JPH0646812B2 - Color picture tube device - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to an improvement of an in-line type color picture tube device.

[Technical background of the invention]

The envelope of the color picture tube has a neck that houses three electron guns,
It is composed of a face plate having a fluorescent screen and a funnel interposed between the neck and the face plate.

The three-electron gun is mounted in the neck in a horizontal direction in an in-line shape, and the emitted electron beam is made to strike the fluorescent surface on which the fluorescent material layer is formed to emit light. In order to realize the emission of the phosphor layer with good color reproduction, it is necessary to selectively project the electron beam onto a predetermined phosphor layer. Therefore, a shadow mask with a large number of apertures is close to the face plate. Are placed.

The in-line electron gun is designed to generate three electron beams on a common plane by a cathode and concentrate these three electron beams in the vicinity of the face plate. A method of concentrating three electron beams is described in, for example, US Pat. No. 2,957,106.
There is a technique in which the electron beam emitted from the cathode is inclined from the beginning as shown in Japanese Patent No. 3772554, and as shown in US Pat. There is a technique for concentrating the electron beam by slightly shifting the holes on both sides of the electrode of the electron beam passage holes to the outside from the central axis of the electron gun, both of which are widely adopted. ing.

In order to display a television image on the screen (fluorescent screen) of a color picture tube, a deflecting device for scanning the electron beam emitted from the electron gun over the entire fluorescent screen is required. This is located outside the funnel cone. Mounted. The deflection device basically has a horizontal deflection coil for generating a horizontal deflection magnetic field for horizontally deflecting the electron beam and a vertical deflection coil for generating a vertical deflection magnetic field for vertically deflecting the electron beam. ing. In an actual color picture tube device, when the electron beam is deflected, the concentration of the three electron beam spots on the face plate collapses. Therefore, measures are taken to prevent this concentration collapse. This is called a convergence-free system, in which the horizontal deflection magnetic field is a pincushion type vertical deflection magnetic field and the vertical deflection magnetic field is a barrel type so that three electron beams are concentrated on the entire phosphor screen. As a result, this system eliminates the need for a parabola current generation circuit for convergence correction and a convergence yoke for generating a convergence correction magnetic field, which results in many effects such as cost reduction and productivity improvement.

[Problems of background technology]

As described above, the quality of the color CRT has been improved by adopting many development techniques, but new problems are being highlighted as the size of the tube becomes widespread.

That is, the beam spot emitted from the three-electron gun and concentrated on the face plate exhibits only a circular core as shown in FIG. 4 (a) at the center of the screen which is not deflected, but is deflected. At the periphery of the screen, a flattened core and flare spread vertically are provided as shown in Fig. 4 (b). As a result, the size of the electron beam of the electron beam increases at the peripheral portion of the screen, and the focusing performance and resolution deteriorate.

Specifically, in the case of a 20-inch 90-degree deflection tube, if the horizontal dimension of the core is C _H and the vertical dimension is C _V , C _H
= C _V = 1.0 mm, but C _H = 20 mm, C _V at the horizontal deflection end
= 0.3 mm, which is extremely flat. Also, the dimension F _V from the upper end to the lower end of the flare is 1.5 mm. This dimension is a value only when the electron beam is horizontally deflected, but is further distorted at the corner of the screen where vertical deflection is applied.

[Object of the Invention]

The present invention has been made to solve the above-mentioned conventional drawbacks, and an object of the present invention is to provide a color picture tube device capable of obtaining bright high resolution over the entire screen while reducing the distortion of the electron beam spot at the peripheral portion of the screen. And

[Outline of Invention]

The present invention provides a neck in which three electron guns are horizontally installed inline, and three colors of red, green, and blue are formed by a bombardment of an electron beam emitted from the electron gun on the inner surface of the neck connected to the neck through a funnel. A plate having a phosphor surface on which a phosphor layer for emitting light is regularly formed and deposited, and a large number of apertures arranged close to the face plate to selectively project the electron beam onto the phosphor layer. A color picture tube having a shadow mask and a deflection device which is mounted on the outer wall of the funnel and generates a deflection magnetic field for horizontally deflecting an electron beam emitted from the electron gun and a deflection magnetic field for vertically deflecting the electron beam. The electron beam emitted from the electron gun is substantially parallel. The horizontal deflection magnetic field forms a substantially uniform magnetic field distribution, and the vertical deflection magnetic field forms a barrel type magnetic field distribution. Further, the half-value width a of the magnetic flux density distribution on the tube axis of the horizontal deflection magnetic field is the distance A from the center of the density distribution to the phosphor screen.
It is included in the range of 0.1 to 0.4 times. When a is 0.2 to 0.3 times as large as A, a better effect is exhibited. The best characteristics are obtained when a is about 0.25 times A.

Furthermore, the transfer signals to the three-electron gun have mutually controlled time lags, whereby the three-electron beams are concentrated on the face plate or near the plate.

The color picture tube device of the present invention having the above configuration will be described in more detail based on the results of experiments conducted by the inventor.

The inventors have paid attention to the fact that the horizontal deflection magnetic field is the pincushion type, which is the main cause of the distortion of the electron beam spot around the screen, and tried to make the horizontal deflection magnetic field uniform. FIG. 5 shows the electron beam spot shapes at the center and the periphery of the screen in the case of a uniform horizontal deflection magnetic field as shown in FIG. 2 (a) with a 20 inch 90 ° deflection tube.
C _H = 1.5 mm and C _V = 0.6 mm, showing that the shape of the core has been greatly improved.

However, this electron beam spot shape is not enough.

The inventor further conducted experiments, and found that the shape of the flare becomes better when a predetermined relationship is established between the magnetic flux density distribution of the deflection magnetic field and the size of the color picture tube.

FIG. 3 is a diagram showing the relationship between the magnetic flux density distribution on the tube axis of the uniform deflection horizontal deflection magnetic field and the distance from the center of this distribution to the phosphor screen.

Here, the position showing the maximum value B _P of the magnetic flux density distribution is defined as the center of the density distribution, and the length determined by the half-width of the maximum value B _P is defined as the magnetic path length a, and the distance from the center of the density distribution to the face plate is defined. Be A. As shown in FIG. 5, if the horizontal dimension of flare is F _H and the vertical dimension is F _V , then a / A and F _V / F
It was found that there is a relationship with _H as shown in Fig. 6.
On the other hand, it is known that the value of F _V / F _H needs to be 0.5 or more and 2.0 or less when evaluated practically.
When applied to the figure, the practical range for a / A is 0.1 or more and 0.4 or less. The more preferable range of a / A is 0.2 to 0.3. The most ideal state is obtained when a / A≈0.25, and the flare is circular and the smallest.

FIG. 7 shows electron beam spot shapes at the center of the screen and the peripheral portion of the screen when a / A≈0.25. In FIG. 7, the electron beam spot shape (b) at the peripheral portion of the screen can be further improved by adjusting the focal length of the electron lens of the electron gun at the screen edge portion. It is improved as shown in the figure.

The above configuration improves the electron beam spot shape. On the other hand, regarding the concentration of the three electron beams, the three electron beams emitted from the electron gun are made substantially parallel by the configuration of the present invention, and the signals fed into the three electron guns have mutually controlled time lags. By doing so, the electron beam is concentrated on the entire face plate.

This method will be described. If signals are simultaneously sent to the three electron guns, the electron beam spots on the face plate are separated from each other by a certain amount Δ. However, in this method, the signal transfer time to the second electron gun is delayed by τ with respect to the signal transfer time to the first electron gun, and the signal transfer time to the second electron gun is set to the third time. The signal transfer time to the electron gun is delayed by τ. Here, if the horizontal width of the screen is H, the horizontal deflection frequency is f _H , and the constant determined by overscan is C, the delay time τ is Thus, the electron beam spot can be concentrated over the entire screen.

In the present invention, since the deviation amount Δ of the three electron beam spots is one factor, it is preferable to keep this Δ constant over the entire screen. For that purpose, the vertical deflection magnetic field needs to be barrel type. There is.

The effect of the barrel-shaped magnetic field on the displacement Δ is given by ∫H ₂ Y (ZZ _S ) dZ ...... (1). Where H ₂ is a coefficient that indicates the inhomogeneity of the magnetic field. Is defined by Y is the amount of the beam on the tube axis of the color picture tube, and increases as it approaches the face plate. Z _S represents the distance from the face plate to the deflection start point.
Therefore, the larger Y is, that is, the closer the deflection magnetic field is to the face plate, the greater the effect that the barrel magnetic field has on the deviation amount Δ.

On the other hand, the amount of flare generated is proportional to ∫ H ₂ Y (ZZ _S ) ² dZ… (2). This formula (2) has the effect of (ZZ _S ) added more than the formula (1). This indicates that flare is generated uniformly regardless of the position in the magnetic field. Therefore, it is important to form a barrel-shaped magnetic field on the face plate side as much as possible in order to keep the amount of deviation Δ constant with a minimum nonuniform magnetic field while suppressing the occurrence of flare as much as possible.

Example of Invention

The present invention will be described below based on examples. FIG. 1 is a schematic sectional view of a 20-inch 90-degree deflection color picture tube device of the present invention.

(1) is a face plate, (2) is a funnel, and (4) is a neck, both made of glass. Face plate (1)
Phosphor dots or phosphor stripes that emit red, green, and blue colors are regularly arranged on the inner surface, and a phosphor screen for displaying images is displayed.
Form (5). A shadow mask (6) is arranged in close proximity to the phosphor screen (5). The shadow mask (6) is usually made of a thin iron plate with a dome shape similar to the inner surface of the face plate (1). It has a large number of open holes.

Inside the neck (4) are three electron guns corresponding to the three colors red, green and blue
(7) is enclosed. These 3 electron guns are arranged in a line in the horizontal direction, and the emitted electron beams are about 6.6m from each other.
It is configured to be parallel with an interval of m. Each electron gun is composed of a cathode control electrode, a closing electrode, a focusing electrode, and a high-voltage electrode of an electron beam generation source, to which a predetermined voltage is applied. The high-voltage electrode voltage is usually 25 kV, which is an extremely high voltage, and the inside of the color tube is maintained at a constant voltage of 25 kV.

