JP2004034471A - Liquid ejection device - Google Patents

Abstract

An object of the present invention is to effectively remove a thickened ink and to prevent air bubbles from being taken into an ink flow path when performing a flushing operation.
A flushing device includes a nozzle, an ejection head for ejecting a liquid from the nozzle, and a supply unit for supplying a drive signal for driving the ejection head. In the liquid ejecting apparatus that performs the operation, the waveform of the drive signal for the flushing operation that is performed before and after is changed.
[Selection] Fig. 10

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid ejection device such as a printing device.
[0002]
[Background Art]
2. Description of the Related Art An inkjet printer as a printing apparatus includes an ejection head that ejects ink from nozzles, and prints images, characters, and the like by landing ink ejected from nozzles on a printing medium such as printing paper. The ejection head is mounted on a carriage that reciprocates in the main scanning direction, and ejects ink onto the printing paper while reciprocating in the paper width direction of the printing paper.
[0003]
The ejection head includes a plurality of nozzles, an ink passage communicating with each nozzle, and a piezoelectric vibrator that changes the pressure of the ink passage. The piezoelectric vibrator vibrates according to the print signal, and the vibration causes the pressure in the ink passage to fluctuate. Then, the ink in the ink passage is ejected from the nozzle by the pressure fluctuation.
[0004]
New ink is successively supplied to the nozzles that continuously eject ink by printing or the like, and thus thickened ink hardly occurs. On the other hand, a nozzle having a small chance of ejecting ink is likely to generate thickened ink due to drying of the ink. Further, in the printing apparatus, after printing is performed by making the ejection head make one reciprocation, the ejection head waits at the standby position until print data for the next one reciprocation is input. Even in the inside, the viscosity of the ink proceeds due to the drying of the ink. Then, as the viscosity increases, it causes ejection failure such as clogging and flight bending caused by convection of the thickened ink near the nozzle.
[0005]
Therefore, in the printing apparatus, a driving signal irrelevant to print data is applied to the piezoelectric vibrator to execute a flushing operation for removing the thickened ink near the nozzles and preventing the occurrence of printing failure. This flushing operation is performed at regular intervals (for example, about 9 seconds), before starting printing, after wiping the nozzle surface by the cleaning mechanism, and forcing ink in the ejection head while the nozzle surface is sealed by the capping mechanism. It is executed at an appropriate timing, such as after being extracted.
[0006]
[Problems to be solved by the invention]
Meanwhile, the flushing operation is performed by supplying a drive signal for causing the ejection head to perform the flushing operation. In each flushing operation, the waveform of the drive signal for the flushing operation supplied to the ejection head is the same, and each flushing operation is performed by the same operation each time.
[0007]
Here, the state of the thickened ink differs depending on the place and environment where the thickened ink is generated, and the flushing operation which has been effective for removing a certain thickened ink does not necessarily remove the thickened ink of another property. Is not always effective. Therefore, even if the flushing operation is repeatedly performed at intervals of time, the thickened ink may not always be effectively removed.
[0008]
This will be specifically described. For example, when a certain flushing operation partially removes the thickened ink present in the vicinity of the nozzle, thereby forming an opening portion, if a subsequent flushing operation is performed, the remaining thickened ink is easily removed. However, the ink continues to be ejected only from the opening portion, and the remaining thickened ink is not removed at all.
[0009]
FIG. 13 shows a nozzle, an ink passage 68 communicating with the nozzle, a piezo element PE for deforming the ink passage 68, ink filled in the ink passage 68, and the like, as shown in FIG. Even when the flushing operation is performed, the state in which the surface shape (meniscus) of the ink has entered so as to avoid the thickened ink mass 75 continues, the behavior of the surface shape 76 becomes extremely unstable, and the ejected ink becomes curved. And the ink cannot be stably ejected. Further, in the case of such a surface shape 76, bubbles may be taken into the ink passage 68, and these bubbles may hinder the effective removal of the ink.
[0010]
An object of the present invention is to provide a liquid ejection device capable of effectively removing a liquid.
[0011]
[Means for Solving the Problems]
A main invention of the present invention for achieving this object includes a nozzle, an ejection head for ejecting a liquid from the nozzle, and a supply unit for supplying a drive signal for driving the ejection head. What is claimed is: 1. A liquid ejecting apparatus which executes a flushing operation based on said drive signal at intervals, wherein the waveform of said drive signal for a flushing operation executed before and after is changed.
Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
=== Disclosure Overview ===
At least the following matters will be made clear by the description in the present specification and the accompanying drawings.
A nozzle, a discharge head for discharging liquid from the nozzle, and a supply unit for supplying a drive signal for driving the discharge head, wherein a flushing operation based on the drive signal is performed at time intervals. A liquid discharging apparatus, wherein a waveform of the driving signal for a flushing operation to be performed before and after is changed.
