JPH0427556A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To minimize the frequency of cleaning operations of a recording head by performing an inference according to a measuring output of a measuring means for measuring a quantity of state pertaining to a discharge condition of the recording head to control a cleaning means. CONSTITUTION:A control section 40 inputs a moisture signal of a recording head 1 involved as detected by a moisture detection means 52 to calculate an optimum driving interval To by a fuzzy inference from the number of sheets to be recorded brought in from a counter 53 and moisture according to a membership function and a rule read out of an RAM 43. When printing time (t) of four recording head 11-14 detected from a timing signal to be outputted from a timer 44 is larger than the optimum driving interval To calculated, a block drive means 51 is operated to perform a cleaning operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet recording device, and particularly to a cleaning mechanism for the ejection orifice surface of a recording head of the inkjet recording device.

[Prior Art] Conventionally, there are various inkjet recording methods in which recording is performed by ejecting ink onto a recording medium such as a recording sheet, but thermal inkjet methods (for example, , U.S. Patent No. 47231
No. 29, U.S. Pat. No. 4,740,796, etc.) have good responsiveness to recording electrical signals, facilitate high-density multiplication of ejection ports (orifices), generate little noise during recording, and print in multiple colors. Since it has advantages such as the ease of recording color images using ink, its future prospects are seen as more promising than other inkjet recording methods.

However, in inkjet recording devices, if foreign matter such as dust or ink droplets adhere to the ejection orifice surface of the printhead, there is a risk of ink ejection failure, so it is necessary to clean the ejection orifice surface of the printhead as appropriate. This is commonly done.

As this cleaning means, a flexible blade made of a plastic sheet or the like is used to wipe the ejection orifice surface of the recording head (for example, Japanese Patent Laid-Open No. 61-23094
No. 7) and a method that forcibly leaks ink from the ejection ports of the print head and then wipes off ink adhering to the ejection port surface of the print head.

[Problems to be Solved by the Invention] However, when the above-mentioned cleaning method is adopted, it takes time to execute it, so if the cleaning operation is performed frequently, the average printing speed (hereinafter referred to as throughput) will decrease. .

Therefore, in consideration of throughput, there is a desire to set the interval until the next cleaning operation as long as possible.

Conventionally, the adhesion of ink droplets, which is the cause of ink ejection failure, is caused by multiple factors such as the number of sheets to be printed, the humidity of the print head, the temperature of the print head, the room temperature, and the length of time the ink is left standing. Some of the factors are measured using a counter sensor and a timer, and the interval is automatically set based on the measured values. Since there is ambiguity in the relationship between the occurrence of adhesion and these factors, it has not been possible to determine the optimum spacing, and further improvement of the throughput remains an issue.

An object of the present invention is to provide an inkjet recording apparatus that can maximize throughput by minimizing the number of cleaning operations of the recording head.

[Means for Solving the Problems] An inkjet recording device of the present invention is an inkjet recording device that performs recording by discharging ink onto a recording medium, and includes an ejection port and ejects ink from the ejection port. a recording head for cleaning, a cleaning means for cleaning an ejection port surface of the recording head, a measuring means for measuring a state quantity related to an ejection state of the recording head, and an inference based on a measurement output of the measuring means. and control means for controlling the cleaning means.

Further, the control means includes a state quantity importing means for importing a state quantity (including a printing time of the recording head) measured by the measuring means; and the state quantity taken in by the state quantity importing means and the cleaning. a memory storing membership functions each expressing a driving interval of the means as a fuzzy set, and a rule indicating a relationship between the state quantity and the driving interval; and the membership function and the rule read from the memory. Accordingly, it is preferable to have a microprocessor that calculates an optimum drive interval from the state quantity by fuzzy inference and operates the cleaning means when the printing time is longer than the calculated optimum drive interval.

Furthermore, it is preferable that the microprocessor calculates the optimum drive interval according to Mamdani's method.

In addition, the measuring means includes a detecting means for detecting the number of recorded sheets, a detecting means for detecting the humidity of the recording head, a detecting means for detecting the temperature of the recording head, a detecting means for detecting the leaving time of the recording head, and It is preferable to have at least one detection means for detecting room temperature.

