Touch Screen, Touch Panel
Anyone who owns a smart phone, uses the self checkout lane at retail stores, or makes purchases at kiosks is well aware of the benefits and popularity of touch screens. Touch screens have virtually no moving parts and are therefore very durable and appropriate for frequent use in unlimited applications. The interactive experience and interface flexibility of a touch screen combined with ease-of-use and extreme durability are just a few reasons why touch screens have become so popular. Sensigraphics is a leading touch screen provider with core competency in the design, engineering, and manufacturing of touch screen assemblies to meet the most unique human-machine interface (HMI) requirements for our customers.
What is a Touch Screen?
A touch screen is a transparent switch that is placed over a visual display. The switch enables interaction through physical contact by detecting the presence and location of a touch. A touch screen is one of the easiest to use and most intuitive of all computer interfaces, a touch screen allows users to navigate a computer system by touching icons or links on the screen.
A touch screen consists of a conductive bottom layer of either glass or film and a conductive top film layer, separated by small, transparent spacer dots. A voltage is applied across the conductive surface. When pressure from a touch is applied to the top layer, it is deflected and makes contact with the bottom layer resulting in a voltage drop. This change is detected by the controller. By alternating the voltage signal between the top layer and the bottom layer, the X and Y coordinates of the user’s touch are computed. This permits the display to function as a control panel and allow human to machine interface.
Components of a Touch Screen
A touch screen typically has the following basic components:
- Touch sensor – A touch-responsive surface, typically a glass panel that is placed over a visual display monitor. The technologies vary slightly, but typically, the sensor registers change in electrical signal distortion to sense a touch event and location.
- Controller – An electronic device (PCB) is the interface between the sensor and the display. The controller takes information from the touch screen and translates it into information a computer can understand.
- Software driver – A computer program that enables the computer operating system and the controller to communicate.
Types of Touch Screens from Sensigraphics
To achieve the desired human to machine interface, there are a number of different touch screen technologies available. Sensigraphics offers a variety of touch screen technologies, including:
Resistive Touch Screens
The Resistive Touch Screen is the preferred solution for low-cost applications. It consists of a conductive bottom layer of either glass or film and a conductive top film layer, separated by transparent spacer dots. A voltage is applied to the conductive surface. When pressure is applied to the top layer, it is deflected and makes contact with the bottom layer resulting in a voltage change. This change is detected by the controller.
This technology is functional and economical for industries and applications such as food service, industrial controls, point-of-sale (POS), and handheld devices.
Resistive Touch Screen Features:
- Activation by finger, glove, or stylus
- High touch point resolution
- Low power requirements
- Value solution
- Reduced optical clarity
Capacitive Touch Screens
Capacitive touch screens have an all-glass construction with greater than 9H surface hardness. A transparent conductive indium tin oxide (ITO) coating is distributed over both sides of the glass substrate. An electrode pattern is printed around the perimeter of the glass to generate an alternating current over the top conductive layer. The touch of a conductive probe draws the current to the specific point of contact. The controller then calculates the location of the touch.
Capacitive technology provides durability, reliability, and enhanced optical clarity. However, it is restricted to touch sensitivity by conductive materials such as a bare finger or capacitive stylus. Popular industry applications include casino gaming machines, industrial equipment, ATM machines and point-of-sale (POS) kiosks.
The unique ability of this technology, is that it allows for multiple zones of touch to occur simultaneously. This can be accomplished due to an invisible grid of sensors on the back of the substrate that map the location of all fingers that come in contact with the screen. The grid pattern detects location of touch by determining relative levels of current within the matrix.
Capacitive Touch Screen Features:
- Activation requires either bare finger or capacitive stylus
- Extremely durable
- Excellent optical clarity
- Good resolution
- Very accurate
Surface Acoustic Wave
This technology is best suited for kiosks and Point of Purchase displays. It relies on piezoelectric transmitters and receivers arrayed along the edges of the touch screen. They transmit and receive signals at once, by converting the signal into ultrasonic waves. When you touch the screen, the waves fan out, are absorbed by the array of traces around the perimeter of the screen, and a touch event is directed to the point.
Surface Acoustic Wave Touch Screen Features:
- Most widely used touch technology
- Activation by finger, soft conductive stylus or some gloves
- Low Cost and wide range of sizes
Contact Sensigraphics for information on additional Touch Screen Technologies:
- Projected Capacitive
- Surface Acoustic Wave (SAW)
Common Features/Benefits of Touch Screens
Touch screens share these common features and benefits:
- Virtually infinite options for user interface design and flexibility compared to physical buttons/switches
- Easy to use interface
- Requires less space – integrated design eliminates the need for external keyboards and other components
- Sealing options can make touch screens highly resistant to environmental conditions
- Faster interface and convenience then keyboard or mouse
Touch Screen Design Considerations
When considering a touch screen application, use the following questions to help determine the right technology for you:
- Interface – What type of touch interface do you need, finger, gloved finger, both, or stylus?
- Options – Do you need touch buttons, drag and drop, or signature capture?
- Display Clarity – Is optical clarity a high consideration?
- Environmental - Will the touch screen be exposed to chemicals, liquids, or extreme weather conditions?
- Cost - What are your cost considerations?
Applications for Touch Screens
Below are just a few examples of touch screen applications:
- ATM machines
- Retail point-of-sale touch screen kiosks
- Satellite navigation systems
- Medical monitors
- Industrial touch screen control panels
- Tablet computers
- Casino gaming machines
Sensigraphics Touch Screen Engineering and Manufacturing Process
Sensigraphics utilizes state of the art equipment, lean manufacturing techniques, and quality management to provide clients with an exceptionally streamlined and efficient product development process. Benefits include reduced lead times, exceptional quality control, and very competitive costs.
How to Work with Sensigraphics for Standard and Custom Touch Screens
Sensigraphics works with customers at various stages of the product development process, from design, prototype and production. Sensigraphics offers design and engineering support for early-stage product development or can simply provide a quote for the desired quantities of fully-engineered and ready-to-manufacture touch screens.
Sensigraphics recognizes that each project is unique. With over 30 years of experience, Sensigraphics’ team of engineers and designers is dedicated to bringing expertise, innovation, and quality to every project.
Terminology Note on Touch Screens
This product is often spelled touch screen (two words) or touchscreen (all one word). A touch screen is also referred to as a touch panel. Other variations include touch screen overlay, panel mount touch screen and touch screen terminal.
Contact Sensigraphics for Touch Screens and all Human-Machine Interface (HMI) Requirements
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