JPS6232790A - Convergence correcting circuit - Google Patents

Abstract

PURPOSE:To certainly realize each convergence correction of red, green and blue represented in R, G and B by correcting the difference between the center position of a mechanism and that of a distortion waveform in each CRT by passing each correcting waveform signal of a red and a blue through an integrated circuit or a differentiating circuit. CONSTITUTION:It is so constituted that a linear picture image can be obtained from the correcting waveform of a green vertical pincushion distortion, and regarding that of a red vertical pincushion distortion, it is offset with the waveform in which the red vertical pincushion distortion is observed with a time base through an integrated circuit 6. Also, regarding the waveform of a blue vertical pincushion distortion correction, so that it has a structural center position symmetrical to a red CRT, it so is constituted that the blue vertical pincushion distortion is offset on the time base by passing the output of a vertical pincushion distortion waveform generating circuit 5 through a differentiating circuit 7. Thereby, the convergence correction can be performed without fail.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a color television device, and particularly to a color television device that projects three primary color images and obtains a color image by superimposing the images on a screen surface. ” is related to parsence correction.

[Technical Background of the Invention 1 Several proposals have been made regarding convergence correction circuits in projection-type color television apparatuses in which a color image is obtained by projecting three primary color images onto a screen surface and superimposing them on the screen surface. ing. That is, as shown in FIG. 9, there is a means for correcting convergence distortion by superimposing various correction waveforms and driving a convergence yoke.

In the figure, reference numeral 1 denotes an input terminal for various convergence correction waveforms, into which signals such as skew correction waveforms, keystone correction waveforms, pincushion distortion correction waveforms, and linearity correction waveforms are input. 2 is a convergence yoke, which is also called an auxiliary deflection yoke or a sub-yoke, and is equipped for each R, G, and B CRT so that the three beams of light emitted from the three CRTs coincide with one point on the screen. It is being Further, the convergence yoke is divided into horizontal and vertical sections.

3 is a drive amplifier for the convergence yoke 2, and 4 is a synthesis circuit for the various correction waveforms.

Here, various waveform signals necessary for convergence correction are adjusted to necessary and appropriate levels and applied to the input terminal 1 to the synthesis circuit 4, and this synthesized waveform signal is sent to the drive amplifier 3.
The convergence yoke 2 is driven to deflect the electron beams of each CRT for convergence. still,
Functionally, the combining circuit 4, drive amplifier 3, and convergence yoke 2 require a total of six systems, since each of the three R, G, and B electron guns is provided with a horizontal and vertical convergence yoke 2.

This application particularly relates to improvements in vertical pincushion distortion, vertical bow distortion, and horizontal linearity, and the following will focus on these.

FIG. 8 shows an example of a convergence distortion correction circuit for vertical pincushion distortion (also called pincushion distortion).

5 is a vertical pincushion distortion correction waveform benshi circuit, which is composed of a circuit that synthesizes a parabolic wave obtained by modulating a horizontal deflection waveform with a vertical deflection waveform, which will be described later, and generates a waveform signal for correcting vertical pincushion distortion; 2 (VR)
, 2 (VG), 2 (V[3) are R, G, and B vertical convergence yokes, and 3 (VR), 3 (V
G), 3 (V[3)F is a drive amplifier that drives the vertical convergence yoke.

The operation of the circuit of this configuration will be described in detail below. Second
FIG. 2(a) shows the vertical deflection waveform, and FIG. 2(b) shows an enlarged view of a part of the vertical deflection waveform.

In what is called one horizontal scanning period, the scanning line is horizontally deflected right sideways, and the image of the horizontal line should become a straight line. However, in reality, due to pincushion distortion of the CRT or lens distortion, the horizontal line image on the screen becomes a curved line with pincushion distortion, as shown in FIG. 2(c).

