KR100597451B1 - Optical System For Biocular Head Mounted Display - Google Patents

Abstract

The present invention relates to a single-plate binocular head mounted display optical system, the main configuration of which has a single display element, and a rotationally symmetric aspherical reflective surface for respectively transmitting left and right images of light emitted from the display element. On the front of the left and right eyes, respectively, the first and second reflection surfaces on the left and right sides, the first and second reflection surfaces facing the first reflection surface, and the rotationally symmetric aspherical surfaces positioned on the left and right sides of the display element. A user's pupil of each of the left and right prism lenses having two planes and one rotationally symmetric aspherical reflective surface, and the image light emitted from the prism lens to transmit the image light reflected from the second reflective surface to both eyes. Special eyepieces including left and right eyepieces each consisting of a rotationally symmetric aspherical surface focused on By using only one display element, which is an expensive component among the components of the head mounted display, a significant cost reduction effect is expected, and each lens is configured by configuring the optical system of the head mounted display using only the rotationally symmetric aspherical surface. It is possible to minimize the cost and time required to manufacture the product by facilitating the performance inspection and calibration of the product.

Display element, first reflective surface, second reflective surface, prism lens, eyepiece

Description

Optical System For Biocular Head Mounted Display

1 is a cross-sectional view schematically showing a conventional two-plate binocular head mounted display optical system,

2 is a cross-sectional view schematically showing a conventional single plate binocular head mounted display optical system,

3 is a cross-sectional view of a single plate binocular head mounted display optical system according to the present invention;

4 is a cross-sectional view showing a mirror coating for reflection of the left and right binocular prism lens according to the present invention,

5 is a cross-sectional view showing an inclined angle with respect to the incident surface of the eyepiece according to the present invention.

<Description of Symbols for Major Parts of Drawings>

30 display element 31L: first reflective surface for the right eye

31R: 1st reflective surface for left eyes 32L: 2nd reflective surface for right eyes

32R: 2nd reflection surface for left eyes 33L: Prismatic lens for left eyes

33R: Right eye prism lens 34L: Left eye eyepiece

34R: Eyepiece for Right Eye

The present invention relates to a single plate binocular head mounted display optical system, and more particularly, a single plate that can significantly lower the product price, and can be easily manufactured and tested for performance, thereby minimizing time and cost for commercialization. A binocular headmount display optical system.

In general, the head mounted display device focuses the video light generated at a position very close to the eye so that a virtual large screen can be composed at a long distance using a precise optical device so that the user can see the enlarged virtual image. An image display device comprising: a binocular (BINOCULAR) method for forming independent optical paths in both eyes in two display elements, and a single plate binocular for forming symmetrical optical paths in both eyes using one display element. ) And a single plate monocular (MONOCULAR) system that provides an optical path only to one eye of both eyes from one display element. FIG. 1 and FIG. 2 are two-sided binocular and single plate binocular HMD optical systems. An example is shown.

First, the dual plate binocular HMD shown in FIG. 1 includes an illumination unit 10 for providing a light source to the liquid crystal panel for the left and right eyes, a display element 11 for displaying an image, an entrance surface 121, and a first, respectively. It consists of an optical system including a rotationally asymmetric free-curve prism lens 12 having a reflection surface 122, a second reflection surface 123, and an exit surface 122, and the display element 11 according to the above configuration ), The image light generated by the light incident on the free-curve prism through the incident surface 121 reaches the first reflective surface 122 at an angle smaller than the critical angle, and is totally reflected on the first reflective surface 122, and then reflected again. After reflecting from the second reflective surface 123 to be coated, it exits the prism lens through the exit surface 122 which shares a surface with the first reflective surface and forms an image on both eyes 13 of the user.

However, the optical system method using the two display elements and the rotationally asymmetric free-curved prism lens of the prior art having the above-described configuration has a simple optical path construction due to the characteristics of the free-curved prism lens that can adjust the direction of light within a certain range. It is possible to greatly reduce the thickness of the HMD and to secure a wide field of view (FOV), but it requires two expensive display elements, which not only increases the price of the product but also lowers the competitiveness. In addition, the two display elements and separate wiring for each display element, and a circuit and components added thereto have a disadvantage in that the weight becomes heavy. In addition, the above method has at least one rotationally asymmetric free surface in the prism lens in order to reduce distortion due to eccentric error, which is relatively difficult compared to the rotationally symmetric optical system, and properly manufactured according to design. It was very difficult to test the performance of this, and if an error occurred, it was difficult to identify the cause of the problem that the possibility of generating a lot of cost until the product was very high.

In view of the problems of the two-plate binocular HMD, a HMD by a single plate binocular (BIOCULAR) method as shown in FIG. 2 has been proposed, and its main configuration includes one display element 20 for providing an image and the display element. A pair of collimating lenses 21 for converting the image light generated at a predetermined angle from one point of 20 into parallel light, and a center crossing to distribute the parallel light equally in both left and right eyes. A pair of X prism 22 having a transflective mirror coating surface on a diagonal surface and a pair of left and right converging the image light distributed from the X prism 22 so that a focal point can be formed at one point. A focusing lens 23L, 23R, a pair of left and right planar reflectors 24L, 24R for changing the angle of the image light converged from the focusing lenses 23L, 23R in the direction of the eye; Finally the image light It consists of a pair of left and right eyepieces (25L, 25R) that form an image on the user's eyes (EL, ER), and the optical system of the above configuration uses the same image for both eyes even if only one expensive display element is used. Since the transmission is possible, the product price can be lowered, and since the image light is folded to 45 ° by using the X prism 22 and the planar reflectors 24L and 24R, eccentricity does not occur, so distortion and other aberration correction are easy, In constructing the collimating lens and the eyepiece, there is an advantage that the image can be imaged only by the curved surface of the rotation symmetry.

However, the above technique requires passing through the transflective mirror coating surface twice before the image light generated from the display element 20 passes through the X prism 22 and is distributed to both eyes, so only 25% of the initial amount of light is delivered to both eyes. 75% is lost in the reflection process, which makes it difficult to realize the natural color of the original image light. Therefore, in order to provide an image of proper brightness to the user's eye, a high-brightness light source must be used separately in consideration of the amount of lost light. In addition, since the X prism may appear as a line of intersection at the center of the X prism when the user views the image, it has to be manufactured precisely to allow no error at all, which increases the production time and cost. do.

Accordingly, the present invention has been made to solve the above-described problems, the object of which is to eliminate the rotationally asymmetric free-curved prism lens and to apply a prism lens consisting of a flat surface and a rotationally symmetric curved surface to facilitate the production and performance inspection To provide a single-plate binocular head mounted display optical system.

In addition, another object of the present invention is to enable a single-plate binocular optical system for distributing image light generated from a single display device to both eyes without using a transflective mirror method, which is a general light splitting method, and thus almost no loss of light. It is to provide a single-plate binocular head mounted display optical system to maintain the optical characteristics of the original image as it is, to significantly reduce the product cost.

In addition, another object of the present invention is a single plate binocular head capable of securing an equivalent wide field of view (FOV) and sufficient EYE RELIEF provided by a single plate binocular optical system. The present invention provides a mount display optical system.

In order to achieve the above object, the present invention is located horizontally in the center of both eyes and one display element for exporting the image toward the user's face, and a predetermined distance from the front of the display element relative to the central axis of the display element Two first reflective surfaces that are symmetrically disposed, two second reflective surfaces that are disposed on the left and right sides of the display element symmetrically with respect to the center axis of the display element, and have a reflective surface toward the face of the user, and the display Two prism lenses disposed in front of the left and right eyes in a symmetrical shape with respect to the central axis of the device, and two eyepieces arranged in a symmetrical shape with respect to the central axis of the display device between the prism lens and the user's eyeball. Single plate binocular with lens In the head mounted display optical system, the first reflecting surface comprises rotationally symmetrical aspheric concave mirror-shaped reflecting surfaces, respectively, to transmit the image light generated from the display element to the second reflecting surface, and the second reflecting surface. Is composed of a rotationally symmetric aspherical concave mirror-shaped reflecting surface for transmitting the image light reflected from the first reflecting surface to the left and right prism lens,

The prism lens has a plane of incidence, a first inner reflection plane, and an exit plane sharing a plane with the first inner reflection plane, respectively, in order to transfer the image light reflected from the second reflection plane to the left and right eyepieces, The second inner reflecting surface has a rotationally symmetric aspherical concave surface, and the eyepiece is characterized in that the incidence surface and the exit surface form a convex aspheric shape of rotation symmetry in order to transfer the image light emitted from the prism lens to the eye. .

