JPH07201290A - Projection type cathode-ray tube device - Google Patents

Abstract

PURPOSE:To improve the focus performance on the periphery of the screen. CONSTITUTION:A convergence yoke 4 of a projection type cathode-ray tube consists of a core 8 and coils 9a, 9b. The deflected magnetic field generated by the convergence yoke 4 is intentionally non-uniformed by changing the balance of the deflected magnetic field generated by the coils 9a, 9b by a balance adjusting means 11, and the beam spot shaped distortion generated by the non- uniformity of the deflected magnetic field generated by a deflected yoke (not shown in the figure) is canceled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CRT device used in a projection display device, that is, a projection CRT device.

[0002]

2. Description of the Related Art As shown in FIG. 9, a projection type cathode ray tube 1 of an electromagnetic focusing system is equipped with a deflection yoke 3, a convergence yoke 4 and an electromagnetic focusing device 5 on a neck portion thereof in order from a fluorescent screen 2 side. . In such a configuration, the electron beam 7 generated at the cathode 6 reaches the fluorescent screen 2 after being subjected to the focusing action by the focusing lens formed by the electromagnetic focusing device 5. In addition to the focusing action of the electromagnetic focusing device 5, the electron beam 7 is deflected by the magnetic field generated by the deflection yoke 3 and the convergence yoke 4, and reaches the peripheral portion 2a of the fluorescent screen 2 as the electron beam 7a. . The main deflection of the electron beam by the deflection action is performed by the deflection yoke 3, and the color misregistration and the raster distortion are mainly adjusted by the convergence yoke 4.

The shape of the fluorescent screen of the projection type cathode ray tube device is
Since the center is different from the spherical surface that coincides with the center of deflection, the distance from the focusing lens formed by the electromagnetic focusing device is different between the center and the periphery of the fluorescent screen. In particular, in the projection type cathode ray tube 1 shown in FIG. 9, the shape of the fluorescent surface 2 is a convex lens shape in order to use the light emitted by the fluorescent material as effectively as possible. Therefore, so-called dynamic focus adjustment is essential in which the strength of the focusing lens formed by the electromagnetic focusing device 5 is changed according to vertical / horizontal deflection. The dynamic focus adjustment is performed by passing a correction current synchronized with the vertical / horizontal deflection wave through the dynamic focus coil 5a provided in the electromagnetic focusing device 5.

Further, in the case of an electrostatic focusing projection CRT device, the electron beam is focused by a focusing lens formed by an electrode provided in the neck of the CRT. Further, the dynamic focus adjustment is performed by changing the voltage applied to the electrodes. The deflection action is the same as in the case of the projection type cathode ray tube device of the electromagnetic focusing system. Related to this type of device, there is a device disclosed in Japanese Patent Application Laid-Open No. 1-276546.

[0005]

However, the above-mentioned prior art has the following problems.

Due to the non-uniform component of the deflection magnetic field generated by the deflection yoke 3 in FIG. 9, the electron beam undergoes different lens actions in the vertical and horizontal directions. For example, when the horizontal deflection magnetic field has a pincushion type distortion, the non-uniform component of the deflection magnetic field is as follows for a horizontally deflected electron beam:
It acts as a focusing lens in the vertical direction and as a diverging lens in the horizontal direction. Therefore, if the focus is adjusted in the vertical direction, the focus becomes underfocus in the horizontal direction, and the beam spot is distorted horizontally. That is, there is a problem that the focusing performance is deteriorated around the phosphor screen.

On the other hand, the distortion of the raster due to the projection optical system in the projection type display device is corrected by the convergence yoke 4 in FIG. Electron beam is deflection yoke 3
Since it is subjected to the deflection effect by the convergence yoke 4 from before, the distance from the focusing lens to the fluorescent screen 2 varies depending on the presence or absence of the correction by the convergence yoke 4, the direction of the correction, and the correction amount. However, in the conventional dynamic focus adjustment corresponding to the vertical / horizontal deflection, the influence of the convergence correction was not taken into consideration.

