JP2017003757A - Optical element, image display device, and method for manufacturing optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical element capable of highly accurately positioning a hologram element inexpensively, an image display device using the optical element, and a method for manufacturing the optical element.SOLUTION: In the optical element including a prism including a hologram element 104h including a hologram part HOE selectively reflecting or transmitting light having a predetermined wavelength, a recess part CC is formed in the end surface of a first prism and when the hologram element 104h is arranged in the recess part CC, the recess part CC and at least a part of the outer periphery of the hologram element 104h come into contact with each other, to position the hologram part HOE to the first prism.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an optical element using a hologram element, an image display device, and a method for manufacturing the optical element.

  2. Description of the Related Art In recent years, development of an image display device in which a holographic optical element (hereinafter abbreviated as “hologram element”) is provided in a prism and an image is projected to a user's eye through the hologram element is progressing. As an example of the image display device, a glasses-type wearable display, a head-mounted display, and the like are known.

  A typical hologram element has two interference fringe patterns consisting of interference fringes that are not parallel to the hologram surface. The image formed by the light of the specified wavelength projected from the display unit is reflected inside the prism and reaches the hologram element, and is diffracted and reflected by the interference fringe pattern of the hologram element and guided to the user's eyes. On the other hand, light other than the specified wavelength in external light passes through the hologram element and is guided to the user's eyes. That is, the user can view the scenery of the outside world and the image formed by the display unit simultaneously through the hologram element.

  Here, in Patent Document 1, a hologram photosensitive material sheet is stuck in a concave portion formed in a prism, and further, an interference fringe pattern is exposed to the hologram photosensitive material sheet with a coherent laser beam, and developed by irradiating ultraviolet rays or the like. Technology is disclosed. In Patent Document 2, a multilayer film including a photosensitive film is positioned and fixed on an eyepiece prism using a jig, and then a coherent laser beam is irradiated on the photosensitive film to produce a hologram element. Technology is disclosed. However, the method of forming the interference fringe pattern by individually exposing the hologram photosensitive material sheet or the multilayer film to the prism and performing the exposure takes time and increases the cost.

JP 2007-163953 A JP 2008-137346 A

  On the other hand, there is an attempt to promote cost reduction by forming an interference fringe pattern in advance on a sheet-like photosensitive material and affixing this to a prism surface. However, according to such a technique, when the sheet on which the interference fringe pattern is formed is attached to the prism surface, if the positioning is not performed with high accuracy, the displayed image may be unclear. On the other hand, Patent Document 2 discloses that a jig such as a positioning pin is used when positioning the multilayer film on the eyepiece prism. Therefore, it is conceivable to apply such a technique to position the sheet on which the interference fringe pattern is formed on the prism using a jig.

  However, when positioning is performed using a jig as described above, a positional deviation occurs between the jig and the sheet, and a positional deviation also occurs between the jig and the eyepiece prism. There is a problem that high-accuracy positioning cannot be realized due to superposition.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an optical element that can accurately position a hologram element at low cost, an image display apparatus using the optical element, and a method for manufacturing the optical element. And

The optical element of the present invention is an optical element having a prism provided with a hologram element provided with a hologram portion that selectively reflects or transmits light of a prescribed wavelength.
A first prism having a concave portion formed on an end surface, the hologram element is disposed in the concave portion, and the concave portion and at least a part of an outer periphery of the hologram element are in contact with each other with respect to the first prism; The hologram part is positioned.

The optical element of the present invention is an optical element having a prism provided with a hologram element provided with a hologram portion that selectively reflects or transmits light of a prescribed wavelength.
A concave portion having a protrusion disposed therein is formed on an end face of the first prism, the hologram element is disposed in the concave portion, and the hologram element has an opening or notch, and the opening or notch is formed in the protrusion. The hologram portion is positioned with respect to the first prism by engaging.

The optical element manufacturing method of the present invention is a method for manufacturing an optical element having a prism provided with a hologram element.
Forming a recess in the end face of the first prism;
Positioning the hologram element with respect to the first prism by bringing the recess into contact with at least a part of the outer periphery of the hologram element;
The hologram element is bonded to the recess.

The optical element manufacturing method of the present invention is a method for manufacturing an optical element having a prism provided with a hologram element.
Forming a recess in the end face of the first prism, and forming a protrusion in the recess,
Forming an opening or notch in the hologram element;
Positioning the hologram element with respect to the first prism by engaging the opening or notch with the protrusion,
The hologram element is bonded to the recess.

  ADVANTAGE OF THE INVENTION According to this invention, the optical element which can position a hologram element accurately at low cost, the image display apparatus using the same, and the manufacturing method of an optical element can be provided.

