JPH04188545A - Cathode-ray tube - Google Patents

Abstract

PURPOSE:To concentrate a plurality of beams onto a fluorescent screen easily by impressing a voltage, which is equal to or lower than the voltage impressed on a final convergence electrode, on an electrode situated apart from the gun axis, and deflecting side beams to the center beam direction with an internal electrode. CONSTITUTION:An internal electrode 19 consisting of electrodes 25, 22, which face each other in the orientation direction of a plurality of beams and in parallel with the gun axis, is installed in the passing zone for side beams 14G, 14R in a final convergence electrode G3 constituting a main lens. Onto that 22 of these mutually facing electrodes which is situated on the gun axis Z side, a voltage is impressed equal to the voltage impressed on the final convergence electrode G3, while a voltage lower than the voltage impressed thereon G3 is impressed on the other electrode 25 which is situated apart from the gun axis Z. Thereby a small-sized electron gun can be accomplished, in which a plurality of beams are concentrated on a fluorescent screen, without requiring eccentric or inclined arrangement of the electrode G3 constituting the main lens or without prolonging the drift space.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a cathode ray tube that emits multiple beams, such as a color picture tube, and particularly relates to a cathode ray tube that emits multiple beams, such as a color picture tube, and in particular, a cathode ray tube that emits multiple beams, including a center beam and side beams, arranged in a row. The present invention relates to a cathode ray tube that has an in-line electron gun that emits , and has improved concentration characteristics of multiple beams emitted from the electron gun.

(Prior Art) Generally, a color picture tube has an envelope consisting of a panel and a funnel integrally joined to the panel, and the inner surface of the panel is coated with three-color phosphor layers that emit light in blue, green, and red. A phosphor screen is formed, and a shadow mask having a large number of electron beam passage holes is disposed inside the phosphor screen, facing the phosphor screen. In addition, an electron gun that emits three electron beams is placed inside the neck of the funnel, and the three electron beams emitted from this electron gun are deflected by the magnetic field generated by the deflection yoke attached to the outside of the funnel, and are deflected through a shadow mask. By horizontally and vertically scanning the phosphor screen, a color image is displayed on the phosphor screen.

In such a color picture tube, especially the electron gun,
There is an in-line type electron gun that emits three electron beams arranged in a row, consisting of a center beam and a pair of side beams that pass on the same horizontal plane.

FIG. 5 shows an example of the in-line type electron gun. This electron gun is the most common pi-potential type electron gun, and has three cathodes (K
B), (KG), (KR), these cathodes (
Three heaters (H) that heat KB), (KG), (KR) and the cathodes (XB), (K
G) and (KR) have first to fourth grids (G1) to (G4) arranged in sequence (in the direction of the phosphor screen), and are integrally connected by a pair of insulating supports (not shown). formed into a fixed structure. Each grid (G1) to (G4) has three cathodes (KB),
Three electron beam passing holes arranged in a row are formed corresponding to (KG) and (KR).

Each central electron beam passing hole is coaxial with the cathode (KG). However, each electron beam passing hole on both sides is
Are the grids (G1) to the third grid (G3) coaxial with the cathodes (KB) and (KR), respectively?
The electron beam passage holes of the fourth grid (G4) are eccentric to the outside with respect to the electron beam passage holes of the third grid (G3).

In this electron gun, the cathodes (KB), (KG),
(KR) and the first and second grids (Gl), (C2
), the cathodes (KB), (KG), (K
The electron emission from R) is controlled, and the emitted electrons are accelerated and focused to form a parallel three-electron beam (IB>
, (IG), (IR), and includes third and fourth grids (G3).

(G4), the main lens (2
) is formed.

Usually each cathode (KB), (KG) of this electron gun
A video signal is added to , (KR), and the first grid (
G1) = 100 ~ OV1 2nd grid (G2) 30
0~100OV, 3rd G') F (G3)l:4.
5-10kV, 25-30kV on the 4th grid (G4)
voltage is applied. Thereby, the cathode (KB)
, (KG), and (KR) are once focused between the first and second grids (Gl) and (G2), become an electron beam, and diverge into the third grid (G3). The third and fourth grids (G3)
The main lens (2) formed by (G4) finally accelerates and focuses the light onto the phosphor screen.

In this case, as shown in Fig. 7, a pair of side beams (
The potential distribution (3) forming the main lens that accelerates and focuses IB) and (IR) is the third grid (G3) as described above.
) with respect to the electron beam passage holes on both sides of the fourth grid (
Since the electron beam passing holes on both sides of G4) are eccentric to the outside, the vicinity of the opening of each grid (G3) and (G4) is axially symmetrical with respect to the central axis of each grid (G3) and (G4). However, at the center of the gap between both grids (G3) and (G4), the distribution is shifted by the eccentricity d of both grids (G3) and (G4). As a result, one of the side beams (I
B) is incident on the central axis of the equivalent convex lens (4) and travels straight without being refracted, and due to the concave lens (5) which is shifted by d with respect to this convex lens (4), it is reflected in the direction opposite to the direction of the shift. is refracted at an angle θ. Similarly, the other side beam (
IR) is also refracted by an angle θ, thereby concentrating the center beam and the pair of side beams.

The refraction angle θ of the pair of side beams at this main lens is approximately proportional to the strength and eccentricity d of the lens. Therefore, the electron beam passing hole diameter of the third and fourth grids is 5.5 mm.
The eccentricity d of the electron beam passing holes in both grids is 0.2 mm.
In one example, when a voltage of 7.2 kV is applied to the third grid and a voltage of 25 kV is applied to the fourth grid, the refraction angle θ of each side beam is 1.1°.

By the way, when assembling a collar storage using such an electron gun, for a large tube, as shown in Fig. 9(a), 3
The electron beams (IB), (IG), and (IR) become concentrated in front of the phosphor screen (7), and in a small tube, as shown in (b), the phosphor screen (a) It becomes a state of lack of concentration where you concentrate at the back. For example, in the case of a 90-degree deflection tube with a neck diameter of 2h+m, a 21-inch tube will have an overconcentration of 2 mm, and a 14-inch tube will have an underconcentration of 2 mm.

If this overconcentration or lack of concentration is attempted to be corrected by a convergence magnet that generates a quadrupole magnetic field attached to the outside of the neck, the electron beam will be incident on the main lens with a displacement, resulting in coma aberration. Moreover, the quadrupole magnetic field changes the aspect ratio of the cross section of the electron beam, significantly deteriorating the beam spot on the screen. Therefore, in this type 2 electron gun, the fourth grid (G3)
It is necessary to change the eccentricity d of the grid (G4) to be optimal for each type of pipe, and it is necessary to manufacture many types of fourth grids (G4) with relatively complicated shapes. In addition, many types of electron gun assembly jigs are required.

Such problems also apply to electron guns that concentrate three electron beams by tilting a grid forming a main lens.

Another electron gun that concentrates three electron beams arranged in a row is an electron gun shown in FIG. This electron gun is a unipotential electron gun called the Trinitron (trademark) system, and has three cathodes (KB) arranged in a row.
(KG), (KR), these cathodes (KB)
, (KG), (KR).
(not shown), the above cathode (KB), (KG),
(KR) The first to fifth grids (
G1) to (G5) and a convergence plate (CP) placed on the fifth grid (G5).

In this electron gun, there are first and second grids (Gl).

(G2) makes the cathode lens, the second and third grids (G2), (G3) make the brifocus lens, the third, fourth, and fifth grids (G3), (G4)
, (G5) forms the main lens.

The convergence plate (CP) consists of four flat plate electrodes (CPI) to (CP4) that face each other, and the two inner flat plate electrodes (C
P2) and (CP3) have the anode voltage, and the outer 2
A voltage of 92 to 96% of the above anode voltage is applied to each of the flat plate electrodes (CPI) and (CP4).

Three electron beams (IB) are emitted from this electron gun.

