JPS6335192A - Electric razor - Google Patents

Abstract

PURPOSE:To prevent damage to an inverter circuit due to overload, by a method wherein when detection signal corresponding to drive state of drive means attains to a prescribed value, oscillation of the inverter circuit is limited. CONSTITUTION:A secondary battery 6 acts as a load of a power source section 13 at motor stop state, and constitutes a main power source 23 together with output from the power source section 13 at motor drive state. An output control circuit 24 maintains voltage supplied to the load to nearly constant value. A rotation control circuit 25 maintains rotational speed of the motor 5 to nearly constant value. When the secondary battery 6 becomes low load state due to overcharging or the like, a low load protection circuit 26 drops the output from the power source section 13. On the other hand, when heavy load state is produced due to lock state of the motor 5 or the like, a heavy load protection circuit 27 stops an inverter circuit 22.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electric shaver, and particularly to one using an inverter circuit as a power source for driving the inner cutters.

[Prior Art] Conventionally, in this type of electric shaver, it is assumed that an operator is present while the razor is being used, and the protection of the electric circuit has been limited to protection from temperature rise due to excessive current during charging. The purpose of this was to prevent fires caused by fires, and the most common methods were to use temperature or current fuses.

[Problems to be solved by the invention] By the way, ordinary users do not often remove hair waste.
In many cases, a small problem such as a biting of the tip of the hair can cause an overload, causing the machine to stop working.
In this case, if the power source is a battery, the battery simply discharges and there is no particular problem if the battery is replaced or charged.

However, if the power source is a commercial power source using an inverter circuit, the inverter circuit itself may be damaged as a result of continuing to flow a large current to the motor for a long time.

[Means for solving the problems] The present invention has been made in view of the above problems, and the present invention has been made in view of the above problems.
As schematically shown in the figure, a power supply means including an inverter circuit, an inner blade drive means connected to the power supply means and supplied with power, and a detection signal corresponding to the driving state of the drive means are generated. and protection means for limiting oscillation of the inverter circuit when the detection signal reaches a set value.

"Operation" In the above configuration, the protection means does not work while the electric shaver is used in a normal state, and the power supply means supplies a specified amount of power to the inner blade drive means.

If an abnormality such as locking of the inner cutter transition occurs, the detection means immediately generates a detection signal corresponding to the above condition, and furthermore, when the value of this detection signal reaches the set value, the inner cutter drive itself When it is determined that it is necessary to stop the inverter circuit, the protection means is activated and stops the oscillation of the inverter circuit, thereby limiting the output from the power supply means, thereby preventing damage to the inverter circuit due to overload. That's what I do.

[Example] The present invention will be described below based on an example in which the present invention is implemented in an electric shaver that can be driven by a motor in parallel with charging.

As shown in FIG. 2, an electric shaver 1 embodying the present invention has an outer cutter 2 detachably attached to the upper part of a main body case 3, and an inner cutter 4 slidably disposed inside the outer cutter 2. do. Furthermore, inside the main body case 3, there is a motor 5 for reciprocating the inner cutter 4, a secondary battery 6 for supplying rotational driving power to the motor 5, and a charging control for the secondary battery 6 or for controlling the motor 5. It houses an electric circuit 7 that performs various controls such as rotation control. In addition, on the front of the main body case 3, a first display element 11 for displaying the rotation control state is located at the upper position on the same line across the push button switch 10 that regulates the timing of energization of the motor 5, and a first display element 11 for displaying the rotation control state is located at the lower position. The second display elements 12 that display the control status are arranged separately from each other.

FIG. 3 shows the electric circuit 7 built into the main body case 3 mentioned above.
6 is a block diagram showing an overall outline of a secondary battery 6 such as a nickel-cadmium battery that can be charged and discharged multiple times.
and a motor 5 as the main loads, a power supply unit 13 supplies power to the loads, a detection unit 14 is capable of outputting detection signals corresponding to various states of the load, and a power supply unit 14 is configured to provide a power supply unit 14 that can output detection signals corresponding to various states of the load. When the load is extremely light or heavy, the control section 15 performs various controls in response to changes in the voltage value of the commercial power supply 20 input to the power supply section 13 or fluctuations in the load. It is composed of a protection section 16 that regulates the operation timing of the power supply section 13, and a display section 17 that displays displays corresponding to various states of the load.

