JPH09314860A - INKJET RECORDING APPARATUS AND INKJET HEAD REMOVED METHOD - Google Patents

Abstract

(57) Abstract: In an inkjet head of a type that ejects ink while allowing bubbles generated for ejecting ink to communicate with outside air through ejection ports, conditions for forming bubbles in a state where they do not communicate with outside air. Even if the number fluctuates due to the head, the bubbles are always stably formed, and the foreign matter on the heater is removed by cavitation when the bubbles disappear. SOLUTION: Ink ejection and output detection by an acoustic sensor at that time are previously detected within a pulse width range A of an ejection signal applied to a heater, which is a driving condition formed in a state where bubbles do not communicate with outside air. And determine the optimum pulse width.

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 more particularly to an ink jet recording apparatus capable of removing foreign matters accumulated on an electrothermal conversion element (heater) that generates thermal energy used for ink ejection. It is a thing.

[0002]

2. Description of the Related Art An ink jet recording apparatus ejects ink as minute liquid droplets from an ejection port to record characters, figures and the like, and has an excellent advantage as a means for high-definition image output and high-speed recording. Have In particular, a method using the pressure of a bubble generated by using heat energy generated by an electrothermal conversion element (hereinafter also referred to as a heater), a so-called thermal ink jet recording method (for example, Japanese Patent Publication No. 61-
The method disclosed in Japanese Patent No. 59911-4) has advantages such as downsizing of the device and easy image densification.

Further, before the ejected ink drop leaves the ejection port, an ink jet recording method in which bubbles for ejection are made to communicate with the outside air in the vicinity of the ejection port and ejected (eg Japanese Patent Application No. 2-
Nos. 112832 to 4)), ink droplets can be made smaller and splashes and mists are less likely to occur, and unlike the thermal inkjet recording method described above, the ejection amount can be improved even if the temperature of the inkjet head itself changes. The feature is that stable ejection can be performed.

FIG. 15 is an exploded perspective view showing an example of an ink jet head to which the above-mentioned bubble communication ejection method can be applied.

As shown in FIG. 15, on the substrate 101,
A predetermined number of heaters 102 and electrode wirings (not shown) for sending electric signals to the heaters 102 are formed, and ink passages 103 that can include these heaters 102 are formed at predetermined intervals and these ink passages 103 are formed. A plurality of partition walls 105 for forming a common liquid chamber 104 communicating with each of the
Is provided. Then, the ink jet head is formed by joining the top plate 107 having the ink supply port 106 formed on the partition walls 105. That is, the partition walls 105, the substrate 101, and the top plate 107 form each ink passage 103 and an ejection port as an opening at an end thereof, and ink is supplied to each of these ink passages from a common liquid chamber 104 that is also formed. It Further, when an ejection signal is applied to the heater 102 via the electrode wiring, bubbles are generated on the heater 102, and the pressure thereof ejects an ink droplet from the ejection port.

FIG. 16 is an exploded perspective view showing another example of an ink jet head to which the valve communication discharge method can be applied.

The structure shown in FIG. 16 is a part of an ink jet head for one ejection port, and the head is composed of a plurality of such constituent units. In the figure,
On the substrate 111, a predetermined number of heaters 112 and electrode wirings (not shown) for sending electric signals to the heaters 112.
And the partition walls 114 for forming the ink paths 113 at predetermined intervals are provided on the heaters 112. Then, the ink jet head is configured by joining the top plate 116 having the ink ejection ports 117 formed on the partition wall 114. That is, the partition 114 and the substrate 111
A portion surrounded by the top plate 116 serves as an ink path 113, and an ejection signal is applied to the heater 112 via the electrode wiring to generate bubbles on the heater 112, whereby droplets are ejected from the ejection port 115.

In the ink jet head shown above, a predetermined ejection signal is applied to the heater to form a bubble on the heater, and while the bubble is communicated with the outside air through the ejection port, droplets are ejected from the ejection port. Can be discharged.

By the way, in the case of an ink jet head of the type which generally ejects ink using a heater, depending on the composition of the ink used and the driving conditions of the ink jet head, when the ink jet head is used for a long period of time or the number of ejections increases. In some cases, for example, deposits or deposits of kogated dyes in ink are deposited on the heater. In such a case, the growth of the bubble is hindered and the pressure is reduced, the discharge amount is reduced or the discharge amount varies among the discharge ports, and as a result, the density of the image is reduced and the density unevenness occurs. The image quality may be degraded due to.

In the bubble communication method, as a method for coping with the above-mentioned kogation etc., during non-recording, the driving conditions for applying a predetermined ejection signal to the heater are changed so that the bubbles are not communicated to the outside air through the ejection port. For example, Japanese Patent Laid-Open No. 7-17040 proposes a method of forming and removing the kogation deposits and precipitates on the heater by cavitation generated when the bubbles disappear.

[0011]

However, this method may have the following problems.

Since the ink jet head of the bubble communication type is designed so that ink is ejected under the condition that the bubbles communicate with the outside air through the ejection ports, the bubbles are ejected without communicating with the outside air through the ejection ports. The driving condition margin for performing is relatively small.

On the other hand, the growth of bubbles generated by applying an ejection signal to the heater is caused by variations in the thickness and shape of the heater, the dimensions of the ejection port, the ink path and the like and the power supply voltage.
The bubble growth characteristics vary depending on the individual differences of the recording device and the head, and even with the same recording device and the same head, the bubble growth characteristics vary depending on the condition of the surface of the heater, the condition of the head, the ink density, and the like.

Along with this, the driving conditions of the ink jet head, in which the bubbles are ejected in a state where they do not communicate with the outside air through the ejection ports, vary. When the variation due to the individual difference of the recording device or the inkjet head is large and the margin of the setting of the driving condition is small as described above, the individual difference of the recording device or the inkjet head is ignored and a predetermined value is set. Under such driving conditions, it may be difficult to perform driving in a state in which bubbles do not communicate with the outside air via the ejection ports.

The present invention has been made to solve such a problem, and an object of the present invention is to generate a bubble when a bubble is formed in a bubble communicating type ink jet head without communicating with the outside air. An object of the present invention is to provide an ink jet recording apparatus that can satisfactorily remove kogation deposits and deposits on a heater by generating a constant amount of cavitation regardless of variations in the state.

[0016]

Therefore, according to the present invention,
An ink jet recording apparatus for performing recording using an ink jet head for forming air bubbles, communicating the air bubbles with the outside air through an ejection port, and ejecting ink from the ejection port. Non-communicating drive means for forming a state of not communicating with outside air through the outlet, head characteristic detecting means for detecting characteristics of the inkjet head associated with driving of the non-communicating drive means, and information obtained by at least the head characteristic detecting means Drive condition setting means for determining the drive condition of the non-communication drive means based on the above.

A method for removing foreign matter from an ink jet head in an ink jet recording apparatus, wherein recording is performed by using an ink jet head that forms bubbles, communicates the bubbles with the outside air through an ejection port, and ejects ink from the ejection port. There, the inkjet head is driven by a non-communicating drive means that forms a bubble and forms a state in which the bubble does not communicate with the outside air through the ejection port, and detects the characteristic of the inkjet head from the result of the drive,
A drive condition of the non-communication drive unit is determined based on the detection, and the non-communication drive unit drives the inkjet head under the determined drive condition to remove foreign matter adhering to the ejection heater of the inkjet head. It is characterized by having each step of removing.

According to the above construction, the non-communication driving means drives the ink jet head in advance, detects the characteristic relating to the non-communication driving of the head at this time, and based on the detection result, the non-communication driving condition of the head. Therefore, the head can be driven under a non-communication drive condition suitable for the characteristics of the head.

[0019]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

<First Embodiment> In this embodiment, the recording head is driven while changing the pulse width of the ejection signal applied to the heater, and whether or not cavitation occurs during the driving is provided on the carriage. Drive condition used to remove the burnt deposits and deposits on the heater by detecting the pulse width range of the discharge signal that occurs when the bubble does not communicate with the atmosphere using the data To decide.

