JP5732808B2 - Virtual image display device - Google Patents

Description

  The present invention relates to a virtual image display device such as a head mounted display that is used by being mounted on a head.

  2. Description of the Related Art In recent years, various types of virtual image display devices that enable formation and observation of virtual images, such as a head-mounted display, have been proposed that guide video light from a display element to an observer's pupil using a light guide plate. As such a virtual image display device, there is one in which a half mirror is provided on the optical path of the display device so that the outside world can be seen simultaneously with the displayed image (see Patent Documents 1 and 2).

  In such a device, when the external light is bright, the brightness of the video is lower than that of the external light, so that the contrast of the video is lowered and is difficult to see. In order to improve this, there is a light shielding member that blocks external light, and the light shielding member is taken in and out of the half mirror as required (see Patent Document 3).

  As a virtual image display device of a different type from the above, it has a thin light guide plate that guides image light using total reflection, and is arranged parallel to each other at a predetermined angle with respect to the main surface of the light guide plate. It is known that image light is reflected by a plurality of partial reflection surfaces and extracted from a light guide plate to reach the observer's retina (see Patent Documents 4 and 5).

JP-T-2001-522477 Japanese Patent Laid-Open No. 5-303053 JP-A-5-325265 Special table 2003-536102 gazette JP 2004-157520 A

  However, in the case of a virtual image display device in which the light shielding member is taken in and out in front of the half mirror, the light shielding member protrudes and obstructs when the light shielding member is not used, and the operation of taking in and out the light shielding member is inconvenient.

  In the case of a virtual image display device using a light guide plate, it is often worn like glasses, and it is impossible to add a light shielding member with a bulky mechanism for taking in and out.

  Therefore, the present invention provides a virtual image display device using a light guide plate, which can observe the outside world and can prevent the observation of images from being disturbed by outside light by a simple method. With the goal.

In order to solve the above problems, a virtual image display device according to the present invention is (a) a light guide plate that allows at least a part of external light to pass to the observation side, and (b) an opposition to the external side of the light guide plate. An optical element that adjusts the transmission state of the external light; and (c) a light control unit that electrically controls the operation of the optical element, and the light guide plate includes (a1) a light incident unit that captures image light inside And (a2) a light guide unit having first and second total reflection surfaces extending opposite to each other, and guiding image light taken in from the light incident unit by total reflection on the first and second total reflection surfaces And (a3) an image take-out unit that has a plurality of reflection surfaces arranged in a predetermined arrangement direction and takes out image light incident through the light guide unit by converting the angle by reflection on the plurality of reflection surfaces to the outside. The optical element includes: (b1) a first region that overlaps the image extraction unit in the field of view; and (b2) a plurality of optical elements. A first peripheral area overlapping on ambient and the field excluding the reflecting surface, and a second peripheral area overlapping with the reflective surface and the field on which they do not overlap on the visual field (b3) a plurality of reflecting surfaces sac Chi light exit plane Yes, and the dimming control unit, the transmittance of the first region and the transmittance of the first peripheral region and the transmittance of the second peripheral region independently controlled, the transmittance of the first region and the second peripheral region Is higher than the transmittance of the first surrounding region .

In the virtual image display device, since the optical element disposed facing the outside of the light guide plate adjusts the transmission state of the outside light under the control of the light control unit, in the case where the outside light is relatively strong, It is possible to prevent the observation of images from being hindered by external light. At this time, since the optical element is electrically controlled and does not involve a mechanical mechanism, an operation for adjusting the transmission state of external light becomes relatively simple. Further, since the optical element has the first region, the first peripheral region, and the second peripheral region, the optical element has a transmittance between the transmittance of the light guide unit with respect to the ambient light and the transmittance of the plurality of reflecting surfaces with respect to the ambient light. Even if there is a difference, the difference between the first region and the second surrounding region and the first surrounding region can be apparently reduced by providing a transmittance difference as an offset.

  In a specific aspect of the present invention, in the virtual image display device, the optical element is any one of an electrochromic element, a liquid crystal panel, and a transmissive voltage element. In this case, accurate and wide-range transmittance control is possible with a small element.

  In still another aspect of the present invention, the optical element is a thin plate-like member disposed so as to cover the light guide plate on the outside side in the vicinity of the light guide plate. In this case, the light guide plate can be protected by an optical element in a space-saving manner, and contact with the surface of the light guide plate, adhesion of dirt, and the like can be effectively prevented.

  In yet another aspect of the present invention, the optical element has a first region that overlaps the visual extraction portion of the light guide plate and overlaps the visual extraction portion, and a second region that does not overlap the visual extraction portion of the optical extraction portion, The dimming control unit controls the transmittance of the first region and the transmittance of the second region independently. In this case, the transmittance of the first region where the image by the image light and the external image by the external light overlap can be controlled independently from the surroundings, and the relationship between the video and the external image can be adjusted as appropriate.

  In still another aspect of the present invention, the dimming control unit adjusts the transmittance of the first region and the transmittance of the two regions to thereby adjust the image light emitted from the image extraction unit and the external light from the back. Superimposing mode that superimposes the light to the observation side, image light priority mode that prioritizes the image light emitted from the image take-out unit by totally shielding the external light, and the external light by totally transmitting the external light At least one of an ambient light priority mode and a sectioning mode in which the transmittance of the two regions is made higher than the transmittance of the first region to guide the ambient light and the image light to the observation side by region. Operate in mode. In this case, the display balance between the image by the image light and the external image by the external light can be adjusted according to the environment and preference in which the user is placed.

  In still another aspect of the present invention, an external light sensor that detects the intensity of external light is provided, and the dimming control unit changes the transmittance of the optical element based on the output of the external light sensor. In this case, it is possible to observe an image adjusted according to a change in the brightness of the outside world.

  In still another aspect of the present invention, the dimming control unit decreases the transmittance of the optical element as the intensity of external light increases. In this case, it is possible to suppress adverse effects such as a decrease in the contrast of the image due to the image light buried in the external light.

  In still another aspect of the present invention, the dimming control unit changes the transmittance of the optical element in accordance with the size of the virtual image formed by the image light emitted from the light guide plate. In this case, it is possible to observe an image adjusted according to the size change of the virtual image.

  In still another aspect of the present invention, the dimming control unit reduces the transmittance of the optical element according to the size of the virtual image. In this case, it is possible to suppress adverse effects such as a decrease in luminance and contrast of a virtual image due to image light as the image is enlarged.

