Transducer assembly vibration sensor

• US 4,093,885 A
• Filed: 04/16/1976
• Issued: 06/06/1978
• Est. Priority Date: 03/19/1976
• Status: Expired due to Term

• Current Assignee: Ampex Corporation (Delta Information Systems, Inc.)
• Original Assignee: Ampex Corporation (Delta Information Systems, Inc.)
• Inventors: Brown, David Edward
• Primary Examiner(s): Budd, Mark O.
• Application Number:
  US05/677,683
• Time in Patent Office: 781 Days
• Field of Search: 310/8, 310/8.1, 310/8.2, 310/8.3, 310/8.5, 310/8.6, 310/9.8, 310/316, 310/317, 310/331, 310/332, 360/113, 360/125, 360/126, 346/112, 179/100.41 P
• US Class Current: 310/331
• CPC Class Codes: B06B 1/0603 using a piezoelectric bender, e.g. bimorph
• CPC Class Codes: G11B 5/588 by controlling the position of the rotating heads by controlling the speed of the record carrier G11B15/467; by controlling speed of the heads G11B15/473; by moving the transducing part of the head relative to the headwheel, in the direction of the scanning movement G11B15/1841
• CPC Class Codes: H10N 30/1071 with electrical and mechanical input and output, e.g. having combined actuator and sensor parts
• CPC Class Codes: H10N 30/2042 Cantilevers, i.e. having one fixed end

Abstract

A sensor for sensing vibrations in a transducer assembly and for generating an electrical signal indicative of the vibrations is disclosed. The sensor includes a piezoelectric generator which is mounted with a bimorph on a common substrate. The piezoelectric generator and bimorph have a common cantilevered end portion and an opposed deflectable free end portion so that deflection of the free end portion of the bimorph causes a corresponding deflection of the free end portion of the piezoelectric generator, whereby the piezoelectric generator generates an electrical indication of the instantaneous degree of deflection of the bimorph.

Claims

1. A deflectable read transducer assembly for use in a magnetic recorder, comprising:

a deflectable support arm comprising a pair of piezo-ceramic elements bonded to a common electrically conductive substrate between said pair of elements, one of said elements having a first conductive layer on the surface opposite said substrate, the other element having a second conductive layer opposite said substrate, said support arm being cantilevered at one end portion of its lengthwise dimension and being free to deflect at its opposed end portion;

a read transducer mounted to one of said pairs of elements on the opposed free end portion of said support arm, said transducer being electrically isolated from said conductive layers so that voltage applied to said substrate and said first and second layers does not produce a signal that is read by said transducer; and

,

a support arm deflection sensor comprising a piezo-ceramic generator element bonded to said common substrate and a third conductive layer overlying said generator element, said third conductive layer being generally in the same plane as said first layer and separated therefrom by a dielectric gap, said third conductive layer being electrically isolated from said first and second conductive layers, whereby deflection of said support arm results in an electrical output signal between said substrate and said third conductive layer, which output signal is indicative of the instantaneous amount of deflection of said support arm.

2. A transducer assembly as set forth in claim 1 wherein one of said piezo-ceramic elements and said generator element comprise a unitary piezo-ceramic element.

3. A read transducer assembly for use in a magnetic recorder, comprising:

a support arm capable of large scale deflection comprising a pair of elongated thin planar piezo-ceramic elements bonded to a common electrically conductive substrate located therebetween, said support arm being cantilevered at one end portion of its lengthwise dimension, the remainder, including the opposite end portion being free for large scale deflection in a direction generally transverse to the plane of said elements, the surfaces of each of said pair of elements opposite said common substrate having an electrically conductive layer bonded thereto, one of said conductive layers having a dielectric gap therein defining a relatively narrow conductive strip extending generally along said lengthwise direction which is electrically isolated from the main portion of said conductive layer, the main portion of said one conductive layer together with the other conductive layer, said substrate and the elements therebetween defining a piezo-ceramic motor for deflecting said arm in response to voltage being selectively applied thereto, the portion of said element adjacent said conductive strip defining a generator for generating an output signal in said conductive strip that is indicative of the instantaneous deflection of said support arm;

a read transducer for reproducing signal information from a magnetic recording media, said transducer being attached to one of said conductive layers at said opposite end of said support arm, the transducer extending beyond the end of said support arm and being electrically isolated from said conductive layer so that the signals being read thereby have no effect on the deflection of said arm and the output signal from said generator.

4. A read assembly as defined in claim 3 wherein said conductive strip is located along one side of said one conductive layer.

5. A transducer assembly as set forth in claim 3 wherein said dielectric gap extends from the cantilevered end portion of said arm to the opposed free end portion thereof.