JP2877971B2 - Ink jet recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In an ink-jet recording apparatus, if the apparatus is left for a long period of time without printing, the ink viscosity increases due to evaporation of ink moisture mainly through the discharge port of a recording head, or the ink supply increases. In some cases, relatively large bubbles may be generated in the ink due to air entrainment in the system or the growth of fine bubbles originally in the ink. If such an increase in ink viscosity or generation of bubbles occurs in ink in an ink path or the like communicating with the discharge port of the recording head, the recording head may not discharge well, and as a result, printing may be performed. The image quality and quality of the image and the like will be impaired. The occurrence of such bubbles and the increase in ink viscosity are not caused only by not performing printing for a long time.For example, when performing printing with a high printing duty,
The number of fine bubbles generated by ejection increases, and these may aggregate to generate relatively large bubbles.Some of the plurality of ejection ports, depending on print data, hardly perform ejection. In such a case, the ink viscosity of such an ejection port may be relatively high.

[0003] In response to the increase in ink viscosity and the generation of bubbles in the recording head as described above, in a conventional ink jet recording apparatus, for example, the ink in the recording head is sucked when the power is turned on, or the recording is performed. An ejection recovery process has been performed in which the ink inside the recording head is refreshed by discharging the thickened ink and bubbles by pressurizing the ink inside the head. Further, during printing, an ejection recovery process such as a so-called idle ejection may be performed according to a printing time, a printing duty, or the like.

[0004]

However, in the above-described conventional ejection recovery processing, the ink is discharged by simply suctioning or pressurizing in response to power-on, so that it is relatively frequent. When the power is repeatedly turned on and off, a discharge recovery process that is not always necessary may be performed. For example, when the power of the printing apparatus is turned on without much time since the previous power-off, while the viscosity of the print head and the degree of bubbles do not affect the ejection, In some cases, an ejection recovery process is performed. In such a case, unnecessary ink is consumed for the ejection recovery processing, and as a result, the running cost of the printing apparatus increases.

The present invention has been made on the basis of the above-mentioned viewpoints, and can indicate the viscosity of the ink in the recording head and the degree of bubbles, for example, the non-ejection time and the time when the ejection port is not capped. By measuring the time during which the predetermined state in the device continues for each of the plurality of predetermined states, and controlling the discharge recovery processing based on the plurality of times measured, the timed discharge recovery processing is performed. Accordingly, it is an object of the present invention to provide an ink jet recording apparatus in which the amount of ink consumption accompanying the ejection recovery processing is reduced.

[0006]

According to the present invention, there is provided:
In an ink jet recording apparatus that performs recording by discharging ink, a recording head for discharging ink, a discharge recovery unit for performing a discharge recovery process of the recording head, and a recording head that affects the discharge of ink from the recording head. A timer means for timing each time a plurality of states in the ink jet recording apparatus continue, and a discharge recovery process by the discharge recovery means in accordance with a combination of the respective time periods for the plurality of states to be counted by the timer means. Recovery control means for controlling.

[0007]

According to the above arrangement, a plurality of states continue, for example, the time since the last ejection of the print head, the time since the last suction, and the time when capping is not performed. The amount of suction, the number of idle discharges, and the like in the discharge recovery processing are controlled in accordance with each time.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic perspective view of an ink jet recording apparatus according to one embodiment of the present invention. This apparatus is a full-color serial type printer having replaceable ink tank integrated recording head cartridges corresponding to four inks of black (Bk), cyan (C), magenta (M), and yellow (Y). And is used as a recording unit of a full-color copying machine as 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 has 128 ejection ports.

In FIG. 1, IJC is Y, M, C, Bk
And four recording head cartridges corresponding to the respective inks, in which a recording head and an ink tank storing ink for supplying ink to the recording head are integrally formed. Each recording head cartridge IJC is detachably mounted on the carriage by a configuration (not shown). Carriage 82
Are slidably engaged along the guide shaft 811 and
Drive belt 85 moved by a main scanning motor (not shown)
2 and a part of it. Thus, the recording head cartridge IJC can be moved for scanning along the guide shaft 811. Reference numerals 815, 816 and 817, 818 denote conveying rollers extending substantially parallel to the guide shaft 811 on the back side and the near side in the drawing of the recording area scanned by the recording head cartridge IJC. Transport rollers 815, 8
16 and 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 facing the surface of the recording head cartridge IJC on which the ejection port surface is disposed.

A recovery unit is provided facing a movable area of the cartridge IJC adjacent to a recording area of the recording head cartridge IJC. This recovery system unit is used when performing idle discharge or ink suction processing according to the present invention. In the recovery unit, reference numeral 8300 denotes a cap unit provided corresponding to each of a plurality of cartridges IJC having a recording head. The cap unit 8300 is slidable in the horizontal direction in FIG. It is possible. When the carriage 82 is at the home position, the carriage 82 is joined to the recording head and capped. In the recovery system unit, reference numeral 8401 denotes a blade as a wiping member. Further, reference numeral 8500 denotes a pump unit for sucking ink or the like from the ejection port of the recording head and its vicinity via the cap unit 8300.
The cap unit 8300 suppresses the evaporation of the ink moisture and prevents the ink from thickening at the time of performing non-printing by performing capping when the ink is discharged into the cap unit 8300 in a state where the cap unit 8300 is capped on the recording head or during non-recording by capping. Used for

