JP2014130735A - Power supply switch circuit, and battery drive type device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress power consumption of a battery to save a power, and to put off a replacement timing or a charging timing of the battery.SOLUTION: A power supply switch circuit comprises: a mechanical switch part having an operation part whose contact is turned on when a pressing force is added and turned off when the pressing force is lost, and connecting/disconnecting a power supply line to a function part having a function operating by a power supplied from a battery, in response to the on/off control of the contact; an electronic switch part connected with the power supply line in parallel to the mechanical switch, and connecting/disconnecting the power supply line by the control from the function part; and a grounding part grounding the power supply line in the case that a preset condition of voltage reduction of the power supply line or condition of delay time is satisfied after the function part supplied with the power from the battery by the turning-on of the mechanical switch controls the electronic switch to operate while maintaining the connection of the power supply line, and then controls the electronic switch to disconnect the power supply line.

Description

  The present invention relates to a power switch circuit and a battery-powered device.

  Devices driven by a battery, such as an IC card with a display function, are forced to replace or charge the battery due to power consumption in an internal circuit. A battery used for an IC card with a display function is small in size and has a small capacity and needs to be replaced or charged in a short period of time.

  In a conventional IC card operated by a battery, for example, a capacitor and a transistor switch are connected to a power supply line from the battery to the control unit, and when the operation is turned off, the transistor switch is turned on to charge the capacitor. A power switch circuit is installed that allows the ground (GND) to escape. In this power switch circuit, since the power line becomes 0 V by the operation of the transistor switch during the OFF operation, the time for the through current to flow can be shortened.

Japanese Patent Laid-Open No. 01-54520

  However, in the above-described conventional power switch circuit, although the potential is electrically changed by the ON / OFF operation of the transistor switch, the circuit wiring itself from the battery to the control unit is connected, so the power supply is completely shut down as a whole system. There is a problem that the power stored in the battery leaks to the circuit and is wasted.

  SUMMARY OF THE INVENTION The present invention has been made to solve such a problem. A power switch circuit and a battery-driven device capable of saving power by suppressing power consumption of a battery and extending the replacement time or charging time of the battery are provided. The purpose is to provide.

  In order to solve the above-described problem, the power switch circuit according to one embodiment of the present invention includes an operation unit in which a contact is turned on when a pressing force is applied, and the contact is turned off when the pressing force disappears, and is supplied from a battery. A mechanical switch unit that connects / disconnects a power line to a functional unit having a function operated by a power source that is operated according to ON / OFF of the contact, and is connected in parallel with the mechanical switch unit, The electronic switch unit for connecting / disconnecting the power line by the control of the electronic control unit and the functional unit to which the mechanical switch is turned on and the power is supplied from the battery control the electronic switch to control the power line. After operating with the connection maintained, the electronic switch is controlled to disconnect the power supply line, and then a preset voltage drop condition or delay time condition is applied to the power supply line. Characterized by comprising a ground portion for grounding the power source line of said functional unit side when Tasa.

  The battery-driven device according to one embodiment of the present invention includes a functional unit having a function of operating by a power source supplied from a battery, and a contact is turned on when a pressing force is applied, and the contact is turned off when the pressing force disappears. A mechanical switch unit for connecting / disconnecting a power line from the battery to the functional unit according to ON / OFF of the contact, and a parallel connection with the mechanical switch unit, and the functional unit An electronic switch unit for connecting / disconnecting the power supply line under control from the control unit, and a condition for a voltage drop or delay time set in advance after the power supply line is disconnected by the electronic switch unit. And a grounding part for grounding the power supply line.

  In the present invention, a mechanical switch unit for connecting / disconnecting the power line from the battery to the functional unit according to ON / OFF of the contacts, and an electronic device for connecting / disconnecting the power line by the control from the mechanical switch and the functional unit When the functional unit ends its operation after the mechanical switch unit is connected to the power line in parallel and turned on by the mechanical switch unit borrower and the functional unit is activated by power supply, the control signal from the functional unit The electronic switch is turned off, and the power line to the functional unit is reliably disconnected from the battery by the electronic switch. As a result, power stored in the battery is prevented from leaking into the circuit and being wasted.

