Fingerprint Sensor Scan Circuit With Multiplexed Sensing Lines
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Solution Overview
Problem
The increase in the area of fingerprint sensor devices leads to an increase in the number of sensor pixels and pads, thereby increasing the manufacturing cost of the fingerprint driving circuit.
Innovation Solution
A fingerprint sensor device with a reduced number of bumps is achieved by using a fingerprint driving circuit that includes a multiplexer to connect multiple fingerprint sensing lines to a single pad line and a fingerprint scan driver with multiple stages, applying fingerprint scan signals with varying pulse widths and a dummy pulse, and a demultiplexer to distribute start signals efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the area of the fingerprint sensor device is increased to improve authentication capability, then the number of sensor pixels is increased, but the number of pads and bumps of the fingerprint driving circuit is increased, leading to increased manufacturing cost
Solution Approach 1:
Multiple fingerprint sensing lines are merged and connected to a single pad line through a multiplexer. This allows the fingerprint sensor device to maintain a large sensing area with high pixel count while reducing the number of pad lines and bumps required in the driving circuit, thereby resolving the contradiction between authentication capability and manufacturing cost
Solution Approach 2:
The multiplexer enables a single pad line to serve multiple functions by sequentially connecting to different fingerprint sensing lines. This multi-functional approach allows the driving circuit to handle a large number of sensor pixels with a reduced number of physical connections, reducing manufacturing complexity and cost while maintaining full sensing capability
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.