Vertical Scan Unit Test Coverage for Imaging Pixels
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Solution Overview
Problem
The existing imaging apparatus has a low test coverage rate due to the inability to inspect all signal generation units and holding units in the vertical scan unit, particularly when each row includes multiple storage elements, leading to decreased efficiency in testing.
Innovation Solution
The proposed imaging apparatus includes a vertical scan unit with an address decoder and multiple holding units, each equipped with SR latch and D latch circuits, which allows for improved test coverage by enabling the inspection of all signal generation units and holding units, enhancing the test coverage rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vertical scan unit includes multiple holding units and signal generation units for testing, then the test coverage rate improves, but the device complexity increases
Solution Approach 1:
The signal generation unit is designed to perform multiple functions: it generates test signals for holding units, generates control signals for pixel arrays, and can operate in different test modes (first test mode for holding units, second test mode for signal generation units). This multi-functionality allows comprehensive testing without adding separate dedicated test circuits for each function, thereby improving test coverage while controlling device complexity.
Solution Approach 2:
The patent implements a hierarchical test structure where the signal generation unit contains nested test capabilities for both holding units and other signal generation units. The holding units are arranged in rows and columns with nested addressing schemes, allowing systematic testing of multiple levels of the vertical scan unit through a unified test architecture.
2Reliability
If the vertical scan unit uses sequential reset operations for multiple rows, then the circuit inspection can be performed, but the testing time increases
Solution Approach 1:
The patent employs periodic test operations where the signal generation unit alternates between different test modes in a systematic sequence. The holding units are tested in a periodic pattern across multiple rows, with each row undergoing the same test sequence. This periodic approach allows comprehensive circuit inspection while maintaining efficient test execution through repetitive, standardized test cycles.
Solution Approach 2:
The test architecture performs preliminary setup by configuring the signal generation unit and holding units in specific test states before actual testing begins. Reset signals are pre-configured and held in ready states, allowing rapid initiation of test sequences without time-consuming reconfiguration during the testing process.
Data Source
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AI summary
An embodiment provides an imaging apparatus including pixels arranged to form rows including first and second rows, first control lines connected to the pixels of the first row, second control lines connected to the pixels of the second row, and a scan unit including at least a first row drive unit generating first control signals supplied to the first control lines and a second row drive unit generating second control signals supplied to the second control lines, the scan unit being configured to drive the pixels in units of rows based on a scanning signal. The first control signals generated by the first row drive unit is input to the second row drive unit. The second row drive unit selects the first control signals and the scanning signal and generates the second control signals based on the selected signals.