JP2001010035A - Ink jet recording device - Google Patents

Abstract

(57) [Problem] To provide an ink jet recording apparatus capable of performing charging for compensating for spontaneous discharge generated in a pressure generating element at an arbitrary timing. In an ink jet recording apparatus, a head drive circuit (7) includes a pressure generating element (ink) charged to a potential that matches an intermediate potential (Vm) of a drive signal (COM) during, for example, periods T5 to T6. In the periods T5 to T6, the intermediate potential Vm is selectively selected from the drive signal COM for the pressure generating element 17 that does not discharge droplets and the pressure generating element 17 that discharges ink droplets of large dots. A signal to be applied to the generator 17 is output. As a result, it is possible to recover the potential of the pressure generating element whose potential has been lowered from the intermediate potential Vm by natural discharge.

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 used as an ink jet printer or an ink jet plotter. More specifically, the present invention relates to a driving technique for a pressure generating element in an ink jet recording apparatus.

[0002]

2. Description of the Related Art In a recording head of an ink-jet recording apparatus used as an ink-jet printer or an ink-jet plotter, a pressure generating element such as a plurality of piezoelectric vibrators (for example, piezo elements) corresponding to a plurality of nozzle openings is provided at the nozzle opening. An ink droplet is ejected from the nozzle opening by pressurizing the ink in the communicating pressure generating chamber. In performing such driving, generally, a common drive signal for each pressure generating element is generated, and an ink discharge potential (a charge potential for ink discharge and a charge potential for ink discharge) included in this drive signal in time series within one recording cycle. (Discharge potential) is selected at a predetermined timing and applied to the pressure generating element. Therefore, if a signal (drive pulse) of a different potential is included in the drive signal and these signals of different potentials are selectively applied to each of the pressure generating elements, a plurality of pressure generating elements can be shared by a common drive signal. Can be driven under different conditions, so that ink droplets of different sizes are ejected from the nozzle openings,
Dots of different diameters can be formed on a medium such as recording paper.

When the pressure generating element is driven by using such a drive signal, an intermediate potential is applied to the pressure generating element which does not discharge ink droplets in the current recording cycle in the previous recording cycle. It is charged with the potential. In addition, the intermediate potential is applied to the pressure generating element that ejects the ink droplets in the current recording cycle in the previous recording cycle until the charging is performed, and the pressure generating element is kept charged at the intermediate potential.

[0004]

However, in the conventional ink jet recording apparatus, an intermediate potential is applied in the previous recording cycle to a pressure generating element which does not discharge ink droplets in the current recording cycle. Even if charged, the potential of the pressure-generating element decreases due to spontaneous discharge occurring in the pressure-generating element. For this reason, there is a problem in that even if an ink ejection potential is applied in the next recording cycle in order to eject an ink droplet, the potential immediately before the ink ejection potential is too low and a desired amount of ink droplet cannot be ejected.
Also, in the pressure generating element that discharges ink droplets in the present recording cycle, if the period until the ink discharge potential is applied is long, even if a predetermined potential is applied to discharge ink droplets, the potential immediately before that is applied. Is too low to discharge a desired amount of ink droplets.

Accordingly, the applicant of the present application has disclosed Japanese Patent Laid-Open No. Hei 4-310.
No. 748 discloses a technique in which all pressure generating elements are recharged at a predetermined timing to absorb spontaneous discharge occurring in the pressure generating elements. According to this technique, all the pressure generating elements are recharged at the same time at a predetermined timing. Therefore, when a potential for ejecting ink droplets is applied, the potential immediately before the potential drops. Can be avoided.

However, in the technique disclosed herein, there is a limitation that all the pressure generating elements can be recharged only at a timing when they are held at the same potential, that is, at an intermediate potential. For example, among the common driving signals including a plurality of driving pulses corresponding to gradation recording, one of the driving pulses or a plurality of driving pulses is selectively applied to the pressure generating element. In the device, it is often difficult to ensure the timing at which the pressure generating elements to which the driving pulses corresponding to the respective gradations are applied are kept at the same potential, so that it is difficult to recharge all the pressure generating elements at the same time. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a configuration in an ink jet recording apparatus capable of appropriately performing charging for compensating for spontaneous discharge generated in a pressure generating element at an arbitrary timing.

[0008]

According to the present invention, a plurality of pressure generating elements corresponding to each of a plurality of nozzle openings pressurize ink in a pressure generating chamber communicating with the nozzle openings. A print head that ejects ink droplets from the nozzle openings, a drive signal generation unit that generates a common drive signal including a plurality of drive pulses to be applied to the pressure generating element, and a drive signal generation unit that generates the drive pulse based on print data. Any one of these, or a head driving unit that applies a plurality of driving pulses to the pressure generating element, wherein the head driving unit includes a predetermined one of the pressure generating elements in one recording cycle. For the pressure generating element charged to a potential equal to the potential of the drive signal at the timing, the potential is selectively set to the previous potential. Select from the drive signal and wherein the recharging to the pressure generating element.

For example, the head driving means selectively selects the intermediate potential from the drive signal for the pressure generating element charged to an intermediate potential among the pressure generating elements, and Recharge the device.

In the present invention, among the pressure generating elements, the pressure generating element held at the intermediate potential includes:
For example, it is a pressure generating element that is maintained in a state where the intermediate potential is charged, by suspending ejection of ink droplets in the current recording cycle.

In the present invention, among the pressure generating elements, the pressure generating element that is maintained at the intermediate potential is, for example, after the ink droplet is ejected in the current recording cycle or in the current recording cycle. The pressure generating element keeps the intermediate potential charged until a charging potential for ejecting ink droplets is applied.

According to the present invention, the pressure generating element is maintained in a state where the intermediate potential is charged by suspending the ejection of the ink droplet in the current recording cycle. Drive pulse (charge potential) for ejecting ink droplets in the recording cycle of
Until is applied, only a predetermined pressure generating element that is maintained at the intermediate potential, such as a pressure generating element that is maintained in a state where the intermediate potential is charged, is selectively switched from the drive signal to the intermediate level. Select and apply a potential and recharge. Therefore, it is possible to avoid a problem that even if a potential is applied to discharge an ink droplet, the potential immediately before the potential is too low to discharge a desired amount of ink droplet. In addition, during such recharging, such a recharging is not performed for the pressure generating element that is being charged or discharged for discharging ink droplets. That is, in the present invention, all the pressure generating elements are not recharged at the same time at a predetermined timing, but are selectively recharged only to the pressure generating elements held at the intermediate potential. Recharging to compensate for spontaneous discharge can be performed without timing when all the generating elements are held at the same potential (intermediate potential).

In the present invention, the head driving means includes:
Print data storage means for storing print data for each input nozzle; nozzle drive conditions corresponding to the print data; and a predetermined timing for a pressure generating element corresponding to predetermined print data among the print data. Control data storing means for storing control data including recharging conditions for applying a voltage for recharging; and the recording data and control data stored in the recording data storing means and the control data storing means, respectively. And a translation means for translating the timing at which the drive signal is applied to the pressure-generating element based on the application into an application presence / absence signal that is defined for each nozzle and each period within one recording cycle. . With this configuration, the recording data is translated into an application presence / absence signal in the head driving means based on the control data, so that the recording data output to the head driving means requires only a small number of bits. Therefore, the serial transfer time from the recording apparatus main body to the head driving means can be reduced. In addition, since recharging is performed based on the translation result based on the control data, recharging conditions can be arbitrarily set, and the recharging conditions can be easily changed.

Further, in the present invention, the control data is transferred and stored collectively to the control data storage means, and the translation means performs the recording for each nozzle stored in the recording data recording means. When generating the application presence / absence signal for each period in one recording cycle based on the data, the control data for the corresponding period is selectively selected from the control data stored in the control data storage unit. It is preferable to generate the application presence / absence signal with reference to FIG. In this way, all of the control data is collectively transferred to the control data storage means and stored, and the control data for the corresponding period is selectively referred to from the control data to determine whether or not to apply the control data. With a configuration in which the signal is translated into a signal, it is not necessary to transfer the data from the recording apparatus body many times within one recording cycle, so that the data transfer time can be reduced.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to the drawings, an ink jet head driving circuit of an ink jet recording apparatus to which the present invention is applied will be described.

[Overall Configuration of Inkjet Recording Apparatus] FIG. 1 is a perspective view showing the configuration of an inkjet recording apparatus to which the present invention is applied. In FIG. 1, the inkjet recording apparatus 1 of the present embodiment is used by being connected to a host computer (not shown) together with a scanner (not shown) and the like. When a predetermined program is loaded and executed on the computer, the entirety of these devices integrally functions as a recording device. In a computer, an application program operates under a predetermined operating system, and displays an image on a CRT display (not shown) while performing predetermined processing on an image or the like read from a scanner. When the application program issues a print command, the computer converts image data read via a scanner, character data input via a keyboard, and the like into data used by the inkjet recording apparatus 1, and Output to

In the ink jet recording apparatus 1, a carriage 101 is connected to a carriage motor 103 of a carriage mechanism 12 via a timing belt 102, and is guided by a guide member 104 to reciprocate in the paper width direction of a recording paper 105 (medium). Is configured. The inkjet recording apparatus 1 is also provided with a paper feed mechanism 11 using a paper feed roller 106. An ink jet type recording head 10 is attached to a surface of the carriage 101 facing the recording paper 105, in the example shown in FIG. The recording head 10 receives the supply of ink from the ink cartridge 107 mounted on the upper part of the carriage 101, and moves the recording paper 1 according to the movement of the carriage 101.
05 to form dots by ejecting ink droplets on recording paper 1
Print images and characters on 05.

A capping device 108 is provided in a non-printing area (non-recording area) of the ink jet recording apparatus 1, and seals a nozzle opening of the recording head 10 during a printing pause. Therefore, it is possible to suppress the ink from thickening or forming an ink film due to the solvent being scattered from the ink during the suspension of printing. Therefore, it is possible to prevent the nozzle from being clogged while the printing is stopped. Further, the capping device 108 receives ink droplets from the recording head 10 due to a flushing operation performed during a printing operation. A wiping device 109 is disposed near the capping device 108.
Is configured to wipe off the ink residue and paper powder adhering thereto by wiping the surface of the recording head 10 with a blade or the like.

FIG. 2 is a functional block diagram of the ink jet recording apparatus 1 of the present embodiment.

In FIG. 2, an ink jet recording apparatus 1
Includes a print controller 40 and a print engine 5 including the recording head 10. The print controller 40 includes an interface 43 for receiving recording information including multi-level hierarchical information from a host computer (not shown), a RAM 44 for storing various data such as recording information including multi-level hierarchical information, and the like. ROM 4 storing routines for performing various data processing
5, a control unit 6 including a CPU and the like, and a clock signal CK.
Oscillating circuit 47, which generates a common driving signal COM to be supplied to the recording head 10, a driving signal generating circuit 8 as driving signal generating means, and recording data developed into dot pattern data (bitmap data). An interface 49 for transmitting the SI, the drive signal COM, and the like to the print engine 5 is provided.

The interface 43 receives, for example, any one of a character code, a graphic function, and image data or record information including a plurality of data from a host computer or the like. The interface 43 can also output a busy signal (BUSY), an acknowledge signal (ACK), and the like to the host computer.

The RAM 44 is used as a reception buffer 44A, an intermediate buffer 44B, an output buffer 44C, a work memory (not shown), and the like. Recorded information from the host computer received by the interface 43 is temporarily stored in the reception buffer 4A. The intermediate buffer 44B stores the intermediate data code converted into the intermediate code by the control unit 6. The dot pattern data is developed in the output buffer 44C. The ROM 45 stores various control routines executed by the control unit 6, font data and graphic functions,
Various procedures are stored.

