A method and apparatus for providing an efficient dormant mode for push-to-talk communication devices in a group communication network provides for determining whether the communication device has been inactive for a predetermined first time period and, if so, causing the communication device to enter a control-hold mode, wherein the communication device maintains its dedicated traffic channel. The optical member moves to a position where the optical path of the optical image of the subject, which is incident via the first lens group, is changed to the direction of the second lens group when a picture is to be taken, and moves to a position where it is withdrawn from this area when a picture is not to be taken. The columnar support portions are arranged in a plurality of places on a surface on the opposite side to a surface in contact with the cushioned surface of the base material. A full track address is generated based on the detected servo zone and the detected partial track address.