Conventionally, when correcting this vertical pincushion distortion, Figure 3 (
A waveform signal in one horizontal scanning period shown in b) is generated and corrected. This waveform signal is generated by superimposing a parabolic current with a horizontal period proportional to the vertical deflection angle on the vertical deflection current using a saturable transformer (hereinafter referred to as a pincushion distortion correction transformer) or the like. Fig. 3(a) shows the main vertical deflection waveform for one vertical scanning period (1V), and Fig. 3(b) shows a part of the waveform with the time axis enlarged. 2, the horizontal line becomes a straight line on the screen as shown in FIG. 3(c). The principle of this straight line will be explained with reference to FIG. When one horizontal scanning period shown in Fig. 2(b) is scanned in a straight line, due to pincushion distortion of the CRT or lens distortion as described above, one horizontal scanning period as shown in Fig. 4(a) occurs. Assume that the image on the screen falls in a curved line at the center of the scanning period. Therefore, the vertical deflection waveform is set at the center of one horizontal scanning period, which is symmetrical to the image distortion, as shown in Figure 4 (b''). If you drive the convergence yoke as a waveform that rises at
) and (b) cancel each other out, and the final image becomes a straight line on the screen surface as shown in FIG. 4(c). In the conventional configuration, the vertical pincushion distortion correction waveform generating circuit 5 generates a waveform in which a parabolic current with a horizontal period proportional to the vertical deflection angle is superimposed on the vertical deflection current as shown in FIG. The three types of electron beams B were uniformly corrected and convergence correction for vertical pincushion distortion was performed.

[Problems with Background Art] Generally, a projection type color television apparatus has a configuration shown in FIG. 5(a), and the figure shows a horizontal plane. In this figure, CRTG is positioned and projected at a right angle to the screen surface, but CRTR,B is positioned and projected at a certain angle φ. Therefore, if the image produced by a CRTG that projects green light shows an image of equally spaced vertical lines as shown in Figure 5(b), the image produced by a CRTR that projects red light will look like the image shown in Figure 5(c). This results in an image with uneven spacing, resulting in an image with a deviation in linearity relative to green.

An image produced by a CRTB that projects blue light is also an image that is deviated from linearity. Conversely, if linearity correction is applied to the red light image on the screen and the convergence is combined with the green light image, the image on the CRT R screen will be in the opposite direction as shown in Figure 5(b). The quality is getting worse. The same applies to blue light. That is, on each CR1' tube surface, the image information at the time center of one horizontal scanning period for green corresponds to the mechanical center position on the projection surface of the CRTG, but the image information for one horizontal scanning period of red and blue corresponds to the mechanical center position on the projection surface of the CRTG. The image information at the time center of is present at a position shifted from the mechanical center position on the projection plane of CRTR and B.

Therefore, the above-mentioned vertical pincushion distortion will be explained.

The pincushion distortion caused by the CRT and the distortion of the optical lens are set so that the mechanical center position on the projection surface of the CRT points toward the center, and the mechanical center position of the optical lens points toward the center, so they tend toward both ends. The more symmetrically the distortion increases. Therefore, since the vertical pincushion distortion for green occurs in a curve centered on the temporal center of one horizontal scanning period (Fig. 4 (a)), it is corrected by the deflection waveform shown in Fig. 4 (b), which is symmetrical to this. Then, a distortion-free green image shown in FIG. 4(c) can be obtained. However, vertical pincushion distortion for red and blue occurs in a curve centered on the mechanical center position on the projection surface of CRTR,B, so for example, the distortion waveform when red pincushion distortion is viewed on the time axis is shown in Figure 6. (Even if the signal is corrected using a signal with a deflection waveform as shown in FIG. 6(b), which has a symmetrical deflection waveform as shown in ai, the screen surface with distortion as shown in FIG. 6(c) The image will be

The above description has been about vertical pincushion distortion correction, but vertical bow distortion correction, which is generally mountain-shaped, and horizontal linearity correction, as shown in Figure 5(c), have similar drawbacks and cannot be completely corrected. could not.

[Object of the Invention] The present invention was made in order to eliminate the drawbacks of the conventional ones as described above. It is an object of the present invention to provide a means that can reliably correct the convergence of each color of red, green, and blue represented by RGB by adding an integrating or differentiating circuit to a signal.

