JPH10112268A - Color crt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the build-up characteristic of electron emission, particularly at the initial stage after a power supply has been turned on in a color CRT of a color picture tube or a color display tube. SOLUTION: This color CRT is provided with a cathode structure, constituted of multiple tubular cathodes 7 laterally arranged in a line and emitting multiple electron beams and an electron gun buried with a control electrode facing the cathode structure and having multiple electron beam passing holes and multiple electrodes including an accelerating electrode, a focusing electrode, and an anode arranged in sequence from the control electrode side to a fluorescent screen side in an insulating supporter and fixed at the fixed intervals in the tube axial direction. The cathode structure is constituted of a metallic cathode supporter 5 fixed with one end of the tubular cathode 7 in it and an insulating substrate 6 penetrated by the cathode supporter 5 and holding it at the prescribed interval at one end on the opposite side to the portion 5a fixing the tubular cathode 7. The portion 5a, fixing the tubular cathode 7 and the portion 5b fixed to the insulating substrate 6 of the cathode carrier 5, are made of metals with different thermal expansion coefficients.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color cathode ray tube such as a color picture tube or a color display tube, and more particularly to a color cathode ray tube provided with a cathode assembly having improved startup characteristics of electron emission at the initial stage of power-on. .

[0002]

2. Description of the Related Art A color cathode ray tube such as a color picture tube or a display tube is widely used as a monitor for television broadcast reception or information processing equipment because of its fine image reproducibility.

A color cathode ray tube of this type contains a funnel having a face plate having a phosphor screen formed on an inner surface thereof, and an electron gun assembly connected to the funnel and emitting an electron beam toward the phosphor screen. A vacuum envelope having at least a neck.

FIG. 6 is a schematic cross-sectional view for explaining the configuration of a shadow mask type color cathode ray tube as an example of a color cathode ray tube to which the present invention is applied. Reference numeral 20 denotes a face plate, 21 denotes a neck, and 22 denotes a face plate. A funnel 23 connected to the neck; a phosphor screen 23 formed on the inner surface of the face plate to form a video display surface;
4 is a shadow mask as a color selection electrode, 25 is a mask frame that holds the shadow mask and forms a shadow mask structure, 26 is an inner shield that shields external magnetism, and 27 is the shadow mask structure planted on the inner wall of the face plate. A suspension spring mechanism for suspending and supporting a standing stud, 28 is housed in a neck and accommodates three electron beams Bs
(× 2), an electron gun that emits Bc horizontally (inline), 29 is a deflecting device that deflects the electron beam horizontally and vertically, and 30 is a magnetic device that performs color purity and centering correction.

In the configuration shown in FIG.
0, a neck 21 and a funnel 22 constitute a vacuum envelope, and deflect the two electron beams Bc and Bs (× 2) emitted from the electron gun 28 in a horizontal line (inline).
The phosphor screen 23 is two-dimensionally scanned by being deflected in two directions, horizontal and vertical, by the deflection magnetic field formed in 9. Note that Bc indicates a center beam and Bs indicates a side beam.

The three electron beams Bs and Bc (× 2) are red (side beam Bs) and green (center beam Bs), respectively.
c) modulated by color signals of blue (side beam Bs), red, green, and red constituting the phosphor screen 23 by receiving a color selection through a beam passage hole of a shadow mask 24 disposed immediately before the phosphor screen 23; A desired color image is reproduced by projecting on each of the three blue phosphor mosaics.

FIG. 7 is a side view of an essential part for explaining an example of the structure of an electron gun structure used for a color cathode ray tube. Reference numeral 31 denotes a cathode structure arranged in line, 32 denotes a first electrode serving as a control electrode, 33 is a second electrode which is an accelerating electrode, 34 is a third electrode
Electrode, 35 is a fourth electrode, 36 is split electrodes 361 and 362
A fifth electrode (focusing electrode), 37 is an anode, 38 is a shield cup fixed to the anode, 39 is an insulating support (beading glass), 40 is an electron gun sealed in the neck of the vacuum envelope Reference numeral 41 denotes a stem pin for supplying a required signal and voltage to each electrode of the electron gun.

The first electrode 32 containing the cathode structure 31 and the other electrodes 33 to 37 are buried and fixed to the insulating support 39 at predetermined intervals. Each electrode is supplied with a required signal and voltage from an external circuit via a stem pin 41. The highest voltage is applied to the anode 37 from an anode terminal (not shown) provided on the wall surface of the funnel through an internal conductive film (not shown).

