JP2010032615A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device, capable of providing a composited display image formed by connecting partial display images, formed of a plurality of display elements as a virtual image without causing gaps, or the like, even when an observer's eye is shifted from a predetermined position. <P>SOLUTION: The display device 10 includes a plurality of projecting units 11, each including a display element 111 which displays a partial display image and a projecting optical system 112 which emits image display light L based on the partial display image; and a virtual image optical system 2, which guides the image display lights L emitted from the plurality of projection units 11 to the observer's eye E as a virtual image of a connected composed display image. The display device, further, includes a screen 12 disposed between the plurality of projection units 11 and the virtual optical system 2, and the image display lights L, emitted from the plurality of projection units 11, are imaged as one real image on the screen 12, before they reach the virtual optical system 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a display device that guides a display image displayed on a display element to a viewer's eye as a virtual image, and particularly relates to a display device (for example, a head-mounted display, a head-up display, or the like) that is worn on the viewer's head. .

Conventionally, a head-mounted display (display device) that displays a display image displayed on a display element such as a CRT or LCD as a virtual image in front of an observer via a virtual image optical system such as a combiner is known. Such a head-mounted display includes, for example, a projection unit having one LCD, a combiner disposed in front of the viewer's eyes, and a control unit that outputs an image signal to the LCD. In the head mounted display, the image display light based on the display image displayed on the LCD is emitted from the projection unit and then reflected by the combiner so as to be guided to the eyes of the observer. As a result, the observer can observe the display image as a virtual image and can also visually recognize the real object in front by the light transmitted through the combiner. At this time, the number of pixels of the virtual image observed by the observer is the same as the number of pixels of the LCD.

By the way, in order to provide an observer with a virtual image having a high pixel density with such a head-mounted display, an LCD having a high pixel density may be used. There is a limit as costs increase.
Thus, there is a head-mounted display that can provide a viewer with a virtual image with a high pixel density by using a plurality of LCDs side by side even when the pixel density of the LCD is low (see, for example, Patent Document 1).
FIG. 5 is a configuration diagram showing an example of a schematic configuration of a head mounted display using three LCDs. The head mounted display 50 includes a projection unit group 51 having three LCDs 51a, 51b, 51c, a hologram optical element (virtual image optical system) 52 arranged in front of the observer's eye E, and three LCDs 51a, 51b, 51c includes a control unit (not shown) that outputs an image signal.
The projection unit group 51 includes a first LCD 51a, a second LCD 51b, and a third LCD 51c. The first LCD 51a, the second LCD 51b, and the third LCD 51c are arranged in parallel in this order in the horizontal row. Then, the image display light based on the partial display image (number of pixels M × N) displayed on the first LCD 51a is emitted from the first LCD 51a and then reflected by the right part of the hologram optical element 52, thereby observing. It is guided to the person's eye E. Further, the image display light based on the partial display image (number of pixels M × N) displayed on the second LCD 51b is emitted from the second LCD 51b and then reflected by the central portion of the hologram optical element 52, thereby observing. It is guided to the person's eye E. Furthermore, the image display light based on the partial display image (number of pixels M × N) displayed on the third LCD 51c is emitted from the third LCD 51c and then reflected on the left part of the hologram optical element 52, thereby observing. It is guided to the person's eye E.

Thereby, the observer wearing the head mounted display 50 displays a composite display image obtained by connecting the partial display image of the first LCD 51a, the partial display image of the second LCD 51b, and the partial display image of the third LCD 51c in a horizontal row. It can be observed as a virtual image. FIG. 6 is a diagram illustrating an example of a virtual image observed by an observer in the conventional head mounted display 50. The virtual image observed by the observer is a combined display image obtained by connecting three partial display images. As a result, the number of pixels of the virtual image is 3M × N.
JP-A-6-512239

However, in the head mounted display 50 using the three LCDs 51a, 51b, and 51c, when the observer's pupil is at a predetermined position (designed pupil position), the observer displays a virtual composite image displayed in a horizontal row. However, if the observer's pupil deviates from a predetermined position, there is a gap between the partial display image of the first LCD 51a, the partial display image of the second LCD 51b, and the partial display image of the third LCD 51c. In addition, there is a drawback that a discontinuous composite display image in which an unnatural joint or the like is formed is observed as a virtual image.
Therefore, the present invention provides a composite display image in which partial display images formed by a plurality of display elements such as LCDs are connected as a virtual image, and even if the observer's pupil deviates from a predetermined position, a gap or unnaturalness is present. It is an object of the present invention to provide a display device that can provide a composite display image in which a joint or the like does not occur as a virtual image.

