JPS6032491A - Power source circuit of television receiver - Google Patents

Abstract

PURPOSE:To prevent ineffective power consumption by cutting off trigger pulse when operating by DC power source. CONSTITUTION:In a television receiver which is constituted to operate by AC and DC power source, a switch 25 is provided in a circuit that applies trigger pulse from a fly-back transformer 16 to the base of a switching transistor 12 and make it close when AC power source is connected and open when DC power source is connected. Trigger pulse which is unnecessary when the receiver is operated by DC power source is cut off. Accordingly, ineffective power consumption can be eliminated and receiving can be made for a long time by a battery.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a power circuit for a dual power source type television receiver that can be connected to either an AC power source or a DC power source.

Conventional configurations and their problems Television receivers used in areas where AC power is not available or for leisure purposes require two types of power supply circuits: AC and DC. FIG. 1 shows an example of a power supply circuit of such a conventional AC/DC receiver. In the same figure, (1
) is an AC power source, (2) is a DC power source such as a battery, and the AC power source (1) is a pair of connectors (3), and the DC power source ( 2) is connected to the P3 and P4 terminals of the connector (3). When using an AC power supply, the AC power is supplied from the S1 and S2 terminals of the connector (4) connected to the connector (3) through the rectifier circuit (5).
) and further smoothed by a smoothing circuit (6), and the smoothed direct current is applied to the N1 winding of a switching transformer (8) and further connected to a switching transistor (12). Windings N3 and N4 provided in the switching transformer (8), capacitor (9), and fixed resistor (10)
, voltage stabilization circuit (11), and fixed resistor (7) constitute a well-known self-excited switching power supply circuit, and the stabilized intermittent current is passed from the N2 winding of the switching transformer (8) to the diode ( 13) and a capacitor (14), and is applied to the N5 winding of a flyback transformer (hereinafter referred to as FBT) (16), and then applied to the horizontal deflection circuit (15).
) works. Since this operation is also well known, the explanation thereof will be omitted. N of this FBT (16)
A trigger pulse is applied from the 8th winding to the base of the switching transistor (12) through the fixed resistor (24) and the diode (23), and by connecting the switching power supply circuit described above in synchronization with the horizontal deflection frequency, the TV It is possible to remove the interference of AC station wave numbers on the screen of the John receiver.

When using a DC power supply, connect P3 and P of connector (3).
From terminal 4 through S3 and S4 terminals of connector (4),
A DC power supply (2) is added to a voltage stabilizing circuit consisting of a VR output transistor (20), a fixed resistor (21), a Zener diode (22), etc., and the AVR output transistor (
The stabilized DC voltage from the emitter of FBT (20)
16), the horizontal deflection circuit (15) operates, and the television receiver operates.

In the circuit described above, the trigger pulse from the N8 winding of FBT (16) is necessary when the receiver operates on AC power, but is not required when the receiver operates on DC power. However, in the conventional circuit, a tri-force pulse is applied from the NS winding of the FBT to the switching transistor (12) even when operating with a DC power supply. For this reason, the NS winding, fixed resistance (24), diode (23),
There is a drawback that power is wasted in the switching transistor (12) and the like.

Purpose of the Invention As described above, the present invention uses a switching system using a flyback pulse as a trigger pulse to stabilize the AC power supply, and uses a separate stabilization circuit for the DC power supply in the power supply circuit of an AC/DC receiver. The purpose is to eliminate wasteful power consumption when using a DC power source.

Structure of the Invention The present invention supplies a trigger pulse from an FBT to a switching transistor of a power supply circuit using a switching method via a switch, and controls the switch to close when AC power is used and open when DC power is used. This prevents the trigger pulse from being supplied to the switching transistor of the switching circuit when a DC power source is used.

DESCRIPTION OF THE EMBODIMENT FIG. 2 shows a circuit of an embodiment of the present invention. In the figure, the same parts as in FIG. 1 are given the same reference numerals. AC source(
1) is connected to the P1 and P2 terminals of the connector (3), and from the S1 and S2 terminals of the connector (4) through the rectifier circuit (5) and the smoothing circuit (6), is connected to the N of the switching transformer (8).
1 winding, and a switching transistor (1
2) is connected to. and switching transformer (
8) N3 and N4 windings, capacitor (9), fixed resistor (
10), a voltage stabilization circuit (11) and a fixed resistor (7) are stabilized by a switching type power supply circuit, and the intermittent current is passed from the N2 winding of the switching transformer (8) to the diode (13) and the capacitor. (14) converts it into DC and connects it to the N5 winding of the FBT (16) to operate the horizontal deflection circuit (15). Also, the DC power supply (2) is connected to the P1 and P4 terminals of the connector (3), and the
AVR output transistor (20) from S1 and S4 terminals of
, a resistor (21), and a Zener diode (22). The above is similar to the circuit shown in FIG.

In the present invention, the N8 winding of the FBT (16) is connected to the collectors of two Darlington-connected transistors Q1 and Q2 constituting the switch circuit (25), and the emitter of the transistor Q2 is connected to the switching circuit of the self-excited switching power supply circuit. It is connected to the base of the transistor (12), and the output pressure of the AC power rectifier circuit (5) is applied to the base of the transistor Q1 via a fixed resistor R1.

In the above configuration, when the receiver operates on an AC power supply, a DC output is output to the rectifier circuit (5), so that voltage is applied to the base of the transistor Q1 via the fixed resistor R1, turning on the transistor Q1. state, and further Q
The emitter output of 1 is applied to the base of transistor Q2, Q2 is also turned on, and a trigger pulse is applied from the NS winding of FBT (16) to the pace of switching transistor (12) through transistor Q2 to generate the normal take action.

Furthermore, when operating with a DC power supply, the rectifier circuit (5) has no output voltage, so the base voltage of transistor Q1 is 0.
Therefore, Q1 is off, Q2 is also off, and FBT
The trigger pulse from the NS winding (16) is never applied to the base of the switching transistor (12). Therefore, when the receiver operates on DC power, the power of the storage battery is not wasted due to the trigger pulse.

In FIG. 2, (17) is the cathode ray tube, and the voltage B2 obtained from the diode (18), the capacitor (19), and the winding N7 is the power source for other circuits of the receiver.

Effects of the Invention According to the present invention, unnecessary power consumption can be eliminated by eliminating the trigger pulse required when operating on an AC power source when the receiver operates on a DC power source. The present invention can be used in television receivers used in the field or leisure television receivers to reduce battery power consumption and operate the receiver for long periods of time.

[Brief explanation of drawings]

FIG. 1 shows a power supply circuit of a conventional AC/DC television receiver, and FIG. 2 shows a power supply circuit of an embodiment of the present invention. (1) AC power supply, (2) DC power supply, (3), (4
)... Connector, (5)... Rectifier circuit, (8)...
・Switching transformer, (11)... Voltage stabilization circuit, (22)... Switching transistor, (15
)...Horizontal deflection circuit, (16)...Flyback transformer, (17)...Cathode ray tube, (20)...A
VR output transistor, (22)... Zener diode, (25)... switch circuit.

Claims (1)

[Claims] a first circuit that rectifies the AC power supply, intermittents the DC current using a switching transistor that turns on and off using a flyback pulse as a trigger pulse, stabilizes the voltage, and supplies the voltage to the flyback transformer via the rectifier circuit; a second circuit that stabilizes a DC power supply voltage and supplies it to the flyback transformer, and is configured to operate on either an AC power supply or a DC power supply, in which a switching transistor is connected from the flyback transformer. In the circuit that adds a trigger pulse to the base of
A television that is provided with a switch that closes when the receiver is connected to an alternating current power source and opens when the receiver is connected to a direct current power source, thereby interrupting the trigger pulse applied to the switching transistor when the receiver operates on the direct current power source. Receiver power circuit.