Method for sensing water level and vibration of washing machine and apparatus therefor

A method and apparatus for sensing the water level and vibration for a washing machine are disclosed. The method includes the steps of measuring a resonant frequency, when a water level of a washtub corresponds to the water level of zero and there is no wash within the washtub, in a water level sensor which converts the variation of water pressure according to the water level of the washtub into the resonant frequency and senses the water level as the converted resonant frequency, setting the measured resonant frequency as a reference resonant frequency, measuring the resonant frequency from the water level sensor, during a dehydration operation among washing operations, and obtaining a deviation of the measured resonant frequency from the reference resonant frequency, and comparing the deviation of the measured resonant frequency from a deviation of the reference resonant frequency to determine whether the dehydration operation is continued, for thereby achieving an optimal washing operation, wherein the method is comprised of the step of sensing the excessive vibration within the washing machine only with an output of existing water level sensor, without having a mechanical vibration sensor.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to a method for sensing a water level and
 vibration of a washtub for a washing machine based the amount of a
 laundry, and in particular, to a method and apparatus for accurately
 sensing a water level and vibration by detecting an abnormal vibration
 caused by an inclination of the laundry during a dehydration process of a
 washing control mode as a LC resonant frequency for thereby optimizing a
 washing control operation and implementing an accurate detection of a
 water level and vibration of a washing machine.
 2. Description of the Background Art
 Generally, a washing machine is designed to detect the amount of a laundry
 in a washtub. When the amount of the laundry is detected, the water level,
 the amount of a detergent, and the entire washing time are determined
 based on the thusly detected amount of the laundry.
 Based upon the total washing time required, the washing machine executes a
 washing operation in which the water within the washtub swirls based on
 the operation of a pulsator to form a frictional force against the laundry
 for thereby washing the laundry.
 After the washing operation, the washing machine discharges the polluted
 water to the outside of the washtub and then execute a rinsing operation
 in which a fresh water is supplied into the washtub to rinse the laundry
 by the preset number of times.
 After the rinsing operation, the washing machine discharges the water to
 the outside of the washtub and then executes a dehydration operation in
 which an induction motor rotates at a certain high speed for thereby
 dehydrating the laundry based on a centrifugal separation force.
 In the washing operation control of the washing machine, at an initial
 washing stage, the washing machine opens a water supply valve to receive a
 certain amount of water in accordance with the amount of the laundry
 within the washtub, until the water level reaches a set water level. At
 this time, as a water level sensing method, there is known a sensing
 method in which a LC resonant frequency is varied based on the pressure of
 water supplied within the washtub.
 By way of example, if the pressure of water supplied within the washtub is
 varied, the LC resonant frequency is varied correspondingly thereto. Then,
 after the varied LC resonant frequency has been measured, the water level
 corresponding to the amount of the laundry is determined and the water
 supply valve is closed to stop the supply of water for thereby
 implementing a proper water level.
 During the dehydration operation, since the motor is typically set to
 rotate at a high speed of about 1700 rotations per minute, a great
 centrifugal force is generated and drastically affects the laundry within
 the dehydration tub to thereby cause a strong vibration or noise.
 Meanwhile, the vibration can not be fully absorbed by means of a balancing
 device such as a snubber bar which is installed at an upper end portion of
 the washtub.
 In addition, the rotation of the dehydration tub is stopped in accordance
 with a control of the induction motor. However, since the rotating force
 caused due to inertia is varied in accordance with the amount of the
 washing water, the rotation of the dehydration tub is temporarily
 decreased. In the case that the induction motor is stopped, it is
 gradually increased. Accordingly, it fails to control the rotation of the
 dehydration tub to prevent the generation of the vibration and noises.
 To overcome the above problems, an improved washing machine capable of
 sensing the water level and vibration within the washtub during the
 washing operation is disclosed.
 The above improved washing machine has a water level sensor and a vibration
 sensor. For instance, during the washing and rinsing operations, the water
 level sensor serves to supply and sense the optimal water level within the
 washtub, and during the dehydration operation, the vibration sensor
 functions to sense the vibration generated in the washing machine.
 FIGS. 1 to 6 illustrate a conventional washing machine in which a water
 level sensor and a vibration sensor are installed independently.
 As shown therein, the washing machine including a water level sensor and a
 vibration sensor includes a tank 100 installed within a casing 102 and
 having an opened top portion and a closed bottom portion, a snubber bar
 107 lying between dampers 108 which are respectively assembled at the
 upper portion of the casing 102 and the lower portion of the tank 100 for
 absorbing the impact of the tank 100, a washing and dehydration tub
 (hereinafter, called as a washtub) 101 installed in the interior of the
 tank 100 and mounted in a coaxial state with the tank 100 to execute the
 washing and dehydration operations, the washtub forming a plurality of
 conically shaped holes on the surface thereof, an induction motor 103
 installed at a lower portion of the outer surface of the tank 100 for
 implementing a reverse rotation, a clutch 104 assembled with the induction
 motor 103 by means of a pulley belt 105 for delivering and decelerating
 the rotating force of the induction motor 103, a pulsator 106 rotatably
 installed on the inner bottom surface of the washtub 101 and interposed
 between the washtub 101 and the clutch 104 for swirling the water within
 the washtub 101, a water supply valve 109 connected with a water supply
 path installed at the upper portion of the tank 100 for supplying the
 water into the washtub 101, a water discharging valve 110 installed on the
 bottom surface of the tank 100 for discharging the polluted water to the
 outside of the washtub 101, a vibration sensor 112 installed on the inner
 surface of one side of the upper portion of the casing 102 for sensing the
 vibration formed by the contact with the tank 100 due to an eccentric
 rotation of the washtub 101 in accordance with an eccentrically formed
 laundry in a certain direction, a water pressure transfer path 113 having
 one end connected to the lower surface of the tank 100 and the other end
 vertically extended to the upper portion of the tank 100 for transferring
 the water pressure generated in accordance with the variation of the water
 level within the washtub 101, a water level sensor 111 installed at the
 other end of the water pressure transfer path 113 for changing and
 outputting an inherent inductance in accordance with the transferred water
 pressure, a waveform shaping unit 116 for applying a fixed capacitance to
 the changed value of the inherent inductance to thereby generate a
 resonant frequency and for then stabilizing the generated resonant
 frequency with a voltage waveform to thereby amplify and output the
 resonant frequency, and a microprocessor 114 for determining the vibration
 and the water level with the vibration sensed by the vibration sensor 112
 and the voltage waveform inputted through the waveform shaping unit 116
 and for controlling the operation of the induction motor 103 using a motor
 driving member 115 and the opening and closing operation of the water
 supply and discharging valves 109 and 110 and a valve driving member 117
 in accordance with the determined vibration and the water level. FIGS. 2
 and 3 illustrate the detailed configuration of the water level sensor 111
 as shown in FIG. 1.
