JP2008165019A - Optical prism, manufacturing method of optical prism, cemented prism, video display apparatus, head mounted display, and video imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simultaneously assure both transferability of s sharp edge and surface precision in a deflection prism 23 by devising a position of a gate 61 and thereby to realize high molding precision. <P>SOLUTION: The gate 61 is provided in a region facing a surface 23e which connects a bottom 23p<SB>1</SB>of a recessed part 23p and a bottom 23q<SB>1</SB>of a recessed part 23q on a surface 23h of the deflection prism 23. A resin is poured into a metal mold via the gate 61 and then the resin is cured. By providing the gate 61 in the region described above, the resin reaches a surface 23e from the surface 23h with the shortest resin flow length and also reaches end parts of respective recessed parts 23p, 23q near an opening with relatively short resin flow length after passing its both sides. Accordingly the resin easily enters to a top acute part (for example, a part where a surface 23d and a surface 23c intersect each other). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical prism having two opposing surfaces facing each other and having a recess in the surface, and a connecting surface for connecting edges of the two opposing surfaces, a method for manufacturing the optical prism, and the optical prism A cemented prism formed by cementing an optical prism with another optical prism, a video display device including the cemented prism, a head-mounted display (hereinafter also referred to as an HMD) including the video display device, and the cemented prism. The present invention relates to a video imaging apparatus.

  Conventionally, video display apparatuses using a cemented prism as an eyepiece optical system have been proposed. For example, Patent Document 1 discloses a video display device that guides video light and external light from a video display element (for example, an LCD) simultaneously to an observer's pupil via a cemented prism. The cemented prism of this image display device is formed by joining a first optical prism and a second optical prism, and has a shape like a spectacle lens as a whole.

  The first optical prism will be described in more detail. The first optical prism has two opposing surfaces and a connecting surface that connects these two opposing surfaces. The two opposing surfaces each have a recess in the surface. The connection surface is composed of a plurality of joint surfaces and an outer peripheral surface. The joint surface is provided to be inclined with respect to the two opposing surfaces, and is a surface that joins the edges constituting the concave portions of the opposing surfaces and is joined to the second optical prism. An outer peripheral surface is a surface which connects edges other than the recessed part of each opposing surface. From such a configuration, the first optical prism has a substantially U-shape as a whole.

JP 2002-156600 A

  By the way, the first optical prism having the above-described configuration is manufactured by, for example, injection molding. At the time of injection molding, a gate is provided somewhere in the prism to be molded, and the resin is formed into a mold through the gate. It is necessary to pour. However, Patent Document 1 does not disclose the position where the gate is provided or the method of forming the first optical prism.

  Further, when the resin is poured into the mold through the gate, the portion farther from the gate (the portion where the resin flow length becomes longer) becomes lower in temperature and tends to become harder. For this reason, when the gate is provided, for example, at a position away from the plurality of bonding surfaces of the first optical prism, the resin poured from the gate faces the sharpened portion, that is, the plurality of bonding surfaces and the bonding surfaces therebetween. It does not penetrate well into the part where one of the two opposing surfaces intersects at an acute angle, sharp edge transferability (sharpness of the sharpened portion) decreases, and surface accuracy of each surface (joint surface, opposing surface) Decreases and it becomes difficult to realize an optical prism with high molding accuracy.

  The present invention has been made in order to solve the above-mentioned problems, and its purpose is to ensure both sharp edge transferability and surface accuracy at the same time, and to achieve high molding accuracy. Optical prism, method for manufacturing the optical prism, cemented prism formed by joining the optical prism and another optical prism, an image display device including the cemented prism, and an HMD including the image display device And providing a video imaging device including the cemented prism.

  The optical prism of the present invention is an optical prism having two opposing surfaces facing each other and having a recess in the surface, and a connecting surface that connects edges of the two opposing surfaces, the connecting surface comprising: It is composed of a plurality of joint surfaces that are joined to other optical prisms, and an outer peripheral surface that joins edges other than the recesses of each opposing surface, while connecting the edges constituting the concave portions of each opposing surface, At least one of the plurality of bonding surfaces is provided to be inclined with respect to the two opposing surfaces, and the optical prism flows resin into a mold through a gate provided on the outer peripheral surface, The gate is formed by curing the resin, and the gate is provided in a region facing the bonding surface connecting the bottoms of the concave portions of the opposing surfaces on the outer peripheral surface.

  Moreover, the manufacturing method of the optical prism of this invention has two opposing surfaces which mutually oppose and have a recessed part in a surface, and a connection surface which connects the edges of said two opposing surfaces, The said connection surface is In addition to connecting the edges that constitute the recesses of each facing surface, it is composed of a plurality of bonding surfaces that are joined to other optical prisms, and an outer peripheral surface that connects the edges other than the recesses of each facing surface. An optical prism manufacturing method in which at least one of the plurality of joint surfaces is provided to be inclined with respect to the two opposing surfaces, and the bottoms of the concave portions of the opposing surfaces are connected to each other on the outer peripheral surface. A resin is poured into a mold through a gate provided in a region facing a bonding surface to be cured, and the resin is cured.

  According to the above configuration, on the outer peripheral surface, the gate is provided in the region facing the bonding surface that connects the bottoms of the concave portions of the opposing surfaces, and the resin is poured into the mold through the gate. The resin reaches the joint surface connecting the bottoms of the recesses with the shortest resin flow length from the outer peripheral surface, and reaches the end near the opening of each recess with a relatively short resin flow length through both sides. . Therefore, even when any of the plurality of bonding surfaces to be bonded to the other optical prism is inclined with respect to the two opposing surfaces, the sharp portion of the prism (for example, the bonding surface and the bonding surface between them) The resin can easily enter a portion where two opposing surfaces face each other at an acute angle. As a result, both the sharp edge transferability and the surface accuracy of each surface (joint surface, opposing surface) can be ensured simultaneously, and an optical prism with high molding accuracy can be realized.

