Illumination device for visual inspection and visual inspection apparatus

A visual inspection apparatus comprising:

• a base including a base body on which an inspection object is placed and a column erected from the base body;
• an imaging apparatus supported by the column with an optical axis of an imaging optical system thereof directed downward;
• a transmissive reflector plate that is supported by the column and formed of a light transmitting material, has an opening in a center through which the imaging apparatus is inserted from above, assumes a dome shape, a radius of which 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 fine unevenness for diffusing and reflecting light from below is formed and an upper surface located on an opposite side of the lower surface;
• first, second, and third light source units that irradiate light on an inspection object, the first, second, and third light source units being provided on the upper surface of the transmissive reflector plate and arranged in a place below the opening and passing the center axis;
• and
• a fourth light unit source unit that irradiates light on the inspection object, the fourth light source unit being provided below the transmissive reflector plate, wherein
• the first light source unit includes plural light sources arranged in an first annular area on the upper surface with the center axis set as a center, lights emitted from the plural light sources being transmitted through the transmissive reflector plate and crossing an imaginary plane, which is orthogonal to the center axis and passes through the inspection object, at a first angle to illuminate the inspection object,
• the second light source unit includes plural 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, lights emitted from the plural light sources being transmitted through the transmissive reflector plate and crossing the imaginary plane at a second angle smaller than the first angle to illuminate the inspection object,
• the third light source unit includes plural 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, lights emitted from the plural light sources being transmitted through the transmissive reflector plate and crossing 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 plural light sources arranged along a lower part of an outer circumference of the transmissive reflector plate, lights emitted from the plural light sources being diffused and reflected by the lower surface of the transmissive reflector plate to illuminate the inspection object.