Patent ID: 7920581

Claim:
A node device in a tree-type broadcast system which is formed by participation of a plurality of node devices and comprises a plurality of hierarchy levels in a tree-like shape formed by the plurality of node devices while placing a broadcast device at a top of the hierarchy levels and connecting the plurality of node devices through a communication unit, wherein content data broadcasted by the broadcast device is sequentially transferred from a node device at an upper hierarchy level to a node device at a lower hierarchy level, wherein the content data is broadcasted through the plurality of node devices participating in the tree-type broadcast system, wherein the tree-type broadcast system is an overlay network formed by participation of all or part of the plurality of node devices which are connected to each other via the communication unit, the node device comprising: a display control unit configured to control display to display a predetermined screen; and a participation and withdrawal control unit configured to carry out a participation process of participating in the tree-type broadcast system when a broadcast information screen related to broadcast of the content data is displayed with the display control unit and to carry out a withdrawal process of withdrawing from the tree-type broadcast system when display of the broadcast information screen is finished with the display control unit, or when a transition of display to another screen occurs with the display control unit, wherein in a case where the display of the broadcast information screen is finished with the display control unit or the transition of display to another screen occurs with the display control unit, the participation and withdrawal control unit continues the participation process of participating in the tree-type broadcast system when the display of the broadcast information screen is finished within a waiting time previously set up or the transition of display to another screen occurs within the waiting time previously set up, and carries out the withdrawal process on a condition that the broadcast information screen is not displayed again with the display control unit within the waiting time previously set up.