JPH09206497A - Iron - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the current capacity of a power source part small, to reduce a price and to make display easy to see in an iron for pressing out the wrinkles of clothes or the like. SOLUTION: A base part 3 is heated by a heater part, the temperature of the base part 3 is arbitrarily set by a temperature setting part 6, the temperature of the base part 3 is detected by a temperature detection part 4 and energizing to the heater part 1 is controlled by a heater control part 7. A control part 14 controls the heater control part and a display body 15 provided with plural display parts and the display body 15 is constituted of a magnetic inversion element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an iron for wrinkling clothes and the like.

[0002]

2. Description of the Related Art Conventionally, in this type of iron, a corded iron is constructed as shown in FIGS. 13 and 14, and a cordless iron is constructed as shown in FIGS. Hereinafter, the configuration will be described.

Generally, in a corded iron, as shown in FIGS. 13 and 14, the heater portion 1 heats the base portion 3 by the electric power supplied from the commercial power source 2. Then, the temperature of the base unit 3 is detected by the temperature detection unit 4, and the detected temperature signal is output to the control unit 5.

The control unit 5 determines whether the temperature signal sent thereto is higher or lower than the set temperature set by the temperature setting unit 6, outputs the result to the heater control unit 7, and the heater control unit 7 Controls the power supply to the heater unit 1, and the base unit 3
The temperature is controlled to be constant.

The display unit 8 displays the set temperature and the current temperature by operating the temperature setting unit 6, and is controlled by the control unit 5. The power supply unit 9 supplies power to the temperature detection unit 4, the control unit 5, the heater control unit 7, and the display unit 8.

The cordless iron is shown in FIGS. 15 and 1.
As shown in FIG. 6, when the iron part 10 is placed on the stand part 11, the electrode parts P1 and P2 provided on the iron part 10 are provided.
And is connected to the commercial power supply 2 provided in the stand 11 via the electrode parts P2 and P3 provided in the stand part 11, and electric power is supplied from the commercial power supply 2 to the heater part 1 to heat the base part 3.

The temperature of the base portion 3 is detected by the temperature detecting portion 4, and the detected temperature signal is output to the control portion 12, so that the control portion 1
In step 2, it is determined whether the temperature signal sent is higher or lower than the set temperature set by the temperature setting unit 6, and the result is output to the heater control unit 7.

The heater control section 7 is configured to control the temperature of the base section 3 by controlling the electric power supply to the heater section 1. The display unit 8 displays the set temperature and the current temperature by operating the temperature setting unit 6, and is controlled by the control unit 12.

In the placement detecting unit 13, the ironing unit 10 is placed on the stand unit 11, or the ironing unit 1
It is to detect whether 0 is detached from the stand portion 11.

The power supply unit 9 supplies power to control circuits such as the temperature detection unit 4, the heater control unit 7, the display unit 8, the control unit 12, the placement detection unit 13, and the iron unit 10 and the stand unit 11. When it is mounted on the power supply unit 9, the control circuit is operated and the power storage unit built in the power supply unit 9 is charged.

When the ironing part 10 is detached from the stand part 11, the power source is secured by the discharging current of the large-capacity electric storage unit built in the power source part 9, and therefore, it is an important point how to reduce the discharging current. Therefore, when the iron part 10 is detached from the stand part 11, the operation of the display part 8 is stopped and the display is turned off.

A switch S provided on the stand unit 11
W1 and SW2 are turned on when the iron part 10 is placed on the stand part 11, and the commercial power source 2 causes the electrode parts P3 and
Power is supplied to the ironing part 10 through P4 and the electrode parts P1 and P2, and when the ironing part 10 is detached from the stand part 11, it is turned off.

[0013]

In the conventional structure as described above, the display section 8 is composed of a light emitting diode, and a large amount of current is required to light it. Therefore, the current capacity of the power supply section 9 is large. However, when the light emitting diode is exposed to strong light such as direct sunlight, the display is difficult to see.

In addition to the above problems, the cordless iron does not display when the ironing part 10 is detached from the stand part 11, so that the ironing part 10 is not displayed.
However, there is a problem that the optimum time for mounting the stand on the stand 11 is unknown.

The present invention is intended to solve the above problems, and it is a first object of the present invention to reduce the current capacity of a power supply unit to reduce the cost and make the display easy to see.

