JP2008165016A - 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 mold an ocular prism 22 to an almost symmetrical shape about a reference surface S by devising a position of a gate 31 and thereby to realize high molding precision. <P>SOLUTION: The gate 31 which becomes an entrance when a resin is poured into a metal mold is provided at any ridgeline part intersecting the reference surface S crossing respective surfaces described above among ridgeline parts of respective surfaces of the ocular prism 22: an incidence surface (a surface 22a), a reflection surface (a surface 22e) and an ejection surface (a surface 22b). The resin is poured into the metal mold via the gate 31 and then the resin is cured. By pouring the resin into the metal mold via the gate 31 thus located, the resin can be equally poured into both sides toward a reference surface S and thereby the ocular prism 22 having an almost symmetrical whole shape about the reference surface S can be obtained by using a corresponding metal mold. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention includes an optical prism that reflects light incident from an incident surface on a reflecting surface and emits the light to the outside through an exit surface, a method for manufacturing the optical prism, and joining the optical prism and another optical prism. The present invention relates to a cemented 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 a video imaging device including the cemented prism. .

  Conventionally, various optical prisms having at least three surfaces of an entrance surface, a reflection surface, and an exit surface have been proposed. Such an optical prism is manufactured by, for example, injection molding, but at the time of injection molding, it is necessary to provide a gate somewhere in the optical prism to be molded and to flow resin into the mold through the gate. . In this regard, for example, in Patent Documents 1 and 2, a gate is provided on the side surface of the optical prism (a surface intersecting the incident surface, the reflecting surface, and the exit surface), and resin is poured from the gate into the mold.

JP 9-73005 A (refer to claim 4, paragraphs [0051] to [0053], FIG. 1) JP-A-11-149003 (see claim 11, paragraphs [0090] to [0093], FIG. 1 (a))

  By the way, when the optical prism has three surfaces, that is, an incident surface, a reflective surface, and an exit surface, as an optical surface, the optical prism has a substantially symmetrical shape with respect to a surface (hereinafter also referred to as a reference surface) that intersects the entrance surface, the reflective surface, and the exit surface. It is desirable to manufacture an optical prism. This is because the image light from an image display element such as an LCD is incident on the incident surface of the optical prism, and the image light is incident on the observer's pupil via the reflecting surface and the exit surface. This is because the image observed by the observer is distorted unless the shape is substantially symmetrical with respect to the reference plane.

  However, as in Patent Documents 1 and 2, in the configuration in which resin is poured from the side surface of the optical prism, one side is close to the gate and the other side is far from the gate with respect to the reference surface. That is, the resin flow length differs on both sides with respect to the reference plane. In this case, the resin flows relatively easily in the portion where the resin flow length is shorter (near the gate), but in the portion where the resin flow length is longer (the portion far from the gate), the temperature at the tip becomes lower and harder. Therefore, it becomes difficult for the resin to flow. As a result, there is a problem that it is difficult to mold the optical prism into a shape that is substantially symmetrical with respect to the reference surface, and an optical prism with high molding accuracy cannot be realized.

  The present invention has been made to solve the above-described problems, and its purpose is to make the gate position substantially symmetric with respect to a reference plane crossing the entrance surface, the reflection surface, and the exit surface. An optical prism that can be reliably molded into a precise shape and can achieve high molding accuracy, a method of manufacturing the optical prism, a cemented prism formed by bonding the optical prism and another optical prism, An object of the present invention is to provide a video display device including the cemented prism, an HMD including the video display device, and a video imaging device including the cemented prism.

  An optical prism according to the present invention is an optical prism that reflects light incident from an incident surface on a reflecting surface and emits the light to the outside through an exit surface, and includes an entrance surface, a reflective surface, and an intersection of each surface of the exit surface. It is characterized in that it is formed by pouring a resin into a mold through a gate provided at any one of them and curing the resin. The optical prism of the present invention is an optical prism that reflects light incident from the incident surface on the reflecting surface and emits the light to the outside through the emitting surface, and intersects each surface of the incident surface, the reflecting surface, and the emitting surface. One of the parts is provided with a gate serving as an inlet when the resin is poured into the mold.

