JP2001066625A - Optical device and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical device and an image display device in which bright images in almost the same level can be observed even when the left and right viewing angles differ from each other. SOLUTION: The optical device and the image display device are equipped with a LCD 2, a first TN cell 21, a combination for horizontal shift of pixels, a second TN cell 24, and a third birefringent plate 25. The LCD 2 emits polarized light with 45 deg. inclination in the counterclockwise direction from the horizontal line. The first TN cell 21 can be switched between the on-state to pass the light from the LCD 2 as it is and the off-state which changes the light into polarized light with 45 deg. inclination in the clockwise direction from the horizontal line to exit. The combination for horizontal shift of pixels is composed of a first birefringent plate 22 having a projection crystal axis with 45 deg. inclination in the lower right direction and a second birefringent plate 23 having a projection crystal axis with 45 deg. inclination in the lower left direction. The second TN cell 24 can be switched between the on-state to pass the light from the second birefringent plate 23 as it is and the off-state which changes the light into polarized light with perpendicular polarization to that of the incident light to exit the plate. The third birefringent plate 25 has a projection crystal axis with 45 deg. inclination in the upper right direction and shifts the pixels in the oblique direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device and an image display device, and more particularly, to an optical device and an image display device capable of observing an image having an apparently higher resolution than that of a display element by performing pixel shift. Related to the device.

[0002]

2. Description of the Related Art Conventionally, video display devices using CRTs have been widely used, but in recent years, video display devices using liquid crystal display elements and the like have been gradually increasing market share.

In such a video display device, the definition of an image to be displayed is basically determined by the number of pixels constituting the liquid crystal display element. However, when the number of pixels is increased to obtain a high definition image, The cost of the liquid crystal display element increases,
A higher-speed signal processing circuit may be required.

Therefore, a technique for displaying a higher definition image using a liquid crystal display element having a limited number of pixels has been developed.

As such a technique, for example, Japanese Patent Application Laid-Open
-63332 and JP-A-7-36054,
A device that shifts the optical axis of light from a display element by using a birefringent plate is described. More specifically, for example, the optical axis of light emitted from a liquid crystal display element is shifted in a time-series manner, Are sequentially shifted to increase the number of observed pixels. Further, in these publications, it is described that one frame is divided into four sub-fields, and a technique of four-point pixel shift for shifting an apparent pixel position for each of these sub-fields and a technique of further multi-point pixel shift are described. Have been.

[0006] As a display element used in the above-described image display device, an LCD or the like that emits light polarized in the horizontal or vertical direction has been generally used.

[0007]

However, when a display element of the type which emits light polarized in the horizontal or vertical direction as described above is used, when the display element is observed from an oblique right direction, It is known that there is a property that the appearance is different from the case of observing from the left oblique direction.

For this reason, when such a display element is applied to a left-eye display element and a right-eye display element of a video display device of a type that can be observed with both eyes, individual differences between users, that is, Since the size of the head and the distance between the left and right eyes are different from each other, there may be a difference in the viewing angle between the display element for the right eye and the display element for the left eye.
In such a case, the state of the image observed by the user will be different.

Means for providing an interpupillary adjustment mechanism or the like can be considered to cope with such a point. However, if such a mechanism is incorporated, the size and weight of the head-mounted image display device increase and the weight increases.
This may lead to higher costs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide an optical device and a video display device that can observe substantially the same image even at different perspective angles.

[0011]

In order to achieve the above object, an optical device according to a first aspect of the present invention performs a pixel shift by optically shifting a light beam emitted from each pixel of a display element. An optical device that makes it possible to observe an image having an apparently higher resolution than the resolution of the display element, and the polarized light emitted from the display element is not orthogonal to one side constituting the display surface of the display element. And a first modulation element that switches to and emits polarized light of two polarization planes orthogonal to each other, and is substantially parallel to one of the two polarization planes related to the polarized light emitted from the first modulation element. And a second birefringent medium having a crystal axis substantially parallel to the other of the two polarization planes of the polarized light emitted from the first modulator. And the display element When one pixel is shifted to two pixels positioned substantially parallel to one side of the display surface, polarized light emitted from the first modulation element is passed through the first birefringent medium. Later, the second birefringent medium is passed.

The optical device according to a second aspect of the present invention is the optical device according to the first aspect, wherein polarized light emitted from the second birefringent medium is orthogonal to one side constituting a display surface of the display element. A second modulating element for switching the polarized light to two polarization planes orthogonal to each other and emitting the light, and a polarized light emitted from the second modulation element being incident and one of the two polarization planes A third birefringent medium having a crystal axis substantially parallel to the plane of polarization.
Light rays emitted from each pixel of the display element emitted from the birefringent medium are shifted by pixels to respective positions corresponding to the four vertices of the parallelogram, and an image having a resolution apparently higher than the resolution of the display element is obtained. Observable.

