Image Sensor Column Delay Compensation for Signal Skew
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Solution Overview
Problem
Conventional image sensors experience signal skew due to manufacturing variations and delays in the control signal supply line, leading to reduced accuracy in high-time-resolution imaging, especially when trying to measure distances with sub-millisecond precision.
Innovation Solution
The image sensor incorporates a delay adjustment unit for each column and row of photoelectric conversion elements, allowing for variable delay times in the control clock to synchronize charge transfer, thereby canceling out differences in transfer delays and preventing signal skew.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high time resolution is requested for the image sensor, then measurement precision is improved, but signal skew occurs due to manufacturing variations and supply line delays
Solution Approach 1:
The patent applies preliminary action by measuring and storing delay characteristics of control signals for each column before actual imaging operations. The delay amount calculation unit pre-calculates the delay characteristics during a measurement period, and the delay amount addition unit adds these pre-calculated delay amounts to the control signals during imaging, thereby compensating for skew effects before they degrade measurement precision.
Solution Approach 2:
The patent changes the time parameter of control signals by adding column-specific delay amounts to compensate for manufacturing variations. The delay amount addition unit modifies the timing parameter of control signals supplied to each column based on pre-measured delay characteristics, thereby equalizing the effective delay across all columns and improving distance measurement accuracy.
2Productivity
If control signals are supplied to multiple columns simultaneously, then productivity is improved, but signal skew increases due to supply line delays
Solution Approach 1:
The patent applies local quality by providing different delay amounts to different columns based on their specific delay characteristics. The delay amount addition unit supplies customized delay amounts to each column (or group of columns) according to pre-measured delay characteristics, thereby locally compensating for supply line delays while maintaining simultaneous operation of all columns.
Solution Approach 2:
The patent measures and stores delay characteristics for each column before actual imaging operations. The delay amount calculation unit pre-calculates the delay characteristics during a measurement period, enabling subsequent real-time compensation without affecting imaging speed or productivity.
3Measurement precision
If delay adjustment units are added to each column, then signal skew is reduced, but device complexity increases
Solution Approach 1:
The patent merges the delay adjustment functionality into the existing control signal supply structure. Rather than adding completely separate delay adjustment units to each column, the delay amount addition unit is integrated with the control signal supply unit, combining measurement, calculation, and compensation functions in a unified structure that reduces overall device complexity.
Solution Approach 2:
The control signal supply unit is designed with multi-functionality, serving both as the original control signal distributor and as a delay compensation unit. The delay amount addition unit performs multiple functions: storing delay characteristics, calculating delay amounts, and adding delay compensation to control signals, thereby reducing the need for separate dedicated delay adjustment circuits in each column.
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 configuration enhances the time resolution and accuracy of imaging, enabling precise distance measurement by synchronizing charge transfer across the sensor array, thus improving the overall imaging performance.
Implementation Method 1
a plurality of photoelectric conversion elements that include a light-receiver to convert incident light into charges
Data Source
AI summary
A high-accurate imaging increased in time resolution can be made. The camera device is provided with a plurality of pixels that include a light-receiving surface embedded region to convert incident light into charges, a charge accumulation region to accumulate the charges, and a gate electrode to control the charges to be transferred from the light-receiving surface embedded region to the charge accumulation region, and are one-dimensionally arranged in each of a plurality of columns, a timing generation circuit which generates a control pulse voltage to be applied to the gate electrode, and a correction circuit unit which is provided in accordance with each of a plurality of columns of the pixels, delays the control pulse voltage in a variable time, and applies the control pulse voltage to the gate electrodes of the plurality of pixels belonging to a column corresponding to the control pulse voltage.