This application claims priority under 35 USC 119 from Japanese Patent Application No. 2004-278043, the disclosure of which is incorporated by reference herein.
1. Field of the Invention
The present invention relates to an ink jet recording head and an ink jet recording apparatus for discharging ink droplets from plural nozzles by driving an element substrate such as a piezoelectric element.
2. Description of the Related Art
An ink jet recording apparatus for printing on a recording medium such as paper by discharging ink droplets from plural nozzles has various advantages such as compactness, inexpensiveness and quietness, and such ink jet recording apparatuses are widely available commercially.
Such ink jet recording apparatuses utilize a piezo ink jet method whereby, for example, pressurization from a piezoelectric element causes a pressure wave to act on an ink in a pressure chamber, thereby discharging an ink droplet from a nozzle.
In response to a requirement for high-speed printing, an ink jet recording apparatus capable of printing across the entire width of a recording medium without requiring a scanning motion of an ink jet recording head has recently been proposed.
As shown in
Further, an ink jet recording head 210 shown in
However, the ink jet recording head 200 shown in
In the ink jet recording head 210 shown in
On the other hand, an ink jet recording head in which head units of a trapezoidal shape, having a group of nozzles corresponding to such shape, are arrayed in an alternately inverted staggered arrangement has been proposed in order to reduce the width W of the head bar. In such an ink jet recording head, the head bar can be made with a smaller width in comparison with the ink jet recording heads 200, 210 shown in
However, in this kind of ink jet recording head, in cases of irreparable nozzle clogging or damage to a discharge port, the entire head bar has to be replaced, since the head units are connected integrally. Further, since the head units have a trapezoidal shape, a wiping operation thereon in any direction geometrically causes contact with an adjacent head unit and thus maintenance cannot be carried out on the basis of individual head units.
The present invention has been made in consideration of the aforementioned circumstances, and is to provide a compact ink jet recording head and an ink jet recording apparatus, capable of printing an entire width of a recording medium with high quality, through an efficient arrangement of element substrates for driving head units. There are also provided an ink jet recording head and an ink jet recording apparatus allowing easy maintenance on the basis of individual head units.
A first aspect of the invention provides an ink jet recording head which discharges ink droplets by driving an element substrate provided in a head unit, the element substrate being constituted of plural drive elements, wherein the head unit has a substantially parallelogram shape, and a head bar is formed by connecting the plural head units in a row.
The element substrate mentioned above is constituted of a group of piezoelectric elements, each of which is driven to cause a pressure wave to act on an ink, thereby discharging an ink droplet from a nozzle. The substantially parallelogram shape means to include a parallelogram of which corners are cut off or rounded.
In the ink jet recording head of the first aspect, a head bar is formed by connecting plural head units in a row. In each head unit, by activation of the element substrate, ink droplets are discharged from nozzles onto a recording medium. In such ink jet recording head, since the head bar is constituted by connecting head units of a substantially parallelogram shape in a row, the head bar can be made smaller in the width thereof (width in a transporting direction of the recording medium), whereby the ink jet recording head can be made more compact. Also at the maintenance operation, a wiping operation or a sucking operation can be executed for each head unit.
A second aspect of the invention provides an ink jet recording apparatus, mounted with the ink jet recording head of the first aspect.
According to the second aspect, the ink jet recording apparatus can be made to be compact by employing the smaller ink jet recording head. Also it enables an easy maintenance on the basis of individual head units.
The present invention of the aforementioned configurations enables an efficient arrangement of the element substrates for driving the head units, thereby realizing an ink jet recording head and an ink jet recording apparatus of high quality and a small size. The invention also realizes easy maintenance on the basis of individual head units.
Embodiments of the present invention will be described in detail based on the following figures, wherein:
In the following, a first embodiment of the present invention will be described in detail, with reference to the accompanying drawings.
As shown in
As shown in
As shown in
A wiper (not shown) for wiping the nozzles 22 at a maintenance operation is moved, as shown in
As shown in
The nozzle plate 30 is provided with a nozzle 22 for discharging an ink droplet. The communicating hole plate 32 is provided with a communicating hole 54 communicating with the nozzle 22, and the damper member 34 is provided with a communicating hole 56. The pool plates 36, 38, 40 are provided respectively with communicating holes 58, 60, 62, and the communicating hole plate 42 is provided with a communicating hole 64. Further, the flow path plate 44 is provided with a communicating hole 66, and the communicating hole plate 46 is provided with a communicating hole 68. The nozzle 22 and the communicating holes 54, 56, 58, 60, 62, 64, 66, 68 are in a mutually communicating relationship and is connected to a pressure chamber 70 formed in the pressure chamber plate 48.
