AU1970401A - A method for determining an appropriate water level in a washing machine - Google Patents

Description

-1-

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicant/s: Actual Inventor/s: Address for Service: LG Electronics Inc.

Gyeong Ho Moon BALDWIN SHELSTON WATERS MARGARET STREET SYDNEY NSW 2000 Invention Title: 'A METHOD FOR DETERMINING AN APPROPRIATE WATER LEVEL IN A WASHING MACHINE' Details of Original Application No. 64781/98 dated 07 May 1998 The following statement is a full description of this invention, including the best method of performing it known to me/us:- File: 30864AUP00 la A METHOD FOR DETERMINING AN APPROPRIATE WATER LEVEL IN A WASHING MACHINE BACKGROUND OF THE INVENTION The present invention relates to a method for determining an appropriate water level in washing machine to detect the volume of laundry.

As shown in FIG. 1, a conventional washing machine comprises a motor 1 for generating rotary power and transmitting the power to the driving portion in response to a control signal from a microcomputer. A clutch 5 receives the power from pulley 2 via v-belt 3 and clutch pulley 4. A stirring vane or agitator 7 is provided to rotate and swirl water in a washing tank 6. The item shown by reference numeral 8 denotes the laundry to be washed.

As shown in FIG. 2, a laundry volume detecting circuit in a conventional 15 washing machine typically comprises a microcomputer 9 for controlling the operation of the machine, and a motor driving circuit 10 including an array of resistors R3-R6, R9- TRIACs TA1,TA2, capacitors C1-C4, and resistors R7,R8, to control the driving of the motor 1. There is also provided a laundry volume detecting means 11 including diodes D1,D2, photo-coupler PC, transistors Q1,Q2 and resistors R16-R19 which 20 transmit data to the micro computer after detecting the washing volume from the residual *e voltage, or back electromotive force, generated by the inertia of the motor and vane e* when electric power to the motor is switched off. Rotation of the stirring vane immediately after power is switched off is converted into a direct current rectangular wave pulse. The laundry volume detecting means then inputs the rectangular wave pulse into the microcomputer.

FIGs. 3(A) and 3(B) are water level display diagrams of the washing machine.

The water level is typically divided into 5 levels or 7 levels (for example, lowest, lower, low, medium low, medium, high medium, and high, as per FIG. The operation of a conventional washing machine will now be described in detail with reference to FIGS. 1 to 6.

Firstly, a user may select a key so as to wash a load of laundry after detecting the volume of the laundry. The microcomputer 9 initially supplies water from a water supply to the washer tank 6 to the predetermined water level by opening the cold and/or hot water valves (not shown) through the motor driving circuit When the water supply operation is completed, the microcomputer 9 outputs a high signal through ports P54, P55 alternatively during certain period of time so as to :detect the volume of the laundry in the tank 6. In particular, the high signal which the port P54 outputs is applied to a gate of TRIAC (bidirectional triode-thyristor) TA1 through the array resistors R4,R6,R 10 and a switching element Q4 as a trigger signal and makes the TRIAC TA1 turn on. The outputted high signal from the port P55 is applied to a gate ofTRIAC TA2 through array resistors R3,R5,R9 and the switching element Q3 as a trigger signal and makes TRIAC TA2 turn on. Therefore, the inputted alternating currents are applied to the motor I through turned on TRIACs TA1,TA2 and the motor 1 starts to rotate the stirring vane 7 in clockwise or counterclockwise direction.

When the motor 1 is started, a voltage is generated in the motor over a certain period of time and is applied to the laundry volume detecting means 11. The laundry -3volume detecting means 11 then converts the voltage generated from the motor I into a rectangular wave pulse and inputs the rectangular wave pulse into the microcomputer 9.

The microcomputer 9 also outputs the signals through the ports P55,P54 during a certain period of time and then TRIACs TA1,TA2 become turned off, thereby cutting off the alternating currents which were applied to die motor.

However, although the alternating currents are cut off, the motor 1 does not stop immediately. It takes time for the motor to come to a complete stop due to momentum of the mechanical components of the system, such as the agitator 7.

If the volume of the laundry is large, the motor 1 is stopped within a relatively short period of time due to the relatively high friction between the agitator 7 and the laundry. On the other hand, if the volume of the laundry is small, the motor 1 comes to a stop relatively slowly due to the correspondingly lower friction between the agitator 7 •and the laundry. A back electromotive force is generated in the motor 1 during the period of time (T2 period) taken for the motor to stop after the current has been cut off as 15 shown in FIG. 6(A).

