JPH0445668A - High voltage generating circuit - Google Patents

Abstract

PURPOSE:To improve a dynamic high voltage regulation characteristic and to stabilize a high output voltage by interposing a top capacitor for bypassing and applying a correcting voltage between the high voltage terminal of a high voltage coil and the low voltage terminal side of a coil winding separated from the high voltage side to the low voltage side for more than one winding. CONSTITUTION:The correcting voltage is bypassed and applied to a high voltage rectifier diode 7 by a top capacitor 17 without passing it through a coil part 6f in the final step where a leakage inductance is made largest, and therefore, the influence of distributed capacitance in the coil part 6f of the final step can be avoided. Since the high output voltage is effectively corrected, the breakdown voltage of the top capacitor 17 can be small, the cost of the said capacitor 17 can be reduced and the capacitor 17 can be miniaturized.

Description

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

[Conventional technology]

When a high voltage output current flows from the high voltage end of the flyback transformer to the anode of the cathode ray tube due to some reason such as brightness adjustment, the high voltage output voltage drops and the high voltage regulation characteristics of the circuit deteriorate. For this reason,
In the past, a correction voltage was applied to the primary side of the flyback transformer to correct the drop in the high-voltage output voltage, but this method of adding correction voltage to the primary side required a complicated circuit and a large device. In recent years, a type of flybank transformer that applies a correction voltage to the low voltage end of the high voltage coil in a flybank transformer has been proposed, for example, in JP-A-1-29.
This is proposed in Japanese Patent No. 8873.

This proposed device is equipped with a high voltage output voltage detection means, an additional voltage generation means, and a high voltage stabilization control means, and the high voltage stabilization control means is adapted to the high voltage detection result of the high voltage output voltage detection means. Based on this, the additional voltage generated by the additional voltage generating means is controlled, and a correction voltage corresponding to the drop in the high voltage output voltage is applied to the low voltage end of the high voltage coil of the flyback transformer, thereby stabilizing the high voltage output voltage. .

[Problem to be solved by the invention]

However, in the method of applying the correction voltage to the low-voltage end of the high-voltage coil, the correction voltage is affected by the leakage inductance of the high-voltage coil on the way from the low-voltage end to the high-voltage end of the high-voltage coil. Therefore, there is a problem in that the applied acceleration of the correction voltage, that is, the transient response is delayed, and a certain limit arises in stabilizing the high voltage output voltage.

In other words, on the high voltage side of the flyback transformer, there is a
) When a high-voltage output current (beam current) as shown in ) flows, a voltage drop as shown in Fig. 4 (mata) occurs in the flyback transformer alone. At this time, in order to stabilize the high voltage output voltage, it is sufficient to apply a correction voltage in an upside-down pattern as shown in FIG. Due to response delay,
As shown in Figure 4 (C), the rise of the correction voltage is delayed from the rise position of the beam current, and the high voltage output voltage after correction remains as shown in Figure 4 (as shown by the peak, a considerable voltage drop remains uncorrected, There is a problem that the high voltage output voltage cannot be sufficiently stabilized.The delay period of the transient response becomes an uncorrectable area, and in the method of adding the correction voltage to the low voltage end of the high voltage output voltage, this uncorrectable interval Due to this occurrence, there is a certain limit to the stabilization of the high-voltage output voltage, and there is a problem that the dynamic regulation characteristics of the high-voltage output voltage cannot be fully satisfied.

The present invention has been made to solve the above-mentioned conventional problems, and its purpose is to minimize the delay in transient response caused by applying a correction voltage to the low voltage end of a high voltage coil, and to improve dynamic regulation characteristics. Therefore, it is an object of the present invention to provide a high voltage generation circuit that can more effectively stabilize a high voltage output voltage.

[Means to solve the problem]

In order to achieve the above object, the present invention is configured as follows. That is, the present invention provides a flyback transformer that boosts a flyback pulse and supplies a high-voltage output voltage from the high-voltage end side of a high-voltage coil to an anode of a cathode ray tube via a high-voltage rectifier diode, and a flyback transformer that detects the high-voltage output voltage and supplies the high-voltage output voltage to the anode of a cathode ray tube. In a high voltage generation circuit, the high voltage output voltage stabilizing circuit applies a correction voltage corresponding to a voltage drop to the low voltage end side of the high voltage coil. The correction voltage is applied between the output end side of the high voltage rectifier diode and the low voltage end side of a coil layer separated from the high voltage end of the high voltage coil by one or more layers on the low voltage side. The structure is characterized in that a top capacitor is interposed to apply a bypass voltage to the top capacitor.

[Operation] In the present invention, when the high voltage output voltage drops, the high voltage output voltage stabilizing circuit operates, and a correction voltage is applied to the low voltage end side of the high voltage coil. This correction voltage passes through the coil layer on the low-voltage end of the high-voltage coil to the top capacitor, and then passes through the top capacitor and bypasses one or more coil layers on the high-voltage end of the high-voltage coil to the high-voltage rectifier diode. The correction voltage is added to the high-voltage output voltage without being affected by the cage inductance of the bypassed coil layer portion.

