Droplet ejection device

Abstract

A droplet ejection device includes a droplet ejection head, a conveyance member, a cleaning unit and a coating unit. The droplet ejection head ejects droplets. The conveyance member retains a recording medium and conveys the recording medium to oppose the droplet ejection head. The cleaning unit cleans the conveyance member. The coating unit applies a coating liquid, with a characteristic of repelling the liquid that is ejected from the droplet ejection head, onto the conveyance member. A surface tension γo of the coating liquid, a critical surface tension γb of the conveyance member, and a surface tension γi of the liquid that is ejected from the droplet ejection head satisfy the following equations (1) and (2).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein:

FIG. 1 is a side view showing general structure of an inkjet recording device of a first exemplary embodiment of the present invention.

FIG. 2 is a side view showing general structure of the inkjet recording device of the first exemplary embodiment of the present invention.

FIG. 3 is a side view showing general structure of a printing section of the inkjet recording device of the first exemplary embodiment of the present invention.

FIG. 4 is a sectional view enlargedly showing a conveyance belt which is provided in the inkjet recording device of the first exemplary embodiment of the present invention.

FIG. 5 is a side view showing general structure of a printing section of an inkjet recording device of a second exemplary embodiment of the present invention.

FIG. 6 is a side view showing general structure of a printing section of an inkjet recording device of a third exemplary embodiment of the present invention.

FIG. 7 is a side view showing general structure of a printing section of an inkjet recording device of a fourth exemplary embodiment of the present invention.

FIG. 8 is a side sectional view showing a combined belt-cleaning and oil-coating unit which is provided in an inkjet recording device of a fifth exemplary embodiment of the present invention.

FIG. 9A is an exploded perspective view showing a first blade and a second blade which are provided at the combined belt-cleaning and oil-coating unit of FIG. 8, and FIG. 9B is a plan view of the first blade and second blade.

FIG. 10 is a side sectional view showing a variant example of the combined belt-cleaning and oil-coating unit of FIG. 8.

FIG. 11A is an exploded perspective view showing a variant example of the first blade and second blade, which are provided at the combined belt-cleaning and oil-coating unit of FIG. 10, and FIG. 11B is a plan view of the variant example.

FIG. 12 is a plan view showing another variant example of the first blade and second blade which are provided at the combined belt-cleaning and oil-coating unit of FIG. 8.

FIG. 13A is a side sectional view showing another variant example of the combined belt-cleaning and oil-coating unit of FIG. 8, and FIG. 13B is a view schematically showing a method of formation of a first blade and second blade which are provided at the combined belt-cleaning and oil-coating unit of FIG. 13A.

FIG. 14A is a side sectional view showing the combined belt-cleaning and oil-coating unit of FIG. 8, and FIG. 14B is a side sectional view showing a variant example of the combined belt-cleaning and oil-coating unit of FIG. 14A.

FIG. 15 is a side sectional view showing a belt-cleaning unit and an oil-coating unit which are provided in an inkjet recording device of a sixth exemplary embodiment of the present invention.

FIGS. 16A and 16B are side views showing a mechanism for mounting/removing the oil-coating unit of FIG. 15 at a device main body.

FIG. 17A is a side sectional view showing a variant example of disposition of the oil-coating unit of FIG. 15, and FIG. 17B is a side sectional view showing a variant example of disposition of the belt-cleaning unit of FIG. 15.

FIG. 18 is a side sectional view showing a variant example of the belt-cleaning unit and oil-coating unit of FIG. 15.

FIG. 19 is a side sectional view showing another variant example of the oil-coating unit of FIG. 15.

FIG. 20 is a side sectional view showing a belt-cleaning unit and an oil-coating unit which are provided in an inkjet recording device of a seventh exemplary embodiment of the present invention.

FIG. 21 is a side sectional view showing a variant example of disposition of the belt-cleaning unit and the oil-coating unit of FIG. 20.

FIG. 22 is a perspective view of a charging roller unit which is provided at an inkjet recording device of an eighth exemplary embodiment of the present invention.

FIG. 23 is a front view of the charging roller unit which is provided at the inkjet recording device of the eighth exemplary embodiment of the present invention.

FIG. 24 is a side view schematically showing a state of discharging between a charging roller and a conveyance belt which are provided at the inkjet recording device of the eighth exemplary embodiment of the present invention.

FIG. 25 is a perspective view showing a charging roller unit which is provided at an inkjet recording device of a ninth exemplary embodiment of the present invention.

FIG. 26 is a side view of the charging roller unit which is provided at the inkjet recording device of the ninth exemplary embodiment of the present invention.

