JPS62247727A - Charged quantity indicating circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a charge amount display circuit, and more particularly to a circuit that displays the charge state of a rechargeable battery built into a small electrical device.

Conventionally, this type of display circuit has been used solely to display whether or not charging is being performed by lighting a light emitting diode in conjunction with the start of charging. However, since such information is obvious when one sees that the device is plugged into an outlet, it only serves as a warning to prevent overcharging, and is not very necessary as a charging display.

The present invention has been made in view of the above-mentioned problem, and it is possible to generate a pulse signal corresponding to the charging time, integrate the pulse signal with a counter, and display the integrated value. It is an object of the present invention to provide a charge amount display circuit that displays a display proportional to the charge amount of a rechargeable battery and allows the state of a rechargeable battery to be properly grasped at all times.

The present invention will be specifically described below based on the embodiments shown in the drawings.2) Explain in detail.

Although the drawings show an example in which the present invention is implemented in an electric shaver, it is needless to say that the present invention is not limited to this and can be implemented in charging circuits of various small rechargeable electric appliances such as tape winders and flashlights.

As shown in FIGS. 1 to 3, an electric shaver 1 embodying the present invention is provided with an outer cutter 3 that is removably attached to the upper part of a main body case 2, and an inner cutter 4 that is inscribed in the outer cutter 3 and can freely reciprocate. A motor 5 for reciprocating the inner cutter 4 and a battery 6 for supplying electric power to the motor 5 are housed inside the main body case 2.

The battery 6 is a rechargeable battery such as a nickel-cadmium battery that can withstand charging and discharging multiple times, and in this embodiment, the battery capacity is 5.
In addition to using an AA type battery of approximately 00 mAh, a charging section 7 is provided at the bottom of the main body case 2, so that the battery 6 can be charged directly from a commercial AC power source.

The charging unit 7 includes a plug blade 9 that can be retracted from the lower end of the two-body case 2, and converts the commercial AC voltage inputted from the plug blade 9 into a predetermined charging voltage by a charging circuit 12 including an inverter circuit. Further, on the output side of the charging circuit 11, a battery 6 and a switching section 12 that regulates the timing of energizing the battery 6 are connected in series.

The switching unit 12 is an NPN type switching transistor, and its base end is connected to the cathode side of a light emitting diode 16 for displaying charging time arranged on the front face 8 of the main body case 2, and the diode 16 is energized during charging. At the same time as the light is turned on, the switching section 12 is turned on and the two batteries 6 are connected to the charging circuit 11 to enable charging.

Both ends of the battery 6 are connected to a DC-DC connector 17 that supplies a predetermined DC voltage to the electronic circuit described below. When this is detected, a voltage detection unit 18 is connected which generates a reset signal to return all circuits to their initial states. Further, both ends of the battery 6 are connected to both ends of the motor 5 via a main switch 13 placed in the center of the front of the main body case 2, and the power is supplied from the battery 6 to the motor 5 in conjunction with the on/off operation of the main switch 13. The timing is regulated.

The present invention detects when the battery 6 is charged, when the motor 5 is driven, and when the device 1 is stopped.

It is characterized by the configuration of the display circuit 14 that displays the amount of charge in the battery 6.

FIG. 2 schematically shows the display circuit 14, which detects the generation rate and generation timing of pulses output from the pulse signal generator 15 and output from the charging timing detector 19 and the discharging timing detector 20. In addition to being controllable with a signal, the number of output pulses generated is stored in the storage unit 21 during charging.
By adding and storing the value in , and conversely, at the time of discharging, the stored value in the storage unit 21 is subtracted at a rate proportional to the load current.

The current amount of charge in the battery 6 is always stored in the storage unit 21 as a value proportional to the amount of charge.

The count value in the storage section 21 is outputted to the display section 22 as appropriate, so that the current value of the charge amount can be displayed.

That is, this type of rechargeable battery 6 usually has a terminal voltage of 1.0.
Approximately 8 seconds after the voltage drops below V and the capacity is completely exhausted.
The charging type flow rate is set so that the battery becomes fully charged in a few hours.On the other hand, when discharging is performed with the motor 5 of the electric shaver 1 as a load, the capacity of the battery increases after approximately 40 minutes of continuous operation, although it varies depending on the discharge current value. Furthermore, even when the motor 5 is stopped, the capacity of the battery 6 gradually decreases due to the maintenance current of the circuit.

Therefore, the storage unit 21 is configured with an up/down counter,
At the time of charging, the signal output from the charging time detection section 19 is inputted to the control terminal of the counter 21, and the counter 21 is made to be an up counter.

The generation rate of charging pulses output from the pulse signal generator 15 is set so that the pulse count number in the counter 21 reaches the set value in 8 hours.

On the other hand, when the electric shaver 1 is used, that is, when the battery 6 is discharged, the output signal from the charging timing detection section 19 disappears.
The counter 21 serves as a down counter, contrary to the above.

Here, a frequency divider 28 with a variable frequency division ratio is disposed between the pulse signal generator 15 and the counter 21, and the frequency division ratio of the frequency divider 28 is changed in accordance with the amount of discharge current. The total number of pulses accumulated and stored in the counter 21 is
A value proportional to the amount of charge currently stored in the battery 6 is constantly stored in the counter 21 by subtracting with a variable discharge pulse that has a higher frequency than during charging and corresponds to the amount of load current. Therefore.

By displaying these i and a values on the predetermined display section 22, the current capacity of the battery 6 can be constantly grasped.

In a normal charging circuit, only the above-mentioned charging and motor driving times are a problem, but in this embodiment, the value stored in the counter is held even when the motor 5 is stopped, so the current is reduced, albeit slightly. is consuming. Therefore, in order to correct this current, a self-discharge pulse is generated at extremely long time intervals when the device is stopped, and the stored value in the counter 21 is subtracted by this pulse.

To explain the above configuration using more specific numerical examples, the pulse signal generating section 15 includes three sets of pulse generators 23, 24, 25 for charging, discharging, and self-discharging, and a pulse switching section 27. , pulse signals having generation rates individually set for each of the pulse generators 23, 24, and 25 are selectively sent to the frequency dividing section 28 by the pulse switching section 27.

The pulse switching unit 27 is configured by combining a plurality of logic gate circuits, for example, and receives a charging timing signal extracted from the charging timing detecting unit 19 by waveform shaping the output of the charging circuit 11, and a motor rotation speed detecting unit 31 to be described later. It switches in conjunction with the application of the zero rotation detection signal output from the motor and indicating when the motor is stopped.

In other words, both the charging timing signal and the zero rotation detection signal are "1".
In this case, the charging pulse generator 23 is selected, and both "
In the case of "O", the discharge pulse generator 24 is selected.Furthermore, in the case where only the zero rotation detection signal is "1", the self-discharge pulse generator 25 is selected and connected to the frequency dividing section 28, respectively.

The frequency divider 28 includes in series a first frequency divider 29 composed of a four-stage binary counter and a second frequency divider 30 composed of a six-stage binary counter. On the output side of the second frequency divider 30, the pulse signal inputted to the second frequency divider 30 is frequency-divided to 1/2In, that is, 1/1024, and taken out.

Further, if the up/down counter 21 used as a memory for the amount of charge is configured with eight binary stages, the maximum count will be 28-1, that is, 255.

Here, it is 8 hours when the upper 4 bits of the counter 21 become "L", that is, when 240 pulses have been counted, and in order to stop charging when 255 pulses have been counted, 8 hours - 2 , 8×104 seconds, the pulse rate l·Pl of the charging pulse output from the charging pulse generator 23 is.

h = 2.8 XIO' / (255x1024)
! ;o,i SeC, and it can be seen that by generating one pulse from the charging pulse generator 23 about every 0.1 seconds, the counter 21 becomes an 8-hour timer.

On the other hand, in this type of small electrical equipment, a DC motor that uses a permanent magnet in the field is often used as the motor 5.
Therefore, as shown in FIG. 4, as the torque T increases due to the accumulation of hair debris, etc.

The load current (2) supplied to the motor 5 during driving increases.

