JPH03224590A - Lifetime display device for blade of hair cutter - Google Patents

Abstract

PURPOSE:To inform the arrive of replacement time of a blade by measuring the use time of a device, comparing a lifetime of the blade stored in advance and the measured use time, and displaying the lifetime. CONSTITUTION:A lifetime display device 6 is constituted of a control circuit 3 consisting of a timer for measuring the use time of an electric razor and a microcomputer constituting a comparing circuit comparing the use time and a lifetime, a nonvolatile memory 4 is which the use time and the service lifetime are stored, and a display part 5. In the nonvolatile memory 4, data, etc., of a total use time extending from the time when an electric razor 10 is used first to the present time point, a blade use time being a use time extending from the time when the blade is replaced in the previous time to the present time point, a motor lifetime, a battery lifetime, and a blade lifetime are stored in each address. In such a state, the use time of the electric razor and the lifetime of the blade are compared, and when the use time reaches the lifetime, the lifetime display is executed. In such a way, the replacement time of the blade can be informed to a user.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lifespan display device that indicates when the blade of a hair cutting device such as an electric razor, an electric hair clipper, or an electric pill remover has reached the end of its lifespan.

[Conventional technology]

Conventionally known hair cutting devices include those in which an inner blade reciprocally driven by a motor slides on the inner surface of an outer blade fixed to the main body of the hair cutting device, and one in which a rotatably driven inner blade slides on an outer blade. The comb-shaped movable blade, which is driven reciprocally, slides on the comb-shaped fixed blade.

The blades of this hair cutting device electric shaver wear out as they are used, becoming dull and the cut hair becomes easily scattered, so they need to be replaced each time.

[Problem to be solved by the invention]

However, since it is not possible to check the degree of wear on the blade, users often replace the blade when they determine that the blade has become dull. As a result, there were many cases in which worn blades were continued to be used without knowing when to replace the blades, making it impossible to obtain good sharpness.

The present invention was made in view of the above circumstances, and its purpose is to provide a blade for a hair cutting device that can indicate that the blade has reached the end of its lifespan and notify the user when it is time to replace the blade. An object of the present invention is to provide a lifespan display device.

[Means to solve the problem]

The blade lifespan display device of a hair cutting device according to the invention described in claim (1) measures the usage time of the hair cutting device, compares the measured usage time with a pre-stored blade lifespan, and determines the usage time. It is configured to display a lifespan display when the time reaches the lifespan time.

A lifespan display device for a blade of a hair cutting device according to the invention set forth in claim (2) is provided with a nonvolatile memory for storing the lifespan time and usage time in the device set forth in claim (1).

The lifespan display device for a blade of a hair cutting device according to the invention set forth in claim (3) is provided with means for setting the thickness of the beard in addition to the device set forth in claim (1), and the lifespan time is set according to the setting of the setting means. It is configured to change or correct the usage time.

The lifespan display device for the blade of the hair cutting device according to the invention described in claim (4) detects the current flowing through the motor that drives the blade in the hair cutting device according to the invention described in claim (1), and changes the lifespan according to this current. , or the usage time is corrected.

The lifespan display device for the blade of the hair cutting device according to the invention set forth in claim (5) detects the current flowing through the motor that drives the blade in the hair cutting device set forth in claim (1), and when this current is larger than a predetermined current. It is configured to measure usage time only.

[For production]

In the blade life display device of a hair cutting device according to the invention as claimed in claims (1) to (5), the usage time of the electric razor is compared with the blade life time, and the usage time reaches the life time. By displaying the lifespan display at times, it is possible to display that the blade has reached the end of its lifespan and notify the user when it is time to replace the blade.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on FIGS. 1 to 4.

FIG. 1 is a block circuit diagram showing the circuit configuration of an electric shaver 10 equipped with a life display device 6. As shown in FIG. electric razor 10
The machine is composed of a motor 1 that drives the blade, and a storage battery B connected to the motor 1 via a power switch SWI. A charging circuit 2 is connected to the storage battery B.

The life display device 6 includes a control circuit 3 consisting of a microcomputer that constitutes a timer that measures the usage time of the electric shaver and a comparison circuit that compares the usage time with the life time.
Non-volatile memory 4 that stores usage time and lifespan
and the display section 5 are the main components.

