JPH06253319A - Television receiver - Google Patents

Abstract

PURPOSE:To supply a control circuit for a relay driving the degaussing circuit of a CRT from a simple subordinate power source. CONSTITUTION:Under the control of a microcomputer 41, a switching transistor(TR) Q2 which turns ON and OFF a degaussing relay RY2 by intermitting the stand-by voltage from a remote control power source part 3 and a switching TR Q1 which turns ON and OFF a main relay RY1 by intermitting the stand-by voltage are driven; when the switching TR Q2 is ON, the stand-by voltage is applied through a switching TR Q3, which is provided in parallel to a limiting resistance R2 and turned ON and OFF by the switching TR Q2, while by-passing a limiting resistance R2 connected in series with the relay coil of the main relay RY1 driving the switching TR Q1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver, and more particularly to a television receiver having a remote control standby power supply and a degaussing circuit.

[0002]

2. Description of the Related Art Depending on the conditions under which a television receiver is installed, the shadow mask may be magnetized due to the magnetism due to the earth's magnetism, or the shadow mask or chassis of a CRT may be magnetized due to a leakage magnetic field from inside or outside the set. is there. For example, if the shadow mask is magnetized, the electron beam will not be scanned accurately, the color purity will deteriorate, and color unevenness will occur on the screen. Therefore, the degaussing section including a degauss coil wound around the periphery of the shadow mask automatically degausses the shadow mask when the power is turned on.

FIG. 2 is a diagram showing an example of the configuration of the degaussing circuit. In this figure, DL is a degaussing coil wound around a shadow mask of a CRT (not shown) to generate an AC magnetic field, and TH is a posistor whose resistance value increases due to temperature rise due to self-heating. Attenuate the current flowing through. RY1 indicates a degauss relay which is turned on by the control of the microcomputer when the power is turned on.

First, when the power is turned on, the television receiver enters the operating state and at the same time, the degauss relay RY is turned on.
1 is turned on, AC power is also supplied to the degaussing circuit, and an AC magnetic field is generated in the degaussing coil DL. The resistance value of the posistor TH increases as the temperature rises, and the alternating current flowing through the degaussing coil DL is attenuated. Thus, with the increase in the resistance value of the posistor TH, the demagnetization of the CRT is performed in about 5 to 6 seconds, for example.

This degaussing circuit is designed to operate automatically when the power is turned on. However, for example, when a current is flowing through the vertical deflection coil of the deflection yoke, it is sufficiently degaussed due to the influence of the magnetic field distribution. Since the effect cannot be obtained, the degaussing circuit is operated before the main power source is started up, and V oscillation by the deflection system circuit is started after the degaussing by the degaussing circuit is completed.

[0006]

By the way, in a television receiver having a built-in satellite broadcast tuner,
In addition to the main power supply, it has a sub power supply so that the output of the satellite broadcast tuner can be recorded even during standby. Therefore, it is possible to operate the satellite broadcast tuner and peripheral circuits from the sub power supply without turning on the main power supply. Therefore, it is possible to supply the power of the degauss relay that operates the degaussing circuit using this sub power supply, but in this case, because the voltage regulation of the sub power supply for rectifying the power supply for the degauss relay is not very good, There is a problem in that the cost is increased because the power source is strengthened.

Further, even in a model without a built-in satellite broadcasting tuner, since it is necessary to supply power to the degauss relay, a sub power supply is required, manufacturing costs are high, and power consumption is low. There was a problem that it would end up.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and includes a first relay switch inserted in an AC voltage input line and the first relay switch. AC power supply to generate a DC voltage, a standby power supply circuit to generate a standby voltage from the AC voltage from the AC voltage input line, and a standby power supply to be supplied from the standby power supply circuit. It is composed of a control unit to which a voltage is supplied and a degaussing unit to which an AC voltage is supplied via a second relay switch and which performs a degaussing operation of the CRT.

The control unit connects and disconnects the standby voltage to control the ON / OFF of the second relay switch, and connects and disconnects the standby voltage to the first switching transistor. When a second switching transistor that performs on / off control is driven and the second relay switch is turned on, a limit connected in series to a relay coil that drives the first relay switch. It is designed to bypass the resistor and apply the standby voltage.

