Dishwashers and detergent dispensers

Claim 2

A liquid dispenser for dispensing a first liquid to a reservoir, said dispenser comprising a pumping device having an inlet adapted to receive said liquid and an outlet adapted to be placed in communication with said reservoir, and control means controlling operation of the pumping device and effecting operation of the pumping device to pump a metered amount of said first liquid into said reservoir, said control means comprising a timer circuit, and sensing means adapted to sense the commencement of delivery of other liquid to said reservoir, said sensing means operating, during use of the dispenser and pursuant to said sensing, to activate the timer circuit to thereby actuate said pumping device for a first predetermined time, said timer circuit including a monostable multivibrator, said sensing means including first switch means actuated, in use of the dispenser, to activate the multivibrator by application of electric supply thereto, said timer circuit further including second switch means operated, pursuant to said application of supply to the multivibrator, to effect said actuation of the pumping device by switching electric supply thereto, said multivibrator being switched to a first state upon said application of said supply thereto at which state said actuation of the second switch means is not precluded, but passing to a second state after said predetermined time at which the second switch means is deactuated to end dispensing, said timer circuit further including latching means for latching said second switch means following application of supply to said multivibrator, until deactuation thereof under control of the multivibrator occurs, irrespective of any intervening deactuation of said first switch means.

Claim 3

A liquid dispenser as claimed in claim 1 wherein said multivibrator includes one or more active circuit elements switched in accordance with a degree of charge of a capacitor connected thereto, the capacitor being connected to charge through a resistor from said supply when the first switch means is actuated whereby the multivibrator is switched to a condition corresponding to said second state when a predetermined charge level of said capacitor is reached, and after said first predetermined time.

Claim 4

A liquid dispenser as claimed in claim 1 including third switch means operable to apply supply to said multivibrator to initiate operation thereof and to thereby effect operation of the second switch means for a second predetermined time under control of said multivibrator.

Claim 5

A liquid dispenser as claimed in claim 3 wherein said latching means operates to latch said second switch means in the actuated condition, until deactuated under control of said multivibrator, irrespective of intervening deactuation of the third switch means.

Claim 6

A liquid dispenser as claimed in claim 4, wherein said multivibrator including one or more active circuit elements switched in accordance with a degree of charge of a capacitor connected thereto, the capacitor being connected to charge through a resistor from said supply when the first switch means is actuated whereby the multivibrator is switched to a condition corresponding to said second state when a predetermined charge level of said capacitor is reached, and after said first predetermined time.

Claim 7

A liquid dispenser as claimed in claim 5 including fourth switch means operated in response to actuation of the third switch means to disconnect said resistor from said capacitor and connect a second resistor instead thereof, said resistors being variable and/or of different value in order to permit said second predetermined time to differ from said first predetermined time.

Claim 8

A liquid dispenser as claimed in claim 6 wherein upon actuation of said third switch means, said fourth switch means is latched to provide continuance of connection to said second resistor until deactuation of said second switch means occurs.

Claim 9

A liquid dispenser for dispensing a first liquid to a reservoir, said dispenser comprising a pumping device having an inlet adapted to receive said liquid and an outlet adapted to be placed in communication with said reservoir, and control means controlling operation of the pumping device and effecting operation of the pumping device to pump a metered amount of said first liquid into said reservoir, said control means comprising: detector means for detecting, in use of the dispenser, the electrical conductivity of liquid in said reservoir and first switch means operated under control of the detector means to cause actuation of said pumping device, said detector means being responsive to a decrease in electrical conductivity of said liquid below a predetermined level to effect said operation of said first switch means and said actuation of the pumping device at least until sufficient said first liquid is added to the liquid in the reservoir to increase the conductivity at least up to said predetermined level, said detector means including circuit elements making up three arms of a bridge circuit, means coupled to spaced electrodes affixable in the liquid of the reservoir so that the fourth arm of the bridge circuit is made up of the effective resistance of liquid between said electrodes, a first controllable switch, and means for applying an alternating voltage across one pair of opposed junctions of said bridge circuit, said first controllable switch being connected between the other pair of opposed junctions of the bridge circuit so as to be sensitive to the existence of an out of balance voltage therebetween, caused by an increase of resistance between the electrodes above a predetermined resistance representing said predetermined level of conductivity, said first controllable switch to then be operated to effect said operation of said first switch means and said actuation of said pumping device, said first controllable switch deactuating said pumping device pursuant to a subsequent decrease of said resistance below said predetermined resistance.

Claim 10

A liquid dispenser for dispensing a first liquid to a reservoir, said dispenser comprising a pumping device having an inlet adapted to receive said liquid and an outlet adapted to be placed in communication with said reservoir, and control means controlling operation of the pumping device and effecting operation of the pumping device to pump a metered amount of said first liquid into said reservoir, said control means comprising: detector means for detecting, in use of the dispenser, the electrical conductivity of liquid in said reservoir and first switch means operated under control of the detector means to cause actuation of said pumping device, said detector means being responsive to a decrease in electrical conductivity of said liquid below a predetermined level to effect said operation of said first switch means and said actuation of the pumping device at least until sufficient said first liquid is added to the liquid in the reservoir to increase the conductivity at least up to said predetermined level, said detector means including circuit elements making up three arms of a bridge circuit, means coupled to spaced electrodes affixable in the liquid of the reservoir so that the fourth arm of the bridge circuit is made up of the effective resistance of liquid between said electrodes, a first controllable switch, and means for applying an alternating voltage across one pair of opposed junctions of said bridge circuit, said first controllable switch being connected between the other pair of opposed junctions of the bridge circuit so as to be sensitive to the existence of an out of balance voltage therebetween, caused by an increase of resistance between the electrodes above a predetermined resistance representing said predetermined level of conductivity, said first controllable switch to then be operated to effect said operation of said first switch means and said actuation of said pumping device, said first controllable switch deactuating said pumping device pursuant to a subsequent decrease of said resistance below said predetermined resistance.

Claim 11

A liquid dispenser as claimed in claim 8 wherein said detector means includes a second controllable switch having a control electrode and two main current carrying electrodes and which can be switched between conductive and non-conductive states existing between the main current carrying electrodes pursuant to application of a control voltage to the control electrode, said first controllable switch being connected to apply to said control electrode voltage of one polarity delivered from said supply, when the first controllable switch is operated, thereby to effect switching of said first controllable switch to a state of conduction and said second controllable switch then operating said first switch means to actuate said pumping device.

Claim 12

A liquid dispenser as claimed in claim 9 wherein said first controllable switch is connected to be turned on pursuant to detection of said out of balance voltage and turns off to effect said deactuation of said pumping device, and wherein a capacitor is arranged to be brought to a charged condition when the first controllable switch is operated and being coupled to maintain said control electrode at a potential sufficient to maintain the second controllable switch in said state of conduction for a predetermined period after turning off of said first controllable switch.

Claim 13

A liquid dispenser as claimed in claim 10, wherein said first switch means includes a relay connected to be energised when said second controllable switch means is placed in said conductive state and having contacts which, when the relay is energised, cause application of electric supply to said pumping device.

Claim 14

A liquid dispenser as claimed in claim 11 including second switch means operable to disconnect supply to said detector and first switch means and operable to directly apply said supply to said pumping device for operation thereof.