Phosphor Wheel Synchronization for Flicker-Free Projector Startup
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Solution Overview
Problem
Projection devices using semiconductor light-emitting elements often experience flickering due to unsynchronized phosphor wheel rotation and light emission, leading to delayed startup and loss of immediate projection capability.
Innovation Solution
A projection device with a controller that initiates phosphor wheel rotation and sets the turn-on timing for the semiconductor light-emitting element's power supply based on predetermined conditions, ensuring synchronization and preventing flickering by maintaining a driving current at zero during initialization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the turn-on pulse is output immediately after starting the rotation of the phosphor wheel, then the projection operation can start quickly, but the phosphor wheel and light emission are not correctly synchronized causing flickering
Solution Approach 1:
The controller outputs the turn-on pulse for the semiconductor light-emitting element before the phosphor wheel has completed its acceleration to stable rotation speed. This preliminary action allows the light emission to be ready immediately when the phosphor wheel reaches synchronization point, eliminating startup delay while ensuring proper synchronization timing.
Solution Approach 2:
The system uses a detection pulse from a marker sensor that detects a marker on the phosphor wheel to provide feedback about the wheel's rotational position. The controller adjusts the turn-on pulse timing based on this feedback signal, ensuring that light emission is synchronized with the phosphor wheel's rotation even during acceleration phases.
2Reliability
If the output of the turn-on pulse is delayed by a fixed time from the start of rotation, then flickering is suppressed, but the projection operation start is delayed and immediate projection capability is lost
Solution Approach 1:
Instead of delaying the turn-on pulse until a fixed time after rotation starts, the controller issues the turn-on pulse in advance. This allows the semiconductor light-emitting element to be ready to emit light immediately when the phosphor wheel reaches the correct synchronized position, eliminating the need for fixed-time delays while preventing flickering.
Solution Approach 2:
The system transitions from a static fixed-time delay approach to a dynamic timing approach where the turn-on pulse is issued based on real-time detection of the phosphor wheel's rotational state. The controller dynamically adjusts timing based on the detection pulse, allowing optimal startup performance without synchronization errors.
3Productivity
If the semiconductor light-emitting element emits light before the phosphor wheel is correctly synchronized, then rapid projection startup is achieved, but flickering occurs in the projected content
Solution Approach 1:
The marker sensor provides a detection pulse that serves as feedback about the phosphor wheel's rotational position. The controller uses this feedback to precisely time the light emission, ensuring that when the semiconductor light-emitting element emits light, the phosphor wheel is at the correct synchronized position, thereby preventing flickering while maintaining rapid startup.
Solution Approach 2:
The controller prepares the semiconductor light-emitting element by outputting the turn-on pulse in advance, but the actual light emission only occurs when the detection pulse confirms proper synchronization. This preliminary preparation without premature emission allows rapid response while preventing flickering.
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 allows for rapid startup without flickering, as the power supply to the light-emitting elements is initiated only after synchronization is established, reducing the time from activation to actual projection and maintaining the advantage of immediate projection readiness.
Implementation Method 1
a semiconductor light-emitting element (LD) as a light source
Implementation Method 2
B light, which is emitted from an LD, is radiated onto a phosphor wheel that is coated with a phosphor, and G light obtained from the phosphor is collected and utilized
Data Source
AI summary
A projection device includes a semiconductor light-emitting element, a rotary wheel configured to emit lights of a plurality of colors in a time-division manner by using light which the semiconductor light-emitting element emits, and a controller configured to start, at a time of activating the device, rotation of the rotary wheel and output of a signal, which instructs a turn-on timing, to the semiconductor light-emitting element, in a state in which supply of power to the semiconductor light-emitting element is stopped, and to start, thereafter, the supply of the power to the semiconductor light-emitting element, based on a predetermined condition relating to an activation state.