1. Field of the Invention
The present invention relates to a display apparatus for displaying an image signal, and more particularly, the present invention relates to a display apparatus for an image signal that can switch transmission paths in response to detection of connection conditions of an image signal cable, and can further switch the transmission paths of a image signal to a wireless communication system automatically when the image signal cable is disconnected from the display apparatus.
2. Description of the Related Art
Conventionally, in a desktop personal computer, for example, peripheral devices such as a keyboard, a display apparatus and a printer are connected to a personal computer main unit. On the other hand, in a notebook personal computer, the keyboard and the display apparatus among these peripheral devices are incorporated in the personal computer main unit. Thus, the display apparatus is indispensable for making full use of features of the personal computer.
But, recently, as lightweight and compact LCDs are more often used, in a display processing unit of the display apparatus, than CRTs that would increase weight of the apparatus, only the display apparatus can be readily moved separately. Further, it has become possible to display more types of contents such as images of CDs, DVDs and television broadcasts, for example, on the display apparatus.
On the other hand, at present, resources are shared by connecting a plurality of personal computers to a network system such as a LAN, wherein image information as the contents are supplied to each personal computer via the LAN. When such image information is displayed on the display apparatus, the image information that is to be displayed on the display processing unit is transmitted from the respective personal computer to the display apparatus via an image signal cable, or a wireless communication system such as a wireless LAN provided between the personal computers and the display apparatus.
However, in the display apparatuses that have been used conventionally, the image signal is supplied from the personal computer via only one fixed connection unit that is either the image signal cable or the wireless LAN.
Thus, in the prior art, it is not possible to switch the connection unit in the display apparatus automatically using any circuit configuration in response to the connection conditions, or in other words, in response to whether the image signal cable is connected to the display apparatus or not.
Further, also in information processing equipment such as a personal computer and a server, it is not possible to switch the connection unit automatically using its internal circuit in response to the connection conditions of the image signal cable.
Therefore, it is an object of the present invention to provide a display apparatus for displaying an image signal supplied from a personal computer and the like that can switch a connection unit automatically using an internal circuit so that one image signal via an image signal cable is displayed when such image signal cable is connected, while another image signal transmitted through other image signal transmission system such as, for example, a wireless transmission system for the personal computer is displayed when the image signal cable is not connected.