Further, in the single-plate binocular head mounted display optical system according to the present invention, the first inner reflection surface of the left and right prism lenses is in the direction of the central axis of both eyepieces from the point closest to the central axis with respect to the central axis of the display element. Reflective mirror coating is preferably applied outwardly at least in part up to the point where the vertical extension of the end meets the first inner reflecting surface of the prism lens.

Further, in the single-plate binocular head mounted display optical system according to the present invention, the incidence planes of the left and right eyepieces are inclined by α in the eyeball direction closest to the central axis of the display element with respect to the horizontal axis. It is preferable that (alpha) makes 0 ( < ) <( 5).

Further, in the single plate binocular head mounted display optical system according to the present invention, the α is more preferably 2 °.

Hereinafter, a single plate binocular head mounted display optical system according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

3 is a schematic view of an embodiment of the construction and arrangement of a single-plate binocular head mounted display optical system using a single display element in accordance with the present invention.

As shown in FIG. 3, the single-plate binocular head mounted display optical system according to the present invention includes one display element 30, two first reflecting surfaces 31L and 31R, and two second reflecting surfaces ( 32L, 32R, two prism lenses 33L, 33R, and two eyepieces 34L, 34R.

The display element 30, which represents an image, is positioned horizontally at the midpoints of the left and right eyes so that the image is directed toward the face of the user.

The two first reflecting surfaces 31L and 31R are spaced a predetermined distance from the front surface of the display element 30 so that each of the two first reflecting surfaces 31L and 31R is symmetrically with respect to the center axis of the display element 30 in the opposite direction to the face of the user. It is arrange | positioned so that it may have a slope, Comprising: The right eye 1st reflection surface 31L for transmitting image light to a right eye, and The left eye 1st reflection surface 31R for transmitting image light to a left eye.

The first right reflecting surface 31L for the right eye serves to transmit the image light generated from the display element 30 to the second reflecting surface 32L, which will be described later, and is made of a rotationally symmetric aspheric concave mirror-shaped reflecting surface. The first reflecting surface 31R for the left eye serves to transmit the image light generated from the display element 30 to the second reflecting surface 32R, which will be described later. Is done.

The two second reflecting surfaces 32L and 32R are arranged to have reflecting surfaces toward the user's face, one on each of the left and right sides of the display element 30 in symmetrical directions with respect to the central axis of the display element 30. The right eye second reflecting surface 32L for transmitting video light to the right eye and the left eye second reflecting surface 32R for transmitting video light to the left eye.

The right eye second reflecting surface 32L transmits the image light transmitted from the first eye reflecting surface 31L to the prism lens 33R, which will be described later, and has a rotationally symmetric aspheric concave mirror-shaped reflecting surface. The left eye second reflecting surface 32R serves to transmit the image light transmitted from the first eye reflecting surface 31R to the prism lens 33L, which will be described later. It consists of a mirror-shaped reflective surface.

The two prism lenses 33L and 33R are disposed in front of the left and right eyes each one in a symmetrical shape with respect to the central axis of the display element 30, and a right eye prism for transmitting image light to the right eye. It consists of a lens 33R and a left eye prism 33L for transmitting video light to the left eye.

The right eye prism lens 33R includes an incidence surface 331R, a first reflection surface 332R, a second reflection surface 333R, and an emission surface 332R sharing a surface with the first reflection surface 332R. The incidence surface 331R, the first reflection surface 332R, and the emission surface 332R are planar, and the second reflection surface 333R is composed of a rotationally symmetric aspherical curved surface.

