JPS6143814B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a color picture tube, and more particularly to an in-line shadow mask type color picture tube. A shadow mask type color picture tube has red, green, and blue luminescent bodies formed on the inner surface of the panel arranged densely so that they are in contact with each other. Maximum light and color purity can be obtained when the light passes through the color sorting part of the shadow mask placed on the panel, aligns with the phosphor on the inner surface of the panel, and hits the designated phosphor. , thereby forming an image. FIG. 1 is an explanatory diagram of the operation of a color picture tube. As shown in FIG. 1, the distance between the center beam 1 and the side beams 2 and 3 on the deflection center plane is S, the distance between the deflection center and the mask 4 is P, and the distance between the mask 4 and the panel 5 is
The distance between the center of deflection and panel 5 is q, and the distance between the center of deflection and panel 5 is l.
shall be. In particular, let the management values be S ₀ , P ₀ , q ₀ , and l ₀ . If the distance W ₀ between phosphors of the same color is the pitch h of the holes in the mask 4, then W ₀ = l ₀ /P ₀ h ₀ ...(1) The distance μ ₀ between adjacent phosphors is μ ₀ = q ₀ / P ₀ S ₀ ...(2) In order to arrange the phosphors so that they are adjacent to each other, W ₀ =3μ ₀ ...(3). From the above relationship, the following relational expression can be obtained on the tube axis: qn=hl ₀ /3S ₀ (4). In the conventionally known color picture tube, the distance q ₀ dimension between the mask 4 and the panel 5 on the tube axis is set to the value given by equation (4). Also, so that the relationship of equation (3) holds in the surrounding area, the inner curvature radius Rp of the panel is
The radius of curvature Rm of the mask is selected with this in mind. However, with an in-line color picture tube,
With the radius of curvature Rm of a single mask, the relationship between the distance w between phosphors of the same color and the distance μ between adjacent phosphors is not constant but varies depending on the location of the panel. This relationship will be defined as shown in the following equation, and g will be called the grouping ratio. 3μ/w=g (5) When g is smaller than 1, it is called grouping, and when g is larger than 1, it is called degrouping. In the case of grouping, the minimum value of μ is from Figure 2 a. μmin = μ = w (g/3) (g≦1) ...(6) In the case of degrouping, the minimum value of μ is from Figure 2 b. w-2/3gw=w(1-2/3g) (g≧1)
… (7) becomes. Therefore, μmin is the same in the case of 2n% grouping and in the case of n% degrouping. Since the value of g cannot be made constant over the entire surface with the conventional single mask curvature Rm, Rm is determined so that the grouping amount is twice the degrouping amount. In this case, the 20″90° ball will result in 3% degrouping and 6% grouping,
It has the disadvantage that the beam alignment deteriorates and the color purity decreases. The present invention was made in view of the above-mentioned drawbacks of the conventional art, and it is an object of the present invention to provide a color picture tube with improved beam arrangement by bringing the grouping ratio g closer to 1. In order to achieve the above object, the present invention is characterized in that it is not a spherical mask having a single mask radius of curvature Rm, but an aspherical mask expressed by a quartic equation of x and y. Embodiments of the present invention will be described below based on the drawings.
FIG. 3 is an explanatory diagram for determining the radius of curvature of the mask. In FIG. 3, the Z axis is taken from the central beam 1 in the tube axis direction, the x axis is taken in the long axis direction of the mask, and the y axis is taken in the short axis direction of the mask. When the vector from the center beam 1 to the side beam 3 is 〓 on the center plane of deflection, and the beam is deflected in the direction β. 〓=Scos・e ⁱ 〓+Ssin・e ⁱ 〓/i…(8). Let δ be the angle between the tangent on the fluorescent surface 5a on which the beam is projected and the plane perpendicular to the Z axis, and the vector 〓
is projected onto the phosphor surface 5a through the mask 4, the vector μι of the spacing between adjacent phosphors is expressed as μι=Scos・q/P・cosβ/cos(β−δ)e
ⁱ 〓 +Ssin・q/P・e ⁱ 〓/i …(9) Taking the real part Reμι of μι, ∴ Reμι=(sin ² +cos ²・cosβ/cos(β
-δ))q/P S...(10) δ is the inner curvature of the panel, and δ=β-arcsin {(Rp-l ₀ /Rp) sinβ}...(
11) Reμι=Reμι｜〓 From ₌₀ (sin ² + cos ² cos β/cos (β-δ)) q/P
S = q ₀ / P ₀ S ₀ …(12) ∴ P/q = (sin ² + cos ² cos β/cos (β-
δ))・P ₀ S/q ₀ S ₀ S…(13) Here, l=sin δ/sin βRp…(14) q=l−P…(15) In the above formula (11), Rp, l ₀ are It is known, and if β is given, δ can be found. Also, formula (13)
In, P ₀ , q ₀ , S ₀ , and S are known, so
The value of P/q for β is determined. Therefore, the grouping ratio g can be determined using equations (14) and (15). As described above, q can be found for β, and the mask curved surface can be known. Note that there is an important value of β that influences the curved surface of the mask. To investigate this, we investigated the grouping ratio g for the case where the mask curved surface was a spherical surface using a 20" 90° inline sphere. As shown in Figure 4, 6% grouping occurred at the center of the short side and 6% at the center of the long side. 2% degrouping is performed.The most degrouping location is the midpoint between the center of the long side and the corner, and has a degrouping amount of 3%.Therefore, the important point for determining the mask surface is 1 shown in Figure 5. You can select 9 points ~9. Take the 9th point in the effective area as far away from the center of the mask as possible. Obtain the q dimension for these 9 points using the method described above, and calculate the distance between the center plane of the mask and these points. Calculate the heights M ₁ to _{M 9} (see Figure 6) of the mask surface.If the long axis of the mask is the x axis, the short axis is the y axis, and the height of the mask surface is M (x, y). ,M
Since (x, y) is symmetrical about the x and y axes, M(x, y) = M(-x, y) = M(x, -y) = M(-x, -y) …(16).

