JP3230225B2 - Image display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device in which a plurality of pixels are arranged in a vertical direction and a horizontal direction, such as an LCD (Liquid Crystal Display). The present invention relates to an invention for making a mesh formed of lines inconspicuous.

[0002]

2. Description of the Related Art In an image display apparatus such as an LCD, which is composed of a group of pixels, it is necessary to increase the number of pixels in order to increase the resolution. Cannot be reduced.

[0003] For this reason, when attempting to form a large screen with this type of image display device, the observer will noticeably see meshes due to pixel dots and gaps between pixels (for example, LCD black stripe portions), which makes it difficult to see. In this type of color image display device, color filters of three primary colors or three types of colors corresponding to the three primary colors are arranged in front of the pixel at a predetermined repetition cycle. In addition, the pixel dot period in which filters of the same color are arranged is conspicuous, making it hard to see.

In a CCD camera, the gap between pixels can be made inconspicuous by electrical processing using a low-pass filter. However, in a display device such as an LCD display device, it is necessary to fill the gap between pixels after light has been emitted. Therefore, it has been difficult to make pixel dots and meshes inconspicuous by electrical processing. As a convenient method, there is a method of blurring the lens focus on the viewing side, but it is not preferable because the signal is also blurred.

Therefore, a diffraction grating is provided on the front surface of a display element such as an LCD to disperse the light from one pixel into a plurality of pieces, and to convert the image of one pixel into a plurality of pixels on the retina of a viewer. A technique has been proposed in which an image is formed as an image (virtual image), pixels are diffused, and an image forming position of the diffused image is set to a mesh position between pixels so that meshes between pixels are made inconspicuous ( See, for example, JP-A-59-214825).

[0008] That is, FIG. 8 is a diagram for explaining the dispersion of light from a pixel by the diffraction grating, where 1 is a pixel dot and 2 is a diffraction grating. The pixel dot 1 is, for example, one pixel dot in an LCD in which a plurality of pixel dots in a matrix are arranged. In this case, the diffraction grating 2 is disposed at a position P2 which is separated from the position P1 on the LCD surface by a distance d.

As shown in FIG. 8, the light emitted from the pixel 1 is dispersed by the diffraction grating 2, so that a viewer of the display device goes straight through the diffraction grating 2 as an image of the pixel 1. And a zero-order image, and a first-order and second-order virtual image are seen at positions sequentially shifted by a shift amount x determined by the distance d and the pitch g of the diffraction grating 2 from the zero-order image. Therefore, by designing the primary and secondary virtual images so as to overlap the position of the contour line between the pixels, the pixel dots and the mesh between the pixel dots can be made inconspicuous.

[0008]

As described above, for example, a diffraction grating is arranged on the front surface of an LCD to disperse light from one pixel into a plurality of pixels, thereby forming a mesh between pixel dots and a color display. Although the pixel dot cycle in which the filters of the same color are arranged in the device can be made inconspicuous, the following drawbacks occur when using a diffraction grating.

That is, in order to make the mesh between pixels inconspicuous, the shift amount x must be determined so as to be appropriate. However, as described above, this shift amount x is It is determined by the distance d from the diffraction grating and the pitch g of the diffraction grating 2, and is determined by the following arithmetic expression (1): x = λ · d / g (1) Here, λ is the wavelength of light.

As can be seen from the arithmetic expression (1), when the diffraction grating 2 is used, the optimal shift amount is determined by the pixel arrangement of the LCD, so that the mounting position of the diffraction grating 2 with respect to the LCD, that is, the distance d is determined. Then, the pitch g of the diffraction grating 2 is determined, and the pitch g cannot be freely selected. For this reason, in the case of a color display device, it is difficult to reduce moire.

In the case of a diffraction grating, the luminance intensity of a diffused image decreases as the order increases, and it is difficult to control the luminance. Therefore, the diffused image of a higher order is substantially used. Can not do. In addition, unnecessary high-order dispersed light may cause a decrease in contrast.

An object of the present invention is to provide an image display device which can make pixel dots and meshes between pixels inconspicuous without causing the above-mentioned drawbacks.

[0013]

In order to solve the above-mentioned problems, an image display device according to the present invention is arranged such that each of a plurality of pixels arranged in a vertical direction and a horizontal direction emits light at a brightness corresponding to image contents. By doing so, in the image display device on which the image is displayed, the fine prism is moved in the vertical and forward directions.
The plurality of optical filters arranged in the horizontal direction are
Being arranged in front of a pixel, wherein the micro prism
It is different from one another inclination angle when viewed in the longitudinal direction 3
And has a number of angular surfaces, truncated pyramid shape together with three angular surfaces with different inclination angles when viewed in the transverse direction
And the direction of light from the pixel is bent by each of the angle planes, and that of the angle plane
Each area is the light of the image corresponding to each of the angular planes.
It is characterized by having a size corresponding to the strength .