1 is a perspective view of a head mounted display 100 including an optical element according to a first embodiment. It is the figure which looked at the head mounted display 100 concerning this Embodiment from the front. It is the figure which looked at the head mounted display 100 concerning this Embodiment from the upper direction. 3 is a schematic cross-sectional view showing a configuration of a display unit 104. FIG. It is a perspective view of the image display part 104B. It is a figure which shows the process of assembling the hologram element 104h to the deflection | deviation prism 104g. In the configuration of FIG. 5, the display unit 104 is cut along a line VII-VII extending in the longitudinal direction through the center of the hologram element 104h on a plane perpendicular to the longitudinal direction of the image display unit 104B. FIG. 2 is a block diagram of main circuits of the head mounted display 100. FIG. It is a perspective view which shows the slope of the deflection | deviation prism 104g concerning the modification of this Embodiment. FIG. 10 is a cross-sectional view of the configuration shown in FIG. 9 cut along a plane passing an XX line extending along the longitudinal direction of the recess CC and passing through the center of the recess CC and viewed in the direction of the arrow. It is a perspective view which shows the inclined surface of the deflection | deviation prism 104g concerning another modification of this Embodiment. 11 is a cross-sectional view taken along the XII-XII line extending along the longitudinal direction of the recess CC and passing through the center of the recess CC and viewed in the direction of the arrow in the configuration of FIG. It is a perspective view which shows the slope of the eyepiece prism 104f and the deflection | deviation prism 104g concerning 2nd Embodiment. It is the figure which cut | disconnected perpendicularly | vertically with respect to the main surface in the surface which passes along the XIV-XIV line | wire of FIG. 13 in the state which joined the eyepiece prism 104f and the deflection | deviation prism 104g, and was seen in the arrow direction. It is sectional drawing similar to FIG. 7 concerning this Embodiment. It is a figure which shows the modification of this Embodiment, and is sectional drawing cut | disconnected by the surface orthogonal to slope PL4, PL5 and passing through the center of recessed part CC. It is sectional drawing which shows another modification. It is sectional drawing which shows another modification. It is a perspective view which shows the inclined surface of the deflection | deviation prism 104g concerning 3rd Embodiment. It is a perspective view which shows the slope of the eyepiece prism 104f and the deflection | deviation prism 104g concerning 3rd Embodiment. FIG. 21 is a view of the eyepiece prism 104f and the deflection prism 104g joined together, cut along a plane passing through the XV-XV line of FIG. It is a top view of the hologram element which is a modification according to the present embodiment. It is a perspective view which shows the inclined surface of the eyepiece prism 104f and the deflection | deviation prism 104g concerning other embodiment.

(First embodiment)
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a head mounted display (hereinafter referred to as HMD) 100 including an optical element according to the first embodiment. FIG. 2 is a front view of the HMD 100 according to the present embodiment. FIG. 3 is a view of the HMD 100 according to the present embodiment as viewed from above. Hereinafter, the right side and the left side of the HMD 100 refer to the right side and the left side for the user wearing the HMD 100.

  As shown in FIGS. 1 to 3, the HMD 100 of the present embodiment has a frame 101. A frame 101 that is U-shaped when viewed from above has a front part 101a to which two spectacle lenses 102 are attached, and side parts 101b and 101c extending rearward from both ends of the front part 101a. The two spectacle lenses 102 attached to the frame 101 may or may not have refractive power.

  A cylindrical main body 103 is fixed to the front portion 101 a of the frame 101 on the upper side of the right eyeglass lens 102 (which may be the left side according to the user's dominant eye). The main body 103 is provided with a display unit 104 that is an image display device. In the main body 103, a display control unit 104DR (see FIG. 8 described later) that controls display of the display unit 104 based on an instruction from the processor 121 described later is disposed. If necessary, a display unit may be arranged in front of both eyes.

  FIG. 4 is a schematic cross-sectional view showing the configuration of the display unit 104. The display unit 104 includes an image forming unit 104A and an image display unit 104B. FIG. 5 is a perspective view of the image display unit 104B. In FIG. 4, the image forming unit 104A is incorporated in the main body unit 103, and includes a light source 104a, a one-way diffuser plate 104b, a condenser lens 104c, and a display element 104d. On the other hand, the so-called see-through type image display unit 104B is generally plate-shaped and is disposed so as to extend downward from the main body unit 103 and to extend in parallel with one eyeglass lens 102 (see FIG. 1). The eyepiece prism 104f as the second prism, the deflecting prism 104g as the first prism, and the hologram element 104h are combined to form an optical element as will be described later. The deflection prism 104g is provided with a tapered portion TP whose thickness decreases as the distance from the image forming unit 104A increases at the end on the image forming unit 104A side. However, such a shape is arbitrary and is limited to the illustrated one. Absent.

  The light source 104a has a function of illuminating the display element 104d. For example, 462 ± 12 nm (B light), 525 ± 17 nm (G light), 635 ± 11 nm (R It is composed of RGB-integrated LEDs that emit light in three wavelength bands (in this case, light of a prescribed wavelength). As described above, the light source 104a emits light having a predetermined wavelength, whereby the image light obtained by illuminating the display element 104d can have a predetermined wavelength, and the hologram element 104h reflects the image light. The user can observe the image over the entire observation angle of view at the position of the pupil B. Further, the peak wavelength for each color of the light source 104a is set in the vicinity of the peak wavelength of the diffraction efficiency of the hologram element 104h, so that the light utilization efficiency is improved. Note that light having a wavelength other than the specified wavelength is transmitted through the hologram element 104h, so that the user can observe the outside world through the display unit 104.

