JP2007157665A - Battery termination detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery termination detector composed by setting the variation of a battery voltage at a value in response to a use environment temperature; to provide a battery termination detection method; and to provide a program. <P>SOLUTION: At a reference environment temperature (25°C), when the variation of a drop voltage extracted through a coupling capacitor 16 reaches a difference Vb-Vdet between a bias voltage Vb generated by a bias resistor A, a thermistor TH having a resistance value depending on temperature, and a bias resistor B, and a voltage detection value Vdet of a voltage detector 19 reduced by the drop variation to be detected, a microcomputer 40 terminates supply of a power voltage to an apparatus by transmitting a signal to a power termination part 60. Since the resistance value of the thermistor TH is increased in the case of a low-temperature environment, the width of the detection variation Vb-Vdet of the drop voltage is increased, whereby a termination voltage in response to temperature can be detected even in the low-temperature environment. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

    The present invention relates to a battery end detection device such as an AA battery.

    In a personal device having a battery-driven semiconductor memory such as a digital camera, the battery state is generally observed by a sub-microcomputer, and the power on / off of the device is controlled. Further, the AA battery drive type model includes a power supply device having a circuit (power drop detection circuit 30) for detecting a voltage drop (change amount) of the battery, like the AA battery drive power supply device 300 shown in FIG. In some cases, control is performed to turn off power when a voltage drop occurs that suddenly falls below the quiescent voltage due to load fluctuation.

FIG. 6 is a diagram showing a conventional example of an AA battery drive power supply device, and a portion within a dotted line frame constitutes a conventional voltage drop detection circuit 30, where symbol 11 is an ideal voltage source. (EVCC 3.3) and bias resistor A provided between the ground, symbol 12 is a bias resistor B, symbol 16 is a coupling capacitor, symbol 19 is a voltage detector, and symbol Va is a point between the bias resistor A and the bias resistor B. The bias voltage given to j is shown.
At the reference ambient temperature (25 ° C.), the bias voltage Va is applied to the point j by the bias resistor A and the bias resistor B. The voltage drop detection value is set by the difference “Va−Vdet” between the bias voltage Va and the detection voltage Vdet that is lower by the amount of change desired to be detected by the voltage detector 19.
When the change amount of the drop voltage taken out via the coupling capacitor 16 reaches “Va-Vdet”, the voltage detector 19 detects it and sends a signal to a microcomputer (hereinafter referred to as “microcomputer”) 40. A power supply termination unit 60 including an LDO (Low Drop Out) 61 terminates the supply of power supply voltage to the personal device.

  On the other hand, when the operating temperature environment is low, the drop amount when the load fluctuates increases due to characteristic deterioration at low temperature, but the power drop detection circuit 30 sets the reference environment temperature (smaller than the drop amount at low temperature). ) Since the end detection is performed by the drop amount, there is a problem that the battery life at a low temperature is shortened.

  FIG. 7 is a diagram showing an example of a battery discharge curve of an AA battery. In FIG. 7, reference numeral 110 denotes a battery voltage at a reference environment temperature (+ 25 ° C.) when the X axis is time T and the Y axis is battery voltage V. A discharge curve indicating the transition of the battery voltage, and reference numeral 120 indicates a discharge curve indicating the transition of the battery voltage at a low temperature. The symbol Vk is the set value of the final voltage (the final voltage when the static load fluctuates) in the AA battery drive power supply apparatus 300 shown in FIG. 6, and the symbol P is the detected drop amount set at the reference environmental temperature (+ 25 ° C.). Symbol Q indicates a drop amount (Q = P) due to a voltage drop of a load fluctuation character at a low temperature.