The rule is that the greater the number of recording sheets, the shorter the driving interval, and the higher the humidity of the recording head, the shorter the driving interval.In addition, the higher the temperature of the recording head, the shorter the driving interval. The shorter the head leaving time, the shorter the time, and the lower the room temperature, the shorter the time.

The cleaning means may be a means of wiping off the ejection opening surface of the recording head with a flexible blade, a means of wiping off ink adhering to the ejection opening surface of the recording head such as an absorber, or a means of wiping off the ink adhering to the ejection opening surface of the recording head using a flexible blade. Preferably, cleaning is performed using a stream or a cleaning solution. Furthermore, the cleaning means may be operated after pressurizing and discharging ink from the nozzles of the recording head, after preliminary ejection, or after sucking ink from the nozzles of the recording head. preferable.

The recording head includes a recording head in which 10 to 100 ejection ports are arranged or a disposable type of print head, but the present invention has ejection ports formed over the entire width of the recording area of the recording sheet for the sake of controllability. It can be preferably applied to full line type.

Further, the recording head uses thermal energy to eject ink from the ejection ports, and preferably includes an electrothermal converter as a means for generating the thermal energy.

[Function] In the inkjet recording apparatus of the present invention, the state quantity for estimating the state of the ejection orifice surface of the recording head is detected by the state quantity detection means, and is taken into the control unit by the state quantity acquisition means. It has a measuring means. Also,
The memory of the control unit stores in advance a membership function expressing the state quantity and the driving interval of the driving means for driving the cleaning means as a fuzzy set, and a rule indicating the relationship between the state quantity and the driving interval. ing. Therefore, according to the membership function and the rule read from the memory by the microprocessor,
A plurality of the state quantities are calculated by calculating an optimum drive interval from the state quantity by fuzzy inference and operating the drive means when the printing time detected by the printing time detection means is longer than the calculated optimum drive interval. Since the optimum drive interval can be calculated by accurately grasping the state of the ejection port surface of the print head, which has an ambiguous relationship with As a result, throughput can be improved to the maximum.

In addition to Mamdani's method, which will be described later, there is also a simple method of fuzzy inference that expresses the membership function as a straight line and uses a linear formula in the conclusion part of the rule (Nikkei Mechanical, September 5, 1988). Date p, 118-p,
126) By using a microprocessor, the optimal drive interval can be easily calculated even when using Mamdani's method, which has good accuracy but requires complicated calculations, so it is easier to calculate than when using the simple method. The optimum drive interval can be calculated with high accuracy.

The adhesion of ink droplets, which is the cause of ink ejection failure in the recording head, depends on the number of sheets to be printed, the humidity of the recording head, the temperature of the recording head, the time the recording head is left unused, and the room temperature. The detection means detects at least one of these to calculate the optimum drive interval.

The adhesion of ink droplets, which is a cause of ink ejection failure in the recording head, is affected by the number of sheets printed, the higher the humidity of the recording head, the higher the temperature of the recording head, and the longer the recording head is left unused. The shorter the driving interval, the more likely it is to occur when the room temperature is low. Therefore, by setting the rule such that the driving interval becomes shorter as such conditions overlap, the optimum driving interval can be calculated with high accuracy.

The cleaning means may include wiping off the ejection opening surface of the recording head with a flexible blade, wiping off ink adhering to the ejection opening surface of the recording head, or cleaning using air flow or cleaning liquid. These operations are performed after pressurizing and discharging ink from the nozzles of the recording head, or after preliminary ejection, or after suctioning ink from the nozzles of the recording head, Ink adhering to the ejection port surface of the recording head is removed. Regardless of which method is used, the cleaning operation can be performed efficiently by operating at the optimum drive interval.

[Example] Next, an example of the present invention will be described with reference to the drawings.

The overall structure of the inkjet recording apparatus of this embodiment will be described with reference to FIGS. 1 to 4.

