JP2006162792A - Optical device, image display device, and head-mounted display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the adhesive strength between transparent base materials 22 and 23 without using a special adhesive even if the area of a junction surface between transparent base materials 22 and 23 is very small. <P>SOLUTION: One transparent base material 22 having an optical element 24 stuck thereto and the other transparent base material 23 are joined with an adhesive 25 so as to interpose the optical element 24 between them, whereby an eyepiece optical system 21 as an optical device is formed. A junction surface of the transparent base material 22 has a plurality of faces 22a, 22b, and 22c having different normal directions, and a junction surface of the transparent base material 23 has a plurality of faces 23a, 23b, and 23c having different normal directions. They are joined so that faces 22a and 23a, faces 22b and 23b, and faces 22c and 23c face each other respectively. The optical element 24 is stuck to, for example, the face 22b. Rough parts 31 and 34 having rugged surfaces are formed on junction faces (for example, faces 22a, 22c, 23a, and 23c) of the transparent base materials 22 and 23. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical device capable of observing an external image through a joint surface of a plurality of transparent substrates, a video display device using the optical device, and a head mount using the video display device It relates to the display.

  Optical elements such as holograms, half mirror coats, and beam splitter layers can be affected by the external environment such as humidity and oxygen if they are embedded in a transparent substrate (sandwiched between two transparent substrates). For example, it is very useful as a combiner for a head-up display or a head-mounted display.

Here, as a means for joining the transparent base materials between which the optical element is sandwiched, a pressure-sensitive adhesive sheet or an adhesive is generally used. For example, in Patent Document 1, in manufacturing a head-up display, a base material on which a hologram optical element is pasted and another base material are joined with an adhesive sheet. For example, in patent document 2, the base material which stuck the some hologram original plate and the other base material are adhere | attached with the adhesive agent.
JP-A-7-234627 JP 2002-40909 A

  However, in the method using an adhesive sheet for bonding between transparent substrates, since the hologram optical element has a thickness, air bubbles easily enter the interface between the hologram optical element and the adhesive sheet. When bubbles enter the interface, the refractive index changes at that location, so that the visibility when observing an external image through the transparent substrate is reduced. Therefore, it is effective to use an adhesive capable of suppressing the mixing of bubbles in joining the transparent substrates.

  On the other hand, when an optical element such as a hologram is used as a combiner for a head-mounted display, for example, the optical element is disposed in front of the observer's eye while being sandwiched between two transparent substrates. For this reason, in order to avoid the danger to the observer by peeling of each transparent base material, it is necessary to raise the joint strength of transparent base materials. That is, in an application using the optical element as a combiner, an overwhelmingly high bonding strength is required, and it is necessary to prevent the bonding strength from being insufficient in actual use. In addition, in applications where the optical element is used as a combiner, the adhesive is required to “not adversely affect the optical element” in addition to the “strong adhesive strength” as described above.

  However, it is practically difficult for the adhesive to satisfy both of these characteristics, and there are not many adhesives that can be used for the above-mentioned applications that require strong adhesive strength. Therefore, the transparent substrates cannot be bonded with high adhesive force without adversely affecting the optical element.

  In particular, a head-mounted display requires a relatively high bonding strength, and the optical element and the transparent substrate are very small compared to a head-up display or a hologram screen embedded in a car windshield. The area is small. For this reason, it has become increasingly difficult to bond transparent substrates with high adhesive strength.

  In addition, there is an optical device (for example, a compound lens) that can observe an external field image through the joint surfaces without arranging optical elements on the joint surfaces of a plurality of transparent substrates. In such an optical device, since there is no optical element on the bonding surface, the adhesive that bonds the transparent substrates to each other does not require the property of “not adversely affecting the optical element”, and “strong adhesion” Only required. However, if the transparent substrates can be bonded with a high adhesive force using an adhesive that can be used in common with these optical devices without using a special adhesive having a strong adhesive force, The range of application of the agent is wide and very useful.

  The present invention has been made to solve the above-described problems, and its purpose is to specialize the adhesive strength between transparent substrates even when the area of the joint surfaces of a plurality of transparent substrates is very small. It is an object of the present invention to provide an optical device that can be made high without using an adhesive, a video display device including the optical device, and a head-mounted display including the video display device.

  In the optical device of the present invention, one of the transparent base materials (also referred to as a first transparent base material) to which the optical element is attached and the other transparent base material (also referred to as a second transparent base material) are the above optical elements. Is an optical device in which an external image is observed through the joint surface (with an adhesive), and an uneven portion having an uneven surface is formed on the joint surface. It is characterized by that.

  According to said structure, a 1st transparent base material and a 2nd transparent base material are joined so that an optical element (for example, hologram) may be pinched | interposed. As described above, the optical element is provided on the joint surface between the first transparent base material and the second transparent base material, so that the optical element can be provided through the joint surface to the observer through the joint surface. An optical device having both functions can be realized.

  Here, the uneven | corrugated | grooved part is formed in the joint surface of a 1st transparent base material and a 2nd transparent base material. The uneven portions may have surface irregularities formed, for example, in a matte shape, may be formed in a stripe shape, or may be formed in a concentric shape. . Moreover, said uneven | corrugated | grooved part may be formed by the convex part being scattered. Moreover, an uneven | corrugated | grooved part may be formed in the joint surface of the 1st transparent base material side, and may be formed in the joint surface of the 2nd transparent base material side. Furthermore, the concavo-convex portion may be formed on the entire bonding surface, or may be formed on a part of the bonding surface.

  By forming the uneven portion on the joint surface in this way, the surface area of the joint surface is significantly increased compared to the case where the joint surface is a mirror surface. Therefore, the bonding strength between the transparent substrates can be increased without using, for example, a special adhesive having a high bonding strength for joining these transparent substrates. As a result, even when the area of the bonding surface is small, the transparent substrates can be bonded with high adhesive strength.

