Method for high resolution measurement of a position

#1. Field of the Invention

#The present invention relates to devices to supply accurate time period information to position sensors which require the accurate measurement of a time period and the methods for accurately measuring such time periods at high resolution.

#More particularly, the present invention relates to sensors based on the principle of magnetostriction which require accurate measurement of time periods and novel methods using magnetostrictive position sensors to make high resolution time period measurements without increased power requirements.

#For a further understanding of the nature and objects of the present invention and the features and advantages thereof, reference is now made to the Detailed Description in conjunction with the attached Drawings, in which like parts are given like reference numerals and wherein:

#FIG. 1 is a block diagram of one preferred embodiment of a sensor of the present invention;

#FIG. 2 is a schematic diagram of one preferred embodiment of an advanced running period acquisition system;

#The instant invention has been implemented in an application-specific integrated circuit (sometime abbreviated ASIC, herein) which also includes several additional novel features. Resistance measurements can be made using the same counting technique, combined with a capacitor charge/discharge scheme. The interrogation pulse generator has a programmable length. Registers are included for a noise rejection window and cycle time, more fully described in U.S. Pat. Nos. 4,721,902 and 5,311,124, incorporated herein by reference. Every measurement includes a scaling value relative to a crystal controlled clock.

#FIG. 1 shows a typical structure of a sensor device generally 10 including a sensor advanced running period acquisition system (sometimes abbreviated as a SARA system herein) 12, a magnetostrictive sensing element 14, a microcontroller 16, an EEPROM 18, an interface 20, a power on reset 22, a CXO 24, an interrogation pulse 26 passing from the SARA system 12 to the magnetostrictive device 14, a comparator 30 passing from the magnetostrictive device 14 to the SARA system 12, a set of temperature sensing reference devices 32, and a plurality of temperature sensing devices such as a resistive thermal device (sometimes referred to as RTDs) 34.

#As shown in FIG. 2, the SARA system 12 includes a control unit 36 for controlling events and sequencing of devices communications. The SARA system 12 also includes a high and low cycle time, write only input registers 38a-b, a pulse length, write only input register 40, a high and low length, write only input registers 42a-b associated with a high noise rejection (HNR) window, scale factor, write only input registers 44 and control, write only input register 46.