  The discharge curves 110 and 120 are downward-sloping curves, and the battery voltage decreases due to discharge over time. In the case of the reference environmental temperature, when the battery voltage is close to the set value Vk of the end voltage, if a drop amount greater than the drop voltage change amount P set by the load fluctuation on the device side is detected, the voltage becomes the end voltage or lower. Therefore, the AA battery drive power supply device 300 stops the power supply to the personal device. On the other hand, when the temperature is low, the drop amount at the time of load change becomes large as shown by the discharge curve 120 due to the characteristic deterioration at low temperature, but the drop amount value is equal to the drop amount P set for the reference environment temperature. Sometimes stop detection is performed, and power supply to the personal device is stopped. In other words, even if the drop amount increases in a low temperature environment, the end detection is performed with the drop amount P set for the reference environment temperature. As a result, the end detection is performed at an early stage, and the battery life is shortened.

  Here, an end voltage for terminating the discharge from the lithium ion secondary battery is set according to the discharge characteristics of the lithium ion secondary battery, and the end voltage is controlled by changing the setting of the end voltage according to the use state of the lithium ion secondary battery. By providing a voltage control unit, even when the battery is used under low-temperature environments or has increased the number of times of charging / discharging, it is possible to discharge the battery by changing and setting the end voltage that terminates discharging from the battery cell according to the characteristics of the battery. There is a battery device that extends the length (for example, see Patent Document 1).

JP 2005-269708 A

  In the technique disclosed in Patent Document 1, even when a battery is used under a low-temperature environment or the number of times of charging / discharging is increased, an end voltage at which discharge from the battery cell is terminated is changed and set on the battery device side according to the characteristics of the battery. Therefore, the time during which discharge is possible can be extended.

  However, when the drop amount when the load fluctuates increases due to the deterioration of the battery voltage characteristics at low temperature, the drop voltage detected by the power drop detection circuit set at the reference environment temperature in the battery drive power supply device as shown in FIG. It does not give a specific solution for solving the problem that the end detection is performed with the change amount, for example, a solution method focusing on the drop amount (that is, the change amount of the battery voltage).

  It is an object of the present invention to provide a battery end detection device, a battery end detection method, and a program in which the amount of change in battery voltage becomes a value corresponding to the use environment temperature.

In order to solve the above-mentioned problem, according to the invention described in claim 1, a battery end detection device in a battery-powered power supply device, an allowable value setting means for setting a voltage drop detection value of a power supply according to temperature, a battery Resistance value control means for changing the resistance value of the bias resistance portion of the power supply voltage according to temperature, resistance value detection means for detecting the resistance value of the bias resistance portion after the change by the resistance value control means, and resistance value detection means There is provided a battery end detection device comprising power supply stop means for stopping supply of battery power when a detected resistance value reaches a voltage drop detection value.
As a result, the battery end detection device can change the voltage drop detection amount according to the temperature by controlling the resistance value of the bias resistor in the voltage drop detection device according to the operating temperature environment. Since the end voltage according to the characteristics can be detected, the battery life can be extended.

According to the second aspect of the present invention, the resistance value control means is a temperature-dependent resistance member whose resistance value changes depending on the temperature, and the bias resistance section includes a plurality of bias resistance members arranged in series and temperature-dependency. The battery end detection device according to claim 1, comprising a mold resistance member.
Accordingly, since a temperature-dependent resistance member whose resistance value varies depending on the temperature is added to the bias resistance portion, it is possible to detect the end according to the use environment temperature, and it is possible to extend the battery life in a low temperature environment.

According to a third aspect of the present invention, the temperature detection unit further detects the temperature, and the resistance value control unit connects the plurality of bias resistance members arranged in series in the bias resistance unit by the temperature detection unit. The battery end detection device according to claim 1, further comprising a changeover switch that switches in accordance with the detected temperature.
As a result, the battery end detection device can change the resistance value of the bias resistor in the voltage drop detection circuit by switching a plurality of changeover switches according to the operating temperature environment, and can set the voltage drop detection amount according to the temperature. Since the end voltage corresponding to the characteristics of the battery can be detected even in a low temperature environment, the battery life can be extended.