As shown in FIG. 2, the four recording heads 1 to 14 used in the inkjet recording apparatus of this embodiment are bubble jet type recording heads corresponding to black, yellow, magenta, and cyan ink colors, respectively. , fixed to block 2.

Each of the recording heads 11 to 14 uses a built-in electrothermal converter 24 (see Figure 3) as an ejection energy generating means, and the heat generated when electricity is applied causes a film boiling phenomenon to cause the growth of bubbles generated in the ink. - Ink droplets are ejected from the ejection port 28 due to contraction, and the density of 4000 PI is 4
It is a full line type with 736 discharge ports arranged. Further, a reading head 12 for reading a recorded image in order to detect the nozzle number of each of the recording heads 11 to 14 for ejection or non-ejection is also fixed to the block 2.

When the block 2 is not recording, such as during standby, it is pulled up by the block drive means (see Figure 1) to the position indicated by the dashed line in the figure, and is placed opposite the capping unit 3, which has been moved to the position indicated by the broken line in the figure. and capped. The capping unit 3 collects ink discharged during the cleaning operation of the ejection port surfaces 29 of the four recording heads 1□-14 and pumps 32 shown in FIG. 4 during the clogging recovery operation of the four recording heads 11-14. It becomes a receiving tray for the ink that is compressed and sent through the first tube 33 and discharged from the ejection port 28, and is led to a waste ink tank (not shown).

An endless charged adsorption belt 4 for conveying the recording sheet 7 is disposed so as to face each of the recording heads 11 to 14 at a predetermined interval.

Further, a back platen 5 is arranged to face each of the recording heads 11 to 14 via a charging adsorption belt 4.

Paper cassette 6 containing recording sheets 7 such as plain paper
is detachably attached to the main body of the inkjet recording apparatus. The pickup roller 8 feeds out only one recording sheet 7 located on the uppermost surface of the paper feed cassette 6. The fed-out recording sheet 7 is transferred to a conveying path 10 by a conveying roller 9.
and is sent to the charged adsorption belt 4 via the transport roller 11.

The heater 13 and fan 14 are connected to each recording head 11 to 1.
In step 4, the ink droplets deposited on the recording sheet 7 are dried and fixed using hot air. The discharge roller 15 discharges the recording sheet 7 on which the fixing has been completed to the outside of the apparatus. The tray 16 sequentially stocks the discharged recording sheets 7.

Although not shown in FIG. 2, the inkjet recording apparatus of this embodiment also has an optimum drive interval T, which is the object of the present invention.
. It is equipped with a control section 40 (see FIG. 1) which is a means for determining.

Next, the configuration of the control section 40 will be explained using FIG. 1.

The control unit 40 includes a timer 44 that outputs a timing signal at regular intervals to detect the printing time t of the four recording heads II to 14, and a humidity detection element 31 provided in the recording head 1□ (Fig. 3). Humidity capturing means converts an analog signal indicating the humidity of the recording head 11 detected by the humidity detecting means 52, which consists of a
/D conversion circuit) 45, the converted humidity is stored, and the number of recording sheets, humidity, and drive shown in FIGS. Membership functions PL, PM, PH, HL, HMllH, TL, which express intervals as fuzzy sets,
RA in which rules indicating the relationship between TM, TH, the number of recorded sheets, the humidity, and the drive interval are stored;
M43, and the membership functions PL, PM, PH, HL, )IM, HH, read from the RAM43.
TL, TM.

According to Tll and the rules, the optimum drive interval T0 is calculated by fuzzy inference from the number of recorded sheets taken in by the counter 53 and the converted humidity, and the four records detected from the timing signal output from the timer 44 are calculated. When the printing time t of the heads 11 to 14 is longer than the calculated optimum drive interval To, the block driving means 51 is operated to perform the cleaning operation, and also to perform the cleaning operation. A microprocessor (hereinafter referred to as CPU) that outputs data to the four recording heads 11 to 14, etc.
41, and a ROM 42 in which programs and the like containing operating procedures of the CPU 41 are stored. Also,
A counter 53 that counts the number of printed recording sheets 7 is connected to the CPU 41.