  Moreover, in the optical device, it is possible to observe the outside world image with see-through through the joining surface between the transparent base materials, but when the uneven portion is provided on the joining surface existing in the observation optical path of the outside world image, The refractive index changes at the interface of the concavo-convex portion, which hinders visual recognition of the external image through the joint surface. Therefore, it is difficult to adopt a configuration in which an uneven portion for increasing the adhesive strength is provided on such a joint surface. However, the above problem can be solved, for example, by eliminating the refractive index difference between the transparent substrate and the adhesive as much as possible (matching the refractive indexes of the two members as much as possible). The structure which provides can be employ | adopted.

  Here, the optical element may be a hologram. In this case, since the hologram has wavelength selectivity, an optical device having both diffraction characteristics and transmission characteristics can be realized.

  The optical element may be a half mirror coat. In this case, an optical device having both reflection characteristics and transmission characteristics by a half mirror can be realized.

  Moreover, it is preferable that the uneven portion is formed in a portion other than the region where the optical element is attached on the bonding surface. That is, it is desirable that an uneven portion is formed on the bonding surface of the first transparent base material at a portion excluding the region where the optical element is attached. Note that, in the bonding surface of the second transparent base material, an uneven portion may be formed in any part (for example, an uneven portion may be formed in a region facing the optical element, or a region other than the facing region). An uneven portion may be formed on the surface).

  According to this configuration, when the first transparent substrate and the second transparent substrate are bonded with, for example, an adhesive, the adhesive strength between the transparent substrates with the adhesive can be increased at a portion other than the optical element. In addition, it is possible to avoid an adverse effect on the optical element due to the adhesive (degradation of the performance of the optical element).

  Further, it is desirable that the uneven portion is formed in a portion other than a region facing the optical element on the bonding surface. In this case, since the bonding strength of each transparent substrate is ensured in the region where the concavo-convex portion is formed, that is, in a portion other than the optical element, it is possible to reduce the impact or load of the optical element from being applied. . In addition, when the concavo-convex portion is formed on the optical element, the optical performance of the optical element may deteriorate due to light diffusion in the concavo-convex portion. However, in the above configuration, the concavo-convex portion is not formed on the optical element. Therefore, it is possible to avoid the performance degradation of the optical element.

  In addition, it is desirable that the joining surface includes a plurality of surfaces having different normal directions. In the case of this configuration, when the transparent base materials are joined together with, for example, an adhesive, the adhesive force of the adhesive acts on the joint surfaces in different directions between the plurality of surfaces. Thereby, the adhesive strength of transparent base materials can be made still higher.

  Moreover, it is desirable that the area of the region where the concavo-convex part is formed is 10% or more of the entire area of the joint surface in the transparent substrate on which the concavo-convex part is formed. In this case, high adhesive strength between the transparent substrates can be ensured at a minimum.

  The area of the region where the optical element is attached is desirably 90% or less of the entire area of the bonding surface of the transparent substrate to which the optical element is attached. In this case, since the part other than the region where the optical element is attached is surely left in the bonding surface, high adhesive strength between the transparent substrates can be secured at the part.

  Moreover, the said uneven | corrugated | grooved part has the desirable structure formed in the satin shape. In this case, compared with the case where the uneven portions are formed in, for example, a stripe shape, the surface area of the uneven portions can be reliably increased, and the adhesive strength between the transparent substrates can be reliably increased.

  Moreover, the said each transparent base material has the desirable structure joined via the adhesive agent in the said joint surface. With this configuration, the transparent substrates can be bonded to each other without mixing bubbles on the bonding surfaces of the transparent substrates.

  At this time, the adhesive is preferably an ultraviolet curable adhesive. Since the ultraviolet curable adhesive has a small shrinkage rate, deformation and damage of the transparent substrate and the optical element can be suppressed as much as possible. Moreover, since heat is not required at the time of curing unlike a thermosetting adhesive, it is particularly advantageous when the transparent base material is made of, for example, plastic (deformation of the base material due to heat can be suppressed). Furthermore, since the ultraviolet curable adhesive does not contain a solvent, the adverse effect on the optical element is small.

  Here, it is desirable that the difference between the refractive index of the transparent base material on which the uneven portions are formed on the joint surface and the refractive index of the adhesive is 0.02 or less. In this case, almost no change in the refractive index at the interface between the transparent substrate and the adhesive can be eliminated. As a result, when an external image is observed through the joint surface with see-through, it is possible to suppress distortion of the external image and to ensure good see-through performance.

  In addition, it is desirable that each of the transparent substrates, the optical element, and the adhesive is made of an acrylic material. In the case of this structure, the adhesiveness of each transparent base material, an optical element, and an adhesive agent can be improved.

  The optical device of the present invention is an optical device in which an external image is observed through through the joint surfaces of a plurality of transparent base materials, and the joint surface has an uneven portion with an uneven surface. It is characterized by that.

  According to said structure, the uneven | corrugated | grooved part is formed in the joint surface of a some transparent base material. The uneven portions may have surface irregularities formed, for example, in a matte shape, may be formed in a stripe shape, or may be formed in a concentric shape. . Moreover, said uneven | corrugated | grooved part may be formed by the convex part being scattered. Moreover, an uneven | corrugated | grooved part may be formed in the joint surface of each transparent base material, and may be formed in the joint surface of one transparent base material. Furthermore, the concavo-convex portion may be formed on the entire bonding surface, or may be formed on a part of the bonding surface.

