JP2003007229A - Cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cathode-ray tube that can suppress generation of moires and which can improve image quality. SOLUTION: The cathode-ray tube comprises an envelope, including a funnel 2 joined to a panel 1, a phosphor screen 4 formed on an inner surface of the panel 1 and provided with a phosphor layer, a shadow mask 3 opposed to the phosphor screen 4 and provided with a plurality of apertures, an electron gun structure 6 arranged in a neck 5 of the funnel 2 to emit electron beams 7 (R, G, B) toward the phosphor screen 4 via the shadow mask 3, and an incident angle varying mechanism 9 and 10 for varying an incident angle to vertical direction Y of the electron beams emitted from the electron gun structure 6, without having to change the incident position thereof on the phosphor layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube device, and more particularly to a shadow mask type color cathode ray tube device.

[0002]

2. Description of the Related Art In a shadow mask type color cathode ray tube device, an electron beam emitted from an electron gun assembly is focused on a phosphor layer in a phosphor screen through a large number of apertures formed in the shadow mask. A color image is displayed. In such a color cathode ray tube device, moire may occur due to interference between the scan lines and the shadow on the phosphor layer due to the bridge in the vertical direction of the shadow mask. This moiré is noticeable in the low current region, but even in the high current region, moiré may occur when the vertical diameter of the beam spot by the electron beam emitted from the electron gun assembly is sufficiently small.

A display device using a color cathode ray tube is mainly used as a display device for a computer and a display device for a television. In the former computer display, moire is reduced by minutely changing the scanning line interval or by changing the focus voltage according to the beam current. In the latter TV display device, the vertical pitch of the shadow mask is set so that moire is unlikely to occur for each tube type, and the focus characteristics (beam profile) of the electron gun assembly are optimally designed. , Moire is reduced.

[0004]

SUMMARY OF THE INVENTION The moire reducing methods in the shadow mask type color cathode ray tube apparatus described above can be summarized as follows.

(1) A method of minutely changing the scanning line interval (Japanese Patent Laid-Open No. 6-326898, etc.) (2) A method of changing the focus voltage according to a change in beam current (luminance) (3) Forming on a shadow mask (4) Method of Optimizing Design of Focus Characteristics of Electron Gun Structure However, each of the above methods has the following drawbacks.

First, in (1), the moiré is reduced by minutely changing the scanning line interval to the extent that the viewer does not care. However, the modulation amount of the scanning line interval depends on the screen size, the resolution, the pitch size of the apertures formed in the shadow mask, and the like, and there are individual differences to the extent that they do not bother. The viewer is not completely flicker-free and the image quality is not degraded.

Regarding (2), the focus voltage is set to the best focus when the beam spot diameter is large and the brightness is high (high current), and the focus voltage is the best focus when the beam spot diameter is small and the brightness is low (low current). The voltage is deviated from the focus voltage. By this,
The moire that is noticeable at low brightness (low current) is reduced. Normally, the focus performance (spot diameter) at low brightness is deteriorated, but the difference from the beam spot diameter at high brightness tends to be small, and this is not considered to be deterioration of resolution. However, when aiming at high brightness and high resolution, moire may occur even at medium to high currents. In this case, if it is attempted to reduce moire with the focus voltage, the resolution will deteriorate.

With respect to (3), the interference with the scanning lines is prevented by changing the vertical pitch of the apertures formed in the shadow mask. However, the vertical pitch of the aperture is limited because it relates to the strength and aperture ratio of the shadow mask, and it is not always possible to effectively reduce moire.

As for (4), the focus voltage is set to medium to high.
When optimized for high brightness, low brightness (low current) will deviate from the optimum voltage for the beam current. At this low brightness, the beam spot diameter is
Although it is enlarged, the electron gun assembly is optimally designed so that the enlarged beam spot diameter is a size that does not cause moire. When the optimum design is performed in this way, the focus performance in the middle to high brightness is also deteriorated. Further, similarly to the method (2), when directing high brightness and high resolution, it is not possible to achieve both moire suppression and resolution improvement. Also,
Since the spot diameter required to prevent the generation of moire differs depending on the tube type, the electron gun assembly is optimally designed for each tube type, resulting in deterioration of productivity.

As described above, it is difficult for the conventional methods to realize the suppression of moire and the improvement of image quality (high brightness / high resolution and flicker-free images) in all tube types.

Therefore, the present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a cathode ray tube device capable of suppressing the generation of moire and improving the image quality. .

[0012]

In order to solve the above-mentioned problems and to achieve the object, a first aspect of the present invention provides an envelope having a panel and a funnel joined to the panel, and an inner surface of the panel. A phosphor screen formed and having a phosphor layer, a shadow mask having a plurality of apertures, which is arranged so as to face the phosphor screen, and arranged in the neck of the funnel. At the same time, an electron gun assembly that emits an electron beam toward the phosphor screen through the shadow mask and a deflection magnetic field that deflects the electron beam emitted from the electron gun assembly in horizontal and vertical directions are generated. In a cathode ray tube device including a deflection yoke, an incident position of an electron beam emitted from the electron gun assembly to enter the phosphor layer can be changed. Without it characterized by comprising an incident angle changing mechanism for changing the incident angle in the vertical direction.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the cathode ray tube device of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a cathode ray tube apparatus according to the present invention, that is, a self-convergence type in-line type color cathode ray tube apparatus, includes a panel 1 and a panel 1.
It has an envelope made up of the funnel 2 integrally joined to. This panel 1 is provided with a phosphor screen 4 on its inner surface, which includes a stripe-shaped or dot-shaped three-color phosphor layer that emits blue, green, and red light. Shadow mask 3
Has a large number of apertures inside and is arranged so as to face the phosphor screen 4.

The in-line type electron gun assembly 6 is provided in the neck 5 corresponding to the small diameter portion of the funnel 2. The electron gun assembly 6 emits three electron beams 7B, 7G, 7R arranged in a row, which includes a center beam 7G passing through the same horizontal plane and a pair of side beams 7B, 7R.

The deflection yoke 8 is mounted from the large diameter portion of the funnel 2 to the neck 5. This deflection yoke 8
Are three electron beams 7B, 7 emitted from the electron gun assembly 6.
An inhomogeneous deflection magnetic field for deflecting G and 7R in the horizontal direction (X) and the vertical direction (Y) is generated. This non-uniform magnetic field is formed by a pincushion type horizontal deflection magnetic field and a barrel type vertical deflection magnetic field.

The three electron beams 7B, 7G and 7R emitted from the electron gun assembly 6 are deflected by the non-uniform magnetic field generated by the deflection yoke 8, and the phosphor screen 4 is passed through the shadow mask 3 in the horizontal and vertical directions. To scan. As a result, a color image is displayed.

The cathode ray tube device further includes auxiliary coil units (incident angle changing mechanism) 9 and 10, as shown in FIGS. These auxiliary coil units 9 and 10 are a pair of magnetic field generating coils 9a and 9b, 10a and 1 arranged to face each other in the horizontal direction X.
It is composed of 0b. These auxiliary coil units 9 and 10 are arranged along the tube axis direction in which the electron beam travels. The attachment positions of these auxiliary coil units 9 and 10 differ depending on the tube type, and the funnel 2 corresponding to the arrangement position of the deflection yoke 8 from the outer surface of the neck 5 corresponding to the cathode position of the electron gun assembly 6 toward the phosphor screen 4. It is preferable to be on the outer surface. Note that, here, an example in which two auxiliary coil units are arranged will be described, but two or more auxiliary coil units may be arranged.

These two auxiliary coil units 9 and 1
0 slightly deflects the electron beam emitted from the electron gun assembly in the opposite directions along the vertical direction Y. For example, when the auxiliary coil unit 9 slightly deflects the electron beam upward along the vertical direction Y, the auxiliary coil unit 1
0 slightly deflects the electron beam slightly deflected downward in the vertical direction Y.

That is, these auxiliary coil units 9 and 10 always generate a reverse magnetic field so as to cancel the upper and lower minute deflections of the electron beams performed by the auxiliary coil units 9 and 10 on the phosphor screen 4. Accordingly, as compared with the normal state, that is, the state in which the auxiliary coil units 9 and 10 are not operated, the incident position of the electron beam emitted from the electron gun assembly 7 on the phosphor layer of the phosphor screen 4 is not changed, It is possible to change the incident angle in the vertical direction Y.

In the normal state, as shown in FIG. 3, when the axis 11 of the trajectory of the electron beam 7a emitted from the electron gun assembly is tilted by θv in the vertical direction Y with respect to the tube axis Z, the electron beam 7a. Enters the phosphor screen 4 at a deflection angle θv in the vertical direction through the shadow mask 3. In this case, the beam spot of the electron beam reaching the phosphor screen 4 causes the part 4a of the phosphor layer to emit light, and the shadow of the bridge 3b in the shadow mask 3 prevents the part 4b of the phosphor layer from emitting light. A part is formed.

At the time of high current (that is, at high brightness), as shown in FIG.
As shown in, the phosphor layer 4a of the phosphor screen 4 emits light by the relatively large beam spot 12a.
At this time, the bridge 3 projected on the phosphor screen 4
The shadow of b forms the non-light emitting portion 4b.

Further, when the current is low (that is, when the brightness is low), as shown in FIG.
2b causes the phosphor layer 4a of the phosphor screen 4 to emit light. Further, at this time, the shadow of the bridge 3b projected on the phosphor screen 4 forms the non-light emitting portion 4b.

When the shadows of the bridge are formed periodically, there is a risk of interfering with the scanning lines and causing moire. Therefore, by making the shadow of the bridge inconspicuous or changing the regularity of the shadow of the bridge, it is possible to reduce the occurrence of moire due to interference with the scanning line.

First, a method of suppressing the generation of moire by making the shadow of the bridge inconspicuous will be described.

That is, in this method, as shown in FIG. 6, while the beam spot on the phosphor screen 4 scans one phosphor layer in the horizontal direction X, at least two electron beams 7a1 and 7a2 is made incident on the same phosphor layer.

For example, at the first timing of scanning one phosphor layer, the electron beam emitted from the electron gun assembly 6 is
It is slightly deflected downward along the vertical direction Y by the auxiliary coil unit 9 in the front stage, and further along the vertical direction Y by the auxiliary coil unit 10 in the rear stage so as to maintain the incident position on the phosphor layer in the normal state. It is slightly deflected upward.

As a result, the electron beam 7a1 is incident on the phosphor screen 4 with an inclination of (-θ ₁ ) in the vertical direction Y with respect to the deflection angle θv of the electron beam in the normal state in the vertical direction Y. In this case, the beam spot of the electron beam 7a1 reaching the phosphor screen 4 causes the part 4a of the phosphor layer to emit light, and due to the shadow of the bridge 3b in the shadow mask 3, the part 4b1 of the phosphor layer does not emit light. A shadow part is formed.

Next, at the second timing of scanning the same phosphor layer, the electron beam emitted from the electron gun assembly 6 is slightly deflected upward in the vertical direction Y by the auxiliary coil unit 9 in the preceding stage, Further, the auxiliary coil unit 10 in the latter stage is slightly deflected downward along the vertical direction Y so as to maintain the incident position on the phosphor layer in the normal state.

As a result, the electron beam 7a2 is incident on the phosphor screen 4 with a tilt of (+ θ ₂ ) in the vertical direction Y with respect to the deflection angle θv of the electron beam in the normal state in the vertical direction Y. In this case, the beam spot of the electron beam 7a1 reaching the phosphor screen 4 causes the part 4a of the phosphor layer to emit light, and due to the shadow of the bridge 3b in the shadow mask 3, the part 4b2 of the phosphor layer does not emit light. A shadow part is formed. The position of the beam spot that reaches the phosphor layer at the second timing is the same as the position at the first timing and is constant. The shadow portion 4b1 at the first timing is emitted at the second timing, and the shadow portion 4b1 at the second timing is emitted.
b2 is emitted at the first timing.

Therefore, apparently, the phosphor layer of the phosphor screen 4 to which the beam spot has reached almost entirely emits light, and the shadow of the bridge of the shadow mask 3 can be made inconspicuous.

At high current (that is, at high brightness), for example, as shown in FIG. 7, a relatively large beam spot 1
2a allows the phosphor layer 4a of the phosphor screen 4 to emit light without forming the shadow of the bridge 3b.

When the current is low (that is, when the brightness is low), for example, as shown in FIG. 8, a relatively small beam spot 12b does not form a shadow of the bridge 3b, and the fluorescence of the phosphor screen 4 is reduced. The body layer 4a emits light.

In order to realize the above method,
The following currents are supplied to the auxiliary coil units 9 and 10.

That is, the auxiliary coil units 9 and 10
When the cycle of the electric current supplied to the device, that is, the incident angle changing frequency is fa (Hz), the incident angle changing frequency fa is set as follows, for example.

Fa> (L / SS) × fh where L (mm) is the effective screen size in the horizontal direction of the phosphor screen 4, and SS (mm) is the electron beam focused on the phosphor screen 4. Is the horizontal spot size, and fh (Hz) is the horizontal deflection frequency of the electron beam by the deflection yoke 8.

