Abstract:
A portable pressure measuring apparatus detects a designated altitude by sensing an outside atmospheric pressure. An A/D converter generates pressure data corresponding to the outside pressure. Pressure data corresponding to a designated altitude is stored in a memory, and the pressure data generated by the A/D converter is compared with the stored pressure data. The designated altitude may be set to any value through a manually-operated input switch and converted into pressure data. Alternatively, the designated altitude may be set as the altitude at which the apparatus is positioned by converting pressure data generated by the A/D converter at that altitude into a corresponding altitude.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a portable pressure measuring apparatus for detecting a designated altitude by sensing an outside pressure, and more particularly to a portable pressure measuring apparatus for detecting a designated altitude by using pressure data so that a high time resolution is obtained. 
     2. Description of the Prior Art 
     As a conventional portable pressure measuring apparatus, there is known a wristwatch with an altitude measurement function. FIG. 5 is a block diagram showing a schematic structure of a conventional wristwatch with an altitude measurement function. The conventional wristwatch with the altitude measurement function includes a pressure sensor  501  for sensing an outside pressure, that is, an atmospheric pressure, an A/D conversion portion  502  for generating digital pressure data by performing A/D (analog/digital) conversion of sensor output (sensing result) of the pressure sensor  501 , a calculation portion  503  for calculating altitude data corresponding to the pressure data generated in the A/D conversion portion  502 , a measurement control portion  504  for controlling the pressure sensor  501  and the A/D conversion portion  502 , a control portion  505  for controlling the whole of the wristwatch with the altitude measurement function, a switch input portion  506  by which a user makes input, a display portion  507  for making display, and a storage portion  508  for storing data. 
     The storage portion  508  stores altitude data of a designated altitude as a threshold, and the control portion  505  compares the altitude data calculated by the calculation portion  503  with the altitude data stored in the storage portion  508  to detect the designated altitude. In the case where the designated altitude is detected, the control portion  505  gives an alarm. 
     In the above structure, the operation of the conventional wristwatch with the altitude measurement function will be described with reference to FIGS. 6,  7  and  8 . FIG. 6 is a flowchart showing the flow of normal altitude measurement processing in the conventional wristwatch with the altitude measurement function. In the normal altitude measurement processing of the conventional wristwatch with the altitude measurement function, first, the control portion  505  drives the pressure sensor  501  through the measurement control portion  504  to sense the outside pressure (step S 601 ). Subsequently, the A/D conversion portion  502  makes A/D conversion of sensor output of the pressure sensor  501  to generate pressure data (step S 602 ). Next, the calculation portion  503  inputs the pressure data from the A/D conversion portion  502  and calculates altitude data corresponding to the input pressure data (step S 603 ). The control portion  505  inputs the altitude data from the calculation portion  503  and causes the display portion  507  to display the altitude (step S 604 ). Here, a pressure value may be displayed, or the pressure data or the altitude data calculated in the calculation portion  503  may be stored in the storage portion  508 . 
     Next, the process for setting of a threshold altitude will be described. In the case where there occurs an input for setting a measurement value of an altitude as a threshold, or there occurs an input for setting a threshold by a user&#39;s direct designation of an altitude, the setting processing of the threshold is started. FIG. 7 is a flowchart showing the flow of the process for setting of a threshold altitude in the conventional wristwatch with the altitude measurement function. In the setting processing of the threshold in the conventional wristwatch with the altitude measurement function, first, the control portion  505  judges whether there occurred an input for setting a measurement value of an altitude as a threshold through the switch input portion  506  (step S 701 ). 
     In the case where the input for setting the measurement value of the altitude as the threshold was made, the control portion  505  drives the pressure sensor  501  to sense an outside pressure (step S 702 ), the A/D conversion portion  502  makes A/D conversion of sensor output of the pressure sensor  501  to generate pressure data (step S 703 ), and the calculation portion  503  calculates altitude data from the pressure data generated in the A/D conversion portion  502  (step S 704 ). On the other hand, in the case where it is judged, at step S 701 , that the input for setting the measurement value of the altitude as the threshold was not made, altitude data is input through the switch input portion  506  (step S 706 ). The control portion  505  causes the storage portion  508  to store the altitude data calculated in the calculation portion  503  or the altitude data input through the switch input portion  506  as the threshold (step S 705 ). 
