JP3151890B2 - Electronic depth gauge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic water depth gauge, and more particularly to an electronic water depth gauge that indicates the current partial pressure of inert gas in a tissue relative to a safe allowable limit when diving.

[0002]

2. Description of the Related Art When diving deep into the water, decompression sickness becomes a problem. Therefore, an electronic water depth gauge has been devised, and the conventional electronic water depth gauge generally displays a floating method for preventing decompression sickness when ascending after diving. For example, a conventional electronic depth gauge generally uses a decompression table prepared by the U.S. Navy and the like, and according to the depth of the water and its residence time, the required decompression depth during ascent (depth to stay for decompression stop). And the decompression stop time (the time during which it must stay at the specified decompression depth) are displayed on the display. Therefore, when the diver dive, when ascending, when reaching the decompression depth according to the display of the electronic depth gauge, the diver stops ascent and stops at that depth for the time required for decompression (decompression stop time). To reduce pressure. By performing this ascent process according to the decompression depth and decompression stop time displayed according to the diving depth and the dwell time, decompression sickness can be prevented.

[0003]

However, in such a conventional electronic water depth gauge, the decompression depth and decompression stop time required for ascending after diving are displayed. Decompression can prevent decompression sickness, but how much the current inert gas partial pressure in the tissue is relative to the safe allowable limit of the inert gas partial pressure in the tissue when ascending. I can't tell if it is. This excessive intake of inert gas causes decompression sickness. The safe allowable limit is a value indicating the upper limit of the partial pressure of an inert gas that can float without worrying about decompression sickness. Therefore, there was a problem that it was not possible to know the detailed safety with respect to the safety tolerance of the inert gas partial pressure in the tissue, and even when diving to the limit of the safety tolerance, that fact could not be known. . As a result, there is still room for improvement in improving diving safety. Therefore, the present invention calculates the current partial pressure of the inert gas in the tissue for each tissue part of the human body in accordance with the diving condition, and also sets the safety allowable limit amount during floating of the partial pressure of the inert gas in the tissue. By calculating and outputting the ratio of the inert gas partial pressure in the tissue to the human body at the time of ascent, it is possible to know the current inert gas partial pressure in the tissue with respect to the safe allowable limit of the partial pressure of the inert gas in the tissue. The aim is to improve safety in diving.

[0004]

Means for Solving the Problems To achieve the above object, the invention according to claim 1 is directed to a method for ascending a partial pressure of inert gas in a tissue which is preset for each of a plurality of tissue sites of a human body during diving. A safety limit amount storing means for storing a safety allowable limit amount in the above, a pressure detecting means for detecting a pressure,
Based on the pressure detected by the pressure detecting means, for each tissue part of the human body, a partial pressure calculating means for calculating the current partial pressure of the inert gas in the tissue, and a current partial pressure calculated by the partial pressure calculating means. Percent data of the inert gas partial pressure in the tissue with respect to the safety allowable limit stored in the safety limit storage means.
A percentage calculating means for calculating the data, the percentage calculation
Display means for displaying the percentage data of the output means . In this case, the percentage
The calculating means may be, for example, as described in claim 2.
Percentage of said safety limit in feet
Calculating a Todeta, also the tissue in an inert gas, for example, as described in claim 3, a nitrogen gas. Further, the display means digitally displays the percentage data , for example, as described in claim 4 .

[0005]

According to the present invention, the safety allowable limit amount at the time of floating of the partial pressure of the inert gas (for example, nitrogen gas) in the tissue set in advance for each of a plurality of tissue parts of the human body during diving is stored in the safety limit amount storage means. And detected by pressure detection means
Based on the measured pressure, the current inert gas partial pressure in the tissue for each tissue site of the human body is calculated, and the percentage of the current inert gas partial pressure in the tissue with respect to the safety allowable limit is calculated.
By calculating the over data, and displays the display means. That is,
The pressure is detected by the pressure detection means, and based on this pressure
Then, for each tissue part of the human body in which the safety limit amount is stored in the safety limit amount storage means, the current partial pressure of the inert gas in the tissue is calculated by the partial pressure calculation means. Of the current inert gas partial pressure in the tissue calculated according to the safety allowable limit amount stored in the safety limit storage means.
The percent data is calculated by the percent calculating means . An output unit such as a display unit outputs the percentage data of the current tissue inert gas partial pressure with respect to the safety allowable limit calculated by the percentage calculation unit . Therefore,
During a dive, the diver can easily find out what percentage of the current inert gas partial pressure in each tissue is relative to the allowable safety limit. The state can be known directly . As a result, in the dive, it is possible to know the ratio of the dive with respect to the safety dive limit, and it is possible to further improve the dive safety.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. 1 to 9 are views showing an embodiment of an electronic depth gauge according to the present invention. FIGS. 1 and 2 are external views of the electronic depth gauge 1. The electronic depth gauge 1 is provided with a display unit 3 and various switches 4, 5, 6 on a main body case 2. As the display unit 3, for example, a liquid crystal display device is used, and display according to various mode settings is performed.
Display contents of the display unit 3 in FIGS. 1 and 2 will be described later. Switches 4, 5, and 6 operate in various operation modes (for example,
It is used for switching between the clock mode and the depth gauge mode), for instructing start / stop of measurement start in the depth gauge mode, and for switching and correcting display contents in various modes.

FIG. 3 is a circuit block diagram of the electronic depth gauge 1. The electronic depth gauge 1 includes an oscillation circuit 11 and a frequency dividing circuit 1.
2. Clock counting circuit 13, CPU (Central Processing U)
nit) 14, ROM (Read Only Memory) 15, RAM (R
and an access memory 16, a pressure sensor 17, an amplification circuit 18, an A / D conversion circuit 19, a switch section 20, a display drive circuit 21 and a display section 3.

The oscillation circuit 11 is a so-called crystal oscillation circuit including a crystal, a resistor, a capacitor, and the like, and generates an original clock signal having a constant frequency.

The frequency dividing circuit 12 is formed, for example, by combining several stages of binary counters.
The original clock signal input from the oscillation circuit 11 is frequency-divided to generate a 1 Hz reference clock signal that can be used as a clock reference signal, and outputs it to the clock counting circuit 13. The clock counting circuit 13 counts the current time and the elapsed time from the start of diving based on the reference clock signal from the frequency dividing circuit 12 and outputs the clock to the CPU 14. The CPU 14 receives the clock from the clock counting circuit 13. By driving the display drive circuit 21 based on the measured time data, the current time, the elapsed time from the start of diving, and the like are displayed and output.

In the ROM 15, a program as the electronic depth gauge 1 and various programs necessary for other mode processing are stored, and a tissue set in advance for each of a plurality of tissue parts of the human body during diving. The safety allowable limit when the internal inert gas partial pressure (for example, nitrogen gas partial pressure) floats is stored. As the allowable safety limit stored in the ROM 15, for example, a decompression table of the United States Navy is stored, and this decompression table is, for example, as shown in FIG. Is stored. In FIG. 4, the half-saturation time is the time required to reach 50% of the saturation amount of the inert gas in the human body tissue, and the M value is the maximum value of the half-saturation time tissue in the human body. Even if the active gas is dissolved, it is a safe allowable inert gas partial pressure, that is, a maximum allowable supersaturation pressure within a specified floating speed, and this value can be regarded as a safe allowable limit. Fsw is a unit of water pressure corresponding to water depth. Each additional foot depth increases by 1 fsw. Therefore, the ROM 15 functions as a safety limit storage means for storing the allowable safety limit when each part of the human body floats. If this value is exceeded, it must be stopped (decompression stop) until the internal inert gas partial pressure drops below the M value at a predetermined water depth, and it is not allowed to rise to that point.

The RAM 16 is used as a work memory, and stores various data during diving as diving record data.

The CPU 14 controls each section of the electronic depth gauge 1 according to a program stored in the ROM 15 and performs various processes as the electronic depth gauge 1 and processes as a clock.

