Display device including a connection board and a method for testing pad connection thereof

A display device comprising:

• a display panel comprising a data line, and first and second panel pads electrically connected to each other;
• a main board comprising first to fourth main board pads, a first test pad, a main controller, and a connection line electrically connected between the third main board pad and the fourth main board pad;
• and
• a connection board, and
• a driving circuit disposed on the connection board and to drive the data line,
• wherein the connection board comprises:
• first and second connection board pads electrically connected to the first and second panel pads, respectively;
• first to fourth main contact pads;
• first and second test lines electrically connecting the first and second connection board pads to the first and second main contact pads, respectively;
• an intermediate connection line electrically connecting the first main contact pad to the fourth main contact pad;
• and
• an output pad electrically connected to the first test pad;
• wherein the third main board pad and the fourth main board pad are electrically connected to each other,
• wherein the driving circuit comprises:
• a pull-up resistor electrically connected between a first voltage terminal and a first node;
• and
• a comparator to compare a voltage at the first node with a reference voltage and to output a contact test signal corresponding to a comparison result to the output pad,
• wherein the second main contact pad is electrically connected to the first node, and the fourth main contact pad is electrically connected to a second voltage terminal through the intermediate connection line and the fourth main contact pad,
• wherein when the first to fourth main contact pads are electrically connected to the first to fourth main board pads, respectively:
• the third main board pad is electrically connected between the third main contact pad and the connection line, and the fourth main board pad is electrically connected between the connection line and the fourth main contact pad;
• and
• a current path is formed in series from the first voltage terminal of the driving circuit to the second voltage terminal of the driving circuit through the pull-up resistor, a third test line, the third main contact pad, the third main board pad, the connection line of the main board, the fourth main board pad, the fourth main contact pad and a fourth test line, and
• wherein the main controller is to receive the contact test signal through the first test pad.

A method for testing pad connection of a display device comprising a display panel comprising first and second panel pads electrically connected to each other;

• and a connection board comprising first and second connection board pads connected to the first and second panel pads, respectively, an input pad, and an output pad, the method comprising:
• electrically connecting the first and second connection board pads to the first and second panel pads, respectively;
• electrically connecting the first connection board pad to a first node in response to a switching control signal received through the input pad;
• and
• comparing a voltage at the first node with a reference voltage and outputting a contact test signal corresponding to a comparison result to the output pad,
• wherein the first panel pad is connected to the second panel pad via a connection line on the display panel,
• the first node is connected to a first voltage terminal of a driving circuit via a pull-up resistor,
• the second connection board pad is electrically connected to a second voltage terminal of the driving circuit, and
• when the first and second connection board pads are electrically connected to the first and second panel pads, respectively:
• the first panel pad is electrically connected between the first connection board pad and the connection line, and the second panel pad is electrically connected between the connection line and the second connection board pad;
• and
• a current path is formed in series from the first voltage terminal of the driving circuit to the second voltage terminal of the driving circuit through the pull-up resistor, a first test line, the first connection board pad, the first panel pad, the connection line on the display panel, the second panel pad, the second connection board pad and a second test line.