Interpolation utilization apparatus

In a measuring instrument for determining the relative position of a first object with respect to a second object, the improvement comprising:

• means for generating a first digital signal representative of the position of the first object with respect to the second object;
• means for generating a digital interpolation signal representative of the position of the first object with respect to the second object, said interpolation signal having a spatial resolution greater than that of the first digital signal;
• means for displaying a composite signal having a spatial resolution greater than that of said first digital signal and representative of the position of the first object with respect to the second object;
• computer means, responsive to the first digital signal and to the interpolation signal and coupled to the display means, for combining the first digital signal with the interpolation signal to generate the composite digital signal and for supplying the composite signal to the display means;
• and
• means, included in the computer means, for correcting the composite signal by one unit of the first digital signal during the period between the transition of the interpolation signal through its maximum value and the transition of the first digital signal from one value to the next.

In a measuring instrument for determining the relative position of a first object with respect to a second object, said instrument including means for generating at least one analog measuring signal indicative of the relative position of the first object with respect to the second object, the improvement comprising:

• means, responsive to the at least one analog measuring signal, for generating a first digital signal representative of the position of the first object with respect to the second object;
• means, responsive to the at least one analog measuring signal, for generating a digital interpolation signal representative of the position of the first object with respect to the second object, said interpolation signal having a spatial resolution greater than that of the first digital signal;
• means for displaying a composite signal having a spatial resolution greater than that of said first digital signal and representative of the position of the first object with respect to the second object;
• computer means, responsive to the first digital signal and the interpolation signal and coupled to the display means, for combining the first digital signal with the interpolation signal to generate the composite signal and for supplying the composite signal to the display means;
• and
• means, included in the computer means, for correcting the composite signal by one unit of the first digital signal during the period between the transition of the interpolation signal through its maximum value and the transition of the first digital signal from one value to the next.

In a measuring instrument for determining the relative position of a first object with respect to a second object, said instrument including a scale mounted to the first object, a scanning unit mounted to the second object to scan the scale and to generate first and second phase shifted periodic analog signals which vary in amplitude as a function of the relative position between the first and second objects, the improvement comprising:

• trigger means for generating first and second square wave signals in response to the first and second analog signals, respectively;
• counter means, responsive to the first and second square wave signals for maintaining a coarse position count;
• interpolation means, responsive to at least one of the first and second analog signals for generating a digital coded interpolation value indicative of position, said coded interpolation value having a spatial resolution greater than that of said coarse position count;
• a computer, responsive to the coarse position count and the coded interpolation value;
• means, included in the computer, for combining the coarse position count with the coded interpolation value to produce a composite signal having a spatial resolution greater than that of the coarse position count;
• and
• means, included in the computer, for correcting the composite signal by one unit of the coarse position count during the period between the transition of the coded interpolation value through its maximum value and the transition of the coarse position count from one value to the next.

In a measuring instrument for determining the relative position of a first object with respect to a second object, said instrument including a scale mounted to the first object, a scanning unit mounted to the second object to scan the scale and to generate first and second phase shifted periodic analog signals which vary in amplitude as a function of the relative position between the first and second objects, the improvement comprising:

• trigger means for generating first and second square wave signals in response to the first and second analog signals, respectively;
• counter means, responsive to the first and second square wave signals for maintaining a coarse position count;
• interpolation means for generating a digital coded interpolation value indicative of position, said coded interpolation value having a spatial resolution greater than that of said coarse position count;
• a computer, responsive to the coarse position count and the coded interpolation value, said computer programmed to combine the coarse position count with the coded interpolation value to produce a composite signal having a spatial resolution greater than that of the coarse position count;
• and
• means, included in the computer, for incrementing the composite signal by one unit of the coarse position count only when the interpolation value is within a first predetermined range of values and one of the first and second square wave signals is in a first predetermined logic state, in order to correct the composite signal by one unit of the coarse position count during the period between the transition of the interpolation value through its maximum value and the transition of the coarse position count from one value to the next.