The control section 6 reads the record information in the reception buffer 44A, converts it into an intermediate code, and stores the intermediate code data in the intermediate buffer 44B. Next, the control unit 6 analyzes the intermediate code data read from the intermediate buffer 44B, and develops the intermediate code data into dot pattern data with reference to the font data and graphic functions in the ROM 45. The developed dot pattern data is stored in the output buffer 44C after performing necessary decoration processing.

When dot pattern data corresponding to one line of the recording head 10 is obtained, the dot pattern data for one line is serially transferred to the recording head 10 via the interface 49 as recording data SI. When one line of dot pattern data is output from the output buffer 44C, the contents of the intermediate buffer 44B are deleted, and the next intermediate data conversion is performed. Here, the data in the output buffer 44C developed into the dot pattern data is composed of, for example, 2 bits as gradation data for each nozzle as described later.

The control unit 6 is provided with a predetermined pressure generating element 1.
7, a head drive condition for applying a drive signal COM at a timing corresponding to the recording data SI to perform recording and fine vibration, and a pressure generating element 17 driven under conditions corresponding to a predetermined recording data SI. The control data SP including the recharging condition for applying the voltage for recharging at a predetermined timing is output to the recording head 10 via the interface 49.

The drive signal generating circuit 8 generates a single drive signal COM composed of a plurality of drive pulses described later.

The drive signal COM output from the drive signal generation circuit 8 is also output to the recording head 10 via the interface 49. The recording head 10 has, for example, six rows of 48 nozzles in the sub-scanning direction, and ejects ink droplets from each nozzle opening 111 at a predetermined timing.

The print engine 5 includes the paper feed mechanism 11 and the carriage mechanism 12. The paper feed mechanism 11 sequentially feeds out recording paper 15 such as recording paper and performs sub-scanning.
Is for causing the recording head 10 to perform main scanning.

From the print controller 40 to the recording head 10, the recording data SI is synchronized with the clock signal (CK) from the oscillation circuit 47, and the head driving circuit 7 (head driving means) ) Is output via the interface 49. The recording data SI output to the head drive circuit 7 is input to a shift register 13 as a serial / parallel conversion unit. A latch circuit 14 is connected to the shift register 13. Then, when a latch signal (LAT) from the print controller 40 is input to the latch circuit 14, the latch circuit 14 latches the recording data SI that has been parallel-converted by the shift register 13. Here, the shift register 13 is configured as a first shift register 131 and a second shift register 132, and is provided with the most significant bit (MS) of the 2-bit recording data SI.
The data of B) is input to the second shift register 132, and the data of the least significant bit (LSB) is input to the first shift register 131.

In the latch circuit 14, a first latch circuit 141 is connected to the first shift register 131, and a second latch circuit 142 is connected to the second shift register 132. . Therefore, in synchronization with the latch signal (LAT) from the print controller 40, the first latch circuit 141 latches the data of the least significant bit of the recording data SI, and the second latch circuit 14
2, the data of the most significant bit of the recording data SI is latched. As described above, in the present embodiment, the shift register 13 and the latch circuit 14 use the recording data storage unit 2.
1 is configured.

In this embodiment, the head driving circuit 7 has a translating means 20 provided with a decoder 18 and a control logic 19. In this translating means 20, the decoder 1
8 shows the recording data SI latched by the latch circuit 14.
Is entered. The decoder 18 controls the recording data SI stored in the latch circuit 14 and the control logic 1
Based on the control data SP stored in No. 9, the 2-bit print data SI is translated into a 12-bit application presence / absence signal DR for each nozzle. This translation processing and control data S
P will be described later with reference to FIGS. 7, 12, and 13.

The application presence / absence signal DR translated by the decoder 18 or the like is output by the level shifter 15 as a voltage converter when the application presence / absence signal DR is, for example, “1”. Converted to tens of volts. Then, the converted application presence / absence signal DR
Is applied to each element of the switch circuit 16, and each element is connected. Here, on the input side of the switch circuit 16,
A drive signal (COM) generated by the drive signal generation circuit 8 is applied, and a pressure generation element 17 such as a piezoelectric vibrator is connected to an output side of the switch circuit 16.

The application presence / absence signal DR controls the operation of the switch circuit 16. For example, while the bit of the application presence / absence signal DR applied to the switch circuit 16 is “1”,
The driving signal COM is applied to the pressure generating element 17, and the pressure generating element 17 expands and contracts by the driving signal COM.
On the other hand, the application presence / absence signal DR applied to the switch circuit 16
During the period in which the bit of “.” Is “0”, the application of the drive signal COM to the pressure generating element 17 is cut off, so that the pressure generating element 17 holds the previous charge.

[Structure of Recording Head] FIG. 3 is an enlarged sectional view showing one of the actuators formed on the recording head 10. As shown in FIG.

In FIG. 3, in the recording head 10, a nozzle opening 111 is formed in a nozzle plate 110, and a through hole for partitioning a pressure generating chamber 113 is formed in a flow path forming plate 112.
There are formed through holes or grooves defining two ink supply ports 114 communicating on both sides with the pressure generating chamber 113, and through holes defining two common ink chambers 115 communicating with these ink supply ports 114, respectively. I have. Diaphragm 11
6 is formed from an elastically deformable thin plate, abuts against the tip of a pressure generating element such as a piezo element (piezoelectric vibrator), and is fixed to the nozzle plate 110 in a liquid-tight manner with the flow path forming plate 112 interposed therebetween. The flow path unit 118 is configured.

An accommodation chamber 120 for accommodating the pressure generating element 17 in a vibrating manner and an opening 121 for supporting the flow path unit 118 are formed in the base 119, and the tip of the pressure generating element 17 is exposed from the opening 121. Pressure generating element 1
7 is fixed by a fixed substrate 122. In addition, base 119
In the state where the island 116 a of the diaphragm 116 is in contact with the pressure generating element 17,
21, the recording head 10 is put together.

