JPH11286124A - Ink nonejection recovery unit for ink jet head - Google Patents

Ink nonejection recovery unit for ink jet head

Info

Publication number
JPH11286124A
JPH11286124A JP2617099A JP2617099A JPH11286124A JP H11286124 A JPH11286124 A JP H11286124A JP 2617099 A JP2617099 A JP 2617099A JP 2617099 A JP2617099 A JP 2617099A JP H11286124 A JPH11286124 A JP H11286124A
Authority
JP
Japan
Prior art keywords
ink
discharge
pressure
jet head
supply path
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
JP2617099A
Other languages
Japanese (ja)
Inventor
Toshiaki Amano
Tatsuo Sugawara
Kunio Yasumi
邦夫 八角
敏明 天野
達夫 菅原
Original Assignee
Alps Electric Co Ltd
Fuji Photo Film Co Ltd
アルプス電気株式会社
富士写真フイルム株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to JP10-22326 priority Critical
Priority to JP2232698 priority
Application filed by Alps Electric Co Ltd, Fuji Photo Film Co Ltd, アルプス電気株式会社, 富士写真フイルム株式会社 filed Critical Alps Electric Co Ltd
Priority to JP2617099A priority patent/JPH11286124A/en
Publication of JPH11286124A publication Critical patent/JPH11286124A/en
Withdrawn legal-status Critical Current

Links

Abstract

PROBLEM TO BE SOLVED: To recover from nonejection of ink due to adhesion of a foreign matter or a bubble to the inside of an ink jet head while preventing an unnecessary bubble from being mixed into the ink head by regulating the inner pressure in the ink supply path being boosted through a boosting means to a set level. SOLUTION: Each ink jet head 10 for yellow, magenta, cyan and black is provided with two ejection nozzles 12. A bubble mixed into ink being fed to the ink jet head 10 is captured in a buffer chamber 12a for regulating the pressure formed on the back side of the nozzle 12. A piezoelectric element being distorted by ink flow is disposed at an appropriate position of an ink supply path and a voltage generated through distortion is detected by a voltage detecting means 26. A decision is made whether ink is ejected or not based on the variation of voltage and when ink is not ejected, a boosting means 19 is driven to boost the pressure in an ink tank 16 thus unclogging the nozzle 12 or removing a bubble therefrom.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-discharge recovery apparatus for an ink jet head used in an ink jet printer for performing recording by jetting ink from a discharge nozzle toward a recording sheet, and an ink jet printer having the same. It is. In particular, the present invention relates to a non-discharge recovery device for an ink-jet head suitable for recovering non-discharge of ink due to the presence of foreign matter or bubbles in a discharge nozzle, and to an ink-jet printer including the same.

[0002]

2. Description of the Related Art In general, an ink jet printer is used as an output device such as a computer or a word processor.

In a conventional ink jet printer, a carriage shaft is disposed in parallel with a platen having a flat plate shape, and a carriage is mounted on the carriage shaft so as to be reciprocally movable. Here, an ink jet head is mounted on the carriage, and an ink discharge nozzle is opened at a position facing the platen of the ink jet head so as to face a recording surface of the platen.

In such a conventional ink jet printer, a recording sheet is conveyed between a platen and an ink jet head, and the carriage is reciprocated while being driven.
Form an image. Here, the inkjet head records a desired image on recording paper by discharging ink based on a predetermined recording signal.

When recording is performed using such an ink jet printer, foreign matter and bubbles may adhere to the discharge nozzles of the ink jet head. If these foreign substances or bubbles adhere, the discharge ports of the discharge nozzles are blocked or narrowed, which causes non-discharge of ink.

In order to solve the problem of non-ejection of ink, in a conventional ink jet printer, foreign matter and bubbles are removed from the ejection nozzle by a non-ejection recovery device. As a method of performing the non-ejection recovery, a suction recovery method and a pressure recovery method are known. In the suction recovery method, the inkjet head is moved to the home position of the carriage to cover the ejection nozzle, and the cap is suctioned to a negative pressure, thereby sucking foreign matter together with the ink in the ejection nozzle to recover non-ejection. Is the way. The pressure recovery method is a method of recovering non-discharge by pressurizing the ink in the ink tank to eject foreign matter together with the ink from the discharge nozzle.

[0007]

In the suction recovery method described above, it is necessary to keep the airtightness by bringing the cap into close contact with the discharge nozzle in order to suck the ink by the cap. There was a problem that was difficult. Further, in the conventional pressure recovery method described above, it is difficult to keep the ink discharge pressure for non-discharge recovery constant for each discharge nozzle, and the pressure tends to vary. If an excessive internal pressure acts in a normal ejection nozzle, unnecessary air bubbles may be generated in the normal ink jet head.

The present invention has been made in view of the above points, and reliably recovers ink non-discharge caused by foreign matter or bubbles adhering to the ink-jet head, and eliminates unnecessary bubbles in the ink head. It is a first object of the present invention to provide a non-ejection recovery device for an ink jet head which can prevent the ink from being mixed. The second is to provide an inkjet printer equipped with this.
It is the purpose of.

