Solid-State Imaging Device Failure Detection Circuit
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Solution Overview
Problem
Existing solid-state imaging devices lack accurate failure detection mechanisms, particularly in on-vehicle applications, where the relationship between reset operations and voltage input is not adequately considered, leading to potential short-circuits and inaccurate failure detection.
Innovation Solution
A solid-state imaging device with first and second detection pixels, each equipped with a transfer transistor and an amplifier transistor, a voltage supply unit, and a connection switch, where the electrical path between the voltage supply unit and the transfer transistor is made non-conductive during specific periods to prevent short-circuits and enhance failure detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reset operations and voltage input operations are performed in parallel on detection pixels, then productivity is improved, but short-circuits may occur between voltage terminals reducing reliability
Solution Approach 1:
The patent applies preliminary action by controlling the timing of voltage input to detection pixels. The voltage input is performed only during periods when transfer transistors are turned off, which is determined in advance by the control signal timing. This prevents short-circuits before they can occur while still enabling parallel operation of reset and voltage input operations, thus maintaining both reliability and productivity
Solution Approach 2:
The patent implements dynamics by making the electrical path between the voltage supply unit and transfer transistor dynamically switchable through connection switches. These switches are controlled by control signals to be conductive or non-conductive based on the operational state, allowing the system to adapt its connectivity in real-time to prevent short-circuits while enabling parallel operations
2Measurement precision
If means for generating reference signal is provided in each pixel, then failure detection capability is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing detection pixels that serve multiple functions: they can perform normal image capture operations and failure detection operations. The same pixel structure with transfer transistors, amplifier transistors, and connection switches is used for both regular photoelectric conversion and for generating reference signals for failure detection, reducing the need for separate dedicated detection structures
Solution Approach 2:
The patent merges the failure detection functionality with the normal pixel operation. The reference signal generation is integrated into the existing pixel circuitry by utilizing the same transfer and amplifier transistors, and by controlling the connection switches to route signals appropriately. This combining approach avoids adding separate complex detection mechanisms to each pixel
Data Source
AI summary
A solid-state imaging device includes a first detection pixel and a second detection pixel, each of the first detection pixel and the second detection pixel including a transfer transistor and an amplifier transistor connected to the transfer transistor via a first node, a voltage supply unit that supplies a predetermined voltage, and a connection switch connected between the voltage supply unit and a second node at which the transfer transistor of the first detection pixel and the transfer transistor of the second detection pixel are connected.