JPH0463066A - Horizontal linearity correcting circuit - Google Patents

Abstract

PURPOSE:To sufficiently correct the horizontal linearity regardless of the somewhat bad high frequency characteristic of an amplifier by providing a parallel resonance circuit on the output side of a low-output impedance amplifier and supplying a correcting current to a horizontal linearity correcting coil. CONSTITUTION:A parallel resonance circuit 4 consists of a coil L, a capacitor C, and a resistance (r), and its output is supplied to an auxiliary deflecting coil 6 provided with a cathode-ray tube 5 (indextron) for the purpose of correcting the horizontal linearity. A correction signal is outputted by a correction signal generating circuit 2 which detects the frequency variance of a PLL circuit 1, and this signal is supplied to an amplifier 3. A fly-back pulse generated at the start point of electron beam scanning is induced in the deflecting coil 6 by a horizontal deflecting yoke, and this induced signal is emphasized by the resonance circuit 4 to output a signal shown by efp. This signal efp interpolates signal components left uncorrected, and as the result. error of the horizontal linearity is resolved as shown in E.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a circuit for correcting the horizontal linearity of a cathode ray tube, and particularly relates to a horizontal linearity correction circuit useful for correcting the horizontal linearity of an indextron. be.

[Prior Art] In cathode ray tubes used in indextrons and projectors, it has been proposed to provide an auxiliary deflection yoke in addition to the main deflection yoke to correct horizontal deflection linearity.

(Unexamined Japanese Patent Publication No. 111588/1988) [Problems to be Solved by the Invention] The horizontal deflection linearity described above is achieved by scanning the electron beam in the horizontal direction by passing a sawtooth wave through the main deflection yoke, and at the same time scanning the electron beam in the horizontal direction. This is an attempt to eliminate horizontal linearity distortion by supplying a correction current to the deflection yoke, but especially when using an indextron in a cathode ray tube, if this horizontal linearity correction is insufficient, color shift may occur. It causes

In particular, when using the indextron as a computer display device, horizontal deflection is performed using a sawtooth wave signal as shown in Figure 3(a) to minimize overscanning of the monitor screen. In this case, there is a problem in that the deterioration of linearity increases at the left end of the screen.

Therefore, as shown in Fig. 3(b), a correction signal that increases the horizontal deflection speed at the left and right edges of the screen is supplied via an amplifier. If the slew rate is not high, there is a problem that a correction current flows as shown in FIG. 2(c), resulting in insufficient correction.

[Means for Solving the Problems] The present invention has been made to solve these problems. Insert a parallel resonant circuit.

[Operation] The parallel resonant circuit resonates due to the flyback pulse induced in the auxiliary deflection yoke, which is slightly electromagnetically coupled to the main deflection yoke, so that the uncorrected portion of the correction current is interpolated, and the auxiliary deflection yoke receives sufficient current. A correction current can be supplied.

[Embodiment] Fig. 1 shows a circuit diagram of the horizontal linearity correction device of the present invention, in which 1 is a PLL circuit to which an index signal is supplied, and 2 is a control gfJ error or oscillation of this PLL circuit 1. A correction signal generation circuit detects frequency fluctuations and converts horizontal linearity deviation into a correction signal, and 3 is a low output impedance amplifier for amplifying the correction signal and supplying it to the auxiliary deflection yoke.

Reference numeral 4 indicates a parallel resonant circuit formed by a coil L, a capacitor C1, and a resistor r, the output of which is supplied to an auxiliary deflection coil 6 provided in the cathode ray tube 5 in order to correct horizontal linearity.

Note that 7 indicates a horizontal deflection coil forming the main deflection yoke, and this horizontal deflection coil 7 and the auxiliary deflection coil 6 are
- They are located radially adjacent to each other.

The operation of the present invention will be explained below with reference to FIG.

The index signal obtained when the indextron is scanned in the horizontal direction is a pulse signal with a substantially constant period when horizontal linearity is maintained, and the correction signal generation circuit 2 does not output a correction signal.

However, as mentioned above, if the indextron is operated in a manner that does not overscan the display surface,
-M, as shown by EC in FIG. 2, an error signal is output that causes the running speed to drop significantly at the left-hand starting edge of the screen, and a correction signal that rises rapidly at this portion is required.

This correction signal is output by the correction signal generation circuit 2 that detects the frequency fluctuation of the PLL circuit 1, and is supplied to the amplifier 3. However, the amplifier 3 generally outputs high-frequency signal components depending on its frequency characteristics. Therefore, the output response signal (with limited slew rate) changes as shown by the dotted line, and the uncorrected signal component (
horizontal nonarity error) occurs.

However, in the case of the present invention, the flyback pulse generated at the start point where the electron beam is scanned by the horizontal deflection yoke is induced into the auxiliary deflection coil, and this induced signal is emphasized by the resonant circuit 4, and the same figure erp
Outputs the signal shown in . This signal erp interpolates the signal component left behind in the correction, and as a result, the horizontal linearity error is eliminated as shown in FIG.

Each impedance value of the parallel resonant circuit 4 is, for example, L
= 47uH, C = 1800pF, r = 10
It is preferable that the resistance is 0Ω, and the resonance Q thereof is approximately 1.

Note that the horizontal linearity correction circuit of the present invention is not limited to indextrons, but can also be applied to ordinary scanning cathode ray tubes.

[Effects of the Invention] As explained above, the horizontal linearity correction circuit of the present invention is configured such that a parallel resonant circuit is provided on the output side of the low output impedance amplifier and a correction current is supplied to the horizontal linearity correction coil. As a result, even if the high frequency characteristics of the amplifier are somewhat poor, horizontal linearity correction can be performed sufficiently.In particular, it has the advantage of being able to eliminate color shifts that tend to occur at the start of horizontal raster scans. be.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the horizontal linearity correction circuit of the present invention, FIG. 2 is a waveform diagram for explaining the operation of FIG. 1, and FIG. 3 is a horizontal linearity correction signal waveform diagram. In the figure, 2 is a correction signal generation circuit, 3 is a low output impedance amplifier, 4 is a parallel resonant circuit, 6 is an auxiliary deflection coil, and 7
indicates a horizontal deflection coil.

Claims (1)

[Claims] A horizontal linearity correction signal is supplied to a supplementary deflection device adjacent to the horizontal deflection device mounted on the cathode ray tube via a low impedance output amplifier and a parallel resonant circuit connected to the output of the amplifier. A horizontal linearity correction circuit characterized by: