JP2000030719A - Battery temperature control circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery temperature control circuit in which the discharge capacity of a battery is increased by raising the temperature of the battery by utilizing the energy of the battery itself to improve the operational time of a camera or electronic equipment with the battery. SOLUTION: This battery temperature control circuit constitutes a closed circuit with a battery 8 used as a power source of an instrument such as a camera, and has a switching means (a MOS transistor) Tr1 passing internal current in the battery 8 when being turned on; and a turning on means (a comparator OP1 and an NTC thermistor Rr1) of the switching means Tr1, which detects the temperature of the battery and when the detected temperature is lower than the specified temperature. A load RL is connected in parallel to the switching means Tr1 to the closed circuit, and the internal current of the battery 8 is limited with the load RL. When the battery temperature falls down than the specified temperature, the switching means Tr1 is turned on, and the closed circuit of the battery 8 is turned on. Current is passed in the battery 8, the battery 8 is self heated by the internal current, the temperature of the battery 8 is raised, and drop in discharge capacity of the battery 8 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery temperature control circuit for an electronic device using a battery as a power source, such as a camera, in which the battery temperature is appropriately controlled to improve the operable time of the electronic device.

[0002]

2. Description of the Related Art Various portable electronic devices such as a camera and a portable telephone use a battery as a power source. in this case,
In mobile phones, etc., secondary batteries that can be used repeatedly are used, but in cameras, etc., due to usage frequency and power consumption,
A temporary battery such as an alkaline battery is used. This type of battery has a characteristic that the discharge capacity indicating the effective amount of energy of the battery changes according to a temperature change. FIG. 5 is a graph showing the characteristics of the discharge capacity of an AA alkaline battery.
The discharge capacity before dropping to [V] is shown using temperature as a parameter. Thus, as the temperature decreases, the discharge capacity of the dry battery also decreases. Therefore, for example, when the camera is used in a cold region, even if the same dry battery is used than in a warm region, the number of shots is reduced, and the intended number of photos cannot be taken. Is more likely to occur.

[0003]

For this reason, conventionally, there has been proposed a configuration in which a battery chamber for accommodating a dry battery has a heat insulating structure so that the dry battery is hardly affected by the outside air temperature. It is difficult to prevent the drop. It is also considered to cover the entire camera with a heat insulating cover, but even in this case, there is a limit to the effect of preventing the temperature of the dry battery from lowering. In addition, such a problem is not limited to dry batteries, but is common to various primary batteries. The same applies to not only cameras but also various electronic devices using a primary battery as a power source.

An object of the present invention is to increase the temperature of a battery by utilizing the energy of the battery itself, thereby increasing the discharge capacity of the battery, and improving the operable time of a camera, an electronic device, or the like using the battery. A temperature control circuit is provided.

[0005]

A battery temperature control circuit according to a first aspect of the present invention forms a closed circuit with a battery provided as a power source for a device such as a camera, and when the battery is turned on, the battery temperature control circuit is internally provided in the battery. A switch for passing a current; and a unit for detecting a temperature of the battery and turning on the switch when the battery temperature falls below a predetermined temperature. In this case, it is preferable that a load is connected in series with the switch means in the closed circuit, and the internal current of the battery is limited by the load.

A battery temperature control circuit according to a second aspect of the present invention comprises a battery provided in an apparatus such as a camera and a switch means for forming a closed circuit, and for allowing a current to flow through the closed circuit when turned on. A heating means connected in the closed circuit, for generating heat by the current and externally heating the battery;
Means for detecting the temperature of the battery and turning on the switch means when the temperature of the battery falls below a predetermined temperature. The heating means is constituted by a resistance heating wire such as a nichrome wire.

A battery temperature control circuit according to a third aspect of the present invention constitutes a closed circuit with a battery provided in a device such as a camera, and a switch for passing a current to the closed circuit when turned on. Means, an inductance element that is connected in the closed circuit, and stores electric energy by passing the current, and an inductance element that is connected in parallel with the inductance element and is energized by the electric energy stored in the inductance element to generate heat. And a means for detecting the temperature of the battery and repeatedly turning on and off the switch means when the temperature of the battery falls below a predetermined temperature. The heat generating means includes a temperature
It is preferable to configure the thermistor with a positive resistance characteristic.