A second object of the cordless iron is to perform a display operation to notify the user of the power supply time even when the iron part is detached from the stand part.

[0017]

A first means of the present invention is as follows.
In order to achieve the first object, the temperature of the base part to be heated by the heater part is arbitrarily set by the temperature setting part, and the temperature of the base part is detected by the temperature detecting part to control the energization of the heater part by the heater. And a heater control unit and a display unit having a plurality of display units are controlled by the control unit, and the display unit is composed of a magnetic reversal element.

As a result, the current capacity of the power supply unit can be reduced to be inexpensive, and the display can be easily viewed.

Further, in order to achieve the second object, the second means is to contact the iron part and the electrode part of the iron part when the iron part is placed to supply power to the iron part. The iron part consists of a stand part having a part, and the iron part sets the temperature of the base part heated by the heater part arbitrarily by the temperature setting part and detects the temperature of the base part by the temperature detection part to energize the heater part. Is controlled by a heater control unit, and further, the heater control unit and a display unit having a plurality of display units are controlled by the control unit, and the display unit is composed of a magnetic reversal element.

With this, even when the iron part is detached from the stand part, the display operation is performed to inform the user of the power supply timing.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention comprises a base, a heater for heating the base,
A temperature setting unit that arbitrarily sets the temperature of the base unit, a temperature detection unit that detects the temperature of the base unit, a heater control unit that controls energization to the heater unit, and a display unit having a plurality of display units. And a heater control unit and a control unit that controls the display unit, and the display unit is composed of a magnetic reversal element, the current capacity of the power supply unit can be reduced to be inexpensive, and the display is easy to see. be able to.

The invention according to claim 2 is an iron part,
The ironing part comprises a stand part having an electrode part for contacting the electrode part of the ironing part and supplying power to the ironing part when the ironing part is placed. The ironing part heats the base part. A heater part, an electrode part for supplying power to the heater part, a temperature setting part for arbitrarily setting the temperature of the base part, a temperature detecting part for detecting the temperature of the base part, and an iron part as a stand part. A placement detector that detects whether it is placed or detached,
A heater control unit that controls energization to the heater unit, a power supply unit that supplies power to a control circuit, a display unit having a plurality of display units, and a control unit that controls the heater control unit and the display unit. Since the display body is composed of the magnetic reversal element, the display operation can be performed to inform the user of the power supply timing even when the iron part is detached from the stand part.

According to a third aspect of the invention, in the invention according to the first or second aspect, the display unit has a first display section and a second display section, and the control section is at power-on. And "off"
The first display section is displayed at the time of setting, the first display section and the second display section are alternately displayed when the temperature of the base section rises or falls, and the second section is displayed when the temperature of the base section reaches an appropriate temperature. The display body is controlled so as to display the display section of No. 2, and when the first temperature display section is displayed, it is informed that ironing cannot be performed, and the second temperature display section is displayed. When the temperature of the base is ironable, when the first display and the second display are displayed alternately, the temperature of the base is rising or falling. Can be displayed separately.

The invention according to claim 4 is the above-mentioned claim 1.
In the invention described in 3, the control unit controls the first display unit to display the first display unit when the temperature of the base unit is out of a predetermined temperature range.
The display unit is controlled so as to switch the display to the display unit of, and by displaying the first display unit when the temperature of the base unit is out of the predetermined temperature range,
It can be displayed that the temperature of the base is low.

According to a fifth aspect of the present invention, in the above-described first or second aspect of the present invention, a plurality of display bodies are provided, and the control unit decreases as the temperature of the base unit decreases to a predetermined temperature. The display is controlled so that the number of displays on the second display is reduced, and it is clearly displayed that the temperature of the base is decreasing and that the iron cannot be used. You can

According to a sixth aspect of the present invention, in the invention according to the second aspect, the control section is the first section when the iron section is detached from the stand section while the temperature of the base section is rising or falling. The display unit is controlled to display the display unit.If the iron unit is detached from the stand unit while the temperature of the base unit is rising or falling, the temperature of the base unit is not a temperature at which ironing is possible. Therefore, it is possible to display the first display unit and display that ironing cannot be performed.

