JP3562257B2 - High voltage supply circuit - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a high voltage supply circuit for supplying a high voltage to an anode electrode of a CRT in a display using a CRT.
[0002]
[Prior art]
FIG. 7 shows a configuration of a conventional high voltage supply circuit. In FIG. 7, reference numeral 1 denotes a high-voltage generation circuit, 2 denotes a CRT, 3 and 4 denote capacitance elements, and 12 denotes a resistance element. The operation of the high voltage supply circuit configured as described above will be described below.
In FIG. 7, the high voltage generated by the high voltage generation circuit 1 is supplied to the anode electrode of the CRT 2 via a filter composed of the capacitance elements 3 and 4 and the resistance element 12 to drive the CRT 2. As described above, high voltage with reduced ripple is supplied to the anode electrode of the CRT 2 through the filter constituted by the capacitance elements 3 and 4 and the resistance element 12.
[0003]
[Problems to be solved by the invention]
However, in the above-described conventional configuration, a high-voltage current generated by the high-voltage generation circuit 1 is supplied to the CRT via the resistance element 12, and a voltage drop occurs in the resistance element 12. In addition, since the amount of current supplied to the CRT changes according to the video signal of the signal source connected to the display, the amount of the voltage drop also changes, and the high-voltage stability decreases.
When the high-pressure stability is reduced, the image projected on the display may be distorted and the image projected on the display may be distorted, or the luminance on the screen may change and luminance unevenness may be seen on the display. There is a problem that the faithful reproduction of the image signal source cannot be performed.
[0004]
Further, the conventional configuration has the above-described problem, and the resistance value of the resistance element 12 cannot be selected to be large enough to reduce the high-voltage ripple. Therefore, the high-voltage ripple cannot be sufficiently reduced, and asynchronous brightness unevenness occurs on the display screen, which causes a problem that the image quality is deteriorated. In addition, there is a problem that power consumption is increased due to a voltage drop generated in the resistance element 12.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned conventional problems, a high-voltage supply circuit of the present invention is sufficiently sealed with an epoxy resin or the like to prevent high-voltage discharge, and furthermore, a coil and a capacitor having a sufficient inductance value to obtain a filtering effect. It is characterized in that a high voltage with sufficiently reduced high voltage ripple is supplied to an anode electrode of a CRT by using a filter composed of elements.
[0006]
ADVANTAGE OF THE INVENTION According to this invention, the subject that the voltage drop by the conventional resistance element is large and the high-pressure stability is impaired can be easily solved by the filter circuit using the coil whose DC resistance value is very small.
Furthermore, since the voltage drop due to the resistive element is eliminated and the high voltage stability is improved, it is possible to select an inductance value large enough to reduce the high voltage ripple. The problem of uneven brightness and deterioration of the image quality can be easily solved. In addition, since the voltage drop due to the resistance element is eliminated, the problem of increased power consumption due to the voltage drop can be easily solved.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
A high-voltage supply circuit according to a first aspect of the present invention includes: a high-voltage generation circuit that generates a high voltage to be supplied to an anode electrode of a CRT; and a high-voltage output of the high-voltage generation circuit. The output is input to one end of a coil. A filter connected to the other end of the capacitive element, the filter having the other end as an output, and a capacitive element modulation circuit connected to one of the two terminals of the capacitive element that is not connected to the coil; The capacitance element modulation circuit detects an output fluctuation signal of the high voltage generation circuit, and modulates one of the two terminals of the capacitance element that is not connected to the coil with an inverted signal obtained by inverting the signal. And has the effect of improving the stability of high pressure.
[0014]
A high-voltage supply circuit according to a second invention is the high-voltage supply circuit according to the first invention , wherein the secondary-side current detection circuit detects a current flowing to the secondary side of the high-voltage generation circuit; An amplifier circuit for amplifying a current detected by the circuit, wherein an output of the amplifier circuit is input to the capacitive modulation circuit as an output variation of the high-voltage generating circuit and connected to the coil among two terminals of the capacitive element It is characterized by modulating the potential of one terminal that is not operated, and has the effect of improving the stability of high voltage.