Further, the optical device according to the third aspect of the present invention shifts the pixels by optically shifting the light rays emitted from the respective pixels of the display element, so that the resolution is apparently higher than the resolution of the display element. An optical device capable of observing an image, wherein polarization emitted from the display element is switched to polarization of two polarization planes which are not orthogonal to one side constituting a display surface of the display element and which are orthogonal to each other. And a third birefringence having a crystal axis on which polarized light emitted from the second modulator is incident and which is substantially parallel to one of the two polarization planes. The medium and the polarized light emitted from the third birefringent medium are switched to polarized light of two polarization planes which are not orthogonal to one side constituting the display surface of the display element and which are orthogonal to each other, and emitted. 1 A modulating element, a first birefringent medium to which polarized light emitted from the first modulating element is incident and which has a crystal axis substantially parallel to one of two polarization planes related to the polarized light; A second birefringence having a crystal axis substantially parallel to the other of the two polarization planes of the two polarization planes of the polarized light emitted from the first birefringent medium and incident on the polarized light emitted from the first modulation element; A light beam emitted from each pixel of the display element emitted from the second birefringent medium is shifted by a pixel to each position corresponding to four vertices of a parallelogram, and the resolution of the display element This makes it possible to observe an image with an apparently higher resolution than that.

An image display device according to a fourth aspect of the present invention is the image display device according to the first, second, or third aspect, further comprising: a polarizing surface having an inclination of approximately 45 degrees with respect to one side constituting its own display surface. And a liquid crystal display element that emits polarized light of

[0015]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 8 show a first embodiment of the present invention. FIG. 1 is a block diagram showing an electrical and optical configuration of a video display device to which an optical device is applied, and FIG. 2 is an LCD. FIG. 3 is a diagram showing a state of pixels arranged in a delta arrangement above, FIG. 3 is a diagram showing an apparent pixel array achieved by shifting the apparent positions of pixels in time series, and FIG. 4 is a pixel skip as one configuration example FIG. 5 is a perspective view showing the optical element exploded in the optical axis direction, FIG. 5 is a view showing an apparent pixel position achieved by a combination of ON / OFF of the first TN cell and the second TN cell, and FIG. FIG. 7 is a perspective view exploded in the direction of the optical axis, FIG. 7 is a view showing the direction of the crystal axis of each birefringent plate viewed from the eyepiece side, and FIG. 8 is a diagram in which a pixel image of the LCD passes through each component of the optical element. Is a diagram showing how the position changes due to .

As shown in FIG. 1, the optical system of the image display device includes a backlight 1 that emits illumination light, and an LCD (light emitting illumination light emitted by the backlight 1 to emit a light flux of an image displayed). Liquid crystal display element) 2 and this LCD
The pixel and the optical element 3 as an optical device for sequentially shifting the apparent position of the pixel by shifting the optical axis of the pixel light flux emitted from the pixel 2 in time series and the image of the pixel passing through the pixel and the optical element 3 And an eyepiece optical system 4 capable of being enlarged for observation.

Next, the electric circuit of the video display device is based on a video signal processing circuit 5 for performing signal processing including double speed processing and the like on an input video signal and an output processed by the video signal processing circuit 5. An LCD drive circuit 6 for driving the LCD 2 and a video synchronization signal and a field discrimination signal output from the LCD drive circuit 6,
A pixel and a skip control circuit 7 for driving the pixel and the skip optical element 3 in synchronization with D2 are provided.

As shown in FIG. 2, the LCD 2 has a plurality of pixels 2a regularly arranged in a two-dimensional manner such as a delta arrangement. This delta array is
Assuming that the horizontal pitch between pixels is Px and the vertical pitch is Py, the odd and even lines of the pixel array are horizontally shifted by Px / 2.

An image display apparatus using such a four-point pixel shift is disclosed in Japanese Patent Application No. 10-3364 by the present applicant.
No. 82 describes this in detail.

FIG. 3A shows an example in which the apparent positions of the pixels in such a delta arrangement are shifted by using the above-mentioned pixel skipping optical element 3. This pixel skipping optical element 3
Is configured to be able to shift the apparent position of a pixel in two independent directions in a plane perpendicular to the ray, and more specifically to shift the apparent position of the pixel in the horizontal and diagonal directions. Is available.

That is, first, it is assumed that the pixel at a certain point is located at the position indicated by number 1. In the next subfield, this is shifted in the horizontal right direction by Px / 2 to move to the apparent position indicated by number 2.

