# US 8,378,836 B2 · Magnetic field strength threshold alarm > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,378,836 B2 - Document ID: US8378836B2 - Status: Granted - Kind: B2 - Application number: 12/623,616 - Filed: 2009-11-23 - Published: 2011-05-26 - Granted: 2013-02-19 - Earliest claimed: 2009-11-23 - Assignees: Kopp Development Inc. - Applicants: Keith Kopp; Harold Duane DeMent - Inventors: Keith Kopp; Harold Duane DeMent - Web page: https://patentgrep.com/patent/US8378836B2 ## CPC - G08B 21/02: Alarms for ensuring the safety of persons - B82Y 25/00: Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance - G01R 33/0385: {in relation with magnetic force measurements (magnetic force microscopes G01Q60/50)} - G01R 33/288: {Provisions within MR facilities for enhancing safety during MR, e.g. reduction of the specific absorption rate [SAR], detection of ferromagnetic objects in the scanner room} - G08B: SIGNALLING SYSTEMS, e.g. PERSONAL CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS - B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract A magnetic field strength threshold alarm that includes sensing means responsive to a magnetic field and actuating in response to field strength above a predetermined threshold, the sensing means being configured to be operational and able to actuate without consumption of energy; and alarm means for outputting an alarm responsive to the sensing means actuation, the alarm means being configured not to consume energy prior to actuation of the sensing means and only consuming energy subsequent to actuation of the sensing means. So, energy is not consumed by the alarm means prior to actuation. The alarm may be considered to include energy storage means for providing electrical energy, wherein the sensing means, the alarm means and energy storage means being operatively connected such that the electrical energy from the energy storage means is provided only when the sensing means is actuated. ## Claims ### Claim 1 A magnetic field strength threshold alarm including: a sensor responsive to a magnetic field and actuating in response to a strength of the magnetic field above a predetermined threshold, the sensor including: a housing including a seat support and an electrical contact; a movable member supported by the support of the housing for movement through a 360° range of directions, the movable member including a magnet responsive to the magnetic field to cause movement of the movable member irrespective of direction of incidence of the magnetic field, the movable member and the magnet thereof being configured to be operational such that the magnet responds to the magnetic field to move the moveable member without consumption of energy, the movable member also including an electrical conductor, movement of the movable member responsive the magnetic field of strength above the predetermined threshold causes the electrical conductor of the movable member to electrically engage the electrical contact of the housing so that electrical energy may flow through the electrical conductor of the movable member; and a bias member is connected between the movable member and the housing to bias the movable member away from an engagement of the electrical conductor of the movable member to the electrical contact of the housing; wherein the movable member includes a single sphere as a pivot point, located coincident with a center of mass of the movable member, the single sphere supported by the housing seat support, and the bias member biases the single sphere into engagement with the seat support; and an alarm device operatively connected to the sensor and outputting an alarm, via consumption of electrical energy, responsive to the sensor actuation via receipt of electrical energy proceeding through the electrical conductor of the movable member and the electrical contact of the housing responsive the magnetic field of strength above the predetermined threshold, the sensor and alarm device being configured such that the alarm device is only powered via the sensor actuation so that the alarm device does not to consume energy without the sensor actuation. ### Claim 2 (depends on 1) The magnetic field strength threshold alarm as set forth in claim 1, further including a circuit, operatively connected to the sensor and the alarm device, and an energy storage device, operatively connected to the circuit, the circuit operates to provide electrical energy from the energy storage device to the alarm device only when the sensor is actuated. ### Claim 3 (depends on 1) The magnetic field strength threshold alarm as set forth in claim 1, wherein the magnetic field strength threshold alarm is configured such that no electromagnetic energy radiates from the magnetic field strength threshold alarm when the sensor is not actuated. ### Claim 4 (depends on 1) The magnetic field strength threshold alarm as set forth in claim 1, wherein the bias member includes an adjustable spring, and adjustment to the spring changes the predetermined threshold of the strength of the magnetic field above which the sensor actuates. ### Claim 5 (depends on 1) The magnetic field strength threshold alarm as set forth in claim 1, wherein the movable member includes one or more magnets, where the number of magnets changes the predetermined threshold of the strength of the magnetic field above which the sensor actuates. ### Claim 6 (depends on 1) The magnetic field strength threshold alarm as set forth in claim 1, wherein the sensor is configured such that the sensor cannot be erroneously actuated by acceleration. ### Claim 7 (depends on 1) The magnetic field strength threshold alarm as set forth in claim 1, wherein the movable member includes a plurality of magnets. ### Claim 8 (depends on 7) The magnetic field strength threshold alarm as set forth in claim 7, wherein at least one of the plurality of magnets being on one side of the pivot point and at least one other of the plurality of magnets being located on an opposite side of the pivot point. ### Claim 9 (depends on 1) The magnetic field strength threshold alarm as set forth in claim 1, wherein the alarm device includes at least one of an audio alarm and a visual alarm. ### Claim 10 (depends on 1) The magnetic field strength threshold alarm as set forth in claim 1, wherein the magnetic field strength threshold alarm is configured such that the sensor is responsive to a magnetic field from a nuclear magnetic resonance device. ### Claim 11 (depends on 1) The magnetic field strength threshold alarm as set forth in claim 1, wherein the magnetic field strength threshold alarm is configured to be attached to equipment that may be brought into an MRI magnet room, and which will provide an alert in response to a magnetic field from an MRI within the MRI magnet room above the predetermined threshold of the strength of the magnetic field at the location of the equipment. ### Claim 12 (depends on 1) The magnetic field strength threshold alarm as set forth in claim 1, wherein the magnetic field strength threshold alarm is configured to be worn by a person.