Apparatus and methods for driving solid-state illumination sources
First Claim
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1. A method for controlling the brightness of light output by a solid-state illumination source, the method comprising:
- obtaining a control value specifying a desired intensity of light to be emitted by the solid-state illumination source, wherein an increase in the control value corresponds to an increase in the intensity of light;
operating the solid-state illumination source in only a constant current mode without alternating or combining with any other mode if the control value is within a first range;
operating the solid-state illumination source in only a frequency modulation mode without alternating or combining with any other mode if the control value is within a second range greater than the first range; and
,operating the solid-state illumination source in only a pulse width modulation mode without alternating or combining with any other mode if the control value is within a third range greater than the second range.
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Abstract
A method for driving a solid-state illumination source to emit light having a brightness determined by a control value involves selecting a control mode based at least in part on the control value. In one embodiment a constant current is supplied to the solid-state illumination source for control values in a low range, a frequency-modulated (FM) current is supplied to the solid-state illumination source for control values in a mid range and a pulse-with modulation (PWM) current is supplied to the solid-state illumination source for control values in an upper range.
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Citations
41 Claims
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1. A method for controlling the brightness of light output by a solid-state illumination source, the method comprising:
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obtaining a control value specifying a desired intensity of light to be emitted by the solid-state illumination source, wherein an increase in the control value corresponds to an increase in the intensity of light; operating the solid-state illumination source in only a constant current mode without alternating or combining with any other mode if the control value is within a first range; operating the solid-state illumination source in only a frequency modulation mode without alternating or combining with any other mode if the control value is within a second range greater than the first range; and
,operating the solid-state illumination source in only a pulse width modulation mode without alternating or combining with any other mode if the control value is within a third range greater than the second range. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A method for controlling the brightness of light output by a solid-state illumination source, the method comprising:
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obtaining a control value specifying a desired intensity of light to be emitted by the solid-state illumination source, wherein an increase in the control value corresponds to an increase in the intensity of light; operating the solid-state illumination source in only a constant current mode without alternating or combining with any other mode if the control value is less than a first reference value; operating the solid-state illumination source in only a frequency modulation mode without alternating or combining with any other mode if the control value is greater than or equal to the first reference value and less than a second reference value; and
,operating the solid-state illumination source in only a pulse width modulation mode without alternating or combining with any other mode if the control value is greater than or equal to the second reference value. - View Dependent Claims (26, 27, 28, 29, 30)
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31. A driver for controlling a solid-state illumination source to emit light, the driver comprising:
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an input configured to receive a control value specifying a desired intensity of light to be emitted by the solid-state illumination source, wherein an increase in the control value corresponds to an increase in the intensity of light; an output connectable to control electrical current in the solid-state illumination source; at least one comparison unit configured to compare the control value with a first reference value and a second reference value; a constant-current driver configured to control the electrical current to have a constant value corresponding to the control value only if the control value is less than the first reference value; a frequency-modulation driver configured to control the electrical current to have pulses at a frequency corresponding to the control value only if the control value is between the first and second reference values; and
,a pulse-width-modulation driver configured to control the electrical current to have pulses having widths corresponding to the control value only if the control value exceeds the second reference value, wherein in operation, only one of the constant-current driver, frequency-modulation driver or pulse-width-modulation driver is applied to control the electrical current in response to the control value.
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32. A method for controlling the brightness of light output by a light emitting diode, the method comprising:
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receiving a control value specifying a desired intensity of light to be emitted by the light emitting diode, wherein an increase in the control value corresponds to an increase in the intensity of light; operating the light emitting diode in only a first mode without alternating or combining with any other mode if the control value is less than a first reference value; operating the light emitting diode in only a second mode without alternating or combining with any other mode if the control value is greater than the first reference value and less than a second reference value; and
,operating the light emitting diode in only a third mode without alternating or combining with any other mode if the control value is greater than the second reference value.
