Automatic faucet

• US 5,918,855 A
• Filed: 11/01/1995
• Issued: 07/06/1999
• Est. Priority Date: 12/20/1993
• Status: Expired due to Term

• Current Assignee: Toto Limited
• Original Assignee: Toto Limited
• Inventors: Iwashita, Hiroyuki, Kaneko, Yoshiyuki, Seki, Mitsuyoshi, Hamanaka, Tatsumi, Murahashi, Toshiyuki, Kawabata, Takatoshi, Honda, Tadahiro
• Primary Examiner(s): LEE, KEVIN L
• Application Number:
  US08/501,032
• Time in Patent Office: 1,343 Days
• Field of Search: 251/129.04, 251/129.01, 4/623
• US Class Current: 251/129.04
• CPC Class Codes: E03C 1/057 touchless, i.e. using sensors
• CPC Class Codes: Y10T 137/86389 Programmer or timer

Abstract

In an automatic faucet having a hand sensor S to start and stop discharging water automatically, only hands can be detected accurately without detecting a washbowl (chinaware) and water stream erroneously. The sensor S comprises a light emitter and a light receiver. The directional axis d of a detection region (in which the light emitting region of the light emitter and the light receiving region of the light receiver are overlapped with each other) intersects the discharged water stream, and further the intersection angle between both is adjusted less than 70 degrees, irrespective of the flow rate of the discharged water. The reflected light levels detected by the light receiver are sampled periodically to calculate an average value and a variance value on the basis of at least eight most updated sampled data. Water discharge is started and stopped on the basis of the calculated average value and the variance value.

Claims

1. An automatic faucet having a hand sensor for detecting presence or absence of hands within a hand washing space to start and stop discharging water from a water discharge opening automatically, the hand sensor comprises:

a transmitter for transmitting a signal wave to a transmission region directed toward the hand washing space;

a receiver for receiving a signal wave reflected from a reception region directed also toward the hand washing space;

a detection region being formed by a partial overlapping portion of both the transmission region and a reception region, and at least one of said wave of said transmission region and of said receiving region being adjusted to intersect a stream of water discharged from the water discharge opening, and said transmission region and said receiving region being adjusted to be roughly in parallel with each other.

2. The automatic faucet of claim 1, wherein an angle θ

between a directional axis of the detection region and an axis of the water stream is less than 70 degrees.

3. The automatic faucet of claim 1, wherein an angle θ

1 between a directional axis of the transmission region and axis of the water stream in less than 70 degrees.

4. The automatic faucet of claim 1, wherein;

an angle θ

2 between a directional axis of the reception region and an axis of the water stream is less than 70 degrees.

5. The automatic faucet of claim 1, wherein;

a water flow straightening element in a pipe passage for introducing water to the water discharge opening, to form a smooth rod-shaped water flow irrespective of flow rate of water discharged from the water discharge opening.

6. The automatic faucet of claim 5, wherein the water flow straightening element is a cylindrical cap for forming the water discharge opening, a diameter of the water discharge opening being determined 1.2 times longer than a water path length of the cylindrical cap.

7. The automatic faucet of claim 1, which further comprises a water sprinkling element for sprinkling water discharged from the water discharge opening in a pipe path for introducing water to the water discharge opening.

8. The automatic faucet of claim 1, wherein a distance between one of said transmitter and said receiver and said stream of water discharged from said water discharge opening is sufficiently long so that the signal wave reflected from the discharged water can be directed away from the receiver.

9. The automatic faucet of claim 1, wherein;

said transmitter is a light emitting element and said receiver is a photoelectric sensor, the light emitting element and the photoelectric sensor being housed within a faucet body of the automatic faucet in such a way that both the element and the sensor are arranged on a same plane at a distance of 0 to 5 cm apart from each other and that direction axes of both elements and the sensor are determined substantially parallel to each other.

10. The automatic faucet of claim 1, wherein;

said transmitter is a light emitting element and said receiver is a photoelectric sensor, the light emitting element and the photoelectric sensor being housed within a faucet body of the automatic sensor in such a way that the sensor is arranged a distance 70 mm apart from a water stream from the water discharge opening in a horizontal direction.

11. The automatic faucet of claim 1, wherein;

said transmitter is a light emitting element and said receiver is a photoelectric sensor, the light emitting element and the photoelectric sensor being housed within a faucet body of the automatic faucet in such a way that the sensor is arranged a distance 35 to 45 mm apart from a water stream from the water discharge opening in a vertical direction and a distance 60 mm or more apart from the same stream in a horizontal direction.

12. An automatic faucet for starting and stopping discharge of water automatically by detecting presence or absence of hands, as recited in claim 1, wherein a water discharge opening is directed so that water can be discharged slightly downward from a horizontal direction.

13. The automatic faucet of claim 12, which further comprises a flow rate control device for holding a water discharge rate at a constant level, irrespective of water pressure of a water supply source.

14. The automatic faucet of claim 12, further comprising a flow rate control device for holding the flow rate of the stream of water at a constant level irrespective of the water pressure of a water supply source.

15. An automatic faucet for starting and stopping discharging water automatically by detecting presence or absence of hands, comprising:

a water discharge opening directed slightly downward from a horizontal direction; and

a hand sensor for detecting presence or absence of hands within a hand washing space, having

a transmitter for transmitting a signal wave to a transmission region directed toward the hand washing space;

a receiver for receiving a signal wave reflected from a receiving region directed also toward the hand washing space; and

a detection region being formed by a partial overlapping portion of both said transmission region and said receiving region, and at least one of directional axes of said transmission region and of said receiving region being adjusted to intersect a stream of water discharged from said water discharge opening, at an angle less than 70 degrees irrespective of flow rate of the stream of water.