(Configuration of Drive Signal Generation Circuit 8) FIG. 4 is a block diagram showing a configuration of the drive signal generation circuit 8. FIG.
FIG. 4 is an explanatory diagram showing a process in which the drive signal generation circuit 8 generates each drive pulse included in the drive signal COM. FIG. 6 is a timing chart showing the timing of each signal when the potential difference (ΔV) is set in the memory using the data signal in the drive signal generation circuit 8.

In FIG. 4, the drive signal generation circuit 8 includes:
A memory 81 for receiving and recording signals from the control unit 6;
A first latch 82 for reading and temporarily holding the contents of the memory 81; an adder 83 for adding the output of the first latch 82 to the output of another second latch 84, which will be described later; A / D converter 86 for converting the output of the latch 84 into analog data, a voltage amplifier 88 for amplifying the converted analog signal up to the voltage of the drive signal, and a current for the drive signal output from the voltage amplifier 88 It comprises an amplifier 89. Here, the memory 81
A predetermined parameter for determining the waveform of the drive signal COM is stored. As described later, the drive signal COM
Is determined by predetermined parameters previously received from the control unit 6. That is, the drive signal generation circuit 8
Are clock signals 801, 802, 803, data signal 830, address signals 810, 811, 812, 81
3, and a reset signal 820 are received.

In the drive signal generation circuit 8 configured as described above, as shown in FIG. 5, prior to generation of the drive signal COM, some data signals indicating the voltage change amount of the control unit 6 and the data signals The address of the signal is output to the memory 81 of the drive signal generation circuit 8 in synchronization with the clock signal 801. The data signal 830 is, as shown in FIG.
Data is exchanged by serial transfer using a clock signal 801 as a synchronization signal. That is, when transferring a predetermined amount of voltage change from the control unit 6, first, a data signal of a plurality of bits is output in synchronization with the clock signal 801, and then the address for storing this data is synchronized with the clock signal 802. Address signal 8
Output as 10 to 803. The memory 81 reads the address signal at the timing when the clock signal 802 is output, and writes the received data to the address. Since the address signals 810 to 813 are 4-bit signals, up to 16 types of slew rates can be stored in the memory 81. Note that the most significant bit of the data is used as a code.

After the setting of the amount of voltage change for each address A, B,...
813, the slew rate corresponding to the address B is held by the first latch circuit 82 by the first clock signal 802. In this state, when the clock signal 803 is output next, the second latch circuit 8
The value obtained by adding the output of the first latch circuit 82 to the output of the fourth latch circuit 84 is held in the second latch circuit 84. That is, as shown in FIG. 5, once the slew rate corresponding to the address signal is selected, every time the clock signal 803 is received thereafter, the output of the second latch circuit 84 increases or decreases according to the voltage change amount. I do. The slew rate of the driving waveform is determined by the voltage change amount ΔV1 stored at the address B and the unit time ΔT of the clock signal 803. The increase or decrease is determined by the sign of the data stored at each address.

In the example shown in FIG. 5, the address A stores a value 0 as a voltage change amount, that is, a value for maintaining a voltage. Therefore, when the address A becomes valid by the clock signal 802, the waveform of the drive signal is maintained in a flat state with no increase or decrease. Further, the address C stores a voltage change amount ΔV2 per unit time ΔT in order to determine a slew rate of the drive waveform. Therefore, after the address C becomes valid by the clock signal 802, the voltage decreases by this voltage ΔV2.

Thus, the waveform of the drive signal COM can be freely controlled only by outputting the address signal and the clock signal from the control unit 6.

[Waveform of Drive Signal] FIGS. 7A and 7B
(C), (D), (E), and (F) are waveform diagrams of the drive signal COM used in the ink jet recording apparatus shown in FIG. 1 and drive pulses included in the drive signal COM are applied to the pressure generating element. FIG. 4 is an explanatory diagram of signals (latch signals and channel signals) that define a period during which the drive signal COM is applied in each period when micro-vibration is performed (gradation value 1). Explanatory diagram, explanatory diagram of an application presence / absence signal DR indicating whether or not the drive signal COM is applied in each period when a small dot is formed (gradation value 2), and when an intermediate dot is formed (gradation value 3) FIG. 7 is an explanatory diagram of an application presence / absence signal DR indicating whether or not to apply the drive signal COM in each period of FIG. 7A, and whether or not to apply the drive signal COM in each period of forming a large dot (gradation value 4). Show It is an illustration of a pressurized existence signal DR.

As shown in FIG. 7A, the drive signal COM generated by the drive signal generation circuit 8 has an intermediate potential Vm.
And drive pulses COM1, COM2, COM3, and COM4 whose potentials change in the charging direction or the discharging direction. That is, the drive signal COM is transmitted to each nozzle opening 2
Dots of three to three sizes (small dots, medium dots,
A plurality of drive pulses COM1, COM2, and COM2 are formed so as to selectively form large and small dots and to cause a micro-vibration in the ink meniscus when ink droplets are not ejected.
COM3 and COM4 are included in chronological order. The term “large dot” used herein means a dot formed by, for example, about 20 ng of ink droplets, and the term “medium dot” means a dot formed by, for example, about 8 ng of ink droplets. Means a dot formed by, for example, about 4 ng of ink droplets.

Of these driving conditions, the case of no dots where no dots are formed is defined as the gradation value 1, and the cases where small dots, medium dots and large dots are formed are represented by the gradation values 2 and 3, respectively.
Assuming that the tone values are 1, 2, 3, 4, for example, (0
0), (01), (10), and (11). Therefore, the print data SI transferred from the print controller 40 to the print head 10 is data compressed to these two bits.

A plurality of such drive pulses COM1 to C
Each pressure generating element 1 is determined using the drive signal COM including OM4.
7 is driven based on the recording data SI,
Based on the application presence / absence signal DR for each nozzle corresponding to each period in one recording cycle, predetermined drive pulses COM1 to COM4 are selectively selected from the drive signal COM by the pressure generating element 1.
7 is applied.

