JPH05236396A - Electric power unit for television - Google Patents

Abstract

PURPOSE:To reduce the size of the power unit by eliminating the need to use two power sources for an in-absence automatic recording and a stand-by function for satellite broadcasting as to a switching power source which is used for the television receiver. CONSTITUTION:A source voltage is supplied to a satellite broadcast receiving circuit 31 through a transformer 4 and rectifying circuits 27 and 28. This voltage is fed back to a control part 23 through a photocoupler 33 to stabilize an output voltage. Further, the output of a rectifier circuit 26 is supplied to a dedicated regulator 31 for stabilization against load variation. Thus, the electric power is supplied to a horizontal deflecting circuit 12 and other video signal circuits. In in-absence automatic video recording mode, the operation of this regulator 31 is stopped to stop electric power supply to the part after the horizontal deflecting circuit 12, all circuits for image projection are stopped, and the power source is continuously supplied to a satellite broadcast receiving circuit 19. This constitution reduces the size of the television power unit incorporated in a satellite broadcast receiver having the in-absence automatic video recording function.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a television receiver having a function of receiving satellite broadcasts, teletext broadcasts, etc., which is designed to supply a stable DC voltage and to be operated independently. The present invention relates to a power supply device for John.

[0002]

2. Description of the Related Art In recent years, television receivers have come to have a built-in satellite broadcast receiver or teletext receiver so that each individual receiver can be operated independently. In order to cope with such multi-functionalization, conventionally, an independent power source is provided for each function so that each individual operation is possible.

A conventional television power supply device will be described below. FIG. 4 shows the configuration of a conventional television power supply device. In this figure, AC power supply terminal 1
Is connected to a transformer 3 via a manual main switch 2 for stopping all power to the television receiver. The transformer 3 is a transformer for remote control that supplies a standby power supply, and its secondary output is supplied with a constant voltage to a microcomputer (not shown) via the rectification circuit unit 4 for the standby power supply. Further, as shown in the figure, the power supply is provided with a relay switch 5 for turning on / off the power of the television receiver based on an external control signal, and a relay switch 6 for turning on / off the power of only the television receiver. A rectifier circuit 8 is provided on the secondary side of these relay switches 5 and 6 via a line filter 7 as shown in the figure. A rectifier circuit 10 is provided at the terminals of the main switch 2 and the relay switch 5 via a line filter 9. Reference numeral 11 denotes a switching power supply which receives the power source rectified by the rectifier circuit 8 and supplies power to each circuit of the television receiver, that is, the horizontal deflection circuit 12 and the high voltage generation circuit 13 connected thereto. The vertical deflection circuit 14, the video signal processing circuit 15, and the audio output circuit 16 are each supplied with a power source of a predetermined voltage. The switching power supply 18 is a switching power supply that is connected to the secondary side of the rectifier circuit 10 to generate each voltage for satellite broadcasting, and its output is given to the satellite broadcasting receiving circuit 19.

The operation of the power supply device of the television receiver thus configured will be described. First, when the main switch 2 is closed, AC voltage is supplied from the AC power input terminal 1 to the transformer 3 for remote control.
Standby power is generated in the rectifier circuit 4 on the secondary side, and power is supplied to a microcomputer (not shown) to start operation. At this time, if the user of the television selects to watch the television, the relay switches 5 and 6 are output so as to be closed together by the control signal from the microcomputer. Then, the AC voltage from the AC input terminal 1 passes through the line filter 7, and the power supply voltage rectified by the rectifier circuit 8 is supplied to the switching power supply 11 and similarly to the rectifier circuit 10.
Is supplied to the switching power supply 18, and oscillation is started. Then, the switching power supply 11 supplies a power supply of a predetermined voltage to each of the horizontal deflection circuit 12, the vertical deflection circuit 14, the video signal processing circuit 15, and the audio output circuit 16, which are loads on the secondary side, as shown in FIG. .. Similarly, the switching power supply 18 also supplies a power supply voltage to the satellite broadcast receiving circuit 19. Therefore, at this time, the television is in a state in which all circuits for displaying an image and outputting a sound operate so that the user can arbitrarily watch a normal television broadcast program and a satellite broadcast program.

Next, a state where the satellite broadcast program is recorded in the answering machine from the above state will be described. That is, when recording an arbitrary program with the video recorder connected when the user is absent, power is not supplied to the circuit on the television receiver side to save power, and only the satellite broadcast receiving circuit is operated. It is a function.

