Koito Manufacturing Company, Ltd.

Shinji Ohta

Masayasu Ito

Tomoyuki Ichikawa

Takao Muramatsu

Masashi Yamazaki

Kotaro Matsui

Yasushi Noyori

Toshiyuki Tsuchiya

Toshikazu Tomono

Yuichi Miyashita

Susumu Ogo

Katsuya Fukuta

Masahiro Sawada

A linear regulator supplies a first drive current to a first light source in a first period in which the first light source is turned on and a second light source is not turned on, and in a second period in which the first light source and the second light source are turned on, and stops the supply of the first drive current in a third period in which the first light source and the second light source are turned off. A switching regulator supplies a second drive current to the second light source in the second period, and stops the supply of the second drive current in the third period.

Lighting circuit and vehicular direction indicator lamp

A driving circuit turns on and off a driving current Ithat flows through a light source, so as to control the lighting on/off state of the light source. A judgment circuit compares a voltage Vacross the light source with a threshold value, and judges the lighting on/off state of the light source based on the comparison result. A first resistor R is provided in parallel with the light source.

Lighting circuit

A rear turn lamp has a structure formed of divided components, i.e., a first lamp unit provided to a fixed portion of a vehicle body and a second lamp unit provided to a movable portion of the vehicle body. The first lamp unit is provided with a controller. A first lighting circuit turns on multiple first light sources. A second lighting circuit turns on multiple second light sources.

Rear turn lamp

Provided is a lighting circuit that drives a first light source and a second light source connected in series with each other. A bypass switch is provided in parallel with the second light source. A constant current circuit is connected in parallel with one of the first light source and the second light source. A drive circuit supplies a drive current to a serially-connected circuit of the first light source and the second light source.

Lighting circuit and vehicular lamp

Provided is a light source drive device including: a current supply device; and a light source device including a light emitting element that emits light by receiving drive current supplied from the current supply device, a temperature sensor that performs temperature detection at a position closer to the light emitting element than the current supply device, and a signal generation unit that outputs a control signal for controlling the drive current depending on a detected value of the temperature sensor to the current supply device. The signal generation unit generates a control signal for reducing the drive current depending on a temperature when the temperature detected by the temperature sensor is equal to or higher than a predetermined temperature.

Light source drive device and vehicle lamp

A lighting circuit for blinking a light-emitting unit having plural light sources is equipped with an abnormality detection unit which generates abnormality information when detecting an abnormality in even one of the plural light sources, and a holding circuit which holds the abnormality information during a period when the lighting circuit is supplied with a blinking signal. The lighting circuit supplies a drive current(s) to the plural light sources according to the blinking signal and stops supplying a drive current(s) to all of the plural light sources according to the abnormality information being held by the holding circuit.

Lighting circuit and vehicular turn signal lamp

A light source lighting circuit comprises a first lighting circuit for receiving current from the electric power supply line and supplying drive current to a first light source and a second lighting circuit for receiving the current from the electric power supply line and supplying drive current to a second light source. When a state of the drive current flowing to the first light source shows an abnormality, or when state of the drive current flowing to the second light source shows an abnormality, the first lighting circuit stops operation. When a state of the drive current flowing to the second light source shows an abnormality, or when a state of the drive current flowing to the first light source shows an abnormality, the second lighting circuit stops operation.

Light source lighting circuit and turn signal lamp

A vehicular lamp has a light-emitting portion connected in series to an input terminal to which a power supply voltage based on an on-board battery is configured to be applied, and having a plurality of light-emitting elements connected in series, a series connection circuit having a first current limiting resistor and a second current limiting resistor, which is inserted in series between the input terminal and the light-emitting portion, a resistor switching switch connected in parallel to one of the first current limiting resistor and the second current limiting resistor, bypass switches, each of which is connected in parallel to a required one of the light-emitting elements in the light-emitting portion, and a control circuit that turns off the resistor switching switch when at least one of the bypass switches is turned on.

Vehicular lamp

A discharge lamp lighting circuit for supplying an AC power to a discharge lamp includes first and second converters for receiving a DC voltage and stepping up the voltage. A controlling circuit drives the first and second converters CON, CONalternately at a first frequency and stops an operation of a side that is not driven such that the AC power is supplied to the discharge lamp to execute a lighting operation.

