Display apparatus and initial setting method for display apparatus

A method of initially setting a display apparatus, the method comprising:

• when a virtual image is formed in a portion of a virtual image forming region of an optical device based on light emitted from an image forming device, controlling a light regulating device so that a light shielding ratio of a virtual image projection region of the light regulating device where a projection image of the virtual image to the light regulating device is included is higher than a light shielding ratio of an other region of the light regulating device,
• setting a light shielding ratio of a region of the light regulating device corresponding to a virtual image of a test pattern higher than a light shielding ratio of the other region of the light regulating device,
• wherein the virtual image of the test pattern is displayed in the virtual image forming region based on the test pattern emitted from the image forming device,
• wherein the virtual image of the test pattern and a high light shielding ratio region of the light regulating device are moved relative to each other so that the virtual image of the test pattern observed by an observer and the high light shielding ratio region of the light regulating device observed by the observer overlap each other,
• wherein the display apparatus comprises:
• a frame that is mounted on a head of the observer;
• an image display device that is attached to the frame;
• and
• the light regulating device, wherein the light regulating device regulates a light amount of external light incident from an outside,
• wherein the image display device includes:
• the image forming device;
• and
• the optical device, wherein the optical device includes:
• the virtual image forming region where the virtual image is formed based on light emitted from the image forming device;
• and
• at least one diffraction grating member including at least one interference fringe, and
• wherein the virtual image forming region of the optical device overlaps the light regulating device, and
• determining comparisons between a first and second lateral length and between a first and second longitudinal length, wherein a virtual rectangle circumscribing the virtual image formed in the optical device has a first lateral length and a first longitudinal length, and wherein a shape of the virtual image projection region of the light regulating device is set to be a shape of a rectangle having a second lateral length and a second longitudinal length.