Patent Grant
10011133
The present invention relates to liquid discharge device such as an ink jet recording apparatus, a method for controlling a liquid discharge device, and a device driver, and particularly to a liquid discharge device that discharges liquid from a nozzle by driving a driver element to cause pressure vibrations of liquid in a liquid channel, a method for controlling such a liquid discharge device, and a device driver.
A liquid discharge device includes a liquid discharge head having a nozzle from which various types of liquid are discharged (ejected). Such a liquid discharge device is exemplified by an image recording device such as an ink jet printer or an ink jet plotter, and has been applied to various types of manufacturing apparatuses by utilizing a feature of causing a very small amount of liquid to impact a predetermined location accurately. Specifically, the liquid discharge device is applied to, for example, display manufacturing apparatuses for manufacturing color filters of liquid crystal displays and the like, electrode formation apparatuses for forming electrodes of organic electro luminescence (EL) displays and field emission displays (FEDs), and chip manufacturing apparatuses for manufacturing biochips. A recording head for an image recording device discharges liquid ink. A coloring material discharging head for a display manufacturing apparatus discharges solutions of coloring materials of red (R), green (G), and blue (B) from nozzles. An electrode material discharging head for an electrode formation apparatus discharges a liquid electrode material. A biogenic organic substance discharging head for a chip manufacturing apparatus discharges a solution of a biogenic organic substance.
In a printer, which is a type of the liquid discharge device, anisotropic etching and formation of a side wall protection film are alternately repeated on a silicon substrate (so-called a Bosch process) so that a nozzle having a circular orifice is formed (see, for example, International Publication No. WO 2008/155986). This technique enables formation of nozzles having smaller sizes with accurately uniformized dimensions and shapes. Inner wall surfaces of the thus-formed nozzles have wave-shaped patterns called scallops. These scallops form a wave-shaped uneven pattern on the inner peripheral surface of a nozzle in cross section formed because annular recesses (recesses) each extending along the circumference of the nozzle are arranged along the center axis of the nozzle. In the case of ejecting liquid including a solid component from a nozzle having such scallops, the following problems arise. That is, while the liquid is stabilized before ejection of liquid, the surface (meniscus) of liquid in the nozzle is located near an opening (an opening toward the outside) of the nozzle. In a liquid discharge operation by driving of a driver element, pressure variations occur in a liquid channel so that the liquid surface is drawn into the nozzle (toward the liquid channel) or pushed toward the outside of the nozzle. In the configuration having an uneven pattern on the inner wall surface of the nozzle as described above, liquid is likely to remain in the recesses, and liquid in the recesses is exposed to outside air when the meniscus is drawn into the nozzle so that the viscosity of liquid gradually increases and a sediment of a solid component of the liquid is attached to the inner wall surface of the nozzle. The sediment on the inner wall surface near the opening of the nozzle causes a flying direction of liquid droplets discharged from the nozzle to be deviated from an intended direction so that the impact location on a target of liquid droplets is shifted from an originally intended location. Such a deviation of the impact location of liquid droplets causes, for example, degradation of quality of a recorded image in the case of recording an image or the like on an impact target.
Regarding the uneven pattern on the inner peripheral surface of the nozzle, the etching rate may be reduced to reduce a level difference of the uneven pattern and, thereby, smooth the uneven pattern. In this case, however, the number and time of processes increase accordingly, resulting in a problem of lower productivity.
An advantage of some aspects of the invention is to provide a liquid discharge device capable of reducing a liquid discharge failure caused by attachment of a solid component in liquid to an uneven portion of a nozzle inner wall surface, a method for controlling such a liquid discharge device, and a device driver.
According to a first aspect of the invention, a liquid discharge device includes a liquid discharge head that includes a nozzle from which liquid is discharged and a liquid channel communicating with the nozzle, and that discharges liquid from the nozzle, wherein the nozzle has an inner wall surface having one or more annular recesses each of which extends along a circumference of the nozzle and which are arranged along a center axis of the nozzle so that the inner wall surface has an uneven pattern, and in a case where ink is continuously discharged from an identical nozzle, at a time when a meniscus in the nozzle after previous discharge is located closer to an initial position before discharge than a center position between the initial position and a position at which the meniscus is most greatly drawn toward the liquid channel, subsequent discharge is performed.
