LED Pulse Timing Control With a Single Timer to Reduce Noise
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Solution Overview
Problem
Existing control devices for light sources in automobiles require multiple timers and expensive CPUs to manage multiple pulses independently, leading to high costs and noise issues due to simultaneous on and off timings.
Innovation Solution
A control device that uses a single timer to output pulses with on-timing and off-timing shifted at constant intervals, allowing for independent duty control of multiple pulses to prevent close timings and reduce noise, implemented using a CPU that adjusts pulse schedules based on predetermined values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple timers are used to control multiple pulses independently, then each pulse can be precisely controlled, but the device cost increases due to requiring an expensive CPU
Solution Approach 1:
The patent combines multiple pulse control functions into a single timer unit. The control device uses one timer to generate multiple pulse signals by sequentially controlling the on-timing and off-timing of each pulse, eliminating the need for multiple separate timers and reducing CPU cost while maintaining precise pulse timing control.
Solution Approach 2:
The single timer is designed to perform multiple functions by generating different pulse signals for multiple channels. The timer can sequentially control different groups of on-timing and off-timing values to produce multiple independent pulse outputs, making one timer unit serve the role of multiple timers.
2Ease of operation
If multiple pulses are turned on and off at the same time, then control simplicity is improved, but high-frequency noise increases
Solution Approach 1:
The patent introduces periodic staggering of pulse on-timing and off-timing across different channels. By sequentially activating and deactivating pulses in a predetermined periodic sequence rather than simultaneously, the system reduces high-frequency noise while maintaining straightforward control logic through the single timer's sequential operation.
Data Source
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AI summary
A control device including a CPU is provided. The CPU outputs a plurality of pulses each having a duty set independently to LED. The CPU creates a schedule in which on-timing and off-timing of the plurality of pluses are designated such that the on-timing or the off-timing of two or more of the plurality of pulses is respectively not close to each other based on the set duty and a duty of the pulse. Further, the CPU sets, in a timer for counting time, time from a time point where the timer finishes counting the time already set to on-timing or off-timing of a pulse to be first turned on or off after the time point in accordance with the schedule. The CPU turns on or off the pulse in accordance with the schedule when the timer finishes counting the set time.