Further, in the next subfield, for example, by shifting by Px / 4 in the horizontal left direction and by Py / 2 in the vertical upward direction, it moves to the apparent position indicated by the number 3 in the upper left diagonal.

Then, in the next subfield, for example, by shifting Px / 2 in the horizontal left direction, it moves to the apparent position indicated by number 4.

In a further subfield,
For example, by shifting by Px / 4 in the horizontal right direction and by Py / 2 in the vertical downward direction, it returns to the apparent position indicated by the above number 1.

The order in which the apparent positions of the pixels are shifted is not limited to this. For example, the positions may be shifted as shown in FIG. 3B.

As described above, one frame of image is
The image is divided into two sub-frames, and the positions of the pixels are shifted for each sub-frame. The pixels in the screen are filled with the shifted apparent pixel positions so that the pixel density (resolution) increases in both the horizontal and vertical directions. Display.

By the way, as a technique that may solve the problem caused by using an LCD of a type that emits light polarized in the horizontal direction or the vertical direction as described above, there is a diagonal right direction of 45 ° or a left direction. An LCD that emits light polarized in an oblique direction of 45 ° may be used. This type of LCD has a property that, even when an image is observed from a direction inclined left and right, the image is observed almost in the same manner.

FIG. 4 and FIG. 4 show an example of a configuration in which such an LCD is combined with a technique for increasing the apparent number of pixels by shifting pixels as described in Japanese Patent Application No. 10-336482. This will be described with reference to FIG.

Since the light emitted from the LCD 2 has passed through the liquid crystal, it has already been polarized in one direction. As described above, this LCD 2 emits the light polarized in the oblique direction of 45 °. For example, as shown in the figure, light of a polarization direction from the upper left to the lower right is emitted.

Since the LCD 2 emits light in an oblique direction, the light is then, for example, leveled by the polarizing plate 11 so that the apparent position of the pixel can be shifted by the skipping optical element 3 after that. The light is converted into light polarized in the direction.

Thereafter, by turning on / off the first TN cell 12, the polarization direction of the light is switched. Specifically, when the first TN cell 12 is turned on, the light passes through with the polarization in the horizontal direction. The light is converted into vertically polarized light and passes therethrough.

The light passing through the first TN cell 12 enters the first birefringent plate 13. This first birefringent plate 13 is
A crystal such as quartz or lithium niobate (LiNbO3) is formed so that its crystal axis forms an angle of 45 degrees in the x-axis direction with respect to the thickness direction (z-axis direction), that is, (x, y, z) = (1, 0, 1) direction, the light is polarized in the vertical direction, and the light polarized in the horizontal direction is refracted. In the example of FIG. The light is emitted shifted.

The displacement of the position at this time is determined by the first
Determined by the thickness of the birefringent plate 13, that is, LC
The thickness is formed to be an appropriate shift amount corresponding to the pixel pitch of D2.

Thus, if the first TN cell 12 is on and has a horizontal polarization direction, it is shifted in the x direction of the figure, while the first TN cell 12 is off and has a vertical polarization direction. In the case of polarized light, it passes almost as it is.

Next, by turning on / off the second TN cell 14, the polarization direction of light is further switched.
Specifically, when the light is turned on, the light passes through the light in almost any state regardless of the polarization state in the horizontal direction or the vertical direction, and when the light is turned off, the light in the horizontal direction is polarized in the vertical direction. , And the vertically polarized light is converted into the horizontally polarized light and passed.

The polarization direction of the light at the time of passing through the second TN cell 14 is determined by the first TN cell 12 and the second TN cell 14.
If the combination of on / off is off-off, there is no horizontal shift. If off-on, there is no vertical shift. If on-off, there is a vertical shift in the x direction. If on-on, there is a shift in the x direction in the horizontal direction.

The light emitted from the first second TN cell 14 subsequently enters the second birefringent plate 15. This second
As described above, the birefringent plate 15 is made of a crystal such as quartz or lithium niobate (LiNbO3), and its crystal axis forms an angle of 45 degrees in the -x-axis direction with respect to the thickness direction (z-axis direction). Thus, (x, y, z) = (-1 ,,
It is formed to have a vector component in the 0,1) direction. Thus, the second birefringent plate 15 shifts the above-mentioned polarized light in the horizontal direction in the -x direction, and passes the polarized light in the vertical direction almost as it is.

The polarized light further enters the third birefringent plate 16. The third birefringent plate 16 is also formed of crystal in the same manner as described above, and its crystal axis forms an angle of 45 degrees with respect to the thickness direction (z-axis direction) in the y-axis direction, that is, (x , Y, z) = (0, 1, 1) direction. Thus, this third
The birefringent plate 16 allows the above-mentioned horizontal polarized light to pass almost as it is and shifts the vertical polarized light to the y direction, thereby achieving the pixel position as shown in FIG. 5B.