  By forming the uneven portion on the joint surface in this way, the surface area of the joint surface is significantly increased compared to the case where the joint surface is a mirror surface. Therefore, the bonding strength between the transparent substrates can be increased without using, for example, a special adhesive having a high bonding strength for joining these transparent substrates. As a result, even when the area of the bonding surface is small, the transparent substrates can be bonded with high adhesive strength.

  Moreover, in the optical device, it is possible to observe the outside world image with see-through through the joining surface between the transparent base materials, but when the uneven portion is provided on the joining surface existing in the observation optical path of the outside world image, The refractive index changes at the interface of the concavo-convex portion, which hinders visual recognition of the external image through the joint surface. Therefore, it is difficult to adopt a configuration in which an uneven portion for increasing the adhesive strength is provided on such a joint surface. However, the above problem can be solved, for example, by eliminating the refractive index difference between the transparent substrate and the adhesive as much as possible (matching the refractive indexes of the two members as much as possible). The structure which provides can be employ | adopted.

  In addition, since the adhesive strength between the transparent base materials by the adhesive can be increased by forming the concavo-convex portion on the joining surface, a special adhesive having a high adhesive strength is not used for the adhesion between the transparent base materials. You can do it. Therefore, the adhesive used for the optical device which has arrange | positioned the optical element to the bonding surface of a some transparent base material can also be used for adhesion | attachment of transparent base materials, for example, and the application range of the said adhesive agent can be expanded.

  An image display apparatus according to the present invention includes the above-described optical device according to the present invention and an image display element that displays an image and provides the image to the optical device. With this configuration, the observer can observe the image provided from the image display element through the optical device, and at the same time, can also observe the outside world image through the optical device.

  At this time, it is desirable that the optical element of the optical device is a volume phase type reflection hologram. In this case, by reflecting the image light provided from the image display element in the direction of the observer with the hologram, the observer can observe a virtual image. Moreover, since the volume phase reflection hologram has a high light transmittance of the external image, the observer can clearly observe the external image.

  Further, the optical element of the optical device may be a combiner that simultaneously guides an image provided from the image display element and an external image to the eyes of an observer. In this case, the observer can simultaneously observe the image provided from the image display element and the external image via the optical element.

  The optical device may constitute an eyepiece optical system that enlarges an image displayed on the image display element and guides the image as a virtual image to an observer. In this case, the observer can sufficiently visually recognize the video displayed on the video display element as a virtual image. In addition, the eyepiece optical system provides the viewer with the display image of the image display element as an enlarged virtual image, so the optical device constituting the eyepiece optical system can be made smaller and lighter, and the image display device can be made smaller and lighter. Can be realized.

  The eyepiece optical system preferably has non-axisymmetric (positive) optical power. In this case, even if the eyepiece optical system is downsized, it is possible to provide an observer with an image that has been favorably corrected for aberrations.

  The transparent base material of the optical device preferably has a configuration in which video light provided from the video display element is totally reflected inside and guided to the optical element. According to this configuration, it is possible to provide a bright image to the observer by using the image light provided from the image display element without waste. In addition, it is possible to dispose the image display element at a position away from the optical device, and a wide field of view of the observer with respect to the outside world can be secured.

  The transmittance of the optical element of the optical device is preferably 10% or more. In this case, the observer can sufficiently observe the external image through the see-through even through the optical element.

  A head-mounted display according to the present invention includes the above-described video display device and support means for supporting the video display device in front of an observer's eyes. According to this configuration, since the video display device is supported in front of the observer's eyes by the support means, the observer becomes hands-free and vacant while observing the external image and the display image on the video display element as a virtual image. A desired operation can be performed by hand. In addition, since the observation direction of the observer is determined in one direction, there is an advantage that the observer can easily search for a display image even in a dark environment.

  According to the present invention, since the uneven portion is formed on the joint surface of the transparent substrate, the surface area of the joint surface is significantly increased as compared to the case where the joint surface is a mirror surface. Therefore, the bonding strength between the transparent substrates can be increased without using, for example, a special adhesive having a high bonding strength for joining these transparent substrates. As a result, even when the area of the bonding surface is small, the transparent substrates can be bonded with high adhesive strength.

An embodiment of the present invention will be described below with reference to the drawings.
2A is a plan view showing a schematic configuration of a head mounted display (hereinafter abbreviated as HMD) according to the present embodiment, and FIG. 2B is a side view of the HMD. (C) is a front view of HMD. The HMD has an image display device 1 and a support means 2 that supports the image display device 1, and as a whole has an appearance in which one lens (for example, for the left eye) is removed from general glasses.

  The video display device 1 allows an observer to observe an outside world image with see-through, displays an image, and provides it to the observer as a virtual image. In the video display device 1 shown in FIG. 2C, the portion corresponding to the right eye lens of the glasses is configured by bonding two transparent base materials 22 and 23 (see FIG. 4) described later. The detailed configuration of the video display device 1 will be described later.

  The support unit 2 supports the video display device 1 in front of the observer's eyes (for example, in front of the right eye), and includes a bridge 3, a frame 4, a temple 5, a nose pad 6, and a cable 7. ing. The frame 4, the temple 5 and the nose pad 6 are provided as a pair on the left and right sides. However, when these are distinguished from each other, the right frame 4R, the left frame 4L, the right temple 5R, the left temple 5L, and the right nose pad 6R. The left nose pad 6L is expressed.

  One end of the video display device 1 is supported by the bridge 3. The bridge 3 supports the left frame 4 </ b> L and the nose pad 6 in addition to the video display device 1. The left frame 4L supports the left temple 5L so as to be rotatable. On the other hand, the other end of the video display device 1 is supported by the right frame 4R. An end of the right frame 4R opposite to the support side of the video display device 1 supports the right temple 5R so as to be rotatable. The cable 7 is a wiring for supplying an external signal (for example, a video signal and a control signal) and power to the video display device 1 and is provided along the right frame 4R and the right temple 5R.

