The design of Projected Capacitive Input (PCI or PCAP) control boards can be divided into two categories:
PCAP Control Board Solution
The first approach is to mount a control IC on a separate PCB (see below). The analog signals will transmit from the touch sensor through the FPC (flexible printed circuit) to the PCB. The control IC firmware will convert this capacitance data into digital touch position data. This digital data will be transmitted further to the host computer via an onboard serial interface such as USB, UART, I2C, or RS-232.
Advantages of Control Board design are:
- Higher Design and integration flexibility due to separate control board and touch screen.
- Faster prototyping with lower tooling and production cost.
- Supports thicker cover glass.
- Better noise filtering capability, less susceptible to interference from noise produced by other components.
Attention should be paid to the length and location of the FPC so as to prevent interference to the weak analog touch signals caused by external noise. Available PenMount PCAP control boards:
- PM1210 P2-06 5"~7.9" 15 24 USB, I²C, UART, RS-232
- PM1310 P2-08 8.4"~10.4" 23 35 USB, UART, I²C
- PM1410 P2-08 x 2 12.1"~15.6" 38 57 USB, I²C, UART, RS-232
- PM1415 P2-08 x 2 12.1"~15.6" 38 57 USB or I²C
- PM1710 P2-08 x 2 15.6"~24" 44 76 USB, RS-232
- PM1711 P2-08 x 2 15.6"~24" 44 76 USB, UART, I²C
- PM1715 P2-08 x 2 15.6"~24" 44 76 USB or I²C
In terms of the noise interference issue, the PenMount’s third generation PCAP controller can meet EMC Level III certification. Testing was performed according to the following standards:
- IEC61000-4-3 Level III (RS test, Passed 10V/m, criteria A)
- IEC61000-4-6 Level III (CS test, Passed 10Vrms, criteria A)
The PenMount’s third generation PCAP controller utilizes a comprehensive hardware design paired with firmware featuring next-generation frequency hopping algorithm technology to effectively reduce the probability of noise interference and allow significant enhancement in the controller’s anti-noise ability.
At the same time, the PenMount PCAP controllers also supports gloved touch functionality. Even though there are many types of gloves and a wide variety of glove material characteristics (dielectric constants), PenMount PCAP touch controllers have already been verified to offer normal PCAP touch panel operation with a number of commonly used gloves such as rubber cleaning gloves, industrial cotton gloves, medical latex gloves, etc.
PCAP COF Solution
The second approach is COF (Chip on Flex), which mounts a control IC on the sensor FPC (see below Fig.). The analog capacitance signal will be converted into digital position data on the FPC. This position data will be transferred to the Host computer by the serial interface on the FPC (such as USB, UART, I2C etc.).
- PM2103 P2-06 3.5"~4.9" 10 17 USB , I²C, UART
- PM2203B P2-06 5"~7.9" 15 24 USB , I²C, UART
- PM2204 P2-06 5"~7.9" 24 16 USB , I²C, UART
- PM2205 P2-08 5"~7.9" 23 19 USB
- PM2300 P2-06 8"~10.4" 24 35 USB, I2C, UART
- PM2303 P2-08 8"~10.4" 23 40 USB, I2C, UART
- PM2304 P2-08 8"~10.4" 23 40 USB
- PM2357 P2-08 8"~12.1" 23 40 USB
The Advantages of COF design are:
- High integration of control IC and sensor, which is very important in mobile hand-held devices.
- Digital interface is highly immune to noise and requires only a small number of circuits, which makes long and slim FPC design possible for easy product installation.
- Connectors for touch panel and system interface are no longer required.
AMT PCAP COF touch panels are applicable to compact mobile devices (e.g. hand-held products with limited system space) with low noise LCD modules. If you have need for custom COF design services, please contact us.
Remark: PCAP COF tails are not for sale separately and must be integrated with touch panels.