JP3535858B2 - Ink jet recording apparatus and ink jet head driving method - Google Patents

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 and an ink jet head driving method using an ink jet head for printing by ejecting ink onto a print medium.

[0002]

2. Description of the Related Art (Technical Background) A printing apparatus used as an image output means such as a printer, a copying machine, a facsimile machine, etc., prints a dot pattern on a printing medium such as paper, a plastic thin plate, cloth or the like based on given image information. It is configured to form a different image. The printing apparatus, depending on the image forming method, is a thermal method such as an inkjet method, a wire dot method, or a thermal transfer method.
Inkjet printing apparatuses that employ an inkjet method, such as a laser beam method, eject ink (recording liquid), for example, as droplets from an ejection port provided in an inkjet head, and attach this to a print medium. It is configured to print.

As one form of an ink jet head used in such an ink jet system, an electrothermal conversion element (ejection heater) is provided in a liquid path communicating with an ejection port, and expansion of bubbles generated by the action of heat generated by energization of the element. There is a method that uses force as a driving force for ink ejection (for example, a bubble jet (registered trademark) method proposed by Canon Inc., which ejects ink by causing film boiling in the ink). With this method, an inkjet head can be manufactured through a process similar to the semiconductor manufacturing process. For this reason, the size of the discharge heater (hereinafter, generically referred to as a nozzle) provided along the liquid path in the vicinity of or inside each discharge port (hereinafter, collectively referred to as a nozzle) is set to generate the energy used for ink discharge. It has an advantage that it can be made much smaller than a piezoelectric element used as an element that enables high-density mounting of nozzles.

In the ink jet head in which a large number of nozzles are mounted in this way, the ejection heater group is divided into a plurality of blocks in order to limit the number of ejection heaters simultaneously driven from the viewpoint of suppressing the upper limit value of the maximum power consumption. However, it is common to perform time-divisional drive in units of blocks within a predetermined drive cycle.

A conventional example of such time-divisional drive will be described with reference to FIGS. First, FIG. 1A is a diagram for explaining a correspondence between nozzles arranged in an inkjet head and signal waveforms applied to a discharge heater provided for each nozzle.

In FIG. 1 (A), reference numeral 1000 is an ink jet head, which is schematically shown as viewed from the front of the ejection port. Nozzles 1 to 12 are nozzles or their ejection ports, from which ink is ejected and landed on a print medium to form an image. Here, in recent years, inkjet heads have been used in order to achieve high-speed printing and high image quality.
Although there is a tendency for ~ 2000 nozzles to be mounted, here, for the sake of simplicity of description, the inkjet head 1 is used.
000 is shown as having 12 nozzles.

In the figure, the timing chart shown on the right side of the ink jet head 1000 shows the waveform of the signal supplied to the discharge heater of each nozzle in association with each nozzle. The vertical axis is the applied voltage, and the "H" level is the energized (ON) state, and the "L" level is the de-energized (OFF).
It is in a state. The horizontal axis is the time axis.

The nozzle array is shown as nozzles 1-12 from the top of the figure for convenience. These twelve nozzles are made into a set of three nozzles each, and the nozzles are driven by being divided into four blocks composed of ejection heaters that are simultaneously driven. Specifically, when the applied voltage is at the “H” level, the nozzle discharges ink using the force of energizing the discharge heater and expanding the bubbles generated by heating. On the other hand, the applied voltage is "L"
At the level, power is not supplied and ink is not ejected.
Of these 12 nozzles, nozzles 1, 5, 9 are the first
The nozzles 2, 6 and 10 are driven in a time division manner at the timing of the block, the nozzles 2, 6 and 10 at the timing of the second block, the nozzles 3, 7 and 11 at the timing of the third block, and the nozzles 4, 8 and 12 at the timing of the fourth block. And as a result of this, the first
~ The ejection openings of the fourth block sequentially perform ejection operation.

FIG. 2 is a conventional example of a drive circuit for performing such time division drive, and FIG. 3 is an operation timing chart of each part of the drive circuit.

In FIG. 2, reference numeral 100 is a one-shot circuit, which is a circuit for detecting a rising edge of a predetermined encoder signal and generating a one-shot pulse signal A.
For example, in a so-called serial type printing apparatus, the encoder signal is a signal that is generated at equal intervals during the main scanning of the print medium by the inkjet head. The one-shot pulse signal A is supplied to the timer circuit 114 and the one-shot circuit 102 in parallel.

The timer circuit 114 is reset by the pulse signal A, and the signals B at equal intervals are generated from the pulse signal A, and the signal B is shifted by the shift circuit 103 and the heat pulse generating circuit 1.
It is connected so that it may be inputted into 04. This signal B
Is the reference signal for the block drive interval in FIG.

The configuration and operation of the timer circuit 114 will be described with reference to FIG. 9A is a timer circuit diagram, and FIG. 9B is an operation timing chart thereof. In the figure, 110, 111, 112 and 113 are T-type flip-flops (hereinafter referred to as TFF). TFF
The pulse input to 110 has a frequency of 800 kH, for example.
It is a square wave of z. The TFF 110 outputs the pulse signal Q output from the terminal Q at each rising edge of the input pulse signal.
Invert 1 As described above, the TFF can halve the frequency by dividing the input signal by one stage. In the figure, since the TFF is connected in four stages, the output pulse B of the final stage TFF 113 is Has a frequency of 50 kHz
Becomes a square wave. The above-mentioned pulse signal A is supplied to the reset input terminals R of the TFFs 110 to 113, respectively. Therefore, every time the one-shot pulse signal A is input, the TFFs 110 to 113 are reset, and the output signals Q1, Q2, Q3 and B of each stage are in the "L" state.
After that, since a pulse signal having a frequency of 800 kHz is input to the TFF 110, the signal B which is started at the trailing edge of the signal A and divided by four stages is output.

Referring to FIGS. 2 and 3, the one-shot circuit 102 generates a one-shot pulse signal at the falling edge of the signal B and further outputs an OR signal C of the pulse signal and the pulse signal A. This signal C is supplied to the heat pulse generation circuit 104. On the other hand, the shift circuit 103 having the form of the Johnson counter circuit has pulse signals QA1 to QA1 at the timing of the signal B, as shown in FIG.
QA4 is output in a time division manner, and the heat pulse generation circuit 104
To enter.

The heat pulse generation circuit 104 generates a signal for energizing the discharge heater and outputs it to the driver circuit 105. Here, the information on the energization time to the ejection heater for ejecting ink is supplied by a microcomputer or the like, which is a control unit of a printing device (not shown), and the information on the energization time to the ejection heater (heat pulse width). Is prescribed. As shown in FIG. 3, the heat pulse generation circuit 104 outputs the block drive signal BL1 for the time defined by the above information at the rising timing of the pulse signal QA1 and supplies it to the driver circuit 105.
Similarly, the heat pulse generation circuit 104 outputs the pulse signal Q
At each rising timing of A2, QA3, and QA4, the block drive signals BL2, BL3, and BL4 are output for a time defined by the above information and supplied to the driver circuit 105.

