EP0550260B1

EP0550260B1 - Automatic faucet system

Info

Publication number: EP0550260B1
Application number: EP92311779A
Authority: EP
Inventors: Kenji Inax Corporation Shirai
Original assignee: Inax Corp
Current assignee: Inax Corp
Priority date: 1991-12-30
Filing date: 1992-12-24
Publication date: 1996-10-30
Anticipated expiration: 2012-12-24
Also published as: DE69214926T2; DE69214926D1; EP0550260A1; KR930013393A; JPH05179680A; JP2622640B2; TW202493B

Description

The present invention relates to an automatic faucet system for automatically discharging water from a discharge opening provided at an end of a discharge pipe by detecting a hand or the like by a sensor and more particularly to an automatic faucet system for detecting a hand or the like by ultrasound.
Conventionally, an automatic faucet system is used for washing hands or the like by automatically discharging water from a discharge opening when ultrasound transmitted from an oscillator of an ultrasonic sensor which is disposed near the discharge opening is reflected by an object such as a hand and is received by a receiver.
The conventional ultrasonic sensor measures the time interval from when ultrasound is transmitted from the oscillator to it being received by the receiver, and the sensor computes a distance to the object based on such time. When the distance changes in a short time, it judges that the object is moving, whereby it opens an electromagnetic valve or the like by a drive controller to discharge water automatically from the discharge opening provided at the end of the discharge opening pipe.
However, the ultrasonic sensor used for such prior art automatic faucet system has a problem in that water may be discharged from the discharge opening even when an object such as a hand is not stretched out due to a so-called crosstalk phenomenon, i.e. ultrasound transmitted from the oscillator may be directly received by the receiver.
DE-B-2034877, on which the preamble of claim 1 is based, discloses a control device for the water supply of a hand basin in which the Doppler effect of a moving object on transmitted ultrasound causes a valve to be opened and the water to be supplied to the basin.
It is an object of the present invention to provide an automatic faucet system which is highly reliable and causes no erroneous operation.
According to the present invention there is provided a system for automatically discharging water by detecting an object near a discharge opening,
comprising: detecting means for detecting a said object near said discharge opening, said detecting means having outputting means for transmitting ultrasound and receiving means for receiving ultrasound reflected back by a said object; and water supplying means including valve means for supplying water to said discharge opening when said detecting means detects said object; said detecting means further having means for comparing a frequency f1 of the output ultrasound and a frequency f2 of the received ultrasound and for outputting a valve opening signal when the received frequency f2 is greater than the output frequency f1 due to Doppler effect caused by approaching movement of said object,
characterised in that said detecting means has means for outputting a valve closing signal when the received frequency f2 becomes smaller than the output frequency fl due to the Doppler effect caused by receding movement of said object.
Thus, the sensor for detecting an object detects the object as a moving body and outputs a detection signal when a difference is generated between the frequency of the ultrasound transmitted from the oscillator and that of the ultrasound received by the receiver, so that a valve associated with the faucet is operated by being driven by a drive controller into which the detection signal is input and water is discharged to the object from the discharge opening provided at the end of the discharge opening pipe. The ultrasonic sensor utilizes Doppler effect and detects an object to be a moving body only when a frequency of ultrasound received differs from that of ultrasound transmitted. It ignores the received ultrasound when a crosstalk phenomenon occurs, i.e. when the frequency of the received ultrasound is the same with that of the oscillated ultrasound.
An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings, in which:-

Fig. 1 is a sectional view illustrating a system of a preferred embodiment of the present invention;
Fig. 2 is a block diagram showing a structure of the system of the preferred embodiment; and
Fig. 3 is a flow chart showing operations of the system of the preferred embodiment.

A discharge opening 5 is provided on a main body of the faucet 3 provided on a washstand 2. A water supply pipe 6, having an electromagnetic valve 8, is connected to the lower part of the main body of the faucet 3. The reference numeral 7 denotes a wash basin.
An ultrasonic sensor 9 for detecting a hand 100 stretched out is provided near the discharge opening 5. The ultrasonic sensor 9 is one utilizing Doppler effect constructed as shown in Fig. 2 so that it can detect the hand only when the hand 100 is moved.
The ultrasonic sensor 9 comprises a speaker 10 for oscillating and outputting ultrasound, a microphone 11 for receiving the ultrasound transmitted from the speaker 10 and reflected by the hand 100 and for converting and outputting the received ultrasound as an electrical signal, an oscillating circuit 12 for outputting an oscillating electric signal of frequency f1 (Hz) which is equal to that of the ultrasound transmitted from the speaker 10, a filter circuit 13 for passing the electric signal from the microphone 11 when a difference which exceeds a predetermined frequency is generated between the frequency f2 of the received signal of the receiver 11 and the frequency f1, i.e. when Doppler effect occurs, and an amplifier 14 for amplifying and outputting the electrical signal that passes through the filter circuit 13.
Due to the Doppler effect, the frequency f2 of the received ultrasound is higher than the frequency f1 of the transmitted ultrasound when the hand 100 approaches the microphone 11 and contrary to that, the frequency f2 of the received ultrasound is lower than the frequency f1 of the transmitted ultrasound when the hand 100 recedes from the microphone 11.
Accordingly, as shown in Fig. 3, when the hand 100 moves in the direction approaching to the sensor 9, f2 becomes greater than f1, thereby the received signal being output to the amplifier 14 through the filter circuit 13.
When the electrical signal output from the amplifier 14 is input to a drive controller 20, the electromagnetic valve 8 is opened by the signal from the drive controller 20 and water is discharged from the discharge opening 5.
After opening the valve, the sensor 9 monitors whether the hand 100 is continuously detected. That is, if the hand 100 is detected and f2 ≥ f1, water is continuously discharged. However, if the hand 100 cannot be detected, the valve is closed. When f2 < f1 even if the hand is detected, the valve is closed because it means that the hand is receding from the discharge opening.
In this faucet, even if a crosstalk phenomenon in which ultrasound from the speaker 10 is directly received by the receiver 11 occurs, since the frequency f2 of the received ultrasound is equal to that of the oscillated ultrasound f1, the electrical signal output from the microphone 11 cannot pass through the filter circuit 13. Accordingly, no erroneous detection due to a crosstalk phenomenon will take place by the sensor 9 of the present invention.

Claims

A system for automatically discharging water by detecting an object (100) near a discharge opening (5), comprising: detecting means (9) for detecting a said object near said discharge opening, said detecting means having outputting means (10) for transmitting ultrasound and receiving means (11) for receiving ultrasound reflected back by a said object; and water supplying means (6) including valve means (8) for supplying water to said discharge opening when said detecting means detects said object; said detecting means (9) further having means (20) for comparing a frequency f1 of the output ultrasound and a frequency f2 of the received ultrasound and for outputting a valve opening signal when the received frequency f2 is greater than the output frequency f1 due to Doppler effect caused by approaching movement of said object (100), characterised in that said detecting means (9) has means (20) for outputting a valve closing signal when the received frequency f2 becomes smaller than the output frequency f1 due to the Doppler effect caused by receding movement of said object (100).
The system according to claim 1, wherein said valve means is continued to be opened when said detecting means detects the reflected ultrasound after opening said valve means.
The system according to claim 1 or 2, wherein said detecting means (9) has a circuit means (13) for comparing the received frequency f2 and the output frequency f1 and passing the received signal when f2 is greater than f1 and when f2 is smaller than fl.
The system according to claim 3, wherein said detecting means (9) has an amplifier (14) for amplifying the signal passed through said circuit means (13) and outputting the amplified signal to said water supplying means (6).