RGB illuminator with calibration via single detector servo

Details RGB illuminator with calibration via single detector servo RGB illuminator with calibration via single detector servo

1999-05-17

2003-10-14

Razavi, Michael (Department: 2672)

Computer graphics processing and selective visual display system

Computer graphics processing

Attributes

C345S084000

Reexamination Certificate

active

06633301

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates generally to methods and arrangements for calibrating illumination assemblies to obtain desired white-point, color balance and/or intensity. More specifically, the invention relates to using electronic storage devices and/or photodetectors and electronic circuitry to vary the current supplied to illumination devices such as light-emitting diodes, thus providing a calibrated light source for display applications.
In micro-display applications utilizing tri-color RGB (red, green and blue) light-emitting diode (LED) assemblies to illuminate a display panel, LED part-to-part illumination variation results in inconsistent brightness, white-point and color balance. Every LED's illumination output as a function of current is different, and each LED's illumination response to current across its entire current-controlled operating range may be non-linear. Manufacturing LEDs within tighter tolerances and more closely matching the three LED colors in a single assembly, thereby providing a more stable white-point and/or color balance, would be unnecessarily expensive, and would nevertheless provide unsatisfactory results.
Referring initially to
FIG. 1
, a prior art display system
100
providing a partial solution to the above-described problem will be described. Display system
100
includes a light modulating display
102
, an illumination device
104
, which provides the light source for display
102
, and an adjustable current source
106
electrically connected to illumination device
104
. Adjustable current source
106
is manually adjusted during manufacturing in order to cause illumination device
104
to provide calibrated light. The adjustment takes place by comparing the illumination output of illumination device
104
to a reference intensity and adjusting current source
106
until the illumination output of illumination device
104
matches the reference intensity. If illumination device
104
contains more than one light source, the process is repeated for each light source.
Display system
100
further includes a controller
108
and a display information input
110
. During operation of display system
100
, controller
108
receives display information via input
110
and determines the current to be supplied to illumination device
104
. The setting made during manufacturing to adjustable current source
106
causes the current to vary proportionally to the setting, thereby providing partially calibrated light. Because the adjustment made to adjustable current source
106
during manufacturing calibrates the illumination output of illumination device
104
for only a single intensity, this system does not correct the non-linear illumination response to current of illumination device
104
across the device's entire current-controlled operating range.
Display system
100
includes the additional limitation that adjustable current source
106
must be manually set during manufacturing. Having to manually calibrate the current source increases the cost of producing such a device.
FIG. 2
illustrates a display system that overcomes this particular limitation.
Referring now to
FIG. 2
, a second prior art display system
120
will be described using like reference numbers for like components. Display system
120
includes a voltage source
122
and an adjustable resistor
124
. Adjustable resistor
124
may be a laser trim resistor that is capable of being adjusted during manufacturing using an automated process to provide the desired intensity for a specific voltage. While this method overcomes one limitation of display system
100
by allowing the calibration to be accomplished by automated means during manufacturing, display system
120
similarly fails to correct the non-linear illumination response to current of illumination device
104
across its entire current-controlled operating range. Further, neither display system
100
nor display system
120
is capable of correcting illumination device variations that occur after manufacturing, such as illumination device aging.
The present invention discloses arrangements and methods for calibrating illumination devices to reduce both pre- and post-manufacturing variations, including non-linear illumination output as a function of current across the current-controlled operating range and illumination device aging.
SUMMARY OF THE INVENTION
As will be described in more detail hereinafter, a display system including an arrangement for calibrating an input-driven illumination device is disclosed. The display system includes a spatial light modulator divided into an array of individually controllable pixels and an input-driven illumination device which is adapted to receive a variable input and which is configured to direct light of variable intensity onto the modulator, depending on the input. The display system further includes an arrangement adapted for connection with the illumination device for providing to the illumination device a specific input for a desired intensity level of the light, the specific input being provided from calibration information particular to the illumination device. The arrangement further includes a memory device for storing the calibration information.
A method of operating a display system as described above includes determining calibration information for an input driven illumination device which is adapted to receive a variable input and which is configured to direct light of variable intensity onto a light modulator, depending on the input. The method further includes storing the calibration information in a memory device and establishing a specific input for a desired intensity level of the light from the calibration information. The method further includes providing the specific input to the illumination device, and directing the light of the desired intensity level onto the light modulator.
As will be described in more detail hereinafter, an illumination assembly, including calibration information is also disclosed. The illumination assembly includes an input-driven illumination device which is adapted to receive a variable input and which is configured to produce light of variable intensity depending on the input. The illumination assembly further includes an arrangement including a memory device for storing calibration information and generating from the information a specific input for causing the illumination device to produce light of a particular intensity. The arrangement is adapted to be connected with the illumination device such that the latter receives the specific input.
In another embodiment of a display system, the display system includes a light modulator and an input-driven illumination device which has been pre-calibrated to provide light of a given intensity in response to a particular input and which is configured to direct the light onto the modulator. The display system further includes an electronic storage arrangement for storing a value which corresponds to the particular input, and an arrangement responsive to the value in the electronic storage means for generating the particular input and using it to drive the illumination device in a way which provides light of the given intensity.
A method of operating a display system as described above includes determining a particular value for controlling the input to an input-driven illumination device and electronically storing the particular value. The method further includes driving the illumination device in response to the particular value in a way which produces light of a desired intensity level, and directing the light of the desired intensity level onto a light modulator.
In a preferred embodiment, the display system includes a light modulator divided into an array of individually controllable pixels and an input-driven illumination device which is adapted to receive a variable input and which is configured to direct light of variable intensity onto the modulator, depending on the input. The display system further includes a calibrating arr

Affiliated with

Also associated with

Rating

RGB illuminator with calibration via single detector servo does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with RGB illuminator with calibration via single detector servo, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and RGB illuminator with calibration via single detector servo will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3152131