DE19620658C1 - Head-mounted display device - Google Patents

Abstract

The invention relates to a head-mounted display which has fastening means which can be used to fasten the display to the head in a predetermined carrier position, and projection means. Said projection means has a micro-mirror array (1) with a plurality of micro mirrors which can be turned in at least two positions, and a light source. Light emitted from the light source is beamed on the micro-mirror array. By turning the micro-mirror in a selective manner into one of the two positions, the light reflected from the micro-mirror array (1) produces the picture elements of the projection. Said projection itself may be obtained in that a picture produced by the micro-mirror array (1) is displayed by a magnifying lens (6) on a semi-permeable glass disc (8) with the result that the projection is visible to the eye (7).

Description

The invention relates to a display device, the Head is portable, a so-called head-mounted display (HMD) the preamble of claim 1.

A display device according to the preamble of claim 1 known from PHOTONICS SPECTRA, June 1995, p. 18 or from DE 40 09 047 A1.

Advanced simulation techniques, animations with moving Images and virtual environments require new concepts for Human-machine communication. Such a concept is a so-called called HMD. Among them there is a general one and also in the following Understood display device, the z. B. comparable to one normal glasses or with a headband or a helmet is worn on the head. The display device has two small ones Display devices, usually called liquid crystal stall display device (LCD) are formed on. Between the eyes and the display units are usually each lens assigns a sharp image of the display unit to the Retina with relaxed eye lens (relaxed vision) possible chen. Such a display device, worn like glasses is called "Virtual i-glasses" by the company Virtual Products GmbH, Bensheim. Such an approach pointing device, which is arranged in a helmet, is off "Helmet-mounted displays incorporate new technology", Chris Chin nock, LASER FOCUS WORLD, May 1995, pp. 145-152.  

Images are produced in the usual way on the display units shown. A representation that is a three-dimensional one pressure (stereo vision) is conveyed by the display perspekti visch different pictures for the left and the right eye achieved, as in Eli Peli, "Real Vision & Virtual Reality", Optics & Photonics News, July 1995, pp. 28-34. Such so-called stereo image signals are generated in known way by stereo cameras or computer image animation.

For the area of so-called "virtual reality", i. H. the ver determination of environments and events created in the computer, the display devices (HMD) also have sensors for determining head position and head movements.

One of the main problems of the known solutions is the behavior The image quality is limited due to the small number of pixels (Number of pixels) and pixel density of the image used screens of the display units. Depending on the screen technology used nology, the brightness and color dynamics are severely limited.

In the advertisement known from PHOTONICS SPECTRA, June 1995, p. 18 The image is displayed on an inclined device Projected disc that is about 10% permeable to the outside light passing through towards the eye remains. This will make one Overlay of projection and environmental view possible.

Micromirror arrays are known from microsystem technology. On such a micromirror array (DMD = digital micromirror device) has several hundred thousand mirrors arranged in a matrix arranges and individually for changing the mirror position are controllable. A common DMD chip with outer Dimensions of approx. 3 × 4 cm, in 5 V, 0.8 µm CMOS technology has an active mirror array area of approximately 15 × 13 mm with approx. 440,000 mirrors. Such a DMD chip is fine work technology and measuring technology F & M, 6/1995, p. 324.  

Such DMDs are currently used for the development of large-format images screens for high-definition television (HDTV) used, as z. B. in electronics 2/1996, pages 56-58 and 63-70. The DMD reflects light in depending on the local mirror position the projection optics. The color attribute of a pixel results from the temporal synchronization of the mirror position with a rotating color filter disc. Alternatively, for each color (RGB) a DMD can be used. The colors (RGB) can be with a lamp and filtering or using three lasers.

From DE 44 26 877 A1 an eye test device is known in which eyesight Sign using a DMD illuminated by a light source is under the control of a projection control device be fathered. The optotypes can be direct or as a projection to be sought.

DE 39 38 515 A1 discloses a device for stereoscopic reproduction shear video images known that a display device after Preamble of claim 1, wherein the image information for the right and left eye through an LCD monitor testifies and projected in front of the eyes via a mirror and lens system is decorated.

DE 40 10 789 A1 describes an optical fiber security system known in which two optical fibers for the transmission of two Laser beams are used.

From US 5 457 566 is the use of a DMD in an IR scan system known.

It is an object of the present invention to provide a display device device that can be worn on the head, to indicate the simple way improved image display and flexible application possibilities offers.

This object is achieved by a display device according to An saying 1.

Developments of the invention are specified in the subclaims ben.

The display device enables by using the micro mirror arrays with its high resolution and the possibility of Using almost any light source with an image display high resolution and high brightness and color dynamics.

By using an optical fiber to deliver the light to the Micromirror array will provide great flexibility for construction reached the display device. It can z. B. the Lich producing components and the control arranged at the back of the head be, so that the comfort increases weight distribution is possible.

Further advantages and advantages of exemplary embodiments of the invention result from the description of exemplary embodiments with reference to the figures. From the figures show:

Fig. 1 is a schematic diagram of the light source, the optics and the micromirror array according to one embodiment of the invention;

Fig. 2 a), b) the geometrical relationships of the light entry and -ausfalls on a micromirror array according to an embodiment of the invention;

Figure 3 is a schematic representation of the projection directly into the eye according to an embodiment of the invention. and

Fig. 4 is a schematic diagram of the projection onto a pane according to an embodiment of the invention.

A display device that can be worn on the head after an off leadership form of the invention has a fastening device such an eyeglass frame, a headband or a helmet, by means of which the display device on the user's head in front agreed carrying position is attachable. The display device device generates the projection by means of a projection device an image to be displayed to the user. Doing so the image information by a projection control device in usual way, as described in the introduction, in a showing picture implemented. Depending on the application, a two-dimensional or, in a known manner, a three-dimensional one Picture (stereo viewing) in black and white (B / W) or in colored representation can be generated.

In the display device, the pixels of the on image to be displayed, the projection of which will be described later, generated by the micromirrors of a micromirror array. To the micromirror array is loaded with light from a light source shine. For a color representation of the image to be displayed are according to an embodiment of the invention in the usual way Use three color parts for an RGB representation of the color image det. The red, green and blue components are after one Embodiment of the invention by photo or laser diodes generated. Photo or laser diodes, the red or green light are already readily available today. Photo or Laser diodes that generate blue light are in the Development and will be available in the foreseeable future. Alternatively, the blue color component by a small lamp be generated with an appropriate color filter.  

The generation of the RGB components and the irradiation of the micromirror array with these color components by means of an irradiation optical system will now be described on the basis of the basic illustration in FIG. 1. As shown in FIG. 1, the three diodes D1 to D3, each of which generates one of the color components, are arranged in such a way that they couple the color component emitted by them into a fiber optic fiber 3 via a coupling device. The coupling device is designed as a lens 2 in FIG. 1. The light coupled into the glass fiber 3 (RGB components) is guided through the glass fiber 3 in a conventional manner and, after exiting the glass fiber 3, through an optical radiation system 4 , which is designed as a collection and collimation lens system in FIG. 1, onto the micromirror -Array 1 directed.

As an alternative to the lens 2 shown in FIG. 1, the coupling device can also be designed as follows by means of a mirror and two beam splitters. The diodes are arranged along a line in a first direction next to one another in such a way that they emit the light generated by them perpendicular to this first direction and parallel to the light emitted by the respective other diodes. The light of the first diode seen in the first direction is deflected by a mirror through 90 ° in the first direction, so that the deflected light crosses the beams emitted by the other two diodes at an angle of 90 °. Beam splitters are arranged at each of the two crossing points defined in this way, which also deflect the light emitted by the other two diodes by 90 ° in the first direction and the light from the preceding diode that is already incident on the back and is already deflected by 90 ° in the first direction (n) let through so that a light beam having all three color components and propagating in the first direction is produced. This is then coupled into the glass fiber in the usual way.

As described at the outset, a micromirror array in FIG a construction currently in use around 440,000 mirrors, which in an X-Y matrix are arranged. Each of the mirrors can se be deflected selectively in three positions. In the first or the second position is the normal or mirror axis of the one  individual micromirror by ± 10 ° compared to the normal of the X-Y-Matri xplane deflected. In the third position is the normal or Mirror axis of the micromirror parallel to the formal of the X-Y matrix level.