[0013]
Here, the liquid ejection device is, for example, a printing device such as an ink jet printer using ink as a liquid. In each flushing operation performed at intervals of time, if the waveform of the drive signal for the flushing operation supplied to the ejection head is the same and each flushing operation is performed by the same operation, the thickened liquid is not necessarily May not be removed effectively. Further, as a method of removing the thickening liquid more effectively, for example, there is a method of changing a drive signal during one flushing operation. However, in terms of a flushing operation unit, a drive signal of each flushing operation is considered. Are the same. Therefore, even if a thickening liquid having a specific shape or property can be effectively removed, it may not always be possible to effectively remove a thickening liquid having a different shape or property. For example, a thickening liquid that cannot be removed by a certain flushing operation may remain without being removed by a next flushing operation.
[0014]
On the other hand, in this liquid ejecting apparatus, since the flushing operation performed before and after is changed, it is possible to effectively remove various types of thickening liquids having different shapes and properties. . For example, a thickening liquid that could not be removed by a certain flushing operation can be effectively removed by the next flushing operation (a flushing operation different from the previous flushing operation).
[0015]
Here, the liquid ejection device includes not only a printing device such as an ink jet printer, but also, for example, a color filter manufacturing device, a dyeing device, a fine processing device, a semiconductor manufacturing device, a surface processing device, a three-dimensional modeling machine, a liquid vaporizing device, Includes general devices that can directly discharge (directly draw) liquid toward an object, such as an organic EL manufacturing device (especially a polymer EL manufacturing device), a display manufacturing device, a film forming device, and a DNA chip manufacturing device. It is. The liquid discharged from the liquid discharge unit may be, for example, a metal material, an organic material (especially a polymer material), a magnetic material, a conductive material, a wiring material, a film forming material, in addition to the dye ink or the pigment ink. There are various things such as liquids (including water) including electronic inks, processing liquids, gene solutions, and the like.
[0016]
In such a liquid ejection apparatus, the amplitude of the drive signal for a flushing operation to be performed before and after may be changed. By changing the amplitude of the drive signal S for the flushing operation executed before and after in this way, for example, it is possible to effectively remove various types of thickening liquids having different properties and shapes. Become.
[0017]
Further, in such a liquid ejection apparatus, the flushing operation is realized by supplying a plurality of continuous drive signals for ejecting liquid to the ejection head. The frequency of the drive signal may be changed. By changing the frequency of the drive signal S for the flushing operation performed before and after in this way, the natural frequency of each thickening liquid suitable for removing each of the various types of thickening liquids Vibration having a frequency equal to or close to the above can be applied to the thickening liquid, and the thickening liquid can be effectively removed.
[0018]
Further, the drive signal for each flushing operation may be changed so as to change the number of ejections in the flushing operation executed before and after. For example, when the thickening liquid cannot be sufficiently removed with a small number of ejections, the number of ejections can be increased to effectively remove the thickening liquid.
[0019]
Further, in such a liquid discharge device, a liquid passage may be communicated with the nozzle, and the drive signal for vibrating the liquid passage may be supplied during a period in which a flushing operation is not performed. Thus, the thickening liquid can be diffused even during a period in which the flushing operation is not performed, and the thickening liquid can be effectively removed.
[0020]
Further, in such a liquid ejection apparatus, printing is performed by ejecting ink while moving the ejection head, and the time when the movement of the ejection head is stopped is measured, and the time is measured before and after the measurement time. The driving signal for the flushing operation to be performed may be changed. By changing the number of ejections in this way, for example, an effect is obtained in which the thickened ink that could not be removed by the flushing operation based on the number of ejections can be easily removed with another number of ejections.
[0021]
Further, in such a liquid ejection apparatus, printing is performed by ejecting ink while moving the ejection head, and during a period between an execution period of a certain flushing operation and an execution period of a flushing operation performed subsequently, A period for the printing from the start of the movement of the ejection head to the stop thereof may be included. As a result, the flushing operation is performed before and after the printing operation, and the printing quality is improved.
[0022]
Further, in such a liquid ejection apparatus, when the timing of printing comes, the printing may be executed after the flushing operation is executed in advance. As a result, the flushing operation is always performed immediately before printing, and the print quality is improved and stabilized.
[0023]
=== Overview of Liquid Discharge Device ===
FIG. 1 is a schematic configuration diagram of a printing system including an ink jet printer 22 described as an example of a printing device that is one of the liquid ejection devices of the present invention. The printer 22 has a sub-scan feed mechanism that conveys the printing paper P by the paper feed motor 23 and a main scan feed mechanism that reciprocates the carriage 31 in the axial direction of the platen 26 by the carriage motor 24. Here, the feeding direction of the printing paper P by the sub-scanning feed mechanism is called a sub-scanning direction, and the moving direction of the carriage 31 by the main scanning feed mechanism is called a main scanning direction.
[0024]
The printer 22 drives a discharge head 60 (also referred to as a “discharge head assembly”) mounted on the carriage 31 to control ink discharge and dot formation, and a paper feed motor 23 and a carriage motor 24, a control circuit 40 for controlling the exchange of signals with the ejection head 60 and the operation panel 32. The control circuit 40 is connected to the computer 90 via the connector 56.
[0025]
The sub-scan feed mechanism that transports the printing paper P includes a gear train (not shown) that transmits the rotation of the paper feed motor 23 to the platen 26 and a paper transport roller (not shown). A main scanning feed mechanism for reciprocating the carriage 31 includes an endless drive belt 36 provided between the carriage motor 24 and a slide shaft 34 erected in parallel with the axis of the platen 26 and slidably holding the carriage 31. And a position detection sensor 39 for detecting the origin position of the carriage 31.
[0026]
=== Circuit configuration ===
FIG. 2 is a block diagram showing the configuration of the printer 22 with the control circuit 40 at the center. The control circuit 40 is configured as an arithmetic logic operation circuit including a CPU 41, a PROM 43, a RAM 44, and a character generator (CG) 45 storing a dot matrix of characters. The control circuit 40 further includes an I / F dedicated circuit 50 dedicated to interfacing with an external motor or the like, and a head drive connected to the I / F dedicated circuit 50 to drive the ejection head 60 to eject ink. A circuit 52 and a motor drive circuit 54 for driving the paper feed motor 23 and the carriage motor 24 are provided. The I / F dedicated circuit 50 has a built-in parallel interface circuit and can receive the print signal PS supplied from the computer 90 via the connector 56.
[0027]
=== Configuration of Discharge Head ===
The configuration of the ejection head 60 will be described with reference to FIGS. 3, 4, and 5. FIG. FIG. 3 is an explanatory diagram illustrating a schematic configuration inside the ejection head 60. FIG. 4 is an explanatory diagram showing the structure of the piezo element PE and the nozzle Nz in detail. FIG. 5 is an explanatory diagram showing the arrangement of the inkjet nozzles Nz in the ejection heads 61 to 66.
[0028]
On the carriage 31 (FIG. 1), a cartridge 71 for black ink (K) and five color inks of cyan (C), light cyan (LC), magenta (M), light magenta (LM), and yellow (Y) are provided. The stored color ink cartridge 72 can be mounted.
[0029]
A total of six ejection heads 61 to 66 are provided below the carriage 31, and an introduction pipe 67 (see FIG. 3) for guiding ink from the ink tank to each color ejection head is provided at the bottom of the carriage 31. Is provided. When the cartridge 71 for black (K) ink and the cartridge 72 for color ink are mounted on the carriage 31 from above, the introduction pipe 67 is inserted into the connection hole provided in each cartridge, and the ejection heads 61 to 66 are discharged from each ink cartridge. Can be supplied to the printer.
[0030]
When the ink cartridges 71 and 72 are mounted on the carriage 31, the ink in the ink cartridge is sucked out through the introduction pipe 67 as shown in FIG. Is led to.
[0031]
In each of the ejection heads 61 to 66 provided in the lower portion of the carriage 31, a piezo element PE, which is one of the electrostrictive elements and is a piezoelectric vibrator having excellent responsiveness, is arranged for each nozzle. Then, as shown in the upper part of FIG. 4, the piezo element PE is installed at a position in contact with the ink passage 68 that guides the ink to the nozzle Nz. As is well known, the piezo element PE is an element that distorts the crystal structure due to the application of a voltage and converts electro-mechanical energy very quickly. In this embodiment, by applying a voltage having a predetermined time width as a drive signal S between electrodes provided at both ends of the piezo element PE, the piezo element PE is extended by the voltage application time as shown in the lower part of FIG. Then, one side wall of the ink passage 68 is deformed. As a result, the volume of the ink passage 68 contracts in accordance with the expansion of the piezo element PE, and the ink corresponding to the contraction becomes the ink droplet Ip, and is discharged from the tip of the nozzle Nz at high speed. The ink droplets Ip penetrate into the printing paper P mounted on the platen 26 to form dots and perform printing.
[0032]
As shown in FIG. 5, the arrangement of the inkjet nozzles Nz in the ejection heads 61 to 66 is black (K), cyan (C), light cyan (LC), magenta (M), light magenta (LM), and yellow (Y). It is composed of six nozzle arrays that eject ink for each color, and 48 nozzles Nz are arranged in a line at a constant nozzle pitch k.
