Projector Chart Image Control for Focus and Keystone Correction
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Solution Overview
Problem
Conventional projectors that use chart images for focus and keystone correction often display these images in a size that can be distracting and unclear, as they need to be visible on the screen for measurement, leading to a strange viewer experience and potentially unclear video.
Innovation Solution
An image display apparatus and method that generates and projects chart images in a small size, using a chart image signal generation unit, projection unit, sensor unit, and chart display information supply unit to ensure the chart images are within the viewable range of the sensor, allowing for precise distance measurement without being overtly visible during the video projection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the chart image is displayed in a large size for distance measurement, then the measurement precision is improved, but the video clarity deteriorates and viewers experience discomfort
Solution Approach 1:
The patent applies local quality by making the chart image semi-transparent rather than fully opaque. This allows the chart to be visible enough for the sensor to measure distance accurately, while simultaneously allowing the video content to show through, maintaining video clarity and viewer comfort. The different transparency levels create local quality differentiation between the measurement function and the display function.
Solution Approach 2:
The patent introduces a new dimension of transparency/opacity as a controlling parameter for the chart image. Instead of only adjusting size (2D), the system now controls the chart's visual presence through transparency (adding a perceptual dimension). This allows the chart to occupy the same spatial position without fully blocking the video, resolving the contradiction between measurement visibility and video clarity.
2Object-affected harmful factors
If the chart image is displayed in a small size to avoid distraction, then the video clarity is improved, but the measurement precision deteriorates
Solution Approach 1:
The patent uses local quality by applying semi-transparency to the chart image, which maintains adequate contrast and visibility in the regions where the sensor needs to detect features for measurement, while reducing visual dominance in viewer-critical areas. This localized quality adjustment optimizes both measurement and viewing experience simultaneously.
Solution Approach 2:
By adding the transparency dimension to the chart image properties, the system can now control the chart's visual weight independently of its physical size. This additional degree of freedom allows the chart to remain small enough not to distract viewers while maintaining sufficient visual characteristics for accurate sensor measurement through appropriate transparency levels.
3Object-affected harmful factors
If the chart image is made transparent to maintain video clarity, then the video quality is improved, but the chart image visibility for measurement deteriorates
Solution Approach 1:
The patent implements local quality by applying semi-transparency rather than full transparency to the chart image. This partial transparency maintains video quality by allowing video content to show through, while simultaneously preserving sufficient chart image contrast and feature visibility in the regions where the sensor requires detection for accurate distance measurement.
Solution Approach 2:
The patent introduces transparency as an additional control dimension beyond size and position. By adjusting the transparency parameter to an intermediate value (semi-transparent), the system optimizes the balance between video quality and measurement visibility, allowing both functions to coexist effectively without fully sacrificing either.
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
Enables the display of chart images in an appropriate size, improving the viewer experience by minimizing distractions and ensuring clear video projection, while allowing for accurate focus and keystone correction, even when the projector and screen distance changes.
Implementation Method 1
the phase difference sensor receives the light from this image so that the distance to the screen may be measured based on the phase difference of the chart image obtained by the phase difference sensor
Data Source
AI summary
In a projector, CPU supplies a chart generation circuit with chart display information designating display position and display size of a chart image to be projected on a screen such that it comes within viewable ranges of phase difference sensors. For focus control, CPU sets display position near center of the screen, and designates display size regardless of distance between the projector and screen. For keystone correction, CPU designates display position and display size based on relationship among angular field of view, distance, and viewable ranges of the phase difference sensors. A superimposing circuit generates a video by superimposing a video signal with a chart image signal based on the chart display information. A display device projects the video superimposed by the superimposing circuit on the screen. CPU obtains the distance to the screen based on phase difference between reflection lights obtained by a sensor unit and corrects the video.