The control circuit 3 is connected in parallel to the storage battery B, and is supplied with power from the storage battery B. A timer configured inside the control circuit 3 starts and stops in conjunction with the opening and closing of the power switch SWI. The control circuit 3 performs comparison calculation processing of data stored in the non-volatile memory 4 and controls the operation of the display section 5 that displays the life of the blade, etc., and has a processing program stored in advance. The control circuit 3 also serves as a control circuit for the charging circuit 20, and causes the charging circuit 2 to charge the storage battery B using a well-known charging control method.

The non-volatile memory 4 internally stores a plurality of storage addresses 4a to 4a.
4e, the total usage time T0 from the time you first used the electric razor IO to the present time, and the blade usage time T which is the usage time from the time you last replaced the blade to the present time.
I, motor life time to+, storage battery life time tow, blade life time 1. data is stored in each address. Address 4e for storing blade life time t1
furthermore, multiple addresses 4e+, 4ez + 4e
* Consists of +4ea.

Three levels of lifespan time t1゜+ F I depending on the thickness of the beard
+ tlz (tz>tzo>tlz) and the lifespan time t in these three stages according to the setting of the beard thickness setting means 7, which will be described later. The data of the blade life time t1 selected from ~t12 are stored at the addresses 4e+ and 4ez.
, 4e+, 4e4. Among the addresses, the address that stores the total usage time T0, blade usage time T1, and blade life time t1 can be read and written, and the address stores the motor life time t. l, storage battery life time toz
The addresses for storing the three stages of life time t1° to t1□ can only be read.

Among each data, motor life time to+, storage battery life time [. The life times t1°+Lll +j+□ of the second and third stages are stored in advance at the manufacturing stage of the electric shaver. These life times differ depending on the model used, so in the case of motors and storage batteries, the life times set in the ratings are stored. For example, the lifespan tel of a standard motor used in an electric shaver is 10
0 hours, and the life time toz of the storage battery is about 300 hours. The three stages of lifespan t1゜~t1□ are for people with standard beard thickness, as the degree of wear on the blade differs depending on the thickness of the user's beard, and the lifespan of the blade changes. Three levels are set and memorized for people with thin beards and for people with thick beards. For example, the lifespan of commonly used blades is 25 hours for people with standard thick beards, 30 hours for people with thin beards, and 2 hours for people with thick beards.
It is set to 0 hours. Of course, the life time differs depending on the type of blade used, so when using different types of blades,
The life time to be memorized is changed for each model that uses the blade.

The nonvolatile memory 4 is connected to the input and output ports of the control circuit 3 so that the control circuit 3 can read and write data.

A blade exchange reset switch S-2, a setting switch S-3, and a display section 5 are connected to the control circuit 3.

The display section 5 is provided on the surface of the housing of the electric shaver 10, as shown in FIG.
, a second lifespan display section 5b that displays that the blade has reached its lifespan, and setting state display sections 5c, 5d, and 5e of a beard thickness setting means 7, which will be described later. Each display section is composed of a light emitting means such as an LED. Characters are written on each display to indicate the meaning of the display. The first lifespan display section 5a displays r, which means that the product itself has reached its lifespan.
END J, the second life display section 5b displays rcHANGEJ, which means that the blade has reached the end of its life and needs to be replaced.
, the setting status display sections 50 to 5e of the setting means 7 display rTlllNJ and rNORMA, which represent the thickness of the beard, respectively.
The letters LJ and rTHIcKJ are written on it.

The setting means 7 for setting the thickness of the beard is the setting switch SW3.
and a control circuit 3, and the user can select this setting switch S.
By operating W3, you can set the thickness of your beard in three levels. The setting switch total 3 is formed of a bushing switch, and is provided below the setting state display sections 5C to 5e of the display section 5.

The blade replacement reset switch SW2 is operated when the blade is replaced to reset the blade usage time T1 stored in the nonvolatile memory 4. The blade exchange reset switch SW2 may be formed of, for example, a bushing switch to prevent it from being accidentally operated during normal use, and the operation button may be placed in a recess formed in the bottom of the housing of the electric shaver 10. Or move the operation button to housing 1.
0, a small hole may be formed in the housing, and the tip of a thin pin or the like may be inserted into the small hole for operation.

The control operation of the control circuit 3 will be explained below based on the flowcharts of FIGS. 2, 3, and 5.

FIG. 2 explains the process from when the control circuit 3 starts in the reset state to normal processing.

