Developing a MIL-SPEC-compliant touchscreen solution for devices used by the military

• Vibration test as previously quoted 514.6 Cat 24 E-1 General Minimum Integrity.

• Drop/shock testing to follow Procedure 1 Mil-Spec 810 (Function Shock) 516.6 Procedure 1 Functional Shock

Our customer was looking to equip a handheld device with a touchscreen that could be used by soldiers in the field. The primary challenge was the right choice of the touchscreen type that would accommodate requirements, low power, use with gloves, moisture, and meeting mil-spec shock and vibration requirements.

Since the device was designed for the military, all of its components – including the touch screen – had to comply with DoD requirements arising from the prospective device use in the field.

Our Solution

The customer wasn’t sure whether to choose the PCAP or resistive touchscreen as they were concerned about the use of gloves and moisture. Our team demonstrated how a PCAP touchscreen with a high-performance controller exceeded the performance of a resistive touch screen.   Implementing the Ilitek controller, our team convinced the client that PCAP is a superior choice for this application, developed in line with the current industry trends.

We solved the problem related to static discharge for our customers and helped the company in developing its product.

Our solution comprised three elements:

• Cover glass

• PCAP sensor

• Display

Cover Glass

To develop the touchscreen, our engineers had to make several decisions about the type of glass to be used, its thickness, and the required impact and scratch resistance.

PCAP Sensor

The PCAP sensor was optically laminated to the back of the glass. It needed testing to ensure that it worked with gloves, moisture, and other parts of equipment that soldiers might be wearing. Testing determined that the PCAP touchscreen meets all of these requirements.

Display

Finally, our engineers had to design a display that would provide excellent visibility in both direct sunlight and low light. The backlight controller had to control display illumination down to 1% with fine resolution and avoid startup inrush current that exceeded system capability.

Electronics

Our team had to solve challenges related to brightness and power consumption. The handheld device where the touchscreen was to be implemented was battery-operated, so energy consumption had to be kept to a minimum.

Another issue was interfacing the display with the main board of the system. The board that our customer was looking to use was designed with the OLED display in mind. That’s why our team had to adapt the display driver to the TFT display used in the application.

Testing

Our team had to solve challenges related to brightness and power consumption. The handheld device where the touchscreen was to be implemented was battery-operated, so energy consumption had to be kept to a minimum.

Another issue was interfacing the display with the main board of the system. The board that our customer was looking to use was designed with the OLED display in mind. That’s why our team had to adapt the display driver to the TFT display used in the application.

• Vibration test a 514.6 Cat 24 E-1 General Minimum Integrity.

• Drop/shock testing to follow 516.6 Procedure 1 Functional Shock (20G) as required for soldier-carried equipment and in-flight transit; not ground equipment transit requiring (40G).

Result

Our customer got a well-designed and thoroughly tested touchscreen, a critical component for the company’s new device.

The project is currently in the pre-production stage. We have manufactured several hundred units that will undergo further testing and evaluation by the military.