  Thereafter, the grounding unit grounds the power supply line when a preset voltage drop condition or delay time condition is satisfied.

  Capacitance components (charge or voltage) are accumulated in the power supply line where the power supply is stopped. Normally, the capacitance component (charge or voltage) gradually decreases, but the ground portion has this charge ( (Voltage) level is monitored (detected) and the power supply line is grounded and reset before the operation of the function unit becomes unstable near the minimum operating voltage. The operation of each circuit can be completely shut off.

  According to the present invention, it is possible to save power by suppressing the power consumption of the battery, and to extend the replacement time or charging time of the battery.

It is a figure which shows the structure of the IC card of 1st Embodiment. It is a figure which shows the circuit structure of the electronic switch circuit and reset circuit of the IC card of FIG. FIG. 3 is a diagram illustrating a first circuit configuration example of the reset circuit of FIG. 2. FIG. 3 is a diagram illustrating a second circuit configuration example of the reset circuit in FIG. 2. It is a figure which shows the structure of the IC card of 2nd Embodiment. It is a figure which shows the structure of the IC card of 3rd Embodiment.

  Hereinafter, an IC card according to an embodiment of the power switch circuit and the battery-driven device of the present invention will be described in detail with reference to the drawings. 1 is a diagram showing a configuration of an IC card according to the first embodiment, FIG. 2 is a diagram showing a circuit configuration of an electronic switch circuit and a reset circuit of the IC card in FIG. 1, and FIG. 3 is a first diagram of the reset circuit in FIG. It is a figure which shows the circuit structural example. FIG. 4 is a diagram showing a second circuit configuration example of the reset circuit of FIG.

  As shown in FIG. 1, the IC card of the first embodiment turns on (connects or turns on) a thin battery 1 such as a button battery and a power supply voltage 2 (hereinafter referred to as “BAT_VDD2”) from the battery 1. ) / SW (disconnect or cut) push switch SW3 which is a mechanical switch unit, and includes a MOS transistor (MOS Tr) or a MOS FET connected to the power line (BAT_VDD2 line) in parallel with push SW3. An electronic switch circuit 4 that is an electronic switch unit, a CPU 6, an electronic display panel 7 as a display device, an antenna 8, an information transfer IC 9, and the like; the push SW 3 and the electronic switch circuit 4 and the functional unit 10; And a reset circuit 5 connected between the two.

  The battery 1 is a small and thin detachable battery such as a button battery or a lithium ion battery. In addition, if the battery 1 is a rechargeable battery, it may not be detachable. The battery 1 supplies, for example, BAT_VDD2 such as DC 3V to the functional unit 10 through a circuit inside the card.

  The push SW 3 has a button as an operation unit that applies a pressing force to turn on the contact, and turns off the contact when the pressing force disappears. The push SW 3 is turned on / off when the button is operated by the user. While the button is pressed by the user, it is turned ON (circuit is connected), and when the button is released, it is turned OFF (circuit is disconnected).

  That is, the push SW 3 connects / disconnects the BAT_VDD 2 line to the functional unit 10 having a function operated by the BAT_VDD 2 supplied from the battery 1 according to ON / OFF of the contact. The push SW 3 completely cuts off the power supply to the function unit 10 when the button is not operated.

  The electronic switch circuit 4 turns on (connects or turns on) or turns off (cuts or turns off) the line BAT_VDD2 in response to a switch control signal (hereinafter referred to as “SW_Cont”) from the CPU 6.

  When the push SW3 is not pushed and the SW_Cont from the CPU 6 is Lo (when not inputted), the electronic switch circuit 4 is turned off, and the power supply from the BAT_VDD2 line to the function unit 10 is completely cut.

  The CPU 6 of the functional unit 10 outputs a control signal instructing connection to the electronic switch circuit 4 in accordance with a program activated by the power supplied from the battery 1, and a control signal instructing disconnection when the processing of the program ends. Is a control unit that outputs to the electronic switch circuit 4.

  The CPU 6 operates in response to the input of BAT_VDD2, a program stored in a memory (not shown) inside the unit is activated, and the respective units (electronic switch circuit 4, electronic display panel 7, and information exchange IC 9) in the card are activated. Perform control action.

  The CPU 6 stores the information received by the information exchange IC 9 in the memory and displays it on the electronic display panel 7. The CPU 6 sends the information stored in the memory to an external device through the information exchange IC 9.

  The electronic display panel 7 is, for example, an LCD panel, an EL panel, and the like. The electronic display panel 7 operates by inputting BAT_VDD2, and displays characters and characters according to a display control signal from the CPU 6.

  The information transmission / reception IC 9 is, for example, an NFC chip (an IC chip for short-range wireless communication) or the like, operates by inputting BAT_VDD2, and performs short-range wireless communication with other short-range wireless devices via the antenna 8 to receive information. Give and receive.

  As shown in FIG. 2, the electronic switch circuit 4 includes a control / bias circuit 20 and a high-side switch 29.

  The control / bias circuit 20 includes resistance elements 22, 23, and 25 and a semiconductor switch element such as an N-type MOS Tr24.

  The resistance element 22 is connected to the switch control signal input terminal 21 and the gate of the N-type MOS TR 24. The resistance element 23 is connected to the ground (hereinafter referred to as “GND”) and the gate of the N-type MOS TR 24. The resistance element 25 is connected to the line BAT_VDD2 and the drain of the N-type MOS Tr24. The source of the N-type MOS Tr24 is connected (grounded) to GND.

  The high side switch 29 has, for example, a P-type MOS Tr26. The gate of the P-type MOS Tr26 is connected to the drain of the N-type MOS Tr24. The source of the P-type MOS TR26 is connected to the BAT_VDD2 line. The drain of the P-type MOS Tr 26 is connected to the output terminal 30 to the function unit 10.

  These N-type MOS Tr24 and P-type MOS Tr26 are both small-signal MOS type (enhancement type) in order to suppress leakage current and operating current consumption.

  The resistance values of the resistance elements 22, 23, 25, etc. of the control / bias circuit 20 are set so that a bias current of about 1 μA to several μA flows in accordance with the semiconductor switch element (MOS Tr or MOS FET) to be used. .

  The reset circuit 5 is connected between the output terminal 30 and GND. The reset circuit 5 includes a comparison switch circuit 28 and a resistance element 27. The resistance element 27 is connected to the drain of the P-type MOS Tr 26 and the comparison switch circuit 28.

  The reset circuit 5 monitors the voltage level of the BAT_VDD2 line after the CPU 6 is operated, so that the reset circuit 5 is turned on when the voltage level between VDD and GND drops to a predetermined threshold, and the BAT_VDD2 line to the CPU 6 is connected to the GND. To ground.

  That is, after the BAT_VDD2 line is cut by the electronic switch circuit 4, the reset circuit 5 functions as a grounding unit that grounds the BAT_VDD2 line when a preset voltage drop condition of the BAT_VDD2 line is satisfied.

  More specifically, in the reset circuit 5, the CPU 6 of the functional unit 10 to which power is supplied from the battery 1 when the push SW3 is turned on and the line BAT_VDD2 is connected controls the electronic switch circuit 4 to control the BAT_VDD2 After operating while maintaining the line connection, the electronic switch circuit 4 is controlled to disconnect the BAT_VDD2 line, and when the preset condition for the voltage drop of the BAT_VDD2 line is satisfied, the function unit 10 side The BAT_VDD2 line is grounded.

  The condition for the voltage drop of the BAT_VDD switch 2 line is whether or not the voltage value of the BAT_VDD2 line has reached a threshold set to a value higher than the minimum operating voltage of the functional unit 10.

  For example, when the delay time condition is satisfied in addition to the voltage drop condition, the BAT_VDD2 line may be grounded. In this case, the condition of the delay time is whether or not the voltage value of the BAT_VDD2 line has reached a threshold set to a value shorter than the time required to reach the minimum operating voltage of the functional unit 10 after the BAT_VDD2 force line is cut. It is.