In this type of electron gun, the first electrode 32 is a cup-shaped electrode in which the cathode structure 31 is housed and fixed. In addition, the first electrode is formed of a plate-shaped electrode.
There is also an electron gun of a type in which the cathode structure is also independently embedded and fixed in the insulating support 39. The present invention is applicable to any of the above types of electron guns.

FIG. 8 is an in-line sectional view for explaining an example of the configuration of a conventional cathode structure of the above-mentioned electron gun.
Is an electron emission surface, 2 is a cap-shaped base metal, 3 is a sleeve, 4 is a metal sleeve support for supporting the lower end of the sleeve, 5 is a metal cathode support having the lower end of the sleeve fixed inside, 6 Is an insulating substrate which is held at a predetermined interval at one end opposite to the portion where the cylindrical cathode is fixed by penetrating the cathode support, and 7 is a cylindrical cathode.

Although a heater is housed inside each cylindrical cathode, it is not shown in FIG.

In FIG. 1, a cylindrical cathode 7 is constituted by an electron emission surface 1, a base metal 2, a sleeve 3, and a sleeve support 4, and the cylindrical cathode 7 is inserted into a cylindrical cathode support 5. And welded to the cathode support in the vicinity of the lower end of the sleeve support, penetrated this through an insulating substrate 6 made of a glass-based material so that the cylindrical cathodes 7 were arranged at predetermined intervals, and fixed by welding. Is configured.

The cathode assembly is fixed together with other electrodes constituting the electron gun to the insulating support rod 39 (see FIG. 7) in a predetermined relationship to assemble an in-line type electron gun.

Japanese Patent Application Laid-Open (JP-A) No. 63-294462 can disclose a prior art relating to this kind of cathode structure.

[0015]

In the above-described cathode structure 7 constituting the conventional electron gun, the cathode support 5 and the insulating substrate 6 are provided.
If the thermal expansion coefficients are different, the bonding strength between the two is reduced, cracks occur in the insulating substrate 6, and the cathode assembly 7 falls off.

Therefore, conventionally, a Kovar material having a thermal expansion coefficient substantially equal to that of the insulating substrate 6 is used as a material of the cathode support 5, and a single cylindrical support is used as a whole.

The lower end of the electrode support 5 (control electrode: first electrode
Weld the lower end of the sleeve support 4 at the side opposite to the electrodes)
The cathode support 5 and the insulating substrate 6 are fixed at the upper end (control electrode: first electrode side) of the cathode support 5. In addition, x mark in a figure shows a welding point or a fixing point.

In such a configuration, when the heater is energized when the cathode ray tube is started, a so-called cathode current flows through the cathode structure. The cathode current increases as the distance between the cathode structure and the first electrode (control electrode) decreases, and the luminance on the screen increases.

At the time of starting, first, the cathode assembly 7 is heated and thermally expanded, and moves toward the first electrode. Next, the heat moves from the cathode structure 7 to the cathode support 5 so that the cathode structure 7 moves in a direction away from the first electrode. Thereafter, the thermal expansion is completed, and the distance between the cathode structure, the first electrode, and the other electrodes becomes a predetermined distance, so that the cathode current is stably at a constant value and the luminance on the screen is also constant.

However, since the conventional cathode structure is fixed to the insulating substrate 6 by the single cathode support 5, the cathode structure 7 due to the thermal expansion of the cathode support 5 and the control electrode, which is the first electrode, are not provided. It takes a long time for the interval between to stabilize to the predetermined interval, and therefore, there is a problem that it is necessary to wait a long time until the screen luminance of the color cathode ray tube becomes constant.

An object of the present invention is to provide a color cathode ray tube provided with an electron gun having a cathode structure in which the time until the screen luminance is stabilized by solving the above-mentioned problems of the prior art.

[0022]

In order to achieve the above object, the present invention is directed to a first member for fixing a cathode support to an insulating substrate and a second member for welding a sleeve support to a first member for fixing the cathode support to the insulating substrate. The first member and the second member are made of dissimilar metal materials having different coefficients of thermal expansion.

The thermal expansion coefficients of the first member and the second member are as follows:
When the rise of the screen luminance is slow, a metal material having a larger thermal expansion coefficient of the second member than that of the first member is used. Conversely, when the rise of the screen luminance is fast, the thermal expansion coefficient of the second member is set to the first member. Use a smaller metal material than that of

In general, the rise of the screen luminance is slow, and the cathode structure at the start of the cathode ray tube is selected so as to minimize the amount of separation from the control electrode (first electrode). In the case of the structure shown, by making the coefficient of thermal expansion of the second member larger than the coefficient of thermal expansion of the first member, the variation in the distance between the cathode assembly and the first electrode is reduced, and the time required to reach stable luminance Is shortened.

