# US 9,434,348 B2 · Seatbelt latch circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,434,348 B2 - Document ID: US9434348B2 - Status: Granted - Kind: B2 - Application number: 14/165,654 - Filed: 2014-01-28 - Published: 2014-09-18 - Granted: 2016-09-06 - Earliest claimed: 2013-03-15 - Assignees: TRW Vehicle Safety Systems Inc. - Applicants: TRW Vehicle Safety Systems Inc. - Inventors: Edgar H. Schlaps - Web page: https://patentgrep.com/patent/US9434348B2 ## CPC - B60R 22/48: Control systems, alarms, or interlock systems, for the correct application of the belt or harness - A44B 11/2565: {Illuminated buckles} - B60R 2022/4816: {for sensing locking of buckle} - G08G 1/00: Traffic control systems for road vehicles (arrangement of road signs or traffic signals E01F9/00 {; automatic vehicle control B62D}) - B60R: VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR - A44B: BUTTONS, PINS, BUCKLES, SLIDE FASTENERS, OR THE LIKE (fastenings specially adapted for footwear A43C) - G08G: TRAFFIC CONTROL SYSTEMS (guiding railway traffic, ensuring the safety of railway traffic B61L; arrangement of road signs or traffic signals E01F9/00; radar or analogous systems, sonar systems, lidar systems specially adapted for traffic control G01S13/91, G01S15/88, G01S17/88; {radar or analogous systems, sonar systems, lidar systems specially adapted for anti-collision purposes G01S13/93, G01S15/93, G01S17/93}) ## Abstract A seatbelt latch circuit can include an illumination source configured to illuminate a seatbelt latch in response to a signal. The seatbelt latch circuit can also include a status sensor configured to output a first current if the seatbelt latch is in a removed state, output a second current if the seatbelt latch is in an inserted state and output a third current if the seatbelt latch has a fault. The seatbelt latch circuit communicates with a vehicle electrical system through only two conductors. ## Claims ### Claim 1 A seatbelt latch circuit comprising: an illumination source configured to illuminate a seatbelt latch in response to a signal; and a status sensor configured to: output a first current if the seatbelt latch is in a removed state; output a second current if the seatbelt latch is in an inserted state; and output a third current if the seatbelt latch has a fault, wherein the first, second and third currents are each different currents; wherein the seatbelt latch circuit communicates with a vehicle electrical system through only two conductors. ### Claim 2 (depends on 1) The seatbelt latch circuit of claim 1, wherein the seatbelt latch circuit is housed in the seatbelt latch. ### Claim 3 (depends on 2) The seatbelt latch circuit of claim 2, wherein the illumination source is connected in series with the status sensor. ### Claim 4 (depends on 3) The seatbelt latch circuit of claim 3, wherein the illumination source comprises a light emitting diode (LED) connected in series with a resistor. ### Claim 5 (depends on 3) The seatbelt latch circuit of claim 3, wherein the status sensor comprises a Hall effect sensor configured to output a current that varies based on a presence or absence of a tongue inserted into the seatbelt latch. ### Claim 6 (depends on 3) The seatbelt latch circuit of claim 3, wherein the status sensor comprises one of a normally open and normally closed switch connected in parallel with a resistor, the switch being configured to change state based on a state of the seatbelt latch. ### Claim 7 (depends on 2) The seatbelt latch circuit of claim 2, wherein the illumination source is connected in parallel with the status sensor. ### Claim 8 (depends on 7) The seatbelt latch circuit of claim 7, wherein the illumination source comprises a light emitting diode (LED) connected in series with a resistor. ### Claim 9 (depends on 7) The seatbelt latch circuit of claim 7, wherein the status sensor comprises a hall effect sensor configured to output a current that varies based on a presence or absence of a tongue inserted into the seatbelt latch. ### Claim 10 (depends on 7) The seatbelt latch circuit of claim 7, wherein the status sensor comprises one of a normally open and normally closed switch connected in series with a resistor, the one of the normally open and normally closed switch being configured to change state based on a state of the seatbelt latch. ### Claim 11 (depends on 2) The seatbelt latch circuit of claim 2, wherein the illumination source comprises: a first light emitting diode (LED) of a first color; and a second LED of a second color, the second color being different that the first color. ### Claim 12 (depends on 2) The seatbelt latch circuit of claim 2, wherein the status sensor comprises: a Hall effect sensor configured to provide an output current that varies based on a presence or absence of a tongue being inserted in the seatbelt latch; and first and second diodes configured to receive the output current provided by the Hall effect sensor. ### Claim 13 A vehicle electrical system comprising: an illumination source configured to illuminate an associated seatbelt latch in response to a signal; a signal measurement system configured to provide a measured signal that varies based on a status of the associated seatbelt latch; a comparator configured to provide a status signal that indicates whether the seatbelt latch is in a removed or an inserted state or if a circuit housed in the seatbelt latch and including the illumination source has a fault, wherein the vehicle electrical system and the circuit housed in the seatbelt latch communicate over exactly two conductors; a pulse width modulator (PWM) configured to provide a pulse width modulated signal that varies as a function of an intensity control; and a driver configured to provide an amplified version of the pulse width modulated signal to the illumination source of the seatbelt latch circuit via a first of the exactly two conductors. ### Claim 14 (depends on 13) The vehicle electrical system of claim 13, further comprising a current sensor configured to receive an output signal from a status sensor via a second of the exactly two conductors. ### Claim 15 (depends on 13) The vehicle electrical system of claim 13, wherein the pulse width modulated signal further varies as a function of color control. ### Claim 16 A vehicle electrical system comprising: an illumination source configured to illuminate an associated seatbelt latch in response to a signal; a signal measurement system configured to provide a measured signal that varies based on a status of the associated seatbelt latch; and a comparator configured to provide a status signal that indicates whether the seatbelt latch is in a removed or an inserted state or if a circuit housed in the seatbelt latch and including the illumination source has a fault, wherein the vehicle electrical system and the circuit housed in the seatbelt latch communicate over exactly two conductors; a pulse width modulator (PWM) configured to provide a pulse width modulated signal that varies as a function of an intensity and color control; an H-bridge configured to provide a first driving signal to the illumination source of the seatbelt latch circuit via a first of the exactly two conductors and a second driving signal to the illumination source of the seatbelt latch circuit via a second of the exactly two conductors. ### Claim 17 A system comprising: a seatbelt latch circuit comprising: an illumination source configured to illuminate a seatbelt latch in response to a signal; and a status sensor configured to: output a first current if the seatbelt latch is in a removed state; output a second current if the seatbelt latch is in an inserted state; and output a third current if the seatbelt latch circuit has a fault, wherein the first, second and third currents are each different currents; and a vehicle electrical system comprising: a signal measurement system configured to provide a measured signal that varies based on a current output by the status sensor; and a comparator configured to provide a status signal that indicates whether the seatbelt latch is in the removed or inserted state or if the seatbelt latch circuit has a fault; wherein the seatbelt latch circuit communicates with a vehicle electrical system with no more than two conductors. ### Claim 18 (depends on 17) The system of claim 17, wherein the illumination source is connected in series with the status sensor, the illumination source comprising a light emitting diode (LED) connected in series with a resistor; and the status sensor comprising a Hall effect sensor configured to provide the first or second current based on a presence or absence of a tongue inserted into the seatbelt latch.