Furthermore, such an increase in the load current I appears as a decrease in the rotational speed n of the motor 5, and therefore, by detecting an increase or decrease in the motor rotational speed n, an increase or decrease in the load current I can be indirectly determined. Furthermore, an increase in the load current ■ will lead to a decrease in the continuous drive time of the motor after full charge, so by setting the capacity of the battery 6 and motor 5, the relationship between the motor rotation speed n and the continuous drive time of the motor can be determined by experiment or calculation. Seeking a relationship.

The solid line curve in FIG. 5 shows an example of such a relationship, and the broken line approximates the curve with a stepped straight line. From this result, the magnitude of the rotation speed n of the motor 5 is detected by the motor rotation speed detection section 31, and the frequency division ratio of the frequency division section 28 is changed in stages according to the detected value of the rotation speed detection section 31. Therefore, a discharge pulse whose pulse rate changes approximating the increase/decrease in the discharge current ■ is output from the output terminal of the internal unit 28 for one minute i! 7 and by subtracting the stored value in the counter 21 using the discharge pulse.

The value in the counter 21 can be decreased at a rate according to the amount of load current.

The discharge timing detection unit 20 uses a coil 32 to detect leakage magnetic flux generated from the armature when the motor rotates, or changes in magnetic flux caused by a magnet (not shown) integrally attached to the rotating shaft of the motor 5.
After detection, the detection signal is waveform-shaped by the Schmitt trigger 33 to form a rotation pulse a with a pulse rate proportional to the motor rotation speed n as shown in FIG. 6(d). input. The motor rotation detection section 31 includes a rotation number counting section 34 that samples and counts the number of one rotation pulse a for a set time, and the counting section 3.
The conversion signal outputted from the rotation speed determination section 36 is configured to include a rotation speed determination section 36 that determines the size of the count number in 4. The frequency division ratio of the first frequency divider 29 is changed manually.

The rotation number counting section 34 includes a rotation number counter 39 having a four-stage binary sampling function, and a monostable multi-by-break 40 that generates a gate signal for setting the sampling period of the counter 39, and generates self-discharge pulses. The self-discharge pulse C output from the device 25 is differentiated by a differentiating circuit 41.
A trigger signal d is generated by differentiating the trigger signal d, and this signal d controls the timing of clearing the counter 39 and generation of the gate signal S. That is, as shown in FIG. 6 (ta+), each time one self-discharge pulse C is output, the signal C is differentiated by the differentiating circuit 41 to generate a trigger signal d (see FIG. 6 (b)). The trigger signal d resets the contents e of the counter 39 as shown in FIG. The number of rotation pulses a output from the discharge timing detection section 20 is sampled.

In this embodiment, a four-stage binary counter is used as the counter 39, and a number of rotation pulses a ranging from 0 to 15 are detected. Therefore, by appropriately selecting the pulse ray 1- of the rotational pulse a output from the discharge timing detection section 20 and the pulse width of the monostable multi-by-break 40, the counter 39 can be detected when the rotational speed shown in FIG. )・Number e is 115”, 1 at 4.700 to 5100 rotations
4″.

It should be set to "13" between 4300 and 4700 rpm, and "12" or lower below 4300 rpm. Looking at the relationship between the rotational speed and the driveable time at this time, as shown in Figure 5, the counter 3
If the drivable time when the count number of 9 is "15" is 10, the drivable time decreases by 10% each time the count number decreases by 1. Therefore, it is basically a binary 4-stage hexadecimal system. By sequentially decreasing the frequency division ratio of the first frequency divider 29 such as decimal when the count number is "15" and 9 base when the count number is "I4", the pulse rate corresponding to the magnitude of the discharge current I can be adjusted. A discharge pulse is obtained. That is, the first frequency divider 29 is
When switching to forward mode, the total count value 255 was calculated by up/down counter 21 over 8 hours during charging.
However, the discharge pulse rate P2 may be set so that it increases by about 38 minutes and reaches O during discharge. Such pulse ray) P
2 is.

P2-38X 60/ (IOX 64X 255)
# 0.014 sec, discharge pulse generator 2
4, it can be seen that it is sufficient to generate one pulse every approximately 0.014 seconds.