The display device of the present invention made to solve the above problems includes a plurality of projection units each having a display element that displays a partial display image and a projection optical system that emits image display light based on the partial display image forward. And a display device including a virtual image optical system that couples image display light emitted from the plurality of projection units and guides a combined display image to an observer's eye as a single virtual image, the plurality of projection units The image display light emitted from the plurality of projection units is formed as a single real image on the screen before reaching the virtual image optical system. Like that.

According to the display device of the present invention, a plurality of projection units, a screen, and a virtual image optical system are provided in this order.
First, image display light based on a partial display image displayed on one display element is emitted forward from the projection optical system, and is guided to a part of the screen. Further, the image display light based on the partial display image displayed on the other display element is emitted forward from the projection optical system and is guided to the other part of the screen. At this time, the image display light emitted from the plurality of projection units is 1 on the screen so as to be a combined display image obtained by connecting a partial display image of one display element and a partial display image of another display element. It is formed as a real image. That is, a composite display image in which no gaps or unnatural joints are generated is once formed on the screen.
Then, image display light based on the composite display image formed on the screen is reflected or refracted by the virtual image optical system, and is guided to the eyes of the observer. Thus, the observer observes a combined display image obtained by connecting the partial display image of one display element and the partial display image of the other display element as a virtual image. At this time, the virtual image observed by the observer becomes a composite display image obtained by connecting a plurality of partial display images, and as a result, the pixel density of the virtual image is high. In addition, since a composite display image in which no gaps or unnatural joints are generated is once formed on the screen, the observer can observe the composite display image in which no gaps or unnatural joints are generated as a virtual image. .

As described above, according to the display device of the present invention, even if a display element having a low pixel density is used, a composite display image having a high pixel density can be converted into a virtual image by connecting partial display images formed by a plurality of display elements. Can be offered as.
Furthermore, even if the observer's pupil deviates from a predetermined position, a composite display image that does not cause gaps or unnatural joints can be provided as a virtual image.

(Means and effects for solving other problems)
In the display device of the present invention, the plurality of projection units may be arranged so that the optical axes of the projection optical systems of the plurality of projection units are parallel to each other toward the screen.
Further, in the display device of the present invention, the plurality of projection units, the virtual image optical system, and the screen may be mounted on the head of the observer.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments described below, and it goes without saying that various aspects are included without departing from the spirit of the present invention.

FIG. 1 is a configuration diagram showing an example of a schematic configuration of a head mounted display (display device) according to an embodiment of the present invention. FIG. 2 is a perspective view showing the positional relationship between the LCD (display element) and the screen of the head mounted display shown in FIG. Further, FIG. 3 is a diagram showing an example of a virtual image observed by an observer in the head mounted display shown in FIG.
The head mounted display 10 includes a projection unit group 11 having four LCDs 111a, 111b, 111c, and 111d, a single flat screen 12, and a combiner (virtual image optical system) 2 disposed in front of the eyes E of the observer. And a control unit 30 that outputs image signals to the four LCDs 111a, 111b, 111c, and 111d. The head mounted display 10 is attached to the observer's head.

The screen 12 is a single flat plate disposed between the projection unit group 11 and the combiner 2. In the screen 12, the surface on the projection unit group 11 side becomes an incident surface that receives the image display light L based on the partial display image from the projection unit group 11, and the surface on the combiner 2 side receives the image display light L based on the partial display image. It becomes an output surface which outputs to the combiner 2.

The projection unit group 11 includes a first projection unit 11a, a second projection unit 11b, a third projection unit 11c, and a fourth projection unit 11d.
The first projection unit 11a includes one LCD 111a that displays a partial display image, and a projection optical system 112a that is disposed in front of the LCD 111a.
The LCD 111 a displays a partial display image (number of pixels M × N) based on the image signal from the control unit 30. Then, the LCD 111a emits image display light L based on the partial display image to the front projection optical system 112a. The projection optical system 112a receives the image display light L based on the partial display image at the incident surface, and then emits the image display light L from the emission surface to the front screen 12 so as to form a real image.
Since the second projection unit 11b, the third projection unit 11c, and the fourth projection unit 11d have the same structure as the first projection unit 11a, description thereof is omitted here.

A total of four projection units such as the first projection unit 11a, the second projection unit 11b, the third projection unit 11c, and the fourth projection unit 11d are arranged and fixed in two rows and two rows. Has been. 2, when viewed from the front, the LCD 111a of the first projection unit 11a in the upper left, the LCD 111b of the second projection unit 11b in the upper right, the LCD 111c of the third projection unit 11c in the lower left, and the fourth in the lower right. The LCD 111d of the projection unit 11d is arranged respectively. In FIG. 2, the projection optical system is not shown.
The optical axis of the projection optical system 112a of the first projection unit 11a, the optical axis of the projection optical system 112b of the second projection unit 11b, the optical axis of the projection optical system 112c of the third projection unit 11c, and the optical axis of the fourth projection unit 11d. The first projection unit 11a, the second projection unit 11b, the third projection unit 11c, and the fourth projection unit 11d are arranged so that the optical axes of the projection optical system 112d are parallel to each other toward the screen 12. Yes. Thus, as shown in FIG. 2, when viewed from the front, the partial display image of the LCD 111a is projected on the upper left part of the screen 12, the partial display image of the LCD 111b is projected on the upper right part of the screen 12, and the partial display image of the LCD 111c is The image is projected on the lower left portion of the screen 12, and the partial display image on the LCD 111 d is projected on the lower right portion of the screen 12. At this time, a single real image is formed on the screen 12 so as to be a combined display image obtained by connecting the partial display image of the LCD 111a, the partial display image of the LCD 111b, the partial display image of the LCD 111c, and the partial display image of the LCD 111d. . That is, a composite display image in which no gaps or unnatural joints are generated is once formed on the screen 12.

The control unit 30 includes a CPU 31. The control / calculation contents executed by the CPU 31 will be described separately for each function. An image signal output for outputting an image signal to the composite display image creation unit 32 for creating a composite display image and the four LCDs 111a, 11b, 111c, and 111d. Part 33.
The composite display image creation unit 32 performs control to create a composite display image. Specifically, one composite display image is created so that an image as shown in FIG. 3 is observed as a virtual image by an observer.

The image signal output unit 33 performs control to output image signals to the four LCDs 111a, 111b, 111c, and 111d. Specifically, first, one composite display image created by the composite display image creation unit 32 is separated into four partial display images so as to be arranged in two vertical rows and two horizontal rows. Next, as shown in FIG. 4, mirror images 40a, 40b, 40c, and 40d of four partial display images are created. Then, an image signal indicating the partial display image 40a is output to the LCD 111a, an image signal indicating the partial display image 40b is output to the LCD 111b, an image signal indicating the partial display image 40c is output to the LCD 111c, and a partial display image 40d is output to the LCD 111d. An image signal indicating is output.

The combiner 2 reflects the image display light L based on the composite display image formed on the screen 12, thereby guiding the composite display image to the observer's eye E as one virtual image.
The combiner 2 includes a first optical element 21 disposed in front of the observer's eye E, and a second optical element 22 disposed in front of the first optical element 11 from the observer's eye E via a space. Have. The first optical element 21 and the second optical element 22 are each composed of, for example, a half mirror or a hologram element. Therefore, the first optical element 21 and the second optical element 22 have a beam splitting function that reflects and transmits incident light.

Here, the surface opposite to the viewer side of the first optical element 21 is defined as a first optical path changing surface 21a, and the surface on the viewer side of the first optical element 21 is defined as a first passing surface 21b. The surface on the viewer side of the second optical element 22 is a second optical path changing surface 22a, and the surface on the viewer side opposite to the second optical element 22 is a second passage surface 22b.
The first optical path changing surface 21a has a convex curved surface shape that diverges incident light (image display light L), and the second optical path changing surface 22a has a concave curved surface shape that converges incident light. The first optical path changing surface 21a, the second optical path changing surface 22a, the first passing surface 21b, and the second passing surface 22b are, for example, “off-axis rotationally symmetric aspheric surfaces”.

The off-axis rotationally symmetric aspherical surface is represented by a surface having a center decentered from the rotationally symmetric axis of the aspherical surface in the aspherical surface specified by the shape function expressed by the following mathematical formula (1) in the xyz coordinate space. Here, in Formula (1), ρ ² = x ² + y ² and c = 1 / R. Equation (1) represents a spherical surface when the quadric surface coefficient K and the aspherical coefficient αi (i = 1 to n) are 0, and the radius of the spherical surface is R. Therefore, the aspherical surface means that at least one aspherical coefficient αi or the quadric surface coefficient K is not 0 in Equation (1).

