Koito Manufacturing Company, Ltd.

Fuminori Shiotsu

Masayasu Ito

Takanori Namba

Satoshi Kikuchi

Yasushi Noyori

Toshiyuki Tsuchiya

Kouichi Isobe

A circuit for lighting a semiconductor light source is provided. The circuit includes: a switching regulator including a switching element and configured to generate a drive current for the semiconductor light source using the switching element; and a control circuit configured to control on-off of the switching element such that the magnitude of the drive current comes close to a targeted value. The control circuit includes: a comparator configured to compare the magnitude of the drive current with the targeted value; an up/down counter configured to count a digital value in a counting-up direction or counting-down direction, based on a comparison result of the comparator; a digital-to-analog converter configured to convert the counted digital value into an analog signal; and a drive circuit configured to control on/off of the switching element based on the analog signal.

Semiconductor light source lighting circuit

A semiconductor light source lighting circuit includes a switching regulator that produces a drive current Iwith a switching element, and a control circuit that controls turning on and off of the switching element so that the magnitude of the drive current Iapproaches a target value. The control circuit includes an error comparator that compares the drive current Iand the target value, an up/down counter that performs a counting operation, in which the control digital value is incremented or decremented based on the result of the comparison, a D/A converter that converts the control digital value into an analog duty ratio setting signal S, and a drive circuit that controls the turning on and off of the switching element based on the signal S. The up/down counter stops the counting operation when the switching regulator is brought into the inactive state.

A vehicle lamp includes: N semiconductor light sources, wherein N is an integer of 1 or more; M fans configured to cool the N semiconductor light sources, wherein M is an integer of 1 or more; N current supply units configured to supply first current to the N semiconductor light sources, respectively; and a control unit configured to receive electric power supplied from an electric power source and supply second current to the N current supply units. The control unit includes: N switch elements that correspond to the N semiconductor light sources; M switch elements that correspond to the M fans; and a control circuit configured to control fan drive current supplied to the fans through the switch elements and the second current. The fans are coupled to the control unit.

Vehicle lamp

A vehicular lamp is arranged to save power by not driving a cooling fan when an LED is unlit. The vehicular lamp is capable of reducing cost and stopping a supply of current to the LED even in the case of open wiring in a supply of current to the cooling fan. The vehicular lamp includes LEDs connected in series, a cooling fan connected in series with the LEDs and arranged to cool the LEDs. A current supply circuit receives power supplied from a power source and supplies current to the LEDs and the cooling fan.

Vehicular lamp

A light emitting apparatus includes a light source block with semiconductor light sources connected in series to each other. A resistor is connected in parallel with one or more of the semiconductor light sources and is connected to two detecting target portions in portions linked to respective electrodes of the semiconductor light sources. A ground fault detecting circuit is connected to one of the two detecting target portions disposed on a ground potential side. The light source block has one of its terminals connected to a power supply and its other terminal grounded. By detecting a change in the voltage through the ground fault detecting circuit, a ground fault can be detected.

Light emitting apparatus

A light emitting device includes multiple light units each of which includes a semiconductor light source, and a current supply control means for controlling supply of current to the semiconductor light source. A control unit includes a control signal generation means for generating and providing a control signal. The light emitting device also includes switching means for controlling feeding from a DC power source to a corresponding one of the light units in response to the control signal. Each of the switching means is coupled to a corresponding one of the light units through a feed line.

Light emitting device

Relative comparison is made between a voltage applied to the whole of the first through eighth LEDs and a voltage applied to the first LED by a comparator. When the voltage applied to the whole of the LEDs has relatively dropped with respect to the voltage applied to part of the LEDs, the comparator outputs a Low Level signal, assumes an abnormality that accompanies a short-circuit fault in any one of the LEDs and causes a ninth LED to illuminate. Meanwhile, relative comparison is made between a voltage applied to the whole of the first through eighth LEDs and a voltage applied to the first LED by another comparator. When the voltage applied to the whole of the LEDs has relatively dropped with respect to the voltage applied to part of the LEDs, the comparator outputs a Low Level signal, assumes an abnormality that accompanies a short-circuit fault in the first LED and causes a ninth LED to illuminate.

Lighting control circuit for vehicle lighting fixture

When a forward direction voltage of any of several LEDstois lowered, a drain voltage of an NMOS transistoremployed in any of series regulatorstobecomes higher than a defined voltage. A zener diode ZD, which is connected to the LED where the abnormal condition occurs, becomes conductive. A voltage, which is increased from the defined voltage, is applied to a negative input terminal of a comparing amplifier, and an output voltage of the comparing amplifieris lowered by this increased voltage portion so that a gate voltage of the NMOS transistoris lowered. A current flowing through the NMOS transistoris decreased. Even if an abnormal condition caused by a voltage drop occurs in any of the LEDsto, then the LEDstocan be protected.

Lighting control apparatus of lighting device for vehicle

To control individually a plurality of loads to be turned on by combining a switching regulator with a charge pump circuit using some of the components of the switching regulator. An LED is controlled to be turned on by a switching regulator having an NMOS transistor connected to a transformer and a control circuit for generating an on/off signal. An LED is controlled to be turned on by a charge pump circuit that shares the NMOS transistor and the control circuit with the switching regulator to charge a condenser with an electric charge during an operation for turning on the NMOS transistor and discharge the electric charge accumulated in the condenser during an operation for turning off the NMOS transistor. Thus, circuit structure is simplified.

Power device for multiple light sources with switching and charge pump circuit

A lighting controller for a lighting device for a vehicle includes a semiconductor light source; a power source for supplying electric power; and control circuitry for controlling a supply of a current to the semiconductor light source. The control circuitry selectively supplies the current to the semiconductor light source through a resistance element or through a bypass circuit for bypassing the resistance element based on a determination of a state of the current. A method for controlling a lighting device for a vehicle includes receiving electric power from a power source; supplying a current to a semiconductor light source; determining a state of the current supplied to the semiconductor light source; and selectively supplying the current to the semiconductor light source through a resistance element or through a bypass circuit for bypassing the resistance element based on the determination of the state of the current.

Lighting controller for lighting device for vehicle

A lighting device for a vehicle comprises: a plurality of light source sections connected in parallel with each other; and a transformer for supplying an electric power to the plurality of light source sections. The transformer includes a primary coil and a plurality of secondary coils provided corresponding to the plurality of light source sections, for respectively supplying electric power to the corresponding light source sections. One end of each light source section is grounded and a semiconductor light emitting element is provided between one end and the other end of the light source section. The lighting device further comprises: a voltage detecting section for detecting voltages at the other ends of the plurality of light sources; and an output control section for controlling an electric current outputted from the transformer according to the voltage detected by the voltage detecting section.

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Shizuoka, Japan

Fuminori Shiotsu