A display device comprising: a display panel adapted to display an image; a data driver adapted to supply a data signal (DATA) to a plurality of data lines (DL1... DLn) of the display panel; and a power saving part adapted to output a control signal (CTRL1, CTRL2) to control a reference power source for the data driver according to a power mode of the display panel, wherein the power mode is either: a power-saving mode corresponding to a display-off period in which a display area comprises a clock display area and a time non-display area (NDSP) and the image is not-displayed in the time non-display area (NDSP) on the display panel or a normal-power mode corresponding to a display-on period in which the image is displayed on the display panel, and in the power-saving mode: either or both of the static current and dynamic current in the data driver are reduced by the power saving part on a per-horizontal line basis by means of the following actions, when the data driver drives the clock display area, an amplifier voltage (AMPV) supplied to amplifiers of the data driver decreases from a maximum voltage (max) to a target voltage with a certain gradient or increases from the target voltage to the maximum voltage (max) with a certain gradient on data lines corresponding to the clock display area of the display panel, and when the data driver moves out of the clock display area and reaches the time non-display area (NDSP), no amplifier voltage (AMPV) is supplied to the amplifiers of the data driver on data lines corresponding to the non-display area of the display panel. a display panel adapted to display an image; a data driver adapted to supply a data signal (DATA) to a plurality of data lines (DL1... DLn) of the display panel; and a power saving part adapted to output a control signal (CTRL1, CTRL2) to control a reference power source for the data driver according to a power mode of the display panel, wherein the power mode is either: a power-saving mode corresponding to a display-off period in which a display area comprises a clock display area and a time non-display area (NDSP) and the image is not-displayed in the time non-display area (NDSP) on the display panel or a normal-power mode corresponding to a display-on period in which the image is displayed on the display panel, and in the power-saving mode: either or both of the static current and dynamic current in the data driver are reduced by the power saving part on a per-horizontal line basis by means of the following actions, when the data driver drives the clock display area, an amplifier voltage (AMPV) supplied to amplifiers of the data driver decreases from a maximum voltage (max) to a target voltage with a certain gradient or increases from the target voltage to the maximum voltage (max) with a certain gradient on data lines corresponding to the clock display area of the display panel, and when the data driver moves out of the clock display area and reaches the time non-display area (NDSP), no amplifier voltage (AMPV) is supplied to the amplifiers of the data driver on data lines corresponding to the non-display area of the display panel. a power-saving mode corresponding to a display-off period in which a display area comprises a clock display area and a time non-display area (NDSP) and the image is not-displayed in the time non-display area (NDSP) on the display panel or a normal-power mode corresponding to a display-on period in which the image is displayed on the display panel, and in the power-saving mode: either or both of the static current and dynamic current in the data driver are reduced by the power saving part on a per-horizontal line basis by means of the following actions, when the data driver drives the clock display area, an amplifier voltage (AMPV) supplied to amplifiers of the data driver decreases from a maximum voltage (max) to a target voltage with a certain gradient or increases from the target voltage to the maximum voltage (max) with a certain gradient on data lines corresponding to the clock display area of the display panel, and when the data driver moves out of the clock display area and reaches the time non-display area (NDSP), no amplifier voltage (AMPV) is supplied to the amplifiers of the data driver on data lines corresponding to the non-display area of the display panel. either or both of the static current and dynamic current in the data driver are reduced by the power saving part on a per-horizontal line basis by means of the following actions, when the data driver drives the clock display area, an amplifier voltage (AMPV) supplied to amplifiers of the data driver decreases from a maximum voltage (max) to a target voltage with a certain gradient or increases from the target voltage to the maximum voltage (max) with a certain gradient on data lines corresponding to the clock display area of the display panel, and when the data driver moves out of the clock display area and reaches the time non-display area (NDSP), no amplifier voltage (AMPV) is supplied to the amplifiers of the data driver on data lines corresponding to the non-display area of the display panel.