Projection Apparatus Spoke Period Light Control
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Solution Overview
Problem
Digital-Light-Processing (DLP) projectors using semiconductor light emitting devices face challenges in maintaining consistent light emission efficiency and color balance during the 'spoke period,' leading to variations in image quality due to individual device specificity and drive status variations.
Innovation Solution
A projection apparatus with a light source unit that time-divisionally emits light in multiple colors, a display element forming optical images, a spoke setting unit for timing changes, a light source drive unit for adjusting light emission based on detected light amounts, and a light source controller to adjust color balance during spoke periods to maintain predetermined balances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If semiconductor light emitting devices are used for light source, then light emission efficiency varies between timing immediately after starting light emission and much later timing, but using these devices provides high light emission efficiency overall
Solution Approach 1:
The patent applies preliminary action by measuring the light emission amounts of multiple light emitting devices during the spoke period in advance, storing these measurement results, and then using them for later color balance adjustments. This allows the system to pre-characterize each device's emission properties and compensate for variations during actual operation, resolving the contradiction between high efficiency and consistency.
2Measurement precision
If current control technology such as PID control is used to achieve target current value, then current accuracy is improved, but rise and fall properties vary depending on voltages, temperatures, and individual device specificity
Solution Approach 1:
The patent applies local quality by individually measuring and storing the light emission characteristics of each light emitting device during the spoke period, then using device-specific correction values for color balance adjustments. This localized approach accounts for individual device specificity, voltage variations, and temperature effects, maintaining both control accuracy and adaptability to device variations.
3Ease of manufacture
If mixed-color light measurement is performed in advance, then color balance adjustment is simplified, but actual light emission amount during spoke period may differ from measured amount due to device property variations
Solution Approach 1:
The patent applies feedback by measuring the actual light emission amounts during the spoke period, comparing them with target values, calculating correction values based on the differences, and using these corrections to adjust color balances. This closed-loop feedback mechanism ensures both ease of adjustment and high reliability by continuously adapting to actual device performance.
4Adaptability or versatility
If spoke period is provided for color changing, then color transition is enabled, but continuity of gradations of projected colors is lost causing image quality deterioration
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the light emission amounts of individual light emitting devices during the spoke period based on measured characteristics and calculated correction values. By changing emission parameters (intensity, timing) of each device, the system maintains color transition capability while preserving gradation continuity and image quality.
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
Ensures precise and high-quality image projection with continuous gradations of colors by accurately controlling light emission amounts and timing, compensating for variations in semiconductor light emitting devices.
Implementation Method 1
a light source unit configured to time-divisionally emit light in a plurality of colors by light emission from a plurality of light emitting devices
Data Source
AI summary
A projection apparatus includes a light source unit which time-divisionally emits light in colors by light emission from light emitting devices; a display element using light emitted from the light source unit, displaying images respectively corresponding to the colors of the emitted light, and forming optical images by reflection or transmission light thereof; a projection unit emitting the optical images formed by the display element toward a projection target; a timing setting unit setting a change timing associated with changing each of the colors, and setting spoke periods generated at each change timing; a light source drive unit driving the light source unit, based on the change timings and spoke periods; a detection unit detecting information indicating a light amount of the light for each of the colors emitted from the projection unit during the spoke periods; and a light source controller setting a delay time for light emission timings at the light source unit in the spoke periods by the light source drive unit, based on information obtained by the detection unit.