When the storage battery B is in an empty state with no remaining capacity, the control circuit 3 consisting of a microcomputer is in a recycle state. The non-volatile memory 4 stores the previously stored usage time data To.
, T+ and life time data t01゜t02+
tI+j+. ~ttz is stored in memory. When a power source is connected to the charging circuit 2 and charging starts, the battery voltage rises and when it exceeds the operating voltage of the control circuit 3, the control circuit 3
starts working.

First, the total usage time T0 up to the previous time and the blade usage time T are stored in the internal memory from the non-volatile memory 4.

Next, it is determined whether the power switch pot 1 is turned on, that is, whether the electric shaver body is in use, based on the signal input from the power switch SWI. When the power switch SWI is on, a timer in the control circuit 3 is started to start measuring the usage time. This measured usage time t is added to the total usage time T0 read out earlier, and this added time (
T0+t) is rewritten as the new total usage time T0.

Next, this rewritten total usage time T.

is the motor life time t read from the non-volatile memory 4
. Compare with l. When the total usage time T0 is longer than the motor life time tel (To > toe), an operation signal is output to the display section 5 to light up the LED of the first life display section 5a. In the next step, the total usage time T0 is similarly compared with the storage battery life time toz read from the non-volatile memo January, and the total usage time T0 is greater than the storage battery life time toz (To > to2 ), the first life display section 5a is lit.

Furthermore, in the next step, the usage time t measured by the timer in the control circuit 3 is converted into the usage time T read out earlier.
, and rewrite this added time (TI + t) as a new total usage time T1.

Next, the rewritten blade life time T1 is compared with the blade life time t1 read from the nonvolatile memory 4. The blade life time T is greater than the blade life time Tl (TI >
t, ), the LED of the second life display section 5b is turned on.

After completing the above steps, determine whether the power switch SWI is off, that is, whether use is completed,
If the power switch SW1 remains on, that is, if it is still in use, the usage time t continues to be measured, and the measured usage time t is used as the total usage time T. Returning to the step of adding , the above steps are repeated until the power switch SWI is turned off.

When the power supply switch SWI is turned off, the timer in the control circuit 3 is stopped, and the total usage time T stored in the internal memory of the control circuit 3 at this point. and the usage time T, are written into the non-volatile memory 4.

When the above steps are completed, the process returns to the step of determining whether the power switch 1 is on, and when the power switch SWI is turned on again, the above steps are executed again. If the power switch SWI remains off, the process moves to step (2) shown in FIG.

FIG. 3 shows the process when the blade replacement reset switch or 2 is operated when the blade life is displayed and the user replaces the blade in response to the above-described series of processes.

First, the user replaces the blade, and it is determined whether the blade replacement reset switch SW2 has been operated. If the blade has not been replaced and the blade replacement reset switch SW2 has not been operated, the process returns to step (2) of determining whether the previous power switch SWI is on.

When the blade replacement reset switch SW2 is operated, the winding time T1 is reset, and by writing this to the non-volatile memory 4, the data of the winding time T stored in the non-volatile memory 4 is reset. .

After the above processing is completed, the process returns to step (3) of determining whether the power switch SWI is on, and the above processing is repeated until the power switch SWI is turned on.

As explained above, each time the use of the electric shaver is completed, the data T0T1 of the usage time at that point is written to the nonvolatile memory 4, so the storage battery B becomes empty.
Even when the control circuit 3 is reset, the data T, , T1 of the usage time at that time is not reset and is stored and held in the nonvolatile memory 4.

Further, in this embodiment, the storage battery B is used as the power source, but an alternating current may be used as the power source. In this case, when the AC power supply is connected, the control circuit 3 that was in the reset state starts operating, and the usage time data T is stored from the nonvolatile memory 4.
When O and T are read out and the AC power source is removed, the usage time data T, , T, stored in the non-volatile memory 174 at that time is stored and retained.

First and second life display sections 5a in this embodiment.

It is also possible to configure 5b with a voice synthesis circuit using the control circuit 3, a buzzer, etc. in place of the LED.

Below, the operation of the setting means 7 for setting the thickness of the beard will be explained as follows.
This will be explained based on the flowchart shown in FIG.

The thickness of the beard is set by operating the setting switch SW3. First, it is determined whether the setting switch SW3 has been operated, and if the setting switch SW3 has been operated, 1 is added to the number of operations ON of the setting switch SW3, and the number of operations stored in the internal memory of the control circuit 3 is calculated. O
Update the data of N. Next, it is determined whether the number of operations ON has reached 4, and when the number of operations ON is 4, the number of operations ON is 4.
Return the data of N to 1. When the number of operations is 3 or less, the process moves to the next step with the number of operations data unchanged.

