Patent ID: 7263876

Claim:
A method of detecting a convexity present on a surface of a member, the method comprising: abrading a surface of the member with a plate; detecting the convexity by measuring at least one of a group including (1) vibration generated on the plate and (2) a change of pressure applied to the member; detecting at least one of the vibration and the change of pressure with a sensor provided on the plate; converting at least one of the vibration and the change of pressure into a digital signal; subjecting the digital signal to a multiple resolution analysis to determine a value; and comparing the value with a threshold; wherein the abrading step includes: first abrading the surface of the member by maintaining a direct engagement between the plate and the member while relatively moving the plate in a first direction, to measure at least one of a first vibration and a first change of pressure, thereafter secondly abrading the surface of the member while relatively moving the plate in a second direction opposite the first direction, to measure at least one of a second vibration and a second change of pressure; the plate configured such that the direct engagement results in the removal of dust in both the first and second directions; and repeating the first abrading and the second abrading steps to obtain plural signals from the sensor; wherein the detecting step includes analyzing the plural signals.