JP2000249968A - Image observation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize miniaturization and to observe picture information with excellent picture quality in wide observation field by sharing one part of optical elements by an illumination optical system and a display optical system and providing the optical element with a curved surface. SOLUTION: Illuminating light emitted from a light source 11 consisting of an LED, etc., passes through a polarizing plate 15 and becomes linearly polarized light, is refracted by a surface 16 and made incident on a prism body L1. The light is partially reflected by a half mirror surface 17 having positive power, emitted from the prism body L1 while it is refracted by a surface 18, and made incident on the display surface of a reflection type display element 30 at a specified angle. The illuminating light is obliquely made incident on the element 30 and reflected, and further the illumination optical system 10 and the display optical system 20 share the optical element having positive power and including the surfaces 17 and 18 equipped with a curved surface. By properly using reflecting action and transmitting action on the surface 17 constituting the optical element, the optical system where a space between the optical element and a display surface is set to be small and whose angle of view is wide and which is miniaturized is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image observation apparatus using a reflection type display element, and more particularly to an optical system having an eccentric non-rotationally symmetric reflection surface in which image information displayed on a reflection type liquid crystal display element is appropriately set. This is suitable for a head-mounted display, a glasses-type display, and the like, which are magnified and observed through an element (prism).

[0002]

2. Description of the Related Art A head-mounted image observation apparatus which conventionally uses a display element such as a CRT or LCD and magnifies and displays an image displayed on these display elements via an image observation optical system. (Head-mounted display) is well known.

For example, JP-A-7-333551, JP-A-8-5
In Japanese Patent Application Laid-Open Nos. 0256, 8-160340, 8-179238, etc., an apparatus using an LCD (liquid crystal) as a display means for displaying image information and a small prism as an observation optical system is used. 2. Description of the Related Art There has been proposed an image observing apparatus which is reduced in size as a whole.

FIG. 6 is a schematic view of a main part of an image observation apparatus proposed in Japanese Patent Application Laid-Open No. 7-333551. In FIG.
The light emitted from the LCD 51 is incident on the incident surface 53 of the small prism 52. And the small prism 52
Total reflection surface 54 having a curvature formed in
5, the light beam is folded, and then the small prism 52 is emitted from the surface 54 to guide the light to the observer E. Thereby, a virtual image of the image information displayed on the display means (LCD) 51 is formed, and the observer E observes the virtual image. The reflection surface 55 of the small prism 52 is formed of an eccentric free-form surface constituted by an eccentric non-rotationally symmetric surface (a surface having a different optical power depending on the azimuth angle, a so-called free-form surface).

FIG. 7 is a schematic view of a main part of an image observation apparatus using a conventional coaxial concave mirror. In the figure, the light flux from the image information displayed on the display element 61 is reflected by the half mirror 62 and is incident on the concave mirror 63. The light beam reflected by the concave mirror 63 is guided to the observer E via the half mirror 62. The image information displayed on the display element 61 is formed as a virtual image enlarged by the concave mirror 63. Thereby, the observer observes the enlarged virtual image of the image information displayed on the display element 61.

The type of optical system shown in FIG. 6 is characterized in that it is easier to reduce the size of the entire apparatus and to increase the angle of view of the observation field as compared with the conventional type using a coaxial concave mirror shown in FIG. are doing.

[0007]

2. Description of the Related Art Conventionally, image observation apparatuses such as a head-mounted display and an eyeglass-type display have been required to be downsized and lightened, in particular, because these apparatuses are mounted on the head. . In addition, it is important to widen the observation angle of view in order to enhance the observation of the image information displayed on the display means.

In an image observation apparatus such as a head-mounted display (HMD) or a glasses-type display as shown in FIG. 6, a reflective display element (for example, a reflective display element) having a high aperture efficiency and advantageous for miniaturization is used as a display element. When an attempt is made to use a ferroelectric liquid crystal element), it is necessary to insert an illumination system 70 for illuminating the display element 51 between the display element 51 and the entrance surface 53 of the small prism 52 as shown in FIG. There is.

