JPH0564412B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a horizontal deflection circuit in a television receiver or the like, and more particularly to linearity correction of a horizontal scanning beam.

[Background of the Invention] For such linearity correction, it has been proposed in JP-A-9-111541 and JP-A-51-80122 to provide a linearity correction means integrated with the deflection coil. Something like this is known. However, in these known examples, the conventional linearity correction coil is simply replaced with a new means, and there is no suggestion of a means for achieving complete linearity correction while also reducing the power consumption of the entire set. do not have.

[Purpose of the invention]

An object of the present invention is to perform complete linearity correction by using the direct current magnetic field of the magnet, which has low power consumption, and is therefore a horizontal linearity correction means that can reduce the power consumption of the deflection circuit and the entire set. An object of the present invention is to provide a horizontal deflection circuit having the following features.

[Summary of the invention]

In order to achieve the above object, the present invention is characterized in that a pair of magnets with the same polarity in the vertical direction are arranged near the left and right ends of the deflection yoke opening.
Furthermore, in the present invention, a winding is provided on the pair of magnets, an alternating current corresponding to the horizontal deflection current is passed through the winding, and the effect of the alternating magnetic field generated by the alternating current on the electron beam is also taken into account. Another feature is that the horizontal linearity correction effect is improved.

[Embodiments of the invention]

An example of the arrangement of linearity correction magnets according to an embodiment of the present invention is shown in FIGS. 1a and 1b.

In FIG. 1a, 1 is a cathode ray tube, 2 is a deflection yoke, and 3 is a linearity correction magnet. The figure shows a cathode ray tube equipped with a deflection coil 2 and a linearity correction magnet 3, viewed from the side.
The electron beam is vertically deflected in the direction of the arrow.

FIG. 1b shows the deflection yoke 2 and the linearity correction magnets 3 and 4 viewed from the opening side of the deflection yoke 2. As shown in the figure, the magnets 3 and 4 are arranged so that the south pole is on the scanning start end side of vertical deflection and the north pole is on the scanning end side of vertical deflection. Therefore, in the portion sandwiched between the magnets 3 and 4, lines of magnetic force are formed upward from below as shown by broken lines and arrows in the figure. The intensity distribution of the magnet formed by the magnets 3 and 4 is as shown in FIG. 2 when viewed in cross section A-A' in FIG. 1b.

In Fig. 2, point O on the horizontal axis indicating the position is the geometric center of the deflection yoke, that is, the electron beam position of the deflection magnet at the opening of the deflection yoke, and points S and E are located at the opening of the deflection yoke, respectively. The horizontal deflection start and end magnetic electron beam positions are shown. That is, at the deflection yoke opening, the electron beam is deflected in the horizontal direction from point S to point E. Here, the magnetic field strength is strong at point S and point E, and weakest at point O. Note that the distribution state of this magnetic field strength can be variously modified depending on the strength, shape, and relative position of the magnets 3 and 4.
The key point of the present invention is to arrange so that the strength is weakest near the O point, and the S and E points are stronger than the O point.

In addition, in Fig. 1, the electron beam is also deflected in the vertical direction, but in order to avoid raster distortion, the effect of magnets 3 and 4 on the electron beam is always constant for the vertical deflection situation. This is desirable.

That is, in the opening of the deflection yoke 2, it is desirable that the magnetic field generated by the magnets 3 and 4 within the range where the electron beam is deflected has only a vertical component and almost no horizontal component.

To do this, the magnets 3 and 4 must be point symmetrical with respect to the center position of the deflection yoke shown in FIG. Just place it.

Furthermore, in order to reduce the horizontal magnetic field component in the electron beam deflection region, the magnets 3 and 4 need to have lengths longer than a certain level. The length of this magnet depends on the deflection angle of the cathode ray tube, etc., but generally it should be about 1/3 or more of the diameter of the deflection yoke opening.

Now, horizontal linearity distortion in normal television receivers, etc. is caused by loss due to DC resistance in the deflection circuit, collector-emitter saturation voltage of the horizontal output transistor (V _CE sat: For example, the power supply voltage of the horizontal deflection circuit is
In small TV receivers etc. of about 10V, this V _CE
The influence of sat is large and cannot be ignored. ), etc., and it is well known that it has an exponential characteristic of elongating at the start end of the horizontal scan and contracting at the end of the horizontal scan. Therefore, in order to correct this linearity distortion, it is necessary to perform correction such that it is shortened at the horizontal scanning start end and expanded at the horizontal scanning end. Conventional general horizontal linearity correction coils use changes in inductance connected in series with the horizontal deflection yoke to perform this correction, but this is especially true for small models where the power supply voltage of the horizontal deflection circuit is low and the initial distortion is large. In TV receivers, etc., the required amount of correction is large, and therefore the inductance value connected in series with the horizontal deflection yoke cannot be ignored compared to the inductance value of the horizontal deflection yoke, and the reactive power in the horizontal deflection power is large. There was a problem.

