LED Drive Controller Port Reduction via Opposite-Parallel Grouping
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Solution Overview
Problem
Conventional light emitting device drive controllers require a large number of control ports to drive four or five LEDs, leading to increased size and cost due to the need for one-on-one correspondence between LEDs and control ports, especially in dynamic drive types where the number of control ports is constrained.
Innovation Solution
A light emitting device drive controller with a reduced number of ports is achieved by connecting two LEDs in parallel in opposite directions per group, using three control ports that can be set to different voltage states or high impedance, allowing selective driving of the LEDs based on the state of a switch detecting a change in a predetermined factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If one-on-one correspondence between LEDs and control ports is used, then each LED can be controlled independently, but the number of control ports increases leading to increased size and cost
Solution Approach 1:
The patent combines multiple LED control functions into a single control port by connecting two LEDs in parallel in opposite directions. The control port can output high level, low level, or high impedance state to control both LEDs simultaneously, eliminating the need for separate control ports for each LED.
Solution Approach 2:
The control port is designed to perform multiple functions: it can drive LEDs in both directions, indicate different battery levels (4 levels), and maintain high impedance state for power saving. This multi-functionality reduces the overall number of control ports needed in the system.
2Productivity
If more control ports are provided, then more LEDs can be controlled simultaneously, but the microcomputer size and wiring cost increase
Solution Approach 1:
The patent adds the time dimension to LED control by using periodic switching. Instead of controlling all LEDs simultaneously through multiple ports, the system controls different LED groups at different time periods through a single port, effectively managing more LEDs without increasing port count or wiring complexity.
Data Source
AI summary
A light emitting device drive controller is disclosed that comprises a first port that is connected to one end of a first light emitting device group where two light emitting devices are connected in parallel in the opposite directions; a second port that is connected to the other end of the first light emitting device group as well as connected to one end of a second light emitting device group where two light emitting devices are connected in parallel in the opposite directions; a third port that is connected to the other end of the second light emitting device group; and a port state setting unit that selectively sets each of the first, second, and third ports to any one of a state of a first voltage, a state of a second voltage which is less than the first voltage, and a high impedance state for each consecutive predetermined period, wherein the light emitting device drive controller drives selectively the light emitting devices constituting the first light emitting device group and the second light emitting device group in response to the states of the first, second, and third ports.