Here, the illumination system 70 includes, for example, a light source 71, a condenser lens 72 for condensing the light beam from the light source 71 and converting it into parallel light, and a half mirror surface 73 a for reflecting the light beam from the condenser lens 72 and illuminating the display element 51. And the like. In an image observation device,
When a reflective display element is used, an illumination system for illuminating the reflective display element must be disposed between the display element 51 and the small prism 52. As shown in FIG. It is necessary to increase the interval, and it is difficult to reduce the size, the weight, and the angle of view without utilizing the characteristics of this type.

Further, since the number of optical working surfaces constituting the optical system (prism 52) is only four including the overlap, the power and aberration correction of each surface is large, and the tolerance is strict, making manufacturing difficult. The problem of becoming a problem arises.

According to the present invention, when observing image information displayed on a reflective display means such as a liquid crystal display in a wide observation field, an illumination system for illuminating the display means and a light beam from the display means are guided to an observer's eyeball. By appropriately setting the configuration of an optical system for emitting light, for example, an optical unit including a prism having a refractive action, the image information can be obtained with a good image quality in a wide observation field while reducing the size of the entire apparatus. It is an object of the present invention to provide an image observation device that can be observed.

[0012]

According to the first aspect of the present invention, there is provided an image observation apparatus, comprising: a reflection type display unit; an illumination optical system for causing a light beam from a light source unit to enter the display unit; and a light beam from the display unit. In the image observation device having a display optical system for guiding the light to the observation position of the observer, the illumination optical system and the display optical system share some optical elements, and the optical elements have a curved surface. It is characterized by:

According to a second aspect of the present invention, there is provided an image observation apparatus, comprising: a reflection type display unit; an illumination optical system for causing a light beam from a light source unit to enter a display surface of the display unit in an oblique direction; A display optical system that guides the light beam to the observer and observes the image information displayed on the display means, wherein the principal ray emitted from the central part of the display means is oblique from the display means. The display optical system has an eccentric non-rotationally symmetric reflection surface, and the illumination optical system and the display optical system share some optical elements. Some optical elements are characterized in that at least one surface is constituted by a curved surface.

According to a third aspect of the present invention, there is provided an image observation apparatus, comprising: a reflection type display element; an illumination optical system for guiding a light beam from a light source means to the display element; and a light beam reflected by the display element to an observation eye. In the image observation device having a display optical system for observing an image, the display optical system is constituted by a non-rotationally symmetric reflection surface having at least one eccentric surface, and a principal ray of a display light flux at a central angle of view from the display means is: Emitted with a predetermined angle with respect to the display surface normal of the display element, and the illumination optical system and the display optical system share some optical elements,
The optical element is characterized in that at least one surface is constituted by a curved surface.

According to a fourth aspect of the present invention, in the first, second, or third aspect, the surface of the optical element is a non-rotationally symmetric surface.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the optical element acts as a transmission surface in an optical path of the display optical system, and functions as a transmission surface in an optical path of the illumination optical system. It is characterized by having a surface acting as a reflecting surface.

According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the surface of the optical element acts as a positive power in both the display optical system and the illumination optical system.

According to a seventh aspect of the present invention, in the fifth or sixth aspect, the surface of the optical element is a curved surface.

According to an eighth aspect of the present invention, in any one of the first to seventh aspects of the present invention, the display element of the reflection type is a ferroelectric liquid crystal panel.

According to a ninth aspect of the present invention, there is provided an image observation apparatus of the reflection type via a first prism body made of a single medium having three or more optical surfaces including a surface decentered with a light beam from a light source means. The display means is illuminated in an oblique direction, and a light beam emitted in an oblique direction from the display means has a single prism having three or more optical surfaces including a surface decentered through a part of the optical surface of the first prism body. The light is guided to the observer through the second prism body made of the above medium, and the image information displayed on the display means is observed.

According to a tenth aspect of the present invention, in the ninth aspect of the invention, the first prism body has an incident surface on which the light beam from the light source means is incident, and a non-rotationally symmetric surface which reflects a part of the light beam from the incident surface. And a light emitting surface for emitting a light beam reflected by the half mirror surface to the display means side.