The driver circuit 105 supplies a drive signal to an ejection heater corresponding to a nozzle for ejecting ink according to image information. The driver circuit 10 according to the image information
The signals supplied to 5 (signals that define the presence or absence of ejection of each nozzle according to the image information) are signals indicated by G1 to G12 and are input from a control unit (not shown). That is, the driver circuit 105 generates drive signals for the ejection heaters permitted by the signals G1 to G12 at the timings of the block drive signals BL1 to BL4.

[0016]

FIG. 1B is a diagram showing a pressure change in the liquid chamber of the ink jet head caused by the driving of the discharging heater or the discharging operation of the nozzle as described above, and the vertical axis represents the pressure. The horizontal axis is the time axis. A broken line shown along the time axis indicates a pressure equal to the external atmospheric pressure, a portion above the broken line indicates high liquid chamber pressure, and a lower portion indicates low liquid chamber pressure.

Assuming that the driving cycle of the entire ink jet head is an ejection cycle, one ejection cycle has a driving period assigned to the first block (FIG. 1A).
In the fourth block, a period from the start of the block interval "1") to the end of the drive period (block interval "4" in FIG. 1A) assigned to the fourth block and the fourth block. The period from the end of the assigned driving period to the start of driving the next first block (hereinafter,
OFF period) is included. In the ON period, bubbles generated by heat generation of the ejection heater act as a force for ejecting the ink from the ejection port, and at the same time, a force for pushing the ink back to the liquid chamber in the nozzle, so that the pressure in the liquid chamber rises. To do. On the other hand, in the OFF period, the pressure in the liquid chamber decreases due to the refill operation (the operation of filling the nozzles with ink due to the capillary phenomenon). When the inkjet head 1000 is continuously driven, ON periods and OFF periods appear alternately and repeatedly, and the pressure in the liquid chamber fluctuates in the ejection cycle. As a result, a pressure wave in the liquid chamber is generated.

By the way, in the method of ejecting the ink by applying thermal energy to the ink like the above-mentioned bubble jet (registered trademark) method, when the ink is rapidly heated by the ejection heater, the ink near the surface of the ejection heater is heated. The water, which is the main component of the water, changes its state to become water vapor.
This becomes bubbles and ink is ejected by using the expanding force as a driving force. The bubbles caused by the steam generated at that time,
When the discharge heater is de-energized, water vapor returns to water and defoams. However, the air that had dissolved in the ink was
Due to the temperature rise of the ink due to the continuous driving, it becomes difficult for the ink to be dissolved in the ink and remains as bubbles.

Generally, in order to form an image with a large number of ink dots, it is necessary to eject a large number of inks, and one nozzle may carry out an ejection operation several thousand to tens of thousands of times. Then, as described above, the bubbles due to the melted air may accumulate and grow with time to become bubbles having a relatively large particle size and stay in the liquid chamber. When such bubbles stay in the liquid chamber, the natural frequency of the meniscus surface (the boundary surface between the ink and the air (outside air)) of the ejection port of the nozzle lowers and the vibration easily occurs. . When it is near the driving frequency, resonance easily occurs. In the resonance state, when the pressure in the liquid chamber rises, the ink at the ejection port becomes convex toward the outside of the nozzle, and when the pressure in the liquid chamber decreases, the ink becomes concave toward the inside of the nozzle. By repeating this, the meniscus surface vibrates (hereinafter, this phenomenon is referred to as meniscus vibration).

As described above, when the ejection operation is performed at the timing when the ink at the ejection port is in the convex state, the amount of ejected ink is large, and conversely, when the ejection operation is performed at the timing when the ink is in the concave state, the ejection operation is performed. Less ink. As described above, when the amount of ink ejected from the nozzles fluctuates, streaks occur in the formed image, which causes deterioration in image quality.

This phenomenon will be described in detail with reference to FIG.
This figure is a view for explaining the side cross section of the inkjet head and the state of meniscus vibration that occurs at the ejection openings of each nozzle, and the vertical axis is the surface of the ejection openings of each nozzle in contact with the ink (meniscus surface). ) Indicates the state.
In addition, it is a normal state when there is a meniscus surface at the position of the broken line drawn corresponding to each ejection port, and as it goes upward from this state, the meniscus surface protrudes outward from the ejection port in a convex shape, On the contrary, as it goes downward, the meniscus surface is recessed inward of the discharge port.

In FIG. 1 (C), reference numeral 1004 is a bubble staying in the liquid chamber 1001 as described above,
In this figure, it exists near the nozzle 1. Resonance of the meniscus surface is more likely to occur in the nozzle located closer to the staying bubble 1004, and the amplitude of meniscus vibration is larger. However, resonance in the meniscus surface is less likely to occur in the nozzle farther from the bubble 1004, and meniscus vibration is smaller. .
In this way, the difference in meniscus vibration causes a difference in the amount of ink ejected from each nozzle and the ejection direction, and as a result, streaks due to spots are formed in the formed image, resulting in a significant deterioration in image quality.

Therefore, the applicant of the present invention has proposed that all of the discharge ports (6
Ink is ejected at the same timing from the number (1) of ejection ports having an ink amount of 7% or less of the amount ejected from (4 units), and the ink ejection period from all ejectable ejection ports is a drive cycle. An ink jet recording apparatus having 70% or more of the above has been proposed (Japanese Patent Laid-Open No. 05-084911). According to the technique disclosed in the same publication, since the level of the negative pressure generated in the liquid chamber can be brought to the closest to the normal pressure by minimizing the amount of ink ejected within a unit time, the amplitude of refill vibration can be minimized. As a limit, it is described that the ejection can be stabilized and the driving frequency can be further improved.

To explain the technique disclosed in the above publication with reference to FIG. 1, "to set the ink ejection period to 70% or more of the driving cycle" means that the ON period is 70% or more of the ejection cycle. Means It can be expressed as follows. ON
Period> ejection cycle × 0.7 And, by setting in this way, the pressure fluctuation in the liquid chamber as shown in FIG. 1 (B) is reduced, and the accumulated bubbles 1004 as shown in FIG. 1 (C) grow. Also, the amplitude of meniscus vibration is small. That is, the closer the ON period is to the drive cycle,
Since the driving frequency component of the pressure wave in the liquid chamber becomes small, meniscus vibration can also be made small.

However, since the operation of transferring the data for causing the ink jet head to perform the ejection operation is performed using the OFF period, the OFF period cannot be eliminated at all. Therefore, as long as the OFF period exists, the drive frequency component remains in the pressure wave in the liquid chamber by the above-described drive method, and therefore it is inevitable that the meniscus surface resonates to cause meniscus vibration. As long as the meniscus vibration occurs, the ink ejection amount and the ejection direction vary depending on the ink ejection timing as described above, and the quality of the formed image deteriorates.

An object of the present invention is to solve the above-mentioned problems, and it is possible to suppress meniscus vibration so as to perform stable ink ejection, and thus to perform high-quality printing. To do.

[0027]

To this end, the present invention provides
In an inkjet recording apparatus that performs recording by using an inkjet head having a plurality of ejection ports for ejecting ink and a liquid chamber that supplies ink to the plurality of ejection ports, the ink is ejected from the plurality of ejection ports a block dividing unit for a plurality of recording elements divided into a plurality of blocks and drives to be used for, min the block dividing means
A block for specifying the drive interval of each divided block.
Means for generating a clock signal and the block dividing means
Based on the selected block signal and image signal
Means for driving the child in a time division manner, and by the block signal
If the drive interval of each block is made non-uniform within the discharge cycle
Both are provided with a control means for performing control so as to make non-uniformity even in each discharge cycle .

