JP2008253279A - Activity meter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an activity meter capable of preventing data from being eliminated by instantaneous shut-off of power supply. <P>SOLUTION: A capacitor C1 connected between a power supply terminal V<SB>DD</SB>of an SRAM 5 and a grand end GND is charged while the power supply is normally fed from a battery 6. If the power supply is instantaneously shut off, the electric charge charged in the capacitor C1 is discharged to be fed between the power terminal V<SB>DD</SB>of the SRAM 5 and the grand end GND, and elimination of the data stored in the SRAM 5 before the power supply is recoverd can be prevented. Further, feeding of the electric charge discharged from the capacitor C1 to a microcomputer 2 can be prevented by a diode D inserted between the capacitor C1 and the battery 6. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an activity meter that measures an activity amount of a measurement subject.

  2. Description of the Related Art Conventionally, as an activity meter for measuring an activity amount of a measurement subject, for example, there is one disclosed in Patent Document 1.

This type of activity meter includes, for example, an acceleration sensor that can detect acceleration in three axes in a three-dimensional orthogonal coordinate system, a memory that stores a detection value of the acceleration sensor, and a detection value ( A microcomputer (hereinafter, abbreviated as a microcomputer) that performs processing for calculating the activity amount of the measured person from the acceleration data), a display device (for example, a liquid crystal display) that displays the activity amount calculated by the microcomputer, A non-volatile semiconductor memory (for example, EEPROM) that stores software (program) for causing the microcomputer to execute the above arithmetic processing and the like, and a battery for supplying power, and these components are portable. Is housed in a housing. Note that a rewritable semiconductor memory (for example, SRAM <Static Random Access Memory>) that does not require an operation for storing and holding is used as a memory for storing a detection value or the like of the acceleration sensor.
JP 2006-204446 A

  By the way, when the person carrying the activity meter as described above performs intense exercise, or when the activity meter is inadvertently dropped, the battery moves in the housing, so that it takes a very short time. There is a possibility that the power supply will stop. When such a power supply interruption occurs, there is a problem that data stored in a memory (SRAM) that requires power supply for storing data is lost.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an activity meter that can prevent data loss due to a momentary power interruption.

  In order to achieve the above object, the present invention is an activity meter that is carried by a person to be measured and measures the amount of activity of the person to be measured, the sensor for detecting the body movement of the person to be measured, and the sensor A calculation circuit for calculating the activity amount of the person to be measured from the detected value, a rewritable volatile semiconductor memory for storing the detection value and data of the activity amount calculated by the calculation circuit, a battery for power supply, The semiconductor memory has a pair of power supply terminals to which a battery voltage is applied for memory retention, and a capacitor charged by the battery via a rectifying element is connected between the power supply terminals. Features.

  According to the present invention, the capacitor charged by the battery is connected between the pair of power supply terminals of the semiconductor memory for storing data via the rectifying element, so that the capacitor is charged even when a power interruption occurs. The stored charge of the semiconductor memory can be retained using the stored charge, and as a result, data loss due to a momentary power interruption can be prevented.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the activity meter according to the present embodiment includes an acceleration sensor 1 that can detect acceleration in three axes in a three-dimensional orthogonal coordinate system, and a measured value (acceleration data) from the acceleration sensor 1. An arithmetic circuit (microcomputer) 2 that performs processing for calculating the amount of activity, a display unit 3 that has a display device such as a liquid crystal display and displays the amount of activity processed by the microcomputer 2, and for calculating the amount of activity Non-volatile semiconductor memory (EEPROM) 4 that stores various data (such as age and weight of the person to be measured), key commands, authentication information, and the like described later, and detected values and activity amounts of the acceleration sensor 1 A rewritable volatile semiconductor memory (SRAM) 5 for storing data, a battery 6 for supplying power, an input operation unit 7 including a push button switch, and an external device (for example, a personal computer) And an external interface (I / F) unit 8 for exchanging data with other), and these components are housed in a portable size of the housing (not shown).

  An EEPROM 4, SRAM 5, and I / O port 9 are connected to the microcomputer 2 via a bus 10, and an acceleration sensor 1, a display unit 3, an input operation unit 7, and an external I / F unit 8 are connected to the I / O port 9. The above arithmetic processing and the like are executed by executing a program stored in a built-in nonvolatile memory. The detection value (acceleration data) output from the acceleration sensor 1 is taken in from the I / O port 9 via the bus 10 and stored in the SRAM 5 under the control of the microcomputer 2. The microcomputer 2 calculates the activity amount of the measurement subject based on the detected value (acceleration data) stored in the SRAM 5, and stores the activity amount data obtained by the calculation in the SRAM 5 through the bus 10, and the input operation unit 7. When the operation input of the push button switch provided in the terminal is taken in from the I / O port 9 via the bus 10, the activity amount data stored in the SRAM 5 is read out and sent from the I / O port 9 to the display unit 3, and the display unit In 3, the amount of activity is displayed. Here, the activity amount measured by the activity meter of the present embodiment is obtained as a ratio index (METs <metabolic equivalents>) corresponding to the exercise intensity at rest from the acceleration value detected by the acceleration sensor 1. It is exercise intensity. However, since the method for calculating the exercise intensity is not the gist of the present invention and is also well known in the art, description thereof will be omitted.

