JPS63150835A - Cathode-ray tube - Google Patents

Abstract

PURPOSE:To display an image having sufficient brightness with the low control voltage by providing an electron multiplier on an electron gun. CONSTITUTION:An electron multiplier 6 is provided between the accelerating electrode 5 and the focusing electrode 7 of the electron gun 2 of a cathode-ray tube, a secondary electron beam multiplied with a small quantity of an electron beam emitted from a cathode 2 as primary electrons is emitted toward the electrode 7, and an electron beam spot to obtain the necessary brightness on a fluorescent screen is formed. Accordingly, an image having sufficient brightness can be displayed with the low control voltage.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an electron gun included in a cathode ray tube such as a picture tube. The present invention relates to a cathode ray tube equipped with an electron gun device that focuses secondary electrons multiplied by an electron multiplier using a focusing lens.

[Conventional technology]

An electron gun device included in a cathode ray tube such as a picture tube has at least a cathode, a control electrode, an accelerating electrode, a focusing electrode, and an anode,
It has the function of controlling the filtering of the electron flow emitted from the cathode with a control electrode, forming an electron beam together with an accelerating electrode, and focusing it on a fluorescent screen with a focusing electrode to form an electron beam spot.

FIG. 8 is a schematic cross-sectional view showing an example of a conventional cathode ray tube. In the figure, the cathode ray tube includes a tube body (1), an electron gun (2), and a phosphor screen (9). , the electron gun (2) has a cathode (3), a control type AI (+l), an accelerating electrode (5), a focusing electrode (7), and an anode (8) coaxially arranged in a predetermined position with the electron beam passage hole as the axis of symmetry. Figure 4 is a schematic diagram for explaining an example of the operation of an electron gun. ) to 400V, focusing electrode i7) Ni6 K! /
, 25 KV is applied to the anode (8), and a negative potential, e.g. -5 KV is applied to the control electrode (4) to adjust the amount of electron beam.
0V is applied to obtain an appropriate amount of electron flow. The cathode (3) is
It consists of a cathode tube (lO), an electron emitter m (11), and a heater θ. Focusing electrode (7) and anode (8)
Electron lenses (1 to 1), which are equivalently shown as optical lenses in the figure, are formed near the boundary of the cathode (3).
The electron beam field emitted from the electron beam has its electron flow rate controlled by the control electrode (4), is accelerated by the accelerating electrode (5), intersects near the accelerating electrode (F+), and forms a crossover point. While diverging, the electron beams enter the focusing electrode (7) and are focused by the electron beams α~, creating an electron beam spot α9) on the phosphor screen (9). The crossover point is the object point of the electron lens, and the electron beam spot α9) is the image point.

In order to project an image on the fluorescent screen (9) using the cathode ray tube configured as described above, it is necessary to modulate the cathode current that forms the electron beam a3 depending on the brightness of the image.

FIG. 5 is a diagram explaining how to modulate the cathode current, where the vertical axis represents the cathode current emitted from the cathode (3), and the horizontal axis represents the voltage applied to the control electrode (4). show. The relationship between control electrode voltage and cathode current is shown by the curve (
2o) is given by As shown in the figure, when the potential of the control electrode (2) is 1100V, the cathode current is zero, that is, in a cut-off state. In the case of 0, -50V, the cathode current is 800 μA, and in the case of Ov, the cathode current is 10
Since the cathode current is operated to obtain 00 μA, the cathode current changes in accordance with the waveform of the signal voltage train for projecting an image, and an image can be projected on the phosphor screen (9). Generally, a cathode current of at least 1000 μA is required to obtain sufficient brightness on the phosphor screen of a picture tube used in a television set or a display monitor. Therefore, in order to project images from dark areas to maximum brightness, it is necessary to display a maximum of 10
A high signal voltage cycle of 0V is required, and in order to obtain such a high signal voltage, the riIj8ii breakdown voltage of the element used in the output stage of the signal amplifier must be at least 100V or more. When a transistor is used as an output element, a base breakdown voltage of approximately 150V is required to satisfy this operating characteristic. It is well known that integrated circuit elements are useful for simplifying the fabrication of electronic circuits, since the output stage of a signal amplifier requires elements with high withstand voltage. The pressure resistance of the device is usually about 20V to 80V, and integrated circuit devices cannot be used in the output stage. Therefore, there is a limit to the integration or simplification of the video circuit in that the output stage must be removed.

