Photo Sensor Signal Distortion in OLED Displays
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Solution Overview
Problem
The interference from signal lines in organic light emitting displays causes distortion in the output signals from photo sensors, leading to variations between measured values and actual brightness, which deteriorates the yield and quality of the displays.
Innovation Solution
A photo sensor design featuring a sensing unit with a first photo diode, a capacitor, and a switch on a transparent substrate, where the switch's switching error is minimized to reduce interference, and an additional compensating unit with a second photo diode and capacitor to correct voltage changes caused by external noise, ensuring accurate brightness control signals are generated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If signal lines are formed in the outline of the organic light emitting display to enable photo sensor operation, then the photo sensor can function to control brightness, but the output signals from the photo sensor are distorted by interference from different signal lines
Solution Approach 1:
The patent extracts the harmful signal lines from the photo sensor's operational area by forming them in the outline region of the display rather than within the sensing area. This spatial separation removes the interference source from the measurement zone, allowing the photo sensor to function reliably while maintaining measurement precision.
Solution Approach 2:
The patent introduces a compensating unit that acts as an intermediary to detect and compensate for voltage changes caused by noise from signal lines. This compensating unit measures the interference and generates compensation signals that cancel out the distortion, thereby preserving both the functionality and measurement accuracy of the photo sensor.
2Ease of operation
If the photo sensor is placed in the outline of the display to sense ambient light, then brightness control is achieved, but variations between measured values and actual brightness occur due to signal distortion
Solution Approach 1:
The patent implements a feedback mechanism where the compensating unit continuously monitors the output signals from the photo sensor and detects voltage changes caused by noise. The system uses this feedback information to generate compensation signals that are applied to correct the distorted measurements, ensuring accurate brightness control while maintaining ease of operation.
3Productivity
If multiple signal lines are arranged in the display outline to support pixel operation, then the display can function properly, but the photo sensor output signals are interfered with by these signal lines
Solution Approach 1:
The patent segments the display structure into distinct functional zones: the pixel array area for display functionality and the outline area for signal line placement. This spatial segmentation allows multiple signal lines to support pixel operation while being positioned away from the photo sensor's sensing area, thereby maintaining both display productivity and signal output quality.
Solution Approach 2:
The compensating unit serves as an intermediary that detects voltage changes caused by interference from the signal lines and generates compensation signals. This intermediary mechanism protects the photo sensor output quality while allowing the signal lines to remain in place for proper display functionality.
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 design reduces switching errors and noise interference, resulting in more accurate measured values and improved yield and quality of organic light emitting displays by minimizing deviations in brightness control.
Implementation Method 1
a first photo diode receiving a first driving power source to generate an optical current wherein a magnitude of the optical current is controlled in response to the brightness of the ambient light
Data Source
AI summary
A photo sensor capable of reducing the distortion of signals output from the photo sensor to output a correct measured value and an organic light emitting display using the same. The organic light emitting display includes a pixel unit formed on a transparent substrate to display an image in response to scan signals and data signals, a scan driver generating the scan signals to transmit the scan signals to the pixel unit, a data driver generating the data signals to transmit the data signals to the pixel unit, and a photo sensor including a sensing unit sensing brightness of ambient light to output a sensing signal and a control unit for receiving the sensing signal to output a brightness control signal for controlling brightness of the image. The sensing unit disposed in a predetermined region of the transparent substrate and includes a first photo diode receiving a first driving power source to generate optical current so that a magnitude of the optical current is controlled in response to the brightness of the ambient light, a first capacitor for storing the optical current, and a first switch coupled between the first driving power source and the first photo diode to perform a switching operation.