The present invention also provides an ink jet recording apparatus for performing recording using an ink jet head having a plurality of ejection openings for ejecting ink and a liquid chamber for supplying ink to the plurality of ejection openings. Block dividing means for dividing a plurality of recording elements used for ejecting ink from a plurality of ejection openings into a plurality of blocks and driving them within a predetermined ejection cycle; and division by the block dividing means.
Block for specifying the driving interval of each block
The means for generating the signal and the block dividing means
Each recording element based on the block signal and the image signal
Means for time-division driving, and
While making the block drive interval uniform within the discharge cycle,
The drive start timing of the first block in the ejection cycle is determined by the block signal for each ejection cycle.
And a control means for performing control so as to be random .

Further, the present invention provides a driving method for an ink jet head having a liquid chamber communicating with the plurality of ejection ports and the plurality of discharge ports for discharging ink, said plurality
Multiple used to eject ink from each ejection port
The recording element of is divided into multiple blocks
A block that generates a block signal to set the drive period
Clock signal generation step, and the block signal and the image signal
A step of time-divisionally driving each of the recording elements based on
The drive interval of each block can be changed by the block signal.
Non-uniform within the period and non-uniform in each discharge cycle
And a control step for performing such control .

Further, according to the present invention, in an ink jet head driving method having a plurality of ejection ports for ejecting ink and a liquid chamber communicating with the plurality of ejection ports, the ink is ejected from the plurality of ejection ports. a block dividing step of performing driving in a predetermined ejection circumferential <br/>-life a plurality of recording elements divided into a plurality of blocks used for the block
Specify the drive interval of each block divided by the dividing means.
Generating a block signal for the block signal, and the block signal
And each of the recording elements are time-divisionally driven based on
And the step of driving each block by the block signal
The interval is made uniform within the discharge cycle and the block signal is
To randomly drive start timing of the first of said blocks for each of the ejection cycle in the discharge period by No.
And a control step for performing control so as to control .

In the above, the ink jet head has a heating element as the recording element, which gives heat energy for causing film boiling in the ink, or
A piezoelectric element may be included as the recording element.

[0032]

In the present invention, it is conceived that the meniscus surface should not resonate with the pressure wave in the liquid chamber in order to suppress the meniscus vibration, and therefore the frequency of the pressure fluctuation in the liquid chamber due to the ink ejection operation. The inkjet head is driven so that is different from the driving frequency of the inkjet head.

That is, in the present invention, when a plurality of printing elements are divided into a plurality of blocks for driving, the driving intervals of the blocks are set so as not to be uniform. Alternatively, a plurality of recording elements may be divided into a plurality of blocks, and
To carry out the driving in the discharge period, the period of the drive start timing of the first of the block in the discharge period so as not uniform in the discharge circumferential period (i.e., from the start of the discharge cycle until the first discharge is started Is set so as to be different between the discharge cycles).

By preventing resonance of the meniscus surface by these, meniscus vibration can be reduced,
It is possible to obtain a stable ink ejection state and perform high-quality printing without spots and streaks.

In the present specification, "print" (sometimes referred to as "recording") means not only the formation of significant information such as characters and figures, but also significant insensitivity and human visual perception. Regardless of whether or not it is actualized, it means a case where an image, a pattern, a pattern, etc. are widely formed on a print medium or a case where the print medium is processed.

The term "printer" means not only one complete device for printing, but also a device having a printing function.

The "print medium" is not limited to paper used in a general printing apparatus, but can widely accept ink such as cloth, plastic film, metal plate, glass, ceramics, wood and leather. In the following, the term "paper" or simply "paper" will be used.

Further, "ink" (which may be referred to as "liquid") is to be broadly construed in the same way as the definition of "print", and when applied on a print medium, an image or a pattern is formed. , A liquid used for forming a pattern or the like, processing a print medium, or treating an ink (for example, solidifying or insolubilizing a coloring material in the ink applied to the print medium).

[0040]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. In the following explanation,
Corresponding parts are designated by the same reference numerals to the respective parts that can be configured similarly to the above-mentioned conventional example or perform similar functions.

(Overall Structure of Inkjet Printing Apparatus) FIG. 5 is a schematic perspective view of an inkjet printing apparatus to which the present invention can be applied.

In this ink jet printing apparatus, the carriage 200 is fixed to the endless belt 201,
Moreover, it is movable along the guide shaft 202. The endless belt 201 is wound around pulleys 203 and 204. A drive shaft of a carriage drive motor 205 is connected to the pulley 203. Therefore, the carriage 200 is reciprocally scanned in the main scanning direction (direction A) along the guide shaft 202 by the rotational driving of the motor 205. An inkjet head 1000 in which a plurality of nozzles are arranged and an ink tank IT as a container for storing ink are mounted on the carriage 200.

The apparatus is also provided with a linear encoder 206 for detecting the moving position of the carriage. The linear encoder 206 includes a linear scale 207 that extends along the moving direction of the carriage 200 and has slits formed at equal intervals such as 600 in 1 inch (reference value: about 25.4 mm), and the carriage 200. It has a slit detection system 208 provided above, for example, having a light emitting section and a light receiving sensor, and a required signal processing circuit. Therefore, the linear encoder 206
Then, as the carriage 200 moves, an ejection timing signal that defines the ink ejection timing and carriage position information are output. If ink is ejected every time a slit is detected, 600 dpi in the main scanning direction
It is possible to execute printing with a resolution of (dot / inch. Reference value).

The recording paper P as a print medium is intermittently conveyed in the direction of arrow B (sub scanning direction) orthogonal to the main scanning direction of the carriage 200. The recording paper P is supported by a pair of roller units 209 and 210 on the upstream side and a pair of roller units 211 and 212 on the downstream side, and is fed with a certain tension to ensure flatness with respect to the head 1000. . The driving force for each roller unit is applied by a recording paper conveyance motor (not shown).
With such a configuration, printing is performed on the entire recording paper P while alternately repeating the printing of the width corresponding to the ejection opening array width of the head accompanying the movement of the carriage 200 and the feeding of the recording paper P.

The carriage 200 is stopped at the home position at the start of printing or during printing, if necessary. At this home position, a cap member 213 that caps the ejection surface side of each head is provided, and this cap member 213 forcibly absorbs ink from the ejection port to prevent clogging of the ejection port. Suction recovery means (not shown) is connected.

(Structure of Inkjet Head) Next, an example of the structure of an inkjet head applicable to the above apparatus will be described with reference to FIGS. FIG. 6 is a perspective view of the inkjet head 1000 as seen obliquely from below, and FIG. 7 is a perspective view thereof. FIG. 8 shows an inkjet head 100.
FIG. 9 is a cross-sectional view of the inkjet head 1000 cut at a right angle to the nozzle array direction, and FIG. 9 is a cross-sectional view of the inkjet head 1000 cut in the nozzle array direction. 10 to 12 are views showing the inkjet head 1000 cut along a plane parallel to the recording paper P, FIG. 10 is a sectional view of a D portion in FIG. 9, and FIG. 11 is a sectional view of an E portion. FIG. 12 is a sectional view of the portion F as well.

