JP3225586B2 - Charging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging apparatus, and more particularly to a charging apparatus for monitoring the state of charge of a secondary battery to be charged.
The present invention relates to a charging device that outputs the state of charge.

[0002]

2. Description of the Related Art A secondary battery (battery) is used as a driving source in a video tape recording / reproducing apparatus (VTR) integrated with a camera. As the power consumption of the secondary battery progresses, the secondary battery is removed from the VTR and charged by a charging device. It is necessary to charge the secondary battery according to charging characteristics according to the type of the secondary battery.

[0003]

Normally, a secondary battery used for a VTR in a charging device is charged for a specified time according to the charging characteristics of the secondary battery. The way it is displayed is not done. As a result, charging is often performed up to the overcharged state, and there are problems such as wasting of charging time and wasting of power due to overcharging.

The present invention solves such a problem. In addition to charging a secondary battery in accordance with the charging characteristics of the secondary battery, the present invention simply monitors the state of charge of the secondary battery and charges the battery. It is an object to provide a charging device capable of outputting a state.

[0005]

According to the present invention, there is provided a charging apparatus for charging a secondary battery from a low voltage state in accordance with the charging characteristics of the secondary battery. There is provided a charging device comprising: means, a charge state monitoring means for monitoring a charge state according to the charge characteristic thereof, and means for outputting a charge state of the secondary battery from a charge state monitoring result of the charge state monitor means. You.

[0006] The secondary battery is a lithium-based secondary battery, the charging state monitoring unit of the lithium-based secondary battery
Until the terminal voltage reaches the specified charging voltage from the low voltage state
Monitor the terminal voltage of the lithium secondary battery at
After the charging voltage of the lithium secondary battery reaches a certain value,
The charging means charges the rechargeable battery while charging is momentarily interrupted.
The above-mentioned charging state monitoring means performs the instantaneous interruption by the above-mentioned charging means.
And previous voltage of the above lithium secondary battery
A method for monitoring the voltage difference from the voltage of the
The stage charges the lithium secondary battery based on the voltage difference.
Output power status.

[0007] When the secondary battery is a nickel-based secondary battery, the charge state monitoring means is provided for the nickel-based secondary battery.
After the terminal voltage reaches the specified level from the low voltage state,
The point at which the pressure drops is detected, and then the nickel-based secondary
Means for monitoring the charging current of the battery and outputting the charging state
Responds to the state of decrease in the charging current of the nickel-based secondary battery.
Then, the state of charge of the nickel-based secondary battery is output.

[0008]

The charging means in the charging device performs charging according to the charging characteristics of the secondary battery. The charging state monitoring means monitors the charging state according to the charging characteristics. The charge state output means outputs the charge state of the secondary battery from the result of charge state monitoring by the charge state monitor means. As a result, charging is performed according to the secondary battery, the charging state based on the charging characteristics is monitored, and the charging state of the secondary battery is output to, for example, an LED based on the monitoring result.

When the secondary battery is a lithium secondary battery, the charge state monitoring means monitors the voltage of the secondary battery until a predetermined charge voltage is reached, and then monitors the charge current of the lithium battery. I do. The means for outputting the state of charge outputs the state when the charge voltage reaches a predetermined voltage, and then outputs the state of charge according to the current value of the secondary battery. Alternatively, the charging state monitoring means monitors the voltage of the lithium-based battery until a predetermined charging voltage is reached, and the charging means charges the secondary battery while interrupting the charging. The means for monitoring the decrease in the voltage of the lithium secondary battery and outputting the state of charge outputs the state when the charge voltage reaches a predetermined voltage, and thereafter, based on the amount of decrease in the voltage of the secondary battery. To output the state of charge of the lithium battery.

When the secondary battery is a nickel-cadmium battery or a nickel-based secondary battery such as nickel-hydrogen, the state-of-charge monitoring means reduces the voltage of the nickel-based battery after the voltage reaches a predetermined level. Means for monitoring the current of the nickel-based battery and then outputting the state of charge, and outputs the state of charge when the voltage of the nickel-based battery drops after the voltage reaches a predetermined voltage. After that, the state of charge is output according to the current value of the nickel-based battery.

