Proximity sensor with simultaneously active intermixed sensor types

• US 3,967,261 A
• Filed: 10/10/1974
• Issued: 06/29/1976
• Est. Priority Date: 10/10/1974
• Status: Expired due to Term

• Current Assignee: Solly L. Fudaley
• Original Assignee: Solly L. Fudaley
• Inventors: Fudaley, Solly L.
• Primary Examiner(s): Swann, III, Glen R.
• Application Number:
  US05/513,521
• Time in Patent Office: 628 Days
• Field of Search: 340/258 C, 340/258 D, 340/285, 340/279, 340/267 R, 340/420
• US Class Current: 173/2
• CPC Class Codes: F16P 3/144 using light grids
• 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: G01V 3/08 operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices with electromagnetic waves G01V3/12
• CPC Class Codes: H03K 17/941 using an optical detector H03K17/968 takes precedence
• CPC Class Codes: H03K 17/955 using a capacitive detector

Abstract

The invention provides an improvement over my earlier U.S. Pat. No. 3,573,783 whereby different types of sensors may be indiscriminately intermingled, intermixed or otherwise used together simultaneously, in the same proximity sensing systems. An antenna sensor may be used when line of sight detection is not appropriate. A photosensor may be used when line of sight detection may be used. Both types of sensors may be used simultaneously, or each may be used separately. The invention is broad enough to enable simultaneous use of almost any other types of sensors. This intermixture is achieved by use of a balanced bridge-like circuit which may be unbalanced either by an intrusion, movement, or exit or any person or object in the field of an antenna or by a snap-action-like sensor, such as a photocell, for example.

Claims

1. A proximity sensor comprising an intermixed plurality of different types of simultaneously operating sensing devices including at least an RF antenna and connected in parallel with at least one off/on switching sensors means for simultaneously mixing the outputs from each of the various types of said parallel connected sensing devices, and detector means including a common circuit operated responsive to the output of said mixing means for giving an alarm signal responsive to a change in an output signal from any one of said sensing devices.

2. The sensor of claim 1 wherein there are a plurality of said switching sensors, each of said sensors being a photocell, said plurality being any one of many different numbers of said photocells, an electrical isolation circuit unit means, means for connecting each of said photocells into the input of said electrical isolation circuit unit, bridge means, and means for connecting said isolation circuit unit to said bridge in a parallel connection with said antenna, whereby different numbers of photocells may be lit or dark without adversely affecting sensor operation.

3. The proximity sensor of claim 2 wherein one type of said sensing devices comprises said RF antenna which is capacitively coupled to its environment, another type of said sensing devices comprises said photocells, and said mixing means comprises said a bridge which is balanced when said antenna is capacitively coupled into a quiescent environment and light is falling on said photocells, and which is unbalanced responsive to any changes in the environment which alter said capacitive coupling or responsive to the on/off switching of any one of the photocells when it is darkened.

4. A proximity sensor comprising an intermixed plurality of different types of simultaneously operating sensing devices including at least an RF antenna and a plurality of off/on switching photocell sensors, said RF antenna being capacitively coupled to its environment, electrical isolation circuit means, means for connecting each of said photocells into the input of said electrical isolation circuit means, means for connecting said isolation circuit means to a bridge in parallel with said antenna, said photocells being parts of a plurality of parallel circuits, said isolation unit comprising an electronic switch connected in series with said parallel circuits, high impedance means for connecting the electronic switch to, but electrically isolating it from, said antenna, means for simultaneously mixing the outputs from each of the various types of said sensing devices, said mixing means comprising said bridge which is balanced when said antenna is capacitively coupled into a quiescent environment and said photocells are lit and which is unbalanced responsive to any changes in the environment which alter said capacitive coupling or responsive to the on/off action of any one of the photocells when it is darkened, and detector means including a common circuit operated responsive to the output of said mixing means for giving an alarm signal responsive to a change in an output signal from any one of said sensing devices.

5. The sensor of claim 4 and feedback means connected across the input and output of said electronic switch to hold it on for a period of time which is long enough to insure an output response by said detector means.

6. The sensor of claim 5 and machine tool means, and means responsive to said alarm signal for shutting down said machine tool means.

7. A proximity sensor comprising an antenna capacitively coupled into its environment, at least on other sensing device comprising any one of many different numbers of photocells connected in parallel with the antenna, isolation circuit means, means for connecting said photocells between one potential and the input of said isolation circuit unit, said one potential being an off bias clamp for said isolation circuit, means responsive to an operation of at least one of said other sensing devices for substituting an on bias for said off bias clamp, means for connecting said isolation circuit unit in parallel with said antenna, a common circuit responsive to both said antenna and said photocells, said common circuit comprising means for simultaneously mixing the outputs from the photocell and the antenna, detector means for simultaneously monitoring said photocells and said antenna and for operating responsive to the output of said mixing means, means for giving an alarm signal responsive to the output of either said antenna or said sensing device applied through said mixing means, machine tool means, and means responsive to said alarm signal for shutting down said machine tool means.

8. The proximity sensor of claim 7 wherein said photocells are positioned to receive light beams extending across the working access area of said machine tool and said antenna is strung around the perimeter of said machine tool which is outside of said working access area.

9. The proximity sensor of claim 7 wherein said antenna is strung along a path followed by work pieces as they pass through said machine tool and said photocells are positioned to guard against the intrusion of a worker into danger areas of said machine tool.

10. The proximity sensor of claim 7 wherein said photocells guard worker gate areas to said machine tool and said antenna guards other danger areas of said machine tool.