Proximity sensor having a non-ferrous metal shield for enhanced sensing range
First Claim
1. A proximity sensor comprising:
- a) a magnetic member having a top surface, a bottom surface, and a side surface having a width between the top and the bottom surfaces of the magnetic member,said top surface being generally planar and wherein the magnetic member defines a cavity that extends into the magnetic member from the top surface;
b) a sensing coil positioned within the cavity of the magnetic member;
c) circuitry, coupled to the sensing coil, for energizing the sensing coil to define a sensing region in relation to the sensing coil and for sensing an object in the sensing region;
d) a sensor housing supporting the circuitry and the magnetic member with the sensing coil; and
e) a non-ferrous metal shield positioned inside the sensor housing and disposed around at least a portion of an outer perimeter of the magnetic member such that at least a portion of the side surface of the magnetic member is between the sensing coil and the non-ferrous metal shield,the non-ferrous metal shield having a top substantially aligned with the generally planar top surface of the magnetic member and having a width less than the width of the side surface of the magnetic member.
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Accused Products
Abstract
A proximity sensor includes a transducer and a circuit having a switch that changes state in response to a presence of an object in spaced relation to the transducer. The transducer includes a magnetic form defining a generally planar surface facing a sensing zone of the sensor. The magnetic form includes a side surface that extends away from the sensing zone and an internal cavity that opens outwardly toward the sensing zone. A sensing coil is positioned within the magnetic form cavity. The transducer additionally includes a sensor housing supporting the sensing coil and the magnetic form in relation to the sensing zone. A non-ferrous metal shield is positioned inside the sensor housing to surround at least a portion of the magnetic form and enhance a sensing range of the proximity sensor. The shield has an edge that faces the sensing zone located substantially co-incident with the generally planar surface of the magnetic form.
95 Citations
25 Claims
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1. A proximity sensor comprising:
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a) a magnetic member having a top surface, a bottom surface, and a side surface having a width between the top and the bottom surfaces of the magnetic member, said top surface being generally planar and wherein the magnetic member defines a cavity that extends into the magnetic member from the top surface; b) a sensing coil positioned within the cavity of the magnetic member; c) circuitry, coupled to the sensing coil, for energizing the sensing coil to define a sensing region in relation to the sensing coil and for sensing an object in the sensing region; d) a sensor housing supporting the circuitry and the magnetic member with the sensing coil; and e) a non-ferrous metal shield positioned inside the sensor housing and disposed around at least a portion of an outer perimeter of the magnetic member such that at least a portion of the side surface of the magnetic member is between the sensing coil and the non-ferrous metal shield, the non-ferrous metal shield having a top substantially aligned with the generally planar top surface of the magnetic member and having a width less than the width of the side surface of the magnetic member. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A proximity sensor defining a sensing region for detecting the presence of a target object entering the sensing region, the proximity sensor comprising:
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a) a housing having an end wall and side walls extending from said end wall defining a housing interior cavity; b) a magnetically permeable pot core having a generally planar upper surface, an annular groove that extends into a body of the pot core from said upper surface, a bottom surface, and a side surface having a width between the upper surface and the bottom surface of the pot core, the pot core disposed in said housing interior cavity such that the upper surface is adjacent the housing end wall and the sensing region extends outwardly in front of the upper surface of the pot core; c) a non-ferrous metal strip disposed around at least a portion of an outer periphery of the pot core side surface such that at least a portion of the side surface of the pot core is between the annular groove and the non-ferrous metal strip, the strip having a top substantially aligned with the upper surface of the pot core and having a width less than the width of the pot core side surface; and d) sensor circuitry for detecting a target object in the sensing region, the sensor circuitry comprising; i) a sensing coil disposed in said annular groove of said pot core, ii) oscillation circuitry electrically coupled to said sensing coil for energizing the sensing coil to define the sensing region in relation to the sensing coil, the oscillation circuitry having an oscillator signal based on whether a target object enters the sensing region, and iii) a comparator coupled to said oscillation circuitry for comparing the oscillator signal to a reference signal, the comparator producing an output signal based on the comparison of the oscillator signal and the reference signal. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A proximity sensor for sensing an object in a sensing region, the proximity sensor comprising:
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a) a pot core formed of a magnetically permeable material, the pot core having a generally planar top surface, a bottom, a side surface having a width between the top and the bottom surface of the pot core, and an outer perimeter bounding the side surface of the pot core, the pot core defining a groove which extends into the pot core from the top surface of the pot core; b) a sensing coil positioned in the groove of the pot core; c) oscillator circuitry coupled to the sensing coil for energizing the sensing coil to define the sensing region in relation to the sensing coil, the oscillator circuitry sensing an object in the sensing region based on an output signal of the sensing coil; d) a non-ferrous metal strip having a top substantially aligned with the generally planar top surface of the pot core and disposed around at least a portion of the outer perimeter of the pot core such that at least a portion of the side surface of the pot core is positioned between the sensing coil and the non-ferrous metal strip, the non-ferrous metal strip having a width less than the width of the side surface of the pot core; and e) an insulator positioned between the non-ferrous metal strip and the outer perimeter of the pot core. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25)
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Specification