With this configuration, in the case of continuously discharging ink from the identical nozzle, ink is repeatedly discharged in the state where the meniscus in the nozzle is located closer to the initial position so that drawing of the meniscus is reduced, and accordingly, a period in which liquid remaining in the inner wall of the nozzle is exposed to outdoor air is reduced. Consequently, sediment caused by a solid component of liquid is less likely to be generated near an opening of the nozzle. As a result, flexure in the flying direction of liquid droplets is reduced.
In the above configuration, the liquid discharge device preferably further includes: a driver element that causes a pressure vibration of liquid in the liquid channel and causes the liquid to be discharged from the nozzle; a driving pulse generator that generates a driving pulse for driving the driver element; and a detection mechanism that detects environment information, wherein the driving pulse generator reduces an occurrence frequency of the driving pulse depending on environment information detected by the detection mechanism.
With this configuration, the occurrence frequency of the driving pulse is reduced in an environment where there is a risk of attachment of sediment to the inner wall surface of the nozzle. Thus, the time from previous discharge to subsequent discharge is extended so that ink can be discharged in a state where the meniscus in the nozzle is closer to the initial position accordingly. This can effectively reduce generation of sediment in the nozzle.
In the above configuration, the environment information may be temperatures, and if a temperature detected by the detection mechanism is lower than a predetermined threshold, the driving pulse generator may set the occurrence frequency of the driving pulse at a maximum occurrence frequency in specification, whereas if the temperature detected by the detection mechanism is the predetermined threshold or more, the driving pulse generator may set the occurrence frequency of the driving pulse lower than the maximum occurrence frequency.
With this configuration, the occurrence frequency of the driving pulse is set at the maximum occurrence frequency in specification in the environment where the temperature is lower than the threshold. Thus, a throughput of a liquid droplet discharge operation can be enhanced, and accordingly, a discharge failure of liquid droplets due to an increase in the viscosity of liquid in the liquid droplet discharge operation can be reduced. On the other hand, the occurrence frequency of the driving pulse is reduced in the environment where the temperature is the threshold or more. Thus, the time from previous discharge to subsequent discharge is extended so that ink can be discharged in a state where the meniscus in the nozzle is closer to the initial position accordingly. This can effectively reduce generation of sediment in the nozzle.
In the above configuration, the environment information may be humidities, and if a humidity detected by the detection mechanism is higher than a predetermined threshold, the driving pulse generator may set the occurrence frequency of the driving pulse at a maximum occurrence frequency in specification, whereas if the humidity detected by the detection mechanism is the predetermined threshold or less, the driving pulse generator may set the occurrence frequency of the driving pulse lower than the maximum occurrence frequency.
With this configuration, the occurrence frequency of the driving pulse is set at the maximum occurrence frequency in specification in the environment where the humidity is higher than the threshold. Thus, a throughput of a liquid droplet discharge operation can be enhanced, and accordingly, a discharge failure of liquid droplets due to an increase in the viscosity of liquid in the liquid droplet discharge operation can be reduced. On the other hand, the occurrence frequency of the driving pulse is reduced in the environment where the humidity is the threshold or less. Thus, the time from previous discharge to subsequent discharge is extended so that ink can be discharged in a state where the meniscus in the nozzle is closer to the initial position accordingly. This can effectively reduce generation of sediment in the nozzle.
In the above configuration, the driving pulse generator preferably changes the occurrence frequency of the driving pulse to a range from 38 [kHz] or more to 42 [kHz] or less.
With this configuration, a significant decrease of a throughput of the liquid droplet discharge operation caused by the reduction of the pulse occurrence frequency can be reduced while flexure of the flying direction of liquid droplets caused by sediment in the nozzle is suppressed. In addition, a discharge failure of liquid droplets due to an increase in the viscosity of liquid in the nozzle during the liquid droplet discharge operation can be reduced.
In the above configuration, the liquid discharge device may further include a controller that causes a display device to display a selection screen for enabling a user to select a lower limit of the occurrence frequency in reducing the occurrence frequency of the driving pulse, and that receives selection by the user through the selection screen, wherein the driving pulse generator may change the occurrence frequency in a range not lower than the lower limit selected by the user.
With this configuration, the lower limit of the occurrence frequency of the driving pulse is selected and set by the user so that a liquid droplet discharge operation satisfying the needs of the user can be performed.