That is, a first aspect of the present invention provides a cathode assembly comprising a plurality of cylindrical cathodes for emitting a plurality of electron beams arranged in a horizontal row, and at least a horizontal row opposed to the cathode. A control electrode having a plurality of electron beam passage holes corresponding to the cathode, and a plurality of electrodes including an acceleration electrode, a focusing electrode, and an anode sequentially arranged from the control electrode side to the phosphor screen side are embedded in an insulating support. In a color cathode ray tube provided with an electron gun fixed at a constant interval in the tube axis direction, the cathode structure includes a metal cathode support having one end of the cylindrical cathode fixed therein, and the cathode support. An insulating substrate that holds the cylindrical cathode at a predetermined interval at one end opposite to a portion where the cylindrical cathode is fixed by penetrating the body, and a portion of the cathode support that fixes the cylindrical cathode and the insulating substrate. And the part to be fixed to Characterized by being configured with different expansion coefficients of metal.

According to this configuration, the fluctuation in the distance between the cathode structure and the control electrode is reduced, and the time required to reach a stable luminance is shortened.

According to a second aspect of the present invention, the length of the second portion is longer than the length of the first portion of the cathode support.

With this configuration, it is possible to avoid a delay in the thermal expansion of the second portion and to reduce the variation in the interval between the cathode structure and the control electrode, thereby shortening the time required for achieving a stable luminance.

[0029] Further, the third invention according to claim 3 provides:
The control electrode according to the first or second aspect of the present invention is characterized in that the control electrode comprises a cup-shaped electrode containing the cathode structure, and the insulating substrate is fixed to the inner wall and fixed to the insulating support.

According to this configuration, the interval between the cathode structure and the control electrode containing the cathode structure is reduced, and the time required to reach a stable luminance is shortened.

Further, the fourth invention according to claim 4 is as follows.
The control electrode in the first or second aspect of the invention is a plate-like electrode independent of the cathode structure, and the insulating substrate to which a cathode support that holds the cathode structure at a predetermined interval is fixed is used as the insulating support. It is characterized by being fixed.

According to this configuration, the fluctuation in the distance between the cathode structure and the control electrode provided in close proximity to the cathode structure is reduced, and the time required to reach a stable luminance is shortened.

The present invention is applicable not only to a color cathode ray tube electron gun having an in-line electron gun, but also to a monochrome cathode ray tube or a projection cathode ray tube having a single electron gun for emitting a single electron beam, or to other types. Can be similarly applied to the cathode ray tube.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to reduce the time-dependent change in the interval between the cathode structure and the control electrode and to shorten the rise time of the luminance on the screen, the position fluctuation due to the thermal expansion of the cathode structure and the control electrode is stabilized. It is necessary to shorten the time until.

The present invention comprises a first member for fixing a cathode structure to an insulating substrate, a first member for fixing the cathode structure to the insulating substrate, and a second member for welding the sleeve support to the first member and the second member.
Embodiments of the present invention will be described in detail below with reference to examples, in which each of the members is made of a dissimilar metal material having a different coefficient of thermal expansion.

FIG. 1 is a sectional view in the in-line direction for explaining the structure of an embodiment of a cathode structure of an electron gun provided in a color cathode ray tube according to the present invention, wherein the same symbols as those in FIG. The first member 5b is a second member.

The overall structure of this cathode structure is the same as that described with reference to FIG. 8, and the electron emission surface 1, base metal 2, sleeve 3, and sleeve support 4 constitute a cylindrical cathode 7. The cathode 7 is inserted through the inside of the cylindrical cathode support 5 and welded to the cathode support near the lower end of the sleeve support.

In the cathode support 5, a first portion for fixing the cylindrical cathode 7 and a second portion for fixing the cathode support 5 to the insulating substrate 6 are made of metals having different coefficients of thermal expansion. A first portion for fixing the cylindrical cathode 7 is a first member 5a,
The second part for fixing the cathode support 5 to the insulating substrate 6 is a second part.
When the member 5b is used, the coefficient of thermal expansion of the second
It is formed by using a metal material larger than that of the member, and the two are joined by butt welding or the like to be integrated into a single cylindrical member.