The laundry volume detecting means 11 detects the back electromotive force of the motor 1 after the current supply has been cut off, and converts the back electromotive force into a rectangular wave pulse. It then inputs this rectangular wave pulse to the microcomputer 9. In particular, the back electromotive force is half-wave rectified by 20 resistors R1,R2 and diode D1, and the rectangular wave pulse as shown in FIG. 6(B) is then outputted by a light emitting element and a light receiving element. The wave pulse is transmitted through transistor Q I and is then inverted by the transistor Q2, and the rectangular wave pulse as shown in FIG. 6(C) is then inputted to the microcomputer 9.

The microcomputer 9 counts the number of inputted wave pulses received from the laundry volume detecting means 11, and thereby determines the appropriate water level, wherein the water level is selected from a high level (level a high medium level (level a medium level (level a medium low level (level a low level (level a lower level (level and a lowest level (level For example, if the number of wave pulses (T2 period) is in the minimum range, the water level is determined to be level 7 and a longer washing period is initiated. On the other hand, if the number of wave pulses (T2 period) is in the maximum range, the water level is determined to be level 1 and a shorter washing time is initiated.

FIG. 4 shows a flow chart of the water level determining process according to whether the user selects the water level. If the determination of the water level and the washing time are set as described above, then the next step in the washing process is performed. The microcomputer 9 controls the rotation of the stirring vane 7 according to the determined water level, as shown in FIG. 5 For example, if the water level is high, the real operating rate of the stirring vane (operating rate of stirring ON position) is large, and if the water level is low, the real operating rate is small.

The real operating rate in case of level 7 stirring ON stirring ON stirring

OFF

(tALl tAL2 tA (tAR tAR2 AP- U RNx 100 (tALl t tALN (tAR tAR2+...+tARN) t 100 Where, tAL driving pulse time period in anticlockwise direction, tAR driving pulse time period in clockwise direction, tAP OFF pulse time period.

As shown in FIG. 5, the real driving rate is proportioned according to the water level.

After the abovementioned process is completed, the following process is performed. If the washing process is only one time, DRAINAGE, Intermittent

SPIN-

DRY, SPIN DRYING, PAUSE, WATER SUPPLY, RINSE is performed in that order.

If the washing process is more than two times, the process is repeated.

Then, a water removal process is performed: that is, the steps of DRAINAGE, Intermittent SPIN-DRY, SPIN DRYING, PAUSE are performed in that order, at the completion of which the washing operation is completed.

However, there are problems associated with this type of conventional washing S. machine insofar as the washing efficiency is deteriorated just following the selected water level. For example, if the water level is higher than that which is optimum for the amount of the laundry to be washed, the washing process is performed successfully but the entanglement rate of the laundry is high, however if the water level is low in comparison to the amount of the laundry, the entanglement of the laundry is low but the washing process is not performed well and the damage rate of the laundry is increased.

Also, because the laundry volume detecting process is performed only one time in order to determine the water level, the efficiency of the washing process is diminished 20 when the laundry volume is detected erroneously. o0**o* SUMMARY OF THE INVENTION It is an object of the present invention to overcome or substantially ameliorate one or more of the disadvantages of the prior art or at least provide a useful alternative thereto.

Accordingly, in a first aspect the invention provides an apparatus for detecting the laundry volume of a loaded washing machine comprising: laundry volume detecting means for detecting the laundry volume before and after the supplying of water; and control means for determining an appropriate water level based on the detected laundry volume.

At least in a preferred form, the present invention comprises a laundry volume detecting means which converts a change of magnetic flux of a magnet formed in a motor shaft into an electric signal at a time of turning OFF of said motor and detects the laundry volume both in wet and dry state, and a microcomputer which determines the 15 water level according to the detected laundry volume.

