Battery polarity determination circuit, charger and electronic equipment

Abstract

The battery polarity determination circuit of the present invention comprises: a battery accommodating portion (2) including a first contact (T1) and a second contact (T2) which are in contact with respective electrode terminals of a battery (BAT); a control device (3) which is connected to a voltage lead-out point (P1) for leading out a voltage of a battery (BAT) through a resistor (R) and determines the polarity of the battery (BAT); a connection switching circuit (4) which can switch between a first connection state and a second connection state; and a diode (D) whose cathode is connected to a voltage reading point (P2) connected to the resistor (R) and the control device (3) and whose anode is grounded, wherein the control device (3) determines the polarity of the battery (BAT) based on a voltage (V) at the voltage reading point (P2) for the connection state of the connection switching circuit (4). P2 ) to determine the polarity of the battery (BAT), the forward voltage (V F ) is set so that the voltage (V P2 ) is the lower limit value of the absolute maximum rating of the control device (3) (V MIN )above.

Description

Technical Field

[0001] The invention relates to a battery polarity determination circuit, a charger and electronic equipment. Background Art

[0002] Generally speaking, cylindrical dry cells and rechargeable batteries are widely used as power sources for various electronic devices. In addition, rechargeable batteries can be repeatedly used by charging, and chargers are widely used as devices for charging rechargeable batteries. When installing a battery on such an electronic device or charger, it is necessary to confirm the polarity of the battery. That is, the battery must be installed on the electronic device or charger in the correct connection direction in which the positive terminal abuts against the contact point where the positive terminal should abut, and the negative terminal abuts against the contact point where the negative terminal should abut.

[0003] However, there are many cases where the battery can be mounted on the electronic device and the charger even when the connection direction is reversed, so the battery may be mounted in the connection direction reversed from the correct connection direction. When the battery is mounted in the connection direction reversed from the correct connection direction, the electronic device will not operate, or the battery cannot be charged in the charger, and for example, the battery may leak.

[0004] As an example of the prior art for solving this problem, for example, Patent Document 1 discloses a charger that determines the connection direction of the battery by using a pair of photocouplers that detect the presence or absence of current flowing from the positive terminal and the negative terminal of the battery, respectively. Also, for example, Patent Document 2 discloses a charger and an electronic device that include a pair of operational amplifiers that compare the voltages of the positive terminal and the negative terminal of the battery, and determines the connection direction of the battery based on the magnitude relationship of the output voltages of the pair of operational amplifiers.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Laid-Open No. 7-39076

[0008] Patent Document 2: Japanese Patent Application Publication No. 2018-153034 Summary of the invention

[0009] Technical problem to be solved by the invention

[0010] However, since the above-mentioned prior arts all use relatively expensive electronic components such as optocouplers and operational amplifiers, it is possible that the cost reduction of chargers and electronic devices is hindered. On the other hand, in order to reduce costs, it is also possible to consider using a control device to directly read the voltage of the battery without using these relatively expensive electronic components. However, in this case, depending on the connection direction of the battery, the control device may be damaged due to the input of a voltage outside the absolute maximum rating range.

[0011] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a battery polarity determination circuit, a charger, and an electronic device that can reduce the possibility of damage and determine the battery polarity at low cost.

[0012] Technical solutions adopted to solve technical problems

[0013] In order to achieve the above-mentioned purpose, the battery polarity determination circuit of the present invention includes: a battery accommodating portion, the battery accommodating portion including a first contact and a second contact abutting against each electrode terminal of the accommodated battery; a control device, the control device is connected to a voltage lead-out point for drawing out the voltage of the battery from the battery accommodating portion through a resistor, and determines the polarity of the battery accommodated in the battery accommodating portion; a connection switching circuit, the connection switching circuit being able to switch between a first connection state in which the first contact is connected to the voltage lead-out point and the second contact is grounded and a second connection state in which the second contact is connected to the voltage lead-out point and the first contact is grounded; and a diode, the cathode of the diode being connected to a voltage reading point to which the resistor and the control device are connected, and the anode of the diode being grounded, the control device determining the polarity of the battery based on the voltage of the voltage reading point for the connection state of the connection switching circuit, the forward voltage of the diode being set so that the voltage of the voltage reading point is above the lower limit value of the absolute maximum rating of the control device.

