Power Supply Circuit Inrush Current Suppression

Solution Overview

Problem

Existing power supply circuits for recording devices experience a high inrush current when starting, due to a large potential difference between the capacitor and power supply, leading to increased circuit size and cost when attempting to mitigate this issue.

Innovation Solution

A power supply circuit with a capacitor and charging/discharging circuits that manage power supply to the recording head, using a switch circuit to control the current mirror and push-pull circuits to stabilize voltage and reduce inrush current, while maintaining a predetermined power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a circuit configured to decrease the inrush current value is provided, then the inrush current is reduced, but the scale and cost of the power supply circuit are increased

Engineering Contradiction:

Improveinrush currentVSAvoidpower supply circuit scale

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The capacitor is pre-charged to a voltage close to the power supply voltage before the recording head is activated. This preliminary charging action reduces the potential difference that would otherwise cause inrush current, while the control circuit manages the charging process without requiring additional current-limiting components.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control circuit acts as an intermediary that manages the capacitor charging process. It controls the charging current to prevent inrush current while maintaining circuit simplicity, avoiding the need for complex current-limiting circuits.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If a circuit configured to decrease the inrush current value is provided, then the inrush current is reduced, but the cost of the power supply circuit is increased

Engineering Contradiction:

Improveinrush currentVSAvoidpower supply circuit cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The capacitor is pre-charged to a voltage close to the power supply voltage before the recording head is activated. This preliminary charging action reduces the potential difference that would otherwise cause inrush current, while the control circuit manages the charging process without requiring additional current-limiting components.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control circuit acts as an intermediary that manages the capacitor charging process. It controls the charging current to prevent inrush current while maintaining circuit simplicity, avoiding the need for complex current-limiting circuits.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If the capacitor has a small number of electrical charges, then the power supply circuit is simpler, but a large inrush current occurs due to large potential difference

Engineering Contradiction:

Improvepower supply circuit complexityVSAvoidinrush current

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The capacitor is pre-charged to a voltage close to the power supply voltage before the recording head is activated. This preliminary charging action reduces the potential difference that would otherwise cause inrush current, while the control circuit manages the charging process without requiring additional current-limiting components.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control circuit acts as an intermediary that manages the capacitor charging process. It controls the charging current to prevent inrush current while maintaining circuit simplicity, avoiding the need for complex current-limiting circuits.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

The solution effectively reduces the occurrence of high inrush current at a lower cost by stabilizing the potential of the recording head and managing power supply efficiently, ensuring stable operation and reduced circuit complexity.

Implementation Method 1

a capacitor (e.g., an electrolytic capacitor) used to supply power to the electric thermal conversion member while maintaining a stabilized voltage value

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

A recording device converts power into heat by using an electric thermal conversion member provided in a recording head

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS8148945B2Device provided with power supply circuit

Publication Date: 2012.04.03 CANON KK

AI summary

A device configured to suppress the occurrence of an inrush current is provided at a low cost, where the device includes a power circuit configured to generate a voltage used to drive a load, a capacitor connected to a supply line provided to supply power from the power circuit to the load, the capacitor being configured in such manner to stabilize the potential of the load, a charging/discharging circuit that supplies an amount of power smaller than a predetermined amount of power to the capacitor and that discharges the smaller amount of power from the capacitor, a charging circuit that supplies an amount of power larger than the predetermined amount of power to the capacitor, and a switch circuit configured to make each of the charging/discharging circuit and the charging circuit operate.