Ring Oscillator Temperature Sensor for Display Panel
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Solution Overview
Problem
Existing temperature sensors outside display panels lack accuracy in monitoring internal temperatures, leading to potential damage from extreme temperatures due to low measurement precision.
Innovation Solution
A temperature sensor integrated into the display panel using a ring oscillator composed of n levels of phase inverters, each with a first and second TFT connected in series, where the second TFT is in a normally-on state and has lower mobility than the first TFT, allowing for accurate temperature measurement by detecting frequency changes in oscillating waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a temperature sensor is disposed outside the display panel, then the display panel can be protected from extreme temperatures, but the measurement precision of the temperature sensor deteriorates
Solution Approach 1:
The patent merges the temperature sensor with the display panel by integrating the ring oscillator circuit directly into the display panel's TFT structure. The sensor shares the same substrate and TFT components as the display panel, eliminating the gap between the sensor and the protected object. This integration ensures that the temperature sensor measures the actual temperature of the display panel accurately while maintaining continuous protection capability.
2Measurement precision
If a ring oscillator with multiple phase inverters is used, then the temperature measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent makes the TFT components serve multiple functions: they act as both the display panel's switching elements and the temperature sensor's active components. The ring oscillator's phase inverters utilize the display panel's existing TFT structure, allowing the same hardware to perform both display control and temperature sensing functions. This multi-functionality reduces device complexity while maintaining measurement precision.
Solution Approach 2:
The patent changes the operational parameters of the TFTs by configuring them in a ring oscillator topology with specific mobility relationships (first TFT mobility greater than second TFT mobility). This parameter configuration enables the circuit to generate oscillations whose frequency varies with temperature. The oscillation frequency serves as the temperature indicator, achieving precise measurement without complex additional circuitry.
3Stability of the object's composition
If the second TFT is configured in a normally-on state, then the stability of the ring oscillator is improved, but the power consumption increases
Solution Approach 1:
The patent applies different operational states to different TFTs within the ring oscillator: the second TFT is configured in a normally-on state while the first TFT has higher mobility and can be dynamically controlled. This local differentiation of operational characteristics allows the circuit to maintain stable oscillations (due to the always-on second TFT providing continuous conduction path) while managing power consumption through the controllable first TFT. The mobility difference between the two TFTs is key to achieving both stability and power efficiency.
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
The integrated temperature sensor enhances measurement accuracy by reflecting temperature changes through oscillating frequency, enabling timely adjustments to prevent display panel damage from extreme temperatures.
Implementation Method 1
accurate temperature measurement by detecting frequency changes in oscillating waves
Data Source
AI summary
The present disclosure discloses a temperature sensor, a display panel, and a display apparatus, in the field of sensors. The temperature sensor includes a ring oscillator consisting of n levels of phase inverters, where n is an odd number greater than or equal to 1. Each level of phase inverter includes a first thin film transistor (TFT) and a second TFT that are connected in series. An on/off state of the second TFT is configured to be in a normally-on state, an on/off state of the first TFT is configured to be determined by a signal input to the phase inverter, and mobility of an active layer material of the first TFT is greater than mobility of an active layer material of the second TFT.