Koito Manufacturing Company, Ltd.

Kentaro Murakami

Masayasu Ito

Hitoshi Takeda

Hiroki Ishibashi

A vehicular lamp has light source units connected in parallel, an output controlling switch operable to intermittently carry an electric current by repeating on and off, an output coil operable to output electric power according to current flowing into said output controlling switch in synchronization when said output switch switches, a selection controlling unit operable to select at least one said light source unit in synchronization when said output controlling switch switches and cause said at least one selected light source to receive the power output from said output coil, and a malfunction detecting unit operable to detect malfunction of each of said light source units, wherein said selection controlling unit selects at least one said light source unit among said light source units from which malfunction is not detected when said malfunction detecting unit detects malfunction of either of said light source units.

Vehicular lamp

A lighting circuit for lighting a vehicular lamp including a plurality of light-emitting diodes, includes: a selection unit for selecting the number of light-emitting diodes to be connected in series in the vehicular lamp based on an instruction from the outside; a switching regulator for applying an output voltage based on a power-supply voltage output by an external DC power supply to the selected number of light-emitting diodes to be connected in series, so as to supply a supply current to the selected number of light-emitting diodes; and an output controlling unit for controlling the output voltage of the switching regulator based on the supply current.

Lighting circuit

A switching regulator circuit for supplying two input potentials to a passive device that is driven by a potential difference between the two input potentials irrespective of potential differences between the two input potentials and a ground potential, includes: a low-voltage input terminal for receiving a lower input potential that is lower one of the two input potentials; a coil provided between the low-voltage input terminal and the passive device in series; and a switching device, provided between the low-voltage input terminal and the passive device to be in series with the coil, for making the coil generate a potential higher than the lower input voltage by repeatedly switching whether or not a current is allowed to flow in the coil, so as to supply the generated potential to the passive device.

Switching regulator circuit

A switching regulator circuit for controlling power supplied to a load, includes: a switching device for repeatedly going on or off to control a voltage or a current applied to the load; a detector for detecting a supply voltage or a supply current supplied to the load; and a controller for controlling a duration ratio of a period in which the switching device is on or off based on the supply voltage or supply current detected by the detector, so as to control a value of the voltage applied to the load. The controller includes: a saw-tooth wave generation unit for charging and discharging a saw-tooth wave generation capacitor grounded at one end so as to change a voltage at another end of the saw-tooth wave generation capacitor to a saw-tooth wave; a charge/discharge controller for changing a ratio of a charge rate and a discharge rate of the saw-tooth wave generation capacitor based on the supply voltage or supply current detected by the detector; and a switching device controller for comparing a voltage value of the saw-tooth wave generation capacitor with a predetermined threshold value and controlling the duration ratio of the period in which the switching device is on or off based on the comparison result.

Switching regulator circuit and vehicular lamp

A lighting circuit for lighting a vehicular lamp including a light-emitting diode, includes: a switching regulator for applying an output voltage based on a power-supply voltage received from a DC power supply provided in the outside thereof to the light-emitting diode so as to supply a supply current to the light-emitting diode; an abnormal state detector for detecting an abnormal state of the lighting circuit based on at least one of the output voltage of the switching regulator, the supply current and the power-supply voltage; and an output controlling unit for controlling the output voltage of the switching regulator based on the supply current or the output voltage of the switching regulator and lowering the output voltage of the switching regulator in a case where the abnormal state detector detected the abnormal state.

Growing community of inventors

Shizuoka-ken, Japan

Kentaro Murakami