  The comparison switch circuit 28 has a voltage level monitoring terminal 28a and two input / output terminals 28b and 28c.

  The comparison switch circuit 28 monitors the voltage level of the drain (BAT_VDD2 line) of the P-type MOS Tr 26 with the monitoring terminal 28a, and when the voltage level of the monitoring terminal 28a is equal to or lower than a preset threshold voltage, The output terminals 28b and 28c are short-circuited.

  In this example, the comparison switch circuit 28 shorts the line from the drain of the P-type MOS Tr 26 to the output terminal 30 through the resistance element 27 to GND. The threshold voltage is set to a value higher than the lower limit value (minimum operating voltage) of the power supply voltage for which the operation of the CPU 6 is guaranteed.

  The comparison switch circuit 28 shorts between the input / output terminals 28b and 28c (in this example, the line BAT_VDD2 -GND) by detecting a threshold voltage higher than the operating voltage of the CPU 6.

  If the BAT_VDD during the ON operation is 3V, for example, and the minimum operating voltage of the CPU 6 is 1.5V, the threshold voltage is about 2.0V.

  As shown in FIG. 3, the comparison switch circuit 28 includes a reference voltage generator 42, a comparison circuit (comparator) 43, a switching buffer 44, and an electronic switch 45.

  In this example, the comparison circuit (comparator) 43 is a logic circuit that monitors the voltage level of the monitoring terminal 28a and outputs a switch control signal when the condition is satisfied.

  When the voltage level of the monitoring terminal 28a becomes lower than the reference voltage level generated by the reference voltage generator 42, the comparison circuit (comparator) 43 changes the switch control signal from LO to HI (outputs HI) and performs switching. The electronic switch 45 is turned on through the buffer 44. As a result, the line from the drain of the P-type MOS Tr 26 to the output terminal 30 is grounded to the GND through the resistance element 27.

Next, the operation of the IC card according to the first embodiment will be described.
In the IC card of the first embodiment, when the push SW3 is pushed by the user, the push SW3 turns on (connects) the line BAT_VDD2 and the line to the function unit 10.

  Then, BAT_VDD2 is supplied from the battery 1 to the functional unit 10 (the CPU 6, the electronic display panel 7, the information transfer IC 9, etc.) while the push SW3 is pressed.

  The CPU 6 starts a memory program and starts a control operation, and outputs SW_Cont (HI) to the SW_Cont input terminal 21 of the electronic switch circuit 4.

  In the electronic switch circuit 4, BAT_VDD continues to be supplied to the CPU 6 even after the N-type MOS Tr24 and the P-type MOS Tr26 are turned on by the input of SW_Cont (HI) and the push SW3 is turned off. The ON period is a period until all the processing of the intended function (such as displaying information received by the information exchange IC 9) is executed and the processing is completed.

  In the functional unit 10, the information exchange IC 9 receives information from other short-range wireless devices by supplying power and passes it to the CPU 6, and the CPU 6 displays the information delivered from the information exchange IC 9 on the electronic display panel 7 for a certain period of time.

  After the information is displayed on the electronic display panel 7 for a certain period of time, if there is no information to be displayed next, the CPU 6 starts a shutdown process (program end process).

  In this case, the CPU 6 sends SW_Cont (LO) to the SW_Cont input terminal 21 of the electronic switch circuit 4.

  In the electronic switch circuit 4, since the N-type MOS Tr24 and the P-type MOS Tr26 are sequentially turned off by the input of SW_Cont (LO) and the push SW3 is turned off, BAT_VDD is completely disconnected from the circuit. 1 power consumption is eliminated.

  Thereafter, the CPU 6 performs a program shutdown process. At this time, the capacity component (charge or voltage) accumulated in the disconnected BAT_VDD switch output line gradually decreases, but the level of this charge (voltage) is reset. The circuit 5 monitors (detects) and resets before the operation of the CPU 6 becomes unstable. That is, the BAT_VDD switch output line and GND are short-circuited (connected), and the voltage level of the BAT_VDD switch output line of the function unit 10 is set. Quickly down to GND level.