[0015]
A high-voltage supply circuit according to a third aspect of the present invention is the high-voltage supply circuit according to the first aspect , wherein the high-voltage change detection circuit detects a change in a high-voltage output of the high-voltage generation circuit. An amplifier circuit to which the detected detection signal is input, wherein the output of the amplifier circuit is input to the capacitive modulation circuit as an output variation of the high-voltage generating circuit and connected to the coil among the two terminals of the capacitive element It is characterized by modulating the potential of one terminal that is not operated, and has the effect of improving the stability of high voltage.
[0016]
High pressure supply circuit of the fourth invention, in the high pressure supply circuit according to the first invention, the input and the cathode current detecting circuit for detecting a current flowing to the cathode of a CRT, or a signal detected by the cathode current detecting circuit And a delay circuit to which the output of the amplification circuit is input. The output of the delay circuit is input to the capacitance modulation circuit as an output fluctuation of the high-voltage generation circuit, and two terminals of the capacitance element are provided. And modulating the potential of one terminal not connected to the coil, and has an action of improving the stability of high voltage.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0017]
(Embodiment 1)
Hereinafter, embodiments of the first and second aspects of the present invention will be described with reference to FIG.
In FIG. 1, reference numeral 1 denotes a high-voltage generating circuit, 2 denotes a CRT, 3 and 4 denote capacitive elements, and 5 denotes a coil. The operation of the high voltage supply circuit configured as described above will be described below.
[0018]
The high voltage generated by the high voltage generation circuit 1 is supplied to the anode electrode of the CRT 2 via the capacitive element 3, the coil 5, and the capacitive element 4. Here, the high-voltage ripple generated by the switching operation of the high-voltage generation circuit is reduced by the filter including the capacitance element 3 and the capacitance element 4 and the coil 5 having the capacitance value and the inductance value that cancel the high-voltage ripple. Furthermore, since the DC resistance value of the coil 5 is very small, a voltage drop caused by the current supplied from the high voltage generation circuit 1 flowing through the coil 5 hardly occurs. With the above operation, even when a very large current is supplied from the high voltage generation circuit 1 to the anode electrode of the CRT 2, the high voltage stability does not decrease.
[0019]
Also, since the coil 5 generates a high-voltage ripple at the same frequency as the switching frequency in the high-voltage generating circuit 1, an inductance value that can constitute a filter having a cutoff frequency capable of sufficiently attenuating the ripple at this frequency. In addition, the coil 5 needs to be sealed with an epoxy resin or the like in order to be able to sufficiently suppress high-voltage discharge in both the coil portion and the electrode portion in order to be used in a high voltage portion.
[0020]
(Embodiment 2)
Next, an embodiment described in the third and fourth inventions will be described with reference to FIGS. The same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted.
[0021]
In the first and second inventions, the capacitive element 3 and the capacitive element 4 are grounded, and a filter composed of the capacitive element 3, the coil 5, and the capacitive element 4 is used to further reduce high-voltage ripple. In the case of such a configuration, the voltage drop due to the current flowing from the high voltage generation circuit 1 to the coil 5 is very small, so that the high voltage stability is reduced and the image displayed on the display has a straight line. Degradation of image quality, such as the distorted display of expected images and the change in luminance on the screen resulting in uneven luminance on the display, making it impossible to faithfully reproduce the image signal source connected to the display. Cause.
[0022]
Therefore, in the present embodiment, by providing the capacitive element modulation circuit 6 that modulates the potential on the negative electrode side of the capacitive element 4 so that the high-voltage stability is optimized, the configuration of the first and second inventions can be improved. A high pressure with high high-pressure stability can be supplied to the anode electrode of the CRT 2.
[0023]
FIG. 3 shows the state of optimal modulation. In response to the fluctuation of the high voltage as shown in FIG. 3, the capacitance element modulation circuit 6 modulates the potential on the negative electrode side of the capacitance element 4 with a modulation signal as shown in FIG. An optimal high-stability high voltage can be supplied to the anode electrode of the CRT 2.