[0011]

FIG. 1 shows a basic configuration of a charging apparatus according to the present invention.
The charging device includes a charging unit 1 for charging the secondary battery 7, a charging state monitoring unit 3, and a charging state output unit 5. The charging means 1 performs charging by a charging method according to the charging characteristics of the secondary battery 7. The charging state monitoring means 3 monitors the charging state of the secondary battery 7 in cooperation with the charging means 1. Charge state output means 5
Outputs the state of charge of the secondary battery 7 in cooperation with the state-of-charge monitoring means 3.

FIG. 2 is an external perspective view of the charging device shown in FIG. The case 11 of the charging device displays a secondary battery mounting portion 13 in which the secondary battery 7 is accommodated, a charging terminal portion 17 to which a power terminal of the secondary battery 7 is connected, and a state of charge of the secondary battery 7. An LED display unit 15 is provided. A charging circuit 20 and a microcomputer 30, which will be described later, are provided inside the case 11 of the charging device. A cable 19 connected to an AC power supply (not shown) is connected to a charging circuit 20 in the case 11 of the charging device. In this example, the LED display unit 15 includes an EMPTY display LED 151 for displaying the state of charge of the secondary battery 7 and a 70% charge display LE.
D152, an 80% charge indicating LED 153, a 90% charge indicating LED 154, and an overcharge indicating LED 155.

An operation of charging the lithium battery 71 will be described as a first example of the secondary battery 7. FIG. 3 is a graph showing the charging characteristics of the lithium battery 71. Initial time t0
In the battery charging voltage V _b is the voltage V0 of the lithium battery 71, the battery charging current I _b is a current I0 (maximum current I _MAX). When charging is started, first, the terminal voltage V (battery charging voltage _Vb ) of the lithium battery 71 increases. Upon reaching the time t1, the battery charging voltage V _b of the lithium battery 71 reaches the saturation voltage V _SAT1, battery charging current I _b starts to decrease. Thereafter, as the time elapses, the battery charging current _Ib gradually decreases while the battery charging voltage _Vb remains constant.

The charging device charges the lithium battery 71 according to the charging characteristics shown in FIG. FIG. 4 shows a specific circuit configuration of the charging device shown in FIG. The charging device shown in FIG.
0, a microcomputer 30 functioning as a part of the charge state monitoring means 3 and the charge state output means 5, and
Charge state output means 5 in cooperation with microcomputer 30
Has an LED display unit 15 functioning as a part of the LED display unit.
The charging circuit 20 includes an AC / DC conversion circuit 21 that inputs AC power from an AC power supply (not shown) such as a 100 V commercial power supply via a cable 19 and converts the AC power into a DC voltage.
Switching regulator circuit 2 for switching DC voltage from DC conversion circuit 21 to adjust the voltage to a predetermined voltage
2. It has a smoothing circuit 23 for smoothing the output voltage of the switching regulator circuit 22. The charging circuit 20 further includes a control transistor 25 controlled by the microcomputer 30, a backflow prevention diode 26, and a voltage conversion resistor 27. Charging terminal 1
7, a lithium battery 71 is connected.

The microcomputer 30 functions as the charged state monitoring means 3 and the charged state output means 5 as described above. The operation of the microcomputer 30 will be described with reference to the flowchart shown in FIG. Step S11 : The microcomputer 30 inputs the state of a charging start switch (not shown), turns on the control transistor 25, and starts charging the lithium battery 71 from the charging circuit 20. Further the microcomputer 30 inputs the battery charging voltage V _b of the lithium battery 71 to be applied via the charging terminal unit 17 to the terminal 30c for monitoring the battery charging voltage V _b. Steps S12 and S13 : microcomputer 30
Receives the battery charging voltage V _b from the terminal 30c, the battery charging voltage V _b to detect whether the host vehicle has reached the saturation voltage V _SAT1 (step S12). When the battery charging voltage V _b has not reached the saturation voltage V _SAT1 is, EMPTY the microcomputer 30 in the LED display section 15
The display LED 151 is turned on, and the monitoring of the battery charging voltage _Vb is continued (step S13). EMPTY display L
The ED 151 is an LED that indicates a state of “EMPTY (empty)” in which the terminal voltage (battery charging voltage V _b ) of the lithium battery 71 has not reached the saturation voltage V _SAT1 .

