JPH0592579A - Ink jet recording apparatus - Google Patents

Abstract

PURPOSE:To perform necessary and sufficient emission restoring operation with respect to a plurality of individual recording heads emitting inks different in concn. CONSTITUTION:An empty emission control circuit 31 of dark ink heads allowing recording heads 22CK, 22MK, 22YK, 22KK for emitting dark inks to perform the empty emission not participated in recording and an empty emission control circuit 32 of light ink heads allowing recording heads 22CU, 22MU, 22YU, 22KU for emitting light inks not participated in recording are constituted in a separated state and, at each time when the standing times corresponding to ink densities are elapsed, the control circuits 31,32 are operated at different intervals.

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 for recording using plural kinds of inks having different densities.

[0002]

2. Description of the Related Art As an ink jet recording apparatus which obtains a high gradation by using a plurality of kinds of inks having different densities, a Japanese Patent Publication No. 2-1490 previously proposed by the present applicant has been proposed.
There is one disclosed in No. 5. According to such a device, 1
It is also possible to express gradations that cannot be expressed only with different types of dots.

On the other hand, some ink jet recording apparatuses perform an ejection recovery process for improving the ink ejection state. There are the following three a, b and c as examples of the method of the ejection recovery process.

A. In order to prevent non-ejection due to viscosity increase due to change of ink with time, a method of ejecting ink from nozzles of all recording heads to the outside of the image forming area at predetermined intervals (hereinafter referred to as "idle ejection"). ).

B. Ink is supplied to the ink ejection port in order to remove thickened ink near the ink ejection port of the recording head that is left for a long period of time and to remove adhering substances to the ink ejection port that cause ink ejection failure. A method in which forced flow means such as a pump is provided in the supply path so that the ink existing in the vicinity of the ink ejection openings of all recording heads is forced to flow.

C. Ink is ejected at high duty,
When printing or the like is repeated, ink droplets or the like that bounce off the recording medium may adhere to the ejection openings of the recording head, causing ink ejection failure.Therefore, prevent such ejection failure. A method in which a flexible blade that comes into contact with the ejection openings of the recording head is provided, and the vicinity of the ejection openings of all the recording heads is similarly wiped by the blade to wipe off the adhered droplets.

[0007]

However, by adopting the above methods a, b and c in an ink jet recording apparatus for recording using a plurality of types of inks having different densities, it is possible to apply to all recording heads. When the same ejection recovery process is performed, there are the following problems.

[Problem in the case of method a] With dark ink and light ink, the rate of change in viscosity over time is faster for dark ink, so the recording head for dark ink ejection has a lighter ink ejection speed. It is necessary to perform idle ejection at a shorter interval than the recording head for recording.

However, if all the print heads are idle-discharged at a short interval required for the dark-ink discharge print head, the frequency of idle discharge is excessive for the light-ink discharge print head. Therefore, there is a problem in that the amount of waste ink increases due to unnecessary blank discharge.

[Problem in the case of the method (b)] In the dark ink and the light ink, the viscosity changes with time with respect to the viscosity of the dark ink is faster. Therefore, when recording such as printing after leaving for a long time,
With respect to the recording head for ejecting dark ink, ink may not be ejected unless the ink in the head is forced to flow, but with regard to the recording head for ejecting light ink, the ink in the head is forced to eject. Ink may be ejected without causing a specific flow.

Therefore, for all recording heads,
Similarly, when the forced flow of the ink occurs, unnecessary time forced loss of the ink with respect to the recording head for ejecting the light ink causes a time loss, and the forced flow of the ink causes waste ink. There is a problem that the leaked ink will be generated more than necessary.

[Problem in the case of method c] Since the duty of the print head corresponding to the ink density varies greatly depending on the density of the ink, the ink is ejected at a high duty to perform printing such as printing. If the same wiping operation is performed for all the print heads in accordance with the heads, more than necessary wiping operation is performed for the dark ink ejection print heads for printing such as printing with low duty. Therefore, there are problems that the deterioration of the blade is accelerated and the fatigue of the surface of the ink ejection port is accelerated.

It is an object of the present invention to provide an ink jet recording apparatus capable of performing an optimum ejection recovery process for each of a plurality of recording heads ejecting ink of different densities.