[0014]

According to the present invention having the above structure, light from one pixel is dispersed into a number equal to the number of the plurality of angular surfaces of the micro prism, and one pixel is divided into the number of pixels equal to the number of dispersion. To spread. In this case, the shift amount of the diffused pixel is
Since the pitch is determined by the refractive index and the prism angle of the prism and has no relation to the pitch at which the minute prisms are formed, the pitch can be freely determined and moire can be made inconspicuous.

FIG. 2 is a diagram for explaining the pixel shift by the prism, and corresponds to FIG. In FIG.
Reference numeral 3 denotes a prism having a surface (hereinafter, referred to as an angle surface) 5 inclined by an angle θ (this is referred to as a prism angle) with respect to a direction orthogonal to the direction of the optical axis 4. Light emitted from the pixel 1 is incident on the angle surface 5 of the prism 3 at an incident angle θi (= θ), is refracted, and is emitted at an emission angle θo. Therefore, to the viewer, light appears to be emitted from a position shifted by the shift amount x from the position of the pixel 1, and a virtual image is obtained at the shifted position.

At this time, assuming that the refractive index of the prism 3 is n, n · sin θi = sin θo (2) When the distance between the pixel 1 and the angle plane 5 is b, the shift amount x is expressed as x = b · tan (θo−θi) (3). Since θi = θ, x = b · tan {sin ⁻¹ (n · sin θ) −θ} (4), and the shift amount x is determined regardless of the prism formation pitch. Therefore, by adjusting the pitch of the plurality of micro prisms, it is possible to easily reduce moire.

Further, since the intensity of the scattered light by each angle plane of each micro prism is determined by the solid angle of the angle plane,
By controlling the solid angle, it is possible to make the intensity of the plurality of dispersed lights uniform.

Further, a shift image is formed for one pixel by the number of angular surfaces of the micro prism. Therefore, if micro prisms having the same number of angle planes as the number of shifted images required for the synthesis are arranged on the front surface of the pixel group, the gap between pixels and the dot cycle of the same color pixel are less noticeable.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an image display device according to the present invention will be described below with reference to the drawings. FIG. 1 is a conceptual diagram when the present invention is applied to an electronic viewfinder.

In FIG. 1, reference numeral 10 denotes an LCD, and FIG.
As shown in FIG. 2, a plurality of pixels 11 are arranged in a vertical (column) direction and a horizontal (row) direction. Reference numeral 12 denotes an opening of each pixel 11, and the opening 12 becomes substantially bright. The width of the opening 12 in the horizontal direction is Lx, and the width in the vertical direction is Ly. In this example, the pixel pitch in the horizontal direction is Px, and that in the vertical direction is Py. In addition, every other row of pixels 11 has a pixel arrangement pitch Px of 1 in the horizontal direction.
/ 2 is formed so as to be shifted in the horizontal direction.

In this example, a color image display device is used. In this example, color filters corresponding to the three primary colors of light are provided for each pixel 11, and in this example, each pixel 11 , Green G or blue B. In this case, for each row of pixels 11, R,
.. Are arranged so that a set of three colors, G, B, R, G, B,. The pitch between pixels of the same color in the horizontal direction is P
Cx (= 3Px). In each of the other rows, the pixels 11 of the same color are arranged in a line in the vertical direction, and the pitch of the pixels of the same color in every other row is PCy.
(= 2Py). Further, in the adjacent rows, the positions of the pixels of the same color are arranged so as to be shifted by １ ／ of the horizontal arrangement pitch PCx of the same color. That is, pixels of the same emission color are arranged in a so-called checkered pattern.

In FIG. 1, reference numeral 20 denotes an LCD 10
This is a so-called backlight member for giving light from behind to make the display on the LCD 10 brighter. 40 is an eyepiece, 50 is a viewer's eye, 51 is its crystalline lens,
52 is a retina.

As will be described later, between the display surface of the LCD 10 and the eyepiece 40, a transparent plate surface 30A is provided.
Diffuser (scattering plate) with many small prisms formed on it
30 are provided. In this case, if the thickness of the diffuser 30 is made equal to the distance D between the surface 30A of the diffuser 30 and the display surface of the LCD, the assembly of the image display device of this example becomes easy. FIG. 4 is an enlarged view of a part of a large number of micro prisms formed on the diffuser 30. In the case of this example, each micro prism 31
Are angle surfaces 32a, 32 of three types of prism angles in the horizontal direction.
b, 32c are angle surfaces 32 of three kinds of prism angles in the vertical direction.
d, 32b, 32e, etc. in both the vertical and horizontal directions,
Each is formed with three types of angle surfaces, and each has a truncated pyramid shape in which the upper part of a pyramid is flattened.

In this case, the light from one pixel 11 of the LCD 10 is divided into three light beams in each direction by three micro prisms 31 of the diffuser 30 and three prism angles in the vertical and horizontal directions. Are distributed. Therefore, the number of shifted images of pixels obtained by bending light from one pixel by each angle surface of the micro prism, that is, the diffusion number of pixels is 3 × 3 = 9.

