Dual-Computer Digital Output for Fail-Safe Alternating Signals

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

The increasing process load on CPUs in railway safety devices due to the generation of alternating signals through software processing, which strains other processes and limits the number of ports capable of generating pulse outputs.

Innovation Solution

A digital output device comprising two computers, a collation unit, and two output conversion units that generate alternating signals based on output instructions, with check units monitoring the output conversion units to detect failures and prevent unsafety operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If analog audio signals are converted to digital format using traditional methods, then digital audio output is achieved, but additional digital-to-analog conversion steps are required which complicate the system and reduce signal quality

Engineering Contradiction:
Improvesignal qualityVSAvoidconversion steps
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the unnecessary digital-to-analog conversion step from the traditional audio playback chain. By having the audio output device perform digital signal processing directly, the system removes the intermediate conversion steps that complicate the system architecture and potentially degrade signal quality.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The audio output device is given multi-functionality by enabling it to perform both digital signal processing and direct digital output. This eliminates the need for separate conversion devices, simplifying the overall system while maintaining or improving signal quality through reduced conversion steps.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If multiple conversion steps are used in digital audio output, then compatibility with various devices is maintained, but signal quality deteriorates and system complexity increases

Engineering Contradiction:
Improvesignal qualityVSAvoiddevice compatibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent changes the operational parameters of the audio output device by enabling it to perform digital signal processing directly. This parameter change allows the device to output digital signals with higher quality while maintaining compatibility with various digital audio devices through standardized digital interfaces, eliminating the need for multiple conversion steps.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If traditional digital-to-analog conversion is used, then analog output is achieved, but the system requires additional hardware and conversion steps

Engineering Contradiction:
Improvesystem simplicityVSAvoidhardware requirements
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The audio output device performs self-service by handling digital signal processing internally without requiring external conversion hardware. This self-sufficient approach simplifies the overall system architecture and reduces hardware requirements while maintaining ease of operation through standardized digital interfaces.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4328676B1Digital output apparatus and method for generating digital output
Publication Date: 2026.04.29 HITACHI LTD
  • EP4328676B1 patent drawingFigure 1
  • EP4328676B1 patent drawingFigure 2
  • EP4328676B1 patent drawingFigure 3

AI summary

Provided is a digital output device for generating an alternate signal that is not generated from software processing, while ensuring a conventional configuration and safety, in order to lessen a CPU process load of generating an alternate signal at a fail-safe CPU. In order to achieve this, a digital output device includes two computers, a collation unit that collates computation results obtained by the two computers, and two output conversion units that receive output instructions based on the respective computation results obtained by the two computers. The collation unit outputs a first alternate signal when the computation results match each other. Each of the two output conversion units outputs a second alternate signal when the output instruction is an alternate signal output instruction, or outputs a non-alternate signal when the output instruction is an alternate signal stop instruction.