However, in the embodiment of the invention shown in FIGS. 1 and 2, horizontal linearity distortion can be corrected without expending reactive power. That is, at the horizontal scanning start end side, the electron beam receives a force mainly due to the magnetic field from the magnet 3 in the opposite direction from the deflection magnetic field of the horizontal deflection yoke, and at the horizontal scanning end side, the electron beam receives a force from the deflection magnetic field of the horizontal deflection yoke. receives a force in the same direction as
That is, it contracts at the horizontal scanning start end and expands at the end, thereby correcting the initial horizontal linearity distortion. It is desirable that the magnetic field strength at point O in Figure 2 is 0, but if directness distortion correction is sufficiently performed at points S and E, the magnetic field strength at point O will not become 0. Sometimes. This indicates that the screen center position shifts according to the magnetic field strength, but this shift is caused by, for example, a two-pole magnet, which has traditionally been used in combination with a deflection yoke, on the cathode ray tube network side of the deflection yoke. That is, it can be easily corrected using a centering magnet.

As explained above, according to the present invention, the strength of the magnet can be increased without causing reactive power in the horizontal deflection circuit.
Horizontal linearity distortion can be corrected by appropriately selecting the shape, arrangement position, etc. Note that in television receivers of the same type, the magnet strength, shape, and arrangement position of the magnets are almost the same, and the same degree of correction effect can always be obtained, and there is no need to make adjustments for each individual television receiver.

Next, a second embodiment of the present invention is shown in FIG. 3 and will be described in detail.

In FIG. 3, the magnets 3 and 4 of FIG. 1b are provided with windings 5 and 6, respectively, as shown. The terminals of the windings 5 and 6 are 7, 8, 9 and 10, respectively, and alternating currents corresponding to the horizontal deflection currents are passed through the windings 5 and 6, respectively, through these terminals. This current may be the horizontal deflection current itself flowing through the horizontal deflection yoke, or may be a toothed wave current obtained by integrating a horizontal synchronization signal or a horizontal flyback pulse. FIG. 3a shows a state in which the electron beam is at the horizontal scanning start end, and FIG. 3b shows a state in which the electron beam is at the horizontal scanning end.

In the state at the scanning start end side shown in FIG. Windings 5 and 6
Due to the current flowing through the magnetic fields, magnetic fields are generated as indicated by dashed lines 11 and 12 and arrows, respectively. On the other hand, the third
In the state at the end of the scan shown in FIG. 2B, current is applied to the windings 5 and 6 from terminals 8 and 10, and current is taken out from terminals 7 and 9, respectively. Therefore, this current generates a magnetic field shown by dashed lines 13 and 14 and arrows.

The magnetic fields indicated by broken lines 11 to 14 are alternating current magnetic fields, and the distribution state of the magnetic field strength combined with the direct current magnetic fields generated by magnets 3 and 4 is shown in FIG. Figure 4 shows the second
In the same way as the figure, it shows the state of magnetic field distribution depending on location, with the horizontal axis representing the positions including points S, O, and E, and the vertical axis representing the magnetic field strength. Also, the fourth
Figure a shows the state at the time when the electron beam is at the scan start end, that is, the state shown in Figure 3 a, and Figure 4 b shows the state when the electron beam is at the end of the scan, that is, the state at the time when the electron beam is at the end of the scan, that is, the state shown in Figure 3.
The state shown in Figure b is shown. In addition, in Fig. 4, A indicates the DC magnetic field generated by the magnets 3 and 4, and B indicates the winding 5.
and 6 shows an alternating current magnetic field generated by an alternating current flowing through it, and C shows a composite magnetic field obtained by combining the magnetic fields of A and B.

The configuration shown in FIG. 3 is characterized in that the correction magnetic field at the required time and place can be used more effectively than in the cases shown in FIGS. 1 and 2. That is, at the time when the electron beam is on the scanning start end side, the correction magnetic field strength is shown in FIG. In addition, when the electron beam in FIG. 4b is on the scanning end side, the combined magnetic field strength on the side of point E, where the electron beam is present, is larger than the DC magnetic field generated by magnets 3 and 4. It's getting bigger compared to just that.