[0010]

For example, the sub-power supply, the rectifying circuit for the degaussing relay, etc. can be omitted, the manufacturing cost can be suppressed, and the power consumption during standby of the remote controller can be reduced.

[0011]

Embodiments of the television receiver of the present invention will be described below. FIG. 1 is a block diagram showing an example of the power supply and degaussing circuit of the television receiver of this embodiment. In this figure, RY1 is a main relay for switching the power supply to the switching power supply unit 2 which will be described later, R1 is a resistor for suppressing an inrush excessive current when the main relay RY1 is operated,
D1 is a rectifying circuit for rectifying a commercial AC voltage, and C1 is a smoothing capacitor for smoothing the direct current rectified by the rectifying circuit D1.

A part 1 surrounded by a broken line shows a switching power supply part. Reference numeral 11 is a switching regulator 11 for converting a DC voltage into an AC voltage by ON / OFF control and converting its output voltage into a constant voltage. T1 insulates and boosts the voltage converted into a constant voltage by the switching regulator 11. A converter transformer is shown, and power for each circuit of the television receiver is supplied from the secondary side. High-voltage current is supplied as power +
Lo used mainly in control circuits at a pressure lower than B and + B
w ・ B, Audio ・ used for power supply for audio
There is B etc.

A part 2 surrounded by a broken line shows a degaussing circuit. In this degaussing circuit 2, DL represents a degaussing coil, which is wound so as to surround the shadow mask peripheral portion of a CRT (not shown) and generates an AC magnetic field when AC power is supplied. TH indicates a posistor having a characteristic that the resistance value increases as the temperature rises due to self-heating. In this posistor TH, the resistance value rapidly increases as the temperature rises due to the Joule heat generated in proportion to the flowing current, and the current gradually becomes difficult to flow. RY2 represents a degauss relay that switches the degaussing circuit 2 on and off.

When degaussing is performed by the degaussing circuit 2, when the power is turned on, the degauss relay RY2 is controlled by the microcomputer 41 of the remote controller control unit 4 which will be described later.
Is turned on, and current starts to flow in the degaussing coil DL,
Demagnetization is initiated by the generation of an alternating magnetic field. At the same time, the resistance value increases due to the rise in the temperature of the posistor TH, and the current flowing through the degaussing coil DL is attenuated, so that the degaussing effect can be obtained.

A part 3 surrounded by a broken line shows a remote control power supply part. T2 is a remote control transformer that isolates and steps down commercial AC voltage, D2 is this remote control transformer T2
A rectifier circuit that rectifies the voltage supplied from the secondary coil of C, and C2 represents a capacitor that smoothes the direct current rectified by the rectifier circuit D2. The voltage rectified / smoothed by the rectifier circuit D2 and the capacitor C2 is used as a remote controller standby power source, a power source for remote controller control, etc.
Is supplied to.

Reference numeral 4 surrounded by a broken line indicates a remote controller control section for controlling the relays and the like. In the remote controller control unit 4, Q1 is a switching transistor for switching the main relay RY1, and Q2 is a switching transistor.
Indicates a switching transistor for switching the degauss relay RY2 of the degaussing circuit 2. Reference numeral 41 denotes a microcomputer, which is operated by the power source supplied from the remote controller power source section 3 and operates from the remote commander RC to the infrared ray receiving section 5
According to the operation command input via the switch, for example, when the power switch on command is input, the switching transistors Q1 and Q2 are controlled. R
Reference numeral 2 is a limiting resistor for maintaining the operation guarantee voltage of the main relay RY1, Q3 is a switching transistor which short-circuits the limiting resistor R2 of the main relay RY1, and is connected from the base to the collector of the switching transistor Q2 via the resistor R4. ing.

The operation of each circuit will be described below. First, when a commercial AC voltage is input, power is supplied to the microcomputer 41 of the remote controller control unit 4 via the remote controller transformer T2, and the remote controller control unit 4 enters a standby state. When a power-on control signal is input from the remote commander RC to the microcomputer 41, a predetermined voltage is applied to the base of the switching transistor Q2 to turn it on, so that a current that turns on the degauss relay RY2 is generated. As a result, the degaussing circuit 2 starts degaussing.

Since the remote control power source section 3 is composed of a simple rectifying circuit, the voltage regulation is not good. Therefore, when the switching transistor Q2 is turned on and the degauss relay RY2 is turned on, the voltage at the point A is lowered and the limiting resistor R2 is further inserted, so that a predetermined voltage is applied to the base of the switching transistor Q1 to turn it on. Even so, the voltage at point B is low and the main relay R
Sufficient current does not flow to turn on Y1, and it is impossible to activate the switching power supply unit 1.

Therefore, at the same time when the switching transistor Q2 is turned on, the switching transistor Q3 is turned on by the voltage divided by the resistors R3 and R4. Then, after the switching transistor Q1 is turned on (for example, after about 0.5 ms), at the time when the switching transistor Q2 is turned on, the current bypassing the limiting resistor R2 is allowed to flow in the main relay RY1.

In this way, the switching transistor Q is supplied with the current supplied from the remote control power supply unit 3 in a state of bypassing the limiting resistor R2 and flowing to the main relay RY1.
When 1 is turned on, a current that allows operation is made to flow through the main relay RY1, and the switching power supply unit 1 starts supplying power to each functional circuit of the television receiver. Become.

When the degaussing operation is completed by the action of the posistor TH, for example, about 5 to 6 seconds after the degaussing is started, the switching transistor Q2 is turned off by the control of the microcomputer 41, and the current is supplied to the degauss relay RY2. Will not be supplied. At the same time switching transistor Q
3 is also off. In this case, since the voltage at the point A rises, by turning off the switching transistor Q3, a voltage that does not exceed the operation guarantee voltage is applied to the coil of the main relay RY1 via the limiting resistor R2. The switching operation of the main relay RY1 is guaranteed. The voltage supplied from the remote control power supply unit 3 may be obtained from the power supply for the BS tuner.

[0022]

As described above, in the television receiver of the present invention, when the degauss relay is operating,
Since the voltage supplied from the remote control power supply to the main relay decreases, the current shorting the limiting resistor is supplied, the degaussing relay is turned off, the degauss relay is turned off, and the voltage supplied to the main relay rises. The operation guarantee voltage comes to be supplied through the limiting resistor. Therefore, stable power supply is always realized from the remote control power supply to both the degaussing circuit and the main power supply circuit. That is, the power supply for the degaussing circuit, which was conventionally supplied from the sub power supply used for satellite recording, can be supplied from the simplified remote control power supply. Also, for example, even in a model without a built-in satellite broadcasting tuner, it is not necessary to provide a sub power supply for the Degauss relay, the cost is reduced, the loss of the sub power supply is eliminated, and the power consumption can be reduced. In addition, even in models with a built-in satellite broadcasting tuner, the rectifier circuit for the power supply for the Degauss relay can be omitted, and load fluctuations due to opening and closing of the Degauss relay can be prevented, so the sub power supply can be efficiently designed and power consumption can be reduced. become.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a degaussing circuit and a power supply circuit of a television receiver according to the present invention.

FIG. 2 is a diagram showing an example of a degaussing circuit.

[Explanation of symbols]

 1 Switching power supply unit 2 Degaussing circuit 3 Remote control power supply unit 4 Remote control unit TH Posistar DL Degauss coil RY1 Main relay RY2 Degauss relay Q1, Q2, Q3 Switching transistor R2 Limiting resistor

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[Procedure amendment]

[Submission date] April 12, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

Claims (3)

[Claims] 1. A first relay switch inserted into an AC voltage input line, a main power supply circuit section which is supplied with an AC voltage via the first relay switch to generate a DC voltage, and the AC voltage input line. A standby power supply circuit section for generating a standby voltage from the AC voltage from the controller, a control section supplied with the standby voltage supplied from the standby power supply circuit section, and an AC voltage supplied via a second relay switch. , C
And a degaussing unit for degaussing the RT, wherein the control unit connects and disconnects the standby voltage with a first switching transistor that performs on / off control of the second relay switch by connecting and disconnecting the standby voltage. Thereby driving a second switching transistor that performs on / off control of the first relay switch, and when the second relay switch is on, a relay that drives the first relay switch. A television receiver configured to apply a standby voltage by bypassing a limiting resistor connected in series with a coil. 2. The television image receiving apparatus according to claim 1, wherein a switching transistor is provided in parallel with the limiting resistor, and the switching transistor is on-controlled by the second switching transistor. Machine. 3. The television receiver according to claim 1, wherein the power supplied to the BS tuner is a standby power supply circuit.