  Further, since the light source 104a is composed of LEDs that emit RGB light, the cost of the light source 104a can be reduced, and a color image is displayed on the display element 104d when the display element 104d is illuminated. The color image can be visually recognized by the user. In addition, since each of the RGB LED elements has a narrow emission wavelength width, the use of a plurality of such LED elements enables high color reproducibility and bright image display.

  The display element 104d displays an image by modulating the light emitted from the light source 104a in accordance with image data, and is configured by a transmissive liquid crystal display element having pixels that serve as light transmitting regions in a matrix. Has been. Note that the display element 104d may be of a reflective type.

  The eyepiece prism 104f totally reflects the image light from the display element 104d that is incident through the base end face PL1 as a light incident surface by the opposing parallel inward principal surface PL2 and the outward principal surface PL3, thereby causing the hologram element 104h to be reflected. In addition to being guided to the user's pupil through the light, the external light is transmitted to the user's pupil, and is composed of, for example, an acrylic resin (or PC or glass) together with the deflecting prism 104g. The eyepiece prism 104f has a slope PL5 as a joint surface on its end face, and the deflection prism 104g also has a slope PL4 as an end face inclined at the same angle and having the same dimensions as the slope PL5.

  Next, a method for manufacturing the image display unit 104B will be described. FIG. 6 is a diagram showing a process of assembling the hologram element 104h to the deflecting prism 104g. As a preparation, a rectangular plate-shaped hologram element 104h is prepared. The hologram element 104h attaches a photosensitive material to a PET rectangular sheet ST as a substrate, irradiates a coherent laser beam from two directions, and forms an interference fringe pattern by the interference of the two laser beams. The hologram portion HOE thus formed is formed (see Japanese Patent Application Laid-Open No. 2008-137346). The interference fringe pattern of the hologram portion HOE is formed with high accuracy with respect to the outer periphery of the hologram element 104h.

  On the other hand, as shown in FIG. 6A, at the center of the inclined slope PL5 of the eyepiece prism 104f, a concave portion CC recessed in a rectangular shape by, for example, molding using a mold or the like, for example, molding of the eyepiece prism 104f. Form simultaneously. The size of the recess CC is preferably slightly larger than the hologram element 104h. The bottom surface CCc of the recess CC is parallel to the slope PL5. The concave portion CC is formed to be in an appropriate position with respect to the deflecting prism 104g when the inclined surfaces PL4 and PL5 are brought together.

  First, an adhesive (AD: UV curable adhesive shown in FIG. 7 is preferable) is applied to the bottom surface CCc, which is the plane of the concave portion CC of the eyepiece prism 104f, and a hologram is obtained as shown in FIG. 6 (b). The element 104h is placed on the bottom surface CCc of the recess CC. At this time, the bottom surface CCc comes into close contact with the hologram portion HOE due to the effect of the adhesive AD. Further, since the adhesive AD does not protrude from the concave portion CC, it can be easily applied and has excellent handleability.

  At that time, one side 104ha of the hologram element 104h is brought into contact with the upper side surface CCa (may be the lower side surface) of the concave portion CC, and the other side 104hb is brought into contact with the left side surface CCb (may be the right side surface) of the concave portion CC. When abutting, the hologram element HOE is accurately positioned without using the hologram element 104h, that is, a jig or the like, with respect to the recess CC. Here, as shown in FIG. 6B, “positioning” means that the center O of the recess CC is the origin, the longitudinal direction of the slope PL5 is the X axis, and the direction perpendicular to the Y axis on the slope PL5 is Y. When used as an axis, the position in the X-axis direction, the position in the Y-axis direction, and the angle θ around the origin O are all within an allowable range with respect to the design position and design angle. The positioning accuracy of the hologram element is preferably 0.1 mm or less, for example, when the length of the hologram element in the longitudinal direction is about 10 mm.

  In this state, the adhesive AD is cured by irradiating UV light from the outside, and the hologram element 104h is fixed to the bottom surface CCc of the recess CC. Next, a UV curable adhesive BD is applied between the slopes PL4 and PL5, and the side faces of the eyepiece prism 104f and the deflection prism 104g are used as a reference, as shown in FIG. The adhesive BD is cured by being positioned at a specified position so as not to protrude from each other and irradiating UV light from the outside. It should be noted that when the slope PL4 and the slope PL5 are joined using an adhesive BD having a volume larger than the space in the recess CC, the excess adhesive BD protrudes from the joint and is wiped off before curing. For example, the space between the slope PL4 and the slope PL5 can be completely filled with the adhesive BD. Note that the rectangular sheet ST may be slightly protruded from the slope PL5 and may be elastically compressed by closely pressing the slope PL4 so as to be flush with the slope PL5.

  The deflecting prism 104g is joined to the eyepiece prism 104f, and is integrated with the eyepiece prism 104f to form a substantially parallel plate. In the present embodiment, the slope PL4 of the deflection prism 104g joined to the end surface (slope PL5) provided with the concave portion of the eyepiece prism 104f is flat. In principle, the user can visually recognize the image light reflected by the hologram element 104h as a virtual image without providing the deflection prism 104g. However, by joining the deflection prism 104g to the eyepiece prism 104f, the user can It is possible to prevent the external image observed through the display unit 104 from being distorted.

