JPH0481172A - High voltage stable circuit - Google Patents

Abstract

PURPOSE:To reduce power loss with a regulator by providing a variable capacitance circuit comprising n-set of capacitors whose capacitance is variable connected in parallel with a resonance capacitance and a control means controlling the capacitance of the circuit in response to a high DC voltage to the title circuit. CONSTITUTION:The resonance capacitance is changed to control a high voltage by using a regulator so as to turn on/off each of switch circuits 14a-14h of a variable capacitance circuit 11. Each of capacitors 13a-13h of the variable capacitance circuit 11 has a capacitance of KX2<m> (m is a positive integer from 1 to n) and the capacitance is varied from a minimum capacitance KX2 to a maximum capacitance KX2<n> at a step of KX2. Thus, the computer processing is easily implemented and the accuracy is improved. Moreover, the high voltage stabilizing circuit detects and compares a high voltage, a decoder circuit 12 decodes the result to change the resonance capacitance by selecting each of the switch circuits 14a-14h of the variable capacitance circuit 11 thereby making the high voltage stable.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to high voltage stabilizing circuits used in television receivers.

BACKGROUND OF THE INVENTION In recent years, as the image quality of television receivers has improved, high voltage stabilizing circuits that do not undergo high voltage fluctuations due to beam current have come to be used.

An example of a conventional high voltage stabilizing circuit will be described below with reference to the drawings. FIG. 2 shows a conventional high voltage stabilizing circuit. As shown in Figure 2, the components are 1 a switching transistor, 2 a damper diode, 3 a resonant capacitor, 4 a flyback transformer, 6 a high voltage detection circuit, 6 a reference voltage, and 7 a comparison circuit. , 8 is a regulator transistor, 9 is a smoothing capacitor, 10
consists of a power supply.

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A resonant circuit is made up of the resonant capacitor 3 and the primary inductance of the flybank transformer 4. This resonant frequency determines the pulse width. The transistor 1 is performing a switching operation, and current flows from the flyback transformer 4 to the transistor 1 during the latter half of the on period. When the transistor 1 is turned off, it generates a resonant voltage (collector pulse) having a half wave of the aforementioned pulse width determined by the flyback transformer 4 and the resonant capacitor 3.

This collector pulse is boosted by a flyback transformer 4 to obtain a high voltage from the secondary side. During the second half of the off period and the first half of the on period, diode 2 in flybank transformer 4
As a result, current is flowing towards the power supply. By changing the input voltage (+B voltage) of the flybank transformer 4, the peak value of the collector pulse can be changed and the high voltage can be controlled. In the high-voltage stabilizing circuit, a high-voltage detection circuit 5 detects high-voltage fluctuations due to changes in beam current, compares them with a reference voltage 6 in a comparator circuit 7, and converts the input electrons (-1-B voltage) of the flyback transformer 4 through a regulator transistor 8. By tilting the beam to the side, high voltage fluctuations due to beam current are eliminated and stable high voltage is obtained.

Problems to be Solved by the Invention However, in the above configuration, the regulator transistor 8 is used to stabilize the high voltage.
This causes power loss and activation becomes a problem.

The present invention takes the above problems into consideration and provides a highly efficient and highly accurate high voltage stabilizing circuit.

Means for Solving the Problems In order to achieve the above object of the present invention, a variable capacitance circuit consisting of n capacitors whose capacitance can be varied in parallel with a resonant capacitor and a Nuinochian circuit, and a capacitance of this variable capacitance circuit are provided. This is a high voltage stabilizing circuit that stabilizes high voltage by providing a control means that controls the value according to the high voltage DC voltage.

Function: In the high-voltage stabilizing circuit of the present invention using the grooved membrane described above, when the capacitance value of the variable capacitance circuit changes, the resonance frequency changes and the pulse width of the collector pulse changes. Therefore, the high voltage DC voltage of the secondary side output of the flyback transformer also changes, and the high voltage DC voltage can be controlled. One element of the accuracy of this control is the variable width of the variable capacitance value of the variable capacitance circuit, and the accuracy improves as the value of n of n capacitors increases. In addition, if the capacitance value of each of n capacitors is composed of 2m times the specific capacitance value (cm is a positive integer value from 1 to n), it is easy to correlate with bit processing by a computer, and the combination This enables highly accurate high-level step control.

In any case, as a high-voltage DC voltage load, for example, the high-voltage DC voltage can be stabilized by controlling the capacity of a variable capacitance circuit with a control means against beam current fluctuations of a television receiver or power supply voltage fluctuations. As a result, a highly efficient high-voltage stabilization circuit with no transistor loss for the regulator can be realized.

