Chihao Xu

50.3: A Video‐Capable Algorithm for Local Dimming RGB Backlight

We present an algorithm for efficient calculation of local dimming RGB LED-Backlight to save power consumption. The algorithm was implemented in hardware to support Full-HD resolution at a low HW- cost. It showed clipping-free and video-capable results.

A New Addressing Scheme for PM OLED Display

This paper presents a new addressing scheme for PM OLED displays by using Consecutive Multiline Addressing, which decomposes the image information into multiline matrices and efficiently reduces the driving current amplitude of OLED pixels. As a result, the lifetime and/or resolution of PM OLED displays can substantially be extended.

Multiline addressing by network flow

We consider an optimization problem arising in the design of controllers for OLED displays. Our objective is to minimize amplitude of the electrical current through the diodes which has a direct impact on the lifetime of such a display. Modeling the problem in mathematical terms yields a class of network flow problems where we group the arcs and pay in each group only for the arc carrying the maximum flow. We develop (fully) combinatorial approximation heuristics suitable for being implemented in the hardware of a control device that drives an OLED display.

P‐56: Application of the SSC Local Dimming Algorithm for an Edge‐Lit TV

The SSC local dimming algorithm, originally developed for direct-lit LCD using a local optimization approach, has been modified and extended. A global optimization approach was used to cover the wide light spread over the display due to the edge-lit. The existing six LED-strings of a commercial available edge-lit TV are controlled by our own driver circuit, while the PWM values for each LED are delivered by the SSC algorithm. The display parameters were measured and used in the SSC processing. An average power saving of up to 51% of the TV power consumption standard video has been achieved, while the visual quality is proven and the brightness is nearly the same as that of the original undimmed TV. with a higher number of LED strings a power saving significantly higher than 50% is to be expected.

46.2: System Architecture and FPGA-Implementation of the SSC Local Dimming Processor for an Edge-Lit Serial TV

We present an efficient hardware implementation of our local dimming processor which consists of a preprocessor (Condenser), the Sorted Sector Covering (SSC) algorithm and a postprocessor (Pixel Compensation) in a low-cost FPGA. The system runs in a typical 40″ Full-HD TV set with edge- LED. An equivalent visual quality like the undimmed version has been achieved, while the power consumption for the BLU with four LED units is reduced by 21%. In case of tolerating limited clipping artifacts, the power consumption can even be reduced by 46%.

Multiline Addressing by Network Flow

We consider an optimization problem arising in the design of controllers for OLED displays. Our objective is to minimize amplitude of the electrical current through the diodes which has a direct impact on the lifetime of such a display. Modeling the problem in mathematical terms yields a class of network flow problems where we group the arcs and pay in each group only for the arc carrying the maximum flow. We develop (fully) combinatorial approximation heuristics suitable for being implemented in the hardware of a control device that drives an OLED display.

Consecutive Multiline Addressing: A Scheme for Addressing PMOLEDs

— Consecutive multiline addressing (CMLA) has been developed to increase a PMOLED displays lifetime, resolution, and power efficiency. Mathematically, it decomposes an image matrix into a set of multiline matrices and a residual single-line matrix. The decomposition is lossless and implemented by a combinatorial algorithm allowing small chip size for the logic and high processing speed, e.g., for video applications. The additional memory needed for CMLA is just a fraction of the graphic data memory (GDRAM). The printed-circuit-board (PCB) prototype with a field programmable gate array (FPGA) proves that the CMLA produces images of the same visual quality as the conventional single-line addressing (SLA), while the power efficiency is substantially higher.

Design and characterization of STI compatible high-voltage NMOS and PMOS devices in standard CMOS process

This paper presents the design of High-Voltage NMOS and PMOS devices with STI (shallow trench isolation) technology fully compatible with a standard 0.25 mum/5 V CMOS process technology. Breakdown voltages of 35 V for n-channel with a specific on resistance of 1.96 mOmega.cm2 and -45 V for p-channel with a specific on-resistance of 8.73 mOmega.cm2 have been achieved without any modification of existing standard CMOS process.

A new local dimming algorithm based on the simplex method

A recently arising important feature of mobile computing is power efficiency. Economical power management allows to increase the battery lifetime of tablets, mobile phones and so on. As the display of those devices yields the largest part of power consumption in the near future, it is necessary to reduce the power consumption of them. This can be achieved by dimming, especially by local dimming, i.e reducing the backlight of the display while the necessary brightness in all pixels has to be satisfied. Mathematically, this problem is modeled in this paper as a linear program, which will be solved by a tuned up version of the popular simplex algorithm. While there are other methods as the sorted sector covering algorithm or the General Dimming Algorithm for local dimming, they do not allow to integrate a-priori information for the solution. For example, restricting the maximum difference of the power of two neighboring LEDs is not possible due to the calculation, while it is a natural demand from the physical point of view. Furthermore, the simplex method allows to integrate smoothness conditions on the solution depending on the second order derivative. Additionally, a problem adapted pivot rule is proposed and the warmstart-strategy of the simplex is elaborated to speed up the proposed algorithm during watching movies. Furthermore, the new method does not only minimize the power consumption, it also aligns the backlight to the image leading to perfectly dimmed images. Numerical examples comparing the different methods substantiate the many advantages of the new method.

P-208L: Late-News Poster: LSF Correlator — An Amending Module for SSC Local Dimming Algorithm to Increase the Static Contrast of Edge-Lit LCDs

A contrast enhancement extension named as LSF Correlator has been amended to our Sorted Sector Covering (SSC) algorithm for the calculation of the LED duty-cycles of a local dimming LED backlight. As a result, the static contrast of the display is significantly increased. The LSF Correlator has been proved on an 8″ WVGA prototype with an edge-lit backlight.