[0014]

The inkjet recording apparatus of the present invention is an inkjet recording apparatus for performing recording by ejecting a plurality of types of ink having different densities from a plurality of recording heads corresponding to the respective inks. Of the recording head, each of the plurality of recording heads, the processing means for performing an ejection recovery process for improving the ejection state of each ink, the processing means, in accordance with the density of the ink ejected by each of the plurality of recording heads, It is characterized in that the conditions of the ejection recovery processing of the plurality of recording heads are made different.

[0015]

In the ink jet recording apparatus of the present invention, a plurality of recording heads ejecting inks of different densities are subjected to the ejection recovery process according to the densities of the ejected inks, so that it is necessary to match the characteristics of the dark and light inks. Stable ejection is always performed by sufficient ejection recovery processing.

As the above-mentioned ejection recovery processing, it is possible to employ any processing such as blank ejection for ejecting ink not involved in recording, forced flow of ink in the recording head, and wiping of the ink ejection port. It is also possible to combine these processes.

[0017]

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

(First Embodiment) FIGS. 1 to 4 are views for explaining a first embodiment of the present invention.

First, in FIG. 3 showing a recording section of a printer as an ink jet recording apparatus, 11 is a recording sheet as a recording medium, and a platen 13 and a pinch roller 14 are provided.
By the and, while being moved in the direction of the arrow 12, an image such as a print is recorded on the upper surface thereof. The driving force of the paper feed motor 15 is transmitted to the platen 13 via the gears 16 to 21 and rotationally drives the platen. Reference numeral 22 is a head unit mounted on the carriage 23, and heads 22YK, 22YU, 22MK, 22MU, 2 for ejecting respective dark, light inks of yellow, magenta, cyan and black.
It has 2CK, 22CU, 22KK and 22KU.
22YK and 22YU are recording heads for ejecting yellow dark ink and light ink, 22MK and 22MU are recording heads for ejecting magenta dark ink and light ink, and 22CK and 22CU are recording heads for ejecting cyan dark ink and light ink. , 22KK and 22KU
Is a recording head for ejecting black dark ink and light ink. Reference numeral 20 denotes a motor that drives a carriage 23 via a belt 26 spanned between rollers 27 and 28, and the carriage 23 moves in the direction of arrow 29 along rods 24 and 25.

Next, the ejection principle of the ink jet recording head used in the apparatus of this embodiment will be described.

A recording head applied to an ink jet recording apparatus generally applies a fine liquid discharge port (orifice), a liquid passage and an energy acting portion provided in a part of the liquid passage, and a liquid in the acting portion. Energy generating means for generating droplet forming energy.

As the energy generating means for generating such energy, an electromechanical converter such as a piezo element is used, or an electromagnetic wave such as a laser is radiated and absorbed in a liquid present therein to generate heat. There are ones in which the liquid droplets are ejected and flown by the action of, and ones in which the liquid is ejected by heating the liquid by the electrothermal converter.

Among them, a recording head used in an ink jet recording system for ejecting a liquid by thermal energy has a high density of liquid ejection ports (orifices) for ejecting recording liquid droplets to form flying liquid droplets. Since they can be arranged, it is possible to record with high resolution. In addition, the recording head using the electrothermal converter as the energy generating means can be easily made compact as a recording head as a whole, and the IC technology and the micro technology which have been remarkably improved in the technological progress and reliability in the recent semiconductor field. The advantages of processing technology can be fully utilized, making it long and flat (2
It is possible to provide an ink jet recording head which is easy to realize multi-nozzle / high-density mounting because it is easy to realize (dimensionalization), and has high mass productivity and low manufacturing cost.

An ink jet recording head manufactured through a semiconductor manufacturing process using an electrothermal converter as the energy generating means is generally provided with a liquid passage corresponding to each ink ejection port, and each liquid passage is provided with a liquid passage. An electrothermal converter is provided as means for applying thermal energy to the liquid that fills the liquid passage to eject the liquid from the corresponding ink ejection port to form flying droplets. The liquid is supplied from a common liquid chamber that communicates with each liquid passage.

Regarding the method of manufacturing the ink ejection section,
The applicant has sequentially laminated a solid layer for forming at least a liquid channel on a first substrate, an active energy ray-curable material layer used for forming at least a wall of the liquid channel, and a second substrate. Then, a mask is laminated on the second substrate, and an active energy ray is irradiated from above the mask to cure the active energy ray-curable material layer at least as a component of a liquid path, and further to a solid layer. And a method for removing an uncured portion of the active energy ray curable material layer from between two substrates to form at least a liquid path (Japanese Patent Laid-Open No. 62-2534).
No. 57).