In the following, with reference to Fig. 2 a) and b) the geometric relationship of the light entry and -ausfalls described on a micro mirror array. As shown in Fig. 2a), a plane E is spanned by the XY matrix of the micromirror array 1 , the normal N of which coincides with the Z axis of the corresponding Cartesian coordinate system. The light used for irradiating the micromirror array 1 , which is generated as described above, is incident on the micromirror array 1 along a direction C which lies in the XZ plane. The direction C is at an angle -γ to the normal N of the plane E.

To simplify the description, it is assumed below that, as shown in Fig. 2 b), each micromirror 5 of the micromirror array 1 can only assume the first position S1 and the second position S2, which were described above. In the first position, the normal or mirror axis A of the micromirror 5 is at an angle -α to the normal N of the plane E. In the second position S2, the micromirror 5 is at an angle of + β to the normal N of the plane E.

In FIG. 2 a) shows the case in which the angle γ is equal to twice the angle α. It follows that the light incident from the direction C is reflected by a micromirror 5 , which is in the first position S1, in the direction of the normal N of the plane E. If a micromirror 5 is in the second position S2, then the light incident from the direction C is reflected at an angle of 2β + γ to the normal N in the XZ plane.

The light reflected by the mirrors in the first position S1 is used to project the image to be displayed, while the light reflected by the micromirrors in the second position is directed into a beam trap. The normal N of the plane E in FIG. 2a) therefore coincides with the projection direction PR, ie with the direction in which the reflected light is used for the projection. By an appropriate deflection of the micromirror 5 of the micromirror array 1 into the first or the second position, an image with several hundred thousand pixels can therefore be generated.

According to one embodiment, a micromirror array is used for each Generation of the projection of the image for the left or the right Eye used.

As is readily apparent from the illustration in FIG. 2 a), a single micromirror array 1 can also be used to generate two different images (for example for the left and right eyes). If, for example, the direction C of the incident light lies in the YZ plane, it is possible to use the light reflected by the micromirrors in the first position S1 to project a first image for the left eye and that in the second position S2 Micromirrors use reflected light to project a second image for the right eye. The light reflected by the micromirrors in the third position described above is reflected in the beam trap.

In Fig. 3, the display is an image using a micromirror array 1 through a projection displayed directly on the retina of the eye. 7 For this purpose, the image generated by the micro mirror array 1 with the micro mirrors 5 in the first position S1 is advantageously enlarged by a magnifying lens 6 prior to the projection onto the retina of the eye 7 .

FIG. 4 shows the projection of the image generated by the micromirrors 5 of the micromirror array 1 in the first position S1 onto a type of “ground glass” 8 . The image generated by the micromirror array 1 is expediently enlarged by a magnifying lens 6 . The term “ground glass” is to be understood in such a way that the ground glass is either an exclusively diffusely scattering pane or a semi-transparent glass pane. When using a semi-transparent glass pane, there is the advantage that the user of the display device can perceive the projected image and at the same time the surroundings. According to a special embodiment, the semi-transparent glass sheet 8 is formed such that it consists of an electrochromic or electro-optical material which can be made impermeable or semi-transparent by applying an electrical or magnetic field. If necessary, the projected image can be enlarged by a second magnifying lens arranged between the focusing screen 8 and the eye 7 . The second magnifying lens is not shown in FIG. 4.

The above-described embodiments of the display device have in common that the image to be displayed can be generated by controlling the individual micromirrors 5 of the micromirror array 1 and irradiating the micromirror array with the light from the light source. In order to achieve a color representation of the image to be displayed, it is necessary to synchronize the control of the micromirrors and the chronological sequence of the generation of the color components (RGB components).

The micromirror array 1 is for this purpose with a periodically repetitive sequence of the color components, e.g. B. RGBRGB. . . ., be irradiated. The synchronization takes place according to an embodiment by direct activation (switching on and off) of the corresponding laser or photodiodes and a coordinated activation of the micromirrors, which is readily possible given the short response times of today's diodes. According to another embodiment, an electro-optical component, such as a Kerr or Pockels cell, is placed between the individual diodes and the coupling-in device, so that control of the chronological sequence of the generation of the color components and a by appropriate control of the electro-optical components so that coordinated control of the micromirrors is possible without any problems.

For a B / W representation of the image to be displayed with gray value variation, the micromirror array 1 is irradiated with white light. By controlling the time period within which a micromirror 5 , which reflects the light for a specific pixel, is in the first position, the gray value of this pixel is set. That can e.g. B. happen by a back and forth movement of the corresponding micromirror 5 between the first and the second position. The contribution of one of the color components (R, G, B) to the color of a pixel in a color display is generated in a comparable manner.

