Head-mounted display, image display system, information storage device, and method for controlling head-mounted display

1. A head-mounted display that is worn on a head of a user, and allows the user to observe a display image, the head-mounted display comprising:

a display that displays the display image; and

a controller comprising hardware, the controller being configured to perform a control process that controls a timing at which the display image is displayed on the display,

the controller performing the control process that causes a display period and a non-display period to repeat alternately, and sets one display period to be equal to or less than 600 ms, the display period being a period in which the display image is displayed on the display, and the non-display period being a period in which the display image is not displayed on the display, and

the controller performing the control process to set a flight period to be the display period, and displays the display image on the display during the flight period, the flight period being a period in which both feet of the user do not make contact with the ground.

2. A head-mounted display that is worn on a head of a user, and allows the user to observe a display image, the head-mounted display comprising:

a display that displays the display image;

a controller comprising hardware, the controller being configured to perform a control process that controls a timing at which the display image is displayed on the display; and

a timer that performs a count process on the display period,

the controller performing the control process that causes a display period and a non-display period to repeat alternately, and sets one display period to be equal to or less than 600 ms, the display period being a period in which the display image is displayed on the display, the display period being set to be equal to or less than 600 ms based on the count process by the timer, and the non-display period being a period in which the display image is not displayed on the display, and

the controller performing the control process that determines whether or not the user is in a stationary state, and sets the display period to be equal to or less than 600 ms when it has been determined that the user is not in the stationary state, and sets the display period to be more than 600 ms when it has been determined that the user is in the stationary state.

3. The head-mounted display as defined in claim 1 , wherein the controller is further configured to:

acquire a motion sensor signal from a motion sensor that detects a motion of the user, and

set the display period and the non-display period based on the motion sensor signal.

4. The head-mounted display as defined in claim 1 , wherein the controller is further configured to:

perform a count process on the display period and the non-display period,

display the display image on the display when the count process on the display period is started,

start the count process up to an expiration timing of the non-display period when the count process up to an expiration timing of the display period has completed, and

stop display of the display image when the the count process on the non-display period is started.

5. The head-mounted display as defined in claim 1 , wherein the controller is further configured to switch a display state of the display image by causing an illumination light source to emit light during the display period, and causing the illumination light source not to emit light during the non-display period.

6. An image display system comprising:

the head-mounted display as defined in claim 1 ; and

an information terminal device that communicates with the head-mounted display.

7. A method for controlling a head-mounted display that is worn on a head of a user, and allows the user to observe a display image, the method comprising:

displaying the display image; and

performing a control process that controls a timing at which the display image is displayed, the control process:

causing a display period and a non-display period to repeat alternately, and setting one display period to be equal to or less than 600 ms, the display period being a period in which the display image is displayed, and the non-display period being a period in which the display image is not displayed, and

setting a flight period to be the display period, and displaying the display image during the flight period, the flight period being a period in which both feet of the user do not make contact with the ground.

8. A method for controlling a head-mounted display that is worn on a head of a user, and allows the user to observe a display image, the method comprising:

displaying the display image;

performing a control process that controls a timing at which the display image is displayed on the display, the control process:

performing a count process on the display period,

causing a display period and a non-display period to repeat alternately, the display period being a period in which the display image is displayed on the display and the non-display period being a period in which the display image is not displayed on the display,

determining whether or not the user is in a stationary state, and

setting the display period to be equal to or less than 600 ms when it has been determined that the user is not in the stationary state, and setting the display period to be more than 600 ms when it has been determined that the user is in the stationary state.