Patent ID: 6879321

Claim:
A display position control apparatus which uses a first sync signal to control a display position of an image in one direction of a matrix type display device and a second sync signal, which is different from the first sync signal, to control the display position of the image in another direction of the display device to generate a position control signal to control the display position of the image in the display device, comprising: a sync signal generating device which generates a third sync signal having a phase difference held in a preset match state with respect to the phase of the first sync signal; a detecting device which detects whether a phase relation between the phase of the first sync signal and the phase of the second sync signal is held in a preset mismatch state; and a control signal generating device which generates the position control signal on the basis of the first sync signal and the third sync signal when it is detected that the phase relation is in the mismatch state, and generates the position control signal on the basis of the first sync signal and the second sync signal when it is not detected that the phase relation is in the mismatch state, wherein the detecting device comprises: a mismatch detection signal generating device which generates a mismatch detection signal having a preset pulse width on the basis of the second sync signal; and a determining device which determines that the phase relation is in the mismatch state when timing of one pulse of the first sync signal is included within a range of the pulse width of the generated mismatch detection signal, and determines that the phase relation is not in the mismatch state when the timing of one pulse of the first sync signal is not included within the range.