Method and apparatus for the measurement and display of error values of precision machine tools, electronic instruments, etc.

Claim 3

The method of claim 1 wherein the value represented by the plurality of higher order digits of the digital value is converted to an analog value representing the desired value nearest to the measured value, and wherein the predetermined value is zero.

Claim 4

The method of claim 1 wherein the error values are positioning errors in a machine tool, the desired values are assumptive distances of movement of the machine tool, and the measured values are measured actual distancEs of movement of the machine tool.

Claim 5

The method of claim 1 wherein the desired value is an integral multiple of the interval between calibration points, and the interval between calibration points is greater than twice the largest error value.

Claim 6

The method of claim 4 wherein the predetermined value is zero and the difference between the measured value represented by the plurality of lower order digits of the digital value and zero is the measured value plus one-half the interval between calibration points, modulo the interval between calibration points, reduced by one-half the interval between calibration points.

Claim 7

The method of claim 1 including the additional step of plotting the analog value representing the desired value along one axis of a graph and plotting the analog value representing the difference between the measured value represented by the plurality of lower order digits of the digital value and a predetermined value representing the value of a corresponding plurality of lower order digits of the desired value along a second axis of the graph.

Claim 10

The method of claim 7 wherein the error values are positioning errors in a machine tool, the desired values are assumptive distances of movement of the machine tool, and the measured values are measured actual distances of movement of the machine tool.

Claim 11

The method of claim 7 wherein the error values are conversion errors in the digital output of an electronic instrument, the desired values are assumptive digital outputs of the instrument, and the measured values are measured actual digital outputs of the instrument.

Claim 12

The method of claim 7 wherein the desired value is an integral multiple of the interval between calibration points, and the interval between calibration points is greater than twice the largest error value.

Claim 13

The method of claim 10 wherein the difference between the measured value represented by the plurality of lower order digits of the digital value and zero is the measured value plus one-half the value of the interval between calibration points, modulo the value of the interval between calibration points, reduced by one-half the value of the interval between calibration points.

Claim 14

The method of claim 7 including the additional step of plotting the analog value representing the difference between the measured value represented by the plurality of lower order digits of the digital value and zero along an axis of a recorder.

Claim 17

The method of claim 13 wherein the error values are positioning errors in a machine tool, the desired values are assumptive distances of movement of the machine tool, and the actual values are actual measured distances of movement of the machine tool.

Claim 18

The method of claim 13 wherein the error values are conversion errors in the digital output of an electronic instrument, the desired values are assumptive digital outputs of the electronic instrument, and the actual values are actual digital outputs of the electronic instrument.

Claim 19

The method of claim 13 including the additional step of plotting the analog value representing the desired value at each calibration point along one axis of a graph and plotting the analog value representing the difference between the actual value represented by the plurality of lower order digits of the digital value produced for each calibration point and zero along a second axis of the graph.

Claim 20

The method of claim 13 including the additional step of plotting the analog value representing the difference between the actual value represented by the plurality of lower order digits of the digital value produced for each calibration point and zero along an axis of a recorder.

Claim 21

Apparatus for deriving an error value between a desired value and a measured value at each of a plurality of calibration points, said apparatus comprising means for measuring the actual value at each calibration point, means for producing a digital value representing the measured value, conversion means for converting the value represented by a plurality of higher order digits of the digital value to an analog value representing the desired value adjacent to the measured value, and conversion means for converting the value represented by a plurality of lower order digits of the digital value to an analog value representing the difference between the measured value represented by the plurality of lower order digits of the digital value and zero representing the value of a corresponding plurality of lower order digits of the desired value.

Claim 22

Apparatus for deriving an error value between a desired value and a measured value at each of a plurality of calibration points, said apparatus comprising means for measuring the actual value at each calibration point, means for producing a digital value representing the measured value, conversion means for converting the value represented by a plurality of higher order digits of the digital value to an analog value representing the desired value adjacent to the measured value, and conversion means for converting the value represented by a plurality of lower order digits of the digital value to an analog value representing the difference between the measured value represented by the plurality of lower order digits of the digital value and zero representing the value of a corresponding plurality of lower order digits of the desired value.

Claim 23

Apparatus as in claim 18 wherein the error values are positioning errors in a machine tool, the desired values are assumptive distances of movement of the machine tool, and the measured values are actual measured distances of movement of the machine tool.

Claim 24

Apparatus as in claim 18 wherein the error values are frequency output errors in a voltage controlled oscillator, the desired values are assumptive frequencies of operation of the oscillator, and the measured values are actual measured frequencies of operation of the oscillator.

Claim 25

Apparatus as in claim 18 wherein the desired value is an integral multiple of the interval between calibration points, and the interval between calibration points is greater than twice the largest error value.

Claim 26

Apparatus as in claim 21 wherein the difference between the measured value represented by the plurality of lower order digits of the digital value and zero is the measured value plus one-half the value between calibration points, modulo the value between calibration points, reduced by one-half the value between calibration points.

Claim 27

Apparatus as in claim 18 including means for plotting the analog value representing the desired value along one axis of a graph and the analog value representing the difference between the measured value represented by the plurality of lower order digits of the digital value and zero along a second axis of the graph.

Claim 28

Apparatus as in claim 18 including means for plotting the analog value representing the difference between the measured value represented by the plurality of lower order digits of the digital value and zero along an axis of A recorder.