For example, when a current having an incident angle changing frequency as shown in FIG. 9A is supplied to the auxiliary coil unit 9 for a horizontal deflection frequency fh as shown in FIG. A current having an incident angle changing frequency as shown in FIG. 9B is supplied to the coil unit 10. The magnitude of the current supplied to each auxiliary coil unit and the incident angle changing frequency are set so that one auxiliary coil unit (auxiliary coil unit 9) makes the electron beam emitted from the electron gun assembly in one direction along the vertical direction. When it is biased to
The other auxiliary coil unit (auxiliary coil unit 10) deflects the electron beam in the other direction along the vertical direction (opposite to the one direction) so as to cancel the deflection of the electron beam by the one auxiliary coil unit. Is set to do.

Further, the electron beam 7a1 tilted downward by θ _{1 with} respect to the deflection angle θv in the vertical direction Y of the electron beam in the normal state, and θ ₂ upward with respect to the deflection angle θv.
When the electron beam 7a2 tilted only by the angle is made incident on the phosphor screen 4, the following relationship is set, for example.

Tan (θv−θ ₁ ) = (l−d1) / q tan (θv + θ ₂ ) = (l + d2) / q d1 + d2 = d l = q + tan (θv) where θv (°) is in the vertical direction Y. Deflection angle, d1
(Mm) is the difference in the position of the bridge shadow between θ ₁ o'clock and the normal state, d 2 (mm) is the difference in the position of the bridge shadow between θ ₂ o'clock and the normal state, and d (mm) is the shadow mask Is the bridge width in the vertical direction Y, and q (mm) is the distance between the shadow mask and the phosphor screen.

Here, by setting d1 = d2 = d / 2, as shown in FIGS. 7 and 8, an electron beam is made to enter the same phosphor layer at the same incident position of at least two different trajectories. It is possible to make the shadow of the bridge of the shadow mask the most inconspicuous. Further, even if the beam spot size is the same, it is possible to expand the light emitting area as compared with the normal state by suppressing the generation of the shadow of the bridge. Therefore, it is possible to improve the brightness as compared with the normal state even with the same current value.

Next, a method of changing the regularity of the shadow of the bridge will be described.

That is, in this method, the incident angle changing frequency fa (Hz) of the current supplied to the auxiliary coil units 9 and 10 is set as follows.

(L / SS) × fh>fa> fh By setting the incident angle changing frequency fa within the above range, the position of the shadow projected on the phosphor screen 4 by the bridge 3b of the shadow mask 3 is shifted. be able to.

At this time, for example, with respect to the horizontal deflection frequency fh as shown in FIG. 9E, the auxiliary coil unit 9 is supplied with a current having an incident angle changing frequency as shown in FIG. 9C. In this case, the auxiliary coil unit 10 is supplied with a current having an incident angle changing frequency as shown in FIG.

In this method, at least the scanning angle of adjacent scanning lines is changed in phase, or the incident angle is changed at intervals of one scanning line or more. Thereby, the regularity (periodicity) of the shadow of the bridge 3b in the shadow mask 3 projected on the phosphor screen 4 can be changed, and the occurrence of moire due to the interference with the scanning line can be suppressed.

According to this method, it is not necessary to make a plurality of electron beams incident on the same phosphor layer at different incident angles,
The current supplied to the auxiliary coil unit does not require a very high incident angle changing frequency as compared with the method described above. Therefore, since it is only necessary to supply a current having a relatively low frequency to the auxiliary coil unit, a large load is not applied to the circuit and the cost is not increased.

As described above, according to the cathode ray tube device of the present invention, when the electron beam emitted from the electron gun assembly is scanned and is made incident on the phosphor layer of the phosphor screen through the shadow mask, the fluorescent light is emitted. The incident angle in the vertical direction of the incident electron beam trajectory is changed without changing the incident position of the electron beam incident on the body layer.

As a result, the shadow on the phosphor screen due to the bridge of the shadow mask is made inconspicuous, or the regularity of the shadow of the bridge is broken to suppress the phenomenon of interference with the scanning line and suppress the occurrence of moire. be able to.

Therefore, it is possible to suppress the occurrence of moire and improve the image quality without deteriorating the focusing performance of the electron beam and without changing the screen display position or the beam spot size.

[0050]

As described above, according to the present invention, it is possible to provide a cathode ray tube device capable of suppressing the occurrence of moire and improving the image quality.

