KR20040005031A - Optical system using single display device for head mounted display - Google Patents

Abstract

PURPOSE: An optic system for single panel type head mount display is provided to reduce largely a manufacturing cost by simplifying a structure of the head mount display and reducing the weight of the head mount display. CONSTITUTION: An optic system for single panel type head mount display includes a display element(401) and a free curve prism(402,403). The display element(401) is used for displaying pictures. The free curve prism(402,403) is arranged in front of the display element(401) in order to enlarge the pictures. The free curve prism(402,403) has four surfaces such as an incident surface, two reflective surfaces(404,405,406,407), and an output surface. The free curve prism(402,403) has a path to form positive pictures on both eyes. The incident surface and the output surface are formed with aspheric lenses in order to correct the distortion.

Description

Optical system using single display device for head mounted display}

In general, a head mounted display device uses a precise optical device in a position very close to the eye and an image display device that allows a user to view a large screen image by constructing a screen by shortening a focal length that can cause an image on the eye. It was initially developed as a device for implementing a virtual reality system for military, education, medical, and entertainment, but now its utility value is increased as a display device for more diverse purposes such as portable computers, DVDs, and TV viewing. Therefore, not only a very precise optical system for realizing a large screen image, but also various devices capable of processing various video signals in a simple, economical manner for carrying HMD are required.

The type of head mounted display is based on the shape of the helmet, glasses, and monocular type (MONOCULAR TYPE) and binocular type (BINOCULAR TYPE), depending on the number of images provided to the eyes. TYPE) and STEREOSCOPIC TYPE, among which binocular type is the most widely used.

Such a binocular type conventional head mounted display has two display elements (LCD, etc.) 101, 102 as schematically shown in FIG. 1, which are in front of the user's left and right eyes 105, 106. Located in An eyepiece 103 or 104 is provided between the left and right eyes 105 and 106 of the user and the two display elements to enlarge and provide an image displayed on the display element to the user. At this time, the shape of the eyepiece 103 (104) may use a concave, convex or free-curved lens according to the developer's intention, and may enlarge the image using a curved reflector.

However, the conventional head-mounted display of the above method requires two expensive display elements, which increases the price of the product, thereby lowering the competitiveness, and increases the weight of the head-mounted display and requires a separate for each display element. There is a disadvantage in that a separate substrate for signal generation inside the wiring or head mounted display is required.

2 and 3 show another example of the configuration of the HMD according to the prior art using a single display element.

Referring to FIG. 2, the structure of the HMD according to the related art using a single display element of another example is arranged in the liquid crystal panel 201 for displaying an image and behind the liquid crystal panel 201 to the liquid crystal panel 201. A back light 202 that emits light and a half mirror that passes through the liquid crystal panel 201 and reflects some of the light including the image, and passes the rest of the reflected light to the left eye of a human being. Half mirror (203), a total reflection mirror (204) for reflecting the light passing through the half mirror (203) to change the path to the right eye of the person, and the light reflected from the half mirror (203) in parallel light The first eyepiece 205 for changing to a left eye and forming an image in the left eye, the second eyepiece 206 for converting light reflected from the total reflection mirror 203 into a parallel light and forming an image in the right eye, and the half mirror Between 203 and the total reflection mirror 204 Value is provided with an optical system that the optical path length comprises an adjustable lens (207). Since the path lengths from the liquid crystal panel 201 to the eyepieces 205 and 206 are different from each other, the optical path length adjusting lens 207 is disposed on a long optical path, thereby reducing the optical path length. 201) to make the image displayed in the user's left and right eyes the same size.

The optical system using a single display element of the prior art having the above configuration operates to separate light including an image from the half mirror 203 while passing through the liquid crystal panel 201 to form an image on the left and right eyes. Since the optical path length adjusting lens 207 is used to view an image of the same size in the eye, there is a problem in that a complex optical system is configured with two eyepieces. In addition, since the half mirror 203 has the same reflection amount and transmission amount, light entering the eyes on the left and right sides has a different brightness due to the difference in path lengths, and thus a problem in that it is impossible to provide a good image to the user.

The structure of the HMD according to the prior art using a single display element of another example shown in FIG. 3 is an X-prism (X-) that is commonly used as a beam splitter when separating an image into left and right images from a single display element. prism) 303 is shown. The optical system uses a conventional lighting device 302 for generating an image, and a liquid crystal panel 301 and a projection lens 304 positioned directly in front of the lighting device 302 for light efficiency. The X-prism 303 is located at the center of the liquid crystal panel 301 to divide the single image into separate left and right identical images for the user's eyes. A typical X-prism 303 consists of four pieces of glass prisms coated with a metal or dielectric on one side of each piece, and these four pieces of prism are bonded to each other in an X shape. The X-prism 303 divides the image from the liquid crystal display 301 to generate an equally separated image, which is reflected through the mirrors 305 and 306, respectively, through the eyepieces 307 and 308. Give each with your eyes.

Prior art head-mounted display systems having a single display element configuration using the X-prism should have a very thick thickness of the eyepieces 305 and 306 to realize a large screen. ) Is shortened, so even if you move your eyes a little, the surrounding image is not visible. In addition, since only 25% of the first incident light can be used, not only the light efficiency is lowered, but also there is a problem that image distortion is aggravated with a slight error compared to other optical systems in the X-prism configuration.