According to an eleventh aspect of the present invention, in the tenth aspect, the light beam from the display means enters from an exit surface of the first prism body, passes through a half mirror surface, and exits from the first prism body. And is incident on the second prism body.

According to a twelfth aspect of the present invention, in the eleventh aspect of the present invention, the second prism body is an incident surface on which a light beam from the half mirror surface of the first prism body is made incident, and the light beam from the incident surface is totally reflected. It has a total reflection surface, a reflection surface composed of a non-rotationally symmetric surface for reflecting a light beam from the total reflection surface, and an emission surface having the same shape as the total reflection surface for emitting a light beam from the reflection surface. It is characterized by.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of a main part of a first embodiment of the present invention. The image observation optical system according to the present embodiment includes a light source 1
1, an illumination optical system 10 including a condenser lens 12, a diffusion plate 13, a condenser lens 14, a polarizing plate 15, and a prism L1, a reflective display element 30, such as a liquid crystal element, a prism L1, a polarizing plate 21, and It has a display optical system 20 composed of a prism body L2.

Next, each element will be described.

A light beam emitted from a light source 11 composed of an LED or the like is converged by a condenser lens 12 while being diffused.
3 and constitutes a secondary light source. The light beam (divergent light beam) that has passed through the diffusion plate 13 passes through the polarizing plate 15 while being converged by the condenser lens 14, and becomes linearly polarized light.
The light is refracted at 16 and enters the prism body L 1, and a part thereof is reflected by the half mirror surface 17 having a positive power, and is refracted by the surface (exit surface) 18 and emerges from the prism body L 1 while being reflected. At a predetermined angle to the display surface normal. The surface 17 is constituted by a rotationally asymmetric aspheric surface having different power depending on the azimuth angle around the surface vertex, thereby correcting various aberrations caused by decentering the optical system. The surfaces 16 and 18 are flat, curved,
It consists of an aspherical surface or a rotationally asymmetric surface. The prism body L1 has three or more optical surfaces including a decentered surface.

On the other hand, the light beam transmitted through the half mirror surface 17 by the light beam from the surface 16 is cut off by the polarizing plate 21 arranged so that its polarization axis is orthogonal to the polarizing plate 15, and is incident on the prism body L2. I try not to. By making the surface 17 have a positive power, the spread of the illumination light beam can be suppressed, so that the size of the illumination optical system 10 is reduced, for example, the outer diameter of the condenser lens 14 can be reduced.

In the present embodiment, the reflective display element 3
As 0, a ferroelectric liquid crystal panel is used. Since the ferroelectric liquid crystal has excellent angle characteristics, the angle of incidence and emission with respect to the display surface can be set large, thereby widening the angle of view. The effect of the present invention can be enhanced. The polarization direction of the linearly polarized light beam incident on the display surface of the reflective display element 30 by the illumination optical system 10 is selectively rotated by the display element 30 in accordance with the display image. When the display is off, the incident light is reflected while the polarization direction is preserved, and when the display is on, the polarization direction is rotated by 90 degrees and reflected. In addition, for example, by using LEDs of three colors of RGB as the light source 11, switching the display in synchronization with the emission of each LED, and controlling the output of the LED, it is possible to express colors and gradations.

The light beam emitted (reflected) at a predetermined angle with respect to the display surface normal on the display surface of the reflective display element 30 is
The light is incident on the prism body L1 while being refracted by the surface 18, is emitted from the prism body L1 while being refracted by the half mirror surface 17 having positive power, and reaches the polarizing plate 21. The light beam reflected by the display element 30 while maintaining the polarization direction is blocked by the polarizing plate 21. On the other hand, the light beam whose polarization direction has been rotated by the display element 30 passes through the polarizing plate 21 and is refracted by the surface 22 to enter the prism L2, enters the surface 23 at an angle greater than the critical angle, is totally reflected, and has a positive power. Mirror surface 24 having
And re-enters the surface 23 at an angle less than the critical angle,
The light is refracted, emitted from the prism body L2, and guided to the observation eye E. The surfaces 17, 18, 22, 23, 24 each have optical power and form an enlarged virtual image of the display element 30. The surfaces 22, 23, and 24 are constituted by rotationally asymmetric aspheric surfaces having different powers depending on the azimuth angles around the surface vertices, so that various aberrations caused by decentering the optical system can be corrected with a small number of optical elements.

