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US 7,247,981 B2Granted
Image forming apparatus
AssigneeCanon Kabushiki Kaisha
InventorKoji Yamazaki
Life of this patent
Estimating the term…
Abstract
In an image forming apparatus utilizing an electron emitting device, a guard electrode for preventing a creepage discharge from an anode electrode is provided without causing an abnormal discharge with a spacer. A guard electrode positioned at a predetermined distance (x) from a metal back constituting an anode electrode is positioned at such a distance (Lg) from a spacer as not to cause a discharge according to a ratio (x/hs) of the distance x and a height (hs) of a spacer.
Claims4
An image forming apparatus comprising:
- a cathode substrate having plural electron emitting devices and a cathode electrode;
- an anode substrate positioned in an opposed relationship to said cathode substrate and having a light emitting member capable of emitting light by an irradiation with electrons emitting from said electron emitting devices, an anode electrode and a guard electrode;
- a plate-shaped spacer positioned between the cathode electrode and the anode electrode and between the cathode electrode and the guard electrode in contact with the cathode electrode and the anode electrode;
- and
- a frame member provided between a peripheral portion of the cathode electrode and the anode electrode and adapted to constitute a vacuum container together with the cathode substrate and the anode substrate:
- wherein the guard electrode is positioned between the anode electrode and the frame member, and a distance x [m] between the anode electrode and the guard electrode, a height hs [m] of the spacer, a potential Va [V] of the anode and a gap Lg [m] between the guard electrode and the spacer satisfy a following condition:
- (
- for
-
-
- x
- ≤
- 0.5
-
-
- hs
- )
- Lg
- ≥
- [
- -
- x
- hs
- +
- 0.8
- ]
-
- Va
- 4
- ×
- 10
- 8
- (
- 1
- )
- (
- for
-
-
- 0.5
-
- hs
- <
- x
- ≤
- hs
- )
- Lg
- ≥
- [
- -
- 0.4
-
- x
- hs
- +
- 0.5
- ]
-
- Va
- 4
- ×
- 10
- 8
- (
- 2
- )
- (
- for
-
-
- hs
- <
- x
- )
- Lg
- ≥
- 0.1
-
-
- Va
- 4
- ×
- 10
- 8
- .
- (
- 3
- )
86 more elements
Dependencies are inferred from the claim text.