〔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. In the figure, a flyback transformer l has a core 2 wound with a low voltage coil 3 and a high voltage coil 4, and the low voltage coil 3 is connected to a horizontal deflection output circuit (not shown).

The high-voltage coil 4 is divided into a plurality of coil parts 68-6f via rectifier diodes 5a-5e, and each coil part 6a-6f is laminated and wound around a high-voltage bobbin with glabellar insulating paper or the like interposed therebetween. The rectifying diodes 5a to 5e are connected between the end of winding of the coil portion of each layer and the start of winding of the coil portion of the next layer in the direction of adding voltage. Further, the high voltage end of the final stage coil portion 6f of the high voltage coil 4 is connected to an anode (not shown) of a cathode ray tube via a high voltage rectifier diode 7.

The high output voltage detection means is constituted by a capacitor 8.9 and a resistor 10.11. Capacitor 8.
9 are connected in series, and resistors 10 and 11 are also connected in series, and one end of the capacitor 8 and one end of the resistor 10 are both connected to the cathode side of the high voltage rectifier diode 7. , the other ends of the capacitor 9 and resistor 11 are connected to ground. And capacitor 8.
The connection portion 9 and the connection portion of the resistor 10.11 are commonly connected to each other, and this common connection portion is connected to the negative terminal of the comparator amplifier 12. Also, comparison amplifier 1
A reference voltage generating circuit 13 is connected to the positive side terminal of 2. This reference voltage generation circuit 13 provides a reference voltage for determining a drop in the high voltage output voltage, and the comparison amplifier 12 uses the reference voltage applied from this reference voltage generation circuit 13 and the voltage detected through the resistor 1o. The high voltage output voltage is compared with the detected voltage, and a signal corresponding to the amount of drop in the high voltage output voltage is applied to the correction voltage control circuit 14.

The correction voltage control circuit 14 includes an addition voltage generation section and an addition voltage control section, and the addition voltage control section receives the signal from the comparator amplifier 12 and generates the addition voltage in the addition voltage generation section by pulse width control or the like. The added voltage is used to create a correction voltage corresponding to the amount of drop in the high voltage output voltage, and this voltage is applied to the low voltage end of the high voltage coil 4 via the diode 15. The high-voltage output voltage detection means, comparator amplifier 12, reference voltage generation circuit 13, and correction voltage control circuit 14 constitute a high-voltage output voltage stabilization circuit, and this circuit is disclosed in the above-mentioned Japanese Patent Laid-Open No. 1-298873. etc., and detailed explanation thereof will be omitted.

In this embodiment, a diode 16 is connected between the low voltage end of the high voltage coil 4 and the ground, with its anode on the ground side. This diode 16 is provided to ensure a ground point for the circuit even when the negative side voltage of the flyback pulse is applied so that the high voltage stabilizing circuit can operate without any trouble.

The characteristic feature of this embodiment is that the output end of the high voltage rectifier diode 7 and the high voltage end of the high voltage coil 4 (the high voltage end of the final stage coil portion 6f of the high voltage coil 4) are separated by only one layer on the low voltage side. The top capacitor 17 is interposed between the low voltage end of the coil portion 6f. In this way, by providing the top capacitor 17, the correction voltage applied to the low voltage end of the high voltage coil 4 is adjusted to the first layer coil portion 6a.
After passing through the coil section 6e of the fifth layer, the top capacitor 17 is connected without passing through the final stage coil section 6f.
It is bypassed and added to the output terminal of the high voltage rectifier diode 7.

The present embodiment is configured as described above, and its operation will be explained below. When a beam current flows from the high voltage end of the high voltage coil to the anode of the cathode ray tube for some reason, the high voltage output voltage drops, the voltage drop is detected through the resistor 10, and the detected voltage is applied to the comparison amplifier 12. The comparison amplifier 12 compares the reference voltage applied from the reference voltage generation circuit 13 with the detected voltage, and applies a signal corresponding to the amount of drop in the high voltage output voltage to the correction voltage control circuit 14.

The correction voltage control circuit 14 controls the voltage generated by the addition voltage generating section, creates a correction voltage commensurate with the amount of drop in the high voltage output voltage, and applies this to the low voltage end of the high voltage coil 4. The correction voltage applied to the low voltage end of the high voltage coil 4 is applied to the output end of the high voltage rectifier diode 7 through the top capacitor 17 after passing through the coil parts 6a to 6e.

