WO1997000349A1

WO1997000349A1 - Sensing system for a washing machine

Info

Publication number: WO1997000349A1
Application number: PCT/US1996/010407
Authority: WO
Inventors: Ertugrul Berkcan; Kenneth Brakeley Ii Welles
Original assignee: General Electric Company
Priority date: 1995-06-19
Filing date: 1996-06-14
Publication date: 1997-01-03
Also published as: JPH10504757A; AU6281296A; AU695300B2; KR970705666A; NZ311470A

Abstract

A system for sensing spin speed and load conditions, including an out-of-balance condition, in a washing machine (10) is provided. The washing machine (10) includes a tub (34) inside a cabinet (12). The tub (34) encloses a washer basket (18) and an agitator (26) that spin about a predetermined spin axis (58) during a spin cycle. The OOB condition can be characterized by excursions, during the spin cycle, of the tub (34) which encloses the washer basket (18). The system includes a magnetic source (50) positioned on the agitator (26) for producing a predetermined magnetic field. A magnetic sensor (70) is positioned to be attached to a wall of the cabinet (12) and is coupled to the magnetic source (50) for supplying an output signal that varies as the agitator (26) rotates relative to the magnetic sensor (70). The system further includes a signal processor (100) coupled to the magnetic sensor (70) for receiving the output signal supplied by the magnetic sensor (70).

Description

- SENSING SYSTEM FOR A WASHING MACHINE --

Background Of The Invention The present invention is generally related to washing machines and, more particularly, to a system based on inductive coupling for sensing spin speed and load conditions during the operation of a washing machine, including an out-of-balance (OOB) condition. In a typical washing machine (such as a top or front- loading washing machine) an OOB condition can occur during a spin cycle, for example, when the articles to be cleansed, such as clothing and the like, bunch up asymmetrically at various locations in the basket for holding such articles. For various detrimental reasons the OOB condition is not desirable if left uninterrupted.

For example, a tub which encloses the basket may violently strike the cabinet of the washing machine and thus cause damage either to the tub, the cabinet or both. Further, unacceptable stress forces can develop during the OOB condition that can affect the suspension mechanism of the washing machine as well as other components thereof such as the transmission or other suitable connecting device which links the motor of the washing machine to the spinning basket.

Regardless of whether an OOB condition actually develops during any given spin cycle, it is useful to accurately sense or measure load conditions and spin speed, during the spin cycle, of a washing machine. For example, these measurements can be used for determining transmission and /or motor performance under various load conditions. Furthermore, the load measurement can be used in a suitable algorithm for optimizing water usage as a function of the actual load condition in the washing machine. It is thus desirable to provide a system for sensing spin speed and for sensing load conditions including any OOB conditions which arise in a washing machine. It is also desirable for this sensing system to be low cost and reliable, i.e., a robust sensing system which does not require elaborate logic to sense spin speed and load conditions in the washing machine, and which does not need frequent calibration or resetting.

Summary Of The Invention

Generally speaking, the present invention fulfills the foregoing needs by providing a system for sensing spin speed and load conditions, including an out-of-balance condition, in a washing machine which typically includes a tub inside a cabinet. The tub in turn encloses a washer basket for holding articles to be cleansed and an agitator. The washing machine further includes a motor for rotating the basket and the agitator, which agitator is typically capable of being angularly accelerated about a predetermined spin axis upon initiating a predetermined dry spin cycle and a suspension system for supporting the washer basket so that the washer basket travels along a predetermined travel axis based on the load in the washer basket. An OOB condition can be characterized by excursions during a spin cycle of the tub which encloses the washer basket. The tub excursions can be in a direction generally perpendicular to the spin axis of the washer basket, for example.

An exemplary embodiment for the system comprises a magnetic source, such as a permanent magnet, positioned in the agitator for producing a predetermined magnetic field. At least one magnetic sensor is attached to a predetermined lateral wall of the cabinet. Each magnetic sensor is made of magnetic sensing elements, such as inductive coils, or solid state sensors, for example magnetoresistive or Hall-effect solid state magnetic sensors. Each magnetic sensor is positioned to be electromagnetically coupled to the magnetic source for supplying an output signal that varies in a predetermined manner as the agitator rotates relative to the magnetic source. The system further includes a signal processor coupled to the magnetic sensor for receiving the output signals supplied by the magnetic sensor. The signal processor is designed or programmed for measuring spin speed during the spin cycle and for detecting load conditions, including out-of-balance conditions, in the washer basket based on the output signals received from the magnetic sensor.