According to a seventh aspect of the present invention, in addition to the second aspect of the present invention, a power supply voltage detection unit for detecting the voltage of the power supply unit is provided, and the control unit outputs the output of the power supply voltage detection unit. A display unit is controlled so as to switch the display from the second display unit to the first display unit when an input is made and the iron unit separates from the stand unit and the voltage of the power supply unit drops to a predetermined voltage. Then, when the voltage of the power supply unit drops to a predetermined voltage, it can be displayed on the safe side by displaying the first display unit and indicating that the temperature of the base unit is low.

In addition to the invention described in claim 2, the invention described in claim 8 is provided with a plurality of display bodies, and the control section is
The display unit is controlled so that the number of the second display units decreases as the voltage of the power supply unit decreases to a predetermined voltage. The time can be clearly displayed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same components as those in the conventional example are denoted by the same reference numerals, and description thereof is omitted.

(Embodiment 1) As shown in FIG. 1, the control unit 14 receives the output signal of the temperature detection unit 4 as an input and outputs from the temperature setting unit 6 which sets the temperature of the base unit 3 to a desired temperature. When the temperature of the base unit 3 is lower than the set temperature as compared with the input signal, the heater control unit 7 is turned on, and when the temperature of the base unit 3 is higher than the set temperature, the heater control unit 7 is turned off. Control the temperature of.

As shown in FIG. 2, the display body 15 has a first display portion 16a on the front and back of a disk 16 formed of a permanent magnet.
And a second display portion 16b, and is composed of a magnetic reversal element for reversing and displaying the disk 16 by an instantaneous pulse current, which consumes no current other than reversing operation,
The disk 16 is characterized in that it maintains its state even when the current is cut off.

The control unit 14 controls the display unit 15 to display the first display unit 16a when the power is turned on and when the power is turned off, and when the temperature of the base unit 3 rises or falls, the first display unit 16a is displayed. The portion 16a and the second display portion 16b are alternately displayed, and when the temperature of the base portion 3 reaches an appropriate temperature, the second display portion 16b is displayed, and the temperature of the base portion 3 is out of the predetermined temperature range. From the second display portion 16b to the first display portion 16a
The display is switched to.

In the above structure, first, the operation of the display body 15 will be described with reference to FIGS. 2 and 3. When the control section 14 turns on the switch section 17, the coil 18 is turned on.
Current flows through. As a result, the pin 19 is magnetized to the polarity as shown in FIG. 2A, and the disk 16 is inverted to display the first display portion 16a.

On the contrary, when the switch section 20 is turned on,
A current flows through the coil 21, and the pin 19 is magnetized to have a polarity as shown in FIG.
The display unit 16b of is displayed.

Next, the operation of the iron will be described with reference to FIG. As the second display unit 16b is not displayed when the first display unit 16a is being displayed, only one of the first display unit 16a and the second display unit 16b is displayed. There is.

When the power is turned on and "OFF" is set, the first display section 16a is displayed, and the temperature setting section 6 sets an arbitrary temperature to raise the temperature of the base section 3 to the set temperature. Inside, the first display portion 16a and the second display portion 16
b is displayed alternately, and the second display portion 16b is displayed when the appropriate temperature is reached.

Even when the temperature setting of the base portion 3 is set to "low" while the temperature of the base portion 3 is high, the first display portion 16a and the second display portion 16b are alternately switched while the temperature of the base portion 3 is decreasing. Alternatively, the second display portion 16b may be displayed when the appropriate temperature is reached.

Further, as shown in FIG. 5, a predetermined temperature range is provided for each set temperature. For example, when the "medium" setting is set, the set temperature is changed to the "high" setting so that the temperature of the base portion 3 is The temperature of the base part 3 drops by using too much power shot that temporarily raises the amount of steam that is three times or more than the normal amount used to elevate or stretch thick cloths and wrinkles. When it goes out of the range T0 from T1, the second display unit 16b is changed to the first display unit 16a.

As a result, the display 15 reverses and displays the disk 16 by the instantaneous pulse current, so that the current capacity of the power supply unit 9 can be reduced and the cost can be reduced.
The display can be made easy to see.

