JPH05100204A - Display device - Google Patents

Abstract

PURPOSE:To shorten the focal length of a lens by shortening the effective optical path length between the lens and a dot when the display device is constituted for the purpose of a stereoscopic display. CONSTITUTION:In front of a dot 2b of a two-dimensional display DP, a microlens 1b is provided corresponding to the dot 2b, and an optical path length variation part 3 and a diffusion layer 4 are provided. In this case, a plane on which the lens is put in focus when the two-dimensional display is observed with the eyes of an observer is not nearby the orienting film 7b of the two- dimensional display DP, but nearby the diffusion layer 3 to equalize the substantial optical path length to the optical path length between the microlens 1b and diffusion layer 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device used in computers, television receivers and the like.

[0002]

2. Description of the Related Art In recent years, three-dimensional images (including stereoscopic images) as seen in computer graphics displays.
There is an increasing need for a technology for displaying the, for example, the document “Image Lab, November 1990, pp. 20-24”.
As disclosed in Japanese Patent Laid-Open No. 2003-242242, a system that actually uses binocular parallax is widely used as a three-dimensional display device. The method using binocular parallax is roughly classified into an eyeglass method and an eyeglass-less method. The method without glasses is
For example, the document “Television Society Journal Vol. 44, No. 5,
Pp. 591-597, 1990 ", it is considered to be used as a television receiver because of its generality.

On the other hand, the spectacle system includes a method using a simple polarizing plate and a color filter for the spectacles, a method having a shutter function in the spectacles, and a method having a two-dimensional display in the spectacles.

In the spectacles method, a method of using a simple polarizing plate is generally used, and a method of projecting two images having different polarizations on a large screen such as IMAX Co., Ltd., or a two-dimensional method such as Sony Tektronix Co., Ltd. There is a method in which a shutter of a polarization filter is provided on the front surface of the display and time-division driving is performed while changing the polarization direction.

Further, in the spectacles system, a spectacle having a two-dimensional display is disclosed in, for example, the document “Image Lab”.
As shown in January 1991, page 29 to page 33 "and the document" Image Lab, January 1991, page 20 to page 23 ", it is also called a head-mounted display (HMD), and has recently been used. It is attracting attention due to research on artificial reality.

[0006]

However, most of the above-mentioned various types of display devices are three-dimensional displays using only binocular parallax,
Since information is displayed stereoscopically using the so-called illusion with only binocular disparity, the eye adjustment mechanism (mechanisms such as focus adjustment) and the vergence mechanism (movement mechanism that gazes at an object) often do not match, Generally, there is a drawback that eye fatigue accumulates when the display is continuously viewed for 20 minutes or more. FIG. 11 is a diagram for explaining this state. For example, two images P1 and P2 are displayed on the screen 210 at a predetermined interval Z, and the two images P1 and P2 are displayed by the human eye. 201,
When binocular vision is performed at 202, the adjustment mechanism of the eyes 201, 202 focuses on the actual distance L1 from the eyes 201, 202 to the screen 210, but the convergence mechanism of the eyes 201, 202 is Towards the image P2, the other eye 20
Since the eyes 201 and 202 are controlled so that the image No. 2 faces the image P1, the gazing point is the intersection position CLS of these, and in the example of FIG. 11, it is in front of the actual screen. Therefore,
Focusing distance L1 and gazing point CLS distance L2
Therefore, it is considered that eye fatigue is caused by this, and if the screen is continuously viewed for a long time, the larger the difference between L1 and L2, the greater the accumulation of eye fatigue.

It is an object of the present invention to provide a display device capable of easily displaying a stereoscopic image rich in realism with less eyestrain and a three-dimensional display device using the display device.

[0008]

In order to achieve the above object, the display device according to claim 1 has a minute lens in front of each dot formed of at least one pixel forming a two-dimensional display. And a means for changing the optical path length between the minute lens and the dot, or a means for changing the focal length of the minute lens, and means for changing the dot and the optical path length. Between the dot and the minute lens, a layer having a higher diffusivity of the display light of the dot than that of other portions in the vicinity, a layer having a low transmittance, or a layer for changing the polarization. It is characterized by being provided.