The cathode support 5 thus constructed is passed through an insulating substrate 6 made of a glass-based material so that the respective cylindrical cathodes 7 are arranged at predetermined intervals in-line, and fixed by welding to form a cathode assembly. I do. The welding of the insulating substrate 6 and the cathode support 5 is performed by performing metallization on the inner wall of the through-hole formed in the insulating substrate 6 so that the welding is performed with the cathode support 5 which is a metal material. Alternatively, both may be fixed using another appropriate fixing method.

In this embodiment, the first member 5a constituting the cathode support 5 is made of a Kovar material (thermal expansion coefficient: 50 × 10 ⁻⁷ / ° C.) having substantially the same thermal expansion coefficient as the insulating substrate 6. Then, as a second member 5b, a stainless steel material (thermal expansion coefficient: 1)
85 × 10 ⁻⁷ / ° C.).

Further, by making the length of the second member 5b longer than that of the first member 5a, it is possible to prevent the sleeve 3 from abnormally approaching the control electrode due to a delay in heat transmission. The setting of the length of the first member and the length of the second member depends on the characteristics of the applied electron gun. The cathode structure 31 in which the three cathode structures 7 are integrated as described above is fixed to the insulating support rod 39 (see FIG. 7) together with the other electrodes constituting the electron gun in a predetermined relationship with each other to form an in-line type. Assemble the electron gun.

FIGS. 2A and 2B are explanatory views of the detailed structure of the control electrode and the cathode structure when a cup-shaped electrode having a built-in cathode structure is used as the control electrode. FIG. 2A is a sectional view, and FIG. (A) is a plan view as seen from the direction of arrow A, and (c) is a side view as seen from the direction of arrow B in (b).

The control electrode 32 is a cup-shaped electrode having three electron beam passage holes 32B, 32G, and 32R at the bottom, and has three cylindrical cathodes 7 arranged in-line therein.
Are housed to form an integrated structure.

As described with reference to FIG. 1, the three cylindrical cathodes 7 are supported by the insulating substrate 6 and a metal fixing member 7a is fixed around the insulating substrate 6, and this fixing member 7a is
2 and are integrated by welding to the cup-shaped inner wall.

The control electrode 32 is fixed by embedding a pair of fixing pieces 32a attached to its outer wall into an insulating support rod (not shown) of the electron gun.

FIG. 3 is a cross-sectional view taken along the line CC of FIG. 2B. As described with reference to FIG. 2, the cathode structure comprises three cylindrical cathodes 7 formed of an insulating substrate 6. It is arranged and fixed in-line, and the cup-shaped control electrode 3 is fixed via the fixing member 7a.
2 is fixed inside.

In this fixing, welding is performed only on the side wall in the in-line direction shown in FIG. 2, and a gap is provided between the side wall (the mounting side of the fixing piece 32a) perpendicular to the in-line direction shown in FIG. You may leave.

FIG. 4 is an explanatory diagram of the rise characteristics of the screen luminance of a color cathode ray tube using an electron gun having the structure of the cathode assembly according to the present invention, and the horizontal axis indicates the elapsed time (minutes) since the power was turned on. The vertical axis indicates luminance (relative value).

In the same figure, a shows the luminance rise characteristics when the cathode support is formed of Kovar alone (conventional);
Shows the luminance rise characteristics of the embodiment of the present invention in which the cathode support is formed of a first member made of Kovar and a second member made of stainless steel and butt-welded.

In the case of using a Kovar cathode support alone, it takes about 20 minutes from turning on the power supply to stabilizing the brightness. On the other hand, in the case of using a Kovar and stainless steel cathode support, 30 seconds to 1 minute is required. It can be seen that the luminance stabilizes in minutes.

FIGS. 5A and 5B are explanatory views of the structure of another embodiment of the cathode structure of the electron gun provided in the color cathode ray tube according to the present invention, wherein FIG. 5A is a sectional view, and FIG. FIG. 4 is a plan view as viewed from a direction A (control electrodes are not shown), and FIG. 4C is a side view as viewed from a direction indicated by an arrow B in FIG.

2, the same reference numerals as in FIG. 2 correspond to the same parts, 7b is a fixed support member fixed around the insulating substrate 6, 7c is a fixed piece 32 'is a control electrode, and 32'B, 3'
2'G and 32'R are electron beam passage holes.

In this embodiment, the control electrode 32 'uses a plate-like electrode independent of the cathode structure, and the cathode structure also insulates the fixing piece 7c independently of the control electrode 32'. It is buried in and fixed.

The cathode support 5 of this embodiment is also composed of a butt-welded member of the first member 5a and the second member 5b as in the previous embodiment, and the structure for fixing the cathode assembly and the insulating substrate 6 is also shown in FIG. This is the same as that described above.

