JP2003291334A - Ink jet recorder and method for driving recording head in ink jet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet recorder in which print quality can be enhanced furthermore by controlling the quantity of ink being ejected by one shot from the nozzle opening of a recording head to be equalized substantially. <P>SOLUTION: A driving signal generating circuit 85 for supplying a driving signal to the piezoelectric oscillator 25 in a recording head 8 is mounted on a print control means 64. The driving signal generating circuit 85 is provided with driving information of each ink from a driving information storage means 86. Consequently, the piezoelectric oscillator 25 is provided with a driving signal such that ink ejection by one shot is substantially equalized depending on respective inks. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus capable of compensating an appropriate ink droplet ejection amount from a recording head, thereby improving print image quality, and a recording head in the apparatus. Driving method.

[0002]

2. Description of the Related Art For example, a serial printing type ink jet recording apparatus carries an ink jet type recording head mounted on a carriage and reciprocating in a main scanning direction, and a recording sheet in a sub scanning direction orthogonal to the main scanning direction. A paper feeding unit is provided, and printing is performed on the recording paper by ejecting ink droplets from the recording head based on the print data. Then, in the recording apparatus having the above-mentioned configuration, at least black, cyan, magenta, and yellow inks are used,
Not only text printing with black ink but also full-color printing is possible by changing the ejection ratio of each ink.

On the other hand, the recording head is provided with a pressure chamber communicating with the nozzle opening and an actuator for changing the ink pressure in the pressure chamber by expanding and contracting the pressure chamber, for example, a piezoelectric piezoelectric vibrator. Has been. In such a recording head, the ink pressure is changed by supplying a series of drive signals to the piezo-piezoelectric vibrator, whereby ink droplets can be ejected from the nozzle openings.

Then, for example, the print control data sent from the host computer is expanded into bit map data by the print control means, and based on the bit map data, the piezoelectric vibrators arranged in the respective pressure chambers are driven. Whether or not to apply the signal is controlled so that a predetermined image is printed.

[0005]

By the way, in recent years, with the diversification of printing, a recording apparatus using an ink (hereinafter, referred to as a pigment ink) in which a pigment is dispersed as a coloring material is used in place of a conventional dye ink. It is provided. In this pigment ink, it is generally observed that the apparent viscosity decreases as the shear rate increases. This characteristic is
Depending on the type of colorant used for dispersion or the concentration of colorant,
The degree is different.

Therefore, even if the range of the shear rate is narrow, or even if the viscosities are matched under a specific condition, the apparent viscosity is observed in the area where the drive frequency of the recording head is different (that is, the area where the shear rate is different). However, even when the same stress (shear stress) is applied, different amounts of ink are ejected between the inks.

The above-mentioned shear stress and apparent viscosity,
And the relationship with the shear rate can be generally expressed as shear stress (γ) = apparent viscosity × shear rate (Γ). Therefore, the relationship between the viscosity and the shear stress can be expressed as shown in FIG. The characteristic g shown in FIG. 9 shows the typical physical properties of the pigment ink as described above, and the characteristic n shows the physical properties of the Newtonian fluid represented by fresh water. That is, unlike Newtonian fluid, the apparent viscosity of pigment ink decreases on the high shear stress side.

In the above-mentioned ink jet recording apparatus, ink droplets are ejected by different shear stress in each printing mode. further,
The characteristic indicated by g is the type of pigment ink (for example,
Since there is a difference depending on the black, cyan, magenta, and yellow inks described above, there is a problem in that the ejection amount of the ink droplets varies for each color, making it difficult to obtain higher quality print results. .

However, in the past, the idea of controlling the discharge amount of ink droplets by adjusting the apparent ink viscosities corresponding to a certain constant shear stress has been adopted. That is, as shown as the print mode in FIG. 10, the viscosity is adjusted at one point where the shear stress (driving frequency) is present. Therefore, in the print mode as shown in FIG. 10, the ink A and the ink B are adjusted by adjusting the viscosity of the ink.
Although the same ejection amount can be obtained between the inks, the apparent viscosity of the ink A and the ink B are different in the print mode in the high shear region, that is, the high drive frequency region. It is inevitable that the discharge amount of the ink will vary.

The present invention has been made in view of the above-mentioned problems, and it is possible to compensate an appropriate ink droplet ejection amount from a recording head according to the ink used in a recording apparatus. Accordingly, it is an object of the present invention to provide an ink jet recording apparatus and a method of driving a recording head in the apparatus, which can further improve the print image quality.

The ink jet recording apparatus according to the present invention, which has been made to achieve the above-mentioned object, prints on a recording medium by ejecting a plurality of different kinds of ink as ink droplets based on print data. An ink jet type recording apparatus equipped with a recording head for
A drive signal that is controlled so as to reduce the difference in ink ejection amount caused by the difference in apparent viscosity based on the difference in shear stress between the different types of ink is arranged corresponding to the nozzle opening of the recording head. It is characterized in that it is provided with a drive signal generating means for supplying to each of the generated actuators.

In this case, preferably, the recording head is
Different types of ink are ejected for each nozzle row, and the drive signal generating means is controlled so as to reduce the difference in ink ejection amount for each actuator corresponding to each nozzle row. It is configured to respectively supply the drive signals.

And in a preferred embodiment,
The drive signal generating means selects one of a plurality of preset basic drive waveform signals, or selects a plurality of preset basic drive waveform signals to determine the difference in the ink ejection amount. Is configured to generate the drive signal that is controlled to reduce In another preferred embodiment, the drive signal generating means changes the voltage level of the drive signal, or selects drive signals of a plurality of voltage levels set in advance, thereby ejecting the ink. Is configured to generate the drive signal that is controlled to reduce the difference.

In this case, the information of the apparent viscosity based on the difference in shear stress can be read out from the data storage means mounted on the ink cartridge mounted on the recording apparatus, and the drive signal generation is performed. The means is
It is possible to preferably employ a configuration in which the drive signal controlled corresponding to each ink is generated based on the information read from the data storage unit.

Further, the drive signal generating means outputs the drive signal controlled corresponding to each ink based on information of apparent viscosity based on the difference in shear stress manually set for the recording apparatus. The configuration to generate can also be suitably adopted. In this case, the manual setting is preferably performed by a drive condition selecting unit installed in the recording apparatus or a drive condition selecting unit executed by a utility of a printer driver installed in a host computer that issues a print command to the recording apparatus. Is made by.

In another aspect of the ink jet recording apparatus according to the present invention, the nozzle diameters of the nozzle openings are different depending on the inks of different types ejected from the nozzle openings of the recording head. It is characterized in that it is configured by Also in this case, preferably, the recording head is configured so that different inks are ejected for each nozzle row, and the opening diameter of the nozzle opening is made different for each nozzle row.

Whichever of the above-mentioned constitutions is adopted, it can be suitably adopted for a recording apparatus using a pigment dispersion type ink as each ink introduced into the recording head.

On the other hand, the recording head driving method according to the present invention is equipped with a recording head for printing on a recording medium by ejecting a plurality of different kinds of ink as ink droplets based on print data. A method of driving a recording head in an ink jet recording apparatus, comprising: an information acquisition step of acquiring information on viscosity characteristics of respective inks of different types introduced into the recording head; and each ink acquired by the information acquisition step. A driving condition setting step for setting driving conditions corresponding to the viscosity characteristic information to the driving signal generating means based on the viscosity characteristic information of
According to the drive condition set by the drive condition setting step, a drive signal corresponding to the viscosity characteristic is output from the drive signal generation means to each actuator corresponding to a nozzle opening from which different types of ink are ejected. The step of supplying the drive signal and the step of supplying the drive signal are sequentially executed.

In this case, in a preferred aspect, in the information acquisition step, viscosity information corresponding to shear stress is respectively acquired as the viscosity characteristic information of each ink, and in the drive condition setting step, the shear stress is corresponded. The drive condition is set for the drive signal generating means based on the viscosity information.

According to the ink jet type recording apparatus of the present invention which employs the above-mentioned driving method, the driving signal generating means ejects ink caused by a difference in apparent viscosity based on a difference in shear stress between inks of different types. Each of the drive signals is controlled to reduce the difference in quantity. Then, the drive signals are supplied to the actuators arranged corresponding to the nozzle openings for ejecting the inks of different types.

That is, considering the case where the drive signal generated by the drive signal generating means is corrected so as to reduce the difference in the ink ejection amount by controlling the drive voltage, the drive signal voltage level before the correction is changed. If V1, the corrected drive signal voltage level is V2, and the drive frequency is f, then V
It can be shown by a relational expression of 2 = K × f × V1. Here, K is a coefficient determined by the type of ink and the composition of the ink, and this coefficient K may be a coefficient relative to one ink used for ejection, when the ink is used as a reference. . As shown in the above relational expression, the correction of the drive voltage is increased as the drive frequency becomes higher.

This makes it possible to adjust the amount of ink ejected in one shot corresponding to each pigment ink, and to use pigment inks having different apparent ink viscosities based on the difference in shear stress. The amount of ink ejected in one shot can be made equal. As a result, it is possible to provide an ink jet recording apparatus capable of further improving the print image quality.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION An ink jet recording apparatus according to the present invention will be described below based on the embodiments shown in the drawings. FIG. 1 is a perspective view showing the basic structure of a recording apparatus main body to which the present invention is applied. Figure 1
In FIG. 1, reference numeral 1 is a carriage, and this carriage 1
Is configured to be guided by a guide member 4 via a timing belt 3 driven by a carriage motor 2 to reciprocate in the main scanning direction along the longitudinal direction of the paper feed member 5.

A paper feed roller 6 is arranged on the paper feed member 5, and the recording paper 7 sandwiched by the paper feed roller 6 and a driven roller (not shown) is fed by the paper feed roller 6
It is configured to be conveyed in the sub-scanning direction orthogonal to the above-mentioned main scanning direction by the rotational drive of. in this case,
A large number of protrusions 5a are intermittently formed on the upper surface of the paper feed member 5 along the longitudinal direction, and the recording paper 7 is conveyed along the upper faces of the protrusions 5a, which will be described later. A predetermined gap is formed between the recording head and the recording head.

On the other hand, an ink jet type recording head 8 is mounted on the lower side surface of the carriage 1 facing the recording sheet 7 as shown by a broken line. Further, a black ink cartridge 9B for supplying ink to the recording head 8 and color ink cartridges 9C, 9M, 9Y enclosing cyan, magenta, and yellow inks, respectively, are adjacent to each other in the main scanning direction on the upper part thereof. Thus, it is detachably attached.

In the figure, reference numeral 11 is a capping means arranged in the non-printing area (home position). When the recording head 8 moves directly above, the capping means 11 moves upward to move the recording head. Nozzle formation surface (lower surface of the recording head 8 in this embodiment)
Is configured to be able to be sealed. The capping means 1 is provided below the capping means 11.
A suction pump 12 for applying a negative pressure to the internal space 1 is arranged.

The capping means 11 functions as a lid for sealing the nozzle forming surface of the recording head 8 to suppress the evaporation of the ink solvent from the nozzle openings during the rest period of the recording apparatus, and the suction pump. By applying a negative pressure from 12 to the recording head 8 to suck and discharge the ink from the recording head, a cleaning operation for maintaining the ink droplet ejection function is also executed.

As shown in FIG. 1, a wiping member 13 formed of an elastic material such as rubber in a strip shape is arranged on the side of the printing area adjacent to the capping means 11, and the carriage 1 is on the side of the capping means 11. When reciprocating, the wiping operation of moving the recording head in the horizontal direction in the horizontal direction and wiping the nozzle forming surface of the recording head 8 for cleaning is performed as necessary.

FIG. 2 schematically shows a nozzle forming surface of an example of the recording head 8 loaded in the recording apparatus shown in FIG. The recording head 8 has, for example, 48 or 64 later-described nozzle openings formed in rows in the sub-scanning direction, and the nozzle rows K, C, M, Y are respectively formed.
The nozzle rows are arranged adjacent to each other in the main scanning direction in correspondence with the number of inks used in the recording apparatus (four in this embodiment).

That is, in this embodiment, as shown in FIG. 2, a nozzle row K for ejecting black ink, a nozzle row C for ejecting cyan ink, and a nozzle row for ejecting magenta ink in order from the left in the main scanning direction. Nozzle rows Y for ejecting M and yellow ink are respectively arranged.

FIG. 3 is a sectional view showing a detailed partial structure of the recording head 8. The recording head 8 illustrated in FIG. 3 is a recording head having a flexural vibration mode piezoelectric vibrator 25 attached thereto. The recording head 8 includes an actuator unit 3 having a pressure chamber 31 formed therein.
2, a flow path unit 33 joined to the front surface of the actuator unit 32, and an actuator unit 32.
On the back surface of the, a piezoelectric piezoelectric vibrator 25 formed corresponding to the pressure chamber 31 is provided.

The actuator unit 32 includes the pressure chamber 3
1, the pressure chamber forming substrate 34, the lid member 35 joined to the front surface of the pressure chamber forming substrate 34, and the rear face of the pressure chamber forming substrate 34 to close the rear side opening surface of the pressure chamber 31. It is composed of a diaphragm 36. The diaphragm 3
6 is composed of, for example, a thin ceramic plate having elasticity. Further, the lid member 35 is formed with a first ink flow path 37 and a second ink flow path 38 communicating with the pressure chamber 31. The flow path unit 33 includes an ink chamber forming substrate 40, a nozzle plate 41 joined to the front surface of the ink chamber forming substrate 40, and a supply port forming plate 42 joined to the back surface of the ink chamber forming substrate 40. Has been done.

The common ink chamber 4 is formed on the ink chamber forming substrate 40.
3 and the nozzle communication port 44 are formed, and the nozzle plate 41 has a large number of nozzle openings 16 arranged in a line (for example, 48 or 64 as described above).
It is drilled. Then, each nozzle opening 16 is
The nozzles 44 communicate with the corresponding nozzle communication ports 44.
Further, the common ink chamber 43 and the first
An ink supply port 45 that communicates with the ink flow path 37 is formed, and the nozzle communication port 44 and the second ink flow path 3 are formed.
A communication port 46 that communicates with 8 is formed.

In the recording head 8 having the above-described structure, the common ink chamber 43, the ink supply port 45, the first ink passage 37, the pressure chamber 31, the second ink passage 38,
A series of ink flow paths are formed through the communication port 46 and the nozzle communication port 44 to reach the nozzle opening 16.

On the other hand, the piezoelectric vibrator 25 is arranged on the back side of the pressure chamber 31 with the vibration plate 36 interposed therebetween. A lower electrode 50 is formed on the front surface of the piezoelectric vibrator 25, and an upper electrode 51 is formed on the back surface so as to cover the piezoelectric vibrator 25. Further, at both ends of the actuator unit 32, connection terminals 52 whose base end portions are electrically connected to the upper electrodes 51 of the respective piezoelectric vibrators 25 are arranged. This connection terminal 5
A flexible circuit board 53 is bonded to the front end surface of the second electrode 2, and a drive signal is supplied to the piezoelectric vibrator 25 via the connection terminal 52 and the upper electrode 51.

In the recording head 8 having such a structure, a potential difference is generated between the upper electrode 51 and the lower electrode 50 when a drive signal as described later is supplied. Due to this potential difference, the piezoelectric vibrator 25 contracts, for example, in the direction orthogonal to the electric field, and the piezoelectric vibrator 25 and the vibrating plate 36 bend so as to project toward the pressure chamber 31 side and contract the pressure chamber 31.

When ejecting ink droplets from the nozzle openings 16, for example, the pressure chamber 31 is rapidly contracted. That is, when the pressure chamber 31 is abruptly contracted, the ink pressure in the pressure chamber 31 rises, and as the pressure rises, ink droplets are ejected from the nozzle openings 16. Also,
If the potential difference between the upper electrode 51 and the lower electrode 50 is eliminated after the ink droplets are ejected, the piezoelectric vibrator 25 and the diaphragm 3
6 returns to the original state. As a result, the contracted pressure chamber 31 expands, and ink is replenished from the common ink chamber 43 into the pressure chamber 31 through the ink supply port 45 and the first ink flow path 37.

Next, FIG. 4 is a block diagram showing an example of a control circuit mounted on the recording apparatus having the above-mentioned structure. Note that, in FIG. 4, parts corresponding to the parts already described are denoted by the same reference numerals, and therefore detailed description thereof will be omitted. In FIG. 4, the suction pump 12
Waste tank 14 for discharging the ink waste liquid sucked by
Is shown, and the ink waste liquid discharged to the waste liquid tank 14 is the waste liquid absorbing material 1 stored in the waste liquid tank 14.
5 is configured to be held.

Reference numeral 60 shown in FIG. 4 is a host computer, and a printer driver 61 is mounted on the host computer 60. Then, using the input device 62 and the display 63 on the utility of the printer driver 61, a known paper size, monochrome /
Color printing selection, recording mode selection, font data and print commands can be input.

By inputting a print command from the input device 62, print data is sent from the printer driver 61 to the print control means 64 mounted on the recording device. The print control means 64 generates bitmap data based on the print data from the host computer 60 and causes the head drive means 65 to generate a drive signal based on the data, and the recording head mounted on the carriage 1. 8 has a function of ejecting ink droplets. The head drive means 65 is also configured to receive a flushing command signal from the flushing control means 66 and output a drive signal for a flushing operation to the recording head 8 in addition to the drive signal based on the print data.

Reference numeral 67 is a cleaning control means,
The cleaning control means 67 is a pump drive means 68.
Is started and the suction pump 12 is operated. Then, for example, the cleaning operation is executed in response to a command signal from the cleaning command detecting means 70 which has received an ON operation of the cleaning command switch 69 arranged on the operation panel. Further, the cleaning control means 67
Even when a cleaning command is received from the above-mentioned host computer via the central control means 71,
Similarly, it has a function of executing a cleaning operation.

Further, a control signal is sent from the central control means 71 to the carriage motor control means 72, whereby the carriage motor 2
Is driven to control the carriage 1 to move to a predetermined position.

A read / write means 73 is connected to the central control means 71. The read / write means 73 serves as a data storage means 74 mounted in each ink cartridge when the ink cartridge is mounted in the recording apparatus. Of, for example, an EEPROM, so that data is exchanged. In this embodiment, characteristic data of ink viscosity (apparent ink viscosity information corresponding to shear stress) enclosed in the respective cartridges is written in the data storage means 74, and is read out. The writing means 73 functions to obtain this information and supply it to the central control means 71. The read / write means 73 also operates so that the data generated on the recording device side can be written to the data storage means 74 as needed.

Then, the central control means 71 stores a driving condition setting table 75 in which data relating to the driving conditions of the recording head corresponding to the above-mentioned ink viscosity information is stored.
Are connected, and the central control means 71 uses the table 7
5 is accessed, and data relating to the drive conditions of the recording head corresponding to the ink viscosity information read from the ink cartridge side can be acquired.

In this case, as the ink viscosity information previously stored in the data storage means 74, it is preferable to give viscosity information corresponding to shear stress in a two-dimensional relationship.
If the dye ink used in the recording device has a predetermined physical property according to each color, it is possible to use a code of several digits as the ink viscosity information, and from this code, The driving condition setting table 75 may be configured to acquire the viscosity information corresponding to the shear stress, which is described by a two-dimensional map.

On the other hand, the central control means 71 is also configured to be supplied with a control signal from the drive condition selecting means 76. The drive condition selecting means 76 is provided with an operation switch 77. By using this operation switch 77, information on the viscosity of the ink enclosed in each mounted cartridge can be manually set.

