JPH05200169A - Electric razor - Google Patents

Abstract

PURPOSE:To minimize stimulation by providing a control circuit which judges the density of beard to output a corresponding speed indication signal to a motor with a correction circuit which corrects the speed indication signal according to time from the start of shaving to always obtain a better cutting performance. CONSTITUTION:After the start of a shaving time timer (t) and a timer for measuring fine time, a control circuit 4 picks up a peak value from a current detection circuit 3 while a specified time passes. At the same time, it sets the maximum value to the maximum peak value among the peak values picked up and counts the frequency at which the peak value exceeding a specified value is generated to determine a peak density. When the specified time passes, the number of revolutions to set is determined from a number of revolutions table and moreover, the number of revolutions is corrected by the number of revolutions correction factor corresponding to time from the start of a shaving obtained from the shaving time timer (t) and a motor M is driven at the number of revolutions after the correction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric razor for detecting a darkness of a beard and driving a motor at a rotation speed corresponding to the darkness of a beard.

[0002]

2. Description of the Related Art As a motor used for an electric shaver, one having a constant voltage is conventionally applied,
In some cases, the motor speed is kept constant by feeding back the motor speed.

[0003]

In the former case, when the beard is thick, the load torque increases and the rotation speed decreases, so that good sharpness cannot be obtained. However, if the beard is dark and the motor rotation speed is set to a high value, the person with a thin beard is too stimulating.

In the latter case, stable sharpness can be obtained even if the load torque varies, but the motor rotates at the same number of revolutions regardless of whether the beard is thick or thin. You will not be able to shave well due to lack, and it will take time to shave again. And when the beard is thin, there is a problem that the stimulation is strong. For this reason, it is conceivable that the beard thickness is determined from the motor current and the motor is driven at a rotational speed that corresponds to the determined beard thickness. At the same time, some parts are shaved and some are left unshaved. Therefore, even for the same person, the optimum motor rotational speed changes between the beginning of shaving and the end of shaving, but the above control based on the motor current cannot be sufficient.

The present invention has been made in view of the above circumstances, and an object of the present invention is to rotate a motor at a rotation speed according to the darkness of a user's beard and the time from the beginning of shaving. It is to provide an electric razor that is always sharp and has less irritation.

[0006]

SUMMARY OF THE INVENTION The present invention, however, determines the thickness of a beard in an electric shaver that determines the thickness of the beard from the motor current and controls the motor rotation speed according to the thickness of the beard. The control circuit for outputting the corresponding speed instruction signal to the motor is provided with a correction circuit for correcting the speed instruction signal according to the time from the start of shaving.

[0007]

According to the present invention, the thickness of the beard is automatically determined according to the motor current of the motor, which is the power for shaving, and the motor is rotated at an appropriate number of revolutions according to this depth and the elapsed time from the start of shaving. Is driven.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the illustrated embodiments. In the drawings, M is a motor for driving an inner blade of an electric razor blade, and a motor current detecting resistor R is connected in series to the motor M. Are connected. The resistor R is used for the filter circuit 31, the voltage amplification circuit 32, and the A / D conversion circuit 3.
A current detection circuit 3 that outputs the magnitude of the motor current as a voltage value together with 3 is configured to output an electric signal according to the magnitude of the load during shaving. Since the load during shaving becomes the largest at the moment when a large number of beards are cut at the same time, the change in motor current has some peaks as shown in FIG.

This electric signal is input to the control circuit 4. The control circuit 4 is mainly composed of a microprocessor, and has a peak detection circuit 41 that holds the maximum value Vm of the peak values Vp within a certain time T and a peak density detection circuit that counts the number of peaks within a certain time T. 42, switch SW
A switch detection circuit 43 for detecting ON / OFF of the motor (ON / OFF of the motor M), a shaving time timer t for measuring the shaving time,
The peak detection circuit 41, the peak density detection circuit 42, and a rotation speed selection circuit 44 that outputs a speed instruction signal to the rotation speed control circuit 5 by obtaining a motor rotation speed to be set from the output of the shaving time timer t. When the beard is formed and it is determined that the beard is dark from the maximum peak value and the peak frequency, the motor rotation speed is increased, and when it is determined that the beard is thin, the motor rotation speed is decreased and the shaving time obtained from the shaving time timer t. The motor rotation speed is gradually reduced according to the elapsed time from the beginning.