[0009]

According to the present invention, the first object can be achieved by driving the pressurizing means to adjust the increased internal pressure in the ink supply path to a set pressure value. That is, an object of the present invention is to provide a non-discharge recovery device for an ink jet head that performs image recording by discharging ink droplets from a discharge nozzle of an ink jet head toward a recording sheet, and detects non-discharge of an ink droplet from a discharge nozzle. A non-discharge detecting means for outputting a non-discharge signal, a pressurizing means for increasing an internal pressure of an ink supply path communicating with the inkjet head, a pressure measuring means for detecting an internal pressure of the ink supply path, and the non-discharge signal Control means for controlling the pressurizing means so that the internal pressure of the ink supply path detected by the pressure measuring means based on the pressure measuring means becomes a set pressure value to discharge ink. This can be achieved by a non-discharge recovery device.

The ink jet head used here includes:
A piezo inkjet system can be used. In this method, a piezoelectric element (piezo element) is provided so as to be in contact with the ink supply path, and a driving voltage is applied to the piezoelectric element to deform the piezoelectric element. Discharge. As the non-ejection detecting means, a piezoelectric element used in the piezo inkjet method can be used. That is, when the piezoelectric element is deformed due to a change in the internal pressure of the ink supply path, a voltage is generated between both ends thereof (piezoelectric effect). Therefore, it is possible to determine the ejection / non-ejection based on the voltage generated by the piezoelectric effect. it can. Here, when the ink is normally ejected, the internal pressure of the ink supply path fluctuates greatly due to the movement of the ink, whereas when the ink is not ejected, the ink does not move and the fluctuation of the internal pressure is small. Become. For this reason, when the fluctuation of the voltage generated by the piezoelectric effect of the piezoelectric element is large, it is possible to determine that the normal ejection is performed, and when the fluctuation is small, it is determined that the ejection is not performed.

When the non-ejection detecting means detects the non-ejection of the ink and outputs a non-ejection signal, the control means raises the internal pressure of the ink supply path to a predetermined set pressure value and then drives the piezoelectric element. If ink is ejected from the ejection nozzles, foreign matter and bubbles can be more reliably removed. In this case, if the driving voltage of the piezoelectric element is set higher than the driving voltage at the time of normal operation, for example, if the voltage is about twice as high, the ejection pressure of the ink is further increased, and the removal of foreign matter and bubbles is more reliably performed. I can do it.

In such a non-ejection recovery operation, it is possible to simultaneously determine whether or not the amount of ink remaining in the ink supply path is insufficient, that is, determine whether or not ink remains. Generally, when the ink supply system is once pressurized, the pressure reduction speed during the rest is small when the ink is sufficiently contained in the ink supply system, and the amount of ink remaining in the ink supply system is small. It becomes bigger. The presence or absence of the remaining ink is determined by utilizing the fact that the pressure reduction speed changes depending on the remaining amount of the ink. That is, during the non-ejection recovery operation, the piezoelectric element is driven for a short time after the ink supply system is pressurized to a predetermined pressure value to discharge foreign substances and bubbles, and at the same time, the pressure reduction rate during and after this is monitored. If the rate of pressure decrease is greater than a certain value, it is determined that there is no remaining ink.

The ink jet head is provided with a buffer chamber for separating air bubbles mixed into the ink, and when the amount of air accumulated in the buffer chamber is adjusted by the head solenoid valve, the buffer chamber is controlled prior to the non-ejection recovery operation. It is advisable to adjust the amount of air in the room. That is, when the amount of air accumulated in the buffer chamber becomes equal to or more than the specified value, bubbles mixed in the ink cannot be separated here, and non-discharge often occurs. Therefore, in this case, the ink supply path is pressurized once based on the non-discharge signal, the head solenoid valve is opened to discharge excess air in the buffer chamber, and then the ink supply path is pressurized again to recover the original non-discharge recovery. The operation may be performed.

It is preferable that the tip of the discharge nozzle of the ink jet head be wiped with a wiper after the non-discharge recovery operation. In a normal non-ejection recovery operation, if the ink supply path is pressurized to eject ink from the ejection nozzle and then the internal pressure of the ink supply path is reduced, ink droplets may adhere to the tip of the ejection nozzle and remain. In addition, ink or foreign matter may be attached around the discharge nozzle. The wiper is for removing ink and foreign matter adhering to the discharge nozzle in this manner, and can operate the wiper using the time for releasing the internal pressure of the ink supply path after the end of the non-discharge recovery operation.

The pressurizing means can be formed by a pressurizing pump for supplying pressurized air to the ink tank, that is, an air pump. In this case, the pressure measuring means can be formed by a pressure sensor that detects the air pressure in the pressurized air passage that connects the pressurizing pump and the ink tank.

