JPH03156832A - Color picture tube - Google Patents

Abstract

PURPOSE:To suppress the occurrence of moire by specifying the alignment pitches of throughholes of a shadow mask and the displacement between a train of adjacent throughholes respectively. CONSTITUTION:The alignment pitches Pv1 and Pv2 of throughholes are set to satisfy the equation I, where Pv1<Pv2. The displacement y between a train of adjacent throughholes is constituted of two kinds of displacement y1 and y2 corresponding to Pv1 and Pv2, and y is set to the value + y1, + y2, - y1, and - y2 for y1 and y2 satisfying the equation II or y1 and y2 satisfying the equations III and IV.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a shadow mask type color picture tube, and in particular to a color picture tube in which the through holes of the shadow mask are arranged in such a way that moiré does not easily occur. Regarding picture tubes.

(Conventional technology) Shadow mask type color picture tubes are generally blue.

A shadow mask with a large number of holes as electron beam passage holes is placed close to and opposite a phosphor screen made of three-color phosphor layers that emit green and red light, and the three electrons emitted from the electron gun are The structure is such that a color image is displayed on the phosphor screen by sorting the beams through the holes in the shadow mask.

Among such color cathode ray tubes, recently, as shown in FIG.
A shadow mask is used in which a plurality of holes are arranged in a straight line in the y-axis direction (in the y-axis direction) via bridges, and a plurality of vertical through-hole rows are arranged in multiple rows in the horizontal direction (in the x-axis direction). Corresponding to the arrangement, a phosphor screen composed of three-color phosphor layers in the form of vertically continuous stripes is generally used. In such a color picture tube, an in-line electron gun is used which emits 3f4 beams arranged in a line passing on the same horizontal plane. In addition, especially for shadow masks, in order to ensure the mechanical strength required as a shadow mask for color cathode ray tubes, the positions of the through holes (■) are regularly set to 1/2 between the adjacent through hole rows (■, ■).
It is common to have a shift of 2 pitches (PV/2).

However, if a shadow mask is used in which the positions of the through holes (2) are regularly shifted by 1/2 pitch as described above.

There is a problem in that moiré tends to occur on the screen.

That is, it is generally known that when two patterns having light and dark stripes are superimposed, the two patterns interfere and cause a moiré phenomenon. In the case of a shadow mask type color cathode ray tube, one of the light and dark stripes that cause this moiré phenomenon is the formation of a plurality of scanning bright lines in the horizontal direction of the screen due to the scanning of the electron beam.

There are bright and dark stripes in which the scanning bright lines are bright parts and the areas between adjacent scanning bright lines are dark parts.The other type is bright and dark fringes that are formed by the through holes and bridges of the shadow mask.

Now, if the arrangement pitch of the through holes in the through hole row is Pv, and the scanning bright line interval on the shadow mask is S, then the electron beam transmittance of the through hole row A(y) and the brightness waveform of the scanning line B(y)
can be expanded as shown below.

7en A (y) ” a, + Σafi cos-y
``'''' ■n, i Pv From this, the brightness I (y) of the scanning line that has passed through the through hole array is:
becomes. The last term in this equation (■) represents moiré.

Therefore, if the pitch of this moiré is P:11 and the degree of modulation is M□, then Pn+m=1/lnym+vs . . .). The moiré pitch on the phosphor screen is the magnification factor multiplied by the above pL, so the pitch on the shadow mask is as follows:
Let's talk about nm.

By the way, if the moiré ring when the positions of the through holes are shifted by Δy between adjacent through hole rows is 4(y), then Inn(y) =-!
anbmcos 2 π((-'-'-) -'-A
y)2 Pv s Pv
This is the case when n/Pv-m/s>O. Therefore, f=
Δ'j/Pv ・・・・・・・・・・・・
Assuming that ■, the magnitude of the phase shift of moiré, 1Δn1, is
1Δn1=2πn1fl ・・・・・・Old・（
). The relationship between this 1Δn1 and Ifl is shown in FIG. As mentioned above, in a shadow mask with a Pv/2 shift between adjacent through hole rows, I f + = 1/2 ...
・・・・・・ (9), 1Δnl=πn ・・・・・・・・・・・・
(10).

