Control of transducer to tape spacing
View Patent ↗A tape drive apparatus for reading and writing data on a magnetic tape includes at least one transducer that interacts with the magnetic tape. A temperature control element is positioned to thermally expand the transducer. A control system controls the amount of current supplied to the temperature control element. A sensing circuit senses the distance between the transducer and the data storage tape. The system generates a spacing signal indicative of the sensed distance and is stored as spacing data. A temperature control element is controlled based upon spacing data to adjust the spacing between the transducer and the tape. The temperature control element may be controlled based upon a fixed adjustment or empirical data. A method is disclosed for controlling spacing between the transducer and a magnetic storage tape by heating the transducer head to cause thermal expansion and reduce pole tip recession.
1. A system for dynamically controlling magnetic spacing between a transducer and a data storage tape comprising:
a data storage tape drive that has a tape head that includes the transducer;
a sensing circuit for measuring instantaneous magnetic clearance between the transducer and the data storage tape by determining the amplitude of a read back signal for a signal of known wavelength, wherein the sensing circuit measures instantaneous magnetic clearance by determining the equation:
V=V 0 e (−2πd/λ)
where V is the instantaneous amplitude, V 0 is the amplitude at d=0, e is the exponential function, d is the distance between the magnetic layer and the read transducer, and λ is the signal wavelength, and generating a spacing signal indicative of the measured clearance that is stored as spacing data; and
a temperature control element operatively connected to the tape head that is controlled based upon the spacing data to control the temperature of a portion of the tape head, wherein the temperature is controlled to adjust the distance between the transducer and the data storage tape.
2. The system of claim 1 wherein the temperature control element is a heating element.
3. The system of claim 1 wherein the sensing circuit utilizes the transducer in a read back mode.
4. The system of claim 1 wherein the sensing circuit includes a sensor.
5. The system of claim 1 wherein the temperature control element is used to control the temperature of the portion of the tape head selectively during read/write operation of the read/write transducer.
6. The system of claim 1 wherein the temperature control element is a resistance heater that is assembled as part of the read/write transducer, wherein the resistance heater is connected to a pre-amplifier that provides current to the resistance heater based upon the spacing data.
7. The system of claim 1 wherein the sensing circuit measures instantaneous magnetic clearance by determining the equation:
V=V 0 e (−2πd/λ)
where V is the instantaneous amplitude, V 0 is the amplitude at d=0, e is the exponential function, d is the distance between the magnetic layer and the read transducer, and λ is the signal wavelength.
8. A method of controlling the spacing between a transducer head and a magnetic storage tape comprising:
determining the instantaneous spacing between the transducer head and the magnetic storage tape wherein during the determining step, the instantaneous magnetic clearance is determined by the equation:
V=V 0 e (−2πd/λ)
where V is the instantaneous amplitude, V 0 is the amplitude at d=0, e is the exponential function, d is the distance between the magnetic layer and the read transducer, and λ is the signal wavelength, wherein the amplitude of a read back signal of known wave length is determined generating a control signal that is used to develop a spacing value that is indicative of the spacing between the transducer head and the magnetic storage tape;
providing current to a resistance heating element based upon the spacing value; and
heating the transducer head to selectively cause thermal expansion of the transducer head to reduce the spacing between the transducer head and the magnetic storage tape.
9. The method of claim 8 wherein the step of determining the instantaneous spacing is used to sense the extent of pole tip recession.