Data processing: measuring – calibrating – or testing – Measurement system – Pressure
Reexamination Certificate
2001-05-03
2003-02-11
Wong, Don (Department: 2821)
Data processing: measuring, calibrating, or testing
Measurement system
Pressure
C368S010000, C368S011000, C128S201270
Reexamination Certificate
active
06519548
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a diver's information processing device. More particularly, the present invention is concerned with a technology for notifying a diver of a pressure decrease ratio at which pressure applied to a diver decreases during surfacing over diving for the purpose of minimizing the risk of the diver's decompression sickness or excess pulmonary expansion at a high altitude at which a pressure change rate tends to increase.
BACKGROUND ART
A diver's information processing device may be referred to as a so-called dive computer. A method of calculating the conditions for decompression after diving that is adapted to the diver's information processing device is described in “Dive Computers—A Consumer's Guide to History, Theory & Performance” (Watersport Publishing Inc., 1991) written by Ken Loyst et al. Moreover, discussions have been made on a calculating method described in a theoretical literature “Decompression—Decompression Sickness” (Springer, Berlin, 1984, pp.14) written by A. A. Buhlmann.
Based on the theory, the diver's information processing device calculates an amount of inert gas absorbed into a body and an amount of inert gas discharged therefrom during and after diving so as to grasp an amount of intracorporeal inert gas all the time. The diver's information processing device is thus designed to minimize the risk of a diver's decompression sickness.
Moreover, if a surfacing speed is too high, nitrogen or any other inert gas having permeated into a body becomes bubbles to cause decompression sickness. From a viewpoint of averting decompression sickness, it is important to observe a specific surfacing speed at which a diver should come up to the surface. In some conventional diver's information processing devices, the surfacing speed is monitored. If a current surfacing speed is faster than the pre-set upper limit of a surfacing speed, a warning indicating that a specified surfacing speed is violated is generated to inform the diver of the fact.
Moreover, the surfacing speed may not be related to a change in hydraulic pressure occurring during surfacing. Specifically, in some diver's information processing devices, a variation of a ratio of hydraulic pressure detected before surfacing to hydraulic pressure detected after surfacing, which is detected during a unit time, is taken into account. The upper limit of a surfacing speed is determined in association with each depth of water, and the surfacing speed is monitored.
However, these devices have a drawback that no consideration is taken into an atmospheric pressure on water in which diving is performed. A case where diving is performed at a high altitude at which the atmospheric pressure on water is low is compared with a case where diving is performed at a low altitude at which the atmospheric pressure on water is high. Consequently, it is revealed that even if a diver surfaces by the same distance at the same time instant in the water that exhibits the same concentration, a pressure change rate is smaller when diving is performed at the high altitude. Herein, the pressure change rate is a quotient of a pressure detected after the end of travel by a pressure detected before the start of the travel. However, the air in the lungs is inversely proportional to the pressure change rate, and is likely to expand more greatly than it is when diving is performed at the low altitude. When diving is performed at the high altitude, the risk of a diver's decompression sickness or excess pulmonary expansion increases.
Nevertheless, although some diver's information processing devices have the upper limit of a surfacing speed, at which surfacing is performed, set in association with a depth of water, many diver's information processing devices have the upper limit of a surfacing speed set to a fixed value. No consideration is taken into the atmospheric pressure on water. From a viewpoint of putting emphasis on safety, the upper limit of a surfacing speed cannot help being set to a considerably small value. As a result, when diving is performed at a high altitude at which an atmospheric pressure on water is low, a warning indicating that a specified surfacing speed is violated is generated frequently, though the surfacing speed is tolerable. Therefore, information that does not match the current situation is provided. In contrast, when the upper limit of a surfacing speed is set to a large value in order to prevent incorrect generation of a warning, it is hard to reliably avert decompression sickness.
In consideration of the foregoing drawbacks, an object of the present invention is to provide a diver's information processing device capable of setting the upper limit of a pressure decrease ratio, at which pressure decreases during surfacing, according to an atmospheric pressure on water in which diving is performed, and properly monitoring a surfacing speed during diving performed even at a high altitude at which the atmospheric pressure on water is low.
DISCLOSURE OF INVENTION
For accomplishing the above object, according to one aspect of the present invention, a diver's information processing device comprises a pressure metering means, a diving time measuring means, a pressure decrease ratio calculating means, an upper limit-of-pressure decrease ratio setting means, and a pressure decrease ratio comparing means. The diving time measuring means measures a diving time. The pressure decrease ratio calculating means calculates a pressure decrease ratio, at which pressure decreases during surfacing, according to the pressure measured by the pressure metering means and the diving time measured by the diving time measuring means. The upper limit-of-pressure decrease ratio setting means sets the upper limit of a pressure decrease ratio. The pressure decrease ratio comparing means compares the upper limit of a pressure decrease ratio set by the upper limit-of-pressure decrease ratio setting means with the current pressure decrease ratio calculated by the pressure decrease ratio calculating means. The upper limit-of-pressure decrease ratio setting means sets the upper limit of a pressure decrease ratio, at which pressure decreases during surfacing within diving, according to information of an atmospheric pressure on water in which diving is performed.
According to the present invention, for monitoring whether a pressure decrease ratio at which pressure decreases during surfacing over diving is appropriate, the upper limit of a pressure decrease ratio is set to a predetermined value associated with an atmospheric pressure on water. What is referred to as the pressure decrease ratio is a quotient of a difference between a current absolute pressure and an absolute pressure detected t sec (min) earlier by a time t. The pressure decrease ratio is compared with the upper limit of a pressure decrease ratio that is associated with a current atmospheric pressure on water. For example, the upper limit of a pressure decrease ratio is set to a small value for diving performed at a high altitude at which the atmospheric pressure on water is low. This is because a change in absolute pressure, which is applied to a diver during surface per unit time is larger when diving is performed at a high altitude, at which the atmospheric pressure on water is low, than when diving is performed at a low altitude at which the atmospheric pressure on water is high. A variation per unit time of a ratio of an absolute pressure detected before start of surfacing to an absolute pressure detected thereafter has a more significant meaning than a decrease ratio at which a hydraulic pressure decreases during surfacing over diving. In Japanese Unexamined Patent Publication No. 10-250683, the upper limit of a surfacing speed is determined based on the current depth of water. Moreover, since the variation of the ratio of the absolute pressures detected before and after surfacing is taken into account, a mere surfacing speed is not employed but a pressure is adopted in
Aizawa Hitomi
Kuroda Masao
Gabrik Michael T.
Seiko Epson Corporation
Vo Tuyet T.
Wong Don
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