When the number of operations is 1, the LED of the setting status display section 5c of the display section 5 is turned on, and the three-stage life time t1゜tll +jl stored in advance in the nonvolatile memory 4 is displayed.
□ Out of (1++>1+.>t+z), the second life time t, which has the longest life time, is copied to the address 4e+ of the blade life time t1 for use in determining the life of the blade.

Through the above processing, the beard is set to be thin (THIN).

On the other hand, when the number of operations is 2, the setting state display section 5d of the display section 5 is turned on, and the first life time tI0, which has an intermediate life time, is set to the address 4 of the blade life time t1.
Copy it on e+. Through the above processing, the thickness of the beard is set to the standard (NORMAL).

Further, when the number of operations is 3, the setting state display section 5e of the display section 5 is turned on, and the third life time t+z, which is the shortest life time, is copied to the address 4e of the blade life time t1. Through the above processing, the beard becomes thicker (THrCK
) are set.

The above process is executed every time the setting switch SW3 is operated, and the setting status display sections 5c to 5e move in the order of 5c → 5d → 5e, so the user can adjust the beard that suits him while looking at this display. You can set the darkness. The data at the address del for the blade life time t is set using the setting switch S.
It is rewritten and changed every time W3 is operated.

As explained above, the degree of wear of the blade differs depending on the thickness of the beard, and even if the lifespan of the blade changes, the lifespan time t1 of the blade can be adjusted according to the thickness of the beard, and the lifespan time t1° + t
+ I + F□ can be selected and changed, so the life of the blade can be displayed very accurately.

Moreover, the life time of three stages t1°~tl! Instead of selecting the blade life time according to the setting of the thickness of the beard,
The processing described below may also be performed.

When performing this process, the non-volatile memory 4 stores only the life time for a beard of standard thickness as the blade life time t.

When the use time t is measured by the control circuit 3, three different coefficients kO, k,
, kg by the measured usage time t.

Add this converted time t゛ to the blade usage time T1,
The lifespan of the blade is determined by comparing it with the blade lifespan time t stored in the non-volatile memory 4.

The three different coefficients ko, k+, kg are, for example, the coefficient ko=l for a standard thick beard, the coefficient ko=l for a thin beard, and the coefficient i+z for a thick beard.
= 1.2.

FIG. 7 shows a second embodiment of the present invention, which differs from the previous embodiment only in the configuration of the beard density setting means 7. This setting means is composed of a current sensor connected in series to the motor 1 and a control circuit 3. The current sensor detects the current flowing through the motor 1, is composed of a current detection resistor, and generates a voltage according to the magnitude of the current.

The control circuit 3 includes an A/D conversion circuit that converts voltage input from the current sensor into a digital signal.

The voltage input from the current sensor to the control circuit 3 is processed as data representing the magnitude of the load on the motor l.

The process of setting the beard density in the control circuit 3 will be explained below.

First, it is determined whether the power switch 1 is on, and when the power switch SWI is on, the initial current Io flowing through the motor 1 is detected from the voltage input from the current sensor and stored in the internal memory. Initial current of motor 1 ■. In the case of an electric razor, this is the current flowing through the motor 1 from when the power switch weight 1 is turned on until shaving begins, that is, the no-load current of the motor 1.

Initial current■. After detecting, the current flowing to motor 1 is
, is detected and compared with the previously stored initial current I0. When the detected current I is larger than the initial current I0, the current
, and the initial current■. , that is, the magnitude of the load applied to the motor 1, and calculate the difference value I, -16 between the two currents by two predetermined values 1. , L (1°〈I,), and the magnitude of the load is identified into three levels. The fact that the detected current I becomes larger than the initial current I0 means that the motor 1 changes from a no-load state in which the motor 1 is running idly without shaving to a load applied to the motor 1 when shaving begins. This means that the flowing current has increased.

When the difference value between both currents is smaller than ■1, non-volatile memory 4
Three lifetime times t, stored in advance.

Ell +jl□ (t+ + >t+o> t+□)
Among them, the second life time tll, which has the longest life time, is
In order to use it for determining the lifespan of the blade, it is copied to the address 4e+ of the blade lifespan time t1. Through the above processing, the beard is set to be thin (THIN).