According to a second aspect of the present invention, at least one lens that acts on the entire surface of the display is provided in front of the dots forming the two-dimensional display, and the lens and the dots are combined. A means for changing the optical path length, or a means for changing the focal length of the lens, and between the dot and the means for changing the optical path length, or between the dot and the lens It is characterized in that a layer having a higher diffusivity of the display light of the dots than that of the above portion, a layer having a lower transmittance, or a layer for changing the polarization is provided.

[0010]

According to another aspect of the present invention, in the display device, the diffusivity of the display light of a dot is larger than that of another portion in the vicinity between the dot and the means for changing the optical path length or between the dot and the minute lens. A layer having a high transmittance, a layer having a low transmittance, or a layer for changing the polarization is provided, and the eye of the observer is focused on this layer, so that the optical path length can be shortened, and thus, the lens can be shortened. The focal length of can be reduced.

In the display device according to the second aspect, the diffusion rate of the display light of the dot is higher than that of the other portion in the vicinity between the dot and the means for changing the optical path length or between the dot and the lens. A layer, or a layer with low transmittance, or a layer for changing the polarization is provided, and the eye of the observer is focused on this layer, so that the optical path length can be shortened, and thus the focus of the lens can be reduced. The distance can be reduced.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are a front view and a sectional view of a first embodiment of a display device according to the present invention. In the display device of FIGS. 1 and 2, the two-dimensional display DP is a simple matrix liquid crystal display, and the two-dimensional display DP includes a liquid crystal layer (STN liquid crystal) 9 in which dots 2a, 2b, 2c are formed. , Alignment films 7a, 7b
An X-direction electrode 10 and a Y-direction electrode 11 for applying a voltage to the liquid crystal layer 9 and the alignment films 7a and 7b, glass substrates 6a and 6b, and polarizing plates 5a and 5b are provided.
In this two-dimensional display DP, dots, for example 2b, are generated in a portion where the polarization direction is changed by applying a voltage between the X-direction electrode 10 and the Y-direction electrode 11, and dots 2b are generated in the portion where the polarization direction is changed. Is displayed by passing the backlight light BK. In addition, in the display device of FIGS. 1 and 2,
As can be seen from FIG. 1, each dot 2a, 2b, 2c consists of one pixel, and in FIG.
Only one dot 2b is shown.

In this embodiment, as will be described later,
With the intention of changing the image position of the dots on the two-dimensional display DP seen from the eyes of the observer and further for stereoscopic display, 1
In front of the dots 2a, 2b, 2c made up of pixels, the minute lenses 1a, 2d corresponding to the dots 2a, 2b, 2c,
1b and 1c are provided, and dots 2a, 2b and 2c and minute lenses 1a, 1b and 1c are provided between the two-dimensional display DP and the minute lenses 1a, 1b and 1c.
An optical path length changing unit 3 is provided for changing the optical path length between and.

The optical path length changing portion 3 includes a liquid crystal layer (nematic liquid crystal) 18, alignment films 14a and 14b, and an X-direction electrode 1.
3, Y-direction electrode 15, glass substrate 16, spacer 1
7 and. In the case of the above-described configuration, it is considered that the surface on which the observer's eyes focus when observing the two-dimensional display is in the vicinity of the alignment film 7b, and for this reason, the minute surface provided in front of the dot 2b. It is considered that the optical path length between the lens 1b and the dot 2b is substantially the optical path length between the minute lens 1b and the vicinity of the alignment film 7b.

By the way, two glass plates 6b and 16 are included in the optical path between the minute lens 1b and the vicinity of the alignment film 7b. The glass plate 6b cooperates with the glass plate 6a to reduce the thickness of the liquid crystal layer 9 of the liquid crystal display DP to at least 0.
In order to maintain the accuracy of 2 μm or less, it is necessary to use a thick material of about 1 mm, and also for the glass plate 16, in cooperation with the spacer 17, the thickness of the liquid crystal layer 18 of the optical path length changing portion 3 In order to maintain the accuracy of 1 μm or less (to prevent the variation of the optical path length), it is necessary to use a thick one of about 1 mm.

