JPH037878Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a fluorescent display tube, and in particular, in a vacuum-tight container, electrons emitted from a cathode are accelerated by a mesh-like control grid and made to collide with an anode having a phosphor layer. This invention relates to the structure of a control grid of a fluorescent display tube that displays characters, numbers, symbols, etc.

Conventionally, in the control grid of a fluorescent display tube, as shown in FIGS. 1 and 2, a uniform step is formed between the mesh-like control grid surface 4 and the control grid lead surface which is drawn out of the vacuum container by molding. . When this control grid is sandwiched and sealed between the vacuum container 7 and the anode substrate 1, the distance between the anode substrate 1 and the vacuum container 7 becomes wider due to the anode leads 5 with bent tips located between the control grid leads. The anode lead 5a is sealed in a floating state from the anode substrate. Since the control grid leads 41 to 43 are connected to the same tie bar 9 as the anode lead, they are similarly sealed in a floating state from the anode substrate. In particular, since the central control grid lead 42 has anode leads arranged on both sides, the distance from the anode substrate is larger than that of the control grid leads 41 and 43 on both sides, and the mesh-like control grid surface and the anode board are parallel. do not become. Usually, the cathode is installed parallel to the anode substrate, so the distance between the mesh-like control grid surface and the cathode is not constant.

The brightness of a fluorescent display tube is determined primarily by the distance between the cathode and the control grid plane. The brightness is high where the distance between the cathode and the control grating surface is short, and the brightness is low where the distance is long, so it has been impossible to obtain uniform brightness over the entire control grating surface.

In order to solve the above-mentioned drawbacks, this invention aims to obtain a fluorescent display tube in which the distance between the cathode and the control grid surface is constant by changing the molding steps of the mesh-like control grid surface and the control grid lead surface. shall be.

The control grid of the fluorescent display tube according to this invention will be explained below with reference to the drawings.

FIG. 3 shows an embodiment of a control grid of a fluorescent display tube according to this invention. Figures 4a and 4b show the central control grid lead 42 and the control grid leads 41 and 43 at both ends.
The sealing cross-sectional views are shown in each case.

The molded heights of the molded parts A and C of the control grid leads 41 and 43 at both ends are equal, and the molded height of the molded part B of the central control grid lead 42 is made lower than the molded height of the molded parts A and C at both ends. The difference in molding height between both ends and the center is determined by the control grid leads 41 at both ends, which are generated when the control grid is sandwiched and sealed between the vacuum container 7 and the anode substrate 1.
43 and the distance between the central control grid lead 42 and the anode substrate 1, the control grid surface and the anode substrate become parallel, and it is possible to keep the distance d between the cathode 6 and the control grid surface 4 constant. .

Therefore, a fluorescent display tube having uniform brightness over the entire control grating surface can be obtained.

In this embodiment, the case where forming occurs on the central control grid lead has been described, but if the control height of both side control grid leads is low, the case where the forming height of the central control grid lead is zero is also included.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a fluorescent display tube, FIG. 2 is a perspective view of a conventional control grid, and FIG. 3 is a perspective view of an embodiment of the control grid according to the invention. FIGS. 4a and 4b are cross-sectional views showing the case where the control grid of FIG. 3 is used for sealing. DESCRIPTION OF SYMBOLS 1... Anode substrate, 2... Conductor layer, 3... Fluorescent layer, 4... Control grid, 5... Anode lead, 6...
Cathode, 7...vacuum container.

Claims (1)

[Scope of utility model registration request] Equipped with multiple control grid leads on the same control grid,
and the fluorescent display tube is configured such that the control grid lead is drawn out from the sealing portion between the vacuum container and the anode substrate in parallel with the anode lead having a bent tip, and the control grid lead is disposed between the anode leads. The molded height of the connecting portion between the grating lead and the mesh-like control grating surface is lower than the molding height of the connecting portion between the grating lead and the mesh-like control grating surface that are not disposed between the anode leads. Fluorescent display tube.