Patent ID: 8192050
Filing Date: 2012-06-05
Classification: G01N,Y10S

Abstract:
1. An illumination device for visual inspection comprising: a transmissive reflector plate that is formed of a light transmitting material, has an opening in a center, assumes a dome shape having a radius that is gradually expanded downward with a center axis of the opening set as a center, and has a lower surface formed of a reflecting surface on which is formed fine unevenness for diffusing and reflecting light from below and an upper surface located on an opposite side of the lower surface; first, second, and third light source units to irradiate light on an inspection object, the first, second, and third light source units being provided on an upper surface side of the transmissive reflector plate and arranged in a place below the opening and passing the center axis; and a fourth light source unit to irradiate light on the inspection object, the fourth light source unit being provided below the transmissive reflector plate, wherein the first light source unit includes first multiple light sources arranged in a first annular area on the upper surface with the center axis set as a center, wherein light emitted from the first multiple light sources is transmitted through the transmissive reflector plate and crosses an imaginary plane, the imaginary plane being is orthogonal to the center axis and passing through the inspection object, at a first angle to illuminate the inspection object, the second light source unit includes second multiple light sources arranged in a second annular area on the upper surface having a radius larger than that of the first annular area with the center axis set as a center, wherein light emitted from the second multiple light sources is transmitted through the transmissive reflector plate and crosses the imaginary plane at a second angle smaller than the first angle to illuminate the inspection object, the third light source unit includes third multiple light sources arranged in a third annular area on the upper surface located between the first annular area and the second annular area with the center axis set as a center, wherein light emitted from the third multiple light sources is transmitted through the transmissive reflector plate and crosses the imaginary plane at a third angle between the first angle and the second angle to illuminate the inspection object, and the fourth light source unit includes fourth multiple light sources arranged along a lower part of an outer circumference of the transmissive reflector plate, wherein light emitted from the plural light sources is diffused and reflected by the lower surface of the transmissive reflector plate to illuminate the inspection object.