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33. A display comprising:
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an array of solid-state illumination sources; and
,a driver configured to control the solid-state illumination sources, the driver comprising; inputs connectable to receive control values specifying desired intensities of light to be emitted by the solid-state illumination sources, wherein higher control values correspond to higher intensities of light; outputs connectable to control electrical currents in the solid-state illumination sources; the driver configured to control the electrical currents according to modes determined based on the corresponding control values, the driver configured to control the electrical currents for illumination sources having control values in a first range in only a first mode without alternating or combining with any other mode, to control the electrical currents for illumination sources having control values in a second range in only a second mode without alternating or combining with any other mode, and to control the electrical currents for illumination sources having control values in a third range in only a third mode without alternating or combining with any other mode, wherein the driver comprises; a constant-current driver configured to control the electrical current of each solid-state illumination sources having a control value within the first range to have a constant value corresponding to the control value; a frequency-modulation driver configured to control the electrical current of each solid-state illumination sources having a control value within the second range greater than the first range to have pulses at a frequency corresponding to the control value; and
,a pulse-width-modulation driver configured to control the electrical current of each solid-state illumination sources having a control value within the third range greater than the second range to have pulses having widths corresponding to the control value. - View Dependent Claims (34, 35, 36, 37, 38)
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39. A method of displaying an image on a display comprising an array of light emitting diodes, the method comprising:
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obtaining image data specifying a desired image; processing the image date to obtain a control value for each light emitting diode of the array of light emitting diodes, wherein an increase in the control value corresponds to an increase in the intensity of light to be emitted by the light emitting diode; operating light emitting diodes having control values within a first range in only a constant current mode without alternating or combining with any other mode; operating light emitting diodes having control values within a second range greater than the first range in only a frequency modulation mode without alternating or combining with any other mode; and
,operating light emitting diodes having control values within a third range greater than the second range in only a pulse width modulation mode without alternating or combining with any other mode.
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40. A driver for controlling a solid-state illumination source to emit light, the driver comprising:
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input means for receiving a control value specifying a desired intensity of light to be emitted by the solid-state illumination source, wherein an increase in the control value represents an increase in the intensity of light; output means for controlling electrical current in the solid-state illumination source the output means configured to drive the illumination means in a mode determined based on the control values, the input means configured to drive the illumination means having control values in a first range in only a first mode without alternating or combining with any other mode, to drive the illumination means having control values in a second range in only a second mode without alternating or combining with any other mode, and to drive the illumination means having control values in a third range in only a third mode without alternating or combining with any other mode, wherein the output means comprises; comparison means for comparing the control value with a first reference value and a second reference value; constant-current driver means for controlling the electrical current to have a constant value corresponding to the control value if the control value is in the first range less than the first reference value; frequency-modulation driver means for controlling the electrical current to have pulses at a frequency corresponding to the control value if the control value is in the second range between the first and second reference values; and
,pulse-width-modulation driver means for controlling the electrical current to have pulses having widths corresponding to the control value if the control value in the third range wherein the control values exceed the second reference value.
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41. A display comprising:
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arrayed illumination means for emitting light; and
,driver means for controlling the illumination means, the driver means comprising; input means for receiving control values specifying desired intensities of light to be emitted by the solid-state illumination sources, wherein higher control values represent higher intensities of light; output means for controlling electrical currents in the illumination means, the output means configured to drive the illumination means in a mode determined based on the control values, the input means configured to drive the illumination means having control values in a first range in only a first mode without alternating or combining with any other mode, to drive the illumination means having control values in a second range in only a second mode without alternating or combining with any other mode, and to drive the illumination means having control values in a third range in only a third mode without alternating or combining with any other mode, wherein the output means comprises; constant-current driver means for controlling the electrical current of each of the illumination means having a control value within the first range to have a constant value corresponding to the control value; frequency-modulation driver means for controlling the electrical current of each of the illumination means having a control value within the second range greater than the first range to have pulses at a frequency corresponding to the control value; and
,pulse-width-modulation driver means for controlling the electrical current of each of the illumination means having a control value within the third range greater than the second range to have pulses having widths corresponding to the control value.
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Specification