In this case, when the data storage means 74 is not loaded in the ink cartridge mounted as described above, or even when the data storage means 74 is loaded, the ink viscosity information is not recorded. In this case, the operation switch 77 can be used. The ink viscosity information may be set on the utility of the printer driver 61 installed in the host computer 60 that issues a print command to the recording apparatus.

FIG. 5 shows the print control means 6 shown in FIG.
4 and a more detailed structure of the head driving means 65 are shown in a block diagram. First, the print control unit 64 includes an interface 80 that receives print data and the like from the host computer 60, a RAM 81 that stores various data, and a ROM 82 that stores control routines for processing various data. A control unit 83 including a CPU and the like, which transmits and receives data to and from the central control unit 71 and executes various controls in the print control unit 64, an oscillation circuit 84, and a drive signal generation circuit which generates a drive signal. 85, a drive information storage means 86 for storing drive information read from the drive condition setting table 75 via the central control means 71, print data and drive signals expanded into dot pattern data (bitmap data) And an interface 87 for transmitting the above information to the head driving means 65.

The interface 80 receives, from the host computer 60, print data including one data or a plurality of data such as a character code, a graphic function, and image data. Further, the interface 80 can output a busy (BUSY) signal, an acknowledge (ACK) signal, or the like to the host computer 60.

The RAM 81 comprises a receiving buffer 81a, an intermediate buffer 81b and an output buffer 81c, and is used as a work memory or the like. Reception buffer 81
The print data or the like from the host computer 60 received by the interface 80 is temporarily stored in a.
Further, the intermediate code 81 converted into the intermediate code by the control unit 83 is stored in the intermediate buffer 81b. Further, dot pattern data is expanded in the output buffer 81c.

The ROM 82 has the control section 83 as described above.
It stores various control routines executed by, font data, graphic functions, and the like. The control unit 83 also has a function of reading the print data in the reception buffer 81a, converting it into an intermediate code, and storing the converted intermediate code data in the intermediate buffer 81b. Further, the control unit 83 has a function of expanding the intermediate code data read from the intermediate buffer 81b into dot pattern data by referring to font data and graphic functions in the ROM 82. Further, the developed dot pattern data functions to be stored in the output buffer 81c after the necessary decoration processing is performed.

When dot pattern data corresponding to one line of printing by the recording head 8 is obtained, this 1
The dot pattern data for the line is the interface 87
Is serially transmitted to the head drive means 65 via. When one line of dot pattern data is output from the output buffer 81c, the contents of the intermediate buffer 81b are erased and the expansion of the next intermediate code is performed.

Next, the electrical construction of the head driving means 65 will be described. The head drive means 65 includes a shift register 90, a latch circuit 91, a level shifter 92, and an analog switch 93. Then, a drive signal is supplied to the piezoelectric vibrator 25 in the recording head 8 via the analog switch 93.

More specifically, as shown in FIG. 6, the shift register 90, the latch circuit 91, the level shifter 92, and the analog switch 93 correspond to each nozzle opening 16 and are respectively provided in the shift register 90a.
To 90n, latch circuits 91a to 91n, level shifter 9
2a to 92n and analog switches 93a to 93n are provided. Then, the analog switches 93a to
Drive signals are supplied to the piezoelectric vibrators 25a to 25n in the recording head 8 via 93n.

In the above configuration, the print data (SI) expanded into dot pattern data is the oscillation circuit 84.
In synchronism with the clock signal (CK) from, the serial transmission is sequentially performed to the shift register 90 (that is, each shift register 90a to 90n shown in FIG. 6) mounted on the head drive unit 65 through the interface 87.
The serially transferred print data (SI) is sent to the latch command signal (LA) sent through the interface 87.
It is latched by the latch circuit 91 (91a to 91n) that receives T).

Then, the latched print data is boosted by the level shifter 92 (92a to 92n), which is a voltage amplifier, to a voltage at which the analog switch 93 can be driven, and the boosted switching signal is applied to the analog switch 93 (93a). ˜93n).

On the input side of the analog switch 93,
The drive signal (COM) from the drive signal generation circuit 85 is input, and the output of the analog switch 93 is the piezoelectric vibrator 25 by the piezo element mounted on the recording head 8.
(25a to 25n). The print data described above controls the on / off operation of the analog switch 93. For example, while the print data applied to the analog switch 93 is “1”, the drive signal is supplied to the piezoelectric vibrator 25, and the piezoelectric vibrator 25 is responsive to the drive signal.
Transforms. On the other hand, while the print data applied to the analog switch 93 is “0”, the supply of the drive signal to the piezoelectric vibrator 25 is cut off. With the deformation of the piezoelectric vibrator 25, ink droplets are ejected from the nozzle openings 16.

