JP2881701B2 - Line arc tube - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear arc tube applied to a viewfinder for monitoring a shooting condition of a video camera.

[Related Art] Conventionally, a color CRT or a color liquid crystal display device has been used as this type of viewfinder.

[Problems to be Solved by the Invention] However, a conventional cathode ray tube or a liquid crystal display device as a color view finder is inevitably expensive because of the complicated electrode structure.

Accordingly, an object of the present invention is to provide an inexpensive linear arc tube constituting a part of a viewfinder according to a novel system.

[Means for Solving the Problems] To solve such problems, a linear arc tube according to the present invention comprises a filament cathode emitting thermoelectrons,
A shield electrode surrounding the filament cathode and shielding an external electric field for electrons emitted from the filament cathode, a first control electrode for controlling brightness by controlling passage of the electron beam, and diffusing the electron beam Alternatively, it is provided with a second control electrode to be focused, and a phosphor screen arranged in a dot shape which emits light by the projection of an electron beam coming from a filament cathode.

[Operation] The linear arc tube according to the present invention has a simple electrode structure.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a view showing a configuration of an embodiment of a linear arc tube according to the present invention. FIG. 1 (a) is a longitudinal sectional view, and FIG. 1 (b) is a transverse sectional view. In the figure, 1 is an insulating substrate, 2 is a translucent glass substrate arranged opposite to the insulating substrate 1, 3 is arranged between the insulating substrate 1 and the translucent glass substrate 2. Spacer glass 4 for hermetically sealing between the substrates is an exhaust pipe, and these insulating substrate 1, translucent glass substrate 2, spacer glass 3 and exhaust pipe 4 constitute an outer vacuum container 5. Reference numeral 6 denotes a filament support fixed inside the insulating substrate 1, reference numeral 7 denotes a filament cathode, reference numeral 8 denotes a shield electrode provided so as to surround the filament cathode 7, and shields an external magnetic field, reference numeral 9 denotes a getter, reference numeral 10
Is a getter shield to prevent scattering of getter film, 11
Is a filamentary cathode 7 on the inner surface side of the translucent glass substrate 1.
The fluorescent screen 11 is formed by arranging about 200 dots along the same horizontal direction. The fluorescent screen 11 is formed on the inner surface of the translucent glass substrate 2 independently by a transparent conductive film (not shown). A base electrode for applying a potential and a lead-out terminal for the base electrode are formed, and each base electrode is formed by applying a phosphor. Reference numeral 12 denotes a first control grid for controlling passage of the electron beam, 13 denotes a second control grid for diffusing or converging the electron beam, and 14 denotes a frit glass for fixing the second control grid 13. Each of these electrodes is housed in the outer vacuum container 5 and hermetically sealed.

In such a configuration, the electron beam emitted from the filamentary cathode 7 supported by the filament support 6 is efficiently diffused or focused by the opposing second control grid 13 and the first control grid 13
The light is accelerated by 12, collides with the phosphor screen 11 formed in a line, emits light, passes through the base electrode and the translucent glass substrate 2, is displayed on the front side, and its emission luminance is controlled. . In this case, when a positive potential is applied to the second control grid 13, the electron beam is diffused, and when a negative potential is applied, the electron beam is focused. The phosphor screen 11 is coated with phosphors of three primary colors of red (R), green (G), and blue (B) in the case of a color display, but is coated with a phosphor of one color in a monochrome display. You. Further, the shield electrode 8 provided so as to surround the filament cathode 7 is maintained at a potential substantially equal to that of the filament cathode 7 and stabilizes the potential of the electron cloud emitted from the filament cathode 7. It is also possible to adjust the total amount of electrons emitted from the filament cathode 7 by applying a potential to the getter shield 10 for preventing the getter film of the getter 9 from scattering.

In addition, as a specific example of the potential application relationship to each electrode, when the filament cathode 7 is set as a reference potential, the first control grid 12 and the phosphor screen 11 have a voltage of about 500 V, and the second A voltage of about 50 to +50 V is supplied.

FIG. 2 is a perspective view of a main part showing a configuration of a viewfinder using a linear arc tube according to the present invention. In the figure, reference numeral 21 denotes a linear arc tube for displaying only one scanning line of a video signal. Light emitted from the linear arc tube 21 is converged by a front lens 22, and this light is further reflected by a mirror 23. And is guided to the picture screen 24. One frame of the linear arc tube 21 is about 33 msec, and the mirror 23 is rotated in synchronization with this, and one image is displayed on the screen 24 at the end of each frame.

[Effects of the Invention] As described above, according to the linear arc tube according to the present invention, the filament cathode emitting thermionic electrons, and the filament cathode surrounding the filament cathode and being externally exposed to the electrons emitted from the filament cathode. A shield electrode for shielding an electric field, a first control electrode for controlling brightness by controlling passage of an electron beam, a second control electrode for diffusing or converging the electron beam, and an electron beam coming from a filament cathode By providing the phosphor screens arranged in a dot shape to emit light by the impact of the projection, an extremely excellent effect that a line-shaped light emitting tube for a viewfinder of a video camera can be provided with a simple configuration at a low cost can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a linear arc tube according to an embodiment of the present invention, and FIG. 2 is a diagram showing a configuration of a viewfinder using the linear arc tube according to the present invention. 1 ... insulating substrate, 2 ... translucent glass substrate, 3 ... spacer glass, 4 ... exhaust pipe, 5 ... outer vacuum container, 6 ...
... filament support, 7 ... filamentary cathode,
8 Shield electrode, 9 Getter, 10 Getter shield, 11 Fluorescent screen, 12 First control grid, 13
... Second control grid, 14... Frit glass.

Claims (1)

(57) [Claims] A filament cathode emitting thermoelectrons;
A shield electrode surrounding the filament cathode and shielding an external electric field for electrons emitted from the filament cathode, a first control electrode controlling passage of an electron beam, and diffusing or focusing the electron beam. A linear arc tube comprising: a second control electrode; and a dot-shaped phosphor screen which emits light by emitting an electron beam coming from the filament cathode.