[0016] Step S12, S14, S15: at time t1 shown in FIG. 3, the microcomputer 30 when the battery charging voltage V _b has reached the saturation voltage V _SAT1 proceeds to the process at step S14 (step S1
2). The microcomputer 30 inputs the output voltage of the amplifier 28 which amplifies the terminal voltage of the voltage converting resistor 27 for converting the battery charging current I _b to the voltage from the terminal 30b battery charging current I _b is 3 It is detected whether or not the current I2 shown has been reached (step S14). That is, the microcomputer 30 calculates the battery charging voltage V _b
There until time to reach the saturation voltage V _SAT1 t1 monitors the battery charging voltage V _b, the time t1 or later after the battery charging voltage V _b has reached the charge saturation voltage V _SAT1 monitoring the battery charging current I _b. When the battery charging current _Ib is equal to the current I2
When not reached, the microcomputer 30 turns on the 70% charging display LED152 off the EMPTY display LED 151 (step S15), and continues to monitor the battery charging current I _b. 70% charge display LED
The LED 152 indicates to the user that the lithium battery 71 has been charged to approximately 70% from the characteristics shown in FIG.
It is.

Steps S14, S16, S17 : The microcomputer 30 monitors the output voltage of the amplifier 28,
At time t2 shown in FIG. 3, upon detecting that the battery charging current I _b of the lithium battery 71 has fallen to the current I2 (step S14), and further the battery charging current I
_b is detected to drop to the current I3 (step S
16). When the battery charging current I _b has not decreased to a current I3 is, the microcomputer 30 instead of the display of the 70% charging display LED 152, 80% charge display LE
D153 is lit, and the state of charge of the lithium battery 71 is 8
The user is notified that the battery charge has reached about 0% (step S17), and monitoring for detecting that the battery charging current _Ib has dropped to the current I3 is continued.

Steps S16, S18, S19 : The microcomputer 30 monitors the output voltage of the amplifier 28,
At time t3 shown in FIG. 3, upon detecting that the battery charging current I _b of the lithium battery 71 has fallen to the current I3 (step S16), and further the battery charging current I
_b is detected to decrease to the current I4 (step S
18). When the battery charging current I _b has not decreased to the current I4, the micro computer 30 instead of the display of the 80% charging display LED 153, 90% charge display LE
D154 is lit, and the state of charge of the lithium battery 71 is 9
The user is notified that it has reached about 0% (step S19), and the monitoring operation for detecting that the battery charging current _Ib has decreased to the current I4 is continued. Steps S18 and S20 : The microcomputer 30 monitors the output voltage of the amplifier 28, and monitors the time t4 shown in FIG.
In, upon detecting that the battery charging current I _b of the lithium battery 71 has fallen to the current I4 (step S1
8) Instead of turning on the 90% charge display LED 154, the overcharge display LED 155 is displayed (step S2).
0). The overcharge display LED 155 is an LED that indicates to the user that the lithium battery 71 has been sufficiently charged.

With the above operation, the charging operation for the lithium battery 71 according to the charging characteristics shown in FIG. 3 is completed. The microcomputer 30 detects that the user has turned off the charging start switch (not shown), turns off the control transistor 25, and stops charging from the charging circuit 20.

As described above, the user places the lithium battery 71 in the secondary battery mounting section 13 such that the terminal of the lithium battery 71 is connected to the charging terminal section 17 shown in FIG. The lithium battery 71 is charged by mounting it and turning on a charging start switch (not shown), and the user can recognize the state of charge by observing the LED display unit 15.

In the above embodiment, the lithium battery 71
Although the example in which the charge start and the charge end to the battery are performed using the charge start switch has been described, the above-described charging operation can be performed without using the charge start switch. The operation will be described. The microcomputer 30 is used as an initial condition.
When activated, the control transistor 25 is turned on to be in a chargeable state. The microcomputer 30 is a battery charging voltage V _b as described above, while monitoring the battery charging current I _b, performs display control of the LED display section 15. The microcomputer 30 determines that the state of charge of the lithium battery 71 is the battery charging current I _{b at} time t4 shown in FIG.
When the voltage falls to the current I4 or less, the control transistor 25 is automatically turned off and charging is automatically terminated.