Next, the operation of ejecting an appropriate amount of each ink droplet from the recording head based on the viscosity information of each ink using the above-mentioned structure will be described. FIG. 7 shows the waveform of the drive signal and the output timing of each of these waveforms. The drive signal generated by the drive signal generation circuit 85 shown in FIG. 5 includes the first drive waveform signal shown in FIG. 7A, the second drive waveform signal shown in FIG. Figure 7
The third drive waveform signal shown in (C) is prepared.
The third drive waveform signal is generated by selecting both the first drive waveform signal and the second drive waveform signal. Therefore, here, the first drive waveform signal and the second drive waveform signal
The total time of generation timings of the drive signal waveforms is set to the drive cycle of one shot in the recording head 8.

Each of the above-mentioned drive waveform signals has a plurality of slopes, and the first drive waveform signal shown as (A) has a drive voltage drop with a slope shown as a and a drive voltage with a slope shown as b. It forms a rising drive waveform. Here, the inclination shown as a produces an action of drawing in the meniscus of the ink formed in the nozzle opening 16 of the recording head when the piezoelectric vibrator 25 as an actuator is driven, and the inclination shown as b shows that the meniscus is The action of pushing the drawn ink to the nozzle opening 16 side is generated. As a result, ink droplets are ejected from the nozzle openings.

The second drive waveform signal shown as (B) forms a drive waveform in which the drive voltage drops at the slope shown as c and the drive voltage rises at the slope shown as d. Here, the inclination shown as c is similarly the piezoelectric vibrator 2
5 drives the ink meniscus formed in the nozzle opening 16 of the recording head, and the inclination indicated by d has a function of pushing out the ink with the meniscus drawn in toward the nozzle opening 16 side. To occur. In this case, the slope shown as d is made slightly steeper than the slope shown as b, and the change in the voltage level is also slightly large. Therefore, the second drive waveform signal shown as (B) has a larger ink droplet ejection function when the piezoelectric vibrator is driven than the first drive waveform signal shown as (A).

Further, the third drive waveform signal shown as (C) is a state in which both of the above-mentioned first and second drive waveform signals are selected, and when the piezoelectric vibrator 25 is driven, the maximum value is obtained. Demonstrate the function of ejecting ink drops. That is, the ink droplets are ejected at the above timings b and d. The drive signal generation circuit 85 shown in FIG. 5 is configured to repeatedly generate the above-mentioned first and second drive waveform signals.

In this embodiment, either the first or the second drive waveform signal as described above is supplied to the piezoelectric vibrator 25 for ejecting each ink based on the above-mentioned information on the viscosity of the ink. Alternatively, a drive signal generated by selecting both of them is supplied to the recording head. As a result, the ejection amount of ink from the nozzle opening in one shot is corrected, and the ejection amount of ink of each color in one shot is controlled to be approximately equal regardless of the type (viscosity characteristic) of the pigment ink. .

As described above, each shift register 90a
.About.90n through the latch circuits 91a to 91n and the like to the analog switches 93a to 93n, while the bit of the print data is "1", the drive signal is the piezoelectric vibrator 25a.
To 25n, the piezoelectric vibrators 25a to 25n expand and contract according to the waveform of the drive signal. On the other hand, while the bit of the print data is "0", the supply of the drive signal to the piezoelectric vibrators 25a to 25n is cut off.

Therefore, as shown in FIG. 7, the bit of the print data is set to "1" or "0" in accordance with the generation timing of the repeatedly generated first and second drive waveform signals. Either one of the first and second drive waveform signals or both the first and second drive waveform signals can be selected and generated as the drive signal. In this case, the drive information storage means 8 shown in FIG.
Drive information corresponding to the viscosity information of each ink is stored in 6 via the central control means 71, and the drive signal generation circuit 85 is synchronized with the generation timing of the first and second drive waveform signals. Then, information for controlling the bit of the print data to "1" or "0" is supplied.

Therefore, for example, when the difference in the apparent ink viscosities corresponding to the shear stress is small,
By setting the bit of the print data to “1,0”, the first drive waveform signal shown in FIG. 7A as the drive signal corresponds to the piezoelectric vibrator 25 corresponding to the nozzle opening portion for ejecting the first drive waveform signal.
Is supplied to. Further, when the difference is medium, the bit of the print data is set to "0, 1" so that the second drive waveform signal shown in FIG. It is supplied to the piezoelectric vibrator 25 corresponding to the nozzle opening. Further, when the difference is large, the bit of the print data is set to "1,1" so that the third drive waveform signal shown in FIG. Is supplied to the piezoelectric vibrator 25 corresponding to.

As a result, the ejection amount of each pigment ink in one shot from the nozzle opening is corrected, and the ejection amount of one shot is controlled to be approximately equal regardless of the type of ink. Therefore, even if a combination of inks having different physical properties of viscosity corresponding to shear stress, as represented by a pigment ink, is used, the ink ejection amount in one shot is almost the same. Can be compensated so that the print quality can be improved.

In the first embodiment described above, for convenience of explanation, the first and second drive waveform signals are prepared as shown in FIG. 7, and either or both of them are adopted. Although three-stage compensation is realized, for example, by preparing three basic drive waveform signals and similarly using any of them or a combination thereof,
Six levels of compensation can be realized.