In the invention described in claim 4, there is further provided switch control means for performing on / off control of the changeover switch, and switch control information storage means for associating the on / off value of the switch with the temperature value measured by the temperature measuring means. The switch control means includes an on / off value of the switch corresponding to the temperature value measured by the temperature measurement means, and performs on / off control of the changeover switch by taking out from the switch control information storage means. A battery end detection device as described is provided.
Thereby, the resistance value control means can take out the switch control information storage means in accordance with the detected temperature value and perform the on / off control of the changeover switch.

According to a fifth aspect of the present invention, there is provided a battery end detection method for a battery-driven power supply apparatus, the step of setting a voltage drop detection value of the power supply according to the temperature, and the resistance value of the bias resistance portion of the battery power supply voltage A step of detecting the resistance value of the bias resistor after the change due to temperature, and stopping the supply of battery power when the detected resistance value reaches the set voltage drop detection value. And a battery end detection method comprising: a step.
As a result, the battery end detection device can control the resistance value of the bias resistor of the battery voltage according to the operating temperature environment and change the voltage drop detection amount according to the temperature. Since the corresponding end voltage can be detected, the battery life can be extended.

According to the sixth aspect of the present invention, the function of setting the voltage drop detection value of the power supply in accordance with the temperature in the computer of the battery-driven power supply device, and the resistance value of the summer bias resistor unit in the battery power supply is changed according to the temperature. And a function for terminating the supply of battery power when the resistance value of the bias resistor after the change due to temperature reaches a set voltage drop detection value.
As a result, the battery-driven power supply device can control the resistance value of the bias resistor of the battery voltage according to the operating temperature environment and change the voltage drop detection amount according to the temperature. Since the corresponding end voltage can be detected, the battery life can be extended.

  According to the present invention, the battery end detection device can change the voltage drop detection amount according to the temperature by controlling the resistance value of the bias resistor of the battery voltage according to the operating temperature environment. Since the end voltage according to the characteristics can be detected, the battery life can be extended.

<Embodiment 1>
The present embodiment is an example in which a thermistor TH is added to the bias resistor portion of the voltage drop detection circuit 30 in FIG. 6 to detect the end voltage corresponding to the temperature. The thermistor TH is usually a temperature-dependent resistor having a large temperature coefficient with a sintered semiconductor material as a component.

  FIG. 1 is a diagram showing an example of an AA battery drive power supply apparatus according to the first embodiment, and a portion within a dotted line frame constitutes a voltage drop detection circuit 10. In the voltage drop detection circuit 10, symbol 11 is a bias resistor A provided between an ideal voltage source (EVCC3.3) and ground, symbol 12 is a bias resistor B, symbol 16 is a coupling capacitor, and symbol 17 is a bias resistor A. Thermistor TH provided between the bias resistor B and the bias resistor B, symbol 19 indicates a voltage detector, and symbol Vb indicates a bias voltage applied to the point j by the bias resistor A, the thermistor TH and the bias resistor B.

At the reference ambient temperature (25 ° C.), the bias voltage Vb is applied to the point j by the bias resistor A, the thermistor TH whose resistance value depends on the temperature, and the bias resistor B. The voltage drop detection value is set by the difference “Vb−Vdet” between the bias voltage Vb and the voltage detection value Vdet that is lower by the drop change amount that the voltage detector 19 wants to detect.
When the change amount of the drop voltage taken out via the coupling capacitor 16 reaches “Vb−Vdet”, the voltage drop detection circuit 10 detects it and sends the change amount of the drop voltage to the microcomputer 40. A signal is sent to the termination unit 60 to terminate the supply of power supply voltage to the device. When the operating temperature environment is low, the resistance value of the thermistor TH is increased and the bias voltage Vb is increased, so that the width of the drop voltage detection change amount “Vb−Vdet” is expanded. The end voltage can be detected, and the battery life can be extended.