Brief Description Of The Drawings

The features of the invention believed to be novel are set forth with particularity in the appended claims. The invention itself, however, both as to organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following detailed description in conjunction with the accompanying drawings in which like numerals represent like parts throughout the drawings, and in which:

FIG. 1 is a perspective view of a typical top-loading washing machine;

FIG. 2 is a simplified schematic representation illustrating an exemplary suspension for the washing machine shown in FIG. 1;

FIG. 3 illustrates the representation of FIG. 2 during an out-of-balance (OOB) condition;

FIG. 4 is a side view schematic of a washing machine incorporating a sensing system in accordance with one embodiment, as claimed in the present invention;

FIG. 5 is a bottom view schematic of the lid of the washing machine showing an exemplary arrangement for magnetic sensors attached to the lid; FIG. 6 shows a schematic diagram for one set of sensing coils connected to supply an output signal capable of being processed for measuring spin speed and loads in the washing machine, and includes an exemplary magnet path during spin cycle;

FIG. 7 shows a schematic diagram of an exemplary signal processor including a comparator for receiving the output signal from the sensing coils of FIG. 6;

Fig 8 shows an exemplary waveform for the output signal supplied by the set of sensing coils of FIG. 6 upon initiating a dry spin cycle;

FIG. 9 shows an exemplary waveform of the output signal from the comparator of FIG. 7 upon initiating the dry spin cycle of FIG. 8;

FIG. 10 shows an exemplary waveform for the output signal supplied by the set of sensing coils of FIG. 6 upon initiating a dry spin cycle; ^* FIG. 11 shows an exemplary waveform of the output signal form the comparator of FIG. 7 upon initiating the dry spin cycle of FIG. 8;

FIG. 12 is a side view schematic of a washing machine incorporating a sensing system using magnetic sensors made up of two magnetic sensing elements in accordance with one embodiment, as claimed in the present invention;

FIG. 13 shows a schematic diagram of an exemplary signal processor for processing the output signal from the single set of coils of FIG. 16 so as to determine the presence of the OOB condition of FIG. 12;

FIG. 14 shows exemplary waveforms for the output signals supplied by the magnetic sensors during a balanced light load condition;

FIG. 15 shows exemplary waveforms during a heavy load condition relative to the load condition of FIG. 14;

FIG. 16 shows a schematic diagram for two sets of sensing coils connected to supply respective output signals capable of being processed for sensing one exemplary OOB condition and including respective illustrative magnet paths during this OOB condition and during a balanced condition;

FIG. 17 shows exemplary waveforms for the respective output signals supplied by the two sets of sensing coils of FIG. 16 during a balanced condition;

FIG. 18 shows exemplary waveforms for the respective output signals supplied by the two sets of sensing coils of FIG. 16 during an OOB condition;

FIG. 19 shows a schematic diagram of an exemplary signal processor for processing the respective output signals supplied from the two set of sensing coils of FIG. 16 so as to determine the presence of an OOB condition;

FIG. 20 shows a schematic diagram for a single set of sensing coils connected to supply an output signal capable of being processed for sensing another exemplary OOB condition and including respective illustrative magnet paths during an OOB condition and during a balanced condition;

FIG. 21 shows a schematic diagram of an exemplary signal processor for processing the output signal from the single set of coils of FIG. 20 so as to determine the presence of an OOB condition;

FIG. 22 shows respective exemplary waveforms for the coil and comparator output signals supplied by the single set of coils of FIG. 20 during a balanced condition; and FIG. 23 shows respective exemplary waveforms of the coil and comparator output signals supplied by the single set of coils of FIG. 20 during an OOB condition.

Detailed Description Of The Invention FIG. 1 illustrates a top loading washing machine 10 which has a cabinet 12 having a respective top panel 14 with an access opening 16 for loading and unloading articles to be cleansed in a washer basket 18. In a conventional washing operation, the articles to be cleansed are loaded through access opening 16 into basket 18, and after lid 22 is closed and a control knob 24 or other suitable control device is properly set, the washing machine sequences through a predetermined sequence of cycles such as wash, rinse and spin cycles. An agitator 26 is generally positioned in washer basket 18 to agitate or scrub the articles to be cleansed during the wash and rinse cycles, for example.

FIG. 2 shows a simplified schematic representation illustrating an exemplary suspension 28 used in washing machine 10 to provide mechanical isolation and support with respect to cabinet 12 of components such as washer basket 18, agitator 26 (FIG. 1), a tub 34, a motor 36 and a transmission 38. Suspension 28 typically comprises connecting rods 30 and springs 32 suitably selected in accordance with the particular mechanical characteristics of a given washing machine. During the wash and rinse cycles, tub 34 is filled with water and agitator 26 may be driven back and forth by motor

36 respectively linked to agitator 26 and washer basket 18 by transmission 38, for example.

