Fingerprint Scan Driver Layout With Fewer Bumps for In-Display Sensing
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Solution Overview
Problem
The manufacturing cost of fingerprint driving circuits is increased due to the large number of bumps required for connecting fingerprint sensor pixels to the driving circuit, which is a result of the increased area and number of sensor pixels in fingerprint sensor devices.
Innovation Solution
A fingerprint sensor device with a reduced number of bumps is achieved by using a demultiplexer to directly apply start signals to the fingerprint scan driver, eliminating the need for direct electrical connections between the fingerprint driving circuit and multiple start lines, thereby reducing the area and cost of the fingerprint driving circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the area of the fingerprint sensor device is increased to accommodate more sensor pixels, then the fingerprint sensing capability is improved, but the number of pads and bumps of the fingerprint driving circuit is increased, leading to increased manufacturing cost
Solution Approach 1:
The fingerprint sensor device is divided into multiple unit blocks, each with its own scan driver. This segmentation allows the sensing area to be expanded while keeping the connection complexity of each block manageable, reducing the overall number of bumps needed compared to a fully connected design
Solution Approach 2:
The patent introduces a hierarchical scanning architecture where scan drivers are arranged in stages across different dimensions. This multi-dimensional organization of scan lines and drivers reduces the direct connection requirements between sensor pixels and the main driving circuit, thereby reducing the number of bumps needed
2Measurement precision
If the number of sensor pixels is increased to improve fingerprint authentication accuracy, then the sensing resolution is improved, but the number of bumps of the fingerprint driving circuit is increased, leading to increased manufacturing cost
Solution Approach 1:
The high-resolution sensor array is segmented into multiple unit blocks with distributed scan drivers. This allows high sensing resolution to be achieved through local scanning units rather than requiring a single large-scale connection interface, reducing the bump count
Solution Approach 2:
Scan drivers act as intermediary components between the sensor pixels and the main driving circuit. These intermediate drivers locally process and route signals, reducing the direct connection requirements between the high-resolution sensor array and the external circuit, thereby reducing the number of bumps needed
Data Source
AI summary
A display device includes a display panel including a plurality of touch electrodes, a touch driving circuit electrically connected to the plurality of touch electrodes, and a fingerprint sensor device disposed on one surface of the display panel and including a plurality of unit blocks. The fingerprint sensor device includes a plurality of fingerprint scan lines extending in a first direction, a plurality of fingerprint sensing lines extending in a second direction crossing the first direction, a plurality of sensor pixels respectively connected to the plurality of fingerprint scan lines and the plurality of fingerprint sensing lines, and a fingerprint scan driver having a plurality of stages for applying a fingerprint scan signal to each of the plurality of fingerprint scan lines. The touch driving circuit applies a start signal to the fingerprint scan driver.