Apple's next iPhone could face supply shortages at launch as one of the firm's LCD manufacturers, Sharp, is reportedly behind schedule due to technical difficulties with the production process. The issue has resulted in lower than expected yields, according to a source speaking to the Wall Street Journal.

The difficulties in manufacturing were apparently prompted by Apple's decision to use in-cell LCD panels, a new technology that allows for even thinner displays by integrating the touch sensors into the LCD itself. More traditional methods usually involve placing them on top of the display.

Sharp is one of three panel makers contracted to make the displays for the upcoming smartphone. Fortunately for Apple, Japan Display Inc., and LG Display Company are already mass-producing and shipping them to Apple's manufacturing plants for assembly, according to another unnamed source familiar with the matter.

The source says Sharp still hasn't started mass production, originally scheduled to begin around the end of this month. It is currently unclear when full production will begin, which raises questions about whether Apple will be able to secure enough components to meet public demand in the first few weeks following the iPhone launch.

This isn't the first time the Japanese firm has had problems mass-producing displays for Apple. Earlier this year it was revealed Sharp was struggling to meet Apple's strict standards when producing the very-high resolution panels for the new iPad. As a result the first round of tablets almost exclusively used panels made by Samsung.

If the latest rumors are correct, Apple is very likely to announce the new iPhone at a media event on September 12 in San Francisco. The device is expected to go on sale nine days later, on September 21. Rumors of a smaller, 7.85-inch iPad are also floating around with Bloomberg citing four separate sources on a supposed launch this October and naming LG Display and AU Optronics as panel suppliers.