Therefore, when image light is incident on the right eye prism lens 33R, the image light transmitted from the second reflective surface 32L first passes through the incident surface 331R of the right eye prism lens 33R. The light incident on the inside of the 33R is advanced to the first reflective surface 332R, and the image light incident on the first reflective surface 332R does not penetrate the surface when the light has an angle of incidence above the critical angle in the transparent material. According to the characteristic of total reflection, total reflection is made and incident on the second reflective surface 333R, and the image light incident on the second reflective surface 333R again emits a surface 332R which shares a surface with the first reflective surface 332R. The light is directed through the right eyepiece 34R. Similarly, when the image light is incident on the left eye prism lens 33L, the image light transmitted from the second reflecting surface 32R is first totally reflected on the first reflecting surface 332L, and then on the second reflecting surface 333L. The light is reflected and again passes through an exit surface 332L which shares a surface with the first reflection surface 332L, thereby being directed to the left eyepiece 34L.

At this time, the second reflective surfaces 333L and 333R of the left and right prism lenses 33L and 33R are concave-shaped rotationally symmetric aspherical curved surfaces, as described above, and are coated on the outside thereof, and the emission surfaces 332L and 332R are used. ) And the first reflective surfaces 332L and 332R sharing the plane with both eyepieces from the point closest to the central axis of the display element 30 of the first reflective surfaces 332L and 332R as shown in FIG. 4. As shown in FIG. 4, the mirror-coating for reflection may be applied outward to the point where the vertical extension line of the central axis end point of the 34L and 34R meets the first reflective surfaces 332L and 332R. In the case of forming the reflective mirror coating at 332R), it is possible to guide the transmitted light through the same path as the totally reflected light without partially total reflection.

On the other hand, the prism lenses 33L, 33R in the present invention, two of the three surfaces of the lens is a flat surface and the other one is composed of a rotationally symmetric aspherical curved surface as a reference plane and the configuration of the exact shape only by the angle and length of the tangent This is possible. Compared with the conventional prism lens 12 shown in FIG. 1, the conventional prism lens 12 has a configuration in which all three surfaces are curved and at least one rotationally asymmetric free curved surface is used. It is very difficult to set the reference point when manufacturing products or molds. Especially, the free surface of rotation asymmetry has different curvature changes about X, Y, and Z axes. It is very demanding, and in order to perform a performance test on whether it is manufactured properly according to design, it is necessary to scan the whole face and divide all coordinates finely and contrast them. Therefore, if the error occurs, it is difficult to identify the cause and correct it. There is a problem that there is a risk of going through a lot of costs and trial and error.

However, the prism lenses 33L and 33R according to the present invention can not only accurately find a reference point when manufacturing a product or a mold by using the intersection point and the intersection angle of two planes that are planar, but also the value of the curvature data of one line passing through the center point. As the performance test is possible only by comparing with each other, various effects that can omit numerous trial and error according to the product manufacturing can be obtained.

The two eyepieces 34L and 34R, which are the last optical components of the present invention, have one prism lens 33L and 33R and a user's eyeball, respectively, in a symmetrical shape with respect to the central axis of the display element 30. It is arranged between the right eyepiece 34R for transmitting image light to the right eye, and the left eyepiece 34L for transmitting image light to the left eye.

The right eyepiece 34R includes an incidence surface 341R and an outgoing surface 342R of a rotationally symmetric aspherical surface, and the image light incident into the eyepiece 34R through the incidence surface 341R is The exit surface 342R is passed through at a predetermined angle to focus the pupil of the user. In addition, the left eye eyepiece 34L includes an incident surface 341L and an exit surface 342L of a rotationally symmetric aspherical curved surface, and the image light incident into the eyepiece 34L through the incident surface 341L. Passes through the exit surface 342L at a predetermined angle to focus the pupil of the user.

As shown in FIG. 5, the incidence surfaces 341L and 341R of the eyepiece are inclined by α in the eyeball direction with respect to the horizontal axis of the eyepiece so that the image light can converge to the pupil position. Inclining the incident surface by α is for correcting the eccentricity error and may be changed and applied according to changes in the aspherical coefficients of the respective reflectors and the prism lenses 33L and 33R within the following ranges.

