JPH06328723A - Ink jet recording apparatus - Google Patents

Abstract

PURPOSE:To eliminate the contamination with the ink droplet bonded to the emitting orifice surface of a recording head without damaging the emitting orifice surface of the recording head, to prevent the occurrence of the deterioration of a recording image such as a change in the density of the recording image before and after the operation of a head surface cleaning means and to always keep the stable recording due to the recording head. CONSTITUTION:A gear pump 18 for pressurizing ink to allow the ink in a nozzle to overflow to the emitting orifice surface 11 of a recording head 1 is provided on the way of the piping route of an ink supply pipe 20a. A control part 30 operates the gear pump during the recording operation of the recording head 1 to clean the emitting orifice surface 11 of the recording head 1 and subsequently supplies a current to a head heater 40 to restore the temp. of the recording head 1 to the temp. immediately before the cleaning of the surface of the recording head l detected by a thermistor 39 to resume the recording operation due to the recording head 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet for recording by ejecting ink as a recording liquid or the like from a discharge port as small droplets and causing the droplets to adhere to the recording surface of a recording material. Recording device

[0002]

2. Description of the Related Art In general, an inkjet head applied to an inkjet recording apparatus has a discharge port for recording liquid droplets,
A liquid passage for supplying a liquid to the discharge port, an energy acting portion provided in a part of the liquid passage, and an energy generating means for generating a droplet forming energy to act on the liquid in the acting portion. I have it.

The energy generating means uses an electromechanical transducer such as a piezo element, irradiates an electromagnetic wave such as a laser and absorbs it in a liquid there to generate heat.
It is known to discharge and fly droplets by the action of heat generation, or a heating element such as an electrothermal converter.

Among them, an ink jet head which has an electrothermal converter as an energy generating means and ejects droplets by thermal energy has the following advantages. a) The ejection openings for ejecting recording droplets to form flying droplets can be arranged at a high density, and a suitable configuration for performing high-resolution recording can be easily taken. . b) It is easy to make the structure compact. c) It is possible to make full use of the advantages of IC technology and micromachining technology, in which the recent technological advances in the semiconductor field and the remarkable improvement in reliability have been made for their fabrication. Shape (two-dimensional), multiple discharge ports, higher density, easier mass production,
The manufacturing cost is also low.

As an ink jet head having multiple discharge ports manufactured through a semiconductor manufacturing process using an electrothermal converter as an energy generating means, liquid paths corresponding to the respective discharge ports are provided, and each liquid path is provided. There is known a structure in which an electrothermal converter is provided, and a structure in which a liquid is supplied to each liquid passage from a common liquid chamber communicating with each liquid passage.

FIG. 8 is a diagram showing the outline of the construction of such an ink jet recording head.

This recording head 1 is used for etching, vapor deposition,
It is composed of an electrothermal converter 3, a electrode 4, a nozzle wall 5, and a top plate 6 formed on a substrate 2 through a semiconductor manufacturing process step such as sputtering.

The recording ink 12 is supplied from a liquid storage chamber (not shown) into the common liquid chamber 8 of the recording head 1 through the ink supply pipe 7. In the figure, 9 is an ink supply pipe connector. Ink 12 supplied into the common liquid chamber 8
Is supplied into the nozzle 10 by capillarity, and is stably held by forming a meniscus at the discharge port surface at the tip of the nozzle. When the electrothermal converter 3 is energized, the liquid on the surface of the electrothermal converter is heated and a bubbling phenomenon occurs, and ink energy is ejected from the ejection port surface 11 by the energy of the bubbling.

With the above-mentioned structure, the nozzle density is 1
It becomes possible to manufacture a multi-nozzle inkjet recording head of 128 nozzles or 256 nozzles with a high-density nozzle arrangement of 6 nozzles / mm.

By the way, when the recording ink is ejected and ejected using the recording head as described above to continue the recording operation, as shown in FIGS. 9A and 9B, the recording ink droplet 14 is formed. An infinite number of satellite-shaped minute ink mist (fog-like ink) 15 generated when each of the nozzles 10 of the recording head 1 discharges the recording head 1 faces the recording paper as a recording material. When the ink adheres / accumulates to the ejection port surface 11 and the adhesion amount increases, it grows into a large ink droplet 16 and spreads to the ejection port 13 of the recording head 1 to eject the ink droplet from each nozzle 10 of the recording head 1. In some cases, such problems may occur such that the recording image is obstructed or adhered to the surface of the recording paper, and the recorded image is stained.

Therefore, conventionally, in order to solve the problem caused by the minute ink mist 15 generated when the recording ink droplets 14 are ejected from the recording head 1 as described above, the vicinity of the ejection port surface 11 of the recording head 1 is solved. An air suction device is installed in
A method of sucking in the minute ink mist 15 or a rubber blade is regularly brought into contact with the ejection port surface 11 of the recording head 1 to remove the adhered ink droplets 16 generated by the adhesion and accumulation of the minute ink mist 15. Methods such as scraping off have been adopted.

[0012]

However, when the air suction device is used as in the conventional example, the device configuration becomes large, the noise is large, and the air suction device operates, so that the satellite-shaped minute Not only the suction of the ink mist 15 but also the flying state of the ink droplets 14 ejected from the ejection port is affected by the air flow, and the recording position of the recording dot on the recording paper is displaced from the original position. The problem was seen.

When a rubber blade is used to remove ink droplets adhering to the ejection port surface 11 of the recording head, the ejection port surface 11 of the recording head 1 is damaged or ejected by the rubber blade. Recording ink droplets 14 on the exit surface 11
However, there is a problem that the ejection direction of the recording ink droplets 14 from each nozzle of the recording head 1 is disturbed.

An object of the present invention is to eliminate contamination by ink droplets adhering to the ejection port surface of the recording head without damaging the ejection port surface of the recording head, and to further improve the recorded image density before and after the operation of the head surface cleaning means. An object of the present invention is to provide an ink jet recording apparatus which can prevent deterioration of a recorded image such as a change and can always maintain stable recording by a recording head.

[0015]

In order to achieve the above object, an ink jet recording apparatus of the present invention comprises head temperature detecting means for detecting the temperature of an ink jet recording head,
Head surface cleaning means for removing ink droplets adhering to the head surface by causing ink in each nozzle of the ink jet recording head to overflow to the ejection opening surface of the ink jet recording head, and recording head heating means for raising the temperature of the recording head During the recording operation by the recording head, the head surface cleaning means is operated to clean the surface of the recording head, and then the recording head heating means is operated to detect the temperature of the recording head by the head temperature detecting means. The head surface cleaning means has a control means for recovering the temperature before the head surface cleaning operation.

[0016]

According to the present invention, in addition to the head surface cleaning operation before the recording operation is started by the recording head, the head surface cleaning is performed even when the recording operation by the recording head is started and the carriage equipped with the recording head is performing the scanning operation. I am trying to do it. This makes it possible to almost completely remove the ink droplets that have adhered and accumulated on the ejection port surface of the recording head during the scanning operation of the recording head during the operation of the recording head. Moreover, since the head surface cleaning means is provided with a head surface cleaning means for causing the ink in each nozzle of the inkjet recording head to overflow to the ejection opening surface of the inkjet recording head to remove the ink droplets adhering to the head surface. Also, the ejection port surface of the recording head is not damaged.

The serial scan operation of the carriage
If the head surface cleaning operation is performed on the way, the initial head
As with the surface cleaning operation, the print head is
Temperature of the recording head
Is the print head temperature immediately before the head surface cleaning operation
T_C The head cleaning operation has ended.
Start the recording operation by the recording head immediately at the timing.
Then, recording is performed before the head cleaning operation starts and after the head cleaning operation ends.
Since a temperature difference of ΔT occurs in the temperature of the head, the recording head
The recorded image due to the recording
Steps will occur. Therefore, in the present invention,
When the head surface cleaning operation is completed, the recording head heating means
The temperature of the recording head immediately before cleaning the head surface.
Temperature T _C I am trying to recover.

According to one embodiment of the present invention, the head surface cleaning means is provided from an ink pressurizing means or a nozzle of the recording head, which is provided in the middle of the piping path of the ink supply path for supplying the recording ink to the recording head. It is composed of suction means for sucking ink.

According to one embodiment of the present invention, the recording head heating means is a heater mounted on the recording head.

According to one embodiment of the present invention, the recording head heating means is means for causing the recording head to perform an idle discharge operation. In addition to energizing the head heater mounted on the recording head, the recording head performs an idle discharge operation, and the recording head is heated by the heat generated when the recording head is driven, so the heating efficiency of the recording head can be increased. Also, the recovery time of the temperature of the recording head to the temperature immediately before the head surface cleaning operation of the recording head can be shortened.

According to one embodiment of the present invention, the recording head heating means is means for applying a pulse voltage that does not eject ink droplets to the electrothermal conversion element in each nozzle of the recording head. In this case, since the recording head is heated without ejecting ink droplets from the recording head, it is possible to heat the recording head at low cost and with high heating efficiency.

[0022]

Embodiments of the present invention will now be described with reference to the drawings.

(First Embodiment) FIG. 1 is a perspective view showing the outline of an ink jet recording apparatus according to the first embodiment of the present invention. The platen roller 23 is driven by a paper feed motor 25, conveys a recording material (not shown) such as paper, and forms / holds a recording surface. The recording material in the form of continuous paper or cut paper is conveyed while being pressed against the platen roller 23 by a pinch roller (not shown) between the recording head 1 and the platen roller 23. The recording head 1 is a carriage 21.
It is mounted on the recording medium and is serially driven along the two guide rails 24a and 24b in the S _A and S _B directions in the figure, and recording is performed on the recording material in the process. The carriage 21 is connected to the shaft 27 of the carriage motor 26 via a belt 29 and a pulley 28a provided between the pulleys 28a and 28b, and is driven in the S _A and S _B directions according to the rotation of the carriage motor 26. Is done.

The recording head 1 is, for example, yellow (Y),
It has four recording units corresponding to four colors of magenta (M), cyan (C), and black (B). The recording units for recording Y, M, C, and B have gear pumps 18Y, 1
Supply pipe with 8M, 18C and 18B
Ink tanks 19Y, 19M, 19C and 19B through 20aY, 20aM, 20aC and 20aB
Ink is supplied from. In addition, these units are connected to the corresponding ink tanks through pipes that do not have a gear pump in the middle. Note that, in FIG. 1, only these pipes 20bY for supplying yellow ink are shown for simplification. At the home position HP of the recording head 1, there is provided capping means 22 that faces the ejection portion of the recording head 1 and moves in the f direction so as to be joined to the recording head 1.

FIG. 2 is a schematic diagram for explaining the configuration of the ink jet recording apparatus of FIG. 1 in more detail. The ink in the nozzles of the recording head 1 is discharged from the ejection port surface 1 of the recording head 1.
As the head surface cleaning means 17 that causes the ink to overflow to 1, the gear pump 18 that is a pressurizing means that pressurizes the ink is provided in the middle of the piping path of the ink supply pipe 20a. Further, in this embodiment, the ejection port surface 11 of the recording head 1
The attached ink droplets that have adhered to and accumulated on the discharge surface 1
In order to more reliably discharge the recording ink droplets from each nozzle of the recording head 1, the head surface cleaning operation is performed before the recording operation of the recording head 1 is started. The head surface cleaning operation is performed even when the carriage 21 carrying the recording head 1 is being started and is performing a scanning operation. Then, before the recording operation by the recording head 1 is started, the gear pump 18, which is a pressurizing means as a head surface cleaning means, is driven by a signal from the control unit 30 connected to the console 31 to remove the ink in the ink supply pipe 20a. Applied pressure P
By pressurizing with, the ink is pushed out from each nozzle of the recording head 1, and the ink overflowing on the ejection port surface 11 flows out on the ejection port surface 11 of the recording head 1 and the ink amount Q ₁ is larger than the ink amount Q _T. Overflow the ink of
After the adhered ink droplets adhered / accumulated on the ejection port surface 11 have been taken into the overflowed ink, the control unit 30
In response to the signal from, the carrier 32 of the capping means 22 is moved so that the ink absorber 34 provided in the capping means 22 contacts the recording head 1, and then the compressed air from the air pump 37 is blown by the air blowing means 36. The air is blown from the air blowing hole 35 provided in the recording head 1 toward the ejection port surface 11 of the recording head 1, and the ink overflowing onto the ejection port surface 11 of the recording head 1 is blown off and absorbed by the ink absorber 34. As a result, the adhered ink droplets that have adhered and accumulated on the ejection port surface 11 of the recording head 1 can be almost completely removed before the recording operation by the recording head 1 is started.

Then, the recording operation by the recording head 1 is further started, and the carriage 21 having the recording head 1 mounted thereon.
Even when the recording head 1 ejects the recording ink droplets while performing the scanning operation, the satellite-like minute ink mist adheres to and accumulates on the ejection port surface 11 of the recording head 1. Even during the scanning operation by the control unit 30, the capping unit 22 is brought into contact with the recording head 1 at a preset timing from the control unit 30, and the gear pump 18, which is the pressurizing unit as the head surface cleaning unit, is activated by a signal from the control unit 30. It is driven to press the ink in the ink supply pipe 20a with a pressing force P to push out the ink from each nozzle of the recording head 1
1, the overflowing ink is discharged onto the ejection port surface 1 of the recording head 1.
1 Ink amount Q that is greater than the ink amount Q _T flowing down
The ink of ₁ overflows and adheres to the ejection port surface 11.
After the accumulated ink droplets have been taken into the overflowed ink, compressed air from the air pump 37 is blown from the air blowing hole 35 provided in the air blowing means 36 to the ejection port surface 11 of the recording head 1. By injecting the ink toward the ejection opening surface 11 of the recording head 1 to blow it off and cause it to be absorbed by the ink absorber 34,
It is also possible to almost completely remove the adhered ink droplets that have adhered and accumulated on the ejection port surface 11 of the recording head 1 during the scanning operation of the recording head 1 during the recording operation of the recording head 1.

FIG. 3 is a model diagram for explaining the cleaning state of the ejection port surface 11 of the recording head 1 according to this embodiment.
In FIG. 3A, the adhered ink droplets 16 formed by adhering and accumulating minute ink mist on the ejection port surface 11 of the recording head 1 adhere to the entire ejection port surface 11, and a part of the ink droplet 16 forms the nozzle 10.
2 shows a state in which the recording head 1 has deteriorated to cover a part of the discharge port 13 and normal recording ink droplets cannot be discharged from the recording head 1. FIG. 3B shows a gear pump 1 which is an ink pressurizing means as a head surface cleaning means.
8 shows a state in which the ink 8 is driven to eject ink from each nozzle of the recording head 1 and the ink 12 overflows onto the ejection port surface 11. In FIG. 3C, the adhered and accumulated adhering ink droplets 16 are removed from the ejection port surface 11 and
It shows the state after cleaning the. As in this example,
The ink supply pipe 20 is provided by a pressurizing means such as a gear pump.
The ink in a is pressed to push out the ink from each nozzle of the recording head 1 and overflow onto the ejection port surface 11 of the recording head 1 to take in the adhered ink droplets 16 adhered / accumulated on the ejection port surface 11. After that, the air pump 37 is driven to clean the ink droplets remaining on the ejection port surface 11 of the recording head 1 without mechanically damaging the ejection port surface 11 of the recording head 1. The discharge port surface 11 can be effectively cleaned.

FIG. 4 shows the ejection port surface of the recording head 1 of this embodiment.
11 shows the cleaning operation of 11 and the temperature change of the recording head 1.
It is a timing chart. Timing t₀ Recording equipment
After the power is turned on, the signal from the control unit 30
To the head heater 40 mounted on the recording head 1.
When the energization is started and the recording head 1 is at the temperature T₀ Heated from
It And the head temperature detection mounted on the recording head 1
The recording head is transmitted by a signal from the thermistor 39 as a means.
The temperature of the recording head that is set in advance
Degree T_S If it exceeds, the signal from the control unit 30
Ng t₁ Energization to the head heater 40 is stopped at
The recording head 1 is in a standby state. After that, timing t
₂ Then, the recording operation is started by the signal from the control unit 30,
Timing t₃ Then, before the recording operation by the recording head 1 starts
The gear pump 18 is driven by a signal from the control unit 30.
Then, the initial head surface cleaning operation is performed. And
At this time, the recording head 1 is pressurized by the gear pump 18.
The ink is cooled by the ink
Degree is the set temperature T_S Control unit
The signal from 30 causes the head heater 40 to be energized.
Will be started again. After that, timing t_Four With gear pump
18 is stopped and timing t_Five Recording head 1
Is the recording head set temperature T_S Head heating above
The power supply to the heater 40 is stopped, and the timing t₆ Recorded by
The recording operation by the head 1 is started. And to the record
S of the carriage 21 carrying the head 1_A , S_B To the direction
Serial scan drive operation is repeatedly performed to record
When the recording operation by the head 1 is continuously performed, recording is performed.
For heat generation of driver IC etc. mounted on the head 1
Therefore, the temperature of the recording head 1 is the set temperature T_S A little more than
Temperature T_C (T_C > T _S ) And then beforehand
When the set number of serial scan drive operations is reached,
The signal from the control unit 30 causes the carriage 21 to be serialized.
The le scan drive operation is stopped, and the recording head 1
The recording operation is suspended, and the timing t₇ And the control unit 30
The gear pump 18 is driven by the signal from the
The surface cleaning operation is performed, and the timing t₈ With gear pump 1
8 is stopped, then S of the carriage 21_A Direction
The serial scan operation of the
The recording operation is restarted.

When the gear pump 18 pressurizes the ink in order to perform the head surface cleaning operation during the serial scanning operation of the carriage 21, the recording head 1 is operated as in the initial head surface cleaning operation. Since the pressure of the ink cools the recording head 1, the temperature of the recording head 1 becomes lower than the recording head temperature T _C immediately before the head surface cleaning operation, and immediately after the timing t ₈ when the head cleaning operation ends. When the recording operation by the recording head 1 is started, a temperature difference ΔT occurs in the temperature of the recording head 1 before the head cleaning operation is started and after the head cleaning operation is completed.
A recording density step corresponding to T occurs. Therefore,
In the present embodiment, as the head surface cleaning operation is performed at the timing t ₇ , ink is applied to the gear pump 18, and at the same time, the head heating heater 40 is energized, and the recording head 1 of the recording head 1 during the ink press operation by the gear pump 18 is performed. I try to reduce the temperature drop. That is, the control unit 3
From the signal from 0, at the timing t ₇ , the temperature T _C of the recording head 1 immediately before driving the gear pump 18 to perform the head surface cleaning operation is detected by the thermistor 39 mounted on the recording head 1, and this recording is performed. Head temperature T _C
The value of is stored in a memory unit composed of a RAM (not shown), the head surface cleaning operation is completed, and the recording head 1 is heated by the head heating heater 40 at the timing t ₈ and the temperature of the recording head 1 is increased. Head heater 40 until the temperature reaches T _C just before the head surface cleaning operation is performed.
Is energized, and the recording operation by the recording head 1 is restarted at the timing t ₉ when the recording head temperature becomes the same before and after the head surface cleaning operation.
Then, as in the present embodiment, the ink is pressed before the recording operation by the recording head 1 is started and during the serial scan driving operation by the recording head 1 to adhere and accumulate on the ejection port surface 11 of the recording head 1. A head surface cleaning operation for removing drops is performed, and when the ink is pressed, the recording head 1
By driving the head heater 40 mounted above to recover the lowered temperature of the recording head 1 to the temperature T _C before the head surface cleaning operation, the ejection port surface 11 of the recording head 1 is not damaged. , Ejection port surface 1 of recording head 1
(1) To prevent contamination by ink droplets adhering to No. 1 and to prevent deterioration of recorded image such as change in recorded image density before and after head surface cleaning operation so that stable recording by the recording head 1 can always be maintained. You can

Incidentally, the head heater 40 is energized in order to more quickly recover the decrease in the recording head temperature caused by the pressurized ink when the gear pump 18 which is the ink pressurizing means is driven as the head surface cleaning operation. A plurality of voltage setting modes are provided for the voltage to be applied to select a set voltage mode in which the voltage applied to the head heater 40 during the head surface cleaning operation is higher than that during the normal image recording operation. A head heating motor is provided to control the operation of the plurality of head heating heaters during the normal image recording operation and the head surface cleaning operation, and the plurality of head heating heaters are driven during the head surface cleaning operation to heat the recording head 1. If so controlled to increase the amount from the time the head surface cleaning operation at the timing t _7, the temperature of the recording head 1 is To a temperature T _C of the front head surface cleaning operation it becomes possible to greatly shorten the time Δt until the recovery.

FIG. 5 shows the ink jet recording apparatus of this embodiment.
3 is a flowchart showing a control flow of the above. Recording device
After the power is turned on, the recording head 1 has the capping means.
Recorded after being capped at 22 (step 101)
The head heater 40 mounted on the head 1 is energized.
It is started (step 102). And on the recording head 1
Recorded by the output signal from the thermistor 39 mounted on
Head 1 temperature T_H Is the recording head set temperature T_S Reached
Whether or not it is determined by a signal from the control unit 30 (step
103), the temperature T of the recording head 1_H Has a recording head
Constant temperature T_S Is reached, the head heater 40 is connected.
Power is stopped (step 104) and then the recording head
Whether the recording is started or not for 1 is transmitted from the control unit 30.
It is judged according to the number (step 105), and is recorded.
If the recording head 1 starts the recording operation,
As a head surface cleaning operation during
Gear pump 18 is driven for a preset time
Then, the ink in the ink supply pipe 20a is printed by the recording head.
1 of the recording head 1 is spilled over the ejection surface 11 of the recording head 1.
Removal of adhered ink droplets that have adhered and accumulated on the exit surface 11
Is performed (step 106). And recording head 1
The energization to the head heating heater 40 mounted on the above is reopened.
Then, the heating operation of the recording head 1 is performed (step
107). After that, the air pump 37 is driven to record.
Cleaning of the ink droplets remaining on the ejection port surface 11 of the head 1
Sweep is performed (step 108), and the temperature of the recording head 1
T_H Is the recording head set temperature T_S Control whether or not
It is judged by the signal from the unit 30 (step 109),
Temperature T of recording head 1_H Is the recording head set temperature T_S Reached
If so, the power supply to the head heater 40 is stopped.
(Step 110). After that, the capping means 22
After the release (step 111), the recording head 1
The recording operation is started and the carrier equipped with the recording head 1
S of 21_A , S_B Direction serial scan drive operation
The image is recorded on the recording paper by (step 1
12). And the image recording by the recording head 1
Whether the set number of serial scan drive times has been reached
Is determined by a signal from the control unit 30 (step 1
13) If the set number of times has not been reached, the recording head 1
The image recording is continuously performed by (step 12).
2). Also, the number of serial scans reaches the set number,
It is determined that the head surface cleaning operation of the recording head 1 is performed.
When the recording head 1 is mounted, the thermistor 39 mounted on the recording head 1
By the temperature T of the recording head 1_C Finds the value of
The data is stored in the memory unit (step 114). And
Ridge 21 S_A , S_B Direction serial scan drive
After the operation is stopped (step 115), the recording head 1
Are capped by the capping means 22 (step
116), as a head surface cleaning operation, pressurizing ink
When the gear pump 18 as a means is preset
The ink in the ink supply pipe 20a is driven for a while.
It overflows to the ejection port surface 11 of the recording head 1 (step
117), energization of the head heater 40 is started,
The recording head 1 is heated (step 118).
After that, the air pump 37 is driven to eject the recording head 1.
After cleaning the ink droplets on the exit surface 11,
Temperature T of head 1_H Is the head surface cleaning operation of the recording head 1.
T just before_C Whether the control unit 30 has reached
It is judged by the signal from (step 120) and recorded
Temperature T of head 1 _H Is the head surface cleaning operation of the recording head 1.
T just before_C The head heating heater
Power to the computer 40 is stopped (step 121), and
Image recording by the head 1 is restarted (step 12).
2). Then, it is judged whether or not the image recording is completed.
(Step 123) If the recording is completed,
Head 1 is capped again and enters the standby state (step
124).

(Second Embodiment) FIG. 6 is a timing chart for explaining an ink jet recording apparatus according to the second embodiment of the present invention. In this embodiment, the gear pump 18 which is an ink pressurizing means as a head surface cleaning means.
Is driven to pressurize the ink in the ink supply pipe 20a, push out the ink from each nozzle of the recording head 1, and cause the ink to overflow onto the ejection port surface 11 to adhere to the ejection port surface 11. Discharge port surface 11 for removing drops
In order to recover the temperature drop of the print head temperature that occurs during the ink pressurizing operation, the gear pump 18 is driven and then the print head 1 is driven, and the heat generated when the print head is driven causes the print head to drive. The temperature of the recording head 1 itself is raised to the temperature T _C just before the head surface cleaning operation of the recording head 1.

That is, as shown in FIG. 6, the recording head 1
Carriage 21 equipped with S_A , S_B Serial to direction
Scan drive operation is performed at timing t₁ Carry on
The 21 S_A Serial scan of the Nth scan in the direction
Drive starts and the carriage 21 scans at a constant speed.
Timing t after the operation state₂ With recording head
Image recording by 1 is started. And timing t₃ 
Image recording by the recording head 1 in the Nth scan
Ends, timing t_Four S of carriage 21_A 
The scanning operation in the direction is stopped and the paper feed motor 25
The recording paper is conveyed by the image recording width of the recording head 1.
Timing t_Five And carriage 21 is S_B Direction to
Clock scan drive is started, and timing t₆ Carry on
S of 21_B Backscan drive in the direction is stopped
Then, the recording operation of the Nth scan is completed. And this
When the recording operation of the Nth scan of
The head surface cleaning operation of the recording head 1 is performed by these signals.
Done. That is, the timing t₆ In the carriage 21
Of S_B After the back scan operation in the direction
Tie before the (N + 1) th scan by the ridge 21 starts.
Ming t₇ The recording head 1 is provided with the capping means 22.
Is capped, timing t₈ With ink pressurizing means
Gear pump 18 as time T_P Just driven and recorded
Ink droplets that have adhered and accumulated on the ejection port surface 11 of the head 1.
Of the head heating heater 40 at this time.
Energization is also started. And timing t₉ In the air
Pump 37 is time T_A Ejection of the recording head 1 driven only
Cleaning of ink drops remaining on the mouth surface 11 was performed.
After, timing t_TenThe recording head 1 is driven by the
The idle discharge operation by the pad 1 is started. And head
Recording by the heater 40 and the idle discharge operation of the recording head 1.
The recording head temperature T due to the heating operation to the head 1_HRises
Then, the output from the thermistor 39 mounted on the recording head 1
Print head temperature T by force signal_H Is the head of the recording head 1.
Temperature T immediately before the surface cleaning operation_C It was decided that
When it is disconnected, the signal from the control unit 30 causes the timing t
₁₁Drive of the head heater 40 and the recording head 1
The idle discharge operation is stopped, and the timing t₁₂Capping with
After the capping by means 22 is released,
G t ₁₃Then again S of the carriage 21_A Direction N + 1th direction
The serial scan operation of the scan eye is restarted and the timing
G t₁₄Image recording by the recording head 1 is started at
Image recording operation continues in the same sequence
Be done.

Then, as in this embodiment, the recording head 1
When the performing of the head surface cleaning operation, in order to restore the temperature drop of the recording head temperature T _H occurring at the ink pressurizing operation, the head heater 4 mounted on the recording head 1
In addition to the energization to 0, the recording head 1 performs an idle discharge operation and heats the recording head 1 by the heat generated when the recording head is driven, whereby the heating efficiency of the recording head 1 can be increased, and the recording head temperature T The recovery time to the temperature T _C immediately before the head surface cleaning operation of the _H recording head 1 can be further shortened.

(Third Embodiment) FIG. 7 is a model diagram for explaining an ink jet recording apparatus according to a third embodiment of the present invention. In this embodiment, the gear pump 18, which is an ink pressurizing unit as a head surface cleaning unit, is driven to pressurize the ink in the ink supply pipe 20a, and the ink is pushed out from each nozzle of the recording head 1 to form the ejection port surface 11. The recording head temperature T generated during the ink pressurizing operation is performed by performing the cleaning operation of the ejection opening surface 11 by removing the attached ink droplets adhering on the ejection opening surface 11 by making the ink overflow.
_In order to recover the temperature decrease of _H , after driving the gear pump 18, a drive pulse voltage that does not cause ink droplets to be ejected is applied to the recording head 1 so that the electrothermal conversion element in each nozzle of the recording head 1 generates the pulse. The temperature of the recording head 1 itself and the temperature T _C immediately before the head surface cleaning operation of the recording head 1 are raised by the heat generated by the heat.

That is, as shown in the second embodiment, when the recording head 1 is driven to perform the idle discharge operation of ink droplets in order to raise the temperature of the recording head 1, actual image recording is performed. In addition to this, the amount of ink consumed becomes large and the cost becomes high. Therefore, in the present embodiment, the pulse width of the pulse voltage V _{H that} is applied to the electrothermal conversion element in each nozzle of the recording head 1 is increased. The pulse width P that is longer than the critical pulse width P _th at which ink can be ejected during normal image recording
₂ is set, and when the recording head is heated during the head surface cleaning operation, by _supplying a pulse voltage having a pulse width P ₁ shorter than the critical pulse width P _{th at} which ink can be ejected, the ink droplets are ejected from the recording head 1. Recording head 1 without ejecting
It is possible to heat the recording head 1 at low cost and with high heating efficiency.

Further, regarding the case where the pressurizing means is provided in the middle of the piping path of the ink supply pipe 20a for supplying the ink to the recording head 1 in order to overflow the ink to the ejection port surface 11 of the recording head 1 so far. As described above, in order to cause the ink to overflow from the nozzles of the recording head 1 onto the ejection port surface 11, for example, a cap member is brought into contact with the ejection port surface 11 of the recording head 1 to eject the ejection port of the recording head 1. The effect of the present invention is also effective in the case of a structure in which the air in the space enclosed by the surface 11 and the cap member is sucked by a suction means such as a pump.

The present invention brings excellent effects particularly in an ink jet type recording head and a recording apparatus for recording by forming flying droplets by utilizing thermal energy among the ink jet recording systems.

Regarding the typical structure and principle thereof, see, for example, US Pat. Nos. 4,723,129 and 4740.
What is done using the basic principles disclosed in 796 is preferred. This method can be applied to both the so-called on-demand type and continuous type, but especially in the case of the on-demand type, liquid (ink)
By applying at least one drive signal to the electrothermal converter arranged corresponding to the sheet or liquid path in which is stored, which corresponds to the recorded information and causes a rapid temperature rise exceeding nucleate boiling. , It is effective because it generates heat energy in the electrothermal converter and causes film boiling on the heat-acting surface of the recording head, resulting in the formation of bubbles in the liquid (ink) corresponding to this drive signal on a one-to-one basis. Is. The liquid (ink) is ejected through the ejection openings by the growth and contraction of the bubbles to form at least one droplet. It is more preferable to make this drive signal into a pulse shape because bubbles can be immediately and appropriately grown and contracted, so that liquid (ink) ejection with excellent responsiveness can be achieved.

As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. If the conditions described in US Pat. No. 4,313,124 of the invention relating to the rate of temperature rise on the heat acting surface are adopted, further excellent recording can be performed.

As the constitution of the recording head, in addition to the combination constitution of the ejection port, the liquid passage, and the electrothermal converter (the linear liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned respective specifications. The present invention also includes configurations using US Pat. No. 4,558,333 and US Pat. No. 4,459,600, which disclose a configuration in which a heat acting portion is arranged in a bending region.

In addition, Japanese Laid-Open Patent Publication No. 59-123670 discloses a structure in which a common slit is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters, and a pressure wave of thermal energy is absorbed. The present invention is also effective as a configuration based on Japanese Patent Application Laid-Open No. 59-138461, which discloses a configuration in which an opening corresponds to a discharge portion.

Further, as a full line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, the length can be increased by combining a plurality of recording heads as disclosed in the above-mentioned specification. The present invention can exert the above-mentioned effects more effectively, although it may have a configuration that satisfies the above requirement or a configuration as one recording head integrally formed.

In addition, by being attached to the apparatus main body, it can be electrically connected to the apparatus main body and can be supplied with ink from the apparatus main body by a replaceable chip type recording head or the recording head itself. The present invention is also effective when a cartridge-type recording head provided with an ink tank is used.

Further, it is preferable to add recovery means for the recording head, preliminary auxiliary means, etc., which are provided as a configuration of the recording apparatus of the present invention, because the effects of the present invention can be further stabilized. If you list these specifically,
Capping means, cleaning means, pressurizing or sucking means for the recording head, preheating means using an electrothermal converter or another heating element or a combination thereof, and a preliminary ejection mode for performing ejection other than recording It is also effective to perform stable recording.

Further, as the recording mode of the recording apparatus, not only the mainstream color such as black is recorded but also the recording head may be integrally formed or a plurality of them may be combined. The present invention is also extremely effective for a device provided with at least one of full colors by color mixing.

In the embodiments described above, the ink is described as a liquid, but it is an ink that solidifies at room temperature or lower and that softens at room temperature, or is a liquid, or the above-mentioned ink jet system. In general, the temperature of the ink itself is adjusted within the range of 30 ° C. or higher and 70 ° C. or lower to control the temperature of the ink so that the viscosity of the ink is within the stable ejection range. Anything can be used.

In addition, the temperature rise due to the thermal energy is positively prevented by using it as the energy for changing the state of the ink from the solid state to the liquid state, or the ink is solidified in a standing state for the purpose of preventing evaporation of the ink. In some cases, such as ink that is liquefied by applying heat energy according to a recording signal and ejected as a liquid ink, or one that has already started to solidify when it reaches a recording medium. The use of an ink having a property of being liquefied only by heat energy is also applicable to the present invention. In such a case, the ink is disclosed in JP-A-54-5684.
No. 7 or JP-A-60-71260, a mode in which the porous sheet is opposed to the electrothermal converter in the state of being held as a liquid or solid in the recess or through hole of the porous sheet. May be In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, as a form of the recording apparatus according to the present invention, in addition to a recording apparatus integrally or separately provided as an image output terminal of information processing equipment such as a word processor or a computer, a copying apparatus combined with a reader or the like is further provided. May take the form of a facsimile machine having a transmission / reception function.

[0050]

As described above, according to the present invention, the ink in each nozzle of the ink jet recording head is made to overflow to the ejection opening surface of the ink jet recording head to remove the ink droplets adhering to the head surface. Means is provided, the head surface cleaning means is operated during the recording operation by the recording head to clean the surface of the recording head, and then the recording head heating means is operated to adjust the temperature of the recording head to the head surface by the head surface cleaning means. By recovering the temperature before the cleaning operation, the contamination of ink droplets adhering to the ejection port surface of the recording head is eliminated without damaging the ejection port surface of the recording head, and recording before and after the operation of the head surface cleaning means is performed. It is possible to prevent deterioration of a recorded image such as a change in image density and to always maintain stable recording by the recording head.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an inkjet recording apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing in detail the configuration of the inkjet recording apparatus of FIG.

FIG. 3 is a diagram for explaining a cleaning state of the ejection port surface 11 of the recording head 1 in the first embodiment.

FIG. 4 is a timing chart showing the cleaning operation of the ejection port surface 11 of the recording head 1 and the temperature change of the recording head 1 in the first embodiment.

FIG. 5 is a flowchart showing a control flow in the first embodiment.

FIG. 6 is a timing chart for explaining the ink jet recording apparatus according to the second embodiment of the present invention.

FIG. 7 is a timing chart for explaining an ink jet recording apparatus according to a third embodiment of the present invention.

FIG. 8 is a schematic configuration diagram of an inkjet recording head using an electrothermal converter.

FIG. 9 is a diagram showing a problem caused by minute ink mist generated from each nozzle of the inkjet recording head.

[Explanation of symbols]

1 Recording Head 2 Substrate 3 Electrothermal Converter 4 Electrode 5 Nozzle Wall 6 Top Plate 7 Ink Supply Pipe 8 Common Liquid Chamber 9 Connector 10 Nozzle 11 Discharge Port Surface 12 Ink 13 Discharge Port 14 Recording Ink Droplet 15 Micro Ink Mist 16 Adhesive Ink Drop 17 Head surface cleaning means 18, 18Y, 18M, 18C, 18B Gear pump 19, 19Y, 19M, 19C, 19B Ink tank 20a, 20aY, 20aM, 20aC, 20aB
Ink supply pipe 21 Carriage 22 Capping means 23 Platen roller 24a, 24b Rail 25 Paper feed motor 26 Carriage motor 27 Shaft 28a, 28b Pulley 29 Belt 30 Control section 31 Console 32 Transport section 33 Ink cartridge 34 Ink absorber 35 Air blowing hole 36 Air Spraying Means 37 Air Pump 38 Ink Pressurizing Means 39 Thermistor 40 Head Heating Heater 101-124 Steps

Claims (8)

[Claims] 1. An ink jet recording apparatus for ejecting and ejecting ink droplets from a fine opening as small droplets and adhering the droplets onto recording paper to perform recording. Head temperature detection for detecting the temperature of an inkjet recording head. Means, a head surface cleaning means for removing the ink droplets adhering to the head surface by causing the ink in each nozzle of the ink jet recording head to overflow to the ejection opening surface of the ink jet recording head, and recording for increasing the temperature of the recording head Head heating means and the head surface cleaning means is operated during the recording operation by the recording head to clean the surface of the recording head, and then the recording head heating means is operated to detect the temperature of the recording head by the head temperature detection means. Recovering to the temperature detected by the head surface cleaning means before the head surface cleaning operation. An ink jet recording apparatus characterized by having a control means. 2. The ink jet recording according to claim 1, wherein the control unit controls the recording head to restart the recording operation after the temperature of the recording head recovers to the temperature before the head surface cleaning operation. apparatus. 3. The head surface cleaning means comprises an ink pressurizing means or a suction means for sucking ink from a nozzle of the recording head, which is provided in an ink supply path for supplying recording ink to the recording head. The inkjet recording apparatus according to claim 1 or 2. 4. The recording head heating means is a head heating heater mounted on the recording head.
7. The inkjet recording device according to any one of 1. 5. The ink jet recording apparatus according to claim 1, wherein the recording head heating unit is a unit that causes the recording head to perform an idle discharge operation. 6. The ink jet recording apparatus according to claim 1, wherein the recording head heating unit is a unit that applies a pulse voltage that does not eject ink droplets to the electrothermal conversion element in each nozzle of the recording head. Recording device. 7. The inkjet recording apparatus according to claim 1, further comprising an electrothermal converter for generating thermal energy for ejecting ink. 8. The ink jet recording apparatus according to claim 7, wherein ink is ejected from an ejection port by utilizing film boiling generated in the ink by energy applied by the electrothermal converter.