FIG. 3 illustrates a condition herein referred to as out- of-balance (OOB) condition which can arise during a spin cycle, as washer basket 18 is rotated about its spin axis by motor 36 at a relatively high spin speed to extract moisture from articles 40. The OOB condition for purposes of illustration can be characterized in terms of excursions of tub 34 in a direction generally perpendicular to the spin axis during the spin cycle, for example. In the case of a top-loading washing machine, such spin axis may be generally situated in a substantially vertical plane whereas in a front-loading washing machine such spin axis may be generally situated in a substantially horizontal plane. As seen in FIG. 3 in the context of a top-loading washing machine, articles 40 may asymmetrically bunch up at various height locations in spinning washer basket 18 and due to the resulting load unbalance in combination with the centrifugal force generated during the spin cycle, tub 34 may initially oscillate substantially symmetrically about the spin axis. However, depending on the severity of the load unbalance, the tub may eventually oscillate uncontrollably so as to strike cabinet 12 as well as to impose undue stress force on various components of the washing machine such as transmission 38, suspension 28 and other such washing machine components. It should be appreciated that the foregoing OOB condition can develop regardless of the specific orientation of the spin axis of washer basket 18 and thus the present invention can be readily adapted for use in either top or front- loading washing machines. In accordance with one embodiment of the instant invention, FIG. 4 further shows a magnetic source 50, such as a permanent magnet, that can be positioned substantially near the tip of agitator 26 for producing a predetermined magnetic field. As shown in FIG. 4, magnetic source 50 is positioned off-axis relative to a spin axis 58 of washer basket 18. During a balanced condition, spin axis 58 generally intersects lid 22 at a point P located on an inner surface 72 of lid 22. A suitable counterweight 60 (or another magnet) can be positioned opposite magnetic source 50 for maintaining balance of agitator 26 during spin cycles. FIG. 4 further shows a magnetic sensor 70 attached to inner surface 72 of lid 22 and positioned substantially near the tip of agitator 26 so as to be magnetically coupled to magnetic source 50 for producing an output signal that varies in a predetermined manner as the agitator rotates relative to magnetic sensor 70, i.e., as magnetic source 50 passes near magnetic sensor 70. It will be appreciated by those skilled in the art that other locations for magnetic sensor 70 and magnetic source 50 can be provided depending on the specific application. For example, if only spin speed sensing is desired and assuming a suitable nonmagnetic material is employed for tub 34 and washer basket 18, then magnetic source 50 could be attached near the base of agitator 26 while magnetic sensor 70 could be attached at a corresponding base section of tub 34. In one embodiment, for the purpose of sensing or measuring article- related load, measurements are taken while washer basket 18 and agitator 26 are angularly accelerated upon initiating a predetermined dry spin cycle, i.e., a spin performed for a suitable time interval without any water having been introduced into washer basket 18. It will be appreciated, however, that the present invention need not be limited to dry-article measurements being that, if desired, the load measurements could readily include the weight of any water in washer basket 18 and /or the weight of the articles to be cleansed. FIG. 5 shows an exemplary embodiment for magnetic sensor 70. In this embodiment, magnetic sensor 70 is made up of a first set of four mutually spaced inductive coils 74 affixed to inner surface 72 of lid 22. By way of example and not of limitation, each coil 74 in this set of coils is positioned substantially equidistant at a predetermined distance from point P on the inner surface of lid 22.

As shown in FIG. 5 each coil 74 is positioned at a predetermined angle with respect to one another on the plane defined by inner surface 72. This predetermined angle can be conveniently chosen to position respective ones of coils 74 in substantially equiangular relationship relative to one another.

FIG. 5 further shows a second set of four spaced apart coils 76 affixed to inner surface 72 of lid 22 and being outwardly positioned relative to first set of coils 74. The angular positioning of second set of coils 76 relative to first set of coils 74 is not often important, however, for the sake of signal processing simplicity, each coil 76 should be preferably positioned substantially equidistant at another predetermined distance from point P so that each coil 76 in the second set is outwardly positioned relative to each coil 74 in the first set. For the purpose of graphical distinction, in FIG. 5, each coil 74 that makes up the first set of coils is shown to be smaller than each coil 76 that makes up the second set of coils, however, in actual practice each of coils 74 and 76 can be chosen substantially identical to one another. It will be appreciated by those skilled in the art that the actual number of coils in the first and second sets is not critical being that even a single coil per set could be used for sensing spin speed and load conditions of a washing machine. The actual number of coils is readily chosen based on the desired resolution and accuracy for the sensing system being that system resolution and accuracy are proportional to the number of sensing coils employed. Further, the use of second set of coils 76 is only optional since depending on the particular implementation even a single set with a single coil could be used for sensing spin speed and load conditions. Although the above description for magnetic sensor 70 was made in terms of inductive coils, it will be appreciated by those skilled in the art that magnetic sensor 70 need not be limited to inductive coils being that solid state magnetic sensors, such as^* Hall-effect sensors, magnetoresistive sensors and the like, could be conveniently employed in lieu of inductive coils.