FIG. 4 shows a schematic structure of the above-mentioned ink jet recording head. As is clear from this figure, the recording head 101 undergoes semiconductor manufacturing process steps such as etching vapor deposition and sputtering, and then the substrate 102 which is the first substrate.
It is composed of an electrothermal converter 103, an electrode 104, a cured active energy ray curable material layer 210 having a liquid path 110 and a top plate 106, which are formed on the above.

In such a recording head 101, however, the recording liquid 112 is supplied from the liquid storage chamber (not shown) into the common liquid chamber 108 through the liquid supply pipe 107.
109 is a connector for a liquid supply pipe. Common liquid chamber 108
The liquid 112 supplied into the inside of the liquid passage 110 is caused by the capillary phenomenon.
The ink is supplied to the inside, and a meniscus is formed at the ink ejection port 111 at the tip of the liquid path, so that the ink is stably held. Therefore, when the electrothermal converter 103 is energized, the liquid on the surface of the electrothermal converter is heated and a bubbling phenomenon occurs, and the energy of the bubbling ejects a droplet from the ink ejection port 111. With the configuration as described above, the discharge port density is 4
It was possible to form a multi-nozzle inkjet recording head with high-density liquid path piping such as 00 DPI.

In such an ink jet recording apparatus, when the volatile component in the ink evaporates from the ink ejection port due to being left for a long period of time and the viscosity of the ink increases and exceeds the upper limit of the ejectable viscosity of the recording head, the ink is ejected. The phenomenon of non-ejection occurs.

On the other hand, the following non-ejection prevention means is adopted.

First, the relationship between the standing time and the increase in ink viscosity will be described with reference to FIG. The change characteristics of the viscosity when using the dark ink is shown by the dotted line in FIG. The dark ink has an upper limit viscosity of η ₁ that can be ejected by evaporation of volatile components during the leaving time T ₁ , and when the dark ink is left for a longer period of time, it becomes impossible to eject the dark ink. .. Therefore, with respect to the dark ink, non-ejection can be prevented in advance by performing idle ejection every time the time T ₃ in FIG. 2, which is a leaving time shorter than T ₁ , elapses.

On the other hand, the light ink has a gradual increase in viscosity with evaporation of volatile components, and the relationship between the standing time and the ink viscosity changes as shown by the solid line in FIG. The standing time to reach a certain η ₁ is T ₂ , which is longer than T ₁ when using dark ink. Therefore, in the case of light ink used, by performing idle discharge each time the time T ₄ in FIG. 2 is a short standing time than T ₂ has elapsed, and thus it can prevent ejection failure in advance.

Therefore, in this embodiment, as shown in FIG. 1, the heads 22CK, 22MK, 22 for ejecting dark ink are provided.
YK and 22KK blank ejection control circuits 31 and light ink ejection heads 22CU, 22MU, 22YU and 2
It is configured separately from the 2 KU blank discharge control circuit 32.

The former idle discharge control circuit 31 causes the dark ink discharge heads 22CK, 22MK, 22YK, and 2 to be discharged every time the above-mentioned leaving time T ₃ elapses.
Drive circuits 33A, 33B corresponding to 2 KK,
33C and 33D are driven to discharge ink from each head toward the outside of the image forming area on the recording paper 11, for example, toward the ink receiver facing each head. Further, by the latter idle ejection control circuit 32, the drive circuits 34A, 34 corresponding to the light ink ejecting heads 22CU, 22MU, 22YU and 22KU, respectively, each time the above-mentioned leaving time T ₄ elapses.
B, 34C, and 34D are driven to eject ink from each head toward the outside of the image forming area on the recording paper 11, for example, toward the ink receiver facing each head. Reference numeral 35 is a timer for measuring the time left in the recording apparatus, and the control circuits 31 and 32 operate at the time intervals T ₃ and T ₄ based on the time measured. Therefore, these timers 3
5 and the control circuits 31 and 32 constitute a processing means 36 for performing head recovery processing.