When a plurality of ink jet heads and a plurality of ink tanks are provided for different colors, one pressure relay unit pressurized by one pressurizing pump and one pressure connecting unit connected thereto are provided. A sensor and one pressure release valve can be provided, and this pressure relay can be separately connected to each tank via a tank solenoid valve. In this case, by maintaining the pressure relay unit at a constant pressure, this constant pressure can be guided to an arbitrary ink tank by opening the tank solenoid valve. Therefore, the configuration can be simplified as compared with a case where a pressure pump, a pressure sensor, and a pressure release valve are separately provided for each ink tank.

In the case where a plurality of ink jet heads are provided, non-ejection of ink can be separately detected for each ink jet head, and a non-ejection recovery operation can be performed only for the ink jet head that has failed. . In this case, wasteful consumption of ink is reduced.

After the internal pressure in the ink supply path increased by driving the pressurizing means once decreases, the control means drives the pressurizing means again to increase the internal pressure in the ink supply path to a set pressure value. You may do so. In this case, the internal pressure of the ink jet head can be more easily and reliably increased to the set pressure value only by performing the two-stage pressurization.

According to the present invention, the second object is to provide an ink jet printer which supplies ink from an ink tank to an ink jet head, and performs recording by discharging ink from a discharge nozzle to a recording sheet based on a predetermined recording signal. The present invention can be achieved by an ink jet printer including the above-mentioned ink jet non-discharge recovery device for an ink jet head.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a first embodiment of an ink jet printer provided with an ink jet non-discharge recovery device for an ink jet head according to the present invention. Reference numeral 1 denotes a printer main body, and the printer main body 1 is supported by a pair of stands 3, 3 extending vertically and having a plurality of casters 2 positioned at the lower end thereof at the front and rear. The stands 3 are connected to each other by an auxiliary frame 4 located at the center of the stands 3 in the vertical direction.

In the printer main body 1, a flat platen 5 is provided so as to face upward. A large number of suction holes 5a are formed in the upper surface of the platen 5, and a recording sheet (not shown) carried on the platen 5 and conveyed is sucked and brought into close contact with the platen 5. Behind the platen 5 of the printer main body 1, two carriage shafts 7, 7 extending parallel to the longitudinal direction of the platen 5 are provided. A carriage 8 is mounted on these carriage shafts 7, 7 so as to be able to reciprocate along the carriage shafts 7, 7. A carriage drive belt 9 located between the carriage shafts 7 is connected to the carriage 8. The carriage driving belt 9 is driven by a driving device (not shown), and as a result, the carriage 8 is moved to the carriage shafts 7, 7.
Reciprocating along.

A head unit 50 is mounted on the carriage 8 at a position facing the platen 5, and four ink jet heads 10 are mounted on the head unit 50. These inkjet heads 10
Is mounted so that the ink discharge nozzle 12 faces the recording surface of the platen 5. In the first embodiment, the four inkjet heads 10 correspond to four colors of yellow (Y), magenta (M), cyan (C), and black (BK). Each inkjet head 10 has two ejection nozzles 12. That is,
It is composed of a total of eight discharge nozzles 12. FIG.
Here, four ejection nozzles 12 are shown for simplicity. A piezoelectric element, that is, a piezo element (not shown) is attached to an ink supply path (not shown) in the discharge nozzle 12. The piezoelectric element is mounted so as to be in contact with the outer peripheral wall of the ink supply path, and presses the ink in the ink supply path by applying a drive voltage to the piezoelectric element to deform the piezoelectric element. As a result, a predetermined amount of ink can be ejected from the ejection nozzle 12 located at the tip of each ink supply path.

Each ink jet head 10 has a buffer chamber 12 a for pressure adjustment on the back side of the discharge nozzle 12.
Are formed. Inside the buffer chamber 12a,
Ink is stored, and a certain amount of air is sealed above the ink. Air bubbles mixed into the ink sent to the ink jet head 10 through the ink supply path are captured by the buffer chamber 12a, and
2 is prevented. The buffer chamber 12a also has a role of a damper for absorbing and attenuating the wave fluctuation of the ink generated in the ink jet head 10 due to the reciprocating movement of the carriage 8. A head solenoid valve 13 is provided above the buffer chamber 12a. This head solenoid valve 13
Is opened, excess air accumulated in the buffer chamber flows out, and the amount of air in the inkjet head 10 becomes constant.

Discharge nozzle 1 of ink jet head 10
A wiper 14 for wiping ink droplets and dirt adhering to the ejection surface is provided at a position facing the ejection surface of No. 2 in a swingable manner. The wiper 14 is driven by a wiper motor 15.

In the first embodiment, the number of the wiper motors 15 is one, and as shown in FIG. 2, the wipers 14 provided for the respective ink jet heads 10 are swung in conjunction with each other. However, the wiper motor 15
May be provided separately and independently.

On one side behind the printer main body 1, four ink tanks 16 are provided for each color. Each of these ink tanks 16 and the inkjet head 10
Are connected by a tube 18. Tube 18
Ink is supplied from each ink tank 16 to each ink jet head 10 via the carriage 8.