[0024]
(Embodiment 3)
Next, an embodiment described in the fifth and sixth inventions will be described with reference to FIG. The same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted.
[0025]
In the first and second inventions, the capacitive element 3 and the capacitive element 4 are grounded, and a filter composed of the capacitive element 3, the coil 5, and the capacitive element 4 is used to further reduce high-voltage ripple. In the case of such a configuration, the voltage drop due to the current flowing from the high voltage generation circuit 1 to the coil 5 is very small, so that the high voltage stability is reduced and the image displayed on the display has a straight line. Degradation of image quality, such as distorted display of supposed images and unevenness of luminance on the screen due to changes in luminance on the screen, makes it impossible to faithfully reproduce the image signal source connected to the display. Cause.
[0026]
Therefore, as shown in the third and fourth inventions, there is a method of modulating the potential on the negative electrode side of the capacitive element 4 with the capacitive element modulation circuit 6 so that the high-voltage stability is optimized. However, if a signal for modulating the potential on the negative electrode side of the capacitive element 4 by the capacitive element modulation circuit 6 so that the high-voltage stability is optimized is generated, the circuit becomes complicated and the circuit scale is increased. I was
[0027]
Therefore, in the present embodiment, the above-mentioned problem is solved by using the secondary side current detection circuit 8 and the amplification circuit 7 of the high voltage generation circuit 1 as shown in FIG. In FIG. 4, a voltage signal proportional to the current flowing to the secondary side of the high voltage generation circuit 1 detected by the secondary side current detection circuit 8 composed of a resistance element is used to convert the potential on the negative electrode side of the capacitance element 4 to the high voltage stability. Is modulated by the capacitance element modulation circuit 6 so as to optimize the voltage, the signal is amplified by the amplification circuit 7 to an optimum amplitude, and the voltage on the negative electrode side of the capacitance element 4 is adjusted by the voltage signal so that the high voltage stability is optimized. Modulation is performed by the capacitance element modulation circuit 6. Here, since the current on the secondary side of the high voltage generation circuit 1 changes in accordance with the fluctuation of the high voltage, the potential on the negative electrode side of the capacitance element 4 is adjusted by the capacitance element modulation circuit 6 so that the high voltage stability is optimized. It can be used as a signal to be modulated.
[0028]
As shown in FIG. 4, by using the current flowing on the secondary side of the high voltage generation circuit 1 as a signal for modulating the potential on the negative electrode side of the capacitance element 4 by the capacitance element modulation circuit 6 so that the high voltage stability is optimized. With a simple circuit, it is possible to improve the high-pressure stability with respect to the configurations of the first and second inventions.
[0029]
(Embodiment 4)
Next, an embodiment described in the seventh and eighth inventions will be described with reference to FIG. The same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted.
[0030]
In the first and second inventions, the capacitive element 3 and the capacitive element 4 are grounded, and a filter composed of the capacitive element 3, the coil 5, and the capacitive element 4 is used to further reduce high-voltage ripple. In the case of such a configuration, the voltage drop due to the current flowing from the high voltage generation circuit 1 to the coil 5 is very small, so that the high voltage stability is reduced and the image displayed on the display has a straight line. Degradation of image quality, such as the distorted display of expected images and the change in luminance on the screen resulting in uneven luminance on the display, making it impossible to faithfully reproduce the image signal source connected to the display. Cause.
[0031]
Therefore, in the fifth and sixth inventions, a method of modulating the potential on the negative electrode side of the capacitive element 4 by the capacitive element modulation circuit 6 based on the secondary side current of the high voltage generation circuit 1 has been used. However, when the high-voltage generation circuit 1 is controlled by feeding back the high-voltage fluctuation information, the secondary-side current information of the high-voltage generation circuit 1 has a phase delay due to the high-voltage fluctuation of the anode electrode position of the CRT 2. Therefore, even if the potential on the negative electrode side of the capacitance element 4 is modulated by the capacitance element modulation circuit 6 based on the secondary side current information of the high voltage generation circuit 1, it is difficult to obtain the optimum high voltage stability. Not only that, if the phase delay further increases, there is a problem that the high-pressure stability is impaired.