FIG. 6 shows an exemplary connection for first set of coils 74. As shown in FIG. 6 each coil 74 is serially coupled to one another so that the first set of coils supplies a combined output signal Sl capable of being processed for measuring spin speed or load conditions in a washing machine, i.e., measuring the weight of the articles contained in washer basket 18 of washing machine 10. FIG. 6 further shows an exemplary path 78 for magnetic source 50 relative to coils 74 as the agitator rotates during the dry spin cycle, for example. FIG. 7 illustrates a signal processor 100 that processes the output signal Sl from coils 74 to determine spin speed or the load in the washer basket. As shown in FIG. 7, signal processor 100 includes a comparator 102 having two input ports, coupled through a suitable resistor 104, for receiving the output signal from the set of coils 74. Comparator 102 supplies a comparator output signal that during spin cycles provides a substantially periodic stream of pulses based on the polarity of the received output coil signal.

As best shown in FIG. 8, each cycle of the comparator output signal has a substantially identical period or cycle length with respect to each other. The comparator output signal is supplied to a microprocessor 106 (FIG. 7) having a counter module 108 which readily allows for measuring either spin speed, based on the number of pulses received per unit time, (i.e., spin speed is proportional to the pulse rate), or load, based on changes in the number of pulses received per unit of time, (i.e., based on changes in the pulse rate). For example, the pulse count can be readily averaged over a suitable period of time so as to provide an average measurement for the spin speed. The beforementioned load relationship follows since, for a substantially load-independent torque provided by motor 36 (FIG. 2) to washer basket 18, changes in the pulse rate are proportional to the moment of inertia of washer basket 18, which in turn is proportional to the load in washer basket 18. Thus, by measuring changes in the pulse rate while agitator 26 (FIG. 4) and washer basket 18 are angularly accelerated, such as upon initiating the dry spin cycle until a predetermined target spin speed is reached, signal processor 100 can readily determine the load in washer basket 18. For example, the measured changes in pulse rate, i.e., the measured angular acceleration, can be readily compared against values stored in a look-up table 109 for relating or referencing values of angular acceleration to values for the load size. It will be appreciated that a simple calibration procedure, such as measuring angular acceleration with no load in washer basket 18, could be performed at suitable time intervals for dynamically updating the values stored in look-up table 109 to compensate for any changes in the operational characteristics of the system. For a substantially constant spin speed, the pulse rate is substantially constant and thus changes in the pulse rate are essentially zero for a constant spin speed. In contrast, for a changing spin speed, i.e., during periods of angular acceleration, changes in the pulse rate have a nonzero value, which is proportional to the load in washer basket 18 as explained above. FIG. 8 shows an exemplary waveform for the output signal Sl supplied by first set of coils 74 upon initialization of the dry spin cycle, while FIG. 9 shows an exemplary waveform for the comparator output signal upon initialization of the dry spin cycle. As suggested above, spin speed can be accurately measured by simply counting the number of pulses received per unit of time. In the case of a coil set made up of four sensing coils, four pulses will be generated per each revolution of the washer basket and agitator. If for example, counter module 108 counts 16 pulses per second, then spin speed is four revolutions per second. It will be appreciated that one important advantage of the present invention is its simplicity of implementation. This allows for providing, at a low cost, a reliable and versatile sensing system.

FIG. 10 shows an exemplary waveform for the output signal Sl supplied by the set of coils 74 upon initialization of the dry spin cycle, while FIG. 11 shows an exemplary waveform for the comparator output signal upon initialization of the dry spin cycle. As suggested above, the load in washer basket 18 can be accurately measured by simply measuring angular acceleration, i.e., measuring changes in the number of pulses received per unit of time. It will be appreciated that one important advantage of the present invention is its simplicity of implementation. This allows for providing, at a low cost, a reliable and versatile sensing system. In accordance with one embodiment of the instant invention, FIG. 12 shows that magnetic source 50 can be laterally attached to washer basket 18, i.e., attached to a lateral section of washer basket 18. In this case, at least one magnetic sensor 170 is attached, at a predetermined height, to a predetermined lateral wall of cabinet 12 to be electromagnetically coupled to magnetic source 50 as washer basket 18 rotates relative to magnetic sensor 170. By way of example, magnetic sensor 170 is made up of a first magnetic sensing element, such as an inductive coil 171, and a second sensing element, such as an inductive coil 172. It will be appreciated by those skilled in the art that suspension system 28 that supports washer basket 18 can be readily designed for allowing washer basket 18, and in turn magnetic source 50, to travel along a predetermined travel axis 178 based on the load in washer basket 18. For example, travel axis 178 can extend in a generally vertical direction, i.e., a direction generally parallel relative to the lateral walls of cabinet 12. Thus, as washer basket 18 is loaded, washer basket 18 , including magnetic source 50, will sink or droop relative to sensor 170. Thus, the respective relative positioning of each coil 171 and 172 with respect to magnetic source 50 can be conveniently employed, as will be explained shortly hereafter, for obtaining load information as washer basket 18 rotates about spin axis 58. For example, each coil