When the temperature of the base portion 3 rises or falls, the first display portion 16a and the second display portion 16b are alternately displayed, but the first display portion 16a is displayed until an appropriate temperature is reached. Is displayed, and the second display portion 16b is displayed after reaching the appropriate temperature.
May be displayed.

(Embodiment 2) As shown in FIG. 6, the ironing portion 22 is provided with the display body 15 described in the above-mentioned Embodiment 1 instead of the display portion 8 of the conventional example, and this display body 15 is provided. It is controlled by the control unit 23. Other configurations are the same as the conventional example.

The operation of the above configuration will be described with reference to FIG. When the first display portion 16a is being displayed, the second display portion 16b is not displayed.
Either the first display unit 16a or the second display unit 16b is displayed.

When the temperature of the base portion 3 is rising, the first display portion 16a and the second display portion 16b are displayed alternately. Then, while the temperature of the base part 3 is rising, the iron part 2
When 2 is detached from the stand portion 11, the first display portion 16a is displayed, and when it is placed again, the first and second display portions 16b are alternately displayed, and when the appropriate temperature is reached, the second display portion 16a is displayed. The display unit 16b is displayed.

Further, as shown in FIG.
Is separated from the stand portion 11 and the temperature of the base portion 3 drops to a predetermined temperature T5 determined for each set temperature, the second display portion 16b is changed to the first display portion 16a.

As a result, a current is supplied to the display unit 15 only when the display is switched, so that the power consumption of the power supply unit 9 when the ironing unit 22 is detached from the stand unit 11 can be suppressed and the power supply can be maintained for a long time. It is possible to inform the user whether or not the iron is ready for use, not only when it is placed but also when it is detached, by an easy-to-read display.

The first and second display portions 16b are alternately displayed when the temperature of the base portion 3 rises or falls when the base portion 3 is placed, but the first display portion 16a is displayed until the appropriate temperature is reached.
May be displayed, and the second display portion 16b may be displayed after the appropriate temperature is reached.

(Third Embodiment) As shown in FIG. 9, the iron of the third embodiment is provided with a plurality of display bodies 25 to 27 controlled by the control unit 24. Display 25-27
Each has a first display portion and a second display portion, like the display body 15 of the first embodiment, and when the first display portion is displayed, the second display portion is displayed. That is, either one of the first display portion and the second display portion is displayed.

The control section 24 controls the display bodies 25 to 27 so that the number of displayed second display sections decreases as the temperature of the base section 3 decreases to a predetermined temperature. The other structure is the same as that of the first embodiment.

The operation will be described with reference to FIG. 10 in the above-mentioned configuration. The power shot for temporarily producing a steam amount three times or more than the usual amount used for stretching a thick cloth or a wrinkle is used too much for the base portion. When the temperature of No. 3 drops and drops to the predetermined temperature T2 determined for each set temperature, the display of the display body 25 is changed from the second display unit to the first display unit.

When the number of times of using the power shot is increased and the temperature of the base portion 3 is further lowered to the predetermined temperatures T3 and T4, the display bodies 26 and 27 are displayed from the second display portion. Change to the first display.

On the contrary, when the temperature rises, the display of the display 27 is changed from the first display to the second as the temperature of the base 3 rises.
Display unit, and then the display of the display body 26 is changed from the first display unit to the second display unit.
Is changed from the first display section to the second display section.

This makes it possible to clearly show that the temperature of the base portion 3 is decreasing and that the iron has become unusable.

It should be noted that the display body 15 of the second embodiment is composed of a plurality of display bodies 25 to 27, and as the temperature of the base portion 3 decreases to a predetermined temperature, the number of second display portions to be displayed decreases. It goes without saying that the display bodies 25 to 27 may be controlled so as to do so.

(Fourth Embodiment) As shown in FIG. 11, the ironing section 28 is provided with a voltage detecting section 29 for detecting the voltage of the power source section 9, and the output of the voltage detecting section 29 is input to the control section 30. I have to. The control unit 30 controls the display unit 15 to switch the display from the second display unit to the first display unit when the iron unit 28 is detached from the stand unit 11 and the voltage of the power supply unit 9 drops to a predetermined voltage. I'm trying to control. The other structure is the same as that of the second embodiment.

