JPH01126079A - Deflector - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a fire and the like by comparing current flowing to the low tension coil of a flyback transformer and current flowing to the high tension coil of the flyback transformer and quickly and surely detecting the abnormality of the flyback transformer. CONSTITUTION:When the abnormality such as rare short occures to the flyback transformer 8, the current flowing to the low tension coil 12 is rapidly increased. As the result of that, current capacity detected by the current detection circuit 22 of a primary side is increased over the reference capacity of current deteced by the current detection circuit 23 of a secondary side and the gate of a gate circuit 24 is opened. By opening this gate, the big capacity of fusing current flows to a protection circuit 25 and a protecting fuse 35 is fused and voltage impression for the low tension coil 12 is obstructed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a deflection device for a television receiver, etc., and particularly to fires caused by a short circuit in a high-voltage coil (secondary coil) of a flyback transformer. This invention relates to a deflection device equipped with prevention means such as the above.

[Conventional technology]

FIG. 3 shows a general basic circuit of a deflection device used in television receivers and general CRT display devices.

This basic circuit has a horizontal deflection output circuit 1 and a high voltage circuit 2. The horizontal deflection output circuit 1 includes a horizontal output transistor 3, a damper diode 4, a resonant capacitor 5, a horizontal deflection coil 6, and a three-figure correction capacitor 7. The horizontal output transistor 3 performs a switching action in response to a voltage pulse sent from a horizontal drive circuit (not shown), and applies a sawtooth wave current to the horizontal deflection coil 6 in cooperation with the damper diode 4. On the other hand, the resonant capacitor 5 and the horizontal deflection coil 6 generate flyback pulses by their resonance action,
This is added to the high voltage circuit 2.

The high voltage circuit 2 includes a flyback transformer 8 and a high voltage rectifier diode 10. One terminal of the low voltage coil (minus coil) 12 of the flyback transformer 8 is connected to the cathode of the damper diode 4, the common terminal of the horizontal deflection coil 6 and the resonant capacitor 5, and the other end of the low voltage coil 12 The side terminal is connected to the input power source 13. On the other hand, the high voltage side terminal of the high voltage coil (secondary coil) 14 of the fly pack unit 8 is connected to the high voltage rectifier diode 1.
In such a configuration, the high voltage circuit 2 boosts the flyback pulse applied from the horizontal deflection output circuit 1 by the flyback transformer 8, and further boosts the flyback pulse applied from the horizontal deflection output circuit 1 by the high voltage rectifier diode lO. Performs signal rectification and outputs the rectified output E,
is added to the anode 16.

[Problems to be solved by the invention] When a deflection device having the basic circuit described in E is operated, if a mistake occurs in design or manufacturing, abnormalities such as a rare short circuit will occur in the high voltage coil 14 of the flyback transformer 8. This may cause disasters such as fire. Possible mistakes during the design include abnormal heat generation in the core 11 of the flyback transformer 8 and the high-voltage coil 14, or poor withstand voltage between the coils 12 and 14 or between the laminated coils. In addition, as a manufacturing error, it is possible that a layer short circuit occurs due to a mistake during the winding work of the coil 12.14, or an internal discharge occurs due to a mistake in the insulation treatment of the coil 12.14.

Although the design and manufacturing of the deflection device is controlled to prevent the above-mentioned mistakes from occurring, it is difficult to completely eliminate such mistakes even if sufficient care is taken. Therefore, for example, the low voltage coil 1 is placed inside the flybank transformer 8.
2 or a temperature fuse connected in series to the human power source 13, and when the flyback transformer generates abnormal heat due to the above-mentioned mistake, the abnormally high temperature heat is used to blow out the fuse, and the flyback transformer It is conceivable to prevent the above-mentioned disaster from occurring by blocking the application of voltage to 8.

However, when arranging the above-mentioned temperature fuse, there is an extremely large potential difference between the temperature fuse and the high voltage coil 14, so if the temperature fuse is placed close to the coil 14, there is a problem that discharge will occur between the two. However, insulation treatment to avoid such discharge is extremely difficult.

Also, in order to prevent the discharge, it is possible to separate the temperature fuse from the high voltage coil 14, but in that case,
The abnormal heat generated by the short circuit in the high-voltage coil 14 is not even transmitted to the temperature fuse, resulting in a delay in safe operation (fuse blowing operation) and the inconvenience of not being able to prevent fires and the like. Furthermore, since the drive frequency of the flyback transformer 8 is generally as high as 15.75KH2 to 130KH, it is necessary to increase the degree of electromagnetic coupling between the low voltage coil 12 and the high voltage coil 14. If a large-sized coil such as the one shown in FIG.

