The present application is based on, and claims priority from JP Application Serial Number 2019-122732, filed Jul. 1, 2019, the disclosure of which is hereby incorporated by reference herein in its entirety.
The present disclosure relates to a liquid ejecting apparatus.
A technique for ejecting a liquid from nozzles onto a medium such as a print sheet has been proposed. When, for example, a medium is curled, the interval between the surface of the medium and each nozzle changes for each nozzle, and the position on the surface of the medium on which the liquid is to land may be an unintended position. For example, JP-A-2003-334941 discloses a configuration in which an ejection timing is changed depending on a distance between a head ejection face and a recording medium.
However, it is difficult for errors to be sufficiently reduced with the configuration of JP-A-2003-334941. For example, an apparent problem may occur when an interval between the head ejection face and the recoding medium changes to a large degree between two neighboring regions in the scanning direction. When a liquid is to be ejected onto each of the two regions at an appropriate ejection timing depending on the interval, the ejection timing at one of the two regions may overlap the ejection timing at the other thereof, and it is difficult to eject the liquid onto both the two regions under a desired condition. Consequently, the errors in the landing positions may not be sufficiently reduced by the change in the ejection timings.
A liquid ejecting apparatus according to an aspect of the present disclosure includes a liquid ejecting head with a nozzle configured to eject a liquid, and a control section configured to control ejection of the liquid by the liquid ejecting head. The control section controls ejection of the liquid by the liquid ejecting head so that an ejection speed of the liquid from the nozzle is a first speed when a distance between the nozzle and a recording medium is a first distance, the ejection speed is a second speed higher than the first speed when the distance between the nozzle and the recording medium is a second distance greater than the first distance, and the ejection amount per ejection from the nozzle when the distance between the nozzle and the recording medium is the first distance is equal to the ejection amount per ejection from the nozzle when the distance between the nozzle and the recording medium is the second distance.
As illustrated in
The movement mechanism 22 moves the liquid ejecting head 26 and the recording medium 12. Specifically, the movement mechanism 22 includes a first movement section 31 and a second movement section 32.
The liquid ejecting head 26 ejects an ink supplied from the liquid container 14 onto the recording medium 12 from nozzles N under control of the control unit 20. Each of the liquid ejecting heads 26 ejects the ink onto the recording medium 12 while the first movement section 31 transports the recording medium 12 and the transport unit reciprocates, and consequently a desired image is formed on a surface of the recording medium 12. An axis perpendicular to the X-Y plane will be denoted as the Z-axis in the following description. The X-Y plane is parallel to the surface of the recording medium 12, for example. The nozzles N eject the ink in the Z-axis direction.
As illustrated in
A pressure chamber C and a drive element (energy generating element) E are formed per nozzle N. The pressure chamber C is a space communicating with the nozzle N. The pressure chambers C in the liquid ejecting head 26 are filled with ink supplied from the liquid container 14. The drive element E generates energy when powered, and varies the pressure of the ink in the pressure chamber C in accordance with the energy. For example, the drive element E may be implemented as a piezoelectric element configured to change the volume of a pressure chamber C by deforming the wall of the pressure chamber C or as a heat generating element configured to generate bubbles in a pressure chamber C by using the ink heated in the pressure chamber C. The drive element E varies the pressure of the ink in the pressure chamber C, and the ink in the pressure chamber C is then ejected from the nozzle N. The processing operations using a piezoelectric element will be described below. A piezoelectric element includes at least a piezoelectric body and two electrodes configured to be electrically coupled to the piezoelectric body.
As illustrated in
Specifically, the drive waveform Q changes in voltage over time as follows. At first, the voltage starts decreasing from the reference voltage at a timing T1, and stops decreasing at a timing T2. The period from the timing T1 to the timing T2 is a period M2 in which the pressure chambers C expand. The voltage is at a constant voltage V1 in the period from the timing T2 to a timing T3.
The voltage then starts increasing at the timing T3 and stops increasing at a timing T4. The voltage increases beyond the reference voltage during the period. The period from the timing T3 to the timing T4 is a period M1 in which the pressure chambers C contract. The voltage is at a constant voltage V2 in the period from the timing T4 to a timing T5. Thereafter, the voltage starts decreasing again at the timing T5 and reaches the reference voltage at a timing T6.