The operation of the above structure will be described with reference to FIG. 12. The voltage of the power source unit 9 is constant when the ironing unit 28 is placed on the stand unit 11, and decreases as soon as the iron unit 28 is detached. . The control unit 30 includes a power supply unit 9
The temperature of the base part 3 is estimated by the voltage of.

For example, the iron part 28 is replaced with the stand part 11
When the control unit 30 receives the output of the voltage detection unit 29 and finds that the voltage of the power supply unit 9 has dropped to the predetermined voltage V1 determined for each set temperature, the display unit 1
5 to control the first display unit 16 from the second display unit 16b.
Change to a.

As a result, when the voltage of the power supply unit drops to a predetermined voltage even after disconnection, the first display unit is displayed to indicate that the temperature of the base unit is low, so that the safety side is displayed. be able to.

In the third embodiment, the base portion 3
Although the display of the plurality of display bodies 25 to 27 is changed depending on the temperature, the plurality of display bodies can be changed by the voltage of the power supply unit 9 when the cordless iron is used.

[0059]

As described above, according to the invention described in claim 1 of the present invention, the base portion, the heater portion for heating the base portion, and the temperature setting portion for arbitrarily setting the temperature of the base portion. And a temperature detection unit that detects the temperature of the base unit,
A heater control unit that controls energization to the heater unit, a display unit having a plurality of display units, a control unit that controls the heater control unit and the display unit, and the display unit is a magnetic reversal element. Therefore, it is possible to reduce the current capacity of the power supply unit to reduce the cost and make the display easy to see.

According to the second aspect of the present invention, a stand having an ironing part and an electrode part for contacting with the electrode part of the ironing part and supplying power to the ironing part when the ironing part is placed. And an iron part, a base part, and a heater part for heating the base part,
An electrode part for supplying power to the heater part, a temperature setting part for arbitrarily setting the temperature of the base part, a temperature detecting part for detecting the temperature of the base part, and an iron part are placed on the stand part. Whether or not detached, a placement detection unit, a heater control unit that controls energization to the heater unit, a power supply unit that supplies power to the control circuit, and a display unit having a plurality of display units, Since the display body is composed of the magnetic reversal element, including the heater control section and the control section for controlling the display body, the display operation is performed even when the iron section is detached from the stand section, and the power supply timing is set by the user. Can be informed.

According to a third aspect of the invention, the display body has a first display section and a second display section, and the control section sets the first display section when the power is turned on and when the power is turned off. No. 1 display unit is displayed, and when the temperature of the base unit rises or falls, the first display unit and the second display unit are alternately displayed, and when the temperature of the base unit reaches an appropriate temperature, the second display unit is displayed. Since the display body is controlled so as to display, it is informed that the ironing cannot be performed when the first temperature display portion is displayed, and the temperature of the base portion is displayed when the second temperature display portion is displayed. Is the temperature at which ironing is possible, and when the first display portion and the second display portion are displayed alternately, the temperature of the base portion is rising or falling, and these are displayed separately. be able to.

Further, according to the invention described in claim 4, when the temperature of the base portion is out of the predetermined temperature range, the control portion switches the display from the second display portion to the first display portion. Since the display body is controlled, it is possible to display that the temperature of the base portion is low by displaying the first display portion when the temperature of the base portion is out of the predetermined temperature range.

Further, according to the invention described in claim 5, the control unit is provided with a plurality of display bodies, and the control unit displays the number of the second display units as the temperature of the base unit decreases to a predetermined temperature. Since the display is controlled so as to decrease, it is possible to clearly display that the temperature of the base portion is decreasing and that the iron cannot be used.

According to the sixth aspect of the present invention, the control section displays the first display section when the iron section is detached from the stand section while the temperature of the base section is rising or falling. Since the display body is controlled, if the iron part is detached from the stand part while the temperature of the base part is rising or falling, the temperature of the base part is not a temperature at which ironing is possible, so the first display part is displayed. It can be displayed to indicate that it cannot be ironed.

Further, according to the invention described in claim 7, a power supply voltage detection unit for detecting the voltage of the power supply unit is provided, the control unit inputs the output of the power supply voltage detection unit, and the ironing unit receives the output from the iron unit. When the voltage of the power supply unit drops to a predetermined voltage after being separated from the display unit, the display body is controlled to switch the display from the second display unit to the first display unit. When the voltage drops, it can be displayed on the safe side by displaying the first display unit and indicating that the temperature of the base unit is low.