 The water level sensor 111 is comprised of a cylindrical housing 10 which
 has a through hole connected through the water pressure transfer path 113
 to the tank 100 at one side thereof and an opening hole at the other side
 thereof, a bellows 11 which is installed within the housing 10 and is
 connected to the water pressure transfer path 113 to be extended or
 expanded in accordance with the pressure of water within the washtub 101,
 a shielding member 12 which is sealed at the top portion of the bellows 11
 and have a hook shape to shield the water pressure, a cylindrical coil 14
 having an inherent inductance value, which is installed at the center
 portion of the inner wall of the housing 10 to be separated by a
 predetermined distance in a vertical direction from the shielding member
 12, a cylindrical core 13 which is hooked at the upper portion of the
 shielding member 12 and moves vertically in the internal space of the coil
 14 in accordance with the extension and expansion of the bellows 11 to
 thereby vary the inherent inductance value of the coil 14, a cylindrical
 support member 16 which is assembled at the top end portion of the coil 14
 and serves to support the coil 14 against the housing 10, a cap 17 which
 is adapted to cover the opening at the top end portion of the support
 member 16, and a coil shape spring 15 which is interposed between the top
 surface of the core 13 and the bottom surface of the cap 17 to restore the
 core 13 to the original position thereof.
 The waveform shaping unit 116, as shown in FIG. 6, is comprised of an
 amplifier 116a which amplifies an input voltage to a substantial voltage
 size to provide the amplified voltage to the microprocessor 114, and
 condensers C1 and C2 which are respectively connected in serial with the
 input and output terminals of the amplifier 116a via resistors R1 and R2
 and feed back the output voltage from the amplifier 116a to the input
 voltage thereof. In this case, the waveform shaping unit 116 is operated
 based on a LC resonant circuit configuration in such a manner that both
 terminals a and b of the coil 14 are respectively connected in parallel
 with the condensers C1 and C2, and the core 13 moves vertically in the
 internal space of the coil 14.
 The vibration sensor 112 such as a safety switch or a limit switch, as
 shown in FIG. 5, is comprised of first and second voltage discontinuous
 members 22 and 23 which are respectively installed at the upper portion of
 the casing 102 and is electrically short-circuited or opened, a switch leg
 20 which is hinged to the first voltage discontinuous member 22 to be
 separated at a predetermined distance from the tank 100 and rotates by the
 striking of the tank 100 according to the rotation radius of the washtub
 101 to electrically short-circuit the first and second voltage
 discontinuous members 22 and 23, and a spring 21 which restores the switch
 leg 20 to the original position thereof to electrically open the first and
 second voltage discontinuous members 22 and 23. An explanation of the
 operation of the conventional washing machine in which the water level
 sensor and the vibration sensor are installed, respectively will be
 discussed in detail with reference to FIGS. 1 to 6.
 Firstly, if an operation is started after the washing operation has been
 set through an operational panel (not shown), the microprocessor 114
 controls the water supply valve 109, the water discharging valve 110 and
 the induction motor 103 through the valve driving member 117 and the motor
 driving member 115 to thereby execute the washing, rinsing and dehydration
 operations in a scheduled sequence.
 At this time, the microprocessor 114 receives an input signal, which is
 generated in accordance with the operation states of the water level
 sensor 111 sensing the water level of the washtub 101 and the vibration
 sensor 112 sensing the vibration of the washtub 101, and then outputs a
 control signal in response to the input signal.
 In this case, the microprocessor 114 meets the following conditions. It
 recognizes the state where the core 13 of the water level sensor 111, as
 will be described in detail, is not advanced into the internal space of
 the coil 14, as the state where the water is not retained within the
 washtub 101, i.e. the water level of zero, and contrarily, recognizes the
 state where the core 13 of the water level sensor 111 moves vertically the
 internal space of the coil 14, as the state where the water is retained
 within the washtub 101 based upon the movement of the core 13.
 Under the above conditions, the microprocessor 114 controls, for the
 purpose of supplying the water within the washtub 101 upon an initial
 washing operation, the valve driving member 117 to open the water feeding
 valve 109 such as an electronic control valve in accordance with the
 amount of the laundry retained within the washtub 101.
 If the water is fed into the washtub 101, the water pressure becomes high.
 Then, the water pressure is applied, through the water pressure transfer
 path 113 connected to the tank 100, to the bellows 11 within the housing
 10 of the water level sensor 111. At this time, the shielding member 12,
 which is sealed at the upper portion of the bellows 11, prevents the water
 pressure from being continuously increased. This results in the generation
 of pressure expansion. Thereby, the pressure expansion renders the bellows
 11 expanded in proportion to the water pressure.
 Referring to FIG. 4, if the bellows 11 is expanded, the cylindrical core
 13, which is assembled with the shielding member 12, moves in the internal
 space of the coil 14 upwardly in the vertical direction, in step ST10. The
 coil 14 has a diameter larger than that of the core 13 and includes the
 inherent inductance value. The inherent inductance value is varied in
 accordance with the upward movement of the core 13, in step ST20. For
 example, the inherent inductance value is increased as the core 13 moves
 in the internal space of the coil 14 in the upward direction.
 The inductance variation value of the coil 14 is multiplied by a
 capacitance value of the condensers C1 and C2 of the waveform shaping unit
 116 of FIG. 6 to be produced as a predetermined resonant frequency. The
 resonant frequency is shaped into a voltage waveform by the waveform
 shaping unit 116 and is then supplied to the microprocessor 114.
 In other words, the both terminals a and b of the coil 14 of the water
 level sensor 111 are respectively connected in parallel with the
 condensers C1 and C2 of the waveform shaping unit 116. As a result, the
 waveform shaping unit 116 is operated based on a single LC resonant
 circuit configuration by the arrangement of the coil 14 and the condensers
 C1 and C2, thus to generate the resonant frequency, at step ST30.
 Conventionally, the resonant frequency f.sub.0 of the LC resonant circuit
 is calculated under the following equation:
 ##EQU1##
 The resonant frequency f.sub.0 is amplified by the amplifier 116a to a
 substantial voltage size, and the amplified voltage waveform is provided
 to the microprocessor 114.
 The microprocessor 114 measures the water level within the washtub 101 on
 the basis of the resonant frequency f.sub.0 of the waveform shaping unit
 116 generated based on the inductance variation value of the water level
 sensor 111. Then, it determines as to whether the measured water level is
 optimal to correspond with the amount of the laundry detected. If
 determined as optimal, it controls the valve driving member 117 to close
 the water supply valve 107.
 Thereafter, it controls the motor driving member 115 to alternatively
 electrify the induction motor 103, which renders the pulsator 106 to be
 forwardly and reversely rotated in turn.
 As a result, the water within the washtub 101 is swirled, which causes the
 frictional force against the laundry to be generated, thus to execute the
 washing operation.
 If the washing operation is completed, the microprocessor 114 controls the
 valve driving member 117 to open the water discharging valve 110 and
 discharges the polluted water to the outside of the washtub 101. At the
 time, the water level sensor 111 senses whether the polluted water within
 the washtub 101 is completely discharged.
 In other words, during the discharging operation, the water pressure is
 decreased as the water level within the washtub 101 is low. Accordingly,
 if the water pressure is increasingly decreased, the bellows 11 is
 expanded, based upon the elastic force of the spring 15, which is
 interposed between the cap 17 and the core 13 of the water level sensor
 111. Moreover, the core 13 gradually descends vertically in the internal
 space of the coil 14, thereby returning to the initial position thereof.
