Huawei will launch the world’s first Z-type folding (tri-fold) smartphone Mate XT in September 2024

The current structure of a book-type foldable smartphone consists of one subcover OLED and one main foldable OLED, usually made of flexible OLED with an LTPS or LTPO TFT backplane.

In 2024, seven new book-type foldable smartphone models have been launched, which are as follows:

• OPPO Find 4: Features a 6.8-inch main foldable display and a 3.26-inch subdisplay from BOE.

• vivo X Fold 3 Pro: Features an 8.0-inch main foldable display from Samsung Display and a 6.53-inch subdisplay from BOE.

• HONOR Magic V3: Features a 7.92-inch main foldable display from BOE and Visionox and a 6.43-inch subdisplay from BOE.

• HONOR Magic Vs3: Features a 7.92-inch main foldable display from BOE, Visionox, and Tianma and a 6.43-inch subdisplay from BOE.

• Samsung Galaxy Z Fold6: Features a 7.6-inch main foldable display and a 6.3-inch subdisplay from Samsung Display.

• Tecno V Fold 2024: Features a 7.85-inch main foldable and a 6.42-inch subdisplay from China Star.

• Xiaomi MIX Fold 4: Features a 7.98-inch main foldable display from Samsung Display and a 6.56-inch subdisplay from China Star.

However, to set itself apart from other smartphone makers, Huawei is considering introducing a new foldable smartphone that would use a single foldable display to replace the current subcover and main foldable display structure. This new foldable display is being referred to as an “N project” because it will feature an N-type folding (or some call it Z-type folding or tri-fold). This means that it will have two folding segments on a single piece of the screen, allowing for both in-folding and out-folding capabilities. Huawei will call this smartphone Mate XT. Figure 1 shows Huawei’s Z-type folding structure.

The Z- or N-type folding structure is not new. This is because some display makers have been developing a similar one-piece folding display since 2021. The combination of in-folding and out-folding capabilities on one display is considered to pave the way for future form factors, such as rollable or stretchable displays.

The following are some examples:

- In 2021, Samsung Display showcased the “Flex In & Out “display prototype, and Samsung Display called it the S-type folding. 

- In 2022, Samsung Display showcased the “Flex G,” which is dubbed as the G-folding.   

- In 2022, BOE demonstrated an N-type folding, as analyzed in Omdia’s Display Dynamics – March 2022: BOE showcased an “N-shaped” folding OLED display.  

- In 2020, OPPO announced a rollable smartphone prototype, as analyzed in Omdia’s Display Dynamics – November 2020: Beyond foldable, OPPO announced a rollable smartphone prototype.

In 2021, Omdia has defined the foldable display evolution as having the following four steps:

Step one: Out-folding display The folding area and the display are exposed, leading to concerns about reliability and susceptibility to shock and vibration.

Step two: In-folding display The folding area and the display are protected, but the display can only be activated when unfolded.

Step three: One subcover display and one main in-folding display The folding area and the main foldable display are protected. Users can still use the subcover display when folded. However, having two displays in one single smartphone may lead to issues, such as increased power consumption and thickness.

Step four: One foldable display with two folding segments This design allows for both in-folding and out-folding of the display, creating a Z-shape or N-shape when folded and unfolded. However, many of the smartphone’s mechanisms, such as fingerprint identification, cover glass lamination, camera hole, and the re-subpixel design of the hole area, must be optimized. In addition, the out-folding area must be protected. Some have called this type of folding display tri-fold because it resembles three foldable displays in one smartphone form factor.

While other panel makers have not demonstrated their Z-type foldable displays for a long time, Samsung Display continues to showcase it as the new direction in the fast-growing foldable OLED segment.

Figure 3 and Figure 4 show Samsung Display’s latest demonstration of the S-type folding displays.

Huawei’s new Mate XT folding smartphone will have a similar structure and is positioned as Huawei’s best high-end smartphone, priced at over $2,500. The display will boast the following advanced specifications:

• 9- to 11-inch display with a 5:4 aspect ratio

• Over 450 PPI resolution

• LTPO TFT backplane

• 1–120Hz variable refresh rate (VRR)

• Two folding areas in one piece, with the in-folding having a 1.3 folding radius and the out-folding having a 1.5 folding radius

• Color filter on encapsulation (COE) to remove the circular polarizer for better folding thickness

• Ultra-thin glass (UTG) cover lens

However, there are several technological hurdles that must be overcome to mass produce this type of display, including:

• Reliability, especially for a two-folding display

• Manufacturing yield rate of a 9- to 11-inch foldable display with both in-folding and out-folding capabilities

• Folding crease management, particularly because there are two folding areas in one display

• Power consumption

• Cover glass lamination yield rate

• Bezel protection issue