Next, FIG. 8 illustrates another example in which an appropriate amount of each ink droplet is ejected from the recording head based on the viscosity information of each ink. FIG. 8 shows the form of the drive signal applied to the piezoelectric vibrator as each actuator corresponding to each nozzle opening. Similar to the example shown in FIG. 7, this drive signal has a slope in which the drive voltage level drops and a slope in which the drive voltage subsequently rises.

As a result, as described above, the meniscus of the ink formed in the nozzle opening of the recording head is drawn in, and the ink in the state where the meniscus is drawn in is pushed out to the nozzle opening side. More ink droplets are ejected.

In this embodiment, based on the characteristic information of the apparent ink viscosity corresponding to the shear stress,
The voltage level of the drive signal is changed, for example, in the range shown by the solid line to the broken line. That is, with respect to the reference drive waveform indicated by the solid line, the reference potential is increased and the amplitude is increased as indicated by h, i, j in the figure. In this way, as the drive waveform signal is changed from the state of the solid line to the state shown by the broken line, the ink droplet ejection function is increased when the piezoelectric vibrator is driven.

Therefore, when ejecting ink having a small apparent viscosity difference corresponding to shear stress, the drive waveform as shown by the solid line is adopted, and when ejecting ink having a large difference, the broken line is used. By adopting the drive waveform as shown in, the ejection amount of the ink from the nozzle opening in one shot is corrected, and the ejection amount of the ink of each color in one shot is almost the same regardless of the type of ink (viscosity characteristic). It can be controlled to approach the same level. According to this example, by appropriately changing the voltage level of the drive waveform signal applied to the piezoelectric vibrator that ejects the ink according to the type of ink (viscosity characteristic), the ejection amount of ink in one shot can be continuously changed. It becomes possible to correct.

On the other hand, for example, the drive waveform shown by the solid line and the drive waveform shown by the broken line in FIG. 8 are generated alternately in a time division manner as the output timings shown in FIGS. 7A and 7B. In such a case, the circuit configuration as shown in FIGS. 5 and 6 can be used as it is. That is, the bit of the print data is controlled to "1" at the output timing of the drive waveform shown by the solid line in FIG. 8, and the bit of the print data is controlled to "0" at the output timing of the drive waveform shown in the broken line in FIG. By doing so, a low-amplitude drive waveform shown by the solid line can be selected and added to the piezoelectric vibrator.

Further, at the output timing of the drive waveform shown by the solid line in FIG. 8, the bit of the print data is controlled to "0", and at the output timing of the drive waveform shown by the broken line in FIG. It is possible to select a high-amplitude drive waveform indicated by a broken line by controlling the value to “”, and this can be applied to the piezoelectric vibrator. As a result, it is possible to correct the ejection amount of ink from the nozzle opening in one shot, and to control the ejection amount of ink of each color in one shot to be approximately equal regardless of the type of ink (viscosity characteristic). it can.

In this case, the drive waveform at the intermediate level between the solid line and the broken line shown in FIG. 8 is further created, and similarly, each drive waveform is selected in a time division manner, so that the ink in one shot can be further increased in multiple steps. It is possible to correct the discharge amount of.

In the above description, different drive signals are supplied to the piezoelectric vibrators corresponding to the nozzle openings from which different inks are ejected.
Although the ejection amount of one shot is made uniform depending on the difference in the viscosity characteristics of each ink, the nozzle diameters of the nozzle openings may be made different to correspond to the inks of different types (viscosity characteristics). , You can get similar results.

That is, in this type of recording apparatus,
An ink cartridge supply system is used so that the inks designated for the respective recording devices are exclusively used, and therefore, ink having physical properties corresponding to the recording device is used. Therefore, according to the viscosity characteristics of the inks of each color used in this recording apparatus, the opening diameter of the nozzle opening for ejecting the ink with low viscosity is made small and the opening of the nozzle opening for ejecting the ink with high viscosity is made small. By previously configuring the nozzle diameters of the nozzle openings of the recording head so as to have a large aperture, it is possible to make uniform the ejection amount of one shot in correspondence with the difference in viscosity of each ink.

[0077]

According to the ink jet recording apparatus adopting the driving method according to the present invention, even when inks having different viscosities corresponding to shear stress are used, as represented by pigment inks, for example. To provide an ink jet recording apparatus capable of further improving the print image quality, since the ink ejection amount of one shot ejected from the nozzle opening of the recording head can be controlled so as to be nearly equal. You can

[Brief description of drawings]

FIG. 1 is a perspective view showing a basic configuration of an ink jet recording apparatus to which the present invention is applied.

FIG. 2 is a schematic diagram showing a state in which a recording head mounted on the recording apparatus shown in FIG. 1 is viewed from a nozzle forming surface.

FIG. 3 is a cross-sectional view showing a detailed structure of a part of the recording head.

FIG. 4 is a block diagram showing a control circuit in the recording apparatus shown in FIG.