  The optical prism manufacturing method of the present invention is a method for manufacturing an optical prism in which light incident from the incident surface is reflected by the reflecting surface and is emitted to the outside through the emitting surface, and includes the incident surface, the reflecting surface, and the emitting surface. It is characterized in that a resin is poured into a mold through a gate provided at any of the intersections of the surfaces, and the resin is cured.

  According to the above configuration, the entrance surface, the reflection surface, and the exit surface can be obtained by pouring the resin into the mold through the gate provided at any of the intersections of the entrance surface, the reflection surface, and the exit surface. The resin can be poured evenly on both sides with respect to the crossing reference plane. That is, the flow and spread of the resin can be made equal on both sides with respect to the reference plane. Accordingly, an optical prism whose overall shape is substantially symmetric with respect to the reference plane can be reliably obtained using the corresponding mold, and an optical prism with high molding accuracy can be realized.

  An optical prism of the present invention is an optical prism that reflects light incident from an incident surface on a reflecting surface and emits the light to the outside through an exit surface, and includes an entrance surface, a reflective surface, and ridges on each surface of the exit surface. Among them, it is characterized in that it is formed by pouring a resin into a mold through a gate provided on any of the ridge lines intersecting the reference plane crossing each of the above surfaces, and curing the resin. The optical prism of the present invention is an optical prism that reflects light incident from the incident surface on the reflecting surface and emits the light to the outside through the emitting surface, and the ridgeline of each surface of the incident surface, the reflecting surface, and the emitting surface Among the portions, a gate serving as an entrance when the resin is poured into the mold is provided at any one of the ridge lines intersecting the reference plane crossing each of the above surfaces.

  The optical prism manufacturing method of the present invention is a method for manufacturing an optical prism in which light incident from the incident surface is reflected by the reflecting surface and is emitted to the outside through the emitting surface, and includes the incident surface, the reflecting surface, and the emitting surface. A resin is poured into a mold through a gate provided at any of the ridge line portions intersecting the reference plane crossing each surface among the ridge line portions of each surface, and the resin is cured. .

  According to said structure, the gate used as the entrance for flowing resin into a metal mold | die is a ridgeline which cross | intersects the reference plane which crosses each said surface among the ridgeline parts of each surface of an incident surface, a reflective surface, and an output surface Since the resin is provided in any one of the portions, the resin can be poured uniformly on both sides of the reference surface by pouring the resin into the mold through the gate. That is, the flow and spread of the resin can be made equal on both sides with respect to the reference plane. Accordingly, an optical prism whose overall shape is substantially symmetric with respect to the reference plane can be reliably obtained using the corresponding mold, and an optical prism with high molding accuracy can be realized.

  In the optical prism of the present invention, it is desirable that the entrance surface, the reflection surface, and the exit surface are formed substantially symmetrically with respect to a reference surface that crosses them. In this case, the overall shape of the optical prism can be reliably made substantially symmetrical with respect to the reference plane.

  In the optical prism of the present invention, it is desirable that the gate is formed substantially symmetrically with respect to a reference plane that crosses the entrance surface, the reflection surface, and the exit surface. In this case, the resin can be poured evenly on both sides with respect to the reference surface through the gate, and an optical prism with high molding accuracy can be reliably realized.

  The optical prism of the present invention further includes a facing surface disposed to face the exit surface, and one end of the reflecting surface is connected to the exit surface while the other end is connected to the facing surface. The opposite side of the opposing surface to the connecting surface with the reflecting surface is connected to the incident surface via the connecting surface, and the gate is formed at the intersection of the incident surface and the connecting surface. There may be.

  For example, when the optical prism of the present invention is applied to a video display device having a video display element (for example, LCD), that is, when the light from the video display element is guided to the observer's pupil via the optical prism. In addition, the gate is located near the image display element. The closer to the image display element, the smaller the incident light beam to the optical prism (the light beam width is narrow), so the influence of the surface near the gate on the optical performance (for example, resolution) is reduced, realizing an image display device with good optical performance. It becomes possible to do.

  In the optical prism of the present invention, it is preferable that the distance between the gate and the exit surface is larger than the distance between the facing surface and the exit surface. In this case, since the shape (thickness) in the vicinity of the gate in the optical prism is thicker than between the facing surface and the exit surface, the curing rate of the resin in the vicinity of the gate during molding is slow. As a result, the resin can be surely poured into a position far from the gate, and the end on the reflection surface side far from the gate can be accurately molded.