However, the refractive index of glass is about 1.
Since it is as large as 5, the optical path length in the above two glasses 6b and 16 becomes as long as approximately 3 mm, and the focal length of the microlens 1b and the optical path length between the microlens and the vicinity of the alignment film are made substantially equal. Then, when trying to make the image of the dots appear far to the observer, at least 3 mm is present in the minute lens 1b.
Focal length is required. Further, as the thickness of the liquid crystal layer 18 of the optical path length changing portion 3 is thicker, the optical path length, that is, the rate of change of the refractive index can be increased, which is advantageous.
If the change in the refractive index is about 10% and the optical path length is to be changed by 0.1 mm, the liquid crystal layer 18 needs to have a thickness of 1 mm. As a result, if the refractive index of the liquid crystal layer 18 is set to 1.5 for convenience, the optical path length between the minute lens and the vicinity of the alignment film needs to be at least 4.5 mm, and the focal length of the minute lens 1b is limited. There is a problem in that it cannot be made smaller.

In other words, the smaller the focal length of the microlens 1b, the smaller the change amount of the optical path length when changing the position of the image, and the thickness of the liquid crystal layer 18 of the optical path length changing portion 3 can be reduced. Although it has an advantage that the thickness can be reduced and the voltage applied between the electrodes 13 and 15 can be reduced, and the thickness control of the liquid crystal layer 18 and the like can be extremely facilitated. As it is, since there is a limit in reducing the focal length, the above advantage cannot be given to the display device.

Therefore, in the first embodiment, further,
Between the two-dimensional display DP and the optical path length changing portion 3, a diffusion layer 4 having a higher light diffusion rate than other portions in the vicinity is provided. By providing this diffusion layer 4, the dots 2 b
The light from is diffused by the diffusion layer 4 and the portion 2 of the diffusion layer 4
7 becomes a new dot for adjusting the focus of the eye, and when the observer observes the dot 2b of the two-dimensional display, the focus of the observer's eye is the alignment film 7 of the two-dimensional display DP.
It is aligned not near b but near diffusion layer 4. Therefore,
In this case, the substantial optical path length is the optical path length between the microlens and the diffusion layer, and the optical path length can be made shorter than in the case where the diffusion layer 4 is not provided, and the microlens is relatively small. It becomes possible to make 1b a short focal length. That is, at this time, the observer is
A virtual image or a real image of the dot can be seen at a position determined by the optical path length between the diffusion layers and the focal length of the minute lens 1b.

The higher the diffusivity of the diffusion layer 4, the less likely it is to be affected by the distance to the dots behind. However, since the image is not formed on the surface of the diffusion layer 4, the diffusivity is high. If it is too much, the outline of the dot image will be blurred and the light transmittance will decrease, so the display quality of the image will deteriorate, and it will be difficult to adjust the eyes due to the decrease in contrast. There is no need to raise it.

FIG. 3 is a diagram showing a modification of the display device of FIGS. 1 and 2. In the display device of FIG. 2, instead of the high diffusion layer 4 of FIG. A layer 20 having a lower transmittance than that of the portion is provided. Specifically, the layer 20 has a color filter in a portion corresponding to a dot, and the light transmittance is suppressed by the color filter. Again, similar to the display device of FIGS. 1 and 2, it is easier for the observer to focus their eyes on the plane of the layer 20, rather than on the actual dots behind them, which results in the display of the dots. The surface can be moved forward of the alignment film 7b, the optical path length to the minute lens can be reduced, and the minute lens can have a small focal length.

Also, instead of the diffusion layer 4 and the layer 20 having a low transmittance, although not shown, a layer having a thin liquid crystal layer for changing the polarization can be provided to obtain the same effect as described above.

Thus, in the first embodiment, 2
By providing a diffusion layer 4, a layer having a low transmittance, or a layer for changing the polarization between the three-dimensional display DP and the optical path length changing portion 3, the effective optical path length is reduced and the microlens has a small focal length. It is possible to display a virtual image or real image of dots at a predetermined position.

