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US 7,679,296 B2Granted
Light emitting diode drive circuit
AssigneeRicoh Company, Ltd.
InventorTomohiko Kamatani
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AssigneeRicoh Company, Ltd.
InventorTomohiko Kamatani
Estimating the term…
A drive circuit includes a constant voltage circuit to supply a constant voltage to one terminal of a load, a constant current circuit to supply a predetermined constant current to another terminal of the load in accordance with a pulse signal input externally, and a first reference voltage generator to generate and output a first reference voltage in accordance with an output voltage at an output terminal of the constant current circuit. The constant voltage circuit controls so that the first reference voltage is proportional to the output voltage output to the load.
A drive circuit, comprising:
An electrical apparatus that drives multiple light emitting devices comprising a drive circuit,
An electrical apparatus that drives a load, the electrical apparatus comprising a drive circuit, the drive circuit, comprising:
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
Converter circuits: switched mode power supply [SMPS]
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Electric heating
About 1 year 6 months of term left · ends 8 May 2028 (estimated)
This patent application claims priority to Japanese Patent Application No. 2007-126612, filed on May 11, 2007 in the Japan Patent Office, the entire contents of which are incorporated by reference herein.
This patent specification relates to a drive circuit, and more particularly, to a light emitting diode drive circuit.
Recently, light emitting diodes (LEDs) have come to be widely used in a variety of types of electrical equipment, for example, display devices, optical disk apparatuses, and the like, because of their low power requirements and long life. The light emitting diode emits light by supplying an electrical current to the light emitting diode by a LED drive circuit.
A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
FIG. 1 illustrates a schematic of a circuit configuration of a known LED drive circuit;
FIG. 2 illustrates a block diagram of a LED drive circuit according to a first example embodiment of the present disclosure;
In describing preferred embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner and achieve similar results.
Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, switching regulators according to example embodiments are described.
FIG. 2 is a block diagram of a drive circuit according to a first example embodiment of the present disclosure. The drive circuit 1 is mounted on an electronic device such as a mobile phone, and causes a LED 10 to emit light in accordance with a pulse signal Spwm modulated by PWM modulation. In some cases, the drive circuit 1 is mounted on the electronic device with the LED 10.