Surgery – Diagnostic testing – Respiratory
Reexamination Certificate
1999-09-16
2001-07-10
Winakur, Eric F. (Department: 3736)
Surgery
Diagnostic testing
Respiratory
C600S532000, C073S023300, C073S023370, C250S343000, C250S339130, C356S437000
Reexamination Certificate
active
06258040
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of Invention
The present invention relates to an airway adapter for a non-dispersive infrared gas analyzer in which an infrared ray passes through apertures provided at opposite side wall portions of a flow tube, and an infrared ray detector measures an amount of the infrared ray which is absorbed and attenuated by gas flowing within the flow tube thereby to measure a concentration of the gas. In particular, the present invention relates to an airway adapter for a non-dispersive infrared gas analyzer which is provided between a patient and a respirator or an anesthesia machine and which measures the concentrations of various gases within a respiratory gas.
2. Related Art
When a mechanical ventilator assists a patient in breathing, an airway adapter is attached to a flow path between the patient and a mechanical ventilator and a concentration of carbon dioxide within the respiratory gas is measured.
FIG. 12
is a perspective view showing an example of the outward appearance of a generally known airway adapter. In
FIG. 12
, the center portion of a cylindrical flow tube
1
along the axial direction thereof is formed in a rectangular tubular shape in section. Circular aperture portions
2
formed by openings for passing an infrared ray therethrough are provided at opposite positions of both side walls of the flow tube, respectively. Transparent windows
3
formed by transparent films configured in a circular plate shape are hermetically attached to the aperture portions
2
, respectively.
As the transparent window
3
, there has been employed sapphire or a plastic sheet formed by a single sheet on which an anti-fogging layer is formed. As the plastic sheet, there has been employed a polyester sheet (hereinafter called a PET sheet)
5
on which a anti-fogging layer
4
can be easily formed by coating or deposition, as shown in FIG.
13
.
However, when the sapphire is employed as the material of the transparent window
3
, there arises a problem that the cost of the transparent window is expensive. Further, in this case, disadvantageously it is required to heat the transparent window by using a heater to prevent a condensation of water in the respiratory gas on the surface of the sapphire.
The PET sheet
5
on which the anti-fogging layer
4
is formed may be used as the transparent window
3
in place of the expansive sapphire. In this case, the cost for manufacturing the airway adapter can be reduced. Further, since the anti-fogging layer is hydrophilic, a thin water layer instead of water drops is formed on the surface of the transparent window
3
, whereby an infrared ray transmits through the transparent windows
3
without being scattered and so the transparent windows do not fog. Thus, the PET sheet has such an advantage that, since it is not necessary to heat the PET sheet by using a heater, the configuration of the analyzer can be simplified and the power consumption of the analyzer can be reduced. However, the PET sheet
5
is required to be made thinner in order to improve the transmittance of the infrared ray since it absorbs infrared rays. If the PET sheet is made thinner, the PET sheet is likely damaged by the heat or mechanical impact. Further, if the PET sheet
5
is made thinner, there arises a problem that, in the case where a water layer is formed on the surface of the anti-fogging layer
4
, the measured value of the gas concentration may contain an error due to the optical interference.
Polypropylene and polyethylene materials have good transmittance for an infrared ray. The transparent window
3
can be made sufficiently thick by using such material. However, in this case, the anti-fogging layer
4
can not be formed on the surface of the transparent window since each of the polypropylene and polyethylene is not good in adhesive property.
SUMMARY OF INVENTION
The present invention has been performed in view of the aforesaid conventional problems.
An object of the present invention is to provide an airway adapter for a non-dispersive infrared gas analyzer having transparent windows on anti-fogging layers which have good heat-resistance properties, mechanical strength and good transmittance and hardly causes optical interference.
In order to achieve the aforesaid object, according to the present invention, there is arranged in an airway adapter for a non-dispersion infrared ray gas analyzer including a flow tube for passing gas therethrough, aperture portions respectively formed by openings provided at opposite positions of a side wall of the flow tube which transmit an infrared ray therethrough, and transparent films hermetically attached to the aperture portions respectively, wherein
each of the transparent films is formed by a plurality of layers including a first film which is capable of forming the anti-fogging layer on a surface thereof and a second film for transmitting the infrared ray therethrough with a good transmittance,
each of the films for a anti-fogging layer is disposed at an inner side of the flow tube, and
each of the anti-fogging layers is formed on the surface of the first film.
The present invention provides an airway adapter which has the films for a anti-fogging layer formed by a polyester sheet and the good transmittance films formed by a polypropylene sheet. The present invention provides an airway adapter which has the films for an anti-fogging layer formed by a polyester sheet and the good transmittance films formed by a polypropylene sheet.
According to the aforesaid configuration of the present invention, since the polypropylene sheet (hereinafter called a PP sheet) with good transmittance and a PET sheet are laminated, the transparent film can be made thicker without reducing an amount of infrared ray which transmits therethrough. As a result, the transparent film can be improved in heat-resistance property and mechanical strength. Further, even in the case where a water layer is formed on the anti-fogging layer due to water vapor in a respiratory gas, it can be prevented that the measured value of the gas concentration contains an error due to the optical interference of the light.
REFERENCES:
patent: 5067492 (1991-11-01), Yelderman et al.
patent: 5095900 (1992-03-01), Fertig et al.
patent: 6044843 (2000-04-01), O'Neil et al.
patent: 6095986 (2000-08-01), Braig et al.
Dainobu Hidetoshi
Todokoro Noriaki
Yamamori Shinji
Natnithithadha Navin
Nihon Kohden Corporation
Sughrue Mion Zinn Macpeak & Seas, PLLC
Winakur Eric F.
LandOfFree
Airway adapter for non-dispersive infrared gas analyzer does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Airway adapter for non-dispersive infrared gas analyzer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Airway adapter for non-dispersive infrared gas analyzer will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2505808