Apple, Apple Watch Series 4에 배터리 지속 시간 늘리는 LTPO TFT 적용

Apple이 현지시간으로 9월 12일 미국 캘리포니아주에 위치한 애플 파크 스티브 잡스 극장에서 이전보다 더 큰 화면에 헬스케어 기능을 강화한 Apple Watch Series 4를 발표했다.

<Apple Watch Series 4, Source:>

Apple은 이번 발표에서 Apple watch Series 4에 LTPO라는 새로운 기술을 도입해 전력 효율을 향상시켰다고 밝히며 이목을 끌었다.

LTPO는 low temperature polycrystalline oxide의 약자로써, 전하 이동도가 우수한 poly-Si과 저전력 구동이 용이한 IGZO의 장점만을 활용한 TFT의 일종이다. LTPO TFT는 누설전류가 적고 on/off 특성이 좋기 때문에 소비 전력이 낮고 배터리의 지속 시간은 늘어난다.

<Apple의 LTPO TFT 특허>

또한, Apple은 Apple Watch 4의 본체 규격을 40mm와 44mm로 키우고 bezel을 좁혀 이전 모델들에 비해 display area를 35%와 32%로 늘렸으며, 화면 해상도도 44mm 모델은 368×448 픽셀, 40mm 모델은 324×394 픽셀로 증가시켰다고 설명했다. Apple Watch4의 디스플레이는 LG디스플레이에서 제작한 plastic OLED이며 최대 밝기는 1,000 nit이다.

Apple Watch Series 4의 출시 가격은 GPS 모델이 399달러부터이며 셀룰러 모델이 499달러부터다. 예약 주문은 9월 14일부터 진행되고 제품 출시는 21일부터다.

What’s the change for full screen implementation?

After Apple launched iPhoneX, applied with notch OLED to implement a wider full screen in 2017, many smartphone makers such as Huawei, Vivo and Oppo started to introduce similar types of smartphones.


The total number of notch-type OLED smartphones, which have been revealed since 2017, is 36, accounting for 10% of total OLED smartphones.

The reason why smartphone makers apply notch-type display is to provide consumers with the large screen size in a limited phone size. However, in the notch type, there is a limitation in expanding the display area (DA), which is the ratio of the display to the smart phone, due to the camera and the front speaker. Thus, the smartphone makers seem to implement the camera function with adopting a popup method.

On June 12, Vivo introduced the smartphone NEX with DA 91.2%.The camera is embedded in the device in the form of a pop-up, and the display itself serves as a speaker and fingerprint sensor. By minimizing the bezel, Vivo achieved a full screen.

Oppo showcased Find X in Paris, France on June 19. Oppo also adopts the camera function as a pop-up method, similar to Vivo, to implement a full screen. It has a 3D face recognition sensor. DA of Oppo’s Find X is 93.8%, which is about 2.7% larger than that of Vivo. This is about 10% larger than Samsung Electronics’ Galaxy S8 +, which had the biggest DA in 2017, and 11% larger than iPhone X.

<Vivo NEX and Oppo Find X, source:, GSMArena>

Analysis of the average DA from 4Q 2017 to 2Q 2018 after the launch of the Notch model, shows that the notch type DA is about 9% and the camera pop type DA is about 17 % wider than that of the conventional smartphones (excluding notch type). By switching the front camera into a pop-up form, more than 90% DA can be realized.

As such, smartphone makers are making various changes to realize full screen. There is a growing interest in how to minimize the bezel for the launching a smartphone with a wider DA.

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