[0014] Effects of the Invention

[0015] According to the present invention, a battery polarity determination circuit, a charger, and an electronic device capable of reducing the possibility of damage and determining the polarity of a battery at low cost can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a circuit diagram of a charger according to Embodiment 1 of the present invention.

[0017] Figure 2 It is a flowchart showing the control operation of the control device.

[0018] Figure 3 This is a circuit diagram of an electronic device according to Embodiment 2 of the present invention. DETAILED DESCRIPTION

[0019] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. In addition, the present invention is not limited to the contents described below, and can be implemented with any changes without changing the gist of the invention. In addition, the drawings used in the description of the embodiments schematically illustrate the structural components, and sometimes, in order to deepen the understanding, the parts are emphasized, enlarged, reduced or omitted, etc., without correctly indicating the scale, shape, etc. of the structural components.

[0020] <Implementation Method 1>

[0021] Figure 1 1 is a circuit diagram of a charger 1 according to Embodiment 1 of the present invention. The charger 1 according to this embodiment includes a battery storage section 2, a control device 3, a connection switching circuit 4, a "battery polarity determination circuit" including a resistor R and a diode D, and a power supply circuit 5. The charger 1 determines the polarity of the battery BAT stored in the battery storage section 2, that is, the connection direction of the battery BAT, and charges the battery BAT in the appropriate connection direction.

[0022] The battery receiving portion 2 includes a first contact T1 and a second contact T2 that abut against each electrode terminal of the battery BAT to be received. That is, in the battery BAT, when the positive terminal abuts against the first contact T1 and is received in the battery receiving portion 2, the negative terminal abuts against the second contact T2, and when the negative terminal abuts against the first contact T1 and is received in the battery receiving portion 2, the positive terminal abuts against the second contact T2. Here, in the present embodiment, the battery BAT is a nickel-metal hydride rechargeable battery with a nominal voltage of 1.2 [V].

[0023] The control device 3 is composed of, for example, a well-known microcomputer control circuit, and as described in detail later, controls the entire charger 1 as a whole, including polarity determination of the battery BAT and charging control of the battery BAT. In addition, the control device 3 of this embodiment has an AD converter (not shown) built in to convert the analog voltage on the circuit into a digital voltage and read it. Here, in this embodiment, the control device 3 is set to have a power supply voltage on the high potential side as V DD =5[V], the power supply voltage on the low potential side is V SS =0[V], and the allowed input voltage is V SS -0.3[V]≤V IN ≤V DD The range of +0.3[V] is generally the absolute maximum rating.

[0024] The connection switching circuit 4 is Figure 1A circuit for switching the connection state of the battery accommodating portion 2 accommodating the battery BAT between the voltage lead-out point P1 and the ground point GND shown. More specifically, the connection switching circuit 4 includes a first switch SW1, a second switch SW2, a third switch SW3, and a fourth switch SW4, for example, which are composed of field effect transistors (Field Effect Transistor: FET). One end of the first switch SW1 is connected to the first contact T1, and the other end is connected to the voltage lead-out point P1. One end of the second switch SW2 is connected to the second contact T2, and the other end is grounded. One end of the third switch SW3 is connected to the second contact T2, and the other end is connected to the voltage lead-out point P1. One end of the fourth switch SW4 is connected to the first contact T1, and the other end is grounded.

[0025] Therefore, the connection switching circuit 4 can switch between, for example, a first connection state in which the first contact T1 is connected to the voltage lead point P1 and the second contact T2 is grounded, and a second connection state in which the second contact T2 is connected to the voltage lead point P1 and the first contact T1 is grounded. In addition, the control device 3 controls the opening and closing of each switch of the connection switching circuit 4.

[0026] One end of the resistor R is connected to the voltage extraction point P1, and the other end is connected to the voltage reading point P2 which is a connection point with the control device 3. The resistor R limits the current flowing between the voltage extraction point P1 and the voltage reading point P2.

[0027] In this embodiment, the diode D is a Schottky barrier diode, the cathode of the diode D is connected to the voltage reading point P2, and the anode is grounded. In the diode D, when the voltage of the anode is higher than the voltage of the cathode and the specified forward voltage V F When the sum of the forward voltage V F is set so that the voltage V at the voltage reading point P2 P2 The lower limit value of the absolute maximum rating of the control device 3 is -0.3 [V] or more. In this embodiment, the forward voltage V F V F = 0.3 [V] Schottky barrier diode is used for the purpose of explanation, but a low V F Furthermore, when the lower limit value of the absolute maximum rating of the control device 3 is low, a rectifying element other than the Schottky barrier diode may be used.

