Photo Sensor Temperature Compensation for Flat Panel Displays
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Solution Overview
Problem
Existing photo sensors in flat panel display devices are sensitive to temperature changes, causing electrical currents generated by light to be overshadowed by temperature-induced currents, which affects the accuracy of ambient light sensing and subsequent image brightness control.
Innovation Solution
A photo sensor system comprising a photo sensing unit, a temperature compensating unit with a dark diode, and a buffer unit that generates a light sensing signal by subtracting temperature-induced currents from light-induced currents, ensuring the signal reflects ambient light changes only.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a photodiode is used to sense ambient light, then light sensing capability is achieved, but temperature-induced electrical currents overshadow light-induced currents at high temperatures
Solution Approach 1:
The patent divides the photo sensor into separate functional units: a photo sensing unit for detecting light, a temperature compensating unit for measuring temperature effects, and a buffer unit for signal processing. This segmentation allows independent measurement and compensation of temperature interference, resolving the contradiction between light sensing accuracy and temperature interference.
Solution Approach 2:
The patent introduces a dark diode as an intermediary element in the temperature compensating unit. This dark diode is identical to the photodiode but blocked from light, serving as a mediator to measure only temperature-induced currents. By comparing signals from the photodiode and dark diode, the system isolates light-induced currents from temperature interference.
2Measurement precision
If temperature compensation is implemented using a dark diode, then light sensing accuracy is improved, but device complexity increases
Solution Approach 1:
The patent combines the photo sensing unit and temperature compensating unit into a single integrated photo sensor device with shared structural elements and processing circuits. By merging these functions into one unit rather than separate devices, the patent reduces overall system complexity while maintaining measurement precision through the dark diode compensation mechanism.
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 solution effectively isolates and compensates for temperature-induced electrical currents, allowing for accurate ambient light sensing and improved image brightness control, reducing power consumption and enhancing user visibility across varying light conditions.
Implementation Method 1
a photodiode, which is sensitive to the temperature. Therefore, when the ambient temperature rises to a predetermined degree, an electrical current generated by temperature becomes significantly larger than an electrical current generated by light in the photodiode
Implementation Method 2
a temperature compensating unit including a dark diode generating a third electrical current having the same magnitude as the second electrical current, corresponding to ambient temperature due to block of light to be incident
Data Source
AI summary
A photo sensor that is capable of generating a photo sensing signal corresponding only to ambient light by comprehending changes in electrical current depending on the change of temperature and compensating for the electrical current according the change of temperature and a flat panel display device using the photo sensor, and the photo sensor including a photo sensing unit generating a first current corresponding to an ambient light and a second current corresponding to an ambient temperature; a temperature compensating unit including a dark diode generating a third current having a same magnitude as the second current, corresponding to the ambient temperature due to block of light to be incident; and a buffer unit outputting a light sensing signal corresponding to current having the same magnitude as the first current by subtracting the third current generated in the temperature compensating unit from the second current generated in the photo sensing unit.