A pressure means 19 such as a pressure pump is connected to the ink tank 16 via a pressure relay section 20.
Reference numeral 22 denotes a pressurizing air passage connecting these. The pressurizing unit 19 is connected to the ink tank 16 through the pressurizing air passage 22.
To supply air into the tube 18 via ink,
The internal pressure of the ink supply path in the inkjet head 10 or the like is increased.

The pressure relay section 20 provided between the pressurizing means 19 and the ink tank 16 is connected to a pressure measuring means 23 such as a pressure measuring device for measuring the pressing force of the pressurizing means 19. I have. A pressure release valve 24 is connected to the pressure relay section 20. The pressure release valve 24 releases the pressure pressurized by the pressurizing means 19 to the outside.

On the other hand, each ink tank 16 and the pressure relay 2
A tank solenoid valve 25 is provided in the middle of the pressurizing air passage 22 that communicates with zero. These tank solenoid valves 25 are
The valve is opened at the time of non-excitation, and air is supplied from the pressurizing means 19 into the ink tank 16. The tank solenoid valve 25 closes at the time of excitation to stop the supply of air into the ink tank 16.

During normal operation, the tank solenoid valve 25 is closed, and the pressurizing means 19 supplies air to each of the ink tanks 16 to increase the internal pressure of the ink supply path when recording on recording paper. The internal pressure at this time is a low constant pressure value (for example, 1.3 atm). When bubbles or foreign matter adheres to the inside of the discharge nozzle 12 and an ink non-discharge state is detected, this state is detected as described later, and the internal pressure of the ink tank 16 is higher than the internal pressure during normal printing, that is, a high set pressure. Pressurize to a value (eg, 1.35 atm). In the first embodiment, the high set pressure value is set to about 1.25 to 1.4 at in consideration of reliably removing foreign matter and bubbles from inside the discharge nozzle 12 and not destroying the discharge nozzle 12.
It is preferable to maintain the value in the range of m.

The head solenoid valve 13, the tank solenoid valve 25, and the pressure release valve 24 are opened and closed at a predetermined timing by a control means 29 described later.

The detection of an ink non-ejection state is performed as follows. In the ink supply path located in the ink jet head 10, the flow of the ink causes distortion of the piezoelectric element (piezoelectric element). Due to this distortion, a voltage is generated on both sides of the piezo element. Therefore, each piezoelectric element is connected to voltage detecting means 26 for detecting the voltage at both ends thereof, and it is possible to detect the presence or absence of ink flow, that is, the presence or absence of ink ejection, based on the detected voltage change. .

The voltage detecting means 26 is connected to a non-discharge detecting means 28 for determining the presence or absence of ink discharge from the detected voltage change. This non-discharge detection means 28
When the specific discharge nozzle 12 is in a non-discharge state due to clogging or a bubble or the like, a change in voltage across the piezo element is small when the specific discharge nozzle 12 is in a non-discharge state. A non-ejection signal indicating the presence is output to the control means 29.

The control means 29 outputs a drive signal to the pressurizing means 19 to pressurize the ink tank 16 when a non-discharge signal is inputted from the non-discharge detecting means 28.

On the other hand, to the pressure measuring means 23, an ink remaining / absent determining means 30 for determining whether or not there is ink in the ink tank 16 is connected. The remaining ink presence / absence determining means 30 monitors the rate of decrease of the internal pressure when the internal pressure of the ink tank 16 is increased to the set pressure value by the pressure means 19 and the application is stopped. The ink tank 16 depends on the magnitude of the rate of decrease in the internal pressure, in other words, whether or not the internal pressure is equal to or greater than a predetermined pressure value after the set time has elapsed.
It is determined whether or not the ink in the ink remains.

That is, when the ink is filled in the ink supply system such as the ink tank 16 and the tube 18, the internal pressure decreasing speed is reduced and the internal pressure is gradually decreased. If not, the internal pressure drops rapidly. This property is used to determine whether ink remains.

The set time for detecting the decreasing speed of the pressurized internal pressure is shorter than the time required for the internal pressure to become equal to or less than a predetermined pressure value when the ink supply system is normally filled with ink. I just need.

This will be described more specifically with reference to FIG. The internal pressure of the ink tank 16 is increased by the pressurizing means 19,
After detecting that the pressure has risen to 1.3 atm by the pressure measuring means 23, pressurization is continued for another 1 second to terminate the pressurization. Two seconds after the end of the pressurization, the internal pressure is detected again. Then, the internal pressure is a constant pressure value of 1.3.
If it is not less than atm, it is determined that there is ink in the ink tank 16. If it is less than 1.3 atm, it is determined that the ink in the ink tank 16 has run out.

The ink remaining / absence determining means 30 includes:
A timer (not shown) is built in, and the timer measures the time from the end of pressurization by the pressurizing means 19 to the re-detection after a lapse of 2 seconds.