EXAMPLE Hereinafter, a high voltage stabilizing circuit according to an example of the present invention will be described with reference to the drawings. FIG. 1 shows a circuit diagram of a high voltage stabilizing circuit in an embodiment of the present invention.

As shown in Figure 1, the components are: 1 a switching transistor, 2 a damper diode, 3 a resonant capacitor, 4 a fly bank transformer, 5 a high voltage detection circuit as a high voltage detection means, and 6 a reference voltage. , 7 is a comparison circuit,
Reference numeral 10 denotes a power source, which has the same configuration as that shown in FIG. 2. The difference from the configuration shown in FIG. 2 is that a variable capacitance circuit 11 and a decoder circuit 12 are provided, and the regulator transistor is eliminated. Further, the reference voltage 6, the comparison circuit 7,
The decoder circuit 12 constitutes a control means.

Regarding the high voltage stabilizing circuit configured as described above, the mutual relationship and operation of the constituent elements will be explained below.

Similar to the conventional example shown in FIG. 2, a resonant circuit is formed by the resonant capacitor 3 and the primary inductance of the flyback transformer 4.

This resonant frequency determines the pulse width. The transistor 1 is performing a switching operation, and current flows from the fly bank transformer 4 to the transistor 1 during the latter half of the on period.

When transistor 1 turns off, flyback transformer 4
and the resonant capacitor 3 generate a resonant voltage (collector pulse) having the aforementioned half-wave pulse width. This collector pulse is boosted by a -y flyback transformer to obtain a high voltage from the secondary side.

During the second half of the off period and the first half of the on period, current flows toward the power source in the flyback transformer 4 due to the diode 2.

The difference from FIG. 2 is that instead of changing the 10B voltage with a regulator, each switch circuit 14 of the variable capacitance circuit 11
By turning on and off a to 14h, the resonance capacitance is changed to control the high voltage.

Each capacitor 13a to 13h of the variable capacitance circuit 11 is K
×2m (m is a positive integer from 1 to n''!), and the minimum capacitance value KX2 to the maximum capacitance value KX2
It can be changed up to n in KX2 increments, and
The combination further increases the variable range. Furthermore, since it changes in units of 2n, there is a correlation with computer bit processing, making computer processing easier and improving accuracy. In addition, the high voltage stabilizing circuit detects and compares the high voltage value, decodes it in the decoder circuit 12, and decodes it in the variable capacitance circuit 11.
By switching each of the switch circuits 142L to 14h, the resonance capacitance is changed and the high voltage value is stabilized. If the switching timing of the switch circuits 142L to 14h is performed at a time other than the collector pulse period, switching can be performed without loss. At this time, a regulator for voltage control is not required, and loss due to control is eliminated.

Effects of the Invention As is clear from the above explanation, according to the present invention, a variable capacitance circuit consisting of a plurality of capacitors and a switch circuit is installed and the resonant capacitance is changed, thereby eliminating the need for a regulator for voltage control. , loss due to control can be eliminated.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a high voltage stabilizing circuit according to an embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional high voltage stabilizing circuit. 1...Transistor, 2...Diode,
3...Resonance field i, 4...Flyback transformer, 6...High voltage detection circuit, 6...
-Reference voltage, 7.Comparison circuit, 11...Variable capacitance circuit, 12...Decoder circuit, 13a~
13h...Capacitor, 141L~14h...
...Switch circuit. Name of agent: Patent attorney Shigetaka Awano and one other person Transistor 9 Circuit diagram of il road lever-90 content switch circuit pressure sensitive 9 constant F3 road

Claims (2)

[Claims] (1) A flyback transformer for high voltage generation, a switching element connected to the primary side of the flyback transformer, and a resonant capacitor connected in parallel with the switching element and resonating with the switching output of the switching element. , a variable capacitance circuit configured of n capacitors and a switch circuit connected in parallel with the resonant capacitor, and high voltage detection means for detecting a high voltage DC voltage after DC conversion on the secondary side of the flyback transformer. , a control means for controlling a switch circuit of the variable capacitance circuit based on the detected voltage detected by the high voltage detection means, and the switch circuit is configured such that the control means stabilizes the high voltage DC voltage. A high voltage stabilizing circuit that controls the capacitance value of the variable capacitance circuit to change the capacitance value of the variable capacitance circuit. (2) The capacitance value of n capacitors is 2^ of the specific capacitance value.
2. The high voltage stabilizing circuit according to claim 1, comprising m times (m is a positive integer up to n).