 If the core 13 is returned to the initial position thereof, the inductance
 value of the coil 14 is also decreased. Hence, the resonant frequency
 f.sub.0, which is obtained by multiplying the inductance variation value
 of the coil 14 by the capacitance value of the condensers C1 and C2, is
 changed to the initial value thereof and then inputted to the
 microprocessor 114. As a result, the microprocessor 114 determines the
 completion time of the discharging operation.
 After the completion of the washing operation, the rinsing operation is
 implemented through the water feeding and discharging to/from the washtub
 101, as mentioned above.
 For the dehydration operation after the washing and rinsing operations are
 performed, the microprocessor 114 controls the induction motor 103 to be
 rotated at a set rotation speed and senses the vibration generated within
 the washtub 101 due to the rotation of the induction motor 103 by means of
 the vibration sensor 112 as shown in FIG. 5.
 During the dehydration operation, an appropriate balance or an undesirable
 vibration within the tank 100 is generated in accordance with the
 collection of the laundry in a certain direction.
 If the laundry is uniformly disposed at the internal wall of the washtub
 101, the vibration within the washtub 101 caused due to the rotation speed
 of the induction motor 103 is not generated after a little amount of
 vibration has been generated. As a result, the washtub 101 finally reaches
 a normal dehydration speed, while having the same rotation radius
 centering around the concentric axis. This creates a balancing state where
 no vibration within the tank 100 is generated, thus to execute the normal
 dehydration operation during the set time period.
 On the other hand, if the laundry is inclined at a certain corner of the
 wall of the washtub 101, the washtub 101 eccentrically rotates in every
 direction as the rotation speed is high, and if the eccentric rotation is
 severe, the tank 100 undesirably strikes against the washtub 101.
 The vibration width is increased in accordance with the strength of the
 striking at the tank 100, and as shown in FIG. 5, the switch leg 20 of the
 vibration sensor 112 such as the safety switch or the limit switch is
 struck at every rotation. Thereby, the switch leg 20 electrically
 short-circuits or opens the first and second voltage discontinuous members
 22 and 23, while rotating counterclockwise or clockwise by means of the
 spring 21.
 If the microprocessor 114 inputs an electrical signal from any one of the
 first and second voltage discontinuous members 22 and 23, it controls the
 water supply valve 109 to supply the water within the washtub 101 and thus
 executes an untwisting operation for the laundry during a predetermined
 time period. Thereby, the laundry can be uniformly disposed on the wall
 surface of the washtub 101 to thereby reduce the strength of the vibration
 formed.
 If the vibration is decreased, the microprocessor 114 controls the motor
 driving member 115 to rotate the induction motor 103 at a high speed,
 thereby completing the dehydration operation.
 Meanwhile, if the microprocessor 114 continuously inputs the electrical
 signal from the corresponding voltage discontinuous member, after the
 untwisting operation for the wash, it halts the induction motor 103 to
 thereby prevent the generation of the over-vibration.
 It can be appreciated that the water level and vibration sensing device in
 the conventional washing machine is capable of sensing, during the washing
 operation for the wash, the water level of the washtub using the LC
 resonant circuit in which an inductance variation value of the coil within
 the water level sensor is calculated and sensing, during the dehydration
 operation for the wash, the vibration within the washtub using the
 separate vibration senor such as a limit switch.
 As known, however, since the conventional washing machine should include
 independent water level sensor and vibration sensor, there are some
 problems in that the production cost is high and a manufacturing process
 is complicate.
 In addition, since the vibration sensor uses mechanical contact points and
 a spring, there is a problem in that malfunctions may be generated due to
 the aged deterioration or corrosion of the contact points. Furthermore, it
 is impossible for the conventional vibration sensor to accurately sense
 the vibration within the washtub because of the necessity of the
 adjustment of the intervals of the contact points and the decrement of the
 restoring force of the spring.
 By way of example, if the vibration sensor is installed adjacent to the
 tank, it senses a slight vibration of the tank, which causes the washing
 machine to execute an unnecessary operation. However, if installed at some
 distance, it does not sense the vibration until the vibration becomes
 severe. Therefore, so as to dispose the initial position of the vibration
 sensor in an accurate manner, an additional production cost should be
 required and a productivity efficiency may be degraded.
 Accordingly, there is a need to provide an improved water level and
 vibration sensing device which can solve the above problems experienced in
 the conventional washing machine and cam be manufactured with relative low
 production cost and high reliability.
 SUMMARY OF THE INVENTION
 Accordingly, the present invention is directed to a method and apparatus
 for sensing the water level and vibration in a washing machine that
 substantially obviates one or more of the problems due to limitations and
 disadvantages of the related arts.
 An object of the invention is to provide a method and apparatus for sensing
 the water level and vibration in a washing machine which installs a
 unitary sensor to accurately sense both the water level and the vibration,
 thereby achieving an optimal washing operation, wherein the method is
 comprised of the step of sensing the excessive vibration within the
 washing machine only with an output of existing water level sensor,
 without having a mechanical vibration sensor.
 Another object of the invention is to provide a method and apparatus for
 sensing the water level and vibration in a washing machine in which an
 active control in washing and dehydration operations is made by monitoring
 and suppressing the vibration state and the water level of the washtub
 therein, wherein the apparatus is comprised of a unitary sensor which is
 miniaturized and simply configured to accurately sense both the water
 level and the vibration of the washtub.
 Still another object of the invention is to provide a method and apparatus
 for sensing the water level and vibration in a washing machine which can
 measure the vibration of a washtub, not in one-way direction, but in
 three-dimensions, to suppress a vibration error rate and can install
 control members for measuring the vibration in three-dimensions, while
 maintaining existing water level sensor function.
 According to an aspect of the present invention, there is provided a method
 for sensing the water level and vibration in a washing machine which
 comprises the steps of measuring a resonant frequency, when a water level
 of a washtub corresponds to the water level of zero and there is no wash
 within the washtub, in a water level sensor which converts the variation
 of water pressure according to the water level of the washtub into the
 resonant frequency and senses the water level as the converted resonant
 frequency, setting the measured resonant frequency as a reference resonant
 frequency, measuring the resonant frequency from the water level sensor,
 during a dehydration operation among washing operations, and obtaining a
 deviation of the measured resonant frequency from the reference resonant
 frequency, and comparing the deviation of the measured resonant frequency
 from a deviation of the reference resonant frequency to determine whether
 the dehydration operation is continued.
 According to another aspect of the present invention, there is provided a
 method for sensing the water level and vibration in a washing machine
 comprises the steps of moving the internal space of a coil by the
 variation of water pressure according to the water level of a washtub,
 during a washing operation, to vary an inherent inductance of the coil,
 moving the internal space of the coil by the vibration in a horizontal
 direction according to an eccentric rotation of the washtub, during a
 dehydration operation, to vary the inherent inductance of the coil, adding
 a predetermined capacitance value to the inherent inductance variation
 value, to thereby vary a resonant frequency, and determining the water
 level and the vibration within the washtub, on the basis of the variation
 amount of the resonant frequency.