Therefore, the present invention is a conventional head-mounted display device of the conventional head-mounted display device has a complicated structure of the optical system and the weight is increased by using a plurality of display elements, which is inconvenient to use and expensive, making it difficult for the general public to use universally The purpose of the present invention is to provide a head mounted display that can simplify the structure, reduce the weight, greatly improve the portability, and significantly reduce the manufacturing cost.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 schematically shows the configuration of an optical system for a head mounted display having two conventional display elements.

2 and 3 schematically show an example of an optical system for a head mounted display having a conventional single display element.

4 schematically shows the configuration and arrangement of an optical system for a head mounted display with a single display element according to the invention;

5 and 6 and 7 show another embodiment of an optical system for a head mounted display with a single display element according to the invention.

In order to achieve the above object, the present invention provides a single organic EL display which can emit light without requiring a separate light source, which simplifies weight and structure, and has low power consumption and high response speed to image change. An element OLED; A free-curved prism disposed at the front left and right sides of the organic EL display element to enlarge an image; And a reflective film coated on the reflective outer surface of the free curved prism to allow total reflection at the internal reflective surface of the free curved prism.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 is a schematic illustration of a first embodiment of the construction and arrangement of an optical system of a head mounted display using a single display element according to the invention. As shown in FIG. 4, first, an optical system for a head mounted display according to the present invention is provided with one display element 401 representing an image. The display element 401 is an organic EL display panel (OLED display panel) capable of producing a high-pixel image without a separate light source including a self-luminous material and is disposed substantially vertically so as to face left and right eyes.

Between the OLED display element and both eyes, left and right free-curved prisms 402 and 403 are inclined at a predetermined angle with respect to the horizontal plane of the display element to face each other to bifurcate the image generated in the display element. The spherical prisms 402 and 403 serve as a screen for providing a magnified image as a kind of multi-facet prism having an incidence surface, two reflecting surfaces, and an outgoing surface, and the incidence surface and the reflecting surfaces 404 and 405 It forms a slightly convex surface and the reflecting surfaces 406 and 407 and the exit surface are slightly concave. The image slightly concentrated at the first reflective surface 404 and 405 through the incident surface is greatly enlarged so that a large screen is produced at the second reflective surface 406 and 407 in the diagonal direction as shown. The incidence plane is composed of aspherical surfaces with different curvatures in consideration of the distortion of the image in the horizontal and vertical directions, and the emission surface is also aspheric for the correction of distortion aberration.

With this configuration, the image projected from the display element 401 onto the incident surface of the free-curved prism 402 or 403 is outside the first reflecting surface 404, 405 and the second reflecting surface 406, 407. It is totally reflected in the coated mirror reflecting film and is refracted through the exit surface and incident on the left and right eyeballs 408 and 409, respectively.

Therefore, since the head mounted display of the present invention configured as described above is operated by one display element, the total weight is lighter than the conventional two display elements and a separate light source. Can be reduced to one, which reduces cost.

5 is a schematic diagram illustrating another embodiment of the construction and arrangement of an optical system of a head mounted display using a single display element. The second embodiment is an example in which the incident angle and the curvature of the reflecting surface of the free-curved prism are arranged to be adjusted in the configuration of the first embodiment shown in FIG. According to the second embodiment, the incidence surfaces of the free-curved prisms 502 and 503 and the reflecting surfaces 506 and 507 form a slightly concave surface, and the reflecting surfaces 504 and 505 and the exit surface are slightly convex. The image generated at the reflecting surfaces 506 and 507 from the display element 501 through the mirror reflecting film passes through the exit surface as in FIG. 4, and focus is formed to transmit images to the left and right eyeballs. .

6 and 7 are schematic diagrams showing yet another embodiment of the construction and arrangement of an optical system of a head mounted display using a single display element.

Embodiments according to the above description can be variously changed and modified without departing from the spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the examples, but should be defined by the claims.

The head mounted display having the optical system according to the present invention is capable of self-luminous and relatively high power consumption by using only one of the high-pixel organic EL display element, the screen configuration of the large screen is possible to reduce the manufacturing cost to have a cost competitiveness It is possible to secure the general purpose of product development for the general public for the head mounted display, which has been in demand only for special purposes and tier, and it is possible to use it for a long time even with a portable rechargeable battery by minimizing the power consumption. It has the effect of greatly improving. In particular, by simplifying the structure can significantly reduce the weight, there is an advantage that can reduce the burden on the user for the headache and dizziness caused by weight when worn for a long time. In addition, instead of the high brightness LED light source used in other head mounted displays, the organic EL display device has a high light efficiency and relatively low self-heating phenomenon. This can solve problems.

Claims (2)

In the head mounted display which enlarges an image output from a single display element at a predetermined ratio to generate a large screen, A display element for displaying an image; And a free-curved prism disposed in front of the display element to magnify the image. In freeform prisms for creating large surfaces, A free-curved prism having a total of four surfaces, such as an entrance plane, two reflection planes, and an exit plane; A free-curved prism whose path is configured such that a forward image is formed in both eyes after the image incident through the incident surface from the display element is reflected at the first and second reflective surfaces; Free-form prism with aspherical surface of entrance and exit surface to correct distortion aberration.