초록 ▼

An air core gage having a pair of coils in quadrature to drive a pointer has the first coil energized by a relatively constant reference current while the second coil is energized by a current which varies as a tangent function of the input quantity in order to drive the pointer through an octant of

An air core gage having a pair of coils in quadrature to drive a pointer has the first coil energized by a relatively constant reference current while the second coil is energized by a current which varies as a tangent function of the input quantity in order to drive the pointer through an octant of the gage. The current polarity to the second coil is reversed and the current is again varied in the same manner to vary the pointer through a second octant. Then, the reference current is applied to the second coil and the current is varied in the first coil according to the tangent function to drive the pointer through a third octant, and so on for a wide angle pointer drive. When the input quantity is a frequency, the driving circuit is conveniently a digital circuit including a ROM which stores the tangent function of the input quantity and a steering logic circuit which selectively applies the steady state and the variable signals to the gage coils to effect the appropriate pointer movement.

대표청구항 ▼

Apparatus for driving a gage to indicate a value proportional to the magnitude of an input quantity wherein the gage has first and second coils in quadrature to establish a resultant magnetic field and a pointer angularly positioned by the resultant field, comprising a circuit responsive to the inpu

Apparatus for driving a gage to indicate a value proportional to the magnitude of an input quantity wherein the gage has first and second coils in quadrature to establish a resultant magnetic field and a pointer angularly positioned by the resultant field, comprising a circuit responsive to the input quantity to generate a binary number proportional to the magnitude of the quantity, the binary number comprising a set of most significant bits changing in value stepwise as the said magnitude increases and a set of least significant bits changing in a repetitive pattern as the said magnitude increases, a memory addressed by the set of least significant bits for storing a table of numbers representing the tangent of an angle represented by the set of least significant bits to provide a binary output, a circuit responsive to the binary output for producing a varying signal proportional to the tangent of the angle represented by the set of least significant bits, and a steering logic and drive circuit controlled by the varying signal and by the set of most significant bits for producing a variable drive current proportional to the varying signal and a reference drive current equal to the maximum value of the variable drive current, and for selectively applying the two drive currents to the two coils respectively and for controlling the polarity thereof to establish a resultant magnetic field in a direction to position the pointer according to the magnitude of the input quantity.