[Summary of the Invention] The present invention involves passing red and blue correction waveform signals through an integrating circuit or a differentiating circuit in convergence correction of a projection type color television device, particularly various corrections of vertical pincushion distortion, vertical bow distortion, and horizontal linearity. The mechanical center position of each CRT and the center position of the distortion waveform are determined by
The feature is that RGB convergence correction is reliably performed by correcting the center difference between the two.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described based on the drawings. In FIG. 1, 6 is an integrating circuit and 1 is a differentiating circuit, and parts equivalent to those in FIG. 8 are indicated by the same symbols. This figure shows an example of vertical pincushion distortion correction, and if the vertical pincushion distortion correction waveform generation circuit 5 is replaced with a vertical bow distortion correction waveform generation circuit or a horizontal linearity correction waveform generation circuit, vertical bow distortion correction, horizontal linearity correction, etc. It is something that can be done reliably. As mentioned above, the green vertical pincushion distortion correction waveform in Figure 1 is shown in Figure 4(b).
The straight line image shown in FIG. 4(c) is obtained by the correction waveform shown in FIG. The red vertical pincushion distortion correction waveform passes through the integrating circuit 6 and becomes the waveform shown by the solid line in FIG. 7(b). The red vertical pincushion distortion is canceled out with the waveform when viewed on the time axis, and as shown in FIG. 7(c), a straight line image is obtained as a convergence correction for the red vertical pincushion distortion.

The blue vertical pincushion distortion correction waveform has a mechanical center position symmetrical to that of the red CRTR, so by passing the output signal of the vertical pincushion distortion correction waveform generation circuit 5 through the differentiator circuit, ) is obtained, and the characteristic blue vertical pincushion distortion of water systems, shown by the dotted line in Fig. 7(a), is canceled out with the waveform when viewed on the time axis, resulting in the waveform shown in Fig. 7(c). As shown, a straight line image is obtained as a result of convergence correction for blue vertical pincushion distortion.

In the above embodiment, an example is shown in which an integrating circuit is used for the red signal and a differentiating circuit is used for the blue signal. It is clear that the object of the present invention can also be achieved using an integrating circuit.

Further, the waveform generation circuit for vertical bow distortion correction and horizontal linearity correction consists of a means for IJing a horizontal parabolic wave by integrating a sawtooth wave on the horizontal axis, and is similar to the vertical bow distortion correction described in the embodiment. Accordingly, the object of the present invention can be achieved. Note that the waveform signals for each correction obtained as described above are applied to the input terminals shown in FIG.

For example, regarding the red color, various correction waveform signals such as skew, keystone, and pincushion distortion passed through an integrating circuit, as well as similar vertical bow distortion and horizontal linearity are adjusted to appropriate levels to each input terminal. The signals are added and combined in a combining circuit, and a drive amplifier circuit drives the vertical convergence yoke of the CRTR to obtain a predetermined convergence characteristic.

Blue and green colors are also processed in the same way to achieve a predetermined purpose.

[Effects of the Invention] As described above, according to the present invention, convergence distortions such as vertical pincushion distortion, vertical bow distortion, horizontal linearity, etc. that occur in each of RGB due to the arrangement system of the mechanical center position of this device can be reduced. Convergence correction can be reliably performed by using an integrating circuit and a differentiating circuit that produce a correction waveform that is appropriate for distortion.

[Brief explanation of the drawing]

FIG. 1 is a block diagram relating to vertical pincushion distortion correction according to an embodiment of the present invention; FIGS. 2, 3, and 4 are waveform diagrams for explaining convergence distortion of a projection type color television apparatus; Figure 5 is a layout diagram of the device and its unique figure on the screen, Figures 6 and 7 are waveform diagrams of a portion processed for convergence correction, and Figure 8 is a conventional vertical pincushion distortion correction. FIG. 9 is a block diagram showing an overview of convergence correction. 2...Convergence yoke 3...Drive amplifier 5...Vertical pincushion distortion correction generation circuit Fig. 6 -H--H--H- -H--H--H-

Claims (1)

[Claims] 1. In a convergence correction circuit for a projection type color television device, (a) correction waveform generation using green as a reference to obtain various correction waveforms for vertical pincushion distortion, vertical bow distortion, and horizontal linearity; (b) an integrating circuit that integrates the output of the correction waveform generation circuit with reference to green with respect to red; and (c) a differentiation circuit that differentiates the output of the correction waveform generation circuit with reference to green with respect to blue. A convergence correction circuit characterized by: 2. The convergence correction circuit according to claim 1, wherein the integrating circuit is a differentiating circuit, and the differentiating circuit is an integrating circuit.