[0033]
The printer 22 is provided with a nozzle Nz having a constant diameter as shown in FIG. 5, but it is possible to form a plurality of types of ink droplets having different ink amounts using the nozzle Nz. This is performed by changing the drive waveform for driving the piezo element PE. Specifically, the change rate when the drive voltage of the piezo element PE is made negative is changed, or the peak voltage of the drive waveform is changed. By changing this, it is possible to form ink droplets having different amounts of ink with one nozzle.
[0034]
In the printer 22 having the hardware configuration described above, the carriage 31 is reciprocated by the carriage motor 24 while the paper P is being conveyed by the paper feed motor 23, and at the same time, the piezo elements PE of the ejection heads 61 to 66 are driven. Each color ink is ejected to form dots and form a multicolor image on the paper P.
[0035]
Here, as described above, the printer 22 having the head that discharges ink using the piezo element PE is used, but various discharge driving elements other than the piezo element can be used. It is. For example, the present invention can be applied to a printer having a discharge drive element of a type in which a heater disposed in an ink passage is energized and ink is discharged by bubbles generated in the ink passage. The configuration of the control circuit 40 also supplies a drive signal S to each ejection drive element, and selectively ejects one or more ink droplets from each nozzle. One that selectively records one of the dots and generates the drive signal S so as to keep the same sequential ejection order of a plurality of types of ink droplets in the forward scan and the return scan of the main scan. , Anything.
[0036]
=== Discharge head drive ===
Next, the driving of the ejection heads 61 to 66 will be described with reference to FIGS. FIG. 6 is a block diagram showing a configuration of the drive signal generator 200 provided in the head drive circuit 52 (FIG. 2). FIG. 7 is a timing chart showing the operation of drive signal generating section 200 shown in FIG.
[0037]
6, the drive signal generator 200 includes a plurality of mask circuits 204, an original drive signal generator 206, and a drive signal corrector 230. The mask circuit 204 is provided corresponding to a plurality of piezo elements PE for driving the nozzles n1 to n48 of the ejection head 61, respectively. In FIG. 6, the number in parentheses added to the end of each signal name indicates the number of the nozzle to which the signal is supplied. The original drive signal generator 206 generates an original drive signal ODRV commonly used for the nozzles n1 to n48. The original drive signal ODRV is a signal including two pulses of the first pulse W1 and the second pulse W2 within the main scanning period for one pixel. The drive signal correction unit 230 performs correction by shifting the timing of the drive signal waveform shaped by the mask circuit 204 back and forth over the entire return path. By the correction of the timing of the drive signal waveform, the deviation of the landing position of the ink droplet between the forward path and the return path is corrected, that is, the deviation of the dot formation position between the forward path and the return path is corrected.
[0038]
As shown in FIG. 6, the input serial print signal PRT (i) is input to the mask circuit 204 together with the original drive signal ODRV output from the original drive signal generator 206. This serial print signal PRT (i) is a 2-bit serial signal per pixel, and each bit corresponds to the first pulse W1 and the second pulse W2, respectively.
[0039]
The mask circuit 204 is a gate for masking the original drive signal ODRV according to the level of the serial print signal PRT (i) (i = 1 to 48). That is, when the serial print signal PRT (i) is at the 1 level, the mask circuit 204 passes the corresponding pulse of the original drive signal ODRV as it is and supplies it to the piezo element as the drive signal DRV, while the serial print signal PRT (i) ) Is at the 0 level, the corresponding pulse of the original drive signal ODRV is cut off.
[0040]
At the time of printing, as shown in FIG. 7A-1, as a pulse of the original drive signal ODRV, a first pulse W1 and a second pulse W2 are generated in this order in each of the pixel sections T1, T2, and T3. . The “pixel section” has the same meaning as the main scanning period for one pixel. As described above, the mask circuit 204 (FIG. 6) passes the pulse of the original drive signal ODRV as it is when the serial print signal PRT (i) is at one level, and outputs the original pulse when the serial print signal PRT (i) is at zero level. The pulse of the drive signal ODRV is cut off.
[0041]
Therefore, as shown in FIGS. 7A-2 and 7A-3, when the two bits of the serial print signal PRT (i) in each pixel section are "1, 0", only the first pulse W1 is generated. It is output in the first half of one pixel section. Thus, small dots having a small size are formed on the printing medium. When the value is "0, 1", only the second pulse W2 is output in the latter half of one pixel section. As a result, a medium-sized medium dot is formed on the printing medium. In addition, when it is “1, 1”, both the first pulse W1 and the second pulse W2 are output. As a result, large dots having a large size are formed on the printing medium.