The ink remaining / non-existence judging means 30 in the first embodiment uses the pressurizing means 19 used for recovering from ink non-ejection in order to simplify the structure. That is, the presence or absence of ink remaining is determined based on the internal pressure applied by the pressurizing means 19 and the rate of decrease of the internal pressure. However, the present invention is not necessarily limited to the one using the pressurization at the time of recovery from the ink non-discharge. At any time other than the time of ink non-discharge recovery, the ink tank 16
May be pressed to determine whether ink remains.

It is preferable that the determination of the presence or absence of the remaining ink is repeated a plurality of times in order to improve the accuracy. This is because if the ink does not remain in the ink tank 16 but remains in the tube 18, the state does not appear to decrease in the internal pressure and may be erroneously recognized.

In the first embodiment, the control means 29 and the ink remaining / non-existence judging means 30 are configured separately and independently.
The configuration may be such that the control unit 29 determines whether or not ink remains.

The remaining ink presence / absence determining means 30 is connected with the remaining ink presence / absence display means 32. When it is determined that there is no ink in the ink tank 16, the remaining ink presence / absence display means 32 emits an error display or a warning sound. To alert the user or stop the operation of the inkjet printer. Conversely, if it is determined that ink remains,
The ink remaining / absent display means 32 is configured to display that there is ink remaining or to emit a warning sound.

One side of the platen 5 of the printer body 1 (FIG. 1)
(Left side in FIG. 3) is the home position of the inkjet head 10. A cap 33 is provided at a position corresponding to the home position.
Covers the discharge nozzle 12 when the discharge nozzle 12 is not used,
This prevents the discharge nozzle 12 from drying or adhering foreign matter. The cap 33 is used for the ink jet head 10.
The ink ejected by the ink non-ejection recovery operation of the ejection nozzle 12 is suctioned and collected by the negative pressure.

The auxiliary frame 4 is provided with a winding mechanism 34. The winding mechanism 34 includes the auxiliary frame 4
Has a pair of supports 35a and 35b located on both sides of the support. In the present embodiment, the one support 35a
1 (left side in FIG. 1) is fixed to the auxiliary frame 4, and the other support 35 b is movable along the auxiliary frame 4.

Each of the supports 35a and 35b is formed with a shaft supporting recess 38 which is open at the top and supports the winding shaft 36. Inside the shaft support recess 38, three support rollers 39 are rotatably arranged. The winding shaft 36 is rotatably and detachably supported by these support rollers 39.

A take-up drive gear 40 is provided below the shaft support recess 38 of one of the supports 35a. A take-up driven gear 42 that meshes with the take-up drive gear 40 is formed at one end of the take-up shaft 36. Then, the winding drive gear 40 is driven to rotate, whereby the winding shaft 36 is driven to rotate via the winding driven gear 42.

Next, the operation of the first embodiment will be described.

In the ink jet printer according to the first embodiment, a recording sheet is conveyed between the platen 5 and the ink jet head 10 by a sheet conveying device (not shown). In addition, the carriage driving belt 9 is driven to reciprocate the carriage 8 along the carriage shafts 7,7. On the other hand, the piezo element of the inkjet head 10 operates based on a predetermined recording signal to cause the discharge nozzle 12 to discharge ink. Thus, a desired image is recorded on the recording paper.

By rotating the take-up drive gear 40 in synchronization with the carrying operation of the sheet carrying device, the take-up shaft 36 is driven to rotate via the take-up driven gear 42. By taking up the sheet after recording by the winding shaft 36, it is possible to prevent the recording sheet after recording from being wrinkled or creased.

During recording, the voltage detecting means 26 detects the voltage between both ends of each piezo element corresponding to each ejection nozzle 12. The voltage of each piezo element is output from the voltage detecting means 26 to the non-ejection detecting means 28.
It is detected whether or not any of the ejection nozzles 12 is non-ejection. During recording, clogging or bubbles occur in the ink supply path of the inkjet head 10 and the discharge nozzle 1
When the non-ejection of the ink from the nozzle 2 occurs, the
Numeral 8 detects the discharge nozzle in the non-discharge state and outputs a non-discharge signal to the control means 29 indicating which discharge nozzle 12 is non-discharge.

When the non-ejection signal is input to the control means 29, the control means 29 stops printing, returns the carriage to the home position, and performs a non-ejection recovery operation. That is, first, the cap 33 is attached to the discharge nozzle 12 at this home position. Thereafter, with the air release valve (not shown) of the cap 33 opened, the ink flowing down is suctioned at a negative pressure, and the pressurizing means 19 is driven as shown in FIG. 4B.

As a result, air is sent into the ink tank 16 through the pressure relay section 20 and the pressurizing air passage 22 to pressurize the ink in the ink supply path. FIG.
(A) shows the internal pressure of the ink supply path detected by the pressure measuring means 23. As shown in FIG. 4 (A), the internal pressure of the ink supply passage is set to about 1.35 (1.35 atm (constant pressure value) or more).
atm (set pressure value) (point A1 in FIG. 4).