FIG. 2 shows an example of the configuration of a head cartridge mountable on a carriage of the ink jet recording apparatus shown in FIG. The cartridge according to the present embodiment has an ink tank unit IT and a head unit IJU integrally, and these are detachable from each other. A wiring connector 102 for receiving a signal or the like for driving the ink ejection unit 101 of the head unit IJU and outputting a remaining ink amount detection signal is provided at a position aligned with the head unit IJU and the ink tank unit IT. . Therefore, when the cartridge is mounted on a carriage described later, the height H
And the thickness of the cartridge can be reduced. This makes it possible to make the carriage small when arranging the cartridges side by side as described above with reference to FIG. When mounting the head cartridge on the carriage, the ejection unit 1
The knob 201 provided on the ink tank unit IT can be gripped and arranged on the carriage with 01 being on the lower side. The knob 201 is engaged with a lever provided on a carriage described later for performing a mounting operation of the cartridge. Then, at the time of mounting, the pins provided on the carriage side engage with the pin engaging portions 103 of the head unit IJU, and the head unit IJU is positioned.

In the head cartridge according to the present embodiment, an absorber 104 for wiping the surface of the ink discharge portion 101 and cleaning a member for cleaning the surface is arranged in parallel with the ink discharge portion 101. Further, an air communication port 203 for introducing air with ink consumption is provided substantially at the center of the ink tank unit IT.

FIG. 3 is an exploded perspective view of the head cartridge shown in FIG. The head cartridge according to the present example includes:
It is composed of a head unit IJU and an ink tank unit IT.
This will be described with reference to FIG.

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

The above-described wiring connector 102 is a PCB 11
5, a drive signal from a control circuit (not shown) is received by the wiring connector 102, and the PCB 115
Is supplied to the heater board 112 via the. PCB11
Reference numeral 5 denotes a double-sided wiring board in this example, and further includes information unique to the head, for example, appropriate driving conditions for the electrothermal transducer,
A ROM-type IC 128 storing a D number, ink color information, driving condition correction data (head shading (HS) data), PWM control conditions, and the like, and a capacitor 12
9 are provided.

As shown in the figure, the IC 128 and the capacitor 129 are provided on the joint surface side of the PCB 115 with the base plate 111 and the notch 11 of the base plate 111.
It is arranged at a position corresponding to 1A. by this,
If the height at the time of mounting the IC or the like is equal to or less than the thickness of the base plate 111, the IC or the like does not protrude from the surface when the PCB 115 and the base plate 111 are joined. Therefore, it is not necessary to consider a storage mode corresponding to the protrusion in the manufacturing process.

On the heater board 112, a common liquid chamber for temporarily storing ink supplied from the ink tank unit IT side and a concave portion for forming a liquid path group for communicating the liquid chamber with the discharge port are provided. The top plate 113 is arranged. The top plate 113 is integrally formed with a discharge port forming member (orifice plate) 113A in which ink discharge ports are formed. 114 is the top plate 113 and the heater board 11
2 is a pressing spring for forming the discharge section 101 by bringing the discharge section 101 into close contact.

Reference numeral 116 denotes a head unit cover, which is an ink supply pipe 1 that enters the ink tank unit IT.
16A, an ink flow path 116B for communicating ink with the top plate-side ink introduction tube, and a base plate 111
Three pins 116C for three-point positioning or fixing to the
It is a member formed by integrally molding the pin engaging portion 103, the mounting portion of the absorber 104, and other necessary portions. A channel cover 117 is provided for the ink channel 116B. A filter 118 for removing bubbles and dust is provided at the tip of the ink supply pipe 116A, and an O-ring for preventing ink from leaking from the joint is provided.

In assembling the above head unit, the pins 111P projecting from the base plate are connected to the PCB.
Positioning is performed so as to be inserted into the through-hole 115P provided in 115, and both are fixed by bonding or the like. In fixing the two, precision is not so required. This is because the heater board 112 to be mounted on the base plate 111 with high accuracy is fixed separately from the PCB 115.

Next, the heater board 112 is precisely placed and fixed on the base plate 111, and necessary electrical connection with the PCB 115 is made. Then, the top plate 113 and the spring 114 are arranged, and after bonding and sealing are performed as necessary, positioning is performed by inserting three pins 116C protruding from the cover into the holes 111C of the base plate 111. Thereafter, the head unit is completed by thermally fusing these three pins 116C.

Ink tank unit In FIG. 3, reference numeral 211 denotes an ink container which forms the main body of the ink tank unit, 215 denotes an ink absorber for impregnating ink, 216 denotes an ink tank cover, and 212 denotes an electrode pin for detecting the remaining amount of ink. , 213 and 214 are pins 21
2 is a contact member.

The ink container 211 generally includes pins 212,
A portion 220 for mounting the contact members 213 and 214 and the above-described head unit IJU, a supply port 231 for receiving the ink supply tube portion 116A, and a knob 201 are integrally provided. It has a hollow cylindrical portion 233 erected almost at the center. Such an ink container can be formed by integral molding of a resin.

The bottom side of the cylindrical portion 233 is opened in consideration of the ink filling process. After filling, the cap 217 shown in FIG. 3 is attached and closed to the atmosphere. On the other hand, a spiral or meandering groove 235 is provided on the upper end surface in FIG. 3 (a spiral in the illustrated example), and a cylindrical portion 233 is formed at one end 235A of the groove (the center of the spiral groove in the illustrated example). There is an opening communicating with the internal space.
The other end 235 </ b> B of the groove is located at the position 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 an equal angle, 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 made through the atmosphere communication port 203, the spiral groove 233, the internal space of the cylindrical portion 233, and the groove 237. And the cylindrical part 2
The internal space of 33 functions as a buffer unit for preventing ink leakage due to vibration or swing. In addition, since there is the spiral groove 233 that lengthens the path to the atmosphere communication port 203, ink leakage is more effectively prevented.

Further, since a plurality of grooves 237 are provided at equal angles on the side surface of the cylindrical portion 233 located substantially at the center of the ink tank as in the present embodiment, the absorber 215 located around the periphery is provided. It is possible to secure a uniform state of balance with the atmosphere and prevent local concentration of ink in the absorber. This can also ensure smooth ink supply to the absorber compression area (around the supply port 231) described later.

Note that the groove 237 extends below the center of the thickness of the container and is provided over a range completely including the range A where the supply port 231 exists. In addition, it is formed in a range in which the position of the remaining amount detection pin 212 is also taken into consideration, thereby ensuring a uniform ink presence state or air communication state around the pin existing portion, and improving the accuracy of the remaining amount detection. be able to.

The ink impregnating absorber 215 according to the present embodiment is provided with a hole 215A for receiving the insertion of the cylindrical portion 233. By arranging the tubular portion 233 in the hole 215A, the absorber 215 is not compressed by the tubular portion 233, and no ink remains in the compressed portion where the negative pressure is high. On the other hand, the absorber 21 according to the present example
Reference numeral 5 denotes a shape in which the portion located at the supply port 231 is slightly swelled 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). Thus, when the absorber 215 is stored in the ink tank unit, the expanded portion is in a compressed state, so that the absorber 215 has a high negative pressure at that portion, and thus supplies ink smoothly. Mouth 23
It can be introduced to one side.

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

Here, reference numeral 800 denotes a controller constituting a main control unit, for example, a CPU 801 in the form of a microcomputer for executing processing described later in FIG. 9, a program corresponding to the procedure, and a pulse width modulation described later. , A ROM 803 storing fixed data such as a heat pulse voltage value, a pulse width, and the like, and a RAM 805 provided with an area for developing image data, a work area, and the like. The controller 800 further includes a timer 807 for measuring a non-ejection time and the like, which will be described later with reference to an embodiment of the present invention. Reference numeral 810 denotes a host device serving as a supply source of image data (in this example, a reader unit for reading an image). Image data and other commands and status signals are transmitted to and received from a controller via an interface (I / F) 812. Is done.

Reference numeral 820 denotes a command from the operator such as a power switch 822, a copy switch 824 for instructing the start of recording (copying), a large recovery switch 826 for instructing the start of a large recovery which is one mode of the ejection recovery processing. This is a switch group that receives an input. Reference numeral 830 denotes a sensor group for detecting a device state, such as 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 a pump position.

Reference numeral 840 denotes a head driver for driving the electrothermal transducer of the printhead according to print data and the like. Part of the head driver is a temperature control heater 30A,
It is also used to drive 30B. Further, the temperature detection values from the temperature sensors 20A and 20B are
Enter 00. 850 is a main scanning motor for moving the carriage 82 in the main scanning direction, and 852 is its driver. A sub-scanning motor 860 is used to convey (sub-scan) a recording medium.

There are various known methods of driving the electrothermal transducer (ejection heater) at the time of ejection in the above-described ink jet recording apparatus, that is, the mode of a drive signal applied to the electrothermal transducer. As typical examples, a single pulse-like electric signal and a double pulse (divided pulse) -like drive signal capable of controlling the amount of ejected ink droplets relatively well are known. In addition, the present applicant has proposed a method in which the initial pulse width of the double pulse is modulated to control the amount of ejected ink droplets in accordance with the head temperature, thereby suppressing the density unevenness of a recorded image.

The outline of the pulse width modulation of the divided (double) pulse and the control of the ejection amount will be described below.

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

In FIG. 5, V _OP is the drive voltage, P ₁ is the pulse width of the first pulse of the plurality of divided heat pulses (hereinafter referred to as the preheat pulse), P ₂ is the interval time, and P ₃ is the second. It is a pulse width of a pulse (hereinafter, referred to as a main heat pulse). T ₁ , T ₂ , and T ₃ indicate times for determining P ₁ , P ₂ , and P ₃ . The driving voltage V _OP is one of the values indicating electric energy required for the electric heat converter to which the voltage is applied to generate heat energy in the ink in the ink liquid path formed by the heater board and the top plate. The value is determined by the area, resistance value, film structure, and liquid path structure of the recording head of the electrothermal transducer. The divided pulse width modulation driving method includes P ₁ , P ₂ ,
And is to be given sequentially pulse width of P _3, the pre-heat pulse is mainly a pulse for controlling the ink temperature in the liquid path, is it load the important role of the ejection amount control. The preheat pulse width is set to a value that does not cause a bubbling phenomenon in the ink due to the thermal energy generated by the electrothermal converter when applied.