  That is, for example, when the deflecting prism 104g is not joined to the eyepiece prism 104f, the external light is refracted when passing through the slope PL5 of the eyepiece prism 104f, so that the external image observed through the eyepiece prism 104f is distorted. However, refraction when external light passes through the slopes PL5 and PL4 (hologram element 104h) is formed by joining the deflection prism 104g having the slope PL4 complementary to the eyepiece prism 104f to form an integral substantially parallel plate. Can be canceled by the deflection prism 104g. As a result, it is possible to prevent distortion in the external image observed through the see-through. In addition, if the spectacle lens 102 (refer FIG. 1) is mounted | worn between the display unit 104 and a user's pupil, it will be possible for the user who normally uses spectacles to observe an image without a problem. It is also possible to incorporate the eyepiece prism 104f and the deflection prism 104g directly into the spectacle lens 102.

  FIG. 7 shows the configuration of FIG. 5 in which the display unit 104 is cut along a line VII-VII extending in the longitudinal direction through the center of the hologram element 104h on a plane perpendicular to the longitudinal direction of the image display unit 104B. It is the figure seen from the arrow direction. The hologram element 104h that transmits light having a wavelength other than the specified wavelength described above substantially transmits the external light OL having a broadband wavelength, and the adhesive AD and the adhesive BD filled in the recess CC without any gap are also transparent. Since the refractive index is substantially equal to the refractive indexes of the eyepiece prism 104f and the deflecting prism 104g, the concave portion CC and the slopes PL4 and PL5 are not visually visible. Therefore, the external light OL passes through the eyepiece prism 104f and the deflecting prism 104g and is visually recognized by the user's pupil below in FIG. On the other hand, the image light IL emitted from the image forming unit 104A is guided through the eyepiece prism 104f, then exits from the slope PL5, and enters the hologram element 104h in the recess CC.

  The hologram unit HOE of the hologram element 104h diffracts and reflects the image light IL (light having a wavelength corresponding to the three primary colors) emitted from the display element 104d, and enlarges the image displayed on the display element 104d to enlarge the user's pupil. It is a volume phase type reflection hologram guided as a virtual image. The hologram unit HOE has, for example, three specified wavelengths of 465 ± 5 nm (B light), 521 ± 5 nm (G light), and 634 ± 5 nm (R light) with a peak wavelength of diffraction efficiency and a half width of diffraction efficiency. It is made to diffract (reflect) the light in the region. Here, the peak wavelength of diffraction efficiency is the wavelength at which the diffraction efficiency reaches a peak, and the wavelength width at half maximum of the diffraction efficiency is the wavelength width at which the diffraction efficiency is at half maximum of the diffraction efficiency peak. is there.

  The reflection type hologram unit HOE has high wavelength selectivity, and only diffracts and reflects light having a wavelength in the specified wavelength range (near the exposure wavelength). Therefore, external light including wavelengths other than the diffracted and reflected wavelength is used. Is transmitted through the hologram portion HOE, and a high external light transmittance can be realized.

  Next, the operation of the display unit 104 will be described. In FIG. 4, the light emitted from the light source 104a is diffused by the one-way diffusion plate 104b, condensed by the condenser lens 104c, and enters the display element 104d. The light incident on the display element 104d is modulated for each pixel based on the image data input from the display control unit 104DR, and is emitted as image light. As a result, a color image is displayed on the display element 104d.

  The image light from the display element 104d enters the eyepiece prism 104f from the base end face PL1, is totally reflected a plurality of times by the inward principal surface PL2 and the outward principal surface PL3, and enters the hologram element 104h. The light incident on hologram element 104h is reflected by hologram portion HOE, passes through inward main surface PL2, and reaches pupil B. At the position of the pupil B, the user can observe an enlarged virtual image of the image displayed on the display element 104d, and can visually recognize it as a screen formed on the image display unit 104B. In this case, it can be considered that the hologram portion HOE constitutes the screen, or it can be considered that the screen is formed on the inward main surface PL2. In the present specification, “screen” may refer to an image to be displayed.

  On the other hand, the eyepiece prism 104f, the deflecting prism 104g, and the hologram element 104h transmit almost all of the external light, so that the user can observe an external image (real image) through them. Therefore, the virtual image of the image displayed on the display element 104d is observed so as to overlap with a part of the external image. In this way, the user of the HMD 100 can simultaneously observe the image provided from the display element 104d and the external image via the hologram element 104h. Note that when the display unit 104 is in the non-display state, the image display unit 104B is transparent, and only the external image can be observed. In this example, the light source and the liquid crystal display element are combined to form the image forming unit. However, instead of the combination of the light source and the liquid crystal display element, a self-luminous display element (for example, an organic EL display element) is used. It may be used. In any case, when the screen is arranged so as to be at least partially overlapped with the effective visual field so as to enter the visual field of the user's eye facing the image display unit 104B, the user can easily visually recognize the image. it can.

