Image forming apparatus and its control method

An image forming apparatus for forming an image on a recording medium includes a print head having ink-discharge surfaces having the ink-discharge openings therein; a cylindrical cleaning roller composed of an elastic material; moving means for moving the cleaning roller and the print head relative to each other while keeping the circumferential surface of the cleaning roller in contact with the ink-discharge surfaces; drive control means for controlling the moving means; a head cap for protecting the ink-discharge surfaces; cap opening/closing means for opening and closing the head cap. When the head cap is opened by the cap opening/closing means, by driving the moving means with control of the drive control means so as to move the cleaning roller relative to the print head while keeping the circumferential surface of the cleaning roller in contact with the ink-discharge surfaces, ink in the ink-discharge openings is sucked.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image forming apparatus for forming an image on a recording medium by discharging ink from ink discharge openings and also to its control method.

2. Description of the Related Art

An inkjet-type image forming apparatus, for example, an inkjet printer, has been widely used because of its advantages such as a low operating cost, easy colorization of a print image, and easy miniaturization of the apparatus. The inkjet printer is designed to form an image by discharging a minute amount of ink from each of fine ink discharge openings formed in corresponding ink-discharge surfaces of a print head. Unless the printer has continued a printing operation for a long time interval and hence has discharged ink from the ink discharge openings of the print head for that time interval, ink discharged during the last printing operation and accreted in the ink-discharge openings and the vicinities thereof of the ink-discharge surfaces may evaporate into high viscosity or solidification, thereby blocking ink from being discharged normally.

On this account, in the known inkjet printer, the print head is cleaned by pressing a blade made from a slightly hard rubber or the like onto the ink-discharge surfaces of the print head and by sliding the blade across the ink-discharge surfaces so as to remove (i.e., to wipe out) ink accreted on the ink-discharge surfaces with the ink having a high viscosity or been solidified. In association with this, Japanese Unexamined Patent Application Publication No. 57-34969 has disclosed a technique in which a plurality of blades are fixed to a rotating shaft and a wiping effect is improved by rotating the blades.

However, since ink accreted on the ink-discharge surfaces is wiped by pressing the blade made from a slightly hard rubber or the like onto the ink-discharge surfaces of the print head and by sliding the blade across the ink-discharge surfaces in such a known related art, a large force is exerted on the ink-discharge surfaces by the blade, thereby sometimes resulting in damaging the ink-discharge surfaces.

Also, when the above blade is used, it is expected to perform its duty depending on only its wiping effect; however, its wiping operation is not enough to solve a problem in that ink sometimes remains in the ink-discharge openings and the vicinities thereof. Even when the plurality of blades are used, the ink-discharge surfaces are sometimes damaged and also ink sometimes remains in the ink-discharge openings and the vicinities thereof in a similar fashion to the former case.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide an image forming apparatus in which, when a cap member for protecting ink-discharge surfaces is opened or closed by cap opening/closing means, by moving a cleaning member relative to a print head while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces, and also it is another object of the present invention to provide a control method of an image forming apparatus.

In order to achieve the above objects, the present invention has been made.

An image forming apparatus according to the present invention is equipped with a print head including ink-discharge surfaces having ink-discharge openings formed therein; a cylindrical cleaning member composed of an elastic material; moving means for moving the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head; drive control means for controlling the moving means; a cap member for protecting the ink-discharge surfaces of the print head; and cap opening/closing means for opening and closing the cap member. When the cap member is opened by the cap opening/closing means, by driving the moving means with control of the drive control means so as to move the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces, ink in the ink-discharge openings is sucked.

With this structure, when the cap member is opened by the cap opening/closing means, by driving the moving means with control of the drive control means so as to move the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head, due to the elastic deformation of the cleaning member during the moving, ink in the ink-discharge openings is sucked and removed. Thus, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces of the print head.

Also, an image forming apparatus according to the present invention is provided with a print head including ink-discharge surfaces having ink-discharge openings formed therein; a cylindrical cleaning member composed of an elastic material; moving means for moving the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head; drive control means for controlling the moving means; discharge control means for controlling an discharge operation of ink from the ink-discharge openings formed in the discharge surfaces; a cap member for protecting the ink-discharge surfaces of the print head; and cap opening/closing means for opening and closing the cap member. When the cap member is opened by the cap opening/closing means, by driving the moving means with control of the drive control means so as to move the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces, ink in the ink-discharge openings is sucked, and after the moving of the cleaning member on the ink-discharge surfaces, ink is preliminarily discharged from the ink-discharge openings with control of the discharge control means.

With this structure, when the cap member is opened by the cap opening/closing means, by driving the moving means with control of the drive control means so as to move the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head, due to the elastic deformation of the cleaning member during the moving, ink in the ink-discharge openings is sucked, and after the moving of the cleaning member on the ink-discharge surfaces, ink is preliminarily discharged from the ink-discharge openings with control of the discharge control means. Thus, due to the absorption of ink in the ink-discharge openings and the subsequent preliminary discharge of ink, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces of the print head.

Also, an image forming apparatus according to the present invention is provided with a print head including ink-discharge surfaces having ink-discharge openings formed therein; a cylindrical cleaning member composed of an elastic material; moving means for moving the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head; drive control means for controlling the moving means; discharge control means for controlling an discharge operation of ink from the ink-discharge openings formed in the discharge surfaces; a cap member for protecting the ink-discharge surfaces of the print head; and cap opening/closing means for opening and closing the cap member. When the cap member is opened by the cap opening/closing means, by performing a discharge operation of ink from the ink-discharge openings with control of the discharge control means, ink is preliminarily discharged from the ink-discharge openings.

With this structure, when the cap member is opened by the cap opening/closing means, by performing a discharge operation of ink from the ink-discharge openings with control of the discharge control means, ink is preliminarily discharged from the ink-discharge openings. Thus, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces of the print head.

Also, an image forming apparatus according to the present invention is provided with a print head including ink-discharge surfaces having ink-discharge openings formed therein; a cylindrical cleaning member composed of an elastic material; a cap member for housing the cleaning member therein and for protecting the ink-discharge surfaces of the print head; cap opening/closing means for opening and closing the cap member and for moving the cleaning member and the print head relative to each other in accordance with the opening operation of the cap member while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head; and drive control means for controlling the cap opening/closing means. When the cap member is opened by the cap opening/closing means, by driving the cap opening/closing means with control of the drive control means so as to move the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces, ink in the ink-discharge openings is sucked.

With this structure, when the cap member is opened by the cap opening/closing means, by driving the cap opening/closing means with control of the drive control means so as to move the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head, due to the elastic deformation of the cleaning member during the moving, ink in the ink-discharge openings is sucked and removed. Thus, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces of the print head.

Also, an image forming apparatus according to the present invention is provided with a print head including ink-discharge surfaces having ink-discharge openings formed therein; a cylindrical cleaning member composed of an elastic material; a cap member for housing the cleaning member therein and for protecting the ink-discharge surfaces of the print head; cap opening/closing means for opening and closing the cap member and for moving the cleaning member and the print head relative to each other in accordance with the opening operation of the cap member while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head; drive control means for controlling the cap opening/closing means; and discharge control means for controlling an discharge operation of ink from the ink-discharge openings formed in the discharge surfaces. When the cap member is opened by the cap opening/closing means, by driving the cap opening/closing means with control of the drive control means so as to move the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces, ink in the ink-discharge openings is sucked, and after the moving of the cleaning member on the ink-discharge surfaces, ink is preliminarily discharged from the ink-discharge openings with control of the discharge control means.

With this structure, when the cap member is opened by the cap opening/closing means, by driving the cap opening/closing means with control of the drive control means so as to move the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head, due to the elastic deformation of the cleaning member during the moving, ink in the ink-discharge openings is sucked, and after the moving of the cleaning member on the ink-discharge surfaces, ink is preliminarily discharged from the ink-discharge openings with control of the discharge control means. Thus, due to the absorption of ink in the ink-discharge openings and the subsequent preliminary discharge of ink, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces of the print head.

Also, an image forming apparatus according to the present invention is provided with a print head including ink-discharge surfaces having ink-discharge openings formed therein; a cylindrical cleaning member composed of an elastic material; a cap member for housing the cleaning member therein and for protecting the ink-discharge surfaces of the print head; cap opening/closing means for opening and closing the cap member and for moving the cleaning member and the print head relative to each other in accordance with the opening operation of the cap member while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head; drive control means for controlling the cap opening/closing means; and discharge control means for controlling an discharge operation of ink from the ink-discharge openings formed in the discharge surfaces. When the cap member is opened by the cap opening/closing means, by performing a discharge operation of ink from the ink-discharge openings with control of the discharge control means, ink is preliminarily discharged from the ink-discharge openings.

With this structure, when the cap member is opened by the cap opening/closing means, by performing a discharge operation of ink from the ink-discharge openings with control of the discharge control means, ink is preliminarily discharged from the ink-discharge openings. Thus, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces of the print head.

Also, an image forming apparatus according to the present invention is provided with a print head including ink-discharge surfaces having a plurality of rows of the ink-discharge openings formed therein for a corresponding plurality of colors; a cylindrical cleaning member composed of an elastic material; a cap member for housing the cleaning member therein and for protecting the ink-discharge surfaces of the print head; cap opening/closing means for opening and closing the cap member and for moving the cleaning member and the print head relative to each other in the direction orthogonal to the plurality of rows of the ink-discharge openings for the respective colors in accordance with the opening operation of the cap member while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head; drive control means for controlling the cap opening/closing means; and discharge control means for controlling an discharge operation of ink from the ink-discharge openings formed in the discharge surfaces. When the cap member is opened by the cap opening/closing means, by driving the cap opening/closing means with control of the drive control means so as to move the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces, ink in the ink-discharge openings is sucked, and in the order of the rows, over which the cleaning member passes with control of the discharge control means, of the ink-discharge openings for the corresponding colors formed in the ink-discharge surfaces, ink is preliminarily discharged from the ink-discharge openings with control of the discharge control means.

With this structure, when the cap member is opened by the cap opening/closing means, by driving the cap opening/closing means with control of the drive control means so as to open the cap member for housing the cylindrical cleaning member therein composed of an elastic material and for protecting the ink-discharge surfaces of the print head and also to move the cleaning member and the print head relative to each other in the direction orthogonal to the plurality of rows of the ink-discharge openings for the respective colors in accordance with the opening operation of the cap member while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head, ink in the ink-discharge openings is sucked due to the elastic deformation of the cleaning member during the moving, and ink is preliminarily discharged from the ink-discharge openings with control of the discharge control means in the order of the rows, over which the cleaning member passes with control of the discharge control means, of the ink-discharge surfaces for the respective colors. Thus, due to the absorption of ink in the ink-discharge openings and the subsequent preliminary discharge of ink, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces of the print head.

An image forming apparatus according to the present invention is provided with a print head including ink-discharge surfaces having ink-discharge openings formed therein; a cylindrical cleaning member composed of an elastic material; moving means for moving the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head; drive control means for controlling the moving means; a cap member for protecting the ink-discharge surfaces of the print head; and cap opening/closing means for opening and closing the cap member. When the cap member is closed by the cap opening/closing means, by driving the moving means with control of the drive control means so as to move the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces, ink in the ink-discharge openings is sucked.

With this structure, when the cap member is closed by the cap opening/closing means, by driving the moving means with control of the drive control means so as to move the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head, ink in the ink-discharge openings is sucked and removed due to the elastic deformation of the cleaning member during the moving. Thus, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces of the print head.

Also, an image forming apparatus according to the present invention is provided with a print head including ink-discharge surfaces having ink-discharge openings formed therein; a cylindrical cleaning member composed of an elastic material; moving means for moving the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head; drive control means for controlling the moving means; discharge control means for controlling an discharge operation of ink from the ink-discharge openings formed in the discharge surfaces; a cap member for protecting the ink-discharge surfaces of the print head; and cap opening/closing means for opening and closing the cap member. When the cap member is closed by the cap opening/closing means, by driving the moving means with control of the drive control means so as to move the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces, ink in the ink-discharge openings is sucked, and after the moving of the cleaning member on the ink-discharge surfaces, ink is preliminarily discharged from the ink-discharge openings with control of the discharge control means.

With this structure, when the cap member is closed by the cap opening/closing means, by driving the moving means with control of the drive control means so as to move the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head, ink in the ink-discharge openings is sucked due to the elastic deformation of the cleaning member during the moving, and after the moving of the cleaning member on the ink-discharge surfaces, ink is preliminarily discharged from the ink-discharge openings with control of the discharge control means. Thus, due to the absorption of ink in the ink-discharge openings and the subsequent preliminary discharge of ink, the ink-discharge openings and the vicinities thereof are cleaned without damaging the ink-discharge surfaces of the print head.

Also, an image forming apparatus according to the present invention is provided with a print head including ink-discharge surfaces having ink-discharge openings formed therein; a cylindrical cleaning member composed of an elastic material; moving means for moving the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head; drive control means for controlling the moving means; discharge control means for controlling an discharge operation of ink from the ink-discharge openings formed in the discharge surfaces; a cap member for protecting the ink-discharge surfaces of the print head; and cap opening/closing means for opening and closing the cap member. When the cap member is closed by the cap opening/closing means, by performing a discharge operation of ink from the ink-discharge openings with control of the discharge control means, ink is preliminarily discharged from the ink-discharge openings.

With this structure, when the cap member is closed by the cap opening/closing means, by performing a discharge operation of ink from the ink-discharge openings with control of the discharge control means, ink is preliminarily discharged from the ink-discharge openings. Thus, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces of the print head.

Also, an image forming apparatus according to the present invention is provided with a print head including ink-discharge surfaces having ink-discharge openings formed therein; a cylindrical cleaning member composed of an elastic material; a cap member for housing the cleaning member therein and for protecting the ink-discharge surfaces of the print head; cap opening/closing means for opening and closing the cap member and for moving the cleaning member and the print head relative to each other in accordance with the closing operation of the cap member while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head; and drive control means for controlling the cap opening/closing means. When the cap member is closed by the cap opening/closing means, by driving the cap opening/closing means with control of the drive control means so as to move the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces, ink in the ink-discharge openings is sucked.

With this structure, when the cap member is closed by the cap opening/closing means, by driving the cap opening/closing means with control of the drive control means so as to move the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head, ink in the ink-discharge openings is sucked and removed due to the elastic deformation of the cleaning member during the moving. Thus, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces of the print head.

Also, an image forming apparatus according to the present invention is provided with a print head including ink-discharge surfaces having ink-discharge openings formed therein; a cylindrical cleaning member composed of an elastic material; a cap member for housing the cleaning member therein and for protecting the ink-discharge surfaces of the print head; cap opening/closing means for opening and closing the cap member and for moving the cleaning member and the print head relative to each other in accordance with the closing operation of the cap member while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head; drive control means for controlling the cap opening/closing means; and discharge control means for controlling an discharge operation of ink from the ink-discharge openings formed in the discharge surfaces. When the cap member is closed by the cap opening/closing means, by driving the cap opening/closing means with control of the drive control means so as to move the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces, ink in the ink-discharge openings is sucked, and after the moving of the cleaning member on the ink-discharge surfaces, ink is preliminarily discharged from the ink-discharge openings with control of the discharge control means.

With this structure, when the cap member is closed by the cap opening/closing means, by driving the cap opening/closing means with control of the drive control means so as to move the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head, ink in the ink-discharge openings is sucked due to the elastic deformation of the cleaning member during the moving, and after the moving of the cleaning member on the ink-discharge surfaces, ink is preliminarily discharged from the ink-discharge openings with control of the discharge control means. Thus, due to the absorption of ink in the ink-discharge openings and the subsequent preliminary discharge of ink, the ink-discharge openings and the vicinities thereof are cleaned without damaging the ink-discharge surfaces of the print head.

Also, an image forming apparatus according to the present invention is provided with a print head including ink-discharge surfaces having ink-discharge openings formed therein; a cylindrical cleaning member composed of an elastic material; a cap member for housing the cleaning member therein and for protecting the ink-discharge surfaces of the print head; cap opening/closing means for opening and closing the cap member and for moving the cleaning member and the print head relative to each other in accordance with the closing operation of the cap member while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head; drive control means for controlling the cap opening/closing means; and discharge control means for controlling an discharge operation of ink from the ink-discharge openings formed in the discharge surfaces. When the cap member is closed by the cap opening/closing means, by performing a discharge operation of ink from the ink-discharge openings with control of the discharge control means, ink is preliminarily discharged from the ink-discharge openings.

With this structure, when the cap member is closed by the cap opening/closing means, by performing a discharge operation of ink from the ink-discharge openings with control of the discharge control means, ink is preliminarily discharged from the ink-discharge openings. Thus, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces of the print head.