The interval time is provided to provide a predetermined time interval so that the preheat pulse and the main heat pulse do not interfere with each other, and to make the temperature distribution of the ink in the ink liquid path uniform. The main heat pulse is caused to foam in the ink in the liquid passage is for discharging ink from the discharge port, the area of the width P ₃ is an electrothermal transducer, resistance, film structure and the recording head It is determined by the structure of the ink liquid path.

FIG. 6 is a diagram showing the dependency of the ejection amount on the preheat pulse. In FIG. 6, V ₀ is P ₁ = 0 [μs
c], and this value is determined by the head structure. Incidentally, V ₀ in this embodiment is the environmental temperature T _R = 25.
In the case of ° C., V ₀ = 18.0 [ng / dot].

[0039] As indicated by the curve a in FIG. 6, in accordance with an increase in the pulse width P ₁ of the pre-heat pulse, the ejection amount V _d is increased with a linearity from Pasuru width P ₁ is 0 to P _1LMT In the range where the pulse width P ₁ is larger than P _1LMT , the change loses linearity and saturates and becomes maximum at the pulse width P _1MAX .

[0040] Thus, the range of variation of the ejection amount V _d relative to the change in the pulse width P ₁ until the pulse width P _1LMT showing the linearity is easily control the discharge amount by changing the pulse width P ₁ It is effective as a range that can be performed. _Incidentally , in this embodiment shown by the curve a, P _1LMT = 1.87 (μs), and the discharge amount at this time is V _LMT = 24.0 [ng / do].
t]. The pulse width P _1MAX when the discharge amount V _d is saturated is P _1MAX = 2.1 [μs],
The discharge amount V _{MAX at} this time was 25.5 [ng / dot].

[0041] When the pulse width is greater than P _1MAX, the ejection amount V _d is smaller than V _MAX. This phenomenon is that when a preheat pulse having a pulse width in the above range is applied, fine bubbling (a state immediately before film boiling) occurs on the electrothermal transducer, and the next main heat pulse is generated before the bubble disappears. The ejection rate is reduced by the applied micro bubbles, which disturb the bubbling by the main heat pulse. This region is called a pre-foaming region, and in this region, it becomes difficult to control the discharge amount via a preheat pulse.

If the slope of a straight line indicating the relationship between the discharge amount and the pulse width in the range of P ₁ = 0 to P _1LMT [μs] shown in FIG. 6 is defined as the preheat pulse dependence coefficient, the preheat pulse dependence coefficient is:

[0043]

(Equation 1)

Is as follows. This coefficient K _P is determined by the head structure, driving conditions, physical properties of the ink, and the like irrespective of the temperature. That is, curves b and c in FIG. 6 show the case of another print head, and it can be seen that the ejection characteristics change when the print head is different. As described above, since the upper limit value _P1LMT of the preheat pulse P1 is different when the printheads are different, the discharge amount control is performed by setting the upper limit value _P1LMT for each printhead as described later. Incidentally, in the recording head and the ink indicated by the curve a in the present embodiment, K _P = 3.209 [ng / ng].
μsec · dot].

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

FIG. 7 is a diagram showing the temperature dependence of the discharge amount. As shown in curve a of Figure 7, the ejection amount V _d relative to the increase in environmental temperature T _R of the recording head (= head temperature T _H) increases linearly. If the slope of this line is defined as a temperature-dependent coefficient, the temperature-dependent coefficient:

[0047]

(Equation 2)

Is as follows. This coefficient K _T does not depend on the driving conditions, but is determined by the structure of the head, the physical properties of the ink, and the like. FIG.
Also, curves b and c show the cases of other recording heads.
Incidentally, in the recording head of this embodiment, K _T = 0.3 [n]
g / ° C. · dot].

As is clear from the description with reference to FIGS. 6 and 7, when the electrothermal transducer is driven by the divided pulse to perform ejection, the amount of the ejected ink droplet is determined by the first pulse of the divided pulse. Depending on the width,
Generally, the amount of ejected ink droplets differs depending on the ink temperature at that time, that is, the environmental temperature. Therefore, when printing, by modulating the initial pulse width of the divided pulse according to the environmental temperature, the amount of ink droplets to be ejected is kept constant so that the density unevenness does not occur in the printed image. Can be FIG. 8 shows the width P of the first pulse of the divided pulse.
₁ shows the state of modulation. As shown in FIG. 8, one of the drive signals 1 to 11 is selected according to the detected environmental temperature.

An ejection recovery process according to an embodiment of the present invention performed in the above-described ink jet recording apparatus will be described below.

In the discharge recovery process of this embodiment, the non-suction time, the thickening time, and the no-cap time are set, and the mode of the recovery process is changed according to these times. These times are managed by the timer 807 shown in FIG. Here, the non-suction time is the time elapsed since the last suction, the thickening time is the time elapsed since the last empty discharge, and the no-cap time is the time elapsed since the capping was released. Say each time you did. In the present example, each of the above times is detected when the power is turned on, and the recovery processing described with reference to FIG. 9 and the like is performed.

A suction operation is performed as one mode of the recovery processing of this embodiment. In the suction operation, the ejection opening surface of the recording head in the cartridge IJC shown in FIG.
And a negative pressure is generated by the pump 8500. As a result, bubbles and thickened ink in the recording head are sucked and discharged from the ejection ports. At the same time, in the ejection recovery processing of this example, idle ejection may be performed. When the suction operation is completed, the ejection port surface dirty with the ink remaining at the time of the suction is replaced with a blade 804 similarly provided adjacent to the cap unit 8300 shown in FIG.
To clean this surface. Thereafter, idle discharge is performed, and the thickened ink and dust pushed into the discharge port by wiping are discharged.

When these discharge recovery processes are performed when the power is turned on, if only a fixed discharge recovery process is set corresponding to each of the above-mentioned times, an appropriate recovery operation may not be performed. For example, when control is performed such that only the suction operation is performed when the non-suction time exceeds a predetermined time, if the time is considerably long, it is possible to completely remove the thickened ink in the recording head only by the suction operation. It can be difficult. In such a case, it is preferable to use the idle discharge together, and by raising the temperature of the ink by the idle discharge, the viscosity of the ink can be reduced and the ink discharge by suction can be facilitated. As described above, in the embodiment of the present invention described below, control is performed so that various ejection recovery processes can be performed according to the plurality of times described above. Hereinafter, the ejection recovery processing will be described.

FIG. 9 is a flowchart showing the sequence of the ejection recovery process according to the first embodiment of the present invention. Hereinafter, the recovery operation at the time of power ON will be described according to this sequence.

This processing is performed in parallel with the warm-up processing accompanying the power-on of the copier. When the power is turned on, the timer 807 in the main body of the recording apparatus shown in FIG. The measured no-cap time is detected. That is, in this example, when the capping by the cap unit 8300 shown in FIG. 1 is released, the time measured by the timer 807 at that time is stored in the RAM 805, and the time measured by the timer 807 when the power is turned on is stored. Is calculated, and the time is detected as the no-cap time. At the same time, the contents of the capping flag are detected. The content of the capping flag is set to “1” when the capping is performed by the cap unit 8300. If the flag is “1” when the power is turned on, that is, if the capping state is established, the capping is normally performed. The process proceeds to step S93, and the non-suction time and the thickening time are detected. The non-suction time and the thickening time store the time of the last suction operation and the last discharge (including idle discharge), respectively, as in the case of the no-cap time. Determined by

After the detection of these times, step S94
Then, the recovery operation is performed with reference to the preset table 1. Hereinafter, this recovery operation will be described.

FIG. 10 is a conceptual diagram of the table 1. This table is classified according to the above-mentioned non-suction time and thickening time.

As is clear from Table 1, the non-suction time is classified on the basis of 5 days, and if this time is 5 days or more, the suction operation is performed. The suction pressure of these suction operations differs depending on the thickening time, and the longer the time, the larger the suction pressure. In addition to this suction,
Perform idle discharge of all discharge ports. This idle discharge has a portion where the operation time overlaps that of suction, and the number of discharges is set so as to increase according to the thickening time.

The reason why the reference value of the non-suction time is set to 5 days is that when the recording head is left in the apparatus main body, if it exceeds 5 days, in the worst case, a relatively large amount is set in the common liquid chamber of the recording head. This is because bubbles may stay and ink ejection may become impossible or unstable. Further, the reason why the suction pressure and the number of idle discharges are increased as the thickening time increases when performing suction is due to the following reason. The longer the non-ejection time (thickening time), the greater the degree of thickening of the ink in the ink path and the like.
The pressure required for suction is large. Also, the increase in the number of ejections of the idle ejections is caused by the evaporation of the ink moisture due to standing, and the change in the ink density caused by the increase in the viscosity extends to the ink in the common liquid chamber of the recording head. If the number of idle ejections at that time remains unchanged, it is not possible to discharge even the ink whose density has changed, and as a result, there is a high possibility that density unevenness will occur in a recorded image or the like.

Regarding the classification of the thickening time, if this time is 10 days or more, after the suction accompanied by the idle discharge operation is completed, the recovery operation is interrupted for about 1.5 seconds. Then, all ejection openings of the recording head are ejected at 4 KHz. This is because the ink in the common liquid chamber becomes considerably thick when the non-discharge time is as long as 10 days or more, and the ink in the common liquid chamber cannot be easily discharged by the normal idle discharge operation. Perform an ink discharge operation with a short interruption. According to the ink discharge operation with this interruption,
During this interruption, convection occurs in the common liquid chamber due to the ink flow and the like generated by the first discharge, and the degree of thickening of the ink in the common liquid chamber is made uniform by this convection. The ink is discharged.

In the process of step S94, if the non-suction time is less than 5 days, as apparent from Table 1 shown in FIG. 10, the suction operation is basically not performed, and the recovery operation is performed only for the idle discharge. That is, for 5 days after the last suction operation, relatively large stagnation of air bubbles that would cause unstable ejection does not occur. Therefore, idle discharge necessary for stable ejection of ink and no occurrence of density unevenness in a recorded image is performed. Therefore, the number of ejections is set to be larger than the number of empty ejections performed simultaneously with the above-described suction operation. In practice, as shown in Table 1 of FIG.
0 shots, 1000 shots at 4 KHz on the first to third days.

