Vehicular Display Fault Notification With Dual Signal Paths
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Solution Overview
Problem
Existing display devices fail to issue notifications of failures when the control device malfunctions.
Innovation Solution
A display device with a controller that outputs opposite signals through two terminals, a first switch and a second switch, including a field effect transistor and a bipolar transistor, to ensure notification of failures even when the controller is faulty, and a delay circuit to prevent instantaneous activation or deactivation of the notification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single output terminal and single switch configuration is used, then the device complexity is reduced, but the reliability of failure notification deteriorates when the controller fails
Solution Approach 1:
The single output terminal is segmented into two separate output terminals (first and second output terminals), each connected to its own switch (first and second switches). This segmentation ensures that if one terminal or switch fails, the other can still activate the notifier, thereby improving failure notification reliability while maintaining manageable circuit complexity through modular design
Solution Approach 2:
The circuit is designed with redundant notification paths before controller failure can occur. By providing two independent output terminals with opposite signal states and two independent switches, the system cushions against potential single-point failures, ensuring that failure notification is maintained even when one component fails
2Reliability
If the notifier is always on, then the visibility of failure states is improved, but the energy consumption increases and false alerts occur
Solution Approach 1:
The notifier's state is made dynamic rather than static. Two switches control the notifier based on opposite signal states from the two output terminals. When the controller is functioning normally, one switch keeps the notifier off while the other is in a high-impedance state. When controller failure occurs, the signal states change, causing one of the switches to activate the notifier. This dynamic control ensures the notifier consumes energy only when needed, improving both energy efficiency and failure detection accuracy
Solution Approach 2:
The system uses feedback from the controller's output terminals to control the notifier state. The two output terminals provide opposite signals that feed back to their respective switches, which in turn control the notifier. This feedback mechanism ensures the notifier is activated only when the controller's signal state changes due to failure, preventing false alerts and reducing unnecessary energy consumption
3Reliability
If a single switch controls the notifier, then the device complexity is reduced, but the ability to detect controller failure deteriorates
Solution Approach 1:
The single switch control is segmented into two independent switches, each responding to opposite signal states from the two output terminals. This segmentation allows the system to detect controller failure by monitoring whether the notifier is inappropriately activated or deactivated, improving failure detection capability while maintaining reasonable circuit complexity through symmetric design
Solution Approach 2:
The two switches are configured with asymmetric signal responses - the first switch activates on one signal state while the second switch activates on the opposite signal state. This asymmetric configuration ensures that any change in controller output state due to failure will be detected by at least one switch, improving failure detection while the overall symmetric structure keeps complexity manageable
Data Source
AI summary
Provided is a vehicular display device that makes it possible to report abnormalities even when there is an abnormality at a control unit. A display device comprises a display unit, a reporting unit that reports abnormalities at the display device when turned on, and a control unit that controls the display unit and the reporting unit. The control unit comprises: a first output terminal that outputs a high signal when an abnormality has occurred at the display device and outputs a low signal when there are no abnormalities at the display device; and a second output terminal that outputs a low signal when an abnormality has occurred at the display device and outputs a high signal when there are no abnormalities at the display device. The display device comprises: a transistor that turns the reporting unit on when the high signal has been outputted from the first output terminal; and an FET and a transistor that turn the reporting unit on when the low signal has been outputted from the second output terminal.