The power supply unit 13 uses an inverter circuit 22 that inputs a voltage obtained by full-wave rectification of a commercial AC power supply 20 by a rectifier circuit 21. The pressure has dropped to

The secondary battery 6 can be connected via a switch 10 to a circuit that performs various controls when the motor is driven. Therefore, when the motor is stopped, it acts as a load for the t source section 13, but when the motor is driven, , @ together with the output from the source section 13 constitutes the earth loading w, 23.

The control unit 15 controls the output control circuit 24 of the inverter circuit 22.
and a rotation control circuit 25 for the motor 5. The output control circuit 24 is intended to maintain the voltage supplied to the load approximately constant regardless of fluctuations in the voltage of the commercial AC power supply 20 or the load, and is configured to Control is performed by regulating the oscillation frequency or oscillation timing of the inverter circuit 22.

On the other hand, the rotation control circuit 25 constantly detects the rotation speed of the motor 5 and increases/decreases the voltage applied to the motor 5 to maintain a substantially constant rotation regardless of the magnitude of the load applied to the motor 5 or fluctuations in the voltage of the main power supply 23. I'm trying to maintain the speed.

The protection section 16 includes a light load protection circuit 26 and a heavy load protection circuit 27.
When the secondary battery 6 becomes fully charged and the load becomes light, the light load protection circuit 26 protects the load by lowering the output from the power supply section 13. , when the motor 5 becomes locked and the load becomes heavy, the heavy load protection circuit 27 protects the inverter circuit 2.
2 to protect the power supply section 13.

The display unit 17 includes a charging status display circuit 29 that prompts to stop charging by displaying that charging of the secondary battery 6 has progressed to a fully charged state, and a charging status display circuit 29 that prompts to stop charging by displaying that charging of the secondary battery 6 has progressed and reached a fully charged state, and a charging status display circuit 29 that prompts to stop charging by displaying that charging of the secondary battery 6 has progressed
The rotation state display circuit 30 is provided on the main body case 3 to indicate that the capacity of the motor 3 is insufficient and control in the rotation control circuit 25 is no longer possible, and to prompt the motor 5 to stop and start charging. Each state can be distinguished and displayed by changing and blinking the emitted light color of the display elements 11 and 12.

Next, the configuration of each of the above-mentioned parts will be explained in more detail using a specific electric circuit diagram.

(Power supply part) The power supply part 13 has a diode bridge 3 as shown in FIG.
1, a rectifier circuit 21 with a filter 32, and an inverter circuit 22, and a commercial AC power supply 20 inputted to the main body case 3 via a detachable power plug 33.
After being full-wave rectified by the rectifier circuit 21, it is applied to the impark circuit 22 through the fuse 34. The fuse acts as a final protection means in case the protection unit 16 malfunctions, cutting off the power to the inverter circuit 22 and forcibly stopping the operation of the inverter circuit 22.

The inverter circuit 22 includes, on the collector side of the transistor 35, a secondary coil 36 and a shock absorbing section 37 that is connected to both ends of the secondary coil 36 and absorbs the shock voltage generated when the transistor 35 is turned off. , a feedback section 40 is provided between the base and the emitter. Furthermore, a feedback coil 41, a secondary coil 42, and a tertiary coil 43 are wound on the same core as the primary coil 36.

The feedback section 40 connects one end of the feedback coil 41 to the transistor 3.
A capacitor 44 is connected between the other end of the feedback coil 41 and the emitter of the transistor 35, and the emitter end is connected to the positive side of the secondary battery 6. Further, a voltage obtained by dividing the output voltage from the rectifier circuit 21 by resistors 45 and 46 can be applied to the connection point between the feedback coil 41 and the capacitor 44 via a resistor 47.