[Problem that the invention seeks to solve]

In conventional cathode ray tubes, the modulation of the cathode current must be increased in order to sufficiently change the brightness of the phosphor screen from the dark area to the maximum brightness, and for this reason, the signal voltage applied to the control electrode is required to be as high as approximately 100V. Requires voltage. Therefore, even if an attempt is made to simplify and lower the cost by integrating the operating circuit of a cathode ray tube using an integrated circuit element (so-called IC), the video output stage of the circuit is The problem was that it had to be excluded.

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to provide a cathode ray tube that can project images with sufficient brightness even with a low control voltage.

[Means for solving problems]

The cathode ray tube according to the present invention includes an electron multiplier between an accelerating electrode and a focusing electrode, and multiplies a small amount of electron current emitted from the cathode as primary electrons, and then multiplies the secondary electron current to the focusing electrode. It is designed to emit light toward.

[Effect]

In the cathode ray tube of this invention, a small amount of electron flow emitted from the cathode of the electron gun is modulated by the control electrode, so the signal voltage may be low. Secondary electrons that are amplified from a small amount of electron flow are emitted toward a focusing electrode, and the focusing electrode focuses the secondary electron flow to form an electron beam spot that provides the necessary phosphor screen brightness.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. 1st
The figure is a schematic cross-sectional view showing one embodiment of the present invention. In the figure, an electron gun (2) is provided at the neck of a tube body (1), and a fluorescent screen (9) is arranged on the facing side. ing. Tube (1+
, the location of the electron gun (2), and the fluorescent screen (9) may be the same as those of the conventional one. FIG. 2 is a partially enlarged sectional view for explaining the configuration and operation of the electron gun of this embodiment. The difference from the conventional one is that the accelerating electrode (
An electron multiplier +8) composed of a microchannel plate α is disposed between the electron beam 5) and the focusing electrode (7). The electrodes of the electron gun (2) are arranged coaxially at predetermined intervals with the electron beam passage hole as the axis of symmetry, and the support body holding these electrode groups is shown in the figure. is omitted. cathode(
3) The cathode cylinder 00) is heated to about 800 m by the heater (+2).
It is heated to a temperature of 0.degree. C. and emits a current of thermionic electrons from thermionic radiation Nl (11).

The electron multiplier (6) is a microchannel plate Q
4), the front electrode α on the side of the accelerating electrode (6), and the back electrode 1.4 on the side of the focusing electrode (7). The basic configuration is a sand winch structure sandwiched between The microchannel plate α is, for example, a bundle of lead glass tubes whose main components are lead oxide PbO and silicon oxide 5iO2, and cut into plate shapes with the tube direction slightly inclined.

The area of the opening of the microchannel plate (141) is determined so that even if the primary electron beam is large, the incident electrons can be reliably received into the electron multiplier. Electrons enter the tube and are multiplied while repeatedly colliding with the inner wall of the tube, and the multiplied secondary electrons are emitted from the other end.

