Precision pressure generator

Claim 3

A system as described by claim 1, wherein the means for providing a pressure command signal including means for correcting the command signal for non-linearity includes: operator-operated keyboard means for providing a binary coded decimal pressure command signal and a binary coded decimal entry signal; an encoder for encoding the command signal; shift register means for shifting and registering the encoded command signal; latch register means for latching and registering the shifted and registered encoded command signal; correction means; the latch register means connected to the keyboard means and to the correction means and responsive to the entry signal for applying a portion of the shifted and registered and latched and registered encoded command signal to the correction means, whereupon said correction means provides a correction signal for correcting the command signal non-linearity; means for combining the correction signal and a portion of the shifted and registered and latched and registered encoded command signal to provide a binary coded decimal combined signal; and means for decoding the binary coded decimal combined signal to provide a corrected decimal digital output pressure command signal.

Claim 4

A system as described by claim 2, wherein the means for combining the correction signal and a portion of the shifted and registered and latched and registered encoded command signal to provide a binary code decimal digital output pressure command signal includes: means for adding the correction signal and the portion of the shifted and registered and latched and registered encoded command signal.

Claim 5

A system as described by claim 2, wherein the correction means includes: first means connected to the latch register and responsive to the portion of the shifted and registered and latched and registered encoded command signal therefrom that defines discrete equal segments over a predetermined pressure range for providing predetermined binary intercept correction outputs for each segment, which outputs sequentially truncate an "error from absolute" curve of the command signal; second means connected to the latch register and addressed by the portion of the shifted and registered and latched and registered encoded command signal therefrom that defines discrete equal segments over a predetermined pressure range for providing predetermind binary slope correction outputs for each intercept correction output, which further truncate the "error from absolute" curve of the command signal; third means connected to the latch register and responsive to that portion of the shifted and registered and latched and registered encoded command signal which defines discrete equal segments within each intercept correction segment for generating incremental address outputs; means for combining the correction outputs from the second means and the address outputs from the third means; and other means for combining the output from the first mentioned combining means and the correction outputs from the first means to provide the correction signal.

Claim 6

A system as described by claim 4 wherein the first mentioned combining means includes: multiplier means for multiplying the correction outputs from the second means and the address outputs from the third means to provide a further higher order truncation of the "error from absolute" curve of the command signal.

Claim 7

A system as described by claim 4, wherein the other combining means includes: adder means for adding the outputs from the first mentioned combining means and the correction outputs from the first means to provide the correction signal.

Claim 8

A system as described in claim 1, wherein: the pressure sensor signal is an analog signal; the corrected pressure command signal is a digital signal; and the means for combining the pressure sensor signal and the corrected command signal includes means for converting the corrected command signal to an analog signal and means for summing the analog pressure sensor signal and the analog corrected command signal for providing a summation signal.

Claim 9

A system as described by claim 7, including: an oscillator for providing an alternating reference signal at a predetermined frequency; the oscillator connected to the converting means and to the pressure sensor for applying the alternating reference signal thereto, whereupon the analog corrected command signal, the analog pressure sensor signal and the summation signal are alternating signals; and a demodulator connected to the oscillator and to the summing means, and triggered by the alternating reference signal to demodulate the alternating summation signal and to provide a constant level summation signal.

Claim 10

A system as described by claim 8, wherein: the means for providing a pressure input includes a vacuum source, a pressure source, a filter connected to the pressure source for filtering the pressure therefrom and a flow control valve connected to the filter for controlling the flow of filtered pressure; and the pressure control means coupled to the vacuum source and to the flow control valve and responsive to the vacuum from the vacuum source and the controlled flow of filtered pressure from the flow control valve for receiving the pressure input, and connected to the demodulator and responsive to the constant level summation signal for providing the pressure output.

Claim 11

A system as described by claim 9, wherein: the pressure control valve is coupled to the pressure sensor for feeding back the pressure output thereto so that the system is at null whereupon the precision pressure is generated.

Claim 12

A system as described by claim 1, including: a decoder connected to the shift register for decoding the shifted and registered encoded command signal; and display means connected to the decoder for displaying the pressure command.