Smart Foil Display

Projektleitung / Project Leader
Prof. Dr. Artem Ivanov

Projektlaufzeit / Project Duration
Oktober 2017 – March 2020

Projektbeschreibung / Description

The project is aimed to demonstrate the use of printed electroluminescent displays (ELD) in real world applications. It is a further step in the work of Landshut UAS on developing printed matrix ELDs with compact low cost driver electronics. The functional principle and integration of such display systems in smart textile articles can be found in [1] and [2] respectively.

Demonstrators of January 2018 (created for LOPEC 2018)

Demonstrators created in January 2018 feature an ELD integrated into a bag and a back pack with the primary goal to allow traffic signalling for cyclists or skaters during the dark periods of day. In this mode light signals for turning and braking will be given by the display to inform the vehicles driving behind the sportsman of her or his manoeuvres. The second mode of operation – the “fun mode” – can be used to show short text messages to surrounding persons, e.g. during social events or in everyday life [3], [4]. The idea for this mode originates from our experience with the previous demonstrators [2] where we observed that young people found it “cool” to be able to “post” their “status” for everyone as it happens in social networks. In the both modes the display will be controlled wirelessly (via Bluetooth) using either a smartphone or a dedicated device.

The major goal of the demonstrator project is to reveal applications which are possible with currently available materials and technology and which can be implemented with low costs even in a low volume production. It will be used at Landshut UAS as a platform for further testing of the use cases and technology under the real life conditions.

The main part of the demonstrators is an electroluminescent matrix display printed on a flexible PET substrate and packaged together with its driver electronics to form a “foil display”. This foil display is designed as a self-contained component to allow an easy integration into textile articles. In the demonstrator the integration is implemented by sliding the foil display into a dedicated pocket on the bag. So it can be easily removed if washing is needed. Several display topologies and matrix resolutions are tested during the project; focus lies on a display with a matrix of 32 by 5 pixels and with six to nine additional pictogram elements.

Demonstrators of January 2019

In this stage of the project 30 printed electroluminescent (EL) display systems have been manufactured to be used with smart textile items. The systems are intended to be powered from compact USB power banks and rely on Bluetooth low energy (BLE) for the communication with a smartphone app and interaction with the user.

The display size in the range of 10 cm to 20 cm (diagonal) is given by the requirement to present texts readable from a distance of several meters. Electroluminescent displays in two variants were printed: a 32 x 13 pixel matrix with three pictograms and a 32 x 5 matrix with ten pictogram elements. Both variants are driven by the same electronic circuit.

In contrast to our previous demonstrators we used white phosphor and created icons of different colours applying optical filters in form of coloured polymer foils upon selected zones on the display. Using this method various colours can be easily generated; the drawback is a reduced brightness of the display: the white phosphor itself produces less light as the blue phosphor, further decrease of intensity is due to the filter absorption. All EL displays were printed on 125 µm thick PET substrates and laminated on one side with a 50 µm foil for protection and electrical insulation. The total thickness of the displays was in the range from 175 µm to 225 µm.

Twelve jackets have been equipped with one or two displays each to undergo a field test which started in March 2019. Planned duration of the test is from March 2019 to February 2020. Twelve volunteers are asked to wear jackets equipped with displays in their everyday life and to log the character and the duration of usage. The field test should not only demonstrate the technical functionality and the reliability of technological solutions but also deliver information on social aspects of the intended application, e.g. on general acceptance and degree of interest to such displays in clothing for different age groups, on especially important use cases, on the limits of application etc. The results will be used to analyse, which system parameters (like mechanical flexibility, stretchability, pixel brightness, size and resolution of the matrix) are especially important for the use case. They will also serve to set the direction of further development.

References:
[1] A. Ivanov: „Vereinfachte Ansteuerung gedruckter Elektrolumineszenz-Displays mit passiver Matrix“, in Proc. 5. Landshuter Symp. Mikrosystemtechnik, 2016, Landshut.
[2] A. Ivanov, M. Wurzer: „Integration of Screen-Printed Electroluminescent Matrix Displays in Smart Textile Items – Implementation and Evaluation“, in Proc. 21th European Microelectronics and Packaging Conf., Sept. 2017, Warsaw.
[3] A. Ivanov, P. Tippmann-Krayer, M. Brandl, M. Kollmannsberger, C. Ströber: „Smart Foil Display – gedruckte Anzeige in einer praktischen Anwendung“, in Proc. Symp. Elektronik und Systemintegration, 2018, Landshut.
[4] A. Ivanov: „A Printed Electroluminescent Matrix Display: Implementation Details and Technical Solutions”, in Proc. NordPac 2018, Oulu. DOI: 10.23919/NORDPAC.2018.8423861.
[5] A. Ivanov: “Implementation of Flexible Displays for Smart Textiles Using Processes of Printed Electronics”, in Proc. NordPac 2019, Lyngby. DOI: 10.23919/NORDPAC.2019.8760351.