[Table] M(x, y) that satisfies equation (16) is x and y
_{Since it} ^is _an ^{even function} _{of _ _} ^{_ _} _{_} ^{_ _} _{_} ⁴ y ² + c ₂₂ x ⁴ y ⁴
…(18) Here, a ₁ , a ₂ , b ₁ , b ₂ , c ₁₁ , c ₁₂ , c ₂₁ , c ₂₂ is obtained by inserting the condition of equation (17) into equation (18), and a ₁ , a ₂ , _b1 ,
b ₂ , c ₁₁ , c ₁₂ , c ₂₁ , and c ₂₂ can be found by solving simultaneous linear equations. [a ₁ x ² +
The two terms [a ₂ x ⁴ ] indicate the mask surface on the long axis, and similarly the two terms [b ₁ y ² +b ₂ y ⁴ ] indicate the mask surface on the short axis. (c ₁₁ x ² y ² + c ₁₂ x ² y ⁴ + c ₂₁ x ⁴ y ² + c ₂₂ x ⁴ y ⁴ ) 4
The term is the mask position M(x, O) of point (x, O) at point (x, y) and the mask position M of point (O, y)
(O, y) (M(x, O) + M(O, y) =
a ₁ x ² + a ₂ x ⁴ + b ₁ y ² + b ₂ y ⁴ ). In addition, b ₁ /a ₁ is a value that indicates the difference in curvature in the X direction and Y direction, and represents the degree of asphericity,
Its value shall be between 0.90 and 0.95. For example, in the case of a 20″ 90° uniform pitch mask, use this method to find the coefficients of equation (18). _{x 0} = 80 mm, y ₀
= 60 mm, and find the height of the mask surface at 9 points: M ₁ = 0 M ₂ = 4.43 M ₃ = 17.90 M ₄ = 2.32 M ₅ = 6.70 M ₆ = 20.0 M ₇ = 9.33 M ₈ = 13.72 M ₉ = 27.15 Therefore, the coefficients of equation (18) are a ₁ = 6.898×10 ^-4 a ₂ = 3.662×10 ^-10 b ₁ = 6.433×10 ^-4 b ₁ = 3.215×10 ^-4 c ₁₁ = −2.628×10 ^{- 9} _{c 12} = 5.305×10 ^-10 _{c 21} = 7.234× ^{10 -11} c ₂₂ = 4.823 In this case, the grouping ratio g could be set to 0.99 to 1.00 not only at the nine points but also over the entire surface.
Note that the above a ₁ to c ₂₂ vary depending on the size of the shadow mask, but are generally as follows. _{a 1} = 6 to ₉ × ^{10 -4 a} _{1 = 3} ^{to 9} It can be determined based on ₁ , a _{2 ,} b 1 , and b ₂ . As is clear from the above explanation, the color picture tube equipped with the shadow mask according to the present invention can improve the beam arrangement compared to the conventional single spherical mask, and improve quality such as color purity and brightness. It can be improved further.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the operation of a color picture tube, Fig. 2 is an explanatory diagram of the beam arrangement on the fluorescent surface, Fig. 3 is an explanatory diagram for determining the mask curved surface, and Fig. 4 is an explanatory diagram of the method using a conventional spherical mask. An explanatory diagram showing an example of the grouping ratio, FIG. 5 is a diagram 9 for calculating the mask surface according to the present invention.
An explanatory diagram of points, FIG. 6 is 9 of the mask surface according to the present invention.
It is a figure showing the height of a point. 1...center beam, 2,3...side beam,
4...Shadow mask, 5...Panel, 5a...
Fluorescent surface, x...Short axis of shadow mask, y...
Long axis of the shadow mask, M(x, y)...height in the tube axis direction.

Claims (1)

[Claims] 1. In a shadow mask type color picture tube, with the center of the shadow mask as the origin, the long axis as the X axis, and the short axis as the Y axis, a point (x, y) that is x away from the short axis and y away from the long axis. The height M of the mask surface at the center of the shadow mask and the mask surface at the center (O, O) in the tube axis direction
(x, y), M(x, y) is x and y
The quartic equation M(x,y)=a ₁ x ² +a ₂ x ⁴ +b ₁ y ² +b ₂ y ⁴ +c ₁₁ x ² y ² +c ₁₂ x ² y ⁴ +c ₂₁ x ⁴ y ² +c ₂₂ x A color picture tube comprising a shadow mask characterized by forming a mask surface with ⁴ y ⁴ and b ₁ /a ₁ =0.90 to 0.95.