The vicinity of the neck (4) connection part of the funnel (2) is called a cone part (3), and the deflecting device (9) is usually attached to this part.

The deflecting device is a magnetic field for horizontally deflecting the electron beam, and a horizontal deflection coil for generating a uniform magnetic field as shown in FIG. 2 (a) and a magnetic field for vertically deflecting the magnetic field.
It consists of a vertical deflection coil that generates a barrel-shaped magnetic field as shown in (b). The deflection coil is designed so that the half width a of the magnetic flux density distribution on the tube axis of the horizontal deflection magnetic field and the vertical deflection magnetic field is 0.25 times the distance A from the center of the density distribution to the phosphor screen.

The width of the screen (fluorescent screen) of the 20-inch 90-degree deflection tube is about 400 mm
When the horizontal deflection frequency is 15.75 kHz, the electron beam spot deviation amount Δ on the screen is 6.6 mm, and the constant C is 0.75, the mutual delay time of the signals transferred to the three electron guns is about 0.8 μsec.

It has been confirmed that the color picture tube device configured as described above has very little distortion of the core and flare not only at the center of the screen but also at the periphery of the screen, is bright over the entire screen, and has good resolution.

As another example, a 26-inch 110-degree deflection tube is used and other conditions are the same as those in the above-mentioned example, and when a / A is 0.1 and 0.4.
When the color picture tube device was evaluated for the above case, it showed better characteristics than the conventional method. a / A is 0.2 ~
When 0.3, the characteristics were further improved.

In the above description, the electron beam in the non-deflected state has been described as being substantially parallel, but this naturally includes geometrical parallelism, and a fixed delay time is given to the signal to perform color misregistration correction. It is natural that the three electron beams in the color picture tube in the non-deflected state are in a non-concentrated state and do not substantially coincide with each other unless the gist thereof is deviated.

According to the present invention, the horizontal deflection magnetic field distribution forms a substantially uniform magnetic field distribution, and the half-value width of the magnetic flux density distribution on the tube axis of the horizontal deflection magnetic field distribution is measured from the center of this density distribution to the phosphor screen. Distance
It is included in the range of 0.1 to 0.4 times, and by making the transfer signals to the three electron guns have mutually controlled time lags, the distortion of the electron beam spot at the peripheral portion of the screen is reduced,
A bright high resolution is obtained over the entire screen.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a color picture tube device of the present invention, and FIG.
FIG. 3 is a diagram for explaining a deflection magnetic field of a deflection device according to the present invention, FIG. 3 is a diagram for explaining a magnetic flux density distribution on a tube axis of a horizontal deflection magnetic field according to the present invention, and FIG. 4 is an electron beam spot in a conventional example. FIGS. 5A, 5B, 7 and 8 are views for explaining the shape, and FIGS.
FIG. 6 is a diagram for explaining the relationship between the horizontal deflection magnetic field and the like and the electron beam spot shape according to the present invention. 1 ... Face plate, 2 ... Funnel, 4 ... Neck, 5 ... Phosphor screen, 6 ... Shadow mask, 7 ... Electron gun

Claims (3)

[Claims] 1. A neck in which three electron guns are horizontally installed inline, and a red, green, and blue neck 3 connected to the neck through a funnel and struck by an electron beam emitted from the electron gun to the inner surface. A face plate having a phosphor surface on which phosphor layers emitting light of different colors are regularly formed and deposited, and a large number of apertures arranged close to the face plate to selectively project the electron beam onto the phosphor layer. A color picture tube having a shadow mask having an outer wall and a deflection device which is mounted on the outer wall of the funnel and generates a horizontal deflection magnetic field for horizontally deflecting an electron beam emitted from the electron gun and a vertical deflection magnetic field for vertically deflecting the electron beam. In the apparatus, the three electron beams emitted from the electron gun are substantially parallel to each other, the horizontal deflection magnetic field forms a substantially uniform magnetic field distribution, and the vertical deflection magnetic field is generated. The field forms a barrel-shaped magnetic field distribution, and the half-value width a of the magnetic flux density distribution on the tube axis of the horizontal deflection magnetic field.
Is 0.1 of the distance A from the center of the density distribution to the phosphor screen.
It is included in the range of up to 0.4 times, and the transfer signals to the three electron guns have mutually controlled time lags so that the three electron beams are concentrated on or near the face plate. Color picture tube device characterized in that 2. The full width at half maximum a of the magnetic flux density distribution on the tube axis of the horizontal deflection magnetic field is included in a range of 0.2 to 0.3 times the distance A from the center of the density distribution to the phosphor screen. A color picture tube device according to claim 1. 3. The color picture tube device according to claim 1, wherein the vertical deflection magnetic field has a barrel-shaped magnetic field distribution at least on the screen side.