The present invention relates to a recording head including ink ejection openings for ejecting ink onto a recoding medium such as a sheet, and also relates to an ink-jet recording apparatus provided with such a recording head.
As recording apparatuses such as facsimile machines, copiers, and printers, ink-jet recording apparatuses, which form images by ejecting ink, are widely used for their ability to form high-definition images.
In such ink-jet recording apparatuses, fine ink droplets (hereinafter, referred to as mist) which are ejected together with ink droplets for image recording, and splashed mist which is generated when ink droplets attach to the recording medium, attach to and solidify on an ink ejection face of a recording head. As mist on the ink ejection face gradually increases and covers the ink ejection openings, it causes, for example, degraded straightness of the ink trajectory (curved flight) or ejection failure, and leads to degraded printing performance of the recording head.
There are also known ink-jet recording apparatuses provided with, for cleaning the ink ejection face of the recording head, a plurality of cleaning liquid supplying openings in a part of the ink ejection face outside an ink ejection region (upstream in the direction of wiping by a wiper) in which a plurality of ink ejection openings are open. In such ink-jet recording apparatuses, after the cleaning liquid is supplied from the cleaning liquid supplying openings, the wiper can be moved across the ink ejection face starting outward of the cleaning liquid supplying openings so that the wiper wipes the ink ejection face while holding the cleaning liquid. Recovery operation for the recording head is thus performed.
An ink-jet recording apparatus provided with a plurality of cleaning liquid supplying openings in the ink ejection face of the recording head is disclosed, for example, in Patent Documents 1 identified below.
Patent Document 1: JP-A-2007-83496
However, in the conventional ink-jet recording apparatus mentioned above, the wiper passes over the cleaning liquid supplying openings every time recovery processing for the recording head is performed, and thus, inconveniently, the tip end of the wiper is damaged by the edge of the cleaning liquid supplying openings. If the tip end of the wiper is damaged so severely as to be chipped away, the wiping performance of the wiper is significantly degraded to leave unwiped areas.
The present invention has been made to solve the above problem. An object of the present invention is to provide a recording head which can clean an ink ejection face while preventing a wiper from being damaged and to provide an inkjet recording apparatus provided with such a recording head.
A recording head according to a first aspect of the present invention is provided with an ink ejection face which includes an ink ejection region in which a plurality of ink ejection openings for ejecting ink onto a recording medium are open. Upstream of the ink ejection region in the wiping direction which is the direction in which a wiper wipes the ink ejection face, a plurality of depressed portions are provided. Inside each depressed portion, two or more cleaning liquid supplying openings for supplying cleaning liquid are provided along the wiping direction.
With a recording head according to the first aspect of the present invention, upstream of an ink ejection region in the wiping direction, a plurality of depressed portions are provided. Inside each depressed portion, cleaning liquid supplying openings for supplying cleaning liquid are provided. With this, after the cleaning liquid is supplied from the cleaning liquid supplying openings, a wiper can be moved across an ink ejection face starting upstream of the depressed portion in the wiping direction so that the wiper wipes the ink ejection face while holding the cleaning liquid. Thus, the ink ejection face can be cleaned.
Inside each depressed portion, two or more cleaning liquid supplying openings are provided along the wiping direction. With this, when recovery operation for the recording head is performed, the number of times the wiper passes the edge of the depressed portion is smaller than the number of times the wiper passes the edge of the cleaning liquid supplying openings. That is, the number of times the tip end of the wiper is rubbed against the edge can be reduced. This helps prevent the tip end of the wiper from being damaged.
This and other objects of the present invention, and the specific benefits obtained according to the present invention, will become apparent from the description of embodiments which follows.
Now, embodiments of the present invention are described with reference to the drawings.
As shown in
On the downstream side (right side in
The recording portion 9 includes a head housing 10 and line heads 11C, 11M, 11Y and 11K which are held on the head housing 10. These line heads 11C to 11K are supported at such a height that a predetermined gap (for example, 1 mm) is formed relative to the conveying face of the first conveying belt 8. As shown in
As shown in
To the recording head 17 constituting the line heads 11C to 11K, ink of four colors (cyan, magenta, yellow, and black) stored in ink tanks (unillustrated) is supplied, ink of the different colors being supplied to corresponding ones of the line heads 11C to 11K respectively.
According to the control signal from the control portion 110 (see
On the recording head 17, a cleaning liquid supplying member 60 for supplying a cleaning liquid is provided. The cleaning liquid supplying member 60 is arranged adjacent to the head portion 18, on its upstream side (right side in
The cleaning liquid supplying face F2 is formed so as to be flush with the ink ejection face F1. In a part of the cleaning liquid supplying member 60 upstream (right-side in
Here, in the cleaning liquid supplying region R2 of the cleaning liquid supplying member 60, as shown in
Inside the depressed portion 64, a plurality of (here, four) cleaning liquid supplying openings 60a for supplying a cleaning liquid are provided. The cleaning liquid supplying openings 60a are connected to the top face of the depressed portion 64.
