Hoffmann+Krippner GmbH from Buchen in the Odenwald has implemented a customized solution for the requirements of Siemens Bahntechnik. A robust touch panel for the driver’s cab of high-speed railcars was developed together with Siemens Mobility specialists, tested according to railroad standards and implemented in series production.
Every day, more than 40,000 trains in Germany take millions of passengers from A to B or goods to their destination. All these trains have a variety of controls and displays in a single cockpit. Siemens Mobility is helping to shape the passenger and freight transportation of today and tomorrow with trains, infrastructure, automation and electrification solutions.
For the control of high-speed trains, Siemens Mobility approached Hoffmann+Krippner with a specific request: an easy-to-read, robust and durable touch display, compliant with standards for the driver’s cab.
The input unit is to consist of a PCAP touchscreen including touch controller, a bonded TFT display and an LED display and is to be flush-mounted in an aluminum carrier plate. The maximum dimensions of the HMI of 310 x 214 x 6 mm must not be exceeded.
- PCAP touch screen incl. touch controller
- viewing angle stable TFT display with automatic brightness adjustment
- low-reflection, scratch-resistant and non-splintering protective screen of the display
- LED display
- Support part with maximum dimensions of 310 x 214 x 6 mm (width x height x thickness)
- Aging compensation for decreasing brightness of display and LEDs
- Degree of protection of min. IP65 and shock resistance according to IK07
- Working temperature: -40°C to +70 °C
- EMC conformity
Hoffmann+Krippner was able to meet all requirements in one touch system. The challenge lay above all in compulsory compliance with the standardized maximum dimensions of the control panel.
To make the touch system robust and shock-resistant, the touchscreen, cover glass and display were bonded using optical bonding. Using OCA and LOCA processes, the components were bonded over an adhesive layer that makes the system more resistant to temperature fluctuations and mechanical stresses. The visual appearance is ensured by an individual design, which is applied to the cover glass by screen printing.
To simplify subsequent assembly at the customer’s site and to give the touch display more stability, the complete touch system is flush-mounted in an aluminum support part via another bonding and simultaneous sealing.
The desired LED display is realized via a separate printed circuit board, which is mounted to the carrier part from behind. For this purpose, the board is equipped with three DUO LEDs and an additional brightness sensor. The viewing-angle stable display automatically adjusts to the ambient brightness via this brightness sensor.
All assemblies are combined into a touch system during assembly and subjected to a final 100% functional test.
The system was developed and produced according to IP65. Another requirement was a drop test according to IK07 – the system must survive a hammer fall (500Gr.) from a height of 1m in the middle without glass breakage and with the display still functioning.
Hoffmann+Krippner is a medium-sized developer and producer of customer-specific HMI input systems, sensors and IoT assemblies with mobile connectivity to ERP systems and IoT platforms, with 400 employees in the group. All development and production steps take place with a high degree of vertical integration at locations in Germany. Further information on the group of companies can be found at www.hk.systems. Source: Hoffmann+Krippner GmbH, Siemensstr. 1, 74722 Buchen. Author: Coralie Cicolelli.
