A display device includes a display panel and a supporting structure. The second arm has a drive plane. The rear lens group 3 is provided with a aperture stop 6 that is eccentric with respect to an optical axis 7 common to the front lens group 2 and the rear lens group 3. The glider also comprises a ballast weight, a stiffener, and optionally an interior skeleton. The microprocessor, when in the test mode, upon receiving at least one test request from the USB host device may cause the USB transceiver to output test data, read back the test data from the USB transceiver, compare the test data with the test data read back from USB transceiver, and generate test results for the USB host device based upon the comparison.