| 摘要 |
PURPOSE: To position more than one pattern on the surface of an object in response to the difference of light quantity at high speed by providing an integrator, a normalization unit and a sample-and-hold circuit and positioning the pattern through the use of an adaptive threshold. CONSTITUTION: Only the analog output of a video camera 20, which corresponds to the selection part of the surface of the object 22, is supplied to an operational amplifier 48 with the control of a switch 37. An amplifier 48 and a capacitor 52 constitute the integrator 114 and the output of the amplifier 48 shows whole light quantity reflected from a selected area in a window, which is controlled by the switch 37 at the time of image-picking up by the camera 20, after the object 22 is scanned. An analog multiplier 56 constituting the normalization unit 17 inputs the integration signal and normalizes it. The normalized signal is an updated value and it is compared with the analog output of the camera 20. A threshold signal is adjusted by a potentiometer 82 in accordance with the result and it is stored in the sample-and-hold circuit 90. Thus, an adaptive threshold circuit 110 can supply the updated threshold to a comparator 40 after scanning and it can correspond to the difference of the light quantity of the other object at high speed. |