In the case of the embodiment shown in FIG. 3, since the horizontal linearity distortion has been corrected in advance by the DC magnetic field generated by the magnets 3 and 4, the amount of horizontal linearity distortion to be corrected by the current flowing through the windings 5 and 6. need to be extremely small. Therefore, the number of turns of the windings 5 and 6 can be extremely small, and the reactive power when the windings 5 and 6 are connected in series to the deflection yoke can also be extremely small.

There are two ways to connect the windings 5 and 6 to the deflection yoke, as shown in FIGS. 5a and 5b.

In FIG. 5, 15 represents a horizontal deflection coil, and 16 and 17 are its opposite ends. 5 to 10 indicate the same items as in FIG. i.e. windings 5 and 6
The effect of reducing the reactive power due to the elements connected in series to the deflection yoke is as shown in Fig. 5b. is larger. The reason for this is, firstly, the impedance decreases due to the parallel connection, and secondly, since the inductance of the required winding of windings 5 and 6 is smaller than that of the other winding, most of the deflection current is required. This is because the current flows through the winding of the other side. For example, in FIG. 3a, that is, when the electron beam is at the scanning start end side, the polarity of the AC magnetic field 11 generated by the winding 5 is the same as the polarity of the DC magnetic field of the magnet 3, but The magnetic field polarity of magnet 4 is opposite. Therefore, the inductance of winding 5 and winding 6
Comparing the inductances of the winding 5, the winding 5 has a smaller inductance, and more deflection current flows through the winding 5.

This is not shown in the graph of Figure 4a (b), but if this is taken into account, the magnetic field strength at point S will be larger in the graph of Figure 4a, (b), and E
The magnetic field strength at the point approaches zero.

Similarly, when the electron beam is at the end of scanning,
In FIG. 3b, the inductance of the winding 5 is greater than the inductance of the winding 6, and therefore more deflection current flows through the winding 6, resulting in a greater correction effect.

Conversely, although the magnetic field strength required for correction is constant, in the second embodiment, compared to the first embodiment,
The DC magnetic field strength at point O can be reduced,
Therefore, the amount of center shift of the image can be reduced.

In addition, in the case of an electronic viewfinder where the image is reflected by a mirror for viewing, the horizontal scanning may be reversed left and right compared to a normal television receiver, and in such a case, the magnets 3 and 4 in Fig. 1 may be used. Just reverse the polarity.

〔Effect of the invention〕

As explained above, according to the first embodiment of the present invention, horizontal linearity correction can be performed without the need for a lot of reactive power, and according to the second embodiment, the horizontal linearity can be corrected significantly compared to the conventional method. A very large correction effect can be obtained with small reactive power.

In addition, in order to maintain the uniformity of the reproduced hue over the entire surface, the beam index method requires stricter horizontal linearity performance than the shadow mask method. With the conventional method of using a linearity correction coil, which uses changes in inductance value that occur with current value to correct linearity, it is extremely difficult to ideally correct linearity over the entire horizontal deflection range. Katta. This is because it was necessary to simultaneously correct the horizontal scanning start side and end side, which require different correction amounts, using one coil.

In contrast, in the present invention, the strength of the left and right magnets can be made different in advance, and the mounting positions relative to the deflection yoke can be selected individually or at the same time. It has many degrees of freedom and can provide extremely good correction performance.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing a first embodiment according to the present invention, Fig. 2 is a characteristic diagram showing the magnetic field intensity distribution of Fig. 1, and Fig. 3 is an explanatory diagram showing a second embodiment according to the present invention. , FIG. 4 is a characteristic diagram showing the magnetic field strength distribution of FIG. 3, and FIG. 5 is an explanatory diagram showing the electrical connection method in the second embodiment. 1... Braun tube, 2... Deflection yoke, 3, 4
...Magnet, 5,6...Winding, 15...Horizontal deflection coil.

Claims (1)

[Claims] 1. In a horizontal deflection circuit of a television receiver, magnets are arranged near the left end and near the right end of the opening of a deflection yoke constituting the circuit, and the magnetism of both magnets is made the same in the vertical direction. A horizontal deflection circuit that corrects the linearity of horizontal scanning beams by aligning them. 2. In the horizontal deflection circuit according to claim 1, each of the magnets is wound with a wire,
Among these magnet windings, a current corresponding to the deflection current in the first half of the horizontal deflection is passed through the magnet winding on the horizontal deflection start end side in a direction that generates a magnetic flux with the same polarity as the magnetic flux caused by the magnet. , a horizontal deflection characterized in that a current corresponding to the deflection current in the second half of the horizontal deflection is passed through the magnet winding on the end side of the horizontal deflection in a direction in which a magnetic flux having the same polarity as the magnetic flux caused by the magnet is generated. circuit.