Therefore, a voltage is generated across the resistor 46 at the same time as the voltage is applied to the inverter circuit 22, and charging of the capacitor 44 is started by this voltage. When the voltage across the capacitor 44 rises and reaches around the turn-on voltage of the transistor 35, current begins to flow through the primary coil 36 connected to the collector terminal of the transistor 35, and this increase in current generates a voltage in the feedback coil 41. do. This voltage quickly charges the capacitor 44 in the opposite direction to the above through the base and emitter of the transistor 35, and the charging voltage of the capacitor 44 becomes a blocking voltage, and the transistor 35
Turn off to fil. After the transistor 35 is turned off, the voltage across the resistor 46 passes through the resistor 47 again to the capacitor 4.
4, the capacitor 44 is charged in the positive direction, and the above-mentioned on/off operation is repeated. Here, the energy stored in the primary coil 36 when the transistor 35 is on is applied to the secondary coil 42 and the tertiary coil during the off period of the transistor 35. The rectifier diodes 50 and 51 selectively take out the signal to the load connected to the output terminal 43.

The secondary battery 6 is always connected to the secondary coil 42,
Rotation control circuit 2 including motor 5 by turning on switch 10
5 is connected, the main power supply 2 is output along with the output from the power supply section 13.
3. Further, by switching the switch 10 and inserting/removing the power plug 33, charging can be performed alone, charging and motor driving can be performed simultaneously, or the motor can be driven by the secondary battery alone.

The number of turns of the tertiary coil 43 is several times larger than that of the secondary coil 42 described above, so it is possible to output a larger voltage than the secondary coil 42 side, and the output is further smoothed using a rectifying diode 51 and a large capacitor 52. Auxiliary power supply 53
Configure. Therefore, the auxiliary power supply 53 can drive and control various circuits even when the inverter circuit 22 is in operation but the inverter circuit 22 is sufficiently controlled and its output is reduced. A necessary and sufficient auxiliary voltage v2 can be supplied to each of the following circuits as a circuit drive voltage or control signal.

(Detection unit) The detection unit 14 includes four sets of first to fourth detection circuits 61 and 61.
62, 63, and 64, each outputting a detection signal of a different value corresponding to the state of the load to be detected.

As shown in FIG. 4, the first detection circuit 61 is connected to both ends of the secondary coil 42 of the main power source 23 via a diode 65, and detects the pulsed voltage output from the secondary coil 42. is smoothed by a capacitor 66, and the capacitor 6
By dividing the voltage across 6 with resistors 67 to 70,
It outputs detection signals SL and S2 whose values change immediately in response to increases and decreases in the average value of the pulsed voltage output from the power supply section 13.

This signal is transmitted to the output control circuit 24 and the charging status display circuit 2.
Used in 9.

Both the second and tt83 detection circuits 62 and 63 are connected to the main power supply 2.
A voltage dividing resistor is connected in parallel with 3, and a detection signal having a voltage value proportional to a change in the terminal voltage 2 of the secondary battery 6 is output.

Here, the second detection circuit 62 detects the motor 5 as shown in FIG.
The normally open switch contact 10 is used in the rotation status display circuit 30 of
A is interposed so that the detection signal S3 is output only when the motor 5 is driven in conjunction with the ON operation of the switch 10.

On the other hand, the third detection circuit 63 can output the detection signal S4 as shown in FIG.
A switching transistor 74 that is turned on at
-78 is stopped to prevent the secondary battery 6 from being exhausted.

As shown in FIG. 6, the fourth detection circuit 64 detects the increase/decrease in the rotational speed of the motor 5 and when the rotation itself is locked by forming a rectangular wave signal with a pulse rate corresponding to the rotational speed of the motor 5. is capable of detecting
By interposing a normally open switch contact 10a on the ground side that closes in conjunction with the suppressing operation of the switch 10, the detection operation is performed only when the motor is driven. This detection signal S is used in the rotation control circuit 25 and the heavy load protection circuit 27.

