| 摘要 |
<p>In a debris detector for a particle counter (10), a particle (18), or transient debris passing through the sensing orifice (16) causes a voltage pulse occurs (fig. 3A). When debris lodges in or against the orifice (16) of the particle detector (10), a d.c. voltage shift occurs. The voltage at the orifice (16) is capacitively (34) coupled to an amplifier (36) and the output of the amplifier (36) is provided to an integrator (40). The integrated voltage (Fig. 3C) is applied to a comparator (42) to provide an output signal (Fig. 3D) whenever the integrated voltage (Fig. 3C) exceeds a reference voltage (Vref). The comparator (42) output signal (Fig. 3D) is provided to a delay circuit (44, 46) having a delay related to the time required for a particle (18) to pass through the orifice (16). If the comparator (42) signal (Fig. 3D) remains after the delay time, a debris alarm signal (Fig. 3E) is provided.</p> |
