JPS59221170A - Circuit for correcting distortion in horizontal deflection linearity - Google Patents

Abstract

PURPOSE:To obtain a correcting circuit for horizontal deflection linearity distortion with less number of components by using two variable inductances with magnetic bias connected in series and opposite polarity as coils for correcting linearity distortion connected in series with a horizontal deflection coil. CONSTITUTION:The horizontal deflection linearity distortion correcting coils Lc1, Lc2 connected in series and opposite polarity are connected in series with the horizontal deflection coil LY. Since the coils are connected with opposite polarity, the linearity at the first half of the horizontal deflection is conducted by the coil Lc1 and the correction at the latter half is performed by the coil Lc2. The correction including the correction of S-shape distortion on demand in this case is conducted independently for the first and latter halves of the deflection. A bias magnetic field is given to the coils Lc1, Lc2 by means of a permanent magnet.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a horizontal deflection linearity distortion correction circuit that can extremely easily adjust the linearity of horizontal deflection.

(2) Conventional technology and problems In cathode ray tubes used in conventional television receivers, the electron flow emitted from the cathode to the phosphor film is horizontal and horizontal on the phosphor surface.
Most often, a deflection coil is used for vertical deflection. A positive pulse is applied to the terminal of the horizontal output transistor TR to turn it on, and a current that increases linearly with time flows through the deflection coil Ly. (The state at time TI in the current waveform diagram shown in Figure 2.) At this time, the capacitor Cs (capacitance value is 1
~10-odd μF) acts as a direct current blocker and is charged from the power source E via the choke coil Lo, so it essentially operates as a direct current power source for the deflection coil Ly. At the same time, as described later, Cs resonates in series with the deflection coil Ly.
It plays the role of correcting character distortion.

Due to the increasing current of the deflection coil Ly, the electron current is scanned from one end of the fluorescent surface in the horizontal direction to the other end (time T2 in Fig. 2).
. Therefore, when a negative pulse is applied to the transistor TR to turn it off, the current flowing through the deflection coil continues to flow in the same direction due to the inertia of the inductance, and although the current value decreases, it starts charging the capacitor C. The voltage across capacitor C increases due to the resonance phenomenon. When the current in the deflection coil becomes zero (time T3 in Figure 2), the voltage in the resonant capacitor C reaches its maximum value, and then the current in the deflection coil starts to flow in the opposite direction, and the voltage in the capacitor C reaches its minimum value, and the voltage in the resonant capacitor C reaches its maximum value. The direction current reaches its maximum (time T4 in FIG. 2), at which time the damper diode D conducts due to the back electromotive force of the deflection coil, and the current flows in the same direction and approaches zero. When it becomes zero, time T5 in Figure 2
is the state one cycle after time Tl. Here, Figure 2 shows an ideal state, but in reality, it is a waveform diagram of the current flowing through the deflection coil due to factors such as the resistance of the deflection coil Ly, the saturation resistance of the output transistor TR, and the nonlinearity of the damper diode D. is distorted as shown in FIG. 3A1. FIG. 3B is a corresponding diagram showing horizontal deflection linearity distortion. The S-shaped distortion correction capacitor Cs is connected to the deflection coil Ly.
This produces series resonance with the deflection current, and causes an S-shaped current to flow superimposed on the deflection current, thereby improving horizontal deflection linearity. When the figure 5 correction capacitor Cs is large, the deflection coil current is A2 in FIG. 3, and the linearity is B2 in FIG. 3, and when Cs is small, the current is A3 in FIG.
It becomes B3. and horizontal deflection linearity distortion correction coil L c
It has also been proposed to further connect Cs in series and change the slope of the deflection current in the first half of scanning to perform correction from the broken line to the solid line shown in FIG. 3 A4.