In this embodiment, as shown in FIG. 4, the surface 24 is a half mirror surface, and a prism L4 is joined to the surface 24, and the light flux from the image displayed on the display element 30 and the image of the outside world is converted into the prism L4. The light may be guided to the observation eye E through L2, and both images may be observed in the same visual field. In FIG. 4, an observation system for observing an image of the outside world is configured by an optical system including the surface 25, the surface 24, and the surface 23.

In this embodiment, the illumination light is obliquely incident on and reflected from the display element 30 as described above, and further includes surfaces (surfaces 18 and 17) having power in the illumination optical system 10 and the display optical system 20. The common use of the optical element and the use of the reflective function and the transmissive function on one surface (the surface 17) constituting the optical element allow the distance between the optical element and the display surface to be set small, thereby increasing the angle of view and widening the angle of view. A compact optical system has been realized.

In this embodiment, not only the prism body L2 but also the surfaces 17 and 18 of the prism body L1 are given power, thereby reducing the power shared by the respective surfaces constituting the optical system. As a result, the occurrence of aberrations is kept low, and the contribution of aberration correction on each surface is reduced, so that the tolerance is loosened to facilitate manufacture.
Further, when the display optical system is constituted only by the prism body L2, when the power tends to be insufficient in the meridional direction (the paper surface direction in FIG. 1), the surface 17 is particularly placed in the sagittal direction (the paper surface in FIG. 1). The imaging performance is improved by using an anamorphic surface having a higher power in the meridional direction than in the vertical direction as a base. The surfaces 17 and 18 may be constituted by rotationally asymmetric aspheric surfaces having different powers depending on the azimuth angles around the surface vertices. According to this, it is possible to further improve the imaging performance.

Further, in this embodiment, two polarizing plates are arranged so that the polarization axes are orthogonal to each of the illumination optical system 10 and the display optical system 20, but this embodiment is not limited to this. Absent.

FIG. 2 is a schematic view of a main part of a second embodiment of the present invention. In the present embodiment, one polarizing plate 19 is provided immediately before the reflective display element 30 as shown in FIG. The embodiment 2 shown in FIG. 2 is different from the embodiment shown in FIG. 1 in that a polarizing plate 19 is provided instead of the polarizing plates 15 and 21, and a reflective display element 30a is provided instead of the reflective display element 30. Have the same configuration, and components having the same function are denoted by the same reference numerals, and description thereof is omitted.

The reflective display element 30a is a reflective display element 3
The polarization control for the incident light when the display is turned on and off differs from 0. In other words, when the display is on by the reflective display element 30a, the linearly polarized light beam incident on the display surface of the reflective display element 30a by the illumination optical system 10a is reflected while the polarization direction of the incident light is preserved, and the display is performed. When it is off, the polarization direction is rotated 90 degrees and reflected. Therefore, when the display is on, the light beam reflected by the reflective display element 30a can pass through the polarizing plate 19, and when the display is off, the light is blocked by the polarizing plate 19. In the case of such a configuration, in the illumination optical system 10a, the light from the surface 16 is
7, the prism body L is guided so as to be guided in a direction that does not enter the observation eye E as indicated by a broken line in FIG.
Each of the two surfaces constitutes.

Further, with this configuration, the prism body L
Since 1 may have birefringence, the range of material selection is expanded, and it is possible to reduce the size and weight.