 Preferably, the amount of variation of the inherent inductance of the coil
 is defined as .DELTA.L1, during the washing operation and as .DELTA.L2,
 during the dehydration operation, under the conditions .DELTA.L1
 &gt;.DELTA.L2.
 According to still another aspect of the present invention, there is
 provided a method for sensing the water level and vibration in a washing
 machine comprises the steps of moving the internal space of a coil by the
 variation of water pressure according to the water level of a washtub, the
 coil having at least two or more inherent inductance values, to thereby
 vary any one inherent inductance value of the coil, freely moving a
 sliding member centering around a support member in which variation area
 and non-variation area are divided, according to an eccentric rotation of
 the washtub, to thereby vary at least one or more inherent inductance of
 the coil including the inherent inductance value for movement in a
 vertical direction, adding a predetermined capacitance value to the varied
 inherent inductance variation value, to thereby vary an inherent resonant
 frequency, and determining the water level and the vibration within the
 washtub, on the basis of the variation amount of the resonant frequency.
 Preferably, the non-variation area is occupied by the portion to which the
 center of the support member is adjacent, and the variation area is
 occupied by the portion from which the center of the support member is
 far. In this case, as the sliding member moves toward the variation area,
 the inherent inductance value of the coil gradually increases.
 Assuming that the left and right directions relative to a concentric axis
 of the washtub is designated as `X`, the before and behind directions as
 `Y`, and the top and bottom directions as `Z`, preferably, the coil has
 the inherent inductance value in the directions X, Y and Z, respectively.
 It is desirable that any one of the directions X, Y and Z of the coil is
 designated as a water level sensing direction and the other as a vibration
 sensing direction.
 Assuming that the vibration in the directions X, Y and Z is denoted as Vx,
 Vy and Vz, and the inherent inductance values in each direction are as Lx,
 Ly and Lz, the vibration in each direction is given by the following
 expressions: Vx=f1 (Lx, Lz), Vy=f2 (Ly, Lz), and Vz=f3 (Vz), where
 coefficients f1, f2 and f3 are optional functions.
 According to yet another aspect of the present invention, there is provided
 an apparatus for sensing the water level and vibration in a washing
 machine which comprises a sealing state maintaining member installed
 within a housing connected via a water pressure transfer path to a tank
 and moving vertically due to the variation of water pressure according to
 a water level of a washtub, a substantially cylindrical coil unit
 installed in the center portion of the internal wall of the housing and
 having an inherent inductance value, a magnetic media assembled on the
 upper surface of the sealing state maintaining member and moving
 vertically the internal space of the coil unit according to the variation
 of the water pressure to thereby vary the inherent inductance value of the
 coil unit, an inclined support member by a predetermined angle disposed to
 be separated by a predetermined distance from the top end portion of the
 magnetic media on the internal space of the coil unit and moving
 vertically according to the variation of the water pressure, along with
 the magnetic media, a sliding member made of a predetermined material,
 having a predetermined diameter, and moving vertically along the inclined
 surface of the support member according to an eccentric rotation of the
 washtub, to thereby vary the inherent inductance value of the coil unit,
 and a waveform shaping unit for adding a predetermined capacitance value
 to the varied inherent inductance variation value of the coil unit to
 thereby generate a resonant frequency and stabilizing the resonant
 frequency in a voltage waveform to selectively measure the amounts of
 water level and eccentricity in each direction.
 According to yet still aspect of the present invention, there is provided
 an apparatus for sensing the water level and vibration in a washing
 machine which comprises a sealing state maintaining member installed
 within a housing connected via a water pressure transfer path to a tank
 and expanding and moving vertically due to the variation of water pressure
 according to a water level of a washtub, a coil unit installed at the
 center portion of the internal wall of the housing and having at least two
 or one inherent inductance values, a magnetic media hook-assembled on the
 upper surface of the sealing state maintaining member and moving
 vertically the internal space of the coil unit according to the variation
 of the water pressure to thereby vary any one of the inherent inductance
 values of the coil unit, a support member disposed to be separated by a
 predetermined distance from the top end portion of the magnetic media on
 the internal space of the coil unit and moving vertically according to the
 variation of the water pressure, along with the magnetic media, the
 support member having the upper surface on which a variation area and a
 non-variation area are divided on the basis of the center portion thereof,
 a sliding member made of a predetermined material, having a predetermined
 diameter, and moving freely to the variation area and the non-variation
 area of the support member according to an eccentric rotation of the
 washtub, to thereby vary any one of the inherent inductance values of the
 coil unit, and a waveform shaping unit for adding a predetermined
 capacitance value to the varied inherent inductance variation value of the
 coil unit to thereby generate a resonant frequency and stabilizing the
 resonant frequency in a voltage waveform to selectively measure the
 amounts of water level and eccentricity in each direction.
 Assuming that the left and right directions relative to a concentric axis
 of the washtub is designated as `X`, the before and behind directions as
 `Y`, and the top and bottom directions as `Z`, preferably, the coil unit
 takes a substantially square hexahedral shape and is comprised of a coil
 which winds horizontally in the directions X, Y and Z, respectively, on
 the square hexahedron in a predetermined winding ratio.
 Preferably, any one of the coils in the directions X, Y and Z varies the
 inductance value by the water level and vibration, and the other coils
 vary the inductance values according to the amount of eccentricity of the
 washtub, together with the one coil.
 The upper surface of the support member is formed to have the portions in
 the left and right directions inclined to have the same angle as each
 other, on the center portion thereof, to thereby sense the eccentricity in
 the direction of X in the washtub, where the inclined angle is 20 degrees.
 Preferably, the upper surface of the support member is rounded to have a
 smooth inclined surface in a radial direction, on the center portion
 thereof, to thereby form a spherical inner rounded surface, on which the
 sliding member moves freely in the radial direction.
 Assuming that the vibration in the directions X, Y and Z is denoted as Vx,
 Vy and Vz, and the inherent inductance values in each direction are as Lx,
 Ly and Lz, the vibration in each direction is given by the following
 expressions: Vx=f1 (Lx, Lz), Vy=f2 (Ly, Lz), and Vz=f3 (Vz), where
 coefficients f1, f2 and f3 are optional functions.
 It can be from the above description understood that the unitary sensor
 according to the present invention can sense, during the washing and
 dehydration operations, both the water level of the washtub and an amount
 of vibration according to the eccentric rotation of the washtub.
 As a result, a method and apparatus for sensing the water level and
 vibration in a washing machine according to the preferred embodiments of
 the present invention has the following advantages: a) a precise measuring
 result for the water level and vibration within the washtub can be
 extracted; b) an error probability of the vibration sensing value and a
 time period required for the dehydration can be all reduced; and c)
 installation of a mechanical vibration sensor is not needed.
 Additional advantages, objects and features of the invention will become
 more apparent from the description which follows.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
 Reference will now be made in detail to the preferred embodiments of the
 present invention, examples of which are illustrated in the accompanying
 drawings.
 The present invention includes, of course, a plurality of embodiments, but
 hereinafter, an explanation on some preferred embodiments of the present
 invention will be in detail discussed.
 In the drawings, like numbers indicate the same or similar elements and an
 explanation of them will be excluded in this detailed description for the
 sake of brevity.