When the plug blade 9 is pulled out from the outlet to stop charging the battery 6, the pulse switching section 27 switches to the self-discharge pulse generator 25 side, and the self-discharge pulse C output from the pulse generator 25 is transferred to the frequency dividing section. 28 to the counter 21 and subtracts the stored value in the counter 21.
The reduction in battery capacity due to the circuit holding current that flows when the device is stopped is corrected.

The reduction in battery capacity due to such current is such that it takes about two months for the battery to reach zero charge from a fully charged state. Therefore, the pulse rate P3 of the self-discharge pulse C is 5.2 x 106 seconds for two months.

P3=5.2Xl06/ (255X1024)
#20 seconds, and the self-discharge pulse generator 25 outputs a self-discharge pulse C at a rate of one pulse approximately every 20 seconds.

The zero rotation speed detection section 43 provided on the output side of the rotation speed counting section 34 outputs a "1" signal when the sampling number e in the counter 39 is zero, that is, when the rotation of the motor 5 has stopped. This zero signal f is input to the pulse switching section 27, and simultaneously switches the pulse generator to the self-pulse generator 25 side in conjunction with the "0" signal of the charging timing pulse described above.

It is inverted by the inverter 44 and becomes "0".

By inputting the signal to the display drive unit 45, the display unit 46 is cleared only when the motor is stopped, thereby suppressing power consumption by the two display units 22.

The display drive unit 45 is configured to display the upper four
The bits are extracted as a data signal, and the hexadecimal number displayed in four binary digits is decoded and displayed on the display 46.

The display device 46 is configured by arranging four light emitting diodes 47 at the center of the front surface 8 of the main body case 2, and increases or decreases the number of light emitted from the four light emitting diodes 47 in accordance with the stored value in the counter 21. . For example, when charging, 2 seconds from the start of charging.
They light up one by one every hour, and when the upper 4 bits in the counter 21 are all set to "1", all the light emitting diodes 47 of the 4111i1 light up to indicate that charging is complete, and then continue charging. At the same time that all 8 bits of the counter 21 become zero, a carry signal is output and the 1 display drive unit 45
The output signal for driving the light emitting diode disappears. At this time, the switching unit 12 for regulating the charging time of the rechargeable battery 6 is connected to the light emitting diode 16 for displaying the charging time, so the switching unit 12 is turned off to forcibly stop charging the battery 6 and prevent overcharging. do.

However, the count value in the counter 21 is reset and maintained at zero as shown at time to of the smta> (if the battery terminal voltage has dropped below 1.0 V, the count value in the counter 21 is shown in the top of FIG. 8). Start charging here.

The up/down counter 21 receives the charging timing signal output from the charging timing detection section 19 and switches to the amplifier side, but at this point the counter 21 has not yet started counting, and the terminal voltage of the battery 6 increases and the time is changed. Only when t1 exceeds 1.0■, the counter 21 starts counting charging pulses with reference to the time t1.

Charging continues further, and when about 8 hours have elapsed from time t1, all four display light emitting diodes 47 light up.

Displays that the battery 6 has reached full charge. Even if the charging state is continued, the output of the display section 22 will be cut off after a predetermined period of time has elapsed.
The switching unit 12 is opened and overcharging of the battery 6 is prevented.

At time t2, when the plug blade 9 is removed from the outlet and charging is stopped, the output from the charging time detection section 19 disappears, the counter 21 is switched to the down side, and the light emission display on the 1 display section 22 is stopped to reduce current consumption. The storage value of the counter 21 is kept to the necessary minimum. At this time, there is no rotation pulse a output from the discharge timing detection section 20, so the zero rotation signal f is applied from the zero rotation detection section 43 to the pulse switching section 27, and the frequency division section 2B is activated by the self-discharge pulse generator 25. The stored value in the counter 21 is subtracted at a rate sufficiently lower than that during discharge to correct the power consumption when the nine devices are not in use.

Next, at time t3, when the switch 13 is closed and the motor 5 is energized, the rotation of the motor 5 is controlled by the discharge timing detection section 20.
is extracted as a rotation pulse a. Furthermore, the motor rotation detection section 31 detects the motor rotation speed, that is, the value of the negative current I, from the sampling number e of one rotation pulse a, and adjusts the frequency division ratio of the first frequency divider 29 according to the magnitude of the current. Switch to either decimal or septal notation, and write 1. The a value is subtracted.

