Scope of application
Capacitive multi-touch screens suitable for consumer electronics (such as MID, car DVD, etc.).
Features and specifications
Structure and Materials
The structure of the touch screen is shown in Figure 1, the materials are shown in Table 1, and the engineering structure diagram is shown in the attachment.
Table 1 The structure and materials of the touch screen
Structure | Materials used | Comment |
Panel | PET | Thickness: 0.188 mm
|
Bonding layer | Optical transparent glue（OCA） | Thickness: 0.125mm
|
Induction circuit layer (ITO glass) | ITO GLASS | Thickness: 1.1 mm |
Lead wire | FPC | Thickness: 1.2 (max)mm
|
Driver IC | GT911 | Package：5×5×0.43 |
Function structure diagram and interface definition
The functional structure diagram of the touch screen is shown in Figure 3.
The interface definition of the touch screen is shown in Table 3.
Pin
| symbol | Function description |
1 | GND | Ground |
2 | SCL | IIC clock input pin |
3 | SDA | IIC data pin |
4 | Shut down | Power supply input for analog circuit |
5 | INT | Interrupt pin for Interrupt request |
6 | VDD（vbus） | Power supply input for I/O circuit |
Test requirements
Before the touch screen is shipped, it needs to meet the requirements of electrical performance testing, interface timing, mechanical performance testing and optical characteristics. Their test requirements are as follows.
Electrical performance
Interface timing
Figure 4 I2C bus fast/standard mode timing diagram
Mechanical behavior
The mechanical performance requirements of the touch screen are shown in Table 6.
Table 6 Surface hardness
Project | Description |
Surface hardness | 3H |
Optical properties
The transmittance test method and transmittance of the touch screen are shown in Figure 5. The average transmittance is shown in Table 7.
Figure 5 Transmittance and test method of touch screen
Note：The calculation method of average transmittance is as following:
Tavg = Σ（Ti）/ 401, i is wavelength ( from 380 to 780)
