JP7672929B2 - Stain removal device - Google Patents

Description

This disclosure relates to a dirt removal device that uses plasma.

Among floor stains, heel marks, which are marks caused by shoes on the floor, are particularly difficult to remove because the frictional heat between the shoe and the floor causes the components of the shoe to become integrated with the components of the floor. The main components of heel marks are polyurethane and nylon, and currently the stains are removed by mechanically scraping the floor surface using a vacuum cleaner called a polisher, or chemically using an alkaline detergent.

Patent No. 4188801

When using a polisher, there is an issue that the floor surface is significantly damaged. In addition, when using an alkaline detergent, there is an issue that the detergent used must be recovered. Although a technology has been proposed to purify the surface to be cleaned using active species generated by a plasma generator (see, for example, Patent Document 1), there is an issue in terms of the time required to remove dirt.

This disclosure provides technology that improves the efficiency of dirt removal.

The dirt removal device disclosed herein comprises a pair of electrodes whose tip portions can be positioned near the surface of the object to be cleaned, and a voltage supply unit that supplies a voltage between the electrodes to generate a creeping discharge along the surface of the object to be cleaned between the electrodes.

This disclosure makes it possible to improve the efficiency of dirt removal.

FIG. 1 is a configuration diagram of a vacuum cleaner according to an embodiment of the present disclosure. Diagram showing examples of dirt on floor surfaces FIG. 2B shows the state of the dirt shown in FIG. 2A after irradiating plasma for 60 seconds using the vacuum cleaner according to the first embodiment. SEM image of floor surface after plasma irradiation FIG. 1 is a diagram showing an example of the waveform of an applied pulse voltage. A diagram showing the relationship between the voltage applied between the electrodes and the number of spark discharges. FIG. 1 is a diagram showing the relationship between the voltage applied between the electrodes and the discharge current. A partial histogram of Fig. 5 A diagram showing the relationship between the voltage applied between the electrodes and the number of spark discharges. FIG. 1 is a diagram showing the relationship between the voltage applied between the electrodes and the discharge current. A diagram showing the relationship between the voltage applied between the electrodes and the number of spark discharges. FIG. 1 is a diagram showing the relationship between the voltage applied between the electrodes and the discharge current. A diagram showing the relationship between the voltage applied between the electrodes and the number of spark discharges. FIG. 1 is a diagram showing the relationship between the voltage applied between the electrodes and the discharge current. A diagram showing the relationship between the voltage applied between the electrodes and the number of spark discharges. FIG. 1 is a diagram showing the relationship between the voltage applied between the electrodes and the discharge current. FIG. 1 shows the evaluation results under condition (1). FIG. 1 shows the evaluation results under condition (2). FIG. 13 shows the evaluation results under condition (3). FIG. 13 shows the evaluation results under condition (4). FIG. 1 shows the measurement results under condition (1). FIG. 1 shows the measurement results under condition (2). FIG. 13 shows the measurement results under condition (3). FIG. 13 shows the measurement results under condition (5).

Below, the embodiments will be described in detail with reference to the drawings. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of already well-known matters or duplicate explanation of substantially the same configuration may be omitted.

The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

(Embodiment 1)
Hereinafter, the first embodiment will be described with reference to FIGS. 1 to 16D.

[1-1. Configuration]
1 shows the configuration of a vacuum cleaner 10 according to an embodiment of the dirt removal device of the present disclosure. The vacuum cleaner 10 includes a suction unit 11, a wiping unit 12, a plasma generating unit 20, and a control unit 30.

The plasma generating unit 20 generates atmospheric pressure plasma and irradiates the cleaning target, such as a floor surface 1, with the plasma in order to remove dirt 2, such as heel marks, that is attached to the cleaning target. The plasma generating unit 20 includes a pair of electrodes 21a, 21b, a power source 22, and a gas supply unit 23.

The pair of electrodes 21a, 21b are configured so that their tip portions can be positioned near the floor surface 1 to generate a creeping discharge along the floor surface 1 to be cleaned. The power source 22 applies a high voltage to the electrodes 21a, 21b to generate a creeping discharge between the electrodes 21a, 21b. The gas supply unit 23 supplies gas for generating plasma between the electrodes 21a, 21b. Since air is usually present near the floor surface 1, if dirt can be removed without supplying gas from the gas supply unit 23, the vacuum cleaner 10 does not need to be equipped with the gas supply unit 23.