If charging is performed at time t5, the charge amount display will not start from zero, but will be integrated with the stored value at time t5, and the current charge amount will always be displayed appropriately. In addition, if the actual current consumption is larger than the subtraction amount and the terminal voltage of the battery 6 drops below 1.0V even though the value remains in the counter 21, the count value will be forced to change. (time t7), the display is stopped, and the user is prompted to charge the battery.

Note that the display unit 22 may directly display numbers using a liquid crystal instead of the light emitting diode 47, or may display more finely and continuously. Furthermore, it is also possible to display the amount of charge audibly instead of or in addition to the visual display.

That is, when the amount of charge approaches a set value during charging, the intermittent signal starts to be generated, and as charging progresses, the interval or frequency of sound generation is changed so that the state of charge can be audibly confirmed.

Furthermore, the pulse signal generator 15 is connected to a charging pulse generator 23.
It can also be used exclusively for charging.

In this case, it goes without saying that the one-frequency divider 28 is not particularly required. Instead of having a plurality of pulse generators 23, 24, and 25 and switching them using the pulse switching section 27, the frequency of one pulse generator may be changed in accordance with charging or discharging timing detection. . If the current change during discharge is small, there is no need to particularly change the frequency division ratio of the first frequency divider 29 for correction.

In addition, the display section 22 is not always illuminated during charging and discharging, but is provided with a separate battery check switch and displayed only when the switch is operated.
It is possible to reduce power consumption to the necessary minimum.

Furthermore, it is of course possible to cause the display circuit to operate in a similar manner through a program using a microprocessor.

In this case, the charging, discharging, and self-discharging pulses are displayed as binary numbers corresponding to the magnitude of the current amount, and are directly added to or subtracted from the stored value in the storage unit 21 at predetermined intervals.

As described above, the present invention generates a pulse signal corresponding to the discharge timing and discharge current amount of the rechargeable battery 6, and displays the stored value on the display section 22 while integrating the pulse signal in the storage section 21. Therefore, the display is proportional to the amount of charge of the rechargeable battery 6, and the state of charge of the battery 6 can be appropriately grasped.

Furthermore, the storage section 21 is configured with an up/down counter, and the record 1. added at the time of charging is stored. By subtracting the a value during discharging, there is an advantage that the state of charge within the battery 6 can be continuously determined throughout the entire cycle of charging and discharging.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an electric shaver showing an example of implementing the present invention, FIG. 2 is a block diagram showing an outline of a display circuit, and FIG.
The figure is a block diagram showing a specific example, Figure 4 is a graph showing the relationship between rotation speed and load current, Figure 5 is a graph showing the relationship between rotation speed and motor drive time, and Figure 6 (a) or g
) is a waveform diagram explaining the operation of the motor rotation speed detection section.
FIG. 8 is a flowchart for explaining the operation, and FIGS. 8(8) and 8(b) are explanatory diagrams showing the relationship between the battery terminal voltage and the stored value in the storage section during charging and discharging. 5...Motor. 6...Battery. 7...Charging part. 11... Charging circuit. 12...Switching section 2 15...Pulse signal generation section. 21... Memory section. 22...Display section. 2B... Frequency dividing section. Figure 1 Figure 4 Figure 9 tshita 1-> Figure 5 mouth rotation number

Claims (4)

[Claims] (1) A pulse signal generator 15 that outputs a pulse signal in accordance with the timing of charging the battery 6, a storage unit 21 that sequentially adds and stores the number of input pulse signals, and the magnitude of the stored value in the storage unit 21. A charge amount display circuit comprising a display section 22 that displays a display corresponding to. (2) The charge amount display circuit according to claim 1, wherein the storage section 21 is an up/down counter, and the stored value in the storage section 21 is subtracted when the battery 6 is discharged. (3) The charge amount display according to claim 1 or 2, in which the display unit 22 causes a plurality of light emitting diodes to emit light, and the number of emitted light increases or decreases in proportion to the increase or decrease in the stored value. circuit. (4) The charge amount display circuit according to claim 1 or 2, wherein the display section 22 is a sound generator, and the sound generation state changes according to an increase or decrease in the stored value.