The present invention has been made in order to solve the above-mentioned conventional problems, and its purpose is to provide a means for quickly and reliably detecting abnormalities such as rare shorts in flyback transformers and preventing disasters from occurring. The object of the present invention is to provide a deflection device which takes such measures and which has almost no adverse effect on the basic performance of a flyback transformer.

[Means for solving problems]

In order to achieve the above object, the present invention is configured as follows. That is, the present invention includes a horizontal deflection output circuit that receives an output signal from a horizontal drive circuit and generates a flyback pulse; boosts the flyback pulse from this horizontal deflection output circuit and connects its output horn to the anode side of the cathode ray tube. a flyback transformer added to the deflection device; a protective fuse connected to the low voltage side of the low voltage coil of the flyback transformer; a primary current detection circuit that detects a current flowing through the low voltage coil of the flyback transformer; a secondary current detection circuit that detects a high voltage current flowing through the high voltage coil of the flybank transformer;
a gate circuit that opens a gate when the current capacity detected by the primary side current detection circuit becomes larger than a current reference capacity detected by the secondary side current detection circuit;
A closed circuit including a series connection of the low-voltage coil, a protective fuse, and a gate circuit, and a protective circuit through which a fuse blowing current flows when the gate circuit is open. .

[Effect]

In the present invention configured as described above, under normal conditions when no abnormality occurs in the flyback transformer,
The current capacity detected by the primary current detection circuit is less than the reference capacity of the current detected by the secondary current detection circuit, so the gate of the gate circuit is closed and the protection fuse of the protection circuit is supplied with the blown current. flows. Never.

On the other hand, when an abnormality such as a layer short circuit occurs in the flyback transformer, the current flowing through the low voltage coil increases rapidly. As a result, the current capacity detected by the primary current detection circuit becomes larger than the reference current capacity detected by the secondary current detection circuit, and the gate of the gate circuit is opened. When the gate is released, a large-capacity blowing current (pulse current) flows through the protection circuit, and the protection fuse is blown. By blowing the fuse, voltage application to the low-voltage coil is blocked, so the operation of the flyback transformer is stopped, and the occurrence of a fire or the like due to abnormal heat generation of the flyback transformer is prevented.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings. In the description of this embodiment, the same reference numerals are given to circuit parts that are the same as those of the conventional example, and redundant explanation thereof will be omitted.

FIG. 1 shows a circuit configuration of a deflection device showing one embodiment of the present invention. In the figure, the deflection device includes a horizontal oscillation circuit (not shown), a horizontal drive circuit 17, a horizontal deflection output circuit 1, a high voltage circuit 2, and an abnormality detection/safety circuit 18. Among these circuits, the circuits other than the abnormality detection/safety circuit 18 are known, so the description of these known circuits will be simplified.

The horizontal drive circuit 17 includes a drive transistor 2
0 and a drive transformer 21, which amplifies the horizontal pulse sent from the horizontal oscillation circuit and applies the waveform-shaped voltage pulse to the horizontal deflection output circuit l.

The horizontal deflection output circuit 1 is constructed in the same manner as in the case of FIG.
Add to.

The high voltage circuit 2 consists of a flyback transformer 8 and a high voltage rectifier diode 10, and as in the case of FIG. Signal rectification is performed by diode 10 and the rectified output is applied to anode 16.

The abnormality detection/safety circuit 18 is the flyback transformer 8
This circuit reliably detects abnormalities such as layer shorts occurring in the high-voltage coil 14, and is a characteristic circuit of this embodiment.

This abnormality detection/safety circuit 18 includes the primary current detection circuit 2
2, a secondary current detection circuit 23, a gate circuit 24,
It consists of a protection circuit 25.

The primary current detection circuit 22 includes an AC bus capacitor 29 that removes an AC component of the current I flowing through the low-voltage coil 12, and a first detection resistor that detects the DC component of the current 1++ from which the AC component has been removed. One end of the parallel circuit 22 is connected to the positive side of the input power supply 13, and the other end of the parallel circuit 22 is connected to the protection circuit 25. Note that the negative side of the input power source 13 is connected to the ground side.