For example, for the pressure generating element 17 corresponding to the nozzle opening 23 that does not discharge ink droplets, the first drive appearing in the period T1 to T2 of the drive pulses COM1 to COM4 included in the drive signal COM. Pulse COM
1 is selectively applied to finely vibrate the meniscus of the ink at the nozzle opening 23 to prevent the ink from drying. Therefore, the signal waveform applied to the pressure generating element 17 at this time is as shown in FIG.

With respect to the pressure generating element 17 corresponding to the nozzle opening 23 for discharging the small dot ink droplet, of the driving pulses COM1 to COM4 included in the driving signal COM, during the period T2 to T3 and the period T9 to T10. The appearing second drive pulse COM2 is applied. Accordingly, the signal waveform applied to the pressure generating element 17 at this time is as shown in FIG.

For the pressure generating element 17 corresponding to the nozzle opening 23 for discharging the medium dot ink droplet, the third of the drive pulses COM1 to COM4 included in the drive signal COM which appears in the period T4 to T5. Drive pulse COM
3 is applied. Therefore, the signal waveform applied to the pressure generating element 17 at this time is as shown in FIG.

With respect to the pressure generating element 17 corresponding to the nozzle opening 23 for discharging a large dot ink droplet, of the driving pulses COM1 to COM4 included in the driving signal COM, during the period T6 to T7 and the period T12 to T13. The appearing fourth drive pulse COM4 is applied. Therefore, the signal waveform applied to the pressure generating element 17 at this time is as shown in FIG.
As shown in FIG.

In order to selectively apply a drive pulse from the drive signal COM to the pressure generating element 17 in this manner, in the present embodiment, one bit of data is assigned as an application presence / absence signal DR for each period in one recording cycle. The desired drive pulse CO is determined by the value of each bit of the application presence / absence signal DR.
M1 to COM4 are selectively applied to the pressure generating element 17. That is, while the bit of the application presence / absence signal DR is “1”, the drive signal COM is applied to the pressure generating element 17, while the bit of the application presence / absence signal DR is “0”, The application of the drive signal COM to 17 is cut off, and the pressure generating element 17 maintains the state immediately before. Therefore, each bit of the application presence / absence signal DR is set to each drive pulse CO
By synchronizing with the generation timing of M1 to COM4, any one or more of the plurality of drive pulses COM1 to COM4 can be selectively applied.

Here, whether or not the drive signal COM is applied for each period is determined by the latch signal (LAT) shown in FIG.
And the channel signals CH (CH1, CH2,...) Are time-division-divided. That is, the period T1
Whether the drive signal COM is applied in T2 to T2 is controlled by the application presence / absence signal DR synchronized with the latch signal LAT, and thereafter, the period T2 to T3 and the period T3 to T4.
.. Is controlled by the application presence / absence signal DR synchronized with the channel signal CH (CH1, CH2,...).

For this reason, as shown in FIG. 7 (C), when the gradation value is 1, the application presence / absence signal DR in the periods T1 to T2 is "1".
(Drive pulse COM1) is applied to the pressure generating element 17, and a slight vibration is applied to the meniscus of the ink. As shown in FIG. 7D, when the gradation value is 2, the periods T2 to T
3 and the application presence / absence signal DR in the periods T9 to T10 is “1”, so during this period, the drive signal COM (drive pulse COM2) is applied to the pressure generating element 17, and the ink for small dots is ejected. Further, as shown in FIG. 7 (E), when the gradation value is 3, the application presence / absence signal DR in the period T4 to T5 is “1”, so that the drive signal COM (drive pulse COM3) generates pressure during this period. The ink is applied to the element 17 and medium dot ink is ejected. Furthermore, as shown in FIG. 7F, when the gradation value is 4, the period T
Since the application presence / absence signal DR in the period 6 to T7 and the period T12 to T13 is “1”, the drive signal COM is
(Drive pulse COM4) is applied to the pressure generating element 17, and large dot ink is ejected.

[Countermeasures against spontaneous discharge of pressure generating element 17] While the pressure generating element 17 is selectively driven using such a drive signal COM, each pressure is applied during the period when the bit of the recording data is “0”. The generating element 17 retains the previous charge, and the potential is maintained. That is, in the pressure generating element 17 or the like that does not discharge ink droplets in the current recording cycle, as shown in FIG. 8, after applying the signal for generating the micro-vibration (drive pulse COM1), the intermediate potential Vm is applied. Is done. However, even if the battery is charged at the intermediate potential Vm, the potential of the pressure generating element 17 decreases due to spontaneous discharge occurring in the pressure generating element 17 as shown by a dotted line L1 in FIG. For this reason, when the drive pulse COM1 is applied again in the next recording cycle, there is a possibility that ink droplets will be ejected by mistake. Further, even if a potential is applied to discharge ink droplets, the potential immediately before the potential is too low, and there is a possibility that a desired amount of ink droplets cannot be discharged.

Further, as shown in FIG. 10, even after the drive pulse COM3 is applied, the intermediate potential Vm is applied to the pressure generating element 17 which has finished ejecting medium dot forming ink droplets in the first half of the present recording cycle. Is long, and as shown by the dotted line L2 in FIG.
In the next recording cycle, the potential immediately before the application of the drive pulse may be too low to discharge a desired amount of ink droplet.

Therefore, in the present embodiment, in order to compensate for such a decrease in potential caused by the spontaneous discharge, the pressure generating element 17 in which spontaneous discharge is a problem is recharged. That is,
As shown in FIGS. 7C and 8, in the case of the gradation value 1, the application presence / absence signal DR is “1” also in the periods T5 to T6 and the periods T10 to T11 as in the periods T1 and T2. During this period, the drive signal COM (intermediate potential) is applied to the pressure generating element 17, and the pressure generating element 17 is recharged.

As shown in FIGS. 7 (E) and 10, when the gradation value is 3, the application presence / absence signal DR also becomes "D" in the periods T5 to T6 and the periods T10 to T11 as in the periods T4 to T5. 1 ”, the drive signal COM during this period.
(Intermediate potential) is applied to the pressure generating element 17, and the pressure generating element 17 is recharged. However, as shown in FIG. 7D and FIG.
At T6, since the pressure generating element 17 is kept at a potential other than the intermediate potential, the pressure generating element 17 is not recharged.