The combination of ON / OFF of the first TN cell 12 and the second TN cell 14 is repeatedly performed in the order shown in FIG.
The positions corresponding to the four vertices of the parallelogram are cyclically moved, such as the numbers 1 → 2 → 3 → 4 → 1 shown in (B), and the number of pixels is determined by the effect of the afterimage of the human eye. Is observed to increase.

However, in the configuration using an LCD that emits light polarized in an oblique direction as described above, once,
Since the light is converted into polarized light in the horizontal direction using a polarizing plate, the amount of light is reduced to about 1/2, so that the observed image is not darkened or the image is not darkened. In addition, it is necessary to increase the brightness of the backlight, which leads to an increase in cost and an increase in power consumption.

A configuration for further improving such a point will be described with reference to FIGS.

As shown in FIG. 6, an optical device applied to this video display device has an LCD 2 that emits light polarized in an oblique direction of 45 ° in the same manner as described above, and turns the light from this LCD 2 on / off. The first TN cell 21 which is a first modulation element that switches to polarization in two directions orthogonal to each other in accordance with the OFF state, and the optical path of light polarized in one direction out of the light passing through the first TN cell 21 is shifted. A first birefringent plate 22, which is a first birefringent medium and forms a part of the birefringent medium for horizontal shift, and an optical path of light polarized in the other direction out of the light passing through the first TN cell 21. A second birefringent plate 23, which is a second birefringent medium that shifts to a different position on the same horizontal plane and forms a part of the birefringent medium for horizontal shift, and turns on / off light that has passed through the second birefringent plate 22. Deflection in two directions orthogonal to each other depending on the off state And a third birefringent medium that shifts the optical path of light polarized in one direction out of the light that has passed through the second TN cell 24. And a third birefringent plate 25 as a birefringent medium.

In the pixel skipping optical element 3, a horizontal pixel shift unit 3h is configured to include the first TN cell 21, the first birefringent plate 22, and the second birefringent plate 23.
The oblique pixel shift unit 3o includes the second TN cell 24 and the third birefringent plate 25.

Further, as shown in FIG. 6, the crystal axis of each birefringent plate is formed so as to form an angle of 45 degrees with the thickness direction (z-axis direction). The direction when the axis is projected on the xy plane is as shown in FIG.

That is, these birefringent plates 22, 23, 2
FIG. 7A and FIG.
7 (B) and FIG. 7 (C), the first birefringent plate 22 has a crystal axis direction obliquely downward to the right, the second birefringent plate 23 has a crystal axis direction obliquely downward to the left, and the third birefringence. The plate 25 is observed in a crystal axis direction obliquely upward to the right.

More specifically, the first birefringent plate 22 is
The second birefringent plate has a crystal axis having a vector component in the (x, y, z) = (1, −1, √2) direction.
The third birefringent plate 25 has a crystal axis of (x, y, z) such that the crystal axis has a vector component in the (x, y, z) = (-1, -1, √2) direction. z) = (1, 1, .SIGMA.2) are formed of crystal such as quartz or lithium niobate (LiNbO3) so as to have a vector component in the (1,1, .SIGMA.2) direction. Here, the symbol √ represents a square root.

As described above, in the configuration of the pixel skipping optical element shown in FIG. 6, the polarizing plate 11 as shown in FIG. 4 is not provided, and the amount of light may be reduced by the polarizing plate 11. Not to be.

Next, the manner in which the apparent position of the pixel on the LCD 2 is changed by the pixel skipping optical element 3 configured as described above will be described with reference to FIG.

It is assumed that the LCD 2 emits light in a 45 ° oblique polarization direction from the upper left to the lower right as shown in FIG. 8A, for example.

When such light is incident on the first TN cell 21, the first TN cell 21 switches the polarization direction of the light according to its ON / OFF state. To the lower right, the light is passed as it is at an oblique angle of 45 ° (hereinafter, referred to as first polarized light), and by turning off the light, the light is oblique 45 ° from upper right to lower left.
(Hereinafter, referred to as second polarized light) and pass it (see FIG. 8B).

Subsequently, light enters the first birefringent plate 22. As shown in FIG. 7A, the first birefringent plate 22 has a crystal axis direction extending from the upper left to the lower right, and forms an optical path of the first polarized light of the incident light. FIG.
As shown in (C), the light is shifted obliquely downward to the right, and the second polarized light is passed almost as it is.

