US20140021140A1

US20140021140A1 - Method for controlling dehydration or water removal in drum washing machine

Info

Publication number: US20140021140A1
Application number: US14/008,521
Authority: US
Inventors: Ui Kun HWANG
Original assignee: Dongbu Daewoo Electronics Corp
Current assignee: WiniaDaewoo Co Ltd
Priority date: 2011-03-28
Filing date: 2012-03-27
Publication date: 2014-01-23
Also published as: EP2692929A4; WO2012134139A2; CN103443348A; WO2012134139A3; EP2692929A2

Abstract

A method for controlling dehydration or water removal in a drum washing machine, which repetitively measures an unbalance value at different speeds during balance spin-drying for spreading laundry items before main spin-drying is performed in a drum washing machine, and senses an unbalance for forward and backward directions of a drum as well as an unbalance for the rotational direction of the drum so that the laundry items are redistributed in a relatively normal manner. Thus, since vibrations of the tub may be reduced during the spin-drying process, the spin-drying efficiency may be improved.

Description

TECHNICAL FIELD

The present invention relates to a method for controlling dehydration (or water removal) in a drum washing machine, and more particularly, to a method for controlling dehydration in a drum washing machine, which repetitively measures an unbalance value at different speeds during a balance spin-drying process for spreading laundry items and before a main spin-drying process is performed in the drum washing machine, and senses an unbalance for forward and backward directions of the drum as well as an unbalance for rotational direction of the drum, thereby increasing spin-drying efficiency.

BACKGROUND ART

General washing machines may be divided into pulsator washing machines, agitator washing machines, and drum washing machines, depending on the washing method.
According to the pulsator washing machine, a rotatable pulsator at the bottom of a washing tub is rotated to generate a vortex of water, thereby spinning laundry items.
According to the agitator washing machine, when a washing rod known as an agitator in the center of a washing tub is regularly rotated, an agitating wing formed at the side of the washing rod forms a water flow. Then, as the water flows causes laundry items to come in frictional contact with the washing rod and the wall of the washing tub, the laundry items are washed.
According to the drum washing machine, a cylindrical drum having a plurality of water holes therein is horizontally installed in a tub. As the drum is rotated, a lifter within the drum lifts laundry items towards an upper space of the drum, and the lifted laundry items fall downward due to gravity. Such a process is repeated to wash the laundry items. When the drum washing machine is used, damage to laundry items may be reduced, the laundry items may not get tangled, and a washing effect of beating and rubbing the laundry items may be achieved.
Such a washing machine washes laundry items while performing a washing process, a rinsing process, and a spin-drying process. The washing process includes a water supply operation, a washing operation, and a drain operation, which are performed to remove stains, dirt, and other soiling in laundry items using wash water containing detergent therein. The rinsing process includes a spin-drying operation, a water supply operation, a rinsing operation, and a drain operation, which are performed to rinse foam and residual detergent from the laundry items using clean wash water containing no detergent. The spin-drying process includes a spin-drying operation which is performed to spin-dry the laundry items.

DISCLOSURE

Technical Problem

An aspect of the present invention provides a method for controlling dehydration (or water removal) in a drum washing machine, which repetitively measures an unbalance value at different speeds, for example during a balance spin-drying process for spreading laundry items and before a main spin-drying process is performed, and senses an unbalance for forward and backward directions of the drum as well as an unbalance for the rotational direction of the drum, thereby increasing spin-drying efficiency.

Technical Solution

According to an aspect of the invention, a method for controlling dehydration (or water removal) in a drum washing machine includes: simultaneously agitating and balance spin-drying laundry in the drum, then accelerating a motor of the washing machine to a laundry adherence speed; detecting a first unbalance value when the motor reaches the laundry adherence speed; accelerating the motor to a water removal speed according to the first unbalance value; detecting a second unbalance value when the motor reaches the water removal speed; and comparing the first unbalance value and the second unbalance value to obtain a comparison result, and performing main spin-drying according to the comparison result.
When the first unbalance value is less than a preset value, the motor may be accelerated to the water removal speed, and when the first unbalance value is equal to or greater than the preset value, the method may continue or repeat the balance spin-drying process.
When the first unbalance value is equal to or less than the second unbalance value, the main spin-drying process may be performed, and when the first unbalance value is greater than the second unbalance value, the method may repeat the balance spin-drying process.
Detecting the second unbalance value may include detecting a variation between forward and backward motions of a tub of the drum washing machine.
When the variation between forward and backward motions of the tub is less than a preset variation, the main spin-drying process may be performed, and when the variation between forward and backward motions of the tub is equal to or greater than the preset variation, the method may repeat the balance spin-drying process.
The variation between the forward and backward motions of the tub may be measured using a distance from the tub by a distance measurement sensor on a rear surface of a front panel of the drum washing machine.
The variation between the forward and backward motions of the tub may be additionally or alternatively measured using a distance from a magnet attached to the tub by a Hall sensor on the rear surface of the front panel.

Advantageous Effects

According to embodiment(s) of the invention, an unbalance value and forward and backward motions of the tub are measured at different speeds during the balance spin-drying process for spreading laundry items before the main spin-drying process is performed in the drum washing machine. Thus, an unbalance for forward and backward directions of the drum as well as an unbalance for rotational direction of the drum may be sensed to uniformly distribute the laundry items. Therefore, vibration of the tub may be reduced during a spin-drying operation, which makes it possible to increase spin-drying efficiency.

DESCRIPTION OF DRAWINGS

The above and other aspects, features and advantages of the invention will become apparent from the following detailed description in conjunction with the accompanying drawings, in which:

FIG. 1 is a cross-sectional view schematically illustrating a drum washing machine in accordance with one or more embodiment(s) of the present invention;

FIG. 2 is a block configuration diagram illustrating a control circuit of the drum washing machine in accordance with embodiment(s) of the present invention;

FIGS. 3A and 3B are diagrams illustrating states of laundry items put into the drum washing machine according to embodiment(s) of the present invention;

FIG. 4 is a diagram illustrating a state in which a Hall sensor is installed in the drum washing machine according to embodiment(s) of the present invention;

FIG. 5 is a flowchart for explaining a method for controlling dehydration (or water removal) in a drum washing machine according to an embodiment of the present invention;

FIG. 6 is a graph illustrating a spin-drying process of the drum washing machine according to embodiment(s) of the present invention; and

FIG. 7 is a flowchart for explaining a method for controlling dehydration (or water removal) in a drum washing machine according to at least one other embodiment of the present invention.