Also, an image forming apparatus according to the present invention is provided with a print head including ink-discharge surfaces having a plurality of rows of the ink-discharge openings formed therein for a corresponding plurality of colors; a cylindrical cleaning member composed of an elastic material; a cap member for housing the cleaning member therein and for protecting the ink-discharge surfaces of the print head; cap opening/closing means for opening and closing the cap member and for moving the cleaning member and the print head relative to each other in the direction orthogonal to the plurality of rows of the ink-discharge openings for the respective colors in accordance with the closing operation of the cap member while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head; drive control means for controlling the cap opening/closing means; and discharge control means for controlling an discharge operation of ink from the ink-discharge openings formed in the discharge surfaces. When the cap member is closed by the cap opening/closing means, by driving the cap opening/closing means with control of the drive control means so as to move the cleaning member and the print head relative to each other while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces, ink in the ink-discharge openings is sucked, and in the order of the rows, over which the cleaning member passes with control of the discharge control means, of the ink-discharge openings for the corresponding colors formed in the ink-discharge surfaces, ink is preliminarily discharged from the ink-discharge openings with control of the discharge control means.

With this structure, when the cap member is closed by the cap opening/closing means, by driving the cap opening/closing means with control of the drive control means so as to close the cap member for housing the cylindrical cleaning member therein composed of an elastic material and for protecting the ink-discharge surfaces of the print head and to move the cap member and the print head relative to each other in the direction orthogonal to the plurality of rows of the ink-discharge openings for the respective colors in accordance with the closing operation of the cap member while keeping the circumferential surface of the cleaning member in contact with the ink-discharge surfaces of the print head, ink in the ink-discharge openings is sucked due to the elastic deformation of the cleaning member during the moving, and ink is preliminarily discharged from the ink-discharge openings with control of the discharge control means in the order of the rows, over which the cleaning member passes with control of the discharge control means, of the ink-discharge surfaces for the respective colors. Thus, due to the absorption of ink in the ink-discharge openings and the subsequent preliminary discharge of ink, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces of the print head.

Also, A control method of an image forming apparatus according to the present invention includes the step of controlling the image forming apparatus such that, when a cap member is opened by cap opening/closing means, by driving moving means with control of drive control means so as to move a cylindrical cleaning member composed of an elastic material while keeping the circumferential surface of the cleaning member in contact with ink-discharge surfaces of a print head, having ink-discharge openings formed therein, ink in the ink-discharge openings is sucked.

Thus, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces of the print head.

Also, A control method of an image forming apparatus according to the present invention includes the step of controlling the image forming apparatus such that, when a cap member is opened by cap opening/closing means, by driving moving means with control of drive control means so as to move a cylindrical cleaning member composed of an elastic material while keeping the circumferential surface of the cleaning member in contact with ink-discharge surfaces of a print head, having ink-discharge openings formed therein, ink in the ink-discharge openings is sucked, and after the moving of the cleaning member on the ink-discharge surfaces, ink is preliminarily discharged from the ink-discharge openings with control of discharge control means.

Thus, the ink-discharge openings and the vicinities thereof can be effectively cleaned without damaging the ink-discharge surfaces of the print head due to the absorption of ink in the ink-discharge openings and the subsequent preliminary discharge of ink.

Also, A control method of an image forming apparatus according to the present invention includes the step of controlling the image forming apparatus such that, when a cap member is opened by cap opening/closing means, by performing a discharge operation of ink from ink-discharge openings formed in ink-discharge surfaces of a print head with control of discharge control means, ink is preliminarily discharged from the ink-discharge openings.

Thus, the ink-discharge openings and the vicinities thereof can be effectively cleaned without damaging the ink-discharge surfaces of the print head.

Also, A control method of an image forming apparatus according to the present invention includes the step of controlling the image forming apparatus such that, when a cap member is opened by cap opening/closing means, by driving the cap opening/closing means with control of drive control means so as to move a cylindrical cleaning member composed of an elastic material while keeping the circumferential surface of the cleaning member in contact with ink-discharge surfaces of a print head, having ink-discharge openings formed therein, ink in the ink-discharge openings is sucked.

Thus, the ink-discharge openings and the vicinities thereof can be effectively cleaned without damaging the ink-discharge surfaces of the print head.

Also, A control method of an image forming apparatus according to the present invention includes the step of controlling the image forming apparatus such that, when a cap member is opened by cap opening/closing means, by driving the cap opening/closing means with control of drive control means so as to move a cylindrical cleaning member composed of an elastic material while keeping the circumferential surface of the cleaning member in contact with ink-discharge surfaces of a print head, having ink-discharge openings formed therein, ink in the ink-discharge openings is sucked, and after the moving of the cleaning member on the ink-discharge surfaces with control of discharge control means, ink is preliminarily discharged from the ink-discharge openings.

Thus, due to the absorption of ink in the ink-discharge openings and the subsequent preliminary discharge of ink, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces of the print head.

Also, A control method of an image forming apparatus according to the present invention includes the step of controlling the image forming apparatus such that, when a cap member is opened by cap opening/closing means, by performing a discharge operation of ink from ink-discharge openings formed in ink-discharge surfaces of a print head with control of discharge control means, ink is preliminarily discharged from the ink-discharge openings.

Thus, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces of the print head of the print head.

Also, A control method of an image forming apparatus according to the present invention includes the step of controlling the image forming apparatus such that, when a cap member is opened by cap opening/closing means, by driving the cap opening/closing means with control of drive control means so as to move a cleaning member composed of an elastic material while keeping the circumferential surface of the cleaning member in contact with ink-discharge surfaces of a print head, having a plurality of rows of ink-discharge openings formed therein for a corresponding plurality of colors, ink in the ink-discharge openings is sucked, and in the order of the rows, over which the cleaning member passes with control of discharge control means, of the ink-discharge openings for the respective colors formed in the ink-discharge surfaces, ink is preliminarily discharged from the ink-discharge openings.

Thus, due to the absorption of ink in the ink-discharge openings and the subsequent preliminary discharge of ink, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces of the print head.

Also, A control method of an image forming apparatus according to the present invention includes the step of controlling the image forming apparatus such that, when a cap member is closed by cap opening/closing means, by driving moving means with control of drive control means so as to move a cylindrical cleaning member composed of an elastic material while keeping the circumferential surface of the cleaning member in contact with ink-discharge surfaces of a print head, having ink-discharge openings formed therein, ink in the ink-discharge openings is sucked.

Thus, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces of the print head.

Also, A control method of an image forming apparatus according to the present invention includes the step of controlling the image forming apparatus such that, when a cap member is closed by cap opening/closing means, by driving moving means with control of drive control means so as to move a cylindrical cleaning member composed of an elastic material while keeping the circumferential surface of the cleaning member in contact with ink-discharge surfaces of a print head, having ink-discharge openings formed therein, ink in the ink-discharge openings is sucked, and after the moving of the cleaning member on the ink-discharge surfaces with control of discharge control means, ink is preliminarily discharged from the ink-discharge openings.

Thus, due to the absorption of ink in the ink-discharge openings and the subsequent preliminary discharge of ink, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces of the print head.

Also, A control method of an image forming apparatus according to the present invention includes the step of controlling the image forming apparatus such that, when the cap member is closed by cap opening/closing means, by performing a discharge operation of ink from ink-discharge openings formed in ink-discharge surfaces of a print head with control of discharge control means, ink is preliminarily discharged from the ink-discharge openings.

Thus, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces of the print head.

Also, A control method of an image forming apparatus according to the present invention includes the step of controlling the image forming apparatus such that, when a cap member is closed by cap opening/closing means, by driving the cap opening/closing means with control of drive control means so as to move a cylindrical cleaning member composed of an elastic material while keeping the circumferential surface of the cleaning member in contact with ink-discharge surfaces of a print head, having ink-discharge openings formed therein, ink in the ink-discharge openings is sucked.

Thus, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces of the print head.

Also, A control method of an image forming apparatus according to the present invention includes the step of controlling the image forming apparatus such that, when a cap member is closed by cap opening/closing means, by driving the cap opening/closing means with control of drive control means so as to move a cylindrical cleaning member composed of an elastic material while keeping the circumferential surface of the cleaning member in contact with ink-discharge surfaces of a print head, having ink-discharge openings formed therein, ink in the ink-discharge openings is sucked, and after the moving of the cleaning member on the ink-discharge surfaces with control of discharge control means, ink is preliminarily discharged from the ink-discharge openings.

Thus, due to the absorption of ink in the ink-discharge openings and the subsequent preliminary discharge of ink, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces of the print head.

Also, A control method of an image forming apparatus according to the present invention includes the step of controlling the image forming apparatus such that, when a cap member is closed by cap opening/closing means, by performing a discharge operation of ink from ink-discharge openings formed in ink-discharge surfaces of a print head with control of discharge control means, ink is preliminarily discharged from the ink-discharge openings.

Thus, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces of the print head.

