JPS60207234A - Cathode ray tube - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a flat shadow polar ray tube.

Many proposals have been made for the design of flat cathode ray tubes.
Some of them are more practical than others. These known proposals can generally be divided into three categories. The first is a control (or reflection) between a transparent electrode supported by a fluorescent screen and a rear electrode remote from this electrode.
An electric field is created and the electron beam is directed along a trajectory that makes an acute angle with the fluorescent screen.

The electron beam follows a parabolic trajectory under the influence of a control electric field and impinges on the fluorescent screen at a substantially constant angle. The range of the beam is determined by the strength of the control field, which can be varied by changing the voltage applied to the rear electrode. A cathode ray tube of this type is disclosed in British Patent Specification No. 865,667. One drawback of this proposed tube is that the larger the fluorescent screen size, the greater the spacing between the fluorescent screen and the rear electrode. Another drawback is that the electron beam has its final energy within the control field, e.g.
It enters at Ke V and requires a large control field that must be varied at frame or line frequency.

Second, the electron beam is placed in an electrostatic field between two spaced electrodes, one supported by a fluorescent screen (if present, mounted on the back wall of the vessel) and the other mounted on a transparent faceplate. This is the type that can be entered from the side. The electron beam is introduced into an electrostatic field by a pair of deflection plates, and the voltage applied to these deflection plates is applied every frame period (
frame rate). This operation may be thought of as the oblique (Iobbing) of the electron beam into the electrostatic field. Examples of this type of cathode rays are GB 592,571, GB 2,071,402 and GB W.
It is disclosed in No. 083100406. These display tubes have the same drawbacks as the first type of cathode ray tube mentioned above.

A third type is one in which the electron beam is produced by an electron gun mounted behind the screen surface with an axis parallel to the screen surface. The generated electron beam is subjected to line scanning after exiting the electron gun. The electron beam is then deflected towards a fluorescent screen.
Reflected 180°. A display tube of this type is disclosed in British Patent Specification No. 739,496. A variant of this type of cathode ray tube is known from GB 2101396A in which the electron multiplier is provided adjacent to and away from the fluorescent screen. This configuration has the advantage that scanning and deflection of the electron beam can be decoupled from the generation of light output from the cathode ray tube.

In both of these known proposals, the scanning of the electron beam when it leaves the electron gun is carried out electrostatically using mutually inclined deflection plates. Furthermore, experiments have shown that there is a limit to the length of a line that can be scanned due to deflection defocus caused by the scanning system, resulting in poor peripheral resolution. This poor edge resolution, relative to the surface area, is
This cannot be overlooked in data graphics or instrument cathode rays, which often have aspect ratios different from the :3 aspect ratio. Deflection defocus is due to the maximum scan angle not being large enough to keep the beam spot focused over the desired viewing area; the scan angle is varied depending on the distribution of the electron beam from the electron gun. Must be.

SUMMARY OF THE INVENTION An object of the present invention is to obtain a flat cathode ray tube in which the thickness of the container is substantially independent of the screen size and the maximum scanning angle can obtain a line length that is larger than the height of the frame. It is something to do.

According to the present invention, a flat cathode ray tube includes a container including a flat face plate and a rear wall spaced apart from the face plate, a fluorescent screen inside the face plate, and a fluorescent screen arranged on the inside of the face plate. an electron multiplier disposed parallel to and spaced apart from said electron multiplier; an array of deflection electrodes disposed adjacent to said rear wall parallel to and coextensive with said electron multiplier; an electron beam generator disposed on the side of the space formed between the multiplier and the deflection electrode array, and in use guiding an electron beam into the space in a direction parallel to the deflection electrode array; a magnetic device disposed along the path of movement of the beam and deflecting the electron beam to the side of the path of movement of the electron beam from the electron gun; and connecting the electrodes of the deflection electrode array to a power source of a deflection voltage; The electron beam is deflected in the direction of the electron multiplier according to the deflection voltage.

Compared to the above-mentioned proposals for cathode ray tubes, the cathode ray tube of the present invention has the same thickness for one range screen size and also has a larger maximum running angle than that obtained with electrostatic beam deflection; Therefore, the shape of the screen can be changed more widely without the problem of deterioration of resolution due to deflection and defocus. Furthermore, by using electron multipliers, particularly micro-channel plate electron multipliers, high-resolution images can be obtained on fluorescent screens, and addressing of the electron multipliers can also be achieved using low-voltage, low-current electron multipliers. It can be done by beam.

The invention will now be explained by way of example with reference to the accompanying drawings.

The cathode ray tube 10 is primarily comprised of three parts: a generally box-shaped display section 12, a cylindrical neck 14, and a flared section, hereinafter referred to as fan 16, connecting this neck to an end wall 18 of said display section 12. It has a container.

The display portion 12 includes a generally flat optically transparent faceplate 20, a generally flat rear wall 22 (FIG. 3) parallel to the faceplate 2°, and a rear wall 22 parallel to the faceplate 20 (FIG. 3). It has an end wall 18 that interconnects the walls 22.

A fluorescent screen 24 is provided on the inner surface of the face plate 20. A micro-channel plate electron multiplier 26 is mounted within display portion 12 parallel to and coextensive with faceplate 20 . Deflection electrode array 28 is provided on rear wall 22 (if this rear wall is an insulating material) or on an insulating substrate supported by the rear wall. The electrode array 28 includes a plurality of separate generally elongated electrodes 30.
These electrodes may be straight or curved. Connections to electrodes 30, electron multiplier 26 and transparent electrodes on faceplate 20 are made via connectors 32 on end wall 18.
．． It is taken out from the container via 34.

