Patent ID: 8319762

Claim:
A scanning image display apparatus comprising: a light source which emits a laser beam; and a scanning unit configured to two-dimensionally scan a scanning surface with the laser beam by two-dimensionally rotating a reflection surface which reflects the laser beam emitted by said light source; wherein, when seen from a side which is perpendicular to an incident plane including a laser beam incident on said scanning unit and a laser beam scanned on said scanning surface by said scanning unit, with said scanning unit held at a rotation center position of said reflection surface, said light source and said scanning unit are arranged to have a positional relationship where the laser beam emitted by said light source is incident on said reflection surface, the laser beam being incident on said reflection surface obliquely at an initial angle of incidence α 0 either clockwise or counterclockwise with respect to a first normal line of said reflection surface at an incident position of the laser beam, and said scanning unit and said scanning surface are arranged to have a positional relationship where the laser beam scanned by said scanning unit is incident on said scanning surface, the laser beam being incident on said scanning surface obliquely at an initial angle of incidence β 0 the other of clockwise or counterclockwise with respect to a second normal line of said scanning surface at an incident position of the laser beam; wherein said scanning unit is configured to two-dimensionally scan said scanning surface with the laser beam emitted by said light source by rotating a first rotation axis which is perpendicular to the incident plane by an angular amplitude ±θy and by rotating a second rotation axis which is perpendicular to both the first normal line and the first rotation axis by an angular amplitude ±θx, and a perpendicular scanning angle ω(α) which is an angle that the laser beam scanned by said scanning unit rotating the second rotation axis by +θx makes with the laser beam scanned by said scanning unit rotating the second rotation axis by −θx satisfies Equation 1 as a function of an actual angle of incidence α ((α 0 −θy)≦α≦(α 0 +θy)) on said scanning unit ω ⁡ ( α 0 - θ y ) ω ⁡ ( α 0 + θ y ) ≤ 1 + tan ⁢ ⁢ 2 ⁢ θ y ⁢ tan ⁢ ⁢ β 0 1 - tan ⁢ ⁢ 2 ⁢ θ y ⁢ tan ⁢ ⁢ β 0 ≤ 1.5 × ω ⁡ ( α 0 - θ y ) ω ⁡ ( α 0 + θ y ) . ( Equation ⁢ ⁢ 1 )