  As a result, even when a large capacitance component is attached to the output side, the functional unit 10 can be surely shifted to the OFF state without malfunctioning, and the timing of the OFF control operation of the high side switch 29 and the operation of the VDD-GND short circuit are shifted. As a result, the generation of the through current can be eliminated. From the above, it is possible to save labor without causing the IC card to malfunction, and the replacement time or charging time of the battery 1 can be delayed.

  As described above, according to the first embodiment, the mechanical switch (push SW3) and the electronic switch (electronic switch circuit 4) are provided in parallel, and when OFF, the CPU 6, the information transfer IC 9, the electronic display panel 7, etc. By completely cutting (cutting off) the power supply to the functional unit 10 including the battery capacity, wasteful outflow of the battery capacity during the switch operation can be suppressed, so that power consumption of the battery 1 can be suppressed and labor can be saved.

  In addition, after the functional unit 10 operates, the capacity component (voltage) accumulated in the circuit during the shutdown process (at the time of OFF operation) gradually decreases, and the voltage value of the capacity component (voltage) is the lowest operation of the CPU 6. When the threshold value is higher than the voltage, the reset circuit 5 shorts between the BAT_VDD switch output line and GND to instantaneously lower the capacitance component (voltage) to the GND level. That is, the operation of each circuit after the switch can be completely shut off by rapidly setting the CPU 6 to 0 V without giving any time for malfunction.

  As a result, it is possible to save power by suppressing power consumption of the battery 1 mounted on the IC card, and to extend the replacement time or charging time of the battery 1.

  The example of the comparison switch circuit 28 shown in FIG. 3 is an example in which the logic circuit is mainly configured, but other configurations can also be configured.

  That is, as shown in FIG. 4, the comparison switch circuit 28 mainly comprises a microcomputer 46 that is a comparison circuit in which digital and analog are mixed, and the electronic circuit is controlled by a control signal from a microcomputer 46 (hereinafter referred to as “microcomputer 46”). The switch 45 may be turned on / off.

  In this case, the microcomputer 46, which is a digital / analog mixed circuit, detects the comparison detection voltage value (digital value) set by the program, outputs an arbitrary control signal to the electronic switch 45 (analog), and turns on the electronic switch 45. / OFF.

  In the configuration of FIG. 4, the switching buffer 44, which is one of the components of the logic block shown in FIG. 3, is not necessary, and the circuit configuration can be simplified.

Next, a second embodiment will be described with reference to FIG.
As shown in FIG. 5, in the IC card of the second embodiment, the function unit 10 operates under the control of the CPU 6, and the sensor 11 that detects the device itself or the external state of the device, and the sensor 11 detects the IC card. And an electronic display panel 7 for displaying the recorded information.

  That is, the second embodiment is an example in which a sensor 11 that detects, for example, light, vibration, position, movement, or the like is arranged as an element of the functional unit 10 instead of the information exchange IC 9 shown in FIG. Specifically, for example, an optical sensor, a count counter, a pedometer (registered trademark), an accelerometer, a GPS receiver, or the like is used as the sensor 11.

  In the case of the second embodiment, when the push SW3 is pushed by the user, the contact is brought into contact (ON) in the push SW3, and the line BAT_VDD2 and the line to the functional unit 10 are connected.

  Then, BAT_VDD2 is supplied from the battery 1 to the functional unit 10 (the CPU 6, the electronic display panel 7, the sensor 11, etc.) while the push SW3 is being pressed.

  With the supply of BAT_VDD2, the CPU 6 starts a memory program and starts a control operation, and outputs SW_Cont (HI) to the SW_Cont input terminal 21 of the electronic switch circuit 4. Thereby, the electronic switch circuit 4 is turned ON.

  The sensor 11 to which power is supplied detects information and passes the detected information to the CPU 6. The CPU 6 sends the passed information to the electronic display panel 7 and the information is displayed on the electronic display panel 7.

  After displaying the information on the electronic display panel 7 for a certain period of time, the CPU 6 outputs SW_Cont (LO) to the electronic switch circuit 4 and starts the entire shutdown process when the additional action from the sensor 11 is not within the specified time. .

  On the other hand, in the electronic switch circuit 4, the internal switch is turned OFF by the input of SW_Cont (LO), the BAT_VDD line from the battery 1 to the functional unit 10 is disconnected, and the supply of BAT_VDD2 is stopped.

  After the power supply is stopped, the charge (voltage) accumulated in the capacitance component of the BAT_VDD line gradually decreases. When the reset circuit 5 that has monitored this charge (voltage) detects that the threshold voltage has been reached, The reset circuit 5 connects the BAT_VDD line and GND to quickly lower the level of the BAT_VDD line, which is the power input line of the function unit 10, to the GND level, so that the CPU 6 of the function unit 10 becomes unstable in operation. It is possible to shift to the OFF state without fail.

  As described above, according to the second embodiment, the same effect as that of the first embodiment can be obtained for the IC card with the sensor 11. As a result, an IC card equipped with functions such as an optical sensor, a count counter, a pedometer (registered trademark), an accelerometer, and a GPS receiver can be provided as a battery-driven device.

Next, a third embodiment will be described with reference to FIG.
As shown in FIG. 6, in the IC card of the third embodiment, the function unit 10 has a keyboard 12 as an input device to which information is input by a key operation, and an electronic display that displays information input from the keyboard 12 Panel 7.

  That is, the third embodiment is an example in which an input device such as a keyboard 12 or a numeric keypad is arranged as an element of the functional unit 10 instead of the information exchange IC 9 shown in FIG.

  In the case of the third embodiment, when the push SW3 is pushed by the user, the contact is brought into contact (ON) in the push SW3, and the line BAT_VDD2 and the line to the function unit 10 are connected.

  Then, BAT_VDD2 is supplied from the battery 1 to the function unit 10 (CPU 6, electronic display panel 7, keyboard 12, etc.) while the push SW3 is being pressed.

  With the supply of BAT_VDD2, the CPU 6 starts a memory program and starts a control operation, and outputs SW_Cont (HI) to the SW_Cont input terminal 21 of the electronic switch circuit 4. Thereby, the electronic switch circuit 4 is turned ON.

  The keyboard 12 to which power is supplied becomes capable of key input, and passes information input by the user through key operations to the CPU 6. The CPU 6 sends the passed information to the electronic display panel 7 and the information is displayed on the electronic display panel 7.

  After the information is displayed on the electronic display panel 7 for a certain period of time, if there is no additional action for the keyboard 12 within the specified time, the CPU 6 outputs SW_Cont (LO) to the electronic switch circuit 4 and starts the entire shutdown process. .

  On the other hand, in the electronic switch circuit 4, the internal switch is turned OFF by the input of SW_Cont (LO), the BAT_VDD line from the battery 1 to the functional unit 10 is disconnected, and the supply of BAT_VDD2 is stopped.

  After the power supply is stopped, the charge (voltage) accumulated in the capacitance component of the BAT_VDD line gradually decreases. When the reset circuit 5 that has monitored this charge (voltage) detects that the threshold voltage has been reached, The reset circuit 5 connects the BAT_VDD line and GND to quickly lower the level of the BAT_VDD line, which is the power input line of the function unit 10, to the GND level, so that the CPU 6 of the function unit 10 becomes unstable in operation. It is possible to shift to the OFF state without fail.

  As described above, according to the third embodiment, the same effect as that of the first embodiment can be obtained for the IC card with the keyboard 12. As a result, an IC card equipped with an input device such as a keyboard 12 or a numeric keypad can be provided as a battery-driven device.

  The invention of the present application is not limited to the above-described embodiment. In the implementation stage, the constituent elements are modified without departing from the scope of the invention (partial deletion of elements, change of combination of elements between the embodiments, etc.). May be.