171 and 172 can be situated to have a predetermined spacing between one another along the predetermined travel axis 178. In this manner, the relative positioning of the first and second coils 171 and

172 with respect to any actual path traveled by magnetic source 50 during the dry spin cycle (or even during a dry agitation cycle characterized by back-and-forth motion of the agitator) allows for generating respective output signals that can be readily processed for measuring the load in washer basket 18. This embodiment assumes that both washer basket 18 and tub 34 are made of a suitable nonmagnetic material, such as plastic or the like. It will be appreciated by those skilled in the art that additional sensors, such as sensor 173, substantially identical to sensor 170, can be attached to predetermined additional lateral walls of cabinet 12 at substantially the same predetermined height relative to one another. By way of example, each sensor can be situated to have a predetermined angle with respect to one another in a substantially horizontal plane, i.e., in a plane substantially perpendicular to travel axis 178 of washer basket 18. For a case of two sensors, such angle could be conveniently chosen as 90° or 180°. In a more general case, the predetermined angle can be conveniently chosen to position respective ones of the additional sensors and the one sensor in substantial equiangular relationship relative to one another in the substantially horizontal plane. Thus, in general, an angle φ could be chosen so that Φ = 360°/N, wherein N represents the total number of sensors used in the sensing system. The actual number of sensors is readily chosen based on the desired resolution and accuracy for the sensing system being that system resolution and accuracy are proportional to the number of sensors employed. As described in the context of FIG. 12, each respective first sensing elements 171 in each sensor 170 and 173 can be serially connected to one another to supply a respective combined output signal having a respective amplitude that varies based on the relative positioning of each first sensing element 171 with respect to magnetic source 50, as magnetic source 50 passes near sensors 170 and 173. Similarly, each respective second sensing elements 172 in each sensor 170 and 173 can be serially connected to one another to supply a respective combined output signal that varies based on the relative positioning of each second sensing element 172 with respect to magnetic source 50, as magnetic source 50 passes near sensors 170 and 173. Again it will be appreciated by those skilled in the art that the sensors need not be limited to inductive coils being that other magnetic sensing elements, such as solid state magnetic sensors, could be conveniently employed in lieu of inductive coils.

FIG. 13 shows a signal processor 200 that allows for measuring load by performing relatively simple signal processing on output signals S5 and S6 respectively supplied from the first and second sensing elements 171 and 172. As shown in FIG. 13, signal processor 200 includes a first amplifier, such as an operational amplifier 207ι having two input ports, coupled through a suitable resistor 205^, for receiving output signal S5 from each first sensing element 171. Signal processor 200 further includes a second amplifier, such as an operational amplifier 207 having two input ports, coupled through a suitable resistor 2052, for receiving output signal S6 from each second sensing element 172. For example, after respective suitable amplification of signals S5 and S6 in operational amplifiers 207\ and 2072, each amplifier output signal is supplied to microprocessor 206 to be digitized using respective analog-to- digital converters 210χ and 2102- An arithmetic logic unit (ALU) 212 in microprocessor 206 allows for taking the ratio of the respective digitized signals so as to determine the load in washer basket 18. For example, if the ratio of the amplitude of the digitized output signal from each first sensing element 171 over the amplitude of the digitized output signal from each second sensing element 172 is computed in ALU 212, then during a relatively light load condition such ratio may be larger than unity, while during a relatively heavy load condition such ratio may be below unity.

Respective exemplary waveforms for the S5 and S6 output signals during a light load condition are shown in FIG. 14. In this case the peak-to-peak values for the output signal S5 will be larger than the peak-to-peak values for the output signal S6 being that each first sensing element 171 would be closer to the magnet path than each second sensing element 172. Respective exemplary waveforms for the S5 and S6 output signals during a heavy load condition are shown in FIG. 15. In this case the peak-to-peak values for the output signal S6 will be larger than the peak-to-peak values for the output signal S5 being that each second sensing coil 172 would, for a relatively heavier load, be closer to the magnet path than each first sensing element 171. For example, if the ratio of the amplitude of the digitized output signal from each first sensing element 171 over the amplitude of the digitized output signal from each second sensing element 172 is computed in ALU 212, then during a relatively light load condition such ratio may be larger than unity, while during a relatively heavy load condition such ratio may be below unity.

