Patent Description:
A conventional washing machine (i. e, a drum type washing machine) is a washing machine, including a drum-type water tub to receive wash water and a cylindrical rotary drum rotatably mounted in the water tub to receive laundry which washes the laundry by lifting and dropping the laundry in the rotary drum during rotation of the rotary drum.

The conventional washing machine detects the weight of laundry (i.e., the amount of load) to determine the amount of wash water according to a user's selection of a washing course, supplies water having an amount sufficient to wet the laundry and detergent into the water tub according to the determined amount of wash water, heats the water and the detergent supplied into the water tub using a heater mounted at the lower part of the washing machine when heating washing is to be performed, and performs a washing operation while the detergent water (i.e., the water plus the detergent), the temperature of which is increased by the heater, is forwarded to the laundry and the laundry is dropped by the rotation of the rotary drum.

However, when using the conventional washing machine, it is necessary to fill a space defined between the water tub and the rotary drum with water to perform the washing. As a result, a large amount of water is used, and therefore, a large amount of energy is required to increase the temperature of the water. Also, as water consumption increases, a large amount of detergent is used to perform high-concentration washing.

Furthermore, laundry, such as wool or silk requiring delicate washing, may be damaged due to the falling of the laundry, the friction between the water and the laundry and the friction between laundry articles caused by the rotation of the rotary drum.

<CIT> discloses a washing machine with a stationary tub and a rotary drum capable of accommodating laundry articles therein. A user may select a preset volume of washing fluid in the tub. The washing machine comprises means for supplying a predetermined amount of air bubbles into the tub in a batchwise manner at such timely interval as to allow the amount of air bubbles supplied in a given batch to be substantially collapsed before a next supply of air bubbles commences.

<CIT> discloses a washing machine with a washing tub having an outer drum body and an inner drum body. Water is supplied from a lower part of the washing tub. The supplied washing water contains fine air bubbles mixed in a bubble generator.

It is an aspect of the present invention to provide a washing machine that is capable of performing washing using bubbles, thereby increasing washability by virtue of high-concentration detergent on bubble surfaces while reducing water consumption.

It is another aspect of the present invention to provide a washing machine that is capable of wetting laundry before bubble generation such that the bubbles easily permeate into the laundry, thereby accomplishing the optimum washing efficiency using the bubbles.

It is another aspect of the present invention to provide a washing machine and that is capable of controlling the amount of wetting water necessary to wet laundry depending upon load of the washing machine, thereby supplying water having an amount adequate to accomplish the optimum wetting efficiency.

It is yet another aspect of the present invention to provide a washing machine that is capable of performing wetting control to wet laundry depending upon kinds of the laundry, thereby reducing the damage to the laundry in small-load delicate washing, in which the wetting control is unnecessary, and reducing washing time.

Additional aspects and/or advantages will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the invention.

The foregoing and/or other aspects of the present invention are achieved by providing a washing machine with the features of claim <NUM>.

Advantageous embodiments are disclosed by the subclaims.

The control unit may detect the amount of load depending upon a weight of the laundry and control the supply of wash water into the water tub to control the amount of wetting water suitable for wetting the laundry depending upon the detected amount of load.

The control unit may increase the amount of wetting water as the amount of load increases. That is, the control unit may increase a number of wetting operations (i.e., wetting times) to wet the laundry or increases an amount of water to be supplied for a one-time wetting operation, to increase the amount of wetting water.

The washing machine may further include an input unit to select a washing course depending upon types of the laundry, and when the selected washing course is normal washing, the control unit controls the water supply unit to directly supply wash water into the water tub such that the laundry is wetted and then the bubble washing is performed.

When the selected washing course is delicate washing, the control unit may control the water supply unit to supply wash water and detergent into a space defined between the water tub and the rotary drum and performs the bubble washing without wetting the laundry.

These and/or other aspects and advantages of the present invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:.

Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiments are described below to explain the present invention by referring to the figures.

<FIG> is a sectional view illustrating the structure of a washing machine using bubbles according to the present invention.

As shown in <FIG>, the washing machine comprises a drum-type water tub <NUM> mounted in a machine body <NUM> to receive wash water and a rotary drum <NUM> rotatably mounted in the water tub <NUM> and having a plurality of through-holes.