A first object of the present invention is to provide a projection type cathode ray tube device capable of correcting the deviation of the focus between the horizontal direction and the vertical direction caused by the action of the nonuniform component of the deflection magnetic field. is there.

A second object of the present invention is to provide a projection type cathode ray tube device capable of correcting the defocus of the focusing lens caused by the operation of the convergence yoke.

[0010]

In order to achieve the above-mentioned first object, the present invention uses a convergence yoke to generate a non-uniform deflection magnetic field, and the electron beam reaches the deflection magnetic field. First means for changing the position is provided.

In order to achieve the second object, the present invention is provided with a second dynamic focus adjusting means for adjusting the focal length of the focusing lens according to the presence / absence of the convergence correction, the direction of the correction, and the correction amount.

[0012]

According to the first means, the distortion of the beam spot around the fluorescent screen caused by the non-uniform component of the magnetic field generated by the deflection yoke can be canceled, and the excellent focusing performance can be obtained over the entire fluorescent screen. can get.

Further, according to the second dynamic focus adjusting means, it is possible to correct the deviation of the focal length of the focusing lens due to the presence or absence of the convergence correction, and it is possible to obtain the excellent focusing performance in the entire fluorescent screen.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following is a description with reference to the drawings of a case in which an embodiment of the present invention is applied to the projection type cathode ray tube 1 shown in FIG.

FIG. 1 is a block diagram showing an embodiment of a projection type cathode ray tube device according to the present invention, in which 4 is the convergence yoke shown in FIG. 9, 8 is a core, 9a and 9b are coils, and
Reference numerals 10a and 10b are coil driving means, and 11 is a balance adjusting means.

In the figure, the convergence yoke 4
Is a ring-shaped core 8 and a coil 9 wound around the core 8.
It is composed of a and 9b. The coils 9a and 9b have the same winding specifications and are driven by independent coil driving means 10a and 10b, respectively. Coils 9a, 9b
The distribution ratio of the current for driving is adjusted by the balance adjusting means 11 based on the convergence correction waveform and the beam spot shape correction waveform.

The deflection action of the convergence yoke 4 and the beam spot shape correction action will be described with reference to FIGS. 2 and 3.
Will be described. However, FIGS. 2 and 3 show the relationship between the magnetic field generated by the convergence yoke 4 and the beam spot shape of the electron beam. In both figures, the back side of the paper surface is the electron gun side, the front side of the paper surface is the fluorescent surface side, and FIG. The horizontal direction of the paper is the horizontal direction, and the vertical direction of the paper is the vertical direction.

FIG. 2 (a) shows a case where currents of the same magnitude are applied to the coils 9a and 9b to deflect the electron beam 12a to the right. In this case, the coil 9
Deflection magnetic field 13 so that it is symmetrical by a and 9b.
a, 13b, 13c are formed. An almost uniform magnetic field is formed in a region near the center where the electron beam 12a passes, and the electron beam 12a receives a rightward force 14 as a whole. Therefore, the beam spot shape of the electron beam 12a after deflection is almost the same as that before deflection. The coil 9
If the directions of the currents applied to a and 9b are reversed, the electron beam 1
The deflection direction of 2a is the opposite left direction.

FIG. 2B shows the case where currents of equal magnitude are applied to the coils 9a and 9b in opposite directions.
In this case, the magnetic field 15a generated by the coil 9a and the coil 9a
The magnetic field 15b due to b is in the opposite direction, and leakage magnetic fields 15c and 15d are also generated. These magnetic fields act as a focusing lens in the horizontal direction and a diverging lens in the vertical direction with respect to the electron beam 12b, and do not serve as a deflection magnetic field. That is, the electron beam 12b has the forces 16a, 16b, 1 shown.
Upon receiving 6c and 16d, the beam spot becomes a vertically long elliptical shape. When the directions of the currents flowing through the coils 9a and 9b are reversed, the beam spot becomes a horizontally long elliptical shape.

In FIG. 3A, the current flowing through the coil 9a is made larger than the current flowing through the coil 9b, and the electron beam 1
2C shows a case in which 2c is deflected to the right.
In this case, the pincushion-shaped deflection magnetic fields 17a, 17b, and 17c which are left-right asymmetrical are formed. These magnetic fields act on the electron beam 12c as a focusing lens in the horizontal direction and as a diverging lens in the vertical direction. That is, as shown in the figure, the electron beam 12c has forces 18a and 18b whose directions are different in the vertical direction and whose magnitudes are equal.
And the rightward forces 18c and 18d having different magnitudes from each other, are compressed in the horizontal direction while being deflected to the right,
Expanded vertically. Therefore, the beam spot becomes a vertically long elliptical shape 12d. When the current flowing through the coil 9b is larger than the current flowing through the coil 9a, the beam spot shape 12d becomes a horizontally long elliptical shape.

In FIG. 3B, the current flowing through the coil 9b is made larger than that flowing through the coil 9a, and the electron beam 1
The case where 2e is deflected to the left is shown.
In this case, the pincushion-shaped deflection magnetic fields 19a, 19b, and 19c which are left-right asymmetrical are formed. These magnetic fields act on the electron beam 12e as a focusing lens in the horizontal direction and as a diverging lens in the vertical direction. That is, as shown in the figure, the electron beam 12e has forces 20a and 20b having different directions in the vertical direction and equal in magnitude.
And the leftward forces 20c and 20d having different magnitudes from each other, are compressed in the horizontal direction while being deflected to the left,
Expanded vertically. Therefore, the beam spot becomes a vertically long elliptical shape 12f. When the current flowing through the coil 9a is larger than the current flowing through the coil 9b, the beam spot shape 12f becomes a horizontally long elliptical shape.

In FIG. 2 (a) showing the initial state, a substantially uniform magnetic field is generated, but by changing the winding specifications of the coils 9a and 9b, the initial state can be changed to an arbitrary distortion magnetic field. , Asymmetric magnetic fields are also possible.

Now, the system configuration of this embodiment including the deflection yoke will be described.

In the display device, the horizontally long screen is the mainstream, and the horizontal deflection amount is larger than the vertical deflection amount. Therefore,
The shape of the beam spot is more susceptible to the horizontal deflection magnetic field. On the other hand, the distortion of the deflection magnetic field is effective in correcting the raster distortion. In particular, the pincushion distortion of the horizontal deflection magnetic field can reduce the pincushion distortion in the vertical direction of the raster, which has a heavy load on the circuit system. Therefore, in the projection type cathode ray tube device in which the vertical deflection magnetic field of the deflection yoke 3 in FIG. 9 is uniform and the horizontal deflection magnetic field has a pincushion type distortion, the relationship between the horizontal deflection magnetic field and the beam spot shape will be described.

First, FIG. 4 shows the distortion of the raster and the beam spot shape at each position on the screen when only the deflection action of the deflection yoke 3 is applied. However, here, in the upper right of the screen 1 /
4 is shown.

In FIG. 4, when the beam spot 21 having a substantially circular shape at the center of the screen is deflected to the periphery of the screen, as shown in the figure, the shape is distorted to become laterally elongated elliptical beam spots 21a, 21b, 21c. Furthermore, the raster 22c
It is assumed that a raster 22b 'having a pincushion type distortion is generated at. In order to correct such distortion, the convergence yoke 4 corrects the position of the beam spot so that the raster 22b 'becomes the raster 22b, and
It is necessary to correct the shape of the beam spot.

Therefore, the position of the illustrated beam spot 21a is corrected to the right as shown by the arrow 23a. To this end, the convergence yoke 4
Then, the magnetic field shown in FIG. 3A may be generated. Also,
The position of the illustrated beam spot 21c is corrected to the left as shown by the arrow 23b. For this purpose, the convergence yoke 4 may generate the magnetic field shown in FIG. Further, since only the shape of the illustrated beam spot 21b needs to be corrected, the convergence yoke 4 may generate the magnetic field shown in FIG. Each of the electron beams is subjected to a force such that the shape of its beam spot becomes a vertically long ellipse.

Therefore, in FIG. 1, as the vertical deflection by the deflection yoke 3 progresses, the balance adjusting means 1 responds to the convergence correction waveform and the beam spot correction waveform.
1 adjusts the ratio of the currents flowing in the coils 9a and 9b and the flowing direction, and when the vertical deflection of the upper half of the screen is started,
The magnetic field shown in (b) is generated from the convergence yoke 4, and the magnetic field generated from the convergence yoke 4 changes to the magnetic field shown in FIG. 2B and the magnetic field shown in FIG. 3A as the vertical deflection progresses. In the lower half of the screen, from the magnetic field shown in FIG. 3A to the magnetic field shown in FIG.
The magnetic field is changed to that shown in (b). As a result, the vertical raster 22b 'can match the regular raster 22b, and the shape of the beam spot can be a perfect circle at any position on the screen, and the distortion of the beam spot due to the deflection magnetic field can be canceled. As a result, excellent focus performance is obtained over the entire screen.

In the above description, both the deflection yoke and the convergence yoke relate to the distortion of the horizontal deflection magnetic field, but in the vertical direction, the coil arrangement and the direction of the generated magnetic field are different by 90 ° from the horizontal direction. Only.

FIG. 5 is a schematic view of a main part of another embodiment of the projection type cathode ray tube device according to the present invention, in which 24a and 24a are provided.
Reference numerals b, 24c and 24d denote coils, and 25a and 25b denote coil driving means, and parts corresponding to those in FIG.

In the figure, the convergence yoke 4
Is a ring-shaped core 8 and a coil 2 wound around the core 8.
4a, 24b, 24c, 24d. The coils 24a and 24b have the same winding specifications, the intermediate portions of the coils 24a and 24b are vacant, and the coils 24c and 24d are wound around the vacant portions.

The coils 24a and 24b are connected in series, and the winding directions of the coils 24a and 24b are set so that the coils 24a and 24b generate magnetic fields in the same direction as shown in FIG. 2 (a). ， The connection relation is set. These coils 24a and 24b are coil driving means 2
Driven by 5b. Also, the coils 24c and 24d
Are also connected in series, and the winding directions and connection relationships of the coils 24c and 24d are set so that magnetic fields in different directions are generated from the coils 24c and 24d, as shown in FIG. 2B. Has been done. These coils 24
The coils c and 24d are driven by the coil driving means 25a.

In this structure, if the coils 24a to 24d are simultaneously driven so that the magnetic field generated from the coil 24c is added to the magnetic field generated from the coil 24a to increase the magnetic field, the magnetic field generated from the coil 24b is generated from the coil 24d. Only the generated magnetic field is attenuated and the magnetic field is prevented from being generated. Therefore, in this case, a magnetic field similar to that shown in FIG. 3A is generated. If the direction of the magnetic field generated by the coils 24c and 24d is reversed from the above, a magnetic field similar to that shown in FIG. 3B will be generated.

Therefore, the shape and the raster distortion of the beam spot shown in FIG. 4 are changed by changing the magnitude and direction of the current flowing through the coils 24c and 24d as the vertical deflection progresses, as described above. Distortion can be corrected, and excellent focus performance can be obtained over the entire screen as in the embodiment shown in FIG.

The method of winding the coils 24a to 24d is not limited to the above, and for example, the coil 24a and the coil 24c, and the coil 24b and the coil 24d may be wound in a laminated manner.

Further, although the projection type cathode ray tube 1 in each of the above-mentioned embodiments is of the electromagnetic focusing type, it can be applied to an electrostatic focusing type projection type cathode ray tube device.

Further, in the two embodiments described above, the convergence yoke 4 is of a type in which a toroidal coil is wound around an annular core, but as shown in FIG.
Core 8 with individual protrusions and coils 2 wrapped around each protrusion
6a, 26b, 26c, 26d, the magnetic field 27a,
27b may be formed. The number of protrusions and coils may be any number as long as it is an even number.

FIG. 7 is a cross-sectional view of a main part showing still another embodiment of the projection type Brown device according to the present invention.
Reference numeral 0c is a coil, 31 is a dynamic focus adjusting means, 32 is a convergence correction applying focus adjusting means, and 33 is a static focus adjusting means.

The above-mentioned embodiments relate to the portion of the convergence yoke 4 in FIG. 9, but this embodiment relates to the portion of the electromagnetic focusing device 5 in FIG.

In FIG. 7, an annular permanent magnet 28 is arranged around the outer surface of the projection type cathode-ray tube 1, and three coils 30a, 30b, 30c are provided between the permanent magnet 28 and the outer surface of the projection type cathode-ray tube 1. It is provided. These coils 30a, 30b, 30c form focusing magnetic fields 34a, 34b which are axisymmetric with respect to the tube axis z. Annular yokes 29a and 29b are provided at both ends of the permanent magnet 28.

The coil 30a is driven by the static focus adjusting means 33, and is used for adjusting the static magnetic field due to variations in the magnetization of the permanent magnet 28. The coil 30c is driven by the dynamic focus adjusting means 31, and adjusts the magnetic field according to the vertical and horizontal deflection of the deflection yoke 3. The coil 30b is driven by the convergence correction adaptive focus adjusting means 32, and adjusts the magnetic field according to the correction amount and the correction direction of the convergence yoke 4.

Here, the operation of the coil 30b will be described with reference to FIG. However, FIG. 8 schematically shows the trajectory of the electron beam deflected to a point 2a around the fluorescent screen of the projection cathode ray tube 1.

In the same figure, the trajectory 35b of the electron beam
Shows a trajectory when the convergence yoke 4 deflects in the same direction as the deflection direction of the deflection yoke 3, and is shorter than the electron beam trajectory 35a when the convergence yoke 4 does not deflect. The trajectory 35c of the electron beam is the trajectory when the convergence yoke 4 receives the deflection action in the direction opposite to the deflection direction of the deflection yoke 3, and is longer than the trajectory 35a of the electron beam. As described above, the length of the trajectory of the electron beam varies due to the deflection effect of the convergence yoke 4. Then, in the case of the electron beam trajectory 35b, underfocus, and in the case of the electron beam trajectory 35c,
The focus becomes overfocus, the focus performance deteriorates, and the resolution deteriorates. The deterioration of the focusing performance cannot be prevented only by the dynamic focus adjustment corresponding to the vertical and horizontal deflection by the coil 30c.

The coil 30b is for preventing the deterioration of the focus performance, and the convergence correction adaptive focus adjusting means 32 adjusts the drive amount of the coil 30b according to the convergence correction amount and the correction direction, whereby the dynamic correction is performed. By adjusting the focus, the fluorescent screen 2 can be displayed regardless of the different electron beam trajectories as shown in FIG.
The size of the beam spot at is almost constant. As a result, excellent focus performance can be obtained over the entire screen.

In this embodiment, the coil 3 is provided with a dynamic focus magnetic field corresponding to vertical and horizontal deflection and a dynamic focus magnetic field corresponding to convergence correction.
Although it was generated by separate coils 0c and 30b, the same coil is used, and the drive signals for the respective dynamic focus magnetic fields are combined to drive this common coil. The effect is obtained.

Further, in the embodiment shown in FIGS. 1 and 5, the yoke 29b located on the phosphor screen side can be used as the core 8 of the convergence yoke 4, whereby the focusing and deflecting system can be made more compact. be able to. In this case, the space of the convergence yoke 4 in FIG. 9 is not necessary, so that the electromagnetic focusing device 5 can be brought closer to the fluorescent screen 2 as a result, and as a result, the focusing lens of the electromagnetic focusing device 5 can be formed. It is possible to reduce the image magnification and reduce the beam spot over the entire screen.

Further, this embodiment can be applied to an electrostatic focusing type projection type cathode ray tube device. in this case,
An adjusting unit similar to the coil 30b may be provided outside the neck of the projection type cathode ray tube, or the electrode inside the neck may be driven by the adjusting signal.