Further, according to the invention described in claim 8, a plurality of display bodies are provided, and the control unit controls the number of the second display units as the voltage of the power supply unit decreases to a predetermined voltage. Since the display body is controlled so as to decrease, it is possible to clearly display how the temperature of the base portion is decreasing and the power supply timing.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of an iron according to a first embodiment of the present invention.

FIG. 2 (a) is a perspective view of a main part of a display state of a first display section of the display body of the iron, and (b) is a perspective view of a main part of a display state of a second display section of the display body of the iron.

FIG. 3 is a drive circuit diagram of a display body of the iron.

FIG. 4 is an operation time chart when the temperature of the iron rises.

FIG. 5 is an operation time chart when the temperature of the iron decreases.

FIG. 6 is a block circuit diagram of the iron according to the second embodiment of the present invention.

FIG. 7 is an operation time chart when the temperature of the iron rises.

FIG. 8 is an operation time chart when the temperature of the iron decreases.

FIG. 9 is a block circuit diagram of an iron according to a third embodiment of the present invention.

FIG. 10 is an operation time chart when the temperature of the iron decreases.

FIG. 11 is a block circuit diagram of the iron according to the fourth embodiment of the present invention.

FIG. 12 is an operation time chart when the temperature of the iron decreases.

FIG. 13 is a block circuit diagram of an example of a conventional iron.

FIG. 14 is a side view of the iron with a part cut away.

FIG. 15 is a block circuit diagram of another example of the conventional iron.

FIG. 16 is a side view in which the iron is partially cut away.

[Explanation of symbols]

 1 Heater Section 3 Base Section 4 Temperature Detection Section 6 Temperature Setting Section 7 Heater Control Section 14 Control Section 15 Display

Claims (8)

[Claims] 1. A base section, a heater section for heating the base section, a temperature setting section for arbitrarily setting the temperature of the base section, and a temperature detecting section for detecting the temperature of the base section.
A heater control unit that controls energization to the heater unit, a display unit having a plurality of display units, a control unit that controls the heater control unit and the display unit, and the display unit is a magnetic reversal element. I made an iron. 2. An iron part, and a stand part having an electrode part that contacts the electrode part of the iron part and supplies power to the iron part when the iron part is placed,
The ironing part includes a base part, a heater part for heating the base part, an electrode part for supplying power to the heater part, a temperature setting part for arbitrarily setting the temperature of the base part, and a base part for the base part. A temperature detecting section for detecting the temperature, a placement detecting section for detecting whether the ironing section is placed on or detached from the stand section, a heater control section for controlling energization to the heater section, and a control circuit. An iron comprising: a power supply unit for supplying power to the device; a display unit having a plurality of display units; the heater control unit; and a control unit for controlling the display unit, the display unit being a magnetic reversal element. 3. The display unit has a first display unit and a second display unit, and the control unit displays the first display unit at the time of turning on the power and setting "off", When the temperature rises or falls, the first display section and the second display section are alternately displayed, and when the temperature of the base section reaches an appropriate temperature, the display body is controlled to display the second display section. The iron according to claim 1 or 2. 4. The control unit controls the display body to switch the display from the second display unit to the first display unit when the temperature of the base unit is out of a predetermined temperature range. The iron according to claim 1. 5. The display device comprises a plurality of display members, and the control unit controls the second unit as the temperature of the base unit decreases to a predetermined temperature.
The iron according to claim 1 or 2, wherein the display body is controlled so that the number of display portions of the display unit is reduced. 6. The control unit controls the display body to display the first display unit when the iron unit is detached from the stand unit while the temperature of the base unit is rising or falling. The iron described. 7. A power supply voltage detection unit for detecting the voltage of the power supply unit is provided, wherein the control unit inputs the output of the power supply voltage detection unit, the iron unit is detached from the stand unit, and the voltage of the power supply unit becomes a predetermined value. The iron according to claim 2, wherein the display body is controlled so as to switch the display from the second display unit to the first display unit when the voltage drops. 8. The display unit is provided with a plurality of display units, and the control unit controls the display units so that the number of the second display units decreases as the voltage of the power supply unit decreases to a predetermined voltage. The iron according to claim 2.