However, when extremely good horizontal deflection linearity is required for cathode ray tube display devices such as display devices,
Simultaneously adjusting both the correction coil Lc and the correction capacitor C3 to the best condition is complicated and extremely troublesome because the adjustment of one element changes the linearity as a whole. In particular, it has been difficult to finely adjust the value of the capacitor Cs as described above.

(3) Object of the Invention An object of the present invention is to provide a horizontal deflection linearity distortion correction circuit that can improve the above-mentioned drawbacks, reduce the number of parts used, and easily adjust the horizontal deflection linearity.

(4) Structure of the Invention The structure of the present invention to achieve the above-mentioned object is to provide a horizontal deflection system in which a deflection coil for horizontally deflecting the electron flow of a cathode ray tube and a linearity distortion correction coil are connected in series. In the linearity distortion correction circuit, two variable inductances magnetically biased by permanent magnets are connected in series with opposite polarities and used as the correction coil.

(5) Embodiment of the invention FIG. 4 is a circuit diagram showing an embodiment of the invention. The same reference numerals as in FIG. 1 indicate similar parts.

Lcl and Lc2 each indicate horizontal deflection linearity distortion correction coils, which are connected in series with opposite polarities. In other words, considering the magnet that provides the bias magnetic field and the coil winding direction for a coil wound around a ferrite magnetic core, when a DC current is passed in the same direction through both coil crowns, what happens? The coils are divided into coils in which a change in inductance with respect to a change of 1fffi occurs for a positive direction current, and coils for a negative direction current.

Therefore, for example, GJ linearity correction in the first half of horizontal deflection can be performed by Lcl, and linearity correction in the latter half can be performed by Lc2. Corrections including the three-character distortion correction required at this time can be performed independently of each other before and after the deflection. To further explain the operation of the horizontal deflection linearity distortion correction coil, when the coil is wound around a ferrite magnetic core, the change in magnetic flux density 2B with respect to the change in magnetic field T is as follows:
A hysteresis curve is drawn as shown in FIG.

When a permanent magnet is added to provide a bias magnetic field with a value of H, the B-H curve becomes as shown in FIG. 5B.

The relationship between the magnetic field H and the magnetic permeability μ is as shown in FIG. If it is made to correspond to changes in inductance L and current (2), the result will be as shown in the fifth diagram. That is, a horizontal deflection linearity distortion correction coil in which the inductance L changes with respect to a change in the negative direction current is obtained.

(6) Effects of the Invention As described above, according to the present invention, the first half and the second half of deflection can be corrected independently without using a capacitor as a figure-8 distortion correction element, making adjustment work extremely easy. Furthermore, since a figure-8 distortion correction capacitor is not used, the deflection coil can be directly connected to the power supply, and a power supply choke coil is also unnecessary. Since the number of circuit elements is reduced, circuit loss is reduced and operating efficiency is increased.

[Brief explanation of drawings]

Fig. 1 is a circuit configuration diagram showing a conventional horizontal deflection linearity distortion correction circuit, Fig. 2 is an ideal operating waveform diagram of Fig. 1, and Fig. 3 is for explaining the linearity distortion correction operation of Fig. 1. FIG. 4 is a circuit configuration diagram showing an embodiment of the present invention, and FIG. 5 is an explanatory diagram of the operation of the linear distortion correction coil in FIG. 4. TR - Horizontal output transistor Ly - Deflection coil C - Resonant capacitor Lc, Lcl
, Lc2 - Horizontal deflection linearity distortion correction coil D - Damper diode Patent applicant: Fujitsu Limited Agent Patent attorney: Edited by Eisuke Suzuki - Figure 2 2 2 3 4 Section 4 Figure 5

Claims (1)

[Claims] In a horizontal deflection linearity distortion correction circuit in which a deflection coil for horizontally deflecting the electron flow of a cathode ray tube and a linearity distortion correction coil are connected in series, the correction coil is a variable voltage biased magnetically by a permanent magnet. inductance 2
1. A horizontal deflection linearity distortion correction circuit characterized in that two circuits are connected in series with opposite polarities.