(1G), (IR) are the second and third grids (G2)
, (G3), and the third, fourth, and fifth grids (G3
) '+ (G4).

The light intersects at the center of the main lens formed by (G5), and then enters between the opposing flat plate electrodes (CPI) to (CP4) of the convergence plate (CP) while diverging. Of the three electron beams (IB), (lc), (IR) that enter between the flat plate electrodes (CPI) to (CP4), a pair of side beams (IB), (IR) are particularly important.
are the opposing flat plate electrodes (CPI), (CP2
) and (CP2), (CP4),
As a result, three electron beams (iB), (lG),
(IR) is concentrated at one point on the phosphor screen.

In this electron gun, a pair of side beams (IB)
, (IR) enters the convergence plate (CP) while diverging at an exit angle equal to the incident angle ζ to the main lens, and forms a center beam (IG) and a pair of side beams (IB) within the convergence plate <cp>. ).

(IR) is required as a section where the beam spacing Sg is a predetermined beam spacing. The total length of the electron gun increases, and accordingly, the total length of the electron gun itself also increases, making it difficult to downsize the color picture tube.

Furthermore, in general, the deflection of an electron beam by a parallel plate is the first
As shown in Figure 1, the deflection angle is α, the phosphor screen (7
) is the deflection distance on the top (X), the distance from the center of the parallel plate (8) to the phosphor screen (7), the length of the parallel plate (8) is 1, and the interval between the parallel plates (8) is d.

If the drift space potential is Eb and the potential difference between the parallel plates (8) is Ed, then tana vote x / L - (1/2d) ・ (Ed /Eb)... (1
). Therefore, the higher Eb is, the longer it is necessary to make l longer and Ed larger, and conversely, it is necessary to make d smaller.

From this point of view, the convergence plate of the electron gun is located in the highest potential space, and the pair of side beams are obliquely incident on the convergence plate, so in order to obtain the required deflection distance There is a trade-off that the plate must be large and have a complicated shape.

(Problem to be Solved by the Invention) As described above, in an electron gun that emits three electron beams arranged in a row consisting of a center beam and a pair of side beams passing on the same plane, grids constituting the main lens are placed adjacent to each other. Concentrating the three electron beams by eccentrically or tilting them with respect to the grid results in overconcentration in large tubes and underconcentration in small tubes. If this overconcentration or lack of concentration is attempted to be corrected by a convergence magnet attached to the outside of the neck, the cross-sectional shape of the electron beam will change, and the beam spot on the screen will be significantly degraded. Therefore, it is necessary to change the amount of eccentricity and angle of inclination for each type of pipe, and many types of grids for eccentricity or inclination must be manufactured, and many types of assembly jigs are required.

Another electron gun is an electron gun that concentrates three electron beams arranged in a row, which are prefocused by a prefocus lens, by intersecting them at the center of the main lens, and then making them diverge while being incident on a convergence plate made of a flat electrode. There is. However, in this electron gun, for electron guns with a small angle of incidence on the main lens or electron guns with a large distance Sg between the center beam and a pair of side beams, the draft space, that is, the total length of the grid forming the main lens becomes long. However, there is a problem in that it is difficult to miniaturize the cathode ray tube.

This invention was made in view of the above problems, and
Multiple beams arranged in a row passing on the same plane can be projected onto a phosphor screen without decentering or tilting the grid that makes up the main lens with respect to adjacent grids, and without increasing the overall length of the grid that makes up the main lens. The purpose is to construct an electron gun that can be focused.

[Structure of the Invention] (Means for Solving the Problem) An electron gun that emits a plurality of beams arranged in a line consisting of a center beam and side beams passing on the same plane is installed,
A plurality of electrodes constituting an electron beam forming section that controls electron emission from the electron gun or cathode and focuses the emitted electrons to form a plurality of parallel beams arranged in a row; A cathode ray tube consists of a plurality of electrodes that form a main lens that accelerates and focuses multiple beams onto a phosphor screen. Arranging electrodes that are parallel to the axis and facing each other in the arrangement direction of the plurality of beams, and applying the same voltage as the voltage applied to the final focusing electrode to the electrode located on the gun axis side among the facing electrodes, An internal electrode was provided to deflect the side beam toward the center beam by applying a voltage lower than the voltage applied to the final focusing electrode to an electrode located away from the gun axis.