Also, A control method of an image forming apparatus according to the present invention includes the step of controlling the image forming apparatus such that, when a cap member is closed by cap opening/closing means, by driving the cap opening/closing means with control of drive control means so as to move a cleaning member composed of an elastic material while keeping the circumferential surface of the cleaning member in contact with ink-discharge surfaces of a print head, having a plurality of rows of ink-discharge openings formed therein for a corresponding plurality of colors, ink in the ink-discharge openings is sucked, and in the order of the rows, over which the cleaning member passes with control of discharge control means, of the ink-discharge openings for the respective colors formed in the ink-discharge surfaces, ink is preliminarily discharged from the ink-discharge openings.

Thus, due to the absorption of ink in the ink-discharge openings and the subsequent preliminary discharge of ink, the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces of the print head.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1is a perspective view of an image forming apparatus, taking an inkjet printer for example, according to an embodiment of the present invention. The ink-jet printer is of a type in which an inkjet head1is removal and is directly mounted in a main body2of the printer. Also, the inkjet printer has a structure in which the ink-jet head1is inserted in the direction of the arrow H indicated in the drawing and fixedly set in the main body2of the printer.

The inkjet head1is intended to finely particularize liquid ink by, for example, an electrothermal transducing method or an electromechanical transducing method and to discharge it so as to form ink dots on a recording sheet (a recording medium), and, as shown inFIGS. 1 and 2, has an ink cartridge3, a print head4, and a head cap5.

The ink cartridge3is intended to contain ink for a single color or a plurality of colors, and has a case having a long slender shape and extending along the width direction of the main body2of the printer shown inFIG. 1, that is, extending through the overall width of a recording sheet along the width direction thereof. Although not shown in the drawing, the above-mentioned case has, for example, four separate ink chambers therein for containing ink for four colors, namely, yellow Y, magenta M, cyan C, and black K. The ink cartridge3is composed of a hard resin or the like.

As shown inFIG. 2which is a magnified transverse sectional view of the inkjet head1shown inFIG. 1, the ink cartridge3has the print head4disposed on the bottom surface thereof. The print head4is intended to finely particulate ink fed from the ink cartridge3and to discharge it, and has ink-discharge surfaces6having fine ink-discharge openings perforated therein along the longitudinal direction of the ink cartridge3so as to correspond to the overall width of a recording sheet.

Each of the ink-discharge surfaces6is composed of, for example, nickel and material including nickel and is formed by nickel-electroforming so as to have a thin sheet-like shape. The ink-discharge surfaces6extend in the longitudinal direction of the ink cartridge3and have four rows of the ink-discharge openings formed therein for corresponding four colors of yellow Y, magenta M, cyan C, and black K so as to provide a four-color integrated line scan head.

Although not shown in the drawing, the ink-discharge surfaces6have portions having the rows of ink-discharge openings formed therein for the respective Y, M, C, and K colors and have other portions, each pair of the other portions having the corresponding row of ink-discharge openings sandwiched therebetween, having projections covering head electrodes with resin formed thereon such that these two types of portions are formed so as to provide an undulating surface.

The ink cartridge3has the head cap5fixed on the bottom surface side thereof. The head cap5has a cleaning roller7housed therein, which will be described later, and serves as a cap member for covering the ink-discharge surfaces6of the print head4so as to prevent the ink-discharge openings from drying and clogging. Also, the head cap5has a long slender shape having the same length as that of the case of the ink cartridge3; has a shallow box-like shape with an open top; and is mounted so as to be movable relative to and detachable from the print head4.

The head cap5is moved by moving means such as a motor or the like in the directions of the arrows A and B indicated in the drawing, which are orthogonal to the longitudinal direction of the ink-discharge surfaces6of the print head4; is removed from the ink cartridge3while being moved in the direction of the arrow A; and is mounted again on the ink cartridge3while being returned in the direction of the arrow B. The head cap5is composed of a hard resin or the like.

The head cap5has the cleaning roller7disposed therein.

The cleaning roller7serves as a cleaning member for cleaning the ink-discharge surfaces6of the print head4. The cleaning roller7having a cylindrical shape is composed of an elastic material; is fixed in the head cap5along one of the side surfaces and in the longitudinal direction of the of the head cap5; and accordingly lies parallel to the longitudinal direction of the ink-discharge surfaces6of the print head4. Thus, the cleaning roller7moves together with the head cap5in the direction of the arrow A so as to clean the ink-discharge surfaces6of the print head4.

The head cap5also has an ink receiver8disposed therein. The ink receiver8is intended to receive ink preliminarily discharged from the ink-discharge openings of the print head4on a part of the bottom or the entire bottom of the shallow box-shaped head cap5.

Referring now toFIGS. 3to5, operative examples of the head cap5and the cleaning roller7will be described. In the state shown inFIG. 4, first, the head cap5is formed so as to have a long slender shape in concert with the width and the length of the ink cartridge3shown inFIG. 1, and as shown inFIG. 3, also to have a shallow box-like shape having a bottom, side walls standing along the entire circumference thereof, and an open top.

As previously mentioned, the head cap5moves in the directions of the arrows A and B which are orthogonal to the longitudinal direction of the ink-discharge surfaces6of the print head4. As means for positioning the head cap5when it is mounted again on the ink cartridge3while being returned in the direction of the arrow B, the head cap5has a positioning claw12disposed at the top end of the side wall thereof on the opposite side of the cleaning roller7, as shown in FIG.3. The positioning claw12is retained at the under edge of the ink cartridge3so that the head cap5is positioned.

In the vicinity of one side wall of the head cap5lying close to the print head4and along the longitudinal direction of the head cap5, the cylindrical cleaning roller7lying in contact with the ink-discharge surfaces6of the print head4across its overall length is removably held. More particularly, as shown inFIG. 4, the cleaning roller7has a pair of pins9disposed in a protruding manner at both ends thereof, and these pins9are held by a pair of respective holding members10having an approximate U-shape, as shown in FIG.3.

Each holding member10has a pin-receiving portion at the top thereof which can be elastically opened and closed. By pressing down the pins9into the corresponding pin-receiving portions, the pin-receiving portions are opened and the pins9are thus received. Then, the pin-receiving portions are closed and the pins9are hence held. On the other hand, by lifting up the pins9, the pin-receiving portions are opened so that the pins9can be removed.

Meanwhile, the cylindrical cleaning roller7has a so-called crown shape which becomes gradually thicker toward its central part in the longitudinal direction thereof, as shown inFIGS. 4 and 5. With this crown shape, the cleaning roller7is prevented from coming out of contact with the ink-discharge surfaces6caused by the downward deformation, which would otherwise occur, of the central part of the cleaning roller7with respect to the longitudinal direction thereof.

A portion of the cleaning roller7lying in contact with the ink-discharge surfaces6is composed of an elastic material such as rubber. In other words, while the core portion of the cleaning roller7is composed of, for example, metal or a hard resin, the cylindrical surface portion outside the core portion is composed of an elastic member such as rubber. The cleaning roller7may be entirely composed of an elastic member such as rubber.

As shown inFIG. 3, a pair of floating springs11are disposed at portions of the head cap5for holding the cleaning roller7to the head cap5. The floating springs11serve as means for urging the cleaning roller7toward the ink-discharge surfaces6of the print head4, each spring made from a leaf spring having, for example, an approximate U-shape in side view, and are inserted in the vicinities of the corresponding holding members10and below the corresponding pin9. Thus, since the urging forces of the floating springs11are exerted on the corresponding pins9at both ends of the cleaning roller7, the cleaning roller7is pressed against the ink-discharge surfaces6of the print head4with an almost uniform pressure.

With this structure, as shown inFIG. 2, with the head cap5being fixed on the bottom surface side of the ink cartridge3, the urging forces of the floating springs11and the elastic force and the crown shape of the cleaning roller7cause the cleaning roller7to remain in contact with the ink-discharge surfaces6of the print head4across its overall length. The floating springs11are not limited to a leaf spring having an approximate U-shape; alternatively, they may be made from a coil spring.

Also, the cleaning roller7rolls due to its contact with the ink-discharge surfaces6of the print head4. Hence, as shown inFIG. 2, when the head cap5moves in the direction of the arrow A, the cleaning roller7rolls in close contact with the ink-discharge surfaces6of the print head4through its length with an appropriate pressure and thus removes ink accreted on the ink-discharge surfaces6due to its rolling movement.

Referring now toFIGS. 6Ato6C, a cleaning operation of the cleaning roller7for the ink-discharge surfaces6of the print head4will be described.FIGS. 6Ato6C are sectional views in which one of the ink-discharge surfaces6, one of ink-discharge openings13, and the cleaning roller7are magnified for easy explanation. First, it is assumed in the states shown inFIGS. 6Ato6C that the cleaning roller7rolls in the direction of the arrow C indicated in the drawing due to its contact with the ink-discharge surfaces6while moving together with the head cap5shown inFIG. 2in the direction of the arrow A, and that the cleaning roller7is to pass over one of the rows of the ink-discharge openings13formed in the ink-discharge surfaces6of the print head4shown in FIG.2.

