JPS593818B2 - Cathode ray tube electrode support device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cathode ray tube, and more particularly to an apparatus for supporting each electrode of an electron gun of a cathode ray tube.

Portable electronic instruments such as portable oscilloscopes and spectrum analyzers are often subjected to severe handling and must be designed to withstand considerable shock and vibration.

Generally, the most severe impact is when these devices are dropped onto a hard surface.

This can occur by accident or negligence, or during normal transportation of the equipment.

In the case of portable equipment that includes a cathode ray tube (CRT), special care must be taken to prevent the CRT from being damaged by such shocks.

Breakage of the CRT's glass or ceramic envelope may be avoided by proper support and mounting according to known techniques.

However, the internal structure of a CRT is susceptible to damage, which is a factor that limits the vibration and shock specifications of the device.

The internal structure of conventional oscilloscopes and other electrostatic deflection type CRTs includes an electron gun, means for deflecting the electron beam generated by the electron gun, and a display screen coated with a phosphor.

This screen is generally solid and can withstand large impacts well, but electron guns and deflection bodies are a different matter.

In addition to the cathode, the electron gun assembly includes additional electrodes for controlling, focusing and accelerating the electron beam emitted from the cathode.

Each of these electrodes must be positioned and fixed with great precision and is generally supported by a common set of glass or ceramic rods.

The beam deflection assembly typically uses two pairs of deflection plates and is generally integrally formed and assembled onto the same support rod as the electron gun.

This is for manufacturing convenience, but also to maintain the deflection plate in an accurate positional relationship with the electron gun.

Similarly, the deflection electrodes of CRTs for special purposes may be directly supported on the inner wall of the neck portion of the tube.

The electron gun and deflection plate assembly are coaxially supported within the neck of the CRT by suitable means, generally a plurality of metal pieces called resilient support devices (snubber).

In addition to supporting and aligning the electron gun assembly, this support device has the function of absorbing shocks and vibrations applied to the tube.

Conventional elastic support devices are not sufficient for large impacts (for example, 40 G).

In such a case, of course, it must be ensured that there is no excessive movement of the electron gun during the impact period.

Without it, the acid will deform the valleys and conductors of the electron gun assembly, and in extreme cases, it will damage the base of the tube or the tube itself.

Instruments such as oscilloscopes perform quantitative interception based on the deflection of the CRT's electron beam.

To compensate for this deflection, a precise scale is provided on the CRT's display screen, and the scale in modern CRTs is generally located on the inner surface of the faceplate to eliminate parallax errors.

Accuracy and reproducibility of measurements requires that the axial position of the electron gun assembly remain substantially unchanged even after shocks within the failure limits are applied.

In the case of conventionally designed support devices, it has been found that when large impacts are applied, the permanent or semi-permanent displacement of this electron gun exceeds the permissible value.

Accordingly, it is an object of the present invention to provide an electrode support device for a CRT with improved design and operating characteristics.

A further particular object of the invention is to provide, especially at high impact levels,
An object of the present invention is to provide an improved elastic support member that supports an electron gun assembly of a CRT more effectively than conventional devices.

Yet another object of the present invention is to provide an elastic support member that not only protects the electron gun assembly at high impact levels, but also sufficiently prevents axial displacement of the electron gun assembly as a result of the impact. .

Another object of the invention is to provide a support device whose modulus of elasticity can be changed after applying a predetermined amount of compression.

These and other objects and advantages of the invention will be understood from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate preferred embodiments of the invention.

Referring first to the accompanying drawings, FIG. 1, an example of a conventional support device 10 is shown.

As is clear from the figure, there are three supporting members 10, typically four, arranged at equal intervals from one end around the axis of the CRT electron gun.
This is one of the same elastic support members.

Some CRTs typically include a set of support members at the front (screen) end of the pentagonal gun assembly.

Others use two or three sets of support members depending on the length and mass of the electron gun assembly and the degree of impact that requires protection.

The support member 10 is an elongated flat elastic body, one end of which is bent inward (downward in the figure) and fixed by welding to a tab 14 of an electron gun (not shown) supported by the support member.

The other end 16 is bent to form a curved portion 18 that abuts the inner wall 20 of the cylindrical glass neck 22 of the CRT.

As is clear from the figure, the support member 10 has a substantially straight beam shape and contacts the inner wall 20 at an axial position considerably distant from the point of contact with the electron gun assembly.

When the electron gun is accelerated from its normal neck center position toward the inner wall 20 in the radial direction by the impact, the support member 10 is bent inward (downward) as shown by the broken line in the figure.

The curved portion 18 is then forced to slide along the inner wall 20 of the neck 22 to absorb this movement, and the support member also absorbs a large amount of energy due to the large friction and pressure bond between the metal and glass surfaces.

After this supporting member slides with friction along the inner wall due to the impact force, even if it attempts to return to its initial state, it cannot return due to the excessive friction between the supporting member and the glass surface, and the electron gun structure is semi-permanently damaged. A large displacement occurs.

Figure 2 shows this effect. The electron gun of an oscilloscope CRT is usually targeted at the center of the display screen.

