JPH07245056A - Indirectly heated cathode body structure for cathode-ray tube - Google Patents

Abstract

PURPOSE:To provide a cathode body structure of a cathode-ray tube capable of shortening the depth length of a cathode-ray tube, also reducing the power consumption of the cathode body structure (cathode), and moreover shortening image outputting time. CONSTITUTION:A cathode 30 has an insulating disk 48; a base metal support 60 retained by the insulative disk 48, and having base metal, having an electron emission substance generating a thermoelectron by heating, in at least a part; and a heater 72 arranged in a bare condition on the back surface side of a base metal support 64 having the electron emission substance, and retained by the insulative disk 48. A reflecting plate 76 is retained in the opening part 52 of the insulative disk 48 so as to be positioned on the back surface side of the heater 72. Three heaters are composed by coil-likely winding one heating wire at a given position. The base metal support is composed of a conductive plate material (preferably the base metal) having a folded part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an indirectly heated cathode assembly used for an electron gun of a cathode ray tube, and more specifically, to reduce the depth of the cathode ray tube and to consume the cathode assembly (cathode). The present invention relates to a cathode structure of a cathode ray tube capable of reducing electric power and further shortening an image output time.

[0002]

2. Description of the Related Art As shown in FIGS. 9 (A) and 9 (B), for example, a cathode assembly 2 used in an electron gun of a medium or large-sized color cathode ray tube having a size of 20 inches or more has three base metal sleeves 4R, It has 4G and 4B. Each sleeve 4R, 4G, 4
In B, a base metal (BM) 6 having an electron emitting substance that generates thermoelectrons when heated is attached to the tip portion thereof. Each base metal sleeve 4R, 4G, 4B
Is a cap or disc on which the base metal 6 is resistance-welded or laser-welded to the tip of the sleeve body 5.
It is manufactured by fitting the tip of the sleeve.

The sleeve body 5 has a diameter of 1 to 2 mm,
Ni or Ni with a thickness of 10 to 30 μm and a length of 6 to 7 mm
A Cr alloy cylinder is used. As the base metal 6,
A Ni metal to which a reducing agent such as Mg, W, or Si of several% or less is added is used.

Each base metal sleeve 4R, 4G, 4B
Are arranged so as to respectively pass through the three openings 10 formed in the ceramic disk 8. One end of each of a pair of V tabs 12, 14 formed by bending a thin metal wire into a V shape is welded to the outer circumference of the rear end side of each sleeve 4R, 4G, 4B. The other ends of the V tabs 12 and 14 are connected to the three pairs of metal pins 16 and 18 fixed to the back surface of the ceramic disk 8 by welding or the like. The metal pins 16 and 18 are fused and fixed to the ceramic disk 8 with glass or the like. Red (R), green (G), and blue (B) signals are input from the three pairs of metal pins 16 and 18, respectively.

On the back surface of the ceramic disk 8, in addition to the metal pins 16 and 18, a pair of heater rests 20 and 20 are provided.
4 metal pins for fixing the heater rest for fixing the
2 is fused and fixed by the same means as the metal pins 16 and 18. By welding the heater rests 20, 20 to the metal pins 22,
0 and 20 are fixed to the ceramic disk 8. The heater rests 20 and 20 have sleeves 4R and 4
The power supply terminals of the heaters mounted inside G and 4B are respectively connected. That is, the heater rests 20, 20
To each sleeve 4 by applying a predetermined voltage to
The heaters mounted inside the R, 4G, and 4B are heated.

Powders of ternary carbonates such as barium, strontium and calcium are sprayed onto the base metal 6 at the tips of the sleeves 4R, 4G and 4B to form an electron emitting material layer.

[0007]

In the cathode assembly 2 according to the conventional example as described above, the total length L from the electron emitting material layer of the base metal 6 to the rear end of the heater rest 20 is as long as about 12 mm. As a result, the length becomes long, and as a result, it is difficult to reduce the depth length of the cathode ray tube. This is mainly due to the sleeves 4R, 4
It is in the length of G and 4B (6 to 7 mm). The function of the sleeve is to hold the base metal 6 and to suppress heat dissipation from the heater.

However, each sleeve 4R, 4G, 4
The portion of the heater mounted in B that contributes to heating the base metal 6 to a required temperature (for example, about 800 ° C.) is about ½ of the entire length of the heater on the base metal side. The portion of does not contribute to the heating of the base metal 6.
That is, about half of the heat quantity of the heater is the sleeve 4R,
While dissipating heat from 4G, 4B to the first grid, etc.,
It escapes to the ceramic disk 8 by heat conduction,
It does not contribute to the heating of the base metal 6.