[0028] The power circuit 5 outputs charging power for charging the battery BAT to the voltage lead-out point P1 based on the control of the control device 3. More specifically, the power circuit 5 is, for example, a DC-DC converter, which converts power supplied from an external power source (not shown) into a voltage suitable for charging the battery BAT based on the control of the control device 3 that monitors the state of the battery BAT.

[0029] Next, an example of a control procedure of the control device 3 for determining the polarity of the battery BAT accommodated in the battery accommodation portion 2 and charging the battery BAT will be described. Figure 2 2 is a flowchart showing the control operation of the control device 3. The control device 3 starts when the battery BAT is stored in the battery storage unit 2. Figure 2 In addition, at the start of the control, each switch of the connection switching circuit 4 is turned off, and the power supply circuit 5 does not output charging power.

[0030] When the control operation starts, the control device 3 controls the first switch SW1 and the second switch SW2 to be turned on, and controls the third switch SW3 and the fourth switch SW4 to be turned off (step S1). As a result, the battery storage portion 2 is in the first connection state in which the first contact T1 is connected to the voltage lead-out point P1 and the second contact T2 is grounded.

[0031] Here, when the positive terminal of the battery BAT is accommodated in the battery accommodation portion 2 in a direction abutting against the first contact T1, the voltage V at the voltage extraction point P1 is P1 The voltage of the battery BAT connected in the forward direction in the first connection state is about 1.2 [V]. At this time, in the circuit from the voltage extraction point P1 to the ground via the resistor R, the voltage reading point P2 and the diode D, since the reverse voltage is applied to the diode D, the current does not flow. Therefore, since it is not affected by the voltage drop at the resistor R, the voltage V at the voltage reading point P2 is P2 This is the same as the voltage at the voltage extraction point P1, which is approximately 1.2 [V].

[0032] Furthermore, when the negative terminal of the battery BAT is accommodated in the battery accommodation portion 2 in a direction abutting against the first contact T1, the voltage V at the voltage extraction point P1 is P1 The voltage of the battery BAT connected in the reverse direction in the first connection state is about -1.2 [V]. At this time, in the circuit from the voltage extraction point P1 to the ground via the resistor R, the voltage reading point P2 and the diode D, a forward voltage is applied to the diode D, so that a current flows. Therefore, the voltage V at the voltage reading point P2 is P2 As the voltage obtained by adding the voltage at the voltage extraction point P1 to the voltage drop at the resistor R, according to the forward voltage V of the diode D FThe magnitude of becomes -0.3 [V]. At this time, the resistor R having a resistance value r is used so that the current flowing from the diode D does not exceed the allowable current of the diode D.

[0033] Thus, the control device 3 controls the connection switching circuit 4 to the first connection state, and reads the voltage V at the voltage reading point P2. P2 , it is possible to determine whether the battery BAT is accommodated in the battery accommodation portion 2 in a state where the positive terminal is in contact with the first contact T1. More specifically, the control device 3 determines whether the voltage V at the voltage reading point P2 is P2 Is it within the specified voltage range (V MIN ≤V P2 ≤V MAX ) (step S2). Here, the prescribed voltage range is a range that specifies the voltage variation region of the normal battery BAT. In the case of the nickel-metal hydride rechargeable battery in this embodiment, for example, the lower limit value V MIN is set to 1.0 [V] as the discharge end voltage, and the upper limit value V MAX The charge end voltage is set to 1.3 [V].

[0034] When the voltage V at the voltage reading point P2 in the first connection state P2 If the voltage is within the specified range (YES in step S2), the control device 3 considers that the battery BAT is connected in the forward direction in the first connection state, controls the power supply circuit 5 to output charging power, and charges the battery BAT in the first connection state (step S3).

