Photo Sensor Control Voltage Switching Circuit

Solution Overview

Problem

Conventional photo sensor switching circuits incur high charging currents and energy costs due to frequent switching between target voltages, which affects the efficiency of the charging pump circuits.

Innovation Solution

A method and circuit for switching the control voltage of a photo sensor cell that involves sequentially switching between multiple voltages provided by different supplies and charge pump circuits, reducing the energy required for turning on and off the signal path by using distinct target voltages that are different from the supply voltages, thereby minimizing the energy provided by the charging pump circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the switching circuit uses a first target voltage higher than system voltage to firmly turn on the signal path, then the signal path is firmly turned on for read-out circuit, but the charging pump circuit has to provide high charging current and energy to reach the required voltage level

Engineering Contradiction:

Improvesignal path turn-on reliabilityVSAvoidcharging pump energy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The voltage switching process is segmented into multiple stages: first switching to an intermediate voltage level (e.g., ground voltage or system voltage) provided by voltage supplies, then finally switching to the target voltage (VH or VL) provided by charging pump circuits. This segmentation reduces the energy burden on charging pump circuits by having voltage supplies handle part of the voltage transition.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Voltage supplies (first voltage supply and second voltage supply) are introduced as intermediary components to provide intermediate voltage levels during the switching process. These intermediaries assist the charging pump circuits by handling part of the voltage transition, thereby reducing the charging current and energy consumption required from the charging pump circuits while still achieving firm turn-on and turn-off of the signal path.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-generated harmful factors

If the switching circuit uses a second target voltage lower than ground voltage to firmly turn off the signal path and avoid dark current, then dark current is avoided, but the charging pump circuit has to provide high charging current and energy to reach the required voltage level

Engineering Contradiction:

Improvedark current suppressionVSAvoidcharging pump energy consumption

Core Design Contradiction:

Object-generated harmful factorsVSUse of energy by moving object

Solution Approach 1:

The voltage switching process is segmented into multiple stages: first switching to an intermediate voltage level (e.g., ground voltage or system voltage) provided by voltage supplies, then finally switching to the target voltage (VH or VL) provided by charging pump circuits. This segmentation reduces the energy burden on charging pump circuits by having voltage supplies handle part of the voltage transition.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Voltage supplies (first voltage supply and second voltage supply) are introduced as intermediary components to provide intermediate voltage levels during the switching process. These intermediaries assist the charging pump circuits by handling part of the voltage transition, thereby reducing the charging current and energy consumption required from the charging pump circuits while still achieving firm turn-on and turn-off of the signal path.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If the charging pump circuits frequently switch between target voltages to enable read-out circuit operation, then the read-out circuit can read charges of photo diode, but the charging pump circuits incur high operating frequency and flying capacitance costs

Engineering Contradiction:

Improvecharge reading capabilityVSAvoidcharging pump operating time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The voltage switching process is segmented into multiple stages: first switching to an intermediate voltage level (e.g., ground voltage or system voltage) provided by voltage supplies, then finally switching to the target voltage (VH or VL) provided by charging pump circuits. This segmentation reduces the energy burden on charging pump circuits by having voltage supplies handle part of the voltage transition.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Voltage supplies (first voltage supply and second voltage supply) are introduced as intermediary components to provide intermediate voltage levels during the switching process. These intermediaries assist the charging pump circuits by handling part of the voltage transition, thereby reducing the charging current and energy consumption required from the charging pump circuits while still achieving firm turn-on and turn-off of the signal path.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11112302B2Method of switching control voltage of photo sensor cell and related switching circuit and photo sensor

Publication Date: 2021.09.07 NOVATEK MICROELECTRONICS CORP

AI summary

A method of switching a control voltage of a photo sensor cell for a photo sensor includes when the photo sensor cell is switched from a turned-off state to an turned-on state, sequentially switching the control voltage to at least one first voltage provided by at least one first voltage supply, and switching the control voltage to a first target voltage provided by a first charging pump circuit; and when the photo sensor cell is switched from the turned-on state to the turned-off state, sequentially switching the control voltage to at least one second voltage provided by at least one second voltage supply or a ground voltage, and switching the control voltage to a second target voltage provided by a second charging pump circuit.