| 摘要 |
An automatic measuring apparatus is capable of measuring the thickness of a work piece with a high degree of precision by removing distance data for carriers from distance data representative of the distances between a pair of surface plates which are detected in a non-contact manner, without being affected by the property of the work piece. An eddy current sensor 5 mounted on a first surface plate 3 detects a distance therefrom to a second surface plate 2 and generates a corresponding analog voltage signal A to an A/D conversion circuit 70 where it is converted into a predetermined number of sampling digital voltage signals P. When the eddy current sensor 5 enters a space M between two adjacent carriers 100-1, 100-2, a first carrier sensor 6A generates a first voltage signal SA to a clock terminal CK of a D-FF circuit 71. Also, when the eddy current sensor 5 moves out of the space M, a second sensor B generates a second voltage signal SB to a reset terminal R of the D-FF circuit 71. As a result, the D-FF circuit 71 generates an output signal SQ to AND circuits 72 only when the eddy current sensor 5 is positioned at the space M, so that during the time, the digital voltage signal P is input to the arithmetic operation circuit 73. Subsequently, the thickness of each work piece 101 held by a corresponding carrier 100 is determined based on a voltage value of a digital voltage signal that has a maximum frequency or a maximum number of occurrences among the digital voltage signals P. <IMAGE> |