In this way, since the correction voltage is added to the high voltage output voltage by the top capacitor 17 while bypassing the final stage coil portion 6r, a significant improvement in the transient response of correction voltage application is achieved. That is, when the high voltage coil 4 is divided by rectifier diodes 5a to 5e to form a multilayer structure, the cage inductance of the coil portion of each layer is expressed as shown in FIG. As can be seen from this curve, the leakage inductance of the coil portion 6f on the high voltage end side of the high voltage coil 4 is the largest, and the coil portion 6a on the low voltage side
The leakage inductance becomes smaller as the distance increases.

Therefore, as in this embodiment, by bypassing the correction voltage with the top capacitor 17 and applying it to the output terminal of the high voltage rectifier diode 7, without passing it through the final stage coil section 6f where the leakage inductance is the largest. , the influence of the phase splitting capacitance of the final stage coil portion 6f can be avoided.

As mentioned above, the delay in the transient response is influenced by the size of the time constant due to the cage inductance, and by bypassing the final stage coil section 6r, the time constant can be made small. It is possible to dramatically improve the transient response when applying .As a result,
When a correction voltage is applied to the low voltage end of the high voltage coil 4, as shown in Figure 2 (
As shown in a), the rising position of the correction voltage almost coincides with the rising position of the beam current, and the delay period (FIG. 4(C)) that occurs when the top capacitor 17 is not provided becomes very small. Therefore, when the high-voltage output voltage drops, a correction voltage is applied extremely quickly, and the high-voltage output voltage after correction is as shown in Figure 2b).
For example, when the voltage drop is 2KV, as shown in
At most, only a voltage drop of about 100ν remains,
The high output voltage is effectively corrected.

Furthermore, in this embodiment, since the top capacitor 17 is provided between the final stage coil portion 6f of the high voltage coil 4, the withstand voltage of the top capacitor 17 may be small;
It is possible to reduce the cost and size of the capacitor 17.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and may take various embodiments.For example, in the above-mentioned embodiments,
The top capacitor 17 is provided between the output end of the high voltage rectifier diode 7 and the winding start side of the first layer coil portion 6r from the high voltage end of the high voltage coil 4 toward the low voltage side. The output end of the diode 7 is one end, and the other end is a coil portion 6e, 6d, etc. of 2N or more from the high voltage end of the high voltage coil 4 to the low voltage side.
・Can be connected to the low pressure end (winding start end) of .

In this way, as the number of bypassed coil sections increases, the one-cage inductance decreases and the transient response becomes correspondingly faster. However, as the number of coil parts to be bypassed increases, the top capacitor 17
It must be noted that the withstand voltage must be increased.

Further, as shown in the circuit of FIG. 3, a capacitor 18 may be provided in parallel with the diode 16, or the capacitor 8 of the circuit of FIG. 1 may be omitted, and various circuit changes are possible.

(Effects of the Invention) The present invention provides a correction voltage between the output end side of a high voltage rectifier diode and the low voltage end side of a coil layer separated by one or more layers from the high voltage end to the low voltage side of the high voltage coil divided by the rectifier diode. Since the top capacitor that bypasses the voltage is inserted, the correction voltage can be added to the high voltage output voltage while avoiding the part of the high voltage coil where the leakage inductance is the largest.As a result, the transient response when applying the correction voltage can be reduced. The delay can be made very small, which results in
Improved dynamic high pressure regulation characteristics,
It becomes possible to stabilize the high voltage output voltage more effectively.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the high voltage generation circuit according to the present invention, FIG. 2 is an explanatory diagram of waveforms of the correction action in the same embodiment, and FIG. 3 is a circuit diagram showing the high voltage generation circuit according to the present invention. FIG. 4 is a waveform explanatory diagram showing the correction effect of a conventional high voltage generation circuit that applies a correction voltage to the low voltage end of a high voltage coil. FIG. It is a graph showing the relationship with cage inductance. 1... flyback transformer, 2... core, 3...
・Low voltage coil, 4...High voltage coil, 5.5a to 5e・
... Rectifier diode, 6a to 6f ... Coil part, 7
...High voltage rectifier diode, 8.9...Capacitor,
10.11...Resistor, 12...Comparison amplifier, 13
...Reference voltage generation circuit, 14...Correction voltage control circuit, 15°16...Diode, 17...Top capacitor, 18...Capacitor.

Claims (1)

[Claims] A flyback transformer that boosts the flyback pulse and supplies the high-voltage output voltage from the high-voltage end of the high-voltage coil to the cathode ray tube anode via a high-voltage rectifier diode, and a correction that detects the high-voltage output voltage and responds to a drop in the high-voltage output voltage. A high voltage generation circuit is provided with a high voltage output voltage stabilizing circuit that applies voltage to a low voltage end side of a high voltage coil, the high voltage coil is divided into a plurality of coil layers via rectifier diodes, and the high voltage rectifier Between the output end of the diode and the low voltage end of a coil layer separated from the high voltage end of the high voltage coil by one or more layers on the low voltage side, there is a top capacitor that bypass-applies the correction voltage to the output end of the high voltage rectifier diode. A high voltage generation circuit characterized in that a high voltage generation circuit is provided.