[0032]
Therefore, in the present embodiment, the above-described problem is solved by using a high-voltage fluctuation detection circuit 9 and an amplification circuit 7 as shown in FIG. In FIG. 5, a voltage signal proportional to the high voltage fluctuation detected by the high voltage fluctuation detection circuit 9 constituted by resistance division of the resistance element is converted into a capacitance such that the high voltage stability is optimized by the potential on the negative electrode side of the capacitance element 4. In order to modulate by the element modulation circuit 6, the amplification circuit 7 amplifies the signal to an optimum amplitude, and uses the amplified signal to change the potential on the negative electrode side of the capacitance element 4 so that the high voltage stability is optimized. Modulate by 6.
[0033]
As shown in FIG. 5, by using the high-voltage fluctuation information for the signal that modulates the potential on the negative electrode side of the capacitance element 4 by the capacitance element modulation circuit 6 so that the high-voltage stability is optimized, the actual high-voltage fluctuation can be reduced. The phase relationship with the signal to be modulated is the same, and it is possible to further improve the high voltage stability with respect to the first and second configurations. In addition, it is possible to prevent an increase in power consumption by using a resistor having a very large resistance value so as not to greatly affect the load current of the high voltage generation circuit 1 as a resistance element used in the high voltage fluctuation detection circuit 9. it can.
[0034]
(Embodiment 5)
Next, an embodiment described in the ninth and tenth aspects will be described with reference to FIG. The same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted.
[0035]
In the first and second inventions, the capacitive element 3 and the capacitive element 4 are grounded, and a filter composed of the capacitive element 3, the coil 5, and the capacitive element 4 is used to further reduce high-voltage ripple. In the case of such a configuration, the voltage drop due to the current flowing from the high voltage generation circuit 1 to the coil 5 is very small, so that the high voltage stability is reduced and the image displayed on the display has a straight line. Degradation of image quality, such as the distorted display of expected images and the change in luminance on the screen resulting in uneven luminance on the display, making it impossible to faithfully reproduce the image signal source connected to the display. Cause.
[0036]
Therefore, in the seventh and eighth inventions, the method of modulating the potential on the negative electrode side of the capacitive element 4 by the capacitive element modulation circuit 6 based on the fluctuation of the high voltage is used. However, when a method of modulating the potential on the negative electrode side of the capacitive element 4 by the capacitive element modulation circuit 6 based on the fluctuation of the high voltage is used, a phase delay occurs between the input of the amplification circuit 7 and the output of the capacitance element modulation circuit 6. The signal that modulates the potential of the negative electrode of the capacitive element 4 has a phase lag due to the fluctuation of the high voltage at the anode position of the CRT 2, and the potential of the negative electrode of the capacitive element 4 is based on the fluctuation of the high voltage. However, it is difficult to obtain an optimum high-pressure stability even when the modulation is performed by the capacitive element modulation circuit 6, and the high-pressure stability is impaired if the phase delay increases.
[0037]
Therefore, in the present embodiment, the above problem is solved by using a cathode current detection circuit 10, an amplification circuit 7, and a delay circuit 11 of a CRT as shown in FIG. In FIG. 6, a voltage signal proportional to the cathode current of the CRT detected by the cathode current detection circuit 10 of the CRT is modulated by the capacitive element modulation circuit 6 so that the potential on the negative electrode side of the capacitive element 4 is optimized for high voltage stability. In order to make the phase of the signal supplied from the capacitive element modulation circuit 6 the same as the actual high-voltage fluctuation phase, the signal is delayed by a delay circuit 11 and the signal is amplified by the capacitive element. 4 is modulated by the capacitive element modulation circuit 6 so that the high voltage stability is optimized.
[0038]
As shown in FIG. 6, a signal for modulating the potential on the negative electrode side of the capacitive element 4 by the capacitive element modulation circuit 6 so that the high-voltage stability is optimized uses information on current flowing through the cathode of the CRT whose phase has been controlled. Thus, the actual fluctuation of the high voltage and the phase delay of the signal to be modulated are eliminated, and the high voltage stability can be further improved compared to the conventional method.