As shown in FIGS. 7 (F) and 11, when the gradation value is 4, the pressure generating element 17 is held at a potential other than the intermediate potential in the periods T10 to T11. The recharge of the pressure generating element 17 is not performed.

Further, as shown in FIGS. 7D, 7F, 9 and 11, periods T10 to T
11, and when the pressure generating element 17 is held at the intermediate potential as in the period T5 to T6 when the gradation value is 4, when the pressure generating element 17 does not need to be recharged, or when the ink is ejected. When recharging should not be performed in terms of performance or the like, the pressure generating element 17 is not recharged.

[Structure of Control Data] FIG.
3B is an explanatory diagram illustrating a timing at which control data SP is input to the control logic 19 and an explanatory diagram illustrating a correspondence relationship between a gradation value and an application presence / absence signal DR in the inkjet recording apparatus illustrated in FIG. is there. FIG.
FIG. 2 is an explanatory diagram showing a data configuration of control data SP used in the ink jet recording apparatus shown in FIG.

In the present embodiment, to realize the above-described driving method, the translating means 20 translates the recording data SI into the application presence / absence signal DR while referring to the control data SP in the procedure described below.

First, from the print controller 40,
The control data SP is collectively transferred to the control logic 19 of the head drive circuit 7 via the interface 49 every recording cycle. The control logic 19 is composed of a register, as will be described later, and as shown in FIG. 12A, the transferred control data SP is a latch signal LA.
It is stored in the control logic 19 in synchronization with T.

As described with reference to FIG. 7, one recording cycle includes periods T1 and T2, periods T2 and T3, and periods T3 and T3.
.., The control data SP is divided into periods T12 to T12 as shown in FIG.
13 (MSB), periods T11 to T12,... Period T1
ＴT2 (LSB), and is composed of 4-bit data for realizing a gradation value 1, a gradation value 2, a gradation value 3, and a gradation value 4. For example, the control data SP includes data (data P0 for gradation value 1) for periods T1 to T2.
0, data P01 for gradation value 2, data P for gradation value 3
02, data (00) for gradation value 4
01), and data (data P10 for gradation value 1 and data P1 for gradation value 2) for periods T2 to T3.
1, data P12 for gradation value 3 and data P for gradation value 4
13) includes data (0010). In other periods, 4-bit data corresponding to each gradation value respectively corresponds.

Therefore, when the decoder 18 translates the recording data SI of the current recording cycle into the application presence / absence data DR, if the tone value is 1, as shown in FIGS. When generating the application presence / absence signal DR corresponding to the periods T1 to T2, the control data SP includes data (P03, P02, P0) corresponding to the periods T1 to T2.
1, P00) to generate an application presence / absence signal DR of “0”, which is the data for the gradation value 1 (the data P00 of the first lower bit) among these data,
When generating the application presence / absence signal DR corresponding to T3, the control data SP refers to the data (P13, P12, P11, P10) corresponding to the periods T2 to T3, and among these data, the gradation value An application presence / absence signal DR of “0”, which is the data for one (data P10 of the lower first bit), is generated, and thereafter, the same processing is repeated, and 12 bits corresponding to twelve periods in one recording cycle are generated. Is generated.

If the gradation value is 2, the data for the gradation value 2 (data P01, P11, P21, P31 of the lower 2 bits) of the data of each period of the control data SP is used.
..) Are generated for each period within one recording cycle. If the gradation value is 3, the data for the gradation value 3 (data P02, P12, P22, P22,
32...), The application presence / absence signal DR of each period within one recording cycle is generated. If the gradation value is 4, the data for the gradation value 4 (data P03, P13, P2 of the lower 4 bits) of the data in each period of the control data SP
3, P33...), The application presence / absence signal DR for each period within one recording cycle is generated.

As a result of such translation processing, as shown in FIG. 7 and FIG. 12B, an application presence / absence signal DR for 12 periods per recording cycle is generated corresponding to each recording data SI. According to the application presence / absence signal DR, printing can be performed at a gray scale corresponding to the print data SI, and a predetermined timing (period T4 to T5, period Recharging can be performed in T10 to T11).

[Main effects of the present embodiment] As described above, in the present embodiment, the 2
Since the bit print data SI is translated into a 10-bit application presence / absence signal DR by the decoder 18 and the control logic 19 in the print head 10, the print controller 4
The data transfer amount from 0 to the recording head 10 can be reduced. Therefore, the frequency of the transfer clock for transferring the recording data SI can be reduced. Therefore, regarding the logic section, there is no problem even if the frequency of the transfer clock has to be reduced when the IC is formed using a semiconductor process.

Further, since the potential lowered from the intermediate potential Vm by the natural discharge is returned to the intermediate potential Vm again, the driving pulse C for applying a slight vibration to the ink meniscus is obtained.
The problem that ink droplets are ejected only by applying M1, and the problem that even if a potential is applied to eject ink droplets, the potential immediately before that is too low to eject a desired amount of ink droplets. Can be avoided.

During such charging, the charging is not performed for the pressure generating element 17 and the like which are held at the potential for discharging the small dot ink droplets. As described above, all the pressure generating elements 17 are not simultaneously charged at a predetermined timing, but are selectively charged only to the pressure generating elements 17 held at the intermediate potential Vm. Charging can be performed even when all the elements 17 are not held at the same potential, that is, the timing at which the elements 17 are held at the intermediate potential Vm.

Further, when the decoder 18 translates the recording data SI while referring to the control data SP output from the print controller 40 to the head driving circuit 7, the recording data SI includes a predetermined value in the control data SP. In the case of the gradation values 1 and 3, the recharging condition of when to apply the recharging voltage is also included. Therefore, the application presence / absence signal D generated by the decoder 18
Since R is data reflecting the recharging condition, the predetermined pressure generating element 17 can be selectively recharged at an arbitrary timing. Also, the control data SP
If it is rewritten, the correspondence relationship between each gradation value and the application presence / absence signal DR and the recharge condition can be easily changed.

