washing machine

Abstract

To prevent a door locked state from being cancelled even by disturbance noise besides failure / malfunction of a program and a control part.SOLUTION: In a case where a rotational frequency of a drum is below a predetermined threshold value, an operation of a driving circuit 31 for controlling a door lock device 6A is permitted, and in a case of surpassing, the operation of the driving circuit 31 based on an operation signal from a control part 20 is banned. Safety circuits 50, 50a include: a pulse detection part 53 for detecting an edge of a rotation pulse from a rotation sensor provided at a drum; and a rotational frequency determination part 54 for determining the rotational frequency of the drum on the basis of the rotation pulse detected by the pulse detection part 53. The rotational frequency determination part 54 is constituted by using an integration circuit 54a for integrating ON / OFF time of the rotation pulse, and an integration hysteresis element 54b for outputting High when the output of the integration circuit 54a has surpassed a predetermined first integration threshold value β1, and for outputting Low when the same is below a predetermined second integration threshold value β2 smaller than this first integration threshold value β1.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to, for example, a washing machine provided with a door lock device for preventing the door from being opened. [Background technology]

[0002] Conventionally, washing machines generally have a door lock device to prevent the door from being opened. The door lock device locks and unlocks the door according to a control signal from a control unit. The control unit stores a program for controlling the operation of the washing machine, and controls the door lock device according to the program.

[0003] The control of a conventional door lock device will be described with reference to Fig. 5. Door lock device 106A has a drive circuit 131 including a solenoid 118a as a drive device to switch the position of a locking portion 118 that locks the door between a locking position and an unlocking position. Drive circuit 131 is connected to operation reception portion 151 that receives an operation signal from control portion 120. Control portion 120 supplies a solenoid power source PS for driving solenoid 118a to operation reception portion 151, and also supplies a door lock signal or unlock signal.

[0004] Therefore, in a conventional washing machine, when the rotation speed of the drum exceeds a predetermined rotation speed, when a solenoid power supply PS and a door lock signal are supplied from control unit 120 to operation reception unit 151, drive circuit 131 operates based on the operation signal to switch to the door lock state. After that, when the rotation speed of the drum falls below the predetermined rotation speed, a solenoid power supply PS and an unlock signal are supplied from control unit 120 to operation reception unit 151, and drive circuit 131 operates based on the operation signal to switch to the unlock state. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-33512 A Summary of the Invention [Problem to be solved by the invention]

[0006] In a conventional washing machine, if a solenoid power supply and unlock signal are supplied from control unit 120 to operation receiving unit 151 due to a malfunction or error of the program or control unit while the door is locked, the door may be erroneously unlocked even if the drum rotation speed exceeds a predetermined rotation speed.

[0007] Therefore, as a washing machine that prevents erroneous door unlocking due to a malfunction or error in such a program or control unit, it is considered effective to employ a safety board 130 equipped with a safety circuit 101 as shown in Fig. 6. Fig. 6 is a comparative example that will be compared with the present invention later.

[0008] The safety circuit 101 is independent of the control unit 120, and when it detects a rotation pulse input from the rotation sensor 153a, the make / break transistor Tr1 turns OFF, thereby cutting off the solenoid power supply PS for a certain period of time. After the certain period of time has elapsed, the make / break transistor Tr1 turns ON, energizing the solenoid power supply PS. However, if the next rotation pulse input is detected from the rotation sensor 153a before the rotation speed increases and the make / break transistor Tr1 turns ON, the make / break transistor Tr1 will maintain its OFF state. To achieve these functions, a D flip-flop 111 and peripheral components are used.

[0009] When a rotation pulse is input to the CK terminal (gate 3) of the D flip-flop 111, the output terminal Q (gate 5) is set ON and the inverted output terminal Q' (gate 6) is set OFF. The D flip-flop 111 is provided with an integration section 112 that counts the time that the output terminal Q is ON, and when a rotation pulse is input again, the integration value is reset by the reset transistor Tr2. Furthermore, if the integration value is not reset for a certain period of time, the clear transistor Tr3 turns ON, and when this is input to the CLR terminal of the D flip-flop 111, the Q' terminal is reset (ON) and the connect / disconnect transistor Tr1 turns ON.