Therefore, it is conceivable to simply shorten the axial length of each of the sleeves 4R, 4G, and 4B. However, in the conventional structure, the sleeves 4R, 4G, and 4B are connected to the V tabs 12 and 1.
Since it is held at 4, it is difficult to simply shorten it. Therefore, in the conventional cathode assembly 2, the cathode assembly 2
It is unavoidable that the total length L becomes long, and it is inevitable that the power consumption becomes as large as 3 to 3.5 watts (total of three colors).

The present invention has been made in view of such circumstances, and aims to shorten the depth of the cathode ray tube, reduce the power consumption of the cathode structure (cathode), and further shorten the image output time. It is an object of the present invention to provide a cathode assembly of a cathode ray tube which can be manufactured.

[0011]

In order to achieve the above object, the cathode assembly of the cathode ray tube according to the present invention generates an insulating disk and a thermoelectron by being held by the insulating disk and heated. The base metal holder having at least a part of the base metal having the electron emitting substance, and the base metal holder having the electron emitting substance, which are arranged in a bare state on the back side and held by the insulating disk. And a heater.

It is preferable that a reflecting plate is held on the insulating disk so as to be located on the back side of the heater. It is preferable that an opening is formed in the insulating disk in a direction substantially orthogonal to the base metal holder, and the reflector is mounted in the opening.

The insulating disc is composed of a ceramic disc, and at least a pair of metal pins are fusion-bonded and fixed to the ceramic disc by glass, and the base metal holding member is attached to the tips of the metal pins. It is preferable that both ends of the body are joined.

Three pairs of metal pins are fixed in parallel to the insulating disk, and both ends of the three base metal holders are joined to the tip portions of the metal pins of each pair. It is preferable that a heater composed of an electric heating coil is arranged on the back surface side of each of the base metal holders having the electron emitting substance, and these electric heating coils are composed of one heating wire.

It is preferable that the base metal holder is made of a conductive plate material having a bent portion, and the bent portion absorbs thermal expansion of the base metal holder toward the grid side. More preferably, the entire base metal holder is made of a base metal, and the central portion of the base metal holder is coated or impregnated with an electron emitting substance.

[0016]

In the indirectly heated cathode assembly of the cathode ray tube according to the present invention,
The sleeve is eliminated, and the bare heater is arranged on the back surface of the base metal holder having the base metal in at least a part thereof.

That is, in the present invention, since the sleeve for holding the base metal is not provided, the total length of the cathode assembly (the total length in the tube axis direction of the cathode ray tube) can be reduced to about half that of the conventional one. it can. Moreover, since the base metal is efficiently heated by the heater, power consumption can be reduced.

In particular, in the cathode assembly in which the reflector is mounted on the back side of the bare heater, the efficiency of heating the base metal by the heater is further improved, and the power consumption can be further reduced. In addition, since there is no sleeve and the base metal part is heated directly by a bare heater, the heat capacity of the heated part is small, the temperature of the base metal part rises quickly, and the output time (switch on It is possible to shorten the time from when the image is captured to the image.

When the base metal holder is made of a conductive plate material having a bent portion, and the bent portion is configured to absorb the thermal expansion of the base metal holder to the grid side, The change in the distance between the base metal and the first grid due to expansion can be suppressed, and the change in the cutoff voltage after the switch is turned on until the operating temperature of the cathode structure is reached can be reduced to about 1% or less. . For this reason, it is possible to suppress color misregistration during image output. In the conventional cathode assembly, the change in cutoff voltage was about 5.6%.

If an opening is formed in the insulating disk in a direction substantially orthogonal to the base metal holder, and the reflector is mounted in the opening, an increase in the total length of the cathode assembly due to the mounting of the reflector is suppressed. can do. If the heaters that respectively heat the base metal portions corresponding to the three primary colors are composed of electric heating coils, and these electric heating coils are composed of one heating wire,
It is not necessary to prepare a heater for each sleeve as in the conventional case, and the wiring is easy and the thermal efficiency is improved.
The heater composed of this one heating wire can be arranged along the opening formed in the insulating disk, and the overall length of the cathode assembly can be made compact.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The indirectly heated cathode structure (cathode) of a cathode ray tube according to the present invention will be described below in detail with reference to the embodiments shown in the drawings. The indirectly heated cathode 3 of this embodiment shown in FIGS.
0 constitutes an electron gun 34 of a cathode ray tube (CRT) 32 shown in FIG. 6, for example, together with a grid group (not shown). As shown in FIG. 6, the CRT 32 has a panel glass 3
6 and the funnel glass 38, which are fused by the frit glass 39, and the inside is maintained in a high vacuum. The electron gun 3 is attached to the neck 40 of the funnel glass 38.
4 is built in. A fluorescent screen 42 is formed on the inner surface of the panel glass 36, and the aperture grill 4 is formed on the back surface of the fluorescent screen 42.
4 is attached. Further, a deflection yoke 46 is attached to the outer periphery of the neck portion 40, and the three electron beams emitted, controlled, accelerated, and focused from the electron gun 34 are deflected by the deflection yoke 46, thereby causing fluorescence. The entire surface 42 is scanned.

As shown in FIGS. 1 (A), (B) and FIG. 2, the cathode 30 of this embodiment has a disk-like (having cutouts 50, 50 at two opposing positions) insulating property. It has a disk 48. The insulating disk 48 is made of a material having insulating properties and heat resistance, and is made of, for example, ceramic. For example, forsterite, steatite, alumina or the like can be used as the ceramic.

At the center of the insulating disk 48, an elongated hole-shaped opening 52 is formed which is substantially parallel to the notch 50. Three pairs of cathode metal pins 54 are fixed in the holes penetrating the front and back surfaces of the disk 48 on both sides along the longitudinal direction of the slot-shaped opening 52. These cathode metal pins 54 are fixed to the disk 48 by means such as heat fusion of glass.

A pair of heater metal pins 56, 56 and a reflector holding metal pin 58, 58 are arranged between the three pairs of cathode metal pins 54. These metal pins 56, 58 are provided. Are fused and fixed to the disk 48 with glass. Unlike the cathode metal pin 54, these metal pins 56 and 58 project only on the back surface of the disk 48.

At the tips of the three pairs of metal pins 54 for cathode,
Both ends 62, 62 of the base metal holder 60 having the shape shown in FIG. 3 are fixed by means such as welding. After this welding, it is preferable to wash with ion-exchanged water or an organic solvent (acetone, ethanol, etc.) for the purpose of removing dirt. Then, after drying, it is preferable to perform heat treatment at 1050 ° C. for 30 to 60 minutes in an atmosphere of hydrogen (dew point −70 ° C. or lower) so as to remove mechanical strain generated by welding.

The base metal holder 60 has a disk-shaped electron emitting portion 64 at the center thereof. Base metal holder 60
Is made of a conductive plate material in which at least the electron emitting portion 64 is made of a base metal. Preferably, the entire base metal holder 60 is made of base metal. As the base metal,
For example, nickel Ni with several percent or less of magnesium M
An alloy containing a reducing agent such as g, tungsten W, or silicon Si is used.

When the base metal and the base metal holder 60 are separately formed, the base metal is spot-welded or laser-welded to the electron emitting portion 64 of the base metal holder 60. An electron emitting material is applied to or impregnated in the electron emitting portion 64 made of a base metal. As a specific means for applying the electron emitting substance to the electron emitting portion 64, for example, a means for spraying a ternary carbonate powder of barium, strontium or calcium with a spray gun or the like can be exemplified. The coating thickness is not particularly limited, but is, for example, 50 to 100 μm.

As shown in FIG. 3, the base metal holder 60.
Is between the electron emitting portion 64 and its both ends 62, 62,
A bent portion 66 is formed. Each bent portion 66 has a first piece 6
8 and a second piece 70. The base metal holder 60 is heated by a heater and expands as described later.
The thermal expansion of the piece 68 and the thermal expansion of the second piece 70 are canceled out so that the position of the electron emitting portion 64 in the grid direction X hardly moves.

As shown in FIGS. 1 (A), 1 (B) and FIG. 2, bare heaters 72 are arranged close to each other behind each base metal holder 60. The heater 72 is composed of electric heating coils, and these electric heating coils are formed by winding a single heating wire 74 in a coil shape in each heater portion as shown in FIG. 4. The heating wire 74 is made of, for example, a pure tungsten wire or a tungsten alloy wire in which tungsten is doped with 2 to 3% of rhenium. The wire diameter of the heating wire 74 is, for example, 60
μm (11 MG). On the outer circumference of this heating wire 74,
In order to have electrical insulation, alumina powder (900
(Mesh) is coated and sintered. The heating wire 74 has, for example, an inner diameter of 0.6 mm and a pitch of 0.1 in the heater portion.
The heater 72 is configured by spirally winding about 17 mm and about 72 times.

Both ends of the heating wire 74 constituting the three heaters 72 are located on the back side of the reflection plate 76 through the through holes 78 formed in the reflection plate 76, as shown in FIGS.
A tungsten wire 80 shown in FIG. 4 is connected to the heater metal pin 56 shown in FIGS. 1 and 2 by welding or the like.