(Function) As mentioned above, an internal electrode consisting of electrodes parallel to the gun axis and facing each other in the direction of arrangement of the plurality of beams is provided in the side beam passage area in the final focusing electrode forming the main lens. Among the electrodes, when applying the same voltage as the voltage applied to the final focusing electrode to the electrode located on the gun axis side, and applying a lower voltage than the voltage applied to the final focusing electrode to the electrode located away from the gun axis, , it is possible to construct a compact electron gun that concentrates multiple beams on a phosphor screen without decentering or tilting the electrode forming the main lens, and without increasing the drift space.

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

FIG. 5 shows a color picture tube which is one embodiment of the present invention. This color picture tube is an in-line type color picture tube, and has an envelope consisting of a panel (10) and a funnel (11) integrally joined to this panel (10), and has an inner surface of the panel (10). A phosphor screen (7) consisting of three-color phosphor layers that emit light in blue, green, and red is formed, and a large number of electron beam passing holes are formed inside the phosphor screen (7), facing the phosphor screen (7). A shadow mask (12) is arranged.

In addition, within the neck (13) of the funnel (11), there are three electron beams (14B), (14G) arranged in a row, consisting of a center beam (14G) passing on the same horizontal plane and a pair of side beams (14B), (14R). ), (
An electron gun (15) that emits 14R) is also arranged.

The three electron beams (14B), (14G), and (14R) emitted from the electron gun (15) are then directed to a deflection yoke (17) attached to the outside of the funnel (11).
is deflected by the magnetic field generated by the shadow mask (12).
The structure is such that a color image is displayed on the phosphor screen (7) by scanning the phosphor screen (7) horizontally and vertically through the phosphor screen (7).

As shown in FIG. 1, the electron gun (15) has three cathodes (KB) arranged in a row on the same horizontal plane.

(KO), (KR), these cathodes (KB),
(KG), (KR) 3 heaters (
) I) and the above cathode (KB), (Rc),
(KR) The first to fourth grids (G
It consists of a pi-potential type electron gun with cathodes (KB), (KG), (
KR), heater (H) and first to fourth grids (
CI) to (G4) are fixed together by a pair of insulating supports (not shown). The first and second grids (G
L).

(G2) is a plate-shaped electrode, the third grid (G3) is a cylindrical electrode, and the fourth grid (G4) is a cup-shaped electrode.

Each of these grids (C1) to (G4) has three electron beam passing holes arranged in a row corresponding to the three cathodes (KB), (KG), and (KR). Each of the three electron beam passing holes, that is, the central electron beam passing hole and the electron beam passing holes on both sides, are connected to the corresponding cathodes (KG), (KG), (
KR).

Furthermore, in this electron gun (16), an internal electrode (
19) are located.

As shown in FIG. 2, this internal electrode (19) has three rectangular electron passing holes (20B), (20G), (20R) arranged in a row corresponding to the three cathodes, and the electron Passing holes (20B), (20G), (20
R) During formation, electron passing holes (20B) on both sides, (2
0R) is cut and raised at right angles to form each electron passing hole (20
B) A first electrode (22) having a pair of first plate-shaped electrode parts (21a) and (21b) located between It has a horizontally elongated rectangular electron passage hole (23), and when forming the electron passage hole (23), a pair of second plate-shaped electrode parts (24a) are formed by cutting and raising the outer edge of the electron passage hole (23) at right angles. ),
(24b) and a second electrode (25). As shown in FIG. 4, these first and second electrodes (22)
, (25) as its first and second plate-shaped electrode parts (21a)
, (21b), (24a).

The 111th pole (22) is arranged with the 4th grid (G4) turned upside down, with the 111th pole (22) facing each other so that the pole (24b) is on the inside.