[0010] The input interval of the rotation pulse input from the rotation sensor 153a is short when the drum rotation is fast, and the input interval is long when the drum rotation is slow. Therefore, when the drum rotation speed exceeds the predetermined rotation speed, the safety circuit 101 continuously detects the input of the rotation pulse and resets the integrating unit 112, so that the solenoid power supply PS is continuously cut off. Therefore, the door is prohibited from being unlocked even if the door is unlocked. On the other hand, when the drum rotation speed is below the predetermined rotation speed, the interval of the rotation pulse is long, so that when the integrating unit 112 exceeds the integral threshold corresponding to the predetermined rotation speed, the clearing transistor Tr3 is turned ON, the disconnecting transistor Tr1 is turned ON, and the solenoid power supply PS is energized. Therefore, the door can be unlocked by performing the door lock operation.

[0011] However, when such a configuration is adopted, the output of the integrator 112 is unstable, and when the voltage fluctuates near the integral threshold value, which is the operating point, the output terminal Q and the inverted output terminal Q' of the D flip-flop also behave unstably. This can result in erroneous detection, such as the Q' terminal of the D flip-flop turning on the power supply disconnection transistor Tr1 even though the drum rotation speed is increasing, making it possible to unlock the door by conducting the solenoid power supply PS, or conversely, the Q' terminal of the D flip-flop not turning on the power supply disconnection transistor Tr1 even though the drum rotation speed is low, preventing the door from being unlocked because the solenoid power supply PS is not conducting.

[0012] Furthermore, if noise is present on the rising or falling waveform of the rotation pulse edge, this circuit will directly invert the output terminals Q and Q' of the D flip-flop 111. This can lead to false detection, such as the Q' terminal turning OFF even though no rotation pulse is being generated, or conversely, the Q' terminal remaining ON even though a rotation pulse is being generated.

[0013] Furthermore, since digital components such as the D flip-flop 111 have low resistance to disturbance noise, not only false detection but also destruction, failure, etc. of the digital components may occur. In other words, although the safety circuit 101 can improve safety against defects and malfunctions of the program and control unit 120, there is a concern about the influence of disturbance noise on the safety circuit 101.

[0014] The present invention aims to provide a washing machine that can prevent the door from being erroneously released from a locked state due to not only a malfunction or error in the program or control unit, but also due to external noise. [Means for solving the problem]

[0015] In order to achieve the above object, the present invention takes the following measures.

[0016] That is, the washing machine of the present invention includes a drum disposed in a housing, a door lock device that switches a door provided in an openable and closable manner on the housing between a door lock state and an unlock state, a control unit that outputs an operation signal supplied to a drive circuit that controls the door lock device to an operation receiving unit, and a safety circuit that permits operation of the drive circuit based on the operation signal from the control unit when it is determined that the rotation speed of the drum is lower than a predetermined rotation speed, and prohibits operation of the drive circuit based on the operation signal from the control unit when it is determined that the rotation speed of the drum is higher than the predetermined rotation speed. the safety circuit includes a pulse detection unit that detects edges of a rotation pulse from a rotation sensor provided on the drum, and a rotation speed determination unit that determines the rotation speed of the drum based on the rotation pulse detected by the pulse detection unit, the rotation speed determination unit being configured using an integration circuit that integrates ON / OFF times of the rotation pulse, and an integration hysteresis element that outputs High when the output of the integration circuit exceeds a predetermined first integration threshold and outputs Low when the output falls below a predetermined second integration threshold that is smaller than the first integration threshold, and the operation reception unit, when receiving an operation signal for a solenoid power supply from the control unit, Leave When the safety circuit permits the operation of the drive circuit based on the operation signal from the control unit, teeth , supplying the solenoid power supply to the drive circuit; and when the safety circuit does not permit the operation of the drive circuit based on the operation signal from the control unit, the solenoid power is not supplied to the drive circuit; When a solenoid power supply is supplied to the drive circuit, if the operation receiving unit receives an operation signal of a door lock signal or an unlock signal from the control unit, the operation signal is supplied to the drive circuit, and the operation of the drive circuit based on the operation signal is carried out.

[0017] In the washing machine of the present invention, it is preferable that the pulse detection unit is configured using a differentiation circuit that differentiates the rotation pulse, and a differentiation hysteresis element that outputs High when the output of the differentiation circuit exceeds a predetermined first differentiation threshold, and outputs Low when the output falls below a predetermined second differentiation threshold that is smaller than the first differentiation threshold.

[0018] In the washing machine of the present invention, integral The hysteresis element preferably uses a Schmitt trigger circuit.