As described above, in the case of the present embodiment, by performing the idle ejection of ink from the head at the timing according to the ink density, it is possible to eliminate wasteful consumption of ink. By the way, in the conventional case, since the dark ink and the light ink are not distinguished from each other and the blank ink is discharged every time T _{3 is} left, the frequency of the blank discharge to the light ink is increased more than necessary, and the ink is wasted. was there.

(Second Embodiment) In the above-described first embodiment, the dark ink head and the light ink head have different idle discharge intervals, but the idle discharge interval is common. The same effect can be obtained even if the driving conditions for the blank discharge are changed.

That is, the common interval of idle ejection is set to the leaving time T ₄ of FIG. 2 and the ink can be reliably ejected to the dark ink head even if the viscosity of the dark ink is η _2. It is driven so as to give such a large ink ejection energy. For example, in the inkjet recording described above, a large ink ejection energy is obtained by extending the width of the drive pulse of the electrothermal converter 103 (see FIG. 3), dividing the drive pulse, or increasing the drive voltage. You can In addition, for example, the number of drive pulses for blank ejection is set to about 50 for the light ink head, and is set to about several hundred for the dark ink head. It is also possible to lower the viscosity of the ink and to push out the thickened ink in the vicinity of the ejection port of the dark ink head.

(Third Embodiment) A more excellent effect can be obtained by making the dark ink head and the light ink head both have different idle discharge intervals and drive conditions for idle discharge. it can.

That is, by setting the idle discharge interval of the dark ink to the leaving time T ₃ and the idle discharge interval of the light ink to the leave time T ₄ , the viscosity of the ink when performing the idle discharge is made uniform, and the stable empty space is maintained. Although light can be ejected, the light ink has a longer standing time, so even if the light ink and the dark ink have the same viscosity in the vicinity of the ejection port, the light ink is In some cases, the amount of thickened ink to be pushed out is large due to the progress of evaporation to the inside. Therefore, as for the light ink head, the idle ink ejection interval is set longer than that of the dark ink head, and the number of drive pulses for the idle ejection is increased to eject a large number of air to eject the light ink head and the dark ink head. The ink states in the respective nozzles can be made the same.

(Fourth Embodiment) When the recording apparatus is left in a low humidity environment for about one week or more, the water component and the solvent component in the ink evaporate, the ink viscosity increases, and the evaporation further progresses. Since the dye dissolved in the ink is deposited and fixed and clogs the nozzle, a supply recovery system as shown in FIG. 5 is configured to remove the fixed matter.

FIG. 5 shows a supply recovery system for one recording head 22. After the valve 136 is closed, the ink in the sub tank 134 is supplied to the supply path 1 by the gear pump 131.
32 to the recording head 22, and the recording head 2
Along with the ink sent from 2, the clogged foreign matter is pushed out from the ejection port. The ink leaked from the ejection port is removed by a cleaning unit (not shown) for cleaning the surface of the ejection port. Such a series of operations is called a pressure recovery operation.

During recording operation such as printing, the valve 1
36 is opened, and ink is supplied to the recording head 22 through the ink supply path 1233.

The necessity of the pressure recovery operation differs between the dark ink and the light ink. Therefore, the reason why the necessity is different will be described based on FIGS. 7 to 9.

The ink composition is, for example, 30% diethylene glycol DEG, 4% dark ink for dye (FB2 as an example of BK ink (black ink)), 1% light ink, and the rest water. First, the composition of dark ink is
As shown in FIG. 7, when the composition before standing is left for 1 week,
The composition is 10% water, 25% diethylene glycol DEG, and 4% dye. As a result of the experiment, the solubility of the dye is
Only 3% of the dye dissolved in a solution containing 10% of water and 25% of diethylene glycol DEG, and the dye was deposited as shown in FIG. 8 after leaving the dark ink for 1 week. On the other hand, in the composition of the light ink, as shown in FIGS. 9 and 10, after standing for 1 week, water was 10%, diethylene glycol DEG was 25%, and the dye was 1%, and the dye did not deposit.

Therefore, in the case of the dark ink, after leaving for 1 week, it is necessary to remove the deposited dye by the above-mentioned pressure recovery operation before the recording operation such as printing, while in the case of the light ink, Before the recording operation such as the printing after left for one week, the pressure recovery operation is not particularly necessary, and it is sufficient to perform, for example, the above-mentioned idle discharge about 100 times.