It should be noted that the curvature c defining the off-axis rotationally symmetric aspheric surface, the quadratic surface coefficient K, and the aspheric surface coefficient αi (i = 1 to n) are the virtual image of the observation object with respect to the real image (partial display image) in the head mounted display 10. In accordance with the magnification, the optical path length from the head mounted display 10 to the eye E of the observer, etc., it is determined so that a virtual image can be clearly formed at a position far from the observer.
The first optical element 21 and the second optical element 22 are plate-like bodies having a uniform thickness. The thickness of the first optical element 21 is made uniform, for example, by making the first optical path changing surface 21a and the first passage surface 21b have the same shape. On the other hand, the thickness of the second optical element 22 is also made uniform, for example, by making the second optical path changing surface 22a and the second passage surface 22b have the same shape.

Here, a mechanism in which the combiner 2 guides the image display light L to the eyes E of the observer will be described. First, the image display light L emitted from the screen 12 and reaching the first optical path changing surface 21a is reflected by the first optical path changing surface 21a toward the second optical path changing surface 22a. Furthermore, the image display light L that has reached the second optical path changing surface 22a is reflected by the second optical path changing surface 22a so as to go toward the first optical path changing surface 21a. Then, the image display light L reaching the first optical element 21 is guided to the observer's eye E by passing through the first optical element 21. Therefore, the combiner 2 forms the virtual image of the observation target by guiding the image display light L to the observer's eye E.

As described above, according to the head-mounted display 10, even when using LCDs (number of pixels M × N) 111a, 111b, 111c, and 111d with low pixel density, the four LCDs 111a, 111b, 111c, and 111d are formed. By connecting the partial display images, a composite display image (number of pixels 2 × (M × N)) having a high pixel density can be provided as a virtual image. Furthermore, even if the observer's pupil is deviated from a predetermined position, a composite display image that does not cause a gap or an unnatural joint can be provided as a virtual image.

(Other embodiments)
(1) The head mounted display 10 described above includes four projection units 11a, 11b, 11c, and 11d. However, the present invention is not limited to the four projection units, and a virtual image having a desired pixel density is provided to the observer. In order to provide, it is good also as a structure provided with a required number of projection units, such as nine and sixteen.
(2) The head mounted display 10 described above is configured to include one screen 12, but may be configured to be separated into four screens so as to be arranged in two vertical rows and two horizontal rows. Good. According to such a configuration, the number of projection units can be easily changed.
(3) In the head mounted display 10 described above, the control unit 30 is configured to separate the combined display image into four partial display images so that there is no overlapping portion, but the control unit is configured so that the combined display image partially overlaps. It is good also as a structure which isolate | separates into four partial display images.
(4) The image display light may be guided to both eyes of the observer, and the second optical path changing surface may be constituted by a total reflection mirror.
(5) Not only a head mounted display but a form like a head up display installed in front of an observer may be sufficient.
(6) The above-described head mounted display 10 is configured to include the combiner 2 that reflects the image display light L to guide the synthesized display image as one virtual image to the observer's eye E. It is good also as a structure provided with the virtual image optical system which guide | induces a synthetic | combination display image to an observer's eyes by refracting | refracting.

  The present invention can be used for a display device that guides a display image displayed on a display element to a viewer's eye as a virtual image.

It is a block diagram which shows an example of schematic structure of the head mounted display which is one Embodiment of this invention. It is a perspective view which shows the positional relationship of LCD and the screen of the head mounted display shown in FIG. It is a figure which shows an example of the virtual image observed by the observer in the head mounted display shown in FIG. It is a figure which shows an example of the mirror image of four partial display images. 10 is a configuration diagram illustrating an example of a schematic configuration of a head mounted display described in Patent Literature 1. FIG. In the head mounted display of patent document 1, it is a figure which shows an example of the virtual image observed by the observer.

Explanation of symbols

2 Combiner (virtual image optical system)
10 Head mounted display (display device)
11a, 11b, 11c, 11d Projection unit 12 Screen 21 First optical element 22 Second optical elements 111a, 111b, 111c, 111d LCD (display element)
112a, 112b, 112c, 112d Projection optical system L Image display light E Eye of observer

Claims (3)

A plurality of projection units each including a display element that displays a partial display image and a projection optical system that emits image display light based on the partial display image forward, and
A display device comprising a virtual image optical system that couples image display light emitted from the plurality of projection units and guides a composite display image as a single virtual image to an observer's eye,
A screen disposed between the plurality of projection units and the virtual image optical system;
The image display light emitted from the plurality of projection units is formed as a single real image on the screen before reaching the virtual image optical system. The display device according to claim 1, wherein the plurality of projection units are arranged so that optical axes of projection optical systems of the plurality of projection units are parallel to each other toward the screen. The display device according to claim 1, wherein the plurality of projection units, the virtual image optical system, and the screen are attached to the head of the observer.

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