FIG. 5 shows a state in which an image of one pixel can be shifted by the number of different prism angles by a group of minute prisms. FIG. 6 is an enlarged view of the micro prism portion of FIG. In this example, for example, using three angle surfaces 32a, 32b, and 32c of three different prism angles in the horizontal direction,
The figure shows how image synthesis (three-pixel diffusion) is realized. Further, it shows that the angle planes of the same prism angle of the micro prism group form an image at the same position on the retina.

The shift image can be formed on a line (dotted line) obtained by extending the light emitted from the angle plane of the micro prism to the pixel side (FIG. 5).
And I, II and III in FIG. 6). In the case of the example shown in the figure, there are three shift amounts: 0, x1, and x2. Therefore, one shift image can be considered for one angle plane. And adjust the solid angle of each angle plane,
By controlling the area of the angle plane, the light intensity of the image corresponding to each angle plane can be controlled.

FIG. 7 shows a state in which the diffuser 30 in which the micro prism group of the example shown in FIG. 4 is formed shifts the pixels, and by combining the shifted pixels, the contour between the pixels and the pixel period of the same color become less noticeable. Is shown. The example of FIG. 7 shows one color, for example, red R in FIG.
And a shift amount in the horizontal direction is ± 1 of the pitch PCx of pixel dots of the same color in the horizontal direction.
/ 3 points and one point where the shift amount is 0 are formed,
In the vertical direction, the shift amount is the pitch P of the same color pixel dots.
As shown in FIG. 7A, three points of ± 1/3 of Cy and one point having a shift amount of 0 are formed, and as shown in FIG. 7A, a nine-point image combination (two-dimensional This shows a case where a (three-pixel diffusion) pattern is formed. In FIG. 7, a pixel with an oblique line attached to the opening and a mark with a circle at the center is a pixel position where the shift amount for a pixel of a certain color is 0, and corresponds to the original pixel position. I have.

As is apparent from FIG. 7, according to this example, it is possible to form a diffused image of the pixel on the contour portion between the pixels, and it is also possible to make the pixel cycle of the same color less noticeable. .

[0029]

Comparing the equations (1) and (4),
In the case of the diffuser 30, the pitch P of the minute prisms
p is not included in the calculation formula. This means that the optimum pitch Pp free from moiré can be freely selected regardless of the mounting position of the diffuser 30.

The light intensity can be changed by changing the size (area) of each angle plane in FIG. 4, that is, in proportion to the angle (solid angle) viewed from the pixel.

[0032]

As described above, according to the present invention, it is possible to eliminate stitches with reduced image quality deterioration (image blur). Also, the size of each angle surface of each micro prism
(Area) is the diffusion image of the pixel to be shifted and its periphery.
Consider light intensity of light intensity of composite pixel with diffuse image of surrounding pixels
The light intensity of the diffuse composite image
Can be suppressed.

Further, the gap between pixels and the dot cycle of the same color become less noticeable, so that the details of the image can be seen better. Therefore, even if the number of pixels is small, image quality equivalent to that of a display device having the number of pixels one rank higher can be reproduced.

Further, since the formation pitch of a large number of micro prisms can be freely determined, the pixel shift amount can be determined by the prism angle even if the mounting position is restricted, and moire can be made inconspicuous.

Further, since the micro prism is used, the intensity of high-order scattered light can be set independently and freely, and unnecessary high-order scattered light can be reduced to zero, so that a decrease in contrast can be reduced. .

Further, the lowest order diffraction of the diffraction grating does not become 3 or less of 0 and ± 1, but since one image can be set independently by one micro prism in the prism, the pixels are shifted in multiple directions and synthesized. In this case, a design can be made in which useless images are reduced and contrast and resolution are hardly deteriorated.

[Brief description of the drawings]

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

FIG. 2 is a diagram for explaining how a pixel image is shifted by a prism used in the present invention.

FIG. 3 is a diagram showing an example of a color pixel array when the present invention is applied to a color image display device.

FIG. 4 is a partially enlarged view of a main part of the present invention.

FIG. 5 is a diagram for explaining the principle of the present invention.

FIG. 6 is a diagram for explaining the principle of the present invention.

FIG. 7 is a diagram showing an example of pixel diffusion according to the present invention.

FIG. 8 is a diagram for explaining a conventional example in which pixel diffusion is performed using a diffraction grating.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 LCD 20 Back light member 30 Diffuser 40 Eyepiece 31 Micro prism

Claims (1)

(57) [Claims] Each of 1. A longitudinal and a plurality of pixels arranged in the horizontal direction, by emitting at brightness corresponding to image content, the image display apparatus in which the image is displayed, the micro prisms A large number is arranged in the vertical direction and the horizontal direction.
An optical filter disposed in front of the plurality of pixels.
A than, the micro prisms, and has a three angles surfaces mutually different tilt angles when viewed in the longitudinal direction, the three angular faces different from each other inclination angle when viewed in the transverse direction
Having a truncated pyramid shape having
Ri, together to bend the direction of light from the pixels, each of the area of the angle surface, it the angle surface
An image display device having a size corresponding to the light intensity of an image corresponding to each of the images.