In these drawings, reference numeral 1003 denotes an ejection port, and the ink jet head 1000 has a plurality of ink ejections arranged in parallel in the conveyance direction of the recording paper P on the surface facing the recording paper P as a print medium. An outlet 1003 is formed. A liquid passage 1005 is provided in the inkjet head 1000 so as to communicate with each of the plurality of ejection ports, and electricity for generating thermal energy used to eject ink is provided corresponding to each liquid passage 1005. A heat conversion body (discharge heater) 1002 is provided. The ejection heater 1002 generates heat by being applied with an electric pulse according to drive data, thereby causing film boiling in the ink, and using the generation of the bubbles as the driving force, the ejection port 102.
Ink is ejected from 03. Each liquid passage 1005 is provided with a common liquid chamber 1001 that communicates with them in common, and this common liquid chamber 1001 is connected to the ink tank IT.

(First Example of Embodiment) A first example of driving an ink jet head according to an embodiment of the present invention will be described with reference to FIGS.

FIG. 13A is a diagram for explaining the correspondence between the nozzles arranged in the ink jet head and the signal waveform applied to the discharge heater provided for each nozzle. In the figure, the inkjet head 1000 is shown as having 12 nozzles for the sake of simplicity. From the top of the figure, nozzle 1, nozzle 2 ,.
-It is assumed that the nozzles 11 and 12 are arranged.

In the drawing, the timing chart shown on the right side of the ink jet head 1000 shows the waveform of the signal supplied to the discharge heater of each nozzle in association with each nozzle. The vertical axis is the applied voltage, and the "H" level is the energized (ON) state, and the "L" level is the de-energized (OFF).
It is in a state. The horizontal axis is the time axis.

A set of 12 nozzles, 3 nozzles each, 4
It is divided into individual groups (blocks). Then, when the applied voltage is at the “H” level, the nozzle discharges ink by utilizing the force of energizing the discharge heater and expanding the bubbles generated by heating. On the other hand, when the applied voltage is at the "L" level, power is not supplied and ink is not ejected. Of these 12 nozzles, nozzles 1, 5 and 9 are at the timing of the first block, nozzles 2, 6 and 10 are at the timing of the second block, nozzles 3, 7 and 11 are at the timing of the third block, and The nozzles 4, 8 and 12 are driven in a time division manner at the timing of the fourth block, and as a result, the ejection openings of the first to fourth blocks sequentially perform ejection operations. Then, as shown in the figure, the driving period (hereinafter,
"1" to "4" (referred to as block intervals) are randomly determined so as not to be uniform.

FIG. 13B is a diagram showing the pressure change in the liquid chamber of the ink jet head caused by the driving of the discharge heater or the discharge operation of the nozzles as described above, where the vertical axis is the pressure and the horizontal axis is the time axis. is there. The broken line shown along the time axis is the pressure equal to the external atmospheric pressure (1 atm), the part above this broken line shows high liquid chamber pressure, and the lower part shows low liquid chamber pressure. There is. In this example, FIG.
As shown in (A), since the block intervals are random, the frequency components of the pressure wave in the liquid chamber are dispersed.

FIG. 13C is a view for explaining the side cross section of the ink jet head and the state of meniscus vibration occurring at the ejection port of each nozzle in this example, and the vertical axis indicates the ejection port of each nozzle. The state of the surface (meniscus surface) where ink and air are in contact is shown. In addition, it is a normal state when there is a meniscus surface at the position of the broken line drawn corresponding to each ejection port, and as it goes upward from this state, the meniscus surface protrudes outward from the ejection port in a convex shape, On the contrary, as the position goes down, the meniscus surface is recessed inwardly in the discharge port.However, in this example, by randomly setting the block interval, the frequency component of the pressure wave in the liquid chamber is dispersed and resonance of the meniscus surface is generated. No meniscus vibration is generated.

In this example, the nozzles are driven by being divided into four groups (blocks), but this is for the sake of simplification of description, and the circuit configuration used at the time of implementation is simple. This is because it is considered to be effective in transforming. That is, the main object of the present invention is to disperse the frequency component of the pressure wave in the liquid chamber, and therefore the number of divided blocks can be appropriately determined including the number of nozzles. For example, energization timing is provided for each nozzle. Alternatively, the number of groups may be other than four.

FIG. 14 shows an example of the configuration of a drive circuit for performing time-divisional drive in which the above block intervals are random, and FIG.
Is an operation timing chart of each part of the drive circuit.

In FIG. 14, the one-shot circuit 100
Detects the rising edge of a predetermined encoder signal and generates a one-shot pulse signal A. The encoder signal is a signal output from the encoder 206 that reads the linear scale 207 having slits at equal intervals while the carriage 200 mounting the inkjet head 1000 moves in the main scanning direction.
Is a signal that is generated at equal intervals when the main scanning is performed at a constant speed.
The one-shot pulse signal A is supplied in parallel to the block drive reference signal generation circuit 101 and the one-shot circuit 102.

The structure and operation of the one-shot circuit 100 will be described with reference to FIG. The circuit diagram of FIG.
(B) is an operation timing chart thereof.

In the figure, 107 and 108 are D-type flip-flops (D-type bistable multivibrator.
It is abbreviated as DFF), and latches the information input to the D terminal at the rising timing of the clock signal of 1 MHz and holds it at the Q output terminal. At that time, the inverted output terminal / Q holds the inverted signal of the Q output.
Further, when an "H" level signal is input to the reset (R) input terminal of the DFF, Q = "L" and / Q = "H".

The signal PUC input to the R input terminal is a signal that becomes "H" level for a moment when a power source (not shown) is turned on, and becomes "L" level when the power supply circuit has settled down. This signal PUC is the DFF 107 and 108.
It is supplied to the R input terminal of the
Q of the F107 is "L", and / Q of the DFF 108 is "H".

The clocks (C
K) 1 MHz square wave is input to the input terminal. Since the encoder signal is input to the D input of the DFF 107, the Q output of the DFF 107 is an encoder signal whose output changes in synchronization with the clock signal of 1 MHz. Since the Q output of the DFF 107 is connected to the D input of the DFF 108, the output of the DFF 108 is D
It changes with a delay of one clock from the Q output of the FF107. In this case, the delay of 1 clock is 1 μs because the clock signal of 1 MHz is used.
An AND gate 109 outputs a signal A obtained by ANDing the Q output of the DFF 107 and the / Q output of the DFF 108. With the above configuration, the one-shot circuit 100
Is “H” only for the rising edge of the encoder for 1 μs
The signal A that becomes is output.

Referring again to FIG. 14, the circuit 101 is reset by the pulse signal A, and the pulse signal B is generated from the circuit 101 at random timing, and this signal B is input to the shift circuit 103 and the heat pulse generation circuit 104. Are connected as they are. This signal B serves as a reference signal for the block drive interval in FIG. The pulse signal B is a signal of equal intervals in the conventional example, but is a pulse having a random width in this example.

