JPH09191413A - Horizontal deflection circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the contraction of a right end on a screen, which is accompanied by the increase of deflection current. SOLUTION: A screen right end distortion correction means 100 constituted by a choke coil 10, a capacitor 11 and FET 12, which are in parallel to an S-shaped correction capacitor 6, is inserted. FET 12 is conducted only in a period from the start of the storage time of a horizontal output transistor 1 to time when a feedback period terminates. During that time, resonance current by means of the choke coil 10 and the capacitor 11 is made to flow.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal deflection circuit such as a television receiver or a terminal display monitor.

[0002]

2. Description of the Related Art FIG. 3 is a circuit diagram showing a configuration of a conventional horizontal deflection circuit. In this figure, a switching current of the horizontal output transistor 1 causes a sawtooth-shaped deflection current to be generated from the damper diode 2 and the capacitor 3, and is supplied to the deflection coil 4. A linearity coil 5 and an S-shaped correction capacitor 6 are inserted in series in the deflection coil 4 to improve the linearity of the deflection current. By the way, recently, the deflection current has been increasing with the increase in size of the image receiver and the increasing deflection frequency. However, as shown in FIG. During the period of about 1 μs, the linearity of the deflection current is deteriorated due to the characteristics of the horizontal output transistor 1 and the like, and the phenomenon that the right end of the screen is locally contracted is becoming remarkable. This phenomenon cannot be improved by the linearity coil 5 and the S-shaped correction capacitor 6.

Therefore, as shown in FIG. 3, a choke coil 8 and a capacitor 9 are inserted in series at both ends of the S-shaped correction capacitor 6 to further improve the linearity. The correction by the choke coil 8 and the capacitor 9 is called M-shaped correction. In the M-shaped correction, as shown in FIG. 5, a resonance current that is about twice as large as the deflection current is passed through the deflection coil 4 to make the picture tube wider and flatter as the receiver becomes larger. Improves linearity deviation.

[0004]

However, such a conventional M-shaped correction has the following problems. (A) There is only a slight improvement in the local shrinkage at the right end of the screen, and if the design is performed by focusing on this shrinkage and determining a constant, good M-shaped correction cannot be obtained. (B) Since the deflection frequency changes in a horizontal deflection circuit compatible with multi-scan, the value of the choke coil 8 or the capacitor 9 must be changed according to the deflection frequency in order to obtain an appropriate correction.

Therefore, an object of the present invention is to provide a horizontal deflection circuit capable of improving the contraction of the right end of the screen due to an increase in deflection current.

[0006]

According to a first aspect of the present invention, a horizontal output transistor; a damper diode and a capacitor for generating a sawtooth-shaped deflection current by the switching operation of the horizontal output transistor; An S-shaped correction capacitor; a screen right end distortion correction means including a switching element, a choke coil, and a capacitor inserted in parallel with the S-shaped correction capacitor; And a control means for controlling conduction for a period corresponding to the portion immediately before the line period. According to this configuration, the switching element conducts only during the period immediately before the blanking period of the deflection current, and the resonance current due to the choke coil and the capacitor connected in series with the switching element flows during that period. Therefore, since the linearity of the deflection current immediately before the blanking period is improved, the right edge of the screen hardly shrinks even when the deflection current is increased.

According to the second aspect of the present invention, the switching element is made conductive only during the period from the start of the storage time of the horizontal output transistor to the end of the blanking period. Therefore, since the linearity of the deflection current in this period is improved, even if the deflection current is increased similarly to the above, the shrinkage of the right end of the screen hardly occurs. The invention of claim 3 uses an FET as a switching element.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the horizontal deflection circuit of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment of a horizontal deflection circuit according to the present invention. In this figure, the same parts as those in FIG. 3 described above are designated by the same reference numerals and the description thereof will be omitted. In this figure, a series circuit of a choke coil 10, a capacitor 11 and a FET (field effect transistor) 12 is inserted in parallel with an S-shaped correction capacitor 6 connected in series with the deflection coil 4. In this case, the source S of the FET 12
Is connected to the capacitor 11 and the drain D is grounded. The gate G is connected to the control circuit 13, and the control circuit 13 controls ON / OFF.