When a user desires to record an answering machine and gives an instruction from a remote controller (not shown) or a keyboard on the front of the television, the microcomputer receives the instruction and outputs a control signal to open the relay switch 6. Then, since the power supply voltage is not supplied to the switching power supply 11 through the line filter 7 and the rectifier circuit 8, it does not operate.
Therefore, each circuit, which is the load on the secondary side, does not operate, and no image appears on the screen. At this time, the main switch 2 and the relay switch 5 remain closed,
The switching power supply 18 is operating, and the satellite broadcast receiving circuit 19 selects an arbitrary broadcast and continues to operate, so that it is possible to record an answering machine.

[0007]

However, such a conventional structure requires two line filters, two rectifier circuits, and two switching power supplies, which results in a large mounting area and a high cost. It was

The present invention has been made in view of the above problems, and provides a small-sized power supply device for a television receiver capable of performing an unattended recording operation for satellite broadcasting and text broadcasting with a single switching power supply. It is a thing.

[0009]

SUMMARY OF THE INVENTION The present invention is a switching power supply circuit which is connected to a commercial AC power supply and outputs a plurality of stabilized power supply voltages, one end of which is connected to a satellite broadcast receiving circuit, and a switching power supply circuit. A regulator circuit for supplying power to the video circuit of the television receiver by supplying power from one end to stabilize the output voltage, and first switch means for connecting and disconnecting the output of the regulator circuit,
It is characterized in that power is supplied to the video circuit by connecting and disconnecting the switching means.

[0010]

According to the present invention having such features, the first
By closing the switch means, a constant voltage is supplied to the satellite broadcast receiving circuit by the switching power supply circuit, and at the same time, power is supplied to the video circuit via the regulator circuit. If you want to set the answering machine to recording,
The switch circuit stops the output of the regulator circuit. Then, only the power supply to the video circuit is stopped. However, since the satellite broadcast receiving circuit is always supplied with power, it is possible to record an answering machine.

[0011]

(Embodiment 1) A first embodiment of the present invention will be described below with reference to FIGS. 1 and 2. In this embodiment, the same parts as those in the conventional example described above are designated by the same reference numerals, and detailed description thereof will be omitted. In this embodiment, a line filter 21 is connected to the main switch 2 and a rectifier circuit 22 is provided on the secondary side thereof. The rectifier circuit 22 generates a rectified DC voltage, and its output end is connected to the controller 23 and one end of the primary winding of the transformer 24. The other end of the primary winding is grounded via a transistor 25 which is intermittently connected by the controller 23. Also this transformer 2
Rectifier circuits 26 to 30 are connected to the secondary side of No. 4. The rectifier circuit 26 is a dropper type regulator circuit 31 shown in FIG.
The rectifying circuits 27 and 28 supply power to the satellite broadcast receiving circuit 19, and the rectifying circuit 29 supplies power to the audio output circuit 16. The rectifier circuit 30 supplies power to the control unit 23. Further, the output of the rectifier circuit 27 is amplified via the error amplifier 32 and given to the input end of the photocoupler 33. The photocoupler 33 supplies the error voltage signal as a feedback signal to the control unit 23.
Here, the transformer 24, its rectifying circuits 26 to 30, the error amplifier 32, the photocoupler 33, the control unit 23, and the transistor 25 constitute a switching power supply circuit that outputs a plurality of stabilized power supply voltages.

In the regulator circuit 31 shown in FIG. 2, the output terminal of the rectifier circuit 26 is the transistor 4 as shown in FIG.
1 and a drive resistor 42 is connected between the base and collector thereof. The emitter is a resistor 43,
It is grounded via a voltage dividing circuit 44, and the midpoint thereof is fed back to the transistor 41 via an error amplifying circuit 45 to form a dropper type regulator.
This stabilized power supply is supplied to the horizontal deflection circuit 12. The flyback pulse is applied to the high voltage generating circuit 34. Further, in this embodiment, a microcomputer 46 and a switching transistor 47 are provided as the first switch means for stopping the operation of the regulator circuit 31. The switching transistor 47 has its collector grounded to the base of the transistor 41 and its emitter grounded.