Claim 29

Apparatus as in claim 18 wherein each of said conversion means comprises a digital-to-analog converter.

Claim 30

Apparatus for deriving an error value between a desired value and an actual value of an operating parameter of a device successively at each of a plurality of calibration points separated by a calibration interval at least twice the maximum error value, said apparatus comprising means for obtaining the actual value at each calibration point, means for producing a digital value representing the actual value at each calibration point, first computer means comprising a first digital-to-analog converter, means for transmitting a plurality of higher order digits of the digital value produced for each calibration point to the first computer means, said first computer means producing an analog output signal proportional to the desired value at each calibration point, second computer means comprising a second digital-to-analog converter, and means for transmitting a plurality of lower order digits of the digital value produced for each calibration point to the second computer means, said plurality of lower order digits representing a value smaller than half the value of the calibration interval, said second computer means producing an analog output signal proportional to the difference between the actual value represented by the plurality of lower order digits of the digital value produced for each calibration point and zero representing the value of a corresponding plurality of lower order digits of the desired value at each calibration point, said difference being the actual value plus half the calibration interval, modulo the calibration interval, reduced by half the calibration interval.

Claim 31

Apparatus for deriving an error value between a desired value and an actual value of an operating parameter of a device successively at each of a plurality of calibration points separated by a calibration interval at least twice the maximum error value, said apparatus comprising means for obtaining the actual value at each calibration point, means for producing a digital value representing the actual value at each calibration point, first computer means comprising a first digital-to-analog converter, means for transmitting a plurality of higher order digits of the digital value produced for each calibration point to the first computer means, said first computer means producing an analog output signal proportional to the desired value at each calibration point, second computer means comprising a second digital-to-analog converter, and means for transmitting a plurality of lower order digits of the digital value produced for each calibration point to the second computer means, said plurality of lower order digits representing a value smaller than half the value of the calibration interval, said second computer means producing an analog output signal proportional to the difference between the actual value represented by the plurality of lower order digits of the digital value produced for each calibration point and zero representing the value of a corresponding plurality of lower order digits of the desired value at each calibration point, said difference being the actual value plus half the calibration interval, modulo the calibration interval, reduced by half the calibration interval.

Claim 32

Apparatus as in claim 26 wherein the desired value at each calibration point is an integral multiple of the interval between calibration points, and the interval between calibration points is greater than twice the largest error value.

Claim 33

Apparatus as in claim 26 including plotting means coupled to both of said first and second computer means for plotting the analog output signals produced thereby.

Claim 34

Apparatus as in claim 26 wherein said second computer means further comprises means for digitally adding a fixed offset value to the first digit of said plurality of lower order digits, and means for thereafter subtracting said offset value from the analog output signal produced by said second computer means.

Claim 35

Apparatus as in claim 29 wherein said means for digitally adding a fixed offset value comprises a one digit adder to which said first digit of said plurality of lower order digits is transmitted, and means for transmitting said fixed offset value to said one digit adder.

Claim 36

Apparatus as in claim 26 including means for transmitting a calibration point signal between said apparatus and said device.

Claim 37

Apparatus for measuring a positioning error value between an assumptive position and an actual position of a machine tool successively at each of a plurality of calibration points separated by a calibration interval at least twice the maximum error value, said apparatus comprising a laser interferometer for measuring the actual value at each calibration point, means for producing a digital value representing the actual value at each calibration point, first computer means comprising a first digital-to-analog converter, means for transmitting a plurality of higher order digits of the digital value produced for each calibration point to the first computer means, said first computer means producing an analog output signal proportional to the desired value at each calibration point, second computer means comprising a second digital-to-analog converter, and means for transmitting a plurality of lower order digits of the digital value produced for each calibration point to the second computer means, said plurality of lower order digits representing a value smaller than half the value of the calibration interval, said second computer means producing an analog output signal proportional to the difference between the actual value represented by the plurality of lower order digits of the digital value produced for each calibration point and zero representing the value of a corresponding plurality of lower order digits of the desired value at each calibration point, said difference being the actual value plus half the calibration interval, modulo the calibration interval, reduced by half the calibration interval.

Claim 38

Apparatus for measuring a positioning error value between an assumptive position and an actual position of a machine tool successively at each of a plurality of calibration points separated by a calibration interval at least twice the maximum error value, said apparatus comprising a laser interferometer for measuring the actual value at each calibration point, means for producing a digital value representing the actual value at each calibration point, first computer means comprising a first digital-to-analog converter, means for transmitting a plurality of higher order digits of the digital value produced for each calibration point to the first computer means, said first computer means producing an analog output signal proportional to the desired value at each calibration point, second computer means comprising a second digital-to-analog converter, and means for transmitting a plurality of lower order digits of the digital value produced for each calibration point to the second computer means, said plurality of lower order digits representing a value smaller than half the value of the calibration interval, said second computer means producing an analog output signal proportional to the difference between the actual value represented by the plurality of lower order digits of the digital value produced for each calibration point and zero representing the value of a corresponding plurality of lower order digits of the desired value at each calibration point, said difference being the actual value plus half the calibration interval, modulo the calibration interval, reduced by half the calibration interval.

Claim 39

Apparatus as in claim 32 wherein the desired value at each calibration point is an integral multiple of the interval between calibration points, and the interval between calibration points is greater than twice the largest error value.