Next, light enters the second birefringent plate 23.
As shown in FIG. 7B, the second birefringent plate 23 has a crystal axis direction extending from the upper right to the lower left.
The optical path of the second polarized light in the incident light is shifted obliquely downward to the left as shown in FIG. 8D, and the first polarized light is passed almost as it is. Note that positions corresponding to pixels on the LCD 2 are indicated by dotted lines.

Further, light enters the second TN cell 24. The second TN cell 24 is also turned on / off in the same manner as described above.
It switches the polarization direction of light according to the OFF state.Specifically, turning ON switches the polarization of light into light without changing it, and turning OFF switches the polarization of light into orthogonal directions. And let it pass.

As a result, the polarization direction and shift position of the light at the time of passing through the second TN cell 24 are as shown in FIG.
As shown in (E), when the combination of on / off of the first TN cell 21 and the second TN cell 24 is off-off, the first polarized light is shifted obliquely downward to the left and off-on. In the case, there is a shift to the left diagonally downward in the second polarized light. In the case of on-off, there is a shift in the diagonal downward right of the second polarized light. There is a downward shift.

Thereafter, the light enters the third birefringent plate 25. As shown in FIG. 7C, the third birefringent plate 25 has a crystal axis direction extending from the lower left to the upper right, and illustrates the optical path of the second polarized light among the incident light. 8
As shown in (F), the light is shifted obliquely to the upper right and the first polarized light is passed almost as it is.

In this manner, the combination of ON / OFF of the first TN cell 21 and the second TN cell 24 is repeatedly performed in the same order as shown in FIG. Number 1 → 2 → 3 shown in 5 (B)
As in the case of → 4 → 1, each position corresponding to the four vertices of the parallelogram is cyclically moved, and the number of pixels is observed due to the effect of the afterimage of the human eye.

In the above description, the direction of the crystal axis of the birefringent plate is approximately 45 degrees in the xy plane as shown in FIG.
°, the present invention is not limited to this, and the pixel pitch P
To match x, Py and other configurations, this 45
It may be arranged so as to be slightly shifted with respect to °.

More specifically, for example, a horizontal pixel pitch Px = 42 (μm) and a vertical pixel pitch Py = 3
When the LCD 2 having a pixel arrangement of 7 (μm) is used, a birefringent plate having an inclination of 60 ° or 30 ° with respect to the x-axis may be used when the crystal axis is projected on the xy plane. Conceivable.

At this time, for example, the second birefringent plate 22 is set so that the crystal axis of the first birefringent plate 22 has a vector component in the (x, y, z) = (√3, −1, 2) direction. The plate has 23 crystal axes (x, y, z) = (-1, -√3, 2)
The third birefringent plate is formed so that the crystal axes of 25 have vector components in the (x, y, z) = (1, √3, 2) directions so as to have vector components in the directions. Good.

In such an arrangement, the direction of the crystal axis intersects the polarization direction of the light emitted from the LCD 2 by 45 °, which is approximately 15 °, so that
Although some leakage light is generated, the leakage light amount is, for example, less than 7%, and thus hardly affects the actually observed image.

According to the first embodiment, an LCD which emits light polarized in an oblique direction of 45 ° is used, so that the appearance of an image is different even if the left and right perspective angles are different. But can be easily observed.
In addition, since it is possible to cope with individual differences such as a difference in the interpupillary distance of a user without providing an interpupillary adjusting mechanism or the like, it is possible to reduce costs and reduce the size and weight of the apparatus.

Further, by adopting the configuration as shown in FIG. 6, since the polarizing plate as shown in FIG. 4 becomes unnecessary, the light from the LCD is not dimmed.
Bright images can be enjoyed. Also, in order to achieve the same brightness, the amount of light from the backlight is smaller, so that power can be saved. In addition, the use of a smaller backlight reduces costs and reduces size and weight. Can be achieved.

In addition, the configuration shown in FIG. 6 only requires adjusting the direction in which each birefringent plate is cut out from a wafer or the like, and requires a special additional configuration and complicated manufacturing steps. However, it is a very excellent configuration that can improve the optical performance without increasing the cost.

FIGS. 9 to 11 show a second embodiment of the present invention. FIG. 9 is a perspective view showing a pixel skipping optical element exploded in the optical axis direction, and FIG. 10 is a view seen from the eyepiece side. FIG. 11 is a diagram showing the direction of the crystal axis of each birefringent plate, and FIG. 11 is a diagram showing apparent pixel positions achieved by a combination of ON / OFF of the first TN cell and the second TN cell.

In the second embodiment, the first
The same components as those of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. Only different points will be mainly described.