On the other hand, the communicating hole plate 32 has a cavity 72 in a position under the damper member 34, thereby enabling a deformation of the damper member 34. The pool plates 36, 38, 40 are respectively provided with ink pools 74, 76, 78 which are mutually connected to constitute a single space. Such ink pools 74, 76, 78 store an ink, supplied from an unillustrated ink supply hole. Further, the communicating hole plate 42 is provided with a supply hole 80 so formed as to be connected with the ink pool 78, and the flow path plate 44 is provided with an ink flow path 82 communicating with the supply hole 80. Further, the communicating hole plate 46 is provided with a supply hole 84 which is so formed as to be connected with the ink flow path 82 at a side thereof opposite to the supply hole 80. These ink pools 74, 76, 78, the supply hole 80, the ink flow path 82, the supply hole 84 and the pressure chamber 70 are in a mutually communicating relationship, whereby the ink is supplied from the ink pools 74, 76, 78 into the pressure chamber 70.
Further, on the vibrating plate 50 and above the pressure chamber 70, there is mounted a piezoelectric element 86 as pressure generation means, which is given a driving voltage from an unillustrated flexible wiring board. The piezoelectric elements 86 are respectively provided above the pressure chambers 70 communicating with the individual nozzles 22, and piezoelectric element groups formed by the plural piezoelectric elements 86 constitute the element substrates 16, 18 shown in
In the following, there will be explained the function of the above-described ink jet recording head 10.
In each head unit 14 of the ink jet recording head 10, an ink is supplied, as shown in
In the ink jet recording head 10, as shown in
In the ink jet recording head 10, as the plural head units 14 are mounted with screws (not shown) on the support member 13 of the head bar 12, each head unit 14 can be individually replaced. Further, as the head units 14 of a substantially parallelogram shape are arranged longitudinally in a row, a sucking operation or a wiping operation for the nozzles 22 can be executed for each head unit 14, thereby facilitating the maintenance operation.
The head unit 14 of the substantially parallelogram shape includes two element substrates 16, 18 of a substantially trapezoidal shape, so that the element substrates 16, 18 can be efficiently arranged within the head unit 14. It is therefore rendered possible to reduce the width (width in the transporting direction of the recording medium P) of the head unit 14, thereby realizing a compact ink jet recording head and also realizing a higher resolution.
As shown in
On the other hand, in
In the following, a second embodiment of the present invention will be described with reference to the accompanying drawings.
In the head unit 110, as shown in
Also as shown in
In such head unit 110, a nozzle 22 is formed at an end side of a pressure chamber 120, and a direction of the pressure chamber 120 to the nozzle 22 is opposite across a connecting (boundary) gap between the element substrates 116A and 116B. Such configuration allows to arrange the pressure chambers 120 efficiently, when the nozzles 22 are uniformly arranged over the connecting gap between the element substrates 116A and 116B.
In the following, a third embodiment of the present invention will be described with reference to the accompanying drawings.
The head unit 130 has a substantially parallelogram shape, and such head units 130 are connected in a row in the transversal direction of the recording medium thereby constituting a head bar (not shown). Within the head unit 130, there is provided a single element substrate 132 of a substantially parallelogram shape. Such configuration allows to arrange the element substrate 132 efficiently and to reduce the width (width in the transporting direction of the recording medium) of the head unit 130.
As shown in
The foregoing embodiments employ the element substrates 16, 18 of a substantially trapezoidal shape, but such shape is not restrictive and there can also be employed a substantially triangular shape. Also the element substrates 16, 18 may have a substantially trapezoidal shape of which corners are cut off or rounded.
Also in the foregoing embodiment, each head unit 14 includes two element substrates 16, 18, but such configuration is not restrictive and there may be provided element substrates of an even number such as 4 or 6. The element substrates of an even number allow an efficient arrangement within the head unit of a substantially parallelogram shape.
The ink jet recording head explained in the foregoing embodiments is intended to record an image (including a character) on a recording medium P, but such configuration is not restrictive. More specifically, the recording medium is not limited to paper, and the liquid to be discharged is not limited to an ink. There are included all liquid droplet emitting apparatuses utilized for industrial applications, such as discharging an ink onto a polymer film or a glass for preparing a color filter for a display, or discharging fused solder onto a board for forming a bump for component mounting.
In the ink jet recording head of the invention, the head bar may be formed in a size corresponding to a width of a recording medium.
Such ink jet recording head, having the head bar formed with the size corresponding to the width of the recording medium, is capable of printing across the entire width of the recording medium by passing the recording medium only once.
The head unit may include the element substrates of a substantially trapezoidal shape by an even number, and such element substrates of an even number may be arranged in such a manner that the substantially trapezoidal shapes are arrayed in an alternately mutually opposed arrangement.
The substantially parallelogram shape means to include a parallelogram of which corners are cut off or rounded.
