JPH0361124B2 - - Google Patents

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to improving the accuracy of a water depth meter.

[Prior art]

Generally, water depth measurement is performed by measuring pressure using the fact that pressure and water depth are in a proportional relationship. The relationship between pressure and water depth value is shown by the following equation.

g×ρ×ε×D=P Here g: gravitational acceleration ρ: Density of pure water at 4℃ ε: specific gravity D: Water depth value P: pressure It is.

Based on this formula, let's consider the relationship between pressure and water depth from the perspective of accuracy.

The gravitational acceleration g varies depending on the location on the earth, but it is a negligible value. ρ is also constant at 1000Kg/ ^m3 . Specific gravity ε has different values depending on the water temperature and the water quality environment at the time of measurement (freshwater or seawater). The effect of water temperature is that as the temperature rises, ε decreases, and as the temperature decreases, ε increases, but this difference is small and can be ignored. However, the specific gravity ε varies greatly from 1 to 1.05 due to the difference in the water quality environment (freshwater or seawater) in which the measured value is measured. For example, let P ₁ be the pressure at a point indicating a depth of 100 m in fresh water with a specific gravity of 1. Then, the specific gravity
In seawater with pressure P of 1.05, the depth value at _one point is 1.05 of the former.
Minute 1≒95.2m. In other words, at _one point with the same pressure P,
There will be a difference of 4.8m between the two. This difference due to specific gravity appears when water depth is measured by measuring pressure.

Therefore, no matter how accurate a pressure detection sensor, sensor output signal processing circuit, and adjustment to improve accuracy are used in manufacturing a water depth gauge, the water depth value is still measured by measuring pressure. As mentioned above, errors due to specific gravity have been considered to be unavoidable errors.

〔the purpose〕

The present invention solves these drawbacks,
The aim is to propose a portable device with a depth measurement function that reduces errors caused by differences in specific gravity in depth gauges that measure water depth by measuring pressure.

〔overview〕

The portable device with a water depth measurement function of the present invention includes a storage means that stores two or more types of water quality environments in advance, a selection means that makes it possible to select this water quality environment by external operation, a display means that displays the selected water quality environment.
It is characterized in that it has a calculation means for calculating a water depth value based on a selected water quality environment, and reduces errors in water depth values due to differences in specific gravity.

Hereinafter, the present invention will be described in detail based on examples.

〔Example〕

FIG. 1 shows an external view of a wristwatch with a depth measuring function as an example of the present invention. In the figure, 1 is an exterior case, 2 is a parting plate, and 3
is the display section. 4 is a symbol printed on the parting board indicating the water quality environment, and 5 is an indicator formed in a part of the display section 7. By operating the external switch 6, the indicator 5 lights up under the water quality environment display symbol S or L, so that the selected water quality environment can be confirmed. Regarding the water quality environmental indicator symbol 4, in the drawing, freshwater is indicated by the initial letter LAKE, and the symbol is "L", and seawater is indicated by the initial letter SEA, but it is not limited to this. Alternatively, these symbols may be printed on the cover glass 8. Also, regarding indicator 5, it is not limited to triangles.
It can be of any shape. The lighting method may be constant lighting or flashing lighting.

FIG. 2 shows a configuration in which the water quality environment selected by the character 9 is displayed on the display section 7.

Next, the internal configuration of the example shown in FIGS. 1 and 2 will be described.

FIG. 3 shows a general block diagram of the internal circuit configuration. 10 is a pressure sensor that detects water pressure, 11 is a sensor drive circuit that drives the pressure sensor, 6 is an external switch, 12 is a display section, and 13 is an AD conversion circuit that converts the output signal of the pressure sensor into a digital signal. 14 is a one-chip microcomputer that stores the water quality environment in advance;
A water quality environment selection means for selecting a stored water quality environment based on an input signal from the external switch 6, a water quality environment display means for displaying the selected water quality environment on the display section 12, and a water quality environment display means for displaying the selected water quality environment. Both are equipped with calculation means for calculating the water depth value. FIG. 4 shows the one-chip microcomputer and peripheral circuits in more detail. In the figure, the area surrounded by dotted lines is the one-chip microcomputer 14. Memories of water quality environment (in the examples in Figures 1 and 2,
The binary values corresponding to S and L and SEA and LAK) are
It is stored in ROM (read only memory) 15. 6 is a switch, one end of which is connected to VDD, and the other end connected to VSS and an IO port (input/output device) 16 via a resistor R. When the switch is turned on, the high level is digitally set, and the switch is turned on.
When turned OFF, a low level is input through the IO port, and the selection of the water quality environment is determined by the water quality environment selection means. The selected water quality environment is displayed on the display section through the IO port 16 in the form of 4 shown in FIG. 1 and 9 shown in FIG. 2. The water depth value is calculated by an ALU (arithmetic unit) 17 using a value selected from among the values stored in the ROM 15. The calculated water depth value is displayed on the display unit through the IO port 16. In addition, 18 is RAM
(random access memory), 19 is an oscillation circuit.

As an example, as shown in the example, if two values are prepared for the water quality environment, [in the possible water quality environment (specific gravity 1 to 1.05), for example, specific gravity
Set selectable water quality environmental values of 1.17 and 1.34. ]
Errors caused by differences in specific gravity can be made smaller than with conventional water depth measurement devices. Needless to say, this error will become smaller if the selectable water depth environmental values are further increased.

〔effect〕

As described above, according to the present invention, the user can judge the water quality environment and select the water quality environment by operating a switch from the outside while checking the display, and can measure the pressure. By doing so, it is possible to minimize errors due to differences in specific gravity in a water depth meter that measures water depth values.

As described above, the effects of the present invention are significant.

[Brief explanation of drawings]

Fig. 1: A diagram showing an external view of an embodiment of a portable device with water depth measurement function according to the present invention, Fig. 2 a, b:
Figure 3: Schematic block diagram of internal circuit configuration; Figure 4: One-chip microcomputer;
FIG. 3 is a diagram illustrating the peripheral circuits in further detail. Here, 1...Exterior case, 2...Parting board, 3
...Display part, 4...Water quality environment display symbol, 5...Indicator, 6...External switch, 7...Display part, 8...Cover glass, 9...Water quality environment display character, 10...Pressure sensor, 11...Sensor drive circuit, 12...Display section, 13...AD conversion circuit, 14...One-chip microcomputer, 15...
ROM, 16...IO port, 17...ALU, 18
...RAM, 19...oscillation circuit.

Claims (1)

[Claims] 1 A pressure sensor that converts at least water pressure into an electrical signal, a pressure sensor drive circuit that drives the pressure sensor, a signal processing circuit that converts the electrical signal from the pressure sensor into a desired measurement signal,
a decoding circuit that generates a signal for displaying a water depth value based on the signal from the signal processing circuit; a display unit;
A portable device with a water depth measurement function comprising a power supply, a case covering the above-mentioned elements, and a cover glass located above the display section and integrated with the case,
a memory circuit that stores two or more types of water quality environments in advance; a selection input circuit that allows the water quality environment to be selected by external operation; a water quality environment display circuit that displays the water quality environment selected by the selection input circuit on the display unit; A portable device with a water depth measurement function, comprising: a calculation circuit that calculates a water depth value based on the water quality environment selected by the selection input circuit.