FIG. 6Aillustrates a state in which the cleaning roller7moving in the direction of the arrow A while rolling in the direction of the arrow C is close to the row of the ink-discharge openings13. In this state, each ink-discharge opening13is filled with ink15from an ink chamber14, and a meniscus16having a concave curve is formed in the ink-discharge opening13due to the surface tension of the ink15.

As shown inFIG. 6A, when moving in the direction of the arrow A while rolling in the direction of the arrow C, the cleaning roller7blocks the ink-discharge opening13beginning from its one edge toward its other edge, and in the meantime, air in the ink-discharge opening13is pushed out through the gap at the other edge as indicated by the arrow D.

Next, as shown inFIG. 6B, moving further in the direction of the arrow A while rolling in the direction of the arrow C and when arriving just at the ink-discharge opening13, the cleaning roller7completely blocks the ink-discharge opening13.

In this state, since the cleaning roller7is pressed against and lies in contact with the ink-discharge surfaces6, microscopically, a part of the surface of the cleaning roller7lying between the one edge and the other edge of the ink-discharge opening13intrudes into the ink-discharge opening13a slight amount due to its elasticity; accordingly, with air in the ink-discharge opening13being pushed out just by that much, the cleaning roller7blocks the entrance of the ink-discharge opening13and hermetically seals the inside space thereof.

Then, as shown inFIG. 6C, the cleaning roller7moves further in the direction of the arrow A while rolling in the direction of the arrow C and opens the one edge of the ink-discharge opening13with the other edge being blocked. In this state, microscopically, when the part of the surface of the cleaning roller7intruding into the ink-discharge opening13a slight amount detaches from the one edge of the ink-discharge openings13, air hermetically sealed in the ink-discharge opening13is sucked and flows out through a gap of the one edge as indicated by the arrow E.

More particularly, due to a change in pressure in the ink-discharge opening13from a state (a positive pressure state) in which a slight amount of air in the ink-discharge opening13is pushed out and the remaining air is hermetically sealed as shown inFIG. 6Bto another state (a negative pressure state) in which the air in the ink-discharge opening13is sucked as shown inFIG. 6C, the ink in the ink-discharge openings13is sucked. With this arrangement, in the state shown inFIG. 2, a sucking force is exerted on ink remaining in the ink-discharge openings13so as to withdraw the ink out from the print head4, whereby the ink remaining in the ink-discharge openings13is sucked and reliably removed.

In this case, since the cylindrical cleaning roller7composed of an elastic material such as rubber moves on the ink-discharge surfaces6, the ink-discharge surfaces6can be cleaned without damaging a resin protective layer covering the head electrodes of the ink-discharge surfaces6.

Although, in the above description, the cleaning roller7rolls due to its contact with the ink-discharge surfaces6of the print head4, it may be fixed so as not to roll while being kept in contact with the ink-discharge surfaces6.

For example, in the state shown inFIG. 3, when the two pins9are formed at both ends of the cleaning roller7so as to extend vertically and are inserted in the approximately U-shaped grooves of the corresponding holding members10, the cleaning roller7does not roll. In this case, since the cleaning roller7moves while rubbing against the ink-discharge surfaces6, not only liquid ink accreted on the ink-discharge surfaces6but also highly viscous ink or solidified ink clogged on the same can be removed.

Also, the cleaning roller7may be formed so as to roll while rubbing against the ink-discharge surfaces6of the print head4by limiting its rolling with a brake mechanism. For example, in the state shown inFIG. 3, since this brake mechanism is constructed such that appropriate elastic bodies are disposed at the portions of the holding members10where the pins9disposed at both ends of the cleaning roller7are held so as to press-fit the pins9into corresponding holes formed in the elastic bodies, or such that both end surfaces of the cleaning roller7are pressed into contact with the corresponding side surfaces of the elastic bodies, an appropriate brake force is generated during the rolling of the cleaning roller7.

In this case, since the cleaning roller7rolls little by little while rubbing against the ink-discharge surfaces6, not only liquid ink accreted on the ink-discharge surfaces6but also highly viscous ink or solidified ink clogged on the same can be removed without damaging the ink-discharge surfaces6.

The ink receiver8disposed inside the head cap5has an ink-absorbing member8′ laid on the receiving surface of the ink receiver8serving as the bottom surface of the head cap5, as shown inFIGS. 3to5. The ink-absorbing member8′ serves as means for preventing rebound of ink preliminarily discharged from the print head4; is composed of a porous polymeric material such as sponge, polyurethane, or formed polyurethane; and is laid on substantially the entire receiving surface of the ink receiver8, as shown in FIG.4. Meanwhile, as shown inFIG. 5, the ink-absorbing member8′ is not laid below the central part of the crown-shaped cleaning roller7, having a large diameter so as not to come into contact with the central part.

When the ink-absorbing member8′ is laid in the above-mentioned manner, ink preliminarily discharged from the print head4shown inFIG. 2is prevented from rebounding and also the ink is absorbed so as not to be stored in the ink receiver8. Thus, the preliminarily discharged ink is prevented from rebounding off the ink receiver8and accordingly from accreting again on the ink-discharge surfaces6. Also, when the ink-absorbing member8′ has absorbed the preliminarily discharged ink after used for a reasonable time interval, by removing it from the ink receiver8and by replacing it with a new one, the preliminarily discharged ink can be easily removed.

Although, in the embodiment illustrated inFIGS. 3to5, the entire bottom surface of the head cap5is used as the ink receiver8by way of example, the present invention is not limited to this arrangement, and a part of the bottom surface may be used as the ink receiver8. For example, in the state shown inFIG. 2, by shifting the cleaning roller7a little toward the center of the head cap5so as to provide a partition between the cleaning roller7and the side wall of the head cap5close to the cleaning roller7, a chamber enclosed by the partition and the above-mentioned wall may be used as the ink receiver8. In such a case, a space for receiving ink preliminarily discharged from the ink-discharge openings of the print head4can be limited to a specific portion of the head cap5.

Next, preliminary discharge of ink from the ink-discharge openings of the print head4will be described. The preliminary discharge of ink is performed, for example, by sucking and removing ink in the ink-discharge openings, prior to a printing operation of characters and/or pictures in order to prevent the above-described situation in which the ink in the ink-discharge openings evaporates to high viscosity or solidification and, as a result, is prevented from being normally discharged. Ink is preliminarily discharged from the ink-discharge openings toward the ink receiver8of the head cap5after the ink-discharge surfaces6are cleaned by the cleaning roller7.

For example, the preliminary discharge is performed by repeating several times of discharging ink droplets from the ink-discharge openings of the print head4at a frequency of about 10 kHz.

In the state shown inFIG. 2, in order to avoid color mixture caused by cleaning the ink-discharge surfaces6for the respective colors with the above-mentioned single cleaning roller7, when the preliminary discharge of ink is performed after cleaning the ink-discharge surfaces6for the respective colors, it is necessary to control the timing of the preliminary discharge of ink.

To achieve this, as shown inFIG. 7, the head cap5has means for detecting the timing of the preliminary discharge of ink from the ink-discharge openings of the print head4while the head cap5is moving relative to the print head4. Meanwhile,FIG. 7illustrates a state in which the head cap5moves in the opposite direction to that shown in FIG.2.

The means for detecting the timing of the preliminary discharge of ink is formed by position-detecting sheets17disposed on the lower surface side of the head cap5and a photoelectric switch18disposed in the main body2of the printer shown inFIG. 1so as to face the position-detecting sheets17, as shown in FIG.7. The position-detecting sheets17are intended to determine a position of the head cap5corresponding to each of the ink-discharge surfaces6of the print head4for the respective colors when the head cap5is moving in the direction of the arrow A.

For example, a light-dark pattern is formed in concert with the array pitch of the ink-discharge surfaces6for the respective colors Y, M, C, and K, and the array of the pattern is arranged in the opposite direction to the order of the colors Y, M, C, and K of the ink-discharge surfaces6. Also, in the initial moving state of the head cap5, the array of the pattern of the position-detecting sheets17is shifted backward with respect to the direction of the arrow A.

The photoelectric switch18is intended to detect the light-dark pattern of the position-detecting sheets17moving together with the head cap5and is an integral combination of a photo emitter18amade from, for example, a light emitting diode (LED), and a photo detector18bmade from a photo diode. The light-dark pattern of the position-detecting sheets17has a reflectance variable with the wavelength of light emitted from the photo emitter18a, and the photo detector18bis also sensitive to the wavelength of the reflected light.

With this structure, when the position-detecting sheets17under the head cap5pass in front of the photoelectric switch18while the head cap5is moving in the direction of the arrow A, the light-dark pattern of the position-detecting sheets17is detected and the positions of the position-detecting sheets17corresponding to the ink-discharge surfaces6for the respective colors Y, M, C, and K are thus determined.