     Next, detection processing of an altitude will be described. In the case where there occurs an input of instructions to start detection processing through the switch input portion  506 , the detection processing of the altitude is started. FIG. 8 is a flowchart showing the flow of the detection processing of the altitude in the conventional wristwatch with the altitude measurement function. In the detection processing of the altitude in the conventional wristwatch with the altitude measurement function, first, the control portion  505  drives the pressure sensor  501  to sense the outside pressure (step S 801 ), the A/D conversion portion  502  makes A/D conversion of sensor output of the pressure sensor  501  to generate pressure data (step S 802 ), and the calculation portion  503  calculates altitude data from the pressure data generated in the A/D conversion portion  502  (step S 803 ). The control portion  505  inputs the altitude data calculated in the calculation means  503 , and displays the altitude through the display portion  507  (step S 804 ). 
     Next, the control portion  505  compares the altitude data calculated in the calculation portion  503  with the altitude data stored in the storage portion  508 , and judges whether the calculated altitude data exceeds the stored altitude data, that is, whether the difference between the calculated altitude data and the stored altitude data is changed from a positive to a negative or from a negative to a positive (S 805 ). In the case where the altitude data calculated in the calculation portion  503  does not exceed the altitude data stored in the storage portion  508 , the processing returns to step S 801 . In the case where the altitude data calculated in the calculation portion  503  exceeds the altitude data stored in the storage portion  508 , it is judged that the designated altitude is detected and the processing is ended. 
     Here, in a time required for the detection processing of the altitude, the ratio of a calculation time for calculating the altitude data at step S 803  is large, and a time resolution of the altitude detection, that is, a measurement period in which the steps from step S 801  to step S 805  are repeated mainly depends on the calculation time of step S 803 . Thus, calculation processing capacity to a certain extent is required. If a clock frequency of the conventional wristwatch with the altitude measurement function is a clock frequency (several tens of kHz to several MHz) of a general portable apparatus, the time resolution of the altitude detection become s about several hundred ms. 
     As described above, according to the conventional portable pressure measuring apparatus, the designated altitude is detected by comparing the previously stored altitude data of the designated altitude with the altitude data calculated from the pressure data corresponding to the outside pressure. 
     However, according to the foregoing conventional technique, since the calculation time for determining altitude is long and the time resolution of the altitude detection is coarse, in the case where it is used in an application in which the altitude changes at a high speed, for example, gliding on skis, skydiving, or the like, which requires a time resolution of about 100 ms to 10 ms, a time delay in the altitude detection can not be neglected, and there has been a problem in that suitable altitude detection can not be achieved. 
     The present invention has been made in view of the above, and an object thereof is to lessen a time delay in altitude detection and to enable suitable altitude detection. 
     SUMMARY OF THE INVENTION 
     In order to achieve the above object, according to a portable pressure measuring apparatus of the invention, in the portable pressure measuring apparatus for detecting a designated altitude by sensing an outside pressure, in order to enable the operation of altitude data calculation to be omitted in altitude detection processing (detection processing of an altitude), there are provided generation means for generating pressure data corresponding to the outside pressure, storage means for storing pressure data corresponding to the designated altitude, and detection means for detecting the designated altitude by comparing the pressure data generated in the generation means with the pressure data stored in the storage means. Here, if display of the pressure and altitude is omitted, a time of display processing can be further saved. 
     Besides, it is also permissible to provide input means for inputting the designated altitude, and pressure data calculation means for calculating pressure data corresponding to the designated altitude inputted through the input means and for storing it in the storage means, so that the designated altitude can be directly set. Besides, it is also permissible to provide input means for inputting instructions to set an altitude where the apparatus itself is positioned as the designated altitude, and pressure data setting means for storing pressure data generated in the generation means as the pressure data corresponding to the designated altitude into the storage means in the case where input is made through the input means, so that the altitude where the apparatus itself is positioned can be set as the designated altitude. 