  Further, in the optical prism of the present invention, the gate includes a central position of the optical prism in a direction along the bottom of the concave portion of each opposing surface on the outer peripheral surface, and a central position of the bottom of the concave portion in the direction. It is desirable to be provided so as to straddle. In this case, the resin flow length from the gate to each joint surface can be shortened as compared with the case where the gate is provided in another region on the outer peripheral surface. As a result, the above-described effect of the present invention that an optical prism with high molding accuracy can be realized can be reliably obtained.

  In the method for manufacturing an optical prism according to the present invention, it is desirable to separate the optical prism from the mold by protruding the entire surface of at least one of the plurality of bonding surfaces with a corresponding mold after the resin is cured. . This is due to the following reason.

  When separating the optical prism from the mold, for example, if a part of the facing surface is ejected with an ejector pin, the projected surface remains on the surface, the appearance quality is impaired, and the optical characteristics of the surface (for example, transmission) Characteristic). In particular, when an optical prism is applied to, for example, an image display device, the quality of the external image observed through the see-through deteriorates due to a decrease in the optical characteristics of the surface. Further, if a part of the joint surface is protruded by the ejector pin, the surface may be partially distorted and the joint strength may not be sufficiently obtained.

  However, in the present invention, since at least one of the entire joining surfaces is projected by the mold, no protruding trace remains on the surface, and no partial distortion occurs on the surface. Therefore, it is possible to avoid both the appearance quality, the quality of the external image, and the decrease in bonding strength.

  In particular, in the method for producing an optical prism of the present invention, it is desirable that all of the plurality of joint surfaces are protruded with a corresponding mold after the resin is cured. When only a part of the joint surface is ejected, the force at the time of ejection is concentrated only on that surface, so the joint surface may tilt from the desired position with respect to the other surface, resulting in a decrease in joint strength. is there. However, by projecting all of the plurality of joint surfaces, each joint surface can be ejected with an equal force (the concentration of force on a part of the joint surfaces can be avoided). As a result, an unnecessary inclination of the joint surface can be prevented, and a decrease in joint strength can be reliably avoided.

  In the method for manufacturing an optical prism according to the present invention, the gate may be protruded by an eject pin after the resin is cured. Thus, in addition to protruding the joint surface with the mold, the optical prism can be easily separated from the mold by protruding the gate with the eject pin.

  The cemented prism of the present invention is a cemented prism formed by cementing a first optical prism and a second optical prism, and the first optical prism is composed of the above-described optical prism of the present invention. It is characterized by that. In this way, by forming the first optical prism with an optical prism having high molding accuracy and bonding the second optical prism to the first optical prism, it is possible to realize a cemented prism with good optical characteristics.

  At this time, the first optical prism may be joined to the second optical prism via an optical element. In this case, a cemented prism having an optical element function (for example, a diffraction reflection function in the case of a volume phase type reflection hologram optical element) can be realized, which is suitable for an image display apparatus and an image imaging apparatus. That is, the cemented prism of the present invention guides the image light incident on the second optical prism to the observer's pupil via the optical element, and transmits the external image light to the observer via the second and first optical prisms. It is applicable to an image display device that guides to the pupil of the second object, and the light of the subject image (for example, external image) incident on the second optical prism is guided to the image sensor through the optical element, and the light of the external image is transmitted to the second and second optical prisms. The present invention can be applied to a video imaging apparatus that leads to the observer's pupil via the first optical prism.

  The video display device of the present invention is a video display device having a video display element that displays video and an eyepiece optical system that guides video light from the video display element to an observer's pupil, wherein the eyepiece optical system includes: The optical element of the cemented prism is a combiner that simultaneously guides the image light and the external light to the observer's pupil.

  According to the above configuration, the observer can observe the image provided from the image display element through the cemented prism, and at the same time, can observe the external image through the cemented prism.

  In this case, it is desirable that the optical element of the cemented prism is a volume phase type reflection hologram optical element. In this case, since the image light incident on the second optical prism from the image display element is diffracted and reflected by the hologram optical element in the direction of the observer, the observer can observe a virtual image. Moreover, since the volume phase type reflection hologram optical element has a high light transmittance of the external field image, the observer can clearly observe the external field image.

  The hologram optical element preferably has an axially asymmetric optical power. In this case, it is possible to provide an observer with a well-corrected aberration image, and to increase the degree of freedom of arrangement of each optical member constituting the apparatus, and it is easy to downsize the apparatus.

  In the video display device of the present invention, the second optical prism may be configured to totally reflect video light from the video display element on two opposing surfaces and guide the light to the optical element. According to this configuration, since the total reflection in the second optical prism is used, the second optical prism and thus the cemented prism can be reduced in size and weight. In addition, since the image from the image display element can be observed, the external light transmittance is increased, so that a bright external image can be observed.

  The head-mounted display of the present invention includes the above-described video display device of the present invention 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 by the support means, the observer can observe the video provided from the video display device in a hands-free manner.

  An image pickup apparatus of the present invention includes an image pickup element that picks up a subject image and the above-described bonded prism of the present invention, and the optical element of the bonded prism is a volume phase type reflection hologram optical element, The light of the subject image incident on the second optical prism of the cemented prism is reflected by the hologram optical element, then totally reflected inside a plurality of times and emitted to the outside. It is characterized in that the light of the external image transmitted through the optical element is guided to the eyes of the observer.

  According to the above configuration, since the cemented prism is configured by using the first optical prism with high molding accuracy, it is possible to realize a video imaging apparatus with good optical characteristics. In addition, since the HOE is used, the apparatus can be reduced in size and weight. In addition, since total reflection is used, the cemented prism can be made small and light, the light transmittance of the external image can be increased, and the external image can be observed well. Moreover, it becomes possible to arrange | position an image pick-up element to the periphery of a visual field, and can ensure a wide external field viewing angle.

