1. An electronic apparatus, coupled to a display device, comprising: a memory, comprising a virtual frame buffer for storing data to be transmitted to the display device; a data transmission interface, performing data transmission between the electronic apparatus and the display device; and a control module, storing a current character image corresponding to a current character in the virtual frame buffer when a user inputs the current character to an input device, determining whether a prior image which has not been transmitted to the display device exists in the virtual frame buffer, determining whether the current character image matches the prior image, and combining the prior image with the current character image to obtain a combined image in place of the prior image when the current character image matches the prior image, wherein when an abscissa value of the upper-left corner of the current character image is equal to the sum of the abscissa value of the upper-left corner of the prior image and the width of the prior image, the ordinate value of the upper-left corner of the prior image is equal to the ordinate value of the upper-left corner of the current character image, and the height of the prior image is equal to the height of the current character image, the control module determines that the current character image matches the prior image.