FIG. 16 shows exemplary respective connections for a first set of coils 274 and for a second set of coils 276 for detecting an OOB condition. During a balanced condition, first set of coils 274 supplies an output signal Sl' as described above in the context of FIGS. 6-9. In contrast, due to the outwardly spatial relationship of second set of coiis 276 relative to first set of coils 274, the output signal S2' provided by second set of coils 276 during a balanced condition will generally have lower peak-to-peak values as compared to the output signal from first set of coils 274. Respective exemplary waveforms for the Sl' and S2' output signals during a balanced condition are shown in FIG. 17. As will be understood by those skilled in the art, for a relatively benign load unbalance, the OOB condition can be characterized by substantially symmetrical excursions or oscillations of tub 34 so that magnetic source 50 travels in a relatively predictable path relative to the sensing coils, such as conceptualized by a path 280. As shown in FIG. 16, during this OOB condition, the radius of path 280 is larger than the radius of a path 278 traveled by magnetic source 50 during a balanced condition, and thus the output signal S2' from second set of coils 276 will now have larger peak-to-peak values than those for the output signal from first set of coils 274. Respective exemplary waveforms for the Sl' and S2' output signals during the above- described OOB condition are shown in FIG. 18.

FIG. 19 shows a signal processor 300 that allows for determining the presence of an OOB condition described in the context of FIG. 16 by performing relatively simple signal processing on the output signals Sl' and S2' respectively supplied from the first and second sets of coils (274, 276). As shown in FIG. 19, signal processor 300 includes a first amplifier, such as an operational amplifier 307ι having two input ports, coupled through a suitable resistor 305}, for receiving output signal Sl from the first set of coils

274. Signal processor 300 further includes a second amplifier, such as an operational amplifier 3072 having two input ports, coupled through a suitable resistor 3052, for receiving output signal S2' from the second set of coils 276. For example, after respective suitable amplification of signals Sl' and S2' in operational amplifiers 30 ^ and 3072 , each amplifier output signal is supplied to microprocessor 306 to be digitized using respective analog-to- digital converters 310χ and 3102- An arithmetic logic unit (ALU)

312 in microprocessor 306 allows for taking the ratio of the respective digitized signals so as to determine the presence of an OOB condition. For example, if the ratio of the digitized output signal from first set of coils 274 over the digitized output signal from second set of coils 276 is computed in ALU 312, then during a balanced condition such ratio will be typically larger than unity while during an OOB condition such ratio will be typically below unity. Once the presence of an OOB condition is determined, control instructions stored in a memory (not shown) allow microprocessor 306 to issue appropriate commands for interrupting or correcting the OOB condition. FIG. 20 shows a connection for a single set of coils 374 as previously described in the context of FIG. 6. As previously suggested, depending upon the severity of the load unbalance, an OOB condition can be characterized by substantially asymmetric excursions of tub 34 so that magnetic source 50 travels in a relatively unpredictable or chaotic path 380 relative to each coil of the single set of coils 374. During a balanced condition, exemplary waveforms for the coil output signal Sl" and the comparator output signal may be as shown in Fig 22, while during an OOB condition exemplary waveforms for the output may be as shown in FIG. 23. Thus, during an OOB condition, instead of each cycle of the comparator output signal having a substantially similar period or cycle-length with respect to one another, in this OOB condition, each respective cycle- length or period for the stream of cycles that makes up the comparator output signal is generally uneven with respect to one another. Thus by measuring or monitoring cycle-length deviation, an OOB condition can be detected.

FIG. 21 shows a signal processor 400 that allows for determining the presence of the OOB condition described in the context of FIG. 20 by again performing relatively simple signal processing on the output signal Sl" from first set of coils 374 or, alternatively, on an output signal S2" from a second set of coils. In this case the stream of pulses in the comparator output signal is supplied to a cycle-length metering device 414 which, over a suitable time interval, measures, for example, the cycle-length standard deviation from a predetermined cycle-length mean value stored in a memory 416. It can be shown that during a balanced condition, the difference between the measured cycle-length standard deviation and the mean value stored in memory 416 would be relatively low because each cycle in the stream of cycles that makes up the comparator output signal has a length or period substantially identical to each other. Conversely, during an OOB condition, the difference between the measured cycle-length standard deviation and the value stored in memory 416 would be relatively high because of the random or uneven cycle-length in the . comparator output signal. As suggested above, once the presence of an OOB condition is determined, control instructions stored in a memory unit (not shown) would readily allow microprocessor 406 to issue appropriate commands for correcting or interrupting the

OOB condition.