A motor <NUM> is mounted at the bottom of the water tub <NUM>, to rotate the rotary drum <NUM> in alternating directions to perform washing, rinsing, and spin-drying operations. In the lower part of the water tub <NUM> are mounted a washing heater <NUM> to heat the wash water supplied into the water tub <NUM> according to a user's selection of water temperature and a water level sensor <NUM> to detect a frequency changed depending upon the water level of the wash water (or concentrated detergent liquid) supplied into the water tub <NUM> to detect the amount (i.e., the water level) of the wash water (or the concentrated detergent liquid).

The water level sensor <NUM> controls a maximum wash water level at which concentrated detergent liquid is not introduced into the rotary drum <NUM>, in which laundry is put (i.e., an optimum water level necessary for bubble generation; hereinafter, referred to as a first water level), to perform washing using bubbles and a minimum wash water level necessary for the bubble generation (a safety water level at which the washing heater is submerged in the detergent water; hereinafter, referred to as a "second water level"). When the amount of the concentrated detergent liquid supplied upon the washing reaches the first water level, the supply of wash water is stopped to prevent the introduction of the concentrated detergent liquid into the rotary drum <NUM>. When the amount of the concentrated detergent liquid is lowered to the second water level due to the bubble generation, wash water is supplied into the water tub <NUM> to maintain concentrated detergent liquid necessary for the bubble generation.

Also, the water level sensor <NUM> controls the concentrated detergent liquid to be maintained at a bubble generation water level at which the bubble generation is possible while the concentrated detergent liquid is not in contact with the laundry through the continuous water level detection in addition to the first and second water levels. Furthermore, the water level sensor <NUM> measures the lowering of the water level through flow rate control or time control during bubble washing to control wash water having an amount necessary for the bubble generation to be supplied.

Also, the water level sensor <NUM> controls a wash water level at which the laundry is wetted before the bubble generation (i.e., the amount of wetting water set depending upon load of the washing machine and types of the laundry; hereinafter, referred to as a "third water level"). The laundry is controlled to be wetted before the bubble generation such that bubbles easily permeate into the laundry during washing.

In the front of the water tub <NUM> and the rotary drum <NUM> are formed openings <NUM>, which are opened and closed by a door <NUM> mounted at the front of the machine body <NUM>.

Above the water tub <NUM> are mounted a detergent supply unit <NUM> to supply detergent, and a water supply unit <NUM> to supply wash water.

The detergent supply unit <NUM> has several partitioned spaces, according to an embodiment of the present invention. Further, according to an embodiment of the present invention, the detergent supply unit <NUM> is mounted at the front side of the machine body <NUM> such that a user easily puts detergent and rinse in the partitioned spaces.

The water supply unit <NUM> comprises a water supply pipe <NUM> to supply wash water and a water supply valve <NUM> mounted on the water supply pipe <NUM> to control the supply of wash water through the water supply pipe <NUM>. The water supply pipe <NUM> is connected with the detergent supply unit <NUM> such that water can be supplied from the outside to the detergent supply unit <NUM>.

A connection pipe <NUM> is mounted between the detergent supply unit <NUM> and the water tub <NUM>, through which the wash water having passed through the detergent supply unit <NUM> is supplied to the water tub <NUM> together with the detergent. A water supply nozzle <NUM> is mounted at the outlet of the connection pipe <NUM>, through which the detergent in the detergent supply unit <NUM> is supplied into the water tub <NUM> together with the wash water to receive high-concentration detergent liquid for bubble generation in a space defined between the water tub <NUM> and the rotary drum <NUM>.

Also, the water supply unit <NUM> further comprises a water replenishment pipe <NUM> connected to the water supply pipe <NUM> to replenish wash water to wet the laundry before bubble generation or replenish wash water necessary for bubble generation, when the water level is lowered due to the bubble generation, and a water replenishment valve <NUM> mounted on the water replenishment pipe <NUM> to control the replenishment of wash water to the water tub <NUM>. The water replenishment pipe <NUM> is connected with the connection pipe <NUM> such that water passing through the water supply pipe <NUM> is directly supplied to the water tub <NUM> not through the detergent supply unit <NUM>.