A method for detecting the laundry volume of a loaded washing machine o*o* comprising the steps of: A) executing a first water level determining process, which includes the substeps of: detecting said laundry volume before the supplying of water and determining the first water level; B) executing a second water level determining process, which includes the substeps of: -7detecting said laundry volume again after supplying the water to a low level when said first water level is higher than a medium low level, and determining the second water level; C) executing a first actual water level determining process which includes, the sub-steps of: comparing said first water level with said second water level, determining the actual water level according to the difference of said two levels, supplying the water and proceeding the washing operation; D) executing a third water level determining process, which includes the substeps of: supplying the water up to a lower level when said first water level is not higher S:i •than a low level; detecting said laundry volume, and determining a third water level; S E) executing a second actual water level determining process, which includes the sub-steps of: comparing said first water level with said third water level and determining said first water level as the actual water level when said first water level is higher than said third water level or a water level difference between the two levels is not larger than one °level which is a lowest level supplying the water, and proceeding the washing operation; and S 20 F) repeating the process from step B) when said water level difference is not smaller than two level after cancelling the determination of third water level.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a general structure of a conventional washing machine; -8- FIG. 2 is a laundry volume detecting circuit diagram of a conventional washing machine; FIG. 3(A) is a water level display diagram of a washing machine with 7 water levels; FIG. 3(B) is a water level display diagram of a washing machine with 5 water levels; FIG. 4 is a flow chart of a water level determining process according to a conventional washing machine; FIGS. 5(A) to 5(G) are waveform diagrams of the driving of the stirring vane according to a conventional washing machine; FIG. 6(A) is a waveform diagram of back electromotive force of the motor of FIG. 2; FIG. 6(B) is a waveform diagram of the output from the photo-coupler in the laundry volume detecting portion of FIG. 2; 0 15 FIG. 6(C) is a waveform diagram of the input to the microcomputer of FIG. 2; FIG. 7 is a block diagram of the laundry volume detecting means of a washing 00 amachine according to the present invention; FIG. 8 is a partially sectional view of the laundry volume detecting means according to the present invention; 2 FIG. 9 is a detailed circuit diagram of a waveform shaping circuit utilised in the present invention; FIG. 10 is a circuit diagram of the constant-voltage switching circuit utilised in the present invention; -9- FIG. 11 is a detailed structure of the magnet of FIG. 7; FIG. 12 is a waveform diagram of the driving of the motor of FIG. 7; FIG. 13 is a water level display and a detergent display diagram of the washing machine according to the present invention; and FIG. 14 is a flow chart of the laundry volume detecting process of the washing machine according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION Preferred embodiments of the present invention will now be described by way of example only, with reference to Figures 7 to 14 described above.

FIG. 7 is a block diagram of the laundry volume detecting means of a washing machine according to the present invention. The laundry volume detecting means comprises a magnet 31 connected to a shaft 2 lof a motor 20, a Hall-effect sensor 32 for detecting a change of magnetic flux of said magnet 31, a waveform transforming circuit eee'.

e 34 which is connected to the Hall-effect sensor 32 through a connecting circuit 33 and which transforms an output signal from the Hall-effect sensor and inputs the transformed signal to the microcomputer (not shown).

FIG. 8 is a partially sectioned view of the laundry volume detecting means according to the present invention. The magnet 31 is connected to the shaft 21 of the ;motor 31, the Hall-effect sensor 32 is installed at an opposing side of the magnet 31 at a S 20 predetermined distance. A casing 35 surrounds the Hall-effect sensor 32.

FIG. 9 is a detailed circuit diagram of the waveform transforming circuit utilised in the present invention. The waveform transforming circuit 34, which comprises capacitors C1,C2, resistors R I 0O-R13, diode D1, and switching element Q6, transforms the outputted signal from the Hall-effect sensor 32 into a rectangular wave pulse, and is connected to the microcomputer 40 which counts the output pulse from the laundry volume detecting means, detects the volume of the laundry, and controls the total operation of the washing machine by using this volume data.

FIG. 10 is a circuit diagram of the Hall-effect sensor. The Hall-effect sensor comprises a variable resistor 32a the internal resistance of which is varied according to the change of magnetic flux of the magnet 31, a comparator 32b for comparing a reference voltage Vref with the output voltage of the hall sensor 32a and outputting the signal of compared value, a constant-voltage element 32c for converting the driving voltage Vcc into the constant voltage and outputting the constant voltage, a switching element 32d for switching ON or OFF the constant voltage from said constant-voltage element 32c according to the output of the comparator 32b and outputting the constant *voltage. Reference numeral 32e denotes a current source.

i Hereinafter, the operation and efficiency of the present invention are described in detail with reference to FIG. 7 to 14.

First, if a user selects the start key when the laundry is placed in the washing ;machine, the microcomputer 40 detects the amount of the laundry in the dry state. That is, the microcomputer 40 makes the motor 20 and the stirring vane 7 rotate in clockwise or counterclockwise direction by predetermined number of rotations as shown in FIG.

20 12. After the microcomputer makes the stirring vane 7 rotate in clockwise direction by predetermined number, it cuts off the power supply to the motor so as to detect the laundry volume. And thereafter the microcomputer makes the stirring vane 7 rotate in -Ilcounterclockwise direction by predetermined number and then cuts off the power supply to the motor Although the microcomputer cuts off the power supply, the motor 20 does not stop immediately and cbntinues to rotate for certain period of time due to the force of the inertia. Hence, if the volume of the laundry is large, rotation of the stirring vane is influenced by the high friction force between the laundry and the stirring vane. If the volume of the laundry is small, then the rotation of the stirring vane is easier.

As mentioned above, when the motor 20 is turned off the laundry volume detecting means 30 detects the residual rotation of the stirring vane, and thereby detects i 0 the volume of the laundry.

When the microcomputer cuts off the power supply after the stirring vane rotates in clockwise direction, the motor 20 is not stopped immediately and continues to rotate for certain period of time. During this time the magnet 31 attached to the center of the motor shaft is also rotating.

The magnet 3 1, as shown in FIG. 11, comprises three pairs of magnetic poles so S0 that the Hall-effect sensor 32 converts a change of magnetic pole into an electric signal.

Referring to FIG. 10, the output voltage of the variable resistor 32a is varied S according to the change of magnetic flux, and the comparator 32b compares the reference voltage Vref with the output voltage of the variable resistor 32a and outputs S 20 the result. At this time, it is assumed that if N pole of the magnet 31 is indicating forward the Hall-effect sensor, the output voltage of the variable resistor 32a is higher than the reference voltage Vref, but if S pole of the magnet 31 is indicating forward the Hall-effect sensor, the reference voltage Vref is higher than the output voltage of the 12 -variable resistor 32a. Therefore. if N pole of the magnet 31 is indicating forward the Hall-effect sensor, the comparator 32b outputs the high signal and if S pole of the magnet 31 is indicating forward the Hall-effect sensor, the comparator 32b outputs the low signal. The switching element 32d repeats an ON, OFF state according to the output of the comparator 32b and outputs the switched constant-voltage. The constant-voltage, which is outputted by the switching element 32d, is inputted to the waveform transforming circuit 34 and is converted into rectangular wave pulse by the waveform transforming circuit 34 and the rectangular wave pulse is inputted to the port P60 of the microcomputer 40 as the pulse signal. The microcomputer 40 then counts the pulse signal and detects the laundry volume. Thus, the microcomputer can detect the laundry volume by counting the number of pulses. By rotating the stirring vane in counterclockwise direction, the abovementioned operation can be repeated.

Preferably, the microcomputer 40 makes the motor 20 rotate two times in a clockwise direction, then cuts off the power supply as shown in FIG. 12 (TI period) and counts the residual rotation pulse. After the count is completed, the microcomputer makes the motor 20 rotate two times in counterclockwise direction, then again cuts off the power supply as shown in FIG. 12 (T2 period) and counts the residual rotation pulse.

oAfter that, the microcomputer 40 detects the laundry volume (S2) by the number of the pulse being counted in the OFF period (TI+T2), determines a first water level W1, 20 and displays the volume of the detergent (S3) to be used.

At this stage the determined water level is not displayed and the volume of the detergents is only displayed in the water level display means and detergent display means while the determined water level data is stored in an internal memory.

13- The microcomputer 40 then determines a second water level W2 according to the first water level WI.

[f the first water level is not less than level 4 (which is the medium low level), water is supplied up to level 3 which is the low level (S5-S6), the laundry volume is detected by the abovementioned method and the second water level W2 is determined (S7-S9).

Then, the microcomputer 40 compares the first water level with the second water level and calculates the water level difference. If the water level difference is not more than one level (for example, WI level 6which is the medium high, W2 level 5 which is the medium), the first water level W1 is determined as the actual water level (S 11), the actual water level is displayed via the water level display means and detergent display means as shown in FIG. 13 (S 12). Then, the water is supplied corresponding to the determined actual water level (S 13). and the washing process is continued (S If the water level difference is not more than one level, it means that the laundry volume detecting error rate is trivial. Generally, the laundry volume detection before the supplying of water is more accurate than the laundry volume detection after the supplying of water. But, when the laundry volume is detected before the supplying of So water, in case that wet laundry is contained in the washer tank, the detection rate is lowered and the water level will be determined higher than actual volume of the laundry.

S• 23 Also, when the laundry volume is detected after the supplying of water, the laundry volume detection error may be decreased, but since the water supplying time is required, the laundry volume detecting time period is longer.

14- On the other hand, since the laundry volume detecting error due to the wet laundry is occurred in case that the water level difference Wl-W2 is not less than two levels, the detected second water level after supplying water to the low level is determined as the actual water level W2 (S 16). The actual water level W2 is displayed through the water level display means and detergent display means as shown in FIG. 13 (S 12). Then, water is supplied to corresponding actual water level W2, and the washing process is performed (S 13-S15).