It will be appreciated by those skilled in the art that the above-described signal processors embodiments for sensing, respectively, spin speed and load conditions, including OOB conditions, can be readily integrated in a common microprocessor.

Further, it will be appreciated that the signal polarity comparison performed on the coil output signal by any external comparator device could be alternatively implemented directly in the microprocessor using, for example, a suitable zero-crossing detection algorithm for performing the signal polarity comparison on the coil output signal.

While only certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

Claims

What is claimed is:

1. A washing machine including a cabinet and a tub, said tub positioned inside said cabinet, said washing machine comprising:

a washer basket for holding articles to be cleansed, said basket positioned within said tub;

an agitator for agitating said articles to be cleansed during respective wash and rinse cycles, said agitator positioned in said washer basket-

means for rotating said washer basket and said agitator about a predetermined spin axis;

a magnetic source positioned within said washing machine for producing a predetermined magnetic field;

at least one magnetic sensor positioned to be electromagnetically coupled to said magnetic source for supplying an output signal that predeterminedly varies as said agitator rotates relative to said magnetic sensor; and

a signal processor coupled to said magnetic sensor for receiving said output signal supplied by said magnetic sensor, said signal processor adapted for measuring spin speed during said spin cycle and for measuring load conditions, including an out of balance condition, within said washer basket during said spin cycle based on said output signal received from said magnetic sensor.

2. The washing machine of claim 1, wherein said magnetic source is positioned substantially at the tip of said agitator.

3. The washing machine of claim 1, wherein said magnetic source is attached to a lateral section of said washer basket.

4. The washing machine of claim 3, wherein said at least one magnetic sensor is attached at a predetermined height to a predetermined lateral wall of said cabinet, said at least one sensor comprising first and second magnetic sensing elements situated to have a predetermined spacing between one another substantially along said predetermined travel axis.

5. The washing machine of claim 1, wherein said at least one magnetic sensor comprise respective inductive coils.

6. The washing machine of claim 1, wherein said at least one magnetic sensor comprise respective solid state magnetic sensors selected from the group consisting of magnetoresistive and Hall-effect solid state magnetic sensors.

7. The washing machine of claim 1, wherein said at least one magnetic sensor comprises a first set of spaced apart coils affixed to an inner surface of the lid of said washing machine.

8. The washing machine of claim 7 wherein each coil in said first set is positioned substantially equidistant from a point in said inner surface intersected by said spin axis.

9. The washing machine of claim 8, wherein each coil in said set of coils is positioned at a predetermined angle with respect to one another.

10. The washing machine of claim 9 wherein said predetermined angle is chosen to position respective ones of said mutually spaced coils in substantially equiangular relationship relative to one another.

11. The washing machine of claim 2 wherein said magnetic sensor comprises a first set of mutually spaced solid state magnetic sensors affixed to an inner surface of the lid of said washing machine.

12. The washing machine of claim 1 wherein said signal processor comprises a comparator coupled to receive the output signal from said set of coils and a microprocessor coupled to said comparator for processing the comparator output signal so as to determine spin speed or load conditions, including an out-of- balance condition, in said washer basket.

13. The washing machine of claim 12 wherein said microprocessor includes a counter for measuring pulse rate changes in the comparator output signal and a look-up table for referencing the measured pulse rate changes against predetermined values stored in said look-up table for determining the load in said washer basket.

14. The washing machine of claim 1, wherein said magnetic sensor further comprises a second set of spaced apart coils.

15. The washing machine of claim 14 wherein said signal processor comprises first and second operational amplifiers coupled to receive, respectively, first and second output signals from said first and second magnetic sensing elements and a microprocessor coupled to said first and second amplifiers for processing the respective output signals from said first and second amplifiers so as to determine the load in said washer basket.

16. The washing machine of claim 4, wherein said signal processor comprises first and second operational amplifiers coupled to receive, respectively, first and second output signals from said first and second magnetic sensing elements and a microprocessor coupled to said first and second amplifiers for processing the respective output signals from said first and second amplifiers so as to determine spin speed or load conditions, including out-of-balance conditions, during said spin cycle

17. The washing machine of claim 4 further comprising additional sensors substantially identical to said at least one sensor, said additional sensors being attached at substantially the same predetermined height to predetermined additional lateral walls of said cabinet to have a predetermined angle with respect to one another in a substantially horizontal plane.

