초록 ▼

An ink level detecting device also functions as a cover opening sensor, and an ink-jet image forming apparatus having the ink level detecting device functions in the same way. The ink level detecting device detects an ink level in an ink container mounted on an ink container mounting unit, and inclu

An ink level detecting device also functions as a cover opening sensor, and an ink-jet image forming apparatus having the ink level detecting device functions in the same way. The ink level detecting device detects an ink level in an ink container mounted on an ink container mounting unit, and includes a first electrode disposed on an inner surface of a cover which covers the ink container mounting unit and a second electrode disposed on the ink container. The ink level detecting device detects an opening of the cover as well as an ink level variation by sensing a variation in a capacitance between the first and second electrodes.

대표청구항 ▼

What is claimed is: 1. An ink level detecting device which detects an ink level in an ink container mounted on an ink container mounting unit, the ink level detecting device comprising: a first electrode disposed at a cover which covers the ink container mounting unit; and a second electrode dispos

What is claimed is: 1. An ink level detecting device which detects an ink level in an ink container mounted on an ink container mounting unit, the ink level detecting device comprising: a first electrode disposed at a cover which covers the ink container mounting unit; and a second electrode disposed on the ink container, wherein the ink level detecting device detects an opening of the cover as well as variations in the ink level by sensing a capacitance variation between the first and second electrodes. 2. The ink level detecting device of claim 1, wherein a capacitance variation range is adjusted so that the capacitance variation falls outside of a variation range when the cover is open. 3. The ink level detecting device of claim 2, wherein the second electrode is formed out of a flexible conductive film. 4. The ink level detecting device of claim 3, wherein the second electrode is formed out of a thin metal plate, a thin metal film, or a synthetic resin film having a coated metal layer. 5. An ink level detecting device of an ink-jet image forming apparatus, which detects an ink level in an ink container mounted on an ink container mounting unit, the ink level detecting device comprising: a first electrode disposed at a cover that selectively opens and closes the ink container mounting unit; a shrinkable ink pack located within an ink container and having a top that is vertically lowered as the ink level therein is reduced; and a second electrode having a front end portion attached to the ink container and a back end portion connected to the front end portion and facing the first electrode at a predetermined distance from the first electrode when the cover is closed, wherein the front end portion of the second electrode is vertically lowered as the shrinkable ink pack runs out of ink, causing a corresponding horizontal movement of the back end portion of the second electrode so that a facing area of the first electrode and the back end portion of the second electrodes varies, wherein the ink level detecting device detects an opening of the cover as well as variations in the ink level by sensing a capacitance variation between the first and second electrodes. 6. The ink level detecting device of claim 5, wherein a capacitance variation range is adjusted so that the capacitance variation falls outside of the capacitance variation range when the cover is open. 7. The ink level detecting device of claim 5, wherein the ink container comprises a guide unit which allows the back end portion of the second electrode to slide in parallel with the first electrode, wherein the back end portion of the second electrode moves horizontally along the guide unit and the front end portion of the second electrode is fixed on a top of the shrinkable ink pack by flexibly extending along an inner-top surface and sidewall of the ink container. 8. The ink level detecting device of claim 5, wherein the shrinkable ink pack comprises a reinforcing plate disposed on the top of the shrinkable ink pack. 9. The ink level detecting device of claim 8, wherein the front end portion of the second electrode is fixed onto the reinforcing plate. 10. The ink level detecting device of claim 5, wherein the second electrode is formed out of a flexible conductive film. 11. The ink level detecting device of claim 5, wherein the capacitance variation between the first and second electrodes is detected by measuring a variation of an output voltage signal with respect to an alternating current input having a predetermined frequency. 12. The ink level detecting device of claim 11, wherein the second electrode is formed out of a flexible conductive film. 13. The ink level detecting device of claim 12, wherein the second electrode is formed out of a thin metal plate, a thin metal film, or a synthetic resin film having a coated metal layer. 14. An ink-jet image forming apparatus comprising: an ink container mounting unit that accommodates an ink container; a cover to selectively open and close the ink container; and an ink level detecting device that detects an ink level in the ink container, the ink level detecting device comprising, a first electrode disposed at a cover that covers the ink container mounting unit; and a second electrode disposed on the ink container, wherein the ink level detecting device detects an opening of the cover, as well as variations in the ink level, by sensing a capacitance variation between the first and second electrodes. 15. An ink-jet image forming apparatus comprising: an ink container mounting unit that accommodates an ink container; a cover to selectively open and close the ink container; and an ink level detecting device that detects an ink level in the ink container, the ink level detecting device comprising, a first electrode disposed at the cover, a shrinkable ink pack located within the ink container and having a top that is vertically lowered as the ink level therein is reduced; and a second electrode having a front end portion attached to the ink container and a back end portion connected to the front end portion and facing the first electrode at a predetermined distance from the first electrode, when the cover is closed, wherein the front end portion of the second electrode is vertically lowered as the shrinkable ink pack runs out of ink, causing a corresponding horizontal movement of the back end portion of the second electrode, so that a facing area of the first electrode and the back end portion of the second electrodes varies, wherein the ink level detecting device detects an opening of the cover, as well as variations in the ink level, by sensing a capacitance variation between the first and second electrodes. 16. An ink level detecting device, comprising: a first electrode disposed at a cover that selectively opens and closes an ink container mounting unit; a shrinkable ink pack located within an ink container and having a top that is vertically lowered as an ink level therein is reduced; and a second electrode facing the first electrode when the cover is closed which slides parallel to the first electrode as the ink level is reduced, wherein the first and second electrodes are designed to function as a capacitor and the ink level is measured by measuring the capacitance of the electrodes by measuring a common surface area A in which the first electrode and second electrodes face each other, according to the formula: description="In-line Formulae" end="lead"C=∈��A/d,description="In-line Formulae" end="tail" wherein C is capacitance, ∈ is a dielectric constant between the facing electrodes, and A is the common surface area in which the first and second electrodes face each other. 17. An ink level detecting device, which detects an ink level in ink containers mounted on an ink container mounting unit, the ink level detecting device comprising: a first electrode disposed at a cover which covers the ink container mounting unit; and a plurality of second electrodes, wherein each ink container has a corresponding second electrode disposed on top, and the ink level detecting device detects an opening of the cover as well as variations in the ink level of each ink container by sensing a capacitance variation between the first and each of the second electrodes. 18. The ink level detecting device of claim 17, wherein the first electrode is formed in a single section on the cover. 19. The ink level detecting device of claim 17, wherein the first electrode is formed in a plurality of sections on the cover corresponding to the plurality of second electrodes.