 FIG. 7 illustrates a sectional view taken in a vertical direction of a
 unitary water level and vibration sensor in a washing machine according to
 a first embodiment of the present invention, and FIG. 8 illustrates an
 enlarged sectional view of a first support member of FIG. 7, in which a
 first sliding member moves in every direction according to the left impact
 of the washing machine and thus senses the vibration therein.
 In the first embodiment of the present invention, a water level and
 vibration sensor 200 includes a cylindrical housing 10 perpendicularly
 installed at an outer wall of a casing and engaged via a tank 100 and a
 water pressure transfer path 113, a bellows 11 installed in the housing
 10, connected with the water level transfer path 113, and retracted and
 elongated in accordance with a variation of the water pressure based on
 the water level in the washtub 101, a shielding member 12 shielded at an
 upper portion of the bellows 11 and having a hook shape for shielding the
 transfer of the water pressure, a circular coil 14 having a certain
 inductance and installed at an inner wall of the housing 10, a cylindrical
 core 13 hooked to the upper surface of the shielding member 12 and
 vertically moving in the interior of the coil 14 in accordance with a
 retracting is and elongating operation of the bellows 11 for varying a
 certain inductance of the coil 14, a cylindrical support member 16 engaged
 to an upper portion of the coil 14 for supporting the coil to the housing
 10, a cap 17 for capping an open portion of the support member 16, a coil
 shape spring 15 vertically engaged at an upper surface of the core 13 and
 a lower surface of the cap 17 for returning the position of the core 13 to
 its original position, a first support member 201 installed in the
 interior of the coil 14 at a certain distance from the upper portion of
 the core 13, vertically moving together with the core 13 based on the
 retracting and elongating operation of the bellows 11 and having its upper
 surface having an inclination 201a, and a first sliding member 202 having
 a diameter of about 3 mm through 5 mm, horizontally and vertically moving
 along the inclination surface 201a of the first support member 201 by an
 eccentric rotation of the washtub 101 and varying the inductance of the
 coil 14. Both terminals a and b of the coil 14 are parallely connected
 between the condensers C1 and C2 as shown in FIG. 6, so that a waveform
 shaping unit 116 operates as a LC resonant circuit when the core 13 and
 the first sliding member 202 vertically move in the interior of the coil
 14 and along the inclination surface 201a of the first support member 201.
 The water level and vibration sensing apparatus according to the first
 embodiment of the present invention operates as follows with respect to
 the detection of the vibration level due to the water level and an
 inclination of the laundry without a sensing error during a washing and
 dehydration process in the washing control operation.
 The first embodiment of the present invention will be explained in more
 detail with reference to the accompanying drawings.
 First, when a washing process, a rinsing process, and a dehydration process
 are set using an operation panel (not shown), the microprocessor 114
 controls the water supply valve 109, the dehydration valve 110, and the
 induction motor 103 based on the valve driving unit 117 and the motor
 driving unit 115 for thereby implementing the set washing, rinsing and
 dehydration processes. At this time, at an initial stage of the washing
 process, the microprocessor 114 opens the water supply valve 109 using the
 valve driving unit 117 based on the amount of the laundry in the washtub
 101 and supplies water into the washtub 101.
 When water is supplied into the washtub 101, the water pressure is applied
 to a certain shielding state maintaining unit such as the bellows 11
 installed in the housing 10 via the water pressure transfer path 113
 connected with the tank 100.
 At this time, the transfer of the water pressure is blocked by the
 shielding member 12 which shields the upper portion of the bellows 11. In
 this state, the bellows 11 is elongated in proportion to the water
 pressure.
 When the bellows 11 is elongated, namely, the bellows 11 is upwardly moved,
 the magnetic medium such as a cylindrical core 13 hooked to the shielding
 member 12 and the first support member 201 are vertically moved in the
 interior of the coil 14. At this time, the first sliding member 202 which
 is formed of a magnetic material is not vertically moved in the leftward
 and rightward directions along the inclination surface 201a of the first
 support member 201 but vertically moved in a state that the same is
 positioned at the rightward portion of the first support member 201 as
 shown in FIG. 8. Here, the inductance variation of the coil 14 based on
 the vertical movement of the first support member 201 is neglected.
 Namely, the inductance of the coil 14 is varied based on the vertical
 moving distance of the core 13. As the core 13 is moved in the upward
 direction in the interior of the coil 14, the inductance value of the coil
 14 is increased.
 The inductance variation value of the coil 14 is multiplied by the
 capacitances C of the condensers C1 and C2 of the waveform shaping unit
 116 as shown in FIG. 6 and is generated as a certain resonant frequency.
 The thusly varied resonant frequency is amplified to a certain level by an
 amplification device 116a of the waveform shaping unit 116 and is provided
 to the microprocessor 114.
 Since both terminals a and b of the coil 14 are parallely connected between
 the condensers C1 and C2 of the waveform shaping unit 116, the waveform
 shaping unit 116 operates as a LC resonant circuit by the coil 14 and the
 condensers C1 and C2 for thereby generating a resonant frequency.
 The microprocessor 114 compares the variation value of the resonant
 frequency inputted from the LC resonant circuit with a water level
 variation for thereby judging the water level of the washing tub 101. If
 the judged water level is the optimum water level corresponding to the
 sensed amount of the laundry, the water supply valve 109 is closed by the
 valve driving unit 117, and the washing process is performed.
 When the washing process is completed, the dehydration valve 110 is opened
 by the valve driving unit 117 for thereby discharging a polluted water
 from the washtub 101.
 In the water draining mode, as the water level is decreased in the washtub
 101, the water pressure is decreased. When the water pressure is gradually
 decreased, the bellows 11 is retracted by an elastic force of the coil
 shape spring 15 engaged between the magnetic medium such as the cap 17 and
 the core 13, and the core 13 and the first support member 201 are
 vertically and downwardly moved in the interior of the coil 14.
 When the core 13 and the first support member 201 are returned to their
 original positions, the inductance of the coil 14 is decreased. The
 resonant frequency based on the decreased inductance and the capacitances
 of the condensers C1 and C2 are changed to the initial values and are
 inputted into the microprocessor 114 for thereby judging the completion
 time of the water draining process.
 When the washing process is completed, the rinsing process is performed
 after the water supply and draining processes are performed based on the
 water level sensing method.
 After the washing and rinsing processes are performed, the microprocessor
 114 operates the inductance motor 103 at a high speed for thereby
 performing a dehydration process.
 In the dehydration process, since the water level of the washtub 101 is a
 zero level, the water pressure applied to the water level sensor becomes
 the resonant frequency at the time when the water level is zero.
 In addition, in the dehydration process, when the laundry is uniformly
 arranged in the washtub 101, the washtub 101 is uniformly rotated with
 respect to the co-axis, so that an optimized operation is implemented
 without vibration of the tank 100.
 When the tank 100 is in the balanced state without vibration, as shown in
 FIG. 8, the first sliding member 202 such as a ball formed of a magnetic
 material is not moved in the leftward and rightward directions along the
 inclination surface 201a of the first support member 201. Namely, the same
 is positioned at the rightward portion of the inclination surface 201a.