On the other hand, in the abovementioned step S4, if the first water level detected in step S4 is not more than level 3 which is the low level, water is supplied up to level 2 which is the lower level (S 17-S 18), the laundry volume is detected according to the same method as described above, and the third water level W3 is determined (S19-S21).

Then, the microcomputer 40 compares the first water level W1 with the third water level W3 (S22), and if the first water level W1 is higher than the third water level W3, the first water level W1 is determined as the actual water level W1 (S23). The actual water level is displayed through the water level display means and the detergent display means of FIG. 13 (S 12). Then, water is supplied corresponding to the determined first water level (S 13), the washing process is performed (S When the first water level WI is not higher than the third water level W3, the water level difference W3-W1 is calculated. And if the water level difference is not 20 more than one level, the first water level WI is determined as the actual water level W1 (S23-S24), and the actual water level is displayed through a water level display means and detergent display means as shown in FIG. 13 (S 12). Then, water is supplied up to the first water level (S 13), and the washing process is performed (S Also, if said water level difference is not less than two level, the third water level W3 is cancelled (S25) and the washing process is jumed to the abovementioned steps (S5-S16).

When the volume of the laundry is detected after the supplying of water, the laundry volume detecting rate becomes to be low in case that the water supply is a small quantity (the lower level) and the volume of the laundry is large. Accordingly, if the water level difference W3-WI is large, water is supplied until level 3 and the laundry volume is detected. If the laundry volume is not more than level 3 which is the low level, it is preferred that water is supplied until level 2 which is the lower level and the laundry volume is detected. And if the laundry volume is not less than level 4 which is the medium low level, it is preferred that water is supplied until level 3 and the laundry volume is detected.

According to the present invention as described above, since the amount of the laundry is detected before and after the supplying of water, the accuracy of the laundry volume detection can be increased and the entanglement of the laundry can be effectively decreased. Also, even when the user sets up the water level erroneously, the selection error is automatically corrected so that the efficiency of washing machine can be improved.

Whilst specific embodiments of the invention have been illustrated and described 20) herein, it is appreciated that modifications and changes may be apparent to those skilled in the art. It is therefore to be understood that the appended claims are intended to cover all modifications and changes as fall within the true spirit and scope of the invention.

Claims (6)

1. A method for determining an appropriate water level in a washing machine for a washing operation comprising the steps of: A) a first water level determining process including detecting a laundry volume before supplying of water and determining a first water level; B) a second water level determining process including detecting said laundry volume again after supplying of water to a low level when said first water level is higher than a medium low level, and determining a second water level; C) a first actual water level determining process including comparing said first water level with said second water level, determining said first water level as the actual water level when the water level difference is not more than a level 1 which is predetermined in a microcomputer, determining said second water level as the actual water level when the water level difference is higher than said water level difference; D) a third water level determining process including supplying water up to lower 15 level when said first water level is not higher than low level, detecting said laundry ooo. volume, and determining a third water level; second actual water level determining process including comparing said first water level with said third water level and determining said first water level as the actual water level when said first water level is higher than said third water level or a water 000 i level difference between said two levels is not larger than said level 1; and F) returning to the step B) when said water level difference is not smaller than said two levels after cancelling the determination of said third water level. -17-

2. A method according to claim 1, wherein said step B) comprises the processes of: supplying water to said low level when said first water level is not smaller than said medium low level; rotating a motor to absorb enough water into said laundry in clockwise or counterclockwise direction by the predetermined rotating number and detecting said laundry volume; and determining said second water level according to said detected laundry volume.

3. A method according to claim 1, whereinsaid step C) comprises the processes of: calculating said water level difference after comparing said first water level with said second water level; and displaying said actual water level, supplying water according to said actual 00.0 water level and returning to washing process.

4. A method according to claim 1, wherein said step D) comprises the processes of: 0 15 supplying water up to low level 2 when said first water level is not higher than low level 3; rotating a motor to absorb enough water into said laundry in clockwise or counterclockwise direction by the predetermined rotating number and detecting said i laundry volume; and 0*00.0 determining said third water level according to said detected laundry volume.

An apparatus for detecting laundry volume of washing machine substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings. -18-

6. A method of detecting laundry volume of washing machine substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings. DATED this 12th Day of February, 2001 LG ELECTRONICS INC. Attorney: RUSSELL J. DAVIES Fellow Institute of Patent Attorneys of Australia of BALDWIN SHELSTON WATERS t.. *o 4a 4