A capacitive switch detects the presence or absence of a conductive object, such as a nger , by measuring changes in capacitance. This means there are no mechanical components within the switch – eliminating any potential mechanical failure and offering excellent durability in even the harshest environments.
Our capacitive switches possess a self-contained system that gives extensibility to the design of your product. We are able to incorporate these switches with many different features including backlighting, touchpads, touchscreens, proximity sensors and more to create a product exclusive to your application. Common applications for capacitive switches include automobiles, computers, cell phones, consumer electronics, and industrial machinery.
CAPACITIVE SWITCH CONSTRUCTION
A capacitive switch consists of three main sections: the graphic overlay, circuit, and backer. The overlay displays your graphics and can also include windows, embossing, coatings, adhesives, and selective texturing. The switch will either be a Flexible Printed Circuit (FPC) or a Printed Circuit Board (PCB). The backer is the nal part of your capacitive switch, and may or may not include an adhesive that must bond to your specie substrate.
CAPACITIVE SWITCH MATERIALS
The most common materials used for overlays are plastic, acrylic, and glass due to their durability and versatility. Any adhesives that are used on the overlay must make good mechanical contact, as air gaps reduce the dielectric constant and sensing uniformity. The adhesive must also be non-conductive. A commonly used acceptable adhesive is the 3M 200MP series acrylic adhesive (3M467, 3M468).
Keetronics most commonly uses the Pantone Matching System or CMYK color model to match custom colors. We can match to a specied or provided color. If you wish to submit a sample, we prefer that it be 2 x 2” in size.
The capacitive switches have one or two electrodes on each key (capacity varies once contact is detected). These electrodes are printed on a polyester film using conductive inks (can be transparent) which allows us to create keys with different sizes and shapes, including rotors and sliders, opaque keys or fully transparent and flexible.
The capacitive switch has three elements; the conductive sheet where the electrodes, the control module and the front cover is placed. The cover can be of different materials and thickness, like Glass, PMMA, Ployetser, Plastic etc.
Possibility of UV resistance High water tightness, Waterproof and fog resistant Anti-vandal No mechanical elements Unlimited lifespan Flexible Light-weight Adaptable to complex shapes Easy assembled Adhesive Clean.
TYPE OF SWITCHES:
The capacitive switches are divided into two types:
1] Self -capacitance or Surface capacity and 2] Mutual capacitance or Projected capacity.
It has a unique electrode per key. When in contact with the electrode, its capacity increases. The controller is responsible for measuring the capacity in respect to ground. In case of needing distance between small keys, the «mutual capacitance» technology is recommended.
It has two electrodes per key. The controller is responsible for measuring the capacitance between them, and by bringing your finger near the electrodes, the capacity between these decreases. These types of switches are particularly advantageous in a battery connected devices and devices with a large number of keys, as it can have a matrix structure.
The control module is responsible for managing the sensibility and warning when interactions over buttons and sliders occur. These are sent by a standard l2C protocol or by the manufacturer to perform the actions set in the machine or tool. The control module is made with “Printed Electronic” techniques, more specifically, with UFPC. This technology allows copper to be printed on a low-cost plastic film of type PET, PEN, PEI, etc. generating flexible electronic circuits, with the possibility of electronic SMD components soldered on plastic substrates by conventional soldering processes.
ROTORS AND SLIDERS:
The capacitive switches can incorporate both rotors and sliders. This may serve to replace potentiometers and encoders.
These elements have the same structure as conventional capacitive keys, except that the keys are more united and distributed with determined shaped. The rotors and sliders can have various different channels (electrodes) for each element. The most common are 3 and 4 channels.
Like the capacitive switches, the rotors and sliders can be «self- capacitance» or «mutual capacitance».
They are also fully customizable and can be designed in different sizes, thickness and shapes.
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