Next, regarding the structure of the recording head 11 shown in FIG.
This will be explained using FIG. 3 (other three recording heads 1□~
14 also has the same structure).

This recording head 1□ uses an electrothermal transducer 24 as a thermal energy generating means for ejecting ink using bubbles generated by heating the liquid.

This recording head 11 includes a plurality of electrothermal transducers 24. A plurality of electrodes 25. It has a plurality of nozzle walls 26 and one top plate 21, which are members for defining a liquid path. Recording ink is provided behind each nozzle 22 as a liquid path on the substrate 20 via a tank 35 (see FIG. 4), a second tube 34 (see FIG. 4), and a connector 27. The liquid is supplied into the common liquid chamber 23. The ink supplied into the common liquid chamber 23 is supplied into each nozzle 22 by capillary action, and is stably held by forming a meniscus at the ejection opening surface 29 at the tip of the nozzle 22. At this time, electrode 2
When the electrothermal converter 24 is energized by 5, the ink on the electrothermal converter 24 is heated, a bubbling phenomenon occurs, and droplets are ejected from the ejection port surface 29 due to the energy of the bubbling. Here, the nozzle 22 has a nozzle density of 400DP I
It is formed with high density.

Further, a humidity detection element 31 such as a humidity-sensitive resistor element for detecting the humidity of the recording head 11 is provided on the side of the substrate 20 of the recording head 1 □ opposite to the surface on which the top plate 21 is provided. (Note that the other three recording heads 12 to 14 have
(No humidity detection element 31 is provided).

Next, a method of ejecting ink from a recording head generally used in an inkjet recording apparatus will be described.

This type of recording head has fine liquid ejection ports (
orifice), a liquid path, an energy acting part provided in the liquid path, and an energy generating means for generating energy to act on the liquid in the energy acting part to form droplets. The energy generating means includes a recording method using an electromechanical transducer such as a piezo element;
A recording method using an energy generation means that generates heat in a liquid by irradiating and absorbing electromagnetic waves such as a laser, and ejects the liquid by the action of the heat generated. Energy generation that heats the liquid with an electrothermal converter and ejects the liquid. There are recording methods using other means.

Among them, the recording head used for the bubble jet method is capable of arranging liquid ejection ports with high density for ejecting recording liquid to form flying droplets, as will be described later. In addition, a recording head using the electrothermal converter as an energy generating means is easy to downsize, and takes advantage of the advantages of IC technology and high micro technology, which have seen recent technological advances and remarkable improvements in reliability in the semiconductor field. Since it can be fully utilized and can be easily made into a long length and planar (two-dimensional), it is easy to make multi-nozzles and high-density packaging, and mass production is possible, and the manufacturing cost is low. Therefore, it is possible to provide an inkjet recording head that has a unique structure.

Next, the ink supply system of the recording head 1 will be explained using FIG. 4 (the same applies to the other three recording heads 11 to 14).

This ink supply system includes a tank 35 having a valve 36 in which ink is stored, and a recording head 1 between the tank 35 and the recording head 1.
A first tube 33 is provided between the tank 35 and the recording head 1 via a pump 32. and a second tube 34 provided between the first and second tubes.

Here, the pump 32 is the capping unit 3.
(See FIG. 2) as well as the nozzle 22 of the recording head 11.
It operates as a means for forcibly leaking ink from the ink (see FIG. 3), and is used when recovering from ink failure caused by ink sticking.

Next, the recording operation of the inkjet recording apparatus of this embodiment will be explained using FIG. 2.

When an operation to start recording is performed, a recording sheet 7 of a specified size is sent out from the paper feed cassette 6 by a pickup roller 8. The sent record sheet 7
is the conveyance roller 9. A charged adsorption belt 4 rotates in a pre-charged state via a conveyance path 10 and a conveyance roller 11 and is flattened by a pack platen 5.
be carried on. As the leading end of the recording sheet 7 reaches the lower part of each of the recording heads 1 to 14, the electrothermal transducer 24 (see FIG. 3) of each of the recording heads 11 to 14 (not shown) is activated. It is driven according to image data by a drive circuit. Due to this drive, ink droplets according to image information are
The image information is ejected from the ejection ports 28 of each of the recording heads 11 to 14 onto the surface of the recording sheet 7, thereby recording the image information. If the recording sheet 7 has poor hygroscopicity, the ink droplets adhering to the surface will not dry and will be rubbed, causing print stains. Therefore, forced drying is performed using the heater 13 and fan 14 to fix the ink droplets. let The recording sheet 7 that has been fixed is transferred to the tray 1 by the ejection roller 15.
6.

