Display Pixel Driving Scheme for NIR Sensor Luminance Stability
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Solution Overview
Problem
The operation of an NIR proximity sensor in display devices causes leakage currents in transistors, leading to luminance deviation in the display due to light radiation, affecting image quality.
Innovation Solution
A display device with a gate driver including scan drivers and a light emission control signal driver, where each pixel has a driving transistor and a compensation transistor to control light-emitting elements, and a bias transistor to apply different bias voltages during NIR sensor operation and non-operation, along with a compensation mechanism for threshold voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an NIR proximity sensor operates to detect proximity of an object, then proximity detection function is improved, but luminance deviation occurs in the display due to leakage current in transistors
Solution Approach 1:
The patent applies preliminary action by turning on the compensation transistor before the sampling section to pre-compensate for threshold voltage shifts caused by NIR light exposure. This提前 compensation ensures that when the NIR proximity sensor operates, the transistor threshold voltage has already been adjusted, preventing luminance deviation before it occurs during normal display operation.
Solution Approach 2:
The patent implements feedback by using the compensation transistor to detect and correct threshold voltage changes in the driving transistor caused by NIR light exposure. The compensation mechanism continuously monitors and adjusts for voltage shifts, creating a closed-loop system that maintains luminance uniformity while the NIR sensor operates.
2Illumination intensity
If a compensation transistor is added to compensate for threshold voltage, then luminance uniformity is improved, but device complexity increases
Solution Approach 1:
The patent merges the compensation function into the existing pixel circuit by integrating the compensation transistor with the driving transistor and light-emitting element. This combination approach allows threshold voltage compensation to be implemented within the standard pixel structure, minimizing additional complexity while achieving luminance uniformity improvement.
3Stability of the object's composition
If different bias voltages are applied during NIR sensor operation, then luminance stability is improved, but control complexity increases
Solution Approach 1:
The patent applies periodic action by applying different bias voltages to the bias transistor depending on whether the NIR sensor is operating or not. During NIR sensor operation, a first bias voltage is applied, and during normal operation, a second bias voltage is applied. This periodic switching of bias conditions stabilizes luminance while managing control complexity through straightforward voltage switching.
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
Prevents luminance changes by compensating for transistor threshold voltage shifts caused by NIR proximity sensor operation, maintaining consistent image brightness.
Implementation Method 1
when the NIR proximity sensor operates, light from an NIR light source is radiated to transistors of each pixel, resulting in leakage current of the transistors
Data Source
AI summary
Provided are a display device and a method of driving the same that prevent an operation of an NIR proximity sensor from affecting luminance change, and the display device includes a display panel including a plurality of pixels, and a gate driver including first to fourth scan drivers and a light emission control signal driver, wherein each of the pixels includes a driving transistor configured to control a driving current of a light-emitting element, and a compensation transistor configured to compensate for a threshold voltage of the driving transistor, each of the pixels is sequentially driven in a first bias section, an initialization section, a sampling section, a second bias section, and a light emission section during one frame, and a first scan signal is output so that the compensation transistor is turned on before the sampling section.