FIG. 1 is a perspective view showing the structure of an ink jet recording apparatus used in this embodiment.

The ink jet head 11 is the carriage 1.
When the ejection recovery operation of the inkjet head 11 mounted on the No. 2 is carried out, the carriage 12 is moved to the suction device 14 provided outside the recording range 13 shown by the arrow in the drawing, and the ejection recovery operation such as the suction process is performed. The suction device 14 has a cap and can cover the ejection port surface of the inkjet head 11 at the time of non-recording. Furthermore, if the recording head is left for a long time without being ejected, the volatile components in the ink may evaporate, which may increase the viscosity or increase the density of the ink near the ejection port. For the purpose of removing such thickened ink, ink droplets are ejected from the recording head at a predetermined number and at a predetermined timing toward an ink receiver (not shown) provided near the suction device 14. To do
So-called preliminary ejection is performed. Further, an acoustic sensor (not shown) is provided on the carriage 12 near the ink ejection portion.

The ink jet head 11 is the same as the ink jet of the bubble communication ejection system shown in FIG. 15, and its description is omitted here. A temperature sensor (not shown) is formed on the substrate 101 of the inkjet head 11 in the same process as the heater and the like, and the output of the temperature sensor can monitor the temperature of the recording head.

The drive of the recording head in this embodiment is
A single driving pulse is used to facilitate high-speed driving. This is driven by a plurality of drive pulses, the ink in the vicinity of the ejection heater is heated by the preceding pulse, and when a bubble is generated and ejected by the subsequent pulse, it is driven by a single pulse. It is possible to generate a relatively large bubble with less energy input compared to the case of operating the recording head, but if the drive of the recording head is attempted at high speed, the time allotted to drive the individual heaters will be shortened by that much. This is because driving at is disadvantageous.
However, since it is relatively difficult to grow bubbles when driven by a single pulse, it is necessary to increase the heater size or the like in order to generate bubbles of the same size as when a plurality of drive pulses are used.

A state in which ink is ejected from the recording head when the ink jet head 11 is driven under the condition that bubbles communicate with the outside air from the ejection port will be described with reference to FIG. In FIG. 2, reference numeral 121 denotes ink in the ink path 103, 123 is an ejection port that is an opening at an end of the ink path 103, 125 is a surface on which the ejection port of the inkjet head is provided (ejection port surface), and 126 is ink. The meniscus 127 formed by is a bubble formed in the ink when the head is driven.

FIG. 2A shows a state before bubbling, and the meniscus 126 of the ink 121 forms a surface substantially continuous with the ejection port surface 125. Here, when the ink 121 in the vicinity of the heater 102 is heated by instantaneously applying the ejection signal to the heater 102, a bubble 127 is generated and the expansion starts (FIG. 2B). The bubble 127 continues to expand and communicates with the outside air via the discharge port 123 (FIG. 2).
(C)). At this time, the ink 128 on the ejection port 123 side of the bubble 127 is pushed forward due to the momentum given by the bubble 127 up to this time (FIG. 2C). Then, the ink 128 is transferred to the ink path 103.
It separates from the ink inside and becomes independent droplets 129 that fly to a recording medium such as paper. That is, ink is ejected (FIG. 2 (d)). At this time, the meniscus 126 is in a state of retracting inward from the ejection port 123, and a void is formed in front of it (FIG. 2 (e)). But this void is
The meniscus 126 advances due to the surface tension of the ink 121 with respect to the ink path or the like and the wettability of the inner wall of the ink path 103 with which the ink is in contact, the ink is filled, and the state before ejection is returned (FIG. 2 (f)).

Next, with reference to FIG. 3, a state of ink ejection when the ink jet head shown in FIG. 2 is driven under the condition that bubbles do not communicate with the outside air through the ejection ports will be described with reference to FIG. In FIG. 3, meniscus bubbles, ink droplets, and the like that behave differently from those shown in FIG. 2 are indicated by reference numerals different from those in FIG.