  As described above, in this embodiment, the thermistor whose resistance value changes depending on the temperature is added to the voltage drop circuit for detecting the voltage drop (change amount), so that it is possible to detect the end according to the use environment temperature. The battery life under the environment can be extended as compared with the prior art.

  FIG. 2 is a graph showing the voltage drop detection change temperature characteristic of the voltage drop detection circuit according to the present embodiment. Symbol 1 is the voltage drop detection change temperature characteristic curve, and symbol 2 is the voltage detection of the voltage detector 19. Value, symbol 3 is a drop amount at low temperature, symbol 4 is a drop voltage change amount Vb indicating a drop amount of 25 ° C. (reference environment temperature), Vb = EVCC3.3 × {(RH + RB) / (RA + RH + RB)} Can be sought. Here, RA is the resistance value of the bias resistor A, RB is the resistance value of the bias resistor B, and RH is the resistance value of the thermistor 16.

<Embodiment 2>
In the second embodiment, a thermistor whose resistance value depends on the temperature is provided in the bias resistor portion of the voltage drop detection circuit, thereby enabling the end detection according to the temperature environment. However, the end detection method according to the temperature environment is described below. It is not limited to this.
In the present embodiment, a temperature sensor 70 is provided, and the detected value of the environmental temperature is input to the sub-microcomputer in the battery-driven power supply device of FIG. In addition, a bias resistor changeover switch for changing the connection of the bias resistors C, D, E is provided, and the bias resistor changeover switch is changed by turning on / off the bias resistor changeover switch by a microcomputer based on the detection value by the temperature sensor. As a result, the voltage drop detection amount is changed, and the end detection suitable for the characteristics of the battery can be performed at the environmental temperature.

  FIG. 3 is a diagram showing an example of an AA battery drive power supply apparatus according to the present embodiment. A portion within a dotted line frame constitutes a voltage drop detection circuit 20. Is a bias resistor A, symbol 13 is a bias resistor C, symbol 14 is a bias resistor D, symbol 15 is a bias resistor E, symbol 16 is a coupling capacitor, symbol 18 is a bias resistor selector switch, symbol 19 is a voltage detector, symbol Vc1 ˜Vc4 indicates a bias voltage applied to the point j by the bias resistor A and a combination of the bias resistors B, D, and E. The bias resistors A, C, D, and E are provided in series between the ideal voltage source (EVCC3.3) and the ground, and the bias resistors B, D, and E are biases that are on / off controlled by the microcomputer 40. The combination can be changed by the resistance changeover switches 18-1 and 18-2.

  FIG. 4 is a diagram showing an embodiment of the bias resistance control table. The bias resistance control table 80 includes bias resistances C, D, E corresponding to ON / OFF of the bias resistance changeover switches 18-1, 18-2. Is a table in which the temperature (temperature range) is associated with the bias voltages Vc1 to Vc4 generated at the point j by the combination of the above and the bias resistor A, and is registered (stored) in the memory of the microcomputer 40 in advance.

  In FIG. 4, symbol 81 is a temperature column storing a temperature range, and symbol 82 stores on / off setting values of bias resistance changeover switches 18-1 and 18-2 corresponding to the detected temperature in the range of the temperature column 81. It means switch setting column. The bias resistance control table 80 may be incorporated into the end detection program as a table constant.

  When the temperature sensor 70 detects the ambient temperature and inputs it to the sub-microcomputer 50, the sub-microcomputer 50 digitizes the detected value and sends it to the microcomputer 40. The microcomputer 40 refers to the bias resistance control table 80 and sets the detected temperature. Using a combination of ON / OFF of the corresponding bias resistance change-over switches 18-1 and 18-2, the bias drop switching is performed so that the voltage drop detection circuit 20 can detect the voltage drop change amount Vc suitable for the current temperature environment. The switches 18-1 and 18-2 are turned on / off.

  In the example of FIG. 4, the temperature range of the temperature column 81 of the bias resistance control table 80 is 25 ° C. or more, 15 ° C. or more and less than 25 ° C., 5 ° C. or more and less than 15 ° C., but less than 5 ° C. The range is not limited to this example. In other words, an approximate value based on a theoretical value or an actual measurement value, or an empirical value is determined in advance and registered in the bias resistance control table 80 in association with the ON / OFF combination of the bias resistance changeover switches 18-1 and 18-2. Can do.

  FIG. 5 is a flowchart showing an example of the operation of the AA battery drive power supply apparatus according to this embodiment when the battery end is detected. The processing shown below is basically stored in a program memory such as a flash memory by the microcomputer 40 in advance. It is executed according to the program. Hereinafter, an example in which the present invention is applied to the AA battery driving power supply apparatus 200 shown in FIG. 3 will be described with reference to FIGS. 3 and 4.

  In the flowchart of FIG. 5, an example is basically described in which the microcomputer 40 executes according to a program stored in a program memory such as a flash memory in advance, but it is not necessary to store all functions in the program memory. Alternatively, a part or all of the information may be received via a network.

  In FIG. 5, the temperature sensor 70 inputs a temperature detection signal to the sub-microcomputer 50 (step S1). The sub-microcomputer 50 converts the temperature signal (analog signal) received from the temperature sensor 70 into a digital signal and a predetermined temperature unit ( For example, it is transmitted to the microcomputer 40 at predetermined time intervals as a temperature value (° C.) (step S2).

  The microcomputer 40 compares the temperature value received from the sub-microcomputer 50 with the temperature range stored in the temperature column 81 of the bias resistance control table 80, and the value in the switch setting column 82 associated with the corresponding temperature range. (On / off values of the bias resistance changeover switches 18-1 and 18-2) are acquired (step S3), and the bias resistance changeover switches 18-1 and 18-2 of the voltage drop detection circuit 20 are turned on / off. (Step S4).

  The voltage drop detection circuit 20 includes a bias voltage Vc generated at a point j by a bias resistor A and a combination of bias resistors C, D, and E according to on / off of the bias resistor changeover switches 18-1 and 18-2. Then, a voltage drop detection amount “Vc−Vdet” which is a difference from the voltage detection value Vdet of the voltage detector 19 is set (step S5), and the bias voltage Vc is compared with the set voltage drop detection amount “Vc−Vdet”. If the bias voltage Vc ≧ the set value, the process proceeds to step S7. If the bias voltage Vc <the set value, the process returns to step S1 (step S6).

  If the bias voltage Vc ≧ the set value (voltage drop detection amount “Vc−Vdet”), the microcomputer 40 sends a signal to the power supply termination unit 60 to stop the supply of the power supply voltage to the device (step S7).

  By the operation shown in the flowchart of FIG. 5, the AA battery drive power supply apparatus 200 controls the resistance value of the bias resistor in the voltage drop detection circuit 20 by the microcomputer 40 according to the operating temperature environment, and detects the voltage drop according to the temperature. Since the amount “Vc−Vdet” can be set, the end voltage according to the characteristics of the battery can be detected even in a low temperature environment, so that the battery life can be extended.

  In the example of FIG. 3, the bias resistors C, D, and E are switched by the bias resistor changeover switch 18, but more than this may be provided. In this case, each time the bias resistance is increased by one, one bias resistance changeover switch 18 is added, and the temperature range corresponding to the switch combination of the bias resistance control table 80 may be changed.

  In the example of FIG. 3, the bias resistance value is made variable by switching control of a plurality of bias resistors. However, the microcomputer 40 generates a point j by a predetermined calculation formula based on the detected temperature. The bias resistance value obtained at the point j by the variable bias resistance element and the bias resistor A is obtained by using a variable bias resistance element whose bias resistance value is continuously variable under the control of the microcomputer 40. By changing the voltage drop detection amount, the end detection suitable for the battery characteristics may be performed at the environmental temperature. If it does in this way, the end detection according to 1 to 1 to the change of the detected temperature can be performed.