FIG. 4 is a diagram showing an arrangement in which the erect virtual image 24 is displayed rearward by setting the effective optical path length to the focal length of the microlenses or less, and FIG. 5 shows the effective optical path length equal to or more than the focal length of the microlens. FIG. 7 is a diagram showing an arrangement in which the inverted real image 26 is displayed in the foreground. In both cases of displaying the erecting virtual image 24 as shown in FIG. 4 and displaying the inverted real image 26 as shown in FIG. 5, it is necessary to reduce the optical path length by using a small lens with a small focal length. It is extremely effective in

FIG. 6 is a block diagram of a second embodiment of the display device according to the present invention. In addition, in FIG.
The same parts as those in are denoted by the same reference numerals. In the display device of the second embodiment, instead of providing the optical path length changing portion 3, the minute lenses 22a, 22b, 22c themselves are
A variable focus lens utilizing the electro-optic effect is used.
That is, the minute lenses 22a, 22b, 22c are the same as those shown in FIG.
In the example, a liquid crystal lens 37 in which a kind of nematic liquid crystal is enclosed, transparent electrodes 38 and 39, and a flat glass 4
0, 41. By changing the voltage applied to the transparent electrodes 38, 39, the refractive index of the liquid crystal lens 37 is changed, whereby the minute lenses 22a, 2
The focal lengths of 2b and 22c are variable. In this case, the position of the virtual image or the real image is changed by changing the focal length instead of the optical path length, but at this time, the optical path length is shortened as in the first embodiment. Is advantageous.

Therefore, in the display device of FIG. 6 as well as in the display device of FIG. 2, light is emitted between the two-dimensional display DP and the minute lenses 22a, 22b, 22c and further in the vicinity thereof. A diffusion layer 4 having a high diffusion rate is provided. Since the diffusion layer 4 is provided, it is easy to adjust the focus of the eyes on the surface of the diffusion layer 4, whereby the optical path length to the minute lens can be shortened and the focal length of the minute lens can be reduced. It becomes possible to make it small. Also in this case, the diffusion layer 4
Instead of this, a layer having a low transmittance or a layer for changing the polarization may be provided.

In the above first and second embodiments,
Although a minute lens is provided for each dot of one pixel of the two-dimensional display, these minute lenses do not necessarily have to correspond to each dot of one pixel. For example, as shown in FIG. 7, R (red), G
The RGB 3 pixels of (green) and B (blue) may be newly defined as the dot 2e, and the minute lens 1e may be provided for each dot 2e composed of the RGB 3 pixels. At this time,
Hue information can be accurately displayed only when there are three RGB pixels. Therefore, in the case of color display, there is no significant change in performance as compared with the case where a minute lens is provided for each of the RGB pixels. It is easy to make minute lenses as much as the diameter can be increased.

Alternatively, as shown in FIG. 8, four groups of dots 2f, 2g, 2h, 2i each consisting of three RGB pixels may be newly set as one dot, and a minute lens 1f may be provided for each dot. In this case, although the display accuracy of the information of the thin line or the contour is somewhat lowered, the diameter of the lens can be further increased, and thus it becomes easy to form a minute lens. Further, instead of using four groups as one dot, 3 × 3 = 9 groups can be used as one dot.

FIG. 9 is a block diagram of the third embodiment of the display device according to the present invention. In this display device, a lens 30 that acts on the entire surface of the display DP is provided in front of the two-dimensional display DP, instead of the above-described minute lens corresponding to each dot.
Between the two-dimensional display DP and the lens 30, the optical path length changing unit 3 having the same configuration as described above for changing the optical path length between them is provided. Note that the example of FIG. 9 shows a case where the optical path length between the lens 30 and the dots 2a to 2i is set to be equal to or less than the focal length of the lens 30,
In this case, the virtual images 28a to 28i of the dots 2a to 2i can be displayed backward, and by changing the optical path length by the optical path length changing unit 3, the virtual image positions of all the dots on the screen can be changed. In addition, when the optical path length changing unit 3 is deformed to change the optical path length for each dot, the position of the virtual image can be changed for each dot.