[0019] In the washing machine of the present invention, it is preferable that the washing machine is provided with a plurality of the safety circuits, the plurality of safety circuits being connected in series, each safety circuit sharing a power supply line to the drive circuit, and a drive power cut-off unit switching the on / off state of this power supply line, so that when all of the plurality of safety circuits are permitted, the power supply line becomes conductive and operation of the drive circuit based on an operation signal from the control unit is permitted.

[0020] In the washing machine of the present invention, it is preferable that the safety circuit is configured by hardware.

[0021] In the washing machine of the present invention, it is preferable that the safety circuit is configured by a circuit board separate from the control unit. Effect of the Invention

[0022] The washing machine of the present invention is provided with a safety circuit that permits operation of the drive circuit based on an operation signal from the control unit when it is determined that the rotation speed of the drum is below a predetermined predetermined rotation speed, and prohibits operation of the drive circuit based on an operation signal from the control unit when it is determined that the rotation speed of the drum is above the predetermined predetermined rotation speed.As a result, when the rotation speed of the drum exceeds the predetermined rotation speed, the safety circuit prohibits operation of the drive circuit based on an operation signal from the control unit, so that it is possible to prevent an operation signal from being supplied to the drive circuit from a malfunction or error in the program or control unit, causing the door to be unlocked by the operation signal.

[0023] Moreover, an integration circuit that integrates the rotation pulse signal from the rotation sensor is used to determine the rotation speed, and two integration thresholds corresponding to predetermined rotation speeds are set for the integration value, and an integration hysteresis element that inverts the output at these integration thresholds is used. This means that even if a disturbance occurs, the integration hysteresis element does not immediately react and invert the output, reducing the problems of destruction, breakdowns, and erroneous output caused by disturbance noise.

[0024] The washing machine of the present invention uses a differentiation circuit that differentiates the rotation pulse and a differentiation hysteresis element that inverts the differentiation value at two differentiation thresholds. This means that even if a disturbance occurs, the differentiation hysteresis element does not immediately react and invert the output, reducing the damage, breakdowns, and erroneous output caused by disturbance noise.

[0025] In the washing machine of the present invention, a Schmitt trigger circuit is used as the hysteresis element, and the Schmitt trigger circuit can be realized with one comparator and a resistor component. This makes it possible to reduce the number of digital components that have low resistance to disturbance noise. In other words, by halving the number of logic operation components compared to the circuit of the comparative example described above, it is expected that the rate of malfunctions caused by disturbance noise will be improved.

[0026] In the washing machine of the present invention, when all of the multiple safety circuits are enabled, the power supply line is made conductive and the drive circuit is enabled to operate. This allows the safety monitoring of the safety circuits to be duplicated, and the door lock state can be reliably prevented from being released by cutting off the power supply.

[0027] In the washing machine of the present invention, the safety circuit is configured by hardware, which makes it possible to prevent the door from being unlocked due to a program malfunction.

[0028] In the washing machine of the present invention, the safety circuit is configured on a circuit board separate from the control unit. By making it a physically separate board, the convenience of circuit design and certification of safety suitability is improved. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is a schematic cross-sectional view of a washing machine 100 according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a control block diagram of the washing machine 100 of FIG. [Diagram 3] FIG. 2 is a circuit diagram of the washing machine 100 of FIG. [Figure 4] 2 is an explanatory diagram of the operation of the washing machine 100 of FIG. 1. [Diagram 5] FIG. 1 is a circuit diagram of a conventional washing machine. [Figure 6] FIG. 4 is a diagram showing a comparative example to be contrasted with the circuit diagram of FIG. 3 of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a schematic cross-sectional view of a washing machine 100 according to an embodiment of the present invention.

[0031] 1, in the washing machine 100, a substantially cylindrical outer tub 2 is disposed inside a box-shaped housing 1, and a substantially cylindrical drum 4 for storing laundry is journaled inside the outer tub 2 by a main shaft 5 extending in the front-rear direction. A clothes insertion opening 2a formed on the front side of the outer tub 2 is opened and closed by a door 6, and laundry can be put in and taken out of the drum 4 when the door 6 is open.

[0032] The drum 4 can rotate around a horizontal axis. A large number of liquid passage holes 4a are formed on the peripheral surface of the drum 4. The solvent supplied to the outer tub 2 during washing and rinsing flows into the drum 4 through the liquid passage holes 4a, and the solvent discharged from the laundry in the drum 4 during centrifugal deliquescence is scattered toward the outer tub 2 through the liquid passage holes 4a.

