JPH0822775A - Color cathode-ray tube - Google Patents

Abstract

PURPOSE:To prevent the occurrence of waviness without generating a moire. CONSTITUTION:A color cathode-ray tube which has through hole trains where almost quadrangular plural through holes 4 are arranged in a straight line shape in the first direction through a bridge 9 and has a shadow mask where these through hole trains are arranged by plural columns in the second direction orthogonal to the first direction, is provided. A first directional length 1 of these through holes 4 and a width Bw of the bridge 9 are made constant, and a first directional positional dislocation quantity ( yn) of the through holes 4 between adjacent optional two through hole trains [(n)th row and (n) + 1 row] among through hole trains of the plural columns is set by the random number. When a through hole arranging pitch in the through hole trains is denoted by Pv, the first directional positional dislocation quantity ( yn) between these through hole trains [(n)th column and (n) + 1 column}] is set by the following expression. [ yn=Pv/2+(-1)<n>.Rn.A]. Herein, Pv is a through hole arranging pitch, and Rn is the random number, and A is [0<A<=Pv/4].

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shadow mask type color cathode ray tube, and more particularly to a color cathode ray tube in which the through holes of the shadow mask are arranged so that moire does not easily occur.

[0002]

2. Description of the Related Art Generally, a shadow mask type color cathode ray tube has a substantially rectangular panel 1 as shown in FIG.
Has an envelope in which a funnel-shaped funnel 2 is integrally joined, and a fluorescent screen 3 is formed on the inner surface of the panel 1. The phosphor screen 3 is composed of a stripe-shaped three-color phosphor layer that emits blue, green, and red light and extends parallel to the vertical axis of the panel 1. A shadow mask 5 having a through hole 4 through which an electron beam passes is provided inside the panel 1 facing the fluorescent screen 3.
Is installed. An electron gun 8 for radiating an electron beam 7 composed of a center beam 7G and a pair of side beams 7B and 7R passing on the same plane including the tube axis is arranged in the neck 6 of the funnel 2, and from this electron gun 8 The emitted electron beam 7 scans the phosphor screen 3 through the shadow mask 5 to display a color image.

The shadow mask 5, as shown in FIG.
A plurality of substantially rectangular through holes 4 are linearly arranged at a constant pitch (Pv) in the vertical direction (Y direction) of the screen via a bridge 9, and the linear through hole rows are horizontal (X direction). ) Is arranged in multiple rows in a mosaic pattern. The phosphor screen 3 is composed of a stripe-shaped three-color phosphor layer having no vertical discontinuity corresponding to the arrangement of the through holes 4 of the shadow mask 5.

The shadow mask type color cathode ray tube having the above-described structure is used for the electron beam 7 emitted from the electron gun 8.
Are deflected by a horizontal deflection magnetic field and a vertical deflection magnetic field formed by a deflection yoke 10 arranged on the neck 6 of the funnel 2, scanned over the entire fluorescent screen 3, and stripes of corresponding colors through the through hole rows of the shadow mask 5. The phosphor layer is excited to emit light to form a color image.

By the way, the arrangement of the through holes 4 of the shadow mask 5 in the color cathode ray tube is as follows.
In order to ensure the mechanical strength of the bridge, as shown in FIG. 4, a bridge 9 (or the through hole 4) is displaced by 1/2 pitch Pv between two adjacent through hole rows. There is.

However, in this way, the shift amount Δ of the bridge 9 is
When the shadow mask 5 in which y is regularly shifted by 1/2 pitch Pv is used, there is a problem that moire is likely to occur on the screen. That is, it is generally known that when two patterns having light and dark stripes are superposed, the two patterns interfere with each other to generate moire fringes. In the case of this color cathode ray tube,
First, although a plurality of scanning bright lines are formed in the horizontal direction of the screen by scanning with the electron beam, bright and dark stripes are formed with the scanning bright lines as bright portions and the spaces between the bright lines as dark portions. On the other hand, shadow mask 5
As described above, since the bridge 9 between two adjacent through hole rows is displaced by 1/2 pitch Pv, the through hole 4 and the bridge 9 are
And cause light and dark stripes. That is, when the scanning line passes through the shadow mask 5 having the through hole arrangement, as shown in FIG. 5A, the shadow mask 5 is divided into areas (A) which are divided in the horizontal direction.
1 to A9), the amount of electron beam transmission is shown in FIG.
The bright and dark fringes having the electron beam maximum transmission portion p as the bright portion and the electron beam minimum transmission portion q as the dark portion are formed in the same direction as the bright and dark fringes formed by the scanning bright lines. Then, the bright and dark stripes of the shadow mask 5 and the bright and dark stripes formed by the scanning bright lines interfere with each other to cause a moire phenomenon.