For example, in the above-described embodiment, in the control data SP shown in FIGS. 12B and 13, data in the periods T5 to T6 in the gradation value 4 is “0”, but this is changed to “1”. Just by changing, as shown in FIG. 11, the pressure generating element 17 can be changed to be recharged immediately before the drive pulse COM4 is applied, and the voltage drop due to the spontaneous discharge that has occurred up to that point ( Dotted line L
3) can be supplemented.

Furthermore, since the control data SP need only be transferred and stored in the control logic 19 only once in one recording cycle, the drive pulses COM1, COM2,... Included in the drive signal COM having a complicated waveform are used. Even when a complicated drive condition such as selective application to the pressure generating element 17 is realized under an arbitrary condition, useless time is not spent on data transfer and the like.

[Concrete Configuration of Translation Means] In such an ink jet recording apparatus 1, the decoder 18 and the control logic 19 constituting the translation means 20 are, for example, shown in FIG.
4 to FIG. FIG. 14 is a simplified logic circuit diagram showing a specific configuration of the decoder used in the ink jet recording apparatus shown in FIG. FIG.
FIGS. 5 and 16 are circuit diagrams each showing a simplified configuration of the input side circuit and the output side circuit of the control logic used in the ink jet recording apparatus shown in FIG. In these figures, for simplification of description, the 2-bit recording data SI is translated into an application presence / absence signal DR, and the driving signal C
The circuit configuration for applying any one of the four drive pulses included in the OM to the pressure generating element 17 is shown.

In FIG. 14, the decoder 18 applies a gradation value of 1 to one nozzle (pressure generating element 17).
Four AND gates 71, 72 corresponding to 2, 3, 4
73 and 74, and an OR gate 75 to which the output of each of the gates 71 to 74 is input. Therefore, when the number of nozzles is one row, 48 nozzle openings are 6
Columns, if formed, AND gates 71-74
268 sets of logic circuits each including the OR gate 75 are provided. Further, as described above, in the latch circuit 14, the first latch circuit 131 and the second latch circuit are formed in a pair for one nozzle, and the first latch circuit 131 stores the recording data SI in the first latch circuit 131. The data of the least significant bit is latched, and the second latch circuit 132 latches the data of the most significant bit of the recording data SI.
142 (the 2-bit recording data S
I) is input to each of the AND gates 71 to 74.

The outputs V0, V1, V2, and V3 from the control logic 19 described below with reference to FIGS. 15 and 16 are input to the respective AND gates 71 to 74.

As shown in FIG. 15, the control logic 19
Is a pattern register in which four flip-flops 200 connected in one stage are divided into one recording period T
12 stages corresponding to several minutes of 1 to T2, T2 to T3,.
It is assembled. These flip-flops 200
Control data SP (program data / data) so that the output of each multiplexer 202 corresponds to a predetermined combination.
See FIG. ) Is entered. That is, a data string corresponding to a predetermined truth table is a data transfer signal (SC
In response to K), the data flows from the flip-flop 200 formed on the lower left side of the drawing. The input of the program data SP is performed once per recording cycle in the inkjet recording apparatus 1. Then, this data string (control data SP) is stored by each flip-flop 200 of each stage.

Here, each flip-flop 200 of each stage
Are connected to the respective multiplexers 202 via the flip-flops 201 shown in FIG.
Therefore, from each flip-flop 200, data P00, P10,... Of the gradation values 1, 2, 3, 4, corresponding to the periods T1 to T2, T2 to T3,.
Is input to a predetermined flip-flop 201 corresponding to the gradation values 1, 2, 3, and 4. Also, multiplexer 1
01 is supplied with the output of the counter 96. For this reason, each multiplexer 202 has a counter 9
Any one of the outputs input to itself according to the output of
Select and output one output. Therefore, the latch signal (LA
T) and channel signals CH (CH1, CH2, CH
3) are sequentially input to the counter 96, and the outputs V0, V1, V2, V3 from the multiplexer 202 are output.
Is input to the AND gates 71 to 74 shown in FIG. 14, so that only one of the AND gates 71 to 74 may output “1”.

The AND gates 71 to 74 have the first
And the data (2-bit recording data SI) latched by the second latch circuits 141 and 142 are input, and depending on the combination of these inputs, any one of A
When the output of the ND gates 71 to 74 becomes “1”, the output of the OR gate 75 becomes “1” and the driving signal C
A predetermined driving pulse is selected from the OM and the pressure generating element 17 is selected.
Can be applied. In this manner, the 2-bit recording data SI is translated into the application presence / absence signal DR for selecting a predetermined drive pulse from the drive signal COM.

In the ink jet recording apparatus 1 configured as described above, the combination of the gradation value and the driving pulse can be freely set by changing the control data SP. Further, even when a complicated driving condition such as applying a predetermined potential from the driving signal COM to the predetermined pressure generating element 17 only at a predetermined timing and performing a charge for supplementing the spontaneous discharge is realized, the predetermined control data SP is not used. What is necessary is just to input to the flip-flop 200 which comprises the control logic 19. Therefore, there is an advantage that it is not necessary to increase the number of signal lines even when driving conditions are complicated.

[0080]

As described above, in the ink jet recording apparatus according to the present invention, the pressure generating element which is maintained at a charged state at the intermediate potential by suspending the ejection of ink droplets in the current recording cycle, or Until the charging potential for ejecting ink droplets is applied in the present recording cycle, the driving signal is selectively applied to the pressure generating element, etc., which is maintained at the charged state at the intermediate potential. Select and apply a potential. Therefore, it is possible to avoid a problem that even if a potential is applied to discharge an ink droplet, the potential immediately before the potential is too low to discharge a desired amount of ink droplet. Also, all the pressure generating elements are not charged at the same time at a predetermined timing, but are selectively charged only to the pressure generating elements held at the intermediate potential. , That is, at a timing not held at the intermediate potential.