Therefore, moiré where n is an odd number has opposite phases between adjacent through hole rows and cancels out each other, making them less noticeable. However, moire when n is an even number has the same phase between adjacent through-hole rows, so it becomes conspicuous as moire continues in the horizontal direction.

Here, the combination mode of moire n and m is (n,
m), it has been experimentally found that the modes that are usually problematic are (2.1), (2,2), and (2,3), where n is an even number. However, in this case, it will be an electronic beer. However, ten is n/Pv-m/s <O,
− As the vertical diameter of the beam becomes smaller, the mode (
4, 3) moiré may also become a problem. Regarding such moire, the relationship between the arrangement pitch Pv of the through holes and the moire pitch P is shown in FIG. In this Figure 9, Pv
and P□ are normalized by the scanning bright line spacing S, and the horizontal axis shows Pv
/s, and the vertical axis is Pn, , /s. In Figure 1, ■ indicates mode (2, 1), (6) indicates mode (2,
2), ■ is mode (2, 3), (to) is mode (4, 3)
) is the curve. Normally, choose Pv where Pv/s is around 415.4/3, and select modes (2, 3) and (2, 2).
) or between the moiré pitches of modes (2, 2) and (2, 1). In this case, pnm=2 g...
There are two types of moiré (11), but since the pitch is small, it usually does not pose a problem.

However, for shared use in broadcasting systems with different numbers of scanning bright lines, a compromise design must be adopted, resulting in a large moiré pitch. Furthermore, even in the case of a single broadcasting system, as the electron beam diameter becomes smaller and the modulation degree becomes larger, (11)
Moiré in the expression becomes more noticeable. Furthermore, when the electron beam diameter becomes extremely small, moiré in mode (4, 3) also becomes a problem. This is inconvenient because the pitch of moiré in modes (2, 2) and (2, 1) becomes large at the minimum pitch.

By the way, in order to suppress such moiré, Japanese Patent Publication No. 57-50338 and Japanese Patent Publication No. 58-4425 disclose two or more types of hole positions, as shown in FIGS. 10 and 11. A shadow mask using a shift Δy is shown. That is, in the shadow mask disclosed in Japanese Patent Publication No. 57-50338, as shown in FIG.
are 3 Pv/8, Pv/4, and Pv/2, and in the shadow mask of Japanese Patent Publication No. 58-4425, as shown in FIG. 11, Δy is Pv/2.
, Pv/3.

However, in such a shadow mask, even if one Δy has a value that causes the moiré to be out of phase and cancel each other out for a specific n, for other Δy, the moiré will be out of phase and the moiré will be cancelled. The inhibitory effect becomes incomplete.

For example, the pitch for the through hole arrangement shown in FIG.

The moiré pattern for a mode (n,=) with a relatively large modulation degree is shown in FIG. This figure shows the expected moire in black and white based on the pitch P of the moire and the phase shift Δn, and (a) to C) indicate the mode (1, 1), (2, 1).

These are (3, 1) moiré patterns, and both are complex patterns.

Furthermore, Japanese Patent Application Laid-Open No. 51-90560 discloses a shadow mask in which through holes (3) are arranged at two or more pitches, as shown in FIGS. 13 and 14.

That is, in the example of FIG. 13, two types of arrangement pitches PV
IIPV□, and in the example of FIG. 14, there are five types of arrangement pitches PVL-PVS. However, in this shadow mask, the pitch Pv of the through hole ■ and the bridge ■
The combination with the positional deviation Δy is not considered, and a complicated pattern of moiré occurs.

