Display Photometric Measurement Using Absolute Position Codes
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Solution Overview
Problem
Existing methods for photometric measurement of electronic displays, such as OLED or MicroLED, face challenges in accurately adjusting pixel control due to variations in photometric and colorimetric parameters caused by production or aging effects, leading to uneven brightness and color distribution.
Innovation Solution
A method using an absolute position code, where a test image and position code are displayed on the display, allowing for precise photometric measurement by transforming camera coordinates into display coordinates, enabling accurate assignment of lighting parameters and reducing errors from camera distortions and positioning inaccuracies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a camera is used to capture the display for photometric measurement, then measurement capability is provided, but camera distortions and positioning inaccuracies introduce errors
Solution Approach 1:
The patent introduces an intermediary coordinate transformation system that mediates between the camera coordinate system and the display coordinate system. By determining the spatial relationship between these two coordinate systems through position codes and transformation matrices, the system eliminates direct reliance on the camera's intrinsic distortion properties, thereby compensating for camera distortions and positioning inaccuracies without requiring complex calibration of the camera itself.
Solution Approach 2:
The patent replaces direct mechanical/physical measurement methods with an optical-coordinate transformation approach. Instead of relying on the camera's physical positioning and intrinsic calibration (mechanical system), the system uses mathematical coordinate transformations to map camera coordinates to display coordinates, substituting physical measurement accuracy with computational geometric accuracy that is less sensitive to physical imperfections.
2Measurement precision
If complex measurement equipment is used to improve measurement accuracy, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent creates a virtual copy of the display coordinate system through mathematical transformation rather than using a physically complex measurement system. By representing the display's coordinate system as a mathematical model that can be transformed from camera coordinates, the system achieves high measurement precision through computation rather than through complex physical instrumentation, thereby reducing device complexity.
Solution Approach 2:
The patent changes the measurement approach from direct physical measurement parameters (requiring complex equipment) to coordinate transformation parameters (mathematical relationships). By determining the spatial relationship between camera and display coordinate systems through position codes and transformation matrices, the system achieves high precision through parameter transformation rather than through complex measurement hardware.
3Measurement precision
If the entire display is measured at once, then measurement completeness is achieved, but measurement time and equipment requirements increase
Solution Approach 1:
The patent segments the measurement process by using position codes that are distributed across the display to provide reference points for coordinate transformation. Instead of requiring the camera to capture the entire display at once with high precision, the system uses these distributed position code references to mathematically transform and align measurement data from different regions, enabling complete measurement through multiple shorter measurements rather than requiring a single comprehensive capture.
Data Source
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Figure 2C~2D
AI summary
The invention relates to a method for the photometric measurement of a display (10) with display elements (11, 12) arranged in a display coordinate system (K). The display (10) is controlled in at least one first measurement position (MP1) of the display (10) relative to the measuring camera (2) to display at least one test image (100) and is captured at least partially by a measuring camera (2) with sensor pixels (21) arranged in a camera coordinate system (K'). The display (10) is further controlled to display at least one absolute position code (P4), which is configured to determine the position of at least one display element (11, 12) relative to the display coordinate system (K), and is captured at least partially by the measuring camera (2) during this process.Based on at least one absolute position code (P4), a coordinate transformation is determined for transforming coordinates of the camera coordinate system (K') into coordinates of the display coordinate system (K). For at least one display element (11, 12), at least one photometric parameter is determined by converting the measured values acquired by the sensor pixels (21) during the display of the at least one test image (100) into the display coordinate system (K) using the coordinate transformation. Furthermore, the invention relates to a method for controlling a display (10) and a device for the photometric measurement of a display (10).