Further, a battery temperature control circuit according to a fourth aspect of the present invention is provided in a device using a battery provided in a device such as a camera as a power source, and constitutes a closed circuit with the battery. Switch means for passing a current to the closed circuit, and a temperature-dependent resistance element connected in series with the switch means in the closed circuit, the resistance of which decreases when the temperature of the battery decreases. Is provided. The temperature-dependent resistance element is constituted by a thermistor having a positive temperature / resistance characteristic.

As described above, in the battery temperature control circuits according to the first to third aspects of the present invention, when the battery temperature falls below a predetermined temperature, the switch means is turned on, and the closed circuit for the battery is turned on. As a result, current flows through the battery or the closed circuit, and the battery self-heats due to the internal current in the battery, or the heating means connected to the closed circuit generates heat and externally heats the battery, thereby reducing the temperature of the battery. Rise, eliminating the decrease in battery discharge capacity. Further, in the battery temperature control circuit according to the fourth aspect of the present invention, when the battery temperature decreases, the resistance value of the temperature-dependent resistance element decreases, current flows through the battery or the closed circuit, and the battery self-powers due to the internal current of the battery. Fever,
Alternatively, the battery is externally heated by the heat generated by the temperature-dependent resistance element, thereby increasing the temperature of the battery and eliminating the decrease in the discharge capacity of the battery.

[0010]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic perspective view of a first embodiment in which a battery temperature control circuit of the present invention is applied to a battery for a power supply of a camera. A photographing lens 2, a viewfinder 3, various switches 4 including a main switch, a release button 5 , LC
A battery storage room 7 is provided in a part of the camera main body 1 in which the D display unit 6 and the like are disposed, and two batteries, here, AA alkaline batteries 8 can be stored in the battery storage room 7. I have. The battery storage chamber 7 is configured such that a part of the bottom surface of the camera body 1 is formed as a hinged battery cover 9, and the battery storage chamber 7 is opened when the battery cover 9 is opened. The battery 8 can be stored in the battery storage room 7. In addition, the battery storage room 7
Inside, a tubular heat insulating material 11 is housed, and the battery 8 to be stored is housed inside the heat insulating material 11, and the heat insulating material 11 suppresses the influence of the outside air temperature on the battery 8. Have been. A temperature sensor (thermistor) 12, which will be described later, is provided in the battery storage chamber 7 so as to detect the temperature of the stored battery 8.

FIG. 2 is a block diagram showing a circuit configuration of a main part of the camera. The CPU 20 is provided with a main switch SW-MAIN as a part of the various switches 4 and a release button 5 in order. The photometric switch SW-S and the release switch SW-R to be operated are connected, and the CPU 20 is reset by the ON operation of the main switch SW-MAIN, and the photometric IC 21 and the AF (auto focus) IC by the ON operation of the photometric switch SW-S.
Then, an appropriate exposure and AF distance are calculated based on the photometric value measured by the photometric IC 21 and the distance value measured by the AFIC 22. At the same time, the motor driver 23 is controlled to drive the AF motor 24 so that the photographing lens 2 performs the AF operation. Further, the CPU 20 performs the exposure operation with the proper exposure by turning on the release switch SW-R, and controls the motor driver 23 after the exposure, and executes the winding of the film by the winding motor 25. Further, the CPU 20 displays predetermined data such as an exposure value and a distance measurement value on the LCD display element 26 of the LCD display unit 6. Further, the CPU 20 is driven by a power supply voltage VCC supplied from the battery 8, and a temperature control circuit 31 for controlling the temperature of the battery 8 is provided between its D / A output terminal and the battery 8. Is connected. Note that the power supply voltage VCC is a certain voltage by a step-up / step-down regulator for the battery voltage.

The temperature control circuit 31 has a comparator OP1 composed of an operational amplifier. The inverting input terminal of the comparator OP1 has a thermistor Rt as the temperature sensor 12.
1 and a resistor R2, a voltage V obtained by dividing the power supply voltage VCC.
2 is input. A non-inverting input terminal of the comparator OP1 has a D / A output terminal D / A of the CPU 20.
The voltage V1 output from -OUT is input. This voltage V1 is a voltage as a reference voltage in the comparator OP1, and is set to a predetermined voltage in advance.
The output terminal of the comparator OP1 is pulled up to the power supply voltage VCC by a pull-up resistor R3, and is connected to the gate of an N-channel MOS transistor Tr1. The drain of the MOS transistor Tr1 has a load resistor RL and Light emitting diode LED1 for display
And a series circuit of a pull-up resistor R4 are connected in parallel,
Connected to the positive electrode of the battery 8. In addition, the M
The source of the OS transistor Tr1 is connected to the negative electrode of the battery 8, that is, the ground.