[0048]

As described above, according to the present invention,
The distortion of the beam spot shape caused by the non-uniform component of the deflection magnetic field generated by the deflection yoke can be corrected by the convergence yoke, and excellent focus performance can be obtained over the entire screen.

Further, according to the present invention, by performing the dynamic focus adjustment corresponding to the change of the electron beam trajectory which occurs at the time of the convergence correction, it is possible to obtain the excellent focus performance in the entire screen.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part of an embodiment of a projection type cathode ray tube device according to the present invention.

FIG. 2 is a diagram showing a magnetic field generated when a current of the same magnitude is applied to the coil in FIG. 1 and a force acting on an electron beam by the magnetic field.

3 is a diagram showing a magnetic field generated when different currents are applied to the coil in FIG. 1 and a force acting on an electron beam by the magnetic field.

FIG. 4 is a schematic diagram showing a raster distortion and a beam spot shape around a phosphor screen.

FIG. 5 is a main part configuration diagram of another embodiment of the projection type cathode ray tube device according to the present invention.

FIG. 6 is a diagram showing another specific example of the coil installation method in the embodiment shown in FIG.

FIG. 7 is a main part configuration diagram of still another embodiment of the projection type cathode ray tube device according to the present invention.

FIG. 8 is a schematic diagram showing changes in the orbit of an electron beam due to the action of a convergence yoke in a projection type cathode ray tube.

FIG. 9 is a partial cross-sectional view schematically showing the structure of a projection type cathode ray tube device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Projection type cathode ray tube 2 Fluorescent screen 3 Deflecting device 4 Convergence yoke 5 Electromagnetic focusing device 6 Cathode 8 Cores 9a, 9b Coil 10a, 10b Coil driving means 11 Balance adjusting means 12a-12f Beam spot 24a-24d Coil 25a, 25b Coil driving means 26a-26d Coil 28 Annular permanent magnet 29a, 29b Annular yoke 30a-30c Coil 31 Dynamic focus adjusting means 32 Convergence correction application focus adjusting means 33 Static focus adjusting means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuo Asano 3300 Hayano, Mobara-shi, Chiba Hitachi, Ltd. Electronic Device Division

Claims (4)

[Claims] 1. A projection type cathode ray tube apparatus having a deflection yoke for scanning an electron beam, a convergence yoke, and a focusing means for focusing the electron beam, the non-uniform component of a deflection magnetic field generated by the deflection yoke. A projection type cathode ray tube device, characterized in that distortion of a beam spot shape is corrected by a non-uniform component of a deflection magnetic field generated by the convergence yoke. 2. A projection type cathode ray tube apparatus having a deflection yoke for scanning an electron beam, a convergence yoke, and a focusing means for focusing the electron beam, wherein the convergence yoke comprises a quadrupole magnetic field generating means. A projection type cathode ray tube device characterized in that distortion of a beam spot shape caused by an inhomogeneous component of a deflection magnetic field generated by is corrected by the quadrupole magnetic field generating means. 3. A projection type cathode ray tube device having a deflection yoke for scanning an electron beam, a convergence yoke, and a focusing means for focusing the electron beam, wherein the focusing means is arranged according to a scanning position of the electron beam on the fluorescent screen. First dynamic focus adjusting means for changing the strength of the focusing magnetic field, and whether or not the deflection position is corrected by the convergence yoke,
A projection type cathode ray tube device, comprising: a second dynamic focus correction means for changing the strength of the focusing lens according to the direction of correction and the strength of the correction. 4. The focusing means according to claim 1, 2 or 3, wherein the focusing means is an annular permanent magnet having a tube axis of a projection type cathode-ray tube as a central axis, and two permanent magnets arranged on both end surfaces of the permanent magnet. Projection, characterized in that 2n sets of toroidal coils each having an annular yoke and having a yoke located on the phosphor screen side as a core among the two annular yokes are constituent members of a convergence yoke. Shaped CRT device.