A conversion apparatus comprising: a first connector configured to be coupled to a display apparatus; a second connector configured to be coupled to an image signal input apparatus and to receive an image signal converted to a serial signal from the image signal input apparatus; a serializer/deserializer SerDes unit configured to convert the image signal, converted to the serial signal and received through the second connector, to a parallel signal, and transmit the image signal converted to the parallel signal to the display apparatus through the first connector; and characterised by a plurality of power supply units (140-1, 140-2, 140-3, 140-4) configured to supply powers having voltages differently set from each other to the first connector, the second connector, and the SerDes unit, and further characterised in that the plurality of power supply units (140-1, 140-2, 140-3,140-4) is autonomously provided in the conversion apparatus as a separate circuit to prevent interference, wherein each of the plurality of power supply units (140-1, 140-2, 140-3, 140-4) is separated by a bead configured to remove noise, wherein the SerDes unit is configured to select one of the plurality of power supply units (140-1, 140-2, 140-3, 140-4) that is set to provide a power having a specific voltage according to a processing function, and receives the power having the specific voltage from the selected power supply unit (140-1, 140-2, 140-3, 140-4), wherein the conversion apparatus is attachable to and detachable from the display apparatus, wherein in response to the conversion apparatus being attached to the display apparatus, the image signal input apparatus is configured to control all of the operations of the display apparatus and the conversion apparatus, and wherein image input terminals of the display apparatus are disabled in response to the conversion apparatus being attached to the display apparatus, and the image input terminals of the display apparatus are enabled in response to the conversion apparatus being detached from the display apparatus. a first connector configured to be coupled to a display apparatus; a second connector configured to be coupled to an image signal input apparatus and to receive an image signal converted to a serial signal from the image signal input apparatus; a serializer/deserializer SerDes unit configured to convert the image signal, converted to the serial signal and received through the second connector, to a parallel signal, and transmit the image signal converted to the parallel signal to the display apparatus through the first connector; and characterised by a plurality of power supply units (140-1, 140-2, 140-3, 140-4) configured to supply powers having voltages differently set from each other to the first connector, the second connector, and the SerDes unit, and further characterised in that the plurality of power supply units (140-1, 140-2, 140-3,140-4) is autonomously provided in the conversion apparatus as a separate circuit to prevent interference, wherein each of the plurality of power supply units (140-1, 140-2, 140-3, 140-4) is separated by a bead configured to remove noise, wherein the SerDes unit is configured to select one of the plurality of power supply units (140-1, 140-2, 140-3, 140-4) that is set to provide a power having a specific voltage according to a processing function, and receives the power having the specific voltage from the selected power supply unit (140-1, 140-2, 140-3, 140-4), wherein the conversion apparatus is attachable to and detachable from the display apparatus, wherein in response to the conversion apparatus being attached to the display apparatus, the image signal input apparatus is configured to control all of the operations of the display apparatus and the conversion apparatus, and wherein image input terminals of the display apparatus are disabled in response to the conversion apparatus being attached to the display apparatus, and the image input terminals of the display apparatus are enabled in response to the conversion apparatus being detached from the display apparatus.