[0033] The main shaft 5 is rotatably supported by a bearing 5a attached to the rear wall of the outer tub 2, and a main pulley 8 is attached to the tip of the main shaft 5 that protrudes further rearward. A motor 9 is installed at the bottom of the housing 1, and a motor pulley 10 is attached to the rotating shaft of the motor 9. The rotational power of the motor pulley 10 is transmitted to the main pulley 8 via a timing belt 11. As a result, when the motor 9 is driven, the drum 4 rotates around the main shaft 5 at a rotational speed that is reduced from the rotational speed of the motor 9 at a predetermined reduction ratio.

[0034] A liquid supply pipe 12 equipped with a liquid supply valve 12a is connected to the upper part of the rear wall of the outer bath 2, and when the liquid supply valve 12a is opened, the solvent is supplied to the outer bath 2 through the liquid supply pipe 12. A liquid drain pipe 16 equipped with a liquid drain valve 16a is connected to a liquid drain port provided at the bottom of the outer bath 2, and when the liquid drain valve 16a is opened, the solvent in the outer bath 2 is discharged outside the machine through the liquid drain pipe 16.

[0035] A door lock device 6A for preventing the door 6 from being opened is installed on the front surface of the housing 1. The door lock device 6A is controlled to be in an unlocked state in which the door 6 can be opened when the rotation speed of the drum 4 falls below a predetermined threshold value, and is controlled to be in a door locked state in which the door 6 cannot be opened when the rotation speed of the drum 4 exceeds the predetermined rotation speed.

[0036] 2 is a control block diagram of the washing machine 100 of this embodiment. The control unit 20 of the washing machine 100 is composed of, for example, a microcomputer, and includes a CPU, a ROM in which a program for controlling the operation of the washing machine 100 is stored, and a RAM in which data used when executing the program is temporarily stored. The operation of the washing machine 100 is controlled by the control unit 20.

[0037] The door lock device 6A has a locking portion 18 which is positioned at a locking position where the door 6 is locked to prevent the door 6 from being opened when the door is locked, and at a release position where the door 6 is not locked to allow the door 6 to be opened when the door is unlocked.

[0038] The door lock device 6A includes a solenoid 18a as a drive device for switching the position of the locking portion 18 between a locking position and a release position.

[0039] The door lock device 6A is controlled by operation signals (solenoid power supply, and door lock signal or unlock signal) supplied from the control unit 20 of the washing machine 100.

[0040] Specifically, when the door lock device 6A receives the solenoid power supply PS and a door lock signal from the control unit 20, the door lock device 6A moves the locking portion 18 to the locking position by the solenoid 18a to switch to the door lock state. When the door lock device 6A receives the solenoid power supply and an unlock signal from the control unit 20, the door lock device 6A moves the locking portion 18 to the unlocking position by the solenoid 18a to switch to the unlocked state.

[0041] The washing machine 100 has a safety board 30 and a drive circuit 31 that controls the door lock device 6A. The drive circuit 31 is a circuit for driving the solenoid 18a, and operates based on an operation signal from the control unit 20.

[0042] 3, and an operation receiving unit 51 that receives an operation signal from the control unit 20. The safety board 30 is connected to a washing machine power supply and a solenoid power supply PS.

[0043] The two safety circuits 50, 50a are circuits for preventing the door lock device 6A from unlocking the door when the door should not be unlocked.

[0044] Specifically, the two safety circuits 50, 50a each permit operation of the drive circuit 31 based on an operation signal from the control unit 20 when the rotation speed of the drum 4 falls below a predetermined specified rotation speed, and prohibit operation of the drive circuit 31 based on an operation signal from the control unit 20 when the rotation speed of the drum 4 exceeds the predetermined specified rotation speed.

[0045] In this embodiment, two safety circuits 50, 50a are arranged in series between the solenoid power supply PS and the operation reception unit 51 on the safety board 30, and the operation reception unit 51 is connected to the solenoid power supply PS via the two safety circuits 50, 50a. When the control unit 20 controls the solenoid 18a, it supplies the solenoid power supply PS, which is an operation signal, to the operation reception unit 51, but the solenoid power supply PS is supplied to the drive circuit 31 only when both of the two safety circuits 50, 50a permit the operation of the drive circuit 31 based on the operation signal from the control unit 20.

[0046] When the solenoid power supply PS is supplied to the drive circuit 31, if the operation receiving unit 51 receives an operation signal of a door lock signal or unlock signal from the control unit 20, the operation signal is supplied to the drive circuit 31, and the operation of the drive circuit 31 (door lock or unlock) based on the operation signal is carried out.