Thus, since the position of the cleaning roller7moving together with the head cap5is obtained, the sequential timing of the preliminarily discharge of ink from each of the ink-discharge openings is controlled immediately after the ink-discharge surfaces6for the respective colors are cleaned by the cleaning roller7. In this state, the preliminarily discharged ink is reliably received in the ink receiver8.

FIGS. 8A and 8Bschematically illustrate a modification of the cleaning roller7. In this modification, the cleaning roller7is driven to rotate by a drive mechanism for rotation in the normal or reverse direction. More particularly, in the state shown inFIG. 2, the rotating shaft of a motor (not shown) disposed in the main body2of the printer is coupled with the pins9of the cleaning roller7via a gear mechanism having an appropriate reduction ratio so as to actively drive the cleaning roller7for rotation.

Thus, as shown inFIG. 8A, the cleaning roller7is driven to rotate by the above-mentioned motor in the same direction as the moving direction of the head cap5indicated by the arrow A shown inFIG. 7, and also the number of rotations of the motor is arranged such that the peripheral speed v2of the cleaning roller7is greater than the moving speed v1of the head cap5. In this case, a difference in the speeds between the ink-discharge surfaces6of the print head4and the circumferential surface of the cleaning roller7causes to rub against each other; as a result, the ink-discharge surfaces6are reliably cleaned. Also, even when the number of rotations of the motor is arranged such that the moving speed v1of the head cap5is greater than the circumferential speed v2of the cleaning roller7, likewise as described above, the ink-discharge surfaces6and the circumferential surface of the cleaning roller7are caused to rub against each other; accordingly, the ink-discharge surfaces6are reliably cleaned.

Alternatively, as shown inFIG. 8B, the cleaning roller7may be rotated in the opposite direction to the moving direction of the head cap5indicated by the arrow A shown in FIG.7. In this case, a difference in the moving directions between the ink-discharge surfaces6of the print head4and the circumferential surface of the cleaning roller7causes to rub against each other; as a result, the ink-discharge surfaces6are reliably cleaned.

As described above, in the case of the modification of the cleaning roller7shown inFIGS. 8A and 8B, the ink-discharge surfaces6of the print head4are cleaned with new portions of the circumferential surface of the cleaning roller7, which are successively rolled out due to the active rotation of the cleaning roller7.

FIG. 9is a block diagram illustrating the configuration and an operation of a control device40for controlling the image forming apparatus having the above-described structure. The control device40is intended to control the drive of the moving means for moving the head cap5having the cleaning roller7housed therein and to control an discharge operation of ink from the ink-discharge openings of the print head4, and is formed by a controller41, a motor driver42, and a head driver43.

The controller41serves as drive control means for controlling the drive of a cap opening/closing motor46, which will be described later, for opening and closing the head cap5and also as discharge control means for controlling a discharge operation of ink from the ink-discharge openings; has a read only memory (ROM)44and a central processing unit (CPU)45therein, respectively, for storing a variety of information and control programs and for sending a variety of control commands in accordance with the control programs read out from the ROM44; and controls the motor driver42and the head driver43, which will be described later.

The motor driver42is intended to drive the cap opening/closing motor46for opening and closing the head cap5and a sheet feeding/delivering motor47for feeding and delivering a sheet of paper as a recording medium. The cap opening/closing motor46serves as moving means for moving the circumferential surface of the cleaning roller7and the ink-discharge surfaces6of the print head4relative to each other while keeping the former surface in contact with the latter surfaces.

The head driver43is intended to drive elements for discharging ink from the ink-discharge openings formed in the ink-discharge surfaces6of the print head4and sends a drive signal to each of electrothermal transducing means48for yellow, electrothermal transducing means49for magenta, electrothermal transducing means50for cyan, and electrothermal transducing means51for black, each made from an exothermic body, for example.

The control device40having the above-described configuration controls the controller41so as to take in a print signal indicating the start of an image forming operation from outside; to receive detecting signals representing the positions of the position-detecting sheets17corresponding to the ink-discharge surfaces6for the respective colors, from the photoelectric switch18shown inFIG. 7; and to send drive signals to the motor driver42and the head driver43so that yellow ink, magenta ink, cyan ink, and black ink are preliminarily discharged in the head cap5in that order in accordance with the order of the rows, over which the cleaning roller7passes, of the ink-discharge openings for the respective colors formed in the ink-discharge surfaces6.

FIG. 10is a flowchart of a control method of an image forming apparatus having the above-described structure, wherein control for its printing operation is mainly illustrated. This control is performed at the directions of the CPU45in accordance with the control program stored in the ROM44in the controller41shown in FIG.9.

First, in Step S1shown inFIG. 10, when a print signal, indicating the start of an image forming operation is input into the controller41shown inFIG. 9, the controller41sends a cap-opening trigger signal to the motor driver42so as to drive the cap opening/closing motor46, which hence starts an opening operation of the head cap5in Step S2. Next, in Step S3, the cleaning roller7cleans the ink-discharge surfaces6in concert with the opening operation of the head cap5, and the controller41sends a preliminary discharge signal to the head driver43so as to preliminarily discharge ink.

Subsequently, when it is confirmed that the head cap5has reached its retraction position in Step S4, the printing operation starts in Step S5. Then, after the printing operation has been performed in Step S6, the controller41sends a cap-closing trigger signal to the motor driver42so as to drive the cap opening/closing motor46, which hence closes the head cap5in Step S7. Then, the process returns to Step S1. Subsequently, the above operation is repeated in response to receipt of a print signal. Meanwhile, although the head cap5is closed immediately after the printing operation has been performed in the above description, the present invention is not limited to the above-mentioned operation; alternatively, the head cap5may be closed after a lapse of a predetermined time interval after the printing operation.

When the print signal has not been input in Step S1, the process advances to Step S8, and it is determined whether the closing state of the head cap5has continued for a predetermined time interval. When the closing state of the head cap5has continued for the predetermined time interval, the process advances to the “YES” side; in Step S9, the head cap5is opened and closed so as to clean the ink-discharge surfaces6and to preliminarily discharge ink; and the process returns to Step S1. Unless the closing state of the head cap5has continued for the predetermined time interval, the process advances to the “NO” side and returns to Step S1.

Referring next toFIGS. 11Ato11H, a sequential cleaning operation of the cleaning roller7and the head cap5of the image forming apparatus having the above-described structure will be described. Here, it is assumed that, in the inkjet head1shown inFIG. 2, the head cap5moves in the direction of the arrow A so as to clean the ink-discharge surfaces6of the print head4, and after this cleaning operation, the preliminary discharge of ink is performed.

FIG. 11Aillustrates an initial state in which the head cap5is closed relative to the ink cartridge3. In this state and in the state shown inFIG. 1, the inkjet head1is inserted and set in the main body2of the printer. Then, while being set in the main body2of the printer, as shown inFIG. 11B, the head cap5moves in the direction of the arrow A relative to the ink cartridge3in response to a head-cap opening signal. With this movement, the cleaning roller7moves together with the head cap5in the direction of the arrow A relative to the ink cartridge3and rolls while being pressed and kept in contact with the ink-discharge surfaces6of the print head4; or the cleaning roller7moves while its rotation being limited by fixing or by a brake mechanism or while being driven to rotate by a motor in the normal or reverse direction.

In this state, it is assumed that, in the state shown inFIG. 2, of the ink-discharge surfaces6of the print head4, the ink-discharge surfaces6for yellow Y have been cleaned. With this cleaning, the position-detecting sheet17disposed on lower surface side of the head cap5and corresponding to yellow Y (seeFIG. 7) moves to the detecting position of the photoelectric switch18, thereby detecting the fact-that the ink-discharge surfaces6for yellow Y have been cleaned.

With the above mentioned operation, a preliminary-discharge start signal is sent from the controller41to the head driver43, both shown in FIG.9. That is, the preliminary-discharge start signal is sent to the row of the ink-discharge openings of the ink-discharge surfaces6for yellow Y (i.e., to the electrothermal transducing means48for yellow).

Next, as shown inFIG. 1C, preliminary discharge ink52is jetted from the ink-discharge openings of the ink-discharge surfaces6for yellow Y. Then, a preliminary-discharge stop signal is sent to the ink-discharge openings of the ink-discharge surfaces6for yellow Y so as to stop the jetting of the preliminary discharge ink52. Subsequently, in a similar fashion to the above-mentioned manner, every time the cleaning roller7sequentially has cleaned each of the rows of the ink-discharge surfaces6for the colors M, C, and K in the state shown inFIG. 2, the photoelectric switch18detects the fact that the corresponding ink-discharge surfaces6have been cleaned, and on the basis of this detection, a preliminary-discharge start signal and then a preliminary-discharge stop signal are sent from the controller41to the corresponding row of the ink-discharge openings.

