Patent ID: 7891825

Claim:
A projection type image display apparatus, comprising: a lamp; an integrator for uniforming light emitted from the lamp; an illuminating optical system formed by a plurality of optical elements for focusing light outputted from the integrator; an image display element for modulating the focused light; a projection lens for projecting an optical image formed by the image display element; a first reflector disposed in a direction opposite to the integrator as viewed from the lamp; and a second reflector disposed between the lamp and the integrator; wherein, when a light emission center of the lamp is an origin, an optical axis direction in which the integrator is present from the origin is a z-axis, an arbitrary axis passing through the origin and running perpendicularly to the z-axis is a y-axis, an axis passing through the origin and running perpendicularly to a y-z plane is an x-axis, a polar angle from the z-axis to an arbitrary point of the outermost outline of the second reflector is θ, an azimuth angle from the x-axis to an arbitrary point of the outermost outline of the second reflector from the x-axis an x-y plane is φ, and a maximum value and a minimum value of the polar angle θ are θ max and θ min , respectively, the following relationship is satisfied: θ max ÷θ min ≧1.02; and wherein a peripheral edge shape of the second reflector is determined based on the following formulas: M (φ)=( f 2 −f 1 −D )×tan β (1) Z 1 2 ÷{( f 2 +f 1 )÷2} 2 +P 1 2 ÷(√( f 2 +f 1 )) 2 =1 (2) P 1 ={( f 2 −f 1 )÷2 −Z 1 }×tan θ (3) sin β=√( P 1 2 +{( f 2 −f 1 )÷2 −Z 1 } 2 =sin θ÷√( P 1 2 +{( f 2 −f 1 )÷2 +Z 1 } 2 ) (4) where: f 1 represents at focal length of the second reflector relative to the first reflector; f 2 represents a focal length of the second reflector relative to the optical axis; D represents a distance from a light emission center of the lamp to the collimator lens; P 1 represents a distance from the optical axis to a designated point at which the light ray passing through an outermost periphery of the second reflector intersects the first reflector; Z 1 represents a distance from an ellipse origin of the first reflector relative to the designated point; β represents an angle between the light ray reflected at the designated point and the optical axis; M(φ) represents an effective diameter of the integrator; and θ represents a polar angle proportional to the effective diameter M(φ) of the integrator.