0˚ < α < 5˚

At this time, if the α value is out of the above range, the intraocular pupillary distance (IPD, INPPULPILARY DISTANCE) is increased or decreased, which affects the formation of binocular vision. In order to have the performance of, it is preferable that the α value is 2 °.

In the single plate binocular head mounted display optical system according to the present invention having the above configuration, the image light projected from the display element is converged to the pupils of the left and right eyes through the first reflecting surface, the second reflecting surface, the prism lens, and the eyepiece. Since the optical system as described above does not have a means for forcing optical loss like the half mirror used in the conventional single-plate binocular optical system, the brightness of the original image in the user's pupil is not included. It can provide a very bright and clear image at about the same level as.

In addition, considering that the preferred angle of view of the head mounted display (HMD) is greater than or equal to 30 mm diagonal and more than 20 mm in the eye relief, the optical system of the present invention provides a wide viewing angle of 37 mm and an eye relief of 21 mm. It is possible to secure sufficient irelief.

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 single plate binocular head mounted display optical system according to the present invention is required for product development and production by applying a prism lens composed of a plane or a rotationally symmetric curved surface without the rotationally asymmetric free curved prism commonly used in the optical system for a two-plate binocular HMD. It can dramatically reduce time and cost, increasing the likelihood of early product realization, as well as simplifying the performance test of the lens, making it easy to measure and calibrate.

In addition, the single-plate binocular head mounted display optical system according to the present invention occurs in a single display device without using a transflective mirror method, which is a general light splitting method, considering that the display device is the only expensive component among the components of the HMD. As the single plate binocular optical system can be configured to distribute the image light to both eyes, it is possible to significantly reduce the cost of the product by maintaining the optical characteristics of the original image with little loss of light.

In addition, the single-plate binocular head mounted display optical system according to the present invention has a user's pupil distance and display element horizontal to the center of both eyes, compared to the two-plate binocular optical system that builds an independent optical path using two display elements, respectively. Despite the additional constraints of being placed in position, it has the added advantage of providing a wide viewing angle and sufficient irelief on the same level as a two-plate binocular optic system.

Claims (4)

One display element positioned horizontally in the center of both eyes and for displaying an image toward a user's face, and two first vanes arranged symmetrically with respect to the center axis of the display element spaced apart from the front surface of the display element by a predetermined distance. A slope, two second reflection surfaces disposed on left and right sides of the display element symmetrically with respect to the center axis of the display element, and having a reflection surface toward the face of the user, and a shape symmetrically based on the center axis of the display element; Single prism head mount comprising two prism lenses disposed in front of the left and right eyes, and two eyepieces arranged in a symmetrical shape with respect to the central axis of the display element between the prism lens and the user's eyeball. In display optics book, The first reflecting surface is made of a rotationally symmetric aspheric concave mirror-shaped reflecting surface for transmitting the image light generated from the display element to the second reflecting surface, The second reflecting surface is made of a rotationally symmetrical aspherical concave mirror-shaped reflecting surface for transmitting the image light reflected from the first reflecting surface to the left and right prism lens, The prism lens has a plane of incidence, a first inner reflection plane, and an exit plane sharing a plane with the first inner reflection plane, respectively, in order to transfer the image light reflected from the second reflection plane to the left and right eyepieces, The second inner reflecting surface has a rotationally symmetric aspherical concave surface, The eyepiece is a single-plate binocular head mounted display optical system, characterized in that both the entrance surface and the exit surface to form a convex aspheric shape of rotationally symmetric in order to deliver the image light emitted from the prism lens to the eye. The method of claim 1, wherein the first inner reflection surface of the left and right prism lens, A reflecting mirror outwardly at least in part from a point closest to the center axis with respect to the center axis of the display element to a point where a vertical extension line of the end points in the central axis direction of both eyepieces meets a first inner reflection surface of the prism lens; Single plate binocular head mounted display optical system characterized by coating The left and right end portions of the left and right eyepieces close to the central axis of the display element are inclined by α in the eyeball direction with respect to the horizontal axis, and α is 0 ° < α < 5. Single-head binocular head mounted display optical system characterized by forming a °. 4. The single-plate binocular head mounted display optical system according to claim 3, wherein said α is 2 degrees.

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