Display device with image shift

1 . A display device, comprising:

a controller to receive original image data and output a display image signal; and

a display panel to receive the display image signal and display a display image corresponding to the display image signal,

wherein:

the controller includes:

an image shift controller to generate shifted image data by modulating the original image data to shift the display image sequentially along a preset shift path on the display panel; and

a memory to store a shift path value indicating a distance by which the display image has been shifted on the preset shift path, the shift path value to be stored in the memory when the display device is powered on and to be retained in the memory when the display device is powered off; and

the image shift controller generates the display image signal by processing the shifted image data, and when the display device is powered on after being powered off, the image shift controller generates shifted image data corresponding to a shift path value for a start location on the preset shift path, and then generates shifted image data corresponding to the shift path value stored in the memory,

wherein the image shift controller includes an image smoother configured to modulate the shifted image data by increasing or decreasing gray values of pixels such that a difference in the gray values of the pixels between successive frames does not exceed a predetermined threshold value, and

wherein, for each pixel whose gray value in the shifted image data for a current frame differs from the corresponding pixel in the shifted image data for a previous frame by more than the predetermined threshold value, the image smoother is configured to increase or decrease the gray value of that pixel by only one gray value per frame.

2 . The device as claimed in claim 1 , wherein the image shift controller is to:

compare image data for at least two successive frames; and

when a proportion of same image data in the at least two successive frames exceeds a preset threshold value, generate the shifted image data by modulating the original image data to shift the display image to a next location on the preset shift path.

3 . The device as claimed in claim 2 , wherein the image shift controller is to:

compare image data corresponding to at least two successive frames;

count the image data corresponding to the at least two successive frames as being identical when the proportion of the same image data exceeds the preset threshold value; and

generate the shifted image data by modulating the original image data to shift the display image to a next location on the preset shift path, when a cumulative count value for image data corresponding to three or more frames is equal to or greater than a preset threshold value.

4 . The device as claimed in claim 1 , wherein the image shift controller is to:

generate the shifted image data by modulating the original image data to shift the display image continuously and sequentially along a series of locations on the preset shift path at predetermined time intervals.

5 . The device as claimed in claim 1 , wherein the preset shift path includes a quadrilateral spiral pattern which winds outwardly from a center location.

6 . The device as claimed in claim 1 , wherein the preset shift path includes a zigzag pattern in which the display image is to be shifted in a first direction multiple times, shifted in a second direction once, and then shifted in a third direction multiple times in a repeated manner.

7 . The device as claimed in claim 1 , wherein:

a display image corresponding to the shifted image data includes a blank between at least an edge of the display panel and an edge of the display image, and

the blank corresponds to no image in the original image data.

8 . The device as claimed in claim 7 , wherein the blank of the display image corresponding to the shifted image data is to be filled with black image data.

9 . The device as claimed in claim 7 , wherein:

a portion of the display image adjacent to the blank is to be enlarged; and

the blank of the display image corresponding to the shifted image data is to be filled with the enlarged portion.

10 . The device as claimed in claim 1 , wherein the display image is to be shifted by one pixel column or one pixel row for each shift.

11 . The device as claimed in claim 1 , wherein the memory is a nonvolatile memory.

12 . The device as claimed in claim 11 , wherein:

the memory includes a lookup table indicating the preset shift path; and

the image shift controller is to receive an operation start signal when the display device is powered on, read a shift path value stored in the memory based on the operation start signal, and generate shifted image data corresponding to the stored shift path value by referring to the lookup table.