Transducer employing wireless transmissions for sending and receiving signals

• US 7,283,922 B2
• Filed: 12/03/2004
• Issued: 10/16/2007
• Est. Priority Date: 01/12/2004
• Status: Expired due to Fees

• Current Assignee: Kulite Semiconductor Products Inc
• Original Assignee: Kulite Semiconductor Products Inc
• Inventors: Kurtz, Anthony D., Landmann, Wolf S.
• Primary Examiner(s): Bui; Bryan
• Assistant Examiner(s): Bhat; Aditya S.
• Application Number:
  US11/003,238
• Publication Number:
  US 20050150286A1
• Time in Patent Office: 1,047 Days
• Field of Search: 702/138, 702/130, 702/133, 702/41, 702/33, 340/825.71, 340/825.72, 340/825.73
• US Class Current: 702/138
• CPC Class Codes: B60C 23/0413 Wireless charging of active radio frequency circuits
• CPC Class Codes: B60C 23/0433 Radio signals

Abstract

A transducer is implemented to operate with transmitted frequency signals. These transmitted signals provide a bias potential to the transducer and enable the transducer to transmit a transducer output signal to a remote location. The transducer has an antenna for receiving transmitted signals. The antenna is coupled to a rectifier circuit; the rectifier circuit is operative to provide a DC voltage in response to said received transmitted signals. This DC voltage is applied to the piezoresistive array via a switching arrangement coupled between the array and the rectifier circuit. An interface circuit controls the switching arrangement to enable DC bias to be applied to the array in a first mode and to remove the bias in a second mode.

Claims

1. A transducer adapted to respond to transmitted signals of a given frequency for providing a bias potential to said transducer and for enabling said transducer to transmit a transducer output signal to a remote location, comprising:

a radio antenna for receiving transmitted radio signals;

a rectifier circuit coupled to said antenna and operative to provide a DC operating voltage in response to said received radio signals;

a piezoresistive array operative to provide an output signal indicative of an applied pressure when said array is biased;

a switch coupled to said rectifier circuit and said array and operative in a first mode to apply said DC operating bias to said array, and operative in a second mode to remove said operating bias; and

an interface circuit coupled to said switch and said array and operating said switch in said first mode during the presence of received radio signals to cause said array to provide said output signal and apply said output signal to said antenna for transmission of said output signal to said remote locations, said interface circuit operative to operate said switch in said second mode when said transmitted radio signals are not received;

wherein, said interface circuit is further coupled to said rectifier circuit to receive an operating bias from said rectifier circuit.

2. The transducer according to claim 1 wherein said interface circuit monitors said rectifier output to operate said first switch in said first mode when said DC voltage exceeds a given value.

3. A transducer adapted to respond to transmitted signals of a given frequency for providing a bias potential to said transducer and for enabling said transducer to transmit a transducer output signal to a remote location, comprising:

a radio antenna for receiving transmitted radio signals;

a rectifier circuit coupled to said antenna and operative to provide a DC operating voltage in response to said received radio signals;

a piezoresistive array operative to provide an output signal indicative of an applied pressure when said array is biased;

a switch coupled to said rectifier circuit and said array and operative in a first mode to apply said DC operating bias to said array, and operative in a second mode to remove said operating bias;

an interface circuit coupled to said switch and said array and operating said switch in said first mode during the presence of received radio signals to cause said array to provide said output signal and apply said output signal to said antenna for transmission of said output signal to said remote locations, said interface circuit operative to operate said switch in said second mode when said transmitted radio signals are not received; and

a memory for storing conservation coefficients for said piezoresistive array.

4. The transducer according to claim 3 wherein said memory is an EEPROM.

5. A transducer adapted to respond to transmitted signals and transmit a transducer output signal to a remote location, comprising:

an antenna for receiving transmitted signals;

a rectifier circuit coupled to said antenna and operative to provide a DC operating voltage in response to said received transmitted signals;

a Wheatstone bridge piezoresistive array comprising a span resistor and operative to provide an output signal indicative of an applied pressure when said array is biased;

a switch coupled to said rectifier circuit and said array and operative in a first mode to apply said DC operating bias to said array, and operative in a second mode to remove said operating bias; and

,

an interface circuit coupled to said switch and said array and operating said switch in said first mode during the presence of received transmitted signals to cause said array to provide said output signal and apply said output signal to said antenna for transmission of said output signal to said remote locations, said interface circuit operative to operate said switch in said second mode when said transmitted signals are not received;

wherein, said span resistor is coupled to said interface circuit to enable said interface circuit to convert a voltage across said span resistor into a radio frequency signal indicative of temperature.

6. A transducer adapted to respond to transmitted signals and transmit a transducer output signal to a remote location, comprising:

a tuned circuit antenna comprising an inductor in parallel with a first and second capacitors in series with a common terminal between said capacitors for receiving transmitted signals;

a rectifier circuit coupled to said antenna and operative to provide a DC operating voltage in response to said received transmitted signals;

a piezoresistive array operative to provide an output signal indicative of an applied pressure when said array is biased;

a first switch coupled to said rectifier circuit and said array and operative in a first mode to apply said DC operating bias to said array, and operative in a second mode to remove said operating bias;

an interface circuit coupled to said switch and said array and operating said switch in said first mode during the presence of received transmitted signals to cause said array to provide said output signal and apply said output signal to said antenna for transmission of said output signal to said remote locations, said interface circuit operative to operate said switch in said second mode when said transmitted signals are not received; and

,

a second switch having a first terminal coupled to said common terminal of said antenna and another terminal coupled to a source of reference potential, wherein in a first mode said second capacitor is shorted by said second switch to cause said antenna to be tuned to a first frequency, and in a second mode said second switch is opened causing said first and second capacitors to tune said antenna to a second different frequency;

said second switch being coupled to said interface circuit for controlling said second switch in said first or second modes.

7. The transducer according to claim 6 wherein said interface circuit operates said second switch to transmit transducer information to said remote location.