A liquid crystal display device includes a pixel having a first to nth subpixels and a circuit. The bandwidth allocation software includes an image representing firmware configured for determining bandwidth allocation requirements. The path length\u2014altering unit has a path scale and a path detector which detect a changing length of the optic path of the measuring andor reference beams and the interferogram records are synchronized with the path measurement. Therefore, the hardware manufacturing cost of the game keyboard device can be considerably reduced. In addition, this method facilitates using small round stones in lieu of metal granules to form unique granulated patterns.