JPS6353661B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an electron gun for a cathode ray tube, particularly an electron gun equipped with a low power consumption cathode as previously proposed.

First, in order to facilitate understanding of the present invention, the previously proposed cathode will be described using FIGS. 1 to 3. Figure 1 shows the entire structure of a directly heated cathode 1 with low power consumption, in which a heater wire with an extremely small heat capacity is wound into a coil in the necessary parts tightly and without contact with each other, and the coil heater is line 2
It is constructed by directly depositing a thermionic emitting material, for example, a metal oxide 3 such as (Ba, Ca, Sr) O ₃ by electrodeposition or spraying. In this case, the coil heater wire 2 is made of a material that acts as a reducing agent for the oxide 3 and has high high-temperature strength, high specific resistance, and a small coefficient of thermal expansion. For example, the coil heater wire 2 is made of tungsten (W). is used. As shown in FIGS. 2 and 3, this cathode 1 consists of a pair of Kovar pins 6a and 6b planted in an insulating support 5 made of ceramic or the like having a central opening 4.
The cathode assembly 7 is attached between the upper surfaces of the cathode assembly 7 by crimping, caulking, welding, or the like. Note that the coil heater wire 2 may be welded onto the Kovar pins 6a and 6b, and then the oxide 3 may be applied. According to this cathode 1, the conventional base metal is omitted, the heat capacity of the coil heater wire 2 itself is very small, and only the necessary portion coated with the oxide 3 is wound into a coil shape, resulting in high resistance. Therefore, the temperature required for local heating and thermionic emission is significantly lower than in the conventional case, and the power consumption of the cathode is significantly reduced. In addition, since the oxide-coated portion of the coil heater wire 2 is coiled and has a high resistance value, variations in resistance at the contact portion with the Kovar pins 6a and 6b can be ignored, and the cathode temperature becomes uniform, reducing variations in life. There are also few. Also, this cathode 1
In this case, when a current of only about 1 to 2 .mu.A is applied to the fluorescent surface of the cathode ray tube, the working area of the cathode 1 is minute, so there is no problem even with a cylindrical cathode, and the cutoff remains constant. Furthermore, the time from turning on the switch to producing a stable image is short, and an instantaneous stable image can be obtained.

Incidentally, an electron gun is usually assembled by supporting and fixing the electrode grids with bead glass in a state in which the respective electrode grids are positioned relative to each other. However, when electron guns are miniaturized, it is extremely difficult to support them on bead glass and assemble them with high precision in this way.

In view of the above points, the present invention provides an electron gun that is equipped with a cathode of low power consumption and that can be assembled with high precision even when downsized.

Hereinafter, an electron gun according to the present invention will be explained with reference to the drawings.

FIG. 4 shows an embodiment of the present invention.

In the present invention, a ceramic spacer 11 having a through hole in the center and having metallized layers 10 such as silver solder on both sides is provided. Then, the control grating _G1 and the accelerating grating _G2 constituting the electron gun are maintained at a predetermined distance _d12 so that the beam transmission holes _h2 and _h1 face each other.
They are joined together via ceramic spacers 11 having metallized layers 10 on both sides to form an integral part. Next, the cathode height H is measured and a ceramic spacer 8 is selected so that a predetermined distance d ₀₁ is maintained between the control grid _{G 1} and the cathode 1. Insert the cathode structure 7 and weld it to the control grid _G1 with the retainer 9, and then connect the electron gun 15.
complete. In addition, 12 is the lead of control grid _G1 ,
13 is the lead of acceleration grating _G2 , 14a and 14b
are a cathode lead and a heater lead connected to a pair of Kovar pins 6a and 6b, respectively.

According to this configuration, the metallized layer 10 is provided on both sides.
Since the cathode structure 7 is assembled after the control grating G ₁ and the acceleration grating G ₂ are joined together to form an integrated component using the ceramic spacer 11 with the mark, even when the electron gun is extremely miniaturized, the assembly can be performed with high precision. Can be done. That is, the distance d ₁₂ between the control grating G ₁ and the acceleration grating G ₂ is uniquely determined with high precision by the thickness of the ceramic spacer. Furthermore, since the control grating _G1 and the accelerating grating _G2 can be integrated and handled as one piece, assembly becomes highly accurate and easy. Since the cathode 1 is made of a coil heater wire coated with a thermionic emission material, the power consumption of the cathode is reduced.

In the electron gun shown in FIG. 4, the ceramic spacer 8 that defines the interval d ₀₁ must be selected for each variation in cathode height H, which is disadvantageous in terms of the number of parts and cost. Kovar pin 6 of insulating support 5
Since the coil heater wire 2 is welded on the upper surfaces of a and 6b, it is difficult to achieve positional accuracy. Since there is quite a bit of play between the control grid _G1 and the insulating support 5 of the cathode structure, no matter how accurately the coil heater wires 2 are attached to the Kovar pins 6a and 6b, the control grid
When the insulating support 5 is inserted into G ₁ , its backlash affects the positioning accuracy of the beam transmission hole h ₁ of the control grid G ₁ and the coil heater wire, that is, the cathode 1 . Cathode structure 7, ceramic spacer 8 and retainer 9
In order to incorporate this into the control grid _G1 , the depth of the control grid _G1 (length in the axial direction of the electron gun) increases, making it difficult to downsize the electron gun.

Next, an embodiment that improves this point will be shown.

FIGS. 5 to 7 show examples thereof. In this example, a through hole 21 is provided in the center as shown in FIG.
An insulating spacer 24 made of, for example, ceramic is provided, which has a convex cylindrical shape with a flange portion 22, and has a shallow stepped portion 23 on its convex surface on which the control grid _G1 is disposed. This insulating spacer 24
A metallized layer 25 is formed on the step portion 23 and the end surface 24a of the flange portion 22 opposite to the surface 22a. The end face 2 of this insulating spacer 24 is
An acceleration grating G ₂ is disposed on the 4a side, a control grating G ₁ is disposed through the step 23 of the acceleration grating G 2 so that the beam transmission holes h ₂ and h ₁ face each other through the through hole 21, and the flange portion 2
A pair of Kovar pins 6a and 6b are disposed on the surfaces of 2, and brazing is performed simultaneously in this state to attach the control grid G ₁ , acceleration grid G ₂ and Kovar pins 6a, 6b to the insulating spacer 24 as a pair. In this case, the distance d ₁₂ between the control grating G ₁ and the acceleration grating G ₂ is uniquely and accurately determined by the thickness l ₁ of the inner edge of the insulating spacer 24 . Also, Kovar pins 6a and 6
As shown in FIG. 7, the brazing position b is a position away from the center line 26 perpendicular to the axis of the insulating spacer 24, that is, the Kovar pins 6a and 6b are connected to the center line 26.
The position where the outer periphery of the Grooves 27 are formed on the side surfaces of the Kovar pins 6a and 6b, respectively, to define the distance d ₀₁ between the cathode and the control grid G ₁ when the cathode is attached, and to improve the work of attaching the cathode. Then, for the Kovar pins 6a and 6b integrated with the control grid G ₁ and the acceleration grid G ₂ ,
A cathode similar to that shown in FIG. 1, that is, a coil heater wire 2 in which heater wires with a small heat capacity are wound into a coil without closely contacting each other, is coated with a thermionic emitting substance such as (Ba, Ca, Sr) O ₃ . Metal oxides such as 3
The cathode 1 is welded to the side surface of the Kovar pin through its groove 27. When welding the cathode 1, the coil heater wire 2 coated with the oxide _{3 is aligned with the position of the beam transmission hole h1 of} the control grid G1 using a so-called misalignment microscope (device for optical centering). After aligning the two, if necessary, finely adjust the Kovar pins 6a and 6b (by slightly bending them, etc.) and join them. The spacing d ₀₁ between the control grids G ₁ for the cathode 1 is determined with high precision by the positions of the grooves 27 of the Kovar pins 6a, 6b. On the other hand, the control grid G ₁ is the sixth
As shown in the figure, it has a shallow cup shape with a notch 28 through which the coil heater wire 2 partially passes, in order to prevent the electron beam from going around (so-called stray).

According to the electron gun having such a configuration, it can be assembled without using the insulating support 5, the ceramic spacer 8, the retainer 9, etc. shown in FIG. 4, so the number of parts is small and it is very advantageous in terms of cost. At the same time, a compact and lightweight electron gun with short length is obtained. In addition, the process before welding the cathode 1, that is, the process of attaching the control grating G ₁ , the accelerating grating G ₂ and the Kovar pins 6a, 6b, only requires one brazing process, and then all is completed by simply welding the cathode 1. Work efficiency improves. Furthermore, since there is no step of assembling the cathode structure 7 into the control grid _G1 as shown in FIG. 4, there is no problem of poor accuracy due to backlash.

