JPH11109873A - Display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the light transmitted through an aperture from being accompanied with a noise component at a periphery part, to avoide a crosstalk between picture elements and to make a display stoyby visible by making the display have a distribution of transmissivity or reflectance which is made lower as going to the periphery part from the center part of a cell. SOLUTION: By setting the transmissivity distribution or the reflectance distribution in the cell (aperture) being the picture element so that the transmissivity or the reflectance may be reduced from the center part to the periphery part at least in one direction, the intensity of emitted light in a main lobe is made uniform. The intensity distribution of the emitted light from the aperture is related to amplitude distribution being a square root. In the case of making the transmissivity distribution at the center part of the aperture definite and reducing the transmissivity from the position as being away from the center part toward the periphery part (waveform is made trapezoidal), the intensity distribution becomes a trapezoidal function. When the amplitude transmissivity of the aperture is the trapezoidal function, the utilization efficiency of incident light is enhanced because the intensity of the emitted light is made high at the center part while keeping the reduction of the intensity at the periphery part in the intensity distribution of the emitted light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a display having pixels as constituent units. In particular, the present invention relates to a display having a transmittance distribution or a reflectance distribution such that the transmittance or reflectance of a cell serving as a pixel decreases in at least one direction of a cell surface from a central portion to a peripheral portion of the cell.

[0002]

2. Description of the Related Art There are various types of displays constituted by a group of cells which are pixels. Among them, a liquid crystal display is typical as a type of display in which an “opening” is a cell and an image is displayed by light rays passing through the opening. FIG. 4 conceptually shows the configuration of the display.

In a liquid crystal display, the shape of a liquid crystal cell serving as an opening is generally rectangular, and the transmittance distribution of light transmitted through the opening is represented by a rectangular function graph shown in FIG. Will be done.

That is, the intensity distribution of the transmitted light illuminated from the backlight and passing through the liquid crystal panel is constant within the range of the opening of each liquid crystal panel (the transmittance does not change according to the position inside the opening). ), Which is represented by a rectangle function.

The above-described intensity distribution is a description that is applied within the range of the opening on the opening surface (from -d to + d in FIG. 1). Depending on the relationship between the distance at which the display is observed and the opening size, the following is given. The situation will change.

[0006] Fresnel number (N) defined as:
The observation state under the condition of N << 1 corresponds to the “Fraunhofer region”. The observation state under other conditions corresponds to the Fresnel region. “N << 1” means “N is much smaller than 1”. (In general, a difference of several times or more is sufficient.) In any region, the intensity distribution of transmitted light from a simple aperture is uniquely determined with respect to the Fresnel number.

[0007]

(Equation 1)

When the observation state corresponds to the Fraunhofer region (generally, when the size of the opening is small), even if the light incident on the opening of the pixel is parallel light, the light passes through the opening due to the diffraction at the opening. Light will spread.
That is, the light intensity distribution at each pixel includes a noise component in the peripheral portion, resulting in crosstalk between pixels. FIG. 5 shows a waveform of the light intensity distribution of the transmitted light in the case where a noise component is involved in the peripheral portion.

[0009] Even when the observation state corresponds to the Fresnel region, similarly to the above, the light transmitted through the aperture is accompanied by a noise component in each peripheral portion, and the light intensity changes drastically in each central portion.

When the pixel size is large to some extent, the range in which an image displayed by incident light (parallel light) can be observed is extremely limited. On this occasion,
If the light emitted from the display has scattering properties, observation from a wide range is possible, but it is difficult to freely set the viewing zone. In the above equation, when the light emitted from the cell has a phase of a spherical wave, it is necessary to consider the distance between the convergence point and the divergence point of the spherical wave in the value of the observation distance.

In an existing display, light transmitted through a pixel (aperture) is illuminating light from a backlight or the like. As a result, a phenomenon that the light spreads due to diffraction at the aperture may be observed. At present, no proposal has been made to make the emitted light have scattering properties.