  According to the present invention, the resin poured into the mold through the gate reaches the joint surface connecting the bottoms of the recesses with the shortest resin flow length from the outer peripheral surface, and is relatively short through both sides thereof. The resin flow length reaches the end near the opening of each recess, and the resin easily enters the sharp part of the prism. As a result, both the sharp edge transferability and the surface accuracy of each surface (joint surface, opposing surface) can be ensured simultaneously, and an optical prism with high molding accuracy can be realized.

[Embodiment 1]
An embodiment of the present invention will be described below with reference to the drawings.

(1. About HMD)
2A is a plan view showing a schematic configuration of the HMD according to the present embodiment, FIG. 2B is a side view of the HMD, and FIG. 2C is a front view of the HMD. is there. 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 spectacles is configured by bonding an eyepiece prism 22 and a deflection prism 23 (both see FIG. 3) 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.

  Note that the HMD shown in FIGS. 2A, 2B, and 2C has a configuration including only one video display device 1, but includes two video display devices 1 corresponding to the left and right eyes. Of course, it does not matter even if it is a different configuration.

(2. About video display device)
Next, details of the above-described video display device 1 will be described.
FIG. 3 is a cross-sectional view illustrating a schematic configuration of the video display device 1. The video display device 1 includes a video display unit 11 and an eyepiece optical system 21. The video display unit 11 includes a light source 12, a unidirectional diffuser plate 13, a condenser lens 14, and an 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 unidirectional diffuser plate 13 diffuses 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 a direction corresponding to the left-right direction when the HMD is worn by an observer (a direction perpendicular to the paper surface of FIG. 3). Is diffused by about 0.2 ° in the vertical direction (the direction parallel to the paper surface of FIG. 3) 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 a video display element that displays video by modulating light from the light source 12 based on a video signal. In this embodiment, the LCD 15 is a transmissive type, but may be a reflective type (in this case, it is necessary to devise the arrangement position of other optical elements such as the light source 12). Further, a light modulation element other than the LCD (for example, DMD (Digital Micromirror Device; manufactured by Texas Instruments Incorporated, USA)) may be used as the image display element.

  On the other hand, the eyepiece optical system 21 is composed of a cemented prism. This cemented prism is formed by joining an eyepiece prism 22 (first optical prism) and a deflection prism 23 (second optical prism) with an optical element 24 interposed therebetween.

  The eyepiece prism 22 and the deflection prism 23 are made of, for example, an acrylic resin, and these are joined with an adhesive. The eyepiece prism 22 is formed in a shape in which the lower end portion of the parallel plate is wedge-shaped and the upper end portion is thickened, and has surfaces 22a, 22b, and 22c. The surface 22a is an incident surface on which the image light from the image display unit 11 is incident, and the surfaces 22b and 22c are surfaces facing each other (opposing surfaces). Among these, the surface 22b is further a total reflection surface and an emission surface.

  The deflection prism 23 is configured to be a substantially parallel flat plate integrally with the eyepiece prism 22 by forming the upper end portion of the parallel plate along the lower end portion of the eyepiece prism 22. When the deflecting prism 23 is not joined to the eyepiece prism 22, the light of the outside world image is refracted when passing through the wedge-shaped lower end of the eyepiece prism 22, so that the outside world image observed through the eyepiece prism 22 is distorted. However, the deflection prism 23 is joined to the eyepiece prism 22 to form an integral substantially parallel plate, so that the deflection when the light of the external image passes through the wedge-shaped lower end of the eyepiece prism 22 is canceled by the deflection prism 23. can do. As a result, it is possible to prevent distortion in the external image observed through the see-through.

  The optical element 24 is composed of a volume phase type reflection hologram optical element (HOE) 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. Yes. The optical element 24 is affixed to an inclined surface (a surface 22e described later (see FIG. 4A)) at the lower end of the eyepiece prism 22, and as a result, is sandwiched between the eyepiece prism 22 and the deflection prism 23. Yes. The volume phase type reflection hologram is produced, for example, by attaching an optical film including a photosensitive layer made of a photopolymer on the eyepiece prism 22 and exposing it with a laser beam.

  With such a configuration of the video display device 1, the light emitted from the light source 12 of the video display unit 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.

  Image light from the LCD 15 enters the eyepiece prism 22 of the eyepiece optical system 21 from its upper end surface (surface 22a), and is totally reflected a plurality of times (at least twice) by the two opposing surfaces 22b and 22c. The light enters the optical element 24 arranged on the surface 22e. The light incident on the optical element 24 is reflected there, exits through the surface 22b, 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, the eyepiece prism 22, the deflection prism 23, and the optical element 24 transmit almost all the light from the outside, so that 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 video (video light) and the external image (external light) provided from the video display unit 11 to the eyes of the observer.

  As described above, in the video display device 1, the video light emitted from the LCD 15 is subjected to total reflection on the surface 22 b (total reflection surface and emission surface) and the surface 22 c (opposite surface) of the eyepiece prism 22, and the surface 22 e and optical. The structure leads to the element 24. As a result, the thickness of the eyepiece prism 22 and the deflection prism 23 can be reduced to about 3 mm as in the case of a normal spectacle lens, and the eyepiece optical system 21 and thus the video display device 1 can be reduced in size and weight. Further, the light transmittance of the external image becomes high, and the external image can be observed well. Furthermore, the video display unit 11 can be arranged at a position far away from immediately before the eyes of the observer, and a wide field of view of the observer with respect to the outside world can be secured. In addition, since the HOE is used as the optical element 24, a bright image can be provided to the observer by combining the emission wavelength of the LED and the diffraction wavelength of the HOE.

