blog banner

What are the properties of Membrane switch assembled with touchscreen?

What are the properties of Membrane switch assembled with touchscreen?

Jul 23, 2021

Capacitive Sensors – A Brief Introduction

Capacitive sensors, which are common in membrane switch assembled with touchscreen, consist of many conductive electrodes embedded in a transparent dielectric material. The electrodes themselves are very thin, made of an almost completely transparent material and are not visible to the naked eye.

Consider the simplest configuration, which consists of two arrays of electrodes located at 90 ° to each other, as we can see in below.

Membrane switch assembled with touchscreen

An illustration of the main components of a capacitive sensor for a touchscreen

When a differential voltage appears between any two or more electrodes, an electrostatic field is generated. Although the field is strongest in the area between and around the electrodes, it also acts at some distance from them. When approaching this area of ​​a conductive object, the fields change, and it becomes possible to measure the resulting change in capacitance between the two active electrodes.

It is this difference in capacitance that is common to determine the position of the finger touching membrane switch assembled with touchscreen. When a potential difference occurs in a subset of the electrodes, the other electrodes will either be electrically isolated individually, or all are electrically connected but electrically isolated. Thus, they will have some permanent but unknown potential.

Model of a capacitive sensor in a wristwatch

For this relatively small device, we can model the entire structure; the size of the sensor is only 20 x 30 millimeters, and the distance between the electrodes is 1 millimeter. For larger touchscreens, it makes more sense to look at only a small portion of the screen.

Capacitive sensor model of the wristwatch

A capacitive sensor comes into the glass (transparent) watch dial. The watch strap and case we can see for visualization only. This area encompasses the membrane switch assembled with touchscreen, the finger and the air volume around the watch. We can argue that the influence of the volume of the surrounding air decreases rapidly as the size increases.

Common boundary condition

In this case, the zero charge condition comes for the boundaries of the air volume. Thereby it simulates the boundary of free space. In addition, the Ground boundary condition is good for the two parallel electrodes. Thus it locks the voltage field to zero. The Terminal boundary condition is easy to apply to the two perpendicular electrodes, which fixes a DC voltage across them.

The Terminal boundary condition will also automatically calculate the capacitance. All other boundaries are modeled using the Floating Potential boundary condition and common membrane switch assembled with touchscreen.

A visual representation of the boundary conditions that apply to the wristwatch model

Finite Element Model Render – Finger, electrical shield, and all electrodes are simulated using the Floating Potential boundary conditions. A potential difference has occurred across two electrodes. Clock face partially obscured. All other surface uses the boundary conditions Electric Insulation.

Membrane switch assembled with touchscreen 2021

A volumetric mesh is easy to apply in the air and on the watch face. For simplicity, the mesh shows only on some surfaces. The Floating Potential boundary condition is common to represent a set of surfaces through which charge can freely redistribute. This condition is for modeling the boundaries of an object with a constant but unknown electric potential.

Materials use

Only two materials are common here. For most areas, a pre- fabricated Air material is common with the dielectric constant set to one. To assign a higher dielectric constant to the membrane switch assembled with touchscreen, a prefabricated Quartz Glass material is common. The boundaries of the finger also have the floating potential boundary condition.

Although the screen is a multi-layer structure of different materials, we assume that all layers have the same properties. Therefore, we do not need to explicitly model the boundaries between layers: they are all considered as a single area.

Image with color rendering of the electric field

It makes no sense to consider the device in detail in the context of this material. Only the key block is important here. The membrane keypad has an elastic rubber membrane under each plastic button.

When pressed, it flexes and closes two contacts that locate under it. And they are responsible, in turn, for a certain action.

Due to the simplicity of design and the use of relatively inexpensive materials in production, the membrane keyboard as a whole is much cheaper than mechanical counterparts, even the most budget ones. Often the consumer guides by this. He does not consider that it will take a long time to type a lot of text, getting pleasure from it, on membranes.

The device and principle of operation of a mechanical keyboard

Precise solutions using adaptive mesh refinement

The accuracy of the results depends on having a finite element mesh fine enough to resolve spatial variation in the stress field. Although we don’t know ahead of time where significant field variations will occur, we can use adaptive mesh refinement to let the program figure out where finer elements we need.

In this article we want to see everything there is to know about membrane switch assembled with touchscreen: what they are the various types that exist, the production methods and, consequently, when and why it can be a good idea to choose them.

MEMBRANE KEYBOARDS: WHAT ARE THEY?

The membrane keyboard is a particular type of keyboard, generally simpler than a classic computer keyboard, for example, but no fewer complexes.

According to its purpose, each membrane keyboard comes in a specific way, precisely to meet the needs require by the tasks it will have to carry out.

Types of membrane switch assembled with touchscreen

There are many types of membrane switch assembled with touchscreen on the market, each of which is perfect for a particular type of use. For example, there are adhesive keyboards, a particular type of keyboard that is easy to apply to any type of surface, very convenient in particular to glue on the medium that the keyboard will control. There are two types of adhesive keyboards:

Dome keyboards:

These have a sort of “dome effect”, thus appearing slightly rounded on the keys. This happens precisely due to the insertion of a small metal dome under the keys that emits the classic “click” when pressed. The operator thus has real feedback after pressing the button.

Bubble keyboards:

In this case the keys we have in the classic bubble shape in advance. Feedback is softer and less effort requires pushing the button. Then there are keyboards with rigid support. These keyboards are easy to assemble, but we can guess, unlike the previous ones, they do not have all the advantages come by the adhesive.

Durability of membrane switch assembled with touchscreen

One of the main problems with membrane switch assembled with touchscreen is that rubber parts tend to lose elasticity over time. The same thing happens with heavy use, which is typical for working with texts or for gambling addicts.

As a result, the diaphragms wear out and stop responding much earlier than the spring mechanisms. In terms of numbers, the average durability of membrane keys is design for 5 million keystrokes, while for mechanics this figure exceeds 50 million.

Tactile sensations

This characteristic is how each keystroke feels to the touch. If you take a membrane keyboard, the movement of its buttons is very soft, indefinite and difficult to feel with your fingertips. In the mechanical version, the opposite is true – the clicks are perfectly track by touch, which is very useful for those who type or play blindly, that is, without looking at the keyboard.

Response speed

The diaphragm for full-fledged operation requires full pressing until it stops. This slows down the process by constantly pressing the same button. In membrane switch assembled with touchscreen, pressing comes at half the stroke. It increases the speed. This characteristic is more important for gamers than for those working with a set of texts.

Types of membrane keyboards

  • Aluminum
  • Plastic
  • Vetronite

Obviously, each of these materials guarantees performance of durability and different weights, even at different prices. Finally, there are also backlit membrane keyboards, and membrane switch assembled with touchscreen excellent if you have to operate in low light conditions.

HOW TO MAKE MEMBRANE SWITCH ASSEMLED WITH TOUCHSCREEN?

We deal exclusively with the customization of the upper part of the membrane keyboard and membrane switch assembled with touchscreen that is the part that will then become the interface that the user will see during use. The customization process treats in detail. It starts with the development of the graphics, always creative, functional and extremely professional.

Secondly, printing comes out, almost always of the direct UV type. At the same time, we also take care of crowning the keys and precisely cutting this surface layer so that it adheres perfectly to the keyboard. In case the keyboard also needs a support, we are able to create this too, usually with plastic or Plexiglas.

CONCLUSIONS

In this article we have therefore explored the world of membrane keyboards and membrane switch assembled with touchscreen explaining how can be useful to you to create the right instrument for your needs. The possible applications of membrane keyboards are many, for example industrial, in electrical panels or in various user devices.

All

    Loading