The present invention is not limited to a mode in which the illumination light enters from the side opposite to the observer via the pixel (opening) and the display light (transmitted light) exits to the observer. Is incident from the observer side via the pixel (opening), and is reflected and emitted toward the observer side.

As described above, when the display is observed due to the non-uniformity of the light emitted from the conventional pixel (aperture), the brightness of the display changes depending on the viewpoint position of the observer, or the display surface is bright or dark. The problem that fringes are observed.

[0014] In addition, in the display having the above-mentioned aperture as a pixel, a method of displaying an image with a three-dimensional effect has been devised by visually recognizing a different two-dimensional image having parallax in accordance with a viewing direction. No proposals have been reported so far.

[0015]

SUMMARY OF THE INVENTION According to the present invention, light transmitted through an aperture is prevented from being accompanied by a noise component at each peripheral portion.
Even if the observation state corresponds to either the Fraunhofer region or the Fresnel region, crosstalk between pixels is avoided and the display is stabilized (the brightness does not change depending on the viewpoint position, and bright and dark stripes are not observed). The main purpose is to make it visible.

[0016]

SUMMARY OF THE INVENTION According to the present invention, the transmittance or reflectance of a cell serving as a pixel constituting a display is determined as follows.
In at least one direction of the cell surface, the cell surface has a transmittance distribution or a reflectance distribution that decreases from the center to the periphery of the cell.

According to a second aspect of the present invention, there is provided a transmittance distribution in which the transmittance or reflectance of a cell constituting a pixel constituting a display decreases in one direction of a cell surface from the center to the periphery of the cell. Alternatively, it has a reflectance distribution, and has a uniform transmittance distribution or a reflectance distribution in a direction perpendicular to the reflectance distribution.

The direction in which the transmittance or the reflectance changes is
Depending on the display to be made, it can be horizontal (or vertical) to the viewer.

According to a fifth aspect of the present invention, in the direction of the cell surface having a distribution such that the transmittance or the reflectance decreases from the center to the peripheral portion, the transmittance or the reflectance is reduced at the center of the cell. From the center to the periphery.

According to a sixth aspect of the present invention, in the direction of the cell surface having such a distribution that the transmittance or the reflectance decreases from the central portion toward the peripheral portion, the transmittance or the reflectance is reduced at the central portion of the cell. It is characterized by being constant in the vicinity and decreasing from a position distant from the center toward the periphery.

According to a seventh aspect of the present invention, light emitted from a cell which is a pixel constituting the display has a spherical wave phase distribution. The spherical wave phase distribution is appropriately selected depending on the display to be manufactured, such as a convergent spherical wave or a divergent spherical wave.

In order to provide a three-dimensional display in the above display, the invention according to claim 11 is to provide a plurality of cells for emitting light having a spherical wave phase distribution in accordance with the number of two-dimensional images described later. Each of the divided regions is a sub-cell which is a pixel unit, and each sub-cell is
In at least the horizontal direction of the sub-cell surface, the sub-cell has a transmittance distribution or a reflectance distribution that becomes lower from the center to the periphery, and each sub-cell is a pixel constituting a plurality of two-dimensional images having parallax. .

<Effect> The transmittance or reflectance of the cell is
For the changing direction (lower from the center to the periphery), the intensity of the light emitted from each cell at the periphery (particularly, the portion outside the geometrical optical image of the cell) is reduced. In addition, the uniformity of the distribution of the emitted light within the main lobe (where the pupil is located in the area where the emitted light from the specific cell reaches and the cell is visually recognized) is improved. (Claim 1) Here, with respect to two directions (X direction, Y direction) of the cell surface,
When the transmittance or the reflectance is changed, the distribution of the emitted light can be made uniform in two directions, so that the above applies to the viewer in both the vertical and horizontal directions of the display.

The transmittance or reflectance is changed only in one direction (either the X direction or the Y direction) of the cell surface, and a uniform transmittance distribution or reflectance distribution is obtained in a direction perpendicular to the cell surface. In this case, the ratio of incident light to the cell functioning as outgoing light is higher than in the case where the light is changed in two directions, and the light use efficiency is increased, so that the brightness of the display is improved.
(Claim 2)

In general, the observer's viewpoint moves in a horizontal direction in many directions. Therefore, if the transmittance or the reflectance is changed in this direction (to decrease from the center to the periphery), the observation can be performed. The display has a small change in brightness as the user moves. (Claim 3)

When the transmittance or the reflectance of the cell is changed so as to decrease from the center to the peripheral portion, the transmittance or reflectivity is gradually decreased from the center to the peripheral portion (a waveform as shown in FIG. 2). (Claim 5) When the maximum value is constant near the center and becomes lower toward the periphery from a position distant from the center to some extent (the trapezoidal waveform shown in FIG. 3). In addition, light incident on the cell can be highly efficiently contributed as output light, and the brightness as a display is improved. (Claim 6)

By making the light emitted from the cell have a spherical wave phase distribution, the emitted light can be expanded to an arbitrary range irrespective of the size of the cell. (Claim 7)

When limiting the viewing area (angle range in which a displayed image can be observed) in a specific direction of the display, it is effective to impart a spherical wave phase distribution to the light emitted from the cell. The distribution of the outgoing light in the inside tends to be non-uniform in that direction. However, when the transmittance or reflectance of each cell is changed in a direction coinciding with the above direction, the distribution of the emitted light in the above direction is made uniform, and unnecessary light ( Noise light) can be reduced. Even in this case, since the direction of movement of the viewpoint of the observer is often horizontal, the horizontal direction is more effective as the specific direction. (Claim 8)

The phase distribution of the spherical wave shape may be such that the light emitted from the cell only diverges from a specific position. It may be “divergent spherical wave shape”.
(Claims 9 and 10)

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the present invention reduces the transmittance distribution or the reflectance distribution in a cell (opening) as a pixel from at least one direction from the center to the periphery. Is a display that makes the intensity of the emitted light within the main lobe uniform.

The intensity distribution of the light emitted from the cell (opening) is
It will be related to the amplitude distribution that is its square root. The mathematical expression for the amplitude transmittance distribution or the amplitude reflectance distribution that decreases from the center to the periphery is si
Examples include an nc function, a Bartlett window function, and a generalized Hamming window function. (Hereinafter, the amplitude transmittance will be described as an example.)

[0032]

(Equation 2)

[0033]

(Equation 3)

[0034]

(Equation 4)

In the above formula, for a circular opening, x is the distance from the center of the opening, and for a rectangular opening, x is a coordinate with an axis perpendicular to any side of the rectangle and the center of the opening being 0. . Note that T is the size of the opening (diameter for a circular opening, length of one side for a rectangular opening), and -T / 2 ≦ x ≦ T
/ 2 range.

In the generalized Hamming window function, the form of the function can be optimized by α, but α = 0.5 or 0.54 is common.

A case where the transmittance distribution at the center of the opening is constant and decreases from a position distant from the center toward the periphery (trapezoidal waveform) corresponds to a trapezoidal function. However, in the present invention, it is assumed that the oblique side is not necessarily a straight line as a trapezoidal function. (That is, a function that takes a constant value near the center and decreases gently on both sides is called a trapezoidal function.)

Although a number of representative functions have been given here as the amplitude transmittance functions of the aperture, the present invention is not limited to these.

It is known that the Fourier transform of the above function has a significantly smaller amplitude value at the periphery than the Fourier transform of a rectangular function. In the optical system, the Fourier transform is equivalent to the calculation of the diffracted light distribution in the Fraunhofer region (sufficiently distant) for the aperture by the parallel light illumination. That is, the distribution of the light emitted from the aperture having these functions as the amplitude transmittance distribution has extremely small intensity at the peripheral portion.

When the light emitted from the aperture has a spherical wave phase distribution, the distribution of the emitted light is controlled by the amplitude transmission of the aperture even under normal observation conditions (the distance between the observer and the display is about 30 cm to 1 m). This is different from the Fourier transform of the rate, and tends to be more non-uniform. At this time, if the transmittance of the opening changes, the distribution of the emitted light can be made uniform, and the intensity distribution of the emitted light can be reduced in the peripheral portion.

