Metal Halide Lamp Ballast Bias Control Circuit
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Solution Overview
Problem
Metal halide lamps in vehicle lighting systems require a ballast to operate effectively, leading to high sleep state bias power drain from the vehicle's power supply, which is inefficient and costly, especially when using complex and expensive bias circuits or electromechanical relays to manage power delivery.
Innovation Solution
A bias control circuit that selectively energizes a bias regulator within the ballast using a remote enable signal, reducing power consumption by minimizing current draw when not in use, and allowing continuous connection to the power supply without the need for high-capacity relays, utilizing a combination of switches and resistive pathways to manage bias voltages efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple and inexpensive bias circuit is used to provide bias power to the controller in sleep state, then the device complexity is reduced, but the power supply is drained over a relatively short period of time
Solution Approach 1:
The patent replaces electromechanical relays with solid-state switching devices (MOSFETs Q1-Q4) to control power delivery to the bias regulator. This substitution eliminates the need for mechanical moving parts while achieving the same power isolation function, thereby reducing sleep state power drain without increasing device complexity
Solution Approach 2:
The patent changes the electrical parameters (voltage levels, current paths) controlled by the solid-state switches to dynamically manage power delivery. By adjusting switch states based on operational mode, the system optimizes power consumption in sleep state while maintaining adequate bias power when active
2Ease of operation
If electromechanical relays are used to provide power to the ballast, then the lighting control module can be simpler, but the device complexity and cost increase
Solution Approach 1:
The patent merges the power switching function previously performed by separate electromechanical relays into the solid-state switching network integrated with the ballast circuitry. The MOSFETs Q1-Q4 work in conjunction with the lighting control module to provide both control and power switching functions, eliminating the need for additional relay components
Solution Approach 2:
The patent introduces solid-state switching devices as intermediaries between the lighting control module and the bias regulator. These switches act as electronic mediators that can rapidly respond to control signals while providing efficient power isolation, replacing the slower, more complex electromechanical relay system
3Reliability
If the ballast is continuously connected to the power supply, then power availability is ensured, but power drain during sleep state increases
Solution Approach 1:
The patent implements periodic control of power delivery to the bias regulator through the solid-state switching network. During sleep state, the switches isolate the bias regulator from the power supply. When operation is required, the switches rapidly connect power, enabling the ballast to be continuously available while minimizing continuous power drain
Solution Approach 2:
The patent segments the power delivery path into controllable sections using solid-state switches. By dividing the power path and selectively enabling/disabling segments based on operational needs, the system maintains power availability reliability while reducing energy loss during non-operational periods
Data Source
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AI summary
A vehicle lighting system receives power from a power supply and includes a lighting control module, a lamp, and a ballast having a bias control circuit. The lighting control module provides a remote enable signal to the ballast in response to an input. The bias control circuit of the ballast receives a supply voltage from a power supply and the remote enable signal and selectively energizes a bias regulator circuit of the ballast as a function of the remote enable signal. When the bias regulator circuit is energized, a controller of the ballast operates the ballast to provide power from the power supply to the lamp.