  Further, as described above, since the optical element 24 is composed of a volume phase type reflection hologram optical element that diffracts only light having a specific wavelength at a specific incident angle, the image light from the LCD 15 is deflected by the eyepiece prism 22. There is no influence on the light of the external image transmitted through the prism 23 and the optical element 24. Therefore, the observer can observe the external image as usual through the eyepiece prism 22, the deflection prism 23, and the optical element 24 while observing the virtual image of the display image on the LCD 15 through the optical element 24.

  Further, since the optical element 24 is a combiner that guides image light and external light simultaneously to the observer's pupil, the observer can observe the image provided from the LCD 15 via the eyepiece optical system 21. At the same time, an external image can be observed through the eyepiece optical system 21 with see-through.

  Further, the hologram optical element constituting the optical element 24 has a positive axially asymmetric optical power for enlarging the image displayed on the LCD 15, and ocular optics that guides the display image as a virtual image to the observer's eyes. Since at least a part of the system 21 is configured, the eyepiece optical system 21 can be reduced in size, and an image that has been favorably corrected for aberrations can be provided to the observer.

(3. Details of eyepiece optical system)
Next, the details of the eyepiece prism 22 and the deflection prism 23 constituting the eyepiece optical system 21 will be described. In the following, for convenience of explanation, it is assumed that the surfaces of the eyepiece prism 22 and the deflection prism 23 are flat surfaces except for a curved surface portion 22k and a surface 23h described later.

  FIGS. 4A, 4B, 4C, 4D, and 4E are a plan view, a bottom view, a front view, a rear view, and a side view of the eyepiece prism 22, respectively. In these drawings, the gate 31 (see FIG. 8A), which will be described later, is omitted for convenience of explanation. The eyepiece prism 22 has a substantially quadrangular pyramid shape as a whole, and the upper surface thereof is the surface 22c described above, and the lower surface (bottom surface) is the surface 22b described above. At least four side surfaces are located around the surfaces 22b and 22c. These four side surfaces are surfaces 22d, 22e, 22f, and 22g arranged counterclockwise around the upper surface in the plan view of FIG. The normal directions of the surfaces 22d, 22e, 22f, and 22g are different from each other.

  Further, the surfaces 22d, 22e, and 22f are inclined with respect to the surfaces 22b and 22c, respectively, and serve as joint surfaces with the deflecting prism 23. The surfaces 22d, 22e, and 22f are inclined at an acute angle (for example, 10 degrees to 80 degrees) with respect to the surface 22b, and are inclined with an obtuse angle (for example, 110 degrees to 170 degrees) with respect to the surface 22c. Yes. That is, the surfaces 22d, 22e, and 22f are arranged such that one end of each of the surfaces 22d, 22e, and 22f is connected to the surface 22b, and the other end of each of the surfaces 22d, 22e, and 22f is connected to the surface 22c. It is an inclined surface. The surface 22g is formed with a protruding portion 22h that protrudes upward from the upper surface. In the protruding portion 22h, a surface 22a serving as an image light incident surface is located on the opposite side of the surface 22g. is doing.

  The optical element 24 described above is attached to the surface 22e of the eyepiece prism 22. Since the optical element 24 has a diffraction reflection function as described above, the surface 22e to which the optical element 24 is attached is also one of inclined surfaces (joint surfaces), but light (image light) incident from the surface 22a. ) Is also reflected and led to the surface 22b. Therefore, it can be said that the eyepiece prism 22 is an optical prism that reflects light incident from the surface 22a on the surface 22e and emits the light to the outside through the surface 22b.

  Further, the surface 22a, the surface 22b, and the surface 22e are formed substantially symmetrically with respect to a surface (hereinafter, this surface is also referred to as a reference surface) S perpendicularly crossing these surfaces. The overall shape is substantially symmetric with respect to the reference plane S.

  Further, the end of the surface 22c opposite to the connection side with the surface 22e is connected to the surface 22a via the surface 22i. That is, the surface 22i constitutes the upper surface of the protruding portion 22h and also constitutes a connecting surface that connects the surface 22c and the surface 22a. The surface 22i may be composed of at least one surface, and in the present embodiment, the surface 22i is composed of three surfaces connected so as to be bent. As a result, the eyepiece prism 22 includes the surface 22a, the first prism portion 22A that faces the surface 22i and the surface 22b, the second prism portion 22B that includes the surface 22b, and faces the surfaces 22b and 22c, and the surface 22e. The third prism portion 22C is opposed to the surface 22b.

Here, the first prism portion 22A is configured further in width as the narrow portion 22A ₁ and the equal width portion 22A _2. The narrow portion 22A ₁ is located on the surface 22a side, perpendicular width on the reference plane S is formed to be narrower than the second prism portion 22B. On the other hand, equal-width portion 22A ₂ is located in the second prism portion 22B side, perpendicular width on the reference plane S is formed to be the same as the second prism portion 22B.

The width and surface 22j that constitutes a side surface of the narrow portion 22A _1, the surface of the narrow portion 22A ₁ side in equal width portion 22A ₂ (i.e., the surface 22 g) and is connected via a curved surface portion 22k. The curved surface portion 22k has a shape having a curvature that becomes wider as it goes from the first prism portion 22A side to the second prism portion 22B side.

  Thus, since the surface 22j is connected to the surface 22g via the curved surface portion 22k, the resin flowing from the gate 31 (see FIG. 8A) described later during molding and flowing in the vicinity of the curved surface portion 22k, It can be made to flow along the shape of the curved surface portion 22k. Thereby, resin can be spread to every corner in the width direction perpendicular to the reference plane S, and the eyepiece prism 22 with high molding accuracy in the width direction can be realized. In particular, since the curved surface portion 22k has a curvature that becomes wider as it goes from the first prism portion 22A side to the second prism portion 22B side, such an effect can be reliably obtained.

