6.0-inch G+G Structure Surface Capacitive Touch Panel for Smart Electronic Equipment
Dr Pan: Welcome to DISPLAY Museum. I am Dr Pan, the curator of Museum.
Greg: Hello, Dr Pan. I am Greg. I came here to learn about surface capacitive touch screen.
Dr Pan: Hello, Greg. Surface capacitive touch screen is rarely used today. It is low cost, simple working principle and simple design circuit,
Dr Pan: but difficult to achieve multi-touch.
Dr Pan: Let’s look at the structure. From top to bottom, scratch resistant top coat, hard coat with anti-glare, the first two layers are protective layers, they provide a good working environment; electrode pattern, conductive coating, the third and fourth layers are functional layers, the bottom layer glass is supporting layer.
Dr Pan: The same phase voltage is applied to the electrodes on the four corners, then a uniform electric field will be forming over the panel.
Dr Pan: When a finger touches on the panel, electrical current will flow from the four corners through the finger. Ratio of the electrical current flowing from the four corners will be measured to detect the touch point.
Dr Pan: The measured current value will be directly proportional to the distance between the touch point and the four corners.
Dr Pan: The location of the point of contact is calculated by the controller and transmitted to the PC.
Greg: Dr Pan, from my experience, we can’t see surface capacitive touch screen very often. Is it true?
Dr Pan: That is right. Surface capacitive touch screen is obsolete.
Dr Pan: It is replaced by projected capacitive touch screen and there are 4 reasons.
Dr Pan: 1. It is the most important reason. The uniform electric field is easily affected by the environments, such as temperature, humidity, dust, greasy dirt and so on.
Dr Pan: Therefore, the touch points will be miscalculated and shifted from time to time.
Dr Pan: 2. It is not responsive to gloved hand or pen writing.
Dr Pan: 3. It can not support multi-touch.
Dr Pan: 4. There is a problem of color distortion due to the uniformity of each wavelength in four layers of composite materials
Dr Pan: and it causes image blurred because of light reflection in each layer.
Greg: Thank you, Dr Pan. Now I got it.
Dr Pan: Welcome to contact us if you have any question.