Vehicle Instrument Panel Pointer Position Detection via Optical Sensor
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Solution Overview
Problem
Vehicle instrument panel assemblies face inaccuracies due to power interruptions causing the pointer to lose its orientation angle, resulting in motor bounce and gauge inaccuracy, as existing systems lack effective methods to determine the pointer's orientation angle reliably.
Innovation Solution
A vehicle instrument panel assembly equipped with a sensor that detects light emitted by a pointer at a predetermined orientation angle, using a trim ring or light pipe to direct light to the sensor, and a controller to determine the correct orientation angle, preventing errors from power loss or stepper motor malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a camera is used to determine offset error during manufacturing, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex optical measurement systems (camera-based offset detection) with a simple optical sensor that detects the position of an illuminated index mark on the pointer. This substitution maintains manufacturing precision while significantly reducing device complexity by using basic optical components instead of sophisticated imaging systems.
Solution Approach 2:
The patent uses an illuminated index mark (a simple visual copy or representation of the pointer position) that can be easily detected by a sensor. This allows the system to determine pointer position without complex measurement equipment, as the index mark serves as a simplified optical copy of the pointer's angular position.
2Reliability
If the instrument panel performs homing operation to spin the pointer back to zero position, then reliability is improved, but the motor may hit hard-stop with excessive force causing bounce and inaccuracy
Solution Approach 1:
The patent replaces mechanical homing methods (spinning the pointer to a physical stop) with an optical detection system. The sensor detects the position of an illuminated index mark on the pointer to determine when the pointer reaches the zero position, eliminating the need for forceful mechanical engagement with a hard stop and preventing motor bounce and vibration.
Solution Approach 2:
The patent introduces an illuminated index mark as an intermediary element between the pointer and the detection system. This index mark provides a clear optical signal that the sensor can detect to determine pointer position, serving as a mediator that enables precise position detection without requiring direct mechanical contact or forceful stopping.
3Ease of manufacture
If the sensor is located remotely from the display surface, then ease of manufacture is improved, but light detection capability deteriorates
Solution Approach 1:
The patent uses a light pipe as an intermediary optical element that bridges the gap between the pointer (light source) and the remotely mounted sensor. The light pipe efficiently conducts light from the pointer's index mark to the sensor, maintaining high light detection capability even when the sensor is located remotely on the circuit board for ease of manufacture.
Solution Approach 2:
The patent replaces direct optical coupling (which would require precise mechanical alignment) with a light pipe-based optical conduction system. This substitution allows the sensor to be mounted remotely on the circuit board without compromising light detection accuracy, as the light pipe efficiently transports light over the distance.
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 ensures accurate pointer positioning by determining the orientation angle in real-time, preventing errors and maintaining gauge accuracy even during power interruptions or stepper motor misalignment.
Implementation Method 1
The pointer is configured to emit light
Implementation Method 2
The sensor is configured to detect light emitted by the pointer
Implementation Method 3
a trim ring configured to direct light emitted by the pointer toward the sensor
Implementation Method 4
a light pipe that is integral to the trim ring and configured to direct light emitted by the pointer from the display surface to the sensor
Data Source
Figure 1
Figure 2~3
AI summary
A vehicle (10) instrument panel assembly (12) configured to determine an orientation angle of an illuminated pointer (24) of the assembly (12). The assembly (12) includes a pointer (24), and a sensor (32). The pointer (24) is configured to emit light (28) and rotate about a display surface (20) of the assembly (12) to point to indicia (22) on the display surface (20). The sensor (32) is configured to detect light (28) emitted by the pointer (24) when the pointer (24) is oriented at a predetermined orientation angle relative to the display surface (20).