[0035] In addition, the control device 3 reads the voltage V at the voltage reading point P2 based on the voltage V P2 Monitor the voltage of the battery BAT (= the voltage V at the voltage extraction point P1) P1 = Voltage V at voltage lead point P2 P2 ), and based on the value of the voltage or its change ΔV and other indicators, it is determined whether the battery BAT has reached a fully charged state (step S4). The control device 3 continues to charge the battery BAT until the battery BAT reaches a fully charged state ("No" in step S4).

[0036] Furthermore, when the battery BAT reaches a fully charged state ("Yes" in step S4), the control device 3 stops the charging power provided by the power supply circuit 5 and controls the switches of the connection switching circuit 4 to be disconnected, thereby ending the charging of the battery BAT and completing a series of control steps. At this time, the control device 3 can notify the user that the charging is normally completed.

[0037] On the other hand, in step S2, when the voltage V at the voltage reading point P2 in the first connection state P2If the voltage is not within the specified voltage range ("No" in step S2), the control device 3 controls the first switch SW1 and the second switch SW2 to be turned off, and controls the third switch SW3 and the fourth switch SW4 to be turned on (step S5). As a result, the battery accommodating portion 2 is in the above-mentioned second connection state in which the second contact T2 is connected to the voltage lead-out point P1 and the first contact T1 is grounded.

[0038] Furthermore, the control device 3 controls the connection switching circuit 4 to the second connection state by reading the voltage V at the voltage reading point P2. P2 , it is possible to determine whether the battery BAT is accommodated in the battery accommodation portion 2 with the positive terminal in contact with the second contact T2. More specifically, the control device 3 determines the voltage V at the voltage reading point P2 in the second connection state. P2 Is it within the above-mentioned specified voltage range (step S6).

[0039] When the voltage V at the voltage reading point P2 in the second connection state is P2 If the voltage is within the prescribed range (YES in step S6 ), the control device 3 considers that the battery BAT is connected in the forward direction in the second connection state, and charges the battery BAT until the battery BAT is fully charged as described above (steps S3 and S4 ).

[0040] On the other hand, when the voltage V at the voltage reading point P2 in the second connection state P2 If the voltage is not within the specified range ("No" in step S6), the control device 3 considers that the battery BAT cannot be charged normally due to a fault in the battery BAT or poor contact of the battery BAT in the battery receiving portion 2, determines an abnormality (step S7), and completes a series of control steps. At this time, the control device 3 can notify the user that the charging is abnormally terminated.

[0041] When a rechargeable battery is frequently and repeatedly shallowly charged and discharged, the battery capacity may be significantly reduced due to the so-called memory effect, and the dischargeable capacity becomes substantially smaller. For example, the significant reduction in battery capacity caused by the memory effect can be eliminated by performing a cyclic repair discharge of deep discharge of the rechargeable battery. The battery polarity determination circuit of the present invention can also perform cyclic repair discharge without causing any damage to the battery. Figure 1 The circuit shown has a new structure added.

[0042] More specifically, when cyclic repair discharge is required, the control device 3 discharges the battery BAT to the discharge end voltage during the period from the time of determining the polarity of the battery BAT in step S2 or step S5 to the time of starting charging in step S3. That is, after determining the polarity of the battery BAT, the control device 3 controls the connection switching circuit 4 so as to be in a reverse biased connection state in which the positive terminal of the battery BAT in the first connection state or the second connection state is grounded.

[0043] For example, when it is determined that the positive terminal is in contact with the second contact T2, the control device 3 controls the first switch SW1 and the second switch SW2 to be turned on, and controls the third switch SW3 and the fourth switch SW4 to be turned off, thereby forming a first connection state. As a result, in the battery polarity determination circuit, a closed circuit is formed that sequentially connects the second contact T2, the second switch SW2, the diode D, the resistor R, the first switch SW1, and the first contact T1, so that the charging capacity of the battery BAT is consumed by the resistor R.

[0044] At this time, the control device 3 repeatedly switches and discharges between the above-mentioned reverse biased connection state and the disconnected state in which all switches are disconnected to disconnect the first contact T1 and the second contact T2 through PWM control, thereby performing cyclic repair discharge with a discharge current suitable for the characteristics of the battery BAT.