 When the first sliding member 202 which is formed of a magnetic material is
 positioned at the rightward portion of the first support member 201, the
 inductance of the coil 14 is not varied. Therefore, the same resonant
 frequency is generated from the LC resonant circuit and is provided to the
 microprocessor.
 The microprocessor 114 recognizes the balanced state of the tank 100 using
 a voltage wave form with respect to the continuously inputted same
 resonant frequency and accelerates the inductance motor 103 using the
 motor driving unit 115 during a certain dehydration time for thereby
 dehydrating the laundry in the washtub 101.
 If the laundry is inclined at a certain wall of the washtub 101, the
 washtub 101 is eccentrically rotated, and the tank 100 is unbalanced based
 on the eccentric rotation, so that the tank 100 is vibrated in the every
 direction.
 When the tank 100 is vibrated, as the first sliding member 202 formed of a
 magnetic material having a diameter of 3 mm through 5 mm is moved, the
 upper surface of the first support member 201 is moved in the leftward and
 rightward directions along the inclination surface 201a at an angle range
 of 0.degree. through 40.degree., namely, in the .+-.X directions and the
 vertical .+-.Z direction.
 For example, as shown in FIG. 8, if a certain force (vibration) is applied
 in the leftward direction, the first sliding member 202 is moved in the -X
 direction along the inclination surface 201a of the first support member
 201 by a reaction operation and is moved in the +Z direction. Namely, the
 first sliding member 202 is moved in the vertical direction (+Z) direction
 in accordance with the inclination angle of the first support member 201.
 Here, the diameter of the first sliding member 202 is about 4 mm, and the
 inclination angle of the first support member 201 is 20.degree.. The
 height D from the lower surface of the first support member 201 to an
 initial position of the inclination angle is about 0 mm.
 Continuously, when the first sliding member 202 is moved in the horizontal
 and vertical directions along the inclination surface 201a of the first
 support member 201 in accordance with the vibration of the tank 100, the
 inductance of the coil 14 is changed.
 When the tank 100 is greatly vibrated, the first sliding member 202 is
 greatly moved in the vertical direction along the inclination surface
 201a, and then is fallen by the gravity. Therefore, the inductance of the
 coil 14 is greatly changed. As a result, the resonant frequency of the LC
 resonant circuit is changed and is inputted into the microprocessor 114.
 Therefore, the microprocessor 114 detects the vibration of the tank caused
 by the eccentric rotation of the washtub 101 using the water level and
 vibration sensor 200, and the rinsing and dehydration processes are
 performed in the above-described manner.
 In the washing process, assuming that the inductance variation of the coil
 14 due to the water level variation of the washtub 101 is .DELTA.1, and
 the inductance variation of the coil 14 due to the vibration of the
 washtub 101 is .DELTA.L2, the variation level of the inductance is
 .DELTA.L1 &gt;.DELTA.L2.
 In the washing process, since the vertical direction movement distance that
 the core 13 is moved in the coil 14 by the pressure of the water supplied
 based on the amount of the laundry in the washtub 101 is great, the
 inductance of the coil 14 is greatly changed. In the dehydration process,
 the vibration is most greatly generated. The first sliding member 202 is
 moved as long as the length of the inclination surface 201a of the first
 support member 201. The variation of the inductance of the coil 14 is
 smaller than the movement of the core 13.
 FIGS. 9, 10 and 13 illustrate the second embodiment of the present
 invention.
 The water level and vibration sensor 300 according to the second embodiment
 of the present invention includes a cylindrical housing 10 vertically
 installed at an outer wall of the upper portion of the casing 102 and
 connected via the tank 100 and the water pressure transfer path 113, a
 bellows 11 installed in the housing and connected with the water pressure
 transfer 113 and implementing a retraction and elongation movement by the
 water pressure based on the water level in the washtub 101, a shielding
 member 12 having a hook shape and shielding the transfer of the water
 pressure at the upper portion of the bellows, a coil unit 303 for
 installed at an inner center portion of the housing 10 and having more
 than at least three inductances, a cylindrical core 13 which is hooked at
 the upper portion of the shielding member 12 and is vertically moved in
 the inner space of the coil unit 303 in accordance with a retracting and
 elongating operation of the bellows 11 and varies an inductance of the
 coil unit 303, a cylindrical support member 16 engaged to the upper
 portion of the coil unit 303 and supporting the coil unit, a cap 17 for
 covering the upper open portion of the support member, a spring 15
 vertically engaged on the upper surface of the core 13 and the lower
 surface of the cap 17 and being formed in a spring shape for returning the
 core 13 to its original position, a second support member 301 installed in
 the inner space of the coil unit 303 spaced apart from the upper portion
 of the core 13 and vertically moving together with the core 13 based on
 the retracting and elongating operation of the bellows 11 and having its
 inclination surfaces 301a and 301b, a second sliding member 302 having a
 diameter of amount 3 mm through 5 mm and vertically moving along the
 inclination surfaces 301a and 301b at the center portion of the upper
 surface of the second support member 301 by the eccentric rotation of the
 washtub 101 and varying an inductance of the coil unit 303 and being
 formed of a magnetic material, and a waveform shaping unit 304 for
 providing a fixed capacitance to the inductance of the coil unit 303 based
 on the vertical movement of the core 13 and the movement of the second
 sliding member 302, generating a resonant frequency, and stabilizing and
 outputting the resonant frequency to a voltage waveform.
 FIG. 14 illustrates the construction of the coil unit 303 according to the
 second embodiment of the present invention.
 The coil unit 303 is formed in a cubic shape and includes coils 303a
 through 303c which are wound in the X, Y and Z directions.
 Namely, The coils 303a and 303b are wound in the X and Y direction, and the
 coil 303c is wound in the Z direction into or onto the coils 303a and
 303b.
 The Z-direction coil 303c is directed to detecting the vertical movement of
 the core 13 based on the water level, and the X and Y direction coils 303a
 and 303b are directed to detecting the current position of the second
 sliding member 302 based on the two-dimensional manner.
 As shown in FIG. 15, the waveform shaping unit 304 according to the second
 embodiment of the present invention includes an amplification device 304a
 for amplifying an input voltage and providing the amplified voltage to the
 microprocessor 114 and condensers C1 and C2 connected in series with
 resistors R1 and R2 at the input and output terminals of the amplification
 device and feeding back the output voltage of the amplification device as
 an input voltage. The terminals (a,b), (c,d) and (e,f) of the coil unit
 303 are parallely connected with the condensers C1 and C2, so that when
 the core 13 and the second sliding member 302 are moved in the vertical
 and horizontal directions in the inner space of the coil unit 303 and
 along the upper surface of the second support member 301, the waveform
 shaping unit 304 operates as a LC resonant circuit.
 The operation of the water level and vibration detection apparatus for a
 washing machine according to the second embodiment of the present
 invention will be explained with reference to the accompanying drawings.
 When a water is supplied into the washtub 101, the water pressure of the
 thusly supplied water is applied to the bellows 11 in the housing 200 of
 the water level and vibration sensor 300 via the water pressure transfer
 path 113 connected with the tank 100.
