JPH05292516A - Deflecting yoke and vertical deflecting circuit using the same - Google Patents

Abstract

PURPOSE:To attain a convergence correction and a gun center correction of a cathode ray tube by a miniaturized constitution without causing any distortion of a beam spot. CONSTITUTION:Vertical deflecting coils 35, 36 of a deflecting yoke 31 are constituted by co-winding, respectively such as a vertical winding coil 10 and a sub- vertical winding coil 14. The vertical deflecting circuits for which plural pieces of projection type CRTs are used, let the deflecting yoke 31 install on the respective projection type CRTs, and a common vertical deflecting current is allowed to flow to the vertical winding coils 10, 11 and 12, and a DC current is allowed to flow to the sub-vertical winding coils 14, 15 and 16 independently. Thereby a convergence correction and a gun center correction are available.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a projection cathode ray tube (hereinafter referred to as C
RT) is used for a projection type video display device using a plurality of red, green and blue colors, and a vertical deflection circuit using the same.

[0002]

2. Description of the Related Art In recent years, image display devices using CRTs have been
The market for displaying high-definition video sources such as high-definition television and clear vision and for displaying character information and graphic information of computers is expanding, and improvement of focus performance is required in terms of high image quality on the entire display screen. Has been.

Particularly, in the projector type using a projection CRT, the current density per unit area of the electron beam applied to the CRT is very large, and C
In order to greatly enlarge the screen on the RT, it is more important to make the focus uniform over the entire screen. From this point, high-definition televisions and other high-definition applications are compared to the electrostatic focusing method. Therefore, it is easy to increase the size of the main lens, and as a result, an electromagnetic focusing projection CRT is often used, which provides good beam spot characteristics. FIG. 4 shows a configuration diagram of a system using the projection type CRT 41 of the electromagnetic focusing system. As a means for further improving the focusing performance in this electromagnetic focusing system, the focus magnet 45 is brought closer to the phosphor screen side,
It is effective to substantially reduce the lens magnification (b / a) of the main lens.

In this case, the uniformity of the magnetic field of each of the deflection yoke 42, the convergence yoke 43, and the centering magnet 44 is important for improving the focusing performance in addition to the focusing portion. Among these, the centering magnet 44 that corrects the gun center deviation caused by the assembly error of the projection type CRT 41 has a great influence on the beam spot at the center of the screen, which is the basis of the overall focusing performance. Figure 5
As shown in FIG. 5B, the dipole magnetic field generated by the centering magnet 44 is generally barrel-shaped, and therefore the force received at each portion within the circular cross section of the electron beam is different. The beam spot is deformed into an elliptical shape, impairing the roundness. Further, since the electron beam has astigmatism, the absolute diameter on the phosphor screen also becomes large. The centering magnet 44 itself has been improved in order to reduce the influence of the beam spot due to the non-uniformity of the magnetic field distribution of the centering magnet 44 as described above. The beam spot deterioration has a great influence.

In addition, as can be seen from FIG. 4, the centering magnet 44 is located immediately behind the convergence yoke 43 in terms of lowering the magnification of the main lens in the electromagnetic focusing system described above, so that the position of the focus magnet 45 is reduced. It is disadvantageous for improving focus performance due to restrictions.

Next, the influence of the convergence yoke 43 on the beam spot will be described. As a convergence correction function, a static convergence correction function that shifts the position of the screen raster in the horizontal and vertical directions on the entire screen and superimposes the colors by observing the screen center of the projected image of the projection type CRT 41 of three colors of red, green and blue. There is a dynamic convergence function that corrects raster distortion and superimposes three colors on each part of the screen. For the convergence correction, the beam before being deflected and scanned by the deflection yoke 42 is moved by a small distance by the correction magnetic field generated by applying the correction current to the horizontal and vertical coils of the convergence yoke 43. As in the case of the centering magnet 44, the correction magnetic field generated by the convergence yoke 43 has a certain degree of non-uniformity in the correction magnetic field, so that performing the convergence correction basically causes deterioration of the spot characteristics. From this point, the spot deterioration can be reduced if the convergence correction amount is as small as possible. Considering the influence of spot deterioration due to the convergence yoke 43, the static convergence correction can be considered to be similar to the centering magnet 44 because of the function of shifting the position of the screen raster.

The centering magnet 4 as described above
4. Recently, as a method of removing the deterioration of the beam spot characteristics due to the convergence yoke 43, a part of the video projector for high definition has adopted a direct current component in the horizontal and vertical sawtooth wave deflection current of the deflection yoke 42. Centering magnet 4 with superimposing and variable adjustment
This is a method of deleting the centering magnet 44 by substituting the function of 4. Since horizontal deflection can be dealt with without largely changing the configuration of the horizontal deflection circuit, the vertical deflection circuit will be described in the present invention.

A first conventional vertical deflection circuit in the case of a gun center correction using a centering magnet and a second conventional vertical deflection circuit in the case of superimposing a DC current on a deflection current will be described with reference to FIGS. 6 and 7. The difference and operation of each vertical deflection circuit will be described while making a comparison. The number of projection CRTs is 3, 6, or more, but there are practical examples, but here, the case of a three-tube type using one projection CRT of single color of red, green, and blue is described as an example. To do. First, in the case of the first conventional vertical deflection circuit for performing the gun center correction using the centering magnet 44, the vertical synchronizing signal VD1 is input to the vertical oscillating circuit 2 as shown in FIG. A vertical pulse synchronized with VD1 is output and input to the vertical sawtooth wave generation circuit 3 and the vertical pulse generation circuit 8. The vertical sawtooth wave generating circuit 3 outputs a vertical sawtooth wave in synchronization with the vertical synchronizing signal VD1, and the sawtooth wave is level-adjusted by the vertical amplitude adjusting circuit 4 and the vertical linearity adjusting circuit 5
Then, S-shaped correction is performed to improve the linearity on the CRT phosphor screen. The vertical sawtooth wave subjected to the vertical amplitude correction and the linearity correction is pre-driven by the vertical drive circuit 6 and power is amplified by the vertical output circuit 7 so that a vertical sawtooth wave current flows through the vertical winding coil of the deflection yoke. The vertical pulse from the vertical oscillation circuit 2 is input to the pulse amplifier circuit 9 as a vertical retrace pulse whose pulse width and level have been adjusted by the vertical pulse generation circuit 8. In the pulse amplifier circuit 9, it is necessary to speed up the current change of the vertical deflection current during the vertical blanking period, so the power supply voltage applied to the vertical output circuit 7 is switched to be increased during this blanking period.

The vertical output circuit 7 includes three vertical winding coils 1 of red, green, and blue projection CRTs connected in series.
0, 11, 12 are connected to perform vertical deflection drive, and the same vertical sawtooth wave deflection current is passed through the vertical winding coils 10, 11, 12. Then, in order to stabilize the deflection amplitude, a feedback resistor 13 for detecting a deflection current is inserted in series with the vertical winding coils 10, 11, 12 between the series circuit of the vertical winding coils 10, 11, 12 and the ground. The fluctuation of the vertical deflection current detected by the feedback resistor 13 as a voltage signal is fed back to the vertical drive circuit 6 to perform negative feedback control, thereby stabilizing the vertical deflection.

On the other hand, FIG. 7 shows a second conventional vertical deflection circuit which eliminates the centering magnet and superimposes and variably adjusts the direct current on the vertical deflection current to independently perform the gun center correction of the three CRTs. Explain. As described in the above example, it is necessary to stabilize the vertical deflection amplitude, and it is necessary to independently superimpose and variably adjust the DC current for each CRT of red, green, and blue. Therefore, the vertical oscillation circuit 2, the vertical sawtooth wave generation circuit 3, the vertical amplitude adjustment circuit 4, the vertical linearity adjustment circuit 5, and the vertical pulse generation circuit 8 of the vertical deflection circuit are common to each color of red, green, and blue. Regarding the vertical drive circuit, vertical output circuit, and pulse amplifier circuit, the same three vertical drive circuits 51, 52, 53 corresponding to the respective vertical winding coils 10, 11, 12 of red, green, and blue, and Vertical output circuits 54, 55, 56, pulse amplifier circuit 57,
It is configured to include 58 and 59. The vertical output circuits 54, 55, 56 for the respective colors are connected to the vertical winding coils 10, 1
1, 12 and a feedback resistor 63 for detecting a deflection current,
64 and 65 are connected in series, the variation of the deflection current for each color is detected and fed back to the vertical drive circuits 51, 52 and 53 for each color, and negative feedback control is performed for stabilization.

Raster shift control circuits 60, 61, 62 for superimposing a direct current on the vertical deflection current for independently performing gun center correction for each color of red, green and blue.
Is added to each of the red, green, and blue vertical deflection circuits so that a DC current can be superimposed on the vertical deflection current of each color. Specifically, the vertical drive circuit 51, 52, 53 clamps the vertical sawtooth wave in a DC manner, and then the position adjustment DC voltages adjusted to both positive and negative polarities from the raster shift control circuits 60, 61, 62 are added, and further, After pre-driving, it is applied to the vertical output circuits 54, 55 and 56. As a result, by adjusting the position adjusting circuit on the screen, the raster can be adjusted independently for each color in the vertical direction without changing the amplitude and the linearity of the vertical deflection scanning.

[0012]

However, the above-mentioned vertical deflection circuit has the following problems. First
In addition, since the output portion of the vertical deflection circuit is provided for each projection type CRT, the circuit size, the number of parts, and the mounting area of the vertical deflection circuit become large, which is also disadvantageous in terms of cost.

Secondly, the output portion of the vertical deflection circuit is provided for each projection type CRT, a separate vertical deflection current is supplied to each projection type CRT, and the stabilization control of the deflection current by negative feedback control is performed for each color. Since it is performed independently for each projection type CRT, there is a high possibility that a variation in vertical deflection will occur separately for each projection type CRT, and this variation becomes a new cause of convergence deviation. In particular, this fluctuation component affects the sawtooth wave current of vertical deflection, and thus causes a dynamic convergence fluctuation factor in the vertical direction of the screen, which makes compensation very difficult. SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a deflection yoke in which convergence adjustment is easy and variation is small, and a vertical deflection circuit using the deflection yoke.

[0014]

In order to achieve the above object, a deflection yoke of the present invention comprises an auxiliary coil which is electrically wound together with a winding of a vertical winding coil, and the auxiliary coil and the vertical coil. A vertical deflection circuit having independent input terminals of winding coils and using the deflection yokes is provided with the deflection yokes attached to each of a plurality of projection type CRTs. The input terminals of the winding coils are connected in series to connect a common vertical deflection current to the vertical drive circuit, and the input terminals of the auxiliary coils of the plurality of deflection yokes are supplied with independent DC currents. And a direct current drive circuit connected to the plurality of projection type CRTs.
It is used to perform convergence correction and gun center correction.

[0015]

The deflection yoke of the present invention having the above-described structure and the vertical deflection circuit using the same are provided in a projection type video display device using a plurality of projection CRTs, such as three monochromatic colors of red, green and blue. Since the common vertical driving current is made to flow by the common vertical driving circuit for the vertical deflection scanning characteristics of the projection type CRT, it is stably maintained at a common level, and the stability of the screen raster is impaired by the auxiliary coil wound together. Instead, it is possible to independently correct the gun center correction and the static convergence correction by the direct current drive circuit provided for each projection type CRT by the vertical deflection circuit. Therefore, the centering magnet and the static convergence correction function can be deleted, and the beam spot deterioration due to the influence of the correction magnetic fields of the centering magnet and the static convergence correction can be reduced.

[0016]

EXAMPLES Examples of the present invention will now be described with reference to FIGS.
This will be described with reference to FIG.

First, the deflection yoke of the present invention will be described with reference to FIG. FIG. 1 (a) is a structural explanatory view of a deflection yoke 31 according to an embodiment of the present invention, in which 32 is an annular core as a constituent element, and the core 32 has a pair of saddle-shaped inner coils having horizontal winding coils. The horizontal deflection coils 33 and 34 and a pair of saddle type vertical deflection coils 35 and 36 formed by the vertical winding coils are wound. Reference numeral 37 denotes a coil bobbin, which is disposed on the inner surface of the core 32 between the horizontal deflection coils 33 and 34 and the vertical deflection coils 35 and 36, and maintains insulation between the horizontal deflection coils 33 and 34 and the vertical deflection coils 35 and 36. , And fulfills the function of defining the positions of the coils 33, 34, 35, 36.

Further, each of the vertical deflection coils 35, 36 has a vertical winding coil 10, 1 as shown in FIG.
1, 12 and sub-vertical winding coil 1 as auxiliary coil
In the state of being electrically insulated by the respective combinations of 4, 15 and 16, for example, they are co-wound as shown in FIG.
The saddle shape as shown in (a) is provided, and the signal input connection terminals are independently provided. As a result, the deflection magnetic fields formed by the two sets of windings can be made substantially the same. In addition, the vertical winding coils 10, 1
In the present embodiment, Litz wires 1 and 12 are wound, on the other hand, sub-vertical winding coils 14 and 1 to be co-wound.
By using a single wire thicker than the litz wire for 5 and 16, it is arranged so that the thin litz wire is wound around the thick single wire during co-winding, and the winding is facilitated.

Next, a vertical deflection circuit according to an embodiment of the present invention using this deflection yoke will be described. It should be noted that those having the same functions as those of the conventional one are denoted by the same reference numerals. As shown in FIG. 2, in the present invention, a drive circuit block for supplying a vertical sawtooth wave current to a vertical deflection coil for so-called vertical deflection scanning and a circuit block for vertically adjusting the position of a scanning raster on a screen are electrically connected. Is also completely separated. The first winding of the vertical deflection coil of the deflection yoke described in FIG. 1 is the vertical winding coils 10, 11, 12 in FIG.
Indicated by. The drive circuit for supplying the vertical sawtooth wave current to the first winding includes a vertical oscillation circuit 2, a vertical sawtooth wave generation circuit 3, a vertical amplitude adjustment circuit 4, and a vertical linearity adjustment circuit from the input of the vertical synchronization signal VD1. 5, a vertical drive circuit 6, a vertical output circuit 7, a vertical pulse generation circuit 8, a vertical sawtooth wave drive circuit for vertical deflection scanning of a portion consisting of a pulse amplifier circuit 9 and three vertical winding coils 1
The series connection of 0, 11, and 12 and the connection and function of the feedback resistor 13 are the same as those of the vertical deflection circuit of the first conventional example, and the description thereof will be omitted.

A circuit block for vertically adjusting the position of the scanning raster on the screen will be described below. The second winding of the vertical deflection coil of the deflection yoke of FIG. 1 is shown in FIG. 2 by the sub-vertical winding coils 14, 15, 16. The position adjusting circuit functions as a sub-vertical winding coil 1 by the vertical raster shift circuits 17, 18 and 19 as a DC current driving circuit.
It is possible to variably adjust the polarity and the current value of the DC current flowing through 4, 15 and 16, and as a result, the vertical position of the screen raster can be moved up and down. Next, details of the operation of the vertical raster shift circuits 17, 18, and 19 will be described with reference to FIG. The adjusting volume 20 is a volume for adjusting the vertical raster position, and by this adjustment, the DC voltage applied to one input terminal of the differential amplification output amplifier 21 can be variably adjusted. The differential amplification output amplifier 21 is a power amplifier for supplying a direct current to the sub-vertical winding coils 14, 15 and 16. In addition, the resistor 23 has a damping action for preventing current oscillation. Further, a feedback is constituted by the resistor 24, the current flowing in the sub vertical winding coils 14, 15 and 16 is detected and fed back to the other input terminal of the differential amplification output amplifier 21, and the direct current is supplied to the sub vertical winding coil. We are trying to stabilize the current. In addition, + B1 and -B1 are DC voltage power supplies with different polarities of the position adjustment control voltage adjustment unit for adjusting the polarity of the DC current and the current value, and + B2 and -B2 are positive and negative power supplies for the differential amplification output amplifier 21. ..

[0021]

As is apparent from the above description, the deflection yoke of the present invention has the auxiliary coil wound together, and the projection type CRT vertical deflection circuit using the same is a vertical drive circuit common to a plurality of deflection yokes. And a DC current drive circuit independently of each other, the vertical deflection scanning characteristics of the projection type image display device using the projection type CRT can be stably maintained at a common level for each projection type CRT, and the screen raster can be stabilized. It is possible to independently correct the gun center correction and the static convergence correction for each projection CRT without causing the deterioration of the degree and the focus characteristic.

[Brief description of drawings]

FIG. 1A is a side view of a partial cross section of a deflection yoke according to an embodiment of the present invention. FIG. 1B is a schematic view showing the configuration of a vertical deflection coil of the deflection yoke of the embodiment. Side view showing an example of co-wound deflection yoke

FIG. 2 is a block diagram showing a configuration of a vertical deflection circuit according to an embodiment of the present invention.

FIG. 3 is a block diagram showing the configuration of a vertical raster shift circuit of the vertical deflection circuit of the same embodiment.

FIG. 4 is a side view showing an outline of a conventional projection CRT system of an electromagnetic focusing system.

FIG. 5A is an explanatory diagram of a magnetic field distribution of the conventional centering magnet, and FIG. 5B is a pattern diagram showing an example of beam spot distortion generated thereby.

FIG. 6 is a block diagram showing a configuration of a vertical deflection circuit of a conventional projection type projector that performs gun center correction by a centering magnet.

FIG. 7 is a block diagram showing the configuration of a vertical deflection circuit of a conventional projection type video projector that performs gun center correction without using a centering magnet.

[Explanation of symbols]

 10, 11, 12 Vertical winding coil 14, 15, 16 Sub vertical winding coil 31 Deflection yoke 35, 36 Vertical deflection coil

Claims (4)

[Claims] 1. A vertical winding coil for vertically deflecting an electron beam of a cathode ray tube, a co-wound auxiliary coil electrically insulated from a winding of the vertical winding coil, and the vertical winding coil. A deflection yoke having independent input terminals of the auxiliary coil. 2. A vertical winding coil having a first wire diameter having a first wire diameter.
And a second coil having a second wire diameter larger than the first wire diameter, and the auxiliary coil is wound around the surface of the second wire. Claim 1
Deflection yoke as described. 3. A plurality of deflection yokes according to claim 1, which are attached to each of a plurality of projection cathode ray tubes, and input terminals of vertical winding coils of the plurality of deflection yokes are connected in series and common. A vertical drive circuit connected so as to pass a vertical deflection current; and a plurality of direct current drive circuits independently connected to each input terminal of the auxiliary coils of the plurality of deflection yokes so as to pass a direct current. A vertical deflection circuit configured to perform convergence correction or gun center correction of the plurality of projection cathode ray tubes by the DC current drive circuit. 4. The vertical deflection circuit according to claim 3, wherein the direct current drive circuit has direct current voltage sources of different polarities for supplying direct currents of both polarities.