According to an embodiment of the present invention, the water replenishment valve <NUM> is a three-way valve to control the flow of the wash water such that the wash water passing through the water supply pipe <NUM> is supplied to the detergent supply unit <NUM> or the water replenishment pipe <NUM>.

The washing machine according to an embodiment of the present invention further comprises a drying unit <NUM> to dry laundry (i.e., clothes). The drying unit <NUM> comprises a drying fan <NUM> mounted at the top of the water tub <NUM>, a drying duct <NUM> connected between an outlet port 41b of the drying fan <NUM> and an air inlet port <NUM> formed at the upper side of the opening <NUM> of the water tub <NUM>, and an condensing duct <NUM> mounted at the rear of the water tub <NUM> to connect an air outlet port <NUM> formed at the lower part of the rear side of the water tub <NUM> and an inlet port 41a of the drying fan <NUM>.

The drying unit <NUM> further comprises a drying heater <NUM> mounted in the drying duct <NUM> to supply hot air into the water tub <NUM> and an condensing unit mounted in the condensing duct <NUM> to condense wet steam generated during drying of the clothes.

The condensing unit comprises a cooling water injection nozzle <NUM> mounted in upper part of the condensing duct <NUM> to inject cooling water into the condensing duct <NUM> and a cooling water supply pipe <NUM> and a cooling water valve <NUM> connected to the water supply unit <NUM> to supply cooling water to the cooling water injection nozzle <NUM>. Consequently, cooling water injected from the cooling water injection nozzle <NUM> falls downward along the condensing duct <NUM> with the result that the cooling water is brought into contact with wet air rising upward, whereby the dehumidification efficiency is improved.

The washing machine according to an embodiment of the present invention further comprises a drainage unit <NUM> to drain water out of the water tub <NUM>. The drainage unit <NUM> comprises a drainage pipe <NUM> connected to the bottom of the water tub <NUM> to guide the water in the water tub <NUM> to the outside and a drainage pump <NUM> mounted at the drainage pipe <NUM>.

The washing machine according to an embodiment of the present invention further comprises an air supply unit <NUM> to supply air such that the laundry in the rotary drum <NUM> is washed by bubbles. The air supply unit <NUM> comprises an air motor <NUM> mounted below the water tub <NUM> to supply air, an air supply pipe <NUM> to forward the air supplied by the air motor <NUM>, and a porous member <NUM> mounted at one end of the air supply pipe <NUM> to disperse the supplied air. The air supplied by the air motor <NUM> passes through the porous member <NUM> via the air supply pipe <NUM>. At this time, the air is dispersed to generate bubbles in detergent water having concentrated detergent liquid and wash water mixed with each other. Consequently, it is possible to wash the laundry in the rotary drum <NUM> only using the bubbles.

Air holes <NUM> are formed in the water tub <NUM> where the air supply unit <NUM> is mounted, through which air from the air supply unit <NUM> is flows. Consequently, air dispersed by the porous member <NUM> is introduced into a space between the water tub <NUM> and the rotary drum <NUM> through the air holes <NUM>.

<FIG> is a control block diagram of a washing control unit of the washing machine according to an embodiment of the present invention. In addition to the components shown in <FIG>, the washing machine further comprises a signal input unit <NUM>, a temperature detection unit <NUM>, a dry detection unit <NUM>, a control unit <NUM>, and a drive unit <NUM>.

The signal input unit <NUM> inputs operation information, such as a washing course (for example, normal washing or delicate washing) selected by a user depending upon types of laundry, upon washing, using bubbles and a washing temperature (hereinafter, referred to as a "predetermined temperature"), spin-drying RPM, and addition of rinsing set by the user, to the control unit <NUM>.

The temperature detection unit <NUM> detects the temperature of wash water supplied into the water tub <NUM>, and the dry detection unit <NUM> detects the temperature and the humidity of the laundry to detect the dryness of the laundry.

The control unit <NUM> is a microcomputer to control the washing machine based on the operation information inputted from the signal input unit <NUM>. The control unit <NUM> stores motor RPM and operation rate (i.e., motor on-off time), washing time, and the number of water resupply operations N (i.e., the number of water resupplies to resupply water to the first water level necessary for bubble generation when the water level is lowered due to the bubble generation) set depending upon the amount of load (i.e., the weight of laundry) in the selected washing course, and the optimum amount of wetting water Dw to wet the laundry depending upon the amount of load.

Consequently, the control unit <NUM> controls the amount of wash water to be supplied together with the bubble generation during bubble washing, controls the motor RPM, the operation rate, and the amount of wetting water depending upon the amount of load, and controls the start point of the bubble generation depending upon the temperature of wash water (water temperature). Specifically, the control unit <NUM> controls the driving of the motor <NUM>, the water supply unit <NUM>, and the air motor to accomplish the optimum washing efficiency while reducing the damage to the laundry.

The drive unit <NUM> drives the motor <NUM>, the washing heater <NUM>, the water supply valve <NUM>, the water replenishment valve <NUM>, the drying fan <NUM>, the drying heater <NUM>, the drainage pump <NUM>, the cooling water valve <NUM>, and the air motor <NUM> according to a drive control signal of the control unit <NUM>.

Hereinafter, the operation of the washing machine with the above-stated construction and a washing control method of the washing machine according to an embodiment of the present invention will be described referring to <FIG>.

According to the washing control method, it is possible to select normal washing and delicate washing depending upon types of laundry in a bubble washing course to wash the laundry using bubbles. The above-described signal input unit <NUM> comprises a button to input a command to select the normal washing or the delicate washing in the bubble washing course to the control unit <NUM>.

<FIG> is a flow chart illustrating a washing control method using bubbles in the washing machine according to an embodiment of the present invention.

When a user puts laundry in the rotary drum <NUM> and selects a bubble washing course, the operation information selected by the user is inputted to the control unit <NUM> through the signal input unit <NUM>.

Consequently, in operation <NUM>, the control unit <NUM> determines whether the washing course selected by the user is the bubble washing course based on the operation information inputted from the signal input unit <NUM>. When washing course is not the bubble washing course, the process moves to operation <NUM>, where the control unit <NUM> controls a standard washing course to be performed.

When the washing course selected by the user is the bubble washing course, the user selects operation information, such as a washing course (i.e., normal washing or delicate washing), washing temperature, spin-drying RPM, and addition of rinsing, based on types of the laundry in operation <NUM>, and the operation information selected by the user is inputted to the control unit <NUM> through the signal input unit <NUM>.

Subsequently, the process moves to operation <NUM>, where the control unit <NUM> detects the amount of load (i.e., the weight of the laundry) W put in the rotary drum <NUM> and sets the amount of wash water, the motor RPM and operation rate (i.e., motor on-off time), washing time, and the number of water resupply operations N (i.e., the number of water resupplies to resupply water to the first water level necessary for bubble generation when the water level is lowered due to the bubble generation) for each washing course based on the detected amount of load W in operation <NUM>.

In this embodiment of the present invention, setting the number of water resupply operations N is to restrict water resupply actions depending upon the amount of laundry, thereby reducing unnecessary water supply actions.

Subsequently, the process moves to operation <NUM>, where the control unit <NUM> performs a washing operation using bubbles for the predetermined washing time based on the amount of wash water, the motor RPM and operation rate, washing time, and the number of water resupply operations N, all of which are set for each washing course depending upon the amount of load W.

In the washing operation using bubbles, the bubbles serve as a cushion when the friction between laundry articles occurs, whereby the damage to the laundry due to the friction between the laundry articles and strong water stream is reduced. Also, contaminants are effectively removed from the laundry using a small amount of water by virtue of high detergent concentration of the bubbles, whereby energy is saved.

After the washing operation using bubbles is performed, the process moves to operation <NUM>, where rinsing and spin-drying operations set based on the amount of load are performed.

Hereinafter, the process for performing the washing course using bubbles (in operation <NUM>), which is the technical characteristic of the present invention, will be described with reference to <FIG> and <FIG>.

<FIG> and <FIG> are flow charts illustrating a washing operation using bubbles in the washing machine according to an embodiment of the present invention.

First, in <FIG>, in operation <NUM>, it is determined whether the washing course selected by the user is normal washing. When the selected washing course is the normal washing, the process moves to operation <NUM> where the control unit <NUM> controls the optimum amount of wetting water necessary to wet the laundry depending upon the amount of load (i.e., the weight of the laundry) W.

This is to control the optimum amount of wetting water necessary to wet the laundry depending upon the amount of load W to supply water having an amount adequate to accomplish the optimum wetting efficiency and to enable bubbles to easily permeate into the uniformly wetted laundry.

When the amount of wetting water is controlled depending upon the amount of load W to wet the laundry, the control unit <NUM> controls the water supply valve <NUM> and the water replenishment valve <NUM> to supply high-concentration detergent liquid necessary for bubble generation such that wash water is supplied into the water tub <NUM> through the water supply pipe <NUM> and the detergent supply unit <NUM> to supply high-concentration detergent liquid necessary for the bubble generation. At this time, the detergent in the detergent supply unit <NUM> is dissolved by the wash water and supplied together with the wash water into the water tub <NUM> through the connection pipe <NUM> and the water supply nozzle <NUM> with the result that concentrated detergent liquid (the wash water containing the detergent in a concentrated state) is supplied into the lower part of the water tub <NUM> (specifically, the space between the water tub and the rotary drum) in operation <NUM>.

On the other hand, when it is determined at in operation <NUM> that the selected washing course is not the normal washing, the control unit <NUM> determines that the selected washing course is delicate washing, and the process moves to operation <NUM> to directly supply high-concentration detergent liquid necessary for bubble generation without performing the wetting control to wet the laundry depending upon the amount of load W.

By advancing to operation <NUM>, unnecessary wetting control is omitted since the volume of the laundry is small in small-load washing, such as delicate washing, and therefore, the bubbles easily permeate into the laundry without wetting the laundry upon the washing using the bubbles. In the normal washing to wash a large amount of laundry, the laundry is wetted at the beginning of the water supply, and then the bubble washing is performed.

As the wash water containing the detergent is supplied into the water tub <NUM>, the space between the water tub <NUM> and the rotary drum <NUM> is filled with the concentrated detergent liquid including the detergent and the wash water mixed with each other. At this time, the water level of the concentrated detergent liquid is detected by the water level sensor <NUM> to determine whether the water level is the predetermined first water level (i.e., the maximum wash water level at which the wash water supplied into the tub is not introduced into the rotary drum; approximately <NUM>/<NUM> of the normal wash water level) in operation <NUM>.

When the water level is not the first water level, wash water containing detergent continues to be supplied until the water level reaches the first water level. When the water level is the first water level, the control unit <NUM> turns the water supply valve <NUM> and the water replenishment valve <NUM> off to stop the supply of wash water in operation <NUM>.

Subsequently, the process moves to operation <NUM>, where the washing heater <NUM> is driven to heat the concentrated detergent liquid to a temperature suitable for bubble generation and the motor <NUM> is stopped such that the laundry in the rotary drum <NUM> is washed with the bubbles. The reason to stop the motor <NUM> is to rapidly heat the concentrated detergent liquid to a temperature suitable for bubble generation.

At this time, the amount of water supplied into the space between the water tub <NUM> and the rotary drum <NUM> is less than that of water in the normal washing operation. Consequently, the water is rapidly heated by the washing heater <NUM>, and therefore, the total washing time is reduced and energy necessary to heat the water is saved.

Subsequently, the temperature of the concentrated detergent liquid (i.e., the water temperature) heated by the washing heater <NUM> is detected by the temperature detection unit <NUM> to determine whether the detected temperature exceeds a predetermined bubble generation temperature (i.e., a temperature at which bubbles are easily generated; approximately <NUM>) in operation <NUM>.

When the water temperature does not exceed the bubble generation temperature, the washing heater <NUM> continues to be driven until the water temperature reaches the bubble generation temperature. When the water temperature exceeds the bubble generation temperature, as shown in <FIG>, the control unit <NUM> drives the air motor <NUM> to generate bubbles such that air is supplied into the concentrated detergent liquid including the detergent and the wash water mixed with each other to generate bubbles in operation <NUM>). The bubbles are generated as follows: air supplied by the air motor <NUM> passes through the porous member <NUM> via the air supply pipe <NUM> with the result that the air is dispersed. The dispersed air is introduced into the concentrated detergent liquid including the detergent and the wash water mixed with each other through the air holes <NUM>, whereby bubbles are generated.

In this embodiment, the bubble generation using the porous member <NUM> was described; however, the present invention is not limited to the above-described construction.

The bubbles generated in the space between the water tub <NUM> and the rotary drum <NUM> is introduced into the rotary drum <NUM> through the through-holes or the opening of the rotary drum <NUM>. The bubble introduced into the rotary drum <NUM> is dispersed throughout the rotary drum <NUM> after a predetermined time (approximately <NUM> minutes), and therefore, the laundry in the rotary drum <NUM> is washed only using the bubbles.

At this time, the process moves to operation <NUM>, where the control unit <NUM> determines whether the water temperature exceeds a user-predetermined temperature when the bubbles are generated by the driving of the air motor <NUM>. When the water temperature exceeds the predetermined temperature, the process moves to operation <NUM>, where the control unit <NUM> stops the driving of the washing heater to interrupt the heating of the wash water.

This is to heat the concentrated detergent liquid to the user-predetermined temperature (the minimum being approximately <NUM>) after heating the concentrated detergent liquid to the bubble generation temperature at which the bubbles are easily generated (approximately <NUM>) through the driving of the washing heater <NUM>. When the concentrated detergent liquid is heated by the washing heater <NUM> and the temperature of the heated concentrated detergent liquid reaches the user-predetermined temperature, the washing heater <NUM> is stopped with the result that the hot water washing using the bubbles is performed at the optimum conditions desired by the user.

Subsequently, the process moves to operation <NUM>, where the control unit <NUM> determines whether the bubbles introduced into the rotary drum <NUM> exceeds a bubble amount detection level (i.e., a level at which bubbles having an amount suitable for the washing progress are generated after the bubble generation is initiated at the first water level; a level at which approximately <NUM>/<NUM> of the rotary drum is filled with the bubbles).

When the bubbles exceeds the bubble amount detection level, the process moves to operation <NUM>, where the control unit <NUM> drives the motor <NUM> to operate the rotary drum <NUM> at a predetermined second RPM (less than the washing RPM) and operation rate such that the washing is performed using the bubbles.

During the bubble generation, it is preferable for the predetermined RPM, operation rate, and washing time of the rotary drum <NUM> to be equal to or less than values set depending upon the amount of load.

The bubbles are dispersed throughout the rotary drum <NUM> by the rotation of the rotary drum <NUM> together with the bubble generation, and contaminants are effectively removed from the laundry by high detergent concentration of the dispersed bubbles. At this time, the bubbles serve as a cushion when the laundry falls and the friction between laundry articles occurs due to the rotation of the rotary drum <NUM>, whereby the damage to the laundry is prevented.

As the washing operation using the bubbles progresses, the amount of the concentrated detergent liquid is reduced. At this time, the water level of the concentrated detergent liquid is detected by the water level sensor <NUM> to determine whether the water level is the predetermined second water level which is the minimum wash water level necessary for the bubble generation, i.e., the safety water level at which the washing heater is submerged in the concentrated detergent liquid in operation <NUM>.

When the water level is not the second water level, the bubble generation is continued and the washing is performed while the rotary drum <NUM> is rotated until the water level reaches the second water level. When the water level is the second water level, the process moves to operation <NUM>, where the control unit <NUM> stops the air motor <NUM> to interrupt the bubble generation.

When the water level reaches the second water level, and therefore, the air motor <NUM> is stopped, the process moves to operation <NUM>, where the control unit <NUM> determines whether water resupply actions to resupply water necessary for bubble generation have been repeated the predetermined number of water resupplies N (S626).

When it is determined at operation <NUM> that the water resupply actions have not been repeated the predetermined number of water resupplies N, the control unit <NUM> controls the water supply valve <NUM> and the water replenishment valve <NUM> such that the wash water is not supplied to the detergent supply unit <NUM> through the water supply pipe <NUM> but to the water tub <NUM> through the water replenishment pipe <NUM>, the connection pipe <NUM>, and the water supply valve <NUM> to further supply water necessary for the bubble generation in operation <NUM>. This is to maintain the bubble generation water level necessary for the bubble generation.