As shown in FIGS. 1 and 2, a reflection plate 76 is mounted in the opening 52 of the disk 48 located on the back surface of the heater 72 along the longitudinal direction thereof. Reflector 76
Has a semi-cylindrical shape, as shown in FIG.
It has a through hole 78 through which both ends of the heating wire are inserted.
Legs 82 are attached to both sides of the reflector 76 at alternate positions. The leg portion 82 is formed integrally with or separately from the reflection plate 76. The reflector 76 is made of a material having a low thermal conductivity, such as nichrome or nichrome-tungsten alloy. Further, the plate thickness is preferably about 30 μm or less for the reason of lowering the heat capacity and suppressing heat conduction.

The legs 82 of the reflector 76 are welded and fixed to the reflector holding metal pins 58, 58 shown in FIGS. As a result, as shown in FIGS.
Is the electron emitting portion 64 of the base metal holder 60 and the reflector plate 7.
It is arranged at a position sandwiched by 6 and 6, and the heat of the heater 72 is efficiently transferred to the back surface of the electron emitting portion 64.

Indirectly heated cathode (cathode structure) 3 of this embodiment
0 is attached to the beaded electron gun with the dimension between the first grid and the cathode set precisely.
Since the indirectly heated cathode 30 of this embodiment does not have a sleeve for holding the base metal, the total length of the cathode (the total length in the axial direction of the cathode ray tube) should be about half of that of the conventional one. You can Moreover, since the base metal is efficiently heated by the heater 72, power consumption can be reduced.

In particular, since the reflecting plate 76 is mounted on the rear side of the bare heater 72, the efficiency of heating the electron emitting portion 64 by the heater 72 can be further improved and the power consumption can be further reduced. For example, in the cathode 30 of this embodiment, the power consumption of the heater is as low as 2 watts or less for three colors. Incidentally, the conventional cathode was 3 to 3.5 watts (three colors). Further, since the rear surface of the electron emitting portion 64 is directly heated by the bare heater 72 without a sleeve, the heat capacity of the heated portion is small, the temperature of the base metal portion rises quickly, and the display time ( The time from when the switch is turned on to when the image is captured) can be shortened. For example, the cathode 30 of this embodiment has a short image output time of 5 seconds or less.

Moreover, in this embodiment, the base metal holder 60 is used.
Is made of a conductive plate material having a bent portion 66, and the bent portion 66 is configured to absorb the thermal expansion of the base metal holding member 60 toward the grid side. It is possible to suppress a change in the distance between the first grid and the first grid (not shown). Therefore, the change in the cutoff voltage after the switch is turned on until the operating temperature of the cathode is reached can be reduced to about 1% or less. For this reason, it is possible to suppress color misregistration during image output. In the conventional cathode, the change in cutoff voltage was about 5.6%.

Moreover, in this embodiment, the insulating disk 48 is used.
The opening 52 in the direction substantially orthogonal to the base metal holder 60.
Since the reflector plate 76 is formed in the opening 52, the increase in the total length of the cathode due to the attachment of the reflector plate 76 can be suppressed. Further, in the present embodiment, the heater 7 that heats the electron emitting portions 64 corresponding to the three primary colors, respectively.
2 is composed of an electric heating coil, and these electric heating coils are composed of a single heating wire 74. Therefore, it is not necessary to prepare a heater for each sleeve as in the conventional case, and the wiring becomes easy and the thermal efficiency is improved. Also improves. The heater 72 composed of this one heating wire can be arranged along the opening 52 formed in the insulating disk 48, and the overall length of the cathode can be made compact.

The present invention is not limited to the above-mentioned embodiments, but can be variously modified within the scope of the present invention. For example, in the above embodiment, a color CRT is used.
Although three base metal holders were placed on the insulating disk 48 for the purpose of this, for a black and white CRT, a single base metal holder may be placed on the insulating disk.

Further, the specific shape of the base metal holder is not limited to the above embodiment, but can be variously modified as shown in FIGS. In the embodiment shown in FIG. 7, the bent portion 66a of the base metal holder 60a is V-shaped. In the embodiment shown in FIG. 8, the bent portion 66a of the base metal holder 60a has a substantially right angle shape.

[0039]

As described above, according to the present invention, since the sleeve for holding the base metal is not provided, the total length of the cathode assembly (the total length in the tube axis direction of the cathode ray tube) is compared with the conventional one. It can be reduced to about half. Moreover, since the base metal is efficiently heated by the heater, power consumption can be reduced.