  When the observer uses the HMD, the right temple 5R and the left temple 5L are brought into contact with the right and left heads of the observer, and the nose pad 6 is put on the nose of the observer so as to wear general glasses. The HMD is attached to the observer's head. In this state, when an image is displayed on the image display device 1, the observer can observe the image on the image display device 1 as a virtual image, and also observes the outside world image through the image display device 1 in a see-through manner. be able to.

  The HMD is not limited to the one provided with only one video display device 1. For example, FIG. 3A is a plan view showing another configuration of the HMD, FIG. 3B is a side view of the HMD, and FIG. 3C is a front view of the HMD. . As shown in these drawings, the HMD may be configured to include two video display devices 1 arranged in front of both eyes of the observer. In this case, the video display device 1 arranged in front of the left eye is supported between the bridge 3 and the left frame 4L. The cable 7 is connected to both the video display apparatuses 1, and an external signal or the like is supplied to both the video display apparatuses 1 through the cable 7.

Next, details of the above-described video display device 1 will be described.
FIG. 4 is a cross-sectional view illustrating a schematic configuration of the video display device 1. The video display device 1 includes a video display element 11 and an eyepiece optical system 21.

  The video display element 11 includes a light source 12, a unidirectional diffuser plate 13, a condenser lens 14, and an LCD 15. The light source 12, the unidirectional diffuser plate 13, and the condenser lens 14 constitute an illumination optical system that illuminates the LCD 15.

  The light source 12 is composed of an RGB-integrated LED that emits light in three wavelength bands whose central wavelengths are, for example, 465 nm, 520 nm, and 635 nm. The light source 12 may be a white light source that emits white light.

  The unidirectional diffuser plate 13 diffuses the illumination light from the light source 12, but the degree of diffusion differs depending on the direction. More specifically, the unidirectional diffuser plate 13 diffuses incident light by about 40 ° in the direction corresponding to the left and right direction when the HMD is worn by the observer (direction perpendicular to the paper surface of FIG. 4). Is diffused by about 2 ° in the up-and-down direction (direction parallel to the paper surface of FIG. 4) when the observer wears.

  The condensing lens 14 condenses the light diffused by the unidirectional diffusion plate 13. The condenser lens 14 is disposed so that the diffused light efficiently forms the optical pupil E. The LCD 15 is display means for displaying an image by modulating incident light based on the image signal.

  On the other hand, the eyepiece optical system 21 has two transparent base materials 22 and 23 and an optical element 24. This eyepiece optical system 21 constitutes an optical device in which an external image is observed through through the joint surfaces of the transparent base materials 22 and 23, and enlarges and observes an image displayed on the image display element 11. This constitutes an optical device that guides the person's eyes as a virtual image. Further, the eyepiece optical system 21 has a non-axisymmetric positive optical power, and the image light incident on the inside is favorably corrected for aberration.

  The transparent base materials 22 and 23 are made of, for example, an acrylic resin, and are bonded with an adhesive 25 (see, for example, FIG. 1A). The transparent base material 22 at this time is formed in a shape in which the lower end portion of the parallel plate is thinned toward the lower end so as to be wedge-shaped, and the upper end portion thereof is thickened toward the upper end. The transparent base material 23 is configured to be a substantially parallel flat plate integrated with the transparent base material 22 by forming the upper end portion of the parallel flat plate along the lower end portion of the transparent base material 22.

  For example, when the transparent base material 23 is not bonded to the transparent base material 22, the external world image is refracted when passing through the wedge-shaped lower end portion of the transparent base material 22, so that the external environment observed through the transparent base material 22 is used. The image is distorted. However, by joining the transparent base material 23 to the transparent base material 22 to form an integral substantially parallel flat plate, the refraction when the light of the external image passes through the wedge-shaped lower end portion of the transparent base material 22 is reduced. The material 23 can be canceled. As a result, it is possible to prevent distortion in the external image observed through the see-through.

  The optical element 24 is configured by a volume phase type reflection hologram that diffracts light in three wavelength bands, for example, 465 ± 10 nm, 520 ± 10 nm, and 635 ± 10 nm, which are incident at a specific incident angle. The optical element 24 is affixed to the inclined surface at the lower end of the transparent base material 22, and as a result, is sandwiched between the transparent base materials 22 and 23. The transmittance of the optical element 24 is set to 10% or more.

  Here, the volume phase type reflection hologram includes, for example, a process of attaching a photosensitive material such as a photopolymer on the transparent substrate 22, a process of exposing the photosensitive material with a laser beam, a fixing process by ultraviolet irradiation, and a baking process. It is formed through a bonding process by ultraviolet irradiation. In addition, as the optical element 24, an optical film having reflection / transmission characteristics may be pasted on the transparent substrate 22, or a half mirror coat in which an inorganic material is coated on the bonding surface of the transparent substrate 22 by vapor deposition or the like. It may be.

  With such a configuration of the video display device 1, the light emitted from the light source 12 of the video display element 11 is diffused by the unidirectional diffusion plate 13, condensed by the condenser lens 14, and enters the LCD 15. The light incident on the LCD 15 is modulated based on the video signal and emitted as video light. At this time, the image itself is displayed on the LCD 15.

  The image light from the LCD 15 enters the inside of the transparent base material 22 of the eyepiece optical system 21 from its upper end surface, is totally reflected a plurality of times by two opposing surfaces, and enters the optical element 24. The light incident on the optical element 24 is reflected and reaches the optical pupil E. At the position of the optical pupil E, the observer can observe an enlarged virtual image of the image displayed on the LCD 15. The distance from the optical pupil E to the virtual image is about several meters, and the size of the virtual image is 10 times or more that of the image displayed on the LCD 15.

  On the other hand, since the transparent base materials 22 and 23 and the optical element 24 transmit almost all the light from the outside, the observer can observe the outside world image. Therefore, the virtual image of the image displayed on the LCD 15 is observed while overlapping with a part of the external image. From the above, it can be said that the optical element 24 functions as a combiner that simultaneously guides the image provided from the image display element 11 and the external image to the eyes of the observer.

  As described above, the video display device 1 is configured to guide the video light emitted from the LCD 15 to the optical element 24 by total reflection in the transparent substrate 22. Thereby, the video display element 11 can be disposed at a position far away from immediately before the eyes of the observer, and a wide field of view for the outside of the observer can be secured. Moreover, the thickness of the transparent substrates 22 and 23 can be set to about 3 mm as in the case of a normal spectacle lens, and the video display device 1 can be reduced in size and weight.

  Further, since the optical element 24 diffracts only the light having the specific incident angle and the specific wavelength as described above, the optical element 24 does not affect the light of the external image transmitted through the transparent base materials 22 and 23 and the optical element 24. Therefore, the observer can observe the external image as usual through the transparent base materials 22 and 23 and the optical element 24. Further, since the transmittance of the optical element 24 is set to 10% or more, the observer can sufficiently observe the external field image through the transparent base materials 22 and 23 and the optical element 24.

Next, the joint part of the transparent base materials 22 and 23 will be described.
FIG. 5A shows a plan view of the transparent substrate 22 (first transparent substrate), and FIG. 5B shows a front view of the transparent substrate 22. FIG. 5C shows a plan view of the transparent base material 23 (second transparent base material), and FIG. 5D shows a front view of the transparent base material 23. Furthermore, FIG.5 (e) has shown the top view of the eyepiece optical system 21 to which the transparent base materials 22 * 23 were joined.

  The transparent base material 22 has a substantially quadrangular pyramid shape as a whole, and its upper surface and lower surface are connected by four side surfaces. These four side surfaces are configured by surfaces 22a, 22b, 22c, and 22d arranged counterclockwise around the upper surface in the plan view of FIG. These surfaces 22a, 22b, 22c, and 22d have mutually different normal directions. Further, a protruding portion 22e protruding upward from the upper surface is formed on one side surface (for example, the surface 22d) of these. The optical element 24 is attached to, for example, the surface 22b of the transparent substrate 22.

  On the other hand, the transparent base material 23 has such a shape that a parallel flat plate is formed by joining the transparent base material 22. That is, the transparent base material 23 has a shape obtained by cutting out the shape of the transparent base material 22 from a parallel plate. Here, in the transparent base material 23, the surfaces facing the surfaces 22a, 22b, and 22c of the transparent base material 22 when bonded to the transparent base material 22 are referred to as 23a, 23b, and 23c, respectively. The normal directions of these surfaces 23a, 23b, and 23c are different from each other.

  By joining the other transparent base material 23 to the one transparent base material 22 to which the optical element 24 is attached in this way via an adhesive 25 (see FIG. 1B) so as to sandwich the optical element 24. As shown in FIG. 5E, an eyepiece optical system 21 is formed. The eyepiece optical system 21 is shaped like a spectacle lens in plan view. By using this eyepiece optical system 21, it is possible to observe an external image through the see-through through the joint surfaces (surfaces 22a, 22b, and 22c, surfaces 23a, 23b, and 23c) of the transparent base materials 22 and 23. .

  Here, FIG. 1A is a cross-sectional view of a part of the eyepiece optical system 21, and FIG. 1B is a cross-sectional view of the other part of the eyepiece optical system 21. In the present embodiment, uneven portions 31 and 32 having uneven surfaces are formed on the joint surfaces of the transparent base materials 22 and 23, respectively. More specifically, as shown in FIG. 1A, the concavo-convex portion 31 is formed on the surfaces 22 a and 22 c excluding the surface 22 b to which the optical element 24 is attached, among the bonding surfaces of the transparent base material 22. . Moreover, the uneven | corrugated | grooved part 32 is formed in surface 23a * 23c except the surface 23b which opposes the surface 22b to which the optical element 24 is affixed among the joint surfaces of the transparent base material 23. FIG. On the other hand, as shown in FIG.1 (b), the surface 22b of the transparent base material 22 and the surface 23b of the transparent base material 23 are mirror surfaces.

  In this embodiment, the uneven portions 31 and 32 are formed in a satin shape in plan view. The uneven portions 31 and 32 are formed at the same time when the transparent base materials 22 and 23 are molded by a mold, for example. In addition, as long as the surface is uneven, the uneven portions 31 and 32 may be formed in any shape. Therefore, as the concavo-convex portions 31 and 32, various forms such as a stripe shape, a lattice shape, a concentric circle shape, and a shape in which convex portions are scattered can be assumed in addition to the satin shape.

  As described above, since the uneven portions 31 and 32 are formed on the joint surface of the transparent base materials 22 and 23, the surface area of the joint surface is significantly increased as compared with the case where the joint surface is a mirror surface. Therefore, the adhesive strength between the transparent base materials 22 and 23 can be increased without using, for example, a special adhesive having a high adhesive strength as the adhesive 25. In particular, in the HMD as in the present embodiment, the optical element 24 and the transparent base materials 22 and 23 are very small and the bonding area thereof is small, but even in such a case, the transparent base materials 22 and 23 are used. They can be joined with high adhesive strength.

  Further, the concave / convex portion 31 or the concave / convex portion 32 may be formed on one of the facing joint surfaces of the transparent base materials 22 and 23, and the other may remain a mirror surface. By forming the concavo-convex portion 31 or the concavo-convex portion 32 on both of the facing joint surfaces of the materials 22 and 23 (surface 22a and surface 23a, surface 22c and surface 23c), the transparent base materials 22 and 23 formed by the adhesive 25 It is possible to reliably increase the bonding strength.

  Moreover, since the uneven | corrugated | grooved part 31 * 32 is formed in site | parts other than the area | region where the optical element 24 is affixed among the joining surfaces of the transparent base materials 22 * 23, it is an adhesive agent in parts other than the optical element 24. While the adhesive strength between the transparent substrates 22 and 23 by 25 is increased, adverse effects on the optical element 24 by the adhesive 25 (degradation of optical element performance such as a change in refractive index) can be avoided.

  Moreover, in this embodiment, the uneven | corrugated | grooved part 32 formed in the transparent base material 23 is formed in site | parts other than the area | region facing the optical element 24 on the transparent base material 22 among the joint surfaces with the transparent base material 22. FIG. ing. That is, in the surface 23b facing the surface 22b of the transparent base material 22 to which the optical element 24 is attached, the uneven portion 32 is not formed in the region facing the optical element 24.

  With such a configuration, the bonding strength of the transparent base materials 22 and 23 is ensured at portions other than the optical element 24. As a result, it is possible to reduce the impact and load on the optical element 24. The uneven portion 32 has a property of diffusing light. If the uneven portion 32 is formed on the optical element 24, the optical performance of the optical element 24 may not be fully exhibited. However, in this embodiment, since the uneven portion 32 is not formed on the optical element 24, it is possible to avoid the performance degradation of the optical element 24.

  By the way, in this embodiment, in the transparent base material 22, although the uneven | corrugated | grooved part 31 is formed only in the surface 22a * 22c and is not formed in the surface 22b to which the optical element 24 is affixed, FIG. As shown to c), you may form in site | parts other than the area | region where the optical element 24 is affixed among the surfaces 22b. In this case, compared with the case where the uneven portion 31 is provided only on the surfaces 22a and 22c, the adhesive strength between the transparent base materials 22 and 23 by the adhesive 25 can be further increased at portions other than the optical element 24. Further, in addition to this configuration, as shown in FIG. 1 (d), if the uneven portion 32 is formed on the surface 23 b of the transparent substrate 23 in a region other than the region facing the optical element 24, the transparent substrate The bonding strength between 22 and 23 can be further increased.

  Moreover, as shown in FIG.1 (e), you may form the uneven | corrugated | grooved part 32 in the whole surface 23b of the transparent base material 23 in addition to the structure of FIG.1 (c). In this case, the bonding strength between the transparent base materials 22 and 23 can be further increased. In this configuration, since the concavo-convex portion 32 exists on the optical element 24, there is a concern that the optical performance of the optical element 24 is deteriorated as described above. However, the adhesive 25 on the concavo-convex portion 32 and the optical element 24 If the refractive index difference is made small, almost no change in refractive index at the interface of the concavo-convex portion 32 can be eliminated. Therefore, it is considered that the performance degradation of the optical element 24 can be suppressed by taking such measures.

  From the above, as a result, the concavo-convex portion 31 only needs to be formed in a portion of the transparent base material 22 other than the region where the optical element 24 is pasted in the entire bonding surface. It can be said that it may be formed anywhere on the 23 joining surfaces. Moreover, it can be said that the uneven part (uneven part 31 * 32) is formed in a part of all the joint surfaces of the transparent base materials 22 * 23.

  Moreover, in this embodiment, the joint surface of the transparent base material 22 contains the several surface (surface 22a * 22b * 22c) from which a normal line direction differs, and the joint surface of the transparent base material 23 is a normal line direction. A plurality of different surfaces (surfaces 23a, 23b, and 23c) are included. Thereby, the adhesive force of the adhesive agent 25 acts on the surfaces 22a, 22b, and 22c of the transparent base material 22 in different directions. Similarly, in the transparent substrate 23, the adhesive force of the adhesive 25 acts on the surfaces 23a, 23b, and 23c in different directions. As a result, the adhesive strength between the transparent base materials 22 and 23 can be further increased to be stronger against breakage.

  Moreover, when the joint surface of the transparent base materials 22 and 23 includes a plurality of surfaces having different normal directions in this way, the surface 22b to which the optical element 24 is attached is normal as in the present embodiment. If the concave and convex portions 31 and 32 are provided on the surfaces having different directions (for example, the surfaces 22a and 22c or the surfaces 23a and 23c), the bonding strength of the transparent base materials 22 and 23 can be dramatically increased.

  Moreover, it is desirable that the area of the region where the uneven portion 31 is formed on the bonding surface (surfaces 22a, 22b, and 22c) of the transparent base material 22 is 10% or more of the entire area of the bonding surface of the transparent base material 22. . Similarly, the area of the region where the concavo-convex portion 32 is formed on the bonding surface (surfaces 23 a, 23 b, and 23 c) of the transparent base material 23 is 10% or more of the entire area of the bonding surface of the transparent base material 23. desirable.

  When the area of the formation area of the concavo-convex parts 31 and 32 is less than 10% of the total area of the joint surfaces of the respective transparent base materials 22 and 23, the bonding force is improved by forming the concavo-convex parts 31 and 32 because the area is too small. The effect of is small. However, if the area of the formation region of the concavo-convex portions 31 and 32 is 10% or more of the total area of the joint surface, high adhesive strength between the transparent base materials 22 and 23 can be ensured at a minimum.

  In addition, the area of the region where the optical element 24 is affixed on the bonding surface of the transparent base material 22 is desirably 90% or less of the total area of the bonding surface of the transparent base material 22. If an adhesive that does not degrade the optical element 24 is selected as the adhesive 25, the adhesive strength is generally weakened. Therefore, it is desirable to ensure the adhesive strength outside the area where the optical element 24 is attached. For this purpose, the area of the region where the optical element 24 is affixed is 90% or less of the total area of the bonding surface, that is, the portion of the bonding surface other than the region where the optical element 24 is affixed. It is desirable to secure 10% or more of the total area of the joint surface.