Details of the circuit 101 will be described with reference to FIG. 9A is a circuit diagram thereof, and FIGS. 9B and 9C are operation timing charts. The TFFs 110 to 113 connected in series as in FIG. 4 divide the frequency of the signal input to the clock input terminal CK by two and hold it at each Q output terminal. Further, when the signal A = “H”, the “H” level signal is input to the R input terminals of all the TFFs, so that Q1 = Q2 = Q3 = Q4 = “L” (reset). That is, the TFFs 110 to 113 are reset at the rising timing of the encoder signal.

Assuming that a square wave of 800 kHz is input to the TFF 110, this signal has Q1 = 4.
00kHz, Q2 = 200kHz, Q3 = 100kHz
, And each is divided. The signal Q3 is input to the TFF 113, and the output B divided into 50 kHz is obtained.
This output B is also supplied to one input terminal of the AND gate 1114.

When this output B = "H", the signal RND = supplied to the other input terminal of the AND gate 1114 =
If it is "H", the output of the AND gate 1114 is "H".
It becomes a level. The output of the AND gate 1114 is connected to the OR gate 1115. When the "H" level signal is input from the AND gate 1114, the OR gate 1114
The output of 15 also becomes "H" level and resets the TFF 113.

As described above, it takes 10 μs after the signal A falls to bring the signal B to the “H” level, and before 10 μs has elapsed, RND = “H”.
Then, the TFF 113 is reset. in this way,
The signal B becomes a signal that varies in 10 μs to 20 μs.
This signal B is the signal that serves as the reference of the block interval in this example.

The RND signal is a signal output from the random signal generation circuit 106 shown in FIG. 14, in which "H" or "L" changes randomly. It can also be generated using a random (RND) function, such as a microcomputer.

Further, in the random signal generating circuit 106, as shown in FIG. 18, the + input of the operational amplifier (OP amplifier) 155 is connected to the reference voltage, and between the − input and the output,
A high resistor 156 is connected and an OP amplifier 155 is connected.
It is also possible to adopt a configuration in which the output of is connected to the NOT circuit 159 via the capacitor 157. That is, the high resistor 1
Since 56 generates white noise (random noise), it is amplified by the OP amplifier 155 and the capacitor 1
The generation of the random signal may be realized by inputting to the NOT circuit 159 via 57. Note that one of the resistors 158 is connected to the reference voltage.

Referring to FIGS. 14 and 15, the one-shot circuit 102 generates a one-shot pulse signal at the falling edge of the signal B, and further outputs an OR signal C of the pulse signal and the pulse signal A. This signal C is supplied to the heat pulse generation circuit 104.

Referring to FIG. 19, one-shot circuit 102
Will be described in detail. FIG. 7A is a circuit diagram thereof, and FIG. 7B is an operation timing chart. 117 and 1 in the figure
Reference numeral 18 denotes a DFF, which latches the input information to the D terminal at the rising timing of the clock (CK) and holds it at the Q output terminal. At that time, an inverted signal of Q is output to the / Q terminal. Further, when the RESET signal is input to the R input terminals of the DFFs 117 and 118 and a signal of "H" level is input thereto, Q = "L" and / Q = "H".

The signal PUC is a signal which becomes the "H" level for a moment only when the power supply circuit (not shown) is turned on and the power supply circuit is unstable at the time of rising, and becomes the "L" level when the power supply circuit becomes stable.
This signal PUC is supplied to the R input terminals of the DFFs 117 and 118.
Of Q = “L” and / Q = “H” of DFF 118.

The clocks (C
K) 1 MHz square wave is input to the input terminal. Since the encoder signal is input to the D input of the DFF 117, the Q output of the DFF 117 is an encoder signal whose output changes in synchronization with the 1 MHz clock signal. Since the Q output of DFF 117 is connected to the D input of DFF 108, the output of DFF 118 is D
It changes with a delay of one clock from the Q output of the FF 117. In this case, the delay of 1 clock is 1 μs because the clock signal of 1 MHz is used.
An AND gate 119 outputs a signal C1 obtained by ANDing the Q output of the DFF 117 and the / Q output of the DFF 108. An OR gate 120 outputs a signal C obtained by ORing the signal C1 and the signal A. With the above configuration, the one-shot circuit 102 operates as the block reference signal B.
Signal C1 which becomes "H" only for 1 µs only at the falling edge of
And "H" only for 1μs only when the encoder starts up
The OR signal C with the signal A becomes The signal C is a timing signal for starting the energization of the discharge heater,
The one-shot interval of the signal C is the block interval.

Referring to FIGS. 14 and 15, shift circuit 103 outputs pulse signal QA1 at the timing of signal B.
~ QA4 is output and input to the heat pulse generation circuit 104.

The details of the shift circuit 103 will be described with reference to FIG. FIG. 7A is a circuit diagram thereof, and FIG. 7B is an operation timing chart. In the figure, 122 to 125 are DF
It is F. The D input terminal of the DFF122 is pulled up to "H", the Q output of the DFF122 is connected to the D input of the DFF123, the Q output of the DFF123 is connected to the D input of the DFF124, and the Q output of the DFF124 is connected to the D input of the DFF125. It has a structure like a so-called shift register.

An OR gate 129 ORs the signal PUC, which is a reset signal, and the signal A output from the one-shot circuit 100 until the power supply circuit is turned on and becomes stable. This signal is the DFF12
Since it is connected to the reset input of 2-125, DF
The F122 to F125 are reset at the time of turning on the power and the timing of the signal A (every time the encoder rises).
The Q output of F122-125 becomes "L" level.

A is input to the CK input of the DFFs 122 to 125.
From the ND gate 121, a signal obtained by ANDing the inverted signal of the signal B output from the circuit 101 and the / Q signal of the DFF 125 is input. When the encoder signal rises, the circuit 100 outputs the one-shot signal A and the DFF12
2-125 are reset. At this time / Q4 = "H"
Therefore, the inverted signal of the signal B is the DFF 122 to 125.
Input to the CK terminal of. Q1 = "H" at the first falling of the signal B, and Q2 = at the second falling.
"H", Q3 = "H" at the third fall. When Q4 = “H” at the fourth fall, the inverted signal / Q4 (“L” level) is input to the AND gate 121, so that the clock CK of the DFFs 122 to 125 is stopped and each DFF respectively. Hold the output of.

Reference numerals 126 to 128 denote AND gates, which are D
An AND of the Q1 output of the FF122 and the inverted output Q2 of the DFF123, an AND of the Q1 output of the DFF123 and the inverted output Q2 of the DFF124, and an AND of the Q1 output of the DFF123 and the inverted output Q2 of the DFF124 are calculated to obtain the signal QA2. , QA3 and QA4 are output.
These signals QA2, QA3 and QA4 are reset at the rising edge of the encoder signal, and DFF1
Only the signal QA1 equal to the Q1 output of 22 becomes "H".
Then, every time the signal B falls, the "H" level becomes QA.
2, QA3, QA4 shifts. These signals QA
1 to QA4 are signals indicating block intervals.