As described above, even when the light emitted from the aperture whose transmittance has changed has a spherical wave phase distribution, the intensity at the peripheral portion can be reduced. However, in the case of having a spherical wave-like phase distribution, in the aperture represented by the rectangular function, the unevenness of the emission light distribution in the main lobe tends to be remarkable, whereas the amplitude transmittance distribution as described above , The intensity distribution of the emitted light tends to be uniform.

As means for imparting a spherical wave phase distribution to the emitted light, (1) illumination light composed of a spherical wave is made to enter an aperture. (2) The opening has a lens function, and illumination light composed of parallel light is made incident on the opening. and so on.

When the amplitude transmittance of the aperture is a trapezoidal function, the intensity at the center can be increased while the intensity distribution of the emitted light is reduced at the periphery, and the utilization efficiency of the incident light can be increased. Therefore, it is more effective. However, if the oblique side of the trapezoid is too small (closer to the rectangle), the intensity distribution of the light emitted from the opening increases in the peripheral portion, and the effect is reduced. Specifically, for example, when the size of the opening is 50 μm, if the oblique side of the trapezoid is about 10 μm (the trapezoid having a base of 50 μm and an upper side of 30 μm), there is a sufficient effect.

In displaying an image on a display having an aperture as a pixel as described above, similarly to a conventional display, the intensity or wavelength of light incident on each pixel (opening) is changed, or the aperture is changed for each pixel. The image may be displayed by changing the size or transmittance distribution of the image.

The direction in which the transmittance changes within the aperture can be horizontal and / or vertical to the observer.
6 and 7 show an opening according to the present invention, and FIG. 8 shows a conventional opening. FIG. 6 shows an opening having a transmittance distribution such that the transmittance decreases from the center to the periphery in one direction (horizontal direction) of the opening surface. FIG. For two directions (horizontal and vertical),
The aperture has a transmittance distribution that decreases from the center to the periphery. In FIG. 8, the transmittance is constant within the opening.

Usually, when viewing the display,
The observer's viewpoint position can be limited to a relatively narrow range in the vertical direction. (Because there is less displacement due to physique differences and observation postures compared to the movement of the observer in the horizontal direction.) Therefore, if the emitted light is given a spherical wave phase distribution in the vertical direction, Light utilization efficiency can be increased. However, the distribution of the emitted light tends to be non-uniform, and therefore, the distribution of the emitted light can be made uniform by changing the transmittance of the opening within the opening (in the direction perpendicular to the observer). . The same is true for the horizontal direction.

By forming the convergent spherical wave shape as the spherical wave phase distribution, it is easy to make the light emitted from the aperture incident on another element (for example, a filter for wavelength selection) arranged near the converging position. become. In particular, it is very effective when the elements have the same arrangement as the pixels of the display.

By providing a divergent spherical wave shape as the spherical wave phase distribution, if there is a place corresponding to the convergence point of the incident light before the light from the light source passes through the pixel (aperture), It is possible to arrange another element as described above at a position (a place corresponding to a convergence point).

In order to perform a display with a stereoscopic effect due to binocular parallax on such a display, an opening for emitting light having a spherical wave-like phase distribution must be arranged in a horizontal direction with respect to the observer (the left and right eyes are aligned). Direction). The number of areas to be divided depends on the number of two-dimensional images having parallax.

Each of the divided apertures has a transmittance distribution that decreases from the center to the periphery in at least one direction (at least in the horizontal direction in which the left and right eyes are aligned with the observer). And each is a pixel unit that constitutes the two-dimensional image.

By appropriately arranging the divided apertures to form a display, different two-dimensional images having parallax can be visually recognized according to the viewing direction, and an image with a three-dimensional effect can be displayed. Can be performed.

The above description also applies to the case where the amplitude reflectance distribution is changed in the aperture.

