LED Driving Apparatus with Parallel Capacitors for Stable Color Projection
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Solution Overview
Problem
Conventional projectors using field sequential color systems face challenges in efficiently driving light-emitting elements of different rated currents, leading to potential delays and instability in color image projection due to mechanical synchronization requirements and power supply fluctuations.
Innovation Solution
A light-emitting element driving apparatus that includes capacitors connected in parallel with each light-emitting element, a direct-current power source, a selection controlling section for choosing elements successively, and a power supplying section that adjusts current output, along with a connection controlling section for timing the capacitor connections, ensuring stable and synchronized operation of LEDs with different rated currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If light-emitting elements of different rated currents are driven in time sharing manner without individual capacitors, then device complexity is reduced, but response speed and stability deteriorate due to power supply fluctuations and switching delays
Solution Approach 1:
The power supply system is segmented into separate capacitor units for each light-emitting element. Each capacitor (C1, C2, C3) is independently connected to its corresponding LED through switching elements, allowing independent energy storage and release. This segmentation enables each LED to receive stable power independently during switching transitions, improving response speed without requiring a completely complex centralized power system.
Solution Approach 2:
Capacitors are pre-charged during the off-period of each light-emitting element and then discharged during the on-period. The connection controlling section pre-establishes the capacitor connection timing to coincide with the switching moment, ensuring immediate power availability when the LED is activated. This preliminary charging action eliminates power supply delays during switching.
2Ease of manufacture
If light-emitting elements of different rated currents are driven without individual capacitors, then manufacturing cost is reduced, but reliability and stability worsen due to power supply fluctuations during switching
Solution Approach 1:
The power supply system is segmented into separate capacitor units for each light-emitting element. Each capacitor (C1, C2, C3) is independently connected to its corresponding LED through switching elements, allowing independent energy storage and release. This segmentation enables each LED to receive stable power independently during switching transitions, improving response speed without requiring a completely complex centralized power system.
Solution Approach 2:
Capacitors are connected in parallel with each light-emitting element to provide beforehand cushioning against power supply fluctuations. During switching transitions, the capacitors act as energy buffers that smooth out voltage variations and current spikes, ensuring stable operation of each LED regardless of switching events in other channels. This cushioning effect enhances reliability without requiring complex active regulation circuits.
3Reliability
If capacitors are connected in parallel with each light-emitting element with precise timing control, then stability and response speed are improved, but device complexity increases
Solution Approach 1:
The switching elements (transistors or MOSFETs) serve multiple functions: they act as on/off switches for the light-emitting elements, as timing control elements for capacitor connection/disconnection, and as current regulation devices. The connection controlling section uses the same switching signals to coordinate both the LED activation and capacitor connection, eliminating the need for separate control circuits and reducing overall system complexity while maintaining precise timing control.
Solution Approach 2:
The control functions for the light-emitting elements and their associated capacitors are merged into a single connection controlling section. The switching elements that control LED activation are the same elements that control capacitor connection and disconnection. This merging of control functions reduces the number of independent control circuits needed, simplifying the overall device architecture while ensuring stable and synchronized operation of all components.
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 solution enables stable and rapid switching of LEDs, maintaining appropriate luminance and preventing simultaneous activation, thereby improving response speed and ensuring consistent color image projection without the need for mechanical color wheels.
Implementation Method 1
capacitors provided each to be connected in parallel with an appropriate light emitting element among the plural light emitting elements
Data Source
AI summary
A light-emitting element driving apparatus, method and projector are provided, in which a common power supplying section drives plural light emitting elements of different rated current in a time sharing driving manner whereby the light emitting elements emit light stably.The light-emitting element driving apparatus comprises a direct-current power source 12 for supplying direct current I-in, a light-emitting element selection controlling section 11 for selecting light emitting elements 10R, 10G, 10B of different rated current, successively, a power supplying section 13 for changing the direct current supplied from the direct-current power source 12 to predetermined output current and supplying the output current I-out to the light emitting element selected by the light-emitting element selection controlling section 11, and a connection controlling section 15 for connecting one subsidiary capacitor among subsidiary capacitors 14R, 14G, 14B in parallel with one appropriate light emitting element out of the light emitting elements 10R, 10G, 10B at a predetermined timing.