In order to prevent the moire phenomenon of the color cathode ray tube, one of the two light and dark stripes may be eliminated. However, the bright and dark stripes formed by the scanning bright lines are determined by the vertical size of the cathode ray tube screen and the broadcasting system.
It has a uniquely determined pitch, which cannot be eliminated. Therefore, conventionally, the arrangement pitch Pv of the through holes 4 in the vertical direction of the shadow mask 5 and the bridge width Bw are properly designed so that moire fringes do not become remarkable.

However, in the shadow mask 5,
When the bridge width Bw is reduced, the mechanical strength of the shadow mask 5 is weakened and the shadow mask 5 is deformed, so that the through hole array pitch becomes a main element of the moire prevention measure. Therefore, various measures for preventing the moire have been proposed in the related art, in which the deviation amount Δy of the bridges 9 of the adjacent through hole arrays is shifted to an appropriate interval. However, since the bright and dark stripes of the shadow mask 5 originally have local light and dark portions as long as there is some regularity in the through hole arrangement, and they appear with periodicity, the light and dark stripes based on the scanning bright lines of the screen. When the stripes overlap, the moire phenomenon occurs, which is unavoidable. For this reason, the actual situation is to select an array pitch that does not cause Moire fringes for each broadcasting system having a different number of scanning lines.

[0009]

Therefore, recently, for example, as shown in FIG. 6, the longitudinal length 1 of the through hole row of the through holes 4 and the width Bw of the bridge 9 are constant, that is, the through holes. The array pitch Pv in the longitudinal direction of the rows is constant, the positional deviation amount Δy of each through hole 4 between adjacent arbitrary through hole rows is set by a random number, and this deviation amount Δy is set with respect to the through hole array pitch Pv. 0.
The one set in the range of 2 Pv to 0.8 Pv is proposed. (See Japanese Patent Laid-Open No. 2-291645)

In such a color cathode ray tube, since the positional deviation amount Δy of the through holes 4 between the adjacent through hole rows is set by a random number, the array pattern of the through holes 4 is completely non-uniform over the entire surface of the shadow mask 5. It can be arranged in a regular pattern, and moire can be prevented from occurring. Further, the positional deviation amount Δy of the through hole 4 is set to 0.
Since it is set in the range of 2 Pv to 0.8 Pv, as shown in FIG. 7, for example, a region A of Δy = 0 or Δy = Pv is formed and the through holes 4 and the bridge 9 are aligned in the horizontal direction. It is possible to prevent the formation of local bright and dark stripes. Further, the area of the through holes 4 included in a certain area becomes uniform over the entire surface of the shadow mask 5, and it is possible to prevent the occurrence of uneven brightness on the screen.

However, the color cathode ray tube in which the position deviation amount Δy of the through holes 4 between the through hole rows is set by a random number in this way and the through hole array is irregularly formed is certainly a moire fringe on a color image. Although the unevenness on the screen can be prevented and uneven brightness on the screen can be prevented, a new problem has been found that a so-called unevenness in the screen is generated.

Therefore, according to the present invention, the positional deviation amount Δy of the through holes 4 between the through hole rows is set by a random number, and in the color cathode ray tube in which the through hole array is formed in an irregular array, the waviness generated on the screen is generated. The present invention has been made in view of the above problem, and an object of the present invention is to provide a color cathode-ray tube that does not generate moire fringes or uneven brightness, suppresses uneven waviness, and can obtain a good image.

[0013]