In this case, the first and second plate-shaped electrode portions (2La), (21b), (24a) of the picture electrodes (22), (25)
, (24b) are located parallel to the gun axis and in the arrangement direction of the three electron beams, and the first plate-shaped electrode portions (21a), (21
b), the first plate-shaped electrode portions (21a), (21
b) and a second plate-shaped electrode part (24a).

(24b), the pair of side beams are opposed to each other across from the arrangement direction of the three electron beams.

Such an arrangement of the internal electrodes (19) can be achieved, for example, by forming the third grid into a structure in which a pair of cup-shaped electrodes are butted together, and before the butting, the first and second electrodes are placed inside the cup-shaped electrodes arranged on the fourth grid side. 2 electrodes (22).

(25) is arranged and fixed by an insulating support that fixes the cathode, the heater, and the first to fourth grids together.

Each cathode of this electron gun (KB), (KG),
A video signal is added to the first grid (Gl).
) to -10 (1~OV, 2nd group! J Tsudo (02) Ni 30
0-100OV, 3rd grid (G3) 1. :4.5～
1 OkV, 4th grid (G4)! : A voltage of 25 to 30 kV is applied. Also, the internal electrode (
19), the first electrode (22) has a third grid (G3).
The same voltage as that of the second
, a lower voltage is applied to the electrode (25). Thereby, the cathode (KB).

(KG), (KR) and the first and second grids (G
l), (G2), the cathode (KB), (
The electron emission from KG), (KR) is controlled, and the emitted electrons are accelerated and focused to form three parallel electron beams (14B), (14G) arranged in a row.

(14R) is configured, and the third and fourth grids (G3) and (G4) form three electron beams (14B) emitted from the electron beam forming section.
).

A main lens is formed which ultimately accelerates and focuses (14G) and (14R) onto the phosphor screen.

Therefore, in this electron gun (6), the cathode (KB)
The electrons emitted from , (KG) and (KR) are
After being once focused between the first and second grids (Gl) and (G2), it enters the third grid (G3) while diverging, and is formed by the third and fourth grids (G3) and (G4). The main lens finally accelerates and focuses the light onto the phosphor screen (7). A pair of side beams (IB) at the same time.

(IR) is the internal electrode (1) inside the third grid (G3).
9), the first and second plate-shaped electrode parts (21a) and (21b
), (24a), and (24b), the first plate-shaped electrode portion (21a).

(21b) and the second plate-shaped electrode part (24a), (24b)
) is deflected by the electric field created by the potential difference between
Electron beams (IB), (IG), (IR) are
It is concentrated at one point on the phosphor screen (7).

Moreover, this electron gun (6) has, for example, a center beam (14G) and a pair of side beams (14B).

(14R) 6.6 degrees, 3rd grid (G3)
Assuming that the voltage is 7.2 kV, in the case of a 21-inch 90-degree deflection tube, the deflection distance X on the phosphor screen (7) of the above formula (1) is 8.6 mm, and the internal electrode (19) (parallel plate) The distance from the center of the screen to the phosphor screen (7) is 381.011111. Drift space potential is 7.
It becomes 2kV. Therefore, the first of the internal electrodes (19),
Second plate-shaped electrode part (21a), (21b), (2
4a), length 1 of (24b) is 7 mm, internal electrode (
19) The distance (
By setting the distance (distance between the parallel plates) to 3.5 rhymes, the internal electrode ( 19) first and second electrodes (22), (25)
The potential difference Ed between them is 124.7V from equation (1).

Furthermore, if the same electron gun (6) is used in a 14-inch 90-degree deflection tube, the distance from the center of the internal electrode (19) to the phosphor screen (7) is 287:4 mn+.
So, 3 electron beams (14G), (14B),
The first and second electrodes (
The potential difference Ed between 22) and (25) is 165; 3V and null from equation (1).

