Inspecting device for inspecting printed state of cream solder

An inspecting device for inspecting a position, area, thickness, or amount of cream solder printed on a printed circuit board, said inspecting device comprising:

• an illumination unit projecting a plurality of phase-shifting light patterns onto said printed circuit board, said phase-shifting light patterns being incident on said printed circuit board at an acute angle, said illumination unit producing said phase-shifting light patterns using a liquid crystal optical shutter having a liquid crystal element as a substantial grating;
• an image pick-up device picking up images of a portion of said printed circuit board where said phase-shifting light patterns are incident, and generating a plurality of image signals based thereon;
• and
• a processor receiving said plurality of image signals from said image pick-up device, and obtaining the position, area, thickness, or amount of cream solder printed on said circuit board from said plurality of image signals.

A method of inspecting a position, area, thickness, or amount of cream solder printed on a printed circuit board, said method comprising the steps of:

• a) projecting a plurality of phase-shifting light patterns onto said printed circuit board using a liquid crystal optical shutter having a liquid crystal element as a substantial grating, said phase-shifting light patterns being incident on said printed circuit board at an acute angle;
• b) picking up images of a portion of said printed circuit board where said phase-shifting light patterns are incident, and generating image signals based thereon;
• and
• c) obtaining the position, area, thickness, or amount of cream solder printed on said circuit board from said plurality of image signals.