  In the optical prism of the present invention, it is desirable that the gate is provided to be inclined with respect to both the incident surface and the opposing surface. In this case, at the time of molding, since the resin can be poured into the mold along both the incident surface and the opposing surface via the gate, it is possible to ensure both the molding accuracy of the two surfaces.

  In the optical prism of the present invention, the facing surface intersects the reflecting surface at an obtuse angle, and the gate is formed so that an angle formed relative to the reflecting surface is smaller than 45 degrees. desirable. In this case, since the gate approaches parallel to the reflecting surface, the resin can be surely poured into the end of the reflecting surface (prism tip) at the time of molding, and the molding accuracy of the reflecting surface can be ensured satisfactorily. . Since the reflective surface has a larger influence on the optical performance than the transmissive surface, according to the above configuration, an optical prism with good optical performance can be realized.

  The optical prism of the present invention includes a first prism portion including an entrance surface and a second prism portion including an exit surface, and the first prism portion is located on the entrance surface side and includes the entrance surface and the reflection surface. The width in the direction perpendicular to the reference plane crossing the surface and the exit surface is narrower than the second prism portion, and the width in the direction perpendicular to the reference surface is located on the second prism portion side. Even with a configuration in which the side surface of the narrow portion and the surface on the narrow portion side in the constant width portion are connected via a curved surface portion. Good.

  In this configuration, the resin that flows from the gate and flows in the vicinity of the curved surface portion during molding can flow along the shape of the curved surface portion. Thereby, resin can be spread to every corner in the width direction, and an optical prism with high molding accuracy in the width direction can be realized. Therefore, it is possible to form the incident surface and the exit surface having different sizes according to the optically required size, and the optical prism can be made smaller and lighter.

  At this time, it is desirable that the curved surface portion has a shape having a curvature that increases in width from the first prism portion side toward the second prism portion side. In this case, it is possible to reliably flow the resin along the shape of the curved surface portion at the time of molding, and it is possible to reliably realize an optical prism with high molding accuracy in the width direction.

  The optical prism of the present invention is preferably separated from the mold by curing the resin poured into the mold and protruding the gate with an eject pin. In the method for producing an optical element of the present invention, it is preferable that the optical prism is separated from the mold by protruding the gate with an eject pin after the resin is cured.

  When separating the optical prism from the mold, for example, if the center of any of the entrance surface, reflection surface, and exit surface is ejected with an ejector pin, the projected surface remains and the quality of the appearance is impaired. At the same time, the optical properties of the surface deteriorate. In particular, when an optical prism is applied to, for example, an image display device, the image quality deteriorates due to a decrease in the optical characteristics of the surface. In addition, when the optical prism of the present invention is joined to, for example, another optical prism to form a cemented prism, the optical prism of the present invention is a surface other than the entrance surface, the reflective surface, and the exit surface, When the joint surface is protruded with an ejector pin, the appearance quality of the surface is impaired, and the joint strength on the surface cannot be sufficiently obtained.

  However, in the present invention, the gate intersects any of the intersections of the optical surfaces (incidence surface, reflection surface, exit surface) (or the reference surface that crosses each optical surface in the ridge line portion of each optical surface). One of the ridge lines). That is, the gate is provided in a portion of the optical prism that does not affect the appearance quality, the image quality, and the bonding strength. Accordingly, by projecting the gate provided at such a position with the eject pin, it is possible to avoid a decrease in appearance quality, video quality and bonding strength.

  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.

  In the cemented prism of the present invention, the first optical prism may be configured to be joined to the second optical prism via an optical element disposed on the reflection surface. In this case, for example, if a hologram optical element having a diffraction reflection function is used as the optical element, the reflection surface of the first optical prism can surely have a reflection function.