As is well known, the thermistor Rt has a characteristic that its resistance value changes according to a temperature change.
As shown in FIG. 3, there are a PTC thermistor having a positive characteristic and a NTC thermistor having a negative characteristic with respect to a change in resistance with respect to a temperature change. Here, the NTC thermistor is used. This NTC thermistor has a temperature To in the example of FIG.
When the temperature is [° C.], the resistance value is Ro [Ω], and when the temperature is lower than this, the resistance value increases.

According to this configuration, for example, if the temperature of the battery 8 is the aforementioned temperature To, here, the temperature To is 0 [° C.], the voltage V2 of the inverting input terminal of the comparator OP1 is obtained.
Is as follows: V2 = VCC · (R2 / (R2 + Ro)) The reference voltage V1 is output from the D / A output terminal of the CPU 20, and is input to the non-inverting input terminal of the comparator OP1. When the reference voltage V1 is set so that V1 = V2 at the temperature of 0 ° C., when the battery temperature is higher than 0 ° C., the output Vo of the comparator OP1 becomes “L”. Therefore, the MOS transistor Tr1 is in the off state, so that no current flows from the battery 8 to the load resistor RL, and the display light emitting diode LED1 does not emit light.

On the other hand, when the temperature of the battery 8 drops below 0 ° C., the resistance value of the thermistor Rt1 increases more than Ro, as shown in FIG. 3, so that the voltage V2 at the input terminal of the comparator OP1 increases. Be lowered. When V1> V2, the output Vo of the comparator OP1 becomes “H”.
And the MOS transistor Tr1 is turned on.
Therefore, the load resistance RL and the MOS transistor Tr1
The current of the battery 8 flows through the source / drain of the battery 8, and this current also flows inside the battery 8, so that the internal resistance of the battery 8 generates heat inside the battery.
The self is heated and the temperature rises. The state in which this current is flowing is indicated by the display light emitting diode LE.
It can be confirmed by the emission of D1. Then, the temperature rises to a certain temperature, and the thermistor Rt1 reaches the temperature of 0 [° C.].
Then, the output of the comparator OP1 becomes "L" again and the MOS transistor Tr1 is turned off, so that the flow of current by the battery 8 is stopped.

As described above, when the temperature of the battery 8 falls below 0 ° C., the battery 8 self-heats due to the current flowing through the load resistor RL and the MOS transistor Tr1, and the temperature of the battery itself rises. Let it. Also, when the battery 8 is
When the temperature is raised to [° C.], the MOS transistor Tr
By turning off 1, the flow of the current is stopped, and the self-heating is also stopped. Therefore, by repeating this operation, the temperature of the battery 8 itself is feedback-controlled, and as a result, as shown in FIG.
The temperature will be kept near. As a result, the temperature of the battery 8 can always be maintained at a temperature close to 0 [° C.] even when photographing at a cold temperature, and as shown in FIG.
, The discharge capacity can be increased, and the number of shots can be increased. The temperature of the battery 8 can be set to an arbitrary temperature by changing and adjusting the reference voltage V1 output from the CPU 20.

FIG. 6 is a conceptual diagram showing a configuration of a battery storage room according to a second embodiment of the present invention. Note that the same reference numerals are given to portions equivalent to the battery storage chamber shown in FIG.
In the second embodiment, the heat insulating material 1 of the battery storage chamber 7 is used.
A nichrome wire 13 serving as a heat generating means is spirally wound along the inner wall of the battery 1, and when the nichrome wire 13 generates heat, the stored battery 8 is heated to increase the temperature. FIG. 7 is a block circuit diagram including the temperature control circuit 32 according to the second embodiment. Here, the nichrome line 13 is connected instead of the load resistor RL in the first embodiment shown in FIG. ing.