The control circuit 13 controls to turn on the horizontal output transistor 1 for each period of the deflection current Iy only for the period from the start of the storage time to the end of the blanking period. Choke coil 10 and capacitor 1
1 indicates that the period of the resonance frequency due to these is EFT1.
A value of about 2 is selected. Choke coil 10, capacitor 11 and FET
Reference numeral 12 constitutes the screen right end distortion correction means 100, and the control circuit 13 corresponds to the control means. Here, FIG. 2 is an operation waveform diagram of each part, the resonant current i _d flows by the choke coil 10 and a capacitor 11 to the ON period of FET12 as shown in this figure, the resonant current i _d, deflection current Iy The linearity is improved for a period of about 1 μs immediately before the blanking period. The resonance current i _d flows in each cycle of the deflection current Iy.

As described above, the FET 12 is set to be turned on only during the period from the start of the storage time to the end of the retrace line period, so that the horizontal output transistor 1 of the horizontal output transistor 1 can be operated even when the deflection frequency changes. As long as the storage time does not change significantly, it is not necessary to change the values of the choke coil 10 and the capacitor 11 so that the resonance frequency corresponds to the deflection frequency. By setting the ON period of the FET 12 as shown by the broken line in FIG. 2, M-shaped correction can be obtained at the same time.

As described above, in this embodiment, the distortion correction means 100 at the right end of the screen, which is composed of the choke coil 10, the capacitor 11 and the FET 12, is inserted in parallel with the S-shaped correction capacitor 6, and the FET 12 is connected to the horizontal output transistor 1. It is made to conduct only during the period from the start of the storage time to the end of the blanking period, during which a resonance current due to the choke coil 10 and the capacitor 11 is made to flow. As a result, about 1 μ immediately before the blanking period of the deflection current Iy
Since the linearity in the period of about s is improved, the deflection current Iy
Even if is increased, the shrinkage of the right end of the screen hardly occurs. In the above embodiment, the FET 1 is used as the switching element.
Although 2 is used, a transistor or the like may be used.

[0012]

According to the inventions of claims 1, 2 and 3,
A distortion correction means at the right end of the screen including a choke coil, a capacitor, and a switching element is inserted in parallel with the S-shaped correction capacitor, and the switching element is connected from the start of the storage time of the horizontal output transistor to the end of the blanking period. Since the resonance current due to the choke coil and the capacitor is made to flow during that period and the resonance current is caused to flow during that period, the linearity of the deflection current for a period of about 1 μs immediately before the blanking period can be improved. It is possible to improve the shrinkage at the right end of the screen due to the increase. Also, as long as the storage time of the horizontal output transistor does not change significantly even if the deflection frequency changes, it is not necessary to change the values of the choke coil and the capacitor to make the resonance frequency correspond to the deflection frequency. Even if it is used, optimum correction is possible.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a horizontal deflection circuit according to the present invention.

FIG. 2 is an operation waveform diagram of the horizontal deflection circuit of the embodiment.

FIG. 3 is a circuit diagram showing a conventional horizontal deflection circuit.

FIG. 4 is a waveform diagram showing a deflection current in a conventional horizontal deflection circuit.

FIG. 5 is a waveform diagram for explaining M-shaped correction in a conventional horizontal deflection circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Horizontal output transistor 2 Damper diode 3 and 11 Capacitor 4 Deflection coil 5 Linearity coil 6 S-shaped correction capacitor 10 Choke coil 12 FET 13 Control circuit 100 Distortion correction means at the right end of the screen

Claims (3)

[Claims] 1. A horizontal output transistor; a damper diode and a capacitor for generating a sawtooth deflection current by a switching operation of the horizontal output transistor;
An S-shaped correction capacitor inserted in series with the deflection coil;
A screen right end distortion correction means including a switching element, a choke coil, and a capacitor inserted in parallel with the S-shaped correction capacitor; and a switching element of the screen right end distortion correction means corresponding to a portion immediately before the blanking period of the deflection current. A horizontal deflection circuit, comprising: a control means for controlling conduction for only a period. 2. The horizontal deflection circuit according to claim 1, wherein the control means conducts the switching element for a period from the start of the storage time of the horizontal output transistor to the end of the blanking period. . 3. The horizontal deflection circuit according to claim 1, wherein the switching element is a FET.