  Further, in FIGS. 1 and 2, a proximity sensor 105 that detects a user's gesture arranged near the center of the frame 101 and a lens 106 a of the camera 106 arranged near the side are located in front of the main body 103. It is provided so as to face.

  1 and 2, a right sub-body portion 107 is attached to the right side portion 101b of the frame 101, and a left sub-body portion 108 is attached to the left side portion 101c of the frame 101. The right sub-body portion 107 and the left sub-body portion 108 have an elongated plate shape, and have elongated protrusions 107a and 108a on the inside. By engaging the elongated protrusion 107a with the elongated hole 101d of the side portion 101b of the frame 101, the elongated auxiliary protrusion 107a is attached to the frame 101 with the right sub-main body portion 107 positioned. By engaging with the elongated hole 101e of the side portion 101c of the frame 101, the left sub-main body portion 108 is attached to the frame 101 in a positioned state.

  In the right sub-main body 107, a geomagnetic sensor 109 (see FIG. 8 to be described later) for detecting geomagnetism, and a gyro and acceleration sensor 110 (see FIG. 8 to be described later) that generates an output corresponding to the posture. And a speaker (or earphone) 111 </ b> A and a microphone 111 </ b> B (see FIG. 8 described later) are provided in the left sub-main body unit 108. The main main body 103 and the right sub main body 107 are connected so as to be able to transmit signals through a wiring HS, and the main main body 103 and the left sub main body 108 are connected so as to be able to transmit signals through a wiring (not shown). Yes. As schematically illustrated in FIG. 3, the right sub-main body 107 is connected to the control unit CTU via a cord CD extending from the rear end. A 6-axis sensor in which a gyro and an acceleration sensor are integrated may be used. Further, the HMD can be operated by sound based on an output signal generated from the microphone 111B according to the input sound. Further, the main main body 103 and the left sub main body 108 may be configured to be wirelessly connected.

  FIG. 8 is a block diagram of main circuits of the HMD 100. The control unit CTU includes a processor 121, an operation unit 122, a GPS reception unit 123 that receives radio waves from GPS satellites, a communication unit 124 that exchanges data with the outside, a ROM 125 that stores programs, and image data. And the like, a power supply circuit 128 for supplying power to each unit, a battery 127, and a storage device 129 such as an SSD or a flash memory. The processor 121 can use an application processor used in a smartphone or the like, but the type of the processor 121 is not limited. For example, if an application processor includes hardware necessary for image processing such as GPU or Codec as a standard, it can be said that the processor is suitable for a small HMD.

  Furthermore, when the light receiving unit 105a detects the detection light emitted from the human body, the signal is input to the processor 121, thereby enabling gesture detection and the like. Further, the processor 121 controls image display of the display unit 104 via the display control unit 104DR.

  The processor 121 receives power from the battery 127 via the power supply circuit 128, operates according to a program stored in at least one of the ROM 124 and the storage device 129, and follows the operation input such as power-on from the operation unit 122 according to an operation input such as power on. Can be input and stored in the RAM 126, and can communicate with the outside via the communication unit 124 as necessary.

  FIG. 9 is a perspective view showing an inclined surface of an eyepiece prism 104f according to a modification of the present embodiment, and FIG. 10 passes through the center of the recess CC along the longitudinal direction of the recess CC in the configuration of FIG. It is sectional drawing cut | disconnected by the surface which passes along XX line | wire extended in the direction of the arrow. In the present modification, a deeper similar dish-shaped portion CCd is formed at the center of the bottom surface CCc of the recess CC. The periphery of the dish-like portion CCd is the bottom surface CCc. According to this modification, as shown by a dotted line in FIG. 10, when the hologram element 104h is attached to the concave portion CC so as to be in close contact with the bottom surface CCc, the dish-like portion CCd is located between the concave portion CC and the hologram element 104h. The applied adhesive BD becomes an escape portion (adhesive pool, that is, a storage portion), and excess adhesive BD can be stored. As a result, fluctuations in the amount of the supplied adhesive BD can be absorbed, and the adhesive leaking to the outside is suppressed, thereby contributing to the improvement of the appearance quality.

  FIG. 11 is a perspective view showing an inclined surface of an eyepiece prism 104f according to another modification of the present embodiment, and FIG. 12 shows the center of the recess CC along the longitudinal direction of the recess CC in the configuration of FIG. It is sectional drawing cut | disconnected by the surface which passes along the XII-XII line | wire extended so that it may pass, and it looked at the arrow direction. In this modification, a deeper circumferential groove CCe is formed around the bottom surface CCc of the recess CC. The inner side of the circumferential groove CCe becomes the bottom surface CCc. According to this modification, as shown by a dotted line in FIG. 12, when the hologram element 104h is attached to the recess CC so as to be in close contact with the bottom surface CCc, the circumferential groove CCe is applied between the recess CC and the hologram element 104h. It becomes the escape part (adhesive agent pool, ie, accommodating part) of the adhesive agent BD which was made, and can accommodate the excess adhesive agent BD.