As a result of the above operations, black, yellow, magenta, and cyan inks are deposited on the recording sheet 7 from each recording head 11 to
14 to form a full color image.

Next, the cleaning operation of the ejection port surface 29 of the recording head E will be explained using FIG. 5 (the same applies to the other three recording heads 12 to 14).

During the cleaning operation, the block 2 is pulled up by the block driving means 51 (see FIG. 1) to the position shown by the dashed line in FIG. be capped. At this time, the four flexible blades 371 to 374 provided at positions facing each of the recording heads 11 to 14 of the capping unit 3, as shown by a in FIG. ~14
It is located away from the discharge port surface 29 of. When the cleaning operation is started, each of the blades 371 to 374 is moved toward the ejection port surface 29 of each of the recording heads 11 to 14 to a position where the tip thereof contacts the ejection port surface 29 and bends. Afterwards (b in FIG. 5), the tip is rotated from left to right in the figure to wipe away ink droplets adhering to the ejection port surface 29 (c in FIG. 5). The wiped ink droplets fall down through the blades 371 to 37 as shown by d in FIG.
The ink is guided to a waste ink tank (not shown) through a tube 39. When the cleaning operation of the discharge port surface 29 is completed in this manner, each of the blades 37. ~374 are returned to the standby state indicated by a in the figure.

Next, fuzzy inference will be briefly explained.

First, to explain the membership functions, for example, regarding the number of recorded sheets, the membership functions PL, PM, and PH, which indicate a state where the number of recorded sheets is small, a state where the number of recorded sheets is medium, and a state where the number of recorded sheets is large, are shown in Fig. 7 (A). ), the membership values X indicating the degree to which the 30 recorded sheets belong to the fuzzy set of the membership functions PL, PM, and PH are respectively 0.5.0.
5. It becomes O. Similarly, regarding humidity, membership functions HL, HM, and HH indicating low humidity, medium humidity, and high humidity are shown in Figure 7 (B).
When defined as shown in FIG.
．． 5.0.5.0. In addition, regarding the drive interval, membership function holes TM, T indicate a state where the drive interval is short, a state where the drive interval is medium, and a state where the drive interval is long.
) I is defined as shown in Figure 7(C),
The driving interval of 10 minutes is the membership function TL, TM,
The membership values Z indicating the degree to which TH belongs to the fuzzy set are 0.1 and 0.0, respectively.

In addition, the rule used for fuzzy inference is that the driving interval becomes shorter as the number of recorded sheets increases and the humidity increases.For example, as rule 1, If Number of recorded sheets=P
Hand Humidity =) IMThen Drive interval = TL
(1) As rule 2, If Number of recorded sheets == PMand Humidity = HMThe
Set as n drive interval=TM(2).

Furthermore, the number of sheets recorded is 80, and the humidity of the recording head II is 4.
Optimal drive interval T according to Mamdani's method, which is a method of fuzzy inference when 0%. is calculated as follows.

From FIG. 7(A), the number of recorded sheets of 80 belongs to the fuzzy set of the membership function P)I, and from FIG. 7(B), the humidity of 40% belongs to the fuzzy set of the membership function 11M. 1) The condition of Rule 1 shown in the formula is met. Therefore, as shown in FIG. 8(A), the membership value X, which indicates the degree to which the number of recorded sheets (80 sheets) belongs to the fuzzy set of the membership function PH,
) is determined, and at the same time, as shown in FIG. 8(B), a membership value Yl (=0.5) indicating the degree to which humidity 40% belongs to the fuzzy set of the membership function HM is determined. When these two membership values X+ and Y+ are compared in magnitude, the membership value Y1 is smaller, so the membership value Yl (=0.5) satisfies the condition of the rule l shown in equation (1) above. The degree of satisfaction is determined by the membership value 2. of the fuzzy set of the membership function TL of the drive interval. The fuzzy set indicated by diagonal lines in FIG. 8(C) for which 0.5 or less is selected.