[0042]
As can be understood from the outward drive signal waveform shown in FIG. 7A-3, the three drive signals DRV (i) for recording the three dots are the drive signals over one pixel section. The waveforms are shaped so that the waveforms are different from each other, that is, at least one of the size and the number of the ink droplets ejected from the nozzle is different. That is, the drive signal DRV (i) in one pixel section is shaped so as to have three different waveforms depending on three different values of the print signal PRT (i).
[0043]
The same drive signal waveform corresponding to each of these dots is used regardless of whether it is a forward scan or a return scan of main scanning. That is, the small ink droplets, the medium ink droplets, and the large ink droplets ejected from one nozzle in one pixel section are ejected in the same order and at the same time interval in the forward pass and the return pass. However, the same drive signal waveform is used for the forward scan and the return scan of the main scanning, but the timing is shifted forward and backward by the drive signal correction unit 230 (FIG. 7) throughout the return scan and corrected. Due to the correction of the timing, the landing positions of the ink droplets are intentionally shifted throughout the return path, and the deviation of the landing positions of the ink drops on the forward path and the return path is corrected.
[0044]
=== Carriage movement ===
FIG. 8 is a diagram for explaining the operation of the carriage 31 of the printer 22 in the main scanning direction. A flushing box 81 (ink receiver), which is a container for receiving ink ejected from the ejection head 60 by a flushing operation, is provided in a standby area within the movement range of the carriage 31. On the side of the flushing box 81 on the side of the printer 22, a cap 82 is provided adjacent to the flushing box 81 to prevent the nozzles Nz from drying during printing suspension or the like. A suction pump (not shown) is connected to the cap 82, and the suction pump applies a negative pressure to the nozzle Nz of the ejection head during cleaning to suck ink from the nozzle Nz.
[0045]
The carriage 31 starts moving from a stop state in the standby area, and performs printing by reciprocating in a print area on the recording paper. In the printer 22 of the present embodiment, each time one round trip printing is completed, the ejection head returns to the position of the flushing box 81 and stops moving, and waits for the next printing timing. The flushing operation is executed, for example, while the carriage 31 is waiting in the flushing box 81. If the standby time is long, the ejection head 60 returns to the position of the cap 82 and waits with the nozzle Nz sealed with the cap 82.
[0046]
=== Flushing operation ===
Specifically, the flushing operation, which is a function of the printer 22, is performed by inputting a drive signal S irrelevant to print data input from the computer 90 to the piezo element PE, thereby discharging ink from the nozzles Nz, This is an operation of removing the thickened ink in the vicinity. For example, the printer 22 performs the flushing operation during the waiting period until the ejection head 60 performs one round trip printing and returns to the standby area, print data for the next round trip is accumulated, and the printing operation is started again. .
[0047]
The flowchart in FIG. 9 describes an operation example when the printer 22 performs printing on the printing paper P. In a state where the printing of the printing paper P is completed (S211), the printer 22 determines whether or not there is the next print data (S212). If the next print data exists, the printing paper P is discharged, and the printing paper P is fed for the next printing (S213). On the other hand, if the next print data does not exist, the paper discharge operation is started (S214). Next, the printer moves the carriage 31 (S215), and drives the paper feed motor 23 (S216). Then, a flushing operation is executed in conjunction with the start of driving of the paper feed motor 23 (S216, S217). In addition to the above-described case, the printer 22 may operate, for example, before the start of the printing operation, periodically (for example, about once every 9 seconds) with a time interval, or a preset non-printing operation. Run at regular time intervals.
[0048]
=== Drive waveform ===
By the way, in a series of flushing operations that the printer 22 performs periodically or irregularly at intervals of time, if the flushing operations performed before and after are performed by the same operation every time, the thickened ink is not necessarily effective. May not be removed. Therefore, in the printer 22 of the present embodiment, in the flushing operation performed before and after, the flushing operation performed before and after is changed by changing the waveform of the drive signal S for each flushing operation, and the thickened ink is printed. Is effectively removed. Hereinafter, this mechanism will be described.
[0049]
FIGS. 10A to 10D exemplarily show the waveforms of the drive signal S for the flushing operation executed before and after at a time interval. In FIGS. 10A to 10D, the drive signal S in the time section indicated by X corresponds to one flushing operation.
FIG. 10A changes the amplitude of the drive signal S for two flushing operations to be performed before and after. In this example, the amplitude of the drive signal S for the flushing operation performed later is set to be larger than the amplitude of the drive signal S for the flashing operation performed earlier. The magnitude of the amplitude of the drive signal S for the flushing operation to be executed before and after may be set arbitrarily. For example, the amplitude of the later drive signal S is smaller than that of the earlier drive signal S May be set to be smaller than the amplitude.
[0050]
By changing the amplitude of the drive signal S for the flushing operation executed before and after in this way, for example, it is possible to effectively remove various types of thickened ink having different properties and shapes. .
[0051]
Further, the flushing operation can be realized by supplying a plurality of continuous drive signals for discharging liquid to the discharge head. For example, FIG. 10B shows a case where the frequency of the drive signal S for two flushing operations to be executed before and after is changed, and the waveform of the drive signal S in this figure is a time section in the figure. The drive signal having the waveform appearing in Y is a waveform having a configuration that appears continuously during the time section X.
[0052]
Here, in this example, the frequency of the drive signal S for the flushing operation performed later is higher than the frequency of the drive signal S for the flushing operation performed earlier, that is, in the time interval Y of the flushing operation performed later. The length is set so as to be shorter than the length of the time section Y in the previously performed flushing operation. The magnitude of the frequency of the drive signal S for the flushing operation to be executed before and after may be set arbitrarily. For example, the amplitude of the later drive signal S is smaller than the earlier drive signal S May be set so as to be lower than the frequency.
[0053]
Here, the thickening ink generated in the vicinity of the nozzle Nz has a natural frequency determined by its property, shape, and the like. Therefore, in order to effectively remove various types of thickening ink, individual inks are required. It is effective to apply vibration having a frequency equal to or close to the natural frequency of the thickened ink so that the thickened ink efficiently absorbs vibration energy and effectively vibrate the thickened ink. By changing the frequency of the drive signal S for the flushing operation performed before and after in this way, the natural frequency of each thickened ink suitable for removing each of the various types of thickened inks Can be applied to the thickened ink, and the thickened ink can be effectively removed.
[0054]
FIG. 10C shows a case where the waveforms of the respective drive signals S are changed so that the respective ejection numbers are different in the two flushing operations executed before and after. Is a waveform in which the drive signal having the waveform appearing in the time section Y in the figure continuously appears during the time section X.
[0055]
Here, in this example, a drive signal S having a waveform for performing a flushing operation for ejecting ink n times is used as a drive signal S for a flushing operation performed earlier, and m (n < m) A drive signal having a waveform for executing a flushing operation for ejecting ink twice is supplied. In addition, the magnitude of the number of discharges of the flushing operation performed before and after may be set arbitrarily. The drive signal S may be set to be smaller.
[0056]
By changing the number of ejections in this manner, for example, an effect may be obtained in which the thickened ink that could not be removed by the flushing operation based on the number of ejections can be easily removed with another number of ejections. Ink can be effectively removed.
[0057]
By the way, in the above, the case where only the amplitude, the frequency, and the number of ejections among the elements for determining the waveform of the drive signal S are changed has been illustrated, but the waveform of the drive signal S is changed by combining these. Is also good. Further, in the examples of FIGS. 7A to 7C, the drive signal S is described as a binary drive signal S as the waveform, but the waveform is limited to such a simple waveform. Instead, the shape may be any other shape such as a mathematical function shape such as a trigonometric function shape or a shape obtained by combining these mathematical functions. In an actual product, for example, a waveform as shown in FIG. In the example of this figure, the amplitude of the waveform of the drive signal S for the flashing operation performed later is set to be larger than the amplitude of the waveform of the drive signal S for the flashing operation performed earlier. This is the case, and the waveform of the drive signal S in this figure is such that the drive signal having the waveform appearing in the time section Y in the figure appears continuously during the time section X.
[0058]
In the above, the case where the waveform of the drive signal S for the flushing operation executed before and after is changed has been described as an example, but a series of three or more times executed periodically or irregularly at time intervals is described. In the flushing operation described above, the drive signal S in each flushing operation may be changed so as to change the flushing operation to be executed before and after. This makes it possible to effectively remove various types of thickened ink.
[0059]
The time during which the carriage 31 waits in the standby area may be measured, and the waveform of the drive signal S for the flushing operation may be changed according to the measured standby time. For example, in the case where the degree of progress of the thickened ink changes according to the length of time during which the movement of the ejection head is stopped, this method can effectively remove the thickened ink. Thus, wasteful consumption of ink can be suppressed. In addition, the waveform of the drive signal S for the flushing operation to be executed before and after may be changed according to the measurement time, the number of ink ejections during the printing operation, the type of ink, and the manner of changing the waveform. It may be. In this manner, various types of thickened ink can be more effectively removed.
[0060]
The drive signal S for vibrating the ink passage 68 may be supplied during a period in which the flushing operation is not performed. In this case, in order to prevent the ink from being wasted, it is preferable that the vibration is a minute vibration that does not cause the ink to be ejected. By vibrating the ink passage 68 during the period in which the flushing operation is not performed, vibration is applied to the thickened ink, whereby the thickened ink can be effectively removed. The diffusion of the thickened ink proceeds by the fine vibration operation, and the thickened ink can be more effectively removed during the flushing operation.
