Thermal measuring and testing – Temperature measurement – In spaced noncontact relationship to specimen
Reexamination Certificate
1998-12-30
2001-03-06
Bennett, G. Bradley (Department: 2859)
Thermal measuring and testing
Temperature measurement
In spaced noncontact relationship to specimen
C374S120000, C374S130000, C374S124000, C374S161000, C374S208000
Reexamination Certificate
active
06196714
ABSTRACT:
SCOPE OF INVENTION
The invention consists of an infrared clinical thermometer which, during measurement of the body temperature of the patient, is put at a preset distance from the patient.
PRIOR ART
Traditional mercury thermometers are well known and still widely used for both medicine and veterinary purposes, even though they require excessively long times (4-5 minutes) to yield a response, and they are not always easy to read or very precise.
Fast-reading mercury thermometers have been developed, Which, however, have not been very successful on the market because they are costly and brittle. Digital thermometers, albeit representing an undoubted technical advance on clinical mercury thermometers, are not without certain drawbacks and limitations deriving basically from their response time, not less than 30-60 seconds, which is (or may be) too long when it is necessary to obtain the body temperature of particularly restless new-born, babies, or else of animals.
Infrared clinical thermometers have recently come on the market, which comprise basically a sensor that detects in a very short time (2-3 seconds) the intensity of the infrared radiation emitted by a preset point of the body of the patient and a logic that processes the signal emitted by the sensor to determine the body temperature of the patient and to show it on a display, normally of a digital type, forming part of the thermometer itself.
As temperature measuring point, the ear drum membrane is normally used, which is located immediately near the hypothalamus (i.e., the gland which regulates body temperature) and which is normally reached by inserting a probe connected to the sensor into the auditory canal. This probe forms a single piece with the sensor and may protected by a cap which is preferably interchangeable.
These infrared thermometers present, however, certain drawbacks. In the first place, measuring the temperature at the ear drum cannot certainly be considered “non-invasive”, since the probe anyway causes a certain discomfort to the patient. In addition, for obvious hygienic reasons it is necessary (or at least very advisable) to apply an interchangeable protective cap to the probe, or else clean the probe after each measuring. These are all things that are uncomfortable and inconvenient, especially in hospitals.
Finally, the precision of the thermometer reading may be impaired by a set of factors that are not always exactly foreseeable or assessable, such as, for example, an imperfect positioning of the end of the probe and/or the presence of wax in the auditory canal, etc. On the other hand, the infrared sensors currently available an the market are of such a size that they cannot be introduced into the auditory canal of the patient, and hence it is essential to use a probe (containing a wave-guide having suitable characteristics) which “conveys” to the sensor the infrared radiation emitted by the ear drum membrane, at the same time preventing the sensor from being affected by the infrared radiation emitted by the surrounding areas, for example, the auricular region.
Remote infrared measuring devices are already known.
WO-A-92/02792 shows a remote temperature difference measuring device comprising a casing including at least a sensor for sensing the infrared radiation emitted by a surface, a measuring circuit comparing the value currently measured by the sensor with a value stored into a memory circuit and display means to display the algebraic difference between said two values; the measuring device further comprising means for positioning said sensor, including a pair of sources of conical light rays positioned outside said casing. and inclined with respect to the axis thereof: when the conical light rays are superimposed, the sensor is at a preset distance from the surface and is perpendicular thereto.
The predominant aim and use of WO-A-92/02792 is for measuring a difference of temperature: only if the stored value of temperature is known and/or it is constant, can WO-A-92/02792 be used for measuring a temperature by algebraically adding the known value to the difference of temperature read on the display means.
GB-A-2,291,498 shows a remote temperature detector, including a lens for focusing radiation from the heat source on a sensor belonging to the detector and a laser aiming system including a laser beam splitter assembly and a mirror: the two components of the split laser beam converge on the focal point of the sensor lens.
The laser beam splitter assembly acts as a laser beam splitter and as a deflecting means; the laser source, the laser beam splitter assembly and the mirror are positioned outside the casing of the detector shown by GB-A-2,291,498. Subject of the present invention is an infrared clinical thermometer that is exempt the limits and disadvantages presented by infrared thermometers of a known type.
SUMMARY OF INVENTION
The subject of the present invention is an infrared thermometer comprising at least a sensor which detects infrared radiation and a logical unit which processes the signal emitted by the sensor and drives display means for displaying the body temperature of the patient.
During measurement of patient's temperature, the sensor is put at a preset distance from the body of the patient, determined preferably by means of an optical aiming system belonging to the thermometer and comprising means for generating a pair of light rays and optical means that cause the aforesaid light rays to converge in a preset point, whose distance from the sensor is equal to the preset distance, the optical means being different from the generating means.
The sensor, the logical unit, the display means, the means for generating the pair of light rays and the optical means are positioned inside the casing of the thermometer.
REFERENCES:
patent: 4773766 (1988-09-01), Nagasaka et al.
patent: 5823678 (1998-10-01), Hollander et al.
patent: 5839829 (1998-11-01), Litvin et al.
patent: 6019507 (2000-02-01), Takaki
patent: 6102564 (2000-08-01), Egawa
patent: 6109782 (2000-08-01), Fukura et al.
Abstract of WO94/20023, Oct. 16, 1999.
Bellifemine Francesco
Rudi Vincenzo
Bennett G. Bradley
Hedman & Costigan ,P.C.
La Tecnica S.r.l.
Verbitsky G.
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