JPS587751Y2 - Convergence device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a convergence device in a projection television receiver that obtains a color television image by projecting three primary colors using three different cathode ray tubes, and reduces the number of cores for convergence correction. This reduces the volume of parts around the neck of the projection cathode ray tube.
The present invention aims to provide a convergence device suitable for smaller projection television receivers.

Conventionally, in a device that uses three cathode ray tubes arranged in a triangular shape to obtain a color image by projecting three primary colors,
As shown in the figure, static convergence deviation occurs because the projection optical axes of each primary color projector do not coincide on the screen.

Furthermore, a dynamic convergence shift occurs due to the difference in the incident angle of each projector to the screen surface.

Fig. 1 is a layout diagram of this device viewed from above, where 1 is the projection screen surface, 2, 3, and 4 are the primary color projectors, respectively.
5, 6.7 are projection optical axes of each projector 2, 3.4.

FIG. 2 shows an example of the raster in the state shown in FIG.

In the figure, 8.9.10 indicates the projection raster by each projector 2, 3.4, and 11, 12.13 indicates the raster center of each projector 2, 3.4.

On the other hand, in order to obtain a clear color image, it is necessary to correct this deviation so that the three primary colors almost completely match.

Regarding dynamic convergence correction,
Since the three projectors are arranged in a triangular shape, there is a difference not only in the angle of incidence in the horizontal direction of the screen, but also in the angle of incidence in the vertical direction, as shown in FIG.

Furthermore, in the case of using an aluminum screen or the like with directivity as the screen surface, the screen surface is made spherical to prevent hot spots, so the raster misalignment is even more complicated.

For this reason, dynamic convergence correction is usually performed in a dedicated core as shown in FIG. 3, for example.

In the figure, correction currents are applied in the horizontal and vertical directions between A-A' and B-B', respectively, to create a magnetic field, deflecting the electron beam passing through the center of the core, and performing convergence correction.

Furthermore, regarding static convergence correction, in the past there was a method in which each projector itself was mechanically moved to adjust its projection direction, but this was very large-scale and costly.

Therefore, in general home projectors, the positions of the three projectors are completely fixed, and the third
As shown in the figure, it is common practice to separately provide another core that is the same as the dynamic convergence score, and to conduct static convergence adjustment in both the horizontal and vertical directions by passing a direct current through this core.

Therefore, the area around the neck of each projector of a general color television apparatus that projects three primary colors is as shown in FIG.

In the figure, 14 is a cathode ray tube bulb, 15 is a deflection yoke, 16 is a dynamic convergence yoke, and 17 is a static convergence yoke.

The convergence yokes 16 and 17 may be placed in either order.

Note that 18 indicates a convergence coil bobbin.

In this way, the neck of the cathode ray tube includes a deflection coil 15,
It is necessary to install the static convergence yoke 17 and the dynamic convergence yoke 16.

Furthermore, the direction of the magnetic field of each yoke must match the vertical and horizontal directions of the deflection yoke, which makes attachment to the neck portion extremely troublesome.

The present invention attempts to eliminate this difficulty.

The present invention will be explained below using FIG. 5 showing a specific example thereof.

The present invention attempts to correct the static convergence deviation by passing a direct current through the deflection coil, thereby omitting the static convergence yoke that is conventionally required.

FIG. 5 shows an example of this.

In the figure, 19 is a horizontal deflection circuit, 20 is a flyback transformer, 21°, 22.23 are horizontal deflection coils of each projector, and 24 is an S-shaped correction capacitor.

Further, 25, 26, and 27 are electrically isolated variable direct current generating circuits.

In this variable DC current generation circuit 25, 26, 27, 2
8 and 29 are rectifier diodes, 30 and 31 are smoothing capacitors, 32 is a static convergence adjustment volume, and 33 is a choke coil exhibiting high impedance to the horizontal deflection current.

Next, the operation will be explained.

The horizontal deflection current generated in the horizontal deflection circuit 19 flows through the horizontal deflection coils 21, 22, and 23 in series.

On the other hand, the flyback pulse generated in the flyback transformer 20 is rectified by diodes 28 and 29, smoothed by capacitors 30 and 31, and positive and negative voltages are generated with respect to the center tap of the winding.

Here, when the slider of the volume 32 of the variable DC current generation circuit 25 is moved from the center point, a DC current flows to the horizontal deflection coil 21 through the choke coil 33, and the DC current circuits 25 to 27 are insulated. Therefore, static convergence correction is performed only for the projector having the horizontal deflection coil 21.

Note that the horizontal deflection current does not flow to the variable direct current generation circuit 25 because of the choke coil 33, but instead flows only to the horizontal deflection coils 21 to 23.

Direct current is applied to the horizontal deflection coils 22, 23 independently from the variable direct current generating circuits 26, 27 in exactly the same manner as described above to perform static convergence correction for each.

Here, since the inductances of the horizontal deflection coils 21 to 23 are equal, the voltages generated at both ends of each horizontal deflection coil are also equal, and the windings of the choke coil 33 can be wound around one core as shown in FIG. can.

Further, vertical static convergence correction can also be performed by passing a direct current through the vertical deflection coil with a configuration similar to that shown in FIG. 5, thereby making it possible to omit the conventionally required static convergence yoke.

As explained above, according to the present invention, the static convergence yoke can be omitted, thereby reducing the volume of the components in the neck portion of the cathode ray tube and making the device more compact.

And since the moving direction of static convergence completely matches the horizontal or vertical deflection direction, adjustment becomes very easy.

Furthermore, when installing the convergence yoke to the cathode ray tube, only the dynamic convergence yoke is required.

Furthermore, in cathode ray tubes that use electromagnetic focusing, the focusing coil can be brought closer to the target surface, which lowers the lens ratio and improves focusing characteristics.

Therefore, the resolution increases and sharper images can be obtained.

[Brief explanation of the drawings] Figure 1 is a diagram showing the arrangement relationship between the projector and screen in a projection television receiver, and Figure 2 is an example of raster when no convergence correction is applied in the same receiver. 3 shows an example of the convergence yoke used in the same receiver, FIG. 4 shows the configuration of a conventional cathode ray tube neck, and FIG. 5 shows a convergence device according to an embodiment of the present invention. FIG. 2.3.4...Projector, 14...Cathode ray tube, 15...Deflection yoke, 21-23...
...Horizontal deflection coil, 25-27...Variable DC current generation circuit, 33...Choke coil.

Claims (2)

[Scope of utility model registration request] (1) In a convergence device for a projection television receiver that obtains a color image by projecting multiple primary color images using different cathode ray tubes, each deflection coil provided at the neck of each cathode ray tube is connected in series. A convergence device characterized in that a variable direct current generating circuit and a choke coil are connected in series to both ends of each of these deflection coils to perform static convergence correction. (2) The convergence device according to claim 1, wherein the windings of each choke coil are wound around the same core.