In the aforementioned configuration, as the head unit includes the element substrates of a substantially trapezoidal shape by an even number and such substantially trapezoidal shapes are arrayed in an alternately mutually opposed arrangement, the element substrates can be efficiently arranged within the head unit of a substantially parallelogram shape. Element substrates of an odd number cannot be arranged efficiently in the head unit of a substantially parallelogram shape (because a parallelogram cannot be formed), whereby the head unit becomes larger in size. It is thus possible to achieve high resolution while reducing the width (in the transporting direction of the recording medium) of the head unit, thereby realizing a compact head bar.
The head unit may include two element substrates of a substantially trapezoidal shape, and the two element substrates may be arranged so that such substantially trapezoidal shapes are mutually opposed. In the trapezoidal shapes within the head unit, the oblique sides other than the mutually opposed oblique sides may be longer oblique sides.
In such configuration, since the head unit includes two element substrates of a substantially trapezoidal shape and, in the trapezoidal shapes within the head unit, the oblique sides other than the mutually opposed oblique sides are longer oblique sides, the element substrates can be efficiently arranged within the head unit of a substantially parallelogram shape. It is thus possible to achieve high resolution while reducing the width (in the transporting direction of the recording medium) of the head unit, thereby realizing a compact head bar.
In the element substrate, an inner angle formed by the oblique side in the mutually opposed position may be larger than an outer angle formed by an oblique side opposed to the aforementioned oblique side.
In such configuration, since the substantially trapezoidal shape of the element substrate has an outer angle smaller than an inner angle, there can be secured a large space between the adjacent element substrates when plural head units are connected in a row. As the element substrates of the adjacent head units have a large overlapping amount when seen in the transporting direction of the recording medium, the space becomes correspondingly large. It is therefore possible to secure a large capping margin for each head unit at the maintenance operation, and also to improve the productivity. Also, when plural head units are connected, the adjacent head units have a long connecting portion, so that the difference in the characteristics between the head units at the connecting portion becomes less conspicuous and streaks or the like do not appear at the printing.
Also the element substrate of the substantially trapezoidal shape may be constituted by connecting, in a close relationship, a first element substrate of a substantially triangular shape and a second element substrate of a substantially trapezoidal shape or a substantially parallelogram shape.
The substantially triangular shape means to include a triangle of which corners are cut off or rounded.
In such configuration, as the element substrate of the substantially trapezoidal shape is constituted by connecting, in a close relationship, a first element substrate of a substantially triangular shape and a second element substrate of a substantially trapezoidal shape or a substantially parallelogram shape, there can be achieved cost reduction and an improvement in the production yield.
The element substrate may include two or more drive elements in an acute angle portion.
In such configuration, an acute angle portion of the element substrate, easily chipped at the manufacture, is provided with two or more drive elements. It is thus rendered possible to alleviate the influence of a chipping of the acute angle portion, by not forming an acute angle portion having only one drive element.
Also in the head unit, the drive element is so driven as to cause a pressure wave to act on an ink in a pressure chamber thereby discharging an ink droplet from a nozzle, and the directions of the pressure chambers with respect to the nozzles may be made mutually opposite across a connecting portion of the first element substrate and the second element substrate in a close relationship.
In such configuration, since the directions of the pressure chambers with respect to the nozzles are made mutually opposite across the connecting portion of the first element substrate and the second element substrate in a close relationship, the plural nozzles can be arranged with a uniform pitch, even in case a gap is formed in the connecting portion of the first element substrate and the second element substrate, whereby the element substrates can be arranged more easily.
Also the drive element is preferably a piezoelectric element.
In such configuration where the drive element is a piezoelectric element, by driving such piezoelectric element, a pressure wave can be made to act on the ink in the pressure chamber, thereby discharging an ink droplet from the nozzle.
Also it is preferred that the head unit includes extended portions formed by outward extending of two obtuse angle portions of the substantial parallelogram and corner cut portions formed by cutting off two acute angle portions and that, when plural head units are connected in a row, the extended portion and the corner cut portion in adjacent positions are in a mutually opposed relationship.
In such configuration, the head unit includes extended portions formed by outward extending of two obtuse angle portions of the substantial parallelogram and corner cut portions to be opposed to the extended portions when the head units are connected in a row. Such configuration prevents a decrease in the distance between the element substrate of the substantially trapezoidal shape and the edge of the head unit even when the head unit is formed in a substantially parallelogram shape, and eliminates the influence of a chipping because there are no acute angle portions provided.
Also the head unit may be detachably mounted on a support member of a length corresponding to the width of the recording medium.
In such configuration, since the head unit is detachably mounted on the support member, a replacement on the basis of individual head units is possible at the maintenance operation and a replacement of the whole head bar is not required.
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