JP5842298B2 - Transmission head-mounted display optical system - Google Patents

Description

  The present invention relates to a transmissive head-mounted display (HMD) optical system. More specifically, information acquisition can be facilitated even during external activities, large screen viewing is possible while significantly reducing the size and weight, reducing manufacturing costs and significantly reducing product prices. The present invention relates to a transmissive head-mounted display optical system that can perform the above-described operation.

  In general, a head-mounted display (HMD) device focuses image light generated at a position very close to the eyes so that a virtual large screen can be formed far away using a precision optical device. It is an image display device that allows a user to see an enlarged virtual image by forming, and is a closed type that can not see the surrounding environment and can only see the image light emitted from the display element It can be divided into an HMD (See-close HMD) system and a transmissive HMD (See-through HMD) system that can see the ambient light through a window while also allowing the image light emitted from the display element to be seen. FIG. 1 shows an example of a transmissive HMD optical system according to the prior art.

  First, the transmissive HMD shown in FIG. 1 is disclosed in Korean Patent Registration No. 10-0926226, and a display element 10 that diverges image light and a specific polarized light out of the light emitted from the micro display panel. A polarization separator 11 that reflects only the light, a phase delay plate 12 that converts the linearly polarized light reflected by the polarization separator into circularly polarized light or changes the incident circularly polarized light into linearly polarized light, and the phase delay plate 12. A translucent concave reflecting mirror 13 for enlarging the circularly polarized light and sending it to the phase delay plate 12 again; and a light opening / closing switch panel 14 attached to the outer surface of the transflective concave reflecting mirror so that the ambient light can be opened and closed. It consists of the optical system of the HMD device.

  The image light generated by the display element 10 having the above-described configuration is converted into a P wave or 90% of the entire image light in the 90-degree direction by the polarization separator 11 disposed at an inclination of 45 degrees on the display element 10. Only the 50% beam having the S wave property is transmitted or reflected to reach the phase delay plate 12, and the image light linearly polarized by the phase delay plate 12 changes to circularly polarized light and reaches the transflective concave reflector 13. The semi-transparent concave reflecting mirror 13 is reflected by the circularly polarized state having the opposite rotation direction and passes through the phase delay plate 12 and the polarization separator 11 again to reach the user's eyes. The user can view the enlarged video.

  However, according to the above-described conventional technique, the image light generated from the display element 10 passes through the polarization separator 11 and the semi-transmissive concave reflecting mirror 13 and loses 50% of the light amount, and 25% of the initial light amount. Since only 75% is transmitted to both eyes and 75% is lost in the reflection process, it becomes difficult to realize the natural color of the original image light, thereby providing an image with appropriate brightness to the user's eyeball. In order to achieve this, there is a problem that a high-intensity light source must be used separately in consideration of the amount of light lost.

  Further, since the polarization separator 11 is located diagonally in a space until the image magnified by the semi-transmissive concave reflecting mirror 13 reaches both eyes, the viewing angle which is the purpose of a normal head mounted display (FOV) or eye box (Eye Box) has a structural problem to enlarge, in order to expand these, the size and weight of the entire device will increase, the user wears In this case, there is a problem that it becomes a factor of pressure on the entire face and it becomes easy to feel fatigue.

  Accordingly, an object of the present invention to solve the above-described conventional problems is to enable the image light and the external image light to be clearly and simultaneously viewed by minimizing the loss of the image light diverging from the display element. Thus, it is an object of the present invention to provide a transmissive head mounted display optical system that can perform activities such as e-mail and information collection while walking, and can promote more efficient business operations.

  Another object of the present invention is to provide a transmissive head-mounted display optical system capable of viewing a large screen by maximizing the size of a virtual screen while significantly reducing the weight and size. It is in.

  Another object of the present invention is to provide a transmissive head-mounted display optical system that can reduce manufacturing costs by applying a magnification method using a wedge prism to minimize lens processing. is there.