In the above configuration, the liquid discharge device may further include a controller that causes a display device to display a selection screen for enabling a user to select one of a first mode in which a liquid droplet discharge operation is performed with the occurrence frequency of the driving pulse reduced depending on the environment information and a second mode in which a liquid droplet discharge operation is performed with the occurrence frequency of the driving pulse unchanged, and that receives selection by the user through the selection screen, wherein the driving pulse generator may set the occurrence frequency of the driving pulse based on the selection by the user.
With this configuration, the user can easily and intuitively select a mode so that a liquid droplet discharge operation satisfying the needs of the user can be performed.
According to a second aspect of the invention, a method for controlling the liquid discharge device according to the first aspect of the invention includes: a selection screen display step of causing the display device to display the selection screen; a selection receiving step of receiving selection by a user through the selection screen; and a frequency setting step of setting the occurrence frequency of the driving pulse based on the selection by the user.
A device driver according to a third aspect of the invention is a device driver capable of being executed by an information processor connected to a liquid discharge device so that the information processor and the liquid discharge device can communicate with each other, wherein the device driver performs the steps of the method for controlling the liquid discharge device described above.
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
Embodiments of the present invention will be described hereinafter with reference to the attached drawings. In the following embodiments, various limitations are described as preferred examples of the invention.
The range of the invention, however, is not limited to the examples unless otherwise specified in the following description. In the following description, an ink jet recording apparatus (hereinafter referred to as a printer) will be described as an example of a liquid discharge device according to the invention.
The printer 3 according to this embodiment includes a CPU 11 (a type of a controller according to the invention), a memory device 12, an input/output interface 13, a driving signal generator 14 (a type of a driving pulse generator according to the invention), a paper feeding mechanism 16, a carriage moving mechanism 17, a temperature sensor 40 (a type of a detection mechanism according to the invention) that detects a temperature near a recording head 18, a display device 41 such as a liquid crystal display device, and the recording head 18, for example.
The input/output interface 13 performs transmission and reception of various types of data, specifically receives a request for execution of printing or data on printing from the computer 1 and outputs status information of the printer 3 to the computer 1. The CPU 11 is an arithmetic processing unit for controlling the entire printer. The memory device 12 is a device for storing a program of the CPU 11 and data for use in various controls, and includes a ROM, a RAM, and a non-volatile random access memory (NVRAM). The CPU 11 controls units in accordance with programs stored in the memory device 12. The CPU 11 according to this embodiment transmits dot pattern data from the computer 1 to a head controller 19 of the recording head 18. The driving signal generator 14 generates an analog signal and amplifies the signal to generate a driving signal illustrated in
An end of the carriage 23 in a scanning direction (i.e., front at the right in
A wiping mechanism 27 is disposed adjacent to the capping mechanism 25. The wiping mechanism 27 is used for wiping a nozzle surface of the recording head 18 with a wiper 28, and is configured to move the wiper 28 to a state in which the wiper 28 is in contact with the nozzle surface or a standby state in which the wiper 28 is separated from the nozzle surface. In this embodiment, the recording head 18 moves in the main scanning direction with the wiper 28 being in contact with the nozzle surface so that the wiper 28 slides on the nozzle surface to wipe the nozzle surface. A configuration in which the wiper 28 runs by itself while movement of the recording head 18 stops to, thereby, wipe the nozzle surface may be employed. That is, the recording head 18 and the wiper 28 only need to move relatively to each other to wipe the nozzle surface.
The recording head 18 according to this embodiment is generally constituted by a nozzle plate 38, a channel substrate 29, and a piezoelectric element 20, for example, and is attached to a holder 30 with these components being stacked. The nozzle plate 38 is made of a silicon single crystal substrate in which a plurality of nozzles 37 are formed at a predetermined pitch and linearly extend in the same direction. In this embodiment, the parallel nozzles 37 constitute a nozzle series. A surface of the nozzle plate 38 from which ink is discharged corresponds to the nozzle surface of the recording head 18.
