Display Device Simultaneous Pixel Sensing Circuit
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Solution Overview
Problem
Existing organic light emitting display devices face challenges in efficiently sensing electrical characteristics of all pixels in a short time without adding a sensing circuit to the drive IC, leading to increased costs and prolonged sensing time.
Innovation Solution
A display device design that senses current flowing through power lines to all pixels simultaneously during a sensing mode, using a resistor and switch to disconnect the resistor during display periods, allowing for pixel data compensation without a dedicated sensing channel in the drive IC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensing circuit including amplifiers, integrators, samples & holders, and ADCs is added to each channel of the drive IC to sense pixel electrical characteristics, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The sensing circuit is extracted from the drive IC and placed externally. The drive IC only needs to output sensing data voltages to pixel circuits, while the external sensing circuit performs the actual electrical characteristic measurement. This separation removes complex sensing components from the drive IC, reducing its complexity while maintaining sensing precision.
Solution Approach 2:
The pixel circuit acts as an intermediary between the drive IC and the external sensing circuit. It receives sensing data voltages from the drive IC, converts them to sensing currents, and outputs these currents to the external sensing circuit for measurement. This intermediary role allows the drive IC to remain simple while enabling precise sensing through the external circuit.
2Measurement precision
If pixels are sensed sequentially one by one to measure electrical characteristics, then measurement precision is improved, but productivity decreases due to prolonged sensing time
Solution Approach 1:
Multiple pixel sensing operations are merged into a single simultaneous measurement process. The external sensing circuit connects to multiple pixel circuits through sense lines and measures their electrical characteristics at the same time by applying the same sensing data voltage to all pixels. This parallel sensing approach maintains precision while dramatically reducing total sensing time compared to sequential measurement.
3Ease of operation
If pixels emit light during sensing mode to display image data, then ease of operation is improved, but object-generated harmful factors increase due to unwanted light emission
Solution Approach 1:
The display device operates in periodic cycles alternating between display mode and sensing mode. During sensing mode, pixels are controlled to emit light at a reduced duty cycle or with dimmed intensity, allowing electrical characteristic measurement while still providing some display function. During display mode, normal full-brightness operation resumes. This periodic switching enables both sensing and display operations without permanent loss of display quality.
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 approach reduces the time required to sense pixel electrical characteristics, prevents light emission during sensing, and avoids input voltage overflow in analog-to-digital converters, enabling efficient and cost-effective pixel characterization.
Implementation Method 1
a sensing circuit configured to simultaneously sense the plurality of the pixels by measuring a current flowing through a first power line
Data Source
AI summary
A display device includes: a plurality of pixels connected to power lines to which a pixel driving voltage and a reference voltage are applied, a plurality of data lines to which data voltages of pixel data of an input image are applied, and a plurality of gate lines to which a gate signal is applied; a display panel driver configured to write the pixel data of the input image to the plurality of pixels during a display mode of the display device and to write preset sensing data to the plurality of pixels during a sensing mode of the display device; and a sensing unit configured to simultaneously sense the plurality of the pixels by measuring a current flowing through a first power line from the plurality of power lines to which the pixel driving voltage is applied to the plurality of pixels during the sensing mode.