FIG. 3A shows a state before bubbling. As in the case shown in FIG. 2, the meniscus 136 of the ink 121 is formed almost continuously with the ejection port surface 125. Here, the ink 12 in the vicinity of the heater 102 is applied to the heater 102 by applying an ejection signal having a pulse width that is sufficient for bubbling the ink and does not allow the bubble to communicate with the atmosphere.
When 1 is heated, bubbles 137 are generated and expansion starts (FIG. 3 (b)). Since the pulse width of the ejection signal to be applied is shorter than that in the case of FIG.
7 does not expand until it communicates with the atmosphere (Fig. 3
(C)). Then, due to this expansion, the ink 138 protruding from the ejection port 123 eventually becomes an independent droplet 139 and flies to a recording medium such as paper (FIG. 3D). After that, the bubble 137 shrinks, and cavitation occurs when it disappears (FIG. 3E). At this time, the meniscus 136 is drawn inward from the ejection port 123, thereby forming a gap in front of the ink path 103 (FIG. 3E). However, due to the surface tension of the ink 121 and the wettability of the inner wall of the ink path 103 in contact with the ink, the meniscus 136 advances into this void and is filled with new ink to return to the state before ejection (FIG. 3 (f)). ).

FIG. 4 is a diagram showing the relationship between the pulse width of the signal (ejection signal) for driving the ink jet head of this embodiment and the ink ejection speed at that time.

The horizontal axis of the figure represents the pulse width of the ejection signal, and the vertical axis represents the initial velocity of the ejected ink droplet. The range indicated by A in the figure is the range of the pulse width in which bubbles are generated by the application of the ejection signal in the state where the bubbles are not in communication with the atmosphere, and the range indicated by B in the figure is that the bubbles are communicated with the atmosphere by the application of the ejection signal. The range of pulse widths in which foaming of the state occurs is shown respectively.

When the pulse width of the ejection signal is increased,
Bubbles are generated (beginning of the area A), though not so much as to eject ink with a certain pulse width, and if the bubble width is further increased, ink is ejected in a state where the bubbles do not communicate with the atmosphere. Then, when the pulse width is further increased, the ink is ejected in a state where the bubble communicates with the atmosphere (the boundary between the regions A and B).

In the present embodiment, the range of the pulse width within which the range of A and in which bubbles capable of producing effective cavitation can be generated varies depending on the individual difference in the characteristics of the ink jet head and the recording apparatus, the change over time, and the like. Focusing attention, the proper range where such cavitation occurs is detected for each inkjet head at the time of processing with kogation etc. on the heater, and by driving the inkjet head with the pulse width of the obtained area, the heater It removes and removes the kogation deposits and precipitates.

The process for removing foreign matter on the heater according to this embodiment will be described below with reference to FIGS. 4 to 8.

The recording head is moved to the above-mentioned preliminary ejection position, the pulse width of the ejection signal is changed at that position, and the recording head is driven with the pulse width, and the presence or absence of cavitation is provided on the carriage. It is detected by the acoustic sensor (step S1 in FIG. 8).

Data acquisition relating to the occurrence of cavitation will be described below with reference to FIGS. 4 and 5.
In this embodiment, data on the presence or absence of cavitation is acquired for each of the pulse widths P ₁ to P ₁₂ shown in FIG. First, the discharge at a frequency of 5kHz between 20msec at a discharge signal pulse width P ₁ as shown in FIG. 5, after then stops the driving between the inkjet head 20msec, the discharge signal pulse width P ₁ again 2
The ejection is performed at a frequency of 5 kHz for 0 msec. Such driving and stopping for 20 msec are repeated 10 times.

When an acoustic sensor having an appropriate response speed is selected and used, a signal having a sawtooth-like waveform as shown in FIG. 5 can be obtained when the head is driven as described above. Data is acquired at the timing shown by S1, S2, S3, ... In the figure. 20mse in this case
Since the driving between c is performed 10 times, data is acquired at the timing of s ₁ to s ₂₀ for the ejection signal width P ₁ , and a total of 20 data are acquired. As described above, since the data sampling is performed at a relatively long cycle of 20 msec, the influence of noise having a short cycle can be removed.

After the data of the ejection signal width P ₁ is acquired, the driving is stopped for 60 msec for heat dissipation of the ink jet head, and the same head driving and data acquisition for the next ejection signal width P ₂ are performed. After that, the same head driving and data acquisition are performed to acquire data up to the pulse width P ₁₂ .

Data 1 of each of the pulse widths P ₁ to P ₁₂ thus obtained is calculated as follows (step S2 in FIG. 8). In the following equations, shows the data obtained at the timing s _n with the same reference numerals s _n.

[0039]

## EQU1 ## d _n = s _2n -s _2n-1 ; n = 1, 2, ..., 9, 10 D = d ₁ + d ₂ + ... + d ₁₀ The pulse widths P ₁ to P ₁₂ thus obtained Each data 1 is represented by D ₁ to D ₁₂ . The above calculation is performed to remove signals having a period other than 40 msec as much as possible. The data thus obtained are shown in FIG. Further, the following processing is performed on the data 1 (step S3 in FIG. 8).

[0040]

[Equation 2] E _m = D _{m + 1} −D _m ; m = 1, 2, ..., 11 This process takes a difference for each D for continuous pulse widths and compares it with a predetermined threshold value. This is to avoid the influence of low-frequency noise on the determination of cavitation occurrence as much as possible by determining the driving condition where cavitation starts and the driving condition where cavitation disappears. Here, m corresponds to the pulse width used for the measurement. If E _m is positive, it means that the cavitation is large there, and if it is negative, it means that the cavitation is small. Data 2 thus obtained is shown in FIG.

Next, the pulse width of the ejection signal suitable for removing the foreign matter on the heater is obtained based on the above data (step S4 in FIG. 8). That is, as shown in FIG. 7, thresholds T ₁ and T ₂ are set in advance, and these thresholds are compared with the data 2 for each pulse width. In the result, when the larger pulse width is sequentially referred to from the pulse width P ₁ , the value of the data 2 is not T _{1 for the} first time.
Find the pulse width when it becomes larger. On the other hand, when referring to the smaller pulse width in order from the pulse width P ₁₂ , the pulse width at which the data 2 becomes smaller than T ₂ for the first time is obtained, and the average of this pulse width and the pulse width obtained above is calculated. This is taken as the pulse width of the ejection signal (kogation peeling drive condition) used when removing kogation deposits and precipitates on the heater.

After the kogation peeling drive condition is determined as described above, the recording head is driven under the condition (step S5 in FIG. 8) to remove foreign matter such as kogation on the heater by cavitation. .

As described above, the driving conditions for effectively causing cavitation in a state where bubbles do not communicate with each other may vary due to individual differences in characteristics of ink jet heads and recording devices, changes over time, and the like. According to this, since an appropriate driving condition is obtained in advance, it becomes possible to stably generate cavitation and satisfactorily remove kogation deposits and deposits on the heater.

In the present embodiment, the cavitation is detected by the acoustic sensor provided on the carriage, but the application of the present invention is not limited to this configuration. The position where the acoustic sensor is provided only needs to be a position where the sound of cavitation can be detected. For example, the sensor may be provided near the ink receiver that receives the ink ejected from the inkjet head, or in the inkjet head. You can make it into.

<Second Embodiment> In the first embodiment,
The presence or absence of cavitation was detected by an acoustic sensor provided on the carriage, and the data was used to determine the range of the pulse width of the ejection signal that occurred when the bubble was not in communication with the atmosphere. On the other hand, in the present embodiment, the driving condition is obtained by passing light through the flight path of the ink droplets ejected from the inkjet head and optically detecting that the light is blocked by the ejected ink droplets. That is,
The timing at which the ink droplets are ejected is optically detected as described above, and the kogation removal driving condition at this time is set.

FIG. 9 is a schematic diagram showing an outline of an optical system for detecting ink drops.