As shown in
The subtank 71 is connected to a downstream end of a cleaning liquid replenishing path 80 comprising a tube through which the cleaning liquid 23 passes. An upstream end of the cleaning liquid replenishing path 80 is connected to a replenishment tank (also called a main tank) 81 in which is stored the cleaning liquid 23 for supply to the subtank 71. The upstream end of the cleaning liquid replenishing path 80 is immersed in the cleaning liquid 23. The cleaning liquid replenishing path 80 is provided with a replenishing pump 82 that pumps up the cleaning liquid 23 from the main tank 81 to feed it to the subtank 71. For the supplying pump 72 and the replenishing pump 82, for example, a tube pump, a syringe pump, or a diaphragm pump can be used. The supplying pump 72 is so configured that it can switch, when the supply is stopped, between a state where the path between an inflow port and an outflow port of the supplying pump 72 is blocked and a state where those ports communicate with each other. The detailed structure of and around the cleaning liquid supplying member 60, the subtank 71 and the main tank 81 will be described later.
In this ink-jet recording apparatus 100, to clean the ink ejection face F1 on the recording head 17, at the start of printing after a long out-of-operation period and during intermissions of printing operation, ink is discharged forcibly from the ink ejection openings 18a in all the recording heads 17. Then the cleaning liquid 23 is supplied through the cleaning liquid supplying openings 60a (see
As shown back in
The sheet S with an ink image recorded on it at the recording portion 9 is conveyed to the second conveying unit 12. While the sheet S passes through the second conveying unit 12, the ink ejected on the surface of the sheet S is dried. Under the second conveying unit 12, a maintenance unit 19 and a cap unit 90 are arranged. When wiping operation is performed by the wiper 35 as mentioned above, the first conveying unit 5 descends. Then the maintenance unit 19 moves to under the recording portion 9, wipes off the ink discharged forcibly from the ink ejection openings 18a in the recording head 17 and the cleaning liquid 23 supplied from the cleaning liquid supplying openings 60a, and collects the ink and the cleaning liquid 23 wiped off. When capping the ink ejection face F1 (see
On the downstream side of the second conveying unit 12 in the sheet conveying direction, there is provided a discharge roller pair 16 which discharges the sheet S with an image recorded on it to outside the apparatus main body. On the downstream side of the discharge roller pair 16, there is provided a discharge tray (unillustrated) on which the sheets S discharged outside the apparatus main body is stacked.
The maintenance unit 19 includes a plurality of wipers 35 (see
The wiper 35 is an elastic member (for example, a rubber member made of EPDM) for wiping the cleaning liquid 23 supplied from the cleaning liquid supplying openings 60a (see
Next, the structures of and around the cleaning liquid supplying member 60, the subtank 71 and the main tank 81 will be described in detail.
As shown in
In a lower part of the main tank 81, a second detection sensor 83 for sensing the cleaning liquid 23 is provided. The second detection sensor 83 has an electrode pair (unillustrated) to which a voltage is applied and which is arranged inside the main tank 81. The second detection sensor 83 can, based on whether a current is present between the electrodes, sense the presence or the absence of the cleaning liquid 23. When the second detection sensor 83 senses the absence of the liquid, and a display panel (unillustrated) of the ink-jet recording apparatus 100 indicates that the main tank 81 has become empty. With this, a user or an operator replaces the main tank 81 with a new one, or replenishes the main tank 81 with the cleaning liquid 23.
The subtank 71 is arranged above the main tank 81 and below the cleaning liquid supplying face F2 of the recording head 17. The subtank 71 is provided with an atmospheric open port 71a for equalizing the pressure in its internal space with the atmospheric pressure. Thus, in a state where the supplying pump 72 is off, if the path between the inflow port and the outflow port of the supplying pump 72 is switched to a communicating state, a negative pressure is applied to the cleaning liquid 23 in the cleaning liquid supplying openings 60a.
As shown in
Four corner portions 64a of the outer edge of the depressed portion 64 are rounded as seen in a plan view. The size of the rounding (the radius) is, for example, 0.5 mm or larger but 1 mm or smaller.
Of the outer edge of the depressed portion 64, as shown in
Next, recovery operation for the recording head 17 using the maintenance unit 19 in the ink-jet recording apparatus 100 of this embodiment will be described. Recovery operation for the recording head 17 described below is performed by controlling the operation of the recording head 17, the maintenance unit 19, the supplying pump 72, and the like based on the control signal from the control portion 110 (see
When recovery operation for the recording head 17 is performed, as shown in
Prior to wiping operation (which will be described later), the control portion 110 (see
Prior to wiping operation (which will be described later), the control portion 110 (see
The control portion 110, as shown in
The control portion 110 moves the wiper 35, which is in a state where the tip end of the wiper 35 is in pressed contact with the inclined face 62 of the cleaning liquid supplying member 60, in the direction of the ink ejection region R1 (arrow A direction), as shown in
When the tip end of the wiper 35 has passed the cleaning liquid supplying region R2, the path between the inflow port and the outflow port of the supplying pump 72 is switched to a communicating state. With this, a negative pressure is applied to the cleaning liquid 23 in the cleaning liquid supplying openings 60a, and the cleaning liquid 23 inside the depressed portion 64 is sucked into the cleaning liquid supplying openings 60a to return to a state in
As shown in
After wiping operation, as shown in
Finally, the control portion 110 moves the maintenance unit 19 arranged between the recording portion 9 and the first conveying unit 5 horizontally to arrange it under the second conveying unit 12, and raises the first conveying unit 5 up to a predetermined position. Recovery operation for the recording head 17 is thus finished.