More specifically, as shown in FIG. 2, when the switch SW is turned on, the control circuit 4 starts the shaving time timer t and the minute time measuring timer t ₂ and then the time T elapses. Until then, the peak value Vp is fetched from the current detection circuit 3, and the maximum value of the fetched peak values Vp is set to the maximum peak value Vm, and a peak value Vp equal to or higher than the predetermined value Vo is generated. The peak density is obtained by counting the number of times of occurrence. When the time T has passed, the maximum peak value V
Based on m and the peak density, the number of revolutions to be set is obtained from the number of revolutions table, and the number of revolutions is corrected by the number of revolutions correction coefficient according to the time from the start of shaving obtained from the shaving time timer t, and the correction is performed. After that, the motor M is driven at the number of revolutions.
This operation is repeated every time the time T elapses.

Here, as shown in FIG. 3, the rotation speed table has a high rotation speed when the maximum peak value Vm is large, and a low rotation speed when the maximum peak value Vm is small, and the peak density is high. If the number of revolutions is high, the number of revolutions is reduced if the peak density is low. As shown in FIG. 4, the number of revolutions correction coefficient is such that the number of revolutions decreases as time passes. In addition, the thinner the whiskers, which are determined from the maximum peak value Vm and the peak density, are, the faster and larger the change of the correction coefficient over time becomes.

Therefore, if it is determined from the motor current that the beard is dark, the motor M is driven at a higher rotational speed, and the rotational speed is gradually lowered as time elapses. If it is determined to be thin, the motor M is driven at a low rotational speed, and the reduction in rotational speed with the passage of time is made earlier and larger than when it is determined that the beard is dark. is there.

It should be noted that the filter circuit 31 in the current detection circuit 3 can be used even if the shaving operation is not actually performed.
If you press the outer blade of the electric razor firmly against your skin, you will see Fig. 6 (a).
This is because the motor current has a large peak P as shown in Fig. 6, and it is composed of a bandpass filter, and as shown in Fig. 6 (b), it has a large level when it is strongly pressed against the skin. The peak P is removed.

FIG. 7 shows another embodiment. This is because the shaving time timer t in the above embodiment counts up only depending on whether or not the switch SW is ON, and the motor M is rotating but the shaving operation is not performed (the time in FIG. 5). This is because the shaving presence / absence detection circuit 45 for detecting whether or not the motor current is above a certain level Vs is provided, and the shaving presence / absence detection circuit 45 actually performs the shaving operation. The shaving time timer t is incremented only while detecting that the shaving has been performed, so that the correction according to the elapsed time from the start of shaving can be performed more accurately. Whether or not the shaving operation is performed may be detected using the outputs of the peak detection circuit 41 and the peak density detection circuit 42.

[0015]

As described above, the present invention automatically determines the thickness of the beard from the motor current of the motor, which is the power for shaving,
Not only can the motor be driven at an appropriate number of revolutions according to this darkness, but also because the motor is driven at a number of revolutions that corresponds to the elapsed time from the start of shaving, when the beard is thick, there is insufficient torque and shaving cannot be done well. Since the stimulation is not too strong when the beard is thin, good sharpness can always be obtained with less stimulation, and the rotation speed of the motor decreases as the shaving progresses. , Quick shave and gentle on the skin.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment.

FIG. 2 is a flowchart of the operation of the embodiment.

FIG. 3 is an explanatory diagram showing a correlation among a maximum peak value, a peak density, and a rotation speed.

FIG. 4 is an explanatory diagram of a correction coefficient according to a lapse of time from the start of shaving.

FIG. 5 is a time chart showing changes in motor current.

6A and 6B are explanatory diagrams showing the operation of the filter circuit.

FIG. 7 is a block diagram showing another embodiment.

[Explanation of symbols]

 t Shaving time timer M motor 3 current detection circuit 4 control circuit 31 rotation speed control circuit

Claims (2)

[Claims] 1. In an electric shaver that determines a beard thickness from a motor current and controls a motor rotation speed according to the beard thickness, the beard thickness is determined and a corresponding speed instruction signal is output to a motor. An electric razor, wherein the control circuit for controlling has a correction circuit for correcting the speed instruction signal according to the time from the start of shaving. 2. The electric razor according to claim 1, wherein the timer that measures the time from the beginning of shaving measures the actual shaving time based on the detection of the shaving operation.