Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2000-02-03
2001-06-19
Lateef, Marvin M. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
Reexamination Certificate
active
06248068
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to ultrasonic monitors and is primarily concerned with ultrasonic movement monitors such as a monitor or apparatus for monitoring breathing movement of a subject, which may be a human being or an animal. However, the invention also has utility in other fields where it is necessary to exclude certain movements and to detect other movements.
2. Description of the Prior Art
It has been heretofore proposed to monitor the breathing of an infant by monitoring ultrasonic waves reflected from the body of the infant, in order to detect the cessation of respiration. An alarm system is initiated when breathing has ceased, to call the parent or a nurse in a hospital so that immediate and urgent attention can be provided to the infant. One such system is U.S. Pat. No. 4,197,856 which issued on Apr. 15, 1980 to Robert B. Northrop entitled “Ultrasonic Respiration/Convulsion Monitoring Apparatus and Method for Its Use”. The system utilizes a continuous ultrasonic wave and a phase-locked-loop is provided whereby the frequency of the ultrasonic source is varied. The analog output signal of the phase-locked-loop represents the movement of the object or person in the time domain.
U.S. Pat. No. 4,738,266 dated Apr. 19, 1988 issued to John B. Thatcher and is entitled “Apnea Monitor”. The patent indicates that the exhaled breath of an infant is collected in a hood. A source of infrared energy emits infrared energy into the hood. So long as the infant is breathing, the carbon dioxide in its breath absorbs a portion of the infrared energy in the hood. Should the infant stop breathing, an infrared detector responds to the resulting increase in infrared energy to activate an alarm so as to enable the attendant personnel to take appropriate action.
U.S. Pat. No. 5,638,824 issued on Jun. 17, 1997 to Jonathon Brian Summers and is entitled “Ultrasonic Monitor”. The monitor operates by periodically emitting burst of ultrasonic pulses from an emitter and subsequently detecting the pulses by a receiver, for example, after reflection from an object such as a sleeping infant. Changes in conditions are determined by monitoring the changes in phase occurring between the input to the emitter and the output from the receiver
While some of the prior art devices referred to previously utilize the same principle of synchronous detection that is in monitoring changes in the reflected signal with respect to the emitted signal, the present invention is arranged as a lock-in amplifier and processes analog signals only. This results in a possibility of measuring not only changes in the phase shift between the two signals, as provided in U.S. Pat. No. 4,197,856, U.S. Pat. No. 5,638,824 and U.S. Pat. No. 5,915,322, but also changes in the amplitude of the reflected signal, which the other devices do not utilize. This makes the overall sensitivity of the present invention higher. The additional measurement does not require any additional hardware and is done simultaneously with the measurement of the phase shift by the multiplication of the two signals with just one analog multiplier integrated circuit.
SUMMARY OF THE INVENTION
It is a feature of the present invention to utilize a second measuring channel, which increases the apparatus' sensitivity and makes it nearly independent of such random external factors as the distance between the apparatus and the infant or object and their mutual orientations.
Still another feature of the present invention is to provide a novel apparatus to reliably and accurately monitor movement and lack of movement, including respiratory movement of a subject and to sound an alarm when conditions warrant.
A further feature of the present invention to provide a non-contact monitoring apparatus for monitoring movements of infants or other subjects, which does not require physical contact with the subject or person.
A still further feature of the present invention is to provide a novel non-contact monitoring device or apparatus providing a motion monitor which will respond to lack of movement in the subject or person by sounding an alarm or buzzer.
Another feature of the present invention to provide a novel apparatus and method for monitoring the degree of respiratory effort and optionally other movements of the infant or subject by reflecting ultrasonic waves from the body of the infant or subject to be monitored.
In accordance with the present invention, there is provided an apparatus for the non-contact monitoring of a person having an ultrasonic means or generator for generating an electrical reference signal and an ultrasonic transmitter coupled to the generator to receive and to convert the electrical reference signal into an ultrasonic emitted wave and to direct the emitted wave towards the body of the person to be monitored, the emitted wave striking the body and being reflected therefrom to form a reflected ultrasonic wave. An ultrasonic receiver is located in a position to receive the reflected ultrasonic wave and to convert the reflected ultrasonic wave into an electric signal of the same frequency as the reflected wave. A preliminary amplifier is coupled to the ultrasonic receiver to receive and to amplify the electric signal supplied by the ultrasonic receiver and to form an amplified electric signal of increased amplitude. A first electrical circuit forming a first channel is coupled to the generator for receiving the electrical reference signal and is also coupled to the preliminary amplifier for receiving and processing the amplified electric signal from the preliminary amplifier. The first circuit introduces a phase shift of 45° to the amplified electric signal from the preliminary amplifier to provide a first shifted amplified signal. The first circuit includes means for multiplying the first shifted amplified signal by the electrical reference signal supplied by the generator. A second electrical circuit is also provided for forming a second channel coupled to the generator for receiving the electrical reference signal and is also coupled to the preliminary amplifier for receiving and processing the amplified signal from the preliminary amplifier. The second electrical circuit introduces a phase shift of negative 45° to the amplified signal from the preliminary amplifier to provide a second shifted amplified signal, with the total phase shift between the first and second shifted amplified signals being equal to 90° and their amplitude being the same. The second circuit includes means for multiplying the second shifted amplified signal by the electrical reference signal supplied to the generator. The apparatus further includes an alarm circuit and a summer circuit or adder which is connected to the first and second electrical circuits and to the alarm circuit. The adder includes means for adding the direct current voltages produced by the first and second electrical circuits and amplifying the result. When the amplified signal from the adder is below a preset voltage, the alarm circuit is activated thereby indicating that the movement of the person has terminated. When the amplified signal from the adder is greater than the preset voltage maintaining the alarm circuit inactive thereby indicating that the movement of the person has not terminated.
In accordance with one aspect of the invention, the apparatus utilizes a standard quartz-crystal-locked generator whose frequency is always constant.
In accordance with another aspect of the present invention, the apparatus contains an analog lock-in amplifier (or synchronous detector) consisting of an analog multiplier and integrator that generates an electric signal proportional to changes at both phase and amplitude of the reflected wave.
In accordance with still another aspect of the present invention, the monitoring apparatus utilizes a second measuring channel, which increases the device sensitivity and makes it nearly independent of such random external factors as the distance between the apparatus and the infant or person and their mutual orientation.
Dykema Gossett PLLC
Lateef Marvin M.
Patel Maulin
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