[0045] As described above, the charger 1 of the first embodiment of the present invention controls the connection switching circuit 4 for switching the connection state of the battery BAT, and can read the voltage V at the point P2 based on the voltage at the connection point between the resistor R and the diode D. P2 The polarity of the battery BAT is determined, and the battery BAT can be charged in an appropriate connection direction. At this time, since the circuit for determining the polarity of the battery BAT is composed of only relatively inexpensive components such as a resistor R and a diode D, it can be constructed inexpensively compared to a circuit using relatively expensive electronic components such as an optical coupler and an operational amplifier. In addition, since the mounting area on the circuit substrate can be reduced, it can contribute to miniaturization. In addition, in the charger 1 of the first embodiment of the present invention, the forward voltage V of the diode D is F It is set based on the absolute maximum rating of the control device 3, so regardless of the connection direction between the control device 3 and the battery BAT, it is possible to prevent a voltage exceeding the absolute maximum rating from being input to the control device 3. Therefore, according to the charger 1 of the first embodiment of the present invention, the possibility of damage can be reduced, and the battery polarity can be determined at a low cost.

[0046] <Implementation Method 2>

[0047] Next, refer to Figure 3As a second embodiment, an electronic device including the battery polarity determination circuit of the present invention will be described. Figure 3 1 is a circuit diagram of an electronic device 10 according to Embodiment 2 of the present invention. The circuit configuration of the electronic device 10 according to Embodiment 2 is different from that of Embodiment 1 in that a load device 20 is included instead of the power supply circuit 5 in the charger 1 of Embodiment 1. Hereinafter, the parts different from Embodiment 1 will be described, and the same reference numerals are given to the components common to Embodiment 1, and detailed descriptions thereof will be omitted.

[0048] When the battery BAT is accommodated in the battery accommodating portion 2, the electronic device 10 of the second embodiment operates by the power supplied from the battery BAT to the load device 20. Here, like the charger 1 of the first embodiment, the electronic device 10 determines the polarity of the battery BAT by the battery polarity determination circuit provided therein. Furthermore, the control device 3 controls the connection switching circuit 4 to the voltage V at the voltage reading point P2 in the first connection state or the second connection state. P2 The voltage of the battery BAT is connected, that is, the positive terminal of the battery BAT is connected to the first contact T1 , so that power is supplied from the battery BAT to the load device 20 .

[0049] Therefore, the electronic device 10 according to the second embodiment of the present invention can discharge the battery BAT in an appropriate connection direction based on the determination of the polarity of the battery BAT, regardless of the orientation of the battery BAT accommodated in the battery accommodation portion 2. In addition, in the electronic device 10, the circuit for determining the polarity of the battery BAT is composed only of relatively inexpensive components, and a voltage exceeding the absolute maximum rating is not input to the control device 3. Therefore, the electronic device 10 according to the second embodiment of the present invention can reduce the possibility of damage and can determine the polarity of the battery at a low cost.

[0050] The above is the description of the embodiments, but the present invention is not limited to the above embodiments. Figure 2 In the control step of controlling the first connection state in step S1 before controlling the second connection state in step S3, however, the order of step S1 and step S3 may be reversed. In addition, for example, in the above-mentioned embodiment 1, the voltage V of the voltage reading point P2 in the first connection state is shown as an example. P2 The control step of starting charging when the voltage is within the specified range (in Figure 2 However, the voltage V of the voltage reading point P2 in the first connection state may also be read. P2 After that, the voltage V at the voltage reading point P2 in the second connection state is immediately read. P2, so that in the initial stage of the control step, in addition to determining the polarity of the battery BAT, it is also determined whether charging is possible.

[0051] <Implementation Methods of the Invention>

[0052] A first aspect of the present invention is a battery polarity determination circuit, comprising: a battery accommodating portion, the battery accommodating portion including a first contact and a second contact abutting against respective electrode terminals of a battery accommodated therein; a control device, the control device being connected to a voltage lead-out point for drawing out the voltage of the battery from the battery accommodating portion via a resistor, and determining the polarity of the battery accommodated in the battery accommodating portion; a connection switching circuit, the connection switching circuit being capable of switching between a first connection state in which the first contact is connected to the voltage lead-out point and the second contact is grounded, and a second connection state in which the second contact is connected to the voltage lead-out point and the first contact is grounded; a diode, the cathode of the diode being connected to a voltage reading point to which the resistor and the control device are connected, and the anode of the diode being grounded, the control device determining the polarity of the battery based on the voltage of the voltage reading point for the connection state of the connection switching circuit, the forward voltage of the diode being set so that the voltage of the voltage reading point is above the lower limit value of the absolute maximum rating of the control device.

[0053] The battery polarity determination circuit controls so that each electrode terminal of the battery accommodated in the battery accommodation portion is connected to the voltage lead-out point or the ground through the connection switching circuit, and determines the connection direction of the battery in the battery accommodation portion, that is, the battery polarity, based on the voltage at the voltage reading point, which is the connection point between the resistor and the diode connected in series between the voltage lead-out point and the ground. At this time, the anode of the diode is grounded, the cathode is connected to the voltage reading point, and the forward voltage is set so that the voltage at the voltage reading point is equal to or higher than the lower limit value of the absolute maximum rating of the control device.

[0054] Therefore, since the circuit structure for determining the battery polarity is composed of only relatively cheap components such as resistors and diodes, the battery polarity determination circuit can be constructed cheaply compared to a circuit using relatively expensive electronic components such as an optocoupler and an operational amplifier. In addition, the mounting area on the circuit substrate can be reduced, thereby contributing to miniaturization. In addition, regardless of the connection direction with the battery, no voltage exceeding the absolute maximum rating will be input to the control device. Therefore, according to the battery polarity determination circuit of embodiment 1 of the present invention, the possibility of damage can be reduced, and the battery polarity can be determined at a low cost.

[0055] A battery polarity determination circuit according to a second aspect of the present invention is the battery polarity determination circuit according to the first aspect of the present invention, wherein the diode is a Schottky barrier diode.

[0056] According to the battery polarity determination circuit of the second embodiment of the present invention, since the voltage drop at the voltage reading point can be suppressed by the Schottky barrier diode with a low forward voltage even in the rectifying element, the possibility of damage to the control device caused by the voltage input to the control device can be further reduced.

[0057] A battery polarity determination circuit according to a third aspect of the present invention is the battery polarity determination circuit according to the first or second aspect of the present invention, wherein the resistance value of the resistor is set so that the current flowing from the diode does not exceed the allowable current of the diode.

[0058] According to the battery polarity determination circuit of the third aspect of the present invention, since the resistance value of the resistor is set so that a current exceeding the allowable current does not flow through the diode, the possibility of the diode being damaged due to the current input to the diode can be reduced.

[0059] The battery polarity determination circuit of the fourth mode of the present invention is that in any one of the first to third modes of the present invention mentioned above, when the voltage at the voltage reading point is not within the prescribed voltage range, whether in the first connection state or in the second connection state, the control device performs an abnormality determination on the battery.

[0060] According to the fourth mode of the battery polarity determination circuit of the present invention, since the battery voltage can be read by switching the connection state between the battery and the control device in the connection switching circuit, it can prevent the battery from being charged in an abnormal state where the battery voltage is not within the specified voltage range.

[0061] A charger according to a fifth aspect of the present invention comprises the battery polarity determination circuit according to any one of the first to fourth aspects of the present invention; and a power supply circuit that outputs charging power for charging the battery to the voltage lead-out point based on control by the control device. After determining the polarity of the battery, the control device charges the battery in a connection state in which the voltage at the voltage reading point in the first connection state or the second connection state becomes the voltage of the battery.

[0062] According to the charger of the fifth aspect of the present invention, charging can be performed in a proper connection state between the power circuit and the battery based on the polarity of the battery determined by the battery polarity determination circuit, and the possibility of damage and cost can be reduced.

[0063] The charger of the sixth mode of the present invention is in the fifth mode of the present invention mentioned above, wherein the control device, during the period from determining the polarity of the battery to starting charging, utilizes the reverse biased connection state in which the positive terminal of the battery is grounded in the first connection state or the second connection state to discharge the battery to the discharge end voltage.

[0064] The charger of the sixth aspect of the present invention forms a closed circuit that consumes the battery capacity of the battery in the resistor when the positive terminal of the battery is grounded in the first connection state or the second connection state according to the circuit structure of the battery polarity determination circuit. Therefore, the charger of the sixth aspect of the present invention can perform cyclic repair discharge of the battery in the period from determining the battery polarity to starting charging without adding a new structure.

