JPH03230685A - High voltage generating circuit - Google Patents

Abstract

PURPOSE:To execute stabilizing control of a high output voltage accurately by interposing a multiple voltage circuit amplifying a correction voltage and applying the amplified voltage to a high voltage terminal of the high voltage coil directly between a high voltage control means and a high voltage terminal of the high voltage coil being a component of a flyback transformer. CONSTITUTION:A high output voltage fed from a high voltage terminal of a flyback transformer 2 to an anode of a cathode ray tube is detected by a variable resistor 15 as a high voltage detection means and a high voltage control means 16 applies a correction voltage in response to the reduction of the detection voltage to a multiple voltage circuit 17 based on the result of detection. The multiple voltage circuit 17 amplifies the correction voltage fed from the high voltage control means 16 and applies the voltage to a high voltage terminal directly of the high voltage coil 11 being a component of the flyback transformer 2. Since the amplified correction voltage is fed to the high voltage terminal of the flyback transformer 2 from the multiple voltage circuit 17 to compensate the drop of the high output voltage. Thus, the high output voltage is made stable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high voltage generation circuit provided with means for stabilizing the high voltage output voltage applied to the anode of a cathode ray tube.

[Conventional technology]

As is well known, when high-voltage output current flows from the high-voltage side of a flyback transformer to a cathode ray tube, the high-voltage output voltage drops, deteriorating high-voltage regulation, and the problem is that the cathode ray tube cannot cope with larger screens and higher definition. occurs. In order to solve these problems, high voltage generation circuits equipped with means for improving high voltage regulation have recently come into use.

FIG. 8 and FIG. 9 show a high voltage generating circuit in which a measure for improving the regie laceration characteristic, that is, a means for stabilizing the high voltage output voltage is used. Generally, high voltage generation circuits are
It is equipped with a horizontal deflection output circuit I and a flyback transformer 2, and the horizontal deflection output circuit I receives a voltage pulse from a horizontal drive circuit (not shown) and sends a sawtooth wave horizontal deflection current to the horizontal deflection coil 3. On the one hand, a flyback pulse is generated and applied to the flyback transformer 2. The flyback transformer 2 boosts the flyback pulse and applies a high output voltage to the anode of the cathode ray tube.

The high voltage stabilizing means 4 shown in FIG. 8 detects the high voltage output voltage through a bleeder resistor 5, compares this detected voltage with a reference voltage provided by a power source 7 in a comparator 6,
When the detection voltage drops below the reference voltage, an operating voltage corresponding to the drop is applied to the base of the control transistor 8 to drive the transistor 8, and is applied to the collector side of the control transistor 8 from a separate correction voltage generating means. A correction voltage is applied to the low voltage side of the low voltage coil 10 of the flyback transformer 2 to stabilize the high voltage output voltage applied from the high voltage coil 11 of the flyback transformer 2 to the anode of the cathode ray tube.

Further, the high pressure stabilizing means 4 shown in FIG. 9 is constructed using a saturable reactor. That is, the bleeder resistor 5
The detected voltage of the high voltage output voltage detected through the coil of the saturable reactor 12 is compared by the comparator 6 as in the case of FIG. A current corresponding to the decrease in the detected voltage is supplied to 12a, the coil 12a side is saturated, and the inductance of the coil 12b side of the saturable reactor 12 is lowered. As a result, the pulse width of the collector pulse becomes narrower, and the peak value of the collector pulse becomes higher. As a result, the high voltage coil 11
The pulse voltage boosted on the side increases, and the high voltage output voltage is stabilized.

[Problem to be solved by the invention]

However, since the circuits shown in FIGS. 8 and 9 are both configured to control the current on the primary side of the flyback transformer 2, the control current flowing through the negative side becomes large and correction is required. The circuit that generates the current requires a high-power element and a large transformer, which increases the size of the device and increases the cost of the device.