The detection operation in the fourth detection circuit 64 described above is performed using a cylindrical reflector 80 attached to the rotating shaft of the motor 5 and a light emitting diode 81 that utilizes the reflection of light on the reflector 80.
This is performed using a photointerrupter 83 consisting of a phototransistor 82 and a phototransistor 82, and generates a signal with a frequency corresponding to the rotational speed of the motor 5. This signal is further input to a filter circuit 84, and only an AC signal having a frequency component corresponding to the rotation period of the motor 5 is selectively sent to a waveform shaping circuit 85. The waveform shaping circuit 85 inputs the output signal from the filter circuit 84 to the negative input terminal of a comparator 86, while inputting the secondary battery voltage V to the positive terminal of the comparator 86 through resistors 87 and 88.
Apply the reference voltage divided by , and also connect a resistor 8 to the output terminal.
A diode 90 is connected to the secondary battery 6 side via a diode 90, and when the motor 5 stops rotating and there is no input signal, the output side of the comparator 86 opens and the diode 90 drops. A voltage value regulated by voltage is output, but each time the motor 5 rotates and the voltage value of the input signal exceeds the reference voltage value, both ends of the diode 90 are short-circuited and drop to zero potential. From both ends of the diode 90, a rectangular wave detection signal S5 as shown in FIG. 8(a) whose peak value is regulated by the forward voltage of the diode 90 is output.
is taken out.

(Control unit) The control unit 15 enables stable load driving during normal use, and is connected to the output control circuit 2 shown in FIG.
4 and a rotation control circuit 25 shown in FIG.

The output control circuit 24 includes first and second transistors 93 and 9.
4, the emitters and base ends of both transistors 93 and 94 are directly connected, the collector end of the first transistor 93 is connected between the resistors 45 and 46 of the inverter circuit 22, and the collector end of the second transistor 94 is connected between the resistors 95 and 46. 96
are connected to the base end of the transistor 35 and the output side of the auxiliary t[53, respectively, and further connected to the base end of the first detection circuit 61
A detection signal S outputted from the sensor is applied. The detection signal SI is obtained by dividing the voltage across a capacitor 66 connected to the secondary coil 42 via a diode 65 using a resistor, and responds to changes in the voltage value of the commercial AC power supply 20 or fluctuations in the load. It is possible to output a voltage of this magnitude.

In the above configuration, for example, assuming that the voltage value of the commercial current w, 20 changes in the range of about 100 to 120V, the transistors 93 and 94 are set so that both transistors 93 and 94 are turned off when the motor is driven when the voltage value is 100V. 1, the voltage value of the detection signal S is set in advance by adjusting the variable resistor 70 of the detection circuit 61. In such a usage state, resistors 95 and 96 are connected to the base end of the transistor 35 of the inverter circuit 22.
An auxiliary voltage v2 is applied via the voltage v2
This shortens the discharge time of the capacitor 44 while the transistor 35 is off, and makes the oscillation frequency of the inverter circuit 22 slightly higher than the frequency when the circuit 22 is at its highest efficiency. Here, when the commercial f4 source voltage increases or the load becomes lighter, the value of the detection signal S increases, and the second transistor 9
4, the base current begins to flow, and the output v from the auxiliary power supply 53
2 is shunted by the transistor 94, and the voltage applied to the base end of the transistor 35 is gradually lowered. Then, the discharge time of the capacitor 44 becomes longer than in the above case, and the oscillation frequency of the inverter circuit 22 decreases.

When the value of the detection signal S further increases, both ends of the resistor 46 are shorted by the first transistor 93, and the inverter circuit 2
The oscillation of 2 is stopped intermittently. As a result of this operation, when the load is constant and the commercial power supply voltage fluctuates, the output is controlled to be constant, and when the commercial power supply voltage is constant and the load increases or decreases, the output is controlled depending on the magnitude of the load. The inverter circuit 22 increases or decreases the output accordingly, thereby ensuring stable power supply operation during normal load driving.
is under control.

As shown in FIG. 5, the rotation control circuit 25 converts the rectangular wave detection signal S5 with a frequency proportional to the rotation speed outputted from the fourth detection circuit 64 into a DA converter 100 with a magnitude corresponding to the frequency. This detection signal is compared with a reference voltage in a comparison 5101, and if a deviation occurs between the two, a control signal corresponding to the deviation value is sent to the control circuit 10.
Send to 2.

The control circuit 102 is interposed in the current supply circuit to the motor 5, and controls the voltage drop value in the control circuit 102 according to the control signal to increase or decrease the voltage applied to the motor 5, thereby reducing the load applied to the motor 5. The size or the main 1! Rotational speed control is performed in immediate response to increases and decreases in the output voltage of the power source 23.

