Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2003-10-22
2004-08-31
Nguyen, Thinh (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06783207
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority under 35 USC 119 from Japanese Patent Application No. 2003-80949, the disclosures of which are incorporated by reference herein.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an inkjet recording head and an inkjet recording device.
2. Description of the Related Art
An inkjet recording device records text, images and the like on recording paper by reciprocating an inkjet recording head in a main scanning direction, conveying the recording paper in a sub-scanning direction, and selectively discharging ink droplets from a plurality of nozzles. A technology is well known in which an inkjet recording head discharges an ink droplet from a nozzle that communicates with a pressure chamber by applying pressure, via an oscillating diaphragm, to ink in the pressure chamber by using an actuator such as, for example, a piezoelectric element which converts electrical energy to mechanical energy.
In recent years, the trend for inkjet recording devices to get faster has intensified. Accordingly, inkjet recording heads which are capable of image formation over broader regions in shorter times have been produced by lengthening the inkjet recording heads, increasing the number of nozzles at each inkjet recording head, and arraying the nozzles in matrix patterns (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2001-334661).
When an inkjet recording head is lengthened and the nozzles are increased in number and arrayed in a matrix pattern as described above, a large number of piezoelectric elements arrayed in the matrix pattern are also required in accordance therewith. This large number of piezoelectric elements arrayed in the matrix pattern are formed by machining, for example, by sandblasting, a single piezoelectric plate (i.e., by machining a piezoelectric material such as a piezoelectric ceramic plate or the like, prior to preparation of the piezoelectric elements). Therefore, the longer the inkjet recording head, the longer the piezoelectric plate for forming the piezoelectric elements. However, making the piezoelectric plate longer and forming the large number of piezoelectric elements arrayed in the matrix pattern is problematic for manufacturing, and leads to a decrease in yields.
Accordingly, a technique has been considered in which a plurality of actuator units, at which the piezoelectric elements are formed, are connected in a row direction of the nozzles for lengthening. With such a structure, the large number of piezoelectric elements are formed so as to be divided up between a plurality of piezoelectric plates. In consequence, the decrease in yields does not result.
However, in a case in which a plurality of actuator units are thus joined for lengthening, problems may arise in assembly if there is no spacing at joining portions thereof. Accordingly, there is a technique in which a plurality of parallelogram-form actuator units are offset in the main scanning direction and a spacing L between the actuator units is assured (see, for example, JP-A No. 10-217452).
However, it is necessary to dispose the parallelogram-form actuator units to be offset in the main scanning direction in order to assure the spacing L between the actuator units. Consequently, the width in the main scanning direction of the inkjet recording head in which the actuator units are joined becomes larger in accordance with lengthening of the inkjet recording head (see FIG. 1 of JP-A No. 10-217452). As a result, the inkjet recording head becomes larger together with the length of the inkjet recording head.
Furthermore, because the nozzle rows are offset in the main scanning direction, it is necessary to offset ink drop discharge timings for each group of nozzles. As a result, the output of image data becomes more complicated.
SUMMARY OF THE INVENTION
The present invention has been devised in order to solve the problems described above, and an object of the present invention is to provide an inkjet recording head and inkjet recording device which improve production yields and enable lengthening of the inkjet recording head while assuring assembly characteristics and not increasing width of the inkjet recording head, and with which output of image data does not become more complicated in accordance with the increase in length.
In a first aspect of the present invention, an inkjet recording head includes: a nozzle plate in which nozzles which eject ink drops are formed; pressure chambers communicating with the nozzles; and actuators abutting at the pressure chambers, which at least one of increase and reduce pressures of ink in the pressure chambers. The inkjet recording head scans in a direction intersecting a conveyance direction of a recording medium and records an image at the recording medium with the ink drops ejected from the nozzles, and includes at least one nozzle row parallel to the conveyance direction of the recording medium. The inkjet recording head includes a plurality of nozzle groups structured by dividing up the nozzle row, the nozzles of the nozzle row include opposing nozzles which are disposed at a boundary between neighboring the nozzle groups which neighbor in the row direction of the nozzle row, the actuators include opposing actuators, which respectively correspond to the opposing nozzles, and actuators within the nozzle groups, which respectively correspond to nozzles neighboring the opposing nozzles in the row direction, and a separation between the opposing actuators disposed at the boundary is equal to or greater than separations between the opposing actuators and the corresponding actuators within the nozzle groups.
According to an inkjet recording head of the present invention, nozzle rows are divided up to structure a plurality of nozzle groups. Hence, the separation between opposing actuators, which respectively correspond to opposing nozzles disposed at a boundary between the nozzle groups which neighbor one another in the row direction of the nozzle rows, is provided so as to be equal to or greater than the separations between actuators within the nozzle groups, which respectively correspond to and are adjacent in the row direction to the nozzles disposed at the boundary, and the actuators corresponding to the nozzles disposed at the boundary.
According to the present aspect, the actuators are formed by machining for each group. When these actuator groups are joined to produce the inkjet recording head, there is naturally no problem with assembly characteristics. Furthermore, because the actuators are formed by machining from a plurality of actuator plates (an actuator material prior to machining of the actuators) which are short in accordance with the nozzle groups, yields are improved.
Further, because the nozzle rows are not offset even though the inkjet recording head is lengthened, the width of the inkjet recording head is not increased even though the number of actuators increases. Moreover, there is no need to offset the discharge timings for each nozzle group, and the output of image data will not become complicated.
In a second aspect of the present invention, an inkjet recording head includes: a nozzle plate in which nozzles which eject ink drops are formed; pressure chambers communicating with the nozzles; and actuators abutting at the pressure chambers, which at least one of increase and reduce pressures of ink in the pressure chambers. The inkjet recording head records an image over the width of a recording medium, which is being conveyed, with the ink drops ejected from the nozzles, and includes at least one nozzle row in a direction intersecting the conveyance direction of the recording medium. The inkjet recording head includes a plurality of nozzle groups structured by dividing up the nozzle row, the nozzles of the nozzle row include opposing nozzles which are disposed at a boundary between neighboring the nozzle groups which neighbor in the row direction of the nozzle row, the actuators include opposing actuators, which respectively cor
Kanda Torahiko
Seto Shinji
Umehara Shigeru
Fuji 'Xerox Co., Ltd.
Nguyen Thinh
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