Furthermore, as shown in Fig. 4, Kovar pins 6a, 6b
If the coil heater wire 2 were welded to the top surface, there was a possibility that a positional deviation of 0.3 mm would occur, but in this example, the Kovar pins 6a, 6b themselves are planted with high precision, so the Kovar pins 6a, Positional accuracy is ensured simply by welding on the side surface of 6b. In addition, in the example shown in Fig. 4, the Kovar pin 6
The positional accuracy could not be guaranteed unless the steps of welding the coil heater wire 2 to the upper surfaces of a and 6b and the step of inserting the cathode structure 7 into the control grid _G1 were performed carefully twice. Since the heater wire 2 is directly welded to the beam transmission hole _h1 of the control grid _G1 while maintaining positional accuracy, the above-mentioned problem does not occur and positional accuracy is guaranteed.

FIGS. 8 to 10 show embodiments in which no Kovar pins are used. In this example, as shown in FIG. 8, there is a through hole 21 in the center, and a shallow cup-shaped control grid G ₁ similar to that shown in FIG. 6 is provided on one end surface.
A cylindrical insulating spacer 31 made of, for example, ceramic is provided, which has a stepped portion 23 into which the spacer is fitted. Step portion 23 of insulating spacer 31, one end surface 31a
A metallized layer 25 is formed on the other end surface 31b, respectively. Then, an acceleration grating _G2 is arranged on the other end surface 31b of this insulating spacer 31, and a control grating _G1 is arranged on the stepped portion 23 facing the acceleration grating G2, and are simultaneously brazed and integrated. Next, Ag paint or inorganic adhesive is directly applied to the pair of metallized layers 25 on one end surface 31a of the insulating spacer 31 while accurately aligning the cathode 1 as shown in FIG. 1 with the beam transmission hole _h1 of the control grid _G1 . Attach via. That is, Figures 9 and 10
As shown in the figure, the ends of the coil heater wires 2 are sandwiched between, for example, nickel plates 32, and bonded thereon with Ag paint or an inorganic adhesive 33. For example, a nickel plate 32 is connected to both ends of the coil heater wire 2.
The cathode lead 14a and the heater lead 14b are led out through the control grating _G1 and the acceleration grating _G2.
Leads 12 and 13 are derived from the respective leads 12 and 13. 34 is a holding lead. In this case, the spacing d ₁₂ between the control grating G ₁ and the acceleration grating G ₂ is precisely defined by the thickness l ₁ of the inner edge of the insulating spacer 31, and the spacing d ₀₁ between the control grating G ₁ and the cathode 1 is also determined by the step 23. is precisely defined by the height l ₂ . According to this configuration, compared to the case of FIG. 5, the Kovar pin is further omitted and the structure is simplified, and the positional accuracy of the cathode 1 with respect to the control grid _G1 is good, and a short, small and lightweight electron gun can be obtained. This provides the same effect as in FIG. 5.

As mentioned above, the present invention enables an electron gun equipped with a cathode with low power consumption to be configured with high accuracy and high working efficiency, and is small and lightweight, making it suitable and suitable for small cathode ray tubes. be.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a cathode applied to the present invention, FIGS. 2 and 3 are a plan view and side view showing a cathode structure for explaining the present invention, and FIG. 4 is a cross-sectional view showing an example of a cathode applied to the present invention. Sectional view showing one embodiment of the main part of the gun, No. 5
The figure is a sectional view showing another embodiment of the main part of the electron gun of the present invention, FIGS. 6 and 7 are perspective views and plan views of the main part, and FIG. 8 is a cross-sectional view of the main part of the electron gun of the present invention. A sectional view showing another embodiment, FIGS. 9 and 10 are a plan view and a sectional view of the main parts thereof. 1 is a cathode, 2 is a coil heater wire, 3 is a thermionic emitting material, G ₁ is a control grid, G ₂ is an acceleration grid, 24,
31 is an insulating spacer.

Claims (1)

[Claims] 1 The control grating and the accelerating grating are integrated with an insulating spacer interposed through a metal layer in the peripheral area excluding the beam transmission area of the opposing surfaces, and the cathode is formed by coating a coil heater wire with a thermionic emissive material. An electron gun placed facing a through hole.