JPS6143916B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an apparatus for obtaining color television images by projecting three primary colors, by reducing the number of cores for convergence correction. The present invention aims to provide a convergence device that reduces the volume of parts and is suitable for a more compact three-primary color projection television device.

Conventionally, in a device that obtains color images by projecting three primary colors using three CRTs arranged in a triangular shape, the dynamic image is created by the difference in the angle of incidence of each primary color projector on the projection screen surface, as shown in Figure 1. Convergence and static convergence become misaligned. Here, in Figure 1, 1
is the projection screen surface, 2, 3, 4 are each primary color projector, 5, 6, 7 are the projection optical axes of each projector 2, 3, 4, respectively, 8, 9, 10 are each projector 2, 3, 4 An example of a projected raster is shown.

In order to obtain a clear color image, it is necessary to correct the deviations of the rasters 8, 9, and 10 so that the three primary colors almost completely match. Furthermore, since both dynamic convergence deviation and static convergence deviation have deviations in the horizontal and vertical directions, it is clear that corrections in both directions are necessary.

Regarding dynamic convergence correction, in the past there was a method in which a correction waveform was superimposed on a deflection coil, but there was also a method in which three projectors were arranged in a delta, and an aluminum screen with directional properties was used as the screen surface. In the case where the screen uses a spherical screen to prevent the occurrence of hot spots, the raster deviation becomes complicated, so the dynamic convergence correction is performed using the method shown in Figure 2, for example. Normally, this is done both vertically and horizontally using a dedicated core. Here, between A and A' in Figure 2,
Horizontal and vertical correction currents are applied between B and B', respectively.

On the other hand, regarding static convergence correction, in the past there was a method of mechanically moving each projector itself to adjust its projection direction, but this was very large-scale and costly. Become something.

Therefore, in general home projectors, the positions of the three projectors are completely fixed, and one core with the same dynamic convergence score as shown in Figure 2 is installed separately, including installation errors. It is common to perform static convergence adjustment in the horizontal and vertical directions by providing a direct current through the convergence. Therefore, the surrounding area of each projector of a general color television projecting three primary colors is as shown in FIG. In the figure, 1
1 is a valve, 12 is a deflection coil, 13 and 14 are a dynamic convergence yoke and a static convergence yoke, respectively.
This context does not matter either way. 15 indicates a coil bobbin. As is clear from Figure 3, it is necessary to attach a deflection coil, static convergence yoke, and dynamic convergence yoke to the CRT neck, and the direction of the magnetic field of each yoke is in the vertical and horizontal directions of the deflection coil. It was also necessary to match them, making it extremely troublesome to attach them to the neck.

In order to solve these problems, instead of providing a dynamic convergence yoke and a static convergence yoke separately as shown in FIG. 3, for example, a core having almost the same shape as the core shown in FIG. It is conceivable that by using both the dynamic convergence yoke and the static convergence yoke, it can serve as both the dynamic convergence yoke and the static convergence yoke.

That is, with the core shape shown in FIG. 2, a static convergence coil and a dynamic convergence coil are wound together on the same coil bobbin 15. This allows one core to be removed from the CRT network,
Furthermore, alignment with the deflection coil can be made simpler.

However, in this case, a problem arises in that the dynamic convergence coil and the static coil are coupled to each other.

The present invention eliminates the effects of this combination. One embodiment will be described below with reference to the accompanying drawings.

Generally, it is necessary to flow current in the dynamic convergence coil in the vertical and horizontal periods of the television. At this time, there is no problem with the vertical period current, but a horizontal period sawtooth current may flow, and in this case, depending on the relationship between the height of the pulse generated during the retrace period and the operating voltage of the dynamic convergence circuit, etc. , the inductance value of the dynamic convergence coil cannot take a very large value, and is only about several hundred μH at most. On the other hand, static convergence coils only require direct current to flow through them, so in order to reduce power consumption, it is desirable to have as large an inductance value as possible, and this value is approximately several tens of mH. Of course, this value is limited by the size of the bobbin, but the larger the value, the better.If these two coils are wound on the same bobbin, the coupling coefficient will be quite large.
If the inductance values of the static convergence coil and dynamic convergence coil are L _S and L _D respectively, and the output impedance of the static convergence circuit is Z _S , then in parallel with the dynamic convergence coil, Z _D ≧ = Z _S × L The impedances of _D and L _S will be combined. Moreover, since the value of L _D /L _S is often one hundredth, unless the value of Z _S is made considerably large, the dynamic convergence coil will be greatly damped, and current will no longer flow to the dynamic correction coil. . Therefore, as a static convergence circuit, a constant voltage source as shown in Figure 4 is divided into resistors _R1 and connected to series resistors.
If you use a circuit that allows the flow to flow through R ₂ , the resistance
It is necessary to select the resistance values of R ₁ and R ₂ to be quite large. In this case, if you try to make a large current flow through the static convergence coil L _S , it is necessary to increase the power supply voltage _EV , and the variable resistor R ₁
There is also a problem that the loss of the fixed resistor R ₂ also increases, and the power consumption also increases.

Therefore, in the first embodiment of the present invention, a high output impedance constant current source circuit as shown in FIG. 5 is used as the static convergence drive circuit. In the figure, _R4 is a variable resistor for adjusting the output current, and _R3 is a variable resistor for adjusting the variable range.

If you make a circuit like this, the fourth convergence coil L _S will require the same current to flow through it.
Compared to the circuit shown in the figure, the power supply voltage is much lower, the overall power consumption can be reduced, and it does not impose any load on the dynamic convergence circuit.

However, in the circuit shown in Figure 4, current can be passed in both directions through the static convergence coil L _S by adjusting the variable resistor _R1 , but in the circuit shown in Figure 5, current can only flow in one direction. However, this is not a special problem as it can be solved by looking at the static deviation and reversing the connection of the coil L _S.

Further, an example of a circuit that allows current to flow in both directions is shown in FIG. With this kind of circuit, when the variable resistor _R5 is located at the center, no current will flow through the static convergence coil _LS , and static convergence can be achieved by moving the movable piece of the variable resistor _R5 up and down. The coil L _S can be supplied with current in both directions from a very high output impedance circuit.

As described above, according to the present invention, one convergence core can be omitted by winding the static convergence coil driven by a high output impedance circuit at the same location in the same core as the dynamic convergence coil, and the convergence coil is connected to the deflection coil. Dynamic and static positioning can be performed at the same time, and the two convergence circuits are driven by independent drive circuits, and the static convergence coil is driven by a constant current circuit connected to the collector side of the transistor. This makes it possible to secure a very wide variable range of static convergence with a small amount of power consumption.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a three-primary color projection television device to which the present invention is applied, FIG. 2 is a diagram showing the configuration of a conventional convergence core, and FIG. 3 is a diagram showing the configuration of a conventional convergence device. 4 is a wiring diagram of a conventional static convergence circuit, FIG. 5 is a wiring diagram of a convergence circuit according to an embodiment of the present invention, and FIG. 6 is a wiring diagram showing another embodiment of the present invention. . 2, 3, 4...Primary color projector, 13...Static convergence yoke, 14...Dynamic convergence yoke.

Claims (1)

[Claims] 1. In the convergence circuit of a projection television that obtains a color image by projecting multiple primary color images by different cathode ray tubes, the static convergence coil and its inductance on the same bobbin on one convergence score are sufficient. Dynamic convergence coils having small inductance are provided separately, and both of the convergence coils are driven by independently provided drive circuits, and the static convergence coil is driven by a constant current circuit connected to the collector side of the transistor. A convergence circuit characterized by