The secondary current detection circuit 23 includes a second detection resistor 27 that detects the high voltage current IN flowing through the high voltage coil 14, a bias power supply 28, and an AC bus capacitor 30 that removes the 1.0 AC component of the high voltage current. , and resistors 31 and 32, one end of the second detection resistor 27 is connected to one end of each of the resistors 31 and 32, and the other end of the second detection resistor 27 is connected to a bias power supply. Connected to the negative side of 2B. The positive side of the power source 28 is connected to one end of the primary current detection circuit 22, that is, the positive side of the input power source 13. The other end of the resistor 31 is branched into two, to which one end of the AC bus capacitor 30 is connected, and the other end of the capacitor 30 is connected to a reference potential (earth side in the figure). . And the resistor 3
The other branch side of the coil 1 is completely connected to the low voltage side (winding start side) of the high voltage coil 14. Note that the connection part between this resistor 31 and the high voltage coil 14 is ABL (Automatic
c Br1tenness Lim1tter) side.

On the other hand, in this embodiment, the gate circuit 24 is composed of a thyristor 33 and a capacitor 34 for noise removal, and the cathode side of the thyristor 33 is connected to the output terminal of the primary current detection circuit 22, that is, the AC bus capacitor 2
9 and one end of the first detection resistor 26 . . Further, the gate side of the thyristor 33 is the output terminal of the secondary current detection circuit 23, that is, the resistor 3
2 is connected to the other end side. Further, a capacitor 34 is connected between the cathode and gate of the thyristor 33.

The protection circuit 25 includes the low voltage coil 12, a protection fuse 35, a diode 36, a smoothing capacitor 37,
and the thyristor 33. The cathode of the thyristor 33, one end of the smoothing capacitor 37, and one end of the protective fuse 35 are commonly connected to one end of the primary current detection circuit 22, and the other end of the protective fuse 35 is connected to one end of the low voltage coil 12. side (low pressure side). An intermediate tap is provided at an appropriate position of this low voltage coil 12, and the anode side of a diode 36 is connected to this intermediate tap, and the cathode side of the diode 36 is connected to the anode side of the lister 33, A closed circuit is formed by being connected to the common connection part with the end side.

In addition, 38 in FIG. 1 indicates a transformer unit, and P1 to
P indicates a terminal of the transformer unit 38.

In this embodiment configured as described above, when the brightness of the cathode ray tube 15 is increased while the circuit is being driven, the high voltage output current [H
increases. On the other hand, if this high voltage output current IN increases, the current 6 flowing from the input power source 13 to the low voltage coil 12 also increases. This current I8 includes an AC component and a DC component, and the relationship between the DC component current 111Dc and the high voltage output current I is shown in FIG. According to this figure, the current +11Dc has a constant direct component t soc. , the changing DC component i increases in proportion to the increase in the high voltage output current IH.
, is added, and 1. When changes from O to the maximum value I of the operating range, rIIDC becomes △1.
Only D changes. The actual current at I8° includes a large sawtooth wave component, but in FIG. 2, the average current value represents IIIDC.

As described above, when the brightness of the cathode ray tube 15 changes, the current In flows through the low voltage coil 12 and the high voltage current IN flows through the high voltage coil 14. The DC component of the current (2) flowing through the low-voltage coil 12 is 18°. is detected by the primary side current detection circuit 22 as follows. That is,
The AC component current of Il+ is removed by the AC bus capacitor 29, and as a result, a completely smoothed DC voltage appears at both ends of the capacitor 29, and is proportional to ■llD. Become). In other words, the DC component current ■.

. and the resistance value R6 of the first detection resistor 26, that is, a voltage of eH=R+XIaoc appears, and the current capacity 1Isoc of the DC component is indirectly converted to a voltage value e and detected. This detected value eB is then applied to the cathode of the thyristor 33.

On the other hand, the high voltage current In flowing through the high voltage coil 14 is detected by the secondary current detection circuit 23 as follows. Of course, when the high voltage current flows through the secondary current detection circuit 23, its AC component is removed by the AC bus capacitor 30, and if the resistance value of the second detection resistor 27 is R2, then the A ripple-free DC voltage of e, □=[HXRZ appears in the resistor 27. This means that the high voltage current 111 is indirectly converted into a voltage eR2 and detected, and this detected value eRfl is applied to the gate of the thyristor 33 through the resistor 32.

In this embodiment, a bias power supply 28 is connected to the secondary current detection circuit 23 in order to balance the detection current capacities of the rain detection circuits 22 and 23.

In other words, the negative DC component flowing through the low voltage coil 12]8DC
As mentioned above, is the sum of the constant component 111DC0 and the variable component 18, and this constant component I. In order to balance with oo, a negative voltage corresponding to the r IDcO is applied from the bias power supply 28 to the second detection resistor 27. As a result, the equilibrium relationship between e and e□ is that the low voltage coil 12
This will be replaced by the relationship between the DC variation component i flowing through the high voltage coil 14 and the high voltage current (i) flowing through the high voltage coil 14.