In addition, as shown in FIGS. 8 and 9, the low voltage coil 1
When the horizontal deflection coil 3 is placed in parallel with zero, a correction current that changes in response to fluctuations in the high-voltage output voltage flows through this negative side, so voltage fluctuations and fluctuations in the pulse width of the flyback pulse are caused by fluctuations in the primary side. This causes a problem in that the amplitude of the deflection current changes, which adversely affects the screen amplitude of the cathode ray tube.

Furthermore, the correction voltage applied to the primary side in response to fluctuations in the high voltage output voltage needs to be smoothed to direct current.
In the circuit shown in Figures and Figure 9, the damper diode 13
Reverse current absorption capacitor 1
4 is used for absorption, but this type of capacitor 14
A capacitor with a large capacity is required for this, and as a result, the time constant for charging and discharging the reverse current absorbing capacitor 14 becomes large, resulting in a problem that the response speed of high voltage stabilization control becomes slow.

Furthermore, in a high voltage generation circuit using a flyback transformer, a tertiary winding is wound around the core of the flyback transformer, and from this tertiary winding, for example, the power supply voltage of the vertical deflection circuit or the power supply of other circuits is supplied. It is often done to take out the voltage or take out the flyback pulse as a signal such as the reference frequency of the AFC circuit, but as mentioned above, the method of adding a correction voltage to the primary side of the flyback transformer Since the voltage and pulse width of the back pulse change, it becomes impossible to extract the power supply voltage, AFC or BLK pulse signal from the tertiary winding. It is necessary to take measures such as providing it in parallel with the horizontal deflection output circuit 1, resulting in a problem that the circuit becomes complicated and the cost becomes high.

The present invention has been made to solve the above-mentioned conventional problems, and its purpose is to solve the various problems described above caused by applying a correction voltage to the primary side of a flyback transformer, and to improve the high-voltage output voltage. An object of the present invention is to provide a high voltage generation circuit that can accurately perform stabilization control.

[Means to solve the problem]

In order to achieve the above object, the present invention is configured as follows. That is, the high voltage generation circuit of the present invention includes a flyback transformer that boosts a flyback pulse and applies a high voltage output voltage to the anode of a cathode ray tube, a high voltage detection means for the suppressed output voltage, and a high voltage detected by the high voltage detection means. In a high voltage generation circuit having a high voltage control means for applying a correction voltage to the high voltage side of a flyback transformer in response to fluctuations in output voltage, the high voltage control means and a high voltage end of a high voltage coil constituting the flyback transformer are connected to each other. The structure is characterized in that a multiplier circuit is provided which amplifies the correction voltage and directly applies it to the high voltage end side of the high voltage coil.

[For production]

In the present invention, the high voltage output voltage applied from the high voltage side of the flyback transformer to the anode of the cathode ray tube is detected by the high voltage detection means. Based on the detection result of the high voltage detection means, the high voltage control means applies a correction voltage to the multiplier circuit in accordance with the decrease in the detected voltage. The multiplier circuit amplifies the correction voltage applied from the high voltage control means and directly applies it to the high voltage end of the high voltage coil constituting the flyback transformer. By applying an amplified correction voltage from this multiple voltage to the high voltage end of the flyback transformer, the drop in the high voltage output voltage is compensated for and the high voltage output voltage is stabilized.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a high voltage generation circuit according to the present invention will be described below with reference to the drawings. FIG. 1 shows a circuit diagram of an embodiment of a high voltage generating circuit according to the present invention. The circuit of this embodiment includes a flyback transformer 2 and a variable resistor 15 as a means for detecting a high voltage output voltage. The main components are a high voltage control means 16, and a multivoltage circuit 17. The flyback transformer 2 is formed by winding a low voltage coil IO and a high voltage coil 11 around a core I8, and the horizontal deflection output circuit 1 is connected to the low voltage coil 10 as in the conventional example.

The high-voltage coil 11 is divided into a plurality of coil parts, six coil parts in the embodiment, using a plurality of rectifier diodes 20, and each coil part is laminated and wound around a high-voltage bobbin with glabellar insulating paper interposed therebetween. The high voltage output voltage supplied from the high voltage end of the flyback transformer to the anode (not shown) of the cathode ray tube is detected by a variable resistor 15 as a high voltage detection means through a bleeder resistor 5, and this detection result is sent to a comparator amplifier 21 which will be described later. has been added to.