The channel substrate 29 has a plurality of cavities serving pressure chambers 31 and individually associated with the nozzles 37. A common liquid chamber 32 common to the pressure chambers 31 is formed outside the series of the pressure chamber 31 in the channel substrate 29. The common liquid chamber 32 communicates with the pressure chambers 31 through ink supply ports 33. The pressure chambers 31 and the ink supply ports 33 individually communicating with the nozzles 37 correspond to a liquid channel according to the invention. Ink is introduced from the ink cartridge 22 to the common liquid chamber 32 through an ink introduction path 34 of the holder 30. The piezoelectric element 20 (a type of a driver element) is disposed on the upper surface of the channel substrate 29 opposite to the nozzle plate 38 with an elastic film 35 interposed therebetween. The piezoelectric element 20 is formed by sequentially stacking a metal lower electrode film, a piezoelectric layer of, for example, lead zirconate titanate, and a metal upper electrode film (which are not shown). The piezoelectric element 20 is a so-called flexure mode piezoelectric element, and covers the pressure chamber 31 from above. The piezoelectric element 20 is deformed by applying a driving signal (driving pulse Pd (see
The expanded state of the pressure chamber 31 is maintained for a certain time by the expansion hold element p2. After being held by the expansion hold element p2, the piezoelectric element 20 is caused to flex by the contraction element p3 toward the inside of the pressure chamber 31 (toward the nozzle plate 38). Accordingly, the pressure chamber 31 is rapidly contracted from the expanded volume to a contracted volume corresponding to the contraction potential VH. In this manner, as illustrated in
In a configuration in which an inner wall surface has the uneven pattern 46 as in the nozzle 37 of this embodiment, ink tends to remain especially in the recess 47. When the meniscus M is drawn toward the pressure chamber 31 in discharging ink as described above, ink remaining in the recess 47 is exposed to the outdoor air. Accordingly, the viscosity of the ink gradually increases, and as illustrated in
In particular, in an environment of a relatively high ambient temperature or a dry environment with a relatively low humidity, the viscosity of ink tends to increase so that the problems described above are likely to arise. Thus, in the printer 3 according to this embodiment, the driving frequency of a driving pulse Pd generated by the driving signal generator 14 is changed depending on a temperature (a type of environment information) detected by the temperature sensor 40. Specifically, a threshold (e.g., 36° C.) is set for the temperature, and if the temperature detected by the temperature sensor 40 is lower than the threshold, the driving frequency of the driving pulse Pd is set at a maximum frequency (100 [%] driving frequency) in specification. On the other hand, if the temperature detected by the temperature sensor 40 is the threshold or more, the driving frequency of the driving pulse Pd is set at a frequency lower than the maximum frequency. For example, in a configuration in which the maximum frequency is 50 [kHz], the driving frequency is set at 40 [kHz], which is lower than the maximum frequency by 20 [%].
As shown in the intermediate graph in
In this manner, if the temperature detected by the temperature sensor 40 is the threshold or more, the driving frequency of the driving pulse Pd is set at a frequency lower than the maximum frequency. Thus, even in the case of continuously discharging ink from the same nozzle 37, ink is repeatedly discharged while the meniscus M is located closer to the initial position Ip as a whole during a print operation, as compared to the case of setting the driving frequency at the maximum frequency. More specifically, subsequent (next) discharge can be performed at a time when the meniscus M is located at the position Np closer to the initial position Ip than the center position Cp between the position Mp at which the meniscus M is most greatly drawn toward the pressure chamber 31 and the initial position Ip. Accordingly, the time in which ink remaining in the inner wall of the nozzle 37 is exposed to outdoor air is reduced so that the sediment Sd is less likely to be generated near the nozzle opening 44. Consequently, flexure in the flying direction of ink droplets caused by the sediment Sd is reduced so that degradation of image quality can be suppressed. In this embodiment, since the potential difference Vd1 of the expansion element p1 of the driving pulse Pd is sufficiently smaller than the potential difference Vd2 of the contraction element p3, the amount of drawing of the meniscus M by the expansion element p1 is reduced. In this regard, this configuration contributes to suppression of generation of the sediment Sd. With a change of a driving frequency, the waveform of the driving pulse Pd may be corrected as necessary. For example, a driving voltage of the driving pulse Pd or a tilt (occurrence time) of each waveform element may be corrected. That is, the driving pulse Pd is preferably corrected so that the weight and the speed of flying of ink droplets discharged from the nozzle 37 are the same between before and after the change of the driving frequency.
