Video display device and control method

Abstract

Provided is a video display device wearable on the head of a user, wherein the video display device includes a video display unit capable of switching two or more display methods, a control unit for indicating a display method to the video display unit, a first detection unit for detecting the motion of the head of a user, a second detection unit for detecting the motion of the point of view of the user, and a motion determination unit for determining the motion state of the device user by using the output from the first detection unit and the output from the second detection unit. The control unit indicates a change of display methods to the video display unit in accordance with the determination result of the motion determination unit.

1 . A video display device wearable on a head of a user, comprising:
 a video display unit capable of switching a display method between two or more display methods;   a control unit that designates the display method for the video display unit;   a first detection unit that detects a movement of the head of the user;   a second detection unit that detects a movement of a viewpoint of the user; and   a motion determination unit that determines a motional state of the user of the device based on an output from the first detection unit and an output from the second detection unit, wherein   the control unit instructs the video display unit to change the display method according to a result of the determination made by the motion determination unit.   
     
     
         2 . The video display device according to  claim 1 , wherein
 the video display unit is a display using a liquid crystal element or a mirror array element, and   the two or more display methods are different from each other in at least one of an interval for updating information on pixels of the liquid crystal element or the mirror array element and an interval for driving a light source.   
     
     
         3 . The video display device according to  claim 1 , comprising video processing means capable of changing at least one of video parameters which are contrast, sharpness, saturation, hue, and image brightness, wherein
 the two or more display methods are methods in which at least one of the contrast, the sharpness, the saturation, the hue, and the image brightness is made different by the video processing means.   
     
     
         4 . The video display device according to  claim 2 , comprising video processing means capable of changing at least one of video parameters which are contrast, sharpness, saturation, hue, and image brightness, wherein
 the two or more display methods are methods in which at least one of the contrast, the sharpness, the saturation, the hue, and the image brightness is made different by the video processing means.   
     
     
         5 . The video display device according to  claim 2 , wherein
 based on the output from the first detection unit and the output from the second detection unit, the motion determination unit determines, as the motional state of the user, whether there is a movement of the head of the user, whether there is a movement of a line of sight of the user, whether the viewpoint of the user is on a video being displayed by the video display unit, and whether the movement of the head and the movement of the line of sight match each other.   
     
     
         6 . The video display device according to  claim 5 , wherein
 the larger the movement of the line of sight of the user relative to the movement of the head of the user, the control unit extends at least one of the interval for updating information on the pixels of the liquid crystal element or the mirror array element and the interval for driving the light source for the video display unit, and   the control unit lowers at least one of the contrast and the brightness of the video when the viewpoint of the user is not on the video being displayed by the video display unit.   
     
     
         7 . The video display device according to  claim 1 , further comprising:
 a storage unit that stores a change of any of the video parameters commanded by the control unit; and   a frequency determination unit that determines content of the change stored in the storage unit and the number of times the change has been made within a prescribed period of time, wherein   the frequency determination unit notifies a video information source of the change of the video parameter that has been changed many times.   
     
     
         8 . The video display device according to  claim 5 , wherein
 the video display unit is a field sequential display, and can perform black and white display by substantially synchronizing intervals of light emissions of all of light sources for R, G, and B, and   when the motion determination unit determines that there is at least one of the movement of the head of the user and the movement of the line of sight of the user, the control unit instructs the video display unit to perform the black and white display.   
     
     
         9 . The video display device according to  claim 5 , wherein
 the motion determination unit transforms an output vector from the first detection unit and an output vector from the second detection unit into two-dimensional vectors by orthographically projecting the output vectors onto a video display plane, and determines that the movement of the head and the movement of the line of sight match in direction when an angle between the two transformed two-dimensional vectors falls below a prescribed value.   
     
     
         10 . The video display device according to  claim 1 , wherein
 the first detection unit includes one of a gyro sensor, an acceleration sensor, a geomagnetic sensor, a GPS, and a camera.   
     
     
         11 . The video display device according to  claim 1 , wherein
 the control unit acquires information on an amount of power remaining in a power source and limits the change of the display method of the video display unit.   
     
     
         12 . A method for displaying a video on a video display unit wearable on a head of a user and capable of switching a display method between two or more display methods, the method comprising:
 causing a first detection unit to detect a movement of the head of the user;   causing a second detection unit to detect a movement of a viewpoint of the user;   causing a motion determination unit to determine a motional state of the user of the device based on an output from the first detection unit and an output from the second detection unit; and   instructing the video display unit to change the display method according to a result of the determination made by the motion determination unit.   
     
     
         13 . A method for detecting a movement of a line of sight or a viewpoint, comprising:
 detecting a movement of a line of sight using a first sensor element; and   in response to detection of the movement of the line of sight by the first sensor element, switching a status of a second sensor element between an operation state capable of detecting the line of sight and an idle state, the second sensor element being capable of detecting a movement of the line of sight more precisely than the first sensor element.   
     
     
         14 . A method for viewpoint deviation correction performed by a video display device wearable on a head of a user, comprising:
 displaying a prescribed point on the video display device;   prompting the user to gaze at the prescribed point;   determining a position of a point of gaze of the user using a viewpoint detection sensor;   setting the thus-determined position of the point of gaze as a reference point; and   based on a distance between the reference point and the viewpoint of the user detected by the viewpoint detection sensor, determining whether the viewpoint of the user is on a video being displayed.   
     
     
         15 . A line-of-sight detector comprising:
 at least two light emitters that irradiate different positions on an eye with light;   two light receivers that are located at different positions and receive light reflected by the eye irradiated with the light;   a movement detector that detects a movement of an eyeball based on outputs from the two light receivers; and   a camera that captures an image of at least one eye and operates while the movement detector is detecting the movement of the eyeball.