Therefore, in the case of this embodiment, it is necessary for the light ink head by performing the pressure recovery operation of the light ink head for a time shorter than that of the dark ink head every predetermined standing time such as one week. Waste of the leaked ink is eliminated without performing the above recovery operation. Therefore, as shown in FIG. 6, the dark ink ejection heads 22CK, 22MK,
Control circuit 1 for 22YKK and 22KK pressure recovery operation
41 and light ink ejection heads 22CU, 22MU, 2
Control circuit 14 for pressure recovery operation of 2YU and 22KU
It is configured separately from 2. Reference numeral 143 is a timer for measuring the left time of the recording apparatus, and the control circuits 141 and 142 operate at a predetermined left time interval based on the time measured. Therefore, these timers 1
43 and the control circuits 141, 142 constitute a head recovery processing means 144.

The operation timing of the control circuits 141 and 142 may be shifted so that the dark ink head performs the pressure recovery operation at an interval shorter than that of the light ink head.

Further, the dark ink head is left for one week for pressure recovery operation, while the light ink head is left for one week for idle ejection in the above-described embodiment to recover the dark and light ink head. The processing method may be different.

Further, by sucking the ink from the ink ejection port of the recording head, foreign matter stuck in the ejection port may be removed as in the pressure recovery operation described above.

(Fifth Embodiment) Kind of dye of light ink,
Depending on the dye concentration and the configuration of the capping unit that caps the ejection port surface of the recording head during standing, the above-described pressure recovery operation may not be necessary for the light ink head.

In this case, only for the dark ink head, the gear pump 131 and the supply passage 132 as shown in FIG.
A recovery system including a valve 136 and the like is provided, and such a recovery system is not provided for the light ink head. By doing so, a simple structure can be obtained.

(Sixth Embodiment) The dark ink head and the light ink head have different ink viscosities after being left for the same time.
Since there is a high possibility that dye will be deposited only in the dark ink head, it is possible to configure different recovery means for the dark ink head and the light ink head.

For example, for the dark ink head, the pressure recovery system described above, which can recover even if the dye is deposited, is used, although the leaked ink is large and the device configuration is large. A suction recovery system using a suction pump and a capping unit, which has a small number and a small device configuration, is applied. In that case, the capping unit is capped on the ink ejection port of the light ink head, and sucks the foreign matter together with the ink from the ink ejection port by the suction force of the suction pump.

(Seventh Embodiment) FIG. 11 shows one of the same color inks among a plurality of sets of density recording heads for different ink colors.
The drive signal system for the pair of grayscale recording heads is shown as 22K and 22U. Here, it is assumed that the dark ink has a dye concentration about twice that of the light ink.

In FIG. 11, the density distribution processing unit 15
1 sorts an image signal into an image signal for dark ink and an image signal for light ink according to a shade distribution table as shown in FIG. 12, and sends each to the binarization processing unit 152. The binarization processing unit 152 binarizes the sent image signals and sends them to the corresponding head drivers 153K and 153U. Head driver 1
53K and 153U drive the corresponding recording heads 22K and 22U based on the input image signal to perform image recording.

In the density distribution table of FIG. 12, in order to reduce the graininess of the ink droplets within the recording range of the highlight portion where the image signal level is 127 or less, one by one.
The number of dots of only light ink is increased according to the image signal level so that one dot is not conspicuous. After the image signal level exceeds 127, for example, and the light ink dots are filled up, dark ink dots are added in accordance with the image signal level, and the light ink dots at the recording position where the dark ink dots are printed are also added. Thin out.

When the dark / light ink head is driven using such a dark / light distribution table, the duty of the light ink head 22U becomes higher than that of the dark ink head 22K. For example, when an image signal with an average of 30% duty was input, the duty ratio of the dark ink and the light ink was about 1: 4.

FIG. 14 shows recording heads 22YK and 22Y in the same ink jet recording apparatus as that shown in FIG.
U, 22MK, 22MU, 22CK, 22CU, 22K
FIG. 16 is a plan view of K and 22 KU, and a blade 16 made of polyurethane or the like having a free length of about 4 mm is provided on the apparatus main body side at the home position set outside the printing area on the left side of the drawing.
One end of 1 is fixed. The blade 161 is arranged so that the other end of the blade 161 penetrates in the direction of the ejection port surface of the recording head by about 1 mm. As shown in FIG. The blade 161 wipes the surfaces of the ink ejection ports when moving in the direction of the arrow 29. In this way, when the ink ejection port surfaces of the eight heads are wiped by one blade 161, in order to avoid color mixture of ink, before the recording operation such as printing after the wiping, outside the printing area. About 200 shots of the above-mentioned blank discharge are performed on each of the eight print heads.