Furthermore, from FIG. 7(A), since the number of recorded sheets of 80 also belongs to the fuzzy set of the membership function PM, the number of recorded sheets of 80 and humidity of 40% also correspond to the conditions of Rule 2 shown in equation (2) above. do. Therefore, as shown in FIG. 8(D), the membership value x2 (=
0.18), and as shown in FIG. 8(E), the membership value Y2 (=0
Find 5). These two membership values X2. When comparing the magnitude of Y2, the membership value x2 is smaller, so the membership value X2 (= about 0.18) is
), as the degree to which the condition of Rule 2 shown in the formula is satisfied, among the fuzzy set of the membership function TM of the drive interval
Figure 8 (F
) select the fuzzy set indicated by diagonal lines.

Then, by finding the sum of the fuzzy sets selected in FIG. 8(C) and FIG. 8(F) and calculating the center of gravity G, the optimum drive interval in this case is determined as shown in FIG. 8(G). To("2 minutes)" is obtained.

Next, the operation of the control section 40 will be explained using the flowchart shown in FIG.

Before operating the inkjet recording apparatus of this example,
Membership function P regarding number of recording sheets, humidity, and drive interval
L, PM, PH, HL, HM, HH, TL,
TM, TH and rules and timers used for fuzzy inference 4
The time interval to (=10 seconds) of the timing signal output from 4 to the CPU 41 and the initial value (=O) of the printing time t detected by the CPU 41 based on the timing signal are stored in the RAM 4.
At the same time, the CPU 41 resets the counter 53 (see FIG. 1) that counts the number of recorded sheets (step 61).

After that, when printing starts (step 62), the CPU
41 transfers the print data sent from the data transfer device 50 (see FIG. 1) to the four records/rads 11 to 14, prints it on the recording sheet 7 (step 63), and prints it on the recording sheet 7 (step 63). When printing for one page (see figure 2) is completed,
The CPU 41 updates the count value of the counter 53 so as to increase it by one (steps 64 and 65). Further, when a timing signal is output from the timer 44 during printing (step 66), the CPU 41 outputs the data of the initial value (=0 seconds) of the printing time t stored in the RAM 43 and the timing signal. time interval t0 (
=10 seconds), and the addition result (=1
0 second) is stored in the RAM 43 as a new printing time t, and the humidity output from the humidity detection means 52 is set as the new printing time t.
It is loaded into the RAM 43 via the D conversion circuit 45, and the number of recording sheets indicated by the counter 53 is read (step 67), and the optimum drive interval T is determined by the above-mentioned fuzzy reasoning from the number of recording sheets and the humidity. is calculated (step 68). The CPU 41 calculates the calculated optimum drive interval T.
o and the new printing time t( stored in the RAM 43)
= 10 seconds), and if the new printing time t is smaller than the optimum drive interval To, the operations from step 63 are repeated (step 69). however,
The second and subsequent additions are performed between the new printing time t and the time interval to. On the other hand, as a result of the size comparison in step 69, if the new printing time t is larger than the optimum drive interval T0, the CPU 41 drives the block drive means 51 to drive the four recording heads 1.
Perform cleaning operations 1 to 14 (step 70)
When the cleaning operation is completed, the new printing time t is set to 0 seconds and stored in the RAM 43, and the counter 53 is reset (step 71).
The operations from step 63 are repeated until printing is completed (step 72).

In this embodiment, the inkjet recording apparatus has means for wiping the ejection orifice surface of the recording head with a flexible blade as cleaning means for the ejection orifice surface of the recording head. A description has been given of an apparatus having a counter for counting the number of recorded sheets as a state quantity detecting means for detecting a state quantity for estimating the state, and a humidity detecting means for detecting the humidity of the recording head.

