Laser Drive Apparatus with Segmented Current Mirror Circuits
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Solution Overview
Problem
Conventional laser drive apparatuses face challenges in responsiveness due to the dependence on video data, leading to unclear images and limitations in supporting high resolution, as the output current of the digital to analog converter changes with video data, affecting the driver's load capacity and response time.
Innovation Solution
A laser drive apparatus is designed with a digital to analog converter featuring multiple current sources and switches, distributing the load capacity through multiple current mirror circuits, ensuring a constant response speed regardless of video data, facilitating color matching and high-resolution imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a single current mirror circuit is used to amplify the output current of the DA converter, then area efficiency is improved, but responsiveness becomes dependent on video data and color matching becomes difficult
Solution Approach 1:
The patent divides the single current mirror circuit into multiple current mirror circuits (first, second, third, and fourth current mirror circuits). Each current mirror circuit processes a portion of the video data and generates a corresponding drive current. This segmentation allows the total drive current to be distributed across multiple parallel paths, reducing the load on each individual circuit and ensuring consistent responsiveness across different video data ranges while maintaining area efficiency through the organized modular structure.
2Illumination intensity
If the output current of the DA converter changes with video data, then brightness control is achieved, but responsiveness decreases significantly when video data is small, becoming a bottleneck for high resolution
Solution Approach 1:
The patent implements a dynamic load distribution mechanism where the video data is divided into multiple ranges (first video data range, second video data range, third video data range), and different current mirror circuits are activated based on the video data value. When video data is small, the first and second current mirror circuits process the data with reduced load, ensuring fast responsiveness. When video data is large, all four current mirror circuits are activated to provide sufficient drive current. This dynamic adaptation maintains high responsiveness across all brightness levels while preserving the brightness control capability.
3Device complexity
If a conventional laser drive apparatus is used, then simplicity is maintained, but the resolution of the image display apparatus is restricted by the responsiveness of the laser drive apparatus
Solution Approach 1:
The patent segments the drive circuit into multiple current mirror circuits that operate in parallel, each handling a specific portion of the video data. This segmentation reduces the processing load on each circuit, enabling faster response times that support higher image resolution. The modular segmented structure maintains relative simplicity while achieving the high-speed performance needed for high-resolution displays.
Solution Approach 2:
The patent employs dynamic range division where video data is adaptively distributed across multiple current mirror circuits based on the data magnitude. This dynamic operation optimizes the responsiveness for different brightness levels, ensuring that even small video data values are processed quickly to maintain high resolution. The dynamic adaptation allows the system to achieve high-resolution performance without excessive complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enables constant response speed, improving color matching and supporting high resolution by distributing the driver load, thereby addressing the limitations of conventional systems.
Implementation Method 1
a digital to analog converter including a plurality of current sources of a number corresponding to a bit number of a digital input code and a plurality of switches of a number corresponding to the number of bits
Implementation Method 2
a driver circuit including a plurality of current mirror circuits that generate a drive current corresponding to each of the output currents based on each of the output currents to drive a laser diode
Implementation Method 3
generates a drive current corresponding to each of the output currents from the plurality of current source sets to drive the laser diode
Data Source
AI summary
A laser drive apparatus is provided with a digital to analog converter including current sources of a number corresponding to a bit number of a digital input code and switches of a number corresponding to the number of bits. The digital input code is converted from input video data, and provided to a DA converter, that generates RGB drive currents for a laser scanning type image display apparatus driven by the laser drive apparatus, and output currents from current sources are weighted in accordance with bits of the digital input code. A ratio of each of the output currents from each of the current sources to a load capacity of a driver having each of current mirror circuits is identical for all bits corresponding to each of the current sources, and the current mirror circuits is configured to distribute load capacity of the driver circuit.