Apple Inc’s suppliers have started initial production of new iPhone models with a feature called Force Touch, which senses how hard users are pressing down on a screen, people with knowledge of the matter said.

Its newest iPhones, in the same 4.7-inch and 5.5-inch sizes as the current iPhone 6 and iPhone 6 Plus devices, will have a similar exterior design, the people said. Volume manufacturing is scheduled to ramp up as soon as next month, they said.

Apple is bringing Force Touch, first unveiled for the Apple Watch and the newest MacBook model, to the iPhone at least two years after it started working with suppliers to perfect the pressure-sensitive displays.

The feature, which lets users adjust the strength of their screen taps to bring up different functions, is Apple’s latest move to stay ahead of rivals such as Samsung Electronics Co, which this year released its latest Galaxy smartphone with a screen that can be viewed from the side.

Suppliers such as Foxconn Technology Group also rely on the iPhone to maintain growth amid slowing PC sales. Apple last year accounted for 50.3 percent of sales at Hon Hai Precision Industry Co, the largest member of the Foxconn group, according to its annual report and Bloomberg supply chain data.

Terry Gou, Foxconn’s chairperson and founder, last week said he’ll deliver at least 10 percent revenue growth this year despite missing the same target last year.

Larger screens

Apple’s release of iPhones last year with bigger displays brought it in line with comparable offerings from Samsung and HTC Corp, helping meet rising demand in China and other Asian countries, where consumers prefer more screen real estate.

iPhone unit sales climbed 40 percent in the March quarter to 61.2 million, topping estimates for 58.1 million. The device helped Apple end Samsung’s three-year reign at the top of the global smartphone market. iPhone sales in China also outpaced the US for the first time in the three months through March.

While final assembly is expected to be smooth because the design of the new iPhones is similar to the current model, the timing and production volume of Force Touch-enabled phones could be impacted by the supply and yield of the displays, said one of the people.

Bloomberg reported in 2013 that Apple was planning to add pressure-sensitive displays to the iPhone.

- Bloomberg