(Problems to be Solved by the Invention) As mentioned above, in a color cathode ray tube, a plurality of bright and dark stripes are formed on the screen, with horizontal bright lines obtained by horizontal scanning of an electron beam as bright areas, and dark areas between adjacent bright lines. Moiré may occur on the screen due to interference between these bright and dark fringes and the bright and dark fringes generated from the through-hole arrangement of the shadow mask.

In order to suppress this moiré, normally the rows of through holes are
In shadow masks shifted by v/2, a method is used to minimize the moiré pitch and make it less noticeable by setting Pv to an appropriate value. But with this method,
When sharing a broadcasting system with a different number of horizontal scanning lines, a compromise design is required, resulting in a large moire pitch, and even in the case of a single broadcasting system, moire becomes more noticeable as the electron beam diameter becomes smaller. There are problems such as: Specifically, in order to suppress moire, there are shadow masks in which the arrangement of through holes is devised or in which the through holes are arranged at two or more different pitches, but in either case, the moire suppressing effect is incomplete.

This invention was made in view of the above problems, and
It is an object of the present invention to configure a color cathode ray tube that can sufficiently suppress moire by arranging the through holes of a shadow mask so as to effectively suppress moire.

[Structure of the invention]

(Means for Solving the Problem) A shadow mask is provided in which a plurality of through holes having a major axis and a minor axis are arranged in the major axis direction via a bridge, and a plurality of through hole rows are arranged in the minor axis direction. In the color picture tube, each of the through-hole rows has two types of through-holes with different major diameters, so that the pitch of the through-holes is alternately Pv□ and Pv□, and when the above-mentioned PVt+PV2 is PV□<P, 2, The arrangement pitch of this hole.

0.42≦pvi/ (pvx + Pvz)≦0.4
4, and the positional deviation Δy of the through holes between adjacent through hole rows
are the two types of positional deviation Δy corresponding to the above PV□ and Pv□
1. It is composed of Δy2, and 0.49≦Δy1/ (Pvz + Pva)≦0.
50.35≦Δyz/(P VL + P V2
)≦0.37, or 0.38≦P v□/ (P v□+ P vz )≦
0.42 and 0.49≦Δ! l'l/ (Pvx + Pvz)≦0
．． 50.29≦Δyz/(pvt+Pv2)
Δy1.≦0.31. Δy is +Δy with respect to Δy2
It is configured to take the values of +ΔYz+−Δy1 and −Δy2.

(Function) As mentioned above, the arrangement pitch of the holes in each hole row is 2.
By using different types of Pv (Pv1, Pv□) and setting the ratio within a predetermined range, it is possible to reduce the amplitude of moiré in a specific mode. As for moire whose amplitude does not decrease, by setting the positional deviation Δy of the through holes between adjacent through hole rows to a value within a predetermined range, it is possible to suppress the moire so that at least every two rows have an opposite phase. .

(Example) Hereinafter, the present invention will be described based on an example with reference to the drawings.

FIG. 3 shows a color cathode ray tube, which is one embodiment of the present invention.

This color cathode ray tube has an envelope consisting of a panel (10) and a funnel (11) integrally joined to this panel (10). A phosphor screen (12) consisting of a striped three-color phosphor layer that emits blue, green, and red light is formed. A shadow mask (13) having a large number of through holes as electron beam passage holes formed inside the shadow mask (13) is mounted opposite to and close to the phosphor screen (12). In addition, a center beam (
15G) and -pair of side beams (15B), (
An electron gun (16R) that emits three electron beams consisting of 15R)
) are provided. Three electron beams (15G) and (15B) are emitted from this electron gun (16).
, (15R), the structure is such that a color image is displayed by scanning the phosphor screen (12) horizontally and vertically through the through hole of the shadow mask (13).