According to the second embodiment, when the temperature of the battery 8 is, for example, 0 ° C. or more, the MOS transistor Tr1 is turned off by the output of the comparator OP1 as in the first embodiment. No current flows through line 13. On the other hand, when the temperature of the battery 8 is 0
When the temperature drops below [° C.], the comparator OP1
Becomes "H", the MOS transistor Tr1 turns on, and a current flows through the nichrome line 13. For this reason,
The battery 8 self-heats due to the current flowing through the inside, and the nichrome wire 13 generates heat due to the current flowing through the nichrome wire 13, and this heat causes the battery 8 to be externally heated. As a result, the temperature of the battery 8 rises to reach 0 [° C.], which prevents a decrease in the discharge capacity due to the temperature decrease and a decrease in the number of shots due to the decrease. As described above, in the second embodiment, the battery 8
Is heated by self-heating and external heating by the nichrome wire 13, so that the temperature can be raised more quickly than in the first embodiment. Further, as in the first embodiment, a temperature control circuit capable of setting the temperature of the battery 8 to an arbitrary temperature by changing and adjusting the reference voltage V1 output from the CPU 20 is the same as in the first embodiment.

FIG. 8 is a conceptual diagram showing a configuration of a battery storage room in a third embodiment of the present invention. In the third embodiment, a heat generating means 14 composed of a PTC thermistor having a positive temperature / resistance characteristic is disposed along the inner wall of the heat insulating material 11 of the battery storage chamber 7, and a current is supplied to the heat generating means 14. The battery 8 is configured to heat the battery 8 by utilizing the heat generated when the battery flows, thereby increasing the temperature. FIG. 9 is a block circuit diagram including the temperature control circuit 33 according to the third embodiment. While the output of the comparator OP1 according to the first embodiment shown in FIG. CPU 20 according to the output of
From the MOS transistor Tr
It is configured to input to one gate. Also, the first
Instead of the load resistor RL, the resistor R4 and the display light emitting diode LED1 of the embodiment, a circuit in which a PTC thermistor Rt2 and a diode D constituting the heating means 14 and a coil (inductor) L are connected in parallel is connected.

According to the third embodiment, when the temperature of the battery 8 is, for example, 0 ° C. or more, the comparator OP1
Is "L", and the CPU 20 receives the
The rectangular signal S1 is not input to the gate of the S transistor Tr1. Therefore, the MOS transistor Tr1
Is turned off, current does not flow through the PTC thermistor 14, and no heat generation operation is performed. On the other hand, when the temperature of the battery 8 drops below 0 [° C.], the output of the comparator OP1 becomes “H”. The CPU 20 receives this signal and inputs the rectangular signal S1 to the gate of the MOS transistor Tr1, so that the MOS transistor Tr1 is repeatedly turned on and off according to the level “H” and “L” of the rectangular signal S1. Then, M at which the rectangular signal S1 becomes “H”
At the instant when the OS transistor Tr1 is turned on, a current flows through the inductor L, so that a current also flows inside the battery 8 and the battery 8 self-heats.

The inductor L is a PTC thermistor R
Since the resistance is lower than t2, a current flows through the inductor L at this time, and current energy is accumulated in the inductor L. The accumulated the energy E is the inductance of the inductor L Lo, when the Io current value is ^{E = Lo · Io 2/2} . Then, at the next instant, the rectangular signal “L” causes M
When the OS transistor Tr1 is turned off, the current from the battery 8 is stopped, but the current due to the energy E stored in the inductor L flows through the diode D to the PTC thermistor Rt2. Therefore, the PTC thermistor Rt2 is heated, and the battery 8 is externally heated by this heating. Therefore, the temperature of the battery 8 increases to reach 0 ° C., and the discharge capacity decreases with the temperature decrease, and This prevents a reduction in the number of images taken. In the third embodiment, the flow of the battery 8 is alternately repeated, and the battery 8 is self-heated during the flow of electricity. When the battery 8 is shut off, the battery 8 is externally heated by the PTC thermistor Rt2 due to the accumulated energy. Use it effectively,
The temperature of the battery 8 can be quickly raised. Note that this third
Also in the embodiment, the temperature of the battery 8 can be arbitrarily set by adjusting the voltage V1 output from the CPU 20.

FIG. 10 is a diagram showing a configuration of a battery storage room according to a fourth embodiment of the present invention. In the fourth embodiment, a PTC thermistor Rt2 as a heating means 14 is arranged instead of the nichrome wire 13 provided in the battery storage chamber of the second embodiment shown in FIG. And FIG.
1 is a block circuit diagram including a temperature control circuit 34 according to the fourth embodiment. When the main switch is turned on from the CPU, the MOS transistor T
The voltage Vo for turning on r1 is input to the gate of the MOS transistor Tr1. The source of the MOS transistor Tr1 has a variable resistor Rv and the PT
The C thermistor Rt2 is connected in series, and the battery 8 is connected to its source / drain.