Even in the case of such a structure, it is advantageous to shorten the optical path length. Therefore, also in the display device of FIG. 9, as in the display devices of FIG. 2 and FIG. 6, between the two-dimensional display DP and the lens 30, the diffusion rate of light is higher than that of other portions in the vicinity. Layer 4 is provided. Since the diffusion layer 4 is provided, it is easy to adjust the focus of the eyes on the surface of the diffusion layer 4, whereby the optical path length to the minute lens can be shortened and the focal length of the minute lens can be reduced. It becomes possible to make it small. Also in this case, instead of the diffusion layer 4, a layer having a low transmittance or a layer for changing the polarization can be provided.

Further, in the configuration of FIG. 9, a real image can be displayed by making the optical path length larger than the focal length, but in this case also, it is advantageous to shorten the optical path length. Similarly, the optical path length can be shortened by providing the diffusion layer 4.

Further, instead of providing the optical path length changing portion 3 in the display device of FIG. 9, a variable focus lens utilizing the electro-optical effect can be used as the lens 30 itself.

In each of the embodiments described above, FIG.
The display device of FIGS. 3, 6 and 9 does not change the optical path length or the focal length of each dot, and the area is wider than the dot, for example, one column in FIG.
When it is configured to change the optical path length or the focal length over the entire area of the dots for a row, it is suitable for the purpose of giving a gentle stereoscopic effect in a wide area. Specifically, in the case where only three types of changes of the distant view, the middle view, and the near view need to be given, by using these configurations, the optical path length,
Alternatively, the focal length can be set to be the same for the distant view, and the optical path length or the focal length can be set to be the same for the near view for all the dots in the near view region.

On the other hand, when these display devices have a structure in which the optical path length or the focal length can be changed for each dot (however, FIG. 9 is not possible), the optical path length, Alternatively, it is suitable for applications in which the focal length is changed, and in this case, a stereoscopic effect can be obtained for each dot.

However, in any of the above cases, the focal length of the minute lens corresponding to each dot or the lens acting on the entire surface of the two-dimensional display DP, or
Since the refractive index of the layer between these lenses and the dots can be easily set to a predetermined value, by determining the focal length or the refractive index according to the image information to be displayed,
Even when the two-dimensional display DP is used, three-dimensional display is possible, and by applying any of the above display devices to the three-dimensional display device, an image can be displayed at the distance of the gazing point even in the case of stereoscopic vision due to binocular parallax. By forming an image, eye fatigue can be reduced.

FIGS. 10A and 10B are views for explaining this situation. For example, on the two-dimensional screen 210, 2
The two images P1 and P2 are displayed at a predetermined distance Z, and when these two images P1 and P2 are observed, FIG.
In FIG. 10A, one eye 201 shows the image P2, and in FIG. 10B, the other eye 202 shows the image P1. The congestion mechanism of the eyes 201 and 202 is shown in FIG.
Since the eyes 201 and 202 are controlled so that the other eye 202 faces toward the image P1, the gazing point is the intersection position CLS of these, and in the example of FIGS. , Which is in front of the actual screen 210. In such a case, the display device according to the present invention is mounted for the left eye and the right eye, respectively, and the display device is controlled according to the image information of the screen 210 to display the screen 2
Since the positions of the ten images P1 and P2 (in this case, the real image positions) can be moved to the position of the gazing point CLS,
As a result, the adjustment mechanism of the eyes 201 and 202 is
The eyes 201, 202 are controlled so as to focus on the distance L2 from the point 1, 202 to the gazing point CLS. As a result, eye congestion and accommodation can be matched, and eye fatigue can be reduced.

Contrary to the above example, the gazing point CLS is the actual distance L1 from the eyes 201, 202 to the screen 210.
When an image at a distance farther than that is displayed on the screen 210, the display device is configured to display a virtual image of the image on the screen 210, and the display device is controlled to display the virtual image at the gazing point. By doing so, it is possible to make eye congestion and adjustment coincide with each other in the same manner, and reduce fatigue.