In this way, in the inkjet recording apparatus of this embodiment, the humidity detection element 31 is provided only in the recording head 11, and the optimum drive interval is calculated from the humidity detected using the humidity detection element 31 and the number of recording sheets counted by the counter 53. T. The cleaning operation was performed for the four recording heads 1 to 14, but the other three recording heads 1 to 14 were also provided with humidity detection elements, and the optimum drive was performed in the same way for each of the recording heads 11 to 14. The interval may be determined and the cleaning operation may be performed independently at the optimum drive interval.

Furthermore, in this example, the optimum drive interval To was determined by detecting the number of sheets to be printed and the humidity of the print head, but the frequency of occurrence of ink droplets adhering to the ejection orifice surface of the print head Since it also depends on the temperature of the head, the time the recording head is left unused, and the room temperature, at least one of these five factors may be detected and the optimum drive interval may be similarly calculated based on the detection result. However, when using the temperature of the print head, the time the print head is left unused, and the room temperature, the rules of fuzzy inference are that the higher the temperature of the print head, the shorter the time the print head is left, the more The lower the room temperature, the shorter the driving interval is used.

Further, in the above-described embodiment, a means for wiping off the ejection port surface of the recording head with a flexible blade was used as a cleaning means, but after forcibly leaking ink from the nozzles of the recording head, the A known means for wiping off ink leaking from the ejection opening surface of the head may be used and the means may be operated at an optimum drive interval calculated in the same way, or the capping unit 3 shown in FIG. It is also possible to provide a known means for forcibly sucking ink from the nozzles of the head and then wiping off ink leaking from the ejection surface of the recording head, and to operate this means at the optimum drive interval similarly calculated. good.

The present invention brings about excellent effects particularly in an inkjet recording apparatus using a recording head of the bubble jet method proposed by Canon among inkjet recording methods.

As for typical configurations and principles thereof, it is preferable to use the basic principles disclosed in, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740,796. This method can be applied to both the so-called on-demand type and continuous type, but especially in the case of the on-demand type, it is necessary to arrange the liquid (ink) in accordance with the sheet and liquid path that hold it. generating thermal energy in the electrothermal transducer by applying at least one drive signal corresponding to the recorded information and causing a rapid temperature rise exceeding nucleate boiling to the electrothermal transducer;
This is effective because film boiling is caused on the heat-active surface of the recording head, resulting in the formation of bubbles in the liquid (ink) in one-to-one correspondence with this drive signal. The growth and contraction of the bubble causes liquid (ink) to be ejected through the ejection opening to form at least one droplet. If this drive signal is in the form of a pulse, bubble growth and contraction will occur immediately and appropriately.
Particularly responsive liquid (ink) ejection can be achieved,
More preferred. As this pulse-shaped drive signal, those described in US Pat. No. 4,463,359 and US Pat. No. 4,345,262 are suitable. Furthermore, if the conditions described in US Pat. No. 4,313,124 concerning the invention regarding the temperature increase rate of the heat acting surface are adopted, even more excellent recording can be performed.

In addition to the combination of ejection ports, liquid paths, and electrothermal converters (straight liquid path or right-angled liquid path) as disclosed in the above-mentioned specifications, the recording head has a heat-acting section. U.S. Pat. No. 4,558,333 and U.S. Pat. No. 44,596 disclose configurations located in bending regions.
It may be configured using those described in the specification of No. 00, respectively. In addition, Japanese Patent Application Laid-open No. 123670 of 1982 discloses a configuration in which a common slit is used as a discharge part for a plurality of electrothermal converters, and a hole that absorbs pressure waves of thermal energy is disclosed. The present invention is also effective as a configuration based on Japanese Patent Application Laid-Open No. 138461 of 1982, which discloses a configuration compatible with a discharge section.

Furthermore, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by an inkjet recording apparatus, a combination of multiple recording heads as disclosed in the above-mentioned specification can be used. Either a configuration that satisfies the length or a configuration as a single recording head formed integrally may be used, but the present invention can more effectively exhibit the above-mentioned effects.