In the fourth embodiment, when the battery temperature is, for example, 0 ° C. or more, the resistance value of the PTC thermistor Rt2 is large due to the positive characteristics of the PTC thermistor shown in FIG. MOS transistor Tr1
The source / drain current is very small, or the flow of current is blocked. Therefore, the battery 8 hardly generates heat, and the PTC thermistor Rt2 does not generate heat. On the other hand, when the temperature of the battery 8 decreases, P
Since the resistance value of the TC thermistor Rt2 is also reduced, PT
A current flows through the battery 8 through the C thermistor Rt2, the variable resistor Rv, and the MOS transistor Tr1. For this reason, self-heating in the battery 8 and the PTC thermistor Rt
The temperature of the battery 8 is increased by the external heating of the heat generated by the battery 2. When the temperature of the battery 8 rises to 0 [° C.], the resistance value of the PTC thermistor Rt2 increases again.
v, the current flowing through the MOS transistor Tr1 is suppressed, and the self-heating of the battery 8 and the PTC thermistor Rt2
External heating is suppressed or stopped. By repeating this operation, it is possible to always control the battery 8 at around 0 ° C.

In the fourth embodiment, since the temperature detecting circuit using the comparator OP1 as in the first to third embodiments is not required, the present invention can be realized with a simple configuration, and the size can be reduced. This is advantageous in reducing the price. The current flowing through the PTC thermistor Rt2 is adjusted by changing and adjusting the resistance value of the variable resistor Rv, and the characteristics of the external heating rate of the battery and the set temperature by the PTC thermistor Rt2 are adjusted. Further, as shown in FIG. 12, the PTC thermistor Rt2 has a characteristic that the response of the current flowing when the same voltage is applied has a time dependency, and after a predetermined time has elapsed, the PTC thermistor Rt2 is in an equilibrium state in a low current state. Therefore, when the battery temperature is controlled for a long time, the consumption capacity of the battery in the PTC thermistor is suppressed, and the influence on the discharge capacity of the battery can be reduced.

In each of the above embodiments, the present invention is applied to a camera using an AA alkaline battery. However, another electronic device using a battery as a power source or a primary battery other than the above is used. The present invention can be similarly applied to cameras and electronic devices. Further, the NTC thermistor as the temperature sensor used in the first to third embodiments may be constituted by another temperature detecting element, and the circuit constitution is arbitrary.

[0026]

As described above, in the battery temperature control circuits according to the first to third aspects of the present invention, the switch means is turned on when the battery temperature falls below a predetermined temperature, and the closed circuit for the battery is turned on. And As a result, current flows through the battery or the closed circuit, and the battery self-heats due to the internal current in the battery, or the heating means connected to the closed circuit generates heat and externally heats the battery, thereby reducing the temperature of the battery. Rise, eliminating the decrease in battery discharge capacity. In this case, the first aspect of the present invention does not require a heat generating means, which is advantageous in reducing the size. Further, in the second invention, the load of the first invention is configured as a heat generating means, and the temperature of the battery is quickly raised to externally heat the battery by the heat generating means, and the battery energy can be effectively used. In addition, the third
According to the invention, the energy of the battery can be more effectively utilized by accumulating the energy in the inductance element. Further, in the battery temperature control circuit according to the fourth aspect of the present invention, when the battery temperature decreases, the resistance value of the temperature-dependent resistance element decreases, current flows through the battery or the closed circuit, and the battery self-powers due to the internal current of the battery. The battery is externally heated by heat generation or heat generated by the temperature-dependent resistance element, thereby increasing the temperature of the battery and eliminating the decrease in the discharge capacity of the battery. Further, in the fourth aspect, means for detecting the battery temperature is not required, which is extremely advantageous for further simplifying the configuration, realizing miniaturization, and reducing the cost.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a first embodiment applied to a battery storage room of a camera of the present invention.

FIG. 2 is a block circuit diagram of the first embodiment.

FIG. 3 is a diagram showing temperature-resistance characteristics of a thermistor;

FIG. 4 is a diagram showing a time change characteristic of a battery temperature in the first embodiment.

FIG. 5 is a diagram showing the temperature dependence of the discharge capacity of a battery.