In other words, when using the electron gun (6) of this example, in a 14-inch 90-degree to 21-inch 90-degree deflection tube, three electron beams can be beamed at an extremely low deflection voltage of 1.7 to 2.3% of the drift space potential. (14G), (1413),
('14R) can be easily concentrated at one point on the phosphor screen (7), and an internal electrode (19) corresponding to the convergence plate of a conventional electron gun is arranged inside the final accelerating electrode. As a result, it is possible to create a compact electron gun with a short overall length.

In the above embodiment, an in-line color picture tube is described which is equipped with a pi-potential type electron gun that emits eight electron beams arranged in a row passing on the same plane. It can also be applied to in-line color picture tubes equipped with electron guns and other cathode ray tubes.

[Effects of the Invention] As described above, the electron gun emits a plurality of beams arranged in a line consisting of a center beam and side beams passing on the same plane. Opposing electrodes are arranged parallel to the axis and in the direction in which the plurality of beams are arranged, and among these opposing electrodes, the same voltage as that applied to the final focusing electrode is applied to the electrode located on the gun axis side. In addition, by providing an internal electrode that deflects the side beam toward the center beam by applying a voltage lower than the voltage applied to the final focusing electrode to an electrode located away from the gun axis, the electrode forming the main lens can be deflected. A compact electron gun can be constructed without eccentricity or tilt, and without increasing the drift space, and the compact electron gun allows multiple beams to be easily focused onto the phosphor screen.

[Brief explanation of the drawing]

1 to 5 are detailed explanatory diagrams of the present invention, in which FIG. 1 is a diagram showing the configuration of an electron gun disposed in an in-line color picture tube, which is an embodiment of the invention, and FIG. 2(a) and (b
) are a plan view and a sectional view taken along the line b-b of the first electrode constituting the internal electrode arranged inside the third grid, respectively, and FIGS. 3(a) and (b) respectively are the same constituting the internal electrode. 4 is a sectional view showing the configuration of the internal electrode, FIG. 5 is a diagram showing the configuration of the in-line color picture tube, and FIG.
11 are explanatory diagrams of a conventional in-line color picture tube, FIG. 6 is a diagram showing the configuration of its pi-potential type electron gun, FIG. 7 is a diagram showing the electric field of its main lens, and FIG.
The figure is a diagram for explaining the effect of the main lens on the side beam, and FIGS. 9(a) and 9(b) respectively show three cases in which the pi-potential type electron gun is applied to a large tube.
A diagram showing a concentrated state of an electron beam and a diagram showing a concentrated state when applied to a small tube, FIG. 1O is a diagram showing a different configuration of an electron gun, and FIG. 1I is a diagram for explaining the action of parallel plate electrodes. It is. 7... Phosphor screens 14B, 14R... A pair of side beams 14B...
Center beam 15... Electron gun 19... Internal electrode 20
B, 20G, 2OR...electron beam passing hole 21a, 2
1b...First plate-shaped electrode part 22...First electrode 23...Electron beam passing holes 24a, 24b...Second plate-shaped electrode part 25...Second electrode H...Heater G1 ...1st Grid G
2...Second grid G3...Third grid G
4...Fourth Grid KB, KG, KR...Cathode Agent Patent Attorney Norihiro Ogo II! I Figure 2 Figure 3 Figure 4 Figure 15 Figure 6 Figure 7 HS Figure Figure 10

Claims (1)

[Claims] It has an electron gun that emits multiple beams arranged in a row consisting of a center beam and side beams that pass on the same plane,
This electron gun controls electron emission from the cathode and focuses the emitted electrons to form a plurality of parallel beams arranged in a row. In a cathode ray tube consisting of a plurality of electrodes forming a main lens that accelerates and focuses emitted beams onto a phosphor screen, a side beam passes through a region in the final focusing electrode forming the main lens. Electrodes that are parallel to the gun axis and opposite to each other in the arrangement direction of the plurality of beams are arranged, and the same voltage as that applied to the final focusing electrode is applied to the electrode located on the gun axis side among these opposing electrodes, and the gun A cathode ray tube characterized in that an internal electrode is provided for deflecting the side beam toward the center beam by applying a voltage lower than the voltage applied to the final focusing electrode to an electrode located away from the axis.