Apple's upcoming smartphones dubbed as iPhone 6 and iPhone 5S are speculated to feature invisible button and slider controls, according to leaked patents found online.

Apple patent-centric tech blog Patently Apple, the iPhone 5S or iPhone 6 may feature an invisible backside button and slider controls if patents proved to be true. 34 Apple patents have been revealed by the US patents office, reportedly for the iPhone 5S, iPhone 6 and iPad Mini 2. Other patents exposed on Patently Apple reveal a new iOS interface for iTunes and magnetometer.

The Invisible Button is created "by micro perforations or holes which could be illuminated to show where the button is," according to the website.

"Apple states that "the backlight can be activated when a user taps or presses down on the button. In another embodiment, a motion sensor (not shown) may interface with the LED and activate it when motion is detected. In another embodiments heat and/or sound sensors (not shown) can interface with and activate LED 95 when heat and/or sound is detected"," says Patently Apple.

In the photo found in the website, the box-like device can be any kind of apple device. It shows the same sort of technology as the first graphic, but presumably would encourage the user to slide their finger up or down the panel. Patently Apple has suggested the controls could be contextual, changing according to the app you are using.

Rumour has it that the next iPhone will feature Retina or IGZO screen display, A7 quad core chip processor, iOS 7, 128GB internal storage, 13 mega-pixel camera, and longer battery life. The lack of NFC support on the iPhone 5 was one of the biggest criticisms aimed at Apple's smartphone.

Meanwhile, the cheaper iPhone 5S is rumoured to sport a plastic casing, 4-inch screen display, dual core processor and 8-megapixel camera.

The Apple chief Time Cook also dropped several hints that the upcoming iPhone 6 and 5S will be released later this year. Cook said that no new products are to launch before the end of the year.

Cook also subtly dented rumours that the iPhone 5S could launch as early as June. "Our teams are hard at work on some amazing new hardware, software, and services that we can't wait to introduce this fall and throughout 2014."

It seems that the reports on the delayed release date of Apple products proved to be true. A number of analysts claimed that Apple's smartphones are delayed due to "production issues".

However, Apple did not give an official statement on the rumours surrounding iPhone 6 and iPhone 5S.