As the wash water is further supplied into the water tub <NUM>, the water level in the space between the water tub <NUM> and the rotary drum <NUM> is detected by the water level sensor <NUM> to determine whether the detected water level is the predetermined first water level in operation <NUM>.

When the detected water level is not the first water level, wash water continues to be further supplied (resupplied) into the water tub <NUM> until the water level reaches the first water level. When the water level is the first water level, the control unit <NUM> turns the water supply valve <NUM> and the water replenishment valve <NUM> off to stop the further supply of water (water resupply) in operation <NUM>. Then, the process returns to operation <NUM>, which is performed to generate bubbles until the performance is repeated the predetermined number of water resupplies N.

Hereinafter, the process for controlling the amount of wetting water depending upon the amount of load W in the normal washing of the bubble washing course to wash a large amount of laundry (operation <NUM> shown in <FIG>) will be described with reference to <FIG>.

<FIG> is a flow chart illustrating a process to control the amount of wetting water depending upon the amount of load in the washing machine according to an embodiment of the present invention.

When the normal washing is selected in the bubble washing course, the control unit <NUM> controls the amount of wetting water according to the detected amount of load W. The amount of wetting water may be controlled by the following two methods.

The first method is to increase the number of wetting times when the amount of load is increased, thereby increasing the amount of wetting water. For example, when the amount of load is <NUM> to <NUM>, the number of wetting times is set to be <NUM>. When the amount of load is <NUM> to <NUM>, the number of wetting times is set to be <NUM>. When the amount of load is <NUM> to <NUM>, the number of wetting times is set to be <NUM>. When the amount of load is <NUM> to <NUM>, the number of wetting times is set to be <NUM>. In this way, the laundry is uniformly wetted depending upon the amount of load.

The second method is to increase the amount of water to be supplied for one-time wetting, thereby increasing the amount of wetting water. For example, when the amount of load is <NUM> to <NUM>, the amount of wetting water is set to be <NUM>. When the amount of load is <NUM> to <NUM>, the amount of wetting water is set to be <NUM>. When the amount of load is <NUM> to <NUM>, the amount of wetting water is set to be <NUM>. When the amount of load is <NUM> to <NUM>, the amount of wetting water is set to be <NUM>. In this way, the laundry is uniformly wetted depending upon the amount of load.

It is possible to supply the amount of wetting water suitable for the amount of load W using any one of the above-described methods. In this embodiment, however, the second method of controlling the amount of supplied water to control the amount of wetting water depending upon the amount of load W will be described below.

Specifically, when the detected amount of load W is not more than <NUM> (in operation <NUM>), the amount of wetting water Dw is set to be <NUM> (in operation <NUM>). When the detected amount of load W is more than <NUM> but not more than <NUM> (in operation <NUM>), the amount of wetting water Dw is set to be <NUM> (in operation <NUM>). When the detected amount of load W is more than <NUM> but not more than <NUM> (in operation <NUM>), the amount of wetting water Dw is set to be <NUM> (in operation <NUM>). When the detected amount of load W is not within the range defined at in operation <NUM>, the detected amount of load W is determined to be more than <NUM>, and therefore, the amount of wetting water Dw is set to be <NUM> (in operation <NUM>).

After the amount of wetting water Dw is set depending upon the detected amount of load W, the control unit <NUM> controls the water supply valve <NUM> and the water replenishment valve <NUM> such that wash water necessary to wet the laundry is not supplied to the detergent supply unit <NUM> through the water supply pipe <NUM> but directly to the water tub <NUM> through the water replenishment pipe <NUM>, the connection pipe <NUM>, and the water supply valve <NUM> (in operation <NUM>).

This is to wet the laundry, before the bubble generation, to effectively perform the washing operation using bubbles such that the volume of the laundry is reduced, and therefore, the bubbles easily permeate into the laundry.

As the wash water necessary to wet the is directly supplied into the water tub <NUM>, the water level of the wash water supplied into the water tub <NUM> is detected by the water level sensor <NUM> to determine whether the detected water level is the predetermined third water level (i.e., the amount of wetting water set depending upon the amount of load) (in operation <NUM>).

