JPS62247728A - 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 at a glance when the device is plugged into an outlet, it is not so necessary for the 5-charging display, which only serves as a warning to prevent overcharging.

The present invention has been made with attention to the above problem, and a pulse signal is generated in response to discharge.

By subtracting the pulse signal from the value stored in the counter and by making the value of the pulse signal correspond to increases and decreases in the amount of discharge current, a display proportional to the remaining amount of the rechargeable battery is displayed, and the state of the rechargeable battery is constantly checked. The purpose is to provide a charge amount display circuit that can be grasped.

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

Although the drawings show an example in which the present invention is implemented in an electric shaver, the present invention is not limited to this, and it goes without saying that the present invention 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 freely retracted from the lower end of the main body case 2, and converts the commercial AC voltage input from the plug blade 9 into a predetermined charging voltage using a charging circuit 1) including an inverter circuit. Further, on the output side of the charging circuit 1), a battery 6 and a switching unit 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 battery 6 is connected to the charging circuit 1) to enable charging.

Both ends of the battery 6 are connected to a DC-DC converter 17 that supplies a predetermined DC voltage to the electronic circuit described below, and a DC-DC converter 17 that supplies a predetermined DC voltage to the electronic circuit described below. When detected, it is connected to a voltage detection section 18 that generates a reset signal to return all circuits to their initial states. Furthermore,
Both ends of the battery 6 are connected to both ends of the motor 5 via a main switch 13 placed at the center of the front of the main body case 2.
In conjunction with the on/off operation of the main switch 13, the timing of energization from the battery 6 to the motor 5 is regulated.

Furthermore, the charging time of the battery 6, the drive time of the motor 5, and the stop time of the device 1 are detected respectively, and the charging time of the battery 6 is detected. The amount is displayed on the display circuit 14.

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 ninth section 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 amount of charging current is set so that the battery will be fully charged in a few hours.On the other hand, when discharging is performed using the motor 5 of the electric shaver 1 as a load, the capacity of the battery will increase after continuous operation for about 40 minutes, 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 section 21 is configured with an amplifier 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.

The present invention is characterized in that a frequency division section 28 with a variable frequency division ratio is disposed between the pulse signal generation section 15 and the counter 21, and the frequency division ratio of the frequency division section 28 is changed in accordance with the amount of discharge current. shall be.

That is, the total number of pulses accumulated and stored in the counter 21 during charging.

The frequency is higher than that during charging and corresponds to the load current amount 6) By subtracting with a variable discharge pulse.

A value proportional to the amount of charge currently stored in the battery 6 is constantly stored in the counter 21. Therefore.

By displaying such stored values on a 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, and 25 for charging, discharging, and self-discharging, and a pulse switching section 27. The pulse switching section 27 selectively sends pulse signals having generation rates individually set for each of the pulse generators 23, 24, and 25 to the frequency dividing section 28.

The pulse switching section 27 is configured by combining a plurality of logic gate circuits, for example, and outputs a charging timing signal taken out from the charging timing detecting section 19 by waveform shaping the output of the charging circuit 1) and motor rotation speed detection, which will be described later. It is switched in conjunction with the application of a zero rotation detection signal outputted from section 31 and indicating when the motor is stopped. That is, when the charging timing signal and the zero rotation detection signal are both "L", the charging pulse generator 23 is selected, and when both are "0", the discharging pulse generator 24 is selected.
is selected, and furthermore, when only the zero rotation detection signal is "1", the self-discharge pulse generator 25 is selected and the frequency dividing section 2
Connected to 8.

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 pulse signal 29 is extracted with its generation rate divided by 1/2 [l, that is, 1/1024.

Furthermore, if the amplifier 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 "1", that is, when 240 pulses have been counted, and in order to stop charging after counting 255 pulses, 8 hours - Since it is 2.8X104 seconds, the pulse rate P1 of the charging pulse output from the charging pulse generator 23 is 1 PI = 2.8 XIO' / (255X1024)
#0.1 sec, and it can be seen that by generating one pulse from the charging pulse generator 23 approximately 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, the load current I 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. An increase in load current 1 will lead to a decrease in the continuous drive time of the motor after full charge, so battery 6
By setting the capacity of the 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.

