JP2009192559A - Image display device - Google Patents

Abstract

An image display apparatus capable of moving an exit pupil and having a function of suppressing deterioration in image quality due to the movement of the exit pupil is provided.
An image light that forms image light by converting light emitted from the light source unit 12 and the light source unit 12 into image light representing an image to be displayed to an observer. A forming unit 14 and an exit pupil control unit 18 that controls the position of the exit pupil of the image display device are provided. The exit pupil control unit 18 includes a liquid crystal optical device 70 and exit pupil control means for controlling the position of the exit pupil by controlling the liquid crystal optical device 70. The image light forming unit 14 forms the image light based on the control amount of the liquid crystal optical device 70 so that the change in the geometric characteristic of the image recognized by the observer due to the control of the liquid crystal optical device 70 is canceled out. The unit 14 corrects the conversion characteristics for converting the light emitted from the light source unit 12 into image light.
[Selection] Figure 1

Description

  The present invention relates to a technique for optically displaying an image, and more particularly to an improvement in a technique for moving an exit pupil of an image display apparatus.

  As a technique for optically displaying an image, for example, image light representing an image to be displayed is projected directly onto the retina of the observer, thereby enabling the observer to observe the image as a virtual image. There are techniques and techniques that project such image light onto a physical screen, thereby allowing an observer to view the image as a real image.

  Furthermore, as a technique for converting light from a light source into image light representing an image to be displayed, for example, planar light incident from the light source is simultaneously applied to each pixel using a spatial modulation element such as an LCD. Spatial modulation, thereby forming a planar image light, or a beam-shaped light incident from a light source and intensity-modulated for each pixel using a scanner There is a technique for converting to image light.

  Patent Document 1 discloses a conventional head mounted display device as a device for optically displaying an image. This head-mounted display device directly projects image light representing an image to be displayed on the retina, thereby enabling an observer to observe the image as a virtual image and a beam incident from a light source. And a technology for converting the intensity-modulated light for each pixel into planar image light using a scanner.

This conventional head-mounted display device further employs a technique for detecting the position of the pupil of the observer who wants to observe the display image and moving the exit pupil of the head-mounted display device according to the movement of the pupil. Yes.
Japanese National Patent Publication No. 8-502372

  The inventor has proposed and studied a technique using a diffraction grating and a deflecting mirror, which are examples of optical elements, in order to move the exit pupil of the image display device. As a result, it is possible to move the exit pupil using these diffraction gratings and deflecting mirrors, but due to the movement of the exit pupil, the geometric characteristics of the display image, for example, the position and size are I noticed that it could be different from the regular one. The possibility and the cause will be described in detail later.

  As described above, in the technique proposed by the present inventor, there is a possibility that the image quality is deteriorated due to the movement of the exit pupil.

  Against the background described above, the present invention provides an image display device capable of moving the exit pupil and having a function of suppressing deterioration in image quality due to the movement of the exit pupil. It was made as an issue.

  The following aspects are obtained by the present invention. Each aspect is divided into sections, each section is given a number, and is described in a form that cites other section numbers as necessary. This is to facilitate understanding of some of the technical features that the present invention can employ and combinations thereof, and the technical features that can be employed by the present invention and combinations thereof are limited to the following embodiments. Should not be interpreted. That is, it should be construed that it is not impeded to appropriately extract and employ the technical features described in the present specification as technical features of the present invention although they are not described in the following embodiments.

  Further, describing each section in the form of quoting the numbers of the other sections does not necessarily prevent the technical features described in each section from being separated from the technical features described in the other sections. It should not be construed as meaning, but it should be construed that the technical features described in each section can be appropriately made independent depending on the nature.

(1) An image display device for optically displaying an image,
A light source unit;
An image light forming unit that forms the image light by converting the light emitted from the light source unit into image light representing an image to be displayed to the observer;
An exit pupil control unit that controls the position of the exit pupil of the image display device,
The exit pupil control unit
An optical element disposed in the course of the image light traveling in the image display device;
Exit pupil control means for controlling the position of the exit pupil by controlling the optical element,
The image light forming unit is configured to control a control amount of the optical element or a physical quantity related to the control amount so that a change in a geometric characteristic of an image recognized by an observer due to the control of the optical element is canceled out. The image display device includes a conversion characteristic correction unit that corrects a conversion characteristic in which the image light forming unit converts light emitted from the light source unit into the image light.

  According to this image display apparatus, when there is a possibility that the geometric characteristic of the image recognized by the observer may change due to the control of the optical element for moving the exit pupil, the change is completely completed. The conversion characteristic that the image light forming unit converts the light emitted from the light source unit into image light is corrected so as to be canceled out partially or partially.

  Therefore, according to this image display device, the change in the geometric characteristics of the image recognized by the observer due to the movement of the exit pupil is suppressed, and as a result, the image quality is deteriorated due to the movement of the exit pupil. Is suppressed.

(2) The image display device according to (1), wherein the geometric characteristic includes a position of an image actually recognized by an observer.

  According to this image display device, the position of the image that is actually recognized by the observer is more likely to be maintained at the normal position regardless of whether or not the exit pupil has moved. As a result, the position of the display image is stabilized regardless of whether the exit pupil moves during display.

(3) The image display device according to (1) or (2), wherein the geometric characteristic includes a scale of an image that is actually recognized by an observer.

  According to this image display device, the scale of the image actually recognized by the observer is maintained at a normal scale regardless of whether or not the exit pupil is moved. As a result, the size of the display image is stabilized regardless of whether or not the exit pupil moves during display.

(4) The optical element includes an electric control element that diffracts the image light incident from the image light forming unit and that has an electrically variable angle of diffracted light. The image display device according to any one of the items.

(5) The electrical control element includes a liquid crystal optical device,
The liquid crystal optical device is configured to include a plurality of electrodes each having a stripe shape and a liquid crystal layer having a surface on which the plurality of electrodes are formed, and the liquid crystal optical device is applied to each of the plurality of electrodes simultaneously. The image display device according to (4), wherein the angle of the diffracted light emitted from the liquid crystal optical device changes according to a plurality of voltage value distribution patterns.

(6) The image display device according to any one of (1) to (3), wherein the optical element includes at least one of an electro-optic effect deflector EOD and an acousto-optic deflector AOD.

(7) The image display device has an intermediate image plane in the middle of the path of the image light,
The image display device according to any one of (1) to (6), wherein the optical element is disposed at a position substantially equal to a position of the intermediate image plane.

(8) The image display device has an intermediate image plane in the middle of the path of the image light,
The image display device according to any one of (1) to (6), wherein the optical element is disposed at a position deviated from the position of the intermediate image plane.

  According to this image display apparatus, light having a larger cross-sectional area is incident on the optical element than when the optical element is disposed at a position substantially equal to the position of the intermediate image plane. As a result, for example, when the optical element is a diffraction grating, the advantage that the diffraction efficiency is improved, and when a foreign substance such as dust adheres to the optical element, the image defect caused by it is not so much. The advantage of not being noticeable is obtained.

(9) The image light forming unit includes a flat panel display that forms the image light by performing spatial modulation on the planar light incident from the light source unit for each pixel based on an image signal. ,
The flat panel display converts the light emitted from the light source unit into the image light according to the image signal,
The conversion characteristic depends on the image signal,
The image display device according to any one of (1) to (8), wherein the conversion characteristic correction unit corrects the image signal based on a control amount of the optical element or a physical amount related thereto.

  According to this image display device, the image signal to be supplied to the flat panel display is corrected, whereby the geometric characteristics of the image recognized by the observer due to the movement of the exit pupil (for example, the image Of the image quality due to movement of the exit pupil is suppressed.

(10) The image display device according to (9), wherein the flat panel display includes at least one of a liquid crystal display, organic electroluminescence, and a digital micromirror device.

(11) The optical element includes a deflection mirror whose angle with respect to incident light is variable,
The exit pupil control means controls the position of the exit pupil so as to follow the change in the pupil position of the observer by changing the angle of the deflecting mirror with respect to the incident light,
The image display apparatus according to (1), wherein the conversion characteristic correcting unit corrects the conversion characteristic based on an angle of the deflection mirror with respect to incident light or a physical quantity related to the angle.

(12) The light source unit generates beam-like light that realizes luminance for each pixel of the image to be displayed to the observer based on the image signal,
The image light forming unit includes an optical scanner that forms the image light by two-dimensionally scanning the beam-shaped light incident from the light source unit using at least one oscillating mirror,
The conversion characteristic depends on the image signal,
The image display device according to any one of (1) to (8), wherein the conversion characteristic correction unit corrects the image signal based on a control amount of the optical element or a physical amount related thereto.

  According to this image display device, the image signal to be supplied to the light source unit that emits light to the optical scanner is corrected, so that the geometry of the image recognized by the observer due to the movement of the exit pupil. The possibility that the target characteristic (for example, the position and size of the image) changes is reduced, and as a result, the deterioration of the image quality due to the movement of the exit pupil is suppressed.

(13) The image light forming unit forms the image light by two-dimensionally scanning the beam-shaped light incident from the light source unit using at least one oscillating mirror. Including
The conversion characteristic depends on the maximum swing angle of the swing mirror,
The image display device according to any one of (1) to (8), wherein the conversion characteristic correction unit corrects a maximum swing angle of the swing mirror based on a control amount of the optical element or a physical amount related thereto. .

  According to this image display device, by correcting the maximum swing angle of the swing mirror in the optical scanner, the geometric characteristics of the image recognized by the observer due to the movement of the exit pupil (for example, The possibility that the image size will change is reduced, and as a result, deterioration of image quality due to movement of the exit pupil is suppressed.

(14) Furthermore, a pupil position detector that detects the position of the pupil is included,
The exit pupil control means controls the optical element to move the exit pupil so as to follow the movement of the observer's pupil based on the output signal from the pupil position detector (1) to ( The image display device according to any one of 13).

  According to this image display apparatus, the exit pupil is automatically moved so as to follow the movement of the observer's pupil.

(15) The exit pupil control means moves the position of the exit pupil to a position corresponding to the input signal by controlling the optical element in accordance with an input signal representing a command from a user. The image display device according to any one of (1) to (13), which is controlled.

  According to this image display device, the user can move the position of the exit pupil to an arbitrary position. For example, the user can manually move the exit pupil so as to follow the movement of the observer's pupil.

(16) The image display device according to (4), wherein the conversion characteristic correction unit determines a parallel movement amount of the image in the diffraction direction based on a control amount of the optical element or a physical amount related thereto.

(17) The conversion characteristic correcting unit determines an enlargement / reduction ratio of the image in the swing direction of the swing mirror based on a control amount of the optical element or a physical amount related thereto. Image display device.

(18) The image display device according to (2), wherein the conversion characteristic correction unit determines a correction amount of the position of the image according to a movement amount of the exit pupil.

(19) The image display device according to (3), wherein the conversion characteristic correction unit determines a correction amount of the scale of the image according to a movement amount of the exit pupil.

  Hereinafter, some of more specific embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 conceptually shows an optical path diagram of the head mounted display device 10 according to the first embodiment of the present invention. The head mounted display device 10 is an image display device of a type that is used by being mounted on the head of an observer (not shown).

  In general, the head-mounted display device 10 spatially modulates planar light incident from a light source at the same time for each pixel using a spatial modulation element, and an image formed in this manner. Light is projected directly onto the viewer's retina via the viewer's pupil, thereby allowing the viewer to view the image as a virtual image.

  Specifically, the head-mounted display device 10 includes a light source unit 12, an image light forming unit 14, a relay optical system 16, an exit pupil control unit 18, a pupil position detection unit 20, and an eyepiece optical system 22. Are arranged in series with each other in that order. A collection of these elements is prepared for each of the observer's right eye and left eye, and image light is incident on any eye of the observer.

  The light source unit 12 includes a white LED 30 as a light source and a field lens 32 into which white light from the white LED 30 is incident. The white LED 30 is driven by the LED driver 34, and thereby emits white light.

  The image light forming unit 14 is configured to include an LCD (liquid crystal display) 40 as a flat panel display (an example of a spatial modulation element). The LCD 40 includes a color filter (RGB filter) that separates the white light from the collimating lens 32 into three color component lights (RGB) for each pixel, and a liquid crystal panel that controls the transmittance of each component light. It is configured as follows. The liquid crystal panel has a plurality of pixels, and controls the transmittance of each component light for each pixel.

  Several examples of the LCD 40 are disclosed in Japanese Patent Application Laid-Open No. 11-194313, which is incorporated herein in its entirety by reference. The LCD 40 is driven by the LCD driver 42, thereby applying spatial modulation to the white light emitted from the white LED 30.

  In the present embodiment, the image light forming unit 14 is mainly configured by a flat panel display, but is not limited thereto, and can be configured by, for example, an optical scanner. In this case, the head mounted display device 10 is also referred to as a retinal scanning display device.

  Moreover, in this embodiment, LCD40 is employ | adopted as an example of a flat panel display, However, It is not limited to this, For example, it can be set as organic electroluminescence or it can be set as a digital micromirror device.

  The relay optical system 16 is configured to include a front-stage relay lens 60 and a rear-stage relay lens 62.

  The exit pupil control unit 18 is provided to control the exit pupil position of the head mounted display device 10 so as to follow the change in the pupil position of the observer. The exit pupil control unit 18 is mainly configured by a liquid crystal optical device 70 which is an example of an electrical control element.

  As shown in FIG. 12, this liquid crystal optical device 70 is offset by a distance d from the intermediate image plane located between the relay optical system 16 and the eyepiece optical system 22 (in this embodiment, the eyepiece optical system 22). (Close position). The effect of the offset arrangement will be described in detail later.

  The liquid crystal optical device 70 functions as a diffraction grating whose diffraction angle is electrically variable. Further, the liquid crystal optical device 70 functions as a transmissive diffraction grating, but is not limited thereto, and a liquid crystal optical device that functions as a reflective diffraction grating can be employed.

  The liquid crystal optical device 70 is designed to perform two-dimensional diffraction, but is not limited thereto, and can be designed to perform one-dimensional diffraction. As shown in a sectional view in FIG. 2, the liquid crystal optical device 70 includes a first portion 72 for diffracting incident light in the X direction, that is, the horizontal direction, and a first portion 72 for diffracting incident light in the Y direction, that is, the vertical direction. The two portions 74 are laminated and integrated with each other via a common transparent glass substrate.

  One conventional example of the liquid crystal optical device 70 is disclosed in Japanese Patent Laid-Open No. 2001-100026, and this publication is incorporated herein in its entirety by reference.

  As shown in FIG. 2, the first portion 72 is configured by laminating a transparent glass substrate 80 and a liquid crystal layer 82. On the surface of the liquid crystal layer 82, a plurality of striped electrodes 84 are formed so as to extend in parallel with each other. The plurality of electrodes 84 are a plurality of transparent electrodes arranged in the X direction. FIG. 3 shows the plurality of electrodes 84 in a front view.

  On the other hand, a ground electrode 86 common to the plurality of electrodes 84 is formed on the back surface of the liquid crystal layer 82. The ground electrode 86 is also a transparent electrode.

  In order to operate the first portion 72, a voltage is applied between a selected one of the plurality of electrodes 84 and the ground electrode 86, whereby an electric field corresponding to the position of the selected electrode 84 is generated in the liquid crystal. Applied to layer 82. As a result, the liquid crystal molecules in the liquid crystal layer 82 are tilted, whereby the refractive index of the liquid crystal layer 82 changes.

  As shown in FIG. 3, mode 1, mode 2 and mode 3 are prepared as distribution patterns of voltage values applied to the plurality of electrodes 84. When mode 1 is adopted, no voltage is applied to any electrode 84 as shown in FIG. This is shown graphically in FIG. As a result, as shown in FIG. 3A, the first portion 72 transmits the incident light from the relay optical system 16 as it is as the 0th-order light.

  On the other hand, when mode 2 is selected, as shown in FIG. 3B, a voltage is applied to the two adjacent electrodes 84, but a voltage is applied to the two adjacent electrodes 84. As a result, voltage is applied to the electrode 84 at intervals of two. This is shown graphically in FIG. As a result, as shown in FIG. 3B, the first portion 72 generates two diffracted lights, that is, + 1st order light and −1st order light from the incident light from the relay optical system 16.

  When mode 3 is selected, as shown in FIG. 3 (c), a voltage is applied to the electrodes 84 every other line. This is shown graphically in FIG. As a result, as shown in FIG. 3C, the first portion 72 generates two diffracted lights, that is, a + 1st order light and a −1st order light from the incident light from the relay optical system 16. The angle (deflection angle or diffraction angle) at which these primary lights exit from the first portion 72 is larger than the angle in mode 2.

  Therefore, when the distribution pattern of the voltage value applied to the first portion 72 is changed to mode 1, mode 2 and mode 3, the angle of the diffracted light emitted from the first portion 72 changes.

  When the angle of the diffracted light changes in this way, the exit pupil moves as shown by the optical path diagram in FIG. Specifically, when mode 1 is selected, light is emitted from the liquid crystal optical device 70 along an optical path indicated by a dotted line in FIG. 5, and as a result, the exit pupil is at a neutral position P1 on the optical axis. Located in

  On the other hand, when mode 2 or 3 is selected, light is emitted from the liquid crystal optical device 70 along the optical path indicated by a double broken line in FIG. 5, and as a result, the exit pupil is shifted by a distance a from the optical axis. Moved to the position P2. For example, when the diffraction angle θ is 7.1 [deg] and the distance b is 40 [mm], the distance a is 5 [mm].

  The liquid crystal optical device 70 emits the + 1st order light and the −1st order light in the mode 2 or 3, but FIG. 5 shows the relationship between the + 1st order light and the −1st order light for the sake of simplicity. Of these, only the diffracted light that forms the exit pupil that will enter the pupil is shown.

  In the present embodiment, when the distribution pattern of the voltage value applied to the first portion 72 is changed to mode 1, mode 2 and mode 3, the angle of the diffracted light emitted from the first portion 72 changes discretely. Therefore, the position of the exit pupil of the head mounted display device 10 is also changed discretely (that is, discontinuously or stepwise).

  As shown in FIG. 2, the second portion 74 is configured by laminating a transparent glass substrate 90 and a liquid crystal layer 92, similarly to the first portion 72. On the surface of the liquid crystal layer 92, a plurality of stripe-shaped electrodes 94 are formed so as to extend in parallel with each other. Each of the plurality of electrodes 94 is a transparent electrode that extends at right angles to the plurality of electrodes 84 in the first portion 72. The plurality of electrodes 94 are arranged in the Y direction.

  On the other hand, a ground electrode 96 common to the plurality of electrodes 94 is formed on the back surface of the liquid crystal layer 92. The ground electrode 96 is also a transparent electrode.

  Since the operation of the second portion 74, the type of mode prepared for the operation, and the relationship between the mode and the diffraction angle are the same as those in the case of the first portion 72, redundant description is omitted.

  As shown in FIG. 1, the liquid crystal optical device 70 is driven by a liquid crystal optical device driver 72.

  In addition, in the present embodiment, the liquid crystal optical device 70 is selected as the optical element used to move the exit pupil, but the present invention is not limited to this. For example, an electro-optic effect deflector EOD is used. It is possible to select an acousto-optic deflector AOD.

  Further, a grating light valve GLV can be selected as such an optical element. The grating light valve GLV includes, for example, a fixed grating having a ribbon-like reflecting surface, and a movable grating having a ribbon-like reflecting surface and movable with respect to the fixed grating according to an electric signal. It is comprised so that it may contain.

  Several examples of the grating light valve GLV are disclosed in Japanese Patent Application Laid-Open No. 2003-341128, which is incorporated herein by reference in its entirety.

  Furthermore, as the above-described optical element, it is possible to select a diffractive element that is made of a material that extends electrically in the direction of the diffraction pitch and thereby has an electrically variable diffraction pitch.

  As shown in FIG. 1, a pupil position detection unit 20 is disposed immediately downstream of the exit pupil control unit 18 described above. The exit pupil control unit 18 moves the exit pupil of the head mounted display device 10 so as to follow the change in the pupil position for each eye of the observer based on the pupil position detected by the pupil position detection unit 20. Let

  The pupil position detection unit 20 includes a half mirror 100 that extracts reflected light from the eyes of the observer as a device used to acquire information useful for detecting the pupil position of the eyes of the observer. . The pupil position detection unit 20 further includes a pupil position detection circuit 102 that optically detects the pupil position based on the incident light from the half mirror 100.

  The half mirror 100 transmits incident light from the liquid crystal optical device 70 toward the eyepiece optical system 22, while reflecting light from the eye of the observer, and converts incident light from the eyepiece optical system 22 into the pupil position. It is designed to reflect toward the light receiving part (not shown) of the detection circuit 102.

  The pupil position detection circuit 102 determines the relative position of the pupil position (for example, the center position of the pupil) with respect to the exit pupil (exit pupil at the neutral position) on the optical axis of the head mounted display device 10 in the horizontal direction (X direction). ) And the vertical direction (Y direction). The pupil position detection circuit 102 is mainly composed of a CCD camera, for example. Accordingly, the pupil position detection circuit 102 outputs a signal representing the horizontal position X of the pupil and a signal representing the vertical position Y of the pupil.

  The eyepiece optical system 22 includes an eyepiece lens 110 and a half mirror 112 as a light guide that guides image light from the eyepiece lens 110 to the pupil of the user.

  In this embodiment, since the light guide is configured as the half mirror 112, the user observes the actual outside world through the half mirror 112 and simultaneously receives the image light from the eyepiece 110 by the reflection of the half mirror 112. Thus, it is possible to observe the display image. That is, the head-mounted display device 10 is a see-through type capable of observing a display image superimposed on the actual outside world.

  FIG. 6 conceptually shows an electrical part of the head mounted display device 10 in a block diagram. The head mounted display device 10 includes a signal processing device 120.

  The signal processing device 120 is configured to include a computer 122, a memory unit 124, an input / output interface 126, and a clock oscillator 128. The aforementioned LED driver 32, LCD driver 42, pupil position detection circuit 102, and liquid crystal optical device driver 72 are electrically connected to the input interface 126.

  As shown in FIG. 6, the signal processing device 120 generally generates a signal necessary for displaying the content based on data representing the content input from the outside, and based on the signal, the LED The white LED 30 is controlled via the driver 34 and the LCD 40 is controlled via the LCD driver 42.

  In the present embodiment, as shown in FIG. 1, an image position signal is also input to the LCD driver 42 in addition to an image signal representing a color and luminance to be realized for each pixel. The image position signal is input to the LCD driver 42 in order to displace the display position of the image for the observer in the horizontal direction and the vertical direction from the default position. Therefore, the image position signal is generated so as to have a component representing the horizontal movement amount from the default position and a component representing the vertical movement amount of the display image.

  The content is expressed by an R luminance signal, a G luminance signal, and a B luminance signal. When these signals are input, the computer 122 stores the R luminance signal, the G luminance signal, and the B luminance signal in the R / G / B buffer 130. The computer 122 generates an R image signal, a G image signal, and a B image signal for controlling the LCD 40 from the R luminance signal, the G luminance signal, and the B luminance signal for each frame, and sends the image signals to the LCD driver 42. Supply.

  As shown in FIG. 7, the memory unit 124 stores in advance an image display program, a pupil tracking program, and an image position correction program in a nonvolatile manner.

  The image display program is executed by the computer 122 to generate an image signal based on the luminance signal representing the content and supply it to the LCD driver 42, thereby displaying the target image. Since this image display program is executed by a well-known procedure, the description by text and illustration is omitted.

  On the other hand, the pupil tracking program moves the exit pupil of the head-mounted display device 10 so as to follow the change of the pupil position based on the signal from the pupil position detection circuit 102 and representing the pupil position. Executed by the computer 122. That is, the pupil tracking program is executed by the computer 122 so that the exit pupil tracks the pupil position.

  FIG. 8 conceptually shows the pupil tracking program in a flowchart. The pupil tracking program is automatically executed periodically after the power (not shown) of the head mounted display device 10 is turned on by the user, or is executed in response to a request from the user.

  When the pupil tracking program is executed, first, in step S1, the horizontal position X of the pupil is detected based on the signal from the pupil position detection circuit 102. Next, in step S2, the signal from the pupil position detection circuit 102 is detected. Based on this, the vertical position Y of the pupil is detected.

  Subsequently, in step S3, an appropriate mode is selected based on the detected horizontal position X so that the exit pupil tracks the pupil position in the horizontal direction among the modes 1 to 3 described above. Thereafter, in step S4, an appropriate mode is selected for tracking the pupil position in the vertical direction among the above-described modes 1 to 3 based on the detected horizontal position Y.

  The mode selection for horizontal tracking and the mode selection for vertical tracking are performed according to a common algorithm. Hereinafter, the algorithm will be described in detail with reference to FIG.

  In FIG. 9, the positions of a plurality of exit pupils that can be adopted by the head mounted display device 10 are indicated by five circles arranged in a horizontal row for each mode. Further, for each mode, the pupil is indicated by a circle larger than the circle representing the exit pupil. In fact, the pupil is larger than the exit pupil.

  In the present embodiment, as described above, when mode 1 is selected, the liquid crystal optical device 70 generates 0th order light, and when mode 2 is selected, the liquid crystal optical device 70 is changed to + first order light. When −1st order light is generated under a small deflection angle and mode 3 is selected, the liquid crystal optical device 70 causes the + 1st order light and −1st order light to be generated under a large deflection angle. generate.

  In the liquid crystal optical device 70, the voltage is applied among the plurality of electrodes 84 and 94. The plurality of electrodes 84 and 94 arranged at a constant pitch with one isolated electrode as a repeating unit (see FIG. 3C). ), Or a plurality of electrodes 84 and 94 (see FIG. 3B) arranged at a constant pitch with a set of adjacent electrodes as a repeating unit. In this liquid crystal optical device 70, the smaller the pitch in which a plurality of repeating units are arranged, the larger the deflection angle of the diffracted light.

  In the present embodiment, the liquid crystal optical device 70 is configured so that the movement amount of the exit pupil is substantially equal between the case where the mode is changed from mode 1 to mode 2 and the case where the mode is changed from mode 2 to mode 3. The configuration and its control method are preset. Furthermore, if the average diameter of the pupil is represented by A and the diameter of the exit pupil is represented by B, the exit is the same regardless of whether the mode 1 is changed to the mode 2 or the mode 2 is changed to the mode 3. The configuration of the liquid crystal optical device 70 and the control method thereof are set in advance so that the pupil moves by a distance substantially equal to (AB).

  As shown in FIG. 9, in the present embodiment, the position of the exit pupil is changed discretely instead of continuously. On the other hand, at each moment, it is desirable from the viewpoint of preventing image multiplexing that there is only one exit pupil in the pupil. Further, it is displayed that there is one exit pupil as a whole in the pupil. This is desirable from the viewpoint of ensuring the brightness of the image.

  In the present embodiment, when the pupil position changes, (1) a condition that only one exit pupil exists in the pupil, and (2) a condition that one exit pupil exists entirely in the pupil. Any one of a plurality of exit pupils that can be taken discretely is selected so that.

  Specifically, for example, taking horizontal tracking as an example, the horizontal position X of the pupil with respect to the neutral position (horizontal position X = 0) (that is, the amount of deviation of the center point of the pupil from the neutral position) is , (A−B) / 2, mode 1 is selected, and as a result, the exit pupil due to the 0th-order light is made to exist in the pupil.

  When the horizontal position X is (A−B) / 2 or more and smaller than 3 (A−B) / 2, mode 2 is selected, and as a result, + 1st order light having a small deflection angle is obtained. Alternatively, the exit pupil due to the −1st order light is made to exist in the pupil.

  Further, when the horizontal position X is 3 (A−B) / 2 or more and smaller than 5 (A−B) / 2, the mode 3 is selected, and as a result, the + 1st order having a large deflection angle is obtained. An exit pupil of light or −1st order light is made to exist in the pupil.

  In addition, in this embodiment, as is clear from FIG. 9, when mode 2 or mode 3 is selected instead of mode 1, two diffracted lights are generated. Of these, only one diffracted light contributes to the formation of the exit pupil existing in the pupil. Therefore, unlike when mode 1 is selected, when mode 2 or mode 3 is selected, the output of the emitted light from light source unit 12 is increased or decreased in order to maintain the brightness of the display image. It is necessary to take output correction measures such as. That is, it is necessary to prevent the amount of light incident on the pupil from fluctuating by changing the output of the emitted light from the light source unit 12 in accordance with the movement of the exit pupil, that is, the mode change.

  On the other hand, the voltage values monotonously increase for each of the plurality of electrodes 82 and 92 in the liquid crystal optical device 70 as shown by mode 4 in FIG. Thus, when a voltage is applied, the liquid crystal optical device 70 functions as a blazed grating.

  When the liquid crystal optical device 70 functions as a blazed grating, as shown in FIG. 10 (b), the diffracted light emitted to the positive side and the diffracted light emitted to the negative side with respect to the optical axis of the liquid crystal optical device 70 are predetermined. The power of the other diffracted light is greater than the power of the other diffracted light.

  Accordingly, not only the amount of deviation of the pupil position from the neutral position but also the direction of deviation is detected based on the signal from the pupil position detection circuit 102, and the voltage is applied to the plurality of electrodes 82 and 92 based on the detection result. It is possible to implement the present invention in such a manner that the device 70 is applied in a voltage value distribution pattern for functioning as a blazed grating.

  Returning to FIG. 8, in this embodiment, in step S3, a mode to be adopted for horizontal tracking is selected based on the horizontal position X of the pupil according to the above-described mode selection algorithm. Thereafter, in step S4, a mode to be adopted for vertical tracking is selected based on the vertical position Y of the pupil according to the mode selection algorithm described above.

  Subsequently, in step S5, voltages are applied to the plurality of electrodes 84 in the first portion 72 of the liquid crystal optical device 70, that is, the portion for moving the exit pupil in the horizontal direction, and the voltages corresponding to the mode selected in step S3. Applied in a distribution pattern. Thus, the position of the exit pupil in the horizontal direction is brought close to or coincident with the current horizontal position of the pupil.

  Thereafter, in step S6, voltages are applied to the plurality of electrodes 94 in the second portion 74 of the liquid crystal optical device 70, that is, the portion for moving the exit pupil in the vertical direction, and the voltage distribution corresponding to the mode selected in step S4. Applied in a pattern. As a result, the vertical position of the exit pupil approaches or coincides with the current vertical position of the pupil.

  This completes one execution of this pupil tracking program.

  FIG. 11 conceptually shows a flowchart of the above-described image position correction program.

  As described above, as shown in FIG. 12, the liquid crystal optical device 70 is offset by a distance d from the intermediate image plane located between the relay optical system 16 and the eyepiece optical system 22 (in this embodiment, , A position near the eyepiece optical system 22).

  FIG. 12A shows that the liquid crystal optical device 70 emits zero-order light in mode 1, and as a result, the exit pupil is located at the neutral position P1. On the other hand, the laser beam incident on the liquid crystal optical device 70 at each moment is considered to be a bundle of a plurality of light beams passing through different points.

  In FIG. 12A, “A” indicates one vertical line passing through the intersection point O between the optical axis of the laser beam (center ray) incident on the liquid crystal optical device 70 and the intermediate image plane, and among the plurality of rays. It means the intersection with the center line of the uppermost one. On the other hand, “B” means the intersection of the one vertical line and the center line of the lowermost one of the plurality of configurations. The position defined by A, O, and B is projected as a virtual image behind the liquid crystal optical device 70, and the positional relationship is equal to the positional relationship of the display image for the observer.

  In FIG. 12B, the liquid crystal optical device 70 emits primary light in mode 2 or 3, and as a result, the exit pupil is located at a position P2 that is offset from the neutral position P1 by a distance a. It is shown.

  The liquid crystal optical device 70 emits the + 1st order light and the −1st order light in the mode 2 or 3, and FIG. 12B shows the + 1st order light and the −1st order light for the sake of simplicity. Of the light, only the diffracted light that forms the exit pupil that will enter the pupil is shown.

  In FIG. 12B, the liquid crystal optical device 70 is disposed at a position offset by a distance d from the intermediate image plane located between the relay optical system 16 and the eyepiece optical system 22. The position of the virtual image formed behind the device 70 is defined by A ′ offset upward from A, O ′ offset upward from O, and B ′ offset upward from B.

  FIGS. 13A and 13B show images (virtual images) observed by the observer in the mode 1 shown in FIG. 12A and the mode 2 or 3 shown in FIG. 12B, respectively. An example is shown. When mode 2 or 3 is selected, the observer observes the image so as to move upward when mode 1 is selected. Since such movement is unscheduled, it is necessary to eliminate or reduce the movement in order to enable the observer to observe the image stably.

  On the other hand, the amount that the image moves unscheduled depends on the amount of movement of the exit pupil. Therefore, if the amount of movement of the exit pupil is determined, the amount by which the image moves unscheduled is uniquely determined. As a result, the amount by which the display image should be moved to cancel the unscheduled amount of movement is also uniquely determined.

  Here, the above-described image position correction program will be specifically described with reference to FIG.

  This image position correction program is periodically and repeatedly executed while the head mounted display device 10 is powered on.

  At the time of each execution, first, in step S101, the horizontal movement amount of the exit pupil is obtained from the type of horizontal tracking mode selected by the execution of step S3 shown in FIG. The relationship between the mode type and the horizontal movement amount of the exit pupil is stored in the memory 124 in advance, and the current value of the horizontal movement amount of the exit pupil is obtained from the current mode type according to the relationship.

  Next, in step S102, in accordance with step S101, the vertical movement amount of the exit pupil is obtained from the type of vertical tracking mode selected by executing step S4 shown in FIG. The relationship between the mode type and the vertical movement amount of the exit pupil is stored in the memory 124 in advance, and the current value of the vertical movement amount of the exit pupil is obtained from the current mode type according to the relationship.

  Subsequently, in step S103, the horizontal correction amount of the image position is determined to have a value for canceling the horizontal movement amount of the image position, which is uniquely determined according to the horizontal movement amount of the exit pupil. The relationship between the horizontal movement amount of the exit pupil and the horizontal movement amount of the image position is stored in the memory 124 in advance, and the horizontal direction of the image position is determined from the current value of the horizontal movement amount of the exit pupil according to the relationship. The current value of the movement amount is obtained, and thus the current value of the horizontal correction amount of the image position is obtained.

  Thereafter, in step S104, in accordance with step S103, the vertical correction amount of the image position has a value for canceling out the vertical movement amount of the image position, which is uniquely determined according to the vertical movement amount of the exit pupil. Asking. The relationship between the vertical movement amount of the exit pupil and the vertical movement amount of the image position is stored in advance in the memory unit 124, and the vertical direction of the image position is determined from the current value of the vertical movement amount of the exit pupil according to the relationship. The current value of the movement amount is obtained, and thus the current value of the vertical correction amount of the image position is obtained.

  Subsequently, in step S105, the above-described image position signal is generated so as to represent the horizontal direction correction amount and the vertical direction correction amount of the image position obtained as described above. Thereafter, the generated image position signal is output to the LCD driver 42 in step S106.

  This completes one execution of the image position correction program.

  Therefore, according to the present embodiment, regardless of whether or not the exit pupil moves, the observer can observe the image at a stable position, and as a result, the display quality of the image by the head mounted display device 10 is improved. improves.

  As is clear from the above description, in the present embodiment, for convenience of description, the liquid crystal optical device 70 and the portion of the signal processing device 120 that executes the pupil tracking program shown in FIG. Configure the example of the “exit pupil control unit” in the item (1), the liquid crystal optical device 70 configures an example of the “optical element” in the item, and execute the pupil tracking program shown in FIG. The portion to be configured constitutes an example of the “exit pupil control unit” in the same term, and the part that executes the image position correction program shown in FIG. 11 in the signal processing device 120 is an example of the “conversion characteristic correction unit” in the same term. It is possible to think that it constitutes.

  Furthermore, in the present embodiment, for convenience of explanation, the combination of the image signal and the image position signal supplied to the LCD driver 42 constitutes an example of the “image signal” in the above item (9), and the horizontal level of the exit pupil. It can be considered that the combination of the direction movement amount and the vertical direction movement amount constitutes an example of “physical quantity related to the control amount of the optical element” in the same term.

  In addition, in the present embodiment, the exit pupil is automatically moved so as to follow the movement of the pupil, but the liquid crystal optical device 70 so that the exit pupil is moved to a position according to a command from the user. It is possible to implement the present invention in such a manner that is electrically controlled.

  Next, a second embodiment of the present invention will be described. However, since the present embodiment differs from the first embodiment only in the light source unit and the image light forming unit, and other elements are common, only the light source unit and the image light forming unit will be described.

  FIG. 14 conceptually shows an optical path diagram of a head mounted display device 150 according to the second embodiment of the present invention.

  The head-mounted display device 150 is generally a beam-shaped light incident from a light source, which is intensity-modulated for each pixel, and converted into a planar image light using a scanner. The image light thus formed is projected directly onto the viewer's retina via the viewer's pupil, thereby allowing the viewer to view the image as a virtual image. .

  As shown in FIG. 14, the head mounted display device 150 includes a light source unit 152 and an image light forming unit 154 as elements different from those in the first embodiment, while an exit pupil control unit 18 and pupil position detection. The unit 20 and the eyepiece optical system 22 are provided as elements common to the first embodiment.

  The light source unit 152 includes a laser 160 that emits a red laser beam, a laser 162 that emits a green laser beam, and a laser 164 that emits a blue laser beam. Each of the lasers 160, 162, and 164 is an individual laser driver. 170, 172, and 174 modulate the intensity of the generated laser beam. Specifically, the laser drivers 170, 172, and 174 generate laser beams from the lasers 160, 162, and 164 that realize intensity (luminance) for each pixel based on image signals corresponding to the laser beams of the respective colors. Let The intensity of each generated laser beam varies with time.

  In the present embodiment, in addition to the above-described image signal, an image position signal is also input to each laser driver 170, 172, 174. The image position signal is generated by each laser in order to displace the position of the image finally formed two-dimensionally using three color laser beams with respect to the observer from the default position in the horizontal direction and in the vertical direction. Input to the drivers 170, 172, and 174. Therefore, the image position signal is generated so as to have a component representing the horizontal movement amount from the default position and a component representing the vertical movement amount of the display image.

  The three color laser beams generated from the lasers 160, 162, and 164 are combined as one laser beam that reflects the color and luminance of the corresponding pixel. The synthesized laser beam is incident on the image light forming unit 154.

  The image light forming unit 154 now receives a main scanning mirror 180 (for example, a polygon mirror) that is driven to scan the laser beam incident from the light source unit 152 in the horizontal direction, and the laser beam incident from the main scanning mirror 180. Includes a sub-scanning mirror 182 (for example, a galvanometer mirror) that is driven to scan in the vertical direction. The main scanning mirror 180 is driven by a main scanning mirror driver 190, and the sub scanning mirror 182 is driven by a sub scanning mirror driver 192.

  The image light forming unit 154 further includes a front relay lens 200 and a rear relay lens 202. The front-stage relay lens 200 is disposed at the same position as the intermediate image plane between the main scanning mirror 180 and the sub-scanning mirror 182, while the rear-stage relay lens 202 is disposed between the sub-scanning mirror 182 and the liquid crystal optical device 70. Arranged at the same position as the intermediate image plane.

  In addition, the liquid crystal optical device 70 is disposed at the same position as the intermediate image plane between the rear relay lens 202 and the eyepiece lens 110, but in FIG. It is said that.

  Also in the present embodiment, in the same way as in the first embodiment, the exit pupil control unit 18 changes the pupil position of the exit pupil of the head mounted display device 150 based on the detection result of the pupil position by the pupil position detection unit 20. Move to follow. As a result, the observer can continue to observe the display image in the same display state regardless of the presence or absence of pupil movement.

  By the way, in the first embodiment, the conversion characteristic that the image light forming unit 14 converts the emitted light from the light source unit 12 into image light depends on the image position signal input to the LCD driver 42, and the image The position signal is generated according to the movement amount of the exit pupil, and as a result, the observer can continue to observe the image at a stable position regardless of whether or not the exit pupil has moved.

  On the other hand, in this embodiment, the conversion characteristic that the image light forming unit 154 converts the light emitted from the light source unit 152 into image light depends on the image position signal input to the laser drivers 170, 172, and 174. The image position signal is generated according to the movement amount of the exit pupil, and as a result, the observer can continue to observe the image at a stable position regardless of whether or not the exit pupil has moved. .

  As is clear from the above description, in the present embodiment, for convenience of description, the combination of the image signal and the image position signal supplied to the laser drivers 170, 172, and 174 is the “image signal” in the above item (12). It can be considered that the amount of horizontal movement and the amount of vertical movement of the exit pupil are examples of “physical quantities related to the control amount of the optical element” in the same term. is there.

  Next, a third embodiment of the present invention will be described. However, this embodiment is different from the first embodiment only in the exit pupil control unit, and the other elements are common, so only the exit pupil control unit will be described. About this embodiment, about the element which is common in 1st Embodiment, the duplicate description is abbreviate | omitted by quoting using the same code | symbol or name.

  FIG. 15 shows an optical path diagram of the head mounted display device 300 according to the present embodiment.

  As shown in FIG. 1, in the first embodiment, the exit pupil control unit 18 is mainly composed of a liquid crystal optical device 70 as a transmissive optical element, but in this embodiment, it is shown in FIG. As described above, the exit pupil control unit 310 is mainly configured by the deflection mirror 312 as a reflective optical element.

  Specifically, the exit pupil control unit 310 is provided to control the exit pupil position of the head mounted display device 300 so as to follow the change in the pupil position of the observer. The deflection mirror 312 in the exit pupil control unit 310 is disposed at a position that matches the position of a certain intermediate image plane in the head mounted display device 300.

  As shown in FIG. 16, the deflection mirror 312 is a swinging mirror that is mounted on a frame 314 that can swing around the X axis extending in the horizontal direction so as to swing around the Y axis extending in the vertical direction. The frame 314 is swung by an unillustrated X-axis actuator mounted on a stationary member of the head-mounted display device 300, while the deflection mirror 312 is swung by a not-illustrated Y-axis actuator mounted on the frame 314. It is done. As a result, the angle of the deflection mirror 312 with respect to the stationary member in the head mounted display device 300 can be adjusted two-dimensionally.

  As shown in FIG. 15, the deflection mirror 312 is driven by a deflection mirror driver 320.

  Based on the pupil position detected by the pupil position detection unit 20, the exit pupil control unit 310 changes the angle of the deflection mirror 312 so as to follow the change in the pupil position for each eye of the observer, thereby Then, the exit pupil of the head mounted display device 300 is moved.

  The pupil position detection unit 20 includes a half mirror 330 that extracts reflected light from the observer's eyes as a device used to acquire information useful for detecting the pupil position of the observer's eyes. . The pupil position detection unit 20 further includes a pupil position detection circuit 102 that optically detects the pupil position based on the incident light from the half mirror 330.

  The half mirror 330 transmits the incident light from the relay optical system 16 toward the deflecting mirror 312 and reflects the transmitted light toward the eyepiece optical system 22. The half mirror 330 further transmits the incident light from the eyepiece optical system 22 toward the light receiving unit (not shown) of the pupil position detection circuit 102, which is reflected light from the eyes of the observer.

  That is, the half mirror 330 performs not only the function of guiding the reflected light from the observer's eye to the pupil position detection circuit 102 but also the function of guiding the emitted light from the deflection mirror 312 to the eyepiece optical system 22. Is designed.

  FIG. 17 conceptually shows an electrical part of the head mounted display device 300 in a block diagram. The head mounted display device 300 includes a signal processing device 120 as in the first embodiment.

  The signal processing device 120 is electrically connected to the LED driver 32, the LCD driver 42, the pupil position detection circuit 102, the deflection mirror driver 320, and the variable focus lens driver 72.

  As shown in FIG. 18, in the memory unit 124, an image display program, a pupil tracking program, and an image scale correction program are stored in advance in a nonvolatile manner. Since the image display program is the same as the image display program in the first embodiment, a duplicate description is omitted.

  On the other hand, the pupil tracking program moves the exit pupil of the head mounted display device 300 so as to follow the change of the pupil position based on the signal from the pupil position detection circuit 102 and representing the pupil position. Executed by the computer 122. That is, the pupil tracking program is executed by the computer 122 so that the exit pupil tracks the pupil position.

  FIG. 19 conceptually shows the pupil tracking program in a flowchart. This pupil tracking program is automatically executed periodically after the power (not shown) of the head mounted display device 300 is turned on by the user, or is executed in response to a request from the user.

  At the time of execution, first, in step S201, the horizontal position X of the pupil is detected based on the signal from the pupil position detection circuit 102. Next, in step S202, the pupil is detected based on the signal from the pupil position detection circuit 102. The vertical position Y is detected.

  Subsequently, in step S203, based on the detected horizontal position X, the angle at which the deflection mirror 312 should rotate around the Y axis in order to track the pupil position in the horizontal direction, that is, the angle around the Y axis is changed. The amount (including the direction in which the deflection mirror 312 is rotated) is determined.

  In the present embodiment, the correspondence between the horizontal position X (the amount of horizontal displacement of the pupil position from the neutral position) and the amount of rotation angle from the neutral position around the Y axis of the deflection mirror 312 is stored as a table in the memory unit. The angle change amount around the Y axis of the deflection mirror 312 corresponding to the current value of the horizontal position X of the pupil is determined in accordance with the relationship.

  Thereafter, in step S204, in accordance with step S203, based on the detected vertical position Y, the angle at which the deflection mirror 312 should rotate around the X axis in order to track the pupil position in the vertical direction, An angle change amount (including a direction in which the deflection mirror 312 is rotated) about the X axis is determined.

  In this embodiment, the correspondence between the vertical position Y (vertical shift amount of the pupil position from the neutral position) and the rotation angle amount from the neutral position around the X axis of the deflection mirror 312 is stored as a table in the memory unit. The angle change amount around the X axis of the deflection mirror 312 corresponding to the current value of the vertical position Y of the pupil is determined in accordance with the relationship.

  Subsequently, in step S205, a control signal to be output to the deflection mirror driver 320 to realize the angle change amount around the Y axis and the angle change amount around the X axis determined in steps S203 and S204, respectively, is generated.

  Thereafter, in step S206, the generated control signal is output to the deflecting mirror driver 320. As a result, the horizontal position and the vertical position of the exit pupil are respectively set to the current horizontal position and the vertical position of the pupil. Approached or matched.

  This completes one execution of this pupil tracking program.

  FIG. 20 conceptually shows a flowchart of the above-described image scale correction program. Hereinafter, this image scale correction program will be described. Prior to that, the background and purpose of using this image scale correction program will be described.

  FIG. 21 shows a light path among the relay optical system 16, the half mirror 100, the deflection mirror 312 and the eyepiece optical system 22 in the head mounted display device 300 shown in FIG. Further, it is also shown that the light emitted from the eyepiece optical system 22 reaches the retina of the observer's eye through the exit pupil and the observer's eyeball lens in order.

  FIG. 21 shows an image plane formed by light emitted from the eyepiece optical system 22 when the deflection mirror 312 is in the neutral position and the exit pupil coincides with the neutral position P1. In this case, the observer perceives a virtual image on which the image plane having the dimension dA is projected.

  On the other hand, in FIG. 22, when the deflection mirror 312 is at a position rotated from the neutral position and the exit pupil coincides with the position P2 shifted by the distance a from the neutral position P1, the deflection mirror 312 is Incoming light and outgoing light are shown. Here, “the state in which the deflecting mirror 312 is rotated from the neutral position” means that not all points on the deflecting mirror 312 are located on the intermediate image plane as shown in FIG. It is. That is, the deflection mirror 312 is not entirely coincident with the intermediate image plane.

  As shown in FIG. 22, when attention is paid to a plurality of light beams forming a plurality of pixels constituting a two-dimensional image at each moment, a portion of the deflection mirror 312 close to the exit pupil with respect to the intermediate image plane The light ray incident on (in FIG. 22, the upper part of the deflecting mirror 312) is reflected at a position before the intermediate image plane and travels toward the exit pupil.

  On the other hand, as shown in FIG. 22, in the deflection mirror 312, a light ray incident on a portion far from the exit pupil with respect to the intermediate image plane (in FIG. 22, the lower portion of the deflection mirror 312) Reflected at a position far from the surface and headed toward the exit pupil.

  On the other hand, the observer perceives the virtual image as if it exists on the intermediate image plane. Therefore, when the deflection mirror 312 generally matches the intermediate image plane, the virtual image is a virtual image on which an image plane with a dA size is projected, but the deflection mirror 312 generally matches the intermediate image plane. If this is not the case, the size of the virtual image coincides with the projected image of the image plane of dB. Since the dimension dB is larger than the dimension dA, the observer perceives the displayed image as being larger than the ideal image when the exit pupil deviates from the neutral position P1.

  On the other hand, the scale of the actually perceived display image size with respect to the ideal image size is larger than 1, and the scale is unambiguous according to the movement amount a of the exit pupil from the neutral position P1. Is determined. Further, the size of the display image can be changed by correcting the image signal supplied to the LCD driver 42.

  Therefore, in the present embodiment, when it is necessary to move the exit pupil, the enlargement of the display image due to the movement of the exit pupil is suppressed by the prior correction of the image signal.

  Here, the above-described image scale correction program will be specifically described with reference to FIG.

  This image scale correction program is repeatedly executed periodically while the power of the head mounted display device 300 is turned on.

  At the time of each execution, first, in step S301, the horizontal direction of the exit pupil according to the angle change amount (deviation amount from the neutral position) of the deflection mirror 312 determined by the execution of step S203 shown in FIG. The amount of movement (the amount of deviation from the neutral position) is determined.

  Note that when it is possible to presuppose that the horizontal movement amount of the exit pupil is always substantially coincident with the horizontal position X of the pupil, the horizontal direction of the pupil detected by the execution of step S201 shown in FIG. It may be acquired as the direction position X.

  In the present embodiment, the relationship between the angle change amount around the Y axis of the deflection mirror 312 and the horizontal movement amount of the exit pupil is stored in the memory unit 124 in advance, and the horizontal movement amount of the exit pupil is determined according to the relationship. The value is calculated this time.

  Next, in step S302, in accordance with step S301, the angle of the exit pupil is changed according to the angle change amount (deviation amount from the neutral position) of the deflection mirror 312 determined by execution of step S204 shown in FIG. A vertical movement amount (deviation amount from the neutral position) is obtained.

  When it is possible to presuppose that the vertical movement amount of the exit pupil is always substantially coincident with the vertical position Y of the pupil, the vertical direction of the pupil detected by executing step S202 shown in FIG. It may be acquired as the direction position Y.

  In the present embodiment, the relationship between the angle change amount around the X axis of the deflection mirror 312 and the vertical movement amount of the exit pupil is stored in the memory unit 124 in advance, and the vertical movement amount of the exit pupil is determined according to the relationship. The value is calculated this time.

  Subsequently, in step S303, a scale correction factor to be realized in order to suppress the horizontal expansion of the display image due to the horizontal movement of the exit pupil is determined. The magnitude of this scale correction factor is determined based on the amount of horizontal movement of the exit pupil (the amount of horizontal deviation from the neutral position). Specifically, the current horizontal scale correction rate is determined according to a predetermined relationship between the horizontal movement amount of the exit pupil and the horizontal scale correction rate, which is stored in advance in the memory unit 124. It is determined.

  Thereafter, in step S304, a scale correction factor to be realized to suppress the vertical expansion of the display image due to the vertical movement of the exit pupil is determined. The magnitude of this scale correction factor is determined based on the amount of vertical movement of the exit pupil (the amount of vertical deviation from the neutral position). Specifically, according to a predetermined relationship between the vertical movement amount of the exit pupil and the vertical scale correction factor, which is stored in the memory unit 124 in advance, the current vertical scale correction factor is It is determined.

  Subsequently, in step S <b> 305, the original image signal is fetched from the R / G / B buffer 130. Thereafter, in step S306, the fetched original image signal is corrected so that the determined horizontal scale correction factor and vertical scale correction factor are simultaneously realized. The image display program shown in FIG. 18 is executed to display an image by supplying the corrected image signal to the LCD driver 42.

  This completes one execution of the image scale correction program.

  Therefore, according to the present embodiment, regardless of whether or not the exit pupil has moved, the observer can observe the image in a state where unexpected enlargement of the image is suppressed, and as a result, the head The display quality of the image by the mount display device 300 is improved.

  As is clear from the above description, in the present embodiment, for convenience of description, the variable focus lens 70 and the portion of the signal processing device 120 that executes the pupil tracking program shown in FIG. The “exit pupil control unit” in the item (1) is configured, and the portion of the signal processing device 120 that executes the pupil tracking program shown in FIG. 19 configures an example of the “exit pupil control unit” in the same term. The portion of the signal processing device 120 that executes the image scale correction program shown in FIG. 20 constitutes an example of “conversion characteristic correction means” in the same term, and the deflection mirror 312 is an example of “optical element” in the same term. It is possible to think that it is composed.

  Further, in the present embodiment, for convenience of explanation, the image signal supplied to the LCD driver 42 constitutes an example of the “image signal” in the item (9), and the horizontal movement amount and the vertical movement of the exit pupil. It can be considered that each quantity constitutes an example of “physical quantity related to the control amount of the optical element” in the same term.

  As described above, some of the embodiments of the present invention have been described in detail with reference to the drawings. However, these are exemplifications, and are based on the knowledge of those skilled in the art including the aspects described in the section of [Disclosure of the Invention]. The present invention can be implemented in other forms with various modifications and improvements.

1 is an optical path diagram conceptually showing a head mounted display device 10 according to a first embodiment of the present invention. It is sectional drawing which shows the liquid crystal optical device 70 shown in FIG. FIG. 3 is a diagram for explaining the relationship between a diffraction pattern by the liquid crystal optical device 70 shown in FIG. 2 and types of modes for applying a voltage to a plurality of electrodes 84 of the liquid crystal optical device 70. 3 is a graph for explaining types of modes for applying a voltage to a plurality of electrodes 84 of the liquid crystal optical device 70 shown in FIG. 2. FIG. 3 is an optical path diagram for explaining the principle of movement of the exit pupil of the head mounted display device 10 shown in FIG. 1 by diffraction of the liquid crystal optical device 70 shown in FIG. It is a block diagram for demonstrating notionally the electrical structure of the head mounted display apparatus 10 shown in FIG. It is a figure which shows the program previously memorize | stored in the memory part shown in FIG. 8 is a flowchart conceptually showing the pupil tracking program shown in FIG. FIG. 9 is a diagram for explaining an algorithm that is used to select one of three modes in accordance with the pupil position in the pupil tracking program shown in FIG. 8. FIG. 10A is a graph for explaining another mode 4 for applying a voltage to the plurality of electrodes 84 of the liquid crystal optical device 70 shown in FIG. 2, and FIG. It is an optical path diagram for demonstrating the diffraction pattern of the liquid crystal optical device 70 implement | achieved when selecting. 8 is a flowchart conceptually showing the image position correction program shown in FIG. It is an optical path diagram for demonstrating the principle by which the virtual image on an intermediate image plane moves as an exit pupil moves by the diffraction by the liquid crystal optical device 70 shown in FIG. It is a figure for demonstrating a display image moving relatively with respect to an observer as an exit pupil moves by the diffraction by the liquid crystal optical device 70 shown in FIG. It is an optical path figure showing notionally the head mounted display apparatus 150 according to 2nd Embodiment of this invention. It is an optical path figure showing notionally the head mounted display apparatus 300 according to 3rd Embodiment of this invention. It is a front view which expands and shows the deflection | deviation mirror 312 shown in FIG. FIG. 16 is a block diagram for conceptually explaining the electrical configuration of the head mounted display device 300 shown in FIG. 15. It is a figure which shows the program previously memorize | stored in the memory part shown in FIG. FIG. 19 is a flowchart conceptually showing the pupil tracking program shown in FIG. 18. 19 is a flowchart conceptually showing the image scale correction program shown in FIG. FIG. 21 is an optical path diagram for explaining the image scale correction program shown in FIG. 20. FIG. 21 is another optical path diagram for explaining the image scale correction program shown in FIG. 20.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Head mounted display apparatus 12 Light source part 14 Image light formation part 18 Exit pupil control part 20 Pupil position detection part 70 Liquid crystal optical device 72 1st part 74 2nd part 84 Electrode 94 Electrode 100 Half mirror 102 Pupil position detection circuit 120 Signal processing Device 122 Computer 150 Head mounted display device 152 Light source unit 154 Image forming unit 300 Head mounted display device 310 Exit pupil control unit 312 Deflection mirror

Claims (19)

An image display device for optically displaying an image,
A light source unit;
An image light forming unit that forms the image light by converting the light emitted from the light source unit into image light representing an image to be displayed to the observer;
An exit pupil control unit that controls the position of the exit pupil of the image display device,
The exit pupil control unit
An optical element disposed in the course of the image light traveling in the image display device;
Exit pupil control means for controlling the position of the exit pupil by controlling the optical element,
The image light forming unit is configured to control a control amount of the optical element or a physical quantity related to the control amount so that a change in a geometric characteristic of an image recognized by an observer due to the control of the optical element is canceled out. The image display device includes a conversion characteristic correction unit that corrects a conversion characteristic in which the image light forming unit converts light emitted from the light source unit into the image light.   The image display apparatus according to claim 1, wherein the geometric characteristic includes a position of an image actually recognized by an observer.   The image display apparatus according to claim 1, wherein the geometric characteristic includes a scale of an image actually recognized by an observer.   4. The optical element according to claim 1, wherein the optical element includes an electrical control element that diffracts the image light incident from the image light forming unit and an angle of the diffracted light is electrically variable. Image display device. The electrical control element includes a liquid crystal optical device,
The liquid crystal optical device is configured to include a plurality of electrodes each having a stripe shape and a liquid crystal layer having a surface on which the plurality of electrodes are formed, and the liquid crystal optical device is applied to each of the plurality of electrodes simultaneously. The image display apparatus according to claim 4, wherein the image display apparatus has a characteristic in which an angle of diffracted light emitted from the liquid crystal optical device changes according to a distribution pattern of a plurality of voltage values.   The image display device according to claim 1, wherein the optical element includes at least one of an electro-optic effect deflector EOD and an acousto-optic deflector AOD. The image display device has an intermediate image plane in the middle of the path of the image light,
The image display device according to claim 1, wherein the optical element is disposed at a position substantially equal to a position of the intermediate image plane. The image display device has an intermediate image plane in the middle of the path of the image light,
The image display device according to claim 1, wherein the optical element is disposed at a position deviated from the position of the intermediate image plane. The image light forming unit includes a flat panel display that forms the image light by performing spatial modulation for each pixel on the planar light incident from the light source unit based on an image signal,
The flat panel display converts the light emitted from the light source unit into the image light according to the image signal,
The conversion characteristic depends on the image signal,
The image display device according to claim 1, wherein the conversion characteristic correction unit corrects the image signal based on a control amount of the optical element or a physical amount related thereto.   The image display apparatus according to claim 9, wherein the flat panel display includes at least one of a liquid crystal display, organic electroluminescence, and a digital micromirror device. The optical element includes a deflecting mirror whose angle with respect to incident light is variable,
The exit pupil control means controls the position of the exit pupil so as to follow the change in the pupil position of the observer by changing the angle of the deflecting mirror with respect to the incident light,
The image display apparatus according to claim 1, wherein the conversion characteristic correction unit corrects the conversion characteristic based on an angle of the deflection mirror with respect to incident light or a physical quantity related to the angle. The light source unit generates beam-like light that realizes luminance for each pixel of an image to be displayed to an observer based on an image signal,
The image light forming unit includes an optical scanner that forms the image light by two-dimensionally scanning the beam-shaped light incident from the light source unit using at least one oscillating mirror,
The conversion characteristic depends on the image signal,
The image display device according to claim 1, wherein the conversion characteristic correction unit corrects the image signal based on a control amount of the optical element or a physical amount related thereto. The image light forming unit includes an optical scanner that forms the image light by two-dimensionally scanning the beam-shaped light incident from the light source unit using at least one oscillating mirror,
The conversion characteristic depends on the maximum swing angle of the swing mirror,
The image display device according to claim 1, wherein the conversion characteristic correction unit corrects a maximum swing angle of the swing mirror based on a control amount of the optical element or a physical amount related thereto. In addition, it includes a pupil position detector that detects the position of the pupil,
The exit pupil control means controls the optical element to move the exit pupil so as to follow the movement of the observer's pupil based on an output signal from the pupil position detection unit. An image display device according to any one of the above.   The exit pupil control means controls the position of the exit pupil to move to a position corresponding to the input signal by controlling the optical element in accordance with an input signal representing a command from a user. Item 14. The image display device according to any one of Items 1 to 13.   The image display device according to claim 4, wherein the conversion characteristic correction unit determines a parallel movement amount of the image in the diffraction direction based on a control amount of the optical element or a physical amount related thereto.   The image display device according to claim 13, wherein the conversion characteristic correcting unit determines an enlargement / reduction ratio of the image in a swing direction of the swing mirror based on a control amount of the optical element or a physical amount related thereto. .   The image display apparatus according to claim 2, wherein the conversion characteristic correction unit determines a correction amount of the position of the image according to a movement amount of the exit pupil.   The image display device according to claim 3, wherein the conversion characteristic correction unit determines a correction amount of the scale of the image according to a movement amount of the exit pupil.

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