As shown in FIG. 9, the optical device applied to the video display device of the second embodiment is a horizontal pixel shift unit 3 in the optical device of the first embodiment.
h and the order of the oblique pixel shifting unit 3o are interchanged.

That is, as shown in FIG. 9, this optical device has an LCD 2 that emits light polarized in an oblique direction of 45 ° in the same manner as described above, and turns the light from the LCD 2 on / off.
A first TN cell 31 serving as a second modulation element that switches to polarized light in two directions orthogonal to each other in accordance with the off state;
A first birefringent plate 32, which is a third birefringent medium and a birefringent medium for oblique shift, which shifts the optical path of light polarized in the other direction out of the light that has passed through the TN cell 31; A second TN cell 33 serving as a first modulation element for switching light passing through the refraction plate 32 into two orthogonal polarizations according to the on / off state of the light, and one of the light passing through the second TN cell 33; A second birefringent plate 34, which is a first birefringent medium for shifting the optical path of light polarized in the direction to different positions on the same horizontal plane and forms a part of the birefringent medium for horizontal shift, and the second birefringent plate A third birefringent plate 35 that is a second birefringent medium that shifts the optical path of light polarized in the other direction out of the light that has passed through the plate 34 and that forms a part of the birefringent medium for horizontal shift. It is configured.

In the pixel skipping optical element 3, an oblique pixel shift unit 3 o including the first TN cell 31 and the first birefringent plate 32 is formed, and the second TN cell
The horizontal pixel shift unit 3h includes the cell 33, the second birefringent plate 34, and the third birefringent plate 35.

The crystal axis of each birefringent plate is formed so as to form an angle of 45 degrees with respect to the thickness direction (z-axis direction) as shown in FIG. The direction when the axis is projected on the xy plane is as shown in FIG.

That is, these birefringent plates 32, 34, 3
FIG. 10 (A), FIG.
0 (B) and FIG. 10 (C), the first birefringent plate 3
Reference numeral 2 indicates a crystal axis direction obliquely downward and left, the second birefringent plate 34 is observed as a crystal axis direction obliquely downward to the right, and a third birefringent plate 35 is observed as a crystal axis direction obliquely downward and to the left.

More specifically, the first birefringent plate 32 is
The second birefringent plate has a height of 34 so that the crystal axis has a vector component in the (x, y, z) = (-1, -1, √2) direction.
Is set so that the crystal axis has a vector component in the (x, y, z) = (1, −1, √2) direction.
Are formed such that the crystal axes have vector components in the (x, y, z) = (-1, -1, √2) directions.

Next, the change in the apparent position of the pixel on the LCD according to such a configuration is as follows.

The LCD 2 emits light in the 45 ° oblique polarization direction from the upper left to the lower right and enters the first TN cell 31. When the first TN cell 31 is turned on, the light is changed from the upper left to the lower right. The light is passed as it is at an oblique 45 ° polarization (hereinafter, referred to as first polarized light), and turned off to convert the light into an oblique 45 ° polarized light (hereinafter, referred to as second polarized light) from the upper right to the lower left. Let it.

Subsequently, the light is incident on the first birefringent plate 32. As shown in FIG. 10A, the first birefringent plate 32 has a crystal axis direction from the upper right to the lower left, and shifts the optical path of the second polarized light of the incident light to the left. The light is shifted obliquely downward, and the first polarized light is passed almost as it is.

Next, the light enters the second TN cell 33.
Similarly, by turning on the second TN cell 33, the second TN cell 33 passes the light as it is without changing the polarization, and turning off the second TN cell 33 converts the polarization of the light in a direction orthogonal to the second TN cell 33 and passes it.

As a result, the polarization direction and the shift position of the light at the time when the light has passed through the second
When the on / off combination of the N cell 31 and the second TN cell 33 is off-off, the first polarized light is shifted obliquely downward to the left, and when the combination is off-on, the second polarized light is left. When there is a shift in the obliquely downward direction, there is no shift in the second polarized light when it is on-off, and there is no shift in the first polarized light when it is on-on.

Further, light enters the second birefringent plate 34. As shown in FIG. 10B, the second birefringent plate 34 has a crystal axis direction extending from the upper left to the lower right, and forms an optical path of the first polarized light of the incident light. The light is shifted obliquely downward to the right, and the second polarized light is passed almost as it is.

Thereafter, the light is incident on the third birefringent plate 35. As shown in FIG. 10C, the third birefringent plate 35 has a crystal axis direction extending from the upper right to the lower left, and shifts the optical path of the second polarized light of the incident light to the left. The light is shifted obliquely downward, and the first polarized light is passed almost as it is.