It is a perspective view which shows the virtual image display apparatus which concerns on 1st Embodiment. (A) is sectional drawing which shows a part of virtual image display apparatus, (B) and (C) are the rear views and top views, such as a light-guide plate. It is a block diagram explaining the structure of a light control board, and the drive control circuit for driving a light control board etc. FIG. (A)-(C) are typical figures for demonstrating the structure of an angle conversion part, and the optical path of the image light in an angle conversion part. It is a flowchart explaining operation | movement of the virtual image display apparatus which concerns on 1st Embodiment. It is a flowchart explaining operation | movement of a virtual image display apparatus. It is sectional drawing which shows a part of virtual image display apparatus which concerns on 2nd Embodiment. It is a block diagram explaining the drive control circuit etc. of the virtual image display apparatus which concerns on 2nd Embodiment. (A) And (B) is a figure explaining the angle conversion part in a modification.

[First Embodiment]
Hereinafter, a virtual image display device according to a first embodiment of the present invention will be described in detail with reference to the drawings.

[A. Appearance of virtual image display device)
A virtual image display device 100 according to this embodiment shown in FIG. 1 is a head-mounted display having an appearance like glasses, and allows an observer wearing the virtual image display device 100 to recognize image light due to a virtual image. In addition, it is possible to make the observer observe the outside world image with see-through. The virtual image display device 100 includes a pair of optical panels 101 and 102, a frame 104 that supports both optical panels 101 and 102, and a pair of drive units 111 and 112 that are attached to the portion of the frame 104 from the end to the temple. Prepare. Here, the first display device 100A that combines the left optical panel 101 and the drive unit 111 in the drawing is a portion that forms a virtual image for the right eye, and functions alone as a virtual image display device. In addition, the second display device 100B in which the right optical panel 102 and the drive unit 112 in the drawing are combined is a portion that forms a virtual image for the left eye, and functions alone as a virtual image display device.

[B. (Structure of display device on one side)
As shown in FIG. 2A, the first display device 100A includes an image forming device 10, a light guide plate 20, and a light control plate 40. Here, the image forming apparatus 10 corresponds to the drive unit 111 in FIG. 1, and the light guide plate 20 and the light control plate 40 correspond to the optical panel 101 in FIG. 1. The light control plate 40 is slightly larger than the light guide plate 20 and is disposed so as to entirely cover the front side of the light guide plate 20, that is, the outside. 2A corresponds to the AA cross section of the light guide plate 20 and the light control plate 40 shown in FIG. 2B.

  The image forming apparatus 10 includes an image display device 11 and a projection optical system 12. Among these, the image display device 11 includes an illumination device 31 that emits two-dimensional illumination light, and a liquid crystal display device 32 that is a transmissive spatial light modulator. First, the illumination device 31 includes a light source 31a that generates light SL including three colors of red, green, and blue, a backlight light guide unit 31b that diffuses the light SL from the light source 31a into a light beam having a rectangular cross section, An emission angle adjusting member 31c that corrects the light distribution characteristics of the illumination light emitted from the backlight light guide unit 31b to an appropriate one in consideration of utilization efficiency. The liquid crystal display device 32 spatially modulates the illumination light from the illumination device 31 to form image light to be a display target such as a moving image. The projection optical system 12 is a collimating lens that converts image light emitted from each point on the liquid crystal display device 32 into light beams in a parallel state.

  The overall appearance of the light guide plate 20 is formed by a light guide plate body 20a which is a flat plate extending parallel to the YZ plane in the drawing. In addition, the light guide plate 20 includes an angle conversion unit 23 configured by a number of semi-transmissive micromirrors embedded in the light guide plate main body 20a at one end in the longitudinal direction, and the light guide plate main body at the other end in the longitudinal direction. It has a structure having a prism part PS formed so as to extend the part 20a and an incident light bending part 21 associated therewith.

  The light guide plate main body 20a is formed of a light-transmitting resin material or the like, and takes in image light from the image forming apparatus 10 on the back side or the observation side plane parallel to the YZ plane and facing the image forming apparatus 10. It has a light incident surface IS that is an incident portion, and a light exit surface OS that is a light exit portion that emits image light toward the observer's eye EY. The light guide plate main body 20a has a rectangular inclined surface RS in addition to the light incident surface IS as a side surface of the prism portion PS. Further, in the light guide plate main body 20a, an angle conversion unit 23 having a fine structure is formed between the light exit surface (light exit portion) OS and the surface on the front side or the outside surface facing the OS, and close to the plane. Has been. The light observation surface OS on the back observation side and the rectangular portion overlapping the light emission surface OS in the field of view on the outer side angle conversion unit 23 on the front side convert the angle of the image light to the outside (specifically, It functions as an image extraction unit 90 for extraction to the back side (that is, the observation side).

  The incident light bending portion 21 as the mirror layer 21a disposed to be inclined and opposed to the light incident surface IS of the light guide plate main body portion 20a is formed by depositing aluminum vapor deposition or the like on the slope RS of the light guide plate main body portion 20a. It is formed by applying, and functions as a reflection surface for reflecting incident light and bending the optical path in a predetermined direction close to a substantially orthogonal direction. In other words, the incident light bending portion 21 bends the image light that is incident from the light incident surface IS that is the light incident portion and travels in the −X direction as a whole toward the + Z direction that is biased in the + X direction as a whole. The image light is reliably coupled into the light guide plate body 20a.

  In addition, the light guide plate main body 20 a receives image light incident on the inside through the incident light bending portion 21 from the incident light bending portion 21 on the entrance side to the angle conversion portion 23 on the back side. It has a light guide 22 for guiding.

  The light guide 22 is a main surface of the flat light guide plate main body 20a and is two planes facing each other and extending in parallel to the YZ plane, and totally reflects the image light bent by the incident light bending portion 21, respectively. The first total reflection surface 22a and the second total reflection surface 22b are provided. Here, it is assumed that the first total reflection surface 22a is on the front side or the outside side far from the image forming apparatus 10, and the second total reflection surface 22b is on the back side or the observation side near the image forming apparatus 10. In this case, the second total reflection surface 22b is a common surface portion with the light incident surface IS and the light exit surface OS. The image light reflected by the incident light bending portion 21 first enters the second total reflection surface 22b and is totally reflected. Next, the image light enters the first total reflection surface 22a and is totally reflected. Hereinafter, by repeating this operation, the image light is guided to the back side of the light guide plate 20, that is, the + Z side where the angle conversion unit 23 is provided. Note that the first and second total reflection surfaces 22a and 22b are not provided with a reflection coating, and external light incident on the total reflection surfaces 22a and 22b from the outside side has a high light transmittance. Pass through 22. That is, the light guide unit 22 is a see-through type capable of seeing through an external image.