Further, in the present embodiment, the illumination system is configured so as to be obliquely incident and reflected on the display element. However, for example, as shown in FIG. The configuration may be as follows. The embodiment shown in FIG. 5 is different from the embodiment shown in FIG.
1 has the same configuration except that a prism body L1a is provided instead of 1 and illumination light is perpendicularly incident and reflected on the display surface of the display element 30. Components having the same function are denoted by the same reference numerals. Description is omitted. With such a configuration, the distance between the optical element and the display surface is slightly larger than that of the embodiment shown in FIG. 1, but a display element 30 having a much better angle characteristic can be used.

FIG. 3 is a schematic view of a main part of a third embodiment of the present invention. The image observation apparatus according to the present embodiment includes an illumination optical system 40 including a surface light source 41, a condenser lens 14, a polarizing plate 15, and a lens L3 having a half mirror surface 31, a reflective display element 30 such as a liquid crystal element, a lens L3, and the like. Polarizing plate 2
1. It has a display optical system 50 composed of a prism body L2. Components having the same functions as those of the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

A light beam emitted from a surface light source 41 such as a light guide plate or a surface light emitting element passes through the polarizing plate 15 while being converged by the condenser lens 14 and becomes linearly polarized light, and is reflected by the half mirror surface 31 having positive power of the lens L3. Part of the light is reflected and enters the display surface of the reflective display element 30 at a predetermined angle with respect to the display surface normal. The surface 31 is constituted by a rotationally asymmetric aspheric surface having different power depending on the azimuth angle around the surface vertex, thereby correcting various aberrations caused by decentering the optical system.

On the other hand, the light beam transmitted from the half mirror surface 31 by the light beam from the deflecting plate 15 passes through the surface 32 and is
Polarizer 2 arranged so that its polarization axis is orthogonal to
1 and is not incident on the prism body L2.

The light beam emitted (reflected) on the display surface of the reflective display element 30 at a predetermined angle with respect to the display surface normal is:
The light is refracted by the lens L3 having the positive power (the surfaces 31 and 32) and reaches the polarizing plate 21. The light beam reflected by the display element 30 while maintaining the polarization direction is blocked by the polarizing plate 21. On the other hand, the light beam whose polarization direction has been rotated by the display element 30 passes through the polarizing plate 21 and is guided to the observation eye E through the same optical path as in the first embodiment, and the enlarged virtual image of the display element 30 is displayed. Form.

With this configuration, a small-sized optical system having a wide angle of view can be realized as in the case of the first embodiment, and the power shared by each surface constituting the optical system can be reduced. In addition, since the occurrence of aberration can be suppressed to a low level and the share of aberration correction can be reduced, manufacturing becomes easy because tolerances are loosened.

Also in this embodiment, the configurations shown in FIGS. 2 and 4 are naturally possible, and the configuration of the present invention is not limited by the arrangement of the polarizing plates and the display system of the reflective display element. For example, when a nematic type liquid crystal panel is used as a display element, the rotation angle of the polarized light can be controlled, so that gradation can be obtained by the rotation angle of the polarized light, and the driving frequency of the liquid crystal can be suppressed low.

In this embodiment, an LED or a surface light source is used as the light source means, but it may be configured to use external light.

[0045]

According to the present invention, as described above, when observing the image information displayed on the reflective display means such as a liquid crystal display in a wide observation field, the illumination system for illuminating the display means and the light from the display means are provided. By appropriately setting the configuration of an optical system for guiding the light flux to the observer's eyeball, for example, an optical unit including a prism having a refractive action, the image information can be obtained while reducing the size of the entire apparatus. It is possible to achieve an image observation device capable of observing good image quality in a wide observation visual field.

In particular, according to the present invention, it is possible to reduce the size of the image observation apparatus and to widen the angle of view even when a reflective display element is used. In addition, the number of optical working surfaces can be increased without increasing the size of the apparatus, and the power of each surface and the sharing of aberration correction can be set low, so that effects such as easy manufacturing can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

FIG. 2 is a schematic diagram of a main part of a second embodiment of the present invention.

FIG. 3 is a schematic diagram of a main part of a third embodiment of the present invention.

FIG. 4 is an explanatory view of another embodiment of FIG. 1;

FIG. 5 is an explanatory view of another embodiment of FIG. 1;

FIG. 6 is a schematic diagram of a main part of a conventional image observation device.