FIG. 27 is the side view of the charging roller unit which is provided at the inkjet recording device of the ninth exemplary embodiment of the present invention.

FIG. 28 is a side view showing general structure of an inkjet recording device of a tenth exemplary embodiment of the present invention.

FIG. 29 is a side view showing general structure of the inkjet recording device of the tenth exemplary embodiment of the present invention.

FIG. 30 is a side view showing general structure of a printing section of the inkjet recording device of the tenth exemplary embodiment of the present invention.

FIGS. 31A and 31B are sectional views enlargedly showing a charging roller and a conveyance belt which are provided at an inkjet recording device of the tenth exemplary embodiment of the present invention.

FIGS. 32A and 32B are another sectional views enlargedly showing the charging roller and the conveyance belt which are provided at the inkjet recording device of the tenth exemplary embodiment of the present invention.

FIG. 33 is a side view showing general structure of a printing section of an inkjet recording device of an eleventh exemplary embodiment of the present invention.

FIG. 34 is a sectional view enlargedly showing a charging roller and a conveyance belt which are provided at the inkjet recording device of the eleventh exemplary embodiment of the present invention.

FIG. 35 is a side view showing general structure of a printing section of an inkjet recording device of a twelfth exemplary embodiment of the present invention.

FIGS. 36A and 36B are sectional views enlargedly showing charging rollers and conveyance belts which are provided at inkjet recording devices of the eleventh exemplary embodiment of the present invention.

FIGS. 37A and 37B are sectional views showing variant examples of oil-coating units which are provided at inkjet recording devices of the eleventh exemplary embodiment of the present invention.

FIG. 38 is a side view showing general structure of a printing section of an inkjet recording device of a thirteenth exemplary embodiment of the present invention.

FIG. 39 is a side view showing general structure of a printing section of an inkjet recording device of a fourteenth exemplary embodiment of the present invention.

FIG. 40 is a side view schematically showing a recording head and a conveyance belt of a previous inkjet recording device.

FIG. 41 is a side view schematically showing a state of discharging between a charging roller and a conveyance belt in a previous inkjet recording device.

FIG. 42 is a graph showing relationships between voltages applied to a charging roller and surface potentials on a conveyance belt in a previous inkjet recording device.

Claims

1. A droplet ejection device comprising: a droplet ejection head that ejects droplets;a conveyance member that retains a recording medium and conveys the recording medium to oppose the droplet ejection head;a cleaning unit that cleans the conveyance member; anda coating unit that coats coating liquid, with a characteristic of repelling liquid that is ejected from the droplet ejection head, onto the conveyance member,wherein a surface tension γo of the coating liquid, a critical surface tension γb of the conveyance member, and a surface tension γi of the liquid that is ejected from the droplet ejection head satisfy the following equations (1) and (2): γo<γb   (1)γo<γi   (2).

2. The droplet ejection device of claim 1, wherein the liquid that is ejected from the droplet ejection head comprises aqueous ink, and the coating liquid includes a water repellent liquid.

3. The droplet ejection device of claim 1, further comprising a web that absorbs the coating liquid and moves while repeatedly abutting against the conveyance member, wherein the coating unit includes a first abutting portion that abuts against the conveyance member at a movement direction upstream side of the web, and coats the coating liquid onto the conveyance member, andthe cleaning unit includes a second abutting portion that abuts against the conveyance member downstream in the movement direction of the web, and scrapes off liquid that has adhered to the conveyance member.

4. The droplet ejection device of claim 1, wherein the cleaning unit and the coating unit are integrally structured.

5. The droplet ejection device of claim 4, wherein the cleaning unit includes a first blade that abuts against the conveyance member, andthe coating unit includes a second blade that is disposed in parallel with the first blade, a path along which the coating liquid flows being formed between the first blade and the second blade.

6. The droplet ejection device of claim 4, wherein the cleaning unit includes a first blade that abuts against the conveyance member, andthe coating unit includes an absorbent body that is joined to the first blade and absorbs the coating liquid.

7. The droplet ejection device of claim 1, wherein the conveyance member comprises an endless belt, and the droplet ejection device further comprises a driving roller round which the belt is wound, wherein the cleaning unit and the coating unit abut against a portion of the belt that is wound round the driving roller.