The control unit 30 controls each component of the vacuum cleaner 10. The control unit 30 positions the tip portions of the electrodes 21a and 21b at a predetermined height from the floor surface 1 at a predetermined interval. The control unit 30 controls the power source 22 to apply a high voltage between the electrodes 21a and 21b, and controls the gas supply unit 23 to supply a gas to be put into a plasma state between the electrodes 21a and 21b. When the voltage between the electrodes 21a and 21b exceeds a certain limit, a discharge occurs between the electrodes 21a and 21b. This discharge causes the gas present between the electrodes 21a and 21b to become a plasma state, and the gas is irradiated onto the floor surface 1.

Dirt on shoe soles and other surfaces is mainly composed of synthetic resins such as polyurethane and nylon. Dirt on the wheels of carry-on bags and other surfaces is mainly composed of synthetic rubber containing ethylene, propylene, butadiene, etc. By irradiating plasma onto these stains 2, the covalent bonds of the molecules that make up the stain 2 can be cut, and the chemical bonds between the molecules that make up the stain 2 and the molecules that make up the floor surface can be cut, causing the stain 2 to peel off from the floor surface or to vaporize. This allows the stain 2 to be removed efficiently and in a short time without damaging the floor surface 1. The same applies to stains composed of other organic matter, etc.

The suction unit 11 sucks up the dirt 2 peeled off from the floor surface 1 by the plasma. The wiping unit 12 wipes off the dirt 2 decomposed by the plasma. This allows the dirt 2 to be removed from the floor surface 1. If the dirt 2 decomposed by the plasma is oxidized in the air and vaporized as carbon dioxide, carbon monoxide, water vapor, or the like, the vacuum cleaner 10 does not need to include the suction unit 11 and the wiping unit 12. In addition, the vacuum cleaner 10 may only have the function of irradiating the plasma to peel off the dirt 2 from the floor surface 1, and the function of sucking and wiping off the dirt 2 may be performed by another vacuum cleaner or the like. In this case, the vacuum cleaner 10 does not need to include the suction unit 11 and the wiping unit 12.

The plasma generating unit 20 may generate a spark discharge between the electrodes 21a and 21b. In this case, the power source 22 may generate multiple spark discharges in a short period of time by applying a pulsed high voltage between the electrodes. This can shorten the time required to remove the dirt 2, improving the cleaning efficiency.

The plasma generating unit 20 may generate a corona discharge between the electrodes 21a and 21b. In this case, at least the tip portions of the electrodes 21a and 21b may be formed in a needle shape. In this case, too, the time required to remove the dirt 2 can be shortened, and the cleaning efficiency can be improved.

Figure 2A shows an example of dirt 2 attached to floor surface 1. Figure 2B shows the dirt 2 shown in Figure 2A after irradiating plasma for 60 seconds using vacuum cleaner 10 according to embodiment 1. The dirt 2 between electrodes 21a and 21b has been removed. It was confirmed that when argon gas was supplied from gas supply unit 23, the dirt 2 was removed by irradiating plasma for 10 seconds. In addition, when the temperature of the plasma on floor surface 1 was measured with a label-type thermometer, the temperature of floor surface 1 was about 50°C. It was therefore confirmed that the dirt 2 was not removed by the action of heat. Figure 2C shows an SEM image of floor surface 1 after plasma irradiation. It was confirmed that floor surface 1 was not damaged by plasma irradiation.

[1-2. Operation]
The operation and function of the vacuum cleaner 10 configured as above will now be described.

When the user instructs the vacuum cleaner 10 to start cleaning, the control unit 30 positions the tips of the electrodes 21a and 21b at a predetermined height from the floor surface 1 at a predetermined interval. The control unit 30 controls the power source 22 to apply a high voltage between the electrodes 21a and 21b, and controls the gas supply unit 23 to supply a gas to be put into a plasma state between the electrodes 21a and 21b. When the voltage between the electrodes 21a and 21b exceeds a certain limit, a discharge occurs between the electrodes 21a and 21b. This discharge causes the gas between the electrodes 21a and 21b to become a plasma state, which is then irradiated onto the floor surface 1. When the user instructs the vacuum cleaner 10 to end cleaning, or when plasma has been irradiated for a predetermined time, the control unit 30 stops applying the voltage and supplying the gas.