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. As a result, a discharge pulse whose pulse rate changes approximately as the increase/decrease in the discharge current I is obtained from the output terminal of the 1 frequency divider 28, and by subtracting the stored value in the counter 21 using this 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 detects 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 the detection in step 2, the detection signal is applied to the Schmitt trigger. Figure 6 (dl) forms a rotation pulse a with a pulse rate proportional to the motor rotation speed n and inputs it to the motor rotation detection section 31. It is composed of a rotation speed counting section 34 that counts the number of rotations, and a rotation speed determination section 36 that determines the size of the counted number in the counting section 34. The frequency division ratio of the first frequency divider 29 is changed by inputting the conversion signal output from the rotation speed determining section 36.

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. The self-discharge pulse C output from the self-discharge pulse generator 25 is differentiated by a differentiating circuit 41.
The trigger signal d is generated by differentiating the trigger signal d, and the trigger signal d controls the clearing of the counter 39 and the generation timing of the gate signal S.

That is, as shown in FIG. 6fa), every time one self-discharge pulse C is output, the signal C is differentiated by a differentiating circuit 41 to generate a trigger signal d (see FIG. 6('b)).

This trigger signal d is applied to the counter 3 as shown in FIG. 6 (fl).
At the same time as resetting the contents e of 9, the monostable multi-by break 40 is activated, and the monostable multi-by break 4 is activated.
The gate of the counter 39 is opened by the gate signal outputted from 0, and the number of rotation pulses a outputted from the discharge timing detection section 20 is sampled.

In this embodiment, the counter 39 has four binary stages. A number of rotational pulses a ranging from 0 to 15 are detected. Therefore, the rotation pulse a output from the discharge timing detection section 20
By appropriately selecting the pulse rate of and the pulse width of the monostable multi-bibreak 40. The count number e of the power counter 39 when the rotation speed shown in Fig. 5 is 5100 revolutions per minute or more.
is "15", and "14" at 4700-5100 rpm. 43
It should be "13" at 00 to 4700 revolutions, and "12" or less at 4.300 revolutions or less. Looking at the relationship between the rotational speed and the driveable time in such a case, the counter 39
If the drivable time is 10 when the count number is 15", the drivable time decreases by 10% each time the count number decreases by 1. Therefore, basically the
The frequency division ratio of the frequency divider 29 is expressed in decimal form when the count number is 15''.

By descending sequentially like a 9-digit number when it is "14". A discharge pulse having a pulse rate corresponding to the magnitude of the discharge current I can be obtained. In other words, when the first frequency divider 29 is switched to decimal, the discharge pulse rate is set so that the total count value 255 counted by the up-down counter 21 over 8 hours during charging becomes 0 over about 38 minutes during discharging. P
2 should be set. This pulse rate P2 is:

P2 = 38X 60/ (10x 64x 255
) #0.014 sec, and it can be seen that the discharge pulse generator 24 should generate one pulse approximately every 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. The self-discharge pulse C output from the pulse generator 25 is applied to the counter 21 via the frequency divider 28 to subtract 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 battery capacity decreases by approximately 2 times from a fully charged state due to this current.
The amount of charge is such that it takes a month to charge the battery to zero. Therefore, the pulse rate (P3) of the self-discharge pulse C is 2) since the month is 5.2 x 106 seconds.

P3=5. 2 x 10” / (255 x 1
024) #20sec. 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. The pulse generator is switched to the self-pulse generator 25 side in conjunction with the "0" signal of the charge timing pulse described above, and at the same time, it is inverted by the inverter 44 and becomes "O" and is input to the 2-display drive unit 45. , the power consumption by the display unit 22 is suppressed by clearing the display 46 only when the motor is stopped.

