Apple has been releasing a range of portable product offerings like the iPhone 5s and the iPad Air. This does not mean the company has abandoned working on old favorites like the MacBook. According to a recent document uncovered, the upcoming MacBook devices may feature a new keyboard system with multi-function "keystacks." The system combines touch sensors, miniature displays and haptic feedback mechanisms.

According to a report by Apple Insider, the company remains working on possible improvements for its some of its traditional offerings. The latest patent sighted is entitled "Multi-functional keyboard assemblies." The system refers to a keyboard featuring "keystacks" or separate keys layered with stitches, sensors and electronics.

The U.S. Patent and Trademark Office published the patent application. According to the document, Apple's version of the multi-functional" keyboard draws inspiration from third party components such as Art. Lebedev Studio's Optimus Maximus keyboard. The system sported clear keycaps layered with tiny configurable OLED displays.

The initial illustration on the patent document shows application of the system using the present generation Macbook Air. The Maxmiums and follow up versions like the Optimus Polaris offered keys using built-in displays. These proved useful as the individual keys can be mapped out to deliver specific pictures, icons or letters. Users can customize the commands.

The problem with these keyboards is that they come in small batches. The devices also come with high price tags without guarantee of optimal performance. Apple's take on the keyboard features a display-within-key concept. The company includes several layers to the keystack. Whereas Optimus has limited output because of the OLED and physical switch, Apple's patent works with multiple modes instead. Users have several input and output modes.

For instance, users can tweak the multi-functional keystack to recognize input via the switch type button. The capacitive surface section, on the other hand, can offer a separate input system via multi-touch gestures.

Apple also adds that the system uses an integrated backlit display in every key to offer visual feedback to users. Apple has released a new line of MacBook airs with discounted price tags. This new keyboard system can find its way to upcoming MacBook releases like the MacBook Pro. Apple has not revealed when the next MacBook Pro will come out.