With the above-mentioned operation, as shown inFIGS. 11Dto11F, the timing of the preliminary discharge from each of the rows of the ink-discharge openings for the respective colors is controlled and the preliminary discharge ink52is sequentially jetted in the order of the colors M, C, and K.

Upon the cleaning of the ink-discharge surfaces6for the respective colors and the preliminary discharge of ink as described above, as shown inFIG. 11G, the head cap5moves to its limit in the direction of the arrow A, then moves slightly upwards, and lies at the retraction position. In this state, characters and/or pictures are printed on a recording sheet.

Next, when characters and/or pictures have been printed on recording sheets with the required number of pages, a head cap closing signal is sent and the head cap5hence moves from the above-mentioned retraction position in the direction of the arrow B relative to the ink cartridge3, as shown in FIG.11H. With this movement, the cleaning roller7moves together with the head cap5in the direction of the arrow B relative to the ink cartridge3; eventually becomes into the closed state and returns to the initial state. Meanwhile, while the cleaning roller7is returning in the direction of the arrow B, the cleaning roller7does not come into contact with the ink-discharge surfaces6; hence the ink-discharge surfaces6are not cleaned. Subsequent to that, the image forming apparatus waits for a next direction of a printing operation of characters and/or pictures.

In the operation illustrated inFIGS. 11Ato11H, when the head cap5moves in the direction of the arrow A, the cleaning roller7comes into contact with the ink-discharge surfaces6and cleans them, and when the head cap5returns in the direction of the arrow B, the cleaning roller7does not come into contact with the ink-discharge surfaces6. However, the present invention is not limited to this arrangement; and the head cap5may move in the directions of the arrows A and B with the cleaning roller7not coming into contact with the ink-discharge surfaces6.

In this case, the cleaning roller7does not clean the ink-discharge surfaces6, and the only thing to do is preliminarily discharge ink toward inside the head cap5. This operational sequence may be arranged such that the preliminary discharge of ink is performed when the head cap5returns from the retraction position shown inFIG. 11Gto the position shown inFIG. 11G, and then the head cap5moves again to the retraction position shown in FIG.11G.

Alternatively, with the head cap5lying at the retraction position shown inFIG. 11G, ink may be preliminarily discharged regardless of the opening/closing operation of the head cap5, that is, without cleaning the ink-discharge surfaces6by the cleaning roller7.

In the description referring toFIGS. 10 and 11Ato11G, the cleaning operation is performed such that the ink-discharge surfaces6are cleaned when the head cap5moves in the direction of the arrow A and is then opened, and the preliminary discharge of ink is performed after this cleaning operation. On the contrary, the cleaning operation may be performed such that the head cap5moves in the direction of the arrow A and is then opened without cleaning the ink-discharge surfaces6; then, the ink-discharge surfaces6are cleaned by the cleaning roller7when the head cap5moves in the direction of the arrow B and is then closed; and the preliminary discharge of ink is performed after this cleaning operation.

FIG. 12is a flowchart of an operation of the image forming apparatus and a control method thereof in the case where the ink-discharge surfaces6are cleaned by the cleaning roller7when the above-mentioned head cap5moves in the direction of the arrow B after being opened and is then closed; and the preliminary discharge of ink is performed after this cleaning operation, wherein control for its printing operation is mainly illustrated. This control is performed at the directions of the CPU45in accordance with the control program stored in the ROM44in the controller41shown in FIG.9.

First, in Step S11shown inFIG. 12, when a print signal indicating the start of an image forming operation is input into the controller41shown inFIG. 9, the controller41sends a cap-opening trigger signal to the motor driver42so as to drive the cap opening/closing motor46, which hence starts an opening operation of the head cap5in Step S12. Next, when it is confirmed that the head cap5has reached its retraction position in Step S13, the printing operation starts in Step S14.

When the printing operation has been performed in Step S15, the controller41sends a cap-closing trigger signal to the motor driver42so as to drive the cap opening/closing motor46, which hence starts a closing operation of the head cap5in Step S16. Next, in Step S17, the cleaning roller7cleans the ink-discharge surfaces6in concert with the closing operation of the head cap5, and the controller41sends a preliminary discharge signal to the head driver43so as to preliminarily discharge ink. Then, the process returns to Step S11.

Subsequently, the above operation is repeated in response to receipt of a print signal. Meanwhile, although the head cap5is closed immediately after the printing operation in the above description, the present invention is not limited to this arrangement; alternatively, the head cap5may be closed after a lapse of a predetermined time interval after the printing operation.

Unless the print signal has been input in Step S1, the process advances to Step S18, and it is determined whether the closing state of the head cap5has continued for the predetermined time interval. When the closing state of the head cap5has continued for the predetermined time interval, the process advances to the “YES” side; in Step S19, the head cap5is opened and closed so as to clean the ink-discharge surfaces6and to preliminarily discharge ink; and the process returns to Step S11. Unless the closing state of the head cap5has continued for the predetermined time interval, the process advances to the “NO” side and returns to Step S11.

FIGS. 13Ato13C illustrate a sequential operation of the head cap5and the cleaning roller7in the case where the ink-discharge surfaces6are cleaned by the cleaning roller7when the above-mentioned head cap5moves in the direction of the arrow B after being opened and is then closed, and the preliminary discharge of ink is performed after this cleaning operation. Here, an operation after the printing operation of characters and/or pictures has been performed in the state shown inFIG. 11Gwill be described.

As shown inFIG. 13A, when characters and/or pictures have been printed on recording sheets with the required number of pages with the head cap5lying at the retraction position, a head cap closing signal is sent and the head cap moves from the above-mentioned retraction position in the direction of the arrow B relative to the ink cartridge3, as shown in FIG.13B.

In accordance with the closing operation of the head cap5, the circumferential surface of the cleaning roller7comes into contact with the ink-discharge surfaces6of the print head4so as to clean the ink-discharge surfaces6in the order of the colors K, C, M, and Y in the opposite direction to that of the opening operation of the head cap5. Then, when the photoelectric switch (not shown) detects the passing of one of the position-detecting sheets (not shown) which corresponds to the ink-discharge surfaces6for the corresponding color, the preliminary discharge ink52for the corresponding color is jetted. Thus, when the ink-discharge surfaces6are cleaned and four kinds of ink for all four colors are preliminarily discharged, the process returns to the initial state shown in FIG.13C.

As described above, according to the operation and the control method illustrated inFIGS. 12 and 13Ato13C, when the head cap5is closed, the cleaning roller7is moved on the ink-discharge surfaces6so as to cause ink in the ink-discharge openings to be sucked, whereby the ink-discharge openings and the vicinities thereof are effectively cleaned without damaging the ink-discharge surfaces6.

Referring now toFIGS. 1 and 14to20, the entire structure and an operation of the above-described image forming apparatus, taking an inkjet printer for example, will be described. This inkjet printer is intended to finely particulate ink and to discharge it from an ink-jet head so as to form ink dots on a recording sheet, and as shown inFIG. 1, has the inkjet head1, the main body2of the printer, a head mounting/demounting mechanism19, and a head-cap opening/closing mechanism20. Meanwhile, the inkjet printer is of a type in which the inkjet head1is directly mounted in the main body2of the printer.

The inkjet head1is intended to finely particularize liquid ink by, for example, an electrothermal transducing method or an electromechanical transducing method and discharges it so as to form ink dots on a recording sheet, and has the same structure as that described with reference toFIGS. 1to13C.

The main body2of the printer is intended to have the inkjet head1mounted at a predetermined portion thereof so as to perform functions required for an inkjet printer and is equipped with a recording-sheet tray, a transport system for a recording sheet, an operational drive system, a control circuit for the overall image forming apparatus, and so forth. Meanwhile, the reference numeral21shown inFIG. 1represents a sheet-feed cartridge for feeding a recording sheet and a discharged-sheet receiver into which a printed sheet is discharged.

The head mounting/demounting mechanism19is intended to mount and fix the inkjet head1at the predetermined portion of the main body2of the printer and to release the fixing. For example, the head mounting/demounting mechanism19is formed by a horizontally oriented bar member having a structure so as to insert the inkjet head1into the predetermined recessed portion disposed at the central part of the main body2of the printer and to press the upper surface of the inkjet head1.

More particularly, the bar member extends through the overall width of the main body2of the printer and is arranged so as to erect vertically and fall down horizontally. Thus, the bar member allows the inkjet head1to be inserted in the direction of the arrow H and to be mounted in the main body2of the printer while erecting vertically as shown in FIG.1and fixes the inkjet head1at the predetermined portion while falling down horizontally as shown in FIG.14.