     Moreover, it is also permissible to provide generated pressure data, storage means for storing the pressure data generated in the generation means, and altitude data calculation means for calculating altitude data on the basis of the pressure data stored in the generated pressure data storage means, so that a change in altitude during altitude detection processing can be confirmed after the altitude detection processing is ended. Besides, in addition to the altitude, the depth of water may be detected. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A preferred form of the present invention is illustrated in the accompanying drawings in which: 
     FIG. 1 is a block diagram showing a schematic structure of a wristwatch with an altitude measurement function according to an embodiment of the invention; 
     FIG. 2 is a flowchart showing the flow of threshold setting processing in the wristwatch with the altitude measurement function of the embodiment; 
     FIG. 3 is a flowchart showing altitude detection processing in the wristwatch with the altitude measurement function of the embodiment; 
     FIG. 4 is a flowchart showing the flow of altitude data confirmation processing of the embodiment; 
     FIG. 5 is a block diagram showing a schematic structure of a conventional wristwatch with an altitude measurement function; 
     FIG. 6 is a flowchart showing the flow of normal altitude measurement processing in the conventional wristwatch with the altitude measurement function; 
     FIG. 7 is a flowchart showing the flow of threshold setting processing in the conventional wristwatch with the altitude measurement function; and 
     FIG. 8 is a flowchart showing the flow of altitude detection processing in the conventional wristwatch with the altitude measurement function. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described in detail with reference to accompanying drawings. Here, as a portable pressure measuring apparatus of an embodiment of the invention, a wristwatch with an altitude measurement function will be exemplified. FIG. 1 is a block diagram showing a schematic structure of a wristwatch with an altitude measurement function according to an embodiment of the invention. 
     The wristwatch with the altitude measurement function of the embodiment includes a pressure sensor  101  for sensing an outside pressure, that is, an atmospheric pressure, an A/D conversion portion  102  for generating digital pressure data by carrying out A/D (analog/digital) conversion of sensor output (sensing result) of the pressure sensor  101 , a calculation portion  103  for calculating altitude data corresponding to pressure data and for calculating pressure data corresponding to altitude data, a measurement control portion  104  for controlling the pressure sensor  101  and the A/D conversion portion  102 , a control portion  105  for controlling the whole of the wristwatch with the altitude measurement function, a switch input portion  106  by which a user makes input, a display portion  107  for making display, and a storage portion  108  for storing data. 
     The storage portion  108  stores pressure data corresponding to a designated altitude as a threshold, and the control portion  105  compares the pressure data generated in the A/D conversion portion  102  with the pressure data stored in the storage portion  108  to detect the designated altitude. In the case where the designated altitude is detected, the control portion  105  gives an alarm. 
     Incidentally, the pressure sensor  101  and the A/D conversion portion  102  correspond to generation means of the invention, the storage portion  108  corresponds to storage means and generated pressure data storage means of the invention, the control portion  105  corresponds to detection means and pressure data setting means of the invention, the switch input portion  106  corresponds to input means of the invention, the calculation means  103  corresponds to altitude data calculation means, and the control portion  105  and the calculation portion  103  correspond to pressure data calculation means of the invention. 
     In the foregoing structure, the operation of this embodiment will be described with reference to FIGS. 2,  3  and  4 . Incidentally, although the wristwatch with the altitude measurement function of this embodiment performs normal altitude measurement processing to measure and display the altitude where the apparatus itself is positioned, since this normal altitude measurement processing is the same as the foregoing conventional normal altitude measurement processing, the description is omitted. 
     First, threshold setting processing for setting pressure data corresponding to a designated altitude as a threshold will be described. In the case where there occurs an input of instructions to set a self-positioned altitude as a threshold, or an input for setting a threshold by a user&#39;s direct designation of an altitude, the threshold setting processing is started. FIG. 2 is a flowchart showing the flow of the threshold setting processing in the wristwatch with the altitude measurement function of the embodiment. In the threshold setting processing in the wristwatch with the altitude measurement function of the embodiment, first, the control portion  105  judges whether there occurred an input of instructions to set the self-positioned altitude as the threshold through the switch input portion  106  (step S 201 ). 
     In the case where there occurred the input of instructions to set the self-positioned altitude as the threshold, the control portion  105  drives the pressure sensor  101  through the measurement control portion  104  to sense an outside pressure (step S 202 ), and the A/D conversion portion  102  generates pressure data through A/D conversion of sensor output of the pressure sensor  101  (step S 203 ). On the other hand, in the case where it is judged, at step S 201 , that there did not occur the input of instructions to set the self-positioned altitude as the threshold, altitude data from the user is inputted through the switch input portion  106  (step S 205 ). The control portion  105  causes the calculation portion  103  to calculate pressure data corresponding to the altitude data desired by the user and inputted through the switch input portion  106 , that is, causes reverse operation for the pressure data (step S 206 ). The control portion  105  stores the pressure data generated in the A/D conversion portion  102  or the pressure data calculated in the calculation portion  103  as the threshold in the storage portion  108  (step S 204 ). 
     Next, altitude detection processing for detecting the designated altitude will be described. In the case where there occurs an input of instructions to start the altitude detection processing through the switch input portion  106 , the altitude detection processing is started. FIG. 3 is a flowchart showing the flow of the altitude detection processing in the wristwatch with the altitude measurement function of this embodiment. In the altitude detection processing of this embodiment, first, the control portion  105  drives the pressure sensor  101  to sense an outside pressure (step S 301 ), and the A/D conversion portion  102  makes A/D conversion of sensor output of the pressure sensor  101  to generate pressure data (step S 302 ). The control portion  105  inputs the pressure data generated in the A/D conversion portion  102  and causes the storage portion  108  to store it (step S 303 ). Here, calculation of altitude data taking a long time and display of a pressure and altitude are omitted. 
     Next, the control portion  105  compares the pressure data generated in the A/D conversion portion  102  with the pressure data stored in the storage portion  108  as the threshold, and judges whether the pressure data generated in the A/D conversion portion  102  exceeds the pressure data stored in the storage portion  108  as the threshold, that is, the difference between the pressure data generated in the A/D conversion portion  102  and the pressure data stored in the storage portion  108  as the threshold is changed from a positive to a negative or from a negative to a positive (S 304 ). In the case where the pressure data generated in the A/D conversion portion  102  does not exceed the pressure data stored in the storage portion  108  as the threshold, the processing returns to step S 301 , and in the case where the pressure data generated in the A/D conversion portion  102  exceeds the pressure data stored in the storage portion  108  as the threshold, it is judged that the designated altitude is detected and the processing is ended. 
     Here, in order to indicate the speed of change in the altitude, in addition to the designated altitude, the change of a constant interval in the altitude may detected, and every time of detection of the change of the constant interval in the altitude, an alarm may be given. 
     Next, altitude data confirmation processing for confirming altitude data during the altitude detection processing after the altitude detection processing will be described. FIG. 4 is a flowchart showing the flow of the altitude data confirmation processing of this embodiment. In the altitude data confirmation processing, the control portion  105  reads out the pressure data stored at the altitude detection processing in the storage portion  108  (step S 401 ), causes the calculation portion  103  to calculate altitude data corresponding to the read out pressure data (step S 402 ), and inputs the altitude data calculated in the calculation portion  103  to display the altitude through the display portion  107  (step S 403 ). 
     As described above, according to the portable pressure measuring apparatus of this embodiment, the pressure data corresponding to the designated altitude is stored, the stored pressure data is compared with the pressure data corresponding to the outside pressure, and the designated altitude is detected. That is, in the altitude detection processing, since calculation of altitude data which occupies a large part of a time taken in the conventional detection processing of the altitude is omitted, a time resolution of altitude detection, that is, a time interval (measurement frequency) in which the steps from step S 301  to step S 304  are repeated is shortened, and suitable altitude detection can be made even in the case where it is used for a use in which the altitude changes at a high speed, for example, gliding on skis skydiving, or the like, which requires a time resolution of about 100 ms to 10 ms. 
     Besides, also in the case where normal altitude detection is performed, by using this apparatus, even if operation processing capacity is small, altitude detection can be made. Further, the pressure data generated in the altitude detection processing is stored, and the altitude data is calculated from the stored pressure data after the end of the altitude detection processing, so that the altitude data during the altitude detection processing can be confirmed. Incidentally, instead of the altitude detection, application can also be made to the case where the depth of water is detected. 
     As described above, the portable pressure measuring apparatus of the invention stores pressure data corresponding to a designated altitude, generates pressure data corresponding to an outside pressure, and compares the generated pressure data with the stored pressure data to detect the designated altitude, so that calculation of altitude data can be omitted in the processing of detecting the designated altitude, a time delay in altitude detection can be made small, and suitable altitude detection can be made. 
     Besides, the portable pressure measuring apparatus of the invention calculates and stores pressure data corresponding to an inputted designated altitude, generates pressure data corresponding to an outside pressure, and compares the generated pressure data with the stored pressure data to detect the designated altitude, so that the designated altitude to be detected can be inputted as it is without the pressure data corresponding to the designated altitude calculated by the user, and a load for the user can be reduced, and further, calculation of altitude data in the processing of detecting the designated altitude can be omitted, a time delay in the altitude detection can be made small, and suitable altitude detection can be made. 
     Besides, the portable pressure measuring apparatus of the invention inputs an instruction to set an altitude where the apparatus itself is positioned as a designated altitude, and stores generated pressure data as pressure data corresponding to the designated altitude, so that the user can set an altitude at a desired position as the designated altitude. 
     Besides, the portable pressure measuring apparatus of the invention stores generated pressure data, and calculates altitude data on the basis of the stored pressure data, so that altitude data during altitude detection processing can be confirmed after the altitude detection processing.