The high voltage control means 6 is wound on the high voltage side using the core 18 of the flyback transformer 2, and the correction voltage el (
a correction voltage generating coil 19 that generates the voltage shown in FIG. 2(a);
A reference pulse generating coil 22, an amplifier 23, a clip circuit 24, an integrating circuit 25, a comparison amplifier 21, an inverting amplifier 26, a switching operation control circuit 27, a switching circuit 28, and a correction voltage supply section 30. It is the main component. The circuit of this high-voltage control means 16 is known, for example, in Japanese Patent Laid-Open No. 1-298873, and a detailed explanation thereof will be omitted, and its structure and operation will be briefly explained.

The reference pulse generating coil 22 is wound around the core 18 of the flyback transformer 2 on the low voltage side insulated from other coils.
A pulse voltage e having a flyback pulse waveform shown in FIG. 2(a) is generated. The negative component of this pulse voltage e8 is cut off by the rectifier 31, and the positive component of the voltage e8 is passed to the amplifier 2.
30 is applied to the inverting input terminal, that is, the negative terminal.

Amplifier 23 amplifies this input voltage and applies its output to clip circuit 24 . Clip circuit 24 and amplifier 2
The head of the voltage waveform amplified by 3 is cut off to produce a rectangular wave voltage e3 whose pulse width is the retrace period Tr, as shown in FIG. 2(b), and this is applied to the integrating circuit 25. The integrating circuit 25 integrates the rectangular wave voltage e over the entire retrace period Tr, and as shown in FIG. 2(C),
The starting point of the retrace period is set to O, and a waveform that rises to the right is created with a peak value at the end point of the same period. In this case,
Since integration is not performed in the range exceeding the retrace period Tr, the waveform becomes a voltage waveform that slopes downward to the right due to discharge etc. from the peak position, and as a whole, the voltage es of the triangular wave peaks at the end point of the retrace period Tr. produced. The comparison amplifier 21 compares the triangular wave voltage es with the detection voltage e applied from the variable resistor 15 (FIG. 2(C)).
The control signal et (Fig. 2 (b)) is a constant negative (including 0) voltage in the section where s exceeds the detection voltage e4, and is a constant positive voltage at other times including the scanning period. to the inverting amplifier 26.

The output signal e, (FIG. 2(r)) whose polarity is inverted by the inverting amplifier 26 is applied to the switching circuit 28 (in this case, when the waveform of e7 is inverted by the inverting amplifier 26, the waveform e/, 2(e)), but t4~1
．． The period between t and t1° is in the scanning period Ts, and the power transistor 33 is cut off, so as a result, a voltage with a waveform of e is applied to the switching circuit 28), and the switching circuit 28 is inverted. When the voltage e applied from the amplifier 26 is positive, the correction voltage supply unit 30
Add a motion signal to.

The correction voltage supply section 30 has a drive transformer 32 and a power transistor 33 as main components, and the operating signal from the switching circuit 28 is transmitted to the drive transformer 3.
2 primary coil 34.

At this time, a base current that drives the power transistor 33 flows through the secondary coil 35 of the drive transformer 32, and the power transistor 33 is turned on and the correction voltage generating coil 1
Of the voltage el generated at 9, the voltage eI during the on period! is output as a correction voltage.

A feature of this embodiment is that a multiplier circuit (in the embodiment, a double voltage circuit) 17 is interposed between the correction voltage supply section 30 and the high voltage end of the high voltage coil ti. The multiplier circuit 17 is composed of an AC side capacitor 37, a DC side capacitor 38, 39, and a plurality of diodes 4°, and doubles the correction voltage applied from the emitter side of the power transistor 33 and uses it. It is added to the high voltage output voltage. That is, in the multiplier circuit 17, during the first retrace period, the current flows along the route a in FIG.
The power transistor 3 is connected to the DC side capacitor 38 shown in the figure.
Of the positive side voltage E of the correction pulse voltage e1 generated on the collector side of No. 3, E+z (FIG. 2(i)) is charged.