(Modification)
In the second embodiment, a temperature sensor is used and the voltage drop detection amount is changed by microcomputer control. However, by combining with the result of automatic battery discrimination by setting or battery type setting by the user, the temperature characteristics of various batteries can be adjusted. An end detection can be performed by a suitable voltage drop.

  As mentioned above, although several Example of this invention was described, it cannot be overemphasized that this invention is not limited to said each Example, A various deformation | transformation implementation is possible.

It is a figure which shows one Example of the AA battery drive power supply device concerning Embodiment 1. FIG. FIG. 6 is a diagram illustrating a detected change amount temperature characteristic of a voltage drop according to the first embodiment. It is a figure which shows one Example of the AA battery drive power supply device concerning Embodiment 3. FIG. It is a figure which shows one Example of the table for bias resistance control. 10 is a flowchart illustrating an operation example when the end of the battery of the AA battery drive power supply device according to the third embodiment is detected. It is a figure which shows the prior art example of an AA battery drive power supply device. It is a figure which shows an example of the battery discharge curve of an AA battery.

Explanation of symbols

10, 20, 30 Voltage drop detection circuit (battery end detection means)
11, 12, 13, 14, 15 Bias resistor 17 Thermistor (resistance value control means)
18-1, 18-2 Bias resistance changeover switch (resistance value control means, changeover switch)
40 Microcomputer (resistance control means, switch control means)
50 Sub-microcomputer 70 Temperature sensor (temperature detection means)
80 Bias resistance control table (resistance value control means, switch control information storage means)
100, 200, 300 AA battery drive power supply

Claims (6)

A battery end detection device in a battery-driven power supply device,
Tolerance setting means for setting the voltage drop detection value of the power supply according to the temperature;
Resistance value control means for changing the resistance value of the bias resistance portion of the battery power supply voltage according to the temperature;
Resistance value detection means for detecting the resistance value of the bias resistance portion after the change by the resistance value control means;
Power supply termination means for terminating the supply of the battery power when the resistance value detected by the resistance value detection means reaches the voltage drop detection value;
A battery end detection device comprising:   The resistance value control means is a temperature-dependent resistance member whose resistance value changes depending on temperature, and the bias resistance portion includes a plurality of bias resistance members arranged in series and the temperature-dependent resistance member. The battery end detection device according to claim 1. Furthermore, a temperature detecting means for detecting the temperature is provided,
The said resistance value control means has a changeover switch which switches the connection of the several bias resistance member arrange | positioned in series in the said bias resistance part according to the temperature detected by the said temperature detection means. Item 4. The battery end detection device according to Item 1. Furthermore, a switch control means for performing on / off control of the changeover switch, and switch control information storage means for associating the on / off value of the switch with the temperature value measured by the temperature measurement means,
The switch control means performs on / off control of the changeover switch by taking out an on / off value of a switch corresponding to the temperature value measured by the temperature measurement means from the switch control information storage means. The battery end detection device according to 3. A battery end detection method in a battery-driven power supply device,
Setting the voltage drop detection value of the power supply according to the temperature;
Changing the resistance value of the battery power supply voltage bias resistor according to the temperature;
Detecting the resistance value of the bias resistor section after change due to temperature;
When the detected resistance value reaches the set voltage drop detection value, terminating the supply of the battery power;
A battery end detection method comprising: On the battery-powered computer,
A function to set the voltage drop detection value of the power supply according to the temperature,
A function to change the resistance value of the battery power supply voltage bias resistor according to the temperature;
A function of terminating the supply of the battery power supply when the resistance value of the bias resistor section after the change due to temperature reaches the set voltage drop detection value;
A program that executes.

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