JP5163166B2 - Image display device - Google Patents

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 deflection mirror, which is an example of an optical element, in order to move the exit pupil of the image display device. As a result, when the deflection mirror is used, the exit pupil can be moved, but it has been found that the display image may be partially out of focus. The possibility and the cause will be described in detail later.

  Furthermore, the present inventor conducted research to eliminate or reduce the possibility that the displayed image partially becomes out of focus. As a result, if the wavefront curvature of the image light forming the display image is corrected, the possibility that the display image will be partially out of focus due to the movement of the exit pupil is eliminated or reduced. There was found.

  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 display device further includes:
A wavefront curvature modulation element for modulating the wavefront curvature of the image light;
Based on the control amount of the optical element or a physical quantity related to the control amount, the image light is transmitted via the wavefront curvature modulation element so that the change in the wavefront curvature of the image light due to the control of the optical element is canceled out. An image display device comprising: wavefront curvature correcting means for correcting the wavefront curvature of the image.

  According to this image display device, based on the control amount of the optical element or the physical quantity related to the control amount so that the change in the wavefront curvature of the image light due to the control of the optical element for moving the exit pupil is canceled out. The wavefront curvature of the image light is corrected.

  Therefore, according to this image display device, the change in the wavefront curvature of the image light due to the movement of the exit pupil is suppressed, and as a result, the deterioration of the image quality due to the movement of the exit pupil is suppressed.

(2) The wavefront curvature correcting means is
Determining means for determining a correction amount of the wavefront curvature for each position on the cross section of the image light based on a control amount of the optical element or a physical quantity related to the control amount;
The image display device according to (1), further comprising: a driving unit that drives the wavefront curvature modulation element in association with each position on the cross section of the image light so that the determined correction amount is realized.

  In one embodiment of the image display device, the cross section of the image light is divided into a plurality of regions, and the correction amount of the wavefront curvature of the image light is determined for each divided region. In this aspect, the wavefront curvature is discontinuously changed on the same cross section of the image light.

(3) 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 by changing the angle of the deflection mirror with respect to the incident light,
The image display device according to (1) or (2), wherein the wavefront curvature correction unit corrects the wavefront curvature of the image light based on an angle of the deflection mirror with respect to incident light or a physical quantity related to the angle.

(4) Further, a pupil position detection unit that detects the position of the pupil of the observer is included,
The exit pupil control means based on the output signal from the pupil position detection unit, in order to move the exit pupil so as to follow the movement of the pupil, (1) to control the optical element (3) The image display device according to any one of the items.

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

(5) 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 (3), 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.

  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 the planar light incident from the light source at the same time for each pixel using a spatial modulation element, and the 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. It has. 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 focal length of the variable focus lens 70 is changed. The variable focus lens 70 is an example of a wavefront curvature modulation element that modulates the wavefront curvature of light incident from the LCD 40. In order to change the focal length of the variable focus lens 70, the variable focus lens 70 is driven by a variable focus lens driver 72.

  The variable focus lens 70 can be a liquid crystal lens or a liquid lens whose refractive index or refractive power or lens shape is variable, but is not limited to this, for example, the light of the relay optical system 16. A movable lens whose position in the axial direction is variable is also possible. Some examples of each of the liquid crystal lens and the liquid lens are disclosed in Japanese Patent Application Laid-Open No. 2006-285182, which is incorporated herein by reference in its entirety.

  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 composed of a deflection mirror 80. The deflection mirror 80 is an example of an optical element for moving the exit pupil, and is an example of a reflective optical element. The deflection mirror 80 is disposed at a position that coincides with the position of a certain intermediate image plane in the head mounted display device 10.

  As shown in FIG. 2, the deflection mirror 80 is a oscillating mirror mounted on a frame 84 that can oscillate about the X axis extending in the horizontal direction so as to be oscillatable about the Y axis extending in the vertical direction. The frame 84 is swung by an X-axis actuator (not shown) mounted on a stationary member of the head mounted display device 10, while the deflection mirror 80 is swung by a Y-axis actuator (not shown) mounted on the frame 84. It is done. As a result, the angle of the deflection mirror 80 with respect to the stationary member in the head mounted display device 10 can be adjusted two-dimensionally.

  As shown in FIG. 1, the deflection mirror 80 is driven by a deflection mirror driver 88.

  Based on the pupil position detected by the pupil position detection unit 20, the exit pupil control unit 18 changes the angle of the deflection mirror 80 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 10 is moved.

  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 relay optical system 16 toward the deflection mirror 80 and reflects the transmitted light toward the eyepiece optical system 22. The half mirror 100 further transmits 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 100 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 80 to the eyepiece optical system 22. Is designed.

  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. 3 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 LED driver 32, the LCD driver 42, the pupil position detection circuit 102, the deflection mirror driver 88, and the variable focus lens driver 72 are electrically connected to the input interface 126.

  As shown in FIG. 3, the signal processing device 120 generally generates a signal necessary for displaying the content based on the 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.

  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 84, and outputs these image signals to the LCD driver 42. To supply.

  As shown in FIG. 4, in the memory unit 124, an image display program, a pupil tracking program, and a wavefront curvature correction program are stored in advance 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. 5 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.

  At the time of execution, 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 pupil is detected based on the signal from the pupil position detection circuit 102. The vertical position Y is detected.

  Subsequently, in step S3, based on the detected horizontal position X, the angle at which the deflection mirror 80 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 80 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 rotation angle amount from the neutral position around the Y axis of the deflection mirror 80 is stored as a table in the memory unit. The angle change amount about the Y axis of the deflection mirror 80 corresponding to the current value of the horizontal position X of the pupil is determined in accordance with the relationship.

  Thereafter, in step S4, in accordance with step S3, based on the detected vertical position Y, the angle at which the deflection mirror 80 should rotate around the X axis in order to track the pupil position in the vertical direction, The amount of change in the angle around the X axis (including the direction in which the deflection mirror 80 is rotated) is determined.

  In the present embodiment, the correspondence between the vertical position Y (the amount of vertical displacement of the pupil position from the neutral position) and the rotation angle amount around the X axis of the deflection mirror 80 is stored as a table in the memory unit. The angle change amount around the X axis of the deflection mirror 80 corresponding to the current value of the vertical position Y of the pupil is determined in accordance with the relationship.

  Subsequently, in step S5, a control signal to be output to the deflection mirror driver 88 to realize the angle change amount around the Y axis and the angle change amount around the X axis determined in steps S3 and S4, respectively, is generated.

  Thereafter, in step S6, the generated control signal is output to the deflecting mirror driver 88. 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. 6 conceptually shows a flowchart of the above-described wavefront curvature correction program.

  7 and 8 show the light paths among the relay optical system 16, the half mirror 100, the deflection mirror 80, and the eyepiece optical system 22 in the head mounted display device 10 shown in FIG. ing. 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. 7 shows an image plane formed by light emitted from the eyepiece optical system 22 when the deflection mirror 80 is in the neutral position and the exit pupil coincides with the neutral position P1. Here, “the state in which the deflecting mirror 80 is in the neutral position” is a state in which all points on the deflecting mirror 80 are located on the intermediate image plane shown in FIG. 9. In other words, the deflection mirror 80 is in a state of being entirely coincident with the intermediate image plane.

  In this case, the image plane is a plane perpendicular to the optical axis of the eyepiece optical system 22, and all the pixels constituting the image formed on the image plane are focused on the retina without blur. That is, the observer can observe the image in a focused state at all positions in the image.

  On the other hand, in FIG. 8, when the deflection mirror 80 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 eyepiece optical system 22 is used. The image plane formed by the light emitted from is shown. Here, “the state in which the deflection mirror 80 is in a position rotated from the neutral position” means that not all points on the deflection mirror 80 are located on the intermediate image plane as shown in FIG. 9. It is. That is, the deflecting mirror 80 is not entirely coincident with the intermediate image plane.

  In the case shown in FIG. 8, when attention is paid to a plurality of light beams forming a plurality of pixels constituting a two-dimensional image at each moment, as shown in FIG. , The light beam incident on the portion close to the exit pupil (in FIG. 8, the upper part of the deflecting mirror 80) is reflected at a position before the intermediate image plane and travels toward the exit pupil. The optical path length, which is the distance to the final image plane (hereinafter simply referred to as “optical path length”), is shorter than when the exit pupil is at the neutral position P1.

  On the other hand, as shown in FIG. 8, in the deflection mirror 80, the light incident on the portion far from the exit pupil with respect to the intermediate image plane (the lower portion of the deflection mirror 80 in FIG. 8) Since the light is reflected at a position far from the surface and travels toward the exit pupil, the optical path length becomes longer than when the exit pupil is at the neutral position P1.

  Thus, the optical path length changes from the original length according to the position where the light beam enters the deflection mirror 80 (the height of the pixel formed by the light beam in the image). The divergence angle changes from the original angle. Therefore, although there are a plurality of light beams for forming the same two-dimensional image, an optical path length difference and a spread angle difference are generated between the light beams.

  In short, as shown in FIG. 9, when the deflection mirror 80 is at a position rotated from the neutral position and does not entirely coincide with the intermediate image plane, a plurality of lines are formed for forming the same image. Of the light beam will be inconsistent with respect to the optical path length. Furthermore, the size of the virtual image is also larger than dB when the deflection mirror 80 is entirely coincident with the intermediate image plane.

  When the exit pupil is located at the neutral position P1, the image light has a wavefront curvature common to the entire cross section of the image light at the pupil position. On the other hand, when the exit pupil moves from the neutral position P1 to the position P2, an optical path length difference and a spread angle difference are generated between a plurality of light beams for forming the same two-dimensional image. At the pupil position, the entire cross section of the image light has a wavefront curvature that is not common.

  As a result, the final image plane formed in the observer's eyeball by the image light is not perpendicular to the optical axis of the eyepiece optical system 22 and the optical axis of the observer's eyeball lens, and thus the retina of the observer It will be inclined with respect to the surface. Therefore, the observer is forced to perceive the image as a partially out-of-focus image.

  Therefore, in this embodiment, as shown in FIG. 10, when it is necessary to move the exit pupil so that a wavefront curvature difference and a spread angle difference are generated between a plurality of light beams forming the same image. The wavefront curvature difference and the spread angle difference are generated in the opposite directions between the plurality of rays so that the wavefront curvature difference and the spread angle difference are canceled out. In the present embodiment, the modulation of the wavefront curvature, that is, the modulation of the beam divergence angle, suppresses the inclination of the final image plane caused by the movement of the exit pupil, and hence the out-of-focus display image.

  Here, referring to FIG. 11 to FIG. 13, in order to suppress the inclination of the final image plane due to the movement of the exit pupil, the wavefront curvature of the image light is determined for each position on the cross section of the image light. An algorithm for correcting will be described.

  First, a variable focus lens 70 is used to correct the wavefront curvature. Image light having a planar shape is incident on the variable focus lens 70 from the LCD 40 at each moment. Therefore, unless special measures are taken, the wavefront curvature of the image light cannot be modulated for each position on the cross section of the image light.

  In the present embodiment, as shown in FIG. 11, one frame for displaying an image is divided into three regions by two parallel straight lines extending in the vertical direction. The first provisional value of the wavefront curvature correction amount is determined for each region. Three wavefront curvature radius correction amounts are respectively assigned to these three regions according to one of a plurality of modes.

  Mode 0 is a mode in which the wavefront curvature is not corrected in any region. Mode +1 is a mode for correcting the wavefront curvature of each of the three regions in a symmetric pattern with respect to the image center and by a small amount. Mode-1 is a mode for correcting the wavefront curvature of each of the three regions in a pattern opposite to that of mode + 1. Mode +2 is a mode for correcting the wavefront curvature of each of the three regions with a pattern symmetrical with respect to the center of the image and by an amount larger than that of mode + 1. Mode-2 is a mode for correcting the wavefront curvature of each of the three regions in a pattern opposite to that of mode + 2.

  In the present embodiment, as shown in FIG. 12, one frame for displaying an image is further divided into three regions by two parallel straight lines extending in the horizontal direction. A second provisional value of the wavefront curvature correction amount is determined for each region. Three wavefront curvature radius correction amounts are respectively assigned to these three regions according to one of a plurality of modes.

  These modes are mode 0, mode + 1, mode-1, mode + 2, and mode-2, and are common to the plurality of modes shown in FIG.

  As shown in FIG. 13, in the present embodiment, one frame is finally divided into 9 (= 3 × 3) areas. Each region includes a first provisional value (horizontal correction amount) of a wavefront curvature correction amount corresponding to one of the five modes (horizontal mode) shown in FIG. 11 assigned to each region, and FIG. A composite value with the second provisional value (vertical correction amount) of the wavefront curvature correction amount corresponding to the one assigned to each region among the five modes (vertical direction mode) is finally assigned. An example of the composite value is a simple sum of the first provisional value and the second provisional value.

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

  This wavefront curvature correction program is periodically and repeatedly executed while the power of the head mounted display device 10 is turned on.

  At the time of each execution, first, in step S101, the horizontal direction of the exit pupil according to the angle change amount (deviation amount from the neutral position) of the deflection mirror 80 determined by the execution of step S3 shown in FIG. The amount of movement (the amount of deviation from the neutral position) is determined.

  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 S1 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 80 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 S102, in accordance with step S101, the angle of the exit pupil is changed according to the angle change amount (deviation amount from the neutral position) of the deflection mirror 80 determined by execution of step S4 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 S2 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 80 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 S103, for each of the three regions shown in FIG. 11, the horizontal wavefront curvature correction amount (first value) to be realized in order to suppress the horizontal inclination of the final image plane due to the horizontal movement of the exit pupil. 1 provisional value) is determined. The magnitude of the horizontal wavefront curvature correction amount is determined based on the horizontal movement amount of the exit pupil (horizontal deviation amount from the neutral position). Specifically, the current horizontal wavefront curvature correction is performed in accordance with a predetermined relationship between the horizontal movement amount of the exit pupil and the horizontal wavefront curvature correction amount, which is stored in the memory unit 124 in advance. The amount is determined.

  Thereafter, in step S104, the vertical wavefront curvature correction amount (second value) to be realized in order to suppress the vertical inclination of the final image plane due to the vertical movement of the exit pupil in each of the three regions shown in FIG. Provisional value) is determined. The magnitude of the vertical wavefront curvature correction amount is determined based on the vertical movement amount of the exit pupil (vertical shift amount from the neutral position). Specifically, according to a predetermined relationship between the vertical movement amount of the exit pupil and the vertical wavefront curvature correction amount that is stored in advance in the memory unit 124, the current vertical wavefront curvature correction is performed. The amount is determined.

  Subsequently, in step S105, for each of the nine areas shown in FIG. 13, as a combined value of the corresponding horizontal wavefront curvature correction amount (first provisional value) and vertical wavefront curvature correction amount (second provisional value). The composite correction amount is determined.

  Subsequently, in step S106, the original image signal is fetched from the R / G / B buffer 130. Thereafter, in step S107, each of a series of a plurality of frames represented by the captured original image signal is divided into nine subframes so as to correspond to the nine regions described above. A subframe signal is generated from the image signal. The image display program shown in FIG. 4 is executed to display an image by supplying the generated subframe signal to the LCD driver 42.

  Subsequently, in step S108, a control signal for controlling the varifocal lens 70 is generated so that the corresponding combined correction amounts are sequentially realized for the nine regions described above. Thereafter, in step S109, the plurality of generated control signals are sequentially output to the variable focus lens driver 72 so as to be synchronized with the supply of the corresponding subframe signals to the LCD driver 42.

  This completes one execution of the wavefront curvature correction program.

  Therefore, according to the present embodiment, regardless of whether or not the exit pupil moves, the observer can observe the image without defocusing. 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 variable focus lens 70 and the portion of the signal processing device 120 that executes the pupil tracking program shown in FIG. 5 constitutes an example of the “exit pupil control unit” in the section (1), and the portion of the signal processing device 120 that executes the pupil tracking program shown in FIG. The portion of the signal processing device 120 that executes the wavefront curvature correction program shown in FIG. 6 constitutes an example of “wavefront curvature correction means” in the same term, and the deflection mirror 80 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 part of the signal processing device 120 that executes steps S101 to S105 shown in FIG. 6 constitutes an example of the “determination means” in the section (2), and performs signal processing. It can be considered that the part of the apparatus 120 that executes steps S108 and S109 shown in FIG. 6 and the variable focus lens driver 72 cooperate with each other to constitute an example of “driving means” in the same section. is there.

  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 emitted laser beam. The laser beams of three colors emitted from the lasers 160, 162, and 164 are combined as one laser beam reflecting the color of the corresponding pixel at each moment. The combined 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 variable focus lens 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 manner 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.

  In the present embodiment, it is not an image light for one frame as in the first embodiment but a single light beam that enters the varifocal lens 70 at each moment. One light beam is two-dimensionally scanned to be converted into two-dimensional image light. One light beam corresponds to one pixel to be displayed at each moment.

  Therefore, in this embodiment, the wavefront curvature of the light beam is emitted by the variable focus lens 70 so as to synchronize with the movement of the position where one light beam is incident on the final image plane in the observer's eyeball. Modulation is performed so that the optical path length difference and divergence angle difference due to pupil movement are canceled out.

  Therefore, according to the present embodiment, regardless of whether or not the exit pupil moves, the observer can observe the image without defocusing. As a result, the display quality of the image by the head mounted display device 150 is improved. improves.

  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 a front view which expands and shows the deflection | deviation mirror 80 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. 5 is a flowchart conceptually showing a pupil tracking program shown in FIG. 5 is a flowchart conceptually showing a wavefront curvature correction program shown in FIG. FIG. 7 is an optical path diagram for explaining the wavefront curvature correction program shown in FIG. 6. It is another optical path diagram for demonstrating the wavefront curvature correction program shown in FIG. It is another optical path diagram for demonstrating the wavefront curvature correction program shown in FIG. FIG. 7 is still another optical path diagram for explaining the wavefront curvature correction program shown in FIG. 6. It is the figure and graph for demonstrating the wavefront curvature correction program shown in FIG. It is another figure and graph for demonstrating the wavefront curvature correction program shown in FIG. It is another figure for demonstrating the wavefront curvature correction program shown in FIG. It is an optical path figure showing notionally the head mounted display apparatus 150 according to 2nd Embodiment of this invention.

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 Variable focus lens 72 1st part 74 2nd part 80 Deflection mirror 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

Claims (5)

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 display device further includes:
A wavefront curvature modulation element for modulating the wavefront curvature of the image light;
Based on the control amount of the optical element or a physical quantity related to the control amount, the image light is transmitted via the wavefront curvature modulation element so that the change in the wavefront curvature of the image light due to the control of the optical element is canceled out. An image display device comprising: wavefront curvature correcting means for correcting the wavefront curvature of the image. The wavefront curvature correcting means is
Determining means for determining a correction amount of the wavefront curvature for each position on the cross section of the image light based on a control amount of the optical element or a physical quantity related to the control amount;
The image display apparatus according to claim 1, further comprising: a driving unit that drives the wavefront curvature modulation element in association with each position on a cross section of the image light so that the determined correction amount is realized. 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 by changing the angle of the deflection mirror with respect to the incident light,
The image display device according to claim 1, wherein the wavefront curvature correction unit corrects the wavefront curvature of the image light based on an angle of the deflection mirror with respect to incident light or a physical quantity related to the angle. In addition, a pupil position detector that detects the position of the pupil of the observer ,
The exit pupil control means based on the output signal from the pupil position detection unit, in order to move the exit pupil so as to follow the movement of the pupil, any of claims 1 to 3 for controlling the optical element An image display device according to claim 1.   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 4. The image display device according to any one of Items 1 to 3.

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