Here, the D-A converter 100 is an integrating circuit using an OP amplifier 103, and when a detected digital detection signal S is applied to a capacitor 104, the capacitor 1
The charge stored in 04 flows to negative feedback capacitor 107 through a pump circuit consisting of diodes 105 and 106. This inflow of charges is integrated via the OP amplifier 103, and an analog signal with a voltage value proportional to the pulse rate is obtained on the output side.

The comparator 101 is a VJ amplifier using a ○P amplifier 110, and inputs the signal on the negative side, while
A reference signal is applied to the positive side and a voltage control signal proportional to the difference between the two is taken out.The reference signal is a diode 111.
By coupling a variable resistor 112 to both ends of the variable resistor 112, its value can be adjusted, and the operating point of the control circuit 102 can be changed.

The control circuit 102 includes a first transistor 113 and a second transistor 113.
The base end of the first transistor 113 is connected to the output side of the ○P amplifier 110, the emitter end is connected to the base end of the second transistor 114, and the emitter terminal of the second transistor 114 is connected to the base end of the second transistor 114.
A circuit between the collectors is interposed in the current supply circuit to the motor 5, and negative feedback is provided from the collector end of the second transistor to the oP amplifier 110 side of the comparator 101 via a resistor 115.

In this configuration, the variable resistor 112 of the comparator 101 is adjusted to bring the control circuit 102 into an amplifying operation state so that the motor 5 exhibits the set rotational speed when a set load is applied. When the comparator 101 detects that the rotational speed of the motor 5 has decreased from the set speed, the value of the control signal is increased to the motor terminal voltage required for the set rotational speed, and the second transistor 114 is brought into saturation. By doing so, the voltage applied to the motor 5 is increased and the rotational speed is corrected in the upward direction. Conversely, when it is detected that the rotational speed has increased above the set value, the value of the control signal is lowered to increase the emitter-collector voltage of the second transistor 114, and the motor applied voltage is lowered to automatically lower the rotational speed. Fix it.

Note that if the main power source 23 has sufficient capacity, the above-described control can be performed relatively stably. However, if power is supplied from the secondary battery 6 alone without using the power supply section 23, and the battery capacity decreases, the value of the control signal itself from the comparator 101 will also become as small as possible. As a result, control circuit 1
Even when the base current that can be supplied to the motor 5 decreases and the secondary battery 6 still has enough capacity to drive the motor 5, the control circuit 102 turns off and forcibly energizes the motor 5. In this embodiment, a resistor 116 is connected between the input side of the control circuit 102 and the secondary battery 6, so that even after control from the comparator 101 side becomes inoperable,
Supplying current directly to the control circuit 102 from the secondary battery 6 side,
The rotatable time of the motor 5 is extended as much as possible.

(Protective Section) FIG. 6 is an electrical circuit diagram showing the overall configuration of the protective section 16, which is composed of a light load protection circuit 26 and a heavy load protection circuit 27. The light load protection circuit 26 has IC1! for the secondary battery 6. When the third detection circuit 63 detects that the load has become light due to rapid charging by current, the third detection circuit 63 controls the oscillation timing of the inverter circuit 22 to reduce the output by 0.1. By shifting to trickle charging at about 0.2 C, deterioration of the secondary battery 6 due to overcharging is mainly prevented. On the other hand, the heavy load protection circuit 27 detects when the fourth detection circuit 64 detects that the motor 5 is locked due to, for example, hair being caught between the outer cutter 2 and the inner cutter 4, resulting in a tjt load. Oscillation of the inverter circuit 22 is stopped to prevent damage to the transistor 35.

The light load protection circuit 26 applies a reference voltage stabilized by the diode 121 of the third detection circuit 63 to the negative input terminal of the comparator 120, while applying the reference voltage output from the third detection circuit 63 to the positive input terminal. A detection signal S4 is applied. Further, a capacitor 122 is connected to the output side of the comparator 120, and an auxiliary power supply 53 is connected to both ends of the capacitor 122 via a resistor 123, and to the base end of a transistor 124 via a Zener diode 125. The transistor 124 also connects its collector end to the transistor 3 of the inverter circuit 22 via a diode 126.
5, and the emitter end and base end are connected through a resistor 127.

