Circuit responsive to rate change in amplitude of analog electrical signal for use in tire processing apparatus

An electronic circuit for detecting an analog electrical signal having a rate of change in amplitude equal to or greater than a predetermined rate, comprising:

• means for connecting an analog electrical signal from an external source to an input of a first switch;
• circuit means, having a time constant, connected to an output of said first switch for inverting said analog electrical signal when said first switch is in a first state and for storing an amplitude of said analog electrical signal when said first switch is in a second state;
• a comparator having a first input connected to said means for connecting and to an output of said circuit means;
• threshold means connected to said comparator for establishing a threshold for said comparator;
• said time constant being effective to produce a difference signal at said first input of said comparator whenever the rate of change in amplitude of said analog electrical signal is not less than a predetermined rate;
• said difference signal causing said comparator to produce an indication signal whenever said difference signal bears a predetermined relation to said threshold;
• and
• switch control means, including:
• (a) a detector/and
• (b) a second switch, said detector having an input connected to said comparator and an output connected to a control terminal of said second switch, said second switch having an output connected to a control terminal of said first switch;
• said switch control means in the absence of said indication signal being operative to place said first switch in said first state and in the presence of said indication signal being operative to place said first switch in said second state;
• said first switch being reset to said first state when said analog electrical signal recovers to said threshold.

A method for detecting an analog electrical signal having a rate of change in amplitude equal to or greater than a predetermined rate, including the steps of:

• inputing an analog electrical signal to a circuit means having a time constant;
• inverting the analog electrical signal, when the circuit means are in a first mode, to produce an inverted electrical signal;
• inputing the inverted electrical signal to a first terminal of a comparator;
• inputing the analog electrical signal to the first terminal of the comparator;
• producing in the comparator an indication signal that the rate of change in amplitude of the analog electrical signal is not less than a predetermined rate;
• switching the circuit means to a second mode in response to the indication signal;
• and
• storing the amplitude of the analog electrical signal at the time the indication signal is produced when the circuit means is switched to the second mode.

A method for generating an input to the grinder positioning apparatus of a tire grinding machine for grinding lug-type tires, including the steps of:

• transducing the circumferential surface configuration for a lug-type tire to produce an analog electrical signal;
• outputing the analog electrical signal to a circuit means having a time constant;
• inverting the analog electrical signal, when the circuit means is in a first mode, to produce an inverted electrical signal;
• outputing the inverted electrical signal to a first terminal of a comparator;
• outputing the analog electrical signal to the first terminal of the comparator;
• producing in the comparator an indication signal whenever the rate of change in amplitude of the analog electrical signal is not less than a predetermined rate;
• switching the circuit means to a second mode in response to the indication signal;
• storing the amplitude of the analog electrical signal at the time the indication signal is produced when the circuit means is switched to the second mode;
• and
• using the output of the circuit means in the first and second modes as the input to the grinder positioning apparatus.

In combination with apparatus for grinding lug-type tires, an electronic circuit, comprising:

• circuit means responsive to the circumferential surface configuration of a lug-type tire for distinguishing lugs from grooves on said tire;
• said circuit means having an output, said output changing in response to radial variations in said tire due to differences in the radial dimension of said lugs, said output not changing in response to radial variations in said tire due to grooves present between said lugs;
• said output for controlling a tire grinding machine so that said tire grinding machine is positioned in response to radial variations in said tire due to differences in the radial dimension of said lugs but not in response to radial variations in said tire due to grooves present between said lugs;
• whereby non-uniformities in said tire can be corrected.

A system for grinding lug-type tires, comprising:

• tire grinding apparatus, including:
• (a) at least one grinder and
• (b) means for positioning said at least one grinder;
• a transducer for generating an analog electrical signal representative of the circumferential surface configuration of a lug-type tire;
• and
• circuit means responsive to said analog electrical signal for distinguishing lugs from grooves on said tire;
• said circuit means having an output, said output changing in response to radial variations in said tire due to differences in the radial dimension of said lugs, said output not changing in response to radial variations in said tire due to grooves present between said lugs;
• said means for positioning being responsive to said output to position said at least one grinder so that said grinder is positioned in response to radial variations in said tire due to differences in the radial dimension of said lugs but not in response to radial variations in said tire due to grooves present between said lugs;
• whereby non-uniformities in said tire can be corrected.

A method for grinding lug-type tires, including the steps of:

• distinguishing lugs on a lug-type tire from grooves on the tire;
• deriving an analog electrical signal in which the grooves are masked, the analog electrical signal changing in response to radial variations in the tire due to differences in the radial dimension of the lugs, the analog electrical signal not changing in response to radial variations in the tire due to grooves present between the lugs;
• and
• controlling a tire grinding machine with the analog electrical signal so that the tire grinding machine is positioned in response to radial variations in the tire due to differences in the radial dimension of the lugs but not in response to radial variations in the tire due to grooves present between the lugs;
• thereby correcting non-uniformities in the tire.