  In order to achieve the above object, a transmissive head mounted display optical system according to the present invention includes a display element, a collimation lens that collimates image light emitted from the display element, and an image that passes through the collimation lens and is aligned in parallel. A first wedge prism provided with a first enlarging means so that light can enter and the image can be enlarged in the horizontal direction, and image light that has passed through the first wedge prism and expanded in the horizontal direction is incident to display an image in the vertical direction. A second wedge prism provided with a second magnifying means so that it can be magnified, image light reflected by the second wedge prism and magnified in the vertical direction, and an external provided to the user through the second wedge prism A third wedge prism having a shape opposite to that of the second wedge prism so as not to distort the image; And wherein the Mukoto.

  Also, the first enlargement means for enlarging the horizontal image provided in the first wedge prism of the transmissive head mounted display optical system according to the present invention forms a lattice structure therein to change the direction of the reflection angle to a desired direction. It is characterized by being a holographic optical element (HOE).

  Also, the first enlargement means for enlarging the horizontal image provided in the first wedge prism of the transmissive head mounted display optical system according to the present invention can change the direction of the reflection angle of the reflection surface to a desired direction. It is a diffractive optical element (DOE) having a sawtooth structure having an inclination angle.

  In addition, the second enlarging means for enlarging the vertical image of the second wedge prism of the transmissive head mounted display optical system according to the present invention forms a lattice structure therein to change the direction of the reflection angle to a desired direction. It is characterized by being a holographic optical element (HOE).

  In addition, the second enlarging means for enlarging the vertical image of the second wedge prism of the transmissive head mounted display optical system according to the present invention is inclined so that the reflection surface can change the direction of the reflection angle to a desired direction. It is a diffractive optical element (DOE) having a sawtooth structure having a corner.

The third wedge prism of the transmissive head-mounted display optical system according to the present invention has an inclined sawtooth shape opposite to that of the second wedge prism when the inclined surface of the second wedge prism is a diffractive optical element (DOE). A feature of the present invention is to provide an optical system that has a surface and is compensated so that a user can view an external image without distortion.

  The transmissive head-mounted display optical system according to the present invention further includes a convex lens between the first wedge prism and the second wedge prism in order to enlarge a viewing angle (FOV).

  In the transmissive head-mounted display optical system according to the present invention, the first wedge prism and the second wedge prism have the same inclination angle, and the ratio of horizontal expansion and vertical expansion of the image light is the same. It is characterized by minimizing distortion.

  In the transmissive head-mounted display optical system according to the present invention, the first magnifying means is characterized in that the reflective surface is a 100% reflective coating surface.

  In the transmissive head mounted display optical system according to the present invention, the second magnifying means is characterized in that the reflecting surface is a 50% half mirror coating surface.

  In the transmission head-mounted display optical system according to the present invention, the first enlargement means is a reflective holographic optical element (HOE).

In the transmissive head-mounted display optical system according to the present invention, the second magnifying means is a reflective holographic optical element (HOE).

  As described above, the transmissive head mounted display optical system according to the present invention minimizes the loss of image light diverging from the display element so that the image light and the external image light can be viewed simultaneously and clearly. In particular, activities such as e-mail and information gathering can be performed, which has the effect of promoting more efficient operations.

  The transmissive head-mounted display optical system according to the present invention has an advantage that a large screen can be viewed by maximizing the size of the virtual screen while significantly reducing the weight and size.

  In addition, the transmissive head-mounted display optical system according to the present invention has an additional advantage that manufacturing costs can be reduced by applying a magnification method using a wedge prism to minimize lens processing.

