Telemetering intracranial pressure transducer
First Claim
1. A telemetering intracranial pressure transducer comprising:
- an airtight housing adapted to engage the skull of a body to be tested;
a pressure-electric transducer having a pressure-sensing portion, disposed in said housing for detecting an intracranial pressure below a dura under the skill wherein said pressure-electric transducer comprises two strain-sensitive elements in a full bridge circuit;
a pressure-receiving layer disposed in said housing and located at a frontal end of said housing in contact with said pressure-sensing portion of said pressure-electric transducer, said pressure-receiving layer being in pressed engagement with said dura; and
a transmitting circuit disposed in said housing for transmitting an output signal from said pressure-electric transducer through a transmitting antenna wherein said transmitting circuit comprises a telemetering transmission circuit connected to said pressure-electric transducer for transmitting an output therefrom and microbatteries for supplying electric power to said pressure-electric transducer and said telemetering transmission circuit with said transmission circuit further comprising a switching means connected to said microbatteries for switching on and off said microbatteries and wherein said telemetering transmission circuit includes a subcarrier oscillator circuit connected to said pressure-electric transducer for modulating an output signal therefrom into a predetermined signal and wherein said telemetering transmission circuit further includes a main carrier oscillator circuit connected to said subcarrier oscillator circuit for transmitting an output signal therefrom with said subcarrier oscillator circuit comprising an astable multivibrator for frequency-modulating a carrier frequency including a full bridge circuit for delivering an electrical signal corresponding to a pressure variation, a differential amplifier connected to said full bridge circuit for amplifying said electrical signal therefrom, a comparator having a first input terminal, a second input terminal connected to said differential amplifier and an output terminal connected to said full bridge circuit, an integrating circuit connected to said first input of said comparator, and a filter circuit connected to said output terminal of said comparator for cutting off a d.c. component in an signal fed thereto and supplying a subcarrier signal to said main carrier oscillator circuit.
1 Assignment
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Accused Products
Abstract
A telemetering intracranial pressure transducer comprises an airtight casing member housing a pressure-electric transducer for detecting an intracranial pressure, a pressure-receiving layer disposed in contact with the pressure-electric transducer and in pressed engagement with the dura under the skull, and a transmitting circuit for transmitting an output signal indicative of the intracranial pressure through a transmitting antenna. The transmitting circuit includes a telemetering transmission circuit, a microbattery and a switch for switching on and off the microbattery. The transducer thus constructed is entirely embedded below the head, dispensing with external wires or a receiving coil on the head, and detects an intracranial pressure safely and accurately without confining or disturbing the activities of a testee.
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Citations
11 Claims
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1. A telemetering intracranial pressure transducer comprising:
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an airtight housing adapted to engage the skull of a body to be tested; a pressure-electric transducer having a pressure-sensing portion, disposed in said housing for detecting an intracranial pressure below a dura under the skill wherein said pressure-electric transducer comprises two strain-sensitive elements in a full bridge circuit; a pressure-receiving layer disposed in said housing and located at a frontal end of said housing in contact with said pressure-sensing portion of said pressure-electric transducer, said pressure-receiving layer being in pressed engagement with said dura; and a transmitting circuit disposed in said housing for transmitting an output signal from said pressure-electric transducer through a transmitting antenna wherein said transmitting circuit comprises a telemetering transmission circuit connected to said pressure-electric transducer for transmitting an output therefrom and microbatteries for supplying electric power to said pressure-electric transducer and said telemetering transmission circuit with said transmission circuit further comprising a switching means connected to said microbatteries for switching on and off said microbatteries and wherein said telemetering transmission circuit includes a subcarrier oscillator circuit connected to said pressure-electric transducer for modulating an output signal therefrom into a predetermined signal and wherein said telemetering transmission circuit further includes a main carrier oscillator circuit connected to said subcarrier oscillator circuit for transmitting an output signal therefrom with said subcarrier oscillator circuit comprising an astable multivibrator for frequency-modulating a carrier frequency including a full bridge circuit for delivering an electrical signal corresponding to a pressure variation, a differential amplifier connected to said full bridge circuit for amplifying said electrical signal therefrom, a comparator having a first input terminal, a second input terminal connected to said differential amplifier and an output terminal connected to said full bridge circuit, an integrating circuit connected to said first input of said comparator, and a filter circuit connected to said output terminal of said comparator for cutting off a d.c. component in an signal fed thereto and supplying a subcarrier signal to said main carrier oscillator circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A telemetering intracranial pressure transducer comprising;
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an airtight housing adapted to engage the skull of a body to be tested; a pressure-electric transducer having a pressure-sensing portion, disposed in said housing for detecting an intracranial pressure below a dura under the skull; a pressure-receiving layer disposed in said housing and located at a frontal end of said housing in contact with said pressure-sensing portion of said pressure-electric transducer, said pressure-receiving layer being in pressed engagement with said dura; a transmitting circuit disposed in said housing for transmitting an output signal from said pressure-electric transducer through a transmitting antenna wherein said transmitting circuit comprises a telemetering transmission circuit connected to said pressure-electric transducer, for transmitting an output therefrom, and microbatteries for supplying electric power to said pressure-electric transducer and said telemetering transmission circuit ansd wherein said transmitting circuit further comprises switching means connected to said microbatteries for switching on and off said microbatteries; and a receiving circuit remotely provided therefrom for receiving an output signal transmitted through said transmitting antenna of said transmitting circuit, wherein said receiving circuit comprises a receiving antenna for receiving a transmitted signal, a detecting circuit connected to said receiving antenna for converting the high-frequency signal composed of the main carrier signal into an intermediate-frequency signal and demodulating the subcarrier signal through FM detection, a subcarrier discriminator circuit connected to said detecting circuit for picking up a signal corresponding to a pressure variation from the subcarrier signal in the input signal, a correction circuit comprising a differential amplifier having first and second input terminals and an output terminal, said first input terminal being connected to said subcarrier discriminator circuit, a barometer connected to said second input terminal of said correction circuit, for correcting the signal therefrom, and an indicator connected to said output terminal of said correction circuit, for indicating the corrected signal from said correction circuit.
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Specification