| 摘要 |
<p>An ultrasonic transducer unit for web edge detection includes multiple transducer elements (27, 28) attached to a single sound conducting plate (30). The transducer elements are preferably piezoelectric disks, and the sound conducting plate is preferably formed of hollow glass microspheres in an epoxy matrix. Multiple transducer elements may be positioned on the sound conducting plate in various geometric arrangements. Transducer units in accordance with the present invention may be mounted in a web edge detector head, such that pairs of transmitting and receiving transducer elements face each other across a detection gap through which a web of material is passed. Individual transducer elements within each transducer unit are activated to transmit/receive an ultrasonic beam in a selected pattern to provide both web edge sensing and ultrasonic signal compensation for varying ambient conditions in the detection gap. Each transducer unit may include a spacer (33) attached to the sound conducting plate and surrounding the transducer elements, and a sealing plate (37) attached to the spacer to enclose the transducer elements within the transducer unit. Transducer element control circuits may be mounted on a portion of the sealing plate which forms a circuit board that is electrically connected to the transducer element and to a main controller external to the detector head.</p> |