FIG. 7 is a schematic diagram of a main part of a conventional image observation device.

FIG. 8 is a schematic diagram of a main part of a conventional image observation device.

[Explanation of symbols]

 10, 40 Illumination optical system 11 Light source means 12 Condenser lens 13 Diffusion plate 14 Condenser lens 15, 21, 19 Polarizer L1, L2, L4 Prism body L3 Lens 20, 50 Display optical system 30 Reflective display element

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazutaka Inokuchi 6-145 Hanasaki-cho, Nishi-ku, Yokohama-shi, Kanagawa Prefecture Inside M-R System Co., Ltd. (72) Inventor Hideki Morishima Hanasaki-cho, Nishi-ku, Yokohama, Kanagawa 6-145 MRC System Research Institute

Claims (12)

[Claims] 1. A reflection type display means, an illumination optical system for causing a light beam from a light source means to enter the display means, and a display optical system for guiding the light beam from the display means to an observation position of an observer. An image observation device comprising: the illumination optical system and the display optical system share some optical elements, and the optical elements have a curved surface. 2. A display device of a reflection type, an illumination optical system for causing a light beam from a light source device to enter a display surface of the display device in an oblique direction, and a light beam from the display device being guided to an observer. A display optical system for observing image information displayed on the display means, wherein a chief ray emitted from a central portion of the display means is emitted from the display means in an oblique direction, and The optical system has a decentered non-rotationally symmetric reflecting surface, the illumination optical system and the display optical system share some optical elements, and the shared optical element has at least one surface. An image observation device characterized by having a curved surface. 3. A reflection type display device, an illumination optical system for guiding a light beam from a light source means to the display device, and a display optical system for guiding a light beam reflected by the display device to an observation eye and allowing the observation eye to observe an image. The display optical system has a non-rotationally symmetric reflection surface having at least one surface decentered, and a principal ray of a display light flux at a central angle of view from the display means is perpendicular to a display surface normal of the display element. In contrast, the illumination optical system and the display optical system share a part of optical elements, and the illumination optical system and the display optical system have at least one surface formed of a curved surface. Image observation device. 4. An apparatus according to claim 1, wherein said optical element has a non-rotationally symmetric surface. 5. The optical element according to claim 1, wherein the optical element has a surface that functions as a transmission surface in an optical path of the display optical system and a reflection surface in an optical path of the illumination optical system. The image observation device according to any one of the above items. 6. The image observation apparatus according to claim 5, wherein the surface of the optical element acts as a positive power in both the display optical system and the illumination optical system. 7. The image observation apparatus according to claim 5, wherein the surface of the optical element is a curved surface. 8. The image observation apparatus according to claim 1, wherein the reflection type display element is a ferroelectric liquid crystal panel. 9. A reflection type display means is obliquely illuminated through a first prism body made of a single medium having three or more optical surfaces including a surface decentered with a light flux from a light source means, The light flux emitted obliquely from the display means includes a surface decentered via a part of the optical surface of the first prism body.
An image observation device, wherein light is guided to an observer through a second prism body made of a single medium having at least one optical surface, and the image information displayed on the display means is observed. . 10. The first prism body is a half mirror surface including an incident surface on which the light beam from the light source means is incident, a non-rotationally symmetric surface for reflecting a part of the light beam from the incident surface,
10. An emission surface for emitting a light beam reflected by the half mirror surface to the display means side.
Image observation device. 11. A light beam from the display means enters from the exit surface of the first prism body, passes through a half mirror surface, exits from the first prism body, and enters the second prism body. The image observation device according to claim 10, wherein: 12. The incident surface on which the second prism body receives a light beam from a half mirror surface of the first prism body.
A total reflection surface for totally reflecting the light beam from the incident surface, a reflection surface composed of a non-rotationally symmetric surface for reflecting the light beam from the total reflection surface, and the same shape as the total reflection surface for emitting the light beam from the reflection surface The image observation device according to claim 11, further comprising: