JP2015055869A - Virtual image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a virtual image display device that enables a viewing distance of an observer to be measured at an appropriate timing, and enables a projection distance of a virtual image to be adjusted.SOLUTION: A virtual image display device comprises: a display optical system 10 that displays a video picture; an eyepiece optical system 20 that projects the video picture displayed by the display optical system as a virtual image; a distance metering part 30 that measures a viewing distance to an object facing eyes of an observer or a gazing point of the observer; a projection distance adjustment part 40 that adjusts a projection distance of the virtual image projected by the eyepiece optical system on the basis of the viewing distance measured by the distance metering part; a field-of-view variation detection part 50 that detects a variation of a field-of-view direction of the observer; and a control part 60. Then, when the variation of the filed-of-view of the observer is detected by the field-of-view variation detection part, the control part sends out a control signal causing the distance metering part to start measurement of the viewing distance.

Description

  The present invention relates to a virtual image display device such as a head mounted display (hereinafter also referred to as an HMD) that is mounted on an observer's head. More specifically, in the virtual image display device of the present invention, an eyepiece optical system such as a prism is arranged in front of the observer's eye, and image light emitted from the display optical system such as a liquid crystal display is guided to the observer's optical pupil. With structure. As a result, the observer can visually recognize the virtual image projected by the eyepiece optical system in his field of view. In particular, the virtual image display device of the present invention is mainly intended to adjust the projection distance of a virtual image in a timely manner in accordance with the viewing distance to an object visually recognized by an observer.

  In recent years, there is an increasing demand for wearable devices that can be attached to a user's body, such as HMDs that are worn on the head. In addition, for example, computers, various sensor devices, and video display devices such as LCD (Liquid Crystal Display) have been miniaturized to such a degree that they can be mounted on wearable devices, and the development of wearable devices equipped with these devices has been rapid. Is progressing.

For example, Patent Documents 1 and 2 disclose conventional HMDs.
Patent Document 1 discloses an HMD that includes a shutter that blocks part or all of external light. According to the HMD of Patent Document 1, it is said that a display screen of a computer can be recognized while moving and working, and an eyepiece display device that is safe and has little eye fatigue can be provided.

  Patent Document 2 discloses an HMD that detects a visual distance from an observer's eye to a gazing point and projects a virtual image at the detected position of the gazing point. Thus, the HMD of Patent Document 2 has a so-called autofocus function. In particular, the HMD of Patent Document 2 has a configuration for displaying a stereoscopic image. That is, the HMD of Patent Document 2 generates display data of an image subjected to a defocus process based on image data of an original image composed of a plurality of pixels, distance data for each pixel, and viewing distance. The display element displays an image based on the generated display data.

JP-A-7-28021 JP-A-10-239634

  As in the HMD described in Patent Document 2, the technique for measuring the visual distance from the observer's eye to the gazing point and projecting a virtual image at the position of the gazing point is a method in which the observer is clearly out of focus. It is thought that it is effective because it makes it possible to see a virtual image that is not visible.

  However, in the conventional HMD, the viewing distance from the observer to the gazing point is always measured, and the projection distance of the virtual image is constantly adjusted based on the viewing distance. As described above, when the viewing distance of the observer is constantly measured, there is a problem that the battery consumption of the HMD increases, which is inefficient. For example, when an observer is reading a book, the viewing distance of the observer may hardly change over a long period of time. In such a case, even if the viewing distance of the observer is measured, the viewing distance of the observer hardly changes. Therefore, it is not necessary to adjust the projection distance of the virtual image. However, the conventional HMD does not have a configuration for stopping the measurement of the viewing distance when the viewing distance of the observer does not change, and includes problems in terms of energy loss such as battery consumption. there were.

  For this reason, at present, there is a demand for a technique that enables measurement of the visual distance at an appropriate timing in an HMD equipped with a mechanism that adjusts the projection distance of a virtual image based on the visual distance of the observer. .

Therefore, as a result of intensive studies on the means for solving the above-described problems of the conventional invention, the inventor of the present invention, for example, when the observer's visual distance needs to be measured is when the observer's head moves. As shown in the figure, it was found that this was the time when the observer's field of view changed. That is, the inventor of the present invention measures the viewing distance of the observer only when a change in the viewing direction of the observer is detected, and adjusts the projection distance of the virtual image based on the measurement result. The knowledge that consumption can be saved was obtained. The inventor has conceived that the problems of the prior art can be solved based on the above knowledge, and has completed the present invention.
More specifically, the present invention has the following configuration.

The present invention relates to a virtual image display device such as a head mounted display (HMD) mounted on an observer's head.
The virtual image display device of the present invention includes a display optical system 10, an eyepiece optical system 20, a distance measurement unit 30, a projection distance adjustment unit 40, a visual field variation detection unit 50, and a control unit 60.
The display optical system 10 includes a display element for displaying an image.
The eyepiece optical system 20 projects the image displayed by the display optical system 10 as a virtual image. That is, the eyepiece optical system 20 includes a prism for guiding the image light emitted from the display optical system 10 to the optical pupil of the observer.
The distance measuring unit 30 measures the viewing distance. Here, the “viewing distance” means a distance to an object facing the observer's eye or a distance to the observer's point of interest. The “viewing distance” may be a distance from a sensor provided in the distance measuring unit 30 to an object facing the observer's eye. Alternatively, the “viewing distance” may be a distance from the observer's eye to the gazing point.
The projection distance adjustment unit 40 includes a mechanism for adjusting the projection distance of the virtual image projected by the eyepiece optical system 20 based on the viewing distance measured by the distance measurement unit 30.
The visual field fluctuation detection unit 50 detects a fluctuation in the visual field direction of the observer.
When the visual field fluctuation detection unit 50 detects a change in the visual field direction of the observer, the control unit 60 sends a control signal for starting the measurement of the visual distance to the distance measuring unit 30.

  As described above, the control unit 60 of the virtual image display device according to the present invention measures the visual distance with respect to the distance measuring unit 30 only when the visual field variation detection unit 50 detects the variation in the visual field direction of the observer. To do. For example, the distance measuring unit 30 measures the viewing distance when the field of view is changed by moving the head of the observer or the field of view is changed by moving the eyes of the observer. Then, based on the viewing distance measured by the distance measuring unit 30, the projection distance adjusting unit 40 changes the projection distance of the virtual image visually recognized by the observer. In this way, by measuring the viewing distance at the timing when the observer's field of view fluctuates, the projection position of the virtual image can be adjusted efficiently and without waste. Therefore, the HMD of the present invention can save battery consumption.

  In the virtual image display device of the present invention, it is preferable that the visual field variation detection unit 50 includes either or both of the gyro sensor 51 and the acceleration sensor 52. And it is preferable that the visual field fluctuation | variation detection part 50 judges that there was the fluctuation | variation of the observer's visual field direction, when the change beyond a fixed threshold value is detected by the sensor.

  By providing the virtual image display device with the gyro sensor 51 and / or the acceleration sensor 52 as in the above configuration, it is possible to detect that the orientation of the observer's head has changed. That is, when the orientation of the observer's head changes, it can be estimated that the observer's visual field has changed. Therefore, based on information obtained from the gyro sensor 51 or the acceleration sensor 52 or information obtained by combining information obtained from the gyro sensor 51 and the acceleration sensor 52, a change in the viewing direction of the observer can be appropriately detected. It is.

  In the virtual image display device of the present invention, the visual field fluctuation detection unit 50 detects changes greater than a certain threshold by sensors (gyro sensor 51, acceleration sensor 52, luminance sensor 53), and detects variations greater than a certain threshold. It is preferable to determine that there has been a change in the viewing direction of the observer when the non-performed time continues for a predetermined time.

  As in the above configuration, it is possible to prevent the measurement of the viewing distance from being wasted by setting the condition for starting the measurement of the viewing distance that the time during which the change beyond a certain threshold is not detected by the sensor is continued for a predetermined time. . That is, for example, when an observer is running, it is conceivable that the gyro sensor 51 or the acceleration sensor 52 detects a change of a certain threshold value or more many times in a short time. However, it can be said that it is almost meaningless to measure the viewing distance repeatedly and adjust the projection distance of the virtual image repeatedly in a situation where the observer is moving violently. Therefore, for example, only when the observer stops moving and stares at an object for a few seconds (for example, 0.5 to 3 seconds or more), the viewing distance of the observer is measured and It can be said that it is effective to match the virtual image projection distance to the distance. As described above, in the preferred embodiment of the present invention, it is possible to appropriately detect the state in which the observer is looking at some object, and to adapt the projection distance of the virtual image to the viewing distance of the observer.

  In the virtual image display device of the present invention, the visual field fluctuation detection unit 50 may have a luminance sensor 53. In this case, the visual field variation detection unit 50 may determine that there has been a variation in the visual field direction of the observer when the luminance sensor 53 detects a change in luminance that exceeds a certain threshold.

  According to the above configuration, for example, although the position of the observer's head is not changed, the viewing distance of the observer can be measured when the observer's field of view is opened. For example, in a situation where an observer is in a car and stares out of a window, the observer's field of view opens up when he or she goes out of a dark tunnel and looks farther away. It is assumed that they will come to stare. For this reason, when the luminance around the HMD changes more than a certain level, the projection distance of the virtual image can be adjusted to an appropriate position by measuring the viewing distance of the observer.

  The present invention provides a virtual image display device having a mechanism for adjusting a projection distance of a virtual image based on a viewing distance of an observer, and includes a visual field variation detection unit that detects a variation in the visual field direction of the observer, thereby providing the viewing distance. Can be measured at an appropriate timing.

FIG. 1 is an external perspective view showing an example of an HMD according to the present invention. FIG. 2 is a block diagram showing an optical component of the HMD according to the present invention. FIG. 3 is a functional block diagram of the HMD according to the present invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below, but includes those appropriately modified by those skilled in the art from the following embodiments.

  FIG. 1 is an external perspective view showing an example of a virtual image display device, particularly a head mounted display (HMD) 100 according to the present invention. FIG. 2 is a block diagram schematically showing an optical system that guides image light to the observer's optical pupil. In particular, FIG. 2 shows a video display device provided at a location surrounded by a broken-line frame in FIG. FIG. 3 is a functional block diagram showing various modules provided in the HMD 100.

  As shown in FIG. 1, the HMD 100 of the present invention is a device that is used by being worn on the observer's head. The HMD 100 includes a video display device (portion surrounded by a frame line) disposed in front of one eye (for example, the right eye) of the observer. The HMD 100 can allow an observer to visually recognize an image by using the image display device.

  As shown in FIGS. 2 and 3, the HMD 100 of the present invention includes a display optical system 10, an eyepiece optical system 20, a distance measurement unit 30, a projection distance adjustment unit 40, a visual field variation detection unit 50, and a control. Part 60. The control unit 60 is a CPU that comprehensively performs electronic control of these modules.

  In brief, the HMD 100 guides the image light displayed by the display optical system 10 to the observer's optical pupil E through the eyepiece optical system 20. The eyepiece optical system 20 projects the image displayed by the display optical system 10 as a virtual image, and the observer can visually recognize the virtual image. The HMD 100 has a so-called autofocus function. That is, the HMD 100 measures the viewing distance of the observer by the distance measuring unit 30. Then, based on the measured value, the projection distance adjusting unit 40 adjusts the projection distance of the virtual image, and the virtual image is displayed at a position where the observer can easily recognize. Furthermore, the HMD 100 of the present invention includes a visual field fluctuation detection unit 50 for detecting an observer's visual field fluctuation. Then, when the visual field variation detection unit 50 detects the observer's visual field variation, the control unit 60 of the HMD 100 sends a control signal to the distance measuring unit 30 so as to start measuring the viewing distance of the observer. Send it out.

  As shown in FIGS. 2 and 3, the display optical system 10 includes a light source 11, a condenser lens 12, and a display element 13. The light source 11 preferably emits light of each color of R (red), G (green), and B (blue). The light source 11 is preferably composed of, for example, an RGB integrated LED panel. The light source 11 may emit monochromatic light or white light. The condensing lens 12 condenses the light from the light source 11 and supplies it to the display element 13. The display element 13 displays an image by modulating incident light according to image data. The display element 13 is preferably composed of, for example, a transmissive liquid crystal display element in which pixels serving as light transmitting regions are arranged in a matrix. Thus, an example of the display optical system 10 is a liquid crystal display (LCD).

  The eyepiece optical system 20 is an optical system that guides the image light from the display element 13 to the optical pupil E. The eyepiece optical system 20 has, for example, a prism 21. The prism 21 is a light guide member that guides the image light from the display element 13 inside. The prism 21 has a shape having an incident surface 21a for image light, a total reflection surface 21b, and an exit surface 21c. The prism 21 may be constituted by a single prism or may be constituted by combining a plurality of prisms. The incident surface 21a of the prism 21 is provided in the depth direction perpendicular to the optical axis of the image light traveling in the lateral direction. The exit surface 21c is provided so as to face the optical pupil E of the observer. The total reflection surface 21b has a rectangular shape (rectangular shape), for example, and functions as means for bending the optical path of the image light at a right angle. Specifically, the total reflection surface 21b totally reflects the image light that enters the prism through the incident surface 21a and travels in the lateral direction toward the front in the depth direction.

  According to the above configuration, the light emitted from the light source 11 is collected by the condenser lens 12 and enters the display element 13. The light is modulated by the display element 13 to become image light. Thereafter, the image light emitted from the display element 13 enters the eyepiece optical system 20. In the eyepiece optical system 20, the image light enters the prism 21 via the incident surface 21a. Thereafter, the image light travels in the prism 21 along the horizontal direction, and the optical path is bent at the total reflection surface 21b and travels in the direction toward the depth direction. As a result, the image light is guided to the observer's optical pupil E via the exit surface 21 c of the prism 21. In this way, the observer can observe an enlarged virtual image of the image displayed on the display element 13 at the position of the optical pupil E.

  That is, when the HMD 100 of the present invention is mounted, the image displayed by the display optical system 10 reaches the observer's optical pupil E through the eyepiece optical system 20. The eyepiece optical system 20 forms an enlarged virtual image V at a position away from the actual position of the total reflection surface 21b of the prism 21. In this way, the observer can visually recognize the virtual image V projected by the eyepiece optical system 20, and it looks as if the image is superimposed on the real world scenery.

  The HMD of the present invention further includes a distance measuring unit 30 and a projection distance adjusting unit 40. Thereby, an autofocus function for automatically adjusting the projection position of the virtual image V can be mounted on the HMD 100.

  First, the distance measuring unit 30 has a function of measuring the “viewing distance” of the observer. The “viewing distance” here means the distance to the object O facing the observer's optical pupil E, or the distance from the observer's optical pupil E to the gazing point.

  In the example illustrated in FIG. 2, the distance from the distance measuring sensor 31 included in the distance measuring unit 30 to the distance from the object O is defined as “viewing distance”. In this case, the distance measuring sensor 31 may be an active sensor provided with a device that emits and receives infrared rays or ultrasonic waves, or may be a passive sensor provided with a CCD camera. For example, an active sensor irradiates an object O facing an observer's optical pupil E with infrared rays or ultrasonic waves, and detects the distance to the object O based on the time until the reflected wave returns and the irradiation angle. Can do. On the other hand, the passive sensor can measure the distance to the object O using the image captured by the lens of the CCD camera. Known methods such as a phase difference detection method, a contrast detection method, and a passive external light method can be used as a passive distance measurement method. The distance measuring sensor 31 is preferably attached, for example, around the eyepiece optical system 20 (position within a radius of 20 mm).

  In the example shown in FIGS. 2 and 2, an infrared sensor is used as the distance measuring sensor 31. The distance measuring sensor 31 irradiates the object O with infrared rays and receives the reflection group. Information acquired by the distance measuring sensor 31 is sent to the distance measuring unit 30. The distance measuring unit 30 analyzes information obtained by using the distance measuring sensor 31 and obtains a distance (viewing distance) from the distance measuring sensor 31 to the object O. In FIG. 2, the viewing distance is indicated by a symbol S.

  However, although illustration is omitted, the “viewing distance” of the observer may be defined as the distance from the optical pupil E of the observer to the gazing point. In this case, the distance measuring sensor 31 provided in the distance measuring unit 30 may be a sensor that observes the optical pupil E and detects the refractive power of the optical pupil E. The distance measuring unit 30 can specify the position of the gazing point on which the optical pupil E is focused based on the refractive power obtained from the distance measuring sensor 31. In this way, the distance measuring unit 30 can also measure the distance (viewing distance) from the observer's optical pupil E to the gazing point.

  When the viewing distance is measured by the distance measuring unit 30, data related to the viewing distance is sent to the control unit 60. The control unit 60 sends data related to the viewing distance to the projection distance adjustment unit 40. The projection distance adjustment unit 40 can adjust the projection distance of the virtual image V projected by the eyepiece optical system 20 based on the data regarding the viewing distance.

  As shown in FIGS. 2 and 3, for example, the projection distance adjustment unit 40 includes a correction lens 41. As shown in the example of FIG. 2, the correction lens 41 is preferably disposed between the display optical system 10 and the eyepiece optical system 20 on the optical axis of the image light emitted from the display optical system 10.

  The projection distance adjustment unit 40 adjusts the projection distance of the virtual image V using the correction lens 41. The method by which the projection distance adjustment unit 40 adjusts the projection distance of the virtual image V can be appropriately selected from known methods, and is not particularly limited.

  For example, in the example shown in FIG. 2, the projection distance adjustment unit 40 has a mechanism for moving the correction lens 41 forward and backward along the traveling direction of the image light. That is, the projection distance adjustment unit 40 adjusts the area where the image light is collected on the total reflection surface 21 of the prism 21 by moving the physical position of the correction lens 41 back and forth. As described above, the projection distance adjusting unit 40 may adjust the projection distance of the virtual image V by adjusting the position of the correction lens 41.

  For example, although not shown, the correction lens 41 may be a variable focus lens such as a liquid lens. For example, in a liquid lens, an aqueous solution and oil are sealed in a lens holder (container), and the shape of the boundary surface between the aqueous solution and oil can be changed by applying a voltage to the aqueous solution from the upper and lower electrodes of the container. Thereby, in the liquid lens, the boundary surface between the aqueous solution and the oil becomes a lens, and the focal length can be adjusted by changing the voltage. Thus, when a liquid lens is used as the correction lens 41, the projection distance adjustment unit 40 only needs to include a mechanism for adjusting the voltage applied to the electrode provided in the correction lens 41. As described above, the projection distance adjustment unit 40 may adjust the projection distance of the virtual image V by adjusting the focal position of the correction lens 41 (liquid lens).

  In addition, although illustration is omitted, the projection distance adjustment unit 40 may include a plurality of correction lenses 41 having different focal positions (flexibility). Then, the projection distance adjustment unit 40 may adjust the projection distance of the virtual image V by physically changing the type of lens inserted between the display optical system 10 and the eyepiece optical system 20.

  As described above, the projection distance adjustment unit 40 can automatically adjust the projection distance of the virtual image V based on the data regarding the viewing distance measured by the distance measurement unit 30.

  Furthermore, the HMD 100 of the present invention includes a visual field fluctuation detection unit 50 that detects fluctuations in the observer's visual field direction. When the visual field fluctuation detection unit 50 detects the fluctuation of the observer's visual field direction, the visual field fluctuation detection unit 50 sends information to that effect to the control unit 60. Only when information is received from the visual field fluctuation detection unit 50, the control unit 60 sends a command signal to the distance measurement unit 30 so as to start measuring the visual distance. The distance measuring unit 30 does not measure the viewing distance unless it receives a command signal from the control unit 60. Accordingly, it is possible to prevent the distance measuring unit 30 from continuously measuring the viewing distance, and thus it is possible to suppress consumption of a battery (not shown) provided in the HMD 100.

  In the embodiment shown in FIGS. 2 and 3, the visual field fluctuation detection unit 50 includes a gyro sensor 51 and an acceleration sensor 52. The visual field fluctuation detection unit 50 may include a luminance sensor 53. The gyro sensor 51, the acceleration sensor 52, and the luminance sensor 53 may be attached at any position of the HMD 100, but are preferably arranged around the display optical system 10 and the eyepiece optical system 20, for example. . Since the gyro sensor 51, the acceleration sensor 52, and the luminance sensor 53 are known sensors, known sensors may be used as appropriate.

  More specifically, the gyro sensor 51 detects the angular velocities around the three axes set in the HMD 100 and sends an angular velocity value indicating the detected angular velocities to the visual field fluctuation detection unit 50. The angular velocity value detected by the gyro sensor 51 changes in accordance with the direction (inclination angle) and movement of the HMD 100 itself. For this reason, the visual field fluctuation detection unit 50 can calculate the direction and movement of the HMD 100 using the angular velocity value acquired by the gyro sensor 51.

  Further, the acceleration sensor 52 detects acceleration (including gravitational acceleration) generated in the HMD 100 and sends an acceleration value indicating the detected acceleration to the visual field fluctuation detection unit 50. The acceleration value detected by the acceleration sensor 52 changes according to the direction (tilt angle) and movement of the HMD 100 itself. For this reason, the visual field fluctuation detection unit 50 can calculate the orientation and movement of the HMD 100 using the acceleration value acquired by the acceleration sensor 52.

  In addition, the luminance sensor 53 detects the luminance (including lightness) of external light around the HMD 100 and sends a luminance value indicating the detected luminance to the visual field fluctuation detection unit 50. The luminance value detected by the luminance sensor 53 changes according to the amount of light around the HMD 100 and the like. Therefore, the visual field fluctuation detection unit 50 can calculate the brightness of the space around the HMD 100 using the brightness value acquired by the brightness sensor 53.

The visual field fluctuation detection unit 50 can detect fluctuations in the visual field of the observer based on changes in various values acquired by the gyro sensor 51, the acceleration sensor 52, or the luminance sensor 53 described above. For example, the visual field fluctuation detection unit 50 can determine that there is an observer's visual field fluctuation when the angular velocity value detected by the gyro sensor 51 changes by a predetermined threshold or more with respect to a certain reference value. . In addition, for example, the visual field fluctuation detection unit 50 determines that there is a visual field fluctuation of the observer when the acceleration value detected by the acceleration sensor 52 changes by a predetermined threshold or more with respect to a certain reference value. Can do. Similarly, the visual field fluctuation detection unit 50 can determine that there has been an observer's visual field fluctuation when the luminance value detected by the luminance sensor 53 changes by a predetermined threshold or more with respect to a certain reference value. it can.
The visual field fluctuation detection unit 50 may detect not only visual field fluctuations by appropriately combining these data, but also using the data detected by these sensors 51 to 53 alone.

  For example, the change in the angular velocity value and the acceleration value acquired by the gyro sensor 51 and the acceleration sensor 52 means that the head of the observer has changed direction or moved. For this reason, when the observer's head changes its direction, the observer's visual field direction naturally changes. It can be assumed that the viewing distance of the observer has changed when the viewing direction of the observer has changed. For this reason, by using the data obtained from the gyro sensor 51 and the acceleration sensor 52 as a trigger for measuring the viewing distance of the observer, at an appropriate timing (timing when the object visually recognized by the observer changes), Distance measurements can be made.

  Also, the change in the brightness value acquired by the brightness sensor 53 means that the brightness of the environment around the observer has changed. In this way, by using the information obtained by the luminance sensor 53, for example, although the position of the observer's head is not changed, the viewing distance of the observer is measured when the observer's field of view is opened. be able to. For example, in a situation where an observer is in a car and stares out of a window, the observer's field of view opens up when he or she goes out of a dark tunnel and looks farther away. It is assumed that they will come to stare. For this reason, when the luminance around the HMD changes more than a certain level, the projection distance of the virtual image can be adjusted to an appropriate position by measuring the viewing distance of the observer.

  Further, the visual field fluctuation detection unit 50 detects the visual field of the observer when a change of a certain threshold value or more is detected by the sensors 51 to 53 and a time during which no change of the certain threshold value or more is subsequently detected continues for a predetermined time. It may be determined that the direction has changed. For example, the gyro sensor 51 will be described as an example. The visual field fluctuation detection unit 50 changes the visual field direction only when the direction of the HMD 100 does not change for a predetermined time after the direction of the HMD 100 changes by a predetermined threshold value or more. Judge that there was. That is, when the data detected by the gyro sensor 51 continuously and repeatedly changes, if the visual distance is measured many times, the projection distance of the virtual image also changes immediately. On the contrary, it becomes difficult for the observer to visually recognize the virtual image. On the other hand, it is considered that the angular velocity value acquired by the gyro sensor 51 does not change for a predetermined time when the observer is looking closely at an object (building or book). Only in such a case, by measuring the viewing distance of the observer and adjusting the projection distance of the virtual image, it becomes possible to cause the observer to visually recognize the chest image appropriately. Here, the “predetermined time” is a time for the observer to look at the object, and may be, for example, 0.5 to 6 seconds, 1 to 5 seconds, or 2 to 4 seconds.

  The preferred form of the visual field fluctuation detection unit 50 has been described above, but the form in which the visual field fluctuation detection unit 50 detects the observer's visual field fluctuation is not limited to the above-described form. For example, the visual field fluctuation detection unit 50 may include a sensor that traces the movement of the observer's black eyes. In this case, the visual field fluctuation detection unit 50 can determine that the visual field fluctuation of the observer has occurred when the black eye of the observer's eye moves.

  When the visual field fluctuation detection unit 50 determines that the observer's visual field fluctuation has occurred based on the change in the data obtained from the sensors 51 to 53 as described above, the control unit 60 sends a signal to that effect. To send to. Only when a signal is received from the visual field fluctuation detection unit 50, the control unit 60 sends a command signal for starting the measurement of the visual distance to the distance measurement unit 30. The distance measurement unit 30 uses the distance measurement sensor 31 to measure the viewing distance of the observer and transmits it to the control unit 60. The control unit 60 sends data regarding the viewing distance obtained from the distance measuring unit 30 to the projection distance adjusting unit 40. The projection distance adjustment unit 40 adjusts the projection distance of the virtual image V projected by the eyepiece optical system 20 by controlling the correction lens 41 based on the data regarding the viewing distance. In this way, according to the present invention, it is possible to measure the viewing distance of the observer and adjust the virtual image projection distance at an appropriate timing when the viewing direction of the observer has changed.

  As mentioned above, in this specification, in order to express the content of this invention, embodiment of this invention was described, referring drawings. However, the present invention is not limited to the above-described embodiments, but includes modifications and improvements obvious to those skilled in the art based on the matters described in the present specification.

    The present invention relates to a virtual image display device such as a head mounted display mounted on an observer's head. For this reason, this invention can be utilized suitably in the manufacture industry of a head mounted display.

DESCRIPTION OF SYMBOLS 10 ... Display optical system 11 ... Light source 12 ... Condensing lens 13 ... Display element 20 ... Eyepiece optical system 21 ... Prism 21a ... Incident surface 21b ... Total reflection surface 21c ... Outgoing surface 30 ... Distance measuring unit 31 ... Distance sensor 40 ... Projection distance adjustment unit 41 ... correction lens 50 ... field-of-view variation detection unit 51 ... gyro sensor 52 ... acceleration sensor 53 ... lightness sensor 60 ... control unit

Claims (4)

A display optical system (10) for displaying an image;
An eyepiece optical system (20) for projecting the image displayed by the display optical system (10) as a virtual image;
A distance measuring unit (30) for measuring a visual distance to an object facing the observer's eye or to the observer's gazing point;
A projection distance adjustment unit (40) for adjusting a projection distance of a virtual image projected by the eyepiece optical system (20) based on the viewing distance measured by the distance measurement unit (30);
A visual field fluctuation detection unit (50) for detecting fluctuations in the visual field direction of the observer;
A control unit that sends a control signal for starting the measurement of the viewing distance to the distance measuring unit (30) when the visual field variation detecting unit (50) detects a change in the visual field direction of the observer. (60) A virtual image display device comprising: The visual field fluctuation detection unit (50)
And / or a gyro sensor (51) and / or an acceleration sensor (52),
The virtual image display device according to claim 1, wherein when the sensor detects a change that is equal to or greater than a certain threshold, there is a change in the viewing direction of the observer. The visual field fluctuation detection unit (50)
3. A change in the viewing direction of the observer is determined when a change of a certain threshold value or more is detected by the sensor and a time when a change of a certain threshold value or more is not detected thereafter continues for a predetermined time. The virtual image display device described in 1. The visual field fluctuation detection unit (50)
Having a luminance sensor (53),
The virtual image display according to any one of claims 1 to 3, wherein when the luminance sensor (53) detects a change in luminance equal to or greater than a certain threshold value, there is a change in the viewing direction of the observer. apparatus.

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