8. The droplet ejection device of claim 1, wherein the conveyance member comprises an endless belt, and the droplet ejection device further comprises a driving roller round which the belt is wound, wherein one of the cleaning unit or the coating unit abuts against a portion of the belt that is wound round the driving roller,and a distance L between a position at which the other of the cleaning unit or the coating unit abuts against the belt and the portion of the belt that is wound round the driving roller satisfies the following equation (A): 0≦L<0.01×E×t×w/ΔF   (A)in which ΔF is an amount of change of load that the belt receives from the other of the cleaning unit or the coating unit (N),E is a longitudinal modulus of elasticity of the belt (N/mm2),t is a thickness of the belt (mm), andw is a width of the belt (mm).

9. The droplet ejection device of claim 1, wherein at least one of the coating unit and the cleaning unit is mountable and removable at a main body of the device.

10. The droplet ejection device of claim 1, further comprising a charging unit that, without touching the conveyance member, electrostatically adheres the recording medium to the conveyance member by electrostatically charging the conveyance member and the recording medium.

11. The droplet ejection device of claim 10, wherein the charging unit comprises a charging roller that is disposed at an upstream side in the conveyance direction of the recording medium relative to the droplet ejection head, so as to not touch the conveyance member and such that a gap between the conveyance member and the charging roller is less than a thickness of the recording medium.

12. The droplet ejection device of claim 11, further comprising a spacer member that includes a circular peripheral surface which abuts against the conveyance member, the spacer member having a larger diameter than the charging roller, the gap being formed by provision of the spacer member at each of two axial direction end portions of the charging roller.

13. The droplet ejection device of claim 11, further comprising a support unit that supports the charging roller to be separated from the conveyance member, the gap being formed by provision of the support unit.

14. The droplet ejection device of claim 13, wherein the support unit comprises a gap adjustment unit that supports the charging roller such that the charging roller is movable toward and away from the conveyance member and that increases and reduces the gap by moving the charging roller toward and away from the conveyance member in accordance with thickness of the recording medium.

15. The droplet ejection device of claim 1, further comprising a charging unit that electrostatically adheres the recording medium to the conveyance member by electrostatically charging at least one of the conveyance member and the recording medium on the conveyance member, wherein the coating liquid is a high-resistance liquid with a higher volume resistivity than the liquid that is ejected from the droplet ejection head.

16. The droplet ejection device of claim 15, wherein the charging unit comprises a charging roller which touches the conveyance member and electrostatically charges the recording medium, and the coating unit includes the charging roller.

17. The droplet ejection device of claim 16, wherein the charging roller is formed with a member capable of absorbing liquid, and is impregnated with the coating liquid.

18. The droplet ejection device of claim 16, further comprising a supply unit that supplies the coating liquid to a surface of the charging roller.

19. The droplet ejection device of claim 15, wherein the volume resistivity of the coating liquid is equivalent to or greater than a volume resistivity of the conveyance member.

20. A droplet ejection device comprising: a droplet ejection head that ejects droplets;a conveyance member that retains a recording medium and conveys the recording medium to oppose the droplet ejection head; anda charging unit that electrostatically adheres the recording medium to the conveyance member by electrostatically charging at least one of the conveyance member and the recording medium on the conveyance member,wherein a high-resistance liquid is interposed between the charging unit and the conveyance member, a volume resistivity of the high-resistance liquid being higher than liquid that is ejected from the droplet ejection head and equivalent to or greater than a volume resistivity of the conveyance member.

21. The droplet ejection device of claim 20, further comprising a coating unit that coats the high-resistance liquid onto the conveyance member.

22. The droplet ejection device of claim 21, further comprising a cleaning unit that cleans the conveyance member.

23. The droplet ejection device of claim 20, wherein the charging unit comprises a charging roller that touches the conveyance member, electrostatically charges the recording medium, and applies the high-resistance liquid to the conveyance member.

24. The droplet ejection device of claim 23, wherein the charging roller is formed with a member capable of absorbing liquid, and is impregnated with the high-resistance liquid.

25. The droplet ejection device of claim 23, further comprising a supply unit that supplies the high-resistance liquid to a surface of the charging roller.

26. The droplet ejection device of claim 20, wherein the high-resistance liquid is insoluble with respect to the liquid that is ejected from the droplet ejection head.

27. The droplet ejection device of claim 20, wherein the high-resistance liquid includes a characteristic of repelling the liquid that is ejected from the droplet ejection head.

28. The droplet ejection device of claim 20, wherein a surface tension γo of the high-resistance liquid, a critical surface tension γb of the conveyance member, and a surface tension γi of the liquid that is ejected from the droplet ejection head satisfy the following equations (1) and (2): γo<γb   (1)γo<γi   (2).

29. The droplet ejection device of claim 20, wherein the liquid that is ejected from the droplet ejection head comprises aqueous ink, and the high-resistance liquid includes a characteristic of repelling the aqueous ink.