With reference to FIGS. 14 and 15, the heat pulse generation circuit 104 generates a signal for energizing the discharge heater and outputs it to the driver circuit 105. Here, the information on the energization time to the ejection heater for ejecting ink is
It is supplied by a microcomputer or the like which is a control unit of a printing apparatus (not shown), and the information thereof defines the energization time (heat pulse width) to the ejection heater. As shown in FIG. 15, the heat pulse generation circuit 104 outputs the block drive signal BL1 for the time defined by the above information at the rising timing of the pulse signal QA1 and supplies it to the driver circuit 105. Similarly, the heat pulse generation circuit 104 outputs the block drive signal BL for a time defined by the above information at each rising timing of the pulse signals QA2, QA3, and QA4.
2, BL3 and BL4 are output and the driver circuit 105
Supply to.

Referring to FIG. 21, heat pulse generation circuit 1
Details of 04 will be described. The circuit diagram of FIG.
(B) is an operation timing chart. 131 in the figure
Is a counter, counting 1MHz square wave,
A signal that counts up in binary number every 1 μs is output via the output terminals QQ1, QQ2, QQ3, QQ4.

Reference numeral 130 is a 4-bit matching circuit, which has 4-bit inputs A1, A2, A3 and A4 connected to QQ1, QQ2, QQ3 and QQ4 respectively, and B1 and B.
2, B3, B4 are compared with 4-bit input, and if the A-sequence signal and the B-sequence signal are equal in 4 bits, O
UT = “H”, otherwise outputs “L”. That is, 4-bit parallel pulse width information signals B1, B2, B
3, B4 and signal QQ which is incremented every 1 μs
1, QQ2, QQ3, QQ4 are compared, and when they match, OUT = “H”.

Reference numeral 132 denotes a set / reset type flip-flop (hereinafter abbreviated as SRFF). SRFF1
32 is Q when S input = “H” and R input = “L”
E output = “H”, S input = “L” and R input = “H”
When QE output = “L”, S input = “L”, and R input = “L”, QE output = hold (invariant). In addition,
S input = “H” and R input = “H” are prohibited.

The signal C is supplied to the reset input of the counter 131 and the set (S) input of the SRFF 132. Counter 13 at one-shot timing of signal C
1 is reset and QE of SRFF becomes “H”. Since the OUT of the counter 131 and the R input of the SRFF 132 are connected, the signal B of the ejection heater pulse width data
After the time indicated by 1 to B4, QE = "L".

The signals QA1 to QA4 are the block signals described above. 133 to 136 are AND gates, which take the AND of the signals QA1 to QA4 and the signal QE to obtain BL.
Output signals 1 to BL4. These signals BL1 to BL4 are
This is a signal of the discharge heater energization timing of each block.

With reference to FIGS. 14 and 15, the driver circuit 105 supplies a drive signal to the ejection heater corresponding to the nozzle for ejecting ink according to the image information.
A signal supplied to the driver circuit 105 according to the image information (a signal for defining the presence / absence of ejection of each nozzle according to the image information) is a signal indicated by G1 to G12, which is input from a control unit (not shown). That is, the driver circuit 105 generates drive signals for the ejection heaters permitted by the signals G1 to G12 at the timings of the block drive signals BL1 to BL4.

FIG. 22 shows a detailed configuration example of the driver circuit 105. In the figure, 137 is an AND gate,
The signal BL1 and the signal G1 are ANDed and the output is N
It is connected to the gate of the channel type MOS FET 139. Reference numeral 138 denotes an ejection heater, one end of which is connected to the ejection heater power source and the other end of which is connected to the drain of the MOS FET 139. The source of the MOS FET 139 is connected to the power supply GND. MOS FET139
Is a switching element of the discharge heater 138. When the gate of the discharge heater 138 is "L", the drain-source resistance is high (several GΩ or more), but the gate is "H".
Then, the drain-source resistance becomes low (several Ω or less), and a current flows from the discharge heater power source to the GND through the discharge heater 139, the drain and the source, and the discharge heater generates heat. Then, ink is ejected by utilizing the bubbling phenomenon that accompanies this.

Although an N channel type MOS FET is used as the switching element of the discharge heater in the illustrated example, other elements such as an NPN type transistor and an IG are also used.
You may comprise using BT, SIT (electrostatic effect transistor) etc. In addition, a switching element, GN on the power supply side
If a discharge heater is connected to the D side, a P channel type MOSFET or a PNP type transistor may be used.

Further, in the figure, one discharge heater (nozzle 1
Corresponding to the number of nozzles) is shown. However, similar driver circuits are provided corresponding to the number of nozzles. That is, the block drive signals BL1, BL
2, BL3, BL4 and image signals G1, G2, respectively
Nozzles 1, 2, and
The energization control of the discharge heaters 3 and 4 is performed. Further, the AND output of the block drive signals BL1, BL2, BL3, BL4 and the image signals G5, G6, G7, G8 respectively controls the energization of the discharge heaters of the nozzles 5, 6, 7, 8. Further, the block drive signals BL1, B
L2, BL3, BL4 and image signals G9, G1 respectively
The AND output of 0, G11, and G12 controls the energization of the discharge heaters of the nozzles 9, 10, 11, and 12, respectively.

At this time, in this example, the block drive signals BL1, BL2, BL3, BL4 are set so that the intervals between the blocks are different, so that the frequency components of the pressure wave in the liquid chamber are dispersed and the resonance of the meniscus surface is caused. Does not occur,
Meniscus vibration is prevented. In particular, since the block interval is randomly changed, it is easier to prevent meniscus resonance.

The driver circuit may be integrally formed on the substrate on which the ejection heater of the ink jet head is formed. However, the predetermined circuits shown in FIG. 14 may be appropriately formed on the substrate or the ink jet head. May be integrally provided in the.

(Second Example of Embodiment) A second example of driving an ink jet head according to an embodiment of the present invention will be described with reference to FIGS.

FIG. 23A is a diagram for explaining the correspondence between the nozzles arranged in the ink jet head and the signal waveform applied to the discharge heater provided for each nozzle. Similar to the above example, the inkjet head 1000 is shown as having 12 nozzles for the sake of simplicity, and from the top of the drawing, nozzle 1, nozzle 2,
... The nozzles 11 and 12 are arranged.

In the drawing, the timing chart shown on the right side of the ink jet head 1000 shows the waveform of the signal supplied to the discharge heater of each nozzle in association with each nozzle. The vertical axis represents the applied voltage, and at the “H” level, the discharge heater is energized (ON), and ink is discharged by foaming accompanying heat generation. The "L" level is a non-energized (OFF) state, and ink is not ejected. The horizontal axis is the time axis.

Similarly to the above example, 12 nozzles are grouped into 3 groups of 3 nozzles and divided into 4 groups (blocks), and the nozzles 1, 5 and 9 are arranged at the timing of the first block.
The nozzles 2, 6 and 10 are driven in time division at the timing of the second block, the nozzles 3, 7 and 11 are driven at the timing of the third block, and the nozzles 4, 8 and 12 are driven in the time division at the timing of the fourth block. The ejection openings of the first to fourth blocks sequentially perform ejection operations.

As shown in FIG. 23A, in this example, the block intervals "1", block intervals "2", block intervals "3", and block intervals "4" are made uniform in length. is there. That is, the block intervals are made uniform. In the above-mentioned first example, the block drive start time in the ejection cycle is made constant while the block intervals are made non-uniform. However, in the present example, the block drive start time in the drive cycle is set for each ejection cycle. It is configured to be variable. Particularly, in the embodiment, this starting time point is randomly changed.