[0053]

As described above, in the display of the present invention, the intensity of the light emitted from each pixel (opening) can be reduced in the peripheral portion. Further, when the phase of the spherical wave is given to the outgoing light, it is possible to improve the uniformity of the main lobe of the distribution of the outgoing light from each pixel (aperture). Therefore, it is possible to display a uniform image with little change in the brightness of the display depending on the viewpoint position of the observer and without showing bright and dark stripes on the display surface. In particular, in the case where the intensity of light emitted from each pixel in the horizontal direction with respect to the observer (both eyes lined up) is reduced in the peripheral portion and the phase of the spherical wave is given to the emitted light, Crosstalk due to light emitted from each pixel is avoided, and the uniformity of the distribution of each emitted light in the main lobe is improved, which is more effective in displaying an image with a three-dimensional effect.

[0054]

[Brief description of the drawings]

FIG. 1 is a waveform showing a conventional transmittance distribution of light transmitted from a pixel (opening).

FIG. 2 is a waveform showing a transmittance distribution of light transmitted from a pixel (opening) according to the present invention.

FIG. 3 is a waveform showing a transmittance distribution of light transmitted from a pixel (opening) according to the present invention.

FIG. 4 is an explanatory diagram showing a configuration of a display having an opening as a cell (pixel).

FIG. 5 is a waveform showing a light intensity distribution of transmitted light from a conventional pixel (opening).

FIG. 6 is an explanatory view showing an example of a pixel (opening) of the present invention.

FIG. 7 is an explanatory diagram illustrating an example of a pixel (opening) according to the present invention.

FIG. 8 is an explanatory view showing a conventional pixel (opening).

Claims (11)

[Claims] 1. A transmittance distribution or a reflectance distribution such that the transmittance or reflectance of a cell serving as a pixel constituting a display decreases in at least one direction of a cell surface from a central portion to a peripheral portion of the cell. A display comprising: 2. A transmittance distribution or a reflectance distribution such that the transmittance or reflectance of a cell serving as a pixel constituting a display decreases in one direction of a cell surface from a central portion to a peripheral portion of the cell. A display having a uniform transmittance distribution or a uniform reflectance distribution in a direction perpendicular to the display. 3. The display according to claim 2, wherein the direction in which the transmittance or the reflectance of a cell which is a pixel constituting the display changes is horizontal to an observer. 4. The display according to claim 2, wherein a direction in which a transmittance or a reflectance of a cell serving as a pixel constituting the display changes is perpendicular to an observer. 5. The transmittance or reflectance in a direction of a cell surface having a distribution such that transmittance or reflectance of a cell serving as a pixel constituting a display decreases from a central portion to a peripheral portion. The display according to any one of claims 1 to 4, wherein the display gradually decreases from the center of the cell to the periphery. 6. The transmittance or reflectance in a direction of a cell surface having a distribution such that transmittance or reflectance of a cell serving as a pixel constituting a display decreases from a central portion toward a peripheral portion. The display according to any one of claims 1 to 4, wherein the display is constant near the center of the cell, and decreases from a position distant from the center toward the periphery. 7. The display according to claim 1, wherein light emitted from cells serving as pixels constituting the display has a spherical wave phase distribution. 8. The light-emitting device according to claim 1, wherein light emitted from a cell serving as a pixel constituting the display has a spherical wave phase distribution only in a direction in which transmittance or reflectance changes. Display according to crab. 9. The display according to claim 7, wherein the spherical wave phase distribution is a convergent spherical wave. 10. The display according to claim 7, wherein the spherical wave phase distribution is a divergent spherical wave shape. 11. A cell that emits light having a spherical wave-like phase distribution is divided into a plurality of regions according to the number of two-dimensional images described later, each of which is a subcell which is a pixel unit, and each subcell is provided to an observer. On the other hand, at least in the horizontal direction of the sub-cell surface, the sub-cell has a transmittance distribution or a reflectance distribution that decreases from the center to the periphery, and each sub-cell forms a plurality of two-dimensional images having parallax. The display according to claim 7 or 8, wherein a stereoscopic image is displayed by using pixels.