Next, during the scanning period, a current flows through route b. Next, during the blanking period again, current flows through route a, and DC
The capacitor 39 on the side is charged with a voltage of 2E,z,
The correction voltage supplied from the power transistor 33 is amplified twice and applied to the high voltage end of the flyback transformer 2. Note that FIG. 7 shows the voltage waveform at each point in FIG. 6, and FIG. 7(a) shows the waveform at each point when the pulse output from the power transistor 33 is ON. FIG. 7(b) shows the waveform at each point when the pulse is OFF.

In the design of this multiplier circuit, the DC side capacitor 3
8.39 is connected to the A'C-like earth point, but this earth point is not only a general earth, but also a cathode ray tube can be selected as the earth point, and as in this embodiment, the high voltage coil 11 In the type that is divided into a plurality of parts via the rectifier diode 20, the low voltage end of the high voltage coil can also be used as the ground point. In these cases, the DC side capacitor 38.39
When connecting the ground point on the cathode ray tube side, use D
This provides the advantage that the withstand voltage of the C-side capacitor 39 can be made lower than when other earth points are selected. Furthermore, in the case of a type in which the high voltage coil 11 is divided into a plurality of parts by rectifier diodes 20, if the correction voltage generating coil 19 is wound around the innermost layer of the laminated high voltage coil, this correction voltage generating coil 19 and Since the innermost coil portion of the high voltage coil 11 can be used as a DC capacitor, the DC capacitor 38 can be omitted. Also,
One end X of the DC side capacitor 39 may be connected to the cathode of an arbitrary current diode 20 that divides the high voltage coil 11 into a plurality of parts.

In the circuit of this embodiment, the detection voltage e6 decreases as the high output voltage decreases, and as can be seen from FIG.
Since the pulse width of the positive portion of the voltage becomes wider and the on period of the power transistor 33 becomes longer, the correction voltage elt applied to the high voltage output voltage becomes larger as shown in FIG. 2(C). Conversely, when the drop in the high-voltage output voltage is small, the positive pulse width of the voltage e= becomes narrower, and the on-period of the power transistor 33 becomes shorter (therefore, the magnitude of the correction voltage e+z added to the high-voltage output voltage also becomes smaller). In this way, in this embodiment, a correction voltage is applied according to the magnitude of fluctuation in the high-voltage output voltage by pulse width control, and the high-voltage output voltage is stabilized.

The switching operation control circuit 27 of this embodiment includes a transistor, and when the high voltage output voltage decreases significantly and the detection voltage e falls below the 0 voltage at the rising position of the triangular wave voltage e5, the switching operation control circuit 27 switches the reference pulse generating coil 22. Amplifier 23
FIG. 2 (
Using the waveform shown in g), the operating signal is transmitted from the switching circuit 2 to the drive transformer 3 during the entire retrace period.
2, the power transistor 33 is turned on throughout the retrace period, and the correction voltage is applied to the high voltage output voltage via the multiplier circuit 17.

By the way, when the correction voltage applied from the correction voltage supply section 30 is doubled by the multiplier circuit 17, there are two methods: one is to apply the doubler output directly to the high voltage end of the high voltage coil 11, as in this embodiment, One possible method is to apply it to the low-pressure end of the However, in the method of applying the double voltage output to the low voltage end of the high voltage coil 11, a large delay occurs when the current passing through the high voltage coil 11 for supplying the correction voltage to the high voltage output voltage passes through the high voltage coil 11 with high impedance. As a result, the high voltage current is delayed due to the influence of the high voltage coil glue and cage inductance, or the flyback transformer 2
A problem arises in that the transient response of the application of the correction voltage is delayed due to the delay in the correction voltage due to the integration circuit formed by the distributed capacitance.

In other words, when the beam current, that is, the high-voltage output current is shown as the waveform in Figure 3(a), the flow of this high-voltage output current causes the flyback transformer alone to produce a high-voltage output as shown in Figure 3(b). Voltage fluctuations occur. In order to compensate for this fluctuation in high voltage output voltage, as shown in Fig. 3(b)
By adding the correction voltage of the waveform and the vertically symmetrical waveform, the high voltage output voltage can be stabilized to a constant value. However, in the method in which the correction voltage doubled by the multiplier circuit is added to the high-voltage output voltage through the high-voltage coil 11, the rise position of the waveform of the correction voltage is different from the rise position of the beam current, as shown in FIG. 3(c). Due to this delay, the high voltage output voltage to which the correction voltage is applied is relatively large, as shown in Figure 3(d), for example, when the pulse width of the beam current is 81 m5 and the magnitude is 4 mA, When the output voltage drop is 2KV,
A problem arises in that even if a correction voltage is added, a voltage drop of approximately IKV remains. In other words, it becomes impossible to correct the drop in the high-voltage output voltage during the delay period of the application of the correction voltage, and this uncorrectable section occurs, resulting in a large shortfall in the high-voltage output voltage after correction.

In contrast, in this embodiment, the correction voltage doubled by the multivoltage circuit 17 is applied directly to the high-voltage output voltage without passing through the high-voltage coil 11, thereby causing a delay when passing through the high-voltage coil. In other words, in this embodiment, by bypassing the correction voltage to the high voltage end of the high voltage coil II by utilizing the phase advance of the AC side capacitor 37 of the multiplier circuit 17, no delay in transient response occurs. Therefore, as shown in FIG. 4(a), at the same time as the pulse rising position of the beam current,
As a result of the doubled correction voltage being added to the high voltage output voltage,
As shown in Fig. 4(b), the high voltage output voltage to which the correction voltage has been applied will only have a slight voltage drop, for example, about too v, and in the case shown in Fig. 3(d), In comparison, more effective stabilization control of the high voltage output voltage is performed.

Moreover, in this embodiment, since a double voltage circuit is adopted as the multiplier voltage circuit 17, at the midpoint of the high voltage coil 11,
l/2 of high voltage output voltage Hv. This has the effect of obtaining a stable voltage point. That is, as shown in FIG. 5, when the high voltage output voltage Hv decreases by ΔHv, the regulation characteristic for the high voltage output current is represented by the curve S1, and the decrease in the high voltage output voltage is represented by the area of the diagonal line A1. Therefore, in order to stabilize the high voltage output voltage Hv,
It is sufficient to add a correction voltage ΔHv represented by a region A2 which is vertically symmetrical to the region A. The regulation characteristic at the midpoint of the high voltage coil 11 is voltage H.

Curve S that is lowered by ΔHv/2 based on the voltage of /2
It becomes 2. This is 1/2 of the area of the diagonally shaded area A3 to A, which is ΔHv/2 lower than this Hv/2. In this embodiment, the multiplier circuit 17 is constituted by a double voltage circuit. A correction voltage of ΔHv/2 is applied before entering the multiplier circuit 17, that is, on the emitter side of the power transistor 33, and at the midpoint of the high voltage coil 11, this voltage of ΔHv/2 is applied to the regulation curve S.
2, and at the midpoint of the high voltage coil 11, a stable voltage of Hv/2 is obtained.

Therefore, if the bleeder resistor 5 for detecting the high-voltage output voltage is connected to the midpoint of the high-voltage coil 11, or if the focus adjustment voltage is extracted from the middle point of the high-voltage coil 11, good followability for the high-voltage output voltage can be achieved. This makes it possible to detect high output voltage and adjust focus with high precision. Furthermore, if the detection voltage and focus adjustment voltage are extracted from the midpoint of the high-voltage coil 11, the extraction voltage will be smaller than when these are extracted from the high-voltage end of the high-voltage coil 11, and the electric power discarded will also be reduced, resulting in power loss. will also be very small. Moreover, as mentioned above, since the extraction voltage can be reduced, when printing a circuit on a circuit board, the withstand voltage between the circuits can be reduced, and as a result, the circuit board can be made smaller. The device can be made smaller.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can take various embodiments.For example, in the above-mentioned embodiments,
Although the high voltage control means 16 is configured with a pulse width control type circuit, the high voltage control means is based on the detection result of the high voltage output voltage.
Any other circuit can be used as long as it has a circuit configuration that can apply the correction voltage to the multiplier circuit. For example, the correction voltage can be generated in a separate transformer, and the correction generated by this transformer can be used. The voltage may be applied to the multiplier circuit. In the case of this transformer as well, the correction voltage is generated in the form of a pulse, and the correction voltage with this pulse waveform is applied to the multiplier circuit.