18. The washing machine of claim 17 wherein each first sensing element in said at least one sensor and in each said additional sensors are serially coupled to one another to provide a combined first output signal and wherein each second sensing element in said at least one sensor and in each said additional sensors are serially coupled to one another to provide a combined second output signal.

19. The washing machine of claim 18 wherein said microprocessor includes converter means for digitizing the respective output signals from first and second amplifiers so as to supply a pair of digitized output signals, and an arithmetic logic unit for measuring a predetermined ratio of the pair of digitized output signals supplied by said converter means.

20. A system for sensing spin speed and load conditions, including an out-of-balance conditions, in a washing machine having a tub inside a cabinet, said tub enclosing a washer basket for holding articles to be cleansed and an agitator, said system comprising: a magnetic source positioned in said washing machine for producing a predetermined magnetic field;

at least one magnetic sensor positioned to be electromagnetically coupled to said magnetic source for supplying an output signal that varies as said agitator rotates relative to said magnetic sensor; and

a signal processor coupled to said magnetic sensor for receiving the output signal supplied by said magnetic sensor, said signal processor being adapted for measuring spin speed during said spin cycle and for detecting load conditions, including an out- of-balance condition, during said spin cycle based on the output signal received from said magnetic sensor.

21. The system of claim 20, wherein said magnetic source is positioned substantially at the tip of said agitator.

22. The system of claim 20, wherein said magnetic source is attached to a lateral section of said washer basket.

23. The system of claim 22, wherein said at least one magnetic sensor is attached at a predetermined height to a predetermined lateral wall of said cabinet, said at least one sensor comprising first and second magnetic sensing elements situated to have a predetermined spacing between one another substantially along said predetermined travel axis.

24. The system of claim 20, wherein said at least one magnetic sensor comprise respective inductive coils.

25. The system of claim 20, wherein said at least one magnetic sensor comprise respective solid state magnetic sensors selected from the group consisting of magnetoresistive and Hall- effect solid state magnetic sensors.

26. The system of claim 20, wherein said at least one magnetic sensor comprises a first set of spaced apart ceils affixed to an inner surface of the lid of said washing machine.

27. The system of claim 26 wherein each coil in said first set is positioned substantially equidistant from a point in said inner surface intersected by said spin axis.

28. The system of claim 27, wherein each coil in said set of coils is positioned at a predetermined angle with respect to one another.

29. The system of claim 28 wherein said predetermined angle is chosen to position respective ones of said mutually spaced coils in substantially equiangular relationship relative to one another.

30. The system of claim 21 wherein said magnetic sensor comprises a first set of mutually spaced solid state magnetic sensors affixed to an inner surface of the lid of said washing machine.

31. The system of claim 20 wherein said signal processor comprises a comparator coupled to receive the output signal from said set of coils and a microprocessor coupled to said comparator for processing the comparator output signal so as to determine spin speed or load conditions, including an out-of- balance condition, in said washer basket.

32. The system of claim 31 wherein said microprocessor includes a counter for measuring pulse rate changes in the comparator output signal and a look-up table for referencing the measured pulse rate changes against predetermined values stored in said look-up table for determining the load in said washer basket.

33. The system of claim 30, wherein said magnetic sensor further comprises a second set of spaced apart coils.

34. The system of claim 33 wherein said signal processor comprises first and second operational amplifiers coupled to receive, respectively, first and second output signals from said first and second magnetic sensing elements and a microprocessor coupled to said first and second amplifiers for processing the respective output signals from said first and second amplifiers so as to determine the load in said washer basket.

35. The system of claim 23, wherein said signal processor comprises first and second operational amplifiers coupled to receive, respectively, first and second output signals from said first and second magnetic sensing elements and a microprocessor coupled to said first and second amplifiers for processing the respective output signals from said first and second amplifiers so as to determine spin speed or load conditions, including out-of-balance conditions, during said spin cycle

36. The system of claim 23 further comprising additional sensors substantially identical to said at least one sensor, said additional sensors being attached at substantially the same predetermined height to predetermined additional lateral walls of said cabinet to have a predetermined ^'angle with respect to one another in a substantially horizontal plane.

37. The system of claim 36 wherein each first sensing element in said at least one sensor and in each said additional sensors are serially coupled to one another to provide a combined first output signal and wherein each second sensing element in said at least one sensor and in each said additional sensors are serially coupled to one another to provide a combined second output signal.

38. The system of claim 37 wherein said microprocessor includes converter means for digitizing the respective output signals from first and second amplifiers so as to supply a pair of digitized output signals, and an arithmetic logic unit for measuring a predetermined ratio of the pair of digitized output signals supplied by said converter means.