[Example]
The present inventors conducted an experiment to investigate the relationship between plasma generation conditions and dirt removal performance.

Needle-shaped electrodes 21a and 21b were placed on either side of dirt 2 adhering to floor surface 1, sandwiching the dirt 2, and a pulse high voltage was applied between the electrodes from power source 22. Figure 3 shows an example of the waveform of the applied pulse voltage. The peak-to-peak voltage is represented by Vpp, the pulse width by Pw, and the period by T. The duty ratio is represented by Pw/T.

Figure 4 shows the relationship between the voltage applied between the electrodes and the number of spark discharges when the electrode distance is 10 mm, the duty ratio is 10%, and no gas is supplied from the gas supply unit 23. The higher the applied voltage, the more discharges occur.

Figure 5 shows the relationship between the voltage applied between the electrodes and the discharge current when the electrode distance is 10 mm, the duty ratio is 10%, and no gas is supplied from the gas supply unit 23. There is a large variance, but this is because there are abnormal values, as shown in Figure 6. Generally, the higher the applied voltage, the smaller the current value.

Figure 7 shows the relationship between the voltage applied between the electrodes and the number of spark discharges when the interelectrode distance is 5 mm, the duty ratio is 10%, and no gas is supplied from the gas supply unit 23. When the applied voltage is 42.6 kVpp or less, the number of discharges increases as the applied voltage is increased, but when the applied voltage is 42.6 kVpp or more, the number of discharges decreases as the applied voltage is increased.

Figure 8 shows the relationship between the voltage applied between the electrodes and the discharge current when the electrode distance is 5 mm, the duty ratio is 10%, and no gas is supplied from the gas supply unit 23. There is a large variation, but this is also due to the presence of abnormal values. Regardless of the applied voltage, the current value is approximately 0 to 10 A.

Figure 9 shows the relationship between the voltage applied between the electrodes and the number of spark discharges when the electrode distance is 10 mm, the duty ratio is 10%, and air is supplied from the gas supply unit 23 at 20 L/min. In general, the higher the applied voltage, the more discharges occur.

Figure 10 shows the relationship between the voltage applied between the electrodes and the discharge current when the electrode distance is 10 mm, the duty ratio is 10%, and air is supplied from the gas supply unit 23 at 20 L/min. When the applied voltage is 38 kVpp or less, the current value increases as the applied voltage is increased, but when the applied voltage is 38 kVpp or more, the current value decreases as the applied voltage is increased.

Figure 11 shows the relationship between the voltage applied between the electrodes and the number of spark discharges when the electrode distance is 10 mm, the duty ratio is 20%, and no air is supplied from the gas supply unit 23. Figure 12 shows the relationship between the voltage applied between the electrodes and the discharge current when the electrode distance is 10 mm, the duty ratio is 20%, and no air is supplied from the gas supply unit 23. The number of spark discharges is greater than when the duty ratio is 10%. When the applied voltage was higher than 40 kVpp, the floor surface scorched, so measurements were not made at voltages higher than this.

Figure 13 shows the relationship between the voltage applied between the electrodes and the number of spark discharges when the electrode distance is 10 mm, the duty ratio is 30%, and no air is supplied from the gas supply unit 23. Figure 14 shows the relationship between the voltage applied between the electrodes and the discharge current when the electrode distance is 10 mm, the duty ratio is 30%, and no air is supplied from the gas supply unit 23. The number of spark discharges is greater than when the duty ratio is 10%. When the applied voltage was higher than 40 kVpp, the floor surface scorched, so measurements were not made at voltages higher than this.

