| 摘要 |
PURPOSE:To confirm and accurately calibrate the gain and DC offset characteristics of a display device by supplying the output signal of a display reference signal generating device or the display device to display a graphic form which indicates a maximum and a minimum value, and comparing the graphic form with a scale. CONSTITUTION:A potentiometer 30a supplies a DC voltage corresponding to the maximum permissible amplitude based upon the scale on a display screen to a signal generating means 34 and a potential meter 32a supplies a DC voltage corresponding to the minimum permissible amplitude. The means 34 is equipped with inverting and noninverting amplifiers 10 and 12 whose input terminals are connected in common and DC voltages are selected alternately by electronic switches 14 and 16 at the input terminals and output terminals of the amplifiers 10 nd 12 to obtain pulse signals 36, i.e. maximum permissible value reference signal and minimum permissible value reference signal. Those reference signals are supplied to the deflecting circuit of the display device to display the maximum and minimum values on the display screen alternately, and the display graphic form is compared with the scale to easily and accurately know whether or not the calibration state of the display device is within the permissible value range.
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