Capacitive touch panel technology uses the body's sense of electricity to work. The capacitive touch panel is composed of a composite glass screen. The interlayer and inner surface of the glass screen are coated with a layer of ITO respectively. The outer surface is covered with a thin layer of silica glass protective layer, and the interlayer ITO coating is used as the working face. Four electrodes are drawn from the four corners, and the inner layer, ITO, is a shielding layer to ensure a good working environment.
When a finger touches the metal layer, due to the electric field of the human body, the user and the surface of the touch screen form a coupling capacitor. The capacitor acts as a direct conductor, and the finger draws a small current from the contact point. The current flows from the electrodes at each of the four corners of the touch screen, and the intensity of the current flowing out is proportional to the distance between the four poles. The controller calculates the exact position of the touch point by calculati ng the proportion of the four currents.
The capacitive touch panel solution can meet the needs of most devices with PCB, capacitive and single-layer indium tin oxide (ITO) touch screen methods. Factors such as size and power consumption are also critical when choosing the smartest and safest solution. As a professional metal core PCB manufacturer, Komkey can provide suitable solutions for you. Welcome to consult and purchase!
Capacitive sensing technology can be found from industrial, automotive, medical devices to common terminal products such as smartphones and tablets. The rapid popularization of capacitive touch technology is inseparable from its ability to easily enhance the user experience of the device, allowing manufacturers to switch from traditional switches to more attractive touch functions.
Capacitive sensing technology also helps to reduce the number of mechanical components of the device, thereby extending the service life of the device and reducing its size. The combination of these features, as long as they are properly designed, calibrated and controlled, can make products with capacitive sensing functions more attractive.
Capacitive sensing technology is also widely used in touch buttons and slider functions, especially in consumer, commercial and industrial applications, but the most common target applications are touch panels and touch screens. To design a sensor with low cost, responsiveness, and energy-saving that can operate stably in a complex environment is already a general demand in the current market. However, some requirements are still very challenging for engineers.
For the user interface, the most basic touch sensing application is the projected capacitive touch technology touchpad people are familiar with. These designs consist of a matrix of rows and columns of conductive material layers between glass plates. Applying a voltage to this grid creates an electric field, which can be measured at each intersection. When a conductive object, such as a human finger, approaches and touches a PCT panel, the electric field at the contact point changes and capacitance difference is created.
The PCT technology can be implemented in two ways: self-capacitance touch panels and mutual-capacitance touch panels.
The self-capacitance design is to wind grounded copper foil on the printed circuit board (PCB). This creates a parasitic capacitance between each sensor on the PCB and the surrounding ground copper foil and the electric field lines on the top of the sensor. As the fingers get closer, additional capacitance is introduced, causing the electric field to distort. The disadvantage of this design is that it can only detect one touch at a time. Therefore, although it is a very cost-effective model, it is only suitable for devices with limited space behind the screen.
However, the mutual capacitance sensing method, which refers to the capacitance existing between any two charged objects, can realize multi-touch detection, which is very suitable for the design of complex devices equipped with large displays. When the finger touches, the presence of the finger is detected by the decrease of the two capacitances. Most importantly, each intersection has its own unique mutual capacitance, which can be tracked independently.
For a mutual capacitance touch panel, the presence of a finger will cause the capacitance to decrease. For a self-capacitance touch panel, the presence of a finger will increase the capacitance, thereby determining the position of the finger.
Multiple capacitive touch panels can be combined to form a touch screen or touch panel, which is used to determine the position of one or more fingers on a single glass plate. Multi-touch technology has been widely used in devices with limited space, such as mobile phones, tablet computers, and high-end wearable devices. It can be divided into three types of applications: PCB, capacitive, and single-layer indium tin oxide touch panels.
PCB touch panels are basically two or more PCB self-capacitance touch panels placed near the display. For prototype construction and commercial equipment without space constraints, the use of low-cost standard PCB manufacturing processes is ideal. When designing touch buttons for PCB touch panels, size is usually a key parameter to consider. However, the shape and the pad pitch (the distance between the buttons) should also be taken into consideration to minimize false detections.
The capacitive touch panel has two vertically stacked layers of highly conductive material—ITO conductive layer, one for the columns and the other for the rows. The key feature of this design is that each intersection has its own unique mutual capacitance, which can be independently tracked by the touch controller.
The capacitive touch panel is very suitable for many applications because it can provide multi-touch and is easy to configure to support two or more touch pads. In addition, its ultra-thin module design is ideal for applications with larger screen sizes.
In addition to capacitive touch panel, Komkey can also supply membrane panel and other kinds of panel. Welcome to select.
The single-layer ITO touch panel method provides many advantages of capacitive touch panels at a lower cost. The biggest difference is that the number of touch panels is preset, so they cannot be changed flexibly like capacitive touch panels. The predefined characteristics are extremely beneficial to the size and the arrangement of the controller's computing resources. From a manufacturing point of view, this method is very similar to the capacitive touch panel, but a capacitive touch panel uses only a single ITO layer.
Before determining the most suitable model for our application, we need to weigh all design advantages and disadvantages. On the whole, most device design and functional requirements can be easily addressed with a capacitive touch solution, but other factors such as size and power consumption are also critical in determining which solution is the smartest and safest for a particular case.
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