Thus, the combination of ON / OFF of the first TN cell 31 and the second TN cell 33 is shown in FIG.
By repeatedly performing the order as shown in FIG. 11A, pixel positions corresponding to four vertices of a parallelogram such as numbers 1 → 2 → 3 → 4 → 1 shown in FIG. Move cyclically.

According to the second embodiment, even when the horizontal pixel shift unit and the oblique pixel shift unit are combined in the reverse order along the optical axis, almost the same effects as in the first embodiment described above can be obtained. be able to.

In each of the above-described embodiments, an example is shown in which an LCD (liquid crystal display element) is used as a display element.
The present invention is not limited to this, and other types of display elements, for example, FED (field emission display), DMD (digital micromirror device), LED display element (light emitting diode display element) and the like can be used. I do not care. However, these FED, DMD, L
Since the light emitted from the ED display element does not have the polarization characteristics as in the above LCD, in order to use it instead of the LCD as described in the above embodiment, a polarizing plate in an oblique direction after emitting the light is required. Need to pass through.

The present invention is not limited to the above-described embodiments, and it is needless to say that various modifications and applications are possible without departing from the gist of the invention.

[Appendix] According to the above-described embodiment of the present invention as described in detail above, the following configuration can be obtained.

(1) A display element in which a plurality of pixels are arranged on a substantially rectangular display surface, and a display element that emits polarized light having a polarization plane inclined at approximately 45 degrees with respect to one side of the display surface; It is possible to switch between a state in which the incident polarized light is transmitted and emitted without changing the polarization plane, and a state in which the polarized plane after emission is converted so as to be orthogonal to the polarization plane before incidence and then emitted. The modulation element and the polarized light incident from this one modulation element are converted into a state in which the polarized light is passed through and emitted without changing the polarization plane, and the polarization plane after the emission is orthogonal to the polarization plane before the incidence. And the other modulating element that can be switched to, and the crystal axis projected on its main surface,
The display device is configured to have a crystal axis that is an oblique direction that is a direction that intersects without being orthogonal to one side of the display surface of the display element, and converts the polarized light having a polarization plane substantially parallel to the crystal axis to the oblique direction. While moving the optical axis in the direction, the birefringent medium for oblique shift that allows polarized light having a polarization plane substantially perpendicular to the crystal axis to pass almost as it is without moving the optical axis, and the crystal axis projected on its main surface is The display device includes a plurality of birefringent media each having a crystal axis that is in the oblique direction and having a projected crystal axis in a direction independent of each other. A birefringent medium for horizontal shift for moving the optical axis in a horizontal direction parallel to one side of the display surface of the display device, wherein one of the birefringent medium for oblique shift and the birefringent medium for horizontal shift is Modulation elements and other While disposed between the tone element,
An image display device characterized in that the other is arranged behind the other modulation element on the optical path.

Therefore, according to the invention described in Appendix (1), it is possible to observe substantially the same bright image even if the expected angle is different from left to right.

[0086]

As described above, according to the optical apparatus of the first aspect of the present invention, it is possible to observe substantially the same image even at different perspective angles.

Further, according to the optical device of the present invention according to the second aspect, the same effect as that of the first aspect is obtained, and the pixel is shifted to each position corresponding to the four vertices of the parallelogram. Therefore, the resolution in the horizontal and vertical directions can be improved.

Further, according to the optical device of the present invention, it is possible to observe substantially the same image even at different perspective angles, and furthermore, it is possible to observe each of the four vertices of the parallelogram. Since the pixel is shifted to the position, the resolution in the horizontal and vertical directions can be improved.

According to the video display apparatus of the present invention, the same effects as those of the first to third aspects can be obtained, and the liquid crystal display element can be arranged with respect to one side constituting the display surface. Since the polarized light is emitted at a polarization plane having an inclination of about 45 degrees, substantially the same image can be observed at different expected angles in the left-right direction.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical and optical configuration of a video display device to which an optical device according to a first embodiment of the present invention is applied.

FIG. 2 is a diagram showing a state of pixels arranged in a delta on the LCD according to the first embodiment.

FIG. 3 is a diagram showing an apparent pixel arrangement achieved by shifting the apparent positions of pixels in time series in the first embodiment.

FIG. 4 is a perspective view showing a pixel skipping optical element as an example of the configuration according to the first embodiment, which is disassembled in an optical axis direction.

FIG. 5 is a diagram showing apparent pixel positions achieved by a combination of ON / OFF of a first TN cell and a second TN cell in the first embodiment.

FIG. 6 is an exemplary perspective view of the pixel skipping optical element according to the first embodiment, which is disassembled in an optical axis direction.

