Display apparatus

A display apparatus comprising:

• an image forming device that generates image light;
• and
• a light guide that guides the image light, wherein
• the light guide includes a first surface, a first mirror, and a second mirror,
• the image forming device causes the image light to enter an inside of the light guide from the first surface,
• the first mirror (i) causes a part of the image light guided inside the light guide to be reflected, and (ii) causes another part of the image light to be transmitted,
• the second mirror (i) causes a part of the image light guided inside the light guide to be reflected, and (ii) causes another part of the image light to be transmitted,
• the first mirror is disposed to be inclined with respect to the first surface,
• the second mirror is disposed to be inclined with respect to the first surface,
• in a plan view of the display apparatus, the first surface is disposed to be inclined with respect to a virtual plane perpendicular to a visual axis, and
• when (i) an inclination angle of the first surface with respect to the virtual plane is defined as a light guide angle α, (ii) an inclination angle of each of the first mirror and the second mirror with respect to the first surface is defined as a mirror angle β, (iii) an angle between a light beam incident on an eye of an observer and the visual axis is defined as a light beam angle η, the light beam being a light beam that forms an angle of view among the image light, (iv) an incidence angle of the image light when the reflectance of the image light becomes 0 with respect to each of the first mirror and the second mirror is defined as a limit incidence angle θth, and (v) a refractive index of the light guide is n, the angle β of each of the first mirror and the second mirror is set so as to satisfy Expressions (1), (2), and (3) described below:
• β1<β≤β2 (1)
• β1=½×[sin−1(1/n)+sin−1(η+α)/n)] (2)
• β2=1/3×[θth+sin−1(sin(η+α)/n))] (3)
• in the plan view, the light guide angle α at which the first surface is inclined with respect to the virtual plane is larger than 0 degrees.