A sign holding device for a folding chair that allows the user to display customized messages on a back rest of the chair. A molten thermoplastic resin material is injected into a cavity defined by a molded product’s appearance surface forming portion and a molded product’s rear surface forming portion through one or more direct gates and one or more hot runners to fill the cavity with the molten resin material, thereby performing injection molding. In addition, the central control section detects the presenceabsence of audio data not associated with playlists, and if audio data not associated with playlists is stored, processes a list of such audio data as one playlist. The patterned layer may usefully be an alignment layer for a liquid crystal device, especially a bistable device, and the different areas may be arranged to give grey scale in the device. The optical hybrid has an optical processing entity for deriving the first and second output optical signals from the incoming optical signal and the local oscillator signal.