JPH0744131Y2 - Focus pack circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a focus pack circuit connected to the secondary side of a flyback transformer for driving a cathode ray tube and performing focus adjustment and the like.

[Conventional technology]

Television receivers and display devices are equipped with a flyback transformer that boosts the flyback pulse and adds the boosted output to the anode of the cathode ray tube.The secondary side of this flyback transformer is the screen of the cathode ray tube. A focus pack circuit that performs focus adjustment and the like is provided.

FIG. 2 shows a conventional general focus pack circuit. In the figure, a high-voltage output voltage is applied from the high-voltage end side of the high-voltage coil 1 of the flyback transformer to the anode side of a cathode ray tube (not shown) via a high-voltage rectifier diode 2. The focus pack circuit 3 is connected to the side. The focus pack circuit 3 includes a drop resistor 4 that drops a high-voltage output voltage, a double focus circuit 5 connected to the output end side of the drop resistor 4, and an output end side of the double focus circuit 5 sequentially connected in series. Connected screen voltage adjusting resistor 6 and high output voltage detecting resistor 7
Consists of. The double focus circuit 5 includes a first variable resistor 8 for adjusting a horizontal focus of a screen of a cathode ray tube (hereinafter referred to as a TV screen) and a second variable resistor 10 for adjusting a vertical focus of the TV screen. And are connected in parallel, and the dynamic capacitor 11 is connected to the voltage extracting terminal side of the first variable resistor 8. A parabolic waveform voltage is applied to the input terminal 15 of the dynamic capacitor 11 to suppress the voltage fluctuation on the horizontal scanning line and correct the distortion on the television screen. The detection resistor 7 detects the high voltage output voltage dropped by the drop resistor 4 and feeds back this detection voltage to an appropriate signal processing circuit.

According to the above-mentioned conventional circuit, the double focus circuit 5 adjusts the focus in the horizontal and vertical directions of the television screen, and the voltage variation on the horizontal scanning line is corrected by the voltage of the parabolic waveform applied to the dynamic capacitor 11. Then, desired control such as stabilization of the high voltage output voltage is performed based on the detected voltage taken out from the detection resistor 7.

However, in this conventional circuit, the dynamic capacitor
Since the voltage of the parabolic waveform applied to 11 appears on the detection resistor 7 side through the first variable resistor 8, there is a problem that this parabolic waveform voltage component is detected by the detection resistor 7. There is a drawback in that control based on voltage cannot be performed accurately.

Recently, in order to eliminate this kind of inconvenience, as shown by the chain line in FIG. 2, resistors 12 and 13 are connected in series to form a detection resistor 7. The one whose one end side is directly connected to the high voltage end of the high voltage coil 1 is used as an improved circuit of the focus pack circuit.

Usually, this type of focus pack circuit is formed on a ceramic substrate by printing or the like. However, if the whole of this improved focus pack circuit is printed on one ceramic substrate, the area of the ceramic substrate becomes very large. It becomes large and the following inconveniences occur. That is, as is well known, the ceramic substrate is superior in electrical characteristics when it is thin, but when the area becomes large, the thickness of the ceramic substrate must be increased from the viewpoint of mechanical strength. However, there arises a problem that the electric characteristics are deteriorated. In order to solve such a problem, in the improved focus pack circuit, the detection resistor 7 composed of the resistors 12 and 13 is formed by printing on one ceramic substrate and the second ceramic substrate is formed. The double focus circuit 5 and the resistors 6 and 7 are formed by printing, and the drop resistor 4 is formed on the third ceramic substrate by printing.
The focus pack circuit was formed using a single ceramic substrate.

[Problems to be solved by the device]

However, the improved focus pack circuit described above has a problem in that three ceramic substrates have to be prepared, and moreover, the circuit must be printed on each of the three substrates. There was a problem of inefficiency.

The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to provide a focus pack circuit capable of efficiently forming a circuit on a thin ceramic substrate of a smaller number by printing. is there.

[Means for Solving the Problems]

The present invention is configured as follows to achieve the above object. That is, the present invention is directed to a drop resistor that lowers the high-voltage output voltage on the secondary side of the flyback transformer, and a detection resistor that detects the high-voltage output voltage stepped down by the drop resistor and outputs the detected voltage as a feedback voltage. And a double variable focus circuit of a resistance parallel circuit in which a first variable resistor that outputs a horizontal focus voltage and a second variable resistor that outputs a vertical focus voltage are connected in parallel. In a focus pack circuit in which a dynamic capacitor for parabolic waveform input is provided on the horizontal focus voltage extraction side of the first variable resistor, the detection resistor and the double focus circuit are provided on the output end side of the drop resistor. And a parallel circuit is connected, and the drop resistor and the detection resistor are common one sheet. Tsu are printed on the click board, double focus circuit is configured as characterized by being printed on the other one of the ceramic substrate.

[Action]

In the present invention, the high voltage output voltage is dropped by the drop resistor. Then, the dropped high voltage output voltage is applied to a parallel circuit of the double focus circuit and the detection resistor, and the detection voltage of the high voltage output voltage is taken out from the detection resistor. When detecting the detection voltage, even if a parabolic waveform voltage is applied to the dynamic capacitor of the double focus circuit, this parabolic voltage does not appear on the detection resistor side, and an accurate high-voltage output voltage that is not affected by the parabolic voltage is generated. It will be detected by the detection resistor.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In the description of the present embodiment, the same parts as those of the conventional circuit are designated by the same reference numerals, and the duplicated description will be omitted.

FIG. 1 shows an embodiment of the focus pack circuit according to the present invention. The characteristic of this embodiment is that
By connecting the double focus circuit 5 and the detection resistor 7 formed by the series connection of the resistors 12 'and 13' in parallel, and connecting this parallel connection to the output end side of the drop resistor 14, is there. Generally, as can be seen from the improved focus pack circuit shown in FIG. 2 of the related art, the high voltage output voltage is detected after being dropped by the resistor 12, and is also added to the double focus circuit 5. The high voltage output voltage is applied after being dropped by the drop resistor 4. In the present embodiment, the conventional second
The function of the resistor 12 and the drop resistor 4 shown in the figure is shared by one drop resistor 14. Then, in the present embodiment, the drop resistor 14 and the detection resistor 7 are printed on one ceramic substrate by printing, and the double focus circuit 5 is printed.
The screen voltage adjusting resistor 6 and the resistor 9 are formed by printing on another ceramic substrate. In this way, even if the detection resistor 7 and the drop resistor 14 are formed by printing on the same ceramic substrate, the area of the ceramic substrate does not become so large, and therefore these drop resistors are formed on the thin ceramic substrate. The body 14 and the detection resistor 7 can be formed. As described above, in this embodiment, the focus pack circuit can be formed on two thin ceramic substrates, and the number of ceramic substrates can be reduced by one compared with the conventional improved focus pack circuit. You can make a profit.

Also, by reducing the number of ceramic substrates by one, the efficiency of circuit printing can be increased accordingly.

Further, in this embodiment, since the double focus circuit 5 and the detection resistor 7 are connected in parallel, the resistance value of the resistor 12 'can be increased. Therefore, even if the parabolic waveform correction voltage is applied from the input terminal 15 of the dynamic capacitor 11, this correction voltage is applied to the resistor 1
The correction voltage is blocked by 2'and is not applied to the detection terminal of the detection resistor 7, whereby the high voltage output voltage can be accurately detected without being affected by the parabolic waveform voltage.

It should be noted that the present invention is not limited to the above-mentioned embodiment, and various modes of implementation can be adopted. For example, in the above-mentioned embodiment, the detection resistor 7 is constituted by the series connection body of the resistance bodies 12 'and 13', but the number of the resistance bodies connected in series can be arbitrarily determined.

In the above embodiment, the first focus of the double focus circuit 5 is
A resistor 16 is connected to the variable resistor 8 and the second variable resistor 10 of FIG. 1, but the number of the resistor 16 is arbitrary, and the resistor 16 can be omitted if necessary. Is.

[Effect of device]

Since the present invention is configured as described above, the focus pack circuit can be formed by printing on two thin ceramic substrates, which is one in comparison with the conventional three ceramic substrates required. By omitting one ceramic substrate, it is possible to simplify the circuit configuration and improve the efficiency of circuit printing. Further, by forming the focus pack circuit on the two ceramic substrates, it is possible to avoid an increase in the size and thickness of the substrate that would occur when forming the focus pack circuit on one ceramic substrate, and to reduce the thickness of the substrate.
The electrical characteristics can be improved.

Also, since the double focus circuit and the detection resistor are connected in parallel, it is possible to increase the resistance value on the detection resistor side, which allows the voltage of the parabolic waveform applied to the dynamic capacitor side to be detected. It is possible to prevent the high voltage output voltage from appearing at the detection terminal of, and this makes it possible to accurately detect the high voltage output voltage without being affected by the parabolic waveform voltage. Using this detection voltage (feedback voltage), It is possible to accurately perform desired control such as stabilization.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a focus pack circuit according to the present invention, and FIG. 2 is a circuit diagram of a conventional focus pack circuit. 1 ... High voltage coil, 2 ... High voltage rectifier diode, 3 ...
Focus pack circuit, 4 ... Drop resistor, 5 ...
Double focus circuit, 6 ... Screen voltage adjusting resistor, 7 ... Detection resistor, 8 ... First variable resistor, 9 ...
… Resistor, 10 …… Second variable resistor, 11 …… Dynamic capacitor, 12,12 ′, 13,13 ′ …… Resistor, 14 …… Drop resistor, 15 …… Input end, 16 …… Resistor.

Claims (1)

[Scope of utility model registration request] 1. A drop resistor for dropping a high-voltage output voltage on the secondary side of a flyback transformer, and a detection resistor for detecting a high-voltage output voltage stepped down by the drop resistor and outputting the detected voltage as a feedback voltage. When,
A first variable resistor that outputs a horizontal focus voltage and a second variable resistor that outputs a vertical focus voltage; and a double-focus circuit of a resistance parallel circuit connected in parallel. In the focus pack circuit in which a dynamic capacitor for parabolic waveform input is provided on the horizontal focus voltage extraction side of the variable resistor of, the detection resistor and the double focus circuit are connected in parallel on the output end side of the drop resistor. When the circuit is connected, the drop resistor and the detection resistor are common 1
The focus pack circuit is formed by printing on one ceramic substrate, and the double focus circuit is formed by printing on another ceramic substrate.