FIG. 7 is a diagram showing a direction of a crystal axis of each birefringent plate viewed from the eyepiece side in the first embodiment.

FIG. 8 is a diagram showing how the position of a pixel image of the LCD changes when the image passes through each component of the pixel skipping optical element in the first embodiment.

FIG. 9 is an exemplary perspective view of a pixel skipping optical element according to a second embodiment of the present invention, which is disassembled in an optical axis direction.

FIG. 10 is a diagram showing a direction of a crystal axis of each birefringent plate viewed from the eyepiece side in the second embodiment.

FIG. 11 is a diagram showing apparent pixel positions achieved by a combination of ON / OFF of a first TN cell and a second TN cell in the second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Back light 2 ... LCD 3 ... Pixel skipping optical element (optical apparatus) 3h ... Horizontal pixel shift unit 3o ... Oblique pixel shift unit 11 ... Polarizer 12 ... 1st TN cell 13 ... 1st birefringent plate 14 ... 2nd TN cell 15: second birefringent plate 16: third birefringent plate 21: first TN cell (first modulating element, one modulating element) 22: first birefringent plate (first birefringent medium, horizontal shift birefringent plate) 23. Second birefringent plate (second birefringent medium, part of horizontal shift birefringent medium) 24 ... second TN cell (second modulating element, other modulating element) 25 ... Third birefringent plate (third birefringent medium, birefringent medium for oblique shift) 31 ... first TN cell (second modulator, one modulator) 32 ... first birefringent plate (third birefringent) Refractive medium, birefringent medium for oblique shift) 33... Second TN cell (first Modulation element, other modulation element) 34: second birefringent plate (first birefringent medium, part of horizontal shifting birefringent medium) 35: third birefringent plate (second birefringent medium, horizontal shifting) A part of birefringent medium)

Claims (4)

[Claims] An optical device that shifts pixels by optically shifting light rays emitted from each pixel of a display element, thereby enabling an image having a resolution apparently higher than the resolution of the display element to be observed. Wherein the polarized light emitted from the display element is not orthogonal to one side constituting the display surface of the display element, and is switched to polarized light of two orthogonal polarization planes and emitted. A first modulation element; a first birefringent medium having a crystal axis substantially parallel to one of two polarization planes of polarized light emitted from the first modulation element; A second birefringent medium having a crystal axis substantially parallel to the other polarization plane of the two polarization planes of the polarized light emitted from the element, wherein one pixel of the display element constitutes the display surface Located almost parallel to one side An optical device, wherein, when shifting a pixel to two pixels, the polarized light emitted from the first modulation element passes through the first birefringent medium and then passes through the second birefringent medium. . 2. The polarized light emitted from the second birefringent medium is switched to polarized light of two polarization planes which are not orthogonal to one side constituting a display surface of the display element and which are orthogonal to each other. A second modulation element that emits the polarized light, and a polarized light that is emitted from the second modulation element is incident on the second modulation element, and
A third birefringent medium having a crystal axis that is substantially parallel to one of the two polarization planes, further comprising: a third birefringent medium that emits light from the third birefringent medium. 2. The emitted light beam is shifted by a pixel to each position corresponding to four vertices of a parallelogram, so that an image having a resolution apparently higher than the resolution of the display element can be observed. Optical device. 3. An optical device which shifts pixels by optically shifting light rays emitted from each pixel of a display element, thereby observing an image having a resolution apparently higher than the resolution of the display element. Wherein the polarized light emitted from the display element is not orthogonal to one side constituting the display surface of the display element, and is switched to polarized light of two orthogonal polarization planes and emitted. And a polarization element emitted from the second modulation element, and
A third birefringent medium having a crystal axis substantially parallel to one of the two polarizing planes, and polarized light emitted from the third birefringent medium constitute a display surface of the display element. Not orthogonal to one side
A first modulation element that switches to and emits polarized light of two polarization planes orthogonal to each other; and a polarized light that is emitted from the first modulation element enters and
A first birefringent medium having a crystal axis substantially parallel to one of the two polarization planes of the polarized light; a polarized light emitted from the first birefringent medium being incident on the first birefringent medium; And a second birefringent medium having a crystal axis substantially parallel to the other polarization plane of the two polarization planes of the polarized light emitted from the first modulation element, and emitted from the second birefringent medium. The light emitted from each pixel of the display element is shifted to each position corresponding to the four vertices of the parallelogram so that an image having a resolution apparently higher than the resolution of the display element can be observed. Characteristic optical device. 4. An optical device according to claim 1, 2 or 3, and a liquid crystal that emits polarized light having a polarization plane inclined at approximately 45 degrees with respect to one side constituting its own display surface. A video display device, comprising: a display element.