[0061]
The period between the execution period of a certain flushing operation and the execution period of the flushing operation that is performed subsequently thereto includes the period for the printing from the start of the movement of the ejection head to the stop thereof. It may be. As a result, the flushing operation is performed before and after the printing operation, and the printing quality is improved. Further, when the timing of printing has come, the printing may be executed after the flushing operation is executed in advance. As a result, the flushing operation is always performed immediately before the printing operation, so that the printing quality is improved and the printing quality can be maintained at a certain level or more.
[0062]
The waveform of the drive signal S may be changed or the waveform may be changed according to the properties of the ink, the state of thickening, the way of thickening, the power consumption of the printer, and the like. Alternatively, the waveform of the drive signal S may be changed or the manner of changing the waveform may be changed using environmental factors such as temperature and humidity detected using a sensor or the like as parameters. By using various factors as parameters as described above, it is possible to effectively remove the thickened ink.
[0063]
=== Configuration of Computer System, etc. ===
Next, an embodiment of a computer system, a computer program, and a recording medium on which the computer program is recorded as an example of an embodiment according to the present invention will be described with reference to the drawings.
[0064]
FIG. 11 is an explanatory diagram showing the external configuration of the computer system. The computer system 1000 includes a computer main body 1102, a display device 1104, a printer 1106, an input device 1108, and a reading device 1110. In the present embodiment, the computer main body 1102 is housed in a mini-tower type housing, but is not limited to this. The display device 1104 generally uses a cathode ray tube (CRT), a plasma display, a liquid crystal display device, or the like, but is not limited thereto. As the printer 1106, the printer described above is used. In the present embodiment, the input device 1108 uses the keyboard 1108A and the mouse 1108B, but is not limited thereto. In the present embodiment, the reading device 1110 uses the flexible disk drive device 1110A and the CD-ROM drive device 1110B, but is not limited thereto. For example, an MO (Magnet Optical) disk drive device or a DVD (Digital Versatile) is used. Disk).
[0065]
FIG. 12 is a block diagram showing a configuration of the computer system shown in FIG. An internal memory 1202 such as a RAM and an external memory such as a hard disk drive unit 1204 are further provided in a housing in which the computer main body 1102 is stored.
[0066]
In the above description, an example in which the printer 1106 is connected to the computer main body 1102, the display device 1104, the input device 1108, and the reading device 1110 to form a computer system has been described. However, the present invention is not limited to this. Absent. For example, the computer system may include the computer main body 1102 and the printer 1106, and the computer system may not include any of the display device 1104, the input device 1108, and the reading device 1110. Further, for example, the printer 1106 may have some of the functions or mechanisms of the computer main body 1102, the display device 1104, the input device 1108, and the reading device 1110. As an example, the printer 1106 includes an image processing unit for performing image processing, a display unit for performing various displays, and a recording medium attaching / detaching unit for attaching / detaching a recording medium for recording image data captured by a digital camera or the like. May be provided.
[0067]
In the above-described embodiment, the computer program for controlling the printer may be stored in the ROM 43 of the control circuit 40. Further, the computer program in the ROM 43 may be loaded into the RAM 44 and executed. Then, the control circuit 40 may execute the computer program to achieve the operation of the printer in the above-described embodiment.
[0068]
The computer system implemented in this way is a system superior to the conventional system as a whole.
[0069]
=== Others ===
As described above, the liquid ejection device according to the present invention has been described based on one embodiment. However, the above embodiment of the present invention is for facilitating understanding of the present invention, and is not intended to limit the present invention. Absent. The present invention can be modified and improved without departing from the gist of the present invention, and the present invention naturally includes equivalents thereof.
[0070]
Although the printing medium has been described as an example of a printing medium, a film, cloth, a thin metal plate, or the like may be used as the printing medium.
[0071]
Further, a computer main body, the printer according to the above-described embodiment connected to the computer main body, an input device such as a mouse and a keyboard provided as necessary, a display device such as a CRT, a flexible disk drive device, and a CD -A computer system having a ROM drive device is also feasible, and the computer system implemented in this way is a system superior to the conventional system as a whole system.
[0072]
The printer according to the above-described embodiment may have some of the functions or mechanisms of the computer body, the display device, the input device, the flexible disk drive device, and the CD-ROM drive device. For example, a configuration in which the printer includes an image processing unit that performs image processing, a display unit that performs various displays, and a recording medium attaching / detaching unit for attaching / detaching a recording medium that records image data captured by a digital camera or the like. Is also good.