 When the water pressure is increased, the pressure of the bellows is
 increased. When the bellows 11 is upwardly moved, the second sliding
 member 302 which is formed of a magnetic material and is positioned at the
 center position of the support member is vertically and upwardly moved in
 the inner space of the coil unit 303 onto which the coils 303a through
 303c are wound in the X, Y and Z directions.
 The inductance of the X direction coil 303c is varied at the coil unit 303
 based on the vertical movement distance of the second support member 301
 and the second sliding member 302. The inductance of the X and Y direction
 coil 303a and 303b are not varied.
 As shown in FIG. 14, since the X and Y direction coils 303a and 303b are
 installed in the vertical direction, even when the core 13, the second
 support member 301 and the second sliding member 302 are moved in the
 vertical direction, the X and Y direction coils 303a and 303b do not
 receive any effects. Therefore, the inductance of the coils 303a and 303b
 do not vary.
 However, since the Z direction coil 303c is installed in the horizontal
 direction, and the core 13, the second support member 301 and the second
 sliding member 302 are moved in the vertical direction in the inner space
 of the horizontally installed Z direction coil 303c, only the inductance
 of the Z direction coil 303c is varied.
 As the core 13, the second support member 301 and the second sliding member
 302 are upwardly moved in the inner space of the Z direction coil 303c,
 the inductance of the Z direction coil 303c is increased.
 The inductance variation value of the Z direction coil 303c is multiplied
 by the capacitance C of the condensers C1 and C2 of the waveform shaping
 unit 304 as shown in FIG. 15 and is changed to a certain resonant
 frequency. The thusly obtained resonant frequency is fully amplified to
 its limit level by the amplification device 304a of the waveform shaping
 unit 304 and is supplied to the microprocessor 114.
 Namely, both terminals a and b of the Z direction coil 303c are parallely
 connected between the condensers C1 and C2 of the waveform shaping unit
 304, the waveform shaping unit 304 operates as a LC resonant circuit by
 the Z direction coil 303c and the condensers C1 and C2 for thereby
 generating a resonant frequency. Therefore, it is possible to measure the
 water level during the washing and rinsing processes using the thusly
 changed resonant frequency in the same manner as the first embodiment.
 After the washing and rinsing processes are performed, the microprocessor
 114 operates the inductance motor 103 at a high speed for thereby
 implementing a dehydration process.
 At this time, if the laundry is uniformly provided in the walls of the
 washtub 101, the washtub 101 is uniformly rotated based on the same
 radius, so that any vibration of the tank 100 does not occur for thereby
 implementing a balanced rotation.
 If the tank 100 is not vibrated in the balanced state, as shown in FIG. 10,
 the second sliding member 302 does not move in the leftward and rightward
 directions along the inclination surfaces 301a and 301b of the second
 support member 301, namely, in the -X and +X directions, and is positioned
 in the non-vibration area.
 Since the second sliding member 302 is positioned in the non-vibration area
 of the second support member 301, and the core 13 is not vertically moved
 by the zero water level of the washtub during the dehydration process, the
 inductance of the X direction coil 303a is not varied.
 If the second sliding member 302 is continuously positioned in the
 non-vibration area of the second support member 301 based on the balanced
 position of the laundry, the same resonant frequency is continuously
 generated from the LC resonant circuit.
 The microprocessor 114 recognizes the balance state of the tank 100 based
 on the voltage wave form with respect to the same resonant frequency and
 accelerates the inductance motor 103 using the motor driving unit 115
 during a set dehydration time for thereby implementing a dehydration
 process in the washtub 101.
 However, if the laundry is non-uniformly provided at the wall of the
 washtub 101, the washtub 101 is eccentrically rotated, and the tank 100 is
 vibrated based on the degree of the eccentric rotation and is leaned in
 the direction of the eccentrically positioned laundry.
 When the tank 100 is vibrated, the second sliding member 302 having a
 diameter of 3 mm through 5 mm slides along the inclination surfaces 301a
 and 301b from the upper surface of the second support member 301 at an
 angle range of zero trough 40.degree. based on the degree of the
 vibration. Namely, the second sliding member 302 slides in the direction
 of the vibration area (.+-.X directions).
 As shown in FIG. 10, when a certain force (vibration) is applied from the
 right portion, the second sliding member 302 is moved in the rightward
 direction (.+-.X) via the inclination surface 301b from the center portion
 (non-vibration area) of the second support member 301, namely, in the
 vertical direction (.+-.Z) in the vibration area. On the contrary, if a
 certain force (vibration) is applied from the left portion, the second
 sliding member 302 is moved in the left direction (-X) via the inclination
 surface 301a from the center portion of the second support member 301,
 namely, in the vertical direction (.+-.Z) in the vibration area.
 As shown in FIG. 14, in a state that the X direction coil 303a is installed
 in the vertical direction, and the Z direction coil 303c is horizontally
 installed, the second sliding member 302 is moved in the horizontal and
 vertical directions (in the vibration area) along the inclination surfaces
 301a and 301b of the second support member 301. As a result, the
 inductance of the X direction coil 303a and the Z direction coil 303c is
 changed.
 In the second embodiment of the present invention, the diameter of the
 second sliding member 302 is about 4 mm, and the inclination angle of the
 inclination surfaces 301 and 301b is about 20.degree..
 The variation value of the inductance of the X direction coil 303a and the
 Z direction coil 303c is changed to a resonant frequency based on the
 condensers C1 and C2 as shown in FIG. 15. Therefore, it is possible to
 obtain a X direction vibration by a certain function with respect to the X
 and Z direction inductance variations by the microprocessor 114 based on
 the thusly obtained variation value.
 Assuming that the vibration in the X and Z directions are V.sub.X and
 V.sub.Z, the X direction vibration V.sub.X =f1 (L.sub.X, L.sub.Z) where f1
 is a certain function.
 If the X direction vibration occurs, the laundry soaking and dehydration
 processes are continuously performed.
 In the second embodiment of the present invention, since the second support
 member 301 is formed on the inclination surfaces 301a and 301b (vibration
 area) at a certain angle in the .+-.X directions at the upper surface
 center portion (non-vibration area), the X direction coil 303a of the coil
 unit 303 is not used. Namely, a horizontally arranged cylindrical coil 14
 as shown in FIG. 3 is additionally used for thereby computing the
 {character pullout} direction vibrations.
 As shown in FIG. 3, when adapting the coil 14, the second sliding member
 302 is moved in the vertical direction with respect to the horizontally
 installed coil based on the inclination angle of the inclination surfaces
 301a and 301b of the second support member 301.
 FIGS. 11 through 13 illustrate the third embodiment of the present
 invention.
 FIG. 11 is a vertical cross-sectional view illustrating a water level and
 vibration sensing apparatus according to a second embodiment of the
 present invention, and FIG. 12 is a perspective view illustrating the
 third support member of FIG. 11, and FIG. 13 is a cross-sectional view
 taken along the line I--I of FIG. 12.
 The third support member 401 of the water level and vibration sensor 400
 according to the third embodiment of the present invention includes a
 three dimensional spherical shape rounded surface having its upper surface
 which is radially rounded from its center portion for thereby implementing
 a radial direction free movement of the third sliding member 402 and is
 directed to detecting the vibrations in the forward and backward
 directions and the upward and downward directions.