By the way, as shown in FIG. 1, the through holes of the shadow mask (13) of the color cathode ray tube in this example have the same short diameter W and ρ4. As shown by Q2, two types of almost rectangular through holes (18a) and (18b) that differ only in their major diameters are aligned with the vertical axis (Y
A plurality of through hole rows (20) in the vertical axis direction are arranged alternately via bridges (19), and each through hole row (20) in the vertical axis direction is constituted by two types of through hole arrangement pitches PV□+PVz. A plurality of through-hole rows (20) are arranged in the horizontal axis (X-axis) direction. Moreover, each adjacent through hole row (20)
The through holes (18a) and (18b) are misaligned between them, and the positional deviations Δy are two types of positional deviations Δy1 and Δy2 corresponding to the above-mentioned through-hole arrangement pitch Pvr Pv2.

By the way, as mentioned above, there are two types of through hole arrangement pitch PV1.
+ Two types of through holes (18a) with different major diameters depending on Pv2
(18b) are arranged alternately to form a through hole row (20), the through holes (18a), (
The arrangement period of 18b) is Pv +PV2, and the electron beam transmittance A (y) of the through hole array (20) is as follows. Here, if the width of the bridge (19) is B, and for simplicity, the shapes of the through holes (18a) and (18b) are assumed to be accurate rectangles, then the following equation is obtained.

Therefore, if μ is selected so as to make coi nπμ in equation (13) small, moiré in mode (n, −) can be suppressed.

FIG. 6 shows the case where n=1 to 10 for cos nπμ. Songs a (221) to (2210) correspond to n=1 to 10, respectively. As a result, when 0.38≦μ≦0.42, n=4.60.42≦μ
It can be seen that when ≦0.44, cos nπμ of n=6.8 becomes small at the same time.

Actually, for n=4.6 and 6,8, μ:0.
It is preferable to set it to 40.0.43.

Therefore, f1=1Δy I / (PV+PV) corresponding to formula 0 −−−−−−(
14) The value of * is devised so that the moiré between adjacent through-hole rows (20) has an opposite phase for n where cos nπμ does not become small. As one of them, if 0.49≦f≦0.50, moire when n is an odd number will have a reverse phase, and moire can be suppressed. As another If+.

For μ0.40, 0.29≦If+≦0.31μ
Regarding 0.43, moire can be suppressed by setting 0.35≦f≦0.37.

The specific through hole arrangement of the shadow mask shown in FIG.
V/(Pvt+Pv2)=+0.5. +0.
36,0.5. 0.36, and Δy is repeated in the above order.

Figure 2 shows the moiré pattern of mode (n, m) that may cause a problem when the pitch S of the scanning bright lines on the shadow mask is 0.75 am for a shadow mask with such a transparent hole arrangement. The diagram (a) shown is mode (2,1),
(b) Figure shows mode (3,l), (C) Figure shows mode (
4,1), (d) figure is mode (5,1), (6) figure is mode (6,2), (f) figure is mode (7,2), (g
) figure shows mode (11,2), (h) figure shows mode (9,2)
) pattern.

Among these patterns, in mode (4, 1) in figure (C) and mode (6, 2) in figure (e), moiré lines are horizontally connected, but these have low contrast because cos nπμ is small. Low and inconspicuous. In other modes as well, moire is not noticeable because the pitch is small or the phase is reversed every two rows, and a shadow mask that sufficiently suppresses moire can be obtained.

FIG. 4 shows specific through-hole arrangements of different shadow masks. In this example, Pvt + pv, = 2.8 ai μ = pvt/ (PV1 + Pvz) = 0-40 mm Δ3
'/(Pvx +Pvz)=+0.5. +0.
3. -0.5. -0.3, and Δy is repeated in the above order.

The pitch S of the scanning bright lines on this shadow mask is 0.75
The mode (n
, m) are shown in FIG. 5. (a) Figure shows mode (2,1), (b) Figure shows mode (3,1), (
c) Figure shows mode (4, 1), (d) Figure shows mode (5,
1), (e) figure is mode (6,2), (f) figure is mode (7,2), (g) figure is mode (8°2), (h) figure is mode (9,2). This is the pattern. Among these patterns, in mode (4, 1) in figure (c) and mode (6, 2) in figure (e), moiré is horizontally continuous, but these are the same as in the above specific example. Since cosnπμ is small, the contrast is low and unnoticeable. In other modes as well, moire is not noticeable because the pitch is small or the phase is reversed every two rows, and a shadow mask that sufficiently suppresses moire can be obtained.

