초록 ▼

Included are a Zener diode D2 having a cathode connected onto a voltage output line, dividing resistors having one terminal connected to the anode of the Zener diode D2 and having the other terminal grounded, a transistor Q1 having a base connected to the junction point between the dividing resistor

Included are a Zener diode D2 having a cathode connected onto a voltage output line, dividing resistors having one terminal connected to the anode of the Zener diode D2 and having the other terminal grounded, a transistor Q1 having a base connected to the junction point between the dividing resistors via a resistor and having an emitter grounded, a transistor Q2 having a base connected to the junction point between the dividing resistors and having an emitter grounded, and a microcomputer having an undervoltage detection terminal 10a which is connected to the collector of the transistor Q1 and to which 3.3 V is externally applied and a power supply terminal 10b which is connected to the collector of the transistor Q2 and via which a P-ON-H signal of 3.3 V that starts a power supply circuit 126 when the power supply is turned on is transmitted.

대표청구항 ▼

What is claimed is: 1. A panel television that includes a voltage rise suppression circuit that suppresses an excessive rise in an output voltage under a control of a microcomputer that monitors a voltage output line of a flyback power supply circuit, and that displays a picture on a flat panel dis

What is claimed is: 1. A panel television that includes a voltage rise suppression circuit that suppresses an excessive rise in an output voltage under a control of a microcomputer that monitors a voltage output line of a flyback power supply circuit, and that displays a picture on a flat panel display according to a television signal while being supplied a supply voltage from the flyback power supply circuit, comprising: the flyback power supply circuit is controlled based on a feedback signal that is fed back over the voltage output line; the voltage rise suppression circuit includes: a first Zener diode having a cathode coupled with the voltage output line and having an anode that is grounded; a second Zener diode having a cathode coupled with the voltage output line; dividing resistors having one terminal coupled with an anode of the second Zener diode and having the other terminal grounded; a first transistor having a base coupled with a junction point between the dividing resistors via a first resistor and having an emitter that is grounded; a second transistor having a base coupled with the junction point between the dividing resistors via a second resistor and having an emitter that is grounded; and a microcomputer having an undervoltage detection terminal that is connected to a collector of the first transistor and to which a fixed voltage is externally applied and a power supply terminal that is connected to a collector of the second transistor and via which a P-ON-H signal that starts the flyback power supply circuit when the power supply is turned on is transmitted; when the output voltage rises, a Zener current flows through the second Zener diode, a voltage is developed at the junction point, and the voltage is applied to the bases of the first and second transistors respectively; the first and second transistors are turned on; the voltage at the undervoltage detection terminal is routed to a ground, and the P-ON-H signal to be sent to the flyback power supply circuit via the power supply terminal is also routed to the ground; the power supply circuit stops and the output voltage drops; when the output voltage drops to fall within a normal range, the Zener current does not flow through the second Zener diode any longer; the first and second transistors are turned off, and the undervoltage detection terminal and power supply terminal are not grounded any longer; and the P-ON-H signal sent via the power supply terminal reaches the flyback power supply circuit to start the power supply circuit; and the microcomputer obtains the voltage at the undervoltage detection terminal at intervals of a predetermined number of times; and when the microcomputer detects a voltage equal to or lower than a predetermined voltage plurality of consecutive times, the microcomputer ceases the transmission of the P-ON-H signal via the power supply terminal. 2. A voltage rise suppression circuit that suppresses an excessive rise in an output voltage by monitoring a voltage output line of a flyback power supply circuit, comprising: a Zener diode that has a cathode coupled with the voltage output line and that undergoes a Zener breakdown when an output on the voltage output line exceeds a predetermined value; dividing resistors having one terminal coupled with an anode of the Zener diode and having the other terminal that is grounded; a first transistor having a base coupled with a junction point between the dividing resistors and having an emitter that is grounded; an undervoltage detection terminal connected to a collector of the first transistor; a power supply terminal through which a voltage signal that starts the flyback power supply circuit is transmitted; a second transistor having a base coupled with the junction point between the dividing resistors, having an emitter that is grounded, and having a collector coupled the power supply terminal; and a voltage rise suppression unit that controls the power supply terminal according to the voltage at the undervoltage detection terminal. 3. The voltage rise suppression circuit according to claim 2, wherein the voltage output line is a line over which a voltage to be monitored is fed back in order to control the power supply circuit. 4. The voltage rise suppression circuit according to claim 2, wherein the voltage rise suppression unit senses a drop in a voltage applied to the undervoltage detection terminal and controls a signal to be transmitted via the power supply terminal. 5. The voltage rise suppression circuit according to claim 2, wherein: the voltage rise suppression unit detects the voltage applied to the undervoltage detection terminal at intervals of a predetermined time; and when the voltage rise suppression unit senses the voltage being lower than the predetermined voltage a predetermined number of times, the voltage rise suppression unit ceases the transmission of the signal via the power supply terminal so as to stop the power supply circuit.