Non-volatile passive revolution counter with reed magnetic sensor

• US 6,628,741 B2
• Filed: 11/20/2001
• Issued: 09/30/2003
• Est. Priority Date: 11/20/2001
• Status: Active Grant

• Current Assignee: Netzer Precision Motion Sensors Ltd. (Sick)
• Original Assignee: Netzer Precision Motion Sensors Ltd. (Sick)
• Inventors: Netzer, Yishay
• Primary Examiner(s): Strecker, Gerard R.
• Application Number:
  US09/988,460
• Publication Number:
  US 20030094945A1
• Time in Patent Office: 679 Days
• Field of Search: 324/160, 324/163, 324/166, 324/168-174, 324/180, 324/207.13, 324/207.15, 324/259, 324/391, 324/392, 200/81.9 M, 738/610.8, 738/611.1, 738/617.7, 738/617.8, 335/205-207, 361/236, 361/239, 361/240, 377/15, 377/16, 377/21, 377/24, 377/24.1, 377/24.2, 340/870.02, 340/870.03
• US Class Current: 377/21
• CPC Class Codes: G01D 5/2515 with magnetically controlled switches, e.g. by movement of a magnet
• CPC Class Codes: G01F 15/06 Indicating or recording devices
• CPC Class Codes: G01P 3/487 delivered by rotating magnets

Abstract

A shaft revolution counter including one or more reed magnetic sensors interacting with one or more magnets attached to the shaft. The interaction generates voltage spikes in the reed magnetic sensors that are used as input signal to an electronic non-volatile counter, as well as its sole power source.

Claims

1. A device for counting based upon cyclic variations in a magnetic field, the device comprising:

(a) at least one reed magnetic sensor including;

(i) a reed mechanism having at least two magnetizable members initially separated by a gap and responsive to a varying magnetic field to abruptly close said gap, thereby causing an abrupt change in magnetic flux through said magnetizable members, and

(ii) a pickup coil associated with said reed mechanism, said abrupt change in magnetic flux through said magnetizable members inducing a voltage pulse in said pickup coil; and

(b) a non-volatile electronic counter electrically associated with said pickup coil, said non-volatile electronic counter being responsive to, and actuated solely by, said pulses.

2. A device for counting the accumulated bi-directional number of revolutions of a shaft, said device including:

at least one magnet attached to said shaft;

at least three stationary reed magnetic sensors, each of said reed magnetic sensors including;

(a) a reed mechanism having at least two magnetizable members initially separated by a gap and responsive to a varying magnetic field to abruptly close said gap, thereby causing an abrupt chanae in magnetic flux throuah said magnetizable members, and

(b) a pickup coil associated with said reed mechanism, said abrupt change in magnetic flux through said magnetizable members inducing a voltage pulse in said pickup coil,

said reed magnetic sensors in combination with said magnet generating voltage pulses with an energy in response to said shaft revolutions; and

a non-volatile electronic counter electrically associated with said at least three reed magnetic sensors, said counter being responsive to, and actuated solely by, said pulses.

3. A device for counting the accumulated uni-directional number of revolutions of a shaft, said device comprising:

at least one magnet mounted on said shaft, at least one reed magnetic sensor, and a non-volatile electronic counter, said at least one reed magnetic sensor including;

(a) a reed mechanism having at least two magnetizable members initially separated by a gap and responsive to a varying magnetic field to abruptly close said gap, thereby causing an abrupt change in magnetic flux through said magnetizable members, and

(b) a pickup coil associated with said reed mechanism, said abrupt change in magnetic flux through said magnetizable members inducing a voltage pulse in said pickup coil,

said at least one reed magnetic sensor in combination with said at least one magnet generating voltage spikes in response to said shaft revolutions, said counter being responsive to, and actuated solely by, said pulses.

4. An impeller type water meter with a rotating shaft, wherein said shaft rotations are monitored by a shaft revolution counter as in claim 3.

5. A remotely readable water meter comprising the water meter of claim 4 operating in combination with a portable readout device, wherein said water meter includes an energy receiving means and an information transmitting means, and wherein said portable readout device includes:

an energy transmitting means for energizing said water meter and an information receiving means for receiving information from said water meter.

6. A counter for counting ferromagnetic moving teeth, said counter comprising at least three reed magnetic sensors, each of said reed magnetic sensors including:

(a) a reed mechanism having at least two magnetizable members initially separated by a gap and responsive to a varying magnetic field to abruntlv close said gap, thereby causing an abrupt change in magnetic flux through said magnetizable members,

(b) a pickup coil associated with said reed mechanism, said abrupt change in magnetic flux through said magnetizable members inducing a voltage pulse in said pickup coil,

(c) a bias magnet,

said reed magnetic sensors responding to said teeth motion by generating signal pulses which are counted with a non-volatile electronic counter which is responsive to, and energized solely by, said pulses.