  On the other hand, FIG. 5A shows a plan view of the deflection prism 23, and FIG. 5B shows a front view of the deflection prism 23. Further, FIG. 6A shows a plan view of the eyepiece optical system 21 in which the eyepiece prism 22 and the deflection prism 23 are joined, and FIG. 6B shows a B- of the eyepiece optical system 21 in FIG. B 'arrow sectional drawing is shown. 5A and 5B, the gate 61 (see FIG. 1A), which will be described later, is omitted for convenience of explanation. Further, the cross-sectional view of the eyepiece optical system 21 shown in FIG. 3 corresponds to a cross-sectional view taken along the line A-A ′ of the eyepiece optical system 21 of FIG.

  The deflection prism 23 is shaped so that a parallel plate is formed by joining the eyepiece prism 22. That is, the deflection prism 23 has a shape (substantially U-shaped) obtained by hollowing out the eyepiece prism 22 from a parallel plate along its shape. The deflecting prism 23 has opposite surfaces 23b and 23c. These surfaces 23b and 23c are located on the same plane as the surfaces including the surfaces 22b and 22c when the eyepiece prism 22 is joined. That is, in this case, one of the two opposed surfaces of the eyepiece optical system 21 facing each other is formed by two surfaces of the surface 22b of the eyepiece prism 22 and the surface 23b of the deflection prism 23, and the other surface is the eyepiece prism 22. The surface 22c and the surface 23c of the deflecting prism 23 are formed. The surfaces 23b and 23c have recesses 23p and 23q in each surface.

  The deflection prism 23 has surfaces 23d, 23e, and 23f that are joined to the surfaces 22d, 22e, and 22f when the deflection prism 23 is joined. These surfaces 23d, 23e, and 23f have mutually different normal directions, are inclined at an obtuse angle (for example, 110 degrees to 170 degrees) with respect to the surface 23b, and are acute with respect to the surface 23c (for example, 10 degrees). It is inclined at not less than 80 degrees and not more than 80 degrees. That is, each of the surfaces 23d, 23e, and 23f is an inclined surface that is disposed so that one end side thereof is closer to the surface 23c than the other end side.

  The edges of the surfaces 23b and 23c are connected to each other through a surface 23g (connection surface). This surface 23g connects the edges constituting the recesses 23p and 23q, and also serves as an outer peripheral surface that connects the surfaces 23d, 23e, and 23f joined to the eyepiece prism 22 and edges other than the recesses 23p and 23q. And the surface 23h.

  As shown in FIG. 6A, the deflecting prism 23 having the above-described configuration is joined to the eyepiece prism 22 to which the optical element 24 is attached via an adhesive so as to sandwich the optical element 24. 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 cemented surfaces (surfaces 22d, 22e, 22f, surfaces 23d, 23e, 23f) of the eyepiece prism 22 and the deflection prism 23. Become. In addition, since the eyepiece prism 22 and the deflection prism 23 can be accurately formed by the manufacturing method described later, the eyepiece optical system 21 is configured by joining the eyepiece prism 22 and the deflection prism 23 to form an optical system. An eyepiece optical system 21 with good characteristics can be realized.

  Further, since the eyepiece prism 22 is joined to the deflecting prism 23 by placing the optical element 24 on the surface 22e, the diffraction reflection function of the optical element 24 is provided to the observer through the joint surface through the see-through image. It is possible to realize the eyepiece optical system 21 having the above.

  Further, as in this embodiment, the surfaces 22d, 22e, and 22f of the eyepiece prism 22 are inclined with respect to the surfaces 22b and 22c, and the surfaces 23d, 23e, and 23f of the deflection prism 23 are inclined with respect to the surfaces 23b and 23c. By doing so, as shown in FIG. 6B, it is possible to avoid the light of the external image reflected at the interface (for example, the interface between the surface 22f and the surface 23f) at the joint surface from entering the eyes of the observer. it can. In addition, it is possible to increase the bonding area of the bonding surface (bonding area of the adhesive) and to release the contraction of the adhesive in an oblique direction to increase the bonding strength.

  FIG. 7 is a perspective view showing another configuration example of the eyepiece optical system 21. As shown in the figure, the surfaces 22d and 22f of the eyepiece prism 22 constituting the eyepiece optical system 21 may be substantially perpendicular to the surface 22b, and the surfaces 23d and 23f of the deflection prism 23 are substantially perpendicular to the surface 23b. There may be. Even in this case, the surface 22e which is one of the joining surfaces is inclined with respect to the surfaces 22b and 22c, and the surface 23e which is also one of the joining surfaces is inclined with respect to the surfaces 23b and 23c. The above-described effect can be obtained by the inclined arrangement of the joint surfaces. Further, if at least one of a plurality of joint surfaces (for example, the surface 23e) in the deflecting prism 23 is provided to be inclined with respect to the two opposing surfaces (surfaces 23b and 23c), a sharp portion ( For example, the intersection of the surface 23e and the surface 23c) is formed, so that the effect of the present invention obtained by the manufacturing method of the deflection prism 23 described later can be obtained.

(4. About manufacturing method of eyepiece prism)
Next, a method for manufacturing the eyepiece prism 22 will be described. In the present embodiment, the eyepiece prism 22 is formed by injection molding. 8A is a cross-sectional view of the eyepiece prism 22 at the time of injection molding, FIG. 8B is a plan view of the eyepiece prism 22 at the time of injection molding, and FIG. It is explanatory drawing which shows the method of isolate | separating the eyepiece prism. In addition, the thick line in FIG.8 (c) shows the parting line PL which is a parting line (including the contact part of a metal mold | die and resin) of a some metal mold | die.

In this embodiment, the ocular prism 22 through a gate 31 provided in the ridge portion 22a ₁ which intersects the reference plane S in the surface 22a from the runner 32 into the mold pouring of resin (e.g., thermoplastic resin), the resin It is formed by curing. That is, the gate 31 serves as an entrance when the resin is poured into the mold, but the gate 31 is not the center of the surface 22a, but a reference surface among a plurality of ridge lines positioned at the end of the surface 22a. It is provided at the ridge line portion 22a ₁ intersecting with S. Moreover, the gate 31 is formed substantially symmetrically with respect to the reference plane S (see FIG. 8B).