The display driving section 45 takes out the upper four bits of the amplifier down counter 21 as a data signal, decodes the hexadecimal number displayed in four binary digits, and displays it on the display 46. The display 46 is constructed by arranging four light emitting diodes 47 at the center of the front face 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, the lights will turn on one by one every two hours from the start of charging, and the top four in the counter 21 will turn on one by one every two hours from the start of charging.
When all bits are set to 1", 4 light emitting diodes 47
all light up to indicate that charging is complete, and charging continues until all 8 bits of the counter 21 become zero, at the same time a carry signal is output and an output signal for driving the light emitting diode from the 1 display driver 45 is generated. 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, if the battery terminal voltage has dropped to 1.0 V or less as shown in Figure 8 (al), the power count value in the counter 21 will be Reset and maintain zero state.When charging starts 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 time t1 exceeds 1.0, the counter 21 starts counting charging pulses with reference to 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 is stopped, the counter 21 is switched to the down side, and the light emission display on the 2nd display section 22 is stopped to reduce the current consumption. The storage value of the counter 21 is kept to the necessary minimum. At this time, there is no output of the rotation pulse a 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 9 frequency division section 28 becomes a self-discharge pulse generator. 25, and subtracts the stored value in the counter 21 at a sufficiently lower rate than when discharging to correct the power consumption when the two 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 unit 31 detects the motor rotation speed 5, that is, the value of the load current ■ from the sampling number e of the rotation pulse a, and changes the frequency division ratio of the first frequency divider 29 from decimal to decimal depending on the magnitude of the current. The value stored in the counter 21 is subtracted at a rate corresponding to the magnitude of current consumption by switching to either hexadecimal system.

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, so that the current charge amount will always be displayed appropriately. Also, as a result of the fact that the actual current consumption was larger than the subtraction amount, the terminal voltage of the battery 6 was 1. If the value falls below OV, the count value is forcibly reset (time t7), the display is stopped, and the user is prompted to charge the battery.

Note that the pulse rate of the discharge pulse during discharge may be changed by changing the oscillation frequency of the discharge pulse generator 24 itself instead of changing the frequency division ratio of the 5-first frequency divider 29. In that case, a variable capacitance diode is used as the capacitor that regulates the oscillation frequency of the discharge pulse generator 24, and a voltage proportional to the motor rotation speed is generated from the discharge timing detection section 20, and the capacitance of the capacitor is directly changed by this voltage. If so, the frequency of the discharge pulse can be changed continuously.

Furthermore, 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 can be changed according to charging or discharging timing detection. There may be.

Further, 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, in place of or in addition to the visual display, it is also possible to display the amount of charge audibly. That is, when the charging amount approaches a set value during charging, the intermittent sound starts to be generated, and as charging progresses, the interval or frequency of the sound is changed, so that the charging state can be confirmed audibly.

Furthermore, the display section 22 does not always display light during charging and discharging, but by providing a separate switch for checking the battery and displaying the display only when the switch is operated.
2 can be suppressed to the necessary minimum.

Yet again. Of course, it is also possible to cause the display circuit described above to operate in a similar manner through a program using a microprocessor. In this case, the charging, discharging, and self-limiting pulses are displayed in 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 discharge pulse signal corresponding to the discharge timing and discharge current amount of the rechargeable battery 6, and
While the pulse signal is subtracted in the storage unit 21, the stored value is displayed on the display unit 22, so that the display is proportional to the current charge amount of one rechargeable battery 6, and the remaining capacity of the battery 6 is appropriately displayed. It has advantages that can be grasped.

[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 drivable time, and Figure 6 (al or g) is a graph showing the relationship between rotation speed and load current.
) is a waveform diagram explaining the operation of the motor rotation speed detection section.
The figure is a flowchart explaining the operation, and FIG. ... Battery. 7 ... Charging section. 1) ... Charging circuit. 12 ... Switching section. 15 ... Pulse signal generation section. 19 ... Charging time detection Part. 20... Discharge timing detection part. 21... Storage part. 22... Display part. 28... Frequency division part. 31... Motor rotation speed detection part. Patent Applicant Kyushu Hitachi Maxell Co., Ltd. Figure 1 Figure 4 Dove right/C 1→ Figure 5 15 Number of rotations n

Claims (3)

[Claims] (1) A storage unit 21 that sequentially subtracts and stores a discharge pulse signal generated in response to changes in the discharge timing and discharge current amount of the battery 6 and the number of inputs of the discharge pulse signal from a stored value; , and a display section 22 that displays a value corresponding to the magnitude of a stored value in a storage section 21. (2) The charge amount display circuit according to claim 1, wherein the storage section 21 is an up/down counter, and when the battery 6 is charged, the stored value in the storage section 21 is added. (3) The discharge pulse signal is obtained by frequency-dividing a pulse signal of a constant frequency generated from the pulse signal generation section 15 by a frequency division section 28 having a variable frequency division ratio. Charge amount display circuit described in section.