FIG. 6 is a conceptual configuration diagram of a battery storage room in a second embodiment of the present invention.

FIG. 7 is a block circuit diagram according to a second embodiment of the present invention.

FIG. 8 is a schematic configuration diagram of a battery storage room according to a third embodiment of the present invention.

FIG. 9 is a block circuit diagram according to a third embodiment of the present invention.

FIG. 10 is a schematic configuration diagram of a battery storage room according to a fourth embodiment of the present invention.

FIG. 11 is a block circuit diagram according to a fourth embodiment of the present invention.

FIG. 12 is a diagram showing the time dependency of a PTC thermistor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Camera main body 4 Various switches (main switch) 5 Release button 7 Battery storage room 8 Battery 11 Insulation material 12 Temperature sensor (NTC thermistor) 13 Heat generation means (Nichrome wire) 14 Heat generation means (PTC thermistor) 20 CPU 31-34 Temperature control Circuit OP1 Comparator Tr1 MOS transistor Rt1 NTC thermistor Rt2 PTC thermistor L Inductance

Claims (13)

[Claims] 1. A device provided with a battery as a power supply, comprising a closed circuit with the battery, a switch means for passing an internal current to the battery when the battery is turned on, and detecting a temperature of the battery. Means for turning on the switch means when the temperature of the battery falls below a predetermined temperature. 2. The battery temperature control circuit according to claim 1, wherein a load is connected in series with the switch means in the closed circuit, and the internal current of the battery is limited by the load. 3. A switch provided in an apparatus using a battery as a power source, the switch comprising a closed circuit with the battery, and allowing current to flow through the closed circuit when the battery is turned on, and connected to the inside of the closed circuit. Heat generating means for generating heat by the current to externally heat the battery, and means for detecting a temperature of the battery and turning on the switch means when the temperature of the battery falls below a predetermined temperature. A battery temperature control circuit. 4. The battery temperature control circuit according to claim 3, wherein said heating means is a resistance heating wire such as a nichrome wire. 5. A temperature detecting circuit for detecting a temperature of a battery and outputting a corresponding voltage, and a reference voltage for outputting a voltage corresponding to a reference temperature of the battery as a reference voltage. And a comparator for comparing a detection voltage from the temperature detection circuit with the reference voltage and outputting a signal for turning on the switch means when the detected temperature is lower than the reference temperature. 5. The battery temperature control circuit according to any one of claims 4 to 4. 6. A switch provided in a battery-powered device, forming a closed circuit with the battery, and allowing a current to flow through the closed circuit when the battery is turned on, and connected to the closed circuit. An inductance element that accumulates electric energy by passing the current; heating means connected in parallel with the inductance element, which is energized by the electric energy accumulated in the inductance element and generates heat to heat the battery; Means for detecting the temperature of the battery and repeatedly turning on and off the switch means when the temperature of the battery falls below a predetermined temperature. 7. The battery temperature control circuit according to claim 6, wherein said heat generating means is a thermistor having a positive temperature / resistance characteristic. 8. A means for turning on / off the switch means detects a temperature of a battery and outputs a corresponding voltage, and outputs a voltage corresponding to a reference temperature of the battery as a reference voltage. A reference voltage circuit, a comparator that compares the detected voltage from the temperature detection circuit with the reference voltage, and outputs a predetermined signal when the detected temperature is lower than the reference temperature; and the predetermined signal of the comparator. 8. The battery temperature control circuit according to claim 6, further comprising: control means for inputting a rectangular signal having a predetermined period to said switch means when said switch is received. 9. The battery temperature control circuit according to claim 5, wherein said temperature detecting circuit is a voltage dividing circuit for dividing a power supply voltage by a thermistor having a negative temperature / resistance characteristic and a fixed resistor. 10. A switch provided in a device powered by a battery, forming a closed circuit with the battery, and causing a current to flow through the closed circuit when turned on, and the switch in the closed circuit. A temperature-dependent resistance element which is connected in series with the means and whose resistance value decreases when the temperature of the battery decreases. 11. The battery temperature control circuit according to claim 10, wherein the temperature-dependent resistance element is a thermistor having a positive temperature / resistance characteristic. 12. The battery temperature control circuit according to claim 1, wherein said switch means is a MOS transistor. 13. The battery according to claim 1, wherein the battery is a primary battery, and the device is a camera powered by the battery.
3. The battery temperature control circuit according to any one of 2.