Patent application number | Description | Published |
20080291956 | Driving laser diodes with immunity to temperature changes, aging, and other effects - Various systems and methods are provided to achieve laser power control. In one embodiment, a system is provided that comprises a counter that holds a digital value. An digital-to-analog converter is employed to convert the digital value to an analog current. A data threshold current is generated by a laser driver based upon the analog current. The data threshold current is employed to represent a data value in a data signal employed to drive a laser diode. Also, circuitry is employed to adjust the digital value based upon a comparison between a target threshold current and a feedback current generated from a laser output of the laser diode. | 11-27-2008 |
20090175302 | Method and apparatus for reducing optical signal speckle - An optical signal generator is configured with an associated control system and driver configured to reduce speckle. Speckle reduction occurs by pulsing the drive signal between a first current level and a second current level. These pulses force the optical signal generator to introduce oscillations into the optical signal. The coherence of the emitted light is reduced during the period of oscillations in the optical signal, which reduces speckle. In one embodiment, the pulsing of the drive signal brings the drive signal down to a level near or below threshold, which in turn intermittently turns off the optical signal output. Returning the optical signal to a desired optical output intensity introduces the speckle reducing oscillation. The pulse frequency, and duty cycle is controlled by a duty cycle control signal to modulate overall optical power and adjust amount of despeckle. | 07-09-2009 |
20090256973 | Reducing power dissipation in portable LCOS/LCD/DLP portable projection systems - A projection system with one or more light sources reduced power consumption and optional scanning capability is disclosed. A controller processes image data to generate light source control signals and pixel screen control signals which are coordinated to generate an image. Reductions in power consumption occur by matching the light output from the light source to the brightest pixel(s) in the pixel screen for a particular frame. By setting the light output level to an intensity or duration matched to only the maximum level corresponding to a image frame, power consumption is reduced as compared to an embodiment which sets the light source output to its maximum level or maximum duration. The pixel screen, which may be an LCD screen, sets pixel areas corresponding to the brightest pixels as transparent and other, less bring pixels on the pixel screen are set to appropriate levels of reduced transparency. | 10-15-2009 |
20120133300 | COLOR MIXING AND DESATURATION WITH REDUCED NUMBER OF CONVERTERS - A system is disclosed to automatically establish proper biasing for light sources in a color mixed projection system having multiple light sources which are active at the same time. Responsive to a feedback signal, a single DC-DC converter generates the bias voltage for the light sources. Comparators compare a headroom signal for each light source to a reference value to generate comparator output signals. The comparator output signals are processed by a channel selector and a digital filter/DAC module. The channel selector controls a switch to selectively provide and combine a headroom signal with an output of the digital filter/DAC module to create the feedback signal. By monitoring each headroom value, the bias voltage is adjusted, based on the feedback signal, until every headroom signal reaches the reference value thereby achieving sufficient biasing for every active light source in the color mixed projection system. | 05-31-2012 |
20120306399 | PROJECTOR SYSTEM WITH SINGLE INPUT, MULTIPLE OUTPUT DC-DC CONVERTER - A projector system with a single DC-DC converter having a single inductor is disclosed. A single DC-DC converter receives an input voltage and connects to two or more light sources such that each light source receives the same DC-DC converter output signal. Connected to the opposite terminal of the light source is a current source driver which receives a control signal control the voltage levels that determine which light source is the active or full power light source in the time multiplexed image generation arrangement. The use of a DC-DC converter having a single inductor reduces cost and size of the system while still enabling color mixing such that two or more light sources share the same single output of the DC-DC converter. | 12-06-2012 |
20130070796 | SCALABLE BUCK-BOOST DC-DC CONVERTER - A DC-DC converter is disclosed having an input configured to receive an input signal and an output configured to present an output signal at a different voltage than the input signal. The converter also includes at least one inductor and at least one capacitor. Two or more transistors fingers are provided such that at least one of the two or more transistor fingers comprises two or more switching transistors, each of which has an input, an output, a control input. An activation controller connect to at least one of the two or more switching transistors, the activation controller to configured to control whether the at least one of the two or more switching transistors is active or non-active. Also disclosed is a buck-boost converter with numerous controlled switches that establish the converter in either buck-boost mode, buck mode or boost mode. | 03-21-2013 |
20130147393 | HIGH ACCURACY, HIGH DYNAMIC RANGE LED/LASER DRIVER - A current driver circuit, for driving a light source, that provides high accuracy and reduced power consumption is disclosed. The driver includes a digital to analog converter configured to receive a digital value representing a light intensity and convert the digital value to an analog current signal. A current minor is configured to receive the analog current signal and create a current minor output which is larger than the analog current signal based on a ratio of the current mirror. This results in a modified analog current signal. A light source receives the modified analog current signal, and responsive thereto generate a light signal such that the light signal has an intensity controlled by the digital value. One or more amplifiers are also part of the current driver and configured to increase response time and accuracy. | 06-13-2013 |
20140111114 | Color Mixing and Desaturation with Reduced Number of Converters - A system is disclosed to automatically establish proper biasing for light sources in a color mixed projection system having multiple light sources which are active at the same time. Responsive to a feedback signal, a single DC-DC converter generates the bias voltage for the light sources. Comparators compare a headroom signal for each light source to a reference value to generate comparator output signals. The comparator output signals are processed by a channel selector and a digital filter/DAC module. The channel selector controls a switch to selectively provide and combine a headroom signal with an output of the digital filter/DAC module to create the feedback signal. By monitoring each headroom value, the bias voltage is adjusted, based on the feedback signal, until every headroom signal reaches the reference value thereby achieving sufficient biasing for every active light source in the color mixed projection system. | 04-24-2014 |
20140152272 | AUTOMATIC BUCK/BOOST MODE SELECTION SYSTEM FOR DC-DC CONVERTER - A reconfigurable DC-DC converter including a controller is disclosed which automatically adjusts the mode of operation (buck mode or boost mode) depending on the system requirements and is able to achieve the maximum efficiency and the lowest inductance current. The method of switching between buck and boost mode allows the converter to operate to 100% duty cycle for buck mode and 0% duty cycle for boost mode. This maximizes efficiency since the buck-boost mode of operation is eliminated and improves the stability and reliability of the system. A converter output voltage is processed and compared to a control voltage to generate buck and boost comparator output signals. The buck and boost comparator output signals are provided to control logic, which generates switch control signals, which are provided to the DC-DC converter to establish buck mode, boost mode, or pass-through mode. | 06-05-2014 |