[Brief description of drawings]

FIG. 1 is a horizontal sectional view schematically showing the structure of an in-line type color cathode ray tube device according to the cathode ray tube device of the present invention.

FIG. 2 is a vertical cross-sectional view schematically showing the structure of the color cathode ray tube device shown in FIG.

FIG. 3 is a diagram showing an electron beam trajectory in a normal state and a light emitting state of a phosphor layer on a phosphor screen at this time.

FIG. 4 is a diagram for explaining a beam spot size at a high current in a normal state and a shadow formation due to a bridge of a shadow mask.

FIG. 5 is a diagram for explaining a beam spot size at a low current in a normal state and a shadow formation due to a bridge of a shadow mask.

FIG. 6 is a diagram for explaining a method of making a shadow due to a bridge of a shadow mask inconspicuous, showing an electron beam trajectory and a light emitting state of a phosphor layer on a phosphor screen at this time. is there.

7 is a diagram for explaining a beam spot size and a light emitting state of a trend layer when a high current is applied in the state shown in FIG. 6;

FIG. 8 is a diagram for explaining a beam spot size and a light emitting state of the trend layer when the current is low in the state shown in FIG. 6;

9 (a) shows the incident angle changing frequency of the current supplied to one auxiliary coil unit in order to make the shadow of the bridge inconspicuous, and FIG. 9 (b) shows at this time. 9C shows the incident angle changing frequency of the current supplied to the other auxiliary coil unit, and FIG. 9C shows the incident angle changing frequency of the current supplied to one auxiliary coil unit in order to change the regularity of the shadow of the bridge. The frequency is shown in FIG. 9 (d).
Indicates the incident angle changing frequency of the current supplied to the other auxiliary coil unit at this time, and FIG. 9E shows the horizontal deflection frequency of the electron beam.

[Explanation of symbols]

1 ... panel 2 ... Funnel 3 ... Shadow mask 4 ... Phosphor screen 5 ... neck 6 ... Electron gun structure 7 (R, G, B) ... Electron beam 8 ... Deflection yoke 9 ... Auxiliary coil unit 10 ... Auxiliary coil unit

Claims (6)

[Claims] 1. An envelope having a panel and a funnel joined to the panel, a phosphor screen formed on an inner surface of the panel and having a phosphor layer, and the phosphor screen. A shadow mask having a plurality of apertures, which are arranged to face each other, and arranged in the neck of the funnel,
An electron gun assembly that emits an electron beam toward the phosphor screen through the shadow mask, and a deflection yoke that generates a deflection magnetic field that deflects the electron beam emitted from the electron gun assembly in horizontal and vertical directions. In the cathode ray tube device including, an incident angle changing mechanism that changes an incident angle in a vertical direction without changing an incident position of an electron beam emitted from the electron gun assembly into the phosphor layer. And a cathode ray tube device. 2. The cathode ray tube apparatus according to claim 1, wherein the incident angle changing mechanism is a coil unit composed of a pair of magnetic field generating coils arranged to face each other in the horizontal direction. 3. The cathode ray tube apparatus according to claim 1, wherein two or more of the incident angle changing mechanisms are arranged along the tube axis direction. 4. When the first incident angle changing mechanism deflects the electron beam emitted from the electron gun assembly in one direction along the vertical direction, the electron beam emitted by the first incident angle changing mechanism is changed. The cathode ray tube according to claim 3, wherein the second incident angle changing mechanism deflects the electron beam emitted from the electron gun assembly in the other direction along the vertical direction so as to cancel the deflection. apparatus. 5. The effective screen size in the horizontal direction of the phosphor screen is L (mm), and the horizontal spot size of the electron beam focused on the phosphor screen is S.
S (mm), where fh (Hz) is the horizontal deflection frequency of the electron beam by the deflection yoke, the incident angle changing frequency fa (Hz) of the electron beam by the incident angle changing mechanism is fa> (L / SS) The cathode ray tube device according to claim 1, wherein the cathode ray tube device is set so as to satisfy xfh. 6. The effective screen size in the horizontal direction of the phosphor screen is L (mm), and the horizontal spot size of the electron beam focused on the phosphor screen is S.
S (mm), where fh (Hz) is the horizontal deflection frequency of the electron beam by the deflection yoke, fa (Hz) is the incident angle changing frequency of the electron beam by the incident angle changing mechanism, which is (L / SS) × The cathode ray tube device according to claim 1, wherein the cathode ray tube device is set so as to satisfy fh>fa> fh.