When the thickening time is 3 to 5 days, 3,000 empty ejections are performed at all the ejection ports at 4 KHz. The driving conditions at this time are not the driving for modulating the pulse axis according to the recording head temperature as described above, but the pulse width is fixed. Further, even when the drive conditions for ejection specific to the print head are set for each print head as in this example, and the ejection is performed in accordance with the data, the main body side performs this idle ejection. The idle discharge is performed under a preset driving condition.

The purpose of this idle discharge is to detect non-discharge. That is, idle discharge is performed to detect whether or not there is a non-discharge in the discharge port in the recording head, and therefore, the heat generated from the discharge heater is made constant. The non-ejection detection method calculates the difference between the print head temperatures before and after the idle ejection, and determines whether the temperature difference is equal to or higher than a predetermined temperature.

In this embodiment, when this temperature difference, that is, when the temperature rise of the recording head is 20 ° C. or more, it is determined that there is non-ejection, and the recovery operation is automatically performed. This recovery operation performs a suction operation, and does not perform idle discharge at the same time as suction.

According to the above-described recovery operation with reference to Table 1, it is possible to output a stable and stable image without consuming excessive ink.

Next, when the no-cap time is 0 or more in step S92 of the procedure shown in FIG. 9, that is, when the no-cap flag is "0" (when capping is not performed), a non-cap time is set in step S95. After detecting the suction time, a recovery operation according to Table 2 shown in FIG. 11 is performed in step S96. This recovery operation will be described below.

If the recording head is not capped, the recovery operation is changed according to the values of the no-cap time and the non-suction time. Here, the reason why the thickening time is not referred to for this recovery operation is that the evaporation of ink moisture through the ejection port when the recording head is not capped is much more than when the capping is performed, This is because the viscosity of the ink in the vicinity and the like is severe.

As shown in Table 2 in FIG. 11, the reference time for classifying the non-suction time is 5 days, and if the non-suction time is 5 days or more, suction is always performed. 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 dust or the like may block the discharge port when the recording head is in the no-cap state, and it is possible to assume that the ink cannot be recovered only by idle discharge. Another reason is that the proportion of bubbles mixed from the discharge port increases. The recovery operation shown in Table 2 of FIG. 11 is basically the same as the recovery operation for the normal cap shown in Table 1 of FIG.

In the above-described first embodiment, the recovery operation is performed by referring to the table in accordance with the combination of the durations of the respective states of the recording head that affect the ejection. The second embodiment of the present invention In the example, instead of referring to the table, the recovery operation is performed according to the value of the function using each time as a variable. Hereinafter, this recovery operation will be described.

Basically, the amount of suction in the suction operation is Q, the number of discharges in the idle discharge for removing thickened ink near the discharge ports is K _NZ , and the high concentration is mainly in the common liquid chamber of the print head. The number of ejections in the idle ejection for removing the _dead ink is K _EK, and these are treated as a function by three variables of the non-suction time t _q , the thickening time t _z0 , and the no-cap time t _n0 . The sum is performed as a recovery operation.

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

[0072]

(Equation 3)

That is, the suction amount Q is a function g ₁ (t _q ),
It is obtained by the max operation of g ₂ (t _n0 ). That is,
The suction amount Q is defined by the larger one of Q ₁ = g ₁ (t ₂ ) and Q ₂ = g ₂ (t _n0 ). Here, k ₁ and k ₂ are coefficients, and T _q and T _N0 are fixed values. For example, _Tq can be 5 days and T _N0 can be 1 hour.
Also, the functions g ₁ and g ₂ can be qualitatively the same function. As a specific example, Q ₁ = g ₁ (t _q ) is shown in FIG.
Shown in

[0074] Here, the minimum suction amount is set, first, set suction amount Q ₁ is a 0 when performing a recovery operation is actually, because there is no effect. In other words, the main purpose of suction is to remove air bubbles in the discharge port and the common liquid chamber and to discharge the air normally. Since the air bubbles have a certain size, it is necessary to remove a certain amount of air bubbles. This is because the suction must be performed. Here Q _1min =
The amount was 0.05 g.

The reason why the maximum suction amount is set is that even if a larger amount is sucked, it is not so effective. That is, if the ink amount about twice the volume of the common liquid chamber is sucked, the ink in the common liquid chamber is almost refreshed. Here, Q _1max = 0.15 g. Therefore,
Function g ₁ is defined is not to exceed a certain value Q _1max.

Next, the number of discharges K _nz in the idle discharge for removing the thickened ink near the discharge port is expressed by the following _{equation (} 4).

[0077]

K _nz = max [f ₁ (t _z0 ), f ₂ (t _n0 )] Here, the functions f ₁ and f ₂ are qualitatively the same, and f
₁ (t) = f ₂ (kt): k can be represented by the relationship of a coefficient. For example, K _nz = f ₁ (t _z0 ) is a function specifically shown in FIG.

Here, the rising slope of K _nz = f ₁ (t) is determined as follows. That is, the evaporation rate of the ink water in the ejection port is relatively large at the beginning, and thereafter the evaporation rate decreases due to the ink thickened by evaporation, and the viscosity increase of the ink in the ejection port progresses according to the evaporation rate. For this reason, the number of idle discharges is determined according to the above-mentioned tendency of evaporation.

The reason _why the maximum value is set for the number of discharges Knz is that a predetermined recovery is possible if the number of discharges is equal to this number. Specifically, the maximum value is set to 1,000.
Further, the driving frequency of the idle discharge is the maximum driving frequency of 4 KH.
z.

Next, the number of ejections K _EK in the idle ejection for removing the highly concentrated ink in the common liquid chamber of the recording head.
Is represented by Equation 5.

[0081]

K _EK = m · h (A−Q) · max [f ₃ (t _z0 ), f ₄ (t ⁿ⁰ ), f ₅ (t _q )] where m is a coefficient and A is It is a constant value. A is set to a value slightly larger than the suction amount Q obtained by Expression 3. H is a function of the suction amount Q, and in this example, h (x) = x
Function. That is, h (AQ) = AQ, and when Q = 0, mh (AQ) = mA ≒ 1. This is because when Q = 0, that is, when suction is not performed, idle discharge determined by K _EK = max [f ₃ , f ₄ , f ₅ ] is performed. Therefore, since mA = 1, A =
In the case of 0.17 (g), m = 1 / 0.17 (1 /
g).

Therefore, when the suction amount Q is the maximum, that is, when Q _max = 0.15 (g) as described above, K _EK =
0.02 / 0.17 × max [f ₃ , f ₄ , f ₅ ), and the idle discharge of the discharge number determined by this number is performed simultaneously with the suction.

As described above, the reason why the number of idle discharges in the case of suction is small is that ink having a high density in the common liquid chamber can be sufficiently removed by the suction, and the idle discharge is performed to assist the removal. Because it is a thing.

FIG. 14 shows a specific example of the functions f ₃ (t _z0 ) and f ₄ (t _n0 ).

The setting of these functions f ₃ and f ₄ is also performed by the function f ₁
The same is done. That is, as in the case of the ink near the ejection port, the ink in the common liquid chamber thickens, so that it becomes difficult for the ink water to evaporate after a certain period of time, so that the ink concentration in the common liquid chamber also saturates. come. Therefore, the number of ejections is set according to the tendency of the density.

The function f ₅ (t _q ) is shown in FIG.

This function is defined as follows. That is, until the function f ₅ a certain period of time is, the value increases almost linearly. This is because when suction is not performed, the ink in the portion where the flow of ink is stagnant in the common liquid chamber may thicken, and this thickening spreads in the common liquid chamber almost in proportion to the non-suction time. Therefore, the number of ejections in proportion to the spread of the thickening is to refresh the thickened ink to some extent.

Here, the maximum value of K _EK was set to 9000 shots. When the number of shots exceeds 3,000, an interval of about 0.5 seconds is provided to perform idle discharge. This is because the idle discharge is set to the maximum drive frequency of 4 KHz, and if the continuous discharge is performed without an interval, the recording head temperature may rise rapidly and may cause unstable discharge. One purpose is to prevent, another is
By providing a certain interval between the ejections, the thickened ink in the liquid chamber can be effectively removed.

As described above, for a plurality of states in the recording head, an optimum recovery operation can be performed by performing a recovery operation based on the value of a multivariable function using the time during which each state continues as a variable. It has become possible. In particular,
Since a table is not used unlike the first embodiment, continuous values can be set, and a more appropriate recovery operation can be performed. That is, compared to the case of the table, unnecessary ink consumption is not required, and the ink of the recording head can be refreshed reliably. Further, since a table is not used, the memory can be reduced.

The functions of 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 represented as a linear function. By doing so, the calculation of the CPU in the main body can be simplified.

Further, by changing the function and its coefficient depending on the color and type of ink, a more appropriate recovery operation can be performed.

Further, these are, for example, C, M, Y, B
When applied to a full-color printer or the like for four colors of k, each of them may have a function independently depending on the ink color.

In addition, although the non-suction time, the thickening time, and the no-cap time have been described above, any other time may be used as long as it is an index of the discharge state of the recording head.

(Others) It should be noted that the present invention includes a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for performing ink ejection, particularly in an ink jet recording system. An excellent effect is obtained in a recording head and a recording apparatus of a type in which the state of ink is changed by the thermal energy. This is because according to such a method, it is possible to achieve higher density and higher definition of recording.

The typical configuration and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method is a so-called on-demand type,
Although it can be applied to any type of continuous type, in particular, in the case of the on-demand type, it can be applied to a sheet holding liquid (ink) or an electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to the recorded information and giving a rapid temperature rise exceeding the nucleate boiling, heat energy is generated in the electrothermal transducer, and film boiling occurs on the heat acting surface of the recording head. Liquid (ink) corresponding to this drive signal on a one-to-one basis.
This is effective because air bubbles inside can be formed. The liquid (ink) is ejected through the ejection opening by the growth and contraction of the bubble to form at least one droplet. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

The configuration of the recording head is not limited to a combination of a discharge port, a liquid path, and an electrothermal converter (a linear liquid flow path or a right-angled liquid flow path) as disclosed in the above-mentioned specifications. U.S. Pat. No. 4,558,333 and U.S. Pat. No. 44,558 which disclose a configuration in which a heat acting portion is arranged in a bending region.
A configuration using the specification of Japanese Patent No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Application Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an aperture for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration is based on JP-A-59-138461, which discloses a configuration corresponding to a discharge unit. That is, according to the present invention, recording can be reliably and efficiently performed regardless of the form of the recording head.

Further, 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 on which a recording apparatus can record. Such a recording head may have a configuration that satisfies the length by a combination of a plurality of recording heads, or a configuration as one integrally formed recording head.

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

It is preferable to add recovery means for the printhead, preliminary auxiliary means, and the like provided as a configuration of the printing apparatus in the present invention since the effects of the present invention can be further stabilized. . If these are specifically mentioned, capping means for the recording head, cleaning means, pressurizing or suction means, preheating means using an electrothermal transducer or another heating element or a combination thereof, Performing a preliminary ejection mode in which ejection is performed separately from printing is also effective for performing stable printing.

Further, the types and the number of recording heads to be mounted are, for example, not only those provided for one color ink but also plural inks having different recording colors and densities. A plurality may be provided. That is, for example, the printing mode of the printing apparatus is not limited to the printing mode of only the mainstream color such as black, but may be any of integrally forming the printing head or a combination of a plurality of printing heads. The present invention is also extremely effective for an apparatus provided with at least one of full colors by color mixture.

In addition, in the embodiments of the present invention described above, the ink is described as a liquid. However, an ink which solidifies at room temperature or below and which softens or liquefies at room temperature, or an ink jet system In general, the temperature of the ink itself is controlled within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. Anything can be used. In addition, the temperature rise due to thermal energy can be positively prevented by using it as energy for changing the state of the ink from a solid state to a liquid state, or ink that solidifies in a standing state to prevent evaporation of the ink can be used. In any case, the ink is liquefied by the application of the thermal energy according to the recording signal, and the ink is liquefied, and the liquid ink is discharged. The present invention is also applicable to a case where an ink that liquefies for the first time by energy is used. In such a case, the ink is disclosed in JP-A-54-56847 or JP-A-60
As described in JP-A-71260, a configuration may be adopted in which a liquid or solid substance is held in a concave portion or through hole of a porous sheet and opposed to an electrothermal converter. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

Further, the form of the ink jet recording apparatus of the present invention is not limited to those used as image output terminals of information processing equipment such as computers, copying apparatuses combined with readers and the like, and facsimile apparatuses having a transmission / reception function. It may take a form.

[0103]

As is apparent from the above description, according to the present invention, for example, the time since the last ejection in the recording head, the time since the last suction, and the capping are not performed. The amount of suction, the number of idle discharges, and the like in the discharge recovery processing are controlled in accordance with each time when a plurality of states continue, such as time.

As a result, an appropriate recovery operation is performed, and stable ejection and high-quality image can be obtained.
Ink consumption accompanying the recovery operation can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a perspective view of a recording head cartridge mounted on the ink jet recording apparatus shown in FIG.

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

FIG. 4 is a block diagram showing a control configuration in the ink jet recording apparatus shown in FIG.

FIG. 5 is a waveform diagram showing a recording head drive signal waveform for ejection in the ink jet recording apparatus shown in FIG.

FIG. 6 is a diagram illustrating a relationship between a drive signal waveform and an ink ejection amount illustrated in FIG. 5;

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

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

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

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

11 is a conceptual diagram of a table used in the processing shown in FIG.

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

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

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

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

(57) [Claims] 1. An ink jet recording apparatus that performs recording by discharging ink, a recording head for discharging ink, a discharge recovery unit for performing a discharge recovery process of the recording head, and an ink discharge of the recording head. Means for measuring the time during which the plurality of states in the ink jet recording apparatus continue to affect the ink jet recording apparatus, and the ejection recovery means according to a combination of the respective times during which the plurality of states continue as measured by the time measuring means. An ink jet recording apparatus comprising: a recovery control unit configured to control an ejection recovery process performed by the printer. 2. The printing apparatus according to claim 1, wherein the ejection recovery unit includes an ink suction unit for sucking ink from the recording head, an idle ejection unit for performing ejection that is not related to recording of the apparatus, and an ink ejection port of the recording head. And a capping unit for covering the part where the recording head has been ejected.
The time since the last suction by the suction means,
2. The ink jet recording apparatus according to claim 1, wherein the time at which the portion where the ink ejection port is provided is not covered by the capping unit. 3. The recovery control unit according to claim 1, wherein the recovery control unit controls the discharge recovery processing by referring to a table based on respective times during which the plurality of states continue. Ink jet recording device. 4. The ink-jet apparatus according to claim 1, wherein the recovery control unit controls the ejection recovery processing based on a function that uses, as variables, respective times during which the plurality of states continue. Recording device. 5. The ink jet recording apparatus according to claim 1, wherein the recording head uses thermal energy to generate bubbles in the ink, and discharges the ink based on the generation of the bubbles. Recording device.