Air core gauge fixed voltage signal and variable pulse width modulation signal interchanged control system therefor
AssigneeChrysler Corporation
InventorsPaul A. Markow, Kevin R. Hammond, Donald E. Hutchings
Life of this patent
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Abstract
A pulse-width modulation system provides means for controlling dual-coil, air-core gauges over 360 degrees. The system moves a dial needle from one octant of the gauge to the next in response to coded data representing measurands by holding one coil at 100% duty cycle while applying a PWM of a varying duty signal to the other coil. When the magnitude of the measurand dictates that the needle should move into another octant of the dial, the PWM signal and the 100% duty cycle signal are interchanged between the coils in a manner permitting the needle to move to other octant of the dial.
Claims8
A drive apparatus for an air core gauge responsive to a coded data indicative of magnitudes and polarities of varying measurands, the drive apparatus comprising:
- a) a fixed frequency PWM count clock with an input terminal for receiving a fixed clock oscillator signal and producing at one output terminal a chosen number of pulse signals at a chosen frequency related to the oscillator signal and, at another output terminal, producing a period signal each time after counting a chosen number of pulses of the pulse signal;
- b) a ROM-BASE current controller, with a ROM containing a corresponding number of memory locations as the total chosen number of pulses counted by the PWM count clock, having one input terminal for:
- (1) receiving the coded data related to the varying measurand to be displayed, the coded data being in a form which can address a ROM location containing a digital word;
- the digital word containing a number of which a portion represents the magnitude of the measurand and another portion which represents bipolar information of the measurand;
- the controller having a second input terminal for:
- (2) receiving the pulse signals and a third input terminal for:
- (3) receiving the period signal and, after having a location addressed by the coded data, producing at a first output port a PWM signal for a duration proportional to the magnitude of the measurand and, at another output port, bipolar control signals indicative of a polarity of the PWM signal that route to one of a first or a second stator coils of the gauge and the polarity of a fixed voltage signal applied to another of the dual stator coils of the gauge not receiving the PWM signal;
- and
- c) a bridge driver having logic circuits for receiving the PWM signal and the control signals, and producing at a first output port the PWM signal of a chosen polarity dictated by the logic circuits that route to the first or the second of the stator coils of the gauge, and producing at a second output port a fixed voltage signal of a chosen polarity that applies to the opposite of the first or second stator coils that receive the PWM signals, also dictated by the logic circuits, the PWM signals and the fixed voltage signal, developing current signals, having a vectorial relationship which causes a rotor with a dial needle connected thereto to rotate to dial positions indicative of the magnitude and direction of the measurand.
Dependencies are inferred from the claim text.