| 摘要 |
PURPOSE: A focus unit having high voltage feedback of a fly back transformer is provided to print resistor for a feedback line for stably sensing high voltage variation without increasing the size of the fly back transformer. CONSTITUTION: A focus unit of a fly back transformer is coupled to a high voltage output via a bleeder resistor(BR1) and formed by printing a resist pattern on a printed circuit board to output a focus voltage(Fv) and a screen voltage(Sv). The focus unit comprises a first variable resistor(VR1), a dynamic capacitor(C10), a second variable resistor(VR2), and a feedback resistor(R10). The first variable resistor(VR1) is coupled to the bleeder resistor(BR1) via a resistor(R11), and coupled to a focus voltage output via a bypass resistor(R14). The dynamic capacitor(C10) is coupled between the bypass resistor(R14) and the focus voltage output, and receives a parabolic phase voltage. The second variable resistor(VR2) is coupled to the first variable resistor(VR1) via a resistor(R12), grounded via a resistor(R13), and coupled to a screen voltage output via a bypass resistor(R15). The feedback resistor(R10) is coupled to the bleeder resistor(BR1) and forms a feedback voltage output.
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