In the above configuration, if the electron multiplication factor is set to 5, for example, in order to obtain a beam current of 1000 μA that gives maximum brightness to the fluorescent screen (9) of the cathode ray tube, the cathode current shown in FIG. 5 is 200 μA. good. As such operating conditions, for example, based on the cathode (3) of the electron gun (2),
100V to accelerating electrode (5), focusing wL pole (7) lc7K
V, positive i (s+25 KV) DC voltages are applied, respectively. In this case, in FIG. 5, the relationship between the control electrode voltage and the cathode current is given by the curve □□□, and the control [! When the potential of +4) is 120V, the cathode current is zero, that is, in the cut-off state, and in the case of OV, a maximum cathode current of 200 μA is obtained. To adjust the electron flow rate, a cathode current of 50 μA is obtained when a negative potential, for example −10 V, is applied to the control electrode (4). When the negative 8i-ray tube is used as an image display device, this negative potential is given as a video signal, and it is understood that the signal voltage A for displaying an image only needs to be 20V at maximum. The electron beam emitted from the cathode (3) has its electron flow rate controlled by the control electrode (4), is accelerated by the acceleration electrode (5), and intersects between the control electrode (4) and the acceleration electrode (5). After forming one point of crossover, the electrons diverge as they pass around the accelerating electrode (5) and enter the electron multiplier (6) as negative electrons. For the operation of the electron multiplier (6), for example, a voltage difference of IKV is applied to the front electrode (15) and the back electrode (16+). It is determined by the characteristics of the electron beam and the specifications for the electron multiplication factor.The primary electrons incident on the electron multiplier (6) are distributed between the front electrode α6) and the back electrode (+6).
The secondary electrons are emitted step by step while being accelerated by the potential difference of
7) and enters the focusing electrode (7). At this time,
Since the electron multiplication factor is 5, a secondary electron flow that is 5 times as large as the primary electron flow can be obtained. Near the boundary between the focusing electrode (7) and the anode (8), an electron lens (1~), which is shown isometrically as an optical lens in the figure, is formed. is focused to create an electron beam spot (+9) on the phosphor screen (9).As mentioned above, the electron flow rate of the electron beam (17) that gives maximum brightness to the phosphor screen (9) is 10
00 μA is required, but since an electron multiplication factor of 5 can be obtained, the cathode current may be 200 μA at maximum. therefore,
The signal voltage (23) for modulating the cathode laminar flow that forms the electron beam θ4 of primary electrons only needs to be 20V at most, so the output stage of the signal amplifier for obtaining this signal voltage (23) is integrated. Circuit elements can be used. This electron multiplication factor is determined by both the voltages applied to the front electrode (5) and back electrode (16) to the electron multiplier (6), so it is possible to make it even larger (signal voltage C;
Needless to say, it can be lowered by having .

In the above embodiment, the electron multiplier (6) is constructed of a microchannel plate circle, but it goes without saying that an electron multiplier having similar functions can be applied.

[Effects of the Invention] As described above, according to the present invention, an electron multiplier that multiplies and emits the electron beam emitted from the cathode is provided between the accelerating wt pole and the focusing electrode. , the cathode current may be small. Therefore, since the signal voltage that modulates the current can be made sufficiently low, it is possible to use an S product circuit element in the output stage of the signal amplifier that drives the cathode ray tube. The circuit can be simplified. Furthermore, since the phosphor screen is made to emit light by the electron flow multiplied by the electron multiplier, there is no need to increase the current density of the cathode, and the burden on the cathode is light, so the cathode has the characteristic of a long life.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a schematic structure of one embodiment of the present invention;
Fig. 2 is an enlarged sectional view of the electron gun portion of this embodiment, Fig. 8 is a sectional view showing the structure of a conventional cathode ray tube, and Fig. 4 is a partially enlarged sectional view showing the structure of the electron gun of this conventional example. , FIG. 5 is a characteristic diagram showing the relationship between control voltage and cathode current for explaining the effects of the embodiment of the present invention. +1)... tube body, (2)... electron gun, (3)...
Cathode, (4)...control electrode, (6)...acceleration electrode,
(6)...Electron multiplier, (7)...Focusing electrode, (
8)...Anode, α fathom...Electron beam of primary electrons, 0
4)...Microchannel plate, σ5)...
front electrode, (161... back electrode, αη... electron beam of secondary electrons). Also, in each figure, the same reference numerals indicate the same or equivalent parts.

Claims (2)

[Claims] (1) It consists of a tube, a fluorescent screen formed on the inner surface of the panel of this tube, and an electron gun that shoots an electron beam into the fluorescent screen, and the electron gun has a cathode and a control electrode. and,
an accelerating electrode, a focusing electrode, an anode, and an electron multiplier disposed between the accelerating electrode and the focusing electrode, which multiplies the electron flow emitted from the cathode and emits it toward the focusing electrode. A cathode ray tube comprising: (2) The cathode ray tube according to claim 1, wherein the electron multiplier is constituted by a microchannel plate.