It should be noted that if the driving frequency is excessively reduced to reduce the print speed, a throughput of a print operation (liquid droplet discharge operation) decreases accordingly so that a time from start to end of the print operation increases. In the nozzle 37 from which ink is not discharged in the print operation, the speed of increase in the viscosity of ink is higher than that in the nozzle 37 from which ink is frequently discharged. When the viscosity of ink in the nozzle 37 increases, in performing a discharge operation with this nozzle, ink droplets are not discharged from the nozzle or even if discharged, the weight of the discharged ink droplets decreases and/or the flying direction thereof flexes because of an increased viscosity of ink. Consequently, there arises a problem that an impact position is greatly shifted from a target position on a recording medium. In a case where the viscosity of ink has increased, the increased viscosity can be eliminated by performing a maintenance operation (cleaning operation) of forcefully sucking and discharging ink from the nozzle by using the capping mechanism 25. This cleaning operation, however, consumes a large amount of ink, and thus, the frequency of this cleaning operation needs to be as low as possible. The performance of capable of discharging ink without any problem even when the cleaning operation or ink discharge is not performed, will be hereinafter referred to as intermittent performance. From the viewpoint of suppressing reductions of throughput and intermittent performance, the driving frequency is preferably changed in an appropriate range.
From the table in
Other embodiments of the invention will now be described.
For example, in a case where the user selects a print speed (with a driving frequency of 42.5 [kHz]) 0.85 times as high as a maximum print speed (i.e., print speed with a driving frequency of 50 [kHz] in the example above), the user positions the slider 51 under this option (i.e., 0.85 times). When the printer driver 9 receives the option selected by the user (selection receiving step S2), selection information indicating which lower limit was selected by the user is then transmitted to the CPU 11 of the printer 3. In response to this, the printer 3 sets a driving frequency based on the selection information (frequency setting step S3). Specifically, the printer driver 9 indirectly reflects the selection information on setting of the driving frequency. In this manner, in the printer 3, even in a situation where the print speed is preferably lower than 0.85 times based on the temperature detected by the temperature sensor 40, a print operation is performed without reduction of the print speed to a degree below 0.85 times as the lower limit. In another case, if the user selects 1.00 time, a print operation is performed at a maximum print speed, independently of an environment temperature. In this manner, the user selects the lower limit of the print speed (driving frequency) so that a print operation satisfying the needs of the user can be performed. The series of processes of the printer driver 9 described above may be performed by the CPU 11 of the printer 3. Specifically, the CPU 11 causes the display device 41 provided in the body of the printer 3 to display a similar GUI, receives selection of a lower limit of the driving frequency by a user through the GUI, and reflects the lower limit on setting of a driving frequency of a driving pulse Pd by the driving signal generator 14. The other part of the configuration is similar to that of the first embodiment.
As described above, based on the premise that the driving frequency (print speed) is changed regularly, a user may select whether to permit an increase in the frequency of change of the driving frequency (print speed) or not. For example, in a manner similar to the second or third embodiment, the printer driver 9 causes an image display device, for example, to display a GUI as illustrated in
The environment information is not limited temperatures, and humidities may be employed. In this case, a threshold is set for a value detected by a humidity sensor in a manner similar to that in the case of temperatures. If the detected temperature is the threshold or less, the viscosity of ink is likely to increase and sediment is likely to be generated. Thus, control is performed to reduce the driving frequency. In this manner, generation of sediment in the nozzle is reduced under low humidity (under a dry environment), and flexure in the flying direction of ink droplets caused by the sediment is reduced so that image quality degradation is suppressed.
The driving pulse Pd is not limited to the examples illustrated in
In addition, in the above embodiments, the so-called flexural vibration piezoelectric element 20 is employed as an example of a driver element. Alternatively, a so-called vertical vibration piezoelectric element may be employed. In this case, the driving pulse Pd described in the above embodiment as an example has a waveform with a reversed direction of potential change, that is, a reversed vertical direction (polarity).
The invention is not limited to the printer 3 described above and is also applicable to various types of ink jet recording apparatuses such as a plotter, a facsimile machine, and a copying machine or liquid droplet discharge devices such as a textile printing device that causes ink to impact from a liquid discharge head onto fabric (textile printing target) that is a type of an impact target, as long as these devices are liquid discharge devices each having an uneven pattern on an inner wall surface of a nozzle. The invention is also applicable to a device driver for these devices.
The entire disclosure of Japanese Patent Application No. 2016-036139, filed Jan. 26, 2016 is expressly incorporated by reference herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-036139 | Feb 2016 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20100134560 | Doi | Jun 2010 | A1 |
| Number | Date | Country |
|---|---|---|
| 2007272680 | Apr 2013 | JP |
| 2015-223768 | Dec 2015 | JP |
| WO-2008-155986 | Dec 2008 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20170246893 A1 | Aug 2017 | US |
