JPS6342613Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of application of the invention] The invention relates to a focus voltage circuit in a television receiver, etc., and is particularly concerned with the focus voltage circuit in a television receiver, etc. The present invention relates to circuit means for realizing a so-called dynamic focus circuit for correcting changes in optimal focus voltage at low cost.

[Background of the idea]

FIG. 1 is a circuit diagram showing a conventional dynamic focus circuit. In the figure, 1 is a cathode ray tube, 2 is a high voltage electrode, 3 is a focus electrode, 4 is a capacitor, 5 is a correction voltage generation circuit, 6 is a horizontal deflection circuit, 7 is a beam current supply source, 8 is a flyback transformer, and 9 is a Variable resistor for focus adjustment, 1
0 is a variable resistor for adjusting the screen.

In FIG. 1, a horizontal synchronization parabow voltage (1A figure)
is superimposed on the focus voltage applied from the variable resistor 9 to the focus electrode 3 via the amplifier circuit capacitor 4 shown as the correction voltage generation circuit 5, and the focus voltage is modulated with horizontal synchronization as shown. is input to the focus electrode 3. In this example, a high voltage of several KV to 10 KV is applied to the capacitor 4 as the DC voltage of the focus electrode, so (1) the capacitor is expensive, and (2) there are mounting restrictions to ensure safety. The disadvantage was that there were many problems and the cost was high.

[Purpose of invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a focus voltage circuit that solves the drawbacks of the prior art and allows focus voltage correction to be realized at low cost.

[Summary of the idea]

In order to solve the above drawbacks of the conventional technology, the present invention eliminates the high voltage capacitor for applying correction voltage, uses a shielded wire instead, and uses the distributed capacitance between the core wire and the outer conductor for correction. The voltage is superimposed on the focus voltage.

[Example of idea]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a circuit diagram showing an embodiment of the present invention. In the figure, 11 is a shielded wire. FIG. 3 is a perspective view schematically showing the shield wire 11 in FIG. 2. In the same figure, 21 is a core wire;
22 is an insulating coating, 23 is a conductor on the outer covering side, and 24 is an outer covering.

Please refer to FIGS. 2 and 3.

The correction voltage from the correction voltage generation circuit 5 is connected to the outer conductor 23 of the shield wire 11, and the focus voltage is supplied from the focus adjustment variable resistor 9 to the focus electrode 3 via the core wire 21.

The impedance of the focus electrode 3 is determined by the variable resistors 9 and 10, but usually a high impedance of about several tens of MΩ is used, and the coupling capacitance between the outer conductor 23 and the core wire 21 is
By securing a capacity of 10PF, it is possible to superimpose the correction voltage on the focus voltage up to a sufficiently low frequency signal.

[Effect of idea]

As described above, the present invention has the advantage that focus correction voltage superimposition can be realized at low cost because a high-withstand voltage capacitor for applying correction voltage can be removed and an inexpensive shielded wire can be used instead. .

In this embodiment, an example of a correction circuit according to the horizontal position of the screen was described as a focus correction voltage, but it goes without saying that it can be used as a correction signal source for a beam current detection voltage, a video signal, and various other applications. Nor.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a conventional dynamic focus circuit, Fig. 1A is a waveform diagram of a horizontally periodic parabolic voltage generated across an S-shaped correction capacitor, and Fig. 2 shows an embodiment of the present invention. Circuit diagram, Figure 3 is the second
It is a perspective view of the shield wire 11 in a figure. Symbol explanation, 1... Braun tube, 2... High voltage electrode, 3
...Focus electrode, 4...Capacitor, 5...Correction voltage generation circuit, 6...Horizontal deflection circuit, 7...Beam current supply source, 8...Flyback transformer, 9...Focus adjustment VR, 10...Screen adjustment VR, 11
...shield wire, 21 ... core wire, 22 ... insulation coating, 2
3...Outer cover side conductor, 24...Outer cover.

Claims (1)

[Scope of utility model registration request] In a focus voltage circuit in a television receiver, etc., which supplies a focus voltage through the core side conductor of a shielded wire consisting of a core wire and an outer sheath, a focus correction voltage is supplied to the sheath side conductor,
1. A focus voltage circuit for a television receiver or the like, characterized in that the focus correction voltage is superimposed on the focus voltage via a coupling capacitance between a jacket and a core wire.