When the wash water level is not the third water level, wash water continues to be directly supplied into the water tub <NUM> until the wash water level reaches the third water level. When the wash water level is the third water level, the control unit <NUM> turns the water supply valve <NUM> and the water replenishment valve <NUM> off to stop the water supply (in operation <NUM>).

After the water supply is stopped, the control unit <NUM> drives the motor <NUM> to operate the rotary drum <NUM> at a predetermined first RPM (less than the washing RPM) and operation rate such that the laundry is wetted by the water supplied into the water tub <NUM> (in operation <NUM>).

During the wetting operation, it is preferable for the predetermined RPM and operation rate of the rotary drum <NUM> to be equal to or less than values set for each washing course depending upon the amount of load.

Subsequently, the control unit <NUM> counts a motor driving time to wet the laundry to determine whether a predetermined time (approximately <NUM> minutes) has elapsed (in operation <NUM>). When the predetermined time has elapsed, the process moves to operation <NUM>, which is performed to supply high-concentration detergent water necessary for bubble generation.

In this embodiment, the wetting operation was performed in the normal washing of the bubble washing course; however, the present invention is not limited to the wetting operation in the normal washing. For example, the wetting operation may be performed in delicate washing. The result of the washing operation using bubbles according to an embodiment of the present invention is shown in <FIG>.

<FIG> is a graph illustrating washabilities when 60MU (Make Up) contaminated cloth is washed using detergent water and bubbles at the same concentration. Specifically, the graph shows reflexibility (%) at amounts of detergent having the same concentration (<NUM>, <NUM>, and <NUM>).

It can be seen from <FIG> that the washability in the washing operation using the bubbles was higher than that in the washing operation using the normal detergent water.

As apparent from the above description, the washing machine according to an embodiment of the present invention has the effect of performing washing using bubbles, thereby increasing washability by virtue of high-concentration detergent on bubble surfaces while reducing water consumption.

Also, the washing machine according to the present invention has the effect of wetting laundry before bubble generation such that the bubbles easily permeate into the laundry, thereby effectively accomplishing the washing operation using the bubbles. Furthermore, the washing machine according to the present invention has the effect of controlling the amount of wetting water necessary to wet laundry depending upon load of the washing machine, thereby supplying water having an amount adequate to accomplish the optimum wetting efficiency.

In addition, the washing machine according to the present invention has the effect of performing wetting control to wet laundry depending upon kinds of the laundry, thereby reducing the damage to the laundry in small-load delicate washing, in which the wetting control is unnecessary, and reducing washing time.

Claim 1:
A washing machine, having a water tub (<NUM>) and a rotary drum (<NUM>) to receive laundry, to perform washing using bubbles, the washing machine comprising:
a water supply unit (<NUM>) to supply wash water;
a detergent supply unit (<NUM>) to store detergent and a water supply pipe (<NUM>) to supply wash water to the detergent supply unit (<NUM>);
a water replenishment pipe (<NUM>) diverging from the water supply pipe (<NUM>) to replenish wash water;
a bubble generation unit to generate bubbles; and
a control unit (<NUM>) to control the water supply unit (<NUM>) to directly supply the wash water into the water tub (<NUM>) before bubble generation, to control the rotary drum (<NUM>) to rotate at a predetermined RPM based on determining that wash water contained in the water tub (<NUM>) reaches to a predetermined water level, to control the water supply unit (<NUM>) to supply the wash water and the detergent based on determining that a predetermined time has elapsed since the rotary drum (<NUM>) rotates, and to control the bubble generation unit to generate bubbles from the supplied wash water, and to perform the washing using the generated bubbles;
wherein the water supply unit (<NUM>) supplies the wash water to the detergent supply unit (<NUM>) such that the detergent stored in the detergent supply unit (<NUM>) is dissolved to form concentrated detergent liquid;
wherein the water supply unit (<NUM>) directly supplies the wash water into the water tub (<NUM>) not through the detergent supply unit (<NUM>) but through the water replenishment pipe (<NUM>); and
wherein the control unit (<NUM>) controls the water supply unit (<NUM>) to directly supply the wash water into the water tub (<NUM>) through the water replenishment pipe (<NUM>) to wet the laundry before the wash water and the detergent are supplied into the space between the water tub (<NUM>) and the rotary drum (<NUM>).