| 摘要 |
A display apparatus of the CRT type displays information by use of a magnetic field. In this apparatus, a deviation amount of the image displayed on the CRT display screen from a reference position is detected by photo sensors arranged at the peripheral positions of the screen. The phase of the display information signal is adjusted for the vertical and horizontal sync signals regarding the CRT so that the display information can be displayed at the reference position on the screen on the basis of the detection information which is obtained from the photo sensors. Thus, the display information can be accurately displayed at the reference position on the CRT screen irrespective of whether the CRT screen is vertically or horizontally set without any influence of an electron beam by the deflecting coils of the display apparatus due to the earth's magnetic field or the like.
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