Image forming apparatus

Abstract

An image forming apparatus capable of applying an adequate amount of fixing fluid to an unfixed toner image and producing high-quality images having high resolution and high image density with stability for a longer period of time while protecting the interior thereof against fixing fluid leakage and achieving reduction in fixing fluid consumption is provided. In an image forming apparatus, a fixing fluid is applied to a toner image on an intermediary transfer belt by a coating roller, and the toner image in a swollen/softened state is fixed onto a recording medium. By a second seal member composed of a film-shaped member and a supporting member, a gap between the coating roller and a fixing fluid chamber which has the opening and places the coating roller therein is closed to avoid leakage of the fixing fluid.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Other and further objects, features, and advantages of the invention will be more explicit from the following detailed description taken with reference to the drawings wherein:

FIG. 1 is a sectional view schematically illustrating the constitution of an image forming apparatus according to a first embodiment of the invention;

FIG. 2 is an enlarged sectional view showing the structure of the main portion of the image forming apparatus 1 depicted in FIG. 1;

FIG. 3 is an enlarged sectional view showing the structure of the main portion of the image forming apparatus 1 depicted in FIG. 1;

FIG. 4 is a sectional view schematically illustrating how the fixing fluid is applied to a toner image formed on the intermediary transfer belt by the coating roller;

FIGS. 5A through 5C are views schematically illustrating the structure of the liquid level detecting section, in which FIG. 5A is a fragmentary longitudinal cross-sectional sectional view showing the coating roller, and FIGS. 5B and 5C are cross-sectional views showing the coating roller;

FIG. 6 is a sectional view schematically illustrating the constitution of an image forming apparatus according to a second embodiment or the invention;

FIG. 7 is a sectional view schematically illustrating the structure of the main portion of the image forming apparatus depicted in FIG. 6;

FIGS. 8A through 8C are views showing the behavior of a first seal member, in which FIGS. 8A and 8B are sectional views showing how a gap between a fixing fluid chamber and a coating roller is closed with the first seal member, and FIG. 8C is a sectional view of the coating roller illustrating the gap-closing operation using the first seal member depicted in FIGS. 8A and 8B;

FIG. 9 is a sectional view schematically illustrating the structure of a liquid level detecting section;

FIG. 10 is a sectional view schematically illustrating how the fixing fluid is applied to a toner image on a transferring and fixing roller by the coating roller;

FIG. 11 is a sectional view schematically illustrating the structure of the fixing fluid applying section according to a modified embodiment; and

FIGS. 12A and 12B are views schematically illustrating the structure of the contact and release operation section, in which FIG. 12A is a top view thereof and FIG. 12B is a sectional view thereof taken along the line XIIb-XIIb of FIG. 12A.

Claims

1. An image forming apparatus to form images by means of electrophotography or electrostatic recording, comprising: a toner image bearing section for bearing an unfixed toner image thereon; anda fixing fluid applying section for applying a fixing fluid which provides an effect of fixing toner onto a recording medium, to the unfixed toner image on the toner image bearing section,wherein the fixing fluid applying section includes:a fixing fluid chamber having an opening formed facing the toner image bearing section;an applying member formed into a roller shape and placed in an interior space of the fixing fluid chamber, for applying the fixing fluid to the unfixed toner image on the toner image bearing section in contact with the toner image bearing section, which is supported inside the fixing fluid chamber so as to be rotatable and moved to contact with and release from the toner image bearing section, and in which at least a certain part is projected outward through the opening of the fixing fluid chamber facing the toner image bearing section in spaced to a side wall of the fixing fluid chamber;a seal member for closing a gap between the opening of the fixing fluid chamber and the applying member; anda contact and release operation section for supporting the fixing fluid chamber so that the applying member moves to contact with and release from the toner image bearing section,wherein at least the fixing fluid chamber, the applying member, and the seal member are integral with one another as a single unit which is freely attachable to and detachable from a main body of the image forming apparatus.

2. The image forming apparatus of claim 1, wherein the fixing fluid chamber places the applying member and also stores the fixing fluid in its interior space, the applying member is provided as a first applying member which is supported inside the fixing fluid chamber so as to be rotatable and moved to contact with and release from the toner image bearing section, has at least its certain part projected outward through the opening of the fixing fluid chamber facing the toner image bearing section in spaced to a side wall of the fixing fluid chamber, has at least its certain part located vertically above a level of the fixing fluid within the fixing fluid chamber, and has a slant region formed at its axial end portion, a diameter of its cross-section in a direction perpendicular to the length of the first applying member of which is tapered from a position near the end portion to the end portion, andthe seal member is provided as a first seal member which is disposed so as to move to contact with and release from the applying member, and has an axial end portion which is brought into contact with the slant region of the applying member to close the gap between the opening of the fixing fluid chamber and the applying member.

3. The image forming apparatus of claim 2, wherein the fixing fluid applying section further comprises a cleaning member which is rotatably supported inside the fixing fluid chamber, makes contact with the first applying member, and is so arranged as to be kept clear of the fixing fluid within the fixing fluid chamber, and in which, at least a surface layer is made of a material which is larger in contact angle with water than the surface of the first applying member.

4. The image forming apparatus of claim 2, wherein the fixing fluid applying section further comprises: a deformable fixing fluid container having an opening placed inside the fixing fluid chamber, which is filled with the fixing fluid; andan application wick for supplying the fixing fluid within the fixing fluid container to the first applying member, in which one end is inserted through the opening into the fixing fluid container to dip with the fixing fluid, and the other end is arranged in pressure-contact with the first applying member.

5. The image forming apparatus of claim 2, wherein the fixing fluid applying section further includes: a liquid level detecting section for detecting an amount of the fixing fluid within the fixing fluid chamber; anda replacement timing indicating section for notifying of a timing of replacement of the fixing fluid applying section from a result detected by the liquid level detecting section.

6. The image forming apparatus of claim 5, wherein the liquid level detecting section includes: a hollow position control member having a plurality of through holes formed on its side wall that permit inflow and outflow of the fixing fluid, in which one end protrudes from a liquid level of the fixing fluid within the fixing fluid chamber into the interior space of the fixing fluid chamber, and the other end is supported on the fixing fluid chamber while being dipped in the fixing fluid;a first fixing-fluid level indicator member put in an interior space of the hollow position control member so as to float in the fixing fluid while moving up-and-down to change its vertical position depending upon increase and decrease of the fixing fluid;a first position detecting section for detecting a position of the first fixing-fluid level indicator member in its vertical direction; anda fixing-fluid amount calculation section for determining the amount of the fixing fluid by calculation from a result detected by the first position detecting section.

7. The image forming apparatus of claim 1, wherein the applying member is provided as a second applying member formed into a roller shape which is supported inside the fixing fluid chamber so as to be rotatable and moved to contact with and release from the toner image bearing section, with at least a certain part of which projected outward through the opening of the fixing fluid chamber facing the toner image bearing section in spaced to a side wall of the fixing fluid chamber, and in which is placed a fixing fluid storage chamber for storing therein the fixing fluid whereby to apply the fixing fluid within the fixing fluid storage chamber to the unfixed toner image on the toner image bearing section in contact with the toner image bearing section, and the seal member is provided as a second seal member for closing the gap between the opening of the fixing fluid chamber and the applying member, which is composed of a film-shaped member formed at a distance from or in intimate contact with the surface of a part of the applying member which is placed in the fixing fluid chamber and a supporting member for supporting the film-shaped member that is disposed in contact with both side of the opening in longitudinal direction of the fixing fluid chamber and with a part of the surface of the applying member in the vicinity of the both side of the opening.

8. The image forming apparatus of claim 7, wherein the second applying member includes: a second fixing-fluid level indicator member which is supported inside the fixing fluid storage chamber so as to be rotatable about the axis of the second applying member depending upon increase and decrease of the fixing fluid;a second position detecting section for detecting a position of the second fixing-fluid level indicator member; andfixing-fluid amount calculation section for determining the amount of the fixing fluid by calculation from a result detected by the second position detecting section.

9. The image forming apparatus of claim 1, wherein the fixing fluid chambers is designed as a vessel member including a flat-shaped portion which is a bottom face when mounted in the image forming apparatus, and a lateral side constituted by a surface having a curvature.