JPS6024038Y2 - Television receiver power circuit - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a television receiver power supply circuit suitable for use in a television receiver with a built-in radio receiver.
In particular, the system is designed to prevent interference sounds from being generated when switching to playback from a radio receiver rather than when playing back a television receiver.

2. Description of the Related Art Conventionally, a television receiver with a built-in radio receiver as shown in FIG. 1 has been proposed.

That is, in Fig. 1, la and lb are, for example, 50H2100.
The commercial power supply input terminals 1a and lb are connected to the power transformer for the television receiver via the power switch 2 for the television receiver. At the same time, this commercial power is supplied to the primary winding 5a of the power transformer 5 for the radio receiver via the power switch 4 for the radio receiver.

In this case, power switches 2 and 4 are linked, so that when power switch 2 is on, power switch 4 is off, and when power switch 2 is off, power switch 4 is
so that it turns on.

Further, the other end of the secondary winding 3b of the power transformer 3 is grounded, and one end of this is connected to the input side of a rectifier circuit 6 consisting of a diode 6a and a smoothing capacitor 6b, so that the direct current obtained at the output side of the rectifier circuit 6 is This rectifier circuit 6 supplies voltage as a DC power source to the load, that is, the television circuit 7.
The output side of the is grounded through a series circuit of a resistor 8 and a ripple filter capacitor 9, and the DC voltage obtained at the connection point of the resistor 8 and capacitor 9 is connected to the DC voltage of the horizontal oscillation circuit 10 of the television receiver. It is supplied as a power source.

Further, the AC voltage obtained at the secondary winding 5b of the power transformer 5 is supplied to the input side of the rectifier circuit 11, and the DC voltage obtained at the output side of the rectifier circuit 11 is supplied as the DC power source for the radio receiver circuit 12. ing.

In FIG. 1, 13 is a radio receiver antenna built into the cabinet of the television receiver, and 14 is a speaker.

In FIG. 1, when the power switch 2 is turned on, the television receiver can be played back, and when the power switch 4 is turned on, the radio receiver can be played back.

However, in a television receiver with a built-in radio receiver as shown in FIG. 1, when switching from the television receiver's playback to the radio receiver's playback, the power switch 2 is turned off, but ripples occur. The charge stored in the filter capacitor 9 is not discharged instantly, and it takes about 2 to 3 seconds to complete the discharge. During this time, the horizontal oscillation circuit 10 operates, and the oscillation signal from the horizontal oscillation circuit 10 is transmitted to the radio receiver. There was a drawback that the noise could be heard through the built-in antenna 13 and cause interference to radio receivers.

In view of this, the present invention has been developed to solve the problem that, in a television receiver with a built-in radio receiver as described above, interference noise occurs when switching to playback from the radio receiver rather than when playing back the television receiver. I made it so that it wasn't.

An embodiment of the power supply circuit of the television receiver of the present invention will be described below with reference to FIG.

In FIG. 2, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and their explanations will be omitted.

In the example shown in FIG. 2, the connection point between the resistor 8 and the capacitor 9 is connected to the anode of the diode 16 via the capacitor 15, and the cathode of the diode 16 is connected to the rectifier circuit 6.
A resistor 17 having a relatively high resistance value, for example, 100Ω or more, is connected in parallel to the diode 16.

In this case, the diode 16 and resistor 17 are used to prevent ripples from being transmitted to the power supply terminal of the horizontal oscillation circuit 10, and the capacitor 15 is charged through the resistor 17.

The rest of the structure is the same as in FIG.

In the example shown in Fig. 2, when switching from the television receiver to the radio receiver reproduction mode, that is, when the power switch 2 is turned off and the power switch 4 is turned on, the ripple filter is activated. The charge stored in the capacitor 9 is instantaneously discharged through the capacitor 15, the diode 16, and the television circuit 7, and the oscillation operation of the horizontal oscillation circuit 10 is also instantaneously stopped.

Therefore, the oscillation signal from the horizontal oscillation circuit 10 does not enter the antenna 13 of the radio receiver as interference sound.

It is easy to understand that the other parts operate in the same manner as in FIG.

As described above, according to the present invention, when the power switch 2 of the television receiver is turned off, the oscillation operation of the horizontal oscillation circuit 10 stops instantaneously, so that the horizontal oscillation circuit 10 does not generate disturbing noise. Therefore, the present invention is extremely suitable for use in a television receiver with a built-in radio receiver.

It goes without saying that the present invention is not limited to the above-described embodiments, and that various other configurations may be adopted without departing from the gist of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a power supply circuit of a conventional television receiver, and FIG. 2 is a block diagram showing an example of a power supply circuit of a television receiver of the present invention. la and lb are commercial power input terminals, 2 and 4 are power switches, 3 and 5 are power transformers, 6 and 11 are rectifier circuits, 7 is a television circuit, 8 and 17 are resistors, 9 and 15 are respectively 10 is a horizontal oscillation circuit, 12 is a radio receiver circuit, and 16 is a diode.

Claims (1)

[Scope of utility model registration request] A voltage from a power supply circuit having a smoothing capacitor is supplied to the load and also to a series circuit of a first resistor and a first capacitor, and the voltage across the first capacitor is supplied as the power supply voltage of the horizontal oscillation circuit. In the power supply circuit of the television receiver, the connection point between the first capacitor and the first resistor is connected to a series circuit of the second capacitor, a diode, and a parallel circuit of the second resistor. to the connection point between the output side of the power supply circuit and the load, and when the power switch is cut off, the charge remaining in the first capacitor is immediately transferred to the second capacitor and the diode. A power supply circuit for a television receiver, characterized in that the horizontal oscillation circuit is discharged and oscillation of the horizontal oscillation circuit is immediately stopped.