The heel mark removal performance was evaluated under the following conditions. The heel mark was irradiated with plasma for 60 seconds, and the change rate of pixel value was evaluated by analyzing the images of the heel mark before and after the plasma irradiation. The larger the change rate, the more the dirt was removed.
(1) Interelectrode distance: 10 mm, duty ratio: 10%, air supply: none (2) Interelectrode distance: 5 mm, duty ratio: 10%, air supply: none (3) Interelectrode distance: 10 mm, duty ratio: 20%, air supply: none (4) Interelectrode distance: 10 mm, duty ratio: 10%, air supply: 20 L/min

Figures 15A to 15D show the evaluation results under conditions (1) to (4), respectively. Under all conditions, more dirt was generally removed at the applied voltage that resulted in a greater number of discharges. It is believed that the greater the number of discharges, the more opportunities there are to break down the molecules that make up the dirt, and therefore the greater the efficiency of dirt removal. Also, under condition (4), in which air was supplied from the gas supply unit 23, the greatest amount of dirt was removed. Supplying gas increases the amount of plasma, and therefore it is believed that the greater the efficiency of dirt removal.

Under the conditions below, the maximum temperature within a 1 cm diameter area at a distance of approximately 20 cm from the floor surface was measured using a non-contact radiation thermometer.
(1) Interelectrode distance: 10 mm, duty ratio: 10%, air supply: none (2) Interelectrode distance: 5 mm, duty ratio: 10%, air supply: none (3) Interelectrode distance: 10 mm, duty ratio: 20%, air supply: none (5) Interelectrode distance: 10 mm, duty ratio: 30%, air supply: none

Figures 16A to 16D show the measurement results under conditions (1) to (3) and (5), respectively. Under conditions (1) and (2), the temperature of the floor surface did not rise even when a discharge occurred. It was confirmed that the dirt was not removed due to the effect of temperature, but was removed by the irradiation of plasma. Under conditions (3) and (4), if the voltage was too high, the temperature of the floor surface would rise and the floor would burn. Even in this case, the floor surface could be cooled by supplying gas from the gas supply unit 23.

[1-3. Effects, etc.]
As described above, in this embodiment, the vacuum cleaner 10 includes a pair of electrodes 21a, 21b whose tip portions are arranged so as to be positioned in the vicinity of the floor surface 1 to be cleaned, and a power source 22 that supplies a voltage between the electrodes 21a, 21b to generate a creeping discharge between the electrodes 21a, 21b along the floor surface 1 to be cleaned. This makes it possible to shorten the time required to remove dirt and improve the efficiency of cleaning.

In addition, in this embodiment, the vacuum cleaner 10 further includes a gas supply unit 23 that supplies gas between the electrodes 21a and 21b. This can reduce the time required to remove dirt and improve cleaning efficiency.

In addition, in this embodiment, the vacuum cleaner 10 generates a spark discharge or a corona discharge between the electrodes 21a and 21b. This can shorten the time required to remove dirt and improve the efficiency of cleaning.

In addition, in this embodiment, the tip portions of the electrodes 21a and 21b have a needle-like shape. This improves the cleaning efficiency.

Other Embodiments
As described above, the first embodiment has been described as an example of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made. In addition, it is also possible to combine the components described in the first embodiment to create a new embodiment.

Therefore, other embodiments are given below as examples.

In the first embodiment, the technology for removing heel marks was mainly described, but the stain removal device disclosed herein can be used to remove any type of stain.

The above-described embodiments are intended to illustrate the technology disclosed herein, and various modifications, substitutions, additions, omissions, etc. may be made within the scope of the claims or their equivalents.

This disclosure can be used in stain removal devices.

REFERENCE SIGNS LIST 1 Floor surface 10 Vacuum cleaner 11 Suction unit 12 Wiping unit 20 Plasma generating unit 21a Electrode 21b Electrode 22 Power source 23 Gas supply unit 30 Control unit

Claims (4)

A pair of electrodes having tip portions placed on a surface to be cleaned having dirt containing synthetic resin or synthetic rubber attached thereto , the distance between the tip portions being 5 mm or more and 10 mm or less;
A voltage supply unit that supplies a pulse voltage of 11 kV to 49 kV between the electrodes to generate a creeping discharge along the surface of the cleaning target between the electrodes;
A stain removal device comprising: The stain removal device according to claim 1 , further comprising a gas supply unit that supplies gas between the electrodes. 3. The stain removing device according to claim 1 or 2, wherein a spark discharge or a corona discharge is generated between the electrodes. 4. The dirt removal device according to claim 1, wherein a tip portion of the electrode has a needle-like shape.

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