In particular, in the cathode structure in which the reflector is mounted on the back side of the bare heater, the efficiency of heating the base metal by the heater is further improved, and the power consumption can be further reduced. In addition, since there is no sleeve and the base metal part is heated directly by a bare heater, the heat capacity of the heated part is small, the temperature of the base metal part rises quickly, and the output time (switch on It is possible to reduce the time from when the image is captured to when the image is captured.

When the base metal holder is made of a conductive plate material having a bent portion and the bent portion is configured to absorb thermal expansion of the base metal holder toward the grid side, The change in the distance between the base metal and the first grid due to expansion can be suppressed, and the change in the cutoff voltage after the switch is turned on until the operating temperature of the cathode structure is reached can be reduced to about 1% or less. . For this reason, it is possible to suppress color misregistration during image output. In the conventional cathode assembly, the change in cutoff voltage was about 5.6%.

If an opening is formed in the insulating disk in a direction substantially orthogonal to the base metal holder, and the reflector is mounted in the opening, an increase in the total length of the cathode assembly due to the mounting of the reflector is suppressed. can do. If the heaters that respectively heat the base metal portions corresponding to the three primary colors are composed of electric heating coils, and these electric heating coils are composed of one heating wire,
It is not necessary to prepare a heater for each sleeve as in the conventional case, and the wiring is easy and the thermal efficiency is improved.
The heater composed of this one heating wire can be arranged along the opening formed in the insulating disk, and the overall length of the cathode assembly can be made compact.

[Brief description of drawings]

FIG. 1 (A) is a plan view of an indirectly heated cathode assembly according to an embodiment of the present invention, and FIG. 1 (B) is a BB shown in FIG. 1 (A).
It is sectional drawing which follows the line.

FIG. 2 is a half sectional arrow view taken along line II-II shown in FIG.

FIG. 3 is an arrow view of the base metal holder shown in FIGS.

FIG. 4 is a front view of the heater shown in FIGS.

FIG. 5 is a perspective view of the reflector shown in FIGS.

FIG. 6 is a schematic view of a cathode ray tube.

FIG. 7 is a front view of a base metal holder used in a cathode according to another embodiment of the present invention.

FIG. 8 is a front view of a base metal holder used in a cathode according to another embodiment of the present invention.

FIG. 9 (A) is a half sectional arrow view of a cathode according to a conventional example, and FIG. 9 (B) is a bottom side arrow view taken along the line BB of FIG. 9 (A).

[Explanation of symbols]

 30 ... Indirect heating type cathode assembly (cathode) 48 ... Insulating substrate 52 ... Opening 54 ... Cathode metal pin 56 ... Heater metal pin 58 ... Reflector plate holding metal pin 60 ... Base metal holder 64 ... Electron emission part 66 ... Bent portion 72 ... Heater 74 ... Heating wire 76 ... Reflector

Claims (7)

[Claims] 1. An insulating disk, a base metal holder having at least a part of a base metal having an electron emitting substance which is held by the insulating disk and is heated to generate thermoelectrons, and this electron emission. On the back side of the base metal holder having the substance,
An indirectly heated cathode structure of a cathode ray tube, which is arranged in a bare state and has a heater held by the insulating disk. 2. The heater is located on the back side of the heater,
The indirectly heated cathode structure for a cathode ray tube according to claim 1, wherein a reflecting plate is held on the insulating disk. 3. The insulating disk according to claim 2, wherein an opening is formed in a direction substantially orthogonal to the base metal holder, and the reflector is mounted in the opening. Indirectly heated cathode assembly for cathode ray tubes. 4. The insulating disc is made of a ceramic disc, and at least a pair of metal pins are fused and fixed to the ceramic disc by glass. The indirectly heated cathode structure for a cathode ray tube according to claim 1, wherein both ends of the metal holder are joined. 5. Three pairs of metal pins are fixed in parallel to the insulating disk, and both ends of the three base metal holders are attached to the tips of the metal pins of each pair.
A heater composed of an electric heating coil is arranged on the back side of each of the base metal holders having the above-mentioned electron emitting materials, which are bonded to each other,
The indirectly heated cathode structure for a cathode ray tube according to claim 4, wherein each of the heating coils is composed of one heating wire. 6. The base metal holder is made of a conductive plate material having a bent portion, and the bent portion is configured to absorb thermal expansion of the base metal holder toward the grid side. An indirectly heated cathode assembly for a cathode ray tube according to any one of 1 to 5. 7. The cathode ray tube according to claim 1, wherein the entire base metal holder is made of a base metal, and the central portion of the base metal holder is coated or impregnated with an electron emitting substance. Indirectly heated cathode assembly.