Therefore, when no signal voltage is applied between the deflection plates, a bright spot 26 (in this case) is produced at the intersection of the center scale lines Xc and Yc on the face 7''L/-t 24.

However, after applying the above-mentioned impact (within the destructive limit), the bright spot 26 will be damaged by the face plate 24 depending on the magnitude of the impact.
The amount of movement becomes a semi-permanent stable state position 26a.

Next, if a shock of the same magnitude is applied at an angle of 90 degrees with respect to the first shock, the bright spot 26 will semi-permanently move to the stable state position 26b in the lateral direction.

The term "semi-permanent" here means that the electron gun remains in a certain position during the non-deflection signal unless the electron gun moves again with the next shock.

Of course, such [trace movement 1] is not preferable for precision measuring instruments.

In conventional electrode support devices, such as that shown in FIG. 1, impact resistance can be increased by using heavier materials or by increasing elasticity.

However, this increases trace movement as the amount of friction between the neck glass and the support member increases.

Additionally, the amount of impact energy directly transferred to the electron gun assembly is a function of the hardness of the support device.

Therefore, if an excessively hard elastic support member is used, even if it is possible to prevent the electron gun assembly itself from impacting the inner wall of the CRT tube, the electron gun assembly itself will be damaged if the impact is large.

Another conventional support member configuration is shown at 30 in FIG.

This support member 30 is similar to the support member 10 described above except that it has an axially extending intermediate portion 32 that is offset from the electron gun attachment point.

Although this configuration provides a compact structure, various drawbacks of the straight beam fixed modulus design shown in FIG. 1 remain unresolved.

Embodiments of good electron gun support devices and support member designs that are currently achievable according to the present invention are shown in FIGS. 4-7.

First, please refer to FIGS. 4 and 5. A CRT 40, such as an oscilloscope, has an evacuated tube 42 of conventional design.

The interior of the bulb 42 includes a cylindrical glass neck 44 suitably sealed at the small end of a ceramic funnel 46.

A glass face plate 48 supporting a phosphor-covered target screen (not shown) is attached to the funnel 4.
6 is sealed at the other end.

Mounted within the neck 44 is an electron gun 50 having a cathode and grid assembly 52, a first anode 54, a focusing electrode 56, and a second anode 58.

The electron gun 50 is disposed coaxially within the neck portion 44 and emits an electron beam 60, which is directed to the horizontal deflection plate 62.
and a vertical deflection plate 64 toward the center of the fluorescent screen.

Conventionally, each electrode and deflection plate is supported by pins or tabs embedded in four parallel glass rods 66.

This allows formation of an integrally formed electron gun/' deflection plate assembly 68 that is precisely aligned with each other.

The electron gun assembly 68 is held within the CRT neck portion 4 mainly by twelve substantially U-shaped support members 70 with expanded open ends.

(Additional support is provided after the electron gun assembly 68, i.e. at the cathode end, using four unused leads from the base of the CRT tube, each lead being
It is welded to a metal tab provided on a nearby glass rod 66 as shown.

) The support members 70 are divided into eight front sets 72 and four rear sets 7402.

The support members of rear set 74 are secured to mounting tabs 76 on first anode 54, preferably by welding, as shown in FIG.

As shown in the figure, there are 90
The CRT neck section 4 is attached at intervals of
Press the inner wall of No.4.

The support members of the front set 72 are secured to mounting tabs 80 attached to the insulation plate provided between the deflection plates 62, 64.

These eight support members are arranged symmetrically around the central axis of the electron gun in four sets of two, and the springs of each set are opened at an angle of about 30 degrees.

This reduces the rotational vibration of the electron gun assembly 68 at the time of impact, and improves the impact characteristics in the axial direction (off-angle).

Reference is now made to FIGS. 6 and 7.

Each elastic support member 70 according to the invention is attached to a leg 82.
It has one end thereof, that is, near the bottom in the figure, and is attached to the attachment tab 76 or 80 of the electron gun assembly 68.

The other (upper) end of the support member 70 has a bidirectionally curved contact point or head 84 and abuts against the inner wall 78 of the CRT neck 44 .

The connecting portions or legs 82 and head 84 are bent to form an inner portion 88 extending outwardly (upward in the figure) from the electron gun assembly 68 at an angle φ relative to the longitudinal axis of the assembly.
It has a folded intermediate section 86 including an outer section 90 that extends in the other direction and further outwardly at an angle .theta.

For example, a suitable support member TO for a spectrum analyzer CRT is made of Inconel X-750, a hardened nickel chrome alloy, about 6 mm wide and about 0.6 mm thick.

(In applications where the sweep speed is slow, such as a spectrum analyzer or a low frequency oscilloscope, it is preferable that the overall length of the CRT is short, especially if it is portable.

Therefore, it is necessary to increase the amount of deflection, that is, the deflection angle, so it should be noted that the size and weight of the electron gun will increase significantly.

) In the unloaded state, the angle φ of the inner portion 88 is approximately 20° with respect to the electron gun axis of the CRT.