The head-cap opening/closing mechanism20is intended to move the head cap5relative to the print head4with the inkjet head1being fixed at the predetermined portion of the main body2of the printer (seeFIG. 2) so as to expose the ink-discharge surfaces6(seeFIG. 2) and also to close the head cap5after an printing operation and is formed by an engaging combination of a rack22and a pinion23disposed, for example, on one of the side surfaces of the main body2of the printer. Meanwhile, the rack22has a pin-shaped projection formed on the inner side surface thereof, which is fitted into a depression formed in the corresponding outer side surface of the head cap5.

Thus, as shown inFIG. 14, with the inkjet head1being fixed at the predetermined portion of the main body2of the printer by the head mounting/demounting mechanism19, when the pinion23is rotated in a predetermined direction by a motor (not shown), the rack22moves in the direction of the arrow A as shown inFIG. 15, thereby causing the head cap5shown inFIG. 1to move in the direction of the arrow A, and to be opened and eventually lie at the retraction position.

Meanwhile, the head-cap opening/closing mechanism20is not limited to the above-mentioned engaging combination of the rack22and the pinion23, and it may have an example structure in which rubber rollers are pressed against on both side surfaces of the head cap5; the rotating shafts of the rubber rollers are coupled with the motor; and the motor is rotated so that the friction with the rubber rollers causes the head cap5to move in the direction of the arrow A and to be opened.

Referring next toFIGS. 16to20, a specific mechanism and operation for fixing the inkjet head1at the predetermined portion of the main body2of the printer shown in FIG.1and for moving the head cap5relative to the print head4(seeFIG. 2) so as to expose the ink-discharge surfaces6(see FIG.2).

FIG. 16shows a state in which, in the state shown inFIG. 1, the inkjet head1is inserted in the direction of the arrow H and is disposed at the predetermined portion of the main body2of the printer. In this state, the elastic force of a helical spring25causes the bottom ends of cap-lock hooks24disposed in the inkjet head1and at both side ends thereof so as to engage with retaining pieces26formed on both sides of the head cap5. With this structure, the head cap5is integrally mounted on the ink cartridge3.

In this state and in the state shown inFIG. 16, the head mounting/demounting mechanism19is pressed down in the direction of the arrow J indicated in the drawing and is fixed. With this movement, top ends28of the cap-lock hooks24are pressed down and turned by a cap-lock releasing piece27disposed at the lower portion of the head mounting/demounting mechanism19; thus, as shown inFIG. 17, the bottom ends of the cap-lock hooks24are raised; as a result, the bottom ends of the cap-lock hooks24are disengaged with the retaining pieces26disposed on both sides of the head cap5. With this arrangement, as shown inFIG. 14, the inkjet head1is fixed to the predetermined portion of the main body2of the printer by the head mounting/demounting mechanism19and also the head cap5becomes movable.

Next, when the head-cap opening/closing mechanism20shown inFIG. 14is activated and the pinion23is rotated by the motor (not shown), the rack22moves in the direction of the arrow A. With this movement, as shown inFIG. 18, the head cap5mounted on the bottom side of the ink cartridge3moves together with the rack22in the direction of the arrow A and is then opened. Then, the cleaning roller7urged by the floating springs11starts to clean the ink-discharge surfaces6of the print head4disposed on the bottom surface of the ink cartridge3as shown in FIG.2. Meanwhile, the head cap5moves while following a moving trajectory P shown in FIG.18.

Then, as shown inFIG. 19, the head cap5moves successively while following the moving trajectory P in the direction of the arrow A. In this state, the ink-discharge surfaces6for the respective colors Y, M, C, and K shown inFIG. 2are successively cleaned by the cleaning roller7fixed to the head cap5, and after this cleaning operation, the preliminary discharge of ink is performed.

When the cleaning of the ink-discharge surfaces6for the respective colors and the preliminary discharge of ink have been performed, as shown inFIG. 20, the head cap5moves to its limit in the direction of the arrow A while following the moving trajectory P; then moves slightly upwards; and lies at the retraction position as shown in FIG.15. In this state, characters and/or pictures are printed on a recording sheet. With this structure, since the head cap5moves slightly upwards as shown inFIG. 20, a space for storing the head cap5can be reduced.

Although a recording sheet passes below the print head4disposed on the bottom surface of the ink cartridge3in the state shown inFIG. 20, the recording sheet may be guided to pass by the lower surface of the head cap5. In such a case, a rib or ribs for guiding the recording sheet may be disposed on the lower surface side of the head cap5. In addition, the lower surface of the head cap5may be treated with water repellent finish in order to prevent ink printed on the recording sheet from accreting on the lower surface.

When characters and/or pictures have been printed on recording sheets with the required number of pages in this state, the head cap5moves from the retraction position shown inFIG. 20in the direction of the arrow B in reverse order to the above-mentioned order, and as shown inFIG. 17, the head cap5returns to the initial state where it lies below the bottom surface of the ink cartridge3.

In the state shown inFIG. 16, when the head mounting/demounting mechanism19is opened in the opposite direction to the arrow J indicated in the drawing, the cap-lock hooks24are engaged with the retaining pieces26disposed on both sides of the head cap5by the elastic force of the helical spring25, whereby the head cap5is integrally mounted on the ink cartridge3. In this state, as shown inFIG. 1, the inkjet head1can be removed from the main body2of the printer.

When the power of the printer is shut off caused by a trouble of some kind with the head cap5lying at the retraction position shown inFIG. 20, the head cap5remains lying at the retraction position. In this state, when the head mounting/demounting mechanism19is opened in the opposite direction to the arrow J as shown inFIG. 16, only the ink cartridge3is removed with the head cap5remaining at the retraction position.

In order to prevent the above problem, an interlock mechanism may be constructed such that the head cap5lying at the retraction position returns automatically to the initial state shown inFIG. 16when the power of the printer is shut off caused by a problem of some kind, or the head mounting/demounting mechanism19is allowed to open in the opposite direction to the arrow J only when the head cap5lies in the initial state shown in FIG.16.

Although the inkjet printer as described with reference toFIGS. 1 and 14to20is of a type in which the ink-jet head1is directly mounted in the main body2of the printer, the present invention is not limited to the above mentioned type, and is likewise applicable to a type in which the inkjet head1is mounted in the main body2of the printer via a tray. Referring now toFIGS. 21A and 21B, an ink-jet printer of another type will be briefly described.

First, as shown inFIG. 21A, the inkjet head1having the head cap5integrally mounted on the ink cartridge3is mounted, in a manner shown by the arrow Q indicated in the drawing, at a predetermined location in a tray29which can move forward and backward relative to the main body2of the printer. Then, the tray29is moved in the direction of the arrow R and is set in the main body2of the printer.

In this state, as shown inFIG. 21B, the head cap5is retained halfway while the tray29is moving in the direction of the arrow R by appropriate retaining means disposed in the main body2of the printer and is brought to a halt. The tray29is intended to set the inkjet head1in the main body2of the printer and to replace it with another one.

Then, since the tray29moves further in the direction of the arrow R, the ink cartridge3moves in the direction of the arrow R relative to the head cap5; as a result, the head cap5is opened. At the same time, when the head cap5moves in the opposite direction to the arrow R relative to the ink cartridge3, the ink-discharge surfaces6of the print head4are cleaned and also the preliminary discharge of ink is performed in accordance with the same operation as shown inFIGS. 11Ato11H. After then, characters and/or pictures are printed on a recording sheet.

Meanwhile,FIGS. 21A and 21Bshow a recording-sheet tray30, a recording sheet31, feeding rollers32, a feeding belt33, a sheet-discharging tray34, and a discharge direction S of a recording sheet.

When characters and/or pictures have been printed, the ink cartridge3moves in the opposite direction to the arrow R relative to the head cap5and returns to the initial state in which the head cap5is closed. In this case, when the ink cartridge3returns in the direction so as to close the head cap5relative to the ink cartridge3, the ink-discharge surfaces6of the print head4are not cleaned and the preliminary discharge is not performed.

Meanwhile, in the case of the operation shown inFIGS. 12,13A, and13B, from the state in which the head cap5shown inFIG. 21Bis opened, when the ink cartridge3moves in the opposite direction to the arrow R relative to the head cap5and the head cap5is closed, the ink-discharge surfaces6of the print head4are cleaned, and after this cleaning operation, the preliminary discharge of ink is performed.

Although an inkjet printer of a line scan head type has been described as an example of the image forming apparatus, the present invention is not limited to the above-described printer and is applicable to an inkjet printer of a serial type. Also, the present invention is not limited to ink-jet printers and is applicable to image forming apparatuses such as a facsimile machine and a copying machine of an ink-jet recording type.