beam splitter 7 Case 8 Eye of observer 9 Reflector 10 Opening 10a End face α Incident angle β Inclination angle

Claims (2)

A light source;
A reflective liquid crystal display panel;
A housing that is arranged so as to cover the image display surface of the reflective liquid crystal display panel, and that has an opening in a region facing the image display surface;
A polarizing plate that transmits only one linearly polarized light out of two linearly polarized light whose polarization axes are orthogonal to each other included in the light emitted from the light source;
The one linearly polarized light that is disposed so as to cover the opening provided in the housing and is transmitted through the polarizing plate is reflected toward the image display surface of the reflective liquid crystal display panel, and the reflective type A beam splitter that transmits the other linearly polarized light whose polarization axis is orthogonal to the one linearly polarized light emitted from the image display surface of the liquid crystal display panel;
In a reflective liquid crystal display device having
Of the light exit surface of the polarizing plate, a point through which the main optical axis of the light emitted from the light source passes, and a point located at the center of the image display region of the light reflection surface of the reflective liquid crystal display panel. The angle formed by the directly connecting optical axis and the normal of the light reflecting surface of the reflective liquid crystal display panel is α,
When the inclination angle of the end surface of the opening provided in the housing is β with respect to the light reflection surface of the reflective liquid crystal display panel,
The α and the β are configured to satisfy an expression represented by β ≦ 90−α.
A reflection-type liquid crystal display device.   The light emitting surface of the polarizing plate is disposed so as to be perpendicular to the light reflecting surface of the reflective liquid crystal display panel, the α is set to 45 °, and the β is set to 45 ° or less. The reflective liquid crystal display device according to claim 1, wherein:

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