[0047] In contrast, when the solenoid power supply PS is not supplied to the drive circuit 31, even if the operation receiving unit 51 receives an operation signal of a door lock signal or unlock signal from the control unit 20, the operation signal is not supplied to the drive circuit 31, and the operation of the drive circuit 31 based on the operation signal (door lock or unlock) is not performed.

[0048] The safety circuit 50 includes a pulse detection unit 53 , a rotation speed determination unit 54 , and a drive power cutoff unit 55 .

[0049] Based on the detection signal from the rotation sensor 53a, the pulse detection unit 53 outputs a rotation pulse according to the rotation speed of the drum 4. The interval and pulse width of this rotation pulse become shorter as the rotation speed of the drum 4 increases, and become longer as the rotation speed of the drum 4 decreases. Therefore, based on the change in the interval and pulse width of the rotation pulse signal output from the pulse detection unit 53, it is possible to detect a change in the rotation speed of the drum 4.

[0050] The pulse detection unit 53 of this embodiment includes a differentiation circuit 53b and a differentiation hysteresis element 53c.

[0051] The differentiation circuit 53b is configured with an RC circuit, and differentiates the input rotation pulse to capture the rising edge and the falling edge of the rotation pulse and output the differential value (FIG. 4). <a1>reference).

[0052] The differential hysteresis element 53c is configured by, for example, a Schmitt trigger circuit, and outputs High when the output of the differentiation circuit 53b exceeds a predetermined first differential threshold α1, and outputs Low when the output falls below a predetermined second differential threshold α2 that is smaller than the first differential threshold α1 (FIG. 4 <a2>reference).

[0053] On the other hand, the rotation speed determination unit 54 in this embodiment is configured to include an integration circuit 54a and an integral hysteresis element 54b.

[0054] The integration circuit 54a is configured with an RC circuit, and adds the time during which the output of the differential hysteresis element 53c is high by integration, and subtracts the time during which the output of the differential hysteresis element 53c is low by integration (see FIG. 4). <a3>That is, in the integrator circuit 54a, a positive time integration proceeds while the differential Schmitt trigger circuit 53c is at a high level, and a negative time integration proceeds while the differential Schmitt trigger circuit 53c is at a low level.

[0055] The integral hysteresis element 54b is configured by, for example, a Schmitt trigger circuit, and outputs High when the output of the integrating circuit 54a exceeds a predetermined first integral threshold β1, and outputs Low when the output falls below a predetermined second integral threshold β2 that is smaller than the first integral threshold β1 (FIG. 4 <a4>reference).

[0056] Waveform diagram of Figure 4(b) <b1> ~ <b4>is a waveform diagram of FIG. 4(a) when the rotation speed of the drum 4 becomes high, that is, when the pulse interval and pulse width become narrow. <a1> ~ <a4>correspond to each.

[0057] The drive power supply cutoff unit 55 is configured with a disconnecting transistor Tr1. The disconnecting transistor Tr1 has a base connected to the integral hysteresis element 54b, a collector connected to the solenoid power supply PS, and an emitter connected to the collector of the disconnecting transistor Tr1 of the second-stage safety circuit 50a.

[0058] The make / break transistor Tr1 turns on when the integral hysteresis element 54b goes high, and turns off when the integral hysteresis element 54b goes low.

[0059] On the other hand, the safety circuit 50a connected in series to the safety circuit 50 has a pulse detection unit 53, a rotation speed determination unit 54, and a drive power supply cutoff unit 55, similar to the safety circuit 50. The configurations and operations of the pulse detection unit 53, the rotation speed determination unit 54, and the drive power supply cutoff unit 55 of the safety circuit 50a are basically the same as those of the safety circuit 50, and detailed descriptions of the same parts will be omitted.

[0060] The difference between the safety circuit 50 and the safety circuit 50a is that the collector of the make / break transistor Tr1 of the safety circuit 50 is connected to the solenoid power supply PS, and the emitter is connected to the collector of the make / break transistor Tr1 of the safety circuit 50a. The emitter of the make / break transistor Tr1 of the safety circuit 50a is connected to the operation reception unit 51.

[0061] The door locking operation of the washing machine 100 will be described with reference to FIGS.

[0062] When drum 4 in washing machine 100 is driven to rotate, rotation pulse signals corresponding to the number of rotations are input from rotation sensor 53a to safety circuit 50 and safety circuit 50a, respectively.