According to this embodiment as well, the time from when the power is turned on until the screen luminance stabilizes can be shortened in the same manner as in the previous embodiment.

The lengths of the first and second members constituting the cathode support in each of the above embodiments are selected according to the magnitude of thermal expansion. Further, in particular, as shown in FIG. 1, the cathode structure located at the center where the temperature rises sharply,
If the length of the first member 5a is made longer than that of the other cathode structures located on the side, substantially the same luminance stabilization time can be obtained for the three cathode structures. First member and second
The materials of the members are not limited to those shown in the above-described embodiments.

In each of the above embodiments, when the power is turned on,
First, the cathode assembly 7 is heated and thermally expanded, and moves toward the first electrode side, and then heat moves from the cathode assembly 7 to the cathode support 5 so that the cathode assembly 7 moves away from the first electrode. Although the configuration in the case of the above is described, if it is desired to obtain the opposite effect, the selection of the coefficient of thermal expansion of the first member and the second member may be reversed. Further, a structure in which the fixing positions of the cathode structure and the insulating substrate are changed without changing the structure may be adopted.

[0058]

As described above, according to the present invention,
The time required for the screen luminance to be constant is reduced without requiring a long time until the interval between the cathode structure and the control electrode as the first electrode is stabilized at a predetermined interval due to the thermal expansion of the cathode support. A color cathode ray tube can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view in the in-line direction illustrating a configuration of an embodiment of a cathode structure of an electron gun provided in a color cathode ray tube according to the present invention.

FIG. 2 is an explanatory view of a detailed structure of a control electrode and a cathode structure when a cup-shaped electrode having a built-in cathode structure is used as the control electrode.

FIG. 3 is a sectional view taken along line CC of FIG. 2 (b).

FIG. 4 is an explanatory diagram of a rise characteristic of a screen luminance of a color cathode ray tube using an electron gun having a structure of a cathode assembly according to the present invention.

FIG. 5 is an explanatory view of the configuration of another embodiment of the cathode structure of the electron gun provided in the color cathode ray tube according to the present invention.

FIG. 6 is a schematic cross-sectional view illustrating a configuration of a shadow mask type color cathode ray tube as an example of a color cathode ray tube to which the present invention is applied.

FIG. 7 is a main part side view for explaining a configuration example of an electron gun structure used for a color cathode ray tube.

FIG. 8 is an in-line sectional view illustrating a configuration example of a cathode structure of a conventional electron gun.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electron emission surface 2 Cap-shaped base metal 3 Sleeve 4 Sleeve support 5 Cathode support 5a 1st member 5b 2nd member 6 Insulating substrate 7 Cylindrical cathode.

Continued on the front page (72) Inventor Yukio Koizumi 3300 Hayano, Mobara-shi, Chiba Pref.Electronic Device Division, Hitachi, Ltd.

Claims (4)

[Claims] 1. A cathode structure comprising a plurality of cylindrical cathodes for emitting a plurality of electron beams arranged in a horizontal line, and a plurality of cathode structures corresponding to the cylindrical cathodes at least in a horizontal line facing the cylindrical cathode. A control electrode having an electron beam passage hole, and a plurality of electrodes including an accelerating electrode, a focusing electrode, and an anode sequentially arranged from the control electrode side to the fluorescent screen side are embedded in an insulating support rod to maintain a constant in the tube axis direction. In a color cathode ray tube having an electron gun fixed at intervals, the cathode structure is a metal cathode support having one end of the cylindrical cathode fixed inside, and the cathode structure is formed by penetrating the cathode support. A first portion for fixing the cylindrical cathode in a longitudinal direction of the cathode support, and a first portion for fixing the cylindrical cathode at an end opposite to a portion to which the cylindrical cathode is fixed, the insulating substrate being held at a predetermined interval; Thermal expansion with the second part to be fixed to the substrate Color cathode ray tube, characterized in that is constituted by different metals of coefficients. 2. The color cathode ray tube according to claim 1, wherein a length of the second portion is longer than a length of the first portion of the cathode support. 3. The control electrode comprises a cup-shaped electrode containing the cathode structure, wherein the insulating substrate is fixed to the inner wall and fixed to the insulating support. 2. The color cathode ray tube according to 2. 4. The control electrode comprises a plate-like electrode independent of the cathode structure, and the insulating substrate to which a cathode support for holding the cathode structure at a predetermined interval is fixed is fixed to the insulating support. 3. A color cathode ray tube according to claim 1, wherein: