JPH04255361A - Ink jet recording apparatus - Google Patents

Abstract

PURPOSE:To reduce the consumption amount of ink accompanied by emission recovery processing by mounting a recovery control means controlling the emission recovery processing due to an emission recovery means corresponding to the combination of respective times when a plurality of states clocked by a clocking means continue. CONSTITUTION:In emission recovery processing, a non-suction time, a thickening time and a no-cap time are set and, corresponding to these times, the mode of recovery processing is changed and these times are controlled by a timer. The non-suction time is the elapse time after final suction and the thickening time is the elapse time after final empty emission and the no-cap time is the elapse time after the release of capping. In recovery processing, the surfaces of the emitting orifices of the recording head of a cartridge IJC are capped by a cap unit 8300 and negative pressure is generated by a pump 8500 and the air bubble or thickened ink in the recording head is sucked to be discharged from the emitting orifices. After sucking operation, the surfaces of the emitting orifices are wipen by a blade 804 and empty emission is carried out to discharge pushed-in matter.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus, and more particularly to an ejection recovery process for ensuring good ink ejection by a recording head of the apparatus.

0002

[Prior Art] In an inkjet recording device, if the device is left unused for a long period of time without printing, the viscosity of the ink increases due to evaporation of ink moisture mainly through the ejection ports of the recording head, and the ink supply increases. Relatively large bubbles may be generated in the ink due to air entrainment in the system or growth of fine bubbles that were originally in the ink. If such an increase in ink viscosity or generation of bubbles occurs in the ink in the ink path communicating with the ejection port of the print head, the ejection in the print head may not be performed properly, and as a result, printing may not be possible. This will impair the image quality and quality of images, etc. The generation of bubbles and increase in ink viscosity are not only caused by not printing for a long time, but also when recording with a high printing duty, for example.
A large number of microbubbles are generated as a result of ejection, and these may aggregate to form relatively large bubbles.Also, depending on the recorded data, there may be some ejection ports that hardly eject. In this case, the viscosity of the ink may be relatively high at such an ejection port.

[0003] In order to deal with the increase in ink viscosity and the generation of bubbles in the recording head as described above, conventional inkjet recording apparatuses have a method of suctioning the ink inside the recording head when the power is turned on, or stopping the recording. Ejection recovery processing is performed to refresh the ink in the print head by pressurizing the ink in the print head to discharge thickened ink and air bubbles. Furthermore, during printing, ejection recovery processing such as so-called dry ejection may be performed depending on the printing time, printing duty, and the like.

0004

[Problems to be Solved by the Invention] However, in the conventional ejection recovery process as described above, ink is simply discharged by suction or pressurization in response to turning on the power, and therefore, the ink is discharged relatively frequently. If the power is repeatedly turned on and off, an ejection recovery process that is not necessarily necessary may be performed. For example, when the printing apparatus is turned on not long after the previous power was turned off, the viscosity and air bubbles in the print head are at a level that does not affect ejection. Ejection recovery processing may be performed. In such a case, unnecessary ink is consumed for the ejection recovery process, resulting in an increase in the running cost of the printing apparatus.

The present invention has been made based on the above-mentioned viewpoint, and can indicate the degree of viscosity increase or bubbles in the ink in the recording head, such as non-ejection time or time when the ejection ports are not capped. By measuring the time during which a predetermined state continues in the device for each of a plurality of predetermined states and controlling the ejection recovery processing based on the plurality of measured times, the ejection recovery processing is performed in a timely manner. Accordingly, it is an object of the present invention to provide an inkjet recording apparatus that reduces ink consumption associated with ejection recovery processing.

[0006]

[Means for Solving the Problems] To this end, in the present invention,
In an inkjet recording apparatus that performs recording by discharging ink, a recording head for discharging ink, a discharge recovery means for performing discharge recovery processing of the recording head, and a device that affects the ink discharge of the recording head. The ejection recovery process is performed by the ejection recovery means in accordance with the combination of a timer for measuring each time during which a plurality of states continue in the inkjet recording device, and each time during which the plurality of states continue as measured by the timer. The invention is characterized by comprising a recovery control means for controlling.

[0007]

[Operation] According to the above configuration, multiple states continue, such as the time since the last discharge was performed in the recording head, the time since the last suction was performed, and the time when capping was not performed. The suction amount, the number of empty ejections, etc. in the ejection recovery process are controlled according to each time.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic perspective view of an inkjet recording apparatus according to an embodiment of the present invention. This device is a full-color serial type printer equipped with replaceable ink tank-integrated recording head cartridges for each of the four colors of ink: black (Bk), cyan (C), magenta (M), and yellow (Y). This is used as a recording section of a full-color copying machine, as will be described later with reference to FIG. The head used in this printer has a resolution of 400 dpi, a driving frequency of 4 KHz, and 128 ejection ports.

In FIG. 1, IJC is Y, M, C, Bk
There are four print head cartridges corresponding to each type of ink, and the print head and an ink tank storing ink to supply ink to the print head are integrally formed. Each recording head cartridge IJC is detachably attached to the carriage by a structure not shown. carriage 82
is slidably engaged along the guide shaft 811, and
Drive belt 85 moved by a main scanning motor (not shown)
Connect with part of 2. This allows the recording head cartridge IJC to move for scanning along the guide shaft 811. 815, 816 and 817, 818 are conveyance rollers extending substantially parallel to the guide shaft 811 on the back side and the front side in the figure of the recording area scanned by the recording head cartridge IJC. Conveyance rollers 815, 8
16, 817, and 818 are driven by a sub-scanning motor (not shown) to convey the recording medium P. The transported recording medium P forms a recording surface that faces the surface on which the ejection port surface of the recording head cartridge IJC is disposed.

A recovery system unit is provided facing a movable area of the cartridge IJC adjacent to the recording area by the recording head cartridge IJC. This recovery system unit is used when performing idle ejection or ink suction processing according to the present invention. In the recovery system unit, 8300 is a cap unit provided corresponding to a plurality of cartridges IJC each having a recording head, and can slide in the left and right directions in the figure as the carriage 82 moves, and can also move up and down in the vertical direction. It is possible. When the carriage 82 is at the home position, it is joined to the recording head section and capped. Further, in the recovery system unit, 8401 is a blade serving as a wiping member. Furthermore, 8500 is a pump unit for sucking ink, etc. from the ejection opening of the print head and its vicinity via the cap unit 8300. With the cap unit 8300 capped on the print head, the cap unit 8300 suppresses the evaporation of ink moisture and prevents ink viscosity when ejecting ink into the cap unit 8300 (so-called idle ejection) or during non-printing by capping. used for

FIG. 2 shows an example of the configuration of a head cartridge that can be mounted on the carriage of the ink jet recording apparatus shown in FIG. The cartridge according to this example integrally includes an ink tank unit IT and a head unit IJU, and these can be attached to and detached from each other. A wiring connector 102 for receiving signals for driving the ink ejection section 101 of the head unit IJU and outputting a remaining ink level detection signal is provided in a position parallel to the head unit IJU and the ink tank unit IT. . Therefore, in the posture taken when this cartridge is loaded into a carriage, which will be described later, the height H can be reduced, and the thickness of the cartridge can be reduced. This allows the carriage to be made smaller when the cartridges are arranged side by side as described above with reference to FIG. When installing the head cartridge to the carriage, please attach the discharge part 1
The ink tank unit IT can be placed on the carriage by grasping the knob 201 provided on the ink tank unit IT with 01 facing downward. This knob 201 engages with a lever provided on the carriage, which will be described later, for performing a cartridge mounting operation. When the head unit IJU is attached, a pin provided on the carriage side engages with a pin engaging portion 103 of the head unit IJU, and the head unit IJU is positioned.

In the head cartridge according to this example, an absorber 104 is juxtaposed to the ink ejection section 101 for cleaning a member that wipes the surface of the ink ejection section 101 to clean it. Further, an atmosphere communication port 203 through which air is introduced as ink is consumed is provided approximately at the center of the ink tank unit IT.

FIG. 3 is an exploded perspective view of the head cartridge shown in FIG. 2. The head cartridge according to this example is
It consists of a head unit IJU and an ink tank unit IT, and the detailed configuration of these units is as follows.
This will be explained using this figure and the like.

Head unit The standard for mounting the components of the head unit IJU is a base plate 111 made of Al or the like, on which a group of elements for generating energy used for ink ejection is formed. A printed circuit board (PCB) 1 having a substrate 112 and wiring etc. for supplying power to the elements.
15 are mounted, and these are connected by wire bonding or the like. As the element, the substrate 112 is provided with an electrothermal conversion element that generates thermal energy that causes film boiling in the ink in response to energization. In the following, this substrate 112 will be referred to as a heater board.

The wiring connector 102 described above is connected to the PCB 11.
A drive signal from a control circuit (not shown) is received by the wiring connector 102 and connected to the PCB 115.
is supplied to the heater board 112 via. PCB11
5 is a double-sided wiring board in this example, and further contains information specific to the head, such as appropriate driving conditions for the electrothermal transducer, I
ROM-format IC 128 and capacitor 12 that store D number, ink color information, drive condition correction data (head shading (HS) data), PWM control conditions, etc.
9 are arranged.

As shown in the figure, the IC 128 and the capacitor 129 are placed on the side of the PCB 115 that is connected to the base plate 111 and in the notch 11 of the base plate 111.
It is placed at a position corresponding to 1A. by this,
If the height of the IC etc. when mounted is equal to or less than the thickness of the base plate 111, the IC etc. will not protrude from the surface when the PCB 115 and the base plate 111 are bonded. Therefore, there is no need to consider the storage mode corresponding to these protrusions in the manufacturing process.

The heater board 112 has a common liquid chamber for temporarily storing ink supplied from the ink tank unit IT side, and a recess for forming a group of liquid paths communicating the liquid chamber and the ejection port. A top plate 113 is arranged. Further, an ejection port forming member (orifice plate) 113A having an ink ejection port formed therein is integrally formed on the top plate 113. 114 is the top plate 113 and the heater board 11
This is a pressing spring for configuring the discharge part 101 by bringing the two parts into close contact with each other.

Reference numeral 116 denotes a head unit cover, which covers the ink supply pipe section 1 that enters the ink tank unit IT.
16A, an ink flow path 116B for ink communication between this and the ink introduction pipe section on the top plate side, and a base plate 111
Three pins 116C for three-point positioning or fixing,
This is a member formed by integrally molding the pin engaging part 103, the attachment part of the absorber 104, and other necessary parts. A channel lid 117 is arranged for the ink channel 116B. Further, a filter 118 for removing air bubbles and dust is provided at the tip of the ink supply pipe 116A, and
An O-ring is provided to prevent ink from leaking from the joint.

When assembling the above head unit, the pin 111P protruding from the base plate must be connected to the PCB.
115 so as to be inserted into the through hole 115P, and the two are fixed by adhesive or the like. In fixing both of them, precision is not required so much. This is because the heater board 112, which should be mounted with high precision on the base plate 111, is fixed separately from the PCB 115.

Next, the heater board 112 is precisely placed and fixed on the base plate 111, and the necessary electrical connections are made with the PCB 115. After arranging the top plate 113 and the springs 114 and performing adhesion and sealing as necessary, three pins 116C protruding from the cover are inserted into the holes 111C of the base plate 111 for positioning. Thereafter, the head unit is completed by heat-sealing these three pins 116C.

Ink tank unit In FIG. 3, 211 is an ink container forming the main body of the ink tank unit, 215 is an ink absorber for impregnating ink, 216 is an ink tank lid, and 212 is an electrode pin for detecting the remaining amount of ink. , 213 and 214 are pins 21
This is a contact member related to No. 2.

The ink container 211 generally has pins 212,
It integrally includes a portion 220 for attaching the contact members 213, 214 and the above-described head unit IJU, a supply port 231 for receiving the entry of the ink supply pipe portion 116A, and a knob 201, and also has a portion 220 on the bottom side in FIG. It has a hollow cylindrical portion 233 that is erected approximately at the center thereof. Such an ink container can be formed by integral molding of resin.

The bottom side of the cylindrical portion 233 is open in consideration of the ink filling process, and after filling, a cap 217 shown in FIG. 3 is attached to close it off from the atmosphere. On the other hand, in FIG. 3, a spiral or meandering groove 235 is provided on the upper end surface (in the illustrated example, a spiral groove), and at one end 235A of the groove (in the illustrated example, the center of the spiral groove), a cylindrical portion 235 is provided. An aperture is provided that leads to the internal space of. Further, the other end 235B of the groove is located at a portion of the atmosphere communication port 203 provided in the tank lid 216.

A plurality of (four in the illustrated example) grooves 237 are provided on the side surface of the cylindrical portion 233 at equal angles and communicate with the internal space of the cylindrical portion 233 . As a result, communication between the inside of the ink tank unit and the atmosphere is established through the atmosphere communication port 203, the spiral groove 233, the internal space of the cylindrical portion 233, and the inside of the ink tank unit.
This is through the groove 237. And the cylindrical part 233
The internal space functions as a buffer section to prevent ink leakage due to vibration or rocking. In addition, atmospheric communication port 2
Since the spiral groove 233 that lengthens the path leading to 03 exists, ink leakage is more effectively prevented.

Furthermore, by providing a plurality of grooves 237 at equal angles on the side surface of the cylindrical portion 233 located approximately at the center of the ink tank as in this example, the absorber 215 located around the grooves 237 can be It is possible to ensure a uniform balance with the atmosphere and prevent local concentration of ink within the absorber. This also ensures smooth ink supply to the absorber compression area (around the supply port 231), which will be described later.

The groove 237 extends below the center of the thickness of the container and is provided over a range that completely encompasses the range A where the supply port 231 exists. In addition, it is formed in a range that takes into consideration the position of the remaining amount detection pin 212, thereby ensuring an even ink presence state or an atmosphere communication state around the area where the pin is present, and improving the accuracy of remaining amount detection. be able to.

The ink-impregnated absorber 215 according to this example is provided with a hole 215A through which the cylindrical portion 233 is inserted. By locating the cylindrical portion 233 in this hole 215A, the absorber 215 is not compressed by the cylindrical portion 233, and no ink remains in the compressed portion where the negative pressure is high. On the other hand, the absorber 215 according to this example
The portion located at the supply port 231 has a slightly swollen shape with respect to the shape of the space formed by the ink tank lid 216 and the ink container 211 (indicated by a dashed line in FIG. 3). As a result, when the absorber 215 is housed in the ink tank unit, the swollen part is in a compressed state, so the absorber 215 has a high negative pressure in that part, and therefore ink can be smoothly supplied. mouth 231
This means that it can be introduced to the side.

FIG. 4 is a block diagram showing an example of the configuration of a control system in the inkjet recording apparatus.

Here, 800 is a controller serving as a main control unit, which includes a CPU 801 in the form of a microcomputer, for example, which executes the processing described later in FIG. 9, a program corresponding to the procedure, and a controller for pulse width modulation described later. The image forming apparatus includes a ROM 803 that stores fixed data such as heat pulse voltage values, pulse widths, and other fixed data, and a RAM 805 that has an area for developing image data, a work area, and the like. The controller 800 further includes a timer 807 for timing non-ejection time, etc., which will be described later regarding an embodiment of the present invention. Reference numeral 810 denotes a host device (in this example, a reader unit for image reading) that serves as a source of image data, and transmits and receives image data, commands, status signals, etc. to and from the controller via an interface (I/F) 812. be done.

Reference numeral 820 indicates commands by the operator, such as a power switch 822, a copy switch 824 for instructing the start of recording (copying), and a large recovery switch 826 for instructing the start of large recovery, which is one aspect of ejection recovery processing. A group of switches that accept input. 830 is a group of sensors for detecting the device state, including a sensor 832 for detecting the position of the carriage 82 such as a home position and a start position, and a sensor 834 including a leaf switch and used for detecting the pump position.

Reference numeral 840 denotes a head driver for driving the electrothermal transducer of the recording head in accordance with recording data and the like. Also, a part of the head driver is equipped with temperature control heaters 30A, 3
It is also used to drive 0B. Furthermore, the temperature detection values from the temperature sensors 20A and 20B are sent to the controller 80.
Enter 0. 850 is a main scanning motor for moving the carriage 82 in the main scanning direction, and 852 is its driver. 860 is a sub-scanning motor, which is used to transport (sub-scan) the recording medium.

Various methods are known for driving the electrothermal transducer (ejection heater) during ejection in the above-mentioned inkjet recording apparatus, that is, various modes of driving signals applied to the electrothermal transducer. Typical examples include a single pulse-like electrical signal and a double-pulse (split pulse) drive signal that can relatively well control the amount of ink droplets to be ejected. Furthermore, the applicant has proposed a method in which the amount of ejected ink droplets is controlled in accordance with the head temperature by modulating the initial pulse width of this double pulse, thereby suppressing density unevenness in a recorded image.

The pulse width modulation of this divided (double) pulse and the ejection amount control thereby will be briefly explained below.

FIG. 5 is a diagram for explaining divided pulses according to an embodiment of the present invention.

In FIG. 5, VOP is the drive voltage, P1
is the pulse width of the first pulse (hereinafter referred to as preheat pulse) of the plurality of divided heat pulses, P2 is the interval time, and P3 is the pulse width of the second pulse (hereinafter referred to as main heat pulse). T1,T
2 and T3 indicate the time for determining P1, P2, and P3. The drive voltage VOP is one of the values that indicates the electrical energy necessary for the electrothermal converter to which this voltage is applied to generate thermal energy in the ink in the ink liquid path composed of the heater board and the top plate. The value is determined by the area of the electrothermal transducer, the resistance value, the film structure, and the liquid path structure of the recording head. The divided pulse width modulation driving method sequentially gives pulses with widths of P1, P2, and P3, and the preheat pulse is a pulse mainly used to control the ink temperature in the liquid path, and is important for ejection amount control. It has a role to play. The width of this preheat pulse is set to a value that does not cause bubbling in the ink due to thermal energy generated by the electrothermal transducer upon application of the preheat pulse.

The interval time is provided to provide a constant time interval so that the preheat pulse and the main heat pulse do not interfere with each other, and to equalize the temperature distribution of the ink in the ink liquid path. The main heat pulse causes bubbles in the ink in the liquid path and causes the ink to be ejected from the ejection port, and its width P3 depends on the area of the electrothermal converter, resistance value, film structure, and ink of the recording head. Determined by the structure of the liquid path.

FIG. 6 is a diagram showing the dependence of the discharge amount on the preheat pulse. In the figure, V0 is P1 = 0 [μs
ec], and this value is determined by the head structure. Incidentally, V0 in this example is the environmental temperature TR.
= 25°C, V0 = 18.0 [ng/dot].

As shown by curve a in FIG. 6, the discharge amount Vd increases as the pulse width P1 of the preheat pulse increases.
The pulse width P1 increases linearly from 0 to P1LMT, and in a range where the pulse width P1 is larger than P1LMT, the change loses linearity, and reaches a maximum value when it is saturated at the pulse width P1MAX.

In this way, the pulse width P1LM shows that the change in the discharge amount Vd with respect to the change in the pulse width P1 is linear.
The range up to T is effective as a range in which the ejection amount can be easily controlled by changing the pulse width P1. Incidentally, in this example shown by curve a, P1LMT=1.87
(μs), and the discharge amount at this time is VLMT = 24
．． It was 0 [ng/dot]. In addition, the pulse width P1MAX when the discharge amount Vd reaches the saturated state is P1MAX
X=2.1 [μs], and the discharge amount VMAx at this time
=25.5 [ng/dot].

[0041] When the pulse width is larger than P1MAX, the ejection amount Vd becomes smaller than VMAX. This phenomenon occurs when a preheat pulse with a pulse width in the above range is applied, causing minute bubbles (just before film boiling) on the electrothermal converter, and before the bubbles disappear, the next main heat pulse is applied. The microbubbles disturb the foaming caused by the main heat pulse, thereby reducing the ejection amount. This region is called a pre-foaming region, and in this region, it is difficult to control the ejection amount using the preheat pulse.

[0042] P1 = 0 to P1LMT [μs
] If we define the slope of the straight line that shows the relationship between the discharge amount and the pulse width in the range as the preheat pulse dependence coefficient, then the preheat pulse dependence coefficient is:

[0043]

[Math 1]

[0044] This coefficient KP is determined by the head structure, driving conditions, ink physical properties, etc., regardless of temperature. That is, curves b and c in FIG. 6 show the case of other print heads, and it can be seen that the ejection characteristics change if the print heads are different. In this way, if the recording head is different, the upper limit value P1LMT of the preheat pulse P1 will be different.
As will be described later, an upper limit value P1LMT is determined for each recording head to control the ejection amount. Incidentally, in the recording head and ink shown by curve a of this example, KP = 3.2.
09 [ng/μsec·dot].

That is, another factor that determines the ejection amount of an inkjet recording head is the temperature of the recording head (ink temperature).

FIG. 7 is a diagram showing the temperature dependence of the discharge amount. As shown in curve a of FIG. 7, the ejection amount V
d increases linearly. If we define the slope of this straight line as the temperature dependence coefficient, then the temperature dependence coefficient:

[0047]

[Math 2]

[0048] This coefficient KT is determined by the structure of the head, the physical properties of the ink, etc., regardless of the driving conditions. In FIG. 7, curves b and c also show the case of other recording heads. Incidentally, in the recording head of this embodiment, KT = 0.3 [
ng/°C·dot].

As is clear from the explanations regarding FIGS. 6 and 7, when ejecting is performed by driving the electrothermal transducer with divided pulses, the amount of ink droplets to be ejected is equal to that of the first pulse in the divided pulses. Varies depending on the width, and
Generally, the amount of ejected ink droplets also varies depending on the ink temperature at that time, that is, the environmental temperature. Therefore, when recording, by modulating the initial pulse width of the divided pulses according to the environmental temperature, it is possible to keep the amount of ejected ink droplets constant and prevent density unevenness in the recorded image. It can be done. FIG. 8 shows the width P of the first pulse of the divided pulses.
This shows the modulation of 1. As shown in FIG. 8, one of the drive signals shown as 1 to 11 is selected depending on the detected environmental temperature.

The ejection recovery process according to an embodiment of the present invention performed in the above-mentioned inkjet recording apparatus will be described below.

In the discharge recovery process of this example, by setting a non-suction time, a viscosity increase time, and a no-cap time, the mode of the recovery process is changed according to these times. Each of these times is managed by the timer 807 shown in FIG. Here, the non-suction time is the time that has elapsed since the last suction was performed, the thickening time is the time that has elapsed since the last empty discharge, and the no-cap time is the time that has elapsed since capping was released. Tell each person the time they spent. In this example, each of the above times is detected when the power is turned on,
The recovery process described with reference to FIG. 9 and the like is performed.

A suction operation is performed as one aspect of the recovery process in this example. The suction operation is performed using the cap unit 8300 on the ejection opening surface of the recording head in the cartridge IJC shown in FIG.
The pump 8500 generates a negative pressure. As a result, air bubbles and thickened ink inside the recording head are sucked and discharged from the ejection ports. Along with this, in the ejection recovery process of this example, empty ejection may be performed. When the suction operation is completed, the ejection port surface soiled by ink left during suction is wiped and cleaned by the blade 804 provided adjacent to the cap unit 8300 similarly shown in FIG. 1. After that, idle ejection is performed to discharge the thickened ink and dust pushed into the ejection port by wiping.

When these ejection recovery processes are performed when the power is turned on, if only certain ejection recovery processes are set corresponding to each of the above-mentioned times, the recovery operation may not be performed properly. For example, if the control is such that only a suction operation is performed when the non-suction time exceeds a predetermined time, if that time is quite long, the thickened ink in the print head may not be completely removed by the suction operation alone. It can be difficult. In such a case, it is preferable to use dry ejection in combination, and by raising the temperature of the ink by this dry ejection, the viscosity of the ink can be lowered, and the ink can be easily discharged by suction. Based on the above, in the embodiment of the present invention described below, control is performed to perform various ejection recovery processes according to each of the plurality of times described above. This ejection recovery process will be explained below.

FIG. 9 is a flowchart showing the sequence of ejection recovery processing according to the first embodiment of the present invention. The recovery operation when the power is turned on will be explained below according to this sequence.

This process is performed in parallel with the warming-up process when the copying machine is powered on, and when the power is turned on, the timer 807 in the recording apparatus main body shown in FIG. Detect the measured no-cap time. That is, in this example, when the capping by the cap unit 8300 shown in FIG. The difference between the two is calculated and the time is detected as the uncapped time. Note that at the same time, the contents of the capping flag are detected. The content of this capping flag is set to "1" when capping is performed by the cap unit 8300, and if this flag is "1" when the power is turned on, that is, in the capping state, capping has been performed normally. The process proceeds to step S93, where a non-suction time and a viscosity increase time are detected. As with the no-cap time, for the non-suction time and viscosity thickening time, remember the time of the last suction operation and last discharge (including empty discharge), respectively, and calculate the time difference from when the power is turned on. Determined by

After detecting these times, in step S94, a recovery operation is performed with reference to Table 1 set in advance. This recovery operation will be explained below.

FIG. 10 is a conceptual diagram of Table 1, which is divided into classes according to the above-mentioned non-suction time and viscosity increase time.

As is clear from Table 1, the non-suction time is divided into classes based on 5 days, and if this time is 5 days or more, suction operation is performed. The suction pressure of these suction operations varies depending on the viscosity thickening time, and is increased as this time increases. In addition to this suction,
Perform empty discharge from all discharge ports. This idle ejection has a portion in which its operation time overlaps with that of suction, and the number of ejections is set to increase according to the viscosity thickening time.

The reason why the standard value of the non-suction time is set to 5 days is because if the recording head is left in the main body of the apparatus, if this continues for more than 5 days, in the worst case, a relatively large amount of liquid will be generated in the common liquid chamber of the recording head. This is because air bubbles may accumulate, making it impossible or unstable to eject ink. Furthermore, when performing suction, the reason why the suction pressure and the number of empty ejections are increased as the viscosity thickening time increases is as follows. The longer the time without ejection (viscosity thickening time), the greater the degree of thickening of ink in the ink path, etc., and therefore the pressure required for suction becomes greater. Additionally, the increase in the number of blank ejections is because the change in ink concentration caused by thickening due to evaporation of ink moisture due to leaving the ink unused extends to the ink in the common liquid chamber of the print head, so the thickening time is relatively short. This is because if the number of idle ejections remains unchanged, even ink whose density has changed cannot be ejected, and this is likely to cause density unevenness in recorded images.

Regarding the classification regarding the viscosity increase time, if this time is 10 days or more, the recovery operation is interrupted for about 1.5 seconds after the suction accompanied by the empty ejection operation, and then , All the ejection ports of the recording head are used to perform idle ejection at 4 KHz. This is because if the ink inside the common liquid chamber thickens considerably if no ejection is performed for a long period of time (10 days or more), the ink inside the common liquid chamber cannot be easily discharged with normal empty ejection operations. The ink ejection operation is performed with some interruption. According to the ink ejection operation accompanied by this interruption,
During this interruption, convection occurs in the common liquid chamber due to the ink flow generated by the first discharge, and this convection equalizes the degree of thickening of the ink in the common liquid chamber, and the restarted discharge operation efficiently thickens the ink. Ink is drained.

In the process of step S94, if the non-suction time is less than 5 days, as is clear from Table 1 shown in FIG. 10, the suction operation is basically not performed and the recovery operation is performed only by dry ejection. That is, for five days after the last suction operation, relatively large bubbles that would normally cause the ejection to become unstable do not accumulate. Therefore, necessary idle ejection is performed so that the ink is stably ejected and density unevenness does not occur in the recorded image. Therefore, the number of ejections is set to be larger than the number of empty ejections performed simultaneously with the above-mentioned suction operation. In fact, as shown in Table 1 of Figure 10, all discharge ports are operated at 500 Hz at 4 KHz until the viscosity increase time is 1 day.
1000 shots at 4KHz for 1 to 3 days.

When the viscosity increase time is 3 to 5 days, dry ejection is performed 3000 times at 4 KHz at all ejection ports. The driving conditions at this time are not driving in which the pulse axis is modulated according to the recording head temperature as described above, but a fixed pulse width. Furthermore, even if drive conditions for ejection unique to each print head are set for each print head as in this example, and ejection is performed according to that data, the main body side is Dry ejection is performed under preset driving conditions.

This is because the purpose of this dry ejection is to detect non-ejection. That is, the idle ejection is performed to detect whether or not there is a failure in ejection at the ejection ports in the recording head, and therefore to keep the heat emitted from the ejection heater constant. The method of detecting a non-ejection is to calculate the difference in the recording head temperature before and after the idle ejection, and to determine whether this temperature difference is equal to or higher than a predetermined temperature.

In this example, when this temperature difference, that is, the temperature increase of the recording head is 20° C. or more, it is determined that there is a failure in ejection, and a recovery operation is automatically performed. In this recovery operation, a suction operation is performed, and empty ejection at the same time as suction is not performed.

According to the above-described recovery operation referring to Table 1, it is possible to reliably output a stable and even image without consuming more ink than necessary.

Next, if the no-cap time is 0 or more in step S92 of the procedure shown in FIG. 9, that is, if the no-cap flag is "0" (if no capping is performed), the After detecting the suction time, a recovery operation is performed in accordance with Table 2 shown in FIG. 11 in step S96. This recovery operation will be explained below.

If the recording head is not capped, the recovery operation is changed depending on the values of the no-cap time and the no-suction time. The reason why we do not refer to the viscosity increase time for this recovery operation is that when the recording head is not capped, ink moisture evaporates through the ejection ports much more than when the print head is capped. This is because the ink thickens rapidly in the vicinity.

As shown in Table 2 of FIG. 11, the standard time for classification regarding non-suction time is 5 days, and suction is always performed if the non-suction time is 5 days or more. Even if the non-suction time is less than 5 days, if the no-cap time is 1 hour or more, suction is performed. This is because when the recording head is in the uncapped state, dust or the like may block the ejection ports, and it can be assumed that recovery cannot be achieved by just empty ejection. This is also because the proportion of air bubbles mixed in from the discharge port increases. The recovery operation shown in Table 2 of FIG. 11 is basically the same as the recovery operation in the case of a normal cap shown in Table 1 of FIG. 10, so the explanation thereof will be omitted.

In the first embodiment described above, the recovery operation is performed by referring to a table according to the combination of durations of each state of the recording head that affects ejection, but in the second embodiment of the present invention, the recovery operation is performed by referring to a table. In the example, instead of referring to a table, the recovery operation is performed according to the value of a function with each of the above times as variables. This recovery operation will be explained below.

Basically, the amount of suction in the suction operation is Q.
, KNZ is the number of ejections during idle ejection mainly to remove thickened ink near the ejection ports, and KEK is the number of ejections during idle ejection mainly to remove highly concentrated ink in the common liquid chamber of the print head. , these are treated as functions of three variables: non-suction time tq, viscosity increase time tz0, and no-cap time tn0, and the sum of these functions is performed as the recovery operation.

First, the suction amount Q is expressed by the following equation 3.

[0072]

[Math 3]

In other words, the suction amount Q is the function g1 (tq
), g2 (tn0). In other words, the suction amount Q is Q1 = g1 (t2), Q2
= g2 (tn0), whichever is larger. Here, k1 and k2 are coefficients, and Tq
, TN0 are fixed values. For example, Tq is 5 days, and T
N0 may be 1 hour. Further, the functions g1 and g2 can be qualitatively the same function, and a specific example thereof is Q1 = g1 (tq
) is shown in Figure 12.

The reason why the minimum suction amount is set here is that, first, setting the suction amount Q1 to 0 when performing a recovery operation is actually ineffective. In other words, the main purpose of suction is to remove air bubbles within the discharge port and the common liquid chamber to ensure normal discharge.Since air bubbles have a certain size, a certain amount is required to remove them. This is because suction must be performed. Here Q1m
In=0.05g.

Furthermore, the reason why the maximum suction amount is set is that suctioning a larger amount will not have much effect. That is, if an amount of ink approximately twice the volume of the common liquid chamber is sucked, the ink in the common liquid chamber is almost refreshed. Here, Q1max=0.15g. Therefore, the function g1 is determined so as not to exceed a certain value Q1max.

Next, the number of ejections Knz in idle ejection for removing thickened ink near the ejection ports is expressed by the following equation 4.

[0077]

[Formula 4] Knz=max[f1 (tz0), f2 (
tn0)] Here, the functions f1 and f2 are qualitatively the same functions, and can be expressed by the relationship f1 (t)=f2 (kt), where k is a coefficient. For example, Knz=f1
(tz0) is a function specifically shown in FIG. 13.

Here, the slope of the rise of Knz=f1 (t) is determined as follows. That is, the evaporation rate of ink water within the ejection port is relatively high at the beginning, and thereafter the evaporation rate decreases because the ink has thickened due to evaporation, and the degree of thickening of the ink within the ejection port progresses in accordance with this evaporation rate. Therefore, the number of blank discharges is determined according to the above-mentioned evaporation tendency.

Further, the maximum value is set for the number of ejections Knz because a predetermined recovery is possible by ejecting this number of shots, and specifically, this maximum value is set to 1000 shots. Furthermore, the drive frequency for idle discharge is the maximum drive frequency of 4KH.
I made it z.

Next, the number of ejections KE in idle ejection for removing highly concentrated ink in the common liquid chamber of the recording head.
K is expressed by the number 5.

[0081]

[Math. 5] KEK=m・h(A-Q)・
×max[f3 (tz
0), f4 (tn0), f5 (tq)] where m
is a coefficient and A is a constant value. A is set to be a value somewhat larger than the suction amount Q obtained by equation 3. Further, h is a function of the suction amount Q, and in this example, h(x)=x. That is, h(A-Q)=A-Q, and Q=0
In this case, mh(A-Q)=mA≒1 is set. This is when Q=0, that is, when not suctioning, KEK=
This is to perform idle ejection determined by max[f3, f4, f5]. Therefore, since mA=1, A=0.
17 (g), m=1/0.17 (1/g).

Therefore, when the suction amount Q is maximum, that is, when Qmax = 0.15 (g) as described above, KE
K=0.02/0.17×max[f3, f4, f
5), and at the same time as suction, idle ejection of the number of ejections determined by this number is performed.

[0083] The reason why the number of idle ejections is small when suction is involved is that the highly concentrated ink in the common liquid chamber can be sufficiently removed by suction, and idle ejection is performed to assist in this process. This is because it is a thing.

Function f3 (tz0), f4 (tn0)
A specific example is shown in FIG.

These functions f3 and f4 are also set in the same way as the function f1. In other words, like the ink near the ejection ports, the ink in the common liquid chamber thickens, making it difficult for the ink moisture to evaporate after a certain period of time, and the concentration of the ink in the common liquid chamber becomes saturated. come. Therefore, the number of ejections is set according to this density tendency.

The function f5 (tq) is shown in FIG.

This function is defined as follows. That is, the value of the function f5 increases almost linearly until a certain period of time. This is because when suction is not performed, the ink in the common liquid chamber where the flow of ink is stagnant may increase in viscosity, and this thickening spreads within the common liquid chamber approximately in proportion to the non-suction time. For this reason, the thickened ink is refreshed to some extent by ejecting the ink in a number proportional to the spread of the thickened ink.

[0088] Here, the maximum value of KEK was set at 9000 shots. When more than 3,000 shots were fired, an interval of about 0.5 seconds was provided to allow empty firing. This is because this idle ejection was set to the maximum drive frequency of 4KHz, so if the ejection was performed continuously without an interval, the recording head temperature would rise rapidly and the ejection could become unstable. One purpose is to prevent this, and another purpose is to effectively remove the thickened ink in the liquid chamber by providing a certain interval between ejections.

As explained above, an optimal recovery operation can be performed for a plurality of states in the recording head by performing a recovery action using the value of a multivariable function in which the duration of each of these states is a variable. It has become possible. especially,
Since a table is not used as in the first embodiment, continuous values can be set and a more appropriate recovery operation can be performed. That is, compared to the case of a table, unnecessary ink consumption is avoided and ink in the print head can be refreshed reliably. Furthermore, since no tables are used, memory can be reduced.

Note that each function in the second embodiment can be made simpler. For example, a certain range of time may be divided and the function of each range may be expressed as a linear function. By doing so, calculations by the CPU within the main body can be simplified.

Furthermore, by changing the function and its coefficients depending on the color and type of ink, it becomes possible to perform a more appropriate recovery operation.

Furthermore, these include, for example, C, M, Y, B
When applied to a four-color full-color printer or the like, each may have an independent function depending on the ink color.

Additionally, although the non-suction time, viscosity increase time, and no-cap time have been described above, other times may be used as long as they serve as indicators of the ejection state of the recording head.

(Others) The present invention particularly relates to means for generating thermal energy as energy used to eject ink, in an inkjet recording system.
For example, the present invention provides an excellent effect in a recording head or recording apparatus that is equipped with an electrothermal converter (for example, an electrothermal converter, a laser beam, etc.) and uses the thermal energy to cause a change in the state of the ink. This is because such a system can achieve higher recording density and higher definition.

For its typical configuration and principle, see, for example, US Pat. Nos. 4,723,129 and 4,740.
Preferably, it is carried out using the basic principles disclosed in the '796 specification. This method is the so-called on-demand type.
It is applicable to both continuous types, but in particular, in the case of on-demand type, it is applicable to the electrothermal converter placed corresponding to the sheet holding the liquid (ink) or the liquid path. , by applying at least one drive signal that corresponds to recorded information and provides a rapid temperature rise exceeding nucleate boiling, the electrothermal transducer generates thermal energy to produce film boiling on the thermally active surface of the recording head. liquid (ink) that corresponds one-to-one to this drive signal.
This is effective because it can form air bubbles inside. The growth and contraction of the bubble causes liquid (ink) to be ejected through the ejection opening to form at least one droplet. It is more preferable to use this drive signal in a pulse form, since the growth and contraction of bubbles can be carried out immediately and appropriately, making it possible to eject liquid (ink) with particularly excellent responsiveness. This pulse-shaped drive signal is described in US Pat. No. 4,463,359 and US Pat.
345262 are suitable. Furthermore, if the conditions described in US Pat. No. 4,313,124 concerning the invention regarding the temperature increase rate of the heat acting surface are adopted, even more excellent recording can be performed.

[0096] In addition to the configuration of the recording head that is a combination of ejection ports, liquid paths, and electrothermal converters (straight liquid flow path or right-angled liquid flow path) as disclosed in the above-mentioned specifications, U.S. Pat. No. 4,558,333 and U.S. Pat. No. 44 disclose a configuration in which a heat acting part is arranged in a bending region.
A configuration using the specification of No. 59600 is also included in the present invention. In addition, JP-A-59-123670 discloses a configuration in which a common slit is used as a discharge part for a plurality of electrothermal converters, and a hole that absorbs pressure waves of thermal energy is disclosed. The effects of the present invention are also effective even with a configuration based on Japanese Patent Application Laid-open No. 138461/1985 which discloses a configuration corresponding to the discharge section. That is, regardless of the form of the recording head, according to the present invention, recording can be performed reliably and efficiently.

Furthermore, the present invention can be effectively applied to a full-line type recording head having a length corresponding to the maximum width of a recording medium that can be recorded by a recording apparatus. Such a recording head may have either a configuration in which the length is satisfied by a combination of a plurality of recording heads, or a configuration as a single recording head formed integrally.

In addition, even in the case of a serial type as in the above example, the recording head is fixed to the main body of the apparatus, or by being attached to the main body of the apparatus, electrical connection with the main body of the apparatus and ink flow from the main body of the apparatus are possible. The present invention is also effective when using a replaceable chip-type recording head that can be supplied with ink or a cartridge-type recording head in which an ink tank is integrally provided in the recording head itself.

Further, it is preferable to add a recovery means for the recording head, a preliminary auxiliary means, etc., which are provided as a configuration of the recording apparatus, to the present invention because the effects of the present invention can be further stabilized. . Specifically, these include capping means for the recording head, cleaning means, pressure or suction means, preheating means using an electrothermal transducer or another heating element, or a combination thereof; It is also effective to perform a preliminary ejection mode in which ejection is performed separately from printing in order to perform stable printing.

[0100] Regarding the type and number of recording heads to be mounted, for example, in addition to one type that corresponds to single-color ink, there are also types and numbers that correspond to multiple inks of different recording colors and densities. A plurality of them may be provided. That is, for example, the recording mode of the recording apparatus is not limited to a recording mode for only a mainstream color such as black, but may also be a recording mode in which the recording head is configured integrally or in a combination of multiple colors, The present invention is also extremely effective for devices equipped with at least one full color by color mixture.

In addition, in the embodiments of the present invention described above, the ink is described as a liquid, but ink that solidifies at room temperature or lower, softens or liquefies at room temperature, or inkjet method. In general, the temperature of the ink itself is adjusted within the range of 30°C to 70°C to keep the viscosity of the ink within the stable ejection range. Any eggplant is fine. In addition, the temperature rise caused by thermal energy can be actively prevented by using the energy to change the state of the ink from a solid state to a liquid state, or ink that solidifies when left standing is used to prevent ink evaporation. In any case, the ink is liquefied by applying thermal energy in accordance with the recording signal, and the liquid ink is ejected, or the ink has already begun to solidify by the time it reaches the recording medium. The present invention is also applicable when using ink that is liquefied only by energy. The ink used in such cases is disclosed in Japanese Patent Application Laid-Open No. 54-56847 or Japanese Patent Application Laid-Open No. 60-1989.
As described in Japanese Patent Publication No. 71260, the material may be held in a liquid or solid state in the recesses or through holes of a porous sheet, facing the electrothermal converter. In the present invention, the most effective method for each of the above-mentioned inks is to perform the above-mentioned film boiling method.

In addition, the inkjet recording apparatus of the present invention can be used as an image output terminal for information processing equipment such as a computer, a copying machine combined with a reader, or a facsimile machine having a transmitting and receiving function. It may also take a form.

[0103]

[Effects of the Invention] As is clear from the above description, according to the present invention, capping is not performed for a period of time after the last ejection or the last suction in the recording head, for example. The amount of suction, the number of empty ejections, etc. in the ejection recovery process are controlled depending on the duration of each of the plurality of states, such as time.

[0104] As a result, an appropriate recovery operation is performed, and stable ejection and high image quality can be obtained.
Ink consumption associated with recovery operations can be reduced.

[Brief explanation of the drawing]

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

FIG. 2 is a perspective view of a recording head cartridge installed in the inkjet recording apparatus shown in FIG. 1;

3 is an exploded perspective view of the recording head cartridge shown in FIG. 2. FIG.

4 is a block diagram showing a control configuration in the inkjet recording apparatus shown in FIG. 1. FIG.

FIG. 5 is a waveform diagram showing a print head drive signal waveform for ejection in the inkjet printing apparatus shown in FIG. 1;

FIG. 6 is a diagram showing the relationship between the drive signal waveform shown in FIG. 5 and the amount of ink ejection.

FIG. 7 is a diagram showing the relationship between the environmental temperature of the print head and the amount of ink ejection.

FIG. 8 is a waveform diagram showing an aspect of waveform modulation of the drive signal waveform shown in FIG. 5;

FIG. 9 is a flowchart showing a predetermined procedure of ejection recovery processing according to the first embodiment of the present invention.

FIG. 10 is a conceptual diagram of a table used in the process shown in FIG. 9;

FIG. 11 is a conceptual diagram of a table used in the process shown in FIG. 9;

FIG. 12 is a diagram showing functions used in a second embodiment of the invention.

FIG. 13 is a diagram showing functions used in a second embodiment of the invention.

FIG. 14 is a diagram showing functions used in a second embodiment of the invention.

FIG. 15 is a diagram showing functions used in a second embodiment of the invention.

[Explanation of symbols]

IJU Inkjet recording head unit IJC
Recording head cartridge 800 Controller 801 CPU 803 ROM 805 RAM 807 Timer 822 Power switch 8041 Blade 8300 Cap unit 8500 Pump unit

Claims (5)

[Claims] 1. An inkjet recording apparatus that performs recording by discharging ink, comprising a recording head for discharging ink, a discharge recovery means for performing discharge recovery processing of the recording head, and an inkjet recording device for discharging ink of the recording head. a timer for measuring each time during which a plurality of states in the inkjet recording apparatus continue that affect the performance of the inkjet recording device; and a timer for measuring each time during which a plurality of states continue, each of which affects the inkjet recording device; An inkjet recording apparatus comprising: a recovery control means for controlling ejection recovery processing by an inkjet recording apparatus. 2. The ejection recovery means includes an ink suction means for suctioning ink from the recording head, an idle ejection means for performing ejection not related to recording of the apparatus, and an ink ejection port of the recording head. and a capping means for covering the area where the liquid has been removed, and the time during which each of the plurality of states lasts is the time since the recording head last ejected, and the time since the last suction was performed by the suction means. 2. The inkjet recording apparatus according to claim 1, wherein the period is a time during which a region where the ink ejection port is disposed is not covered by the capping means. 3. The recovery control time is determined by controlling the ejection recovery process by referring to a table based on the duration of each of the plurality of states. Inkjet recording device. 4. The recovery control means controls the ejection recovery process based on a function that uses as a variable the time during which each of the plurality of states lasts.
or 2. The inkjet recording device according to 2. 5. The inkjet according to claim 1, wherein the recording head generates bubbles in the ink using thermal energy, and ejects the ink based on the generation of the bubbles. Recording device.