[Brief description of the drawings]

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

FIG. 2 is a block diagram of the ink jet recording apparatus shown in FIG.

FIG. 3 is a cross-sectional view of an actuator formed on a recording head of the ink jet recording apparatus shown in FIG.

FIG. 4 is a block diagram of a drive signal generation circuit formed in the inkjet recording apparatus shown in FIG.

FIG. 5 is an explanatory diagram showing a process of generating each pulse included in the drive signal in the drive signal generation circuit shown in FIG.

6 is a timing chart showing the timing of each signal when a slew rate is set in a memory based on a data signal in the drive signal generation circuit shown in FIG. 4;

FIG. 7 (A), (B), (C), (D), (E),
(F) is a waveform diagram of a drive signal used in the ink jet recording apparatus shown in FIG. 1, an explanatory diagram of a signal that defines a period in which a drive pulse included in the drive signal is applied to the pressure generating element, and performs fine vibration. FIG. 4 is an explanatory diagram of an application presence / absence signal indicating whether or not a drive signal is applied in each period of a case (gradation value 1), and a drive signal is applied in each period of forming a small dot (gradation value 2). Explanatory diagram of an application presence / absence signal indicating whether or not a medium dot is formed (gradation value 3)
FIG. 7 is an explanatory diagram of an application presence / absence signal indicating whether or not a drive signal is applied in each period of FIG. 7A, and an application presence / absence indicating whether or not a drive signal is applied in each period of forming a large dot (gradation value 4) FIG. 4 is an explanatory diagram of a signal.

FIG. 8 shows a configuration of the ink jet recording apparatus shown in FIG.
FIG. 6 is a waveform diagram of a driving signal for generating a meniscus micro-vibration applied to a pressure generating element that does not discharge an ink droplet.

FIG. 9 shows a configuration of the ink jet recording apparatus shown in FIG.
FIG. 5 is a waveform diagram of a drive signal applied to a pressure generating element that ejects small dot ink droplets.

10 is a waveform diagram of a drive signal applied to a pressure generating element that ejects medium dot ink droplets in the ink jet recording apparatus shown in FIG.

11 is a waveform diagram of a drive signal applied to a pressure generating element that ejects a large dot ink droplet in the ink jet recording apparatus shown in FIG.

12A and 12B are explanatory diagrams illustrating timings at which control data is input in the inkjet recording apparatus illustrated in FIG. 1, and a description illustrating a correspondence relationship between each gradation value and an application presence / absence signal. FIG.

FIG. 13 is an explanatory diagram showing a data configuration of control data used in the ink jet recording apparatus shown in FIG.

14 is a simplified logic circuit diagram showing a specific configuration of a decoder used in the ink jet recording apparatus shown in FIG.

FIG. 15 is a simplified circuit diagram showing a configuration of an input side circuit of control logic used in the ink jet recording apparatus shown in FIG.

16 is a simplified circuit diagram showing a configuration of an output side circuit of control logic used in the ink jet recording apparatus shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink jet recording apparatus 5 Print engine 6 Control part 7 Head drive circuit (head drive means) 8 Switch circuit 10 Recording head 13 Shift register 14 Latch circuit 15 Level shifter 16 Switch circuit 17 Pressure generating element 18 Decoder 19 Control logic 20 Translator 21 Recording Data storage means CH, CH1, CH2... Channel signal COM drive signal COM1 to COM4 drive pulse DR application / non-application signal SI record data SP control data

Claims (6)

[Claims] A recording head for ejecting ink droplets from the nozzle openings by a plurality of pressure generating elements corresponding to each of the plurality of nozzle openings pressurizing ink in a pressure generating chamber communicating with the nozzle openings; A drive signal generating means for generating a common drive signal including a plurality of drive pulses to be applied to the pressure generating element, and any one of the drive pulses, or a plurality of drive pulses, based on print data. An ink jet recording apparatus having a head driving unit for applying a voltage to a generating element, wherein the head driving unit is charged to a potential equal to a potential of the driving signal at a predetermined timing in one recording cycle in the pressure generating element. For the pressure generating element, the potential is selectively selected from the drive signal to recharge the pressure generating element. An ink jet recording apparatus according to claim and. 2. The head driving means according to claim 1, wherein the head driving means selectively applies the intermediate potential to a pressure generating element that is charged to an intermediate potential in the drive signal among the pressure generating elements. An ink jet recording apparatus, wherein the pressure generating element is recharged by selecting from a drive signal. 3. The pressure generating device according to claim 2, wherein the pressure generating element charged to the intermediate potential suspends the ejection of ink droplets in a current recording cycle, and the pressure maintained at the intermediate potential charged state. An ink jet recording apparatus, which is a generating element. 4. The driving pulse according to claim 2, wherein the pressure generating element charged to the intermediate potential discharges an ink droplet in a current recording cycle or discharges an ink droplet in a current recording cycle. An ink-jet recording apparatus, wherein the pressure generating element is maintained in a charged state until the intermediate potential is applied. 5. The method according to claim 1, wherein
The head driving unit is driven by a recording data storage unit that stores input recording data for each nozzle, a nozzle driving condition corresponding to the recording data, and a condition corresponding to predetermined recording data among the recording data. Control data storage means for storing control data including recharge conditions for applying a voltage for recharge at a predetermined timing to the pressure generating element, and the recording data storage means and the control data storage means Based on the stored print data and the control data, the timing at which the drive signal is applied to the pressure generating element is translated into an application presence / absence signal that defines for each nozzle and each period within one recording cycle. An ink jet recording apparatus, comprising: a translation unit. 6. The control data according to claim 5, wherein:
The translation means is collectively transferred and stored to the control data storage means, and the translation means performs the application for each period in one recording cycle based on the recording data for each nozzle stored in the recording data recording means. When the presence / absence signal is generated, the application presence / absence signal is generated by selectively referring to control data of a corresponding period from the control data stored in the control data storage unit. An ink jet recording apparatus characterized by the above-mentioned.