The above-described supply of the generated by the diode Light leads to the micromirror array by means of a glass fiber to the fact that the structure of the display device with respect to the arrangement of the individual elements very simply to different An requirements can be adjusted.

Claims (10)

1. Display device that can be worn on the head with a fastening device, such as an eyeglass frame, a headband or a helmet, by means of which the display device can be fastened to the head in a predetermined carrying position, and a projection device that is supplied by a projection control device Image information for the display thereof is projected such that the projection is visible to the eye or the eyes in the predetermined carrying position,
characterized in that
the projection device
a micromirror array ( 1 ) with a plurality of micromirrors ( 5 ), each of which can be controlled for deflection in at least two positions, a first and a second position (S1, S2), and has a light source (D1-D3),
wherein the micromirror array ( 1 ) is irradiated by the light emitted by the light source (R, G, B) and the projection control device controls the micromirrors ( 5 ) in accordance with the image information to be displayed such that they selectively enter the first or Steer from the second position and the light (R, G, B) reflected by the micromirrors ( 5 ) deflected into the first position (S!) generates the pixels of the projection. 2. Display device according to claim 1, characterized in that the micromirror array ( 1 ) has the plurality of micromirrors ( 5 ) in one plane (E), the normal or mirror axis (A) of each micromirror ( 5 ) in the first position (S1) at a first angle (α) and in the second position (S2) at a second angle (β) to the normal (N) of the plane (E). 3. Display device according to claim 1 or 2, characterized in that the projection device is an optical system ( 2-4 ), the micromirror array ( 1 ) with the light emitted by the light source (D1-D3) (R, G, B) irradiated from a radiation direction (C) which is at a third angle (γ) to the normal (N) of the plane (E). 4. Display device according to one of claims 1 to 3,
characterized,
that the light source three diodes (D1 to D3), each providing a color component (R, G, B) of the light for a color representation of the individual pixels, and
a color component control device which controls the emission of the individual color components (R, G, B) of the light in such a way that the respective color components are sequentially emitted from the light source in a cyclically and reversing order, and
that the projection control device controls the micromirrors ( 5 ) synchronized with the order in which the color components (R, G, B) of the light are emitted by the light source in such a way that the reflected color components give the color value and the brightness of the pixels of the projection. 5. Display device according to one of claims 1 to 4, characterized in that the optics an optical waveguide ( 3 ) such as a glass fiber, a coupling device ( 2 ) for coupling the light emitted by the light source into the optical waveguide, and an irradiation optics ( 4 ), which irradiates the micromirror array ( 1 ) with the light emerging from the optical waveguide. 6. Display device according to one of claims 1 to 5, characterized in that the light from the micromirrors ( 5 ) located in the first position (S1) is reflected by a magnifying lens ( 6 ) for projection. 7. Display device according to one of claims 1 to 6,
characterized,
that the projection device has two micromirror arrays ( 1 ), and
that the pixels of the projection for the corresponding image information for the left eye by reflecting the light with the first of the two micromirror arrays ( 1 ) and for the right eye by reflecting the light with the second of the two micromirror arrays ( 1 ) be generated. 8. Display device according to one of claims 2 to 6,
characterized,
that the projection device has a micromirror array ( 1 ), the micromirror ( 5 ) in a third position in which the normal or mirror axis (A) of each micromirror ( 5 ) at a fourth angle to the normal (N) of the plane (E ) stands, are deflectable, and
that the pixels of the projection for the corresponding image information for the left eye by reflection of the light by means of micromirrors ( 5 ) deflected in the first position (S1) and for the right eye by means of reflection of the light by means of micromirrors deflected by the second position (S2) ( 5 ) are generated. 9. Display device according to one of claims 1 to 8, characterized in that the projection takes place directly on the retina of the corresponding eyes ( 7 ) or on a disc ( 8 ) such as a ground glass. 10. Display device according to one of claims 4 to 9, characterized, that the color fraction control device for generating the recurring order of the respective color components switches the three diodes (D1 to D3) on and off directly, or the amount of color emitted by the three diodes (D1 to D3) because of an electro-optical component such as a Kerr or Pockels cell selects according to the order.