As shown in the figure, an optical path is formed in the ink flight path between the ink jet head and the ink receiver. By incorporating a lens or the like in the light source 201, the emitted light is made into parallel light. The light emitted from the light source passes through the path where the ink droplets fly, and then the optical sensor 20
Reaches 4. With this configuration, it is possible to detect that the ink has been ejected by changing the output of the optical sensor when the ejected ink droplet blocks the light.

Similarly, in this embodiment, P ₁ shown in FIG.
Ink droplets are detected by driving the inkjet head using the ejection signals with pulse widths from P to P ₁₂ . Also, in this case, as in the first embodiment, a sensor having an appropriate response speed is used, and a difference between the output of the sensor when the inkjet head is driven and the output of the sensor when the head is not driven is calculated. Moreover, the S / N ratio can be increased by further summing the data a plurality of times. The data thus obtained is referred to as data 1. Pulse width P ₁ to P
Each data 1 corresponding to ₁₂ is shown in FIG.

Similar to the first embodiment, the difference between the data 1 is taken and the data 2 is obtained. Data 2 is shown in FIG. 11 for each pulse width.

In FIG. 11, a threshold value T for determining the start of ink ejection is set, and the data 2 is T.
A minimum pulse width that becomes larger (hereinafter, referred to as P _th ) is detected. In the recording apparatus used in this embodiment is about 1.15 times the pulse width to P _th, the bubble has been found that a state in which communication with the atmosphere and thus, the P _th 1.
By driving the inkjet head by using the pulse width multiplied by 08, the kogation deposits and deposits on the heater are removed.

As described above, also in the present embodiment, the kogation deposits and deposits on the heater can be removed similarly to the first embodiment, but the optical ejection detection is performed for the ejection failure detection of the ink jet head. The ink jet recording apparatus provided with the mechanism has an advantage that the mechanism can be shared and the kogation peeling drive condition can be determined.

In the first and second embodiments described above, as a data acquisition method, data is sampled while repeating driving and pausing of a predetermined ink jet head, and the data during driving and the data during pausing are sampled. The difference was taken and summed for multiple iterations. This makes it possible to remove the influence of noise having a short cycle to some extent or noise having a cycle longer than a certain length. However, other methods of reducing noise by utilizing the periodicity depending on the driving timing of the inkjet head are conceivable, and such a method may be performed. For example, by using a sensor with good responsiveness, shortening the data sampling interval, processing the obtained data by a fast Fourier transform (FFT), and adopting only the data of the frequency that drives the head, S The / N ratio can be further improved.

<Third Embodiment> In the third embodiment of the present invention, the pulse width (P _th ) at which the head starts ejecting ink is detected from the temperature rise and fall of the ink jet head caused by predetermined blank ejection, and this is determined. It is used to determine the driving conditions for the kogation peeling drive.

FIG. 12 is a schematic diagram showing the temperature rise and fall of the recording head when a predetermined number of ejections are performed with a certain pulse width. In the figure, the broken line shows the temperature rising / falling curve when ink droplets are not ejected from the inkjet head, and the solid line shows the temperature rising / falling curve when ink droplets are ejected.

When an ink drop is ejected, some of the heat generated by the heater along with the ejected ink drop is carried away to the outside of the head, so the temperature rise and fall of the head becomes small. The temperature rise and fall of the head can be evaluated by the following formula ΔTi.

[0056]

## EQU3 ## ΔTi = (T ₂ −T ₁ ) + (T ₂ −T ₃ ) This is for more accurately evaluating the temperature rise / fall due to the heater driving even when the inkjet head has a gradual temperature change. Is.

In this embodiment, first, the temperature of the ink jet head is measured (T ₁ ), the pulse width P ₁ and the frequency 5 kHz.
The head temperature is measured by driving z for 1 second (T ₂ ).
Then, after the head drive is stopped for one second, the head temperature is measured (T ₃ ). This measurement is continuously performed for each pulse width P ₂ , P ₃ , ..., P ₁₂ .