The inventors of the present invention have made extensive studies as to the cause of the wavy unevenness, and as a result have finally clarified the cause. The occurrence of the wavy unevenness is solved as follows. It was possible. That is, it was found that the shadow mask 5 in which the through hole arrangement was set by random numbers had a wavy pattern on the mask surface, and waviness could be generated in the screen corresponding portion of the color cathode ray tube equipped with this. did. And as a result of observing these wavy parts in detail,
I found out the following. FIG. 2 shows an array pattern of the through holes 4 of the shadow mask 5 shown in FIG. 6 in which the positional deviation amount Δy of the through holes 4 between the through hole rows is set by a random number. In this arrangement pattern, each through hole 4 is shown by a rectangular dotted line for simplicity. As shown by the broken line in FIG. 2, focusing on the positions of the bridges 9 in each of the adjacent through hole arrays and looking at the angles θ1 and θ2 formed between the adjacent bridges 9, first, in the bridge 9a, θ1 <Θ2 occurs, and then, also in the bridge 9b, θ1 <θ2 occurs. This .theta.1 <.theta.2 is connected to the bridge 9e and is inverted by the bridge 9e to generate .theta.1> .theta.2. The polygonal line in the figure connects the smaller angle of the angles .theta.1 and .theta.2 formed by the left and right bridges 9, 9 of each adjacent through hole arrangement. By the way, in the above through hole arrangement, the left and right bridges 9, 9
The angles θ1 and θ2 formed by θ1> θ2 occur, or conversely θ
It is completely random and unclear whether 1 <θ 2 occurs or at what probability. Also, it may be connected in the same direction as three or four, or may be reversed. According to our observation, the size of each through hole 4 in the above through hole array is, for example, 0.5 mm × 0.0
It is extremely small, about 6 mm, and the pattern and displacement of itself are invisible to the naked eye, but when the through holes 4 are connected in the same direction, the connected portion is visually recognized by the human eye and inverted. It was confirmed that the parts were not connected and could not be visually recognized. Therefore, for example, the bridge 9 between two adjacent rows of through holes is displaced by the 1/2 pitch Pv in FIG.
The shadow mask 5 has a pattern in which the through holes 4 are vertically inverted for each array and has a uniform regularity. Therefore, the through hole pattern of the array pattern is not recognized by human eyes and the entire surface is covered. It only looks like a light gray color, and there is no waviness on the screen. However, in the shadow mask 5 of FIG. 6 in which the array pattern of the through holes 4 is randomly set with random numbers, when the through holes 4 are connected to three or four in the same direction in the array pattern, the connected part is seen by human eyes. It seemed to form a group, and it was found that this was seen as wavy and wavy. Therefore, the inventors of the present invention have an array pattern of minute through holes that is difficult for the human eye to visually recognize with each of the shadow masks 5, and when the through hole rows are arranged in a continuous manner, they are wavy as seen by the human eye. This is solved based on the fact that it is visually recognized, and the displacement amount of the array pattern is set randomly with a random number, and the array pattern of a series of adjacent through holes is set so as not to be arrayed continuously. Is. That is, the color cathode ray tube of the present invention has a through hole array in which a plurality of substantially quadrangular through holes are linearly arranged in the first direction via a bridge, and the through hole array is in the first direction. In a color cathode ray tube including a plurality of rows of shadow masks arranged in a second direction orthogonal to the second direction, the length of the through holes in the first direction and the width of the bridge are constant, and , The positional deviation amount Δyn in the first direction of the through holes between any two adjacent through hole rows (the n-th row and the (n + 1) th row) is set by a random number, and this through-hole row (the n-th row). And the nth
The positional deviation amount Δyn in the first direction between the (+1 column) is set by the following equation, where Pv is the through hole array pitch in the through hole array. Δyn = Pv / 2 + (− 1) ⁿ · Rn · A where Pv: Through hole array pitch Rn: Random number A: 0 <A ≦ Pv / 4

[0014]

[Operation] A positional deviation amount of a through hole between two adjacent through hole rows Δ
yn is set by a random number, and its positional deviation amount Δy
Since n is set in the range of 0.25 Pv to 0.75 Pv, the alignment of the bridges between adjacent rows of through holes is completely prevented, and the through holes are arranged irregularly over the entire shadow mask. be able to. In addition, the values of the positional deviation amount Δyn of adjacent rows of through holes are 1Pv / 2 to 3Pv / 4 and 1 respectively.
Pv / 4 to 1Pv / 2 are alternately set, and the array of the through holes 4 becomes an array pattern in which the arrays are vertically inverted for each column. Further, the area of the through holes becomes uniform over the entire surface of the shadow mask, and it is possible to prevent the occurrence of uneven brightness on the image.

[0015]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an example of a shadow mask 5 in a shadow mask type color cathode ray tube according to an embodiment of the present invention.

As is apparent from the figure, the through holes 4 which are vertically long in the vertical direction (Y direction) of the screen are connected to the bridge 9.
In a configuration in which through-hole rows are formed in a row at a constant pitch Pv via the holes, and the through-hole rows are arranged in parallel in the horizontal direction (X direction) at equal intervals, and in the arrangement of the through-hole rows, they are adjacent to each other in the horizontal direction. Although the deviation amount Δy of the bridge 9 between the matching through-hole rows is randomly set by a random number, it is the same as in the conventional example shown in FIG. 6, but the bridge 9n between the nth row and the (n + 1) th row is The difference is that the deviation amount Δyn is set according to the following equation. As in the case of FIG. 6, this through-hole row has a constant length l of the through-hole row in the longitudinal direction and a width Bw of the bridge 9, and the array pitch Pv of the through-holes 4 is set to be constant. There is. Δyn = Pv / 2 + (− 1) ⁿ · Rn · A where Pv: Through hole array pitch Rn: Random number A: 0 <A ≦ Pv / 4

In the shadow mask 5 thus constructed, the positional deviation amount Δyn of the through holes 4 between adjacent rows of through holes is set by the random number Rn, so that the through holes 4 are formed over the entire shadow mask. It is arranged irregularly and the moire phenomenon can be prevented.