[0073]
In the above embodiment, a color inkjet printer has been described. However, the present invention is applicable to a monochrome inkjet printer, and is also applicable to printers other than the inkjet type. INDUSTRIAL APPLICABILITY The present invention is generally applicable to a printing apparatus that performs printing on a printing medium, and is also applicable to, for example, a facsimile apparatus and a copying machine. However, in a so-called ink jet type printing apparatus that performs printing by discharging ink from a discharge head, particularly, it is required to improve the image quality of a printing result.
In the above embodiment, a part of the configuration realized by hardware may be replaced with software, and conversely, a part of the configuration realized by software may be replaced with hardware. .
[0074]
【The invention's effect】
According to the liquid ejection device of the present invention, the liquid can be effectively removed.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a printing system including an inkjet printer according to an embodiment of the present invention.
FIG. 2 is a block diagram of a control circuit according to one embodiment of the present invention.
FIG. 3 is a diagram showing a schematic configuration inside a discharge head according to an embodiment of the present invention.
FIG. 4 is a diagram illustrating a structure of a piezo element and a nozzle according to an embodiment of the present invention.
FIG. 5 is a diagram showing an arrangement of inkjet nozzles in a discharge head according to one embodiment of the present invention.
FIG. 6 is a block diagram showing a configuration of a drive signal generator provided in a head drive circuit according to one embodiment of the present invention.
FIG. 7 is a timing chart showing an operation of a drive signal generator according to one embodiment of the present invention.
FIG. 8 is a diagram illustrating the operation of the carriage in the main scanning direction according to one embodiment of the present invention.
FIG. 9 is a flowchart illustrating an operation example when a printer performs printing on print paper according to an embodiment of the present invention.
FIG. 10 is a timing chart showing a waveform of a drive signal for a flushing operation performed before and after at a time interval according to an embodiment of the present invention.
FIG. 11 is an explanatory diagram showing an external configuration of a computer system.
FIG. 12 is a block diagram showing a configuration of the computer system of FIG.
FIG. 13 is a diagram illustrating a state of a nozzle, an ink passage communicating with the nozzle, a piezo element, ink filled in the ink passage, and the like in a conventional inkjet printer.
[Explanation of symbols]
22 Inkjet Printer
23 Paper feed motor
24 Carriage motor
26 Platen
31 carriage
32 Operation panel
40 control circuit
41 CPU
43 PROM
45 Character Generator
50 I / F dedicated circuit
52 Head drive circuit
54 Motor drive circuit
60 Discharge head
61-66 Discharge head
67 Introduction pipe
68 Ink passage
71,72 Ink cartridge
81 Flushing Box
82 cap
90 Computer
200 drive signal generator
S drive signal
PE piezo element
Nz inkjet nozzle
Ip ink drop

Claims (10)

A nozzle, a discharge head for discharging liquid from the nozzle, and a supply unit for supplying a drive signal for driving the discharge head, wherein a flushing operation based on the drive signal is performed at time intervals. A liquid ejection device,
A liquid ejecting apparatus, wherein a waveform of the drive signal for a flushing operation to be executed before and after is changed. 2. The liquid ejecting apparatus according to claim 1, wherein an amplitude of the drive signal for a flushing operation performed before and after is changed. 3. The liquid ejecting apparatus according to claim 1, wherein a frequency of the drive signal for a flushing operation performed before and after is changed. 4. The liquid ejecting apparatus according to claim 1, wherein the drive signal for each flushing operation is changed so as to change the number of ejections in the flushing operation executed before and after. Liquid ejection device. 5. The liquid ejection device according to claim 1, wherein a liquid passage communicates with the nozzle, and the drive signal for vibrating the liquid passage during a period in which a flushing operation is not performed is supplied. A liquid discharge device characterized by the above-mentioned. The liquid ejecting apparatus according to any one of claims 1 to 5, wherein printing is performed on a printing medium by ejecting ink. The liquid ejection device according to claim 6,
Printing is performed by discharging ink while moving the discharge head,
A liquid discharge apparatus, wherein a time during which the movement of the discharge head is stopped is measured, and the drive signal for the flushing operation executed before and after is measured in accordance with the measured time. The liquid ejection device according to claim 6, wherein:
Printing is performed by discharging ink while moving the discharge head,
The period between the execution period of a certain flushing operation and the execution period of the flushing operation performed subsequently includes the period for the printing from the start of the movement of the ejection head to the stop thereof. A liquid discharge device characterized by the above-mentioned. 9. The liquid ejecting apparatus according to claim 6, wherein when the timing of the printing arrives, the flushing operation is executed before the printing is executed. 10. The liquid ejection device according to claim 1, wherein the flushing operation is realized by supplying a plurality of continuous drive signals for ejecting liquid to the ejection head. A liquid discharge device characterized by the above-mentioned.

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