[0063] First, the safety circuit 50 will be described. A rotation pulse signal from the rotation sensor 53a is input to the differentiation circuit 53b as an alternating waveform. <a1>As shown in FIG. 1, a signal having a generally impulse-like waveform is output, which swings in the positive direction at the rising edge of the rotation pulse and swings in the negative direction at the falling edge.

[0064] This signal is input to the differential hysteresis element 53c, which is shown in FIG. <a2>2, when the output of the differentiation circuit 53b exceeds the first differentiation threshold α1, it becomes High and maintains High until it falls below the second differentiation threshold α2. Moreover, when the output of the differentiation circuit 53b falls below the second differentiation threshold α2, the differentiation hysteresis element 53c becomes Low and maintains Low until it exceeds the first differentiation threshold α1. The output signal of the differentiation hysteresis element 53c is a square wave.

[0065] Figure 4 <a1>When noise is added to the output of the differentiation circuit 53b shown in FIG. 4, the waveform fluctuates near the threshold value. <a2>Because of this hysteresis, once the signal goes high or low, the high or low state is maintained until the next rising or falling edge of the rotation pulse from the differentiation circuit 53b is detected.

[0066] The output signal of the differential hysteresis element 53c is input to the integrating circuit 54a. <a3>5, when the output of the differential hysteresis element 53c becomes High, positive time integration is started, and when the output of the differential hysteresis element 53c becomes Low, negative time integration is started. The output signal of the integration circuit 54a has a roughly sawtooth waveform.

[0067] The output signal of the integrating circuit 54a is input to the integral hysteresis element 54b. The integral hysteresis element 54b is shown in FIG. <a4>As shown in Fig. 1, when the output of the integration circuit 54a exceeds the first integration threshold β1, it goes High and remains High until it falls below the second integration threshold β2. Also, when the output of the integration circuit 54a falls below the second integration threshold β2, the integration hysteresis element 54b goes Low and remains Low until it exceeds the first integration threshold β1. The output signal of the integration hysteresis element 54b is a square wave.

[0068] When the rotation speed of drum 4 is low and the pulse width and pulse interval are long, <a2>As shown in FIG. 4, the time ta during which the output of the differential hysteresis element 53c is high is long. <a3>As shown in FIG. 1, the integration of the integration circuit 54a proceeds, so that when the rotation speed of the drum 4 exceeds a predetermined rotation speed, the integration value exceeds the first integration threshold value β1 of the integration hysteresis element 54b. <a4>As shown in Figure 1, the integral hysteresis element goes high.

[0069] Negative integration proceeds in the integrator circuit 54a, and the disconnecting transistor Tr turns on until the integral hysteresis element 54b inverts to low. In the safety circuit 50a, if it detects that the rotation speed of the drum 4 is low, the disconnecting transistor Tr1 turns on through substantially the same operation. As a result, the solenoid power supply PS is conducted to the operation receiving unit 51 via the disconnecting transistor Tr1. Therefore, when the operation receiving unit 51 receives an unlocking operation, the drum 4 is unlocked.

[0070] After that, when the differential circuit 53b detects the falling edge of the rotation pulse and the differential hysteresis element 53c is inverted to low, the integration circuit 54a starts negative integration. Then, when the rotation speed of the drum 4 exceeds a predetermined rotation speed, the integral value falls below the second integral threshold value β2, and <a4>As shown, integral hysteresis element 54b goes low.

[0071] On the other hand, when the rotation speed of the drum 4 increases and the pulse width and pulse interval of the rotation pulse become shorter, as shown in FIG. <b2>As shown in FIG. 4, the time tb during which the output of the differential hysteresis element 53c is high is shortened. <b3>As shown in FIG. 4, the output of the differential hysteresis element 53c is inverted to Low before the integration of the integration circuit 54a has progressed sufficiently. Therefore, the integral value cannot exceed the first integral threshold value β1 of the integration hysteresis element 54b, and the integration hysteresis element 54b is inverted to Low. <b4>As shown in Fig. 1, the solenoid power supply PS does not become high but remains low. Therefore, the make / break transistor Tr1 does not turn on, and the solenoid power supply PS is not conducted through the make / break transistor Tr1.

[0072] Similarly, in the safety circuit 50b, if an increase in the rotation speed of the drum 4 is detected, the on / off transistor Tr1 is not turned on, and as a result, the solenoid power supply PS is not turned on to the operation receiving unit 51. For this reason, even if the operation receiving unit 51 receives an unlocking operation, the drum 4 is not unlocked.