In addition, as said some ridgeline part here, the site | part which gave some width | variety (area) to the line | wire (ridgeline) produced when two adjacent surfaces cross | intersect can be assumed, Said ridgeline part 22a ₁ refers to the site including the ridge line of intersection between the surface 22a and the surface 22i.

  The above-mentioned mold is composed of a plurality of molds including a fixed mold and a movable mold. For example, an eject pin 41 is provided on the movable mold. Therefore, after the resin is cured in the mold, the movable side mold is separated from the fixed side mold, and the gate 31 of the molded product (eyepiece prism 22) stuck to the movable side mold is ejected 41. Can be separated from the movable mold. Thereafter, the gate 31 may be cut at a predetermined location.

In the present embodiment, as shown in FIG. 8 (c), a portion of the parting line PL and a surface of the stationary mold corresponding to (this portion is referred to as the parting line PL ₁ a), molding The mold is configured such that the surface that contacts the optical surface (for example, the surface 22b) of the product (eyepiece prism 22) is inclined with respect to the surface perpendicular to the mold separation direction. By configuring the mold in this way, for example, even when the surface 22a of the eyepiece prism 22 is inclined at an acute angle with respect to the surface 22b, the molded product is fixed and fixed when the mold is separated in the above direction. It can be prevented that it cannot be removed from the side mold.

As described above, since the gate 31 is provided on the ridge line portion 22a ₁ of the surface 22a of the eyepiece prism 22, when the resin is poured into the mold through the gate 31, the reference surface S is provided on both sides. Resin can be poured evenly. That is, the flow and spread of the resin can be made equal (substantially symmetrical) on both sides with respect to the reference plane S. This makes it possible to reliably obtain the eyepiece prism 22 whose overall shape is substantially symmetric with respect to the reference plane S using the corresponding mold, and to realize the eyepiece prism 22 with high molding accuracy.

Moreover, the gate 31 is not a center of the surface 22a, since provided on the ridge portion 22a _1, it does not affect the optical characteristics (transmission characteristics) in the plane 22a. Therefore, it is possible to obtain the eyepiece prism 22 with high molding accuracy while avoiding the deterioration of the optical characteristics on the surface 22a.

  Further, since the gate 31 is formed substantially symmetrically with respect to the reference plane S, the resin can surely be poured into both sides of the reference plane S via the gate 31 with high molding accuracy. The eyepiece prism 22 can be reliably realized.

(5. About manufacturing method of deflection prism)
Next, a method for manufacturing the deflection prism 23 will be described. FIG. 1A is a plan view of the deflection prism 23 illustrating the gate 61, FIG. 1B is a front view of the deflection prism 23, and FIG. 3 is a cross-sectional view of a deflection prism 23. FIG.

The deflecting prism 23 is formed by pouring a resin (for example, a thermoplastic resin) into a mold through a gate 61 provided on the surface 23h and curing the resin. The above gate 61, on the surface 23h, the bonding surface connecting the bottom 23p ₁ · 23q ₁ of the respective recesses 23p · 23q, that is provided on the surface 23e facing the area. More specifically, the gate 61, on the surface 23h, the center position C1 of the deflecting prism 23 in the direction along the bottom 23p ₁ · 23q ₁ of each recess 23p · 23q, the center of the bottom portion 23p ₁ · 23q ₁ in the direction It is provided so as to straddle position C2.

  The mold used for the injection molding of the deflection prism 23 is composed of a plurality of molds including a fixed mold and movable molds 71 and 72. Therefore, after the resin is cured in the mold, the movable molds 71 and 72 are separated from the fixed mold and the molded product (deflection prism 23) that is stuck to the movable molds 71 and 72. ), The deflection prism 23 can be separated from the molds 71 and 72 by projecting the entire joint surface (for example, the surface 23e) with the corresponding mold 71.

  The movable die 72 is provided with an eject pin 73 at a position corresponding to the gate 61. Therefore, when the deflection prism 23 is separated from the molds 71 and 72, in addition to the protrusion by the mold 71, the molded product can be separated from the molds 71 and 72 by protruding the gate 61 with the eject pin 73. It becomes easy. Thereafter, the gate 61 may be cut at a predetermined location.

  The gate 61 is not provided on the optical surface (surface 23c) or the bonding surface (surfaces 23d, 23e, and 23f), and affects the appearance quality, the quality of the external image, and the bonding strength on the surface 23h. Since the gate 61 is provided by the eject pin 73, the appearance quality, the image quality, and the bonding strength are not deteriorated.

  As described above, in the present embodiment, the gate 61 is provided in the region on the surface 23h of the deflecting prism 23, which is opposed to the innermost joining surface (surface 23e). Since the resin is poured into the mold through the surface, the resin reaches the surface 23e with the shortest resin flow length from the surface 23h, and the openings of the recesses 23p and 23q with a relatively short resin flow length through both sides. It reaches the end of the neighborhood. Therefore, even if any joint surface of the deflection prism 23 is inclined with respect to the two opposing surfaces, the resin can easily enter the sharpened portion (for example, the intersection of the surface 23e and the surface 23c) of the deflection prism 23, and the sharp edge. Transferability (sharpness of the sharpened portion) and surface accuracy of the joint surfaces (surfaces 23d, 23e, and 23f) and the opposing surface (surface 23c) can be simultaneously ensured. As a result, the deflection prism 23 with high molding accuracy can be realized.

  Further, since the gate 61 is not provided on the bonding surface or the opposite surface, the gate 61 reduces the optical characteristics (for example, transmission characteristics) on each surface and the bonding strength with the eyepiece prism 22 on the bonding surface. There is no reduction.

