LED Driver Serial-to-Parallel Conversion for Refresh Rate
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Solution Overview
Problem
Conventional LED drivers face limitations in refresh rate due to serial input of bits and have high complexity and cost associated with pulse width control, which affects the luminance and efficiency of light emitting units.
Innovation Solution
A light emitting diode (LED) driver comprising a serial-to-parallel conversion unit, a counting unit, and a data buffer unit that converts M-bit gray codes into N-bit signals, allowing for reduced waiting time and increased refresh rate while maintaining low interference and cost by using a geometric sequence output control signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If bits are serially input to the serial-to-parallel conversion unit, then the device complexity is reduced, but the refresh rate of driving current signals is limited by the bit input rate
Solution Approach 1:
The patent applies preliminary action by pre-storing M-bit gray codes in the data buffer unit before they are needed for driving light emitting units. This allows the system to maintain a higher refresh rate because the gray codes are already prepared in the buffer, eliminating the bottleneck where the serial-to-parallel conversion unit must wait for bit input completion before generating driving signals.
2Measurement precision
If pulse width control is used to control the luminance of light emitting units, then the luminance control precision is improved, but the device complexity and cost increase
Solution Approach 1:
The patent extracts the luminance control function from complex pulse width modulation control and simplifies it by directly using gray code values to determine driving current levels. Instead of controlling pulse widths to achieve luminance control, the system directly maps gray codes to current levels, thereby reducing device complexity while maintaining control precision.
3Device complexity
If the data buffer unit stores only sixteen bits, then the device complexity is reduced, but the time period between adjacent falling edges must be sufficient to serially input sixteen bits, limiting the refresh rate
Solution Approach 1:
The data buffer unit pre-stores M-bit gray codes before they are needed for driving light emitting units. This preliminary storage eliminates the waiting time that would otherwise be required for serial bit input completion, allowing the system to operate at higher refresh rates without increasing device complexity.
Data Source
AI summary
A light emitting diode driver includes: a serial-to-parallel conversion unit converting, based on a reference clock signal, a serial input signal carrying a number (N) of M-bit gray codes into a parallel input signal carrying the M-bit gray codes; a counting unit counting an output control signal to output a counting value; a data buffer unit storing, based on a latch signal, the M-bit gray codes carried by the parallel input signal, and outputting, based on the counting value and the M-bit gray codes, an N-bit signal consisting of N bits, each of which is an ith one of M bits of a respective M-bit gray code, where i is associated with the counting value; and an output unit generating a number (N) of driving current signals based on at least the N-bit signal.