[0073] Figure 4 <a3>When noise is present in the output of the integrating circuit 54a shown in FIG. 4, the waveform fluctuates near the threshold value. <a4>Because of this hysteresis, once the signal goes High or Low, it remains High or Low until the integration circuit 54a next detects another threshold value.

[0074] The washing machine 100 of this embodiment is a washing machine comprising: a drum 4 arranged in a housing 1; a door lock device 6A that switches a door 6, which is openably and closably provided on the housing 1, between a door locked state and an unlocked state; a control unit 20 that outputs an operation signal supplied to a drive circuit 31 that controls the door lock device 6A; and safety circuits 50, 50a that permit operation of the drive circuit 31 based on the operation signal from the control unit 20 when it is determined that the rotation speed of the drum 4 is below a predetermined rotation speed, and prohibit operation of the drive circuit 31 based on the operation signal from the control unit 20 when it is determined that the rotation speed of the drum 4 is above the predetermined rotation speed.

[0075] The safety circuits 50, 50a include a pulse detection unit 53 that detects edges of a rotation pulse from a rotation sensor 53a provided on the drum 4, and a rotation speed determination unit 54 that determines the rotation speed of the drum 4 based on the rotation pulse detected by the pulse detection unit 53. The rotation speed determination unit 54 is configured using an integration circuit 54a that integrates the ON and OFF times of the rotation pulse, and an integral hysteresis element 54b that outputs High when the output of the integration circuit 54a exceeds a predetermined first integration threshold β1, and outputs Low when it falls below a predetermined second integration threshold β2 that is smaller than the first integration threshold β1.

[0076] As a result, when the rotation speed of the drum 4 exceeds a predetermined rotation speed, the safety circuits 50, 50a prohibit the operation of the drive circuit 31 based on an operation signal from the control unit 20, thereby preventing the door lock state from being released by an operation signal that is supplied from the control unit 20 to the drive circuit 31 due to a malfunction or error in the program or control unit.

[0077] Moreover, an integration circuit 54a is used to integrate the rotation pulse signal from the rotation sensor 53a to determine the rotation speed, and two integration thresholds β1 and β2 corresponding to predetermined rotation speeds are set for the integral value, and an integration hysteresis element 54b that inverts at these integration thresholds β1 and β2 is used. As a result, even if a disturbance occurs, the integration hysteresis element 54b does not immediately react and invert the output, and the occurrence of destruction, failure, and erroneous output due to disturbance noise can be effectively reduced.

[0078] In the washing machine 100 of this embodiment, the pulse detection unit 53 is configured using a differentiation circuit 53b that differentiates the rotation pulse, and a differentiation hysteresis element 53c that outputs High when the output of this differentiation circuit 53b exceeds a predetermined first differentiation threshold value α1 and outputs Low when the output falls below a predetermined second differentiation threshold value α2 that is smaller than the first differentiation threshold value α1.

[0079] As a result, even if a disturbance occurs, the differential hysteresis element 53c does not immediately react and invert the output, effectively reducing the damage, breakdown, and erroneous output caused by disturbance noise.

[0080] In the washing machine 100 of this embodiment, the hysteresis elements 53c and 54b are configured and used using a Schmitt trigger circuit, and the Schmitt trigger circuit can be realized by one comparator and a resistor component. In the comparative example shown in FIG. 6, since the D flip-flop has four NAND gates inside, four digital components are required for one safety circuit. In contrast, in this embodiment, the Schmitt trigger circuit can be configured by two digital components.

[0081] In the washing machine 100 of this embodiment, a plurality of safety circuits 50, 50a are provided, and the plurality of safety circuits 50, 50a are connected in series. Each safety circuit 50, 50a shares a power supply line to the drive circuit 31 and is provided with a drive power cut-off unit 55 that switches the on / off state of this power supply line. When all of the plurality of safety circuits 50, 50a are permitted, the power supply line is made conductive, and operation of the drive circuit 31 based on the operation signal from the control unit 20 is permitted.

[0082] Therefore, the safety monitoring of the safety circuits 50, 50a is duplicated, and the door lock state can be reliably prevented from being released by cutting off the power supply.

[0083] In the washing machine 100 of the present embodiment, the safety circuits 50 and 50a are configured by hardware.

[0084] This prevents the door from being unlocked due to a program malfunction.