The thyristor 33 has a voltage e on the gate side that is greater than the sum eH of the detected voltage value ellt and the voltage value E of the bias voltage #28.
The gate is opened when , becomes large, and the gate is closed when e, ≧e, that is, when the high voltage coil 14 is normal and there is no short circuit. Therefore, in the circuit of this embodiment, the resistance value R+ of the detection resistor 26.27,
The operating point of the thyristor 33 is determined depending on how Rz and the voltage E of the bias power supply 28 are determined.

The process of determining R, , R2Es can be expressed using the following formula.

First, a DC component I flows through the low voltage coil 12. 0 is I
woe = AI H+ I goco-・---
−−−−−−−−−−−−(1) (However, A is a constant)
It is expressed as

Moreover, eH+el is expressed as follows.

e o = Io X Rz + E! 1-・---
−・−−−−−−(2) e ll= I IDc X
R+ −−−−−−−−−−−−−−・−(3)(1
) into equation (3), we get ell""'AX IHxRl + IgocoXR+
In normal operation, it is set as eB-ell, so l l
lX Rz + Es =AX l u X R++
I BDCOX R+ Therefore, In XR2=Ax I, IxR.

,',RZ=AXR+ ES=IIDC0XR.

In other words, R,,R,,E are the circuit constants to be determined. Now, if E, is determined first, then R,,R, becomes R+ =
Es/Loco.

It is determined as Rz=AXEs/IIIDcO.

In this embodiment, E is taken into consideration, such as variations in the circuit.

If the value of is set to be appropriately large with a margin, the thyristor 33 will always maintain an off state during normal operation, and the gate will not be opened.

On the other hand, the high voltage coil 14 of the flyback transformer 8
If an abnormality such as a rare short occurs in the low voltage coil 12
When the change component ia of the current flowing through the transformer increases rapidly, especially in the case of an abnormality that causes the flyback transformer 8 to ignite, the increase in iB becomes nearly twice as much as ΔI IIDc in FIG. As a result, the detection voltage e corresponding to the current capacity detected by the primary current detection circuit 22 is the base i4! detected by the secondary current detection circuit 23! The thyristor 33 is turned on and the gate is opened at a time when the detection voltage ell becomes larger than the detection voltage ell corresponding to the current capacity and sufficiently before ignition occurs. When this gate is opened, a pulse current (fuse current) flows through the protection circuit 25, and the protection fuse 35 is immediately blown. By blowing out the protective fuse 35, the operation of the flyback transformer 8 is stopped, and the occurrence of a fire or the like caused by a short circuit in the flyback transformer 8 is prevented.

In the above embodiment, circuits for detecting a layer short circuit and ensuring its safety, that is, current detection circuits 22 and 23 on the primary side and secondary side, a gate circuit 24, and a protection circuit 25 are used.
These circuits are compactly formed within the transformer unit 38, and the desired purpose can be achieved without introducing any operating signals from outside the unit 38. Therefore, there is no need to increase the number of terminals of the transformer unit 38, and the above purpose can be achieved simply by adding a circuit inside the conventional transformer unit, making the device easy to manufacture and assemble, and extremely easy to handle. It becomes convenient.

In the above embodiment, a circuit configuration in which the high voltage circuit and the horizontal deflection output circuit are not separated is shown, but in the case where they are separated, the horizontal deflection coil 6 and the three-character correction capacitor 7 become unnecessary. However, even in this case, only the horizontal deflection coil 6 can be replaced with a dummy inductance.

Further, the present invention is not limited to the circuit configuration shown in FIG. 1, and various circuit changes are possible. For example, in the above embodiment, the bias power supply 28 is provided on the secondary side current detection circuit 23 side, The current flowing through the low voltage coil 12 is balanced with a constant DC component IBDCO, but unlike this, a bias power supply that adds a positive DC voltage is provided in the primary current detection circuit 23 to Current component I B
It is also possible to cancel the DCO.

Further, in the circuit shown in FIG. 1, the high-voltage coil (4) is not wound in parts, but it may be wound in multiple parts to form a multi-gingler type.

In this case, diodes are connected in series between each divided coil.

Furthermore, in this embodiment, the resistor 32 is connected to the gate side of the thyristor 33, but this resistor 32 may be omitted, and the gate of the thyristor 33 and the diode 3
The smoothing capacitor 37 connected between the capacitors 6 and 6 can also be omitted if necessary. Furthermore, in this embodiment, the thyristor 33 is used as a gate circuit, but this can be replaced by a transistor or the like.
It may also be constructed using other circuit elements.