  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 provided 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 image display device according to the aspect of the invention, the first optical prism may totally reflect the image light from the image display element incident from the incident surface on the exit surface and the facing surface facing the reflected surface. The structure which guides may be sufficient. In this configuration, since the total reflection in the first optical prism is used, the first 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. In 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 according to the present invention includes an image pickup device that picks up a subject image and a cemented prism that guides light of the subject image to the image sensor, and the joint prism includes a first optical prism and a second optical prism. The first optical prism is composed of the above-described optical prism of the present invention, and is joined to the second optical prism via an optical element disposed on the reflection surface thereof. The optical element is a volume phase type reflection hologram optical element, and after reflecting light of a subject image incident on the first optical prism of the cemented prism by the hologram optical element, a plurality of optical elements are internally provided. It is characterized in that the light of the external image transmitted through the hologram optical element is guided to the observer's eye at the same time as being reflected by the total reflection and emitted to the outside.

  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. Furthermore, 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, since the resin can be poured evenly on both sides with respect to the reference surface crossing the entrance surface, the reflection surface, and the exit surface, the entire shape is relative to the reference surface using a corresponding mold. A substantially symmetric optical prism can be reliably obtained, 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. 1A), 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. 1A), which will be described later, at the time of 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. In FIGS. 5A and 5B, the gate 61 (see FIG. 11A), 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.

  By the way, the surfaces 22d and 22f of the eyepiece prism 22 may be substantially perpendicular to the surface 22b, and the surfaces 23d and 23f of the deflection prism 23 may be substantially perpendicular to the surface 23b. By tilting at least one of the surfaces 22d, 22e, and 22f of the eyepiece prism 22 with respect to the surface 22b, or by tilting at least one of the surfaces 23d, 23e, and 23f of the deflection prism 23 with respect to the surface 23b, FIG. As shown in FIG. 6B, it is possible to prevent 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 observer's eyes. 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.

(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. FIG. 1A is a cross-sectional view of the eyepiece prism 22 at the time of injection molding, FIG. 1B 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.1 (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. 1B).

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. 1 (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.

The position where the gate 31 is provided is not limited to the ridge line portion 22a ₁ of the surface 22a described above as long as it is a ridge line portion intersecting with the reference plane S. For example, the intersection of the surface 22a and the surface 22b (ridge line portion on the surface 22b side in the surface 22a), the intersection of the surface 22b and the surface 22e (ridge line portion on the surface 22e side in the surface 22b), the surface 22e and the surface 22c, Alternatively, a gate 31 may be provided at the intersection (the ridge line portion on the surface 22c side of the surface 22e) so that the resin is poured into the mold. In any of these cases, since the resin can be poured evenly on both sides with respect to the reference plane S, an eyepiece prism 22 that is substantially symmetrical with respect to the reference plane S can be reliably obtained, and the eyepiece with high molding accuracy. The prism 22 can be realized. Further, even if the gate 31 is provided as described above, the gate 31 does not affect the optical characteristics (reflection characteristics, transmission characteristics) on the surfaces 22e and 22b, and the optical characteristics of these surfaces are deteriorated. There is no.

From the above, the ocular prism 22, surface 22a, one of each side of the intersection of the surface 22e and the surface 22b (ridge 22a ₁ described above can be considered as the intersection of the plane 22a and the plane 22e) It can be said that it may be formed by pouring a resin into a mold through a gate 31 provided in the substrate and curing the resin. Further, the eyepiece prism 22 is connected via a gate 31 provided in any one of the ridge line portions of the surfaces 22a, 22e, and 22b that intersect with the reference surface S that crosses each of the surfaces. It can be said that it may be formed by pouring a resin into a mold and curing the resin.

In particular, as described above, if the gate 31 is provided at the ridgeline portion 22a ₁ , that is, the intersection of the surface 22a and the surface 22i, in the video display device 1, the gate 31 is positioned relatively close to the LCD 15. Therefore, the image display device 1 with good optical performance can be realized, which is desirable. That is, the closer to the LCD 15, the smaller the incident light beam on the eyepiece prism 22 (the narrower the light beam width), the less the influence of the surface near the gate 31 on the optical performance (for example, resolution), and the video display with good optical performance. The device 1 can be realized.

  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.

Incidentally, when the gate 31 is provided in the ridge portion 22a _1, the distance between the gate 31 and the surface 22b is greater than the distance between the surface 22c and the surface 22b. That is, the eyepiece prism 22 has a shape (thickness) near the gate 31 that is thicker than between the surface 22c and the surface 22b. In this case, when the resin is poured into the mold through the gate 31, the curing speed of the resin near the gate 31 is slow. Therefore, the resin can surely be poured into an end portion far from the gate 31 (intersection portion of the surface 22e with the surface 22b), and such an end portion can be accurately molded.