In the present embodiment, as shown in FIG. 13, dark ink ejecting heads 22CK, 22MK, 22.
Wiping control circuit 171 for YK and 22KK
And heads 22CU, 22MU, 22 for ejecting light ink
Wiping control circuit 172 for YU and 22KU
And the respective control circuits 171 and 172 are
The recording apparatus operates at a predetermined leaving time interval based on the time measured by the timer 173 that measures the time allowed to stand. The timer 173 and the control circuits 171 and 172 form a head recovery processing unit 174.

Therefore, in the case of the present embodiment, two wiping modes are selected in response to the light ink head having a print duty about several times that of the dark ink head, as described above.

In the first wiping mode, as shown in FIG. 15, only the dark ink head is retracted in the direction of arrow 162 by using a selective head slide means (not shown), and the blade 161 is used to eject the ejection surface of the light ink head. It is a mode to wipe only. On the other hand, in the second wiping mode, as shown in FIG. 14, all the dark and light ink heads are wiped. The selection of these two wiping modes is automatically switched by the control circuits 171 and 172 according to the necessity of wiping the dark and light ink heads. During recording operations such as printing, the discharge port surfaces of the dark and light ink heads are returned to one line.

The frequency ratio between the mode of wiping all heads and the mode of wiping only the light ink heads is a predetermined ratio (eg,
1: 3) is set in advance.

Further, when wiping only the light ink head, it is sufficient to perform the above-mentioned blank discharge for color mixing prevention only on the light ink head.

(Eighth Embodiment) In the above-described seventh embodiment, the frequency ratio between the mode of wiping all the heads and the mode of wiping only the light ink head is fixed, but the present invention is not limited to this. It is not something that can be done.

The density distribution processing unit 15 of FIG. 11 described above.
In FIG. 1, when the grayscale image signal is distributed using the grayscale distribution table as shown in FIG. 12, the ratio of the dark and light image signals after the grayscale distribution largely changes depending on the input level of the image signal before the grayscale distribution. .. For example,
When the signal level before distribution is 127, the dark ink has a duty of 0%, whereas the light ink has a duty of 100%, and when the level is 255, the dark ink has a duty of 100%. As a result, the light ink has a duty of 0%. In this way, the distribution ratio of dark and light ink depends on the magnitude of the input level.

Therefore, in the present embodiment, the video signal (dark) and the image signal (light) after the light and shade distribution are respectively video counted, and when the count of the image signal (light) exceeds a predetermined set value, The light ink head is wiped, while the dark ink head is wiped when the count of the image signal (dark) exceeds a predetermined set value.

As a simpler configuration having the same function as this, for example, the image signal before the light and shade distribution is 0 to 12
The 7-level range and the 128-256 level range are separately video-counted, the ratio of the image signals after the light and shade distribution is calculated from these count values, and the dark ink head and the light ink head are calculated according to the ratio. It is possible to adopt a configuration in which the ratio of the wiping frequency with

FIG. 18 shows a configuration for video counting, comparing an image signal from the image signal processing circuit with a fixed signal (for example, 128 level) from the fixed signal generating circuit, and comparing the signal level with the fixed signal or more. The number of pixels of the image signal of 1 is counted by the counter 1, and the number of images of the image signal less than the level of the fixed signal is counted by the counter 2.

The wiping of the light ink head is
It is performed every time t _{1 in} the following formula (1) (k ₁ is a predetermined value).

[0069]

[Equation 1]

The wiping of the dark ink head is performed every time t ₂ of the following equation (2) (k ₂ is a predetermined value).

[0071]

In Equation 2] t ₂ = k ₂ × (count value of the counter 1) (2) (a ninth embodiment) The seventh embodiment described above, in order to wipe only light ink head, dark ink head only However, the present invention is not limited to this.

