This analyst opinion article indicates that the price for LTPS LCD with TDDI will be more competitive than a-Si LCD with TDDI, and panel makers and driver makers are positive in promoting TDDI solutions for automotive displays.
Key findings
- One of the key selling points of touch and display driver integration (TDDI) is cost-saving for in-cell integration. Panel makers are positive in promoting TDDI for both low-temperature polycrystalline silicon (LTPS) LCD and amorphous silicon (a-Si) LCD.
- Cost comparison indicates that the total price of a-Si LCD is less competitive for in-cell TDDI solution in automotive displays because more TDDI drivers are needed.
TDDI is popular for automotive displays
Panel makers and driver makers are positive in promoting TDDI solution for automotive displays; the key value of TDDI is cost saving. Additionally, LTPS LCD is preferred because it is good for gate on array (GOA); it also has a higher resolution, a lower power consumption, and a better performance, which Japanese and Korean panel makers are focusing on. On one hand, a-Si LCD is still the leading technology of automotive displays and Chinese panel makers have big a-Si capacity and limited LTPS capacity for automotive displays. Thus, Chinese panel makers are also promoting a-Si LCD with TDDI solution aggressively.
TDDI is bundled with larger-sized automotive displays mainly
Japanese panel makers are strong in automotive and industrial displays because of the factory restructuring plan, in which small and old fab lines are shutting down. G6 LTPS LCD capacity is gradually shifting the focus from smartphone to automotive displays. Hence, Japanese panel makers are positive in promoting large LTPS LCD screens, bundled with in-cell touch, to replace a-Si panels.
a-Si LCD needs more TDDI drivers, which has a higher cost than LTPS LCD with TDDI solution
Different from smartphone’s one-chip driver, a larger-sized automotive display needs more TDDI drivers. Reliability is the most important factor for automotive displays. A single gate is necessary for a-Si panels. However, LTPS LCD can introduce mux3 for the same resolution. The source lines in a-Si LCD are triple the source line in LTPS LCD. For example, a 1920x720 a-Si LCD has three source lines, which is 1920x3(RGB), whereas a LTPS LCD, with mux3, is 1920x3(RGB)/3. Currently, the mainstream TDDI solution in automotive display is 960 touch channels with 1920 source channels. The number of drivers for a-Si LCD depends largely on resolution. For example, a 1920x720 a-Si LCD needs three pieces of TDDI drivers. On the other hand, the number of drivers for LTPS LCD depends largely on panel size because the pattern pitch of touch sensor should be designed with a reasonable size to ensure a good touch performance. 4.5–5mm pitch is preferred while 7mm is the limit. 960 touch channels can support up to 12.x inches. Figure 1 shows the examples of real projects:
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In the first quarter of 2020 (1Q20), the price quotation of automotive TDDI was approximately $4.x, with 1920 source channels and 960 touch channels. The cost gap between a-Si panel and LTPS panel is less than $4. In this case, the total price of a-Si LCD is less competitive because more TDDI drivers are needed. Therefore, Chinese panel makers will face the pressure of higher cost for a-Si with TDDI solution.
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