The heavy load protection circuit 27 includes a fourth circuit as shown in FIG. 8(a).
A rectangular wave detection signal S5 with a frequency proportional to the rotational speed of the motor 5 output from the detection circuit 64 is input to the conversion section 130 to convert the digital signal into an analog signal. The converter 130 controls the transistor 131 on and off by supplying the base current of the transistor 131 from the detection signal S, and also connects the collector side to the secondary battery 6 to take out the output, as shown in FIG. 8(b). A rectangular wave voltage S6 having a peak value larger than the detection signal S5 and having a pulse rate proportional to the rotational speed is generated only when the motor is rotating, as shown in FIG. This output voltage S6 is further input to the integrating circuit 132, integrated, and applied to the negative input terminal of the comparator 133 as a detection voltage S7 whose magnitude corresponds to the magnitude of the rotational speed. The comparator 133 has its positive terminal applied with the detection signal 84' output from the third detection circuit 63 as a reference voltage, and further connects its output terminal to the base end of the transistor 135 via the Zener diode 134, and a resistor 136. They are each connected to an auxiliary power source 53 via the power supply. The collector side of the transistor 135 is connected in parallel to the above-mentioned light load protection circuit 26 via a diode 137. Furthermore, by connecting a normally closed switch contact 10b and a diode 138 connected in series and a resistor 39 in parallel with the base-emitter, the resistor 139 is connected in parallel with the base-emitter. Both ends are short-circuited to forcibly stop the application of base pressure to prevent the heavy load protection circuit 27 from malfunctioning.

Next, the operation in the protection section 16 will be explained in detail based on the waveform diagram shown in FIG.

In the above configuration, the variable resistor 76 of the third detection circuit 63 is set so that the voltage value of the detection signal S4 substantially matches the reference voltage ■ when the secondary battery 6 approaches full charge (time 1). is adjusted in advance. Here, with the switch 10 turned off and the motor 5 stopped, time 1. When the power plug 33 is inserted at , the secondary battery 6 is 'I!' , charging is started as a load to the source section 13. At the beginning of charging,
The value of the detection signal S4 is sufficiently smaller than the reference voltage V3, so both ends of the capacitor 122 are shorted by the output side of the comparator 13120, the transistor 124 remains off, and the inverter circuit 22 is controlled by the output control circuit 24 described above. It continues its normal oscillation. As the charging progresses further and approaches full charge (time 1+), the detection signal S4 is instantaneously activated in response to the output of the pulsed voltage from the secondary coil 42.
exceeds the reference voltage, and the output side of the comparator 120 is pulsed to output the auxiliary voltage v2. However, instead of directly controlling the transistor 124 with the voltage V2, it is once applied to the capacitor 122 and integrated, and only when the integrated value exceeds the Zener voltage of the diode 125, the diode 125 is made conductive and the transistor 1
The oscillation of the inverter circuit 22 is stopped by supplying a base current to the transistor 24, turning on the transistor 124, and grounding the base end of the transistor 1240. That is, by limiting the amount of output regulation of the inverter circuit 22 by the light load protection circuit 26 as much as possible at the time of starting control, the amount of charging current during this period is substantially increased, and the charging current can be reduced in a short time. The charging current for the secondary battery 6 is narrowed down. Therefore, the output from the inverter circuit 22 during light loads is regulated to the necessary minimum, and deterioration of the secondary battery 6 due to overcharging is prevented.

Next, when the switch 10 is turned on (time ta) with the secondary battery 6 fully charged as described above, the motor 5 is under rotation speed control by the rotation control circuit 25.
Start constant speed rotation. Note that at the time when the motor 5 starts rotating, there is no detection signal S5 from the fourth detection circuit 64, but a signal that is sufficiently larger than the reference voltage S, l is applied from the main power supply 23 side through the resistor 140 and the diode 141. In addition, even after the constant speed rotation state is reached, the variable resistor 76 of the third detection circuit 63 is adjusted in advance so that the reference voltage S4° remains the detection voltage even when no load is applied to the inner cutter 4. By setting the voltage value to be sufficiently small compared to S7, the output side of the comparator 133 is always grounded when the rotation speed is sufficiently high and the rotation speed control described above is effective. , the transistor 135 continues to be off and has no effect on the inverter circuit 22.

However, as the load applied to the motor 5 increases, the output voltage V from the main power source 23 decreases, and eventually the rotation control becomes impossible (time t4). The rotation speed decreases. At the same time, the value of the detection voltage Sa input to the comparator 133 also decreases, and when the rotation of the motor 5 is locked by biting the tip of the hair, the input to the integrating circuit 132 disappears (time 11
), 1. The detection voltage S7 does not disappear immediately, but falls below the value of the reference voltage S4' at time L+) after the elapse of the time determined by the discharge time constant of the capacitor 142 and the resistor 143, opening the output terminal of the comparator 133. . At the same time, the auxiliary voltage v2 is applied to the base of the transistor 135 via the diode 134, turning on the transistor 135 and stopping the oscillation of the inverter circuit 22, as shown in FIG. 8(d).

Note that if the above-described locking of the motor 5 is temporary and the lock is released immediately at time t8, as described above, from the time of locking until the oscillation of the inverter circuit stops,
For example, since a time difference of about 0.3 to 1 second is set in advance, the detection voltage S7 is immediately changed to the reference voltage S as shown by the dashed line.
, l, and return to a normal value sufficiently higher than l, and the motor 5 continues its normal rotational operation.

Note that the detection voltage ST value repeatedly fluctuates greatly during periods when a large load is applied to the motor 5 but there is no need to stop it, so the reference voltage is It is desirable that S4° be as low as possible, but once the rotation has stopped, the protection circuit must continue to operate without unnecessary rotation by turning on and off the switch 10 until the cause of the rotation stop is removed. In order to achieve this, it is necessary that the reference voltage S4° is high to some extent. In this embodiment, a voltage obtained by dividing the output voltage of the main power supply 23 is used as the reference voltage 84°. Therefore, the reference voltage S4' automatically decreases as the rotational speed decreases, and returns to the original value after the motor stops, satisfying the above-mentioned contradictory demands without any troublesome adjustment.

Further, the heavy load state can be detected not by directly detecting the rotation of the motor 5 itself, but also by detecting the output voltage from the main power source 23. In that case, it is also possible to perform both heavy load detection and light load detection.

(Display section) As shown in FIG. 7, the display section 17 includes a charge state display circuit 29 that operates during charging to display the fully charged state, and a rotation state display circuit that operates when the motor is driven to display the state of rotation speed control. It consists of a display circuit 30.

The charging state display circuit 29 inputs the detection signal S2 outputted from the first detection circuit 61 to the base end of the first transistor 150, connects the collector end to the base end of the second transistor 151, and connects the collector end of both transistors to the base end of the second transistor 151. After connecting the second display element 12 to the side, it is connected to the main power source 23 via a switching transistor 152 that is turned on by inputting the auxiliary voltage V2 and a normally closed switch contact 10b. The second display element 12 is a combination of red and green light emitting diodes, and includes a green light emitting diode 153 in series with the first transistor 150, and a green light emitting diode 153 in series with the first transistor 150.
A red light emitting diode 154 is connected in series with 1.

The rotation state display circuit 30 applies the reference voltage taken from both ends of the diode 156 of the second detection circuit 62 to the positive input terminal of the comparison W155, inputs the detection signal S3 to the negative side, and outputs the output terminal. the first transistor 1
It is connected to the base end of 57. Furthermore, the collector end of the first transistor 157 is connected to the base end of the second transistor 158, the green light emitting diode 159 is connected to the first transistor 157, the red light emitting diode 160 is connected to the second transistor 158, and then a normally open switch is connected. Contact 1
It is connected to the main power supply 23 via 0a.

The timing of lighting of each display element 11 and 120 will be explained below using FIG. 8. Note that FIG. 8(f) shows the lighting timing of the pjs2 display element 12, and FIG. 8(g) shows the lighting timing of the first display element 11.

In the above configuration, when the motor is stopped, the inverter circuit 2
2 is activated, the auxiliary voltage V2 is output, the transistor 152 is turned on, and the charging state display circuit 29 starts to be energized. At the same time, the detection signal s2 is output from the first detection circuit 61 at time t.

If the capacity of the secondary pond 6 is decreasing, the light load protection circuit 26 is not controlled, and therefore the value of the detection signal S2 is large, so the first transistor 150 is turned off. The second transistor 151 turns on and energizes the red light emitting diode 154 to indicate that charging is in progress.

Next, as charging progresses and the light load protection circuit 26 is activated and control begins (time 117 t I ), the value of the detection signal S2 intermittently decreases, the first transistor 150 is turned on, and the green light emitting diode is turned on. 153 starts to light up. In other words, red and green lights are alternately lit, and as charging approaches the end, the percentage of green lighting time gradually increases.
The color of the emitted light changes from red to orange, and then changes to green at time t2 to indicate that the battery is fully charged.

Next, when the switch 10 of the main body case 3 is turned on, rotational driving of the motor 5 is started (time t3). Here,
By adjusting the variable resistor 72 of the second detection circuit 62 in advance, the values of the reference voltage and the detection signal S3 are made to substantially match at time t4 when the rotation control circuit 25 loses control.

Then, while the rotation control is effective because the load is small or the voltage of the main power supply 23 is high, the first transistor 157 is turned on and the first display element 11 lights up in green to indicate that it is rotating normally. indicate. However, when the control goes out of control (time t4), the second transistor 158 starts to turn on, and the time that the red light emitting diode 160 lights up gradually increases, changing from green to orange, and then to red at time 1s. Displays abnormalities in motor rotation. 'y! To,
When the rotation of the motor 5 is about to stop (time to), the first
The display element 11 turns off to indicate a decrease in battery capacity.

Note that by disposing the second display element 12 that displays the charging state below the switch 10 on the main body case 3, the operator can manually turn on the second display element 12 while the electric shaver 1 is in use. The display is covered, so even if the lighting of the first and second display elements 11 and 12 is switched by turning on and off the switch 10, the display will not be misunderstood.

Furthermore, since the auxiliary power supply 53 that regulates the on-period of the transistor 152 is configured to be more stable than the first detection circuit 61 and to obtain a sufficiently large output, the second display element 1
The transistor 152 reliably remains on even during the period in which the display element 2 repeats blinking red and green, thereby preventing the display element 12 itself from blinking and flickering.

[Effects of the Invention] As described above, the present invention constantly detects the driving state of the inner cutter, and when an abnormality in this state is detected, the oscillation of the inverter circuit is limited. Damage to the circuit is effectively prevented.

Furthermore, when the motor that drives the inner blade stops, instead of immediately regulating the operation of the inverter circuit, the protective operation is performed after a predetermined delay, which prevents temporary rotation abnormalities such as a large amount of bristles being bitten. It does not malfunction, etc.
Has many advantages.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an outline of the present invention. FIGS. 2 and 3 show an example of implementing the present invention, with FIG. 2 showing an overall perspective view and FIG. 3 showing a TL electric circuit block diagram. Figures 4 to 7 are specific electrical circuit diagrams of Figure 3, in which Figure 4 shows the power supply section, Figure 5 shows the control section, Figure 6 shows the protection section, and Figure 7 shows the display section. Each is shown. FIGS. 8(a) to 8(g) are waveform diagrams illustrating the operation of the electric circuit. 4. . . . Inner blade, 5. . . . Motor, 6. . . Secondary battery, 7. . . Electric circuit, 10. . . Switch, 13. . . Power supply section, 14. . Parts, 15... Control part, 16... Protection part, 17... Display part, 22... Inverter circuit.

Claims (3)

[Claims] (1) A power supply means including an inverter circuit, a means connected to the power supply means to drive the inner cutter, a means for generating a detection signal corresponding to the driving state of the inner cutter drive means, and the detection signal is a set value. Electric shavers equipped with protective measures that limit the oscillations of the inverter circuit. (2) The electric shaver according to claim 1, wherein the driving means is a motor, and the value of the detection signal corresponds to the rotational speed of the motor. (3) The electric shaver according to claim 2, wherein the value of the detection signal reaches the set value after a predetermined time delay after the rotation of the motor stops.