(Second Embodiment)
FIG. 13 is a perspective view showing slopes of the eyepiece prism 104f and the deflection prism 104g according to the second embodiment. 14 shows a state in which the eyepiece prism 104f and the deflecting prism 104g are joined and cut along a plane passing through the XIV-XIV line (a line extending in the longitudinal direction of the image display unit 104B through the center of the hologram element 104h) in FIG. It is the figure seen from the arrow direction. FIG. 15 is a cross-sectional view similar to FIG. 7 according to the present embodiment. The difference between the present embodiment and the first embodiment will be mainly described, and the description of the configuration common to the first embodiment will be omitted.

  In the present embodiment, a convex portion CV protruding into a rectangular plate shape is formed at the center of the slope PL4 of the deflecting prism 104g by, for example, molding using a mold. The top surface CVa of the convex portion CV is a flat surface. The outer peripheral shape of the convex portion CV matches the inner peripheral shape of the concave portion CC. In the present embodiment, it is not necessary to apply an adhesive to the hologram portion HOE. When the display unit is assembled, as shown in FIGS. 14 and 15, the hologram element 104h is placed on the bottom surface CCc while being positioned with respect to the concave portion CC. Next, a UV curable adhesive is applied to one of the slope PL4 and the slope PL5, and the convex portion CV is engaged with the concave portion CC. When the slope PL4 and the slope PL5 are in close contact with each other, the sheet ST of the hologram element 104h is entirely pressed by the convex portion CV, so that the hologram portion HOE can be brought into close contact with the bottom surface CCc. In this state, the adhesive is cured by irradiating UV light from the outside.

  According to the present embodiment, by engaging the convex portion CV with the concave portion CC, the eyepiece prism 104f and the deflecting prism 104g are positioned, and at the same time, the hologram element 104h can be pressed and fixed. The hologram portion HOE can be accurately positioned.

  Also in the present embodiment, the external light OL passes through the eyepiece prism 104f and the deflecting prism 104g and is visually recognized by the user's pupil below in FIG. On the other hand, the image light IL guided through the eyepiece prism 104f is guided through the eyepiece prism 104f, then exits from the slope PL5, and enters the hologram element 104h in the recess CC.

  FIG. 16 is a view showing a modification of the present embodiment, and is a cross-sectional view taken along a plane orthogonal to the slopes PL4 and PL5 and passing through the center of the recess CC. In the embodiment described above, the top surface of the convex portion CV is a flat surface, whereas in the present modification, the top surface CVa is a curved surface (a cylindrical surface having an axis perpendicular to the paper surface).

  When the eyepiece prism 104f and the deflecting prism 104g are assembled, as shown in FIG. 16A, when the convex portion CV of the slope PL5 approaches the concave portion CC of the slope PL4, first, the center of the top surface CVa is a concave portion. When contacting the center of the sheet ST of the hologram element 104h positioned at the CC and further bringing the slopes PL4 and PL5 closer to each other, the hologram element 104h is elastically deformed so that the sheet ST gradually moves from the center to the periphery of the top surface CVa. Abut. Thereby, even if air exists between the hologram portion HOE and the bottom surface CCc, in the state shown in FIG. 16B, it is suppressed from being pushed out to the peripheral side and remaining as bubbles. Therefore, the optical characteristics of the display unit can be enhanced.

  17 and 18 are diagrams showing still another modified example. In the example of FIG. 17, the top surface CVa of the convex portion CV and the bottom surface CCc of the concave portion CC have curved surfaces having the same curvature radius. On the other hand, in the example of FIG. 18, the top surface CVa that is the convex curved surface of the convex portion CV and the bottom surface CCc that is the concave curved surface of the concave portion CC have curved surfaces, but the radii of curvature are different from each other. . It is preferable that the curvature radius of the top surface CVa is larger than the curvature radius of the bottom surface CCc. The radius of curvature of each part can be selected to an optimum value in consideration of the effect of pushing out bubbles. In the embodiment described above, the bubbles can be assembled so as to be pushed out to the opposite side by inclining the convex portion CV with respect to the concave portion CC while being brought into contact with the hologram element 104h. Further, by making the hologram portion HOE a curved surface following the bottom surface CCc, it is possible to suppress the influence of the focus position shift of the formed virtual image.

(Third embodiment)
FIG. 19 is a perspective view illustrating an inclined surface of the eyepiece prism 104f according to the third embodiment. FIG. 20 is a perspective view showing slopes of the eyepiece prism 104f and the deflection prism 104g according to the third embodiment. 21 shows a surface passing through the XXI-XXI line (a line extending through the center of the cylindrical protrusion CY and extending along the short direction of the hologram element 104h) in FIG. 20 in a state where the eyepiece prism 104f and the deflecting prism 104g are joined. FIG.

  In the present embodiment, the hologram element 104h has a shorter hologram portion HOE stacked on a PET rectangular sheet ST, and both sides of the rectangular sheet ST sandwiching the hologram portion HOE. Is formed with a circular opening CH. The position of the circular opening CH is accurately positioned with respect to the interference fringe pattern of the hologram portion HOE. As a manufacturing method of the hologram element 104h, a photosensitive material is pasted on a rectangular sheet ST having a circular opening CH formed by a punch or the like, and further fixed to a jig or the like using the circular opening CH. The hologram part HOE oriented with respect to the circular opening CH can be formed by irradiating the photosensitive material with two laser beams from two directions.

  On the other hand, on the bottom surface CCc of the concave portion CC on the slope PL5 of the eyepiece prism 104f, two cylindrical portions CY (which constitute a protrusion in the present embodiment) having an outer diameter substantially equal to the inner diameter of the circular opening CH are implanted. Yes. The inner diameter of the circular opening CH and the outer diameter of the cylindrical portion CY are fitted to each other and are within the tolerance range. The height of the cylindrical portion CY is longer than the depth of the concave portion CC, and therefore the cylindrical portion CY protrudes outward from the slope PL5. The concave portion CC and the cylindrical portion CY can be formed simultaneously with the molding of the eyepiece prism 104f.

  Further, a pair of bag holes BH (which form a depression in the present embodiment) having an inner diameter equal to the outer diameter of the cylindrical portion CY are formed on the slope PL4 of the deflection prism 104g. The bag hole BH can also be formed simultaneously with the formation of the deflection prism 104g.

  At the time of assembly, after applying adhesive to the bottom surface CCc, which is the flat surface of the concave portion CC of the eyepiece prism 104f, and applying the adhesive into the concave portion CC, the circular opening CH is opposed to the cylindrical portion CY of the concave portion CC as shown in FIG. Then, the hologram element 104h is placed on the bottom surface CCc while the hologram element 104h is brought close to the concave portion CC and the cylindrical portion CY is engaged with and passed through the circular opening CH. By providing a pair of circular openings CH on both sides across the hologram part HOE, the mutual interval is widened. Therefore, by engaging the circular opening CH with the cylindrical part CY, accurate positioning can be performed. At this time, the bottom surface CCc comes into close contact with the rectangular sheet ST due to the effect of the adhesive.

  According to the present embodiment, by engaging the cylindrical portion CY with the circular opening CH, the hologram element 104h, that is, the hologram portion HOE is accurately positioned with respect to the slope PL5.

  In this state, with the concave portion CC filled with a UV curable adhesive, as shown in FIG. 20, the cylindrical portions CY are inserted into the bag holes BH so that the slopes PL4 and PL5 are aligned. As shown in FIG. 21, when the inclined surfaces PL4 and PL5 are in close contact with each other while the cylindrical portion CY is engaged with the bag hole BH, the hologram element 104h is positioned with high accuracy with respect to the eyepiece prism 104f. Thereafter, by irradiating UV light from the outside, the adhesive in the concave portion CC can be cured, and the eyepiece prism 104f and the deflection prism 104g can be joined.

  For example, instead of providing a pair of columnar portions in the recess CC, a cylindrical bag hole is formed, a corresponding cylindrical protrusion is formed on the rectangular sheet ST of the hologram element 104h, and the cylindrical bag hole has a cylindrical shape. The hologram element 104h can be positioned by engaging the protrusion. In such a case, positioning of the eyepiece prism 104f and the deflecting prism 104g may be performed using both side surfaces, and the bag hole BH is unnecessary. Further, by engaging one cylindrical portion CY with one circular opening CH, positioning in the XY direction shown in FIG. 6B is performed, and a part of the outer periphery of the rectangular sheet ST is brought into contact with the concave portion CC. Thus, positioning in the θ direction can also be performed.

  FIG. 22 is a top view of a hologram element which is a modified example according to the present embodiment. In this modification, a cutout CT is formed in the rectangular sheet ST instead of a circular opening. The notch CT includes a substantially circular engaging portion CTa and an extending portion CTb extending from the engaging portion CTa to the end side. In the present modification, the hologram element 104h is positioned by engaging the cylindrical portion CY with the engaging portion CTa. By configuring as in the present modification, the installation work of the hologram element 104h is facilitated, and the hologram element 104h is less likely to be deformed due to the heat generated when the photosensitive material is irradiated with light. is there.

  In each of the embodiments described above, the eyepiece prism 104f is the first prism, and the hologram element 104h is disposed in the recess formed in the eyepiece prism 104f. However, the present invention is not limited to this, and as an auxiliary optical member for correcting the distortion of the virtual image. The deflection prism 104g may be the first prism, and as shown in FIG. 23, the hologram element 104h may be disposed in a recess formed in the deflection prism 104g. In this case, as shown in FIG. 23, the slope PL5 of the eyepiece prism 104f as the second prism may be provided with a convex portion corresponding to the concave portion CC provided on the slope PL4 of the deflection prism 104g. It may be flat.

