Whether there is a defect such as chipping of a die or separation of a resin in a wafer level package is electrically detected. The projector has a zoom adjusting module and a keystone correcting module. The body is generally cylindrical shaped with opposing end portions. The domain-specific target language model may be built dynamically or \u201con-the-fly\u201d based on the currently displayed text, while the general-domain garbage language model is shared among all different text outputs. Via a fuel-supplying mixture channel, the storage channel is connected with a fuel supply.