  Further, since the gate 61 is provided so as to straddle the position C1 and the position C2 on the surface 23h, the gate 61 is compared with the case where the gate 61 is provided in another region on the surface 23h. The resin flow length from the surface to the surfaces 23d, 23e, and 23f can be shortened. As a result, it is possible to reliably realize the deflection prism 23 with high molding accuracy.

  Further, in this embodiment, after the resin is cured, the deflection prism 23 is separated from the molds 71 and 72 by protruding the entire surface 23e with the corresponding mold 71, so that a part of the surface is ejected. The protruding trace generated when protruding with the pin does not remain on the surface 23e, and the surface is not partially distorted. Therefore, it is possible to avoid both the appearance quality, the quality of the external image, and the decrease in bonding strength.

  By the way, when the deflection prism 23 is separated from the dies 71 and 72, not only the surface 23e but also other joint surfaces (for example, the surface 23d and the surface 23f) protrude the entire surface with the corresponding dies. It is desirable to do so. Thus, by projecting a plurality of joint surfaces with corresponding molds, it is possible to avoid concentration of force on a part of the joint surfaces and project each joint surface with an equal force. As a result, an unnecessary inclination of the joint surface can be prevented, and a decrease in joint strength can be reliably avoided. In particular, when the deflection prism 23 is separated from the molds 71 and 72, the above-described effects can be most effectively obtained by projecting all of the plurality of joint surfaces with the corresponding molds.

  The above-described optical prism gates (the gate 31 of the eyepiece prism 22 and the gate 61 of the deflecting prism 23) can be scraped to some extent by polishing or the like, but even in that case, for example, via a polarizing plate. By applying light (linearly polarized light) to the optical prism, it is possible to know how birefringence occurs in the optical prism based on the light transmitted through the optical prism. As a result, the position of the scraped gate and the fluidity of the resin (how the resin flows) can be known.

  In the above description, the case where each surface of the eyepiece prism 22 and the deflecting prism 23 (excluding the curved surface portion 22k and the surface 23h) is a plane has been described. However, each surface may be configured by a curved surface. For example, by giving curvatures to the surfaces 22b and 22c and the surfaces 23b and 23c, the eyepiece optical system 21 can also have a function as a correction spectacle lens.

[Embodiment 2]
The following will describe another embodiment of the present invention with reference to the drawings. For convenience of explanation, the same components as those in the first embodiment are denoted by the same member numbers, and the description thereof is omitted.

  FIG. 9 is an explanatory diagram showing a schematic configuration of the video imaging apparatus 81 according to the present embodiment and a positional relationship between the external image and the observer's pupil. The video imaging device 81 includes a cemented optical prism 82, an imaging optical system 83, and an imaging element 84.

  The cemented optical prism 82 is obtained by joining the first optical prism 91 and the second optical prism 92 with the optical element 93 interposed therebetween, and the light of the subject image is captured via the imaging optical system 83. Lead to 84. The optical element 93 is disposed on the joint surface of the first optical prism 91. The first optical prism 91, the second optical prism 92, and the optical element 93 of the present embodiment have the same configuration as the eyepiece prism 22, the deflection prism 23, and the optical element 24 shown in the first embodiment. However, although the surfaces 91b and 91a of the first optical prism 91 correspond to the surfaces 22b and 22a of the eyepiece prism 22, they function as an entrance surface and an exit surface, respectively, in this embodiment. The surface 91 c of the first optical prism 91 corresponds to the surface 22 c of the eyepiece prism 22.

  The imaging optical system 83 is an optical system that guides the light emitted from the cemented optical prism 82 to the imaging element 84, and includes, for example, a photographing lens. The image pickup device 84 picks up a subject image by receiving light obtained through the image pickup optical system 83, and is composed of, for example, an image sensor such as a CCD or a CMOS.

  That is, in the video image pickup apparatus 81 of the present embodiment, in the video display apparatus 1 of the first embodiment, the light source 12 and the LCD 15 are replaced with the imaging element 84, the condenser lens 14 is replaced with the image pickup optical system 83, and the eyepiece optical system 21. Is merely replaced by the cemented optical prism 82. In addition, the shape and characteristics of the prism are all the same as those of the video display device 1 described above.

  According to the configuration described above, the light of the subject image (for example, the image of the observer's pupil) is incident from the surface 91b of the first optical prism 91, is diffracted and reflected by the optical element 93, and then internally multiple times. The light is totally reflected and emitted from the surface 91 a, and is guided to the image sensor 84 through the imaging optical system 83. At the same time, the light of the external image transmitted through the optical element 93 is guided to the eyes of the observer. That is, with this arrangement of the video imaging device 81, it is possible to capture a pupil image of an observer who is looking at an external field image through the optical element 93.

  Also, as shown in FIG. 10, if the positional relationship between the external image and the observer's pupil with respect to the video imaging device 81 is reversed from that in FIG. 9, the video imaging device 81 allows the viewer to see through the optical element 93. It is possible to capture an image of the outside world.

  As described above, in the present embodiment, the configuration of the cemented prism (the eyepiece optical system 21) according to the first embodiment is applied to the cemented optical prism 82 of the video imaging device 81. Therefore, it is possible to realize a video imaging device 81 with good optical characteristics.

  Further, by using HOE as the optical element 93, the video imaging device 81 can be made small and light. In addition, since the total reflection at the first optical prism 91 is used, the cemented optical prism 82 can be reduced in size and weight, the light transmittance of the external image can be increased, and the external image can be observed well. . In addition, the image sensor 84 can be arranged around the visual field, and a wide external field viewing angle can be secured.

  Of course, various devices can be configured by appropriately combining the methods and configurations described in the embodiments.

  The optical prism (deflection prism) of the present invention can be used for a cemented prism with an eyepiece prism, a video display device, a video imaging device, an HMD, and the like.