  In this embodiment, an ultraviolet curable adhesive is used as the adhesive 25 used for joining the transparent base materials 22 and 23. In general, since the ultraviolet curable adhesive does not contain a solvent and has a small shrinkage rate, damage to the optical element 24 is very small. In addition, since the ultraviolet curable adhesive does not require heat during curing unlike the thermosetting adhesive, it is particularly advantageous when the transparent substrates 22 and 23 are made of plastic, for example.

  Moreover, when the transparent base materials 22 and 23 are joined with the adhesive 25 as in this embodiment, the difference between the refractive index of the transparent base materials 22 and 23 and the refractive index of the adhesive 25 is 0.02 or less. It is desirable to be. As a combination of the transparent base materials 22 and 23 and the adhesive 25 satisfying such conditions, for example, Mitsubishi Rayon acripet (refractive index 1.49) and Toagosei LCR0628A (refractive index 1.50). )

  In general, when the concave and convex portions 31 and 32 are formed on the joint surface, light is diffused by the concave and convex portions 31 and 32, which causes a problem when an external image is viewed through the joint surface. However, the difference between the refractive index of the transparent base materials 22 and 23 and the refractive index of the adhesive 25 is set to 0.02 or less, and the refractive index of the adhesive 25 used for bonding is changed to the transparent base provided with the uneven portions 31 and 32. By making the refractive index of the materials 22 and 23 as close as possible, light refraction and scattering at the interface between the adhesive 25 and the transparent base material 22 and 23 are reduced, and the observer can view the external image without any problem through the joint. Visual recognition is possible.

  By the way, as the transparent base materials 22 and 23, an acrylic material excellent in transparency and moldability is used, and as the optical element 24 made of a hologram, an acrylic material (acrylate derivative) showing an excellent refractive index change is used. It is desirable to use a photopolymer. Therefore, when the transparent base materials 22 and 23 and the optical element 24 are made of such a material to produce an optical device, an acrylic material (acrylate derivative) is used as the adhesive 25 for joining the transparent base materials 22 and 23. ) Is desirable.

  More specifically, as the material of the transparent base materials 22 and 23, for example, a material containing a methacrylic resin (for example, an acrypet manufactured by Mitsubishi Rayon, a Delpet manufactured by Asahi Kasei Corporation) can be used. As the material (photosensitive material) of the optical element 24, for example, a material containing polymethyl methacrylate, phenoxyethyl acrylate, or chlorophenyl acrylate (for example, OmniDex manufactured by DuPont) can be used. In this case, the adhesive 25 includes, for example, an acrylic modified oligomer (for example, LCR0628A from Toagosei Co., Ltd.), a tetrahydrofuruyl methacrylate (for example, NOA68 from Norland Optical), tetrahydrofuruyl methacrylate, substituted ethyl acrylate, Those containing a substituted urethane acrylate (for example, NOA76 from Norland Optical) can be used.

  Generally, the same kind of material is stronger than the dissimilar material in terms of adhesion (adhesive force) of the material. Therefore, in the case where an acrylic material is used for both the optical element 24 (photosensitive material) and the transparent base materials 22 and 23, it is inevitably bonded that the adhesive 25 also uses an acrylic material. It becomes possible.

  By the way, in this embodiment, although the joint surface of each transparent base material 22 and 23 demonstrated the structure containing several surface (surface 22a * 22b * 22c, surface 23a * 23b * 23c) from which a normal line direction differs. The bonding surface may be only one surface.

  For example, FIG. 6A is a plan view showing another configuration example of the transparent base material 22, and FIG. 6B is a plan view showing another configuration example of the transparent base material 23. (C) is a top view which shows the other structural example of the eyepiece optical system 21 to which the transparent base materials 22 and 23 were joined. The bonding surface of the transparent substrate 22 is only one surface 22f, and the bonding surface of the transparent substrate 23 is only one surface 23f. And the transparent base materials 22 and 23 are joined via an adhesive so that the surface 22f and the surface 23f face each other, and thereby the eyepiece optical system 21 is configured.

As described above, in the configuration in which there is only one bonding surface in each of the transparent base materials 22 and 23, as shown in FIGS. 6A and 6B, the surface 22f of the transparent base material 22 to which the optical element 24 is attached. was a mirror, in the surface 23f of the transparent substrate 23, while the region 23f ₁ including a portion facing the optical element 24 and mirror, uneven portions on the remaining region 23f ₂ surface 23f (region excluding the region 23f ₁₎ 32 may be formed.

  Further, although not shown in the figure, on the surface 22f of the transparent base material 22, the uneven portion 31 is formed in a region where the optical element 24 is not provided, and the uneven portion 32 is formed on the entire surface 23f of the transparent base material 23. Also good. In addition, the configuration of the eyepiece optical system 21 described with reference to FIGS. 1A to 1E may be applied to the eyepiece optical system 21 of FIG. Of course, even in a configuration having only one joint surface, the effect of the present invention can be obtained by providing the concave and convex portions 31 and 32 on the joint surface.

  Moreover, although this embodiment demonstrated the structure which arrange | positions the optical element 24 in the joint surface of the transparent base materials 22 * 23, the structure which provides the uneven | corrugated | grooved part 31 * 32 in the said joint surface is the optical element 24 in the said joint surface. Of course, the present invention can also be applied to a configuration in which the transparent base materials 22 and 23 are simply bonded to each other without using the adhesive. For example, the present invention can be applied to a composite lens in which two transparent base materials made of different materials are bonded together with an adhesive. In this case, the above-described compound lens is an optical device in which an external image is seen through through the joint surfaces of a plurality of transparent base materials, and an uneven portion having an uneven surface is formed on the joint surface. It can be expressed as an optical device.