Next, the control means 29 turns on the head solenoid valve 13 and opens it, as shown in FIG. 4C. By this operation, the air in the buffer chamber 12a is discharged to make the amount of air constant, and the pressure in the buffer chamber 12a is adjusted. When the air in the buffer chamber is exhausted and the ink flows from the discharge nozzle 12 to the cap 33, the pressure in the inkjet head 10 decreases as indicated by A2 in FIG. 4A.

Thereafter, in order to replenish the pressure drop, the control means 29 again pressurizes the pressurizing means 19 as shown in FIG.
Is driven to supply air into the ink tank 16 via the pressure relay section 20 and the pressurizing air passage 22, and pressurized as indicated by A3 in FIG. That is, a period until the pressurizing unit 19 is driven again (a period L in FIG. 4A) functions as an air amount adjustment period of the buffer chamber 12a.

The internal pressure in the ink supply path is about 1.35 atm.
When the pressure is again increased to (set pressure value), the pressurization is stopped (point A4 in FIG. 4A), and the control means 29 sets the piezo element to about twice the normal recording as shown in FIG. 4D. And the ink is ejected from the ejection nozzle 12 at a high pressure. The beating at this time causes the foreign matters and bubbles adhering to the inside of the discharge nozzle 12 to be peeled off, and is discharged into the cap 33 together with the ink.

After the ink is discharged at a high pressure as described above,
As shown in FIG. 4 (E), the pressure release valve 24 is opened to release the pressure of the pressurizing means 19, and the inside of the pressure relay unit 20 is set to the atmospheric pressure (A5 in FIG. 4 (A)). At this time, before the pressure is completely reduced to the atmospheric pressure, the wiper motor 15 is driven as shown in FIG. In this manner, the ink adhered to the ejection nozzles 12 of the inkjet head 10 is wiped off.

On the other hand, the ink tank 1 is
When the internal pressure in Step 6 is increased, the ink remaining / absence determining means 30 simultaneously determines whether or not ink remains in the ink supply path. That is, after the internal pressure in the ink supply path is increased to about 1.35 atm (about 1 second has elapsed after the detection of 1.3 atm) by the pressurizing means 19, the pressurization is terminated (A4 in FIG. 4A). After a lapse of 2 seconds from (point), it is detected whether the pressure is above or below 1.3 atm. 1.3a
tm or more, it is determined that ink remains.
If it is less than 1.3 atm, it is determined that there is no ink remaining. A period M shown in FIG. 4A is a period for determining whether or not ink remains.

Such determination is repeated a predetermined number of times, and when it is finally determined that there is no ink remaining, the ink remaining / absent display means 32 notifies the user by displaying an error or a warning sound. Further, a signal is output to the control means 29 to stop the non-discharge recovery operation.

Therefore, according to the first embodiment, non-ejection of ink caused by foreign matter or bubbles adhering to the ink jet head 10 can be reliably recovered.

Further, since the presence / absence of ink remaining in the ink tank 16 can be determined by using the ink non-discharge recovery device, the structure is simple and the manufacturing cost is low, and the disposal of the ink tank 16 is not troublesome.

[0063]

Second Embodiment Next, a second embodiment of the present invention will be described. In the configuration of the second embodiment, components that are considered to be equivalent or equivalent to the configuration of the above-described first embodiment are denoted by the same reference numerals, and the description thereof will not be repeated.

In the first embodiment described above, when the non-discharge detecting means 28 outputs the non-discharge of any of the discharge nozzles 12, the control means 29 controls the non-discharge state including the discharge nozzles 12 in which the non-discharge state has not occurred. An ejection recovery operation is performed. On the other hand, in the second embodiment, the first embodiment is such that the recovery operation is performed only on the ejection nozzles 12 in the ink non-ejection state.

This will be described more specifically with reference to FIG. For example, consider a case where the ejection nozzles 12 of the inkjet head 10 for black ink are in a non-ejection state. FIG. 5A shows the pressure applied to the ink head other than the normally operating black ink, and FIG. 5Abk shows the pressure applied to the ink head of the black ink in the non-ejection state. In this case, first, the tank solenoid valve 25 for the black ink is kept off, that is, in the open state, and the tank solenoid valves 25 for the other inks (yellow, magenta, and cyan) are turned on and closed. (FIG. 5 (G), (H)). In this manner, only the black ink tank 16 is communicated with the pressurizing means 19.

In this state, the pressurizing means 19 is driven to supply air into the black ink ink tank 16 through the pressure relay section 20 and the pressurizing air passage 22. Then, the internal pressure of the black ink in the ink supply path is increased to 1.35 atm (set pressure value). Next, among the head electromagnetic valves 13, only the valves related to the black ink discharge nozzles 12 are opened, and the air amount of the black ink in the buffer chamber 12 a in the ink head 10 is adjusted to be constant.

