Touch Screens Systems

Touch Screens Systems

When designing the cTouch 2, Spring had to design a product from scratch that would fit in with today's high-end consumer electronics. This product showcases our ability to work on every aspect of electronic product design, from custom PCB and firmware to custom enclosures and high-end graphical Uis.

The product has many advanced features: UPS (uninterrupted power supply) built in, ethernet, 10 inch TFT colour touch screen display with SBC (single board computer) to provide rich, fluid UI. We also provide an online update system accessible from the UI or via the web interface.

Enclosure

It was very important from the beginning that this device should blend in with other high-end consumer devices. With this design criteria in mind it was obvious we would require a custom enclosure, but with projected sales making this a low volume product, it was always going to be difficult. The final solution was to use a sheet folding process involving CNC routing and forming. The shape and fit were all designed in-house in CAD. Going for a forming process instead of injection moulding allowed us to reduce tooling costs and supply a full custom enclosure for a low volume product.

The touch screen panel is securely mounted in the lid along with the LCD. these two parts are bonded together to ensure there is no calibration drift over time.

To make mounting the unit simple, we included mounting holes for the 75mm VESA standard. We supply the unit with a stand of our own design. The stand is manufactured from 4mm steel, laser cut and formed, then powder coated.

Custom Electronics

Using an SBC is a sensible choice when dealing with large scale graphical displays. By utilising off the shelf components, you can save design time and speed up the time to market. However, the downside is that the physical shape or specification of the SBC may be changed midway through your production run. This can and will happen so we are always ready with alternatives. The second problem is that they will never have all the features you require, so it is sensible to incorporate an additional custom board. In this product, it takes the shape of a small PIC based circuit that talks to the SBC via serial (UART). This provides important features that the SBC lacks, each feature represents both hardware and firmware design.

1. RS485:  we use this to interface to various control networks and is an industry standard for controlling equipment.

2. Voltage regulation: for the SBC we take 12V (external PSU) down to 5V using an internal switch-mode supply. Designing switch mode regulators are more difficult than linear regulators, but achieving 90% efficiency and low heat operation is not possible with linear regulator designs.

3. UPS: once a power fail (loss of external PSU) is detected, we can switch over to the internal lithium battery. This will hold up the SBC for around two minutes, allowing the unit to wait to see if the power returns, or to perform an orderly shutdown.

4. RTC (real time clock): the SBC does not have a battery-backed clock on board, so this is important to set the clock time when no network connection is present.

5. LED notification: a small window at the bottom of the unit allows us to light up a row of RGB LEDs, giving another dimension of user notification.

Graphical UI

To stand out in the world of consumer touch electronics, considerable design time must be spent on the user interface. It has to be easy to use, intuitive and engaging. Using the Qt graphical library we were able to jump straight into designing and implementing the UI. All graphics were designed in-house using vector formats to support any resolution. The UI code was written in Javascript and QML while the back end code was written in C++. As the base OS is Linux, interfaces between the server code and OS were written using script files, to allow us to migrate the OS with minimal effort.

Web Inteface

Using a web interface to configure the unit facilitates remote configuration as well as allowing the users to download and upload configuration files from a computer.

Networked

Units can talk to each other using an SSL encrypted link, to provide remote control and status monitoring. As this feature uses standard internet technology, the remote unit can be in the room next door, or halfway around the world.

M P Touch 2 - Data Sheet