In this embodiment, as shown in FIGS. 14 and 15, blades (161KU to 161YK) corresponding to the respective heads 22YK to 22KU are provided, and in the mode of wiping all the heads, FIG. As shown in, all heads are moved in the direction of arrow 29 while all blades are in contact with the corresponding heads. On the other hand, in the mode of wiping only the light ink head, as shown in FIG. 17, the blades corresponding to the respective dark ink heads are compared to the upper side in the drawing by the blade slide means (not shown) to make the light ink heads. All heads are moved in the direction of arrow 29 with the corresponding blades in contact with the light ink heads.

(Others) The present invention is particularly provided with means for generating thermal energy as energy used for ejecting ink (for example, an electrothermal converter or laser light) even in the ink jet recording system. The present invention provides excellent effects in a recording head and a recording apparatus of the type in which the thermal energy causes a change in ink state. This is because such a system can achieve high density recording and high definition recording.

Regarding its typical structure and principle, see, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740.
What is done using the basic principles disclosed in 796 is preferred. This method is a so-called on-demand type,
It can be applied to any of the continuous type, but especially in the case of the on-demand type, it can be applied to the sheet holding the liquid (ink) or the 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 nucleate boiling, heat energy is generated in the electrothermal converter, and film boiling is caused on the heat acting surface of the recording head. Liquid (ink) corresponding to this drive signal as a result
This is effective because bubbles can be formed inside. Due to the growth and contraction of the bubbles, liquid (ink) is ejected through the ejection openings to form at least one droplet. It is more preferable to make this drive signal into a pulse shape, because the bubble growth and contraction are immediately and appropriately performed, so that the ejection of the liquid (ink) with excellent responsiveness can be achieved. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. If the conditions described in US Pat. No. 4,313,124 of the invention relating to the rate of temperature rise on the heat acting surface are adopted, more excellent recording can be performed.

As the constitution of the recording head, in addition to the combination constitution of the discharge port, the liquid passage, and the electrothermal converter (the straight liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned respective specifications. U.S. Pat. No. 4,558,333, U.S. Pat. No. 44, which discloses a configuration in which a heat acting portion is arranged in a bending region.
The configuration using the specification of No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters, and an opening for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration corresponding to the ejection portion is disclosed in Japanese Patent Laid-Open No. 59-138461. That is, according to the present invention, recording can be surely 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 which can be recorded by the recording apparatus. 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 recording head integrally formed.

In addition, even in the case of the serial type as in the above example, the recording head fixed to the main body of the apparatus, or the electrical connection to the main body of the apparatus or the ink from the main body of the apparatus by being attached to the main body of the apparatus. 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 integrally provided in the recording head itself is used.

Further, as the constitution of the recording apparatus of the present invention, it is preferable to add ejection recovery means of the recording head, preliminary auxiliary means, etc. because the effects of the present invention can be further stabilized. Specifically, heating is performed by using a capping means, a cleaning means, a pressure or suction means for the recording head, an electrothermal converter or a heating element other than this, or a combination thereof. Examples thereof include a preliminary heating unit for performing the discharge and a preliminary discharge unit for performing discharge different from the recording.

Regarding the type and the number of recording heads to be mounted, for example, only one is provided corresponding to a single color ink, or a plurality of inks having different recording colors and densities are supported. A plurality of pieces may be provided. That is, for example, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but may be either integrally formed of the recording heads or a combination of a plurality of them. The present invention is also very effective for an apparatus provided with at least one of full-color recording modes by color mixing.

In addition, in the above-described embodiments of the present invention, the ink is described as a liquid, but an ink that solidifies at room temperature or lower and that softens or liquefies at room temperature may be used. Or, in the inkjet method, it is common to adjust the temperature of the ink itself within the range of 30 ° C. or higher and 70 ° C. or lower to control the temperature so that the viscosity of the ink is within the stable ejection range. At times, a liquid ink may be used. In addition, the temperature rise due to thermal energy is positively prevented by using it as the energy for changing the state of the ink from the solid state to the liquid state, or in order to prevent the evaporation of the ink, it is solidified and heated in a standing state. You may use the ink liquefied by. In any case, by applying heat energy such as ink that is liquefied by applying heat energy according to the recording signal and liquid ink is ejected, or that begins to solidify when it reaches the recording medium. The present invention can be applied to the case where an ink having a property of being liquefied for the first time is used. In this case, the ink is
JP 54-56847 A or JP 60-7.
As described in Japanese Patent No. 1260, it may be configured to face the electrothermal converter in a state of being held as a liquid or a solid in the concave portion or the through hole of the porous sheet. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, as the form of the ink jet recording apparatus of the present invention, in addition to the one used as an image output terminal of information processing equipment such as a computer, a copying apparatus combined with a reader or the like, and a facsimile apparatus having a transmitting / receiving function can be used. It may be in a form or the like.