Furthermore, in this embodiment, an intermediate tap is provided on the low voltage coil 12 and the anode of the diode 36 is connected thereto, but this intermediate tap is omitted and the anode of the diode 36 is connected to the high voltage side of the coil 12. You can. However, in this case, a high voltage is applied to the thyristor 33, which may cause problems in terms of the withstand voltage of the thyristor 33. Therefore, if an intermediate tap is provided and the diode 36 is connected,
Since the voltage applied to the thyristor 33 is reduced, no problem with withstand voltage occurs. If this intermediate tap is provided, its position will depend on the stone used for the thyristor 33.
It will be installed at a safe winding position in terms of voltage resistance.

〔Effect of the invention,〕

Since the present invention is configured as explained above,
It is possible to quickly and reliably detect an abnormality due to a rare short circuit or the like in a flyback transformer, and take safety measures, thereby preventing disasters such as fires caused by abnormalities in the flyback transformer.

In addition, it is not necessary to install a temperature heater inside the flyback transformer to detect the abnormality, so the basic performance of the flyback transformer is not impaired, and the circuit configuration is simple. It becomes possible to provide a deflection device that is excellent both technically and economically.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, and Fig. 2 shows the DC component current IBDC flowing through the low-voltage coil and the high-voltage current flowing through the high-voltage coil. , and FIG. 3 is a general basic circuit diagram of a deflection device. ■...Horizontal deflection output circuit, 2...High voltage circuit, 3...
・Horizontal output transistor, 4--damper diode, 5--resonant capacitor, 6--horizontal deflection coil,
7... 5-character correction capacitor, 8... Fly bank transformer, 10... High voltage rectifier diode, 11... Core, 12... Low voltage coil, 13... Input power supply, 14
...High voltage coil, 15...Cathode ray tube, 16...
Anode, 17... Horizontal drive circuit, 18... Abnormality detection/safety circuit, 20.0. drive transistor,
21... Drive transformer, 22... Primary side current detection circuit, 23... Secondary side current detection circuit, 24...
Gate circuit, 25... Protection circuit, 26... First detection resistor, 27... Second detection resistor, 28... Bias power supply, 29... AC lotus capacitor, 30...
・AC bus capacitor, 31.32...Resistor, 33
...Thyristor, 34...Capacitor, 35...
Protection fuse, 36...diode, 37...smoothing capacitor, 38...transformer unit. 'X 3/B

Claims (4)

[Claims] (1) A horizontal deflection output circuit that receives the output signal from the horizontal drive circuit and generates a flyback pulse; a flyback that boosts the flyback pulse from this horizontal deflection output circuit and applies the output power to the anode side of the cathode ray tube. a transformer; a protective fuse connected to the low voltage side of the low voltage coil of the flyback transformer; a primary side current detection circuit that detects a current flowing through the low voltage coil of the flyback transformer; a secondary current detection circuit that detects a high voltage current flowing in a high voltage coil of a transformer; a current capacity detected by the primary current detection circuit is larger than a reference capacity of the current detected by the secondary current detection circuit; a gate circuit that opens the gate when the low-voltage coil, the protective fuse, and the gate circuit are connected in series, and a protective circuit in which a fuse blowing current flows when the gate circuit is open; A deflection device characterized by: (2) The gate circuit is composed of a thyristor, and the protection circuit has the cathode side of the thyristor connected to one end of the protective fuse, the other end of the fuse connected to the low voltage side of the low voltage coil, and the intermediate tap position of the low voltage coil connected to the protective circuit. The anode of the diode is connected to the anode of the thyristor, and the cathode of the thyristor is connected to the output of the primary current detection circuit, and the gate of the thyristor is connected to the output of the primary current detection circuit. 2. The deflection device according to claim 1, wherein the deflection device is connected to each output terminal of the secondary current detection circuit. (3) The primary current detection circuit and the secondary current detection circuit include:
a capacitor that removes the alternating current component of the detected current, and
A resistor that converts the DC detected current value obtained by this capacitor into a voltage value is built in, and the voltage converted by the corresponding resistor of each current detection circuit is applied to the cathode side and gate side of the thyristor. 3. A deflection device according to claim 2, characterized in that: (4) A bias power supply for applying a bias current is connected to one side of the primary side current detection circuit and the secondary side current detection circuit. Deflection device according to any one of the above.