〔Effect of the invention〕

For a shadow mask in which a plurality of through holes having a major axis and a minor axis are arranged in the major axis direction via a bridge, and a plurality of through hole rows are arranged in the minor axis direction, the arrangement of the through holes in each through hole column. Two types of Pv (PI/L +
By using Pv□) and setting the ratio within a predetermined range, it is possible to reduce the amplitude of moiré in a mode (n, m) where n is specific. As for moire whose amplitude does not decrease, by setting the positional deviation Δy of the through holes between adjacent through hole rows to a value within a predetermined range, it is possible to suppress the moire so that at least every two rows have an opposite phase. . Moreover,
With the above configuration, the range in which moire can be suppressed can be widened, it can be shared with broadcasting systems with different numbers of scanning lines, and the number of scanning lines can be reduced to about 2 from the current number.
It is also effective for sharing high-definition vision, which is twice as large, with the current system.

[Brief explanation of the drawing]

Figures 1 to 6 are detailed explanatory diagrams of this invention.
The figure shows the through-hole arrangement of the shadow mask in one embodiment, FIGS. 2(a) to h) show the moiré patterns of each mode of the shadow mask, and FIG. 3 shows the color cathode ray tube of one embodiment. FIG. 4 is a diagram showing the through hole arrangement of a shadow mask in another embodiment,
Figures 5(a) to h) are diagrams of moiré patterns in each mode of the shadow mask, and Figure 6 is a diagram of μ and Co.
A diagram showing the relationship with Snπμ, FIG. 7 is a diagram showing the through-hole arrangement of a shadow mask in which the through-holes are shifted by 1/2 between adjacent through-hole rows,
FIG. 8 is a diagram showing the relationship between lf+ and the magnitude of the moiré phase shift 1Δn1, FIG. 9 is a diagram showing the relationship between the arrangement pitch of through holes and the moire pitch, and FIGS. 10 and 11 are diagrams showing different conventional methods. Figures 12(a) to 12(c) are diagrams showing the through-hole arrangement of a shadow mask that suppresses moiré, respectively, and Figures 13 and 14 are diagrams of moire patterns in each mode of the shadow mask shown in Figure 11. FIG. 7 is a diagram illustrating a through-hole arrangement of a shadow mask that suppresses moiré in a different conventional manner.

Claims (1)

[Scope of Claims] A color picture tube comprising a shadow mask in which a plurality of through holes each having a major axis and a minor axis are arranged in the major axis direction via a bridge, and a plurality of through hole rows are arranged in the minor axis direction. In each of the above-mentioned through-hole rows, the arrangement pitch of the through-holes becomes P_V_1 and P_V_2 alternately due to the arrangement of two types of through-holes with different major diameters, and the above-mentioned P_V_1 and P_V_2 are set as P_V_1<P_V.
_2, the arrangement pitch of the through holes is 0.42≦P_V_1/(P_V_1+P_V_2)≦
0.44, and the positional deviation Δy of the through-holes between adjacent through-hole rows is composed of two types of positional deviations Δy_1 and Δy_2 corresponding to the above P_V_1 and P_V_2, and 0.49≦Δy_1/(P_V_1+P_V_2)≦0
．． 50.35≦Δy_2/(P_V_1+P_V_2)
≦0.37, Δy_1, Δy_2, or 0.38≦P_V_1/(P_V_1+P_V_2)≦
0.42, and 0.49≦Δy_1/(P_V_1+P_V_2)≦0
．． 50.29≦Δy_2/(P_V_1+P_V_2)
Δy is + for Δy_1 and Δy_2 which are ≦0.31.
A color picture tube characterized by taking values of Δy_1, +Δy_2, -Δy_1, and -Δy_2.