FIG. 6 shows another charging characteristic of the lithium battery. FIG. 6 shows that the battery charging voltage _Vb is the charging / saturating voltage V
After time t1 when _SAT2 is reached, lithium battery 7
When the charging current is turned off to 1, the battery charging voltage _Vb decreases in accordance with the magnitude of the charging current at that time. For example, when the charge current of the lithium battery 71 is turned off, the drop amount V1 of the battery charge voltage _{Vb from} the saturation voltage _VSAT2 when the battery charge current _Ib is large immediately after the time t1 is the battery charge in the subsequent time. charging current I _b of magnitude drop amount greater than V2 from saturation voltage V _SAT2 when lowered. The microcomputer 30 shown in FIG. 4, until time t1 monitors the battery charging voltage V _b, then, by identifying the amount of decrease in the battery charging voltage V _b when turning off the charging current, the lithium battery 71 Is determined.

FIG. 7 is a flowchart showing a charge state monitoring operation of the lithium battery 71 based on the charge characteristics shown in FIG. Steps S31 to S33 : Step S11 shown in FIG.
Same as S12. Step S34 to S36: the microcomputer 30 after the time t1 shown in FIG. 6, first enter the battery charging voltage V _b at that time (step S34). Normally, this voltage is the saturation voltage V _SAT2 . Microcomputer 3
A value of 0 causes the control transistor 25 to be momentarily interrupted to stop charging the lithium battery 71 instantaneously, so that the charging current is turned off. While the charging current is off, the microcomputer 30 inputs the battery charging voltage _Vb .
Immediately thereafter, the microcomputer 30 turns on the control transistor 25 to restart charging the lithium battery 71 (steps S35 and S36).

[0024] Step S37, S38: microcomputer 30 immediately after the battery charging voltage V _b immediately before turning off the control transistor 25 battery charging voltage V _b
Then, the voltage difference (the amount of decrease) of the voltage is detected (step S37). Microcomputer 3
0 compares the magnitude of the voltage drop amount with a value stored in advance to determine the charge state of the lithium battery 71 according to the voltage difference, and determines the corresponding LE in the LED display unit 15.
D is turned on (step S38). With this, LED
The display unit 15 displays L according to the state of charge of the lithium battery 71.
ED lights up. Step S39 : The microcomputer 30 is delayed for a predetermined time. This delay operation is performed by turning off the charging current and delaying by the period of time that defines the operation of detecting the voltage difference as described above. Step S40 : The microcomputer 30 repeats the above operation until it is determined that the charging of the lithium battery 71 is completed.

FIG. 8 is a graph showing charging characteristics of a nickel-cadmium battery or a nickel-based battery such as nickel-hydrogen. The charging characteristics of a secondary battery differ depending on the type of the secondary battery. A charging device similar to that shown in FIG. 3 can be applied to a charging device for a nickel-cadmium battery, but its charging voltage and charging current are different from those of the lithium battery 71. In the nickel-cadmium battery 73 and the like, the charging voltage and the charging current are also different from those of the above-described lithium battery 71, but the battery charging voltage _Vb is changed at time t1.
At the time when the voltage reaches the predetermined voltage -.DELTA.V. Therefore, when charging a nickel-cadmium battery or nickel-metal hydride, “−Δ
V method ".

The microcomputer 30 first monitors the battery charging voltage _Vb to detect the above-mentioned -ΔV, and determines that the charging of the nickel-cadmium battery 73 is at a predetermined level.
For example, it is detected that the battery has reached 70%, and thereafter, the battery charge current _Ib is monitored, and the charge state of the nickel-cadmium battery is displayed on the LED display unit 15 from the reduced state. Other operations are the same as the charging operation in the above-described lithium battery.

As described above, the charging device of the present invention has been described as charging a lithium battery or a nickel-based battery as a secondary battery. Charging of other secondary batteries is performed in the same manner as described above. Perform according to. As described above, according to the present invention, charging is performed in accordance with the charging characteristics of the secondary battery to be charged, the charging state is monitored based on the charging characteristics, and the charging state is displayed on the LED display unit 15.
For example, it is displayed in a state that can be easily recognized by the user.
The device that outputs the state of charge of the secondary battery is LE
Instead of the discrete display mode by the D display unit 15, continuous% display can be performed. Alternatively, the state of charge may be displayed on a display device such as a CRT instead of the LED, or may be output to a printer or the like instead of the display device.

When the secondary battery is used in a camera-integrated VTR or the like, the charging device described above can be incorporated in the camera-integrated VTR. In this case, the charging device can display the state of charge of the secondary battery such as a viewfinder of the VTR while charging the secondary battery.

[0029]

As described above, according to the charging apparatus of the present invention, charging is performed according to the charging characteristics of the secondary battery, and the state of charge is monitored according to the charging characteristics of the secondary battery. Based on the result of monitoring the state of charge, the state of charge of the secondary battery can be displayed in a form that can be easily understood, and effective charging can be performed for the user. In addition, the user can stop the charging at an appropriate timing by monitoring the charging state display, or the charging can be automatically stopped by the control means in the charging device, resulting in unnecessary power consumption. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration of a charging device of the present invention.

FIG. 2 is an external perspective view of an embodiment of the charging device shown in FIG.

FIG. 3 is a characteristic diagram showing a charging characteristic as a first example when a secondary battery is a lithium battery and its charging state monitoring condition.

FIG. 4 is a diagram showing a circuit configuration of a charging device as a first embodiment of the charging device of the present invention for performing charging based on the charging method shown in FIG. 3 and monitoring the charging;

5 is a flowchart showing an operation process of the charging device shown in FIG.

FIG. 6 is a characteristic diagram showing a charge characteristic and a charge state monitoring condition as a second example when the secondary battery is a lithium battery.

FIG. 7 is a flowchart showing an operation process of the charging device shown in FIG. 4 based on the charging method shown in FIG.

FIG. 8 is a characteristic diagram showing a charge characteristic and a charge monitoring condition as a first example when the secondary battery is a nickel-cadmium battery.

[Explanation of symbols]

 1 ··· Charging means, 3 ·· Charging state monitoring means, 5 ··· Charging state output means, 7 ··· Secondary battery, 11 ·· Charging device case, 13 ··· Secondary battery mounting part, 15 ·· LED Display unit, 17 charging terminal unit, 19 cable, 20 charging circuit, 21 AC / DC conversion circuit, 22 switching regulator circuit, 23 smoothing circuit, 25 control transistor, 26 .. Diode for backflow prevention, 27 .. Resistor for voltage conversion, 28 .. Amplifier, 30 .. Microcomputer, 71 .. Lithium battery, 73 .. Nickel cadmium battery, 75. Nickel hydrogen battery, 151..EMPTY display LED, 152..70% charge display LED, 153..80% charge display LED, 154..90% charge display LED, 155..overcharge Display LED.

Claims (2)

(57) [Claims] A charging means for charging the lithium secondary battery from a low voltage state in accordance with a charging characteristic of the lithium secondary battery; a charging state monitoring means for monitoring a charging state in accordance with the charging characteristic; Means for outputting the state of charge of the lithium-based secondary battery from the result of monitoring the state of charge in the state-of-charge monitoring means. A charging apparatus for a lithium-based secondary battery comprising: The terminal voltage of the lithium secondary battery is monitored until the terminal voltage of the battery reaches a predetermined charging voltage from the low voltage state, and after the charging voltage of the lithium secondary battery reaches a constant value, the charging means Charges the secondary battery while interrupting the charging, and the charging state monitoring means controls the voltage between the previous voltage and the current voltage of the lithium secondary battery at each instantaneous interruption by the charging means. Monitor means for outputting the charged state the charging device of the lithium secondary battery to output a state of charge of the secondary batteries based on the voltage difference. A charging means for charging the nickel-based secondary battery from a low voltage state in accordance with the charging characteristic of the nickel-based secondary battery; a charging state monitoring means for monitoring the charging state in accordance with the charging characteristic; Means for outputting the state of charge of the nickel-based secondary battery from the state-of-charge monitoring result of the state-of-charge monitoring means. Means for detecting when the terminal voltage of the battery reaches a predetermined level from the low voltage state and then lowering the voltage, monitoring the charging current of the nickel-based secondary battery, and outputting the charging state,
An apparatus for charging a nickel-based secondary battery that outputs a state of charge of the nickel-based secondary battery in accordance with a state of decrease in the charging current of the nickel-based secondary battery.