Photoelectric Conversion Device Current Control Circuit
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Solution Overview
Problem
Photoelectric conversion devices experience signal quality deterioration due to fluctuations in power source potential when the signal line and current source are electrically disconnected and then reconnected, leading to potential overshoot currents that affect the power supply potential.
Innovation Solution
A photoelectric conversion device is designed with a current adjusting unit, including a switch to control the connection or disconnection between the current source and signal line, and an assisting transistor to manage the current flow, reducing overshoot currents by assisting the change in current when the driving current transitions from a disconnected to a connected state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the current source is electrically disconnected from the signal line and then reconnected, then power consumption is reduced, but power source potential fluctuation occurs causing signal quality deterioration
Solution Approach 1:
The assisting transistor is activated in advance before the current source is reconnected to the signal line. This preliminary action prepares the current path and prevents potential fluctuation when the current source is reconnected, thereby maintaining signal quality while still allowing power consumption reduction during disconnection periods.
Solution Approach 2:
The assisting transistor acts as an intermediary element between the current source and the signal line. It provides a controlled current path that mediates the connection process, preventing direct abrupt connection that would cause potential fluctuation and signal quality deterioration.
2Power
If the driving current is increased from the first current amount to the second current amount, then the driving capability is improved, but overshoot current occurs affecting power supply potential stability
Solution Approach 1:
The assisting transistor is activated in advance before the driving current is increased. This preliminary action establishes a controlled current path that prevents overshoot current when the driving current is increased, thereby maintaining power supply potential stability while still improving driving capability.
Solution Approach 2:
The assisting transistor provides beforehand cushioning by being activated prior to the current increase. It cushions against the potential overshoot current that would occur during the transition to higher driving current, protecting the power supply potential from instability.
Data Source
AI summary
Provided is a photoelectric conversion device including a pixel array in which pixels, each of the pixels including a photoelectric conversion element, are arranged in columns, a signal line that is arranged corresponding to one of the columns in the pixel array and to which a signal from the pixel is output, a current source configured to supply the signal line with a driving current; a current adjusting unit configured to control the driving current into a current amount including a first current amount and a second current amount greater than the first current amount, and an assisting element configured to assist a change in a current flowing through the signal line when the driving current changes from the first current amount to the second current amount. The first current amount is a current amount in a state where the driving current is disconnected.