  Next, the structure which becomes the summary of this invention is demonstrated.

  The activity meter of the present embodiment configured as described above is carried by a person to be measured and measures the amount of activity of the person to be measured. However, as described in the related art, the person to be measured performs intense exercise. When it is performed or when the activity meter is inadvertently dropped, there is a possibility that the power supply to the SRAM 5 may be interrupted due to the movement of the battery 6 in the housing. Since the SRAM 5 requires a power supply for storage, there is a possibility that the stored detection value of the acceleration sensor 1 and the data of the activity amount may be lost if the power interruption as described above occurs.

Therefore, in this embodiment, a capacitor C1 having a relatively large capacity is connected between the power supply terminal V _{DD of the} SRAM 5 and the ground terminal GND, and the cathode of the diode D is connected to one end of the capacitor C1 connected to the power supply terminal V _DD. In addition, the anode of the diode D is connected to the positive electrode of the battery 6. That is, the capacitor C1 connected between the power supply terminal V _{DD of the} SRAM 5 and the ground terminal GND is charged while the power is normally supplied from the battery 6, and when the power supply is interrupted, the capacitor C1 The charge stored in the SRAM 5 is discharged and the power is supplied between the power supply terminal V _{DD of the} SRAM 5 and the ground terminal GND. Therefore, the data stored in the SRAM 5 is lost before the power supply is restored from the momentary power interruption. Can be prevented. Further, the diode D inserted between the capacitor C1 and the battery 6 can prevent the electric charge discharged from the capacitor C1 from being supplied to the microcomputer 2. In the present embodiment, a capacitor C2 serving as a backup power supply at the time of instantaneous power interruption is also connected between the power supply terminal V _CC of the microcomputer 2 and the ground terminal GND.

  By the way, in the active mass meter of this embodiment, the watchdog timer 11 is provided in case the microcomputer 2 goes into an infinite loop due to a program bug or the like, or the microcomputer 2 runs away due to the influence of external noise or the like. When the watchdog timer 11 counts up due to the runaway of the microcomputer 2, the data stored in the SRAM 5 (detection value and activity amount data) is saved in the EEPROM 4, and the microcomputer 2 is reset after writing a key command. The restarted microcomputer 2 accesses the EEPROM 4 and, if a key command is written, reads the data saved in the EEPROM 4 and continues the activity amount calculation process. Therefore, even when the microcomputer 2 runs away and is reset, the activity amount calculation process can be continued using the data before the runaway. However, it goes without saying that if no key command is written in the EEPROM 4, the microcomputer 2 starts the operation amount calculation process from the beginning.

  Here, the activity meter of the present embodiment includes the external I / F unit 8. For example, the detected values and activity data stored in the SRAM 5 through the external I / F unit 8 are stored in the external device ( For example, it can be stored in a personal computer) and stored or processed. However, since these data are information about the privacy of the person being measured (so-called personal information), it should be avoided that the data is disclosed to the person to be measured or a third party other than the person authorized by the person to be measured. Don't be. Therefore, authentication information (for example, a personal identification number) for authenticating the person to be measured or a person authorized by the person to be measured is stored in the EEPROM 4, and from an external device connected to the external I / F unit 8. When accessed, the microcomputer 2 issues an authentication request to the external device, and the access is permitted only when the authentication information sent from the external device matches the authentication information stored in the EEPROM 4. That's fine.

It is a block diagram which shows embodiment of this invention.

Explanation of symbols

1 Acceleration sensor 2 Microcomputer (arithmetic circuit)
5 SRAM (Rewritable volatile semiconductor memory)
6 Battery C1 Capacitor

Claims (1)

An activity meter that is carried by the subject and measures the amount of activity of the subject,
A sensor for detecting the body movement of the measurement subject, a calculation circuit for calculating the activity amount of the measurement subject from the detection value of the sensor, and a rewrite for storing the detection value and the activity amount data calculated by the calculation circuit It is equipped with possible volatile semiconductor memory and a battery for power supply,
The semiconductor memory has a pair of power supply terminals to which a battery voltage is applied for storage retention, and a capacitor charged by the battery via a rectifying element is connected between the power supply terminals. Activity meter.

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