Thereafter, the air amount in the buffer chamber 12a corresponding to the black ink is adjusted and the discharge nozzle 12 is adjusted.
The ink from the ink jet head 10
Internal pressure decreases. Then, the pressurizing means 19 is driven again to supply air into the black ink ink tank 16, and the internal pressure in the ink supply path is set to the set pressure value of 1.35.
Press until atm. In addition, the piezo element is
Pulsing with double the voltage, discharge nozzle 1 of black ink
Foreign matter and air bubbles adhering to 2 are ejected with ink at high pressure.

After the non-ejection of the ink jet head 10 relating to the black ink is recovered in this way, the pressurizing means 19 is driven again, and the tank solenoid valves 25 other than the black ink are turned off and opened. The valve is pressed to pressurize the inside of each ink tank 16. Then, the ink is caused to flow out from all the ink jet heads 10 and the ejection surface of the ejection nozzle 12 is wiped by the wiper 14.

The reason why the ink is caused to flow out of all the ink jet heads 10 after the recovery from the non-discharge is as described in the second embodiment.
Each wiper 14 in the embodiment has one wiper motor 1
5 is driven. That is, only the wiper 14 for black ink cannot be driven, and the discharge surface of another color will be damaged unless the ink has flowed out from all the discharge nozzles 12. Therefore, if a wiper motor 15 that is driven separately and independently is connected to the wiper 14 for each color, only the wiper 14 related to the black ink may be driven when the pressure is reduced after high-pressure ejection.

Therefore, according to the second embodiment, in addition to the effects of the first embodiment, the high-pressure ejection for the non-ejection recovery operation is not performed for the ink jet head 10 in which the ink ejection is normal. Therefore, an effect of reducing wasteful consumption of ink can be obtained.

The present invention is not limited to the above-described embodiment, but can be variously modified as needed. For example, the head solenoid valve, the tank solenoid valve, and the pressure release valve each use an electromagnetic valve because it can be easily and surely opened and closed by an electromagnetic action, but the invention is not limited to this. Is also good.

[0072]

As described above, according to the apparatus for recovering non-ejection of an ink-jet head according to the present invention, the control means adjusts the internal pressure in the ink-jet head to the set pressure value when the non-ejection state is detected. Therefore, non-ejection can be recovered by reliably removing bubbles and foreign matters in the inkjet head.

In addition, if a non-ejection state of ink is individually detected for a plurality of ink jet heads and ink is jetted for non-ejection recovery only for non-ejection heads, wasteful consumption of ink can be reduced. Can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of an ink jet printer provided with an ink ejection failure recovery device for an ink jet head according to the present invention.

FIG. 2 is a schematic circuit diagram illustrating a main part of an embodiment of an ink jet printer having an ink ejection failure recovery device for an ink jet head according to the present invention.

FIG. 3 is an explanatory diagram showing a principle of determining whether or not ink remains by an ink remaining / non-determining unit according to the embodiment;

FIG. 4 is a timing chart for ink non-ejection recovery according to the first embodiment of the present invention.

FIG. 5 is a timing chart for ink non-ejection recovery according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printer main body 5 Platen 8 Carriage 10 Ink jet head 12 Discharge nozzle 12a Buffer chamber 13 Head electromagnetic valve 14 Wiper 16 Ink tank 18 Tube 19 Pressurizing means 23 Pressure measuring means 24 Pressurizing release valve 25 Tank electromagnetic valve 26 Voltage detecting means 28 Non Discharge detecting means 29 Control means 30 Ink remaining / absent determining means 32 Ink remaining / absent displaying means 50 Head unit

Continued on the front page (72) Inventor Kunio Octagon 2-26-30 Nishiazabu, Minato-ku, Tokyo Inside Fujisha Shin Film Co., Ltd.

Claims (15)