[0037]

As described above, in the display device according to the first aspect, a minute lens is provided in front of each dot formed of at least one pixel forming a two-dimensional display. A means for changing the optical path length between the minute lens and the dot, or a means for changing the focal length of the minute lens, between the dot and the means for changing the optical path length, or Between the dot and the minute lens, a layer having a higher diffusion rate of the display light of the dot than the other portions in the vicinity, a layer having a low transmittance, or a layer for changing the polarization is provided, When the optical path length can be shortened, the focal length of a minute lens can be shortened, and further, when a three-dimensional display is constructed using this display device. By varying the optical path length or focal length appropriately appropriately changing the image position, it is possible to easily display a stereoscopic image rich in fatigue less realistic eye.

Further, in the display device according to the second aspect, at least one lens that acts on the entire surface of the display is provided in front of the dots forming the two-dimensional display, and the lens and the dots are combined. A means for changing the optical path length, or a means for changing the focal length of the lens, and between the dot and the means for changing the optical path length, or between the dot and the lens Since a layer having a higher diffusivity of the display light of the dots than that of, or a layer having a low transmittance or a layer for changing the polarization is provided, the optical path length can be shortened and the focal length of the lens can be reduced. Furthermore, when a three-dimensional display is constructed using this display device, the optical path length or the focal length is appropriately changed to appropriately adjust the image position. By reduction, it is possible to easily display a stereoscopic image rich in fatigue less realistic eye.

[Brief description of drawings]

FIG. 1 is a front view of a first embodiment of a display device according to the present invention.

FIG. 2 is a cross-sectional view of a first embodiment of a display device according to the present invention.

FIG. 3 is a diagram showing a modification of the display device shown in FIGS. 1 and 2.

FIG. 4 is a diagram showing an arrangement in which an effective optical path length is set to be equal to or less than a focal length of a minute lens and an erecting virtual image is displayed backward.

FIG. 5 is a diagram showing an arrangement in which an effective optical path length is set to a focal length of a microlens or more and an inverted real image is displayed in front.

FIG. 6 is a configuration diagram of a second embodiment of a display device according to the present invention.

FIG. 7 is a diagram showing a configuration in which minute lenses are arranged corresponding to a plurality of pixels.

FIG. 8 is a diagram showing a configuration in which minute lenses are arranged corresponding to a plurality of pixels.

FIG. 9 is a configuration diagram of a third embodiment of a display device according to the present invention.

10 (a) and 10 (b) are diagrams for explaining the principle of matching eye congestion and accommodation according to the present invention.

FIG. 11 is a diagram for explaining a general relationship between eye congestion and accommodation.

[Explanation of symbols]

 1a, 1b, 1c Microlens 2a, 2b, 2c Dot 3 Optical path length changing part 4 Diffusion layer 5a, 5b Polarizing plate 6a, 6b Glass substrate 7a, 7b Alignment film 9 Liquid crystal layer 10 X-direction electrode 11 Y-direction electrode 13 X Directional electrodes 14a, 14b Alignment film 15 Y-direction electrode 16 Glass substrate 17 Spacer 18 Liquid crystal layer 20 Low transmittance layer 22a, 22b, 22c Micro lens 30 Lens 37 Liquid crystal lens 38, 39 Transparent electrode 40, 41 Flat Glass

Claims (2)

[Claims] 1. A minute lens is provided in front of the dot for each dot composed of at least one pixel forming a two-dimensional display, and the optical path length between the minute lens and the dot is changed. Means or means for changing the focal length of the minute lens, and between the dot and the means for changing the optical path length, or between the dot and the minute lens, another nearby A layer with a higher diffusion rate of the dot display light than the part,
Alternatively, a display device provided with a layer having a low transmittance or a layer for changing polarization. 2. At least one lens acting on the entire surface of the display is provided in front of the dots forming the two-dimensional display, and further, means for changing the optical path length between the lens and the dot, or a lens. A means for changing the focal length of the dot, and between the dot and the means for changing the optical path length, or between the dot and the lens, the diffusion of the display light of the dot more than the other portion in the vicinity. A display device provided with a layer having a high reflectance, a layer having a low transmittance, or a layer for changing polarization.