FIG. 13 shows a rough correlation between ΔTi and the pulse width when ink droplets are not ejected from the recording head.

As is clear from the figure, ΔTi is almost proportional to the pulse width. Therefore, P _n (n = 1, 2, ..., 1
Shows the .DELTA.Ti for 2), the _{ΔTi n (P n / P 1} )
Make a comparison by dividing by the value of.

[0060]

## EQU4 ## ΔTi ' _n = ΔTi _n / (P _n / P ₁ ); n =
1, 2, ..., 12 An example of this data is shown in FIG. As shown in FIG. 14, as the pulse width increases, the value of ΔTi ′ becomes smaller than 1 when ink droplets start to be ejected.
Therefore, the threshold value T shown in the figure is set, and the minimum pulse width showing ΔTi ′ _n smaller than T is adopted as P _th .

Then, P _th is 1.0 as in the second embodiment.
It is possible to drive the ink jet head by using the head drive pulse width that is 8 times, thereby peeling the kogation deposits and deposits on the heater and removing them.

The structure of the present embodiment has an advantage that the temperature can be kept relatively low because the data can be measured by using the temperature sensor built in the ink jet head. On the other hand, it may take a relatively long time to set the pulse width and the like as compared with the cases of the first and second embodiments.

In the present embodiment, both the data of the temperature rise due to the driving of the ink jet head and the subsequent temperature decrease are used, but it is not necessary if sufficient accuracy can be obtained. Only the data is enough.

Further, in the first to third embodiments, the ejection in the ink jet head is performed by using a single rectangular pulse, but it may be driven by a plurality of pulses. Also, by making the voltage of the drive pulse variable,
The driving conditions may be changed.

Further, in each of the above-mentioned embodiments, the driving condition for the kogation peeling driving is set to a value approximately at the center of the pulse width under the condition that the bubble does not communicate with the atmosphere shown in FIG. 4, but it is sufficiently accurate. When the driving conditions for the burnt-off drive can be set, it may be better to set the input energy to be larger than the center within the range of conditions in which bubbles do not communicate with the atmosphere. This is because the larger the input energy, the larger the bubbles grow, the larger the cavitation at the time of defoaming, and the greater the effect of removing kogation deposits and precipitates on the heater.

[0066]

As is apparent from the above description, according to the present invention, the non-communication drive means drives the ink jet head in advance, and the characteristic relating to the non-communication drive of the head at this time is detected. Since the non-communication drive condition of the head is determined based on the above, the head can be driven under the non-communication drive condition suitable for the characteristics of the head.

As a result, even when the individual difference of the ink jet head or the recording apparatus and the change with time are large, the bubbles can be stably formed without communicating with the outside air through the ejection ports, and the bubbles can be eliminated. It is possible to always satisfactorily remove kogation deposits and precipitates on the heater by cavitation caused by bubbles.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of an inkjet recording apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view of an inkjet head for explaining an ejection mechanism of an example of a bubble communication ejection method.

FIG. 3 is a cross-sectional view of an inkjet head for explaining an ejection mechanism of an example of a non-bubble communication ejection method.

FIG. 4 is a diagram showing an example of a correlation between a head drive pulse width and an ink droplet ejection speed.

FIG. 5 is a diagram for explaining acquisition of cavitation occurrence data in the first embodiment of the present invention.

FIG. 6 is a diagram for explaining processing of the data in the first embodiment.

FIG. 7 is a diagram for explaining processing of the data in the first embodiment.

FIG. 8 is a flowchart illustrating a procedure of a kogation removal drive data determination process according to the first embodiment.

FIG. 9 is a diagram for explaining the configuration of an apparatus for detecting ink droplets used in the second embodiment of the present invention.

FIG. 10 is a diagram for explaining processing of data obtained by the ink drop detection in the second embodiment.

FIG. 11 is a diagram for explaining the processing of the data in the second embodiment.

FIG. 12 is a diagram for explaining temperature raising / lowering characteristics of an inkjet head according to a third embodiment of the present invention.

FIG. 13 is a diagram for explaining temperature raising / lowering characteristics of an inkjet head according to a third embodiment.