  Of the image extraction unit 90, the angle conversion unit 23 is formed on the back side (+ Z side) of the light guide unit 22 along the extension plane of the first total reflection surface 22a and close to the extension plane. The angle conversion unit 23 reflects the image light incident through the first and second total reflection surfaces 22a and 22b of the light guide unit 22 at a predetermined angle and bends it toward the light exit surface OS. That is, the angle conversion unit 23 converts the angle of the image light. Here, it is assumed that the image light first incident on the angle conversion unit 23 is an extraction target as virtual image light. In addition, since the angle conversion unit 23 is formed of a semi-transparent micromirror, the external image can be seen through although there is some light reduction. The detailed structure of the angle conversion unit 23 will be described later with reference to FIG.

  In addition, the refractive index n of the transparent resin material used for the light-guide plate main-body part 20a shall be a high refractive index material of 1.5 or more. By using a transparent resin material having a relatively high refractive index for the light guide plate 20, it becomes easier to guide the image light inside the light guide plate 20, and the angle of view of the image light inside the light guide plate 20 is made relatively small. be able to.

  Since the light guide plate 20 has the above-described structure, the image light emitted from the image forming apparatus 10 and incident on the light guide plate 20 from the light incident surface IS is uniformly reflected by the incident light bending portion 21 and bent. The first and second total reflection surfaces 22a and 22b of the light guide unit 22 are repeatedly totally reflected and travel in a state of having a certain spread substantially along the optical axis OA. By being bent at an angle, it can be taken out and finally emitted from the light emitting surface (light emitting portion) OS to the outside. The image light emitted to the outside from the light exit surface OS enters the observer's eye EY as virtual image light. By forming the virtual image light on the retina of the observer, the observer can recognize image light such as video light by the virtual image.

  The light control plate 40 is a thin plate-like optical element, and includes an electrochromic element, a liquid crystal panel, a transmission voltage element, and the like. The dimming plate 40 is disposed near and parallel to the front side of the light guide plate 20, but has a larger area than the light guide plate 20 and covers the light guide plate 20 from the front side, that is, from the outside. Thus, the object is prevented from coming into contact with the surface of the light guide plate 20, that is, the first total reflection surface 22a, causing damage or contamination.

  As shown in FIG. 3, the light control plate 40 is opposed to the image extraction unit 90 or the light exit surface OS of the light guide plate 20 shown in FIG. 1 area A0 is opposed to the surrounding portion of the light guide plate 20 excluding the image extraction unit 90 (the portion adjacent to the image extraction unit 90 in the vertical and horizontal directions on the visual field) and overlaps the image extraction unit 90 in the visual field. And a second region A1 that does not become necessary. Further, the second region A1 includes a first peripheral region A11 that faces a peripheral portion of the light guide plate 20 excluding the angle conversion unit 23 (a portion adjacent to the top, bottom, left, and right of the angle conversion unit 23 on the visual field), and a visual field. It has a pair of rectangular second surrounding areas A12 and A12 facing the upper and lower adjacent parts of the image extraction unit 90 above. The first region A0, the first surrounding region A11, and the second surrounding region A12, A12 can adjust the transmittance independently, but each region A0, A11, A12, A12 The in-plane transmittance is substantially uniform and equal. The light control plate 40 has a structure in which an electrochromic substance is sandwiched between a pair of flat glass plates on which transparent electrodes are formed, although illustration is omitted when the light control plate 40 is configured by, for example, an electrochromic element. Become. Here, by appropriately setting the outline of the transparent electrode, the first area A0, the first surrounding area A11, and the second surrounding areas A12 and A12 as described above are formed, and these are driven independently. can do. Further, when the light control plate 40 is constituted by a transmissive liquid crystal display device, the light control plate 40 is not shown in the figure, but a liquid crystal in which liquid crystal molecules are sandwiched between a pair of flat glass plates on which transparent electrodes are formed. A panel and a pair of polarizing filter affixed on the surface and back surface of a liquid crystal panel are provided. Furthermore, when the light control plate 40 is configured by a guest-host type liquid crystal display device, the light control plate 40 is not shown in the figure, but it is sufficient to have a structure in which liquid crystal molecules and dye molecules are sandwiched in the liquid crystal panel. The polarizing filter can be omitted. In addition, when the light control plate 40 is configured by a transmissive piezoelectric element, the light control plate 40 is obtained by sandwiching a plate-like member having a Pockels effect between transparent electrodes and arranging a pair of polarizing filters on the outside thereof.

  In the above, the first area A0 corresponds to the image extraction unit 90, and when the external light is bright as in the outdoors, if the transmittance of the first area A0 is increased, the image light from the image extraction unit 90 is external light. There is a tendency that the contrast of the image is lowered due to being buried in the screen. On the other hand, the first surrounding area A11 corresponds to the light guide section 22 around the angle conversion section 23 and transmits the outside light almost without dimming. Therefore, when the outside light is bright, the transmittance of the first surrounding area A11 is increased. When the size is increased, the video observed through the image extraction unit 90 becomes darker than the surroundings, and tends to be difficult for the observer to see. As described above, since the appearance of the image varies greatly due to fluctuations in the external light, it is desirable to detect the external light and adjust the transmittance of each of the areas A0, A11, A12, and A12 according to the intensity of the external light. In the case of the present embodiment, there is a difference between the transmittance of the light guide unit 22 with respect to the ambient light and the transmittance of the angle conversion unit 23 with respect to the ambient light around the image extraction unit 90. In order to reduce the appearance, a difference in transmittance as an offset may be provided in advance between the first region A0 and the second surrounding regions A12, A12 and the first surrounding region A11.

  Note that the second display device 100B has the same structure as the first display device 100A only by horizontally inverting the first display device 100A, and therefore the description of the structure of the second display device 100B is omitted.

[C. (Optical path of image light)
First, the cross section shown in FIG. 1A, that is, the optical path in the XZ plane will be described. In the cross section, among the image light emitted from the liquid crystal display device 32, the component indicated by the dotted line emitted from the center portion of the emission surface 32a is the image light GL1, and emitted from the right side (−Z side) of the emission surface 32a. The component indicated by the alternate long and short dash line is image light GL2, and the component indicated by the two-dot chain line emitted from the left side (+ Z side) of the emission surface 32a is image light GL3.

The main components of the image lights GL1, GL2, and GL3 that have passed through the projection optical system 12 are incident on the first and second total reflection surfaces 22a and 22b at different angles after entering from the light incident surface IS of the light guide plate 20, respectively. Repeat total reflection. Specifically, among the image lights GL1, GL2, and GL3, the image light GL1 emitted from the central portion of the emission surface 32a of the liquid crystal display device 32 is reflected by the incident light bending portion 21 as a parallel light flux, The light enters the second total reflection surface 22b of the light guide unit 22 at the standard reflection angle γ ₀ and is totally reflected. Thereafter, the image light GL1 is, while maintaining the standard reflection angle gamma _0, first and second total reflection surface 22a, repeating total reflection at 22b. The image light GL1 is totally reflected N times (N is a natural number) at the first and second total reflection surfaces 22a and 22b, and enters the central portion 23k of the angle conversion unit 23 provided in the image extraction unit 90. The image light GL1 is reflected at a predetermined angle at the central portion 23k, and is emitted as a parallel light flux in the direction of the optical axis AX perpendicular to the YZ plane including the light emission surface OS from the light emission surface OS of the image extraction unit 90. Is done. Further, the image light GL2 emitted from one end side (−Z side) of the emission surface 32a of the liquid crystal display device 32 enters the light incident surface IS as a parallel light flux after passing through the projection optical system 12, and enters the incident light bending portion 21. Then, the light is incident on the second total reflection surface 22b of the light guide unit 22 at the maximum reflection angle γ ₊ and is totally reflected. The image light GL2 is totally reflected, for example, NM times (M is a natural number) on the first and second total reflection surfaces 22a and 22b, and is predetermined in the peripheral portion 23h on the back side (+ Z side) of the angle conversion unit 23. And is emitted from the light exit surface OS as a parallel light beam in a predetermined angle direction. The exit angle at this time is such that it is returned to the incident light bending portion 21 side, and becomes an obtuse angle with respect to the + Z axis. On the other hand, the image light GL3 emitted from the other end side (+ Z side) of the emission surface 32a of the liquid crystal display device 32 enters the light incident surface IS as a parallel light flux after passing through the projection optical system 12, and enters the incident light bending portion 21. Then, the light is incident on the second total reflection surface 22b of the light guide unit 22 at the minimum reflection angle γ ₋ and is totally reflected. The image light GL3 is totally reflected, for example, N + M times at the first and second total reflection surfaces 22a and 22b, and is reflected at a predetermined angle at the peripheral portion 23m on the entrance side (−Z side) of the angle conversion unit 23, The light exits from the light exit surface OS in a predetermined angular direction as a parallel light flux. The exit angle at this time is such that it is away from the incident light bending portion 21 side, and is an acute angle with respect to the + Z axis. In addition, since the reflection efficiency of light by the total reflection at the first and second total reflection surfaces 22a and 22b is very high, the number of reflections differs between the image lights GL1, GL2, and GL3 as described above. However, this hardly causes luminance unevenness, and does not feel the influence of image unevenness or the like on visual recognition.

Here, the reflection angle γ ₊ of the image light GL2 has a maximum value in the light guide plate 20 specification, and the reflection angle γ ₋ of the image light GL3 has a minimum value in the light guide plate 20 specification. Therefore, the total reflection angle of propagation of other effective image light within the light guide plate 20 is a value between these reflection angles γ ₊ and γ ₋ . The difference between the reflection angle range, that is, the maximum reflection angle γ ₊ and the minimum reflection angle γ ₋ corresponds to the horizontal angle of view on the optical design on the image forming apparatus 10 side, that is, the angle of view in the Z direction. ing.

As an example of the value of the refractive index n of the transparent resin material used for the incident light bending portion 21 and the light guide portion 22, when n = 1.5, the value of the critical angle γ _c is γ _c ≈41.8 °. When n = 1.6, the critical angle γ _{c has} a value of γ _c ≈38.7 °. The minimum reflection angle γ ₋ of the reflection angles γ ₀ , γ ₊ , γ ₋ of each of the image lights GL1, GL2, and GL3 is set to a value larger than the critical angle γ _c , thereby guiding the necessary image light. The total reflection condition in the portion 22 can be satisfied.

  The above is the description of the optical path in the transverse section, that is, the XZ plane. Specifically, among the image light emitted from the liquid crystal display device 32, the image lights FL2 and FL3 emitted from the upper and lower sides of the emission surface 32a in the Y direction are converted into parallel light beams by passing through the projection optical system 12, respectively. Are separated from each other in the Y direction (see FIG. 2B). Thereafter, the two image lights FL2 and FL3 are collected so as to be close to the optical axis OA as parallel light beams when passing through the light guide plate 20 while being totally reflected, and also in the angle conversion unit 23 provided in the image extraction unit 90. The light is reflected while maintaining a relative angle, and is finally emitted as a parallel light flux directed from the upper and lower ends of the light exit surface OS of the image extraction unit 90 toward the observer's eye EY.

[D. Angle conversion unit
Hereinafter, the structure of the angle conversion unit 23 and the bending of the optical path of the image light by the angle conversion unit 23 will be described in detail with reference to FIGS.

  First, the structure of the angle conversion unit 23 will be described. The angle conversion unit 23 includes a large number of linear reflection units 23c arranged in a stripe shape. That is, the angle conversion unit 23 is configured by arranging a large number of elongated reflection units 23c extending in the Y direction in the first direction in which the light guide unit 22 extends, that is, the Z direction, at a predetermined pitch PT. Each reflection unit 23c is a first reflection surface 23a that is one reflection surface portion disposed on the back side, that is, the optical path downstream side, and another one reflection surface portion that is disposed on the entrance side, that is, the optical path upstream side. The second reflecting surface 23b is provided as a set. Among these, at least the second reflection surface 23b is a partial reflection surface capable of transmitting a part of light, and allows an observer to observe an external image in a see-through manner. Each reflection unit 23c is formed in a V shape or a wedge shape in the XZ sectional view by the adjacent first and second reflection surfaces 23a and 23b. More specifically, the first and second reflection surfaces 23a and 23b are parallel to the first total reflection surface 22a shown in FIG. 2A and the like and are arranged in the Z direction in which the reflection units 23c are arranged. The second direction, ie, the Y direction extending perpendicularly to the longitudinal direction, is extended linearly. Further, the first and second reflection surfaces 23a and 23b are inclined at different angles (that is, different angles with respect to the YZ plane) with respect to the first total reflection surface 22a with the longitudinal direction as an axis. Yes. As a result, the first reflecting surfaces 23a are periodically and repeatedly arranged and extend in parallel with each other, and the second reflecting surfaces 23b are also periodically and repeatedly arranged and extend in parallel with each other. In the specific example shown in FIG. 4A and the like, each first reflection surface 23a is assumed to extend along a direction (X direction) substantially perpendicular to the first total reflection surface 22a. Each second reflecting surface 23b extends in a direction that forms a predetermined angle (relative angle) α counterclockwise with respect to the corresponding first reflecting surface 23a. Here, the relative angle α is assumed to be, for example, 54.7 ° in a specific example.

  In the specific example shown in FIG. 4A and the like, the first reflecting surface 23a is assumed to be substantially perpendicular to the first total reflecting surface 22a, but the direction of the first reflecting surface 23a is guided. Any tilt angle within a range of, for example, 80 ° to 100 ° clockwise with respect to the −Z direction with respect to the first total reflection surface 22a is appropriately adjusted according to the specifications of the optical plate 20. It can be made. Further, the direction of the second reflecting surface 23b makes any inclination angle within a range of, for example, 30 ° to 40 ° clockwise with respect to the −Z direction with respect to the first total reflecting surface 22a. And can. As a result, the second reflecting surface 23b has any relative angle within the range of 40 ° to 70 ° with respect to the first reflecting surface 23a.

  The reflection unit 23c including the pair of reflection surfaces 23a and 23b is formed, for example, by forming a film such as aluminum vapor deposition on one inclined surface of the underlying V groove, and then filling the resin in the light guide plate 20 by filling with resin. Embedded.

  Hereinafter, bending of the optical path of the image light by the angle conversion unit 23 will be described. Here, among the image light, the image light GL2 and the image light GL3 that enter the both ends of the angle conversion unit 23 are shown, and the other optical paths are the same as these, so the illustration and the like are omitted.

First, as shown in FIGS. 4A and 4B, the image light GL2 guided by the reflection angle γ ₊ having the largest total reflection angle among the image light is the light incident surface IS of the angle conversion unit 23. The light enters the reflection unit 23c disposed in the peripheral portion 23h on the + Z side farthest from (see FIG. 2A). In the reflection unit 23c, the image light GL2 is first reflected by the first reflection surface 23a on the back side, that is, the + Z side, and then reflected by the second reflection surface 23b on the entrance side, that is, the −Z side. The image light GL2 that has passed through the reflection unit 23c is emitted from the light exit surface OS shown in FIG. 1A or the like without passing through the other reflection unit 23c. That is, the image light GL <b> 2 is bent to a desired angle by one pass through the angle conversion unit 23 and extracted to the viewer side.

Further, as shown in FIGS. 4A and 4C, the image light GL3 guided at the reflection angle γ ₋ having the smallest total reflection angle is included in the light incident surface IS (see FIG. The light enters the reflection unit 23c disposed in the peripheral portion 23m on the −Z side closest to (A). In the reflection unit 23c, as in the case of the image light GL2, the image light GL3 is first reflected by the first reflection surface 23a on the back side, that is, the + Z side, and then the second light on the entrance side, that is, the −Z side. Is reflected by the reflecting surface 23b. The image light GL3 that has passed through the reflection unit 23c is bent to a desired angle by one pass through the angle conversion unit 23 without passing through the other reflection unit 23c, and is taken out to the viewer side.

Here, in the case of the two-stage reflection on the first and second reflecting surfaces 23a and 23b as described above, as shown in FIGS. 4B and 4C, when each image light is incident, The bending angle ψ, which is the angle between the direction and the direction at the time of injection, is ψ = 2 (R−α) (R: right angle). That is, the bending angle ψ is constant regardless of the incident angle with respect to the angle conversion unit 23, that is, the values of the reflection angles γ ₀ , γ ₊ , γ _{− and the} like that are the total reflection angles of the respective image lights. Accordingly, as described above, a component having a relatively large total reflection angle in the image light is made incident on the + Z side peripheral portion 23h side of the angle conversion unit 23, and a component having a relatively small total reflection angle is incident on the angle conversion unit. Even when the light beam is incident on the peripheral portion 23m side on the −Z side of the image 23, the image light can be efficiently extracted in an angle state so as to collect the image light as a whole on the eye EY of the observer. Since the configuration is such that the image light is extracted with such an angle relationship, the light guide plate 20 can pass the image light only once without passing through the angle conversion unit 23 a plurality of times, and the image light can be passed through the virtual image with little loss. It can be extracted as light.

In addition, in the optical design such as the shape and refractive index of the light guide 22 and the shape of the reflection unit 23c constituting the angle conversion unit 23, by appropriately adjusting the angle etc. through which the image light GL2, GL3, etc. are guided, The image light emitted from the image extraction unit 90 can be incident on the observer's eye EY as virtual image light with the overall symmetry maintained around the basic image light GL1, that is, the optical axis AX. Here, a angle theta ₂ with respect to the X direction or the optical axis AX of the image light GL2 at one end, the angle theta ₃ with respect to the X direction or the optical axis AX of the image light GL3 at the other end, a substantially equal opposite magnitude It shall be. That is, the image light is emitted to the eye EY in a symmetric state about the optical axis AX. In this way, the angle θ ₂ and the angle θ ₃ are equal to each other and are symmetrical with respect to the optical axis AX, so that the angle θ ₂ and the angle θ ₃ are half the horizontal angle of view. The horizontal half angle of view becomes θ.

  As already described, the first reflecting surface 23a or the second reflecting surface 23b constituting the group of reflecting units 23c have a constant pitch and are parallel to each other. Thereby, the image light which is the virtual image light incident on the eye EY of the observer can be made uniform, and the deterioration of the quality of the observed image can be suppressed. A specific numerical range of the pitch PT that is an interval between the reflection units 23c constituting the angle conversion unit 23 is 0.2 mm or more, and more preferably 0.2 mm to 1.3 mm. By being in this range, the image light to be taken out can be prevented from being affected by diffraction in the angle conversion unit 23, and the lattice fringes by the reflection unit 23c can be made inconspicuous for the observer.

[E. (Drive control circuit)
Hereinafter, the drive control circuit of the virtual image display device 100 will be described with reference to FIG. The drive control circuit 70 includes a light source drive circuit 71, a liquid crystal drive circuit 72, a dimming drive circuit 73, an optical sensor drive circuit 74, and a main control unit 77. The light source drive circuit 71 supplies power to the light source 31a provided in the drive unit 111 of the first display device 100A for the right eye and the light source 131a provided to the drive unit 112 of the second display device 100B for the left eye. And emits light SL having a stable brightness. The liquid crystal driving circuit 72 outputs an image signal or a driving signal to the liquid crystal display device 32 provided in the driving unit 111 of the first display device 100A for the right eye, thereby generating a moving image or a still image as a transmittance pattern. By forming image light of the color to be and outputting an image signal or drive signal to the liquid crystal display device 132 provided in the drive unit 112 of the second display device 100B for the left eye, Color image light that forms the basis of a still image is formed. Note that different images can be formed on the liquid crystal display devices 32 and 132, and for example, a 3D image can be obtained by combining both images. The dimming drive circuit 73 includes a dimming plate 40 provided on the optical panel 101 of the first display device 100A for the right eye, and a dimming plate 40 provided on the optical panel 102 of the second display device 100B for the left eye. An on / off pattern signal is supplied to the light adjusting plate 40 to adjust the transmittance of the two light control plates 40, 40. The optical sensor drive circuit 74 detects signals from the external light sensors 50 and 50 while supplying power to the external light sensors 50 and 50, and detects the intensity of external light around the virtual image display device 100, that is, the observer. . The main control unit 77 operates the light source driving circuit 71 and the liquid crystal driving circuit 72 based on an external control signal or image signal, and causes the image display device 11 including the driving units 111 and 112, that is, the liquid crystal display devices 32 and 132, to be operated. Display operation is performed. The main control unit 77 monitors the output of the optical sensor drive circuit 74 and adjusts the transmittance of the light control plates 40 and 40 to the ambient light and the intention of the observer via the light control drive circuit 73. Adjust as appropriate. Here, each of the light control plates 40, 40 can be controlled independently in the first area A0, the first surrounding area A11, and the second surrounding areas A12, A12, and each of the areas A0, A11, A12, The transmittance of A12 can be matched, but can also be different from each other. The main control unit 77 cooperates with the dimming drive circuit 73 to adjust the transmittance of the dimming plates 40 and 40 in various ways, and the dimming control for electrically controlling the operation of the dimming plates 40 and 40. It functions as a part.

[F. Specific operation example)
Hereinafter, an example of the operation of the virtual image display device 100 will be described with reference to FIGS. 5 and 6. First, the main control unit 77 checks the display mode of the virtual image display device 100 (step S11). As a display mode of the virtual image display device 100, for example, (1) superposition mode, (2) image light priority mode, (3) external light priority mode, (4) segmentation mode, and the like can be set. These display modes can be recorded in a memory (not shown) of the main control unit 77. Here, the superimposing mode superimposes the image light emitted from the image extracting unit 90 and the external light coming from behind the image extracting unit 90 by setting both the light control plates 40 and 40 to standard transmittance. In addition, it is possible to observe by guiding it to the observation side. The image light priority mode gives priority to the observation of the image light emitted from the image extraction unit 90 while totally blocking the external light by reducing the transmittance of the light control plates 40 and 40 as a whole. is there. In the external light priority mode, the transmittance of the first region A0 and the second region A1 of the two light control plates 40, 40 is increased as a whole, and the luminance of the light sources 31a, 131a is decreased, thereby weakening the image light. The external light is transmitted as a whole, and the external light is given priority. In the section mode, the ambient light and the image light are obtained by increasing the transmittance of the second region A1, that is, the first and second surrounding regions A11, A12, and A12, than the transmittance of the first region A0 of both the light control plates 40 and 40. Can be observed by guiding them to the observation side in parallel by region.

  Next, the main control unit 77 checks whether or not the offset adjustment is set (step S12). The offset adjustment means that there is a transmittance difference as an offset between the first area A0 and the like and the first surrounding area A11, and the presence or absence of the setting can be recorded in the memory of the main control unit 77. It has become. When the offset adjustment is performed, even if there is a difference between the transmittance of the light guide unit 22 with respect to the external light and the transmittance of the angle conversion unit 23 with respect to the external light, such a difference is represented by the first region A0 and the second surroundings. By compensating for the difference between the transmittance of the area A12 and the transmittance of the first surrounding area A11, luminance unevenness of the observed external image is prevented. Specifically, the transmittance of the first region A0 and the second surrounding region A12 is set higher than the transmittance of the first surrounding region A11 by a compensation amount. Such offset adjustment is set so as to be maintained even when the transmittance of the light control plates 40, 40 increases or decreases as a whole.

  Next, the main control unit 77 checks whether or not the environment support mode is set (step S13). The environment-friendly mode means that the transmittance of the light control plates 40, 40 is increased or decreased as a whole according to the intensity of external light, and the presence or absence of setting can be recorded in the memory of the main control unit 77. . When the environmental mode is set, the image forming apparatus 10 forms the light by appropriately adjusting the transmittance of the light control plates 40 and 40 based on the detection signals from the external light sensors 50 and 50 to appropriately block the external light. This prevents a decrease in contrast and difficulty in viewing the virtual image.

  Next, the main control unit 77 appropriately operates the light source driving circuit 71, the liquid crystal driving circuit 72, the dimming driving circuit 73, the optical sensor driving circuit 74, and the like based on the display mode checked in step S11, and the virtual image display device 100. The display operation for realizing each display mode is performed (step S14).

  FIG. 6 is a flowchart for explaining the outline of the operation in each display mode. First, the main control unit 77 reads the basic setting with reference to a memory (not shown) provided therein and sets it as control information (step S21). This basic setting means the setting of various parameters corresponding to the display mode described above. Specifically, for example, in the superposition mode, the basic setting means a standard transmittance or the like to be set for the light control plates 40 and 40. For example, in the case of the image light priority mode, the basic setting means a low transmittance to be set for the light control plates 40, 40, a luminance increase amount of the light sources 31a, 131a, and the like. For example, in the case of the external light priority mode, the basic setting means a high transmittance to be set for the light control plates 40, 40, a luminance reduction amount of the light sources 31a, 131a, and the like. Further, for example, in the case of the division mode, the basic setting means a transmittance difference or a transmittance ratio between the first area A0 and the second area A1 (surrounding areas A11, A12, A12) in the light control plates 40, 40. .

  Next, the main control unit 77 reads the additional setting with reference to the memory provided therein and sets it as control information (step S22). This additional information means the setting of various parameters relating to the offset adjustment and the environment support mode in the selected display mode. For example, when the offset adjustment is set, the additional setting means a transmittance difference set in the first area A0, the second surrounding area A12, and the first surrounding area A11, and the offset adjustment is not set. The additional setting means that the first region A0, the second surrounding region A12, and the first surrounding region A11 have the same transmittance. For example, when the environment compatible mode is set, the additional setting means a calculation formula or a table of the transmittance to be set in the light control plates 40, 40 based on the detection signals of the external light sensors 50, 50. When the environment support mode is not set, the additional setting means the transmittance to be set for the light control plates 40, 40 regardless of the detection signals of the external light sensors 50, 50.

  Next, the main control unit 77 operates the dimming plates 40 and 40 via the dimming drive circuit 73 (step S24), and the images of the drive units 111 and 112 via the light source drive circuit 71 and the liquid crystal drive circuit 72 are displayed. The display device 11 is caused to perform a display operation (step S25). For example, when the superimposition mode is set and the offset adjustment and the environment-compatible mode are set, both the light control plates 40 and 40 are set to a standard transmittance and the image emitted from the image extraction unit 90 is displayed. The brightness of the light is also relatively bright. Thereby, the observer wearing the virtual image display device 100 can observe the image light and the external light superimposed on each other. At this time, since offset adjustment is also performed, a difference in transmittance is provided in the first area A0, the second surrounding area A12, and the first surrounding area A11 in both the light control plates 40, 40 so that the appearance of the external image is substantially reduced. Make equal. Further, since the operation in the environment-friendly mode is executed, when the intensity of the external light is strong, the transmittance of both the light control plates 40 and 40 is decreased from the standard value according to the intensity of the external light, and the image extraction is performed. The relative luminance of the image light emitted from the unit 90 with respect to the ambient light is not greatly reduced. At this time, the transmittance difference or the transmittance ratio among the first region A0 and the second surrounding region A12 and the first surrounding region A11 is maintained. On the other hand, when the intensity of the external light is weak, the transmittance of both the light control plates 40, 40 is increased from the standard value according to the intensity of the external light, and the external light of the image light emitted from the image extraction unit 90 Make sure that the relative luminance of is not too high. At this time, the transmittance difference or the transmittance ratio among the first region A0 and the second surrounding region A12 and the first surrounding region A11 is maintained. When changing the transmittance of both the light control plates 40 and 40 according to the intensity of the external light, the brightness of the image light can be adjusted by increasing or decreasing the brightness of the light sources 31a and 131a. The range will be substantially expanded.

  Next, the main control unit 77 checks whether or not a request for changing the setting of the operation mode or the like has been made (step S26), and if there is a request for setting change from the observer wearing the virtual image display device 100, the setting is made. When the process proceeds to the change process and there is no request for such a setting change, the process returns to step S24 to continue the process.

  In the virtual image display device 100 according to the first embodiment described above, the dimming plates 40, 40 arranged facing the outside or the outside of the light guide plate 20 are under the control of the main control unit 77 and the dimming drive circuit 73. Since the transmission state of the external light is adjusted, it is possible to prevent the observation of the image from being hindered by the external light when the external light is relatively strong. At this time, since the light control plates 40 and 40 are electrically controlled and do not involve a mechanical mechanism, an operation for adjusting the transmission state of external light is automated and becomes relatively simple. Further, in the case of the virtual image display device 100 according to the first embodiment, the main control unit 77 and the dimming drive circuit 73 change the transmittance of the dimming plates 40 and 40 based on the output of the external light sensor 50, and external light. Since the transmittance of the light control plates 40, 40 decreases as the intensity of the light increases, it is possible to suppress adverse effects such as a decrease in the contrast of the image due to the image light buried in the external light.

[Second Embodiment]
The virtual image display device according to the second embodiment will be described below. The virtual image display device according to the present embodiment is a modification of the virtual image display device 100 according to the first embodiment, and is the same as the virtual image display device 100 according to the first embodiment unless otherwise described.

  In FIG. 7, the image forming apparatus 10 of the first display device 100 </ b> A includes a zoom type projection optical system 212. The projection optical system 212 not only collimates the image light emitted from each point on the liquid crystal display device 32, but can also increase / decrease the spread angle of the parallel light flux from each point, thereby changing the angle of view. Can be made. That is, the vertical and horizontal angles of view of the image light emitted from the image extraction unit 90 can be changed by adjusting the projection optical system 212, and the size of the virtual image recognized by the observer can be increased or decreased.

  FIG. 8 is a block diagram illustrating the drive control circuit 70 of the virtual image display device 100 according to the second embodiment. In this case, a zoom sensor 76 is added, and the setting of the angle of view by the projection optical system 212 is monitored. In the example shown in the figure, the projection optical system 212 is manually operated. However, the observer may increase or decrease the angle of view by operating an operation key (not shown).

Although description of specific control is omitted, generally, when the angle of view (size) of the virtual image is increased n times by the projection optical system 212, the luminance of the video is reduced to 1 / n ² times. Therefore, the external light is blocked by uniformly reducing the transmittance of the light control plates 40 and 40, and the image formed by the image light emitted from the image extraction unit 90 is relatively easy to see. Here, it is not always necessary to reduce the transmittance of the light control plates 40 and 40 to 1 / n ² times, and only by reducing the transmittance of the light control plates 40 and 40 as the angle of view of the virtual image increases. The light is relatively easy to see. Furthermore, the brightness of the image light can be adjusted by increasing or decreasing the brightness of the light sources 31a and 131a.

  In the virtual image display device 100 according to the second embodiment described above, the main control unit 77 and the dimming drive circuit 73 are configured so that the dimming plate 40, the dimming plate 40 according to the size of the virtual image formed by the image light emitted from the light guide plate 20. Since the transmittance of the light control plates 40 and 40 is reduced as the size of the virtual image is increased by changing the transmittance of 40, it is possible to suppress adverse effects such as a decrease in image brightness and contrast due to image light as the image is enlarged. .

[Others]
Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments, and can be implemented in various modes without departing from the gist thereof. Such modifications are also possible.

  In the above-described embodiment, the light control plate 40 is divided into the first region A0, the second region A1, and the like. However, the light control plate 40 can be evenly controlled without being divided into regions.

  In the above embodiment, the case where the size of the angle conversion unit 23 is larger than the light emission surface OS in the vertical direction in the image extraction unit 90 has been described, but the size of the angle conversion unit 23 is, for example, equal to the size of the light emission surface OS. You can also

  In the above embodiment, the first and second total reflection surfaces 22a and 22b are guided by totally reflecting image light by the interface with air without applying a mirror, a half mirror, or the like on the surface. The total reflection in the present invention includes reflection formed by forming a half mirror film on the whole or a part of the first and second total reflection surfaces 22a and 22b. For example, in the second total reflection surface 22b, the brightness difference of the external image can be reduced by applying the above mirror coating around the light exit surface OS.

The structure of the angle conversion unit 23 provided in the image extraction unit 90 is not limited to that shown in FIG. For example, like the angle conversion unit 323 shown in FIGS. 9A and 9B, a large number of image light reflecting surfaces 23d may be arranged in the Z direction at a predetermined pitch. These image light reflecting surfaces 23d extend in a band shape with the direction extending perpendicularly to the Z direction in which the image light reflecting surfaces 23d are arranged, that is, the Y direction as the longitudinal direction. These image light reflecting surfaces 23d are parallel to each other and form the same angle β with respect to the first total reflection surface 22a. The image light reflecting surface 23d is a partially reflecting surface that transmits part of the light component of the image light and reflects the rest by adjusting the reflectance. The adjacent image light reflecting surfaces 23d are connected by a boundary portion 23e that does not have a function as a reflecting surface or the like for extracting image light. As a result, the image light reflecting surfaces 23d are arranged in a separated state periodically and repeatedly along the optical axis OA, that is, along the Z direction, and extend parallel to each other. The image light reflecting surface 23d is formed, for example, by forming a film such as aluminum vapor deposition on one inclined surface of the underlying V groove, and is embedded in the light guide plate 20 by filling with resin thereafter. As shown in FIG. 9A, the image light GL2 that is totally reflected by the first and second total reflection surfaces 22a and 22b of the light guide unit 22 at the minimum reflection angle γ ₋ passes through the angle conversion unit 323 a plurality of times. after passing to reach the periphery 23h of the innermost of the angle conversion unit 323 (+ Z side), the reflection at the peripheral portion 23h, an angle theta ₂ from the light emission surface OS to the optical axis AX of the eye EY It is emitted as a parallel light beam toward the eye EY. On the other hand, as shown in FIG. 9B, the image light GL3 totally reflected by the first and second total reflection surfaces 22a and 22b of the light guide unit 22 at the maximum reflection angle γ ₊ is generated by the angle conversion unit 323. of reached periphery 23m of the most inlet-side (-Z side) by the reflection at the periphery 23m, as a parallel light beam toward an angle theta ₃ with respect to the optical axis AX of the eye EY from the light exit surface OS to the eye EY It is injected.

  The pitch PT of the arrangement of the reflection units 23c and the image light reflection surface 23d constituting the angle conversion units 23 and 323 described above is not limited to the same, and the pitch PT can be changed.

  In the above description, the transmissive liquid crystal display device 32 or the like is used as the image display element. However, the image display element is not limited to the transmissive liquid crystal display device, and various elements can be used. For example, a configuration using a reflective liquid crystal display device is possible, and a digital micromirror device or the like can be used instead of the liquid crystal display device 32. Moreover, the structure using the self-light-emitting element represented by LED array, OLED (organic EL), etc. is also possible.

  In the above description, the virtual image display device 100 includes the first display device 100A for the right eye and the second display device 100B for the left eye, but includes only one of the display devices 100A and 100B, and the image Can be viewed with one eye.

  In the above description, the light incident surface IS and the light exit surface OS are arranged on the same plane. However, the present invention is not limited to this. For example, the light incident surface IS is on the same plane as the first total reflection surface 22a. The light emission surface OS may be arranged on the same plane as the second total reflection surface 22b.

  In the above description, the tilt angle of the mirror layer 21a and the slope RS constituting the incident light bending portion 21 is not particularly mentioned. However, the present invention is not intended to use the tilt angle of the mirror layer 21a or the like with respect to the optical axis OA. Various values can be used according to other specifications.

  In the above description, the V-shaped groove formed by the reflection unit 23c is illustrated with a sharp tip, but the shape of the V-shaped groove is not limited to this, and the tip is cut flat. It may also be one that has an R (roundness) at the tip.

  In the above description, the virtual image display device 100 has been specifically described as being a head-mounted display, but the virtual image display device 100 can be modified to a head-up display.

DESCRIPTION OF SYMBOLS 10 ... Image forming apparatus, 11 ... Image display apparatus, 12 ... Projection optical system, 20 ... Light guide plate, 20a ... Light guide plate main-body part, 21 ... Incident light bending part, 22 ... Light guide part, 22a ... 1st all Reflecting surface, 22b ... second total reflecting surface, 23 ... angle converting unit, 23c ... reflecting unit, 31 ... illuminating device, 31a ... light source, 31b ... back light guide unit, 31c ... emission angle adjusting member, 32 ... liquid crystal Display device 40 ... Light control plate (optical element) 50 ... External light sensor 70 ... Drive control circuit 71 ... Light source drive circuit 72 ... Liquid crystal drive circuit 73 ... Light control drive circuit 74 ... Photo sensor drive circuit , 77 ... main control unit, 100 ... virtual image display device, 100A ... first display device, 100B ... second display device, 101, 102 ... optical panel, 104 ... frame, 111, 112 ... drive unit A0 ... first region, A1 ... second region, A11 ... first surrounding region, A12 ... second surrounding region, AX ... optical axis, EY ... eye, GL1, GL2, GL3 ... image light, IS ... light incident surface OA ... optical axis, OS ... light exit surface (light exit part)

Claims (8)

A light incident part for taking image light inside;
A light guide unit having first and second total reflection surfaces extending opposite to each other, and guiding the image light captured from the light incident unit by total reflection on the first and second total reflection surfaces;
The angle of the image light that has a plurality of reflecting surfaces arranged in a predetermined arrangement direction and enters through the light guide unit is converted by the reflecting surface that overlaps the light exit surface on the field of view among the plurality of reflecting surfaces. And a light guide plate that passes at least part of the external light to the observation side,
An optical element that is arranged to face the outside side of the light guide plate and adjusts the transmission state of outside light; and
A dimming control unit for electrically controlling the operation of the optical element,
Said optical element has a first region that overlaps on the field in the image pickup unit, a first peripheral area overlapping on ambient and the field excluding the plurality of reflecting surfaces, the plurality of reflecting surfaces sac Chi before serial light A reflecting surface that does not overlap the exit surface in the field of view and a second surrounding region that overlaps the field of view;
I have a,
The dimming control unit independently controls the transmittance of the first region, the transmittance of the first surrounding region, and the transmittance of the second surrounding region,
A virtual image display device, wherein the transmittance of the first region and the second surrounding region is higher than the transmittance of the first surrounding region . The virtual image display device according to claim 1, wherein the second surrounding region overlaps with a portion adjacent to the image extraction unit on a visual field.   The virtual image display device according to claim 1, wherein the optical element is any one of an electrochromic element, a liquid crystal panel, and a transmissive voltage element.   4. The virtual image display according to claim 1, wherein the optical element is a thin plate-like member disposed so as to cover the light guide plate on the outside side in the vicinity of the light guide plate. 5. apparatus. It has an external light sensor that detects the intensity of external light,
The dimming controller, on the basis of the output of the external light sensor to change the transmittance of the optical element, the virtual image display device according to any one of claims 1 to 4. The virtual image display device according to claim 5 , wherein the dimming control unit decreases the transmittance of the optical element as the intensity of external light increases. The dimming control unit, depending on the size of the virtual image formed by the image light emitted from the light guide plate changes the transmittance of the optical element, in any one of claims 1 to 6 The virtual image display device described. The virtual image display device according to claim 7 , wherein the dimming control unit reduces the transmittance of the optical element according to a size of the virtual image.

Images