JPH0422535Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a fluorescent display tube in which thermoelectrons emitted from a cathode filament collide with a phosphor of a display anode to cause it to emit light.

[Technical background of the invention and its problems]

A conventional fluorescent display tube of this type is shown in FIG. 4, and will be described below.

1 is a face plate, 2 is a transparent conductive film, and 3 is a filament forming a cathode for emitting thermoelectrons. Usually, a tungsten wire coated with oxide is used.

Reference numeral 4 denotes a grid, which is usually a rectangular frame with electrodes of the same shape welded to it, and a protrusion of the frame is led out to form a terminal 8 to which a voltage is applied.

Reference numeral 5 denotes an anode segment, in which an electrode is coated on an insulating layer on a substrate glass 6, and a phosphor is further coated on the electrode, and the electrode is exposed to the outside through an anode wiring pattern 7. It is led to the terminal 8 and a voltage is applied thereto.

To explain the operation of this display fluorescent tube in the case of a static drive, thermionic electrons emitted from the filament 3 are accelerated or controlled by the grid 4 and uniformly diffused.

The thermoelectrons uniformly diffused by the grid 4 are
collides with the phosphor that is the selected anode electrode,
This produces a luminescent phenomenon.

However, since the grid 4 is formed into a mesh having the same shape and the same roughness, the acceleration or control of the thermoelectrons is performed uniformly, so the amount of thermoelectrons reaching the anode electrode is also made uniform.
The luminescence phenomenon of the phosphor also has the same brightness.

Therefore, it is not possible to create a sense of perspective by partially changing the luminance of the phosphor, and the conventional method for creating such a partial change in luminance is to slit the light emitting part. The brightness was either divided into two parts and controlled by controlling the anode voltage, or the brightness was changed by adjusting the density of an external filter.

However, control using an anode voltage has the disadvantage that the external circuit is complicated and the anode wiring pattern is also complicated because many terminals are provided and the voltage applied to each is changed.

Further, when an external filter is used, there is a drawback that when the light is turned off, the shading of the filter is visible to the eye, resulting in an unnatural appearance.

[Purpose of invention]

In order to eliminate the above-mentioned drawbacks of the conventional fluorescent display tube, the present invention gradually changes the roughness of the mesh of the grid to partially change the luminance of the phosphor, thereby improving perspective. The purpose of this invention is to obtain a fluorescent display tube that can display the following.

[Example of idea]

An example of the present invention will be described below, in which a sense of perspective is created by making facing triangular figures as shown in Figure 3 darker in the center and brighter towards the outside. , FIGS. 1 and 2 will be explained.

The structure of the electrodes except for the grid and the fact that thermionic electrons emitted from the filament of the cathode reach the anode electrode and cause the phosphor to emit light are the same as in the prior art, so a description thereof will be omitted.

In the embodiment described above, the grid 11 is
As shown in the figure, the mesh is fine in the center and coarser towards the outside, but it is exaggerated in Figure 1 for the sake of explanation; in reality, it is a finer mesh. Various shapes are used, such as a tortoiseshell shape.

The thermoelectrons emitted from the filament are accelerated or controlled by the grid 11 and collide with the phosphor of the anode electrode, causing it to emit light.
Grid 11 in the fine mesh part in the center
The number of thermoelectrons passing through and reaching the anode electrode decreases, resulting in lower brightness.

As the mesh is rougher, the number of thermoelectrons that pass through it and reach the anode electrode increases as you move toward the outside, and the brightness gradually increases, with the outermost brightness being the brightest.

Therefore, display segment 1 with facing triangles
0 is brightest on the outside and becomes darker toward the center, expressing a sense of perspective.

In the above embodiment, the brightness is changed in the horizontal direction, but depending on the design, the shape of the display segment 10, etc., the brightness may be changed vertically or diagonally as well. The brightness can be freely changed by changing the direction.

[Effect of the invention] As mentioned above, the present invention allows the brightness of the display segment to be partially changed by gradually changing the mesh coarseness of the mesh grid.
Perspective and brightness can be expressed depending on the design, the shape of the display segment, etc.

Therefore, there is no need for a complicated fluorescent display tube configuration in which the anode electrode is divided into slits and the applied voltage is changed as in the conventional case, or for an external circuit that generates a large number of applied voltages.

Furthermore, unlike the case where the shading of an external filter is used, the shading of the filter does not appear unnatural when the light is turned off.

Incidentally, since mesh grids are usually made by etching, even coarse grid meshes such as those of the present invention can be manufactured in the same manner as in the past, and can be easily manufactured without increasing costs.

[Brief explanation of the drawing]

FIG. 1 is a front view showing the relationship between a display segment and a grid mesh according to an embodiment of the present invention, FIG. 2 is a side view thereof, and FIG. 3 is a front view of the display segment.
FIG. 4 is a partially cutaway exploded perspective view of a conventional fluorescent display tube. 10...display segment, 11...grid.

Claims (1)

[Scope of utility model registration request] A display anode portion that brightly displays the mesh size of a mesh grid located between a cathode filament in a vacuum container in which an anode substrate glass and a face plate are sealed at the periphery and a display anode coated with a phosphor. A fluorescent display tube characterized by a gradual change in the display area, with coarse changes in the areas to be displayed and fine changes in the areas to be displayed in the dark.