5 is a block diagram showing a detailed configuration of a part of blocks in the control circuit shown in FIG.

FIG. 6 is a block diagram showing a main part of a recording head drive unit.

FIG. 7 is a waveform diagram showing an example of a drive signal supplied to a recording head.

FIG. 8 is a waveform diagram showing an example of another drive signal supplied to the recording head.

FIG. 9 is a characteristic diagram illustrating the relationship between viscosity and shear stress.

FIG. 10 is a characteristic diagram illustrating a relationship between ink ejection amounts corresponding to shear stress in different inks.

[Explanation of symbols]

1 carriage 2 Carriage motor 5 Paper feed member 7 Recording paper 8 recording head 9B-9Y ink cartridge 11 Capping means 12 Suction pump 13 Wiping member 16 nozzle opening 25 Piezoelectric vibrator (actuator) 31 Pressure chamber 36 diaphragm 41 nozzle plate 60 host computer 61 Printer driver 64 printing control means 65 head driving means 71 Central control means 73 read / write means 74 Data storage means 75 Drive condition setting table 76 Drive condition selection means 90 shift register 91 Latch circuit 92 level shifter 93 analog switch K, C, M, Y nozzle row

Claims (12)

[Claims] 1. An inkjet recording apparatus equipped with a recording head for performing printing on a recording medium by ejecting a plurality of different kinds of ink as ink droplets based on print data. The drive signals controlled so as to reduce the difference in the ink ejection amount caused by the difference in the apparent viscosity based on the difference in the shear stress in each ink, are arranged corresponding to the nozzle openings of the recording head. An ink jet recording apparatus comprising drive signal generating means for supplying each to an actuator. 2. The recording head is configured to eject different types of ink for each nozzle array, and the drive signal generating means is configured to eject ink for each actuator corresponding to each nozzle array. 2. The ink jet recording apparatus according to claim 1, wherein the drive signals are controlled so as to reduce the difference between the two. 3. The drive signal generating means, by selecting any one of a plurality of preset basic drive waveform signals, or by selecting a plurality of preset basic drive waveform signals, The ink jet recording apparatus according to claim 1, wherein the drive signal is generated so as to be controlled so as to reduce the difference in ink ejection amount. 4. The drive signal generating means reduces the difference in ink ejection amount by changing the voltage level of the drive signal or by selecting drive signals of a plurality of preset voltage levels. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is configured to generate the drive signal controlled as described above. 5. The drive signal generating means is constituted so that information on apparent viscosity based on a difference in shear stress can be read from a data storage means mounted on an ink cartridge mounted on the recording apparatus. The ink jet recording apparatus according to any one of claims 1 to 4, wherein is configured to generate the drive signal controlled corresponding to each ink based on the information read from the data storage means. . 6. The drive signal generation means outputs the drive signal controlled corresponding to each ink, based on information of apparent viscosity based on a difference in shear stress manually set for the recording apparatus. Claim 1 configured to generate
The inkjet recording apparatus according to claim 4. 7. The drive condition selecting means, wherein the manual setting is executed by a drive condition selecting means installed in a recording apparatus or a utility of a printer driver installed in a host computer which issues a print command to the recording apparatus. The ink jet recording apparatus according to claim 6, wherein the ink jet recording apparatus is configured to be performed by the following. 8. An ink jet recording apparatus equipped with a recording head that prints on a recording medium by ejecting a plurality of different kinds of ink as ink droplets based on print data. An ink jet recording apparatus characterized in that the nozzle diameters of the nozzle openings are made different to correspond to different types of ink ejected from the nozzle openings. 9. The ink jet recording apparatus according to claim 8, wherein the recording head is configured to eject different ink for each nozzle row, and the opening diameter of the nozzle opening is made different for each nozzle row. Recording device. 10. The ink introduced into the recording head is a pigment-dispersed ink.
The ink jet recording apparatus according to any one of 1. 11. A method of driving a recording head in an ink jet recording apparatus equipped with a recording head that prints on a recording medium by ejecting a plurality of different types of ink as ink droplets based on print data. There is an information acquisition step of acquiring information on the viscosity characteristics of the respective inks of different types introduced into the recording head, and a drive signal based on the information of the viscosity characteristics of the respective inks acquired by the information acquisition step. A drive condition setting step for setting a drive condition corresponding to the viscosity characteristic information to the generating means, and a nozzle opening for ejecting different types of ink corresponding to the drive condition set by the drive condition setting step. For each actuator corresponding to the above, a drive signal is supplied from the drive signal generating means to the drive signal corresponding to the viscosity characteristic. A method of driving a recording head in an ink jet recording apparatus, which is configured to sequentially perform a feeding step and a feeding step. 12. In the information acquisition step, viscosity information corresponding to shear stress is respectively acquired as the viscosity characteristic information of each ink, and in the drive condition setting step, based on the viscosity information corresponding to shear stress, The method for driving a recording head in an ink jet recording apparatus according to claim 11, wherein a driving condition is set for the driving signal generating means.