Inner and outer parts 8 connected by a curved part with a radius of approximately 2.5 mm
The internal angle θ between 8.90 and 90 is approximately 27°.

The contact portion 84 is a curved surface with a radius of approximately 6 mm in the axial direction and approximately 2.5 mm in the perpendicular direction.

The total length of the elastic support member 70, excluding the attachment portion 82, is approximately 15 mm.

FIG. 8a shows the support member 7 in the state in which it is installed on the CRT 40.
Indicates 0.

The contact portion 84 and the contact portion of the inner wall 78 of the neck portion 44 are approximately directly above the portion 82 where the support member 70 is attached.

When an impact is applied to the CRT 40 and the electron gun assembly 68 is accelerated from its resting state outward (upward in the figure) from the neck center position toward the inner wall 78, the outer portion 90 of the support member center position 86 first It is bent inward (downward) as shown in the figure.

However, the inner part 88 does not do this, and when a force is applied to the inner part 88 and the outer part 90, which have relatively large radii, they tend to bend outward (upward).

When the electron gun assembly 68 moves further outward (FIG. 8c),
The outer portion 90 bends further inwardly and the central portion 8 of the support member 70
6 comes into contact with the inner neck wall 78 at point 92.

At this point, the elastic modulus of the support member 700 increases because the practical spring length becomes shorter.

Subsequent relative compression between the CRT electron gun assembly and the neck tube wall 78 is achieved by inward bending of the inner portion 88 of the support member 70.

A particularly remarkable effect of the electron gun support device according to the present invention described above is that when the support member 70 is bent, the contact portion 84 hardly slides on the inner wall of the neck and remains at one point.

As can be seen from FIGS. 8a-C, since the contact portion 84 is located almost directly above the portion 82 when the support member 70 is attached, it will slide along the inner wall of the glass neck portion even if the support member 70 is compressed. It simply rotates along the curve on the inner wall.

Therefore, when the impact load is removed, the contact portion 84 easily returns to its initial state, returning the electron gun assembly 68 to the center position again.

Since there is no frictional resistance of the conventional support member, the electron gun assembly of the present invention returns to the axial center position of the CRT neck before the impact is applied, and no trace movement occurs.

This also applies when a large impact is applied.

An additional advantage of the present invention is that the support member can be laterally bent, as indicated by reference numeral 90A in FIG.

Therefore, for example, a support member (
For example, the support members at the 3 o'clock and 9 o'clock positions of the rear 74 in FIG. 5) warp in response to a vertical impact.

Conventional support devices, such as those shown in FIGS. 1 and 3, are not capable of flexing in this manner, allowing the support member to slide within the tube wall.

This caused the problem of trace movement mentioned above.

As is clear from the above description, in the cathode ray tube electrode support device according to the present invention, one end of the U-shaped elastic support member with a wide open end is bent and fixed to the electron gun structure, and the other end has a curved head. At the same time, by positioning the center of the contact part directly above the bent part of the elastic support member, the head will slide on the inner wall of the glass neck even if the support member is compressed by an impact. Since it only rotates without moving, it can easily return to its initial position once the impact is gone.

Therefore, semi-permanent trace movement does not occur.

An improved support member and electron gun support apparatus that achieves the various objects mentioned above have been described based on preferred embodiments of the present invention.

In one embodiment shown in FIGS. 4 and 5, the standard 11
Experimental equipment has confirmed that it can withstand large impacts of 100G or more during m5.

Of course, no electrical or mechanical defects occurred.

Although the above description has been made regarding only the preferred embodiments of the present invention, those skilled in the art will understand that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, it goes without saying that the technical scope of the present invention includes these modifications.

[Brief explanation of drawings]

Fig. 1 is a side view of a conventional flat elastic support member, Fig. 2 is an enlarged front view showing the central part of an oscilloscope face plate having an internal scale, and Fig. 3 is a side view of another conventional elastic support member. , FIG. 4 is a side view of the oscilloscope CRT with a portion cut away to show the electron gun and electron gun support device.
5 is a cross-sectional view taken along the line V-■ in FIG. 4, FIG. 6 is an enlarged side view of the elastic support member according to the present invention, and FIG. 7 is a view of the support member in FIG. 6 viewed from the left side. Figures 8a-c are side views showing the relationship between the elastic support member and the CRT tube wall at different compression levels. In the figure, 40 is a cathode ray tube (CRT), 68 is an electron gun assembly, and 7
0 is an elastic support member, 44 is a cylindrical neck portion 84 is a head, 8
6 is the middle part, and 88 is the inner part.

Claims (1)

[Claims] 1. In a cathode ray tube electrode support device having a plurality of elastic support members for supporting an electron gun assembly within the neck of a tube bulb of the cathode ray tube, each of the elastic support members has a U shape with an enlarged open end.
One of the open ends is bent and fixed to the electron gun structure, and the other has a curved head that contacts the inner wall of the tube. An electrode support device for a cathode ray tube, wherein the midpoint is located on a line that passes through the bent portion of the elastic support member and is perpendicular to the tube axis of the cathode ray tube.