As mentioned above, on the upstream side of the ink ejection region R1 in the wiping direction, a plurality of depressed portions 64 are provided. Inside each depressed portion 64, the cleaning liquid supplying openings 60a for supplying the cleaning liquid 23 are provided. With this, after supplying the cleaning liquid 23 from the cleaning liquid supplying openings 60a, moving the wiper 35 from upstream of the depressed portion 64 in the wiping direction along the ink ejection face F1 permits the wiper 35 to wipe the ink ejection face F1 while holding the cleaning liquid 23. Thus, the ink ejection face F1 can be cleaned.
Inside the depressed portion 64, two or more (here, four) cleaning liquid supplying openings 60a are provided along the wiping direction. With this, when recovery operation for the recording head 17 is performed, the number of times the wiper 35 passes the edge (outer edge) of the depressed portion 64 is smaller than the number of times the wiper 35 passes the edge of the cleaning liquid supplying openings 60a. That is, the number of times the tip end of the wiper 35 is rubbed against the edge can be reduced. This helps prevent the tip end of the wiper 35 from being damaged.
A plurality of depressed portions 64 are provided in the cleaning liquid supplying region R2 arranged upstream of the ink ejection region R1 in the wiping direction. With this, the path of the ink and the cleaning liquid in the recording head 17 can be formed separately (away from each other), and thus it is possible to prevent the structure of the recording head 17 from becoming complicated.
As mentioned above, the corner portions 64a of the outer edge of the depressed portion 64 are rounded as seen in a plan view. This further helps to prevent the tip end of the wiper 35 from being damaged.
Also, as mentioned above, of the outer edge of the depressed portion 64, a part which intersects with the cleaning liquid supplying face F2 is rounded as seen in a cross-sectional view. This further helps to prevent the tip end of the wiper 35 from being damaged.
Also, as mentioned above, the length of the depressed portion 64 in the head width direction is equal to or shorter than 1 mm. This makes it possible, during cleaning liquid supplying operation, to form a meniscus easily around the outer edge of the depressed portion 64.
It is also possible to suppress an increase in the size of the depressed portion 64. That is, it is possible to suppress an increase in the total volume of the depressed portion 64. Thus, it is possible to suppress an increase in the amount of cleaning liquid 23 required to fill the depressed portion 64 with the cleaning liquid 23 as well as an increase in the time for supplying the cleaning liquid 23.
Since an increase in the size of the depressed portion 64 can be suppressed, even if a sheet S is bent, it is possible to prevent the sheet S from entering the depressed portion 64.
The embodiments disclosed above should be understood to be in every aspect illustrative and not restrictive. The scope of the present invention is defined not by the description of the embodiments given above but by the appended claims, and should be understood to encompass any modifications made in the sense and scope equivalent to those of the claims.
For example, while the above embodiments deal with an example where the cleaning liquid supplying member 60 in which the depressed portion 64 and the cleaning liquid supplying openings 60a are formed is provided separately from the head portion 18, this is not meant to limit the present invention. Instead of the cleaning liquid supplying member 60 being provided, the depressed portion 64 and the cleaning liquid supplying openings 60a may be formed in the head portion 18.
While the above embodiments deal with an example where the outer edge of the depressed portion 64 is formed in a substantially rectangular shape, this is in no way meant to limit the present invention. For example, the outer edge of the depressed portion 64 may be formed in an oval (elliptic) shape or in a circular shape.
While the above embodiments deal with an example provided with four cleaning liquid supplying openings 60a arranged inside each depressed portion 64 along the wiping direction, this is not meant to limit the present invention. For example, as in the recording head 17 of the modified example of the present invention shown in
While the above embodiments deal with an example where recovery operation for the recording head 17 is performed using the cleaning liquid 23 and the ink (purged ink) 22, this is not meant to limit the present invention. Recovery operation for the recording head 17 may be performed using only the cleaning liquid 23. That is, ink purging operation does not necessarily need to be performed.
Any configurations achieved by combining the configurations of the embodiments and modified examples described above are also within the technical scope of the present invention.
Number | Date | Country | Kind |
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2017-003925 | Jan 2017 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2017/035772 | 10/2/2017 | WO | 00 |