BEST MODE

Embodiments of the invention will hereinafter be described in detail with reference to the accompanying drawings. It should be noted that the drawings are not necessarily to precise scale and may be exaggerated in thickness of lines or sizes of components for descriptive convenience and clarity only. Furthermore, the terms as used herein are defined by taking functions of the invention into account and can be changed according to the custom or intention of users or operators. Therefore, definition of the terms should be made according to the overall disclosures set forth herein.
FIG. 1 is a cross-sectional view schematically illustrating a drum washing machine in accordance with embodiment(s) of the present invention.
FIG. 1 illustrates a state in which water is supplied to a predetermined water level 15 in a tub 10 which surrounds a drum 11 housing laundry items 14 therein. When the drum 11 is rotated, the laundry items 14 dipped or at least partially immersed in wash water are moved upward by the lifter(s) 12. Then, when the laundry items 14 reach a certain position, the laundry items 14 fall due to their own weight. Such a process is repeated to wash the laundry items 14.
Furthermore, a washing heater 13 for heating the wash water and/or laundry items is installed at the bottom of the drum 11, in order to improve washing capability and/or efficiency, and/or obtain an effect of boiling and/or washing the laundry.
FIG. 2 is a block configuration diagram illustrating a control circuit of the drum washing machine in accordance with embodiment(s) of the present invention.
The control circuit includes a load cell sensor 21, a water level sensor 29, a microcomputer, microcontroller or other logic circuit 20, a water supply controller 22, a drain controller 24, a motor driving controller 27, a washing heater 13, and a distance measurement sensor 30. The load cell sensor 21 is configured to sense the weight of the laundry items 14 in the drum 11. The water level sensor 29 is configured to sense the level of wash water within the tub 10. The microcomputer 20 is configured to receive the values of the load cell sensor 21 and the water level sensor 29 and control the overall operations of the drum washing machine. The water supply controller 22 is configured to control the operation of a water supply valve 23 according to a water supply control signal from the microcomputer 20. The drain controller 24 is configured to control the operations of a drain valve 26 and/or a drain motor 25 according to a drain control signal from the microcomputer 20. The motor driving controller 27 is configured to control the operation of a motor 28 for rotating the drum 11 according to a motor control signal from the microcomputer 20. The distance measurement sensor 30 is configured to detect forward and backward motions of the tub 10. The washing heater 13 serves to heat wash water according to a control signal from the microcomputer 20.
The operation of the drum washing machine configured in such a manner will be described as follows.
First, when a user opens a door of the drum washing machine, puts laundry items into the drum 11, and turns on a washing operation start switch, the load cell sensor 21 detects the weight of the laundry items 14 within the drum 11. The weight of the laundry items sensed by the load cell sensor 21 is input to the microcomputer 20.
Then, the microcomputer 20 determines an amount of water to supply by referring to a memory table that stores predetermined values of the amount of water corresponding to a particular weight or weight range of laundry in the drum, and outputs a control command to the water supply controller 22 to open the water supply valve 23. Then, the water supply is started. While the water is supplied, the water level sensor 29 at one side of the tub 10 detects the level of water, and provides the detected water level to the microcomputer 20. Then, the microcomputer 20 determines whether or not the detected water level from the water level sensor 29 approaches or is at a preset water level. When the detected water level approaches or is at the preset water level, the water supply controller 22 stops the water supply valve 23 to stop the water supply.
When the proper or predetermined amount of wash water corresponding to the weight of the laundry items 14 has been supplied to the tub 10 of the drum washing machine, the microcomputer 20 outputs a control signal to the motor driving controller 27 according to a washing operation program stored therein (e.g., in the microcomputer 20), thereby causing the motor 28 to rotate the drum 11.
When the drum 11 is rotated, the laundry items 14 are washed while being moved upward by the lifter 12 of the drum 11 and then falling (e.g., into the wash water).
After the washing operation is completed, a spin-drying operation using centrifugal force is performed by rotating the drum 11 at high speed, thereby removing at least some of the wash water in the laundry items 14.
The wash water removed from the laundry items 14 escapes to the tub 10 through a large number of holes formed in the circumference of the drum 11. Then, the drain valve 26 is opened and the drain motor 25 is operated (e.g., turned on) to discharge the wash water outside of the washing machine (e.g., through one or more pipes or tubes to an external drain).
In order to perform the spin-drying operation after the washing operation and the rinsing operation, the following process may be performed. First, a balance spin-drying process is performed to agitate the laundry items in a side-to-side direction, thereby spreading the laundry items. In one embodiment, balance spin-drying may comprise alternately rotating the drum 11 in forward and reverse directions, each forward and reverse rotation being for a relatively small number of rotations (e.g., 5 full rotations or less, 3 full rotations or less, 1 full rotation or less, ½ of 1 rotation [180°], etc.). Then, the motor is accelerated at a predetermined speed (e.g., a laundry adherence speed) so that the laundry items adhere on the inner wall of the drum, and a first unbalance value is detected. When the first unbalance value is equal to or less than a preset value, a main spin-drying process is performed.
FIGS. 3A and 3B are diagrams illustrating states of laundry items put into the drum washing machine according to embodiment(s) of the present invention. FIG. 4 is a diagram illustrating a state in which a Hall sensor is installed in the drum washing machine according to embodiment(s) of the present invention.
In the present embodiment, the laundry adherence speed refers to a speed at which the laundry items 14 adhere on the inner wall of the drum 11 and do not come off from the inner wall during a balance spin-drying process. The laundry adherence speed may be from 50 to 150 RPM (e.g., a value of from 80 to 120 RPM, such as 95 RPM). A water removal speed refers to a speed at which foam and water contained in the laundry items 14 are removed before the main spin-drying process is performed. The water removal speed may be from 100 to 300 RPM (e.g., a value of from 125 to 250 RPM, such as 180 RPM).
Referring to FIG. 3A, the laundry items 14 may be uniformly distributed in the up and down and/or left and right sides of the drum 11, when seen from the front side. In this case, the motor may be accelerated at the laundry adherence speed, and a first unbalance value is then detected during the balance spin-drying process. When the detected first unbalance value is less than a preset value, the process for accelerating the motor to the water removal speed may be performed.
When the first unbalance value is equal to or greater than the preset value, the method returns to the balance spin-drying process so as to spread the laundry items 14 more evenly.
On the other hand, referring to FIG. 3B, the laundry items 14 may be uniformly distributed in the up and down and/or left and right sides of the drum 11 as illustrated in FIG. 3A, but may be concentrated in the front and/or rear sides of the drum 11. In this case, the first unbalance value may be detected as a value less than preset value, because the laundry items 14 are uniformly distributed in the up and down and/or left and right sides of the drum 11. Then, the main spin-drying process may be performed.
However, when the RPM of the motor 28 is increased to perform the main spin-drying process, vibration occurs in the forward and backward direction as indicated by the double-headed arrow, due to the laundry items 14 being concentrated in the front and rear sides of the drum 11, with a damper 31 and a spring 32 set to an axis as illustrated in FIG. 3B. As a result of such vibration(s), the tub 10 may collide with a gasket 34 or cabinet front 33 and cause noise, and the washing machine may move or become damaged.
Thus, in order to solve such a problem, the first unbalance value is detected at the laundry adherence speed. Then, when the first unbalance value is less than the preset value, the motor is accelerated to the water removal speed.
Then, a second unbalance value is detected at the water removal speed, and compared to the first unbalance value. When the first unbalance value is equal to or smaller than the second unbalance value, the main spin-drying process is performed. Alternatively, when the second unbalance value is equal to or smaller than a second preset value, the main spin-drying process is performed. Thus, it is possible to prevent the vibration caused when the laundry items are concentrated in the front and rear sides of the drum 11.
Furthermore, the second unbalance value at the water removal speed may comprise a variation between forward and backward motions of the tub 10. When the variation is smaller than a preset variation, the main spin-drying process is performed. Thus, it is possible to prevent the vibration caused when the laundry is concentrated in the front and rear sides of the drum 11.
The variation between forward and backward motions of the tub 10 may be measured using a distance from the tub 10 by the distance measurement sensor 30 on a rear surface of a front panel 35.
That is, when the tub 10 moves in the direction(s) indicated by the double-headed arrow, the distance between the tub 10 and the rear surface of the front panel 35 repetitively decreases and increases, and the distance measurement sensor 30 measures or detects the repetitive variation in the distance from the tub 10. In this way, the variation between forward and backward motions of the tub 10 may be detected to determine an unbalance for the forward and backward directions.
Referring to FIG. 4, the variation between forward and backward motions of the tub 10 may be detected by measuring a distance between a Hall sensor 40 on the rear surface of the front panel and a magnet 42 attached to the tub 10.
That is, when the distance between the Hall sensor 40 and the magnet 42 repetitively decreases and increases due to the forward and backward motions of the tub 10, a change of magnetic force may be sensed to detect the variation between forward and backward motions of the tub 10. Thus, the variation between forward and backward motions of the tub 10 may be detected to determine the unbalance for the forward and backward directions.
In the present disclosure, variation(s) between forward and backward motions of the tub 10 can be detected using the distance measurement sensor 30 and/or the Hall sensor 40. However, the present invention is not limited thereto, and the variation(s) between forward and backward motions of the tub 10 may be measured or detected using various methods.
FIG. 5 is a flowchart for explaining a method for controlling dehydration or water removal in a drum washing machine according to one or more embodiments of the present invention. FIG. 6 is a graph illustrating a spin-drying process of the drum washing machine according to embodiment(s) of the present invention.
Referring to FIG. 5, the spin-drying control method for the drum washing machine according to embodiment(s) of the present invention is performed as follows. First, in order to perform a spin-drying operation after washing and rinsing operations are finished, a balance spin-drying process is performed. The balance spin-drying process may comprise an agitating operation in which laundry items 14 are agitated in the side-to-side direction to spread the laundry items 14 at step S10.
After the laundry items 14 are spread by performing the agitating operation (or a preset number of agitating operations), the motor 28 is accelerated at the laundry adherence speed at step S20.
As described above, the laundry adherence speed refers to a speed at which the laundry items 14 adhere to the inner wall of the drum 11 without coming off from the inner wall of the drum 11. In one example, the laundry adherence speed may be set to 95 RPM, although it may be any value at which the laundry adheres to the inner wall of the drum (e.g., from 50 to 150 RPM).
When the motor 28 or drum 11 is accelerated to reach the laundry adherence speed (e.g., section A of FIG. 6), a first unbalance value is detected at steps S30 and S40.
Using the first unbalance value, an unbalance caused by laundry items 14 concentrated in the up and down or left and right sides of the drum 11 may be detected.
Then, the detected first unbalance value is compared to a preset value. When the first unbalance value is less than the preset value, it may be determined that the balance is maintained. Then, the method proceeds to steps S50 and S60 to accelerate the motor 28 to the water removal speed.
However, when the first unbalance value is equal to or greater than the preset value, the procedure returns to step S10 to perform or repeat the balance spin-drying process.
That is, the agitating operation is performed again to uniformly spread the laundry items 14.
As described above, the water removal speed refers to a speed at which foam and water contained in the laundry items 14 are removed before the main spin-drying process is performed. In one embodiment, the water removal speed may be set to 180 RPM, although it is generally greater than the laundry adherence speed, and it may be any value at which free water is removed from the laundry (e.g., from 125 to 250 RPM).
When the motor 28 or drum 11 is accelerated to reach the water removal speed, that is, a section B of FIG. 6, a second unbalance value is detected at steps S70 and S80.
When the drum 28 reaches the water removal speed, vibrations may occur in the forward and backward directions in the case where the laundry items 14 are concentrated in the front and/or rear sides of the drum 11. However, when damping of the damper 30 is not performed in a vertical direction (e.g., vibrations in the forward and backward directions do not necessarily cause damping by the damper 30), the second unbalance value may be detected as a smaller value than the first unbalance value, even though some vibration occurs.
However, when the laundry items 14 are not concentrated in the front and rear sides of the drum 11, the second unbalance value is detected as a larger value than the first unbalance value, as the damping of the damper 30 in the vertical direction increases due to the relatively high-speed rotation.
Thus, the first and second unbalance values may be compared to each other, in order to determine whether or not the vibration occurs in the forward and backward directions.
That is, when the first unbalance value is equal to or smaller than the second unbalance value, it may be determined that the laundry items 14 are not concentrated in the front and rear sides of the drum 11, but are relatively uniformly distributed, and the main spin-drying process is then performed at steps S90 and S100.
However, when the first unbalance value is larger than the second unbalance value, it is determined that vibrations are occurring in the forward and backward directions due to concentration of the laundry items 14 in the front and rear sides of the drum 11. Then, the method returns to step S10 to perform the balance spin-drying process.
That is, the agitating operation is performed again to uniformly spread the laundry items 14.
Alternatively, when the second unbalance value is equal to or smaller than a second preset value, the main spin-drying process may be performed. Thus, when the second unbalance value is equal to or greater than the preset value, the procedure may return to step S10 to perform the balance spin-drying process, although the second preset value may be the same as or different from the preset value for the first unbalance determination.
FIG. 7 is a flowchart for explaining a method for controlling dehydration or water removal in a drum washing machine according to another embodiment of the present invention.
In the spin-drying control method for the drum washing machine according to the present embodiment, a variation between forward and backward motions of the tub is detected as the second unbalance value detected at the water removal speed. When the variation between forward and backward motions is less than a preset variation, a main spin-drying process is performed, and when the variation between forward and backward motions is equal to or greater than the preset variation, the procedure returns to perform a balance spin-drying process.
The spin-drying control method for the drum washing machine according to one or more embodiments is performed as follows. First, after washing and rinsing operations are finished, the balance spin-drying process is performed. First, an agitating operation for agitating the laundry items 14 in the side-to-side direction to spread the laundry items 14 is conducted at step S110.
After the laundry items 14 are spread by performing the agitating operation (or a preset number of agitating operations), the motor 28 is accelerated to the laundry adherence speed at step S120.
As described above, the laundry adherence speed refers to a speed at which the laundry items 14 adhere to the inner wall of the drum 11 and do not come off the inner wall of the drum 11, and may be set to 50-150 RPM (e.g., 95 RPM).
When the motor 28 reaches the laundry adherence speed, that is, the section A of FIG. 6, a first unbalance value is detected at steps S130 and S140.
Using the first unbalance value, an unbalance caused by the laundry items 14 concentrated in the up and down and/or left and right sides of the drum 11 may be detected.
The detected first unbalance value is compared to the preset value. When the first unbalance value is less than the preset value, it is determined that the balance is maintained, and the motor 28 is accelerated to the water removal speed, at steps S150 and S160.
However, when the first unbalance value is equal to or greater than the preset value, the procedure returns to step S10 to perform the balance spin-drying process.
That is, the agitating operation is performed again to uniformly spread the laundry items 14.
As described above, the water removal speed refers to a speed at which foam and water in the laundry items 14 are removed before the main spin-drying process is performed. The water removal speed may be set to 125-250 RPM (e.g., 180 RPM).
When the motor 28 reaches the water removal speed, that is, the section B of FIG. 6, a variation between forward and backward motions of the tub 10 is detected as a second unbalance value, at steps S170 and S180.
As described above, the variation between forward and backward motions of the tub 10 may be measured through a distance from the tub 10 by the distance measurement sensor 30 on the rear surface of the front panel 35.
Furthermore, the variation between forward and backward motions of the tub 10 may be measured through a distance from the magnet 42 attached to the tub 10 by the Hall sensor 40 on the rear surface of the front panel 35.
When the drum 28 reaches the water removal speed, vibrations may occur in the forward and backward directions when the laundry items 14 are concentrated in the front and/or rear sides of the drum 11. In this case, as the distance between the front panel 35 and the tub 10 repetitively decreases and increases, the variation between forward and backward motions of the tub 10 is detected as a value equal to or greater than a preset variation.
Thus, when the variation between forward and backward motions of the tub 10 is smaller than the preset variation, it is determined that the laundry items 14 are not concentrated in the front and rear sides of the drum 11, but are uniformly distributed, and the main spin-drying process is performed at steps S190 and 200.
However, when the variation between forward and backward motions of the tub 10 is equal to or larger than the preset variation, it is determined that vibrations occur due to the laundry items 14 concentrated in the front and/or rear sides of the drum 11. The procedure then returns to step S110 to perform the balance spin-drying process again.
That is, the agitating operation is performed again to uniformly spread the laundry items 14.
Although some embodiments have been provided to illustrate the invention in conjunction with the drawings, it will be apparent to those skilled in the art that the embodiments are given by way of illustration only, and that various modifications and equivalent embodiments can be made without departing from the spirit and scope of the invention. The scope of the invention should be limited only by the accompanying claims.

Claims

1. A method for controlling dehydration or water removal in a drum washing machine, comprising:

agitating and balance spin-drying laundry in a drum of the washing machine, then accelerating a motor of the washing machine to a laundry adherence speed;

detecting a first unbalance value when the motor reaches the laundry adherence speed;

accelerating the motor to a water removal speed according to the first unbalance value;

detecting a second unbalance value when the motor reaches the water removal speed to obtain a comparison result; and

comparing the first unbalance value and the second unbalance value, and performing main spin-drying according to a comparison result.

2. The method of claim 1, wherein:

when the first unbalance value is less than a preset value, the motor is accelerated to the water removal speed, and

when the first unbalance value is equal to or greater than the preset value, the method continues or repeats balance spin-drying.

3. The method of claim 1, wherein, after detecting the second unbalance value,

when the first unbalance value is equal to or less than the second unbalance value, main spin-drying is performed, and

when the first unbalance value is greater than the second unbalance value, the method repeats balance spin-drying.

4. The method of claim 1, wherein detecting the second unbalance value comprises detecting a variation between forward and backward motions of a tub of the washing machine.

5. The method of claim 4, wherein, after detecting the variation between the forward and backward motions of the tub,

when the variation between the forward and backward motions of the tub is less than a preset variation, main spin-drying is performed, and

when the variation between the forward and backward motions of the tub is equal to or greater than the preset variation, the method repeats balance spin-drying.

6. The method of claim 4, wherein the variation between the forward and backward motions of the tub is measured using a distance from the tub by a distance measurement sensor on a rear surface of a front panel of the washing machine.

7. The method of claim 4, wherein the variation between the forward and backward motions of the tub is measured using a distance from a magnet attached to the tub by a Hall sensor on a rear surface of a front panel.

8. A method for controlling dehydration or water removal in a drum washing machine, comprising:

balance spin-drying laundry in a drum of the washing machine, then accelerating a motor of the washing machine to a laundry adherence speed;

accelerating the motor to a water removal speed when the first unbalance value is less than or equal to a preset value, and repeating balance spin-drying when the first unbalance value is greater than the preset value;

detecting a second unbalance value when the motor reaches the water removal speed; and

performing main spin-drying when the second unbalance value is less than or equal to a preset variation, and repeating balance spin-drying when the second unbalance value is greater than the preset variation.

9. The method of claim 8, wherein detecting the second unbalance value comprises measuring a variation in a distance of a tub of the washing machine from a distance measurement sensor on a rear surface of a front panel of the washing machine.

10. The method of claim 8, wherein detecting the second unbalance value comprises measuring a variation in a distance of a magnet attached to a tub of the washing machine from a Hall sensor on a rear surface of a front panel of the washing machine.

11. The method of claim 8, wherein the laundry adherence speed is 50-150 RPM.

12. The method of claim 8, wherein the water removal speed is greater than the laundry adherence speed.

13. The method of claim 8, wherein the water removal speed is 125-250 RPM.

14. A control circuit for a drum washing machine, comprising:

a load cell sensor configured to sense a weight of laundry in a drum of the drum washing machine,

a water level sensor configured to sense a level of wash water in the tub,

a microcomputer, microcontroller or other logic circuit configured to receive values from the load cell sensor and the water level sensor, and control operations of the drum washing machine,

a motor driving controller configured to control a motor that rotates the drum, and

a distance measurement sensor configured to detect forward and backward motions of the tub.

15. The control circuit of claim 14, further comprising a water supply controller configured to control the operation of a water supply valve according to a water supply control signal from the microcomputer, microcontroller or other logic circuit.

16. The control circuit of claim 14, further comprising a drain controller configured to control the operations of a drain valve and/or a drain motor of the drum washing machine, according to a drain control signal from the microcomputer, microcontroller or other logic circuit.

17. The control circuit of claim 14, wherein the motor driving controller controls the motor according to a motor control signal from the microcomputer, microcontroller or other logic circuit.

18. A drum washing machine, comprising:

the control circuit of claim 14,

the tub,

the drum, horizontally rotatable in the tub, and having a number of holes in its circumference, and

the motor.

19. The drum washing machine of claim 18, further comprising a washing heater that heats wash water according to a control signal from the microcomputer, microcontroller or other logic circuit.

20. The drum washing machine of claim 18, further comprising a plurality of dampers and a plurality of springs configured to reduce vibrations of the tub.