The drive circuit 40 supplies the drive waveform Q to each of the drive elements E per unit period U. The drive elements E operate in response to the supply of the drive waveform Q, and the ink is ejected from the nozzles N corresponding to the drive elements E. That is, the drive waveform Q is a waveform to eject the ink from the nozzles N.
As illustrated in
As described above, the liquid ejecting head 26 moves in the X-axis direction and the ink is ejected in the Z-axis direction. As illustrated in
The detection section 28 of
The control unit 20 controls the ejection speed v in response to the distance G measured by the detection section 28. As illustrated in
When the ejection speed v changes, the ejection amount may change in response to the change in the speed. In such a case, the ejection amount or the density of an image to be recorded on the recording medium differs between the first distance G1 and the second distance G2, and good image quality cannot be achieved. According to the present embodiment, the ejection amount remains unchanged while the ejection speed is switched between the first speed v1 and the second speed v2.
An angle θ formed between the resultant vector σc corresponding to the ink flying speed and the Z-axis changes in response to the ejection speed v. Specifically, an angle 02 formed between the resultant σc and the Z-axis at the second speed v2 is smaller than an angle θ1 formed between the resultant vector σc and the Z-axis at the first speed v1. Thus, as illustrated in
Specifically, the control unit 20 controls the ejection speed v by changing the shape of the drive waveform Q of
In other words,
A drive signal COM is generated in response to the distance G measured by the detection section 28 in parallel with the movement of the liquid ejecting head 26 and the recording medium 12 by the movement mechanism 22. For example, the shape of the drive signal COM changes each time the distance G is measured by the detection section 28. The drive signal COM generated by the control unit 20 is supplied to the drive elements E via the drive circuit 40. Thus, the ink can be ejected at the ejection speed v in response to the distance G between the recording medium 12 and the nozzle N. As can be understood from the above description, the ejection speed v is switched in response to the distance G in parallel with the movement of the liquid ejecting head 26 and the recording medium 12 by the movement mechanism 22.
The control unit 20 may change the rate of change of voltage in the period M2 of the drive waveform Q of
In other words,
The control unit 20 may control the ejection speed v by changing the amplitude P of the voltage of the drive waveform Q as a shape of the drive waveform Q. In
In other words,
As can be understood from the above description, the control unit 20 corresponds to a component configured to control ink ejection by the liquid ejecting head 26 so that the ejection speed v is the first speed v1 at the first distance G1, the ejection speed v is the second speed v2 at the second distance G2, and the ejection amount per ejection is equal between the first distance G1 and the second distance G2. The meaning of “the ejection amount is equal” includes a strictly equal amount of ejection and a substantially equal amount of ejection. The meaning of “the ejection amount is substantially equal” is that the ejection amount is within a range of manufacture error, for example. For example, an ejection amount with an error of 5% or less may be expressed as “the ejection amount is substantially equal”.
According to the first embodiment, the ejection speed v is controlled in response to the distance G between the nozzle N and the recording medium 12, thereby reducing the error E of the landing position x when the distance G changes.
A second embodiment will be described below. The components having similar functions to those of the first embodiment will be given like reference numerals, and detailed description of each component will be omitted as appropriate.
The first movement section 31 according to the second embodiment rotates a recording medium 12 about a center axis W of the recording medium 12 under control of the control unit 20. The second movement section 32 moves the liquid ejecting head 26 on a curve S along the section of the recording medium 12 while the nozzle N faces the landing face F2 of the recording medium 12. The movement of the recording medium 12 by the first movement section 31 and the movement of the liquid ejecting head 26 by the second movement section 32 are performed concurrently. Both the recording medium 12 and the liquid ejecting head 26 thereby move to eject the ink in the circumferential direction of the landing face F2.
As illustrated in
The first movement section 31 moves the recording medium 12 to a third position K3 and a fourth position K4 different from the third position K3 about the center axis W. As illustrated in
Also in the second embodiment as in the first embodiment, the distance G between the nozzle N and the recording medium 12 changes in response to the movement of the liquid ejecting head 26 and the recording medium 12. For example, the distance G is the first distance G1 when the liquid ejecting head 26 is at the first position K1 and the distance G is the second distance G2 when the liquid ejecting head 26 is at the second position K2. As in the first embodiment, the second distance G2 is greater than the first distance G1. As in the first embodiment, the control unit 20 controls ink ejection by the liquid ejecting head 26 so that the ejection speed v is the first speed v1 at the first distance G1, the ejection speed v is the second speed v2 at the second distance G2, and the ejection amount per ejection is equal between the first distance G1 and the second distance G2.