  Moreover, in this embodiment, as shown to Fig.1 (a), the gate 31 is provided inclining with respect to both the surface 22a and the surface 22c. In this case, at the time of molding, the resin can be poured into the mold along both the surface 22a and the surface 22c via the gate 31, so that the molding accuracy of the two surfaces can be ensured together.

  In the present embodiment, the surface 22c intersects the surface 22e at an obtuse angle, and the gate 31 is formed such that the angle formed relative to the surface 22e is smaller than 45 degrees. In this case, since the gate 31 approaches parallel to the surface 22e, the resin can surely flow into the end of the surface 22e (prism tip) at the time of molding, and the molding accuracy of the surface 22e can be ensured satisfactorily. it can. The surface 22e functions as a reflecting surface as described above. However, since the reflecting surface has a larger influence on the optical performance than the transmitting surface, the relative angle between the gate 31 and the surface 22e as described above. By setting this, it is possible to realize an eyepiece prism 22 with good optical performance.

  In this embodiment, the eyepiece prism 22 is separated from the mold by protruding the gate 31 with the eject pin 41 after the resin poured into the mold is cured. In the present embodiment, the gate 31 is provided at any of the intersections of the optical surfaces (surfaces 22a, 22e, and 22b) (or any of the ridge lines that intersect the reference surface S on the optical surface). The eyepiece prism 22 is provided at a portion that does not affect the appearance quality, the image quality, and the bonding strength with the deflection prism 23. Accordingly, by projecting the gate 31 provided at such a position with the eject pin 41, it is possible to avoid a decrease in appearance quality, video quality and bonding strength.

  By the way, when separating the eyepiece prism 22 from the mold, the following method may be adopted. That is, as shown in FIG. 7, the fixed pin is also provided with an eject pin 51, and the eject pin 51 protrudes, for example, the surface 22g of the eyepiece prism 22 from the fixed die, while the ejector 51 ejects from the movable die. A pin 41 projects the gate 31 of the eyepiece prism 22. In this way, when the movable mold is pulled away from the fixed mold, either the eyepiece prism 22 is caught by the movable mold or the fixed mold, either eject pin Thus, the eyepiece prism 22 can be projected, and the eyepiece prism 22 can be reliably separated from the mold. As shown in FIG. 8, the ejector pin 51 is provided only on the fixed mold, and the surface 22g of the eyepiece prism 22 is projected from the fixed mold by the ejector pin 51, so that the eyepiece prism 22 is removed from the mold. Of course, it does not matter even if the method of separating is adopted.

  Further, the fixed side mold and the movable side mold shown in FIG. 1C may be a movable side mold and a fixed side mold, respectively. In other words, in this case, as shown in FIG. 9, the movable pin is provided with an eject pin 42, and the eject pin 42 projects the surface 22g of the eyepiece prism 22 so that the eyepiece prism 22 is moved from the movable die. Will be separated.

  FIG. 10A is a plan view showing another configuration example of the eyepiece prism 22, and FIG. 10B is an explanatory diagram showing a method for separating the eyepiece prism 22 from the mold. The eyepiece prism 22 shown in FIG. 1A is the same as that shown in FIG. 1 except that the surfaces 22d and 22f are extended toward the surface 22a so that the first prism portion 22A and the second prism portion 22B have the same width. The configuration is the same as that of the eyepiece prism 22 in FIG.

In the configuration of the eyepiece prism 22 shown in FIG. 10A, the exposed portions 22d ₁ and 22f ₁ are exposed on the surfaces 22d and 22f without being in contact with the surfaces 23d and 23f at the time of joining with the deflection prism 23. Since the exposed portions 22d ₁ and 22f ₁ are portions that do not contact the surfaces 23d and 23f of the deflecting prism 23, it is not necessary to request flatness. Therefore, when the eyepiece prism 22 is molded, after the resin poured into the mold is cured, the exposed portions 22d ₁ and 22f ₁ are ejected by the eject pin 43 to separate the eyepiece prism 22 from the movable mold. You may do it.

  The effects of the present embodiment described above can be obtained if the eyepiece prism 22 has at least a surface 22a that is an incident surface, a surface 22e that is a reflecting surface, and a surface 22b that is an exit surface. it can. That is, for example, in the eyepiece prism 22, there is no surface 22c that faces the exit surface, and there are only three surfaces that intersect the reference surface S: the entrance surface, the reflection surface, and the exit surface, and the eyepiece prism 22 alone is an eyepiece optical system. Even in the case of configuring 21, the present invention in which the gate 31 is provided at a predetermined ridge line portion can be applied, and even in this case, the effect of the present embodiment described above can be obtained.

(5. About manufacturing method of deflection prism)
Next, a method for manufacturing the deflection prism 23 will be described. FIG. 11A is a plan view of the deflection prism 23 illustrating the gate 61, FIG. 11B 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. Accordingly, the resin can easily enter the sharpened portion (for example, the intersection of the surface 23e and the surface 23c) of the deflecting prism 23, the sharp edge transferability (the sharpness of the sharpened portion), and the joint surface (the surfaces 23d, 23e, and 23). 23f) and the surface accuracy of 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. 12 is an explanatory diagram showing a schematic configuration of the video imaging apparatus 81 of 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.

  As shown in FIG. 13, 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. 12, 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 (eyepiece prism) of the present invention can be used for a cemented prism with a deflection prism, a video display device, a video imaging device, an HMD, and the like.

(A) is sectional drawing at the time of injection molding of the eyepiece prism of the eyepiece optical system which comprises the video display apparatus of HMD which concerns on one Embodiment of this invention, (b) is at the time of injection molding of the said eyepiece prism. (C) is explanatory drawing which shows the method of isolate | separating the said eyepiece prism from a metal mold | die. (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, (b) is a bottom view of the eyepiece prism, (c) is a front view of the eyepiece prism, and (d) is the eyepiece prism. (E) is a side view of the eyepiece prism. (A) is a top view of the deflection prism of the eyepiece optical system, and (b) is a front view of the 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 explanatory drawing which shows the other example of the method of isolate | separating the said eyepiece prism from a metal mold | die. It is explanatory drawing which shows the further another example of the method of isolate | separating the said eyepiece prism from a metal mold | die. It is explanatory drawing which shows the further another example of the method of isolate | separating the said eyepiece prism from a metal mold | die. (A) is a top view which shows the other structural example of the said eyepiece prism, (b) is explanatory drawing which shows the method of isolate | separating the said eyepiece prism from a metal mold | die. (A) is a plan view of the deflection prism illustrating the gate of the eyepiece optical system, (b) is a front view of the deflection prism, and (c) is a view of the deflection prism during injection molding. It is sectional drawing. 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 (first optical prism)
22a surface (incident surface)
22a ₁ ridgeline (intersection)
22b surface (exit surface)
22c surface (opposite surface)
22e surface (reflective surface)
22g surface 22i surface (connection surface)
22j surface 22k curved surface portion 22A first prism portion 22A ₁ narrow portion 22A ₂ equal width portion 22B second prism portion 23 deflection prism (second optical prism)
24 optical element 31 gate 41 eject pin 81 video imaging device 82 cemented optical prism (joint prism)
84 Image sensor 91 First optical prism 92 Second optical prism 93 Optical element S Reference plane

Claims (24)

An optical prism that reflects light incident from an incident surface on a reflecting surface and emits the light to the outside through an exit surface,
An optical prism formed by pouring a resin into a mold through a gate provided at any of intersections of the incident surface, the reflecting surface, and the exit surface, and curing the resin . An optical prism that reflects light incident from an incident surface on a reflecting surface and emits the light to the outside through an exit surface,
An optical prism characterized in that a gate serving as an entrance when a resin is poured into a mold is provided at any of intersections of the incident surface, the reflecting surface, and the exit surface. An optical prism that reflects light incident from an incident surface on a reflecting surface and emits the light to the outside through an exit surface,
A resin is poured into a mold through a gate provided on any one of the ridge line portions of each of the incident surface, the reflection surface, and the emission surface that intersects the reference surface that crosses each of the surfaces. An optical prism formed by curing. An optical prism that reflects light incident from an incident surface on a reflecting surface and emits the light to the outside through an exit surface,
Of the ridge line portions of each of the incident surface, the reflective surface, and the exit surface, a gate serving as an entrance for pouring the resin into the mold is provided at any of the ridge line portions intersecting with the reference surface crossing each of the above surfaces. An optical prism characterized by that.   5. The optical prism according to claim 1, wherein the incident surface, the reflective surface, and the exit surface are formed substantially symmetrically with respect to a reference surface that crosses the incident surface, the reflective surface, and the exit surface.   6. The optical prism according to claim 1, wherein the gate is formed substantially symmetrically with respect to a reference plane crossing the entrance surface, the reflection surface, and the exit surface. It further has a facing surface that is disposed to face the emission surface,
One end of the reflective surface is connected to the exit surface, while the other end is connected to the opposing surface,
The opposite side of the opposite surface to the connection side with the reflection surface is connected to the incident surface through the connection surface,
7. The optical prism according to claim 1, wherein the gate is formed at an intersection between the incident surface and the coupling surface.   The optical prism according to claim 7, wherein a distance between the gate and the exit surface is larger than a distance between the facing surface and the exit surface.   9. The optical prism according to claim 7, wherein the gate is provided to be inclined with respect to both the incident surface and the opposing surface. The facing surface intersects the reflecting surface at an obtuse angle,
10. The optical prism according to claim 9, wherein the gate is formed so that an angle formed relative to the reflecting surface is smaller than 45 degrees. A first prism portion including an incident surface;
A second prism portion including an exit surface,
The first prism unit is located on the incident surface side and has a narrower width in the direction perpendicular to the reference surface that intersects the incident surface, the reflective surface, and the exit surface, and is narrower than the second prism unit, and the second prism unit And a constant width portion whose width in the direction perpendicular to the reference plane is the same as that of the second prism portion,
11. The optical prism according to claim 1, wherein the side surface of the narrow portion and the surface on the narrow portion side in the equal width portion are connected via a curved surface portion.   The optical prism according to claim 11, wherein the curved surface portion has a shape having a curvature that increases in width from the first prism portion side toward the second prism portion side.   13. The optical prism according to claim 1, wherein after the resin poured into the mold is cured, the gate is separated from the mold by protruding the gate with an eject pin. A method of manufacturing an optical prism that reflects light incident from an incident surface on a reflecting surface and emits the light to the outside through an exit surface,
A method for manufacturing an optical prism, comprising: pouring a resin into a mold through a gate provided at any of intersections of an incident surface, a reflective surface, and an exit surface, and curing the resin. A method of manufacturing an optical prism that reflects light incident from an incident surface on a reflecting surface and emits the light to the outside through an exit surface,
The resin is poured into the mold through a gate provided at any of the ridge line portions intersecting with the reference surface crossing each of the ridge line portions of the incident surface, the reflection surface, and the exit surface, A method for producing an optical prism, characterized by curing.   16. The method of manufacturing an optical prism according to claim 14, wherein the optical prism is separated from the mold by protruding the gate with an eject pin after the resin is cured. A cemented prism formed by cementing a first optical prism and a second optical prism,
The cemented prism, wherein the first optical prism is configured by the optical prism according to any one of claims 1 to 13.   The cemented prism according to claim 17, wherein the first optical prism is joined to the second optical prism via an optical element disposed on a reflection surface thereof. 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 18,
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.   20. The video display device according to claim 19, wherein the optical element of the cemented prism is a volume phase reflection hologram optical element.   21. The image display device according to claim 20, wherein the hologram optical element has an axially asymmetric optical power.   The first optical prism guides the image light incident from the incident surface from the image display element to the reflection surface by totally reflecting the light from the exit surface and the facing surface opposite to the exit surface. 21. The video display device according to any one of 21. The video display device according to any one of claims 19 to 22,
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 for guiding the light of the subject image to the image sensor,
The junction prism is formed by joining a first optical prism and a second optical prism,
The first optical prism is constituted by the optical prism according to any one of claims 1 to 6, and is joined to the second optical prism via an optical element disposed on a reflection surface thereof. ,
The optical element is a volume phase reflection hologram optical element,
After the light of the subject image incident on the first optical prism of the cemented prism is reflected by the hologram optical element, it is totally internally reflected a plurality of times and emitted to the outside, and is 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.

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