  Further, each component described in the above embodiment may be realized by a program installed in a storage such as a memory of a computer, and the program is stored in a computer-readable electronic medium: electronic media, The computer may realize the functions of the present invention by causing a computer to read a program from an electronic medium.

  Examples of the electronic medium include a recording medium such as a CD-ROM, a flash memory, and a removable media. Further, the configuration may be realized by distributing and storing components in different computers connected via a network, and communicating between computers in which the components are functioning.

1 ... Battery 2 ... Power supply voltage (BAT_VDD)
3 ... Push SW
4 ... Electronic switch circuit 5 ... Reset circuit 6 ... CPU
7 ... Electronic display panel 8 ... Antenna 9 ... Information transfer IC
DESCRIPTION OF SYMBOLS 10 ... Functional part 11 ... Sensor 12 ... Keyboard 20 ... Control and bias circuit 21 ... Input terminal 22, 23, 25, 27 ... Resistance element 28 ... Comparison switch circuit 28a ... Monitoring terminal 28b, 28c ... Input / output terminal 29 ... High side Switch 30 ... Output terminal 42 ... Reference voltage generator 44 ... Switching buffer 45 ... Electronic switch 46 ... Microcomputer

Claims (9)

The contact is turned ON when a pressing force is applied, and the contact is turned OFF when the pressing force disappears, and a power line to a functional unit having a function operated by a power source supplied from a battery is connected to the contact. A mechanical switch that connects / disconnects with ON / OFF;
An electronic switch unit connected to the power supply line in parallel with the mechanical switch, and connected / disconnected to the power supply line by control from the function unit;
After the mechanical switch is turned on and the function unit supplied with power from the battery operates while maintaining the connection of the power line by controlling the electronic switch, the functional unit controls the electronic switch. A grounding unit for grounding the power supply line on the functional unit side when a preset voltage drop condition or delay time condition is satisfied after the power supply line is disconnected. A featured power switch circuit. The voltage drop condition of the power line is
2. The power switch circuit according to claim 1, wherein the voltage value of the power line has reached a threshold set to a value higher than a minimum operating voltage of the functional unit. The delay time condition is
2. The power switch circuit according to claim 1, wherein whether or not the voltage value of the power supply line has reached a threshold set to a value shorter than a time required to reach a minimum operating voltage of the functional unit after the power supply line is disconnected. . The electronic switch unit is
4. The power switch circuit according to claim 1, wherein the power switch circuit is a MOS type semiconductor switch. A functional unit having a function of operating with power supplied from a battery;
The contact is turned on when a pressing force is applied, and the contact is turned off when the pressing force disappears, and the power line from the battery to the functional unit is connected / disconnected as the contact is turned on / off. A mechanical switch,
An electronic switch unit that is connected in parallel with the mechanical switch unit, and that connects / disconnects the power supply line by control from the function unit;
After the mechanical switch is turned on and the function unit supplied with power from the battery operates while maintaining the connection of the power line by controlling the electronic switch, the functional unit controls the electronic switch. A grounding unit configured to ground the power supply line on the functional unit side when a preset voltage drop condition or delay time condition is satisfied after the power supply line is disconnected. Battery powered device characterized. The functional unit is
A control unit that outputs a control signal instructing connection to the electronic switch unit in accordance with a program started by a power source supplied from the battery, and that outputs a control signal instructing disconnection when the processing of the program ends. The battery-powered device according to claim 5, comprising: The functional unit is
The battery-driven type according to claim 6, further comprising: an IC chip for short-range wireless communication that is controlled and operated by the control unit; and a display device that displays information obtained by wireless communication using the IC chip. apparatus. The functional unit is
7. The apparatus according to claim 6, further comprising: a sensor that operates under the control of the control unit and detects a state of the apparatus itself or the outside of the apparatus; and a display device that displays information detected by the sensor. Battery powered device. The functional unit is
The battery-powered device according to claim 5, further comprising: an input device to which information is input by a key operation; and a display device that displays information input from the input device.

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