Electron emitting device

Abstract: An electron emitting device for causing electron emission from a high resistance film by a current supply therein, wherein said high resistance film is composed of an agglomerate of fine metal particles having small gaps therebetween, characterized in that the size of said particles and the size of the gaps therebetween are relatively uniform.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a so-called surface conduction electron emitting device, for causing electron emission by supplying a current to a high resistance film. Related Background Art A surface conduction electron emitting device is provided with a high resistance film in which the film-constituting material is discontinuous as an island structure or has defects, and emits electrons by supplying a current to such resistance film. Conventionally such high resistance film has been obtained by forming, on a insulating substrate, a thin film of metal, metal oxide or semi-metal by chemical vapor deposition or sputtering, and applying a current to thus formed film of several ohms to several hundred ohms to cause local destructions of the film by Joule's heat, thereby obtaining a resistance of several killoohms to several hundred megaohms. However, because of such forming process, the electron-emitting device cannot be formed on another semiconductor device but has to be formed as a separate device. The manufacturing process is therefore inevitably complex, and it has been difficult to achieve compactization through integration with a driving circuit. Besides, in the conventional resistance film utilizing metal, metal oxide or semi-metal, the quantity of electron emission is increased by forming, on the surface of said film, a layer of a material for reducing the work function such as a Cs or CsO layer, stable electron emission cannot be expected since the alkali metal such as cesium is unstable. Such unstability can be prevented by forming a silicide of such alkali metal, but the formation of a silicide or oxide layer on the conventional thin film of metal, metal oxide or semi-metal complicates the manufacturing process. Also such conventional forming process is unstable, so that the produced electron emitting devices show fluctuation in the efficiency of electron emission and are associated with a short service life. SUMMARY OF THE INVENTION An object of the present invention is to provide an electron emitting device not associated with the above-mentioned drawbacks associated with the prior technology. Another object of the present invention is to provide an electron emitting device provided with a high electron emission efficiency, a limited device-to-device fluctuation of the characteristics, and a long service life. BRIEF DESCRIPTION OF THE DRAWINGS Figs. 1 is a schematic view showing an embodiment of the electron emitting device of the present inveniton; Fig. 2 is a schematic cross-sectional view of an example of the coarse high resistance film in said embodiment. Fig. 1 is a schematic plan view of the electron emitting device constituting an embodiment of the present invention. Referring to Fig. 1, on an insulating member 101 such as a glass plate, there are provided electrodes 102, 103 for current supply, between which formed is a high resistance film 104 composed of fine particles. Fig. 2 is a schematic cross-sectional view of an example of the high resistance film 104 in the present embodiment. In Fig. 2, metal particles of a size of 0.1 to 10 µm are formed with a distance of 10 - 100 Å. on the insulating member 101 to constitute a coarse high resistance film 104 having discontinuous areas of regular distribution in the sense that the size and gap of the particles are relatively uniform.

Claims: An electron emitting device for causing electron emission from a high resistance film by a current supply therein, wherein said high resistance film (104) is composed of an agglomerate of metal particles (105) having gaps therebetween, characterized in that said gaps are small in comparison with the size of the metal particles and the high resistance film has discontinuous areas of regular distribution in the sense that the size and gaps of the particles are relatively uniform.

Inventors: OKUNUKI MASAHIKO, SHIMIZU AKIRA, SHIMODA ISAMU, SUGATA MASAO, SUZUKI AKIRA, TSUKAMOTO TAKEO, OKUNUKI, MASAHIKO, SHIMIZU, AKIRA, SHIMODA, ISAMU, SUGATA, MASAO, SUZUKI, AKIRA, TSUKAMOTO, TAKEO, SUGATA, MASAO C/O CANON KABUSHIKI KAISHA
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1987
Main classification: H01J1
IPC codes: H01J1