Similar effects as in the first embodiment are also achieved in the second embodiment. The direction in which the ink is ejected from the liquid ejecting head 26 at the first position K1 is different from the direction in which the ink is ejected from the liquid ejecting head 26 at the second position K2, and thus the liquid ejecting head 26 can be used for printing on recording mediums 12 of various shapes.
Each of the above-described embodiments can be variously modified. Specific variants applicable to each of the above-described embodiments will be described below by way of example. Two or more variants arbitrarily selected from the following variants may be combined as appropriate when compatible with each other.
(1) The recording medium 12 with the uneven landing face F2 may be used in the first embodiment and the recording medium 12 may be a three-dimensional (3D) container in the second embodiment, for example, but the recording medium 12 is not limited to the above examples. A typical example of the recording medium 12 is a 3D object having an uneven surface. The present disclosure is suitably used when the recording medium 12 is a 3D object. The 3D object is not limited to, for example, print sheets or containers having an uneven landing face F2 and may be various 3D products.
(2) In each of the above-described embodiments, the movement mechanism 22 includes the first movement section 31 and the second movement section 32, but the configuration of the movement mechanism 22 is not limited to the above example. The movement mechanism 22 may include at least one of the first movement section 31 and the second movement section 32. That is, the movement mechanism 22 moves at least one of the liquid ejecting head 26 and the recording medium 12. The direction in which the first movement section 31 moves the recording medium 12 and the direction in which the second movement section 32 moves the liquid ejecting head 26 are not limited to the examples in the above-described embodiments, and the directions may be changed as appropriate depending on the shape and kind of the recording medium 12.
When the recording medium 12 is a sheet of roll paper or the like, the recording medium 12 may be curled, for example. Consequently, the present disclosure is suitably used even when the distance G changes due to a change in shape of the recording medium 12.
(3) The control unit 20 may control the ejection speed v in the following exemplary way. A numerical range assumed for the distance G between the nozzle N and the recording medium 12 is divided into two or more periods Rn (n=1 to N). For example, the distance G is greater in the period Rn than in the period Rn−1. The control unit 20 specifies one of the periods R to which the distance G measured by the detection section 28 corresponds and switches the ejection speed v to the ejection speed vn based on the period R. For example, the control unit 20 switches the ejection speed v to any one of the ejection speeds vn corresponding to the periods R. The ejection speed vn is higher than the ejection speed vn−1. In the configuration, for example, the distance G is the first distance G1 in the period Rn1 and the distance G is the second distance G2 in the period Rn2 (n1<n2).
In the configuration, the liquid ejecting apparatus 100 may store in advance drive signals COMn corresponding to ejection speeds vn. The control unit 20 supplies the drive circuit 40 with a drive signal COMn corresponding to a period Rn among the drive signals COMn. Thus, the ink is ejected at the ejection speed vn based on the period R.
(4) The liquid ejecting apparatus 100 described in each of the above-described embodiments may be used for various devices such as facsimile machines or copying machines in addition to printing-only devices. The applications of the liquid ejecting apparatus are not limited to printing. For example, a liquid ejecting apparatus configured to eject a solution of color material is used as a manufacturing apparatus configured to form a color filter of a display apparatus such as liquid crystal display panel. A liquid ejecting apparatus configured to eject a solution of conductive material is used as a manufacturing apparatus configured to form a wiring or an electrode of a wiring substrate. A liquid ejecting apparatus configured to eject a solution of bioorganic material is used as a manufacturing apparatus configured to manufacture a biochip, for example.
(5) In each of the above-described embodiments, the liquid ejecting apparatus 100 includes the detection section 28 and is configured such that the detection section 28 performs the detection operation at the same time as the liquid ejecting operation and measures a distance between a recording medium and a nozzle, but may operate in other ways. For example, the liquid ejecting apparatus 100 is not limited to including the detection section 28 and may store in advance, in the liquid ejecting head or the storage section, a surface shape of a recording medium or a change in distance between a recording medium and a nozzle before the start of the ejecting operation.
Number | Date | Country | Kind |
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2019-122732 | Jul 2019 | JP | national |