Laser Scanner Control Device Current Segmentation for Non-Display Area Brightness
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Solution Overview
Problem
Existing laser scanning devices face challenges in reducing the rise time and brightness of non-display areas, leading to potential luminance issues and resolution deterioration during scanning.
Innovation Solution
A control device with two current sources and a controller that adjusts the driving current to 1/n times the threshold current when oscillation starts in non-display areas, and a second current source set to zero or less than 1−1/n times the threshold current, to minimize light emission in these areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the driving current with threshold current value is supplied to the laser device during scanning of non-display area, then the laser device can start oscillation quickly, but the non-display area becomes dimly illuminated
Solution Approach 1:
The driving current is segmented into two independent components: a first driving current from a first current source that provides the threshold current value for quick oscillation startup, and a second driving current from a second current source that can be independently controlled to zero or small values during non-display area scanning. This segmentation allows the threshold current component to remain for fast response while the excess current component is removed to prevent unwanted illumination in non-display areas.
Solution Approach 2:
Different current values are applied for different scanning regions: during display area scanning, both current sources contribute to provide sufficient driving current for image display; during non-display area scanning, the second current source is set to zero or small values while the first current source maintains the threshold current for fast response. This local differentiation of current quality resolves the contradiction between fast startup and preventing unwanted illumination.
2Illumination intensity
If the driving current is not supplied to the laser device during scanning of non-display area, then the non-display area brightness is reduced, but the rise time of the laser device becomes long
Solution Approach 1:
The first current source preliminarily establishes the threshold current value in the laser device before actual image display begins. This preliminary action ensures that when scanning transitions to display areas, the laser device is already near oscillation threshold, enabling extremely fast response without requiring full current buildup from zero. This preliminary current establishment resolves the rise time issue while maintaining the ability to control non-display area brightness.
3Device complexity
If a single current source supplies the threshold current value, then the device structure is simple, but the non-display area becomes dimly illuminated and resolution deteriorates
Solution Approach 1:
The single current source is segmented into two independent current sources: the first current source dedicated to providing the threshold current value for fast response, and the second current source providing the gradation current for image display. This segmentation enables independent optimization of each current component's function, allowing fast rise time and high resolution while managing the increased device complexity through modular design.
Solution Approach 2:
The two current sources work together to achieve multiple functions: the first current source ensures fast oscillation startup and short rise time, the second current source provides precise current control for image gradation and resolution, and their combination enables both display and non-display area optimization. This multi-functionality justifies the increased complexity by delivering superior overall performance.
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 approach shortens the rise time of the laser device while reducing the brightness of non-display areas, improving image clarity and resolution by controlling the driving current effectively.
Implementation Method 1
Laser oscillation begins when the driving current I reaches a threshold current value Ith, and the optical output P in an oscillation region A2 in which the laser device makes the laser oscillation, rapidly increases with increasing driving current I
Implementation Method 2
The optical output P in a spontaneous emission region A1 in which the laser device makes the spontaneous emission (for example, Light Emitting Diode (LED) emission), gradually increases with increasing driving current I
Data Source
AI summary
A control device, which controls a laser scanning display device, includes a laser device, a first current source that generates a first driving current supplied to the laser device, a second current source that generates a second driving current supplied to the laser device, and a controller. The controller controls the first current source to generate the first driving current having a first set current value that is 1/n times a threshold current value at a time when oscillation of the laser device starts, when scanning a non-display area in which no image is displayed, where n is a number greater than 1. The controller controls the second current source to generate the second driving current having a second set current value that is zero or greater and less than 1−1/n times the threshold current value, when scanning the non-display area.