Solid State Imaging Pixel Array Regional Signal Readout
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Solution Overview
Problem
Existing solid state imaging apparatuses face challenges in accurately performing illuminance and movement detection across divided pixel arrays due to limitations in reading signals from partial regions, leading to inadequate illuminance detection and increased chip size or impedance issues with power supply switches.
Innovation Solution
A solid state imaging apparatus with a pixel array where each unit pixel includes a photoelectric conversion element, transfer, reset, and output transistors, along with an addition node and signal reading circuit that allows for the addition and reading of signals from each pixel block, enabling more accurate illuminance and movement detection by dividing the pixel array into regions and using vertical signal lines and amplification transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pixel array is divided into multiple regions for illuminance and movement detection, then measurement precision is improved, but device complexity increases due to difficulty in reading signals from partial regions
Solution Approach 1:
The pixel array is divided into multiple regions (e.g., first region and second region) with separate signal reading circuits. Each region can be independently read, allowing accurate illuminance and movement detection in each partial region without increasing overall system complexity. The segmentation enables parallel processing of different regions.
Solution Approach 2:
The patent introduces a regional division dimension to the pixel array structure. By organizing pixels into distinct regions with separate readout paths, the system gains the ability to independently analyze different spatial zones, improving measurement precision for illuminance and movement detection without complicating the signal reading process.
2Measurement precision
If a switch is added to set the power supply of reset transistors to floating state, then illuminance detection capability is improved, but chip size increases
Solution Approach 1:
The reset transistor's power supply node serves multiple functions: it can be connected to the power supply voltage for normal operation or set to floating state for illuminance detection. This multi-functionality eliminates the need for separate dedicated switches, reducing chip size while maintaining illuminance detection capability.
Solution Approach 2:
The reset transistor's power supply node automatically serves dual purposes by being able to operate in two states (connected or floating) without requiring additional control circuitry. The node itself provides the illuminance detection function when floated, eliminating the need for separate switches and reducing overall chip area.
3Area of stationary object
If the power supply switch is made smaller to reduce chip size, then chip area is reduced, but impedance of power supply line increases and image quality deteriorates
Solution Approach 1:
The patent extracts the illuminance detection function from the normal signal path by utilizing the floating state of the reset transistor's power supply node. This separation allows the main power supply lines to remain optimized for signal quality while the floating node provides illuminance detection without requiring additional switching components that would increase impedance.
4Use of energy by moving object
If signals are read from all pixels collectively, then power consumption is reduced, but illuminance detection accuracy deteriorates due to inability to perform regional analysis
Solution Approach 1:
The pixel array is segmented into multiple regions with independent readout circuits. This allows selective reading of specific regions based on detection needs, enabling accurate regional illuminance and movement detection. The segmentation maintains reasonable power consumption by allowing independent control of readout operations for each region.
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 allows for more accurate illuminance detection and movement detection across divided pixel regions, reducing power consumption and improving image quality by enabling the reading of signals from partial regions without increasing chip size or impedance.
Implementation Method 1
Each pixel includes a photodiode 61, a transfer transistor 62, floating diffusion 63, a reset transistor 64, an amplification transistor 65, a selection transistor 66, and an output transistor 67. The photodiode 61 performs photoelectric conversion of incident light, and generates and accumulates a charge corresponding to this amount of light.
Implementation Method 2
a lens is placed in front of a photodiode in a camera module formed by combining an image sensor and a lens. In such a camera module, for example, a camera module using a fixed focal length lens such as a so-called sub-camera (also called an in-camera) included in a mobile phone, light sources are brought into focus which are in positions separated by a degree of separation of several tens of cm or more.
Data Source
AI summary
There is provided a solid state imaging apparatus including a pixel array in which a plurality of unit pixels are arranged two-dimensionally. Each pixel includes a photoelectric conversion element, a transfer transistor which transfers a charge accumulated in the photoelectric conversion element to floating diffusion, a reset transistor which resets the charge of the floating diffusion, and an output transistor which outputs the charge of the floating diffusion. The floating diffusion of at least one of the plurality of unit pixels is electrically connected via the output transistor.