[0085] In the washing machine 100 of this embodiment, the safety circuits 50 and 50a are configured by a circuit board 30 separate from the control unit 20.

[0086] For this reason, by using a physically separate board, the convenience of circuit design and certification of safety compliance is improved.

[0087] Although the embodiment of the present invention has been described above, the specific configuration of each part is not limited to the above-described embodiment.

[0088] For example, in the above embodiment, the washing machine 100 having the drum 4 rotatable around a rotation axis along the horizontal direction has been described, but the present invention is applicable to a washing machine having a drum 4 rotatable around a rotation axis inclined with respect to the horizontal direction. Also, the present invention is applicable to a vertical washing machine having a washing tub (drum) rotatable around a rotation axis along the vertical direction.

[0089] In the above embodiment, the washing machine has two safety circuits 50 and 50a, but the number of safety circuits is arbitrary. The washing machine of the present invention may have one safety circuit or three or more safety circuits.

[0090] In the above embodiment, the door lock device 6A has the solenoid 18a as a drive device for driving the locking portion 18, but the drive device is not limited to this. In the door lock device 6A, the locking portion 18 may be driven by, for example, a motor as a drive device.

[0091] Other configurations can also be modified in various ways without departing from the spirit of the present invention. [Explanation of symbols]

[0092] 1 Case 4 Drums 6 Doors 6A Door lock device 20 Control section 30 Safety board 31 Drive circuit 50,50a safety circuit 51 Operation reception section 53 Pulse detection unit 53b Differential circuit 53c Differential Hysteresis Element 54 Rotation speed determination unit 54a Integrator circuit 54b Integral Hysteresis Element 55 Drive power cutoff section 100 Washing Machine < / a1> < / b1>

Claims

1. A drum disposed within the housing; a door lock device for switching a door provided in the housing in an openable and closable manner between a door lock state and a door unlock state; a control unit that outputs an operation signal supplied to a drive circuit that controls the door lock device to an operation reception unit; a safety circuit that permits operation of the drive circuit based on an operation signal from the control unit when it is determined that the rotation speed of the drum is lower than a predetermined rotation speed, and prohibits operation of the drive circuit based on an operation signal from the control unit when it is determined that the rotation speed of the drum is higher than the predetermined rotation speed, The safety circuit includes: a pulse detection unit that detects an edge of a rotation pulse from a rotation sensor provided on the drum; a rotation speed determination unit that determines the rotation speed of the drum based on the rotation pulse detected by the pulse detection unit, the rotation speed determination unit is configured using an integration circuit that integrates ON and OFF times of the rotation pulse, and an integration hysteresis element that outputs High when the output of the integration circuit exceeds a predetermined first integration threshold and outputs Low when the output falls below a predetermined second integration threshold that is smaller than the first integration threshold, when the operation reception unit receives an operation signal for a solenoid power supply from the control unit, if the safety circuit permits the operation of the drive circuit based on the operation signal from the control unit, the operation reception unit supplies the solenoid power supply to the drive circuit, and if the safety circuit does not permit the operation of the drive circuit based on the operation signal from the control unit, does not supply the solenoid power supply to the drive circuit; When the operation receiving unit receives an operation signal of a door lock signal or a door unlock signal from the control unit while solenoid power is supplied to the drive circuit, the operation signal is supplied to the drive circuit, and the drive circuit operates based on the operation signal.

2. 2. The washing machine according to claim 1, wherein the pulse detection unit is configured using a differentiation circuit that differentiates the rotation pulse, and a differentiation hysteresis element that outputs High when the output of the differentiation circuit exceeds a predetermined first differentiation threshold and outputs Low when the output of the differentiation circuit falls below a predetermined second differentiation threshold that is smaller than the first differentiation threshold.

3. 2. The washing machine of claim 1, wherein the integral hysteresis element is a Schmitt trigger circuit.

4. A plurality of the safety circuits are provided, the plurality of safety circuits are connected in series; Each safety circuit shares a power supply line to the drive circuit and includes a drive power cutoff unit that switches the power supply line between an on state and an off state, The washing machine according to any one of claims 1 to 3, characterized in that when all of the plurality of safety circuits are permitted, the power supply line is conductive and operation of the drive circuit based on an operation signal from the control unit is permitted.

5. 5. The washing machine according to claim 1, wherein the safety circuit is configured by hardware.

6. 6. The washing machine according to claim 1, wherein the safety circuit is configured on a circuit board separate from the control unit.

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