Process timing apparatus
AssigneeTRW Inc.
InventorRobert L. Hyde
Life of this patent
Estimating the term…
Abstract
An indicating electronic timer useful for timing processing events and for controlling a process measures the elapsed time from a moment at which a process variable attains a predetermined value and produces a signal which varies in accordance with the elapsed time. During a timing operation, the signal is displayed on a display device which normally displays the process variable, and may be such that the display device indicates the percentage of a predetermined time interval which has elapsed. The timer may be conveniently implemented with relatively inexpensive integrated circuits, such as a variable oscillator, binary counters, and D/A converters.
Claims24
In a system for controlling a process, timing apparatus comprising a display device normally operative to display a value representative of a process variable;
- control means responsive to the process variable attaining a predetermined value for producing a control signal to change the process from a first state to a second state;
- timing means responsive to the process variable attaining said predetermined value for measuring, during a predetermined period of time, the elapsed time from the time at which the process variable attains said predetermined value and for producing a timing signal having an instantaneous value representative of the elapsed time;
- and means for displaying on the display device, during said predetermined period of time and in place of the value representative of the process variable, a value dependent upon the relationship between the value of the timing signal and the predetermined period of time.
Timing apparatus comprising an oscillator for generating a predetermined frequency;
- control means responsive to the occurrence of a predetermined event for enabling the operation of the oscillator for a predetermined period of time;
- counter means connected to the oscillator for counting said frequency, the counter means having an instantaneous count value that is representative of the elapsed time from the occurrence of the predetermined event;
- means responsive to the count value for producing a voltage having a voltage value that is dependent upon the relationship between the elapsed time and the predetermined period of time;
- and means for displaying the voltage value as a percentage of said predetermined period of time.
Dependencies are inferred from the claim text.