FIG. 23B is a diagram showing a pressure change in the liquid chamber of the ink jet head caused by the driving of the discharge heater or the discharge operation of the nozzle as described above, in which the vertical axis represents pressure and the horizontal axis represents time axis. is there. The broken line shown along the time axis is the pressure equal to the external atmospheric pressure (1 atm), the part above this broken line shows high liquid chamber pressure, and the lower part shows low liquid chamber pressure. There is. In this example, FIG.
As shown in (A), since the block drive start timing is random, the frequency components of the liquid chamber pressure wave are dispersed.

FIG. 23C is a diagram for explaining the side cross section of the ink jet head in this example and the state of meniscus vibration generated at the ejection port of each nozzle, and the vertical axis indicates the ejection port of each nozzle. The state of the surface (meniscus surface) where ink and air are in contact is shown. Also, it is a normal state when there is a meniscus surface at the position of the broken line drawn corresponding to each ejection port, and as the position goes upward from this state, the meniscus surface protrudes outwardly of the ejection port, On the contrary, as it goes downward, the meniscus surface is recessed inward of the discharge port.

In this example, the frequency component of the pressure wave in the liquid chamber is dispersed by randomizing the interval from the start time of the discharge cycle to the start time of the block drive, and the meniscus vibration is eliminated by eliminating the resonance of the meniscus surface. Virtually no occurrence.

In order to perform such driving, basically the same circuit configuration as that of the first example shown in FIG. 14 can be used, but in the case of this example, the one-shot circuit 1 is used.
00 and the block drive reference signal generation circuit 101 are different from the first example.

FIG. 24A is a diagram showing a circuit configuration example of the one-shot circuit according to this example, and FIG. 24B is an operation timing chart. In the figure, 148, 152 and 153 are DFFs.
Is. Q0 is a signal R supplied from the same random signal generation circuit as described above every time the encoder signal falls.
This is a signal obtained by latching ND with the DFF 148.

AND gate 149 and AND gate 150
The selection circuit is composed of (NOT input to only one) and the OR gate 151. For example, a 100 kHz square wave signal and a 1 MHz square wave signal are selectively output by the signal Q0. That is, the selection signal Q0 causes the OR gate 151 to output the clock signal CK of 100 kHz or 1 MHz.

The DFFs 152 and 153 and the AND gate 154 form a one-shot circuit, and the one-shot pulse having the width of the clock signal CK is output from the AND gate 154 every time the encoder signal rises. Since the signal PUC is connected to the DFFs 152 and 153, Q = “L”, D of the DFF 152 immediately after the power is turned on.
/ Q of the FF 153 becomes "H".

The clock signal CK is input to the clock input terminals of the DFFs 152 and 153. DFF15
Since the encoder signal is input to the D input of 3,
An encoder signal is output from the Q terminal of the DFF 152 in synchronization with the clock signal CK. Q of this DFF152
The output is connected to the D input of the DFF 153. DFF
The Q output of 153 changes with a delay of one clock from the Q output of the DFF 152. In this case, the delay of 1 clock is
Since the signal of 1 MHz and the signal of 100 kHz change randomly, it becomes 1 μs or 10 μs.

The AND gate 154 is connected to the Q of the DFF 152.
A signal A obtained by ANDing the output and the / Q output of the DFF 153 is output. That is, the one-shot circuit 10 of this example
0 is 1 only at the rising edge of the encoder signal at random
The signal A which is at the “H” level only for μs or 10 μs is output. The block drive reference signal generation circuit 101 may have the same configuration as the timer circuit in FIG.

As described above, as shown in FIG.
By setting the drive block of the discharge heater to start with a delay of 1 μs or 10 μs with respect to the rising edge of the encoder signal, the discharge frequency is slightly deviated, and resonance of the meniscus surface can be suppressed. That is, in this example, by randomly setting the timing of the start block of the block in each discharge cycle so as not to be uniform, the frequency component of the pressure wave in the liquid chamber is dispersed, resonance of the meniscus surface is suppressed, and meniscus vibration is prevented. is doing.

Needless to say, the above delay time or its type can be appropriately determined. Further, in the above embodiments, the block interval and the example in which the start timing of the block drive within the ejection cycle is randomly changed have been described, but if the drive is performed at different intervals or different start timings even if not random. Good. However, it is preferable to change it at random because the periodicity can be eliminated further.

(Others) In the above description, the electrothermal conversion element (ejection heater) is provided inside the ejection port, and the expansion force of the bubbles generated by the action of heat generated by the energization is used as the driving force for ink ejection. The case where the present invention is applied to (for example, a bubble jet (registered trademark) method proposed by Canon Inc. for ejecting ink by causing film boiling in the ink) has been described. However, if the amount of ejected ink or the ejecting direction can be varied due to the meniscus vibration, an ink jet head of an ink jet method of another method (for example, a piezoelectric element is used as a recording element that generates energy used for ink ejection) Needless to say, it can be effectively applied to an inkjet printing apparatus.

[0106]

As described above, according to the present invention,
The ink jet head is driven so that the frequency of the pressure fluctuation in the liquid chamber due to the ink ejection operation is different from each nozzle resonance frequency in the ink jet head, and the meniscus surface is prevented from resonating with the pressure wave in the liquid chamber, thereby causing the meniscus vibration. Suppressed.

That is, according to the present invention, when a plurality of recording elements are divided into a plurality of blocks for driving, the driving intervals of the blocks are set so as not to be uniform. Alternatively, a plurality of recording elements may be divided into a plurality of blocks, and
To carry out the driving in the discharge period, the period of the drive start timing of the first of the block in the discharge period so as not uniform in the discharge circumferential period (i.e., from the start of the discharge cycle until the first discharge is started Is set to be different between driving cycles). By preventing resonance of the meniscus surface by these, it is possible to reduce meniscus vibration, so that it is possible to obtain a stable ink ejection state and perform high-quality printing without spots or streaks.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a problem caused by a conventional time-divisional drive of a plurality of nozzles, and FIG. 1A illustrates a correspondence with a signal waveform applied to an ejection heater provided for each nozzle. FIG. 6B is a diagram for illustrating the pressure change in the liquid chamber of the inkjet head caused by the driving of the discharge heater or the discharge operation of the nozzles, and FIG. 7C is a state of the meniscus vibration generated at the discharge ports of the nozzles. FIG.

FIG. 2 is a block diagram showing a conventional example of a drive circuit for performing time-division drive of a plurality of nozzles.

FIG. 3 is an operation timing chart of each part in the drive circuit of FIG.

4A and 4B are a circuit diagram and an operation timing chart showing the configuration of the timer circuit in FIG. 2, respectively.

FIG. 5 is a schematic perspective view of an inkjet printing apparatus to which the present invention can be applied.

6 is a perspective view showing a configuration example of an inkjet head applicable to the apparatus of FIG.

FIG. 7 is a perspective view of the inkjet head of FIG.

8 is a cross-sectional view showing the inkjet head of FIG. 6 cut at a right angle to the direction in which nozzles are arranged.