Discharge lamp lighting circuit

A lighting circuit includes a capacitor and inductor for a resonance, and a first output, a second output, a resistor and a monitor circuit. A DC-AC converting circuit generates an AC voltage from a DC voltage. The resistor has an end connected to the second output and the other end connected to an end of a secondary winding. A monitoring output is connected to the other end of the resistor, and is provided for providing a signal for monitoring a current flowing to a discharge lamp. The end of the resistor is connected to a grounding conductor GND. The monitor circuit receives a signal from the monitoring output. The monitor circuit generates a signal for monitoring a current IL flowing to the discharge lamp.

A DC/AC converterperforms AC conversion and a boosting function upon the reception of a DC voltage. A control unitcontrols the DC/AC converterto perform the lighting control of a discharge lamp. The DC/AC converter includes an AC conversion transformer, switching devicesH,L and a resonance capacitor, and drives the switching devices to produce series resonance in the capacitorand an inductance component for the transformeror the inductance device. Before the discharge lampis turned on, the drive frequency for the switching devices gradually nears a resonance frequency fto increase an unloaded output, and a start signal is supplied to the discharge lamp. After the lighting of the discharge lamp has been initiated, the drive frequency is defined that is higher, by a predetermined frequency displacement value &#x394;F, than the drive frequency immediately before the discharge lamp is turned on. And the drive frequency for the switching device is shifted to a frequency area fb that is higher than a resonance frequency fwhen the discharge lamp is turned on.

A discharge lamp lighting circuit includes a DC/AC converter, a starting circuit, a control unit, a plurality of switching elements driven by the control unit and a series LC resonance circuit. At the time of lighting the discharge lamp, the driving frequency of the switching elements is set to a value higher than a resonance frequency at a time of lighting the discharge lamp thereby to drive and control the switching elements. When the driving frequency reduces and the extinction of the discharge lamp is detected, the driving frequency is shifted to a frequency region which is higher than a resonance frequency at a time of extinguishing the discharge lamp thereby to restart the lamp. Further, when the driving frequency reduces to a value lower than the resonance frequency at a time of lighting the discharge lamp during the lighting of the discharge lamp, the driving frequency is restored to a frequency region higher than the resonance frequency at a time of lighting the discharge lamp.

In a discharge lamp lighting circuit, circuits, which respectively detect a voltage applied to a discharge lampand a current flowing through the discharge lamp are provided. Light on/off state, furthermore, light on/off state detecting meansis provided, which detects light on state or light off state of the discharge lamp, in that the absolute value of the difference between voltage and current detection values of the discharge lamp in light off state is larger than that in light on state.

In a lighting apparatus for a discharge lamp, a mask signal against a re-arc voltage is correctly generated to detect a lamp voltage accurately in view of a support to high frequency lighting such that the detection of the lamp voltage is not affected by the re-arc voltage. The lighting apparatus for the discharge lamp comprises a DC-AC converter for receiving an input voltage from a DC power supply to convert the input voltage to an AC voltage; detecting means for detecting a lamp voltage associated with a discharge lamp or a lamp voltage and a lamp current; and a signal generator circuit for generating a mask signal for excluding a re-arc voltage, which occurs at the time the polarity is inverted, from items to be detected, in the event of a detection of the lamp voltage. The signal generator circuit detects the lamp voltage or lamp current or a voltage at an output stage of the DC-AC converter to correctly capture a polarity inversion timing to generate a mask signal against the re-arc voltage. A timing shift of the mask signal can be limited within an allowable range even if the discharge lamp is lit at a high frequency.

Lighting apparatus for discharge lamp

A discharge lamp lighting circuit has a structure of a voltage resonance type including a transformer and a switching element to be provided on a primary side thereof as a DC&#x2014;DC converting circuit for converting a DC input voltage into a desirable DC voltage. The lighting circuit further includes a control circuit serving to ON/OFF control the switching element, thereby controlling an output voltage Vout of the DC&#x2014;DC converting circuit, and has a function of a current limitation related to the switching element. In the lighting circuit, if the output voltage Vout is raised, a current flowing to the switching element is limited to be decreased. Consequently, a voltage applied to the switching element can be suppressed, and furthermore, the winding ratio of the transformer does not need to be increased. Accordingly, it is possible to prevent an electrical efficiency from being deteriorated.

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Shizuoka, Japan

Shinji Ohta