Metal Button Touch Reference Design with Tactile Feedback
Inductive sensing technology allows designers to rethink many of the problems that have existed for many years. Today, I will show you an advanced method of button design; in this method, you no longer need to use any moving parts.
Traditionally, buttons on appliances and consumer electronics use a resistive touch solution; this solution relies on mechanical buttons for normal functionality. The use of moving parts is susceptible to long-term stability and looks unattractive. This method also fails to achieve a complete seal of the housing, which also makes it vulnerable to moisture and other contaminants.
Capacitive buttons have solved many problems with mechanical buttons, such as stability issues, but capacitive buttons are still affected by foreign substances, such as water droplets on the surface of the button. In addition, sometimes it is impossible to operate the capacitor button with gloves.
Inductive-to-digital conversion (LDC), which supports metal touch technology, solves these problems while at the same time enabling stylish and very reliable buttons. Its housing can be made of a single piece of metal (as shown in Figure 1), which makes it highly cost-effective and is not affected by the moisture environment.
Figure 1: ToM design with four buttons
The sensor is a printed circuit board (PCB) coil inside the enclosure that is isolated from the outside environment. LDC takes advantage of the relationship between inductance and metal proximity, allowing LDC to translate the metal bending caused by the user's button press into a detectable inductance change. The use of TI's 28-bit LDCs, such as the LDC1612 and LDC1614, can detect submicron changes in metal proximity, which is completely invisible to the naked eye and does not require significant power.
Figure 2 shows a button application with a 20mm diameter circular button and a 0.25mm thick aluminum sheet. The height of this button is nominally 0.55mm away from the PCB coil. In general, a button press will result in a 5 μm bend.
Figure 2: Metal bending caused by button press
The LDC1612 features a configurable resolution and sampling rate for maximum flexibility in human-machine interface and metal bending distance design. In this example, the LDC1612 is configured for 155 SPS and 13-bit resolution. At a nominal 0.55 mm proximity, this configuration is sufficient to detect metal bending within 5 μm. A microcontroller can process data to detect when the inductance value exceeds a preset threshold. Haptic feedback events can also be supported to provide haptic feedback and tell the user that a button has been pressed.
Figure 3: LDC1612 output response when button is pressed four times
Figure 3 shows the LDC1612 raw output and threshold settings when the button was pressed four times. When the LDC output passes the threshold, the microcontroller can indicate that a button press has occurred and triggers a tactile response. Depending on the desired strong or weak button press detection, a higher or lower threshold can be set.
For a complete design using the principles I talked about in this article, check out the TI Button's TI Designs reference design that supports tactile feedback.
Obviously, thanks to the inductor technology and post-processing, we have a completely new understanding of the button. The possibilities are endless. Please leave us a message below to tell us which button applications you wish to improve.
ZGAR PCC
ZGAR electronic cigarette uses high-tech R&D, food grade disposable pod device and high-quality raw material. All package designs are Original IP. Our designer team is from Hong Kong. We have very high requirements for product quality, flavors taste and packaging design. The E-liquid is imported, materials are food grade, and assembly plant is medical-grade dust-free workshops.
From production to packaging, the whole system of tracking, efficient and orderly process, achieving daily efficient output. We pay attention to the details of each process control. The first class dust-free production workshop has passed the GMP food and drug production standard certification, ensuring quality and safety. We choose the products with a traceability system, which can not only effectively track and trace all kinds of data, but also ensure good product quality.
We offer best price, high quality Vape Device, E-Cigarette Vape Pen, Disposable Device Vape,Vape Pen Atomizer, Electronic cigarette to all over the world.
Much Better Vaping Experience!
E-Cigarette Vape Pen,Disposable Device Vape,Vape Pen Atomizer,Latest Disposable E-Cigarette OEM vape pen,OEM electronic cigarette
ZGAR INTERNATIONAL(HK)CO., LIMITED , https://www.szvape-pods.com