Next, the operation of this embodiment will be described. First, a case where all circuits are operated will be described. When the main switch 2 is closed, the AC voltage from the AC input terminal 1 is applied to the rectifier circuit section 22 via the line filter 21 and converted into a DC voltage. Since this output is given to the control unit 23, the control unit 23 starts oscillating and interrupts the transistor 45. Then, a voltage is generated at each voltage terminal on the secondary side of the transformer 24. The power supply voltage of the satellite broadcast receiving circuit 19, which is a stabilization target voltage that should avoid voltage fluctuations due to load fluctuations, is fed back to the control unit 23 via the error amplifier 32 and the photocoupler 33. Therefore, when the power supply voltage reaches a predetermined voltage, the system becomes stable. After that, the control unit 23 is supplied with a stable voltage by the rectifier circuit 30.

Since the power supply voltages from the smoothing circuits 27 and 28 are supplied to the satellite broadcast receiving circuit 19 and the power supply voltage of the smoothing circuit 29 is supplied to the audio output circuit 16, each circuit operates normally. Further, the voltage stabilized by the regulator circuit 31 is applied to the horizontal deflection circuit 12. Then, the flyback pulse is applied to the high voltage generation circuit 34, and the high voltage for the cathode ray tube is generated. At the same time, by setting the transformer winding ratio on the secondary side of the high voltage generating circuit 34 arbitrarily, a constant voltage, for example, the vertical deflection circuit 14 or the video signal processing circuit 1 can be obtained.
A low voltage (about 30 to 12 V) for 5 can be generated, and these are supplied to the vertical deflection circuit 14 and the video signal processing circuit 15. In this way, the image is displayed and the audio circuit can be operated.

Next, the operation to reach the recorded state of the satellite broadcast will be described. The microcomputer 46 turns on the transistor 47 in response to a user's instruction. Then, the base voltage of the transistor 41 is lowered, so that the transistor 41 is turned off, and the voltage is not supplied to the horizontal deflection circuit 12 and thereafter. Therefore, no image is displayed on the television receiver, and the satellite broadcast receiving circuit 19 continues to operate. Here, the power is supplied to the audio output circuit 16 as it is. It is possible to mute the sound by a signal from the microcomputer 46.
This is also to enable use for satellite broadcasting reception of audio only, if necessary.

A second embodiment of the present invention will be described below with reference to the drawings. In this embodiment, the satellite broadcast receiving circuit 1
A teletext receiving circuit 51 is provided in parallel on the power source side of 9 so that the teletext receiving circuit 51 side can always be supplied with power, and the satellite broadcasting receiving circuit 16 is powered by a second switch means. The switch 52 allows the connection and disconnection. In the standby operation of teletext, if the user controls the switch 52 to be in the off state, power can be supplied only to the teletext receiving circuit 51. Therefore, it becomes possible to save the program previously selected by the user in the memory in the teletext receiving circuit 51.

[0017]

As described in detail above, according to the present invention, it is possible to realize a single power supply for a power supply circuit using a plurality of conventional switching power supplies. Therefore, the mounting area occupied by the power source can be reduced to about 1/2. Further, since the structure is simplified, the effect that the cost can be reduced can be obtained.

[Brief description of drawings]

FIG. 1 is a circuit diagram (part 1) showing a television power supply device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram (part 2) showing a television power supply device according to an embodiment of the present invention.

FIG. 3 is a circuit diagram showing a television power supply device according to a second embodiment of the present invention.

FIG. 4 is a circuit diagram showing a conventional television power supply device.

[Explanation of symbols]

 1 AC input power terminal 2 Main switch 5,6 Relay switch 7,9,21 Line filter 4,8,10,22,26 ~ 30 Rectifier circuit 11,18 Switching power supply 12 Horizontal deflection circuit 13,34 High voltage generation circuit 14 Vertical Deflection circuit 15 Video signal processing circuit 16 Audio output circuit 19 Satellite broadcast receiving circuit 23 Control unit 24 Transformer 31 Regulator circuit 32 Error amplifier 33 Photocoupler 46 Microcomputer 47 Transistor

Claims (2)

[Claims] 1. A switching power supply circuit which is connected to a commercial AC power supply and outputs a plurality of stabilized power supply voltages, one end of which is connected to a satellite broadcast receiving circuit, and power is supplied from one end of the switching power supply circuit. A regulator circuit for stabilizing the output voltage to supply power to the video circuit of the television receiver; and a first switch means for connecting and disconnecting the output of the regulator circuit. A power supply unit for a television, characterized in that it is configured to supply power to a power supply circuit. 2. The television power supply device according to claim 1, further comprising second switch means for connecting and disconnecting the power supplied to the satellite broadcast receiving circuit.