FIG. 14 is a diagram for explaining processing of data relating to temperature rise and fall of an inkjet head in the third embodiment.

FIG. 15 is an exploded perspective view showing the structure of an example of an inkjet head that ejects ink using thermal energy.

FIG. 16 is an exploded perspective view showing the structure of another example of the same inkjet head.

[Explanation of symbols]

 11, 211 Inkjet head 12 Carriage 14 Suction device 102 Electrothermal conversion element (heater) 103 Ink path 123 Ink ejection port 125 Ejection port surface

Claims (10)

[Claims] 1. An ink jet recording apparatus for performing recording using an ink jet head for forming air bubbles, communicating the air bubbles with outside air through an ejection port, and ejecting ink from the ejection port. And a non-communicating drive means for forming a state in which the air bubbles do not communicate with the outside air via the ejection port, a head characteristic detecting means for detecting characteristics of an inkjet head related to the driving of the non-communicating drive means, and at least the head characteristic detecting means. An ink jet recording apparatus comprising: a drive condition setting unit that determines a drive condition of the non-communication drive unit based on the information obtained by the above. 2. The non-communication driving means supplies driving energy of a bubble, which is smaller than a driving energy at which the bubble communicates with the atmosphere through the ejection port, and has a size capable of forming the bubble to the ejection heater of the inkjet head. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is driven by being driven. 3. The head characteristic detecting means drives the ink jet head with a plurality of levels of driving energy, and detects the cavitation at the time of defoaming of bubbles formed by an acoustic sensor to detect the characteristic of the ink jet head. It detects, It is characterized by the above-mentioned.
The inkjet recording device according to item 1. 4. The head characteristic detecting means detects the characteristic of the inkjet head by driving the inkjet head with a plurality of levels of driving energy and detecting whether or not ink is ejected from the inkjet head. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is an inkjet recording apparatus. 5. The head characteristic detecting means positions the inkjet head at a position where an ink droplet ejected from the inkjet head can pass through an optical path between a light source and an optical sensor, and the inkjet head has a plurality of steps. The inkjet head is driven by drive energy, and whether or not ink is ejected from the inkjet head is detected from the output of the optical sensor when the ink blocks the optical path, and the characteristics of the inkjet head are detected using the detection information. The inkjet recording apparatus according to claim 4, wherein the inkjet recording apparatus detects. 6. The head characteristic detection means drives the ink jet head with a plurality of levels of driving energy,
Whether or not the ink is ejected from the inkjet head is detected from the temperature increase due to the driving, the temperature decrease after ejection, or the temperature change of at least one of the temperature increase and the temperature decrease, and the inkjet information is detected using the detection information. The ink jet recording apparatus according to claim 4, wherein the characteristics of the head are detected. 7. The ink jet recording apparatus according to claim 1, wherein the drive energy is a pulse width of an electric pulse supplied to the ejection heater. 8. A method for removing foreign matter from an inkjet head in an inkjet recording apparatus, wherein recording is performed using an inkjet head that forms bubbles, communicates the bubbles with the outside air through an ejection port, and ejects ink from the ejection port. The inkjet head is driven by a non-communicating drive unit that forms bubbles and forms a state in which the bubbles do not communicate with the outside air via the discharge port, and the characteristics of the inkjet head are detected from the result of the drive, The drive condition of the non-communication drive unit is determined based on the detection, and the non-communication drive unit drives the inkjet head under the determined drive condition to remove foreign matter adhering to the ejection heater of the inkjet head. Foreign matter removal of the inkjet head characterized by having each step Law. 9. The non-communication drive means supplies drive energy of a bubble, which is smaller than drive energy at which bubbles communicate with the atmosphere through an ejection port, and is large enough to form bubbles to an ejection heater of an inkjet head. 9. The method for removing foreign matter from an inkjet head according to claim 8, wherein the driving is performed by performing the driving. 10. The method according to claim 9, wherein the drive energy is a pulse width of an electric pulse supplied to the ejection heater.