JPS618827A - Reverse view type fluorescent display tube - Google Patents

Abstract

PURPOSE:To improve workability and reduce the disconnection failure of a filament by providing a cold cathode, filament for stimulating activation, and self- radiation holding electrode and heating the cold cathode only at the beginning of the activation. CONSTITUTION:When a filament 5 for stimulating activation is heated by the voltage V1 of approximately 10 volts, thermoelectrons are emitted. These thermoelectrons strike against a cold cathode 3 and secondary electrons are emitted from the MgO layer of the cold cathode 3 and then an electron that causes an electronic avalanche is generated. In this case, the MgO layer is charged positively. Assuming that the positive potential V2 of approximately 200 volts is applied to an SSE holding electrode 6 for the cold cathode 3, the cold cathode 3 continuously emits the electrons and this state is continued even if the feeding of the filament 5 for stimulating the activation is disconnected. As a result, the collector current continues flowing into the SSE holding electrode 6 and the electrode 6 is set to the keep alive state. The heating of the filament 5 for stimulating the activation that applies electronic bombardment to the cold cathode 3 requires less than 1sec and a circuit to which the voltage V1 is connected is set to OFF when approximately 1sec elapses after the voltage is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a reverse-view fluorescent display tube in which a display is observed from the anode side.

[Prior art]

In conventional reverse-pew type fluorescent display tubes, a transparent anode with a desired pattern is formed on a transparent glass substrate that also serves as a vacuum outer container, and a phosphor is coated on this anode to capture the electrons emitted from the cathode. The flow was controlled by a control grid. In such a fluorescent display tube, the number, character, and nine figures displayed by the luminescence of the phosphor were observed through a transparent glass plate on the anode side.

However, such conventional fluorescent display tubes had the following drawbacks because the cathode was coated with an oxide consisting of a tungsten core wire K (Ba, Sr, Ca)0. was.

(a) During assembly, the applied oxide easily peeled off during the process of stretching the filament, resulting in poor workability.

(b) Because the filament was continuously heated, wire breakage was likely to occur.

(C) The oxide applied to the filament was deposited on the phosphor screen, reducing the brightness.

(d) Since it was necessary to constantly heat the filament with electricity during operation, most of the power consumption of the entire tube was required to heat the filament.

(e) In a fluorescent display tube with a large number of filaments, the temperature of the tube rises due to the heat radiated from the filaments, causing a phenomenon called temperature quenching of the phosphor, resulting in a decrease in brightness.

[Object and structure of the invention]

Therefore, an object of the present invention is to provide a reverse pew type fluorescent display tube that solves all of these drawbacks at once.

In order to achieve this purpose, this invention uses a cold cathode,
It is equipped with a filament for activation stimulation, a self-emission sustaining electrode, and a cold cathode that is heated only at the beginning of activation.

Hereinafter, the present invention will be described in detail using drawings showing embodiments.

〔Example〕

The figure is a sectional view showing an embodiment of the present invention.

In the figure, 1 is a reverse view type fluorescent display tube, 2 is a Ni-based metal plate, 3 is a cold cathode, 4 is a spacer glass, and 5
6 is a starting stimulation filament whose tungsten core wire is coated with (Ba, Sr, Ca)O oxide like the filament of a normal fluorescent display tube, and 6 is a 5SE (Self-5ustained) which acts as a self-emission sustaining electrode.
Emission) A sustaining electrode, 7 a control grid, 8 an anode coated with phosphor, 9 a transparent glass substrate, and the Ni-based metal plate 2 and cold cathode 3 constitute a cathode section. The 5EIZE sustain electrode 6 is formed by etching a metal plate, such as stainless steel, into a mesh shape, and has a structure that allows electrons generated from the cold cathode 3 to pass therethrough. In addition, the cold cathode 3 is N
i The base metal plate 2 is coated with MgO powder by, for example, a spray method. Each electrode is V, ~■3 as shown in the figure.
voltage is supplied.

The operation of the thus constructed fluorescent display tube is as follows. When the activation stimulation filament 5 is heated with a voltage v1 of about 10 volts, thermoelectrons are emitted, and these thermoelectrons impinge on the cold cathode 3 and cause secondary electrons to be emitted from the cold cathode 17 cold cathode 30Mg0 layer, forming the buds of an electron avalanche. Generate electrons.

At this time, the MgO layer has a positive band 1. Now, if a positive potential of about 200 volts is applied to the SSE sustaining electrode 6 to the cold cathode 3, the cold cathode 3 will start emitting electrons continuously, and this state will be triggered by the activation stimulus. Filament 50 continues even if the power is turned off. For this reason, S
A collector current continues to flow through the SE sustaining electrode 6, resulting in a keep-alive state. In addition, heating of the starting stimulation filament 5 for applying an electron shock to the cold cathode 3 can be done within 1 second, and the circuit to which voltage 1 is connected will be turned off after about 1 second has passed after the voltage is generated. That's how it is.

The electrons generated in this way are accelerated by the control grid 7 to which a positive voltage is applied, and are caused to collide with the anode 8, causing the fluorescent screen coated there to emit light. You can see through it. In this case, the phosphor screen can be formed into any shape, and since it is of a reverse view type, it goes without saying that the cathode part does not interfere with observation. The guide 3 supplies a voltage of about 30 volts when the fluorescent display tube emits light.

〔Effect of the invention〕

As explained in Explanation 1 above, this invention is equipped with a cold cathode, a starting stimulation filament, and a self-emission sustaining electrode, and the cold cathode is heated only at the beginning of starting, so it has the following effects. .

(1) Since electrons are emitted from the MgO cold cathode, even if the oxide coated on the starting stimulation filament peels off to some extent, the luminescence unevenness of the phosphor will be reduced, so there is no need to pay much attention to assembly. Improves workability.

(2) Since the filament is used to stimulate startup, it only needs to be lit during startup, which reduces disconnection accidents, suppresses evaporation of oxides, and eliminates brightness reduction due to evaporation of oxides.

(3) Since there is no need to continuously heat the cathode, power consumption is reduced.

(4) Since the electric power for heating the cathode has been reduced, the temperature quenching phenomenon of the phosphor due to the rise in the temperature of the bulb due to the heat radiated from the filament is eliminated, and a decrease in brightness does not occur.

[Brief explanation of drawings]

The figure is a sectional view showing an embodiment of a reverse view type fluorescent display tube according to the present invention. 1...Reverse view type fluorescent display tube, 2...N
i Substrate metal plate, 3... MgO cold cathode, 4... Spacer glass, 5... Filament for starting stimulation, 6
... SSE sustaining electrode, 7 ... control grid, 8 ... anode, 9 ... transparent glass substrate.

Claims (1)

[Claims] In a reverse-view fluorescent display tube in which a transparent anode having a desired pattern shape is formed on a transparent glass substrate, and the light emitted when electrons emitted from the cathode impinge on the anode are observed from the anode side. , Mg on Ni-based metal plate
A revieve-type fluorescent display tube characterized by comprising a cold cathode coated with O, a filament for activation stimulation, and a self-emission sustaining electrode.