In this case, the positional deviation amount Δyn set by the random number Rn is set in the range of 0.25 Pv to 0.75 Pv with respect to the array pitch Pv of the through holes 4, and is shown in FIG. Similarly, the positional deviation amount Δy is Δy =
The area A of 0 or Δy = Pv is not formed, and it is prevented that the through holes 4 and the bridges 9 are aligned in the horizontal direction to form local bright and dark stripes.

Furthermore, the positional deviation amount Δyn for each array of through holes is set as in the above equation, and the value of the positional deviation amount Δyn for adjacent through hole arrays is alternately set in a range above and below a half pitch. 1Pv / 2 to 3Pv / 4 and 1Pv / 4 to 1P
Since the value is set to v / 2, the arrangement positions of the through holes 4 are inverted vertically for each array of through holes. Therefore, in the through hole arrangement, the through holes 4 are not connected and arranged in the same direction, and the occurrence of waviness is prevented.

Further, since the length 1 of the through hole 4 and the width Bw of the bridge 9 are set to be constant and the array of through holes is randomly set by a random number, the through holes 4 occupy a constant area of the shadow mask 5. Since the area is constant, the uneven brightness of the screen can be eliminated.

The polygonal line in FIG. 1 is, as in the case of FIG. 2, connected to the smaller one of the angles θ1 and θ2 formed by the left and right bridges 9 of each adjacent through hole array.
The array positions of the through holes 4 are reversed for each array and are not continuous. Therefore, the occurrence of waviness is prevented.

[0023]

As described above, according to the present invention, the positional deviation amount Δy of the through holes is randomly set by a random number, the regularity of the through hole arrangement is eliminated, and the generation of bright and dark stripes is eliminated, and the on-screen image is eliminated. The moire phenomenon due to the interference with the bright and dark fringes can be completely prevented, and since the arrangement pattern of the continuous through holes is eliminated, it is possible to prevent the occurrence of image waviness and provide a color cathode ray tube with a good screen.

[Brief description of drawings]

FIG. 1 is a view showing an example of a through hole arrangement of a shadow mask in a shadow mask type color cathode ray tube according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a wavy unevenness generation principle of a shadow mask in which a through hole array is set by random numbers.

FIG. 3 is a schematic sectional view of a shadow mask type color cathode ray tube.

FIG. 4 is a diagram showing an example of a through hole arrangement of a shadow mask in a conventional shadow mask type color cathode ray tube.

5A and 5B are explanatory diagrams of the generation principle of bright and dark fringes of a shadow mask, FIG. 5A is a pattern diagram, and FIG. 5B is a diagram showing corresponding bright and dark fringes.

FIG. 6 is a diagram showing an example in which a through hole array of a shadow mask in a conventional shadow mask type color cathode ray tube is set by random numbers.

FIG. 7 is a through hole arrangement of FIG.
Pattern diagram of through hole arrangement in the range of v

[Explanation of symbols]

 4 Through hole 5 Shadow mask 9 Bridge Pv Through hole pitch Bw Bridge width Δy Amount of displacement of through hole array

Claims (1)

[Claims] 1. A plurality of substantially quadrangular through-holes has a row of through-holes linearly arranged in a first direction via a bridge, and the row of through-holes is orthogonal to the first direction. In a color cathode-ray tube having a shadow mask arranged in a plurality of rows in the same direction, the length of the through holes in the first direction and the width of the bridge are made constant, and any of the plurality of through hole rows adjacent to each other is adjacent. A positional deviation amount Δyn in the first direction between the two through-hole rows (the n-th row and the (n + 1) th row) is set by a random number, and this through-hole row (the n-th row and the (n + 1) th row) The amount of positional deviation Δyn in the first direction between the through holes array pitch in the through hole array is P
A color cathode ray tube, wherein v is set by the following equation. Δyn = Pv / 2 + (− 1) ⁿ · Rn · A where Pv: Through hole array pitch Rn: Random number A: 0 <A ≦ Pv / 4