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Smartwatch Touch Panel

In recent years, smartwatches were introduced to provide users instant access to digital activity. Smartwatches have built-in computing devices that can perform almost all the basic mobile phone functions. They are light-weight which allows the user to wear a smartwatch all the time to get access to digital data 24/7.

Since smart-watches have made their way to the market, the demand for them is continuously increasing due to their touch screen capabilities, features, weight, reliability, quality, and durability. With the latest smart-watches, users can control music, answer phone calls, and check notifications all without taking out their mobile phones.

The list does not end here as now smart-watches have built-in sensors that are continuously tracking your blood pressure, heart rate, walking distance, and other health metrics. Many also have sleep monitor sensors that encourage users to not only wear their smart-watch during the day but also at night. 


Mobile phones and smart-watches fundamentally interact through touch panels. Mobile phones have comparably larger touch screens which makes them more comfortable to operate. However, some might have reservations about getting a smartwatch due to the small and limited interactive touch screen. The good news is, there is a solution to overcome the issue some users may have with smart-watches. The issue can be solved by expanding the touch area to the back of the user’s hand.  


A recent study found that the solution is for the user to be able to make gestures on the back of their hand and have those gestures translate to on-screen actions. With the help of compact IR (infrared) line array sensors embedded on one side of the smart-watch, it can detect fingers’ positions when they interact with the back of a hand. Using a finger position sensor around the smart-watch to detect the position of fingers is a new revolution in this industry.

The infrared sensor is an electronic device that can detect and measure the radiations in its surroundings. It provides output in digital and analog form. 

Around Device Interface (ADI):

Around Device Interface (ADI) is the device that helps sense the finger gesture and position at the back of the hand. It will make interactions with the smart-watch by sensing the finger positions and reflected IR intensity. Around Device Interface is an efficient way to expand the interaction space on small devices like smart-watches. 


Now let’s understand the ADI System, how it is developed, and how it will work. While sensing the finger position when it touches the hands’ back, there are two IR emitters and sensors located along one side of the smart-watch. These are sensors with lenses placed along one middle side of the smart-watch. Simultaneously, there are two emitters used on the left and right sides of the lenses so they can cover the hand’s back.

To measure the fingers’ position and gestures, image sensors and a 128×1 array photodetector are used so they can detect the light reflected by fingers and emitted from IR light-emitting diodes. There are wide-angle IR LEDs used to cover the large interaction surface within a short distance. This short distance will help to reduce the LED power consumption. There is an IR band-filter used to eliminate the external light.

Evaluate Performance:

When a user interacts with the back of their hand, IR intensity will be high at the finger’s position because it is very close to the emitter. It determines the two-dimensional coordinates from pixel intensity relative to the IR line image sensor in each frame. There are six degrees of freedom (6-DoF) industrial robots used to detect and measure the peak position and IR intensity at each position.

The module’s power consumption is measured when the robot interacts every second, 10m having a screen off. There is a sense resistor applied between the power supply and the developed system to measure the developed module’s power consumption.

For performance evaluation, there is a mock test performed by taking a robot tip and controlling it on the back of the hand, and then check the performance of click motion at different positions. After 50 repetitions, the maximum intensity error was 11.7%, while the maximum pixel error was 8.2% 

Finger Touch Recognition:

Since the smart-watch is worn on the wrist, there are high chances that the system will detect the unwanted motions as well. For example, you may unintentionally touch your hand’s back, and the smart-watch starts performing unwanted actions.

For this, the system must know the user’s touch status to recognize if a user intentionally interacts with the smart-watch. There are inertial motion signals from a gyroscopic sensor embedded in the smart-watch to measure the time series similarity between the template signal and incoming signal with a dynamic time warping algorithm.

To get accurate operation of the algorithm on the smart-watches, there is a Sakoe-Chiba Band constraint used to have a width of 10% template signal length. 

Implementation of Smartwatch AID Touch:

There is a developed graphic user interface (GUI) based on the expanded module and around the touch panel for a smart-watch to implement the smart-watch AID touch. When IR sensors sense finger movements and detect the actions through gyroscopic, click and swipe gestures can be read through the smart-watch interface.

Users can control smart-watch UI and applications through the developed touch interface. A user can swipe or make gestures to interact with the smart-watch interface. So if a user swipes rightward or leftward, smart-watch GUI will show the user screen display moving horizontally. 

For example, to access the menu, you can swipe leftward. Similarly, upward/downward is assigned to scroll in a vertical position. It is similar to mobile phone touchscreen controls where you use the mobile phone’s contact list and scroll upward/downward to explore the contacts. A click on the hand’s back allows you to select a particular option.

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While we are talking about AID touch and GUI, the display of the smart-watch is also very important. There are different types of displays and each has its specifications and benefits. 


There are many display technologies available today in the market. Some of them are:

          -Electroluminescent display (ELD) 

          -Liquid crystal display (LCD)

          -The light-emitting diode (LED) backlit LCD

          -Thin-film transistor (TFT) LCD

          -Light-emitting diode (LED) display

          -Active Matrix Organic Light Emitted Diodes (AMOLED) display

          -Plasma display (PDP)

          -Quantum dot display (QLED)

          -Organic Light-Emitting Diodes (OLED) display

          -Smartwatches are traditionally manufactured with OLED displays.


OLED stands for Organic Light-Emitting Diodes. It is a flat light emitting technology that is made by placing a series of organic thin films between two conductors. A bright light will emit when there is an electrical current applied. OLEDs do not require any backlight as there are emissive displays and are more efficient than LEDs.

Emissive displays are those displays that emit light from each pixel. A combination of this light that emits, with different colors and intensity, makes an image that users see.

Some of the benefits of the OLEDs are the following:

          -OLED does not face any motion lag or blur issues because they are built on technology that has the                  fastest response time rate. They have a faster response time than LCDs.

          -Most of the OLED displays feature Ultra High Definition UHD or 4K options.

          -Unlike Custom LCD Displays, OLED has very thin and flexible touch panels that reduce their screens’                  weight and thickness.

          -OLEDs are built on the most energy-efficient technology. They need a  very low power to operate.

          -OLED TV and monitors will have the benefit of no screen burn-in.

          -OLEDs have almost a perfect viewing angle. OLED pixel colors appear correct and unshifted even                        though the viewing angle moved from normal to 90 degrees.


There is a solution of ADI where users can interact with smart-watch without actually touching the touch panel, which can ultimately solve many small OLED screen problems that users are currently facing. The ADI technology is new and innovative and will take some time to make its entry into the market. Once this technology does hit the market, it will change the smart-watch space for the better. This unique and innovative technology will only increase the user experience. 

About E3 Displays:

We’re a global design and manufacturing company that helps the world’s most innovative companies define the future of their business display needs. With over 20 years of combined experience in display technology, E3 Displays has everything you need to develop and manufacture your custom touch display all in one place. With customer-centric solutions featuring strategic planning, competitive pricing, longevity, and support, we ensure the best products on the market to help you scale. In the end, displays are a centerpiece in any hardware that provides a very important visual message in your product. We want to ensure that the visual entity exceeds your optical and performance requirements.

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