| 摘要 |
PURPOSE:To enable easy identification of a reference value in a display picture by conducting digital comparison of a value of an input signal with the reference value and changing the brightness of a display unit in accordance with the result of the comparison in the display unit wherein orthogonal coordinates are displayed by digital signals. CONSTITUTION:A digital signal delivered from an AD converter 4 based on an analog signal supplied to an input terminal 1 is supplied to one input end of a digital comparator 9. Meanwhile, a digital value as a reference value delivered from an AD converter 13 based on a voltage generated in a variable resistor 10 or 11 selected by a switch 12 is supplied to the other input end of the comparator 9. When a bit value inputted from the AD converter 13 is a signal of ''1'' level indicating a significant condition, the comparator 9 inverts the condition of the input signal of the comparator 9 corresponding to the bit and delivers the same, and when the bit value is a signal of ''0'' level indicating a non-significant condition, the condition of the input signal of the comparator 9 is delivered as it is. By this constitution, the brightness of a display unit 6 is changed to facilitate observation of the reference value in a display picture. |