100 Head Mount Display (HMD)
101 Frame 101a Front part 101b Side part 101c Side part 101d Long hole 101e Long hole 102 Eyeglass lens 103 Main body part 104 Display unit 104A Image forming part 104B Image display part 104DR Display control part 104a Light source 104b Unidirectional diffuser 104c Condensing lens 104d Display element 104f Eyepiece prism (second prism)
104g deflection prism (first prism)
104h Hologram element 104ha One side 104hb One side 105 Proximity sensor 105a Light receiving unit 106 Camera 106a Lens 107 Right sub-main unit 107a Protruding member 108 Left sub-main unit 108a Protruding member 109 Geomagnetic sensor 110 Acceleration sensor 111B Microphone 121 Processor 122 Operation unit 123 GPS Reception unit 124 Communication unit 127 Battery 128 Power supply circuit 129 Storage device AD Adhesive B Pupil BD Adhesive BH Bag hole CC Recess CCa Upper side CCb Left side CCc Bottom CCd Dish-shaped part CCe Circumferential groove CD Code CH Circular opening CT Notch CTa Engagement portion CTb Extension portion CTU Control unit CV Protrusion portion CVa Top surface CY Cylindrical portion HOE Hologram portion HS Wiring IL Image light OL External light PL1 Base end surface PL2 Inward main surface PL3 Outward main surface PL4 Slope PL Slope ST rectangular sheet TP tapered portion

Claims (20)

In an optical element having a prism provided with a hologram element provided with a hologram part that selectively reflects or transmits light of a prescribed wavelength,
A first prism having a concave portion formed on an end surface, the hologram element is disposed in the concave portion, and the concave portion and at least a part of an outer periphery of the hologram element are in contact with each other with respect to the first prism; An optical element in which the hologram part is positioned.   A second prism having a joint surface that is joined to an end face of the first prism, and a convex portion that engages with the concave portion is formed on the joint surface of the second prism, and the concave portion and the convex portion; The optical element according to claim 1, wherein the second prism is positioned with respect to the first prism by being engaged with each other.   The optical element according to claim 2, wherein the second prism is bonded to an end surface of the first prism in a state where the hologram element is pressed toward the concave portion by the convex portion.   The optical element according to claim 1, wherein a top surface of the convex portion of the second prism is a convex curved surface.   The optical element according to claim 3, wherein a bottom surface of the concave portion of the first prism is a curved surface or a flat surface having a curvature equal to or less than a curvature of a top surface of the convex portion of the second prism.   The optical element according to claim 2, wherein the second prism is bonded to the first prism to correct a distortion of a virtual image formed by light reflected by the hologram element. .   The optical element according to claim 1, wherein the first prism guides image light incident from a light incident surface to the end surface on which the hologram element is disposed. In an optical element having a prism provided with a hologram element provided with a hologram part that selectively reflects or transmits light of a prescribed wavelength,
A concave portion having a protrusion disposed therein is formed on an end face of the first prism, the hologram element is disposed in the concave portion, and the hologram element has an opening or notch, and the opening or notch is formed in the protrusion. Is an optical element in which the hologram portion is positioned with respect to the first prism.   The hologram element includes a substrate on which the hologram portions are stacked, the openings or notches are formed on both sides of the substrate sandwiching the hologram portions, and the recesses of the first prism are respectively associated with the openings or notches. The optical element according to claim 8, wherein two projections are provided.   A second prism having a joint surface joined to an end face of the first prism, and a recess engaging with the projection is formed on the joint surface of the second prism; The optical element according to claim 9, wherein the second prism is positioned with respect to the first prism by passing through the notch and engaging with the recess.   The optical element according to claim 1, wherein a pressure-sensitive adhesive that adheres the hologram element is applied to the concave portion of the first prism.   The optical element according to claim 1, wherein the hologram element is fixed to a concave portion of the first prism using an adhesive, and the concave portion includes a storage portion that stores the adhesive.   An image display device comprising: the optical element according to claim 1; and an image forming unit that emits light having the specified wavelength to the optical element. In the method of manufacturing an optical element having a prism provided with a hologram element,
Forming a recess in the end face of the first prism;
Positioning the hologram element with respect to the first prism by bringing the recess into contact with at least a part of the outer periphery of the hologram element;
A method for manufacturing an optical element, wherein the hologram element is bonded to the recess. Forming a convex portion on the joint surface of the second prism;
The method of manufacturing an optical element according to claim 14, wherein a joint surface of the second prism is joined to an end face of the first prism so that the concave portion and the convex portion are engaged with each other.   The method of manufacturing an optical element according to claim 15, wherein the convex portion presses the hologram element when the concave portion and the convex portion are engaged.   The method for manufacturing an optical element according to claim 14, wherein the hologram element is manufactured by forming a hologram portion by irradiating light having a predetermined wavelength from two directions onto a photosensitive material laminated on a sheet. In the method of manufacturing an optical element having a prism provided with a hologram element,
Forming a recess in the end face of the first prism, and forming a protrusion in the recess,
Forming an opening or notch in the hologram element;
Positioning the hologram element with respect to the first prism by engaging the opening or notch with the protrusion,
A method for manufacturing an optical element, wherein the hologram element is bonded to the recess. Forming a recess in the joint surface of the second prism,
19. The optical element according to claim 18, wherein after the projection or the notch is passed, the projection is engaged with the depression, and the junction surface of the second prism is joined to the end surface of the first prism. Production method.   The optical element according to claim 18 or 19, wherein a photosensitive material is laminated on the substrate provided with the opening or notch, and the hologram element is formed by forming a hologram portion by irradiating the photosensitive material with light from two directions. Manufacturing method.