Furthermore, in the above embodiment, the multiplier circuit is configured with a double voltage circuit, but it may also be configured with a circuit of other multiplier type, such as a triple voltage circuit or a quadruple voltage circuit. Various configurations are possible, such as interposing a plurality of multiplier circuits between the correction voltage supply section 30 and the high voltage output terminal of the high voltage coil 11. just,
In this case, as in this embodiment, the power transistor 33
For the type that uses pulse width control,
The circuit form of the multiplier circuit is designed in consideration of the withstand voltage of the power transistor 33.

〔Effect of the invention〕

The present invention uses a multiplier circuit to apply the drop in high voltage output voltage to the high voltage end of the secondary side of the flyback transformer, so it does not affect the primary side of the flyback transformer, and the - secondary side Various conventional problems caused by adding a correction current to the current can be effectively solved.

Moreover, since the present invention applies the correction voltage directly to the high-voltage end of the flyback transformer without passing it through the high-voltage coil of the flyback transformer, the time delay caused by passing the correction voltage through the high-voltage coil is completely eliminated. Therefore, the dynamic response to fluctuations in the high-voltage output voltage can be greatly improved, and the high-voltage output voltage can be stabilized with high precision.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the high voltage generation circuit according to the present invention, and FIG. 2 is a waveform diagram of each circuit part in the same embodiment.
FIG. 3 is a waveform explanatory diagram showing a delayed transient response state when a correction voltage is applied through a high-voltage coil; FIG. 4 is a waveform explanatory diagram showing a correction action in a state where there is no transient response delay in this embodiment; Fig. 5 is an explanatory diagram of the regulation characteristics at the midpoint of the high voltage coil in this embodiment, Fig. 6 is a circuit diagram explaining the operation of the multiplier circuit in this embodiment, and Fig. 7 is an illustration of each point in Fig. 6. The voltage waveform diagrams in FIGS. 8 and 9 are circuit diagrams of a high voltage generating circuit equipped with a conventional general high voltage stabilizing means. 1.--Horizontal deflection output circuit, 2.--Flyback transformer, 3.--Horizontal deflection coil, 4.--High voltage stabilizing means, 5.
- bleeder resistor, 6 - comparator, 7 - power supply, 8 - control transistor, IO - low voltage coil, l l - high voltage coil, 12 - saturable reactor, 12a, 12b -
Coil, 13-damper diode, 14--reverse current absorption capacitor, 15--variable resistor, 16--high voltage control means, 17--multiplier circuit, 18--core, 19-
---1 Correction voltage generating coil, 20- Rectifier diode,
21-comparison amplifier, 22--reference pulse generation coil,
23-Amplifier, 24-Clip circuit, 25-Integrator circuit, 26-Inverting amplifier, 27-Switching operation control circuit, 28-Switching circuit, 30 Correction voltage supply section, 31-Rectifier, 32--Drive transformer, 33 −
・Power transistor, 34・--Primary coil, 35
・-Secondary side coil, 36-Resistor, 3'7'-A C side capacitor, 38.39---D C side capacitor, 4
0 diode.

Claims (1)

[Claims] A flyback transformer that boosts the flyback pulse and applies a high output voltage to the anode of the cathode ray tube, a high voltage detection means for the high voltage output voltage, and a correction voltage corresponding to fluctuations in the high voltage output voltage detected by the high voltage detection means. In a high voltage generation circuit having a high voltage control means applied to the high voltage side of a flyback transformer, the correction voltage is amplified between the high voltage control means and the high voltage end of the high voltage coil constituting the flyback transformer, and the high voltage of the high voltage coil is directly applied. A high voltage generation circuit characterized by being provided with a multi-voltage circuit applied to the end side.