(A) is a top view of the deflection prism which illustrated the gate of the eyepiece optical system which comprises the image display apparatus of HMD which concerns on one Embodiment of this invention, (b) is a front view of the said deflection prism. (C) is a sectional view of the deflection prism during injection molding. (A) is a top view which shows the outline structure of HMD, (b) is a side view of HMD, (c) is a front view of HMD. It is sectional drawing which shows the schematic structure of the said video display apparatus. (A) is a plan view of the eyepiece prism of the eyepiece optical system, (b) is a bottom view of the eyepiece prism, (c) is a front view of the eyepiece prism, and (d) is a front view of the eyepiece prism. FIG. 3 is a rear view of the eyepiece prism, and FIG. 3E is a side view of the eyepiece prism. (A) is a top view of the said deflection prism which abbreviate | omitted illustration of a gate, (b) is a front view of the said deflection prism. (A) is a top view of the said eyepiece optical system, (b) is a B-B 'arrow sectional drawing of the eyepiece optical system of (a). It is a perspective view which shows the other structural example of an eyepiece optical system. (A) is sectional drawing at the time of injection molding of the said eyepiece prism, (b) is a top view at the time of injection molding of the said eyepiece prism, (c) isolate | separates the said eyepiece prism from a metal mold | die. It is explanatory drawing which shows a method. It is explanatory drawing which shows an example of the schematic structure of the video imaging device which concerns on other embodiment of this invention, and shows an example of the positional relationship of the external field image with respect to the said video imaging device, and an observer's pupil. It is explanatory drawing which shows the other example of the positional relationship of the external field image and observer's pupil with respect to the said video imaging device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Video display apparatus 2 Support means 15 LCD (video display element)
21 Eyepiece optical system (joint prism)
22 Eyepiece prism (optical prism, first optical prism)
23 Deflection prism (optical prism, second optical prism)
23b surface (opposite surface)
23c surface (opposite surface)
23d surface (joint surface)
23e surface (joint surface)
23f surface (joint surface)
23g surface (connection surface)
23h surface (outer peripheral surface)
23p recess 23p ₁ bottom 23q recess 23q ₁ bottom 24 optical element 61 gate 71 mold 72 mold 73 ejector pin 81 image pickup device 82 joined optical prism (joined prism)
84 Image sensor 91 First optical prism 92 Second optical prism 93 Optical element

Claims (14)

Two opposing surfaces facing each other and having a recess in the surface;
An optical prism having a connecting surface that connects edges of the two opposing surfaces,
The connecting surface is
A plurality of joint surfaces to be joined to other optical prisms, while connecting the edges constituting the concave portions of each facing surface,
It is composed of outer peripheral surfaces that connect edges other than the concave portions of each facing surface,
At least one of the plurality of joint surfaces is provided to be inclined with respect to the two opposing surfaces,
The optical prism is formed by pouring a resin into a mold through a gate provided on the outer peripheral surface and curing the resin.
The optical prism according to claim 1, wherein the gate is provided in a region facing a joint surface that connects bottoms of the concave portions of the opposing surfaces on the outer peripheral surface.   The gate is provided on the outer peripheral surface so as to straddle the central position of the optical prism in the direction along the bottom of the concave portion of each facing surface and the central position of the bottom of the concave portion in the direction. The optical prism according to claim 1. Two opposing surfaces facing each other and having a recess in the surface;
A connecting surface that connects the edges of the two opposing surfaces;
The connecting surface is
A plurality of joint surfaces to be joined to other optical prisms, while connecting the edges constituting the concave portions of each facing surface,
It is composed of outer peripheral surfaces that connect edges other than the concave portions of each facing surface,
An optical prism manufacturing method in which at least one of the plurality of joint surfaces is provided to be inclined with respect to the two opposing surfaces,
An optical prism characterized in that on the outer peripheral surface, a resin is poured into a mold through a gate provided in a region facing a joint surface that connects the bottoms of the concave portions of each facing surface, and the resin is cured. Manufacturing method.   4. The optical prism according to claim 3, wherein after curing of the resin, the optical prism is separated from the mold by projecting at least any one of the plurality of joint surfaces with a corresponding mold. 5. Production method.   5. The method of manufacturing an optical prism according to claim 4, wherein after the resin is cured, all of the plurality of bonding surfaces are protruded by a corresponding mold.   6. The method of manufacturing an optical prism according to claim 4, wherein after the resin is cured, the gate is protruded by an eject pin. A cemented prism formed by cementing a first optical prism and a second optical prism,
3. The cemented prism according to claim 1, wherein the first optical prism includes the optical prism according to claim 1.   The cemented prism according to claim 7, wherein the first optical prism is joined to the second optical prism via an optical element. An image display element for displaying an image;
An image display device having an eyepiece optical system for guiding image light from the image display element to an observer's pupil,
The eyepiece optical system includes the cemented prism according to claim 8,
The image display device, wherein the optical element of the cemented prism is a combiner that simultaneously guides the image light and the external light to an observer's pupil.   10. The video display device according to claim 9, wherein the optical element of the cemented prism is a volume phase type reflection hologram optical element.   The video display device according to claim 10, wherein the hologram optical element has an axially asymmetric optical power.   12. The image display device according to claim 9, wherein the second optical prism totally reflects the image light from the image display element on two opposing surfaces and guides the image light to the optical element. A video display device according to any one of claims 9 to 12,
A head-mounted display comprising support means for supporting the video display device in front of an observer's eyes. An image sensor for capturing a subject image;
A cemented prism according to claim 8;
The optical element of the cemented prism is a volume phase type reflection hologram optical element,
The light of the subject image incident on the second optical prism of the cemented prism is reflected by the hologram optical element, then totally reflected internally several times, emitted to the outside, and guided to the imaging element. An image pickup apparatus for guiding light of an external image transmitted through a hologram optical element to an observer's eye.

Images