  Even in such a compound lens, the surface area of the joint surface is greatly increased by forming the concavo-convex portion on the joint surface of a plurality of transparent base materials, compared to the case where the joint surface is a mirror surface. Even when the area is small, it is possible to obtain the same effect as that of the present embodiment, such that the transparent substrates can be bonded with high adhesive strength without using a special adhesive having high adhesive strength. Furthermore, since it is not necessary to use a special adhesive having a high adhesive strength for joining the transparent substrates, for example, the transparent substrates are bonded to each other using the adhesive 25 used in the optical device of the present embodiment. The application range of the adhesive 25 can also be expanded.

  In addition, although this embodiment demonstrated the case where the joint surface of transparent base materials 22 and 23 was a plane, it is not necessarily limited to this, For example, a curved surface may be sufficient.

  In the present embodiment, the example in which the video display device 1 is applied to the HMD has been described. However, for example, the video display device 1 may be applied to a head-up display.

  In the present embodiment, as the transparent base materials 22 and 23, those on a flat plate are used, but they may have a curvature. In this case, the eyepiece optical system 21 can have a function as a correction spectacle lens.

(A) is sectional drawing of a part of eyepiece optical system of the video display apparatus used for the head mounted display which concerns on one Embodiment of this invention, (b) is another part of the said eyepiece optical system. It is sectional drawing, (c) is sectional drawing which shows the other structure of the said eyepiece optical system. (A) is a top view which shows the schematic structure of the said head mounted display, (b) is a side view of the said head mounted display, (c) is a front view of the said head mounted display. (A) is a top view which shows the other structure of the said head mounted display, (b) is a side view of the said head mounted display, (c) is a front view of the said head mounted display. It is sectional drawing which shows the schematic structure of the said video display apparatus. (A) is a top view which shows one schematic structure of the two types of transparent base materials which comprise the said eyepiece optical system, (b) is a front view of the said transparent base material, (c) ) Is a plan view showing a schematic configuration of the other transparent substrate, (d) is a front view of the transparent substrate, and (e) is a plan view of the eyepiece optical system. (A) is a top view which shows the other structural example of said one transparent base material, (b) is a top view which shows the other structural example of said other transparent base material, (c) is FIG. 10 is a plan view showing another configuration example of the eyepiece optical system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image display apparatus 2 Support means 11 Image display element 21 Eyepiece optical system (optical device)
22 transparent substrate 22a surface (joint surface)
22b surface (joint surface)
22c surface (joint surface)
23 transparent substrate 23a surface (joint surface)
23b surface (joint surface)
23c surface (joint surface)
24 Optical element 25 Adhesive 31 Uneven portion 32 Uneven portion

Claims (22)

An optical device in which an optical element is bonded to one transparent substrate and the other transparent substrate so as to sandwich the optical element, and an external image is observed through the bonding surface,
An optical device, wherein an uneven portion having an uneven surface is formed on the bonding surface.   The optical device according to claim 1, wherein the optical element is a hologram.   The optical device according to claim 1, wherein the optical element is a half mirror coat.   The optical device according to claim 1, wherein the concavo-convex portion is formed in a portion other than a region where the optical element is attached on the bonding surface.   5. The optical device according to claim 1, wherein the uneven portion is formed in a portion other than a region facing the optical element on the bonding surface.   The optical device according to claim 1, wherein the bonding surface includes a plurality of surfaces having different normal directions.   The area of the region where the concavo-convex part is formed is 10% or more of the area of the entire bonding surface in the transparent substrate on which the concavo-convex part is formed. The optical device described.   The area of the region where the optical element is affixed is 90% or less of the total area of the joint surface in the transparent substrate to which the optical element is affixed. An optical device according to claim 1.   The optical device according to claim 1, wherein the uneven portion is formed in a satin shape.   The optical device according to claim 1, wherein each of the transparent substrates is bonded to the bonding surface via an adhesive.   The optical device according to claim 10, wherein the adhesive is an ultraviolet curable adhesive.   The optical device according to claim 10 or 11, wherein a difference between a refractive index of the transparent base material on which the concave and convex portions are formed on the bonding surface and a refractive index of the adhesive is 0.02 or less. .   The optical device according to any one of claims 10 to 12, wherein each of the transparent base material, the optical element, and the adhesive is made of an acrylic material. An optical device in which an external image is seen through through the joint surfaces of a plurality of transparent substrates,
An optical device, wherein an uneven portion having an uneven surface is formed on the bonding surface. An optical device according to any one of claims 1 to 13,
An image display device comprising: an image display element for displaying an image and providing the image to the optical device.   The video display device according to claim 15, wherein the optical element of the optical device is a volume phase reflection hologram.   The video display device according to claim 15 or 16, wherein the optical element of the optical device is a combiner that simultaneously guides an image provided from the video display element and an external image to the eyes of an observer.   18. The eyepiece optical system according to claim 15, wherein the optical device constitutes an eyepiece optical system that enlarges an image displayed on the image display element and guides the image as a virtual image to an observer's eye. Video display device.   The video display device according to claim 18, wherein the eyepiece optical system has non-axisymmetric optical power.   20. The video display according to claim 15, wherein the transparent base material of the optical device causes the video light provided from the video display element to be totally reflected inside and guided to the optical element. apparatus.   21. The image display device according to claim 15, wherein the transmittance of the optical element of the optical device is 10% or more. A video display device according to any one of claims 15 to 21,
A head-mounted display comprising: support means for supporting the video display device in front of an observer's eyes.

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