LIGHT-EMITTING DIODE DRIVING CIRCUIT AND PLANAR ILLUMINATING DEVICE HAVING SAME
First Claim
1. A light-emitting diode driving circuit that drives a plurality of light-emitting diodes which are connected in series with each other and which are connected in series with a constant-current source for allowing a constant current to flow, the light-emitting diode driving circuit comprising:
- a plurality of switches, each of which is connected in parallel with each of the plurality of light-emitting diodes or is connected in parallel with a predetermined number of light-emitting diodes; and
a PWM signal generating unit that generates PWM signals for switching on and off states of the respective switches connected in parallel with their corresponding light-emitting diodes, according to target luminances of the respective light-emitting diodes, whereinthe PWM signal generating unit generates the PWM signals based on a plurality of timing control signals for controlling timings at which the plurality of switches are placed in one of an on state and an off state as an initial state.
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Accused Products
Abstract
There is provided an LED driver capable of preventing deterioration of display quality for moving image display in a display device employing, as a backlight, light-emitting diodes formed in a plurality of rows. An LED driver includes a plurality of bypass switches connected in parallel with a respective plurality of light-emitting diodes; switch control circuits that control on and off states of the bypass switches; registers provided in one-to-one correspondence with the bypass switches; a first counter and a second counter that count clocks; and comparators that compare the value of the first counter or the second counter with the values of the registers. Here, as timing control signals, a first reset signal is provided to the first counter and a second reset signal is provided to the second counter.
33 Citations
8 Claims
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1. A light-emitting diode driving circuit that drives a plurality of light-emitting diodes which are connected in series with each other and which are connected in series with a constant-current source for allowing a constant current to flow, the light-emitting diode driving circuit comprising:
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a plurality of switches, each of which is connected in parallel with each of the plurality of light-emitting diodes or is connected in parallel with a predetermined number of light-emitting diodes; and a PWM signal generating unit that generates PWM signals for switching on and off states of the respective switches connected in parallel with their corresponding light-emitting diodes, according to target luminances of the respective light-emitting diodes, wherein the PWM signal generating unit generates the PWM signals based on a plurality of timing control signals for controlling timings at which the plurality of switches are placed in one of an on state and an off state as an initial state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification