JPH0681260B2 - Deflection device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a deflection device such as a television receiver, and particularly to a fire caused by a rare short circuit of a high voltage coil (secondary coil) of a flyback transformer. The present invention relates to a deflection device provided with prevention means such as the above and means for preventing emission of X-rays from a cathode ray tube.

[Conventional technology]

FIG. 3 shows a general drive circuit of a deflection device used in a television receiver or a general CRT display device.

This drive circuit is based on a horizontal oscillation circuit 1 that generates a horizontal oscillation frequency, a horizontal drive circuit 2 that amplifies a signal from the horizontal oscillation circuit 1 and performs waveform shaping, and an output from the horizontal drive circuit 2. A horizontal output circuit 3 that generates a flyback pulse and applies a sawtooth wave current to a horizontal deflection coil, and a flyback that boosts the flyback pulse generated in the horizontal output circuit 3 and adds the boosted output to the cathode of a cathode ray tube. Transformer 4
The protection circuit 6 has a built-in comparison circuit 5. The flyback transformer 4 has a low voltage coil 7, a high voltage coil 8 and a detection coil 10 for extracting a detection voltage of a flyback pulse. The comparison circuit 5 compares a reference voltage supplied from a reference power source (not shown) through the terminal 11 with a detection voltage of the flyback pulse detected by the detection coil 10. The protection circuit 6 stops the operation of the horizontal oscillation circuit 1 when the detected voltage exceeds the reference voltage.

As is well known, when the flyback pulse voltage becomes abnormally large, X-rays are emitted from the cathode ray tube, which adversely affects the human body. In order to prevent such an adverse effect, the protection circuit 6 stops the circuit operation when the pulse voltage of the flyback pulse exceeds the reference voltage and prevents the X-ray emission from the CRT.

[Problems to be Solved by the Invention]

In recent years, in the horizontal deflection circuit, when a rare short circuit of the high voltage coil 8 occurs in the flyback transformer, a protection circuit has been provided for preventing smoke and ignition due to the rare short circuit.

However, in the case of providing a protection circuit for preventing smoke and ignition due to such a rare short circuit, it is general to provide the protection circuit separately from the X-ray radiation prevention circuit, which would complicate the circuit configuration. There's a problem.

The present invention has been made to solve the above conventional problems, and an object thereof is to simplify a circuit configuration by partially using an X-ray radiation prevention circuit as a smoke / ignition prevention circuit due to a rare short circuit. X-ray from the cathode ray tube due to smoke / ignition due to rare shorts and increase in flyback pulse.
It is an object of the present invention to provide a deflecting device that can prevent line radiation.

[Means for Solving the Problems]

The present invention is configured as follows to achieve the above object. That is, the present invention provides a horizontal deflection output circuit that receives an output signal from a horizontal drive circuit and generates a flyback pulse; the flyback pulse from this horizontal deflection output circuit is boosted, and the boosted output is output to the anode side of a cathode ray tube. A flyback transformer for adding; a protective fuse directly or indirectly connected to a low voltage coil of the flyback transformer; a primary side current detection for detecting a current flowing in the low voltage coil of the flyback transformer. A circuit; a voltage to the low voltage coil of the flyback transformer that opens the gate to flow a fusing current to blow the protection fuse when the current capacity detected by the primary side current detection circuit becomes larger than a reference capacity. Gate circuit to prevent application; pulse voltage of flyback transformer exceeds reference value It is configured as characterized by having; Te and voltage regulation circuit of the flyback pulse for fusing the protection fuse open gate of the gate circuit when the increased.

In the present invention configured as described above, when a rare short circuit occurs in the high voltage coil of the flyback transformer, the current flowing through the low voltage coil increases, and as a result, it is detected by the primary side current detection circuit. Since the current capacity becomes larger than the reference capacity, the gate of the gate circuit is opened. When the gate is opened in this way, a fusing current flows into the protective fuse, and the protective fuse is blown to stop the operation of the flyback transformer.

On the other hand, when the pulse voltage of the flyback pulse generated in the horizontal deflection output circuit exceeds the reference value and becomes large,
As a result of the gate of the gate circuit being opened by the voltage regulation circuit, similarly, a fusing current flows through the protective fuse, and the circuit operation is stopped due to the fusing of the protective fuse.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In the description of the present embodiment, the same circuit parts as those in the conventional example are designated by the same reference numerals, and the duplicate description thereof will be omitted.

FIG. 1 shows a circuit configuration of a deflection device showing an embodiment of the present invention. In the figure, the deflecting device includes a horizontal oscillation circuit (not shown), a horizontal drive circuit (not shown), a horizontal output circuit 3, a high voltage circuit 9, and a rare short protection circuit.
12 and an X-ray radiation prevention circuit 13. Of these, the circuits other than the rare short protection circuit 12 and the X-ray radiation prevention circuit 13 are known, and therefore the description of these known circuits will be simplified.

The horizontal output circuit 3 includes a horizontal output transistor 14, a damper diode 15, a resonance capacitor 16, and a horizontal deflection coil.
The horizontal deflection coil 17 is provided with a sawtooth wave current and a flyback pulse is generated, which is applied to the high voltage circuit 9.

The high voltage circuit 9 is composed of a flyback transformer 4 and a high voltage rectifying diode 20, the flyback pulse applied from the horizontal output circuit 3 is boosted by the flyback transformer 4, and the high voltage rectifying diode 20 performs signal rectification. The rectified output is applied to the anode 22 of the cathode ray tube 21.

Rare short protection circuit 12 is the flyback transformer 4
The first characteristic circuit of this embodiment is for surely detecting an abnormality such as a rare short circuit occurring in the high voltage coil 8 of FIG. The rare short protection circuit 12 includes a primary side current detection circuit 19, a secondary side current detection circuit 23, a gate circuit 24, a protection fuse 25, and a bias power supply 30.

Said primary-side current detection circuit 19, the first consists of the detection resistor 26, one end side protection fuse of the first detection resistor 26 for detecting by converting the DC component of the primary side of the current I _B to voltage twenty five
Is connected to the low voltage side (winding start side) of the low voltage coil 7, and the other end of the resistor 26 is connected to the positive side of the input power supply 27. The negative side of the input power source 27 is connected to the reference potential side (ground side in the figure).

The secondary side current detection circuit 23 comprises a second detection resistor 28 for detecting the high voltage current I _H flowing through the high voltage coil 8. One end of the second detection resistor 28 is connected to a common connection portion between the first detection resistor 26 and the positive side of the input power source 30 via a bias power supply 30, and the second detection resistor 28 has a common connection portion. The other end is a resistor
It is connected to the low voltage side (winding start side) of the high voltage coil 8 via 31. The low voltage side of the high voltage coil 8 is ABL (Aut
Omatic Brightness Limiter).

Further, in the present embodiment, the gate circuit 24 is configured by the thyristor 32. The cathode side of the thyristor 32 is connected to the common connection portion of the protection fuse 25 and the first detection resistor 26, and the gate side of the thyristor 32 is the other end of the second detection resistor 28. Side, that is, resistor
It is connected to the common connection between 28 and 31. A smoothing capacitor 33 that removes an AC component and blocks noise is connected between the cathode and the gate of the thyristor 32.

On the other hand, the anode side of the thyristor 32 is connected to the cathode side of the diode 34. The anode side of the diode 34 is connected to the intermediate tap 35 provided on the low voltage coil 7.

On the other hand, the second characteristic X-ray radiation prevention circuit 13 of this embodiment is a voltage regulation circuit 29, a gate circuit 24, and a smoothing capacitor 33.
Among them, the flyback pulse voltage regulation circuit 29 includes the diode 34, the dividing resistors 36 and 37, and the Zener diode 38. The dividing resistors 36 and 37 are connected in series, one end side of the series connection body is connected to a common connection portion of the anode of the thyristor 32 and the cathode of the diode 34, and the other end side of the series connection body is a bias power supply. It is connected to the common connection between 30 and the first sense resistor 26. Further, the cathode side of the Zener diode 38 is connected to the series connection portion of the dividing resistors 36 and 37, and the anode side of the Zener diode 38 is connected to the thyristor 32.
Connected to the gate side of.

In the present embodiment configured as described above, as the brightness of the cathode ray tube 21 is increased while the circuit is being driven, the high voltage output current I _H applied to the anode 22 of the cathode ray tube 21 increases. On the other hand, if this high-voltage output current I _H increases, the input power supply 27
The current I _B flowing from the low voltage coil 7 to the low voltage coil 7 also increases. This current
I _B includes an AC component and a DC component, and the relationship between the DC component current I _BDC and the high-voltage output current I _H is shown in FIG.

Current I _BDC is According to this figure, a constant DC component I _BDCO, changes direct current component i _B increases in proportion to the increase of the high voltage output current I _H
When I _H changes from 0 to the maximum value I _{HM of the} operating range, I _BDC changes by _{ΔI BDC} . Although the actual current of this I _BDC includes a large sawtooth wave component, in FIG. 2, I _BDC is represented by the average current value. In this embodiment, the change in I _B is used to operate the rare short protection circuit 12 to stop the circuit operation before smoking or ignition which may occur due to the rare short of the high voltage coil 8 is important. To prevent it.

In this embodiment, the current I _BDC of the DC component of the current I _B flowing through the low voltage coil 7 is detected by the first detection resistor 26 as the primary side current detection circuit as follows. That is, the noise component and the AC component current of I _B are removed and smoothed by the smoothing capacitor 33, and the product of the DC component current I _BDC and the resistance value R _{1 of} the first detection resistor 26, that is, e _B = R A voltage of ₁ × I _BDC (a voltage at which the input power supply 27 side becomes positive) appears across the resistor 26. This means that the current capacity I of the DC component on the primary side is
_It means that the _BDC is indirectly converted into the voltage value e _B and detected. The detected value e _B is applied to the cathode side of the thyristor 32.

On the other hand, the high voltage current I _H flowing through the high voltage coil 8 is detected by the second detection resistor 28 as a secondary side current detection circuit as follows. That is, when the high voltage current I _{H from} which the AC component and the noise component have been removed by the smoothing capacitor 33 flows through the second detection resistor 28 to the high voltage coil 8, the resistance value of the second detection resistor 28 is changed to R If it is ₂ , then e _H =
A DC voltage without ripple of I _H × R ₂ appears. This means that the high voltage current I _H is indirectly converted into the voltage e _H and detected, and this detection value e _H is applied to the gate of the thyristor 32.

In this embodiment, in order to balance the detection current capacities of both detection circuits 19 and 20, the secondary side current detection circuit 23 has a bias power supply 30
Are connected.

That is, the negative DC component I _BDC flowing through the low-voltage coil 7 is the sum of the constant component I _BDCO and the changing component i _{B as} described above, and the bias power source 3 is used to balance the constant component I _BDCO.
The negative voltage corresponding to the I _BDCO from 0 is applied to the second sense resistor 28
In addition to. As a result, the equilibrium relationship between e _B and e _H is that the direct-current change component i _B flowing through the low-voltage coil 7 and the high-voltage coil 8
It will be replaced by the relationship with the voltage and current I _H that flows. In the present embodiment, this e _H functions as a reference capacity when converting the current capacity I _BDC detected by the primary side current detection circuit 19 into a voltage value for comparison.

The thyristor 32 maintains the off state when the high voltage coil 8 does not have a rare short circuit normally, that is, when e _H ≧ e _B. On the other hand, when a rare short circuit occurs in the high voltage coil 8,
A large amount of power is lost in this rare short section. If this loss power is P, the primary-side current i _B increases by P / E _B (where E _B is the voltage of the input power supply 27). In general, the DC power source component I _BDC flowing through the low-voltage coil 7 becomes nearly double that in the normal state, resulting in a state of e _H <e _B. When e _H <e _B , the thyristor 32 opens the gate and is turned on, and a large fusing current is passed through the protective fuse 25 to blow the fuse 25. Thus, in the circuit of the present embodiment, the detection resistors 26, 2
The operating point of the thyristor 32 is determined by how to determine the resistance values R ₁ and R _{2 of 8} and the voltage E _S of the bias power supply 30.

The determination process of R ₁ , R ₂ , and E _S can be shown by a mathematical formula as follows.

First, the direct-current component I _BDC flowing through the low-voltage coil 7 is represented by I _BDC = Al _H + I _BDCO (1) (where A is a constant).

Further, e _H and e _B are also expressed as follows.

−e _H = I _H × R ₂ + E _S (2) −e _B = I _BDC × R ₁ (3) Substituting equation (1) into equation (3), −e _B = A × I because definitive and e _B = e _H in _{H × R 1 + I BDCO ×} R 1 normal _{operation, I H × R 2 + E} S = a × I H × R 1 + I BDCO × R 1 Accordingly, I _H × R ₂ = A × I _H × R ₁ ∴R ₂ = A × R ₁ E _S = I _BDCO × R ₁ That is, R ₁ , R ₂ , and E _S are circuit constants to be determined. Now, E _S
If R ₁ and R ₂ are determined _first , R ₁ and R ₂ are _{calculated as} R ₁ = E _S / I _BDCO and R ₂ = A × E _S / I _BDCO .

In this case, if the value of E _S is appropriately increased with a margin in consideration of circuit variations and the like, the thyristor 32 is always kept in the off state during normal operation and the gate is not opened.

On the other hand, when an abnormality such as a rare short circuit occurs in the high voltage coil 8 of the flyback transformer 4, as described above,
The DC component I _BDC of the current flowing through the low voltage coil 7 increases rapidly.
As a result, e _B > e _H , and the thyristor 32 is turned on sufficiently before the ignition, and the gate is opened. Since the protective fuse 25 is immediately cut off by opening the gate, the operation of the flyback transformer 4 is stopped, and a fire or the like due to a rare short circuit of the flyback transformer 4 is prevented from occurring.

Generally, in case of circuit protection, such as AC transformer,
The temperature fuse connected in series to the low-voltage coil is directly wound in the transformer, and the temperature fuse is blown by the rise of the internal temperature at the time of abnormality, and the operation of the transformer is stopped. However, in the flyback transformer, a high voltage of 10 KV to 30 KV is applied between the low voltage coil 7 and the high voltage coil 8, and it is not possible to arrange a temperature fuse in this flyback transformer in the same manner as the AC transformer. There is a problem in insulation processing. Further, the flyback transformer is very high and the driving frequency is 15.75KH _Z ~130KH _Z, must increase the degree of coupling between the low pressure coil 7 and the high voltage coil 8, the ones shaped like a thermal fuse large both The interposition between the coils 7 and 8 lowers the degree of coupling, which impairs the basic performance of the flyback transformer. In this respect,
According to the configuration of the present embodiment, the problem of insulation treatment of the flyback transformer and the deterioration of the basic performance can be solved, and the object can be achieved without directly adversely affecting the manufacture and performance of the flyback transformer.

Next, the operation of the X-ray radiation prevention circuit 13 in this embodiment will be described.

As is well known, when the oscillation frequency of the horizontal oscillation circuit is lowered or the connection of the resonance capacitor 16 of the horizontal output circuit 3 is broken, the pulse voltage of the flyback pulse exceeds the standard value (reference value). growing. When the flyback pulse voltage becomes abnormally large, X-rays are emitted from the cathode ray tube 21 and this has a problem of adversely affecting the human body. The X-ray radiation prevention circuit 13 is intended to effectively solve such a problem.

That is, when the pulse voltage of the flyback pulse exceeds the reference value and increases, the pulse voltage generated between the low voltage side terminal 40 of the low voltage coil 7 and the intermediate tap 35 also increases in proportion thereto. The pulse voltage generated at the terminal 40 and the intermediate tap 35 is applied to the Zener diode 38 via the diode 34, and is further resistance-divided by the dividing resistors 36 and 37. At this time, if the pulse voltage of the flyback pulse is smaller than the reference value, the Zener diode 38
Since it is smaller than the Zener voltage of, the operation signal for turning on the thyristor 32 is not applied to the gate side of the thyristor 32. On the other hand, when the pulse voltage of the flyback pulse exceeds the reference value and becomes large, the Zener diode 38 receives the reference voltage, that is, the pulse voltage exceeding the Zener voltage of the Zener diode 38 is added. The Zener diode 38 becomes conductive, the operating current is supplied to the thyristor 32 from the Zener diode 38 side, the thyristor 32 is turned on, and the fusing current is applied to the protective fuse 25. As a result of the protection fuse 25 being blown by this blowing current, the operation of the flyback transformer 4 is stopped.

As described above, in the present embodiment, when a rare short circuit occurs in the high voltage coil 8 of the flyback transformer 4, the thyristor 32 is turned on to melt the protective fuse 25, and the high voltage coil 8 rarely shorts. In normal operation, if the pulse voltage of the flyback pulse exceeds the standard value and becomes large, the Zener diode
The thyristor 32 is turned on by the conduction of 38, and the protection fuse 25 is blown in the same manner, and the operation of the flyback transformer 4 is stopped. That is, in the present embodiment, the thyristor 32 constitutes a part of the rare short protection circuit 12 and a part of the voltage regulation circuit. As described above, in the present embodiment, since the main constituent part of the circuit of the rare short protection circuit 12 also serves as the main constituent part of the X-ray radiation prevention circuit 13, the circuit structure is achieved despite performing the multifunctional operation. Has been greatly simplified.

Further, as shown in FIG. 1, a rare short protection circuit and an X-ray radiation prevention circuit for detecting a rare short and ensuring its safety are compactly formed in the transformer unit.
The intended purpose can be achieved without introducing any operation signal from outside the unit. Therefore, it is not necessary to increase the number of terminals of the transformer unit, and the above object can be achieved only by adding a circuit in the conventional transformer unit, which facilitates the manufacturing and assembling of the device and is extremely convenient to handle. Becomes

Although the high voltage circuit and the horizontal output circuit are not separated in the above embodiment, the horizontal deflection coil 17 and the S-correction capacitor 18 are not necessary when separating them.
However, also in this case, a dummy inductance can be used instead of the horizontal deflection coil 17.

Further, the present invention is not limited to the circuit configuration shown in FIG. 1, and various circuit modifications are possible. For example, in the above embodiment, the bias power supply 30 is provided on the secondary side current detection circuit 23 side, and a constant DC component of the current flowing through the low voltage coil 7
Although it is balanced with I _BDCO , unlike this, a bias power supply that adds a positive current voltage is used for the primary side current detection circuit.
19 may be provided to cancel the negative DC current component I _BDCO .

Further, in the circuit of FIG. 1, the high voltage coil 8 is not divided and wound, but it may be divided into plural windings to form a multi-single type. In this case, the diode is connected in series between the coils that are divided and wound.

Further, in the circuit of FIG. 1, the second detection resistor 28, the bias power supply 30, and the resistor 31 may be omitted. As described above, when the second detection resistor 28 and the bias power source 30 are omitted, only the abnormality of the primary side current I _B is detected by the first detection resistor.
It will be detected by 26 and the thyristor 32 will be operated.

Further, in this embodiment, the thyristor 32 is used as a gate circuit.
However, this may be configured by another circuit element such as a transistor.

〔The invention's effect〕

Since the present invention is configured as described above,
An abnormality due to a rare short-circuit of the flyback transformer can be detected quickly and surely, and safety measures can be taken, so that a disaster such as a fire caused by the abnormality of the flyback transformer can be prevented. Further, since it is not necessary to dispose the temperature fuse in the flyback transformer for detecting the abnormality, the basic performance of the flyback transformer is not impaired.

Further, according to the present invention, when the pulse voltage of the flyback pulse exceeds the standard value and becomes large, the gate of the gate circuit is similarly opened to blow the protective fuse by the operation of the voltage regulation circuit of the flyback pulse. Since the operation of the flyback transformer is stopped, X-rays are not emitted from the cathode ray tube due to abnormal voltage of the flyback pulse and do not harm the human body, and it is possible to provide a safe device for health. Becomes

Further, in the present invention, a main circuit portion, for example, a gate circuit, is used as a circuit for preventing ignition or the like caused by a rare short circuit and a circuit for preventing radiation emission due to an abnormal voltage of a flyback pulse. Despite having the function of preventing rare shorts and the function of preventing radiation of X-rays, the circuit configuration is extremely simplified, which makes it possible to facilitate device manufacturing and reduce device cost. Becomes

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a deflection device according to the present invention, and FIG. 2 is a characteristic diagram showing a relationship between a current I _{BDC of a} DC component flowing in a low voltage coil and a high voltage current I _H flowing in a high voltage coil,
FIG. 3 is a circuit diagram showing a basic circuit of a conventional general deflection apparatus provided with an X-ray radiation preventing means caused by an abnormal pulse voltage. 1 ... Horizontal oscillation circuit, 2 ... Horizontal drive circuit, 3 ...
Horizontal output circuit, 4 ... Flyback transformer, 5 ... Comparison circuit, 6 ... Protection circuit, 7 ... Low-voltage coil, 8 ... High-voltage coil, 9 ... High-voltage circuit, 10 ... Detection coil, 11 ...
Terminals, 12 …… Rare short protection circuit, 13 …… X-ray radiation prevention circuit, 14 …… Horizontal output transistor, 15 …… Damper diode, 16 …… Resonance capacitor, 17 …… Horizontal deflection coil, 18 …… S-shape Correction capacitor, 19 ... Primary side current detection circuit, 20 ... High voltage rectifier diode, 21 ... CRT,
22 …… Anode, 23 …… Secondary side current detection circuit, 24 …… Gate circuit, 25 …… Protective fuse, 26 …… First detection resistor, 27 …… Input power supply, 28 …… Second detection Resistor, 29 ……
Voltage regulation circuit, 30 ... Bias power supply, 31 ... Resistor, 32
...... Thyristor, 33 …… Smoothing capacitor, 34 …… Diode, 35 …… Middle tap, 36,37 …… Split resistor, 38 ……
… Zener diode, 40 …… Low voltage side terminal.

Claims (1)

[Claims] 1. An output signal from a horizontal drive circuit is received,
A horizontal deflection output circuit for generating a flyback pulse;
A flyback transformer that boosts the flyback pulse from the horizontal deflection output circuit and applies the boosted output to the anode side of the cathode ray tube; and a deflection device that is directly or indirectly connected to a low-voltage coil of the flyback transformer. A protection fuse; a primary side current detection circuit for detecting a current flowing in the low voltage coil of the flyback transformer; and a gate opened when a current capacity detected by the primary side current detection circuit becomes larger than a reference capacity. A gate circuit that blows a fusing current to blow the protective fuse to prevent voltage application to the low voltage coil of the flyback transformer; and the gate circuit when the pulse voltage of the flyback transformer exceeds a reference value. Voltage control circuit of flyback pulse that opens the gate of the fuse to blow out the protective fuse ; Deflection device, characterized in that it has a.