    [Claims]
  1. A non-discharge recovery apparatus for an ink-jet head for recording an image by discharging ink droplets from a discharge nozzle of the ink-jet head toward a recording sheet, wherein the non-discharge recovery of the ink droplet from the discharge nozzle is detected. A non-discharge detecting means for outputting a non-discharge signal; a pressurizing means for increasing an internal pressure of an ink supply path communicating with the inkjet head; a pressure measuring means for detecting an internal pressure of the ink supply path; A control unit for controlling the pressurizing unit so that the internal pressure of the ink supply path detected by the pressure measuring unit on the basis of the pressure measurement unit becomes a set pressure value.
  2. 2. An ink jet head comprising a piezoelectric element mounted so as to be in contact with an ink supply path, and by applying a drive voltage to the piezoelectric element, the piezoelectric element is deformed to increase the internal pressure of the ink supply path. The non-discharge recovery device for an ink-jet head according to claim 1, which discharges ink.
  3. 3. A non-discharge detecting means for monitoring a change in a generated voltage caused by a deformation of the piezoelectric element due to a change in an internal pressure of an ink supply path immediately after an ink discharging operation, and based on the change in the generated voltage, a discharge / non-discharge state. 3. The ink ejection failure recovery device for an ink jet head according to claim 2, wherein ejection is determined.
  4. 4. The ink-jet head according to claim 2, wherein the control means increases the internal pressure of the ink supply path to a set pressure value based on the non-ejection signal, and then drives the piezoelectric element to eject the ink. Ink discharge recovery device.
  5. 5. An ink ejection failure recovery apparatus for an ink jet head according to claim 4, wherein the drive voltage of the piezoelectric element is higher than the drive voltage during normal operation.
  6. 6. A non-ejection recovery operation, wherein the rate of decrease of the ink supply path internal pressure after the ink supply path internal pressure is increased to a predetermined pressure value by the pressure means is monitored, and based on the magnitude of the decrease rate, the presence or absence of ink remaining is determined. The ink non-ejection recovery device for an ink jet head according to any one of claims 1 to 5, further comprising an ink remaining / absence determination unit for performing a determination.
  7. 7. An ink-jet head comprising: a buffer chamber which communicates with an ink supply path and separates bubbles mixed into ink;
    A head solenoid valve for exhausting the air in the buffer chamber; the control means activates the pressurizing means based on the non-ejection signal prior to the non-ejection recovery operation to increase the pressure in the ink supply path; 7. The non-discharge recovery device for an ink jet head according to claim 1, wherein a valve is opened to adjust an amount of air in the buffer chamber.
  8. 8. A wiper for wiping the discharge surface of the discharge nozzle, wherein the control means opens a pressure release valve for releasing the internal pressure of the ink supply path after completion of the ink non-discharge recovery operation. The non-ejection recovery device for an ink jet head according to any one of claims 1 to 7, wherein the wiper is operated after the opening operation.
  9. 9. The pressurizing means is formed by a pressurizing pump for supplying pressurized air to an ink tank connected to the ink jet head, and the pressure measuring means is a pressurizing air passage communicating the pressurizing pump and the ink tank. The non-ejection recovery device for an ink-jet head according to any one of claims 1 to 8, wherein the device is formed by a pressure sensor that detects an air pressure in the ink jet head.
  10. 10. A plurality of ink jet heads corresponding to different colors, a plurality of ink tanks corresponding to each ink jet head, a pressure relay unit pressurized by one pressurizing pump, and a plurality of pressure relay units. Tank solenoid valves provided in a plurality of pressurized air passages communicating with the ink tanks, one pressure sensor for detecting the pressure of the pressure relay, and one pressure release for releasing the internal pressure of the pressure relay. An ink non-discharge recovery device for an inkjet head according to any one of claims 1 to 9, further comprising a valve.
  11. 11. A non-ejection detecting means for individually detecting the presence or absence of an ink non-ejection state for a plurality of ink jet heads, and a control means for performing a non-ejection recovery operation for an ink jet head in an ink non-ejection state. The non-discharge recovery device for an ink-jet head according to claim 10.
  12. 12. A non-discharge detecting means for detecting non-discharge of ink from discharge nozzles of a plurality of ink jet heads for each discharge nozzle and outputting a non-discharge detection signal; pressurization for increasing an internal pressure in an ink supply path. And control means for driving the pressurizing means to increase the internal pressure of each ink supply path to discharge ink from the discharge nozzle when a non-discharge signal of any of the nozzles is output from the non-discharge detection means. A non-discharge recovery device for an ink jet head, comprising: the control means driving the pressurizing means to adjust the increased internal pressure in the ink supply path to a set pressure value. Non-discharge recovery device for inkjet heads.
  13. 13. The control means sets the internal pressure in the ink supply path by driving the pressurization means again after the internal pressure in the ink supply path increased by driving the pressurization means once decreases. 13. The non-discharge recovery device for an ink jet head according to claim 12, wherein the pressure value is increased to a pressure value.
  14. 14. The apparatus according to claim 1, wherein said control means increases the internal pressure of only the ink supply path of the discharge nozzle to which the non-discharge signal is output by said non-discharge detection means to a set pressure value. 12 or Claim 13
    2. The non-discharge recovery device for an ink-jet head according to claim 1.
  15. 15. An ink jet printer which performs recording by supplying ink from an ink tank to an ink jet head and discharging ink from a discharge nozzle to a recording sheet based on a predetermined recording signal. 14. An ink jet printer, comprising: the ink non-discharge recovery device for an ink jet head according to any one of 14.
JP2617099A 1998-02-03 1999-02-03 Ink nonejection recovery unit for ink jet head Withdrawn JPH11286124A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
JP10-22326 1998-02-03
JP2232698 1998-02-03
JP2617099A JPH11286124A (en) 1998-02-03 1999-02-03 Ink nonejection recovery unit for ink jet head

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2617099A JPH11286124A (en) 1998-02-03 1999-02-03 Ink nonejection recovery unit for ink jet head

Publications (1)

Publication Number Publication Date
JPH11286124A true JPH11286124A (en) 1999-10-19

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
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Country Link
JP (1) JPH11286124A (en)

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JP2007223315A (en) * 2006-02-20 2007-09-06 Samsung Electronics Co Ltd Inkjet printing system, inkjet printer head, control method of inkjet printing system and recording medium
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