9 is a cross-sectional view showing the inkjet head of FIG. 6 cut in the direction in which nozzles are arranged.

10 is a view showing the inkjet head of FIG. 6 cut along a plane parallel to the recording paper P, and is a cross-sectional view of a portion D in FIG.

11 is a view showing the inkjet head of FIG. 6 cut along a plane parallel to the recording paper P, and a sectional view of a portion E in FIG.

12 is a view showing the inkjet head of FIG. 6 cut along a plane parallel to the recording paper P, and a sectional view of a portion F in FIG.

FIG. 13 is a diagram for explaining a first example of driving an inkjet head according to the embodiment of the present invention, in which (A) corresponds to a signal waveform applied to an ejection heater provided for each nozzle. FIG. 6B is a diagram for explaining, FIG. 6B is a diagram showing a pressure change in the liquid chamber of the inkjet head caused by driving of a discharge heater or discharge operation of nozzles, and FIG. FIG.

FIG. 14 is a block diagram showing a configuration example of a drive circuit for performing time-division drive of the inkjet head according to the embodiment of the present invention.

15 is a timing chart of signals at various parts in the drive circuit of FIG.

16A and 16B are respectively a circuit diagram showing a configuration example of the one-shot circuit in FIG. 14 and a timing chart of signals at respective parts thereof.

17 (A) is a circuit diagram showing a configuration example of the block drive reference signal generation circuit in FIG. 14, (B) and (C).
Is a timing chart of signals of respective parts.

FIG. 18 is a circuit diagram showing an example of a random signal generation circuit applicable to the circuits of FIGS. 14 to 17A.

19A and 19B are respectively a circuit diagram showing a configuration example of the one-shot circuit in FIG. 14 and a timing chart of signals at respective parts thereof.

20A and 20B are a circuit diagram showing a configuration example of the shift circuit in FIG. 14 and a timing chart of signals at respective parts thereof.

21A and 21B are respectively a circuit diagram showing a configuration example of the heat pulse generation circuit in FIG. 14 and a timing chart of signals at respective parts thereof.

22 is a circuit diagram showing a configuration example of a driver circuit in FIG.

FIG. 23 is a diagram for explaining a second example of driving the inkjet head according to the embodiment of the present invention, in which (A) corresponds to the signal waveform applied to the ejection heater provided for each nozzle. FIG. 6B is a diagram for explaining, FIG. 9B is a diagram showing a pressure change in the liquid chamber of the inkjet head caused by driving of a discharge heater or a discharge operation of a nozzle, and FIG. FIG.

24A and 24B are respectively a circuit diagram showing a configuration example of a one-shot circuit applicable to the example of the driving method of FIG. 23, and a timing chart of signals at respective parts thereof.

FIG. 25 is a timing chart of signals of respective parts of the second embodiment.

[Explanation of symbols]

1-12 Nozzle 100 One-shot circuit 101 Block drive reference signal generation circuit 102 One-shot circuit 103 Shift circuit 104 Heat pulse generation circuit 105 Driver circuit 106 Random signal generation circuit 107, 108, 117, 118, 122-125, 1
48, 152, 153D type flip-flop (DFF) 109, 119, 121, 126-128, 133-1
36, 137, 149, 150, 1114 AND gates 110-113 T-type flip-flop (TFF) 114 Timer circuit 120, 129, 151, 1115 OR gate 130 Matching circuit 131 Counter 138 Discharge heater 139 MOS FET 200 Carriage 206 Linear encoder 1000 Inkjet head 1001 Liquid chamber 1003 Discharge port 1004 Retained bubbles

Continuation of front page (56) Reference JP 2001-246738 (JP, A) JP 11-240158 (JP, A) JP 6-198906 (JP, A) JP 5-185606 (JP, A) JP-A-9-216350 (JP, A) JP-A-7-60967 (JP, A) JP-A-5-84898 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) ) B41J 2/01 B41J 2/045 B41J 2/05 B41J 2/055

Claims (8)

(57) [Claims] 1. An inkjet recording apparatus for performing recording using an inkjet head having a plurality of ejection openings for ejecting ink and a liquid chamber for supplying ink to the plurality of ejection openings, wherein the plurality of ejection openings are provided. A plurality of recording elements used for ejecting ink from a plurality of blocks to drive by dividing into a plurality of blocks, and a drive interval of each block divided by the block dividing means
Means for generating a block signal for designating the block signal, and the block signal and the image signal generated by the block dividing means.
And means for time-divisionally driving each recording element based on
And the drive interval of each block is output by the block signal.
Non-uniform within the discharge cycle and non-uniform during each discharge cycle
An ink jet recording apparatus comprising: a control unit for performing control so as to: 2. An inkjet recording apparatus for performing recording using an inkjet head having a plurality of ejection openings for ejecting ink and a liquid chamber for supplying ink to the plurality of ejection openings, wherein the plurality of ejection openings are provided. A plurality of recording elements used for ejecting ink from the
Between the block dividing means that drives within the ejection cycle and the drive of each block divided by the block dividing means
Means for generating a block signal for specifying the distance, and the block signal and the image signal generated by the block dividing means.
And means for time-divisionally driving each recording element based on
And the drive interval of each block is discharged by the block signal
While the uniform period, controlled to randomly drive start timing of the first of the blocks in the block signal by <br/> the discharge cycle for each of the ejection cycle
An inkjet recording apparatus comprising: a control unit for performing the above . 3. The ink jet recording apparatus according to claim 1, wherein the ink jet head has a heating element as the recording element for applying heat energy for causing film boiling of the ink. 4. The ink jet head has a piezoelectric element as the recording element.
Alternatively, the inkjet recording device described in 2. 5. A method for driving an ink jet head having a plurality of ejection ports for ejecting ink and a liquid chamber communicating with the plurality of ejection ports, which is used for ejecting ink from the plurality of ejection ports.
Each recording element is divided into multiple blocks.
Block signal to set the drive period for each clock
And a block signal generating step, and based on the block signal and the image signal, each recording element
The step of driving the child in a time-division manner, and the drive interval of each block is discharged by the block signal.
Non-uniform within the discharge cycle and non-uniform within each discharge cycle
A method for driving an inkjet head, comprising: 6. A method for driving an ink jet head having a plurality of ejection ports for ejecting ink and a liquid chamber communicating with the plurality of ejection ports, which is used for ejecting ink from the plurality of ejection ports. Divide multiple recording elements into multiple blocks
Between the block dividing step of driving within the ejection cycle and the driving of each block divided by the block dividing means.
Generating a block signal for designating an interval, and each recording element based on the block signal and the image signal.
The step of driving the child in a time division manner, and the driving interval of each block is discharged by the block signal.
While the uniform period, controlled to randomly drive start timing of the first of the blocks in the block signal by <br/> the discharge cycle for each of the ejection cycle
A method of driving an inkjet head, comprising: Wherein said ink jet head, an ink jet according to 6 claim 5 or <br/> other, characterized in that it comprises a heating element that gives heat energy to cause film boiling in the ink as the recording element How to drive the head. Wherein said ink-jet head, according to claim 5, characterized in that it comprises a piezoelectric element as said recording element
Alternatively, the method of driving the inkjet head according to Item 6 .