Capacitively coupled machine tool safety system having a digital quantizer

• US 4,470,046 A
• Filed: 02/02/1982
• Issued: 09/04/1984
• Est. Priority Date: 02/02/1982
• Status: Expired due to Term

• Current Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Betsill, Harry E.
• Primary Examiner(s): YUSKO, DONALD
• Application Number:
  US06/345,192
• Time in Patent Office: 945 Days
• Field of Search: 340/825.72, 340/562, 340/680, 340/825.23, 361/179, 361/181, 328/5, 328/151, 307/115, 307/116, 307/326, 307/328
• US Class Current: 341/155
• CPC Class Codes: F16P 3/147 using electro-magnetic technology, e.g. tags or radar
• CPC Class Codes: F16P 3/148 using capacitive technology
• CPC Class Codes: G08B 13/26 by proximity of an intruder causing variation in capacitance or inductance of a circuit

Abstract

A machine tool safety system having a signal induced in a capacitive receptor antenna by the action of an electric field capacitively coupled thereto includes a receiver having an array of linear amplifiers with fast response times, a network connected to the output of each amplifier and responsive to a first command to sample the amplifier output signal, an analog-to-digital converter associated with the sampling network to quantize the signal from the first amplifier in the array that is not saturated, and a network responsive to a second command to dump the sampled signal value prior to the occurrence of the next sample time.

Claims

1. A machine tool safety system comprising

an electric field generator for generating an electric field having a predetermined recurrence rate;

a capacitive receptor antenna cooperable with the electric field generator to form a capacitive coupled transmission arrangement operative to induce in the capacitive antenna a signal having a corresponding recurrence rate;

a receiver for detecting the induced signal, the receiver comprising;

a network responsive to a first command for asynchronously sampling the induced signal a predetermined number of sample times during each period of the induced signal;

an analog-to-digital converter connected to the sampling network for quantizing the magnitude of the sampled signal at each sample time; and

a network responsive to a second command to remove the sampled signal value from the sampling network prior to the occurrence of the next sample time.

2. A machine tool safety system comprising

an electric field generator for generating an electric field having a predetermined recurrence rate;

a capacitive receptor antenna cooperable with the electric field generator to form a capacitive coupled transmission arrangement operative to induce in the capacitive antenna a signal having a corresponding recurrence rate;

a receiver for detecting the induced signal, the receiver comprising

a plurality of serally connected amplifier stages each of which includes a linear limiting amplifier with fast recovery;

a sampling network connected to the output of each amplifier stage for asynchronously sampling, in response to a first command, the signal at the output of each amplifier stage;

an analog-to-digital converter connected to each sampling network for quantizing the signal level of the first of the amplifier stages not saturated; and

,

a network associated with each amplifier stage and responsive to a second command to remove the sampled signal value from its associated amplifier stage prior to the occurrence of the next sample time.