Proximity switched machine control method and apparatus

• US 5,212,621 A
• Filed: 04/26/1990
• Issued: 05/18/1993
• Est. Priority Date: 04/26/1990
• Status: Expired due to Fees

• Current Assignee: Square D Company (Schneider Electric SE)
• Original Assignee: CNC Retrofits, Inc.
• Inventors: Panter, Ronald L.
• Primary Examiner(s): Pellinen, A. D.
• Assistant Examiner(s): Osborn, David
• Application Number:
  US07/514,770
• Time in Patent Office: 1,118 Days
• Field of Search: 307/38, 307/39, 307/308, 307/326, 307/328, 307/112, 307/116, 307/140, 307/141.4, 361/160, 361/170, 361/179, 361/181, 361/280, 200/600, 200/50 C, 200/61.85, 328/5, 328/7, 83/DIG. 1, 192/129 R, 192/129 A, 192/130, 192/131 R, 192/131 H, 192/132, 318/16
• US Class Current: 361/181
• CPC Class Codes: F16P 3/12 with means, e.g. feelers, which in case of the presence of a body part of a person in or near the danger zone influence the control or operation of the machine F16P3/08 takes precedence
• CPC Class Codes: F16P 3/20 for electric control systems
• CPC Class Codes: H03K 17/955 using a capacitive detector

Abstract

A control station for a machine is equipped with capacitive proximity sensors in two locations for sensing the presence of operator'"'"'s hands at the locations. The sensors are enclosed in a protective housing behind exterior target surfaces forming exterior wall surfaces of the enclosure and are supplied by a voltage source. A relay in series with each sensor and the voltage source is actuated when the operators hands are both sensed. Each sensor generates an electrical field extending outwardly a predetermined distance forwardly beyond each target surface for sensing an operators hands which are outside the enclosure within the field and need not be in tactile contact with the target surfaces. Only when both hands are sensed do the relays indicate operation of the machine.

Claims

1. A pressure-free operator station for a machine, having a control output for connection to said machine, and comprising:

a voltage supply circuit,

a protective enclosure having a pair of exposed, spaced apart exterior targets forming exterior portions of the enclosure,

a capacitive proximity sensor in the circuit inside the enclosure behind each target and generating an electrical field extending outwardly a predetermined distance forwardly beyond the respective exterior target in a local area for sensing an operator'"'"'s respective hand which can but need not touch the targets,

activatable elements coupled in circuit with the voltage supply and the sensors for operating the machine upon sensing an operator'"'"'s hands near the respective targets, and

means for connecting the activatable elements to said control output.

2. A pressure-free operator control station in combination with an industrial machine press to be activated comprising:

a voltage supply circuit,

a protective enclosure structure having substantially spaced exposed exterior target surfaces forming exterior portions of the enclosure,

a plurality of capacitive proximity sensors inside the enclosure structure behind said target surfaces, each sensor generating an electrical field extending outwardly a predetermined distance forwardly beyond the respective target surface on the enclosure in a local area for sensing an operator'"'"'s hand outside the enclosure structure and within the field, and each sensor having a normally open switch which is closed upon sensing said hand,

a control output for connection to said machine,

activatable elements coupled in circuit with the voltage supply means and the sensor switches for operating the press upon sensing an operator'"'"'s two hands near the respective targets, and

means for connecting the activatable elements to said control output.

3. A pressure-free operator control station having a control output for connection to a machine comprising:

a metal housing,

a plurality of relatively widely spaced sensing apertures in the housing, nonmetallic non-conductive covers secured to the housing over each aperture and having exposed exterior surfaces providing accessible exterior target surfaces forming exterior wall portions of the enclosure and shielding each aperture;

capacitive proximity sensors inside the housing and close to each aperture for sensing an operator'"'"'s hand at any target surface outside the housing, each sensor generating an electrical field extending outwardly a predetermined distance forwardly beyond the exterior target surface and including a normally open switch which is closed upon sensing said hand,

a relay operatively coupled to each sensor switch for operation of relay contacts upon sensing an operator'"'"'s hands near the respective target surfaces, the hands can but need not touch the covers, and

means for connecting the relay contacts to said control output.

4. In combination with an industrial machine requiring proper positioning of both hands of an operator for machine operation, an operator control station for machine control comprising:

a voltage supply circuit,

a steel housing having a top wall,

a pair of relatively widely spaced apertures in the top wall of the housing,

a non-conductive polymer panel presenting a nonconductive exterior target surface covering each aperture and forming an exterior wall portion of the housing top wall,

a pair of spaced apart capacitive proximity sensors inside the housing and connected to said voltage supply circuit, each sensor being adjacent an aperture and having a sensing field extending upwardly a distance beyond the exterior target surface of the panel for sensing an operator'"'"'s hand which need not touch the panel outside of the respective aperture,

a relay serially coupled to each sensor and the voltage supply means for switching relay outputs in response to sensing an operator'"'"'s hands adjacent the respective panels, and

terminal means connected to said relays and to the industrial machine for coupling the control station to the machine.

5. A method of activating an operator control station for a machine, the control station including a protective enclosure structure with substantially spaced apart exterior targets forming exterior wall portions of said enclosure and having a pair of activatable, signal producing, spaced apart capacitive proximity sensors within the enclosure structure behind the targets, each sensor having outwardly disposed radiating faces generating a local electrical field, and electrical circuitry including a voltage supply connecting the sensors to activate the machine when the sensors are activated, comprising the steps of:

a. electrically energizing the sensors and producing electrical fields extending a predetermined distance forwardly beyond the exterior targets;

b. moving each hand of an operator to a position spaced forwardly of the respective targets in which each hand enters one of said fields adjacent said sensor faces of the enclosure structure, without entering the enclosure structure; and

c. simultaneously transmitting the signal produced by each sensor, by reason of the palms of the hands merely entering said fields without touching anything, to activate the machine.