It is sectional drawing which showed the conventional transmissive | pervious head mounted display optical system schematically. 1 is a perspective view schematically showing a transmissive head mounted display optical system according to the present invention. FIG. FIG. 3 is a schematic diagram schematically illustrating a light path in a three-dimensional light path in the transmissive head mounted display optical system according to the present invention. It is sectional drawing which showed the path | route of the light in a general prism. It is sectional drawing which showed one Example of the image horizontal expansion means installed in the inclined surface of the wedge prism by this invention. It is the conceptual diagram which introduced the operation | movement principle of the reflection type holographic optical element which is one of the image horizontal expansion means installed in the inclined surface of the wedge prism by this invention. It is sectional drawing which showed the diffraction optical element (DOE) which is another Example of the image horizontal expansion means installed in the inclined surface of the wedge prism by this invention. It is sectional drawing for demonstrating the path | route of the light in a general prism. It is sectional drawing which showed one Example of the image | video vertical expansion means installed in the inclined surface of the wedge prism by this invention. It is sectional drawing which showed another Example of the image | video vertical expansion means installed in the inclined surface of the wedge prism by this invention. 4 is a view showing an embodiment of a structure in which a reflector is added in the optical path of the optical system of the transmissive head mounted display according to the present invention. 6 is a view showing another embodiment of a structure in which a magnifying lens is added to an optical path between a first wedge prism and a second wedge prism according to the present invention.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in the drawings, the same components are denoted by the same reference numerals as much as possible. Specific details are set forth in the following description, which is provided to aid in a more general understanding of the invention. In the description of the present invention, if it is determined that a specific description of a related known technique or configuration can unnecessarily obscure the gist of the present invention, a detailed description thereof will be omitted.

  First, FIG. 2 is a diagram schematically showing an embodiment of the configuration and arrangement of a transmissive head-mounted display optical system using a wedge prism according to the present invention. FIG. 3 shows a moving path of image light in three dimensions. It is the displayed outline map.

  The transmissive head-mounted display optical system according to the present invention includes a display element 20, a collimation lens 21, a first wedge prism 22, a second wedge prism 23, and a third wedge prism, as shown in FIGS. 24.

  With the configuration as described above, the transmissive head-mounted display optical system according to the present invention is configured to pass through the collimation lens 21 in which the image light diverging from the display element 20 is positioned in parallel with the display element 20 so that the optical axes thereof coincide with each other. After changing to parallel light, the light enters the first wedge prism 22 and travels in parallel in the horizontal direction, and the size of the image in the horizontal direction by the horizontal direction enlargement means installed on the inclined surface 221 of the first wedge prism 22. After being enlarged, the light is reflected vertically downward and emitted from the first wedge prism 22. Further, the image light reflected vertically below the first wedge prism 22 enters the second wedge prism 23 positioned below the first wedge prism 22, and the vertical direction positioned on the inclined surface 231 of the second wedge prism 23. After the image size is enlarged in the vertical direction by the magnifying means, the image is reflected vertically forward and emitted from the second wedge prism 23, so that the user can move in the horizontal and vertical directions from the size of the first display element. It will be possible to view a greatly enlarged video.

  At this time, in order to minimize the distortion of the image by making the ratio of the image enlargement in the horizontal direction and the image enlargement in the vertical direction the same, the inclination angles of the first wedge prism 22 and the second wedge prism 23 are set. Must be identical.

  Further, the third wedge prism 24 disposed on the rear surface of the second wedge prism 23 has an inclined surface when the vertical expanding means of the second wedge prism 23 is a holographic optical element (HOE). When the vertical magnifying means of the second wedge prism 23 is a diffractive optical element (DOE), it has a sawtooth shape opposite to that of the diffractive optical element of the second wedge prism 23, and the user distorts the external image. Provide a compensated optical system so that it can be seen without.

  FIG. 4A is a schematic diagram of the path of a general image light when the inclined surface of the first wedge prism 22 does not have a horizontal expansion means. According to FIG. Since the angle θ and the reflection angle θ ′ must be the same, the width d of the incident video light and the width d ′ of the reflected video light are the same, so there is no expansion effect.

  FIG. 4 b is a diagram schematically showing the path of image light when the holographic optical element 223 is held as the horizontal expansion means on the inclined surface 221 of the first wedge prism 22, and according to FIG. The image light incident on the inclined surface in the horizontal direction includes a pattern pattern that is input in advance so that a diffraction angle is determined according to the wavelength of the image signal inside the holographic optical element 223. The image light is reflected vertically below the input.