An electron gun 36 is mounted within the class 14 and arranged so that its longitudinal axis coincides with a plane of symmetry extending across the thickness of the container. Fan 16 has generally flat upper and lower surfaces, with the lower surface being flush with rear wall 22.

The cross-sectional height of the fan 16 is smaller than that of the display portion 12. Therefore, the electron beam 38 is placed in the electron gun 36 on a path of motion closer to the deflection electrode array 28 than to the electron multiplier 26.
released. Electron multiplier 26 and deflection electrode array 28
40G of space between the electrode 30 and the electron multiplier 26
Electron beams under the influence of the electric field generated during
is large enough to deflect the electron beam from a path of motion parallel to the deflection electrode array 28 so that it approaches the electron multiplier at a substantially constant angle. In this case, the space 4 mentioned above
The depth of zero is the same regardless of the emission length of the electron beam 38 from the electron gun 36.

A scanning coil 42 is provided at the transition between the outside neck of the container and the fan. For example, 125 mm as shown in Figure 2.
For a square display area of
Therefore, when using the cathode ray tube 10, the deflection angle must vary from 0° to 90°, while at the same time the beam spot size at the input of the electron multiplier 26 must be constant. Rather than using electromagnetic scanning, focusing modulation is applied to the electron spot.
It has been found that this is possible by applying modulation and keystone correction to the scan line.

In operation, a low voltage, low current electron beam 38 is generated by an electron gun 36 having a final anode voltage of +400V relative to the cathode voltage (eg, 0.times.). This electron beam 38 is line-scanned by a suitable current flowing through a scanning coil 42.

The input side of the electron multiplier 26 is connected to the final anode voltage of the electron gun (
+400V), and the voltage applied to the output side is IKV higher. Ultimately, the voltage applied to the electrons on the fluorescent screen is 10 KV higher than the voltage applied to the output of electron multiplier 2B. Suitably, the electrodes of the electrode array 28 are at 0.times.0.degree. so that the electron beam 38 enters the reflected electric field and is deflected toward the near green of the fluorescent screen. The voltage on the electrode 30 is applied to the electron gun so as to create an electric field-free space through which the electron beam 38 passes unhindered until it reaches a reflected electric field that redirects the electron beam to the electron multiplier. Starting from the electrode closest to , the voltage is increased approximately linearly to +400V. To obtain a roughly linear scan, if the voltage at one electrode 30 is half the final voltage (in this case +400 cm in the 1M example), the next electrode 30 in the electrode array 28 will be at the same rate. and so on.

Obviously, if one wants to deflect the electron beam in the opposite direction, all but the two electrodes 30 furthest from the electron gun 36, which are at OV and +200V respectively, are first at +400V and then the electrodes gradually decrease the voltage to Ov one after another in the reverse order.

As a modification of the illustrated cathode ray tube device, the externally disposed scanning coil 42 may be replaced by internally disposed pole pieces and/or deflection coils.

The number of electrodes 30 in array 28 is a compromise between the allowable thickness of the tube and the number of frame scan voltage generators required. 125
Taking a screen size of +nm x 125ma+ as an example, if 21 electrodes are used, the tube thickness will be 25I.
If the number of electrodes were instead on the order of 7, the thickness would be on the order of 40 m.

If it is desired to create a color display for data graphics or instrumentation purposes, the fluorescent screen 24 can be
enetron) Wi can be made from optical material.

Different colors are created by keeping the voltage at the output side of the electron multiplier 2G constant and changing the voltage applied to the transparent electrode on the face plate 20 appropriately.

[Brief Description of the Drawings] Fig. 1 is a partially cutaway perspective view of the cathode ray tube of the present invention, Fig. 2 is a plan view of the cathode ray tube of Fig. 1, and Fig. 3 is a longitudinal axis of the cathode ray tube of Fig. 1. A diagrammatic cross-sectional view along . 10... Container 12-... Box-shaped display portion 14... Neck 16... Fan 18... End wall 20... Face plate 22...
- Rear wall 24... Fluorescent screen 26... Micro-channel plate electron multiplier 28... Electrode array 30
...Electrode 32, 34...Connector 36...Electron gun 38...Electron beam 40...Space 42...
・Scanning coil

Claims (1)

[Claims] 1. A container including a flat face plate and a rear wall spaced apart from the face plate, a fluorescent screen inside the face plate, and a fluorescent screen parallel to and extending from the face plate. a remotely located electron multiplier;
a deflection electrode array disposed adjacent to the rear wall, parallel to and coextensive with the electron multiplier, and on the sides of the space formed between the electron multiplier and the deflection electrode array; an electron beam generating device disposed along the movement path of the electron beam and guiding the electron beam into the space in a direction parallel to the deflection electrode array when in use; A magnetic device for deflecting the electron beam to the side of the movement path and the electrodes of the deflection electrode array are connected to a power source for deflection voltage, and the electron beam is directed in the direction of the electron multiplier in accordance with the deflection voltage. A cathode ray tube characterized in that it has a deflecting device. 2. The cathode ray tube according to claim 1, wherein the magnetic device has a coil attached to the outside of the container. 3. The magnetic device is disposed within the container.
Cathode ray tube as described in section.