 In this case, the Z direction coil unit 303 is capable of detecting the
 movement of the core 13 based on the water level of the washtub during the
 washing process and is capable of measuring the water level and the upward
 and downward direction vibrations of the third sliding member 402.
 In view of the .+-.Z direction movements, there are two types of the
 movements. Namely, the third sliding member 402 formed of a magnetic
 material is moved in the upward and downward directions at the third
 support member 401, and the third sliding member 402 is moved based on an
 inclination angle at the rounded surface 401a of the third support member
 401.
 Continuously, the X and Y direction coils 303a and 303b are capable of
 measuring the current position of the third sliding member 402 which is
 moved in the forward and backward directions at the rounded surface 401a
 of the third sliding surface 401 in two dimension.
 Therefore, it is possible to measure the X, Y and Z direction vibrations by
 measuring the X and Y direction vibrations in the above-described manner.
 At this time, assuming that the inductances of the X, Y and Z direction
 coils 303a through 303c measured in the X, Y and Z directions are L.sub.X,
 L.sub.Y, L.sub.Z, the expression of V.sub.X =f1 (L.sub.X, L.sub.Z),
 V.sub.Y =f2 (L.sub.Y, L.sub.Z), and V.sub.Z =f3 (V.sub.Z). Here, f1
 through f3 are certain function.
 FIG. 16 illustrates the fourth embodiment of the present invention.
 In the fourth embodiment of the present invention, the vibrations in the
 washing machine are detected using only the water level sensor 111 without
 the support members 201, 301 and 401 and the sliding members 202, 302 and
 402.
 FIG. 16 illustrates the water level and vibration detection method
 according to the fourth embodiment of the present invention based on FIGS.
 2, 3 and 6. FIG. 16A is a resonant frequence wave form measured based on
 the water level sensor at the time when the dehydration process is
 performed in the non-eccentric process, and FIG. 16B is a resonant
 frequence wave form measured based on the water level sensor at the time
 when the dehydration process is started in the eccentric process. As shown
 in FIG. 16A, in the case that there is not eccentricity in the laundry or
 in the case of the non-load dehydration process, the induction motor 103
 is driven in the zero water level state, and even when the speed of the
 induction motor 104 is increased based on the time lapse, the washtub 101
 is not eccentrically rotated. Therefore, the resonant frequency of the
 water level sensor 111 is not changed.
 However, as shown in FIG. 16B, in the case that there is a great
 eccentricity at the laundry, as the speed of the induction motor 103 is
 increased, the eccentric rotation of the washtub 101 is increased. The
 thusly increased eccentric rotation operates as an impact force which is
 applied to the outer casing 102, and the thusly applied impact force is
 detected by the water level sensor 111. The core 13 of the water level
 sensor 111 is moved in the interior of the coil 14 in the vertical
 direction based on the impact degree of the outer casing 102, so that the
 inductance of the coil 14 is changed. The thusly changed inductance is
 changed to a resonant frequency by the LC resonant circuit, so that it is
 possible to measure the vibration by measuring the thusly changed resonant
 frequency. Namely, as shown in FIG. 16B, in the case that there is a great
 eccentricity at the laundry, the variation .DELTA.Hz of the resonant
 frequency of the water level sensor 111 is increased. Therefore, it is
 possible to check the current dehydration vibration state by detecting the
 variation .DELTA.Hz of the resonant frequency.
 In more detail, the changed water pressure based on the water level of the
 washtub 101 is changed to the resonant frequency variation. In the case
 that the water level of the washtub 101 is a zero level checked by the
 water level sensor 111, and there is not water to be dehydrated, the
 resonant frequency H1 is measured and is set in the microprocessor 114 as
 a reference resonant frequency.
 Thereafter, it is confirmed whether the current washing operation is a
 dehydration process. If the current mode is the dehydration mode, the
 resonant frequency H2 is measured in the case that the water level is a
 zero level measured by the water level sensor 111, and there is water to
 be dehydrated for thereby obtaining deviations H2-H1 based on the
 reference resonant frequency H1. The thusly obtained deviation is compared
 with the reference variation .DELTA.H. If the deviation is smaller than
 the reference variation .DELTA.H, the induction motor 103 is rotated at a
 high speed for thereby implementing a normal dehydration. However, if the
 thusly obtained deviation is larger than the reference variation .DELTA.H,
 the driving operation of the induction motor 103 is stopped, and the
 dehydration process is temporarily stopped, so that the over vibration of
 the washtub 101 is prevented.
 The reference variation .DELTA.H is a value which is previously set with
 respect to the values which are obtained based on a characteristic such as
 a type, capacitance, standard, etc. of the washing machine. In the
 dehydration process of the fourth embodiment of the present invention, the
 case that the vibrations are detected was explained. In another embodiment
 of the present invention, in the case that the induction motor 103 is in
 the turned on mode, it is possible to detect an over vibration during the
 entire washing processes by measuring the frequency variation using the
 water level sensor 111.
 In the present invention, it is possible to detect the vibrations of the
 washing machine based on the water level of the washtub and the rotation
 of the washtub using the water level and vibration sensor in the washing
 and dehydration modes compared to the conventional art in which the water
 level of the washtub is detected using the water level sensor and LC
 resonant circuit in the washing process, and the vibration of the washing
 machine is detected using a mechanical vibration sensor such as a limit
 switch in the dehydration mode.
 As a result, in the present invention, it is possible to accurately measure
 the vibration of the washing machine based on the water level of the
 washtub and the eccentric rotation of the washtub, so that the error of
 the vibration detection and the time for dehydration are decreased. In
 addition, the number of the mechanical elements is decreased.
 As described above, in the present invention, the vibration of the washing
 machine due to the eccentricity of the laundary and the water level are
 more accurately measured for thereby preventing the energy increase due to
 the vibration detection error and the increased dehydration time in the
 conventional art.
 In the present invention, the water level and vibrations are accurately
 detected based on a quick operational response of the sliding member and
 coils in accordance with the eccentric degree of the laundry, so that it
 is possible to implement a better washing and dehydration process compared
 to the conventional washing machine. In addition, the reliability of the
 product is enhanced by implementing a performance stabilization of the
 product.
 In the water level and vibration detection apparatus for a washing machine
 according to the present invention, the water level of the washtub and the
 vibration of the washing machine are accurately detected by a unitary
 sensor or a water level sensor, so that the mechanical vibration detection
 limit switch is not used for thereby implementing a cost reduction and
 preventing a complicate structure.
 In addition, in the present invention, it is possible to implement a three
 dimensional vibration measurement. If the vibration width of the washing
 machine is large, it is possible to implement a simple control for
 stopping the washing and dehydration processes, and an active operation
 which is directed to detecting the vibration state during the washing and
 dehydration processes.
 Although the preferred embodiment of the present invention have been
 disclosed for illustrative purposes, those skilled in the art will
 appreciate that various modifications, additions and substitutions are
 possible, without departing from the scope and spirit of the invention as
 recited in the accompanying claims.