US Patent 7233846 Trouble diagnosing device

An enlargement button that instruct enlargement of first to fourth buttons to is displayed on a display. The first to fourth buttons to are used to instruct the operation of a control device to be controlled by an electronic control unit to which a trouble diagnosing device is connected. When the enlargement button is manipulated, the first to fourth buttons to are enlarged in the display respectively in corners sections created by dividing the display screen substantially equally into four. With this arrangement, the operator no longer needs to monitor the first to the fourth button by eyes for manipulating these buttons, thereby improving the operability.