Inductive proximity sensor and related methods

• US 7,969,141 B2
• Filed: 03/02/2010
• Issued: 06/28/2011
• Est. Priority Date: 07/20/2000
• Status: Expired due to Fees

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Hardie, David
• Primary Examiner(s): NGUYEN, LONG T
• Application Number:
  US12/716,030
• Publication Number:
  US 20100148799A1
• Time in Patent Office: 483 Days
• Field of Search: 327/517, 32420713-20715, 324/207.22, 324/207.26
• US Class Current: 324/207.15
• CPC Class Codes: H03K 17/9512 using digital techniques
• CPC Class Codes: H03K 17/9547 with variable amplitude
• CPC Class Codes: H03K 2217/94026 Automatic threshold calibration; e.g. threshold automatically adapts to ambient conditions or follows variation of input
• CPC Class Codes: Y10T 29/49105 Switch making

Abstract

An inductive proximity sensor or switch and a method of using same. The sensor or switch includes an Application Specific Integrated Circuit (“ASIC”) and a plurality of external components. The ASIC is implemented in CMOS technology and has an oscillator. A switch point of the sensor or switch is predetermined by selection of a bias voltage to a potential node of the oscillator.

Claims

1. An inductive proximity sensor, comprising:

a sensor head; and

a programmable circuit coupled to the sensor head, the programmable circuit having a programming mode and a normal operating mode, where the programmable circuit automatically enters the programming mode upon an initial power up of the programmable circuit where one or more of a functional setting and/or a sense distance setting is programmed, and once the programming mode is exited, the programmable circuit automatically sets a lock flag that prevents the programmable circuit from re-entering the programming mode upon a subsequent power up of the programmable circuit, and causes the programmable circuit to enter the normal mode upon the subsequent power up.

2. The inductive proximity sensor of claim 1, wherein the programming mode executes an automatic trimming routine that automatically trims one or more components to accommodate a desired sense distance.

3. The inductive proximity sensor of claim 2, wherein a metal target is spaced from the sensor head by the desired sense distance when the programmable circuit is in the programming mode.

4. The inductive proximity sensor of claim 3, wherein the automatic trimming routine uses a successive approximation routine to automatically trim the one or more components.

5. The inductive proximity sensor of claim 1, wherein the functional setting selects between a normally closed and normally open output.

6. The inductive proximity sensor of claim 1, wherein in the programming mode, the functional setting is selected based upon a magnitude of a voltage applied to a pin of the inductive proximity sensor.

7. The inductive proximity sensor of claim 6, wherein the voltage is applied to a code block that generates a functional code that is applied to a plurality of fuses so as to blow one or more of the fuses to program the functional setting of the programmable circuit.

8. The inductive proximity sensor of claim 1, wherein in the programming mode, the sense distance setting is programmed based on a distance a metal target is placed from the sensor head when the programmable circuit is in the programming mode.

9. The inductive proximity sensor of claim 1, wherein the programmable circuit includes an oscillator that produces an oscillator signal whose amplitude is quenched when a metal target is brought into proximity to the sensor head.

10. The inductive proximity sensor of claim 1, wherein the amplitude of the oscillator signal is voltage controlled.

11. A method for programming an inductive proximity sensor, comprising:

placing a target a target distance from a sensor head of a inductive proximity sensor;

powering up the inductive proximity sensor for a first time;

entering a programming mode;

once in the programming mode, execute an automatic trimming routine that automatically trims one or more components of the inductive proximity sensor to set a sense distance setting of the inductive proximity sensor to the target distance;

setting a lock bit that prevents the inductive proximity sensor from re-entering the programming mode upon a subsequent power up; and

exiting the programming mode.

12. The method of claim 11, wherein during subsequent power ups, the inductive proximity sensor enters a normal mode of operation rather than the programming mode.

13. The method of claim 11, wherein the automatic trimming routine uses a successive approximation routine to automatically trim the one or more components.

14. The method of claim 11, wherein once in the programming mode, setting a functional setting of the inductive proximity sensor.

15. The method of claim 14, wherein the functional setting is selected based upon a magnitude of a voltage applied to a pin of the inductive proximity sensor.

16. The method of claim 15, wherein the voltage may be applied to a code block that generates a functional code that is applied to a plurality of fuses so as to blow one or more of the fuses to program the functional setting of the inductive proximity sensor.

17. A method for programming an inductive proximity sensor, comprising:

powering up the inductive proximity sensor for a first time;

entering a programming mode;

applying a predetermined signal to a pin of the inductive proximity sensor;

once in the programming mode, programming a functional setting of the inductive proximity sensor based upon a characteristics of the predetermined signal that is applied to the pin of the inductive proximity sensor;

setting a lock bit that prevents the inductive proximity sensor from re-entering the programming mode upon a subsequent power up; and

exiting the programming mode.

18. The method of claim 17, further comprising:

placing a target a target distance from a sensor head of a inductive proximity sensor;

once in the programming mode, executing an automatic trimming routine that automatically trims one or more components of the inductive proximity sensor to set a sense distance setting of the inductive proximity sensor to the target distance.

19. The method of claim 17, wherein the predetermined signal may be applied to a code signal block that generates a code that is applied to a plurality of fuses so as to blow one or more of the fuses to program the functional setting of the inductive proximity sensor.

20. The method of claim 17, wherein during all subsequent power ups after the first time, the inductive proximity sensor enters a normal mode of operation rather than the programming mode.