[0082]

As described above, the ink jet recording apparatus of the present invention is configured to perform the ejection recovery process according to the density of the ejected ink on the plurality of recording heads ejecting the inks of different densities. Therefore, stable ejection can be always guaranteed by the necessary and sufficient ejection recovery processing according to the characteristics of the dark and light ink.

As the above-mentioned ejection recovery processing, any processing such as idle ejection for ejecting ink not involved in recording, forced flow of ink in the recording head, and wiping of the ink ejection port can be adopted. , And those processes can be combined.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main part of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of the relationship between the leaving time of dark and light ink and the viscosity.

FIG. 3 is a perspective view showing a main part of an example of an inkjet recording apparatus to which the present invention can be applied.

FIG. 4 is a perspective view showing an example of the configuration of the recording head shown in FIG.

FIG. 5 is a schematic configuration diagram of a supply recovery system showing a fourth embodiment of the present invention.

FIG. 6 is a schematic block configuration diagram for explaining a control unit of the supply recovery system shown in FIG.

FIG. 7 is an explanatory diagram of the relationship between the composition of dark ink and the standing time.

FIG. 8 is an explanatory diagram of a relationship between viscosity of dark ink and leaving time.

FIG. 9 is an explanatory diagram of a relationship between a composition of light ink and a standing time.

FIG. 10 is an explanatory diagram of a relationship between viscosity of light ink and leaving time.

FIG. 11 is a schematic block configuration diagram for explaining a drive unit of a recording head according to a seventh embodiment of the present invention.

FIG. 12 is an explanatory diagram of a distribution table provided in the density distribution processing unit shown in FIG. 11.

FIG. 13 is a block diagram showing a main part of a seventh embodiment of the present invention.

14 is a plan view of an essential part for explaining a second wiping mode by the recovery processing means shown in FIG.

FIG. 15 is a plan view of an essential part for explaining the first wiping mode by the recovery processing means shown in FIG.

FIG. 16 is a plan view of an essential part for explaining an all head wiping mode in a ninth embodiment of the present invention.

FIG. 17 is a plan view of an essential part for explaining a light head wiping mode in a ninth embodiment of the present invention.

FIG. 18 is a block diagram illustrating a configuration for video counting according to an eighth embodiment of the present invention.

[Explanation of symbols]

22CK, 22MK, 22YK, 22KK dark ink ejection recording head 22CU, 22MU, 22YU, 22KU light ink ejection recording head 31, 32 idle ejection control circuit 35 idle time timer 36 processing means

Claims (7)

[Claims] 1. An ink jet recording apparatus that performs recording by ejecting a plurality of types of ink having different densities from a plurality of recording heads corresponding to the respective inks. In addition, the processing means performs a discharge recovery process for each of the plurality of print heads according to the density of ink discharged by each of the plurality of print heads. An inkjet recording apparatus characterized in that the conditions are different. 2. The ink jet recording apparatus according to claim 1, wherein the ejection recovery unit ejects ink not involved in recording from each of the plurality of recording heads. 3. The ejection recovery means is configured to vary the number of ejections of ink not involved in recording ejected from the plurality of recording heads per predetermined time as a condition of the ejection recovery processing. Item 2. The inkjet recording device according to item 2. 4. The ink jet recording apparatus according to claim 1, wherein the ejection recovery unit causes the ink in the plurality of recording heads to flow. 5. The ink jet recording according to claim 4, wherein the ejection recovery unit varies the strength of flowing ink in the plurality of recording heads as a condition of the ejection recovery process. apparatus. 6. The ink jet recording apparatus according to claim 1, wherein the ejection recovery unit is a unit that cleans ink ejection units of the plurality of recording heads. 7. The ejection recovery unit is configured to vary the number of cleanings of the ink ejection units of the plurality of print heads per predetermined time as a condition for the ejection recovery process. Inkjet recording device.