[0065] The charger of the seventh aspect of the present invention is in the sixth aspect of the present invention, wherein the control device controls the discharge current of the battery through PWM control, and the PWM control switches between the reverse biased connection state and the disconnection state in which both the first contact and the second contact are disconnected.

[0066] According to the charger of the seventh aspect of the present invention, the discharge current of the battery can be controlled by PWM control of the connection switching circuit, and cyclic repair discharge suitable for the battery characteristics can be performed.

[0067] An electronic device according to an eighth aspect of the present invention comprises the battery polarity determination circuit according to any one of the first to fourth aspects of the present invention; and a load device that operates using the discharge power of the battery output to the voltage lead-out point. After determining the polarity of the battery, the control device discharges the battery in a connection state in which the voltage at the voltage reading point in the first connection state or the second connection state becomes the voltage of the battery.

[0068] The electronic device of the eighth aspect of the present invention can discharge the battery along the appropriate connection direction based on the determination of the polarity of the battery, regardless of the orientation of the battery contained in the battery containing portion. In addition, in the electronic device, the circuit for determining the polarity of the battery is composed only of relatively cheap components, and the voltage exceeding the absolute maximum rated value is not input to the control device. Therefore, according to the electronic device of the eighth aspect of the present invention, the possibility of damage can be reduced, and the battery polarity can be determined at a low cost.

[0069] Description of symbols

[0070] 1 Charger

[0071] 2 Battery compartment

[0072] 3 Control device

[0073] 4. Connect the switching circuit

[0074] 5 Power Circuit

[0075] 10 Electronic devices

[0076] 20 Loading device

[0077] BAT Battery

[0078] T1~T2 First contact~Second contact

[0079] SW1~SW4 First switch~Fourth switch

[0080] R Resistor

[0081] D Diode

[0082] P1 Voltage lead point

[0083] P2 Voltage reading point.

Claims

1. A battery polarity determination circuit, characterized in that: include: A battery receiving portion, the battery receiving portion including a first contact and a second contact for contacting respective electrode terminals of a received battery; a control device connected to a voltage lead-out point for leading the voltage of the battery from the battery receiving portion through a voltage reading point and a resistor in sequence, and determining the polarity of the battery received in the battery receiving portion; a connection switching circuit capable of switching between a first connection state in which the first contact is connected to the voltage lead-out point and the second contact is grounded, and a second connection state in which the second contact is connected to the voltage lead-out point and the first contact is grounded; as well as a diode, the cathode of which is connected to the voltage reading point and the anode of which is grounded, the control device determines the polarity of the battery based on the voltage of the voltage reading point for the connection state of the connection switching circuit, The forward voltage of the diode is set so that the voltage at the voltage reading point is equal to or greater than a lower limit value of the absolute maximum rating of the control device.

2. The battery polarity determination circuit according to claim 1, characterized in that: The diode is a Schottky barrier diode.

3. The battery polarity determination circuit according to claim 1 or 2, characterized in that: The resistance value of the resistor is set so that the current flowing from the diode does not exceed the allowable current of the diode.

4. The battery polarity determination circuit according to claim 1, characterized in that: When the voltage at the voltage reading point is not within a prescribed voltage range in both the first connection state and the second connection state, the control device determines that the battery is abnormal.

5. A charger, characterized in that: include: The battery polarity determination circuit as claimed in claim 1; as well as a power supply circuit that outputs charging power for charging the battery to the voltage lead-out point based on control of the control device, The control device charges the battery in a connection state in which the voltage of the voltage reading point in the first connection state or the second connection state becomes the voltage of the battery after determining the polarity of the battery.

6. The charger according to claim 5, characterized in that: The control device discharges the battery to a discharge end voltage using a reverse bias connection state in which the positive terminal of the battery is grounded in the first connection state or the second connection state during a period from determining the polarity of the battery to starting charging.

7. The charger according to claim 6, characterized in that: The control device controls the discharge current of the battery by PWM control, which switches between the reverse biased connection state and the disconnection state in which the first contact and the second contact are both disconnected.

8. An electronic device, characterized in that: include: The battery polarity determination circuit as claimed in claim 1; as well as a load device that operates using the power of the battery output to the voltage lead-out point, After determining the polarity of the battery, the control device discharges the battery in a connection state in which the voltage at the voltage reading point in the first connection state or the second connection state becomes the voltage of the battery.

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