[0039]
【The invention's effect】
As described above, according to the high-voltage supply circuit of the present invention, by configuring a filter circuit using a coil, a voltage drop caused by the resistance element in a conventional high-voltage supply circuit including a filter circuit using a resistance element is achieved. Accordingly, the high-pressure stability is reduced, the problem that the high-voltage ripple cannot be completely reduced is solved, and the increase in power consumption can be easily suppressed.
[0040]
In the high-voltage supply circuit of the present invention, a high-stability high-voltage supply can be realized by modulating the potential on the negative electrode side of the capacitive element based on the current flowing on the secondary side of the high-voltage generation circuit.
[0041]
Further, the potential of the negative electrode of the capacitor is modulated based on the fluctuation of the high voltage. This makes it possible to realize a high-pressure supply with higher stability.
[0042]
Further, by modulating the potential on the negative electrode side of the capacitive element based on the current flowing to the cathode of the CRT, it is possible to realize high-stability high-voltage supply.
[Brief description of the drawings]
1 is a block diagram of a high-voltage supply circuit according to a first embodiment of the present invention; FIG. 2 is a block diagram of a high-voltage supply circuit according to a second embodiment of the present invention; FIG. 4 is a block diagram of a high-voltage supply circuit according to a third embodiment of the present invention. FIG. 5 is a block diagram of a high-voltage supply circuit according to a fourth embodiment of the present invention. FIG. 7 is a block diagram of a high voltage supply circuit according to a fifth embodiment of the present invention. FIG. 7 is a block diagram of a conventional high voltage supply circuit.
1 High voltage generation circuit 2 CRT
3, 4 Capacitance element 5 Coil 6 Capacitive element modulation circuit 7 Amplification circuit 8 Secondary side current detection circuit 9 High voltage fluctuation detection circuit 10 Cathode current detection circuit 11 Delay circuit 12 Resistance element

Claims (4)

A high voltage generation circuit for generating a high voltage (hereinafter, referred to as a high voltage) to be supplied to the anode electrode of the CRT ;
A filter connected to a high-voltage output of the high-voltage generation circuit, having the output as an input, being input to one end of a coil and being connected to a capacitive element at the other end, and having the other end as an output;
A capacitive element modulation circuit connected to one of the two terminals of the capacitive element that is not connected to the coil;
With
The capacitance element modulation circuit detects an output fluctuation signal of the high voltage generation circuit, and modulates one of the two terminals of the capacitance element that is not connected to the coil by an inverted signal obtained by inverting the signal. High-voltage supply circuit characterized. A secondary-side current detection circuit that detects a current flowing to the secondary side of the high-voltage generation circuit,
An amplifier circuit for amplifying the current detected by the secondary-side current detection circuit,
Further comprising
Characterized by modulating the potential of one terminal that is not connected to the coil of the second terminal of the capacitive element receiving the output of the amplifier circuit to the capacitive element modulation circuit as an output variation of said high voltage generating circuit The high-voltage supply circuit according to claim 1 . A high-voltage fluctuation detection circuit for detecting fluctuations in the high-voltage output of the high-voltage generation circuit ,
An amplification circuit having a detection signal detected by the high-voltage fluctuation detection circuit as an input,
Further comprising
Characterized by modulating the potential of one terminal that is not connected to the coil of the second terminal of the capacitive element receiving the output of the amplifier circuit to the capacitive element modulation circuit as an output variation of said high voltage generating circuit The high-voltage supply circuit according to claim 1 . A cathode current detection circuit for detecting a current flowing to the cathode of the CRT,
An amplifier circuit to which a signal detected by the cathode current detection circuit is input,
A delay circuit having an output of the amplification circuit as an input,
Further comprising
Characterized by modulating the potential of one terminal that is not connected to the coil of the second terminal of the capacitive element is input to the capacitance element modulation circuit the output of the delay circuit as the output variation of the high voltage generating circuit The high-voltage supply circuit according to claim 1 .

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