The pressure sensor 17 is constituted by a piezoelectric element or the like, detects an environmental pressure, particularly, a water pressure, and outputs a detection result to the amplifier circuit 18. The amplification circuit 18 includes the pressure sensor 17
A / D conversion circuit 19 amplifies the detection signal input from
Output to The A / D conversion circuit 19 converts the analog detection signal input from the amplification circuit 18 into a digital signal,
Output to PU19. Further, the CPU 14 calculates the water depth based on the detection signal, and calculates the nitrogen partial pressure in the body for each of a plurality of tissue sites of the human body based on the calculated water depth and the residence time. Therefore, the CPU 14 functions as a partial pressure calculating unit that calculates the current partial pressure of the inert gas in the tissue for each tissue part of the human body based on the water depth and the dive time. Further, the ratio between the allowable safety amount stored in the ROM 15 and the nitrogen partial pressure in the body is calculated. Therefore, CPU1
Reference numeral 4 functions as a partial pressure ratio calculating means for calculating the ratio of the calculated current inert gas partial pressure in the tissue to the safe allowable limit.

The switch section 20 includes the above-described various switches 4,
The CPU 11 detects the scanning state of the switch unit 20 and performs a process corresponding to the operation of the switch unit 20.

The display drive circuit 21 is driven under the control of the CPU 14 and drives the display unit 3 according to display data input from the CPU 14. Various data are displayed on the display unit 3 by driving the display drive circuit 21.

Next, the operation will be described. In the following description of the operation, for simplicity, the case where the inert gas is only nitrogen will be described. However, the present invention is not limited to only nitrogen, and it affects human body tissues during diving and reduces decompression sickness. Applicable to any inert gas that may be produced.

When diving, the partial pressure of nitrogen in the body tissue of a diver generally changes as shown in FIG. That is, if the stagnation is performed under the water pressure of N, the nitrogen partial pressure in the human body tissue gradually increases with the lapse of the residence time from the P partial pressure of the human body tissue when the residence time is 0, and becomes N. Saturates to a partial pressure of nitrogen in the body.

Therefore, in this embodiment, when diving is performed,
As shown in FIG. 6, first, constants such as each M value and half-saturation time are read from the ROM 15 and written into the RAM 16 (step S1), and the water pressure is detected by the detection signal from the water pressure sensor 17 (step S2). When the detection data of the water pressure is input, the CPU 14 calculates the water depth from the input water pressure (step S3). The calculation of the water depth is based on a water depth calculation method conventionally performed by a water depth gauge.

After calculating the water depth, it is determined whether or not diving has started (step S4). This determination of whether to start diving is made by checking whether the water depth has reached a predetermined water depth and the dive at that water depth has passed for a predetermined time, for example, whether or not the water depth of 1.5 meters or less has continued for 10 seconds or more. When this condition is satisfied, it is determined that diving has started.

If the dive is not started, it is determined whether or not the dive is stopped (step S5). The determination as to whether or not to stop the dive is made by checking whether or not a predetermined time has elapsed at a water depth shallower than the predetermined water depth different from the determination as to whether or not the dive has started. It is checked whether the diving is stopped if the above conditions are satisfied. If it is determined that the dive is to be stopped, the process is terminated as it is. If it is not determined that the dive is to be stopped, the process returns to step S2, where the detection of the water pressure and the calculation of the water depth are performed in the same manner to check whether or not the dive is started (steps S3, S4). .

If it is determined in step S4 that diving has started,
The water pressure is detected (step S6), and the water depth is calculated based on the detected water pressure (step S7). The measurement of the dive time is started from the start of the dive.

After calculating the water depth, the nitrogen pressure in the body is calculated for each tissue part of the human body (step S8). This partial pressure of nitrogen in the body is calculated by the following equation. Q (i) = P (i) + (NP ⁽ i)) * (1−0.5 ^{(TIM / H (i))} ) (1) where Q (i) is the current Nitrogen partial pressure of tissue number i (b
ar), P (i) are the nitrogen partial pressure (bar) of the tissue number i before T time (minute), N is the nitrogen partial pressure of the respiratory gas (eg, 0.79) (bar), H (i) ) Is the half saturation time (min) of the tissue number i.

When the nitrogen partial pressure in the body at each tissue site of the human body is calculated by the above equation (1), the ratio of the nitrogen partial pressure in the body to the safety allowable limit (internal nitrogen partial pressure / safe allowable limit × 10) is calculated.
0 (%)) is calculated for each organizational unit (step S).
9). Next, the in-vivo nitrogen partial pressure calculated by the above equation (1) is compared with the allowable safety limit stored in the ROM 15 to check whether the in-vivo nitrogen partial pressure is equal to or less than the allowable safety limit (step). S10). In the present embodiment, a value that requires decompression stop at a water depth of 10 feet (hereinafter referred to as an M value at 10 feet) is adopted as the safety allowable limit in this embodiment.

