Discharge Lamp Lighting Device Rapid Current Modulation

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Solution Overview

Problem

Conventional discharge lamp lighting devices face challenges in rapidly modulating the brightness of high-intensity discharge lamps, leading to issues such as power wastage, image quality deterioration, and increased manufacturing costs due to the need for high-speed AD converters and microprocessors, which also result in jitter in modulation timing.

Innovation Solution

A discharge lamp lighting device with a power supply circuit, current control element circuit, and current reduction modulation control circuit that rapidly interrupts or reduces the lamp current by detecting output current and adjusting it using a proportional constant, allowing for immediate restoration without relying on microprocessors or complex feedback loops, thus minimizing jitter and overshoot.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the lamp current is completely interrupted to reduce power consumption, then power savings are improved, but the lamp cannot resume discharge or produces abnormal emission spectrum

Engineering Contradiction:

Improvepower consumptionVSAvoiddischarge resumption capability

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

Instead of completely interrupting the lamp current, the invention applies partial action by reducing the current to a low level (e.g., 10-20% of normal operating current) during the off-period. This partial current maintenance prevents the discharge plasma from completely extinguishing, allowing the lamp to resume discharge immediately when the modulation signal ends, while still achieving significant power savings and reduced heat generation.

Inventive Principle:

Principle #16Partial or excessive action

2Speed

If high-speed AD converters and microprocessors are used for rapid current modulation, then modulation speed is improved, but manufacturing costs and device complexity increase

Engineering Contradiction:

Improvemodulation speedVSAvoidcircuit complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The invention extracts and removes the complex microprocessor and high-speed AD converter components from the system. Instead, it uses a simple comparator circuit that compares the actual lamp current with a reference current to generate modulation signals. This extraction of unnecessary complex components dramatically reduces manufacturing costs and device complexity while maintaining rapid modulation capability through the inherent speed of analog comparator operations.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention substitutes the digital control system (microprocessor with AD converters) with an analog control system using operational amplifiers and comparators. This mechanical/electrical substitution leverages the natural speed of analog signal processing to achieve rapid current modulation without the overhead of digital conversion and processing, thereby simplifying the overall system architecture.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If digital signal processing is used for current modulation, then control precision is improved, but modulation timing jitter increases

Engineering Contradiction:

Improvecurrent control precisionVSAvoidmodulation timing jitter

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The invention maintains continuous analog signal processing throughout the modulation process, from the input modulation signal through the operational amplifiers to the final current control. This continuous analog action eliminates the discrete sampling and processing steps inherent in digital systems, thereby eliminating modulation timing jitter while preserving control precision through the continuous nature of analog signal relationships.

Inventive Principle:

Principle #20Continuity of useful action

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

Enables rapid and precise modulation of lamp current, reducing power consumption and maintaining image quality by minimizing delay and jitter in the modulation process, while also preventing abnormal discharge spectra and extending lamp lifespan.

Implementation Method 1

a power supply circuit 11 which supplies power to the discharge lamp 1

Methodology Applied

Scientific EffectElectrical Resistance: Electrical Resistance

Implementation Method 2

a current control element circuit 12 which reduces a current flowing through the discharge lamp 1

Methodology Applied

Scientific EffectElectrical Conduction: Conduction (electrical)

Implementation Method 3

a discharge lamp 1 having a pair of main discharge electrodes E1 and E2 facing each other

Methodology Applied

Scientific EffectPlasma: Plasma

Implementation Method 4

a glow discharge and an arc discharge sequentially occur

Methodology Applied

Scientific EffectElectric Arc: Electric Arc

Data Source

PatentUS7332868B2Discharge lamp lighting device

Publication Date: 2008.02.19 USHIO INC

AI summary

The present discharge lamp lighting device is capable of rapid modulation in which a lamp current is rapidly reduced and rapidly restored. The current control circuit is provided to perform specific current control such that the brightness of a lamp is reduced by a predetermined percentage without being affected by a variation or change in lamp voltage over time, thereby reducing a lamp current.