On the other hand, the difference value between the two currents is two predetermined values ■.

When it is between and ■, copy the first life time t1°, which is the middle life time, to the address 4e+ of the blade life time tl. Through the above processing, the thickness of the beard becomes the standard (NORM)
AL).

In addition, when the difference value between the two currents is larger than the predetermined value ■, the third life time t+z, which is the shortest life time, is replaced by the blade life time t.
Copy it to address 4e+ of 1. Through the above processing, the setting is made that the beard is thick (THICK).

As explained above, according to the setting means of this embodiment, the current flowing through the motor 1 is detected and the thickness of the beard is automatically set according to this current. Then, the blade life time t1 is selected according to the set thickness of the beard, and the blade life time t is changed, so that the user and others can perform the setting operation as in the previous embodiment. There is no need to do this. Further, since the setting switch SW3 and the setting state display sections 50 to 5e, which were present in the previous embodiments, are no longer necessary, the structure is simplified.

Furthermore, as explained in the previous embodiment, instead of selecting the blade life time t1 from the three stages of life time t I O'' t l□ according to the setting of the thickness of the whiskers, 0.kl, 2 to 2 with different coefficients selected depending on the darkness setting
may be converted by multiplying the usage time t of the blade. The content of this process is the same as the process described in the previous embodiment, so the explanation will be omitted.

FIG. 8 shows a third embodiment of the present invention, which differs from the previous embodiment only in the method of measuring usage time.

Although FIG. 8 only explains the life display of the blade, the structure of the life display of the motor 1 and storage battery B is as follows:
Since this is the same as the previous embodiment, the explanation will be omitted.

In this embodiment, a current sensor is connected in series to the motor 1,
The output voltage of this current sensor is configured to be input to the control circuit 3. The current sensor detects the current flowing through the motor 1, is composed of a current detection resistor, and generates a voltage according to the magnitude of the current. The control circuit 3 converts the voltage input from the current sensor into a digital signal.
/D conversion circuit is provided internally. The control circuit 3 includes a dedicated timer for measuring the usage time of the blade. This timer is configured separately from a timer that measures the usage time of the motor 1 and power storage on other days.

The voltage input from the current sensor to the control circuit 3 is processed as data representing the magnitude of the load on the motor 1.

The processing operation of the control circuit 3 will be explained below. Incidentally, FIG. 8 shows the control circuit 3 starting from the reset state and ending with normal processing.

When the storage battery B is in an empty state with no remaining capacity, the control circuit 3 consisting of a microcomputer is reset. When a power source is connected to the charging circuit 2 and charging of the storage battery B is started, the battery voltage increases, and when the battery voltage becomes equal to or higher than the operating voltage of the control circuit 3, the control circuit 3 starts operating.

First, from non-volatile memory 4, the time T of heaven use until the previous time is stored.
1 is read and stored in internal memory.

Next, it is determined whether the power switch SWI is on, and when the power switch SWI is on, the initial current (■) flowing to the motor 1 is determined from the voltage input from the current sensor. is detected and stored in internal memory.

Initial current■. After detecting the current flowing through the motor
, is detected and the initial current stored previously ■. Compare with. When the detected current It becomes larger than the initial current I0, a timer in the control circuit 3 is reset and started to start measuring the usage time t.

The detection current ■ is the initial current ■. In the following cases, check again whether the power switch SWI is on, and if it remains on, the current is 1. Return to the step of detecting.

If the power switch SWI is turned off, this means that use has been discontinued, and the process returns to the previous step of determining whether the power switch 1 is on.

The detection current I is the initial current ■. When the value is greater than t, a timer is started to start measuring the usage time t. The measured usage time t is the sky usage time T read out in advance.
, and this added time (T, + t) is rewritten as the new angel usage time T1.

Next, the blade life time t read out from the nonvolatile memory 4 is the rewritten blade life time T.

Compare with. The blade usage time is T, but the blade life time is 1. If it is larger (T, >t, ), L on the life display section 5b
Turn on the ED. If the blade usage time T+ is equal to or less than the blade life time t, proceed to the next step.

In this step, the detected current ■, is compared with the initial current I0, and if the detected current I, is larger than the initial current I0, since the beard is still being shaved, the current l flowing through the motor 1 is detected and measured. The usage time t in the middle is the current usage time T1
Return to the step of adding to . On the other hand, the detection current I is the initial current ■. In the following cases, the electric razor 10 is removed from the face and shaving is interrupted, or the power switch SWI is turned off and shaving is completed, so the timer is stopped and the shaving operation is completed at this point. The heaven usage time T1 is written into the non-volatile memory 4.

When the above processing is completed, it is determined whether the power switch needle 1 is on, and if it is off, shaving is completed, and the process returns to the step of determining whether the power switch SWI is on or not in preparation for the next use. .

When the power switch SWI is on, the electric razor 10 is removed from the face and shaving is interrupted, so the process returns to the step of detecting the current flowing through the motor l.

By the above process, after turning on the power switch SWI and driving motor 1, excluding the time when motor 1 is running idly without shaving, the usage time is the time when actually shaving. This improves the accuracy of determining the life of the blade. Furthermore, if the motor 1 is driven but the blade is left as it is without shaving, and the blade life is displayed even though the blade has not reached the end of its life, there is a risk of giving the user a sense of distrust. Yes, but there is no need to worry about that.

Although each of the above-mentioned embodiments uses an electric razor, an electric hair clipper, an electric pill remover, or the like may also be used.

〔Effect of the invention〕

Since the life display device for the blade of the hair cutting device of the present invention is configured as described above, it has the following effects.

The device described in claim (1) measures the usage time of the electric razor, and when the usage time reaches the pre-stored blade life time, a life display is displayed, so that the user can know the blade life. When the blade has reached this point, you will know that it is time to replace the blade, and you can replace the blade accordingly, so you can continue to use a worn blade and maintain good sharpness. This can eliminate the problem of not being able to obtain

In addition to the above-mentioned effects, the device described in claim (2) stores the life time and the usage time in a non-volatile memory, so even when the life display device loses power, the data on the usage time up to that time is stored. The device according to claim (3) and claim (4) is stored in a non-volatile memory, and the usage time data is not erased and the lifespan cannot be displayed.
1) In addition to the effects described above, by changing the blade lifespan depending on the thickness of the beard or correcting the usage time of the electric razor, the thickness of the beard differs depending on the person, and the lifespan of the blade can be reduced. Even if the blade changes, the lifespan of the blade can be accurately displayed.

Furthermore, in the device according to claim (4), the current flowing through the motor is detected and the beard density is automatically set according to this current, so that the user can set the beard density. No need to do it.

The device described in claim (5), in addition to the effect of the device described in claim (1), detects the current flowing through the motor, and detects the current flowing in the motor only when this current is larger than a predetermined current that is greater than or equal to the no-load current of the motor. Since the usage time is measured, the actual shaving time can be measured as the usage time, which improves the accuracy of determining the blade life.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram showing one embodiment of the present invention, FIGS. 2 and 3 are flowcharts thereof, and FIG. 4 is a block circuit diagram showing an embodiment of the present invention.
A front view of the display section, FIG. 5 is a flowchart, FIG. 6 is an explanatory diagram of the main part of the nonvolatile memory, FIG. 7 is a flowchart showing the second embodiment of the present invention, and FIG. 8 is a flowchart. , a flowchart showing a third embodiment of the present invention. 1-Motor, 3-Control circuit, 4--Nonvolatile memory, 5--Display section, 5a, 5b--Lifetime display section, 6...
-Lifetime display device, 7.-Setting means, 10-Electric shaver. Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (5)

[Claims] (1) A lifespan display device for the blade of a hair cutting device, which measures the usage time of the hair cutting device, compares the measured usage time with a pre-stored blade lifespan, and determines how long the usage time is. A lifespan display device for a blade of a hair cutting device, which displays the lifespan when the time is reached. (2) A lifespan display device for a blade of a hair cutting device according to claim 1, further comprising a non-volatile memory for storing lifespan and usage time. (3) The life of the blade of the hair cutting device according to claim (1), wherein a means for setting the thickness of the beard is provided, and the life time is changed or the usage time is corrected according to the setting of the setting means. Display device. (4) The lifespan display of the blade of the hair cutting device according to claim (1), wherein the current flowing through the motor that drives the blade is detected, and the lifespan time is changed or the usage time is corrected according to this current. Device. (5) The life of the blade of the hair cutting device according to claim (1), wherein the current flowing through the motor that drives the blade is detected, and the usage time is measured only when this current is larger than a predetermined current. Display device.