When the internal nitrogen partial pressure is equal to or lower than the allowable safety limit, the non-decompression diving time, which is the time required for decompression, is calculated, and the dive time, water depth, internal nitrogen partial pressure / safety allowable limit amount ratio. And the infinite pressure dive time is displayed on the display unit 3 (steps S11 and S12). This no-decompression diving time T
(I) is calculated by the following equation. T (i) =-H (i) * log (1-F (i)) / log2 (2) Here, F (i) is given by the following equation. F (i) = (M10 (i) -P (i)) / (NP (i)) (3)

Here, M10 (i) is the M value of each tissue part in the body at 10FT (feet). In the above equation (2), T (i) is satisfied only on the condition of 1−F (i)> 0, and can be calculated.
It is premised that the condition of F (i), that is, M10 (i) <N, is satisfied. That is, when the nitrogen partial pressure of the diver's respiratory gas exceeds the safe allowable limit, and if this condition is not satisfied, the internal nitrogen partial pressure exceeds the safe allowable limit no matter how long the condition is continued. Nothing.

The infinite pressure dive time calculated in this way, the ratio of the intracorporeal nitrogen partial pressure calculated in step S9 to the allowable safety limit, the water depth and dive time calculated in step S3 are shown in FIG. Display output to the display unit 3. That is, FIG. 1 shows the display content when the internal nitrogen partial pressure is equal to or less than the allowable safety limit, and the ratio between the internal nitrogen partial pressure and the allowable safety limit is expressed as a percentage. In FIG. 1, the indication "FREE" indicates that no decompression is necessary.

On the other hand, in step S10, the decompression stop depth (water depth) is determined (step S13), and the decompression stop time is calculated (step S14). This decompression stop water depth is R
It is determined by referring to the decompression table of OM15, and is determined by the decompression table according to the diving depth and the residence time. Further, the decompression stop time is set by setting the M value corresponding to the decompression stop water depth in the above equation (3), whereby the above (2)
For example, when the non-decompression water depth of 10 feet is the decompression stop water depth, for example, the M value at 10 feet serving as a reference for the safety allowable limit amount, that is, M1
By setting 0 (i), it can be calculated by the above equation (2).

The decompression stop water depth, the decompression stop time, the dive time, the current water depth, and the ratio between the nitrogen partial pressure in the body and the safety allowable limit thus obtained are output to the display unit 3 as shown in FIG. (Step S15).

For example, the relationship among the nitrogen partial pressure in the body, the dive time and the allowable safety limit can be shown in FIG.
The relationship between water depth and time at this time can be shown as in FIG. That is, as shown in FIG. 5, when staying under the water pressure of N, the nitrogen partial pressure in the human body tissue is determined by the elapse of the residence time from the nitrogen partial pressure in the human body tissue when P is zero. And gradually increases and saturates to the partial pressure of nitrogen in the body. Therefore, in FIG. 7, 10 is the water pressure at a depth of 10 feet, M10 is the M value at a depth of 10 feet, T1 is the time when the nitrogen partial pressure in the body exceeds M10, T4.
Is the time when the internal nitrogen partial pressure falls below M10, T0
When staying at a depth of N feet from T2 to T2, the nitrogen partial pressure in the body gradually increases and exceeds the value of M10. Thus, as shown in FIG. 2, a display is provided when decompression is required. Then, the diver knows that decompression is necessary during the ascent, and when the diver moves from the water depth N feet to the water depth 10 feet from T2 to T3, the diver stops at the water depth 10 feet for ΔT time. As a result, the partial pressure of nitrogen in the body
It decreases as shown in FIG. FIG. 8 shows the relationship between water depth and time at this time. Further, the ratio between the partial pressure of nitrogen in the body and the allowable safety amount at this time is shown in FIG. 9, and the ratio between the partial pressure of nitrogen in the body and the allowable safety amount is displayed in percentage in FIG. .

As described above, the ratio between the internal nitrogen partial pressure and the safe allowable limit is output and displayed on the display unit 3, and this display shows how dangerous the current internal nitrogen partial pressure is. It is possible to know whether the player is diving and to easily manage the physical strength during diving. As a result, diving safety can be further improved.

The above step S12 or step S1
When the display output by 5 is completed, it is checked whether or not the diving is completed (step S16). The determination as to whether or not the dive has been completed is made based on whether or not the dive at a water depth shallower than the predetermined water depth has continued for a predetermined time or more. For example, when diving has continued for 10 minutes or more at a water depth less than 1.0 meter, it is determined that diving has ended. When diving is not over,
It is checked whether a predetermined time (for example, 3 seconds) has elapsed from the start of the dive determined in step S4 (step S4).
17). If the predetermined time has not elapsed, the process proceeds to step S6 after waiting for the predetermined time to elapse, and similarly, a series of processes after the detection of the water pressure are performed.

If it is determined in step S16 that diving has been completed, the diving data detected and calculated in each of the above-described steps S is written in the RAM 16, and the process is terminated (step S18).

As described above, similarly to the conventional electronic depth gauge, when decompression is necessary, the decompression stop water depth and the decompression stop time can be displayed and output, and the decompression process during diving can be appropriately performed. In both cases where decompression is not required and when decompression is required, the ratio between the nitrogen partial pressure in the body and the safe allowable limit is
Since the information is displayed on the display unit 3, it is possible to know the danger of the current nitrogen partial pressure in the body by this display, and it is possible to easily manage the physical strength during diving. As a result, diving safety can be further improved.

[0034]

According to the present invention, it is possible to output the ratio between the nitrogen partial pressure in the body and the safe allowable limit, so that it is possible to determine how dangerous the current nitrogen partial pressure is in the body. It is possible to know, and it is possible to easily perform physical strength management during diving. As a result, diving safety can be further improved.

[Brief description of the drawings]

FIG. 1 is an external view showing an electronic water depth gauge according to an embodiment of the present invention, in which a display is provided when depressurization is not required.

FIG. 2 is an external view showing an electronic water depth gauge according to an embodiment of the present invention, which displays a display when decompression is required.

FIG. 3 is a circuit block diagram of an electronic depth gauge according to one embodiment of the present invention.

FIG. 4 is a diagram showing a part of a decompression table.

FIG. 5 is a diagram showing the relationship between the nitrogen pressure in the body and the dive residence time.

FIG. 6 is a flowchart showing various operation processes of the electronic depth gauge.

FIG. 7 is a view showing a relationship among a nitrogen partial pressure in the body, a dwell time, and a safe allowable limit when diving.

FIG. 8 is a diagram showing the relationship between water depth and residence time during diving.

FIG. 9 is a diagram showing a ratio between a partial pressure of nitrogen in the body and a safe allowable limit amount during dive in relation to a residence time.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electronic depth gauge 2 Main body case 3 Display part 4, 5, 6 switch 11 Oscillation circuit 12 Divider circuit 13 Clock circuit 14 CPU 15 ROM 16 RAM 17 Pressure sensor 18 Amplification circuit 19 A / D conversion circuit 20 Switch part 21 Display drive circuit

Claims (4)

(57) [Claims] 1. A safety limit amount storage means for storing a safety allowable limit amount at the time of floating of an inert gas partial pressure in a tissue preset for each of a plurality of tissue sites of a human body during diving, and detecting the pressure. Pressure detecting means; and partial pressure calculating means for calculating the current inert gas partial pressure in the tissue for each tissue part of the human body based on the pressure detected by the pressure detecting means; percentile of calculating the percentage data for the safety tolerable amount stored in the safe limit value memory of the calculated current tissue inert gas partial pressure by means
A cement calculation means, and displays the percentage data for the percentage calculation unit
An electronic water depth gauge comprising: a display unit . 2. The electronic depth gauge according to claim 1, wherein said percent calculating means calculates percent data for said safe allowable limit at 10 feet. 3. The electronic depth gauge according to claim 1, wherein the inert gas in the tissue is nitrogen gas. 4. The display means displays the percentage data.
The electronic depth gauge according to claim 1, wherein the digital depth gauge is displayed digitally .