(1) Field of the Invention
The present invention relates to a pressure instrument for measuring pressures such as water pressure, air pressure and the like.
(2) Description of the Prior Art
A pressure detecting instrument employing a semiconductor pressure sensor is well known which calculates water depth data and altitude data from the pressure data detected with the pressure sensor. For example, in U.S. Pat. No. 4,835,716 there is disclosed an electronic wrist watch embodying such a pressure detecting instrument.
In U.S. Pat. No. 4,783,772 there is disclosed an electronic wrist watch provided with functions of measuring and storing water depth data.
More specifically, the electronic wrist watch disclosed in U.S. Pat. No. 4,783,772 calculates and stores in a memory a maximum water depth data and diving time data in addition to water depth data while the user is diving. After diving, with use of the electronic wrist watch, the user can compare the maximum water depth data and diving time data with those previously obtained, respectively.
The electronic wrist watch disclosed in U.S. Pat. No. 4,783,772, however stores only data for one-time dive. Therefore, the user has to make notes of data stored in the memory before he dives next time.
As a consequence, consideration has been given to installation of a plurality of memories in the wrist watch for storing the maximum water depth data and diving time data for several-time dives. However, when a diver dives, he needs not only the maximum water depth data and dive time data but also the other conditions such as water temperature, ocean current, ebb tide and flood tide. Accordingly, a wrist watch may be constructed which is provided with memories sufficient for storing these data, however such wrist watch will need a large number of keys for entering these data, resulting in inconvenient bulk or size and troublesome manipulation of these keys.
Further, even though the wrist watch is installed with a plurality of memories, it stores such data as obtained even when the diver dives by skin diving (breath hold diving) for a short time, resulting in short in the memory.