  In order to input a diffraction angle into the holographic optical element 223 in advance, as shown in FIG. 4c, a laser incident beam (Object Beam) is incident horizontally in the opposite direction of the holographic optical element. If the other laser beam (Reference Beam) is irradiated with an inclination angle, it is engraved with a pattern pattern in which a diffraction angle is input in advance in the holographic optical element. After completing the input in this way, if image light having the same wavelength band as the laser beam (Object Beam) used for input is irradiated at the same angle as the laser beam (Reference Beam) used at the time of input, The image light reflects the image light in the opposite direction of the laser incident beam (Object Beam) according to the input pattern, and the light width d of the image light at this time is enlarged to d ′ and reflected. Such theory and test have been scientifically verified and applied in many fields.

  In addition, the holographic optical element can input pattern patterns for each of R, G, and B, which are the three primary colors, using the same lasers. It is also possible to input a pattern pattern by simultaneously irradiating the holographic optical element with an RGB laser, or to make a holographic optical element in which each of the RGB pattern patterns is input and then attach the holographic optical element to the inclined surface by a lamination method. Generally, a photopolymer is used for the holographic optical element.

  FIG. 4d is a diagram schematically showing the path of image light when the first wedge prism has a diffractive optical element 225 as a horizontal expansion means on the inclined surface 221 of 22 according to FIG. 4d. The image light d incident on the inclined surface in the horizontal direction is reflected in an enlarged state as the image light d ′ vertically downward by the sawtooth reflecting surface protruding on the surface of the diffractive optical element 225. At this time, since the interval between the sawtooth structures must be larger than the wavelength of visible light, it must be at least 10 μm, and is 200 μm or less in consideration of the size of the pupil of the human eye. The most ideal sawtooth spacing is between 10 and 50 μm, taking into account that the limit at which diffraction lines can be recognized by the human eye is 50 μm, and the depth is between the spacing of the diffraction grating and the sloped surface. It is determined by a function of the angle and the angle of the diffraction grating surface. The outer surface of the diffractive optical element 225 is 100% reflective mirror-coated so that all the image light reflected inside the second wedge prism 23 can be reflected.

  FIG. 5a is a schematic diagram of the path of a general image light when the inclined surface 231 of the second wedge prism 23 does not have a vertical expansion means, and according to FIG. Since the incident angle θ and the reflection angle θ ′ must be the same, the width d of the incident video light and the width d ′ of the reflected video light are the same and there is no expansion effect.

  FIG. 5b is a diagram schematically showing the path of image light when the holographic optical element 233 is provided as the vertical magnifying means on the inclined surface 231 of the second wedge prism 23, and according to FIG. In accordance with the same principle as presented in 4b, the image light incident on the inclined surface in the vertical direction is input in advance into the holographic optical element 233 so that the angle at which it is diffracted according to the wavelength of the image signal is determined. The reflected pattern is included, and the image light is reflected in front of the input horizontal.

  FIG. 5c is a diagram schematically showing the path of the image light when the inclined surface 231 of the second wedge prism 23 has a diffractive optical element 235 as horizontal expansion means, and according to FIG. According to the same principle as presented in 4d, the image light d incident on the inclined surface in the vertical direction becomes the image light d 'horizontally forward by the sawtooth reflecting surface protruding on the surface of the diffractive optical element 235. Reflects in an enlarged state. The outer surface of the diffractive optical element 235 is half-mirror coated so that both the image light reflected inside the second wedge prism 23 and the image light transmitted from the outside can be seen simultaneously.

  FIG. 6 illustrates the display of the transmissive head-mounted display system shown in FIG. 2 by adding a 45-degree reflector 211 between the collimation lens 21 and the first wedge prism 22. An embodiment in which the element 20 and the collimation lens 211 can be arranged in a spectacle frame is shown.

  With the above-described configuration, the image light diverging from the display element 20 is converted into parallel light through the collimation lens 21 positioned so as to coincide with the optical axis in parallel with the display element, and then the 45 degrees. Then, the image is rotated by 90 degrees and is incident on the inside of the first wedge prism 22, and as described above with reference to FIG. 2, an enlarged image is provided to the user by horizontal and vertical enlargement means.

  7 additionally enlarges horizontal and vertical images between the first wedge prism 22 and the second wedge prism 23 in the transmission head-mounted display system of the present invention presented in FIG. An embodiment in which the viewing angle (FOV) can be further increased by adding a lens 25 having power, which is a possible means, is shown.

  The transmissive head-mounted display optical system according to the present invention having the above-described configuration uses the horizontal direction enlargement means provided by the first wedge prism 22 and the vertical direction enlargement means provided by the second wedge prism 23 to display an image. Can not only minimize the use of lenses for image enlargement, but can also enlarge the image so that a large screen can be viewed despite its thin thickness . Further, by suppressing the use of a means for forcing light loss such as a half mirror to the maximum, it is possible to provide a very bright and clear image of a level almost equivalent to the original image.

  On the other hand, in the detailed description of the present invention, specific embodiments have been described. However, it goes without saying that various modifications can be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be defined only by the embodiments described, but should be defined not only by the claims but also by the equivalents of the claims.

20: display element 21: collimation lens 22: first wedge prism 221: inclined surface 23 of the first wedge prism 23: second wedge prism 231: inclined surface 24 of the second wedge prism 24: third wedge prism

Claims (12)

Display elements,
A collimation lens that collimates image light emanating from the display element;
A first wedge prism having a first enlarging means so that image light aligned in parallel through the collimation lens is incident and the image can be enlarged in the horizontal direction;
A second wedge prism provided with a second enlarging means so that the image light expanded in the horizontal direction through the first wedge prism can enter and the image can be expanded in the vertical direction; and
A third wedge prism having a shape opposite to that of the second wedge prism and disposed on the rear surface of the second wedge prism
Including
A transmissive head-mounted display optical system characterized by providing an optical system compensated so that a user can view an external image without distortion . The first enlarging means for enlarging the horizontal image provided in the first wedge prism,
The transmissive head mounted display optical system according to claim 1, wherein the holographic optical element (HOE) is capable of changing a reflection angle direction to a desired direction by forming a lattice structure therein. The first enlarging means for enlarging a horizontal image provided in the first wedge prism includes:
2. The transmissive head-mounted display optical according to claim 1, wherein the reflection surface is a diffractive optical element (DOE) having a sawtooth structure having an inclination angle so that the direction of the reflection angle can be changed to a desired direction. system. The second magnifying means for magnifying the vertical image of the second wedge prism,
The transmissive head mounted display optical system according to claim 1, wherein the holographic optical element (HOE) is capable of changing a reflection angle direction to a desired direction by forming a lattice structure therein. The second magnifying means for magnifying the vertical image of the second wedge prism,
2. The transmissive head-mounted display optical according to claim 1, wherein the reflection surface is a diffractive optical element (DOE) having a sawtooth structure having an inclination angle so that the direction of the reflection angle can be changed to a desired direction. system. The third wedge prism is
If the inclined surface of the second wedge prisms of the diffractive optical element (DOE), characterized in that it possesses an inclined surface having a second wedge prism opposite sawtooth, transmission head mount according to claim 1 Display optical system.   The transmissive head mounted display optical system according to claim 1, further comprising a convex lens between the first wedge prism and the second wedge prism in order to enlarge a viewing angle (FOV). The inclination angles of the first wedge prism and the second wedge prism are the same,
2. The transmissive head-mounted display optical system according to claim 1, wherein image distortion is minimized by making the ratio of horizontal expansion and vertical expansion of the image light the same. The first expansion means includes
The transmissive head-mounted display optical system according to claim 3, wherein the reflective surface is a 100% reflective coating surface. The second expansion means includes
6. The transmissive head mounted display optical system according to claim 5, wherein the reflecting surface is a 50% half mirror coating surface. The first expansion means includes
The transmissive head-mounted display optical system according to claim 2, which is a reflective holographic optical element (HOE). The second expansion means includes
5. The transmissive head mounted display optical system according to claim 4, wherein the transmissive head mounted display optical system is a reflective holographic optical element (HOE).