In addition, a replaceable chip-type recording head that is attached to the device body enables electrical connection to the device body and ink supply from the device body, or a chip-type recording head that is installed integrally with the recording head itself. The present invention is also effective when a cartridge type recording head is used.

In addition, the recording mode of the inkjet recording device is as follows:
In addition to the recording mode for only the mainstream color such as black, the recording head may be configured integrally or by a combination of multiple colors, but it is also possible to use a device equipped with at least one of multiple colors of different colors or full color by mixing colors. The present invention is also extremely effective.

In the embodiments of the present invention described above, the ink is explained as a liquid, but it is an ink that solidifies at room temperature or lower, but softens or becomes a liquid at room temperature, or an ink that is generally used in inkjet. It may be one that becomes soft or liquid within the temperature range of 30° C. or higher and 70° C. or lower, which is the temperature range for temperature adjustment. That is, it is sufficient if the ink is in a liquid state when the recording signal is applied.

In addition, it is possible to proactively prevent temperature rise due to thermal energy by using it as energy to transform the ink from a solid state to a liquid state, or to prevent ink from evaporating by preventing ink from solidifying when left unused. In any case, the ink is liquefied by applying thermal energy in accordance with the recording signal and is ejected as liquid ink, or the ink has already begun to solidify by the time it reaches the recording medium. It is also applicable to the present invention to use ink that is liquefied only by the following steps. In such a case, the ink is held in a liquid or solid state in the recesses or through holes of the porous sheet, as described in JP-A-54-56847 or JP-A-60-71260. , it may also be in a form that faces the electrothermal converter. In the present invention, the most effective method for each of the above-mentioned inks is to implement the above-mentioned film boiling method.

[Effects of the Invention 1 The present invention is configured as described above, and therefore has the following effects.

The controller includes a measuring means for detecting a state quantity for estimating the state of the ejection port surface of the recording head by the state quantity detecting means and importing the state quantity into the control part by the state quantity importing means. A membership function expressing the state quantity and the driving interval of the driving means for driving the cleaning means as a fuzzy set, and a rule indicating the relationship between the state quantity and the driving interval are stored in advance in the memory, and are stored in advance by the microprocessor. , calculating an optimal drive interval by fuzzy inference from the state quantity according to the membership function read from the memory and the rule;
By operating the driving means when the printing time detected by the printing time detection means is longer than the calculated optimum driving interval, the optimum driving interval is calculated with high precision, and the ejection orifice surface of the recording head is cleaned. Since the number of operations can be minimized, throughput can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a control section of an embodiment of an inkjet recording device of the present invention, FIG. 2 is a diagram showing a schematic configuration of an embodiment of an inkjet recording device of the present invention, and FIG. FIG. 4 is a schematic diagram showing the ink supply system of the recording head shown in FIG. 2, and FIG. 5 is a capping means shown in FIG. 2. 6th diagram illustrating the operation during the cleaning operation.
The figure is a flowchart explaining the calculation operation of the optimum drive interval in the control unit, and No. 7rIIJ is a graph showing membership functions. Graphs showing membership functions; (C) is a graph showing each membership function related to drive intervals; FIG. , (A) is the membership value x
A graph showing the calculation method of 1, (B) is the membership value Y
Graph showing how to calculate I, (C) is membership value Z
, (D) is the membership value X
A graph showing the calculation method of 2, (E) is the membership value Y
Graph showing the calculation method of 2, (F) is the membership value z
Graph showing the calculation method of 2, (G) is the optimal drive interval T0
It is a graph showing a calculation method. 11. 12, Is, 14...recording head, 2.
... Block, 3... Capping unit, 4... Charge adsorption belt, 5... Back platen, 6... Paper feed cassette, 7... Recording sheet, 8...
Pickup roller, 9.11... Conveyance roller, 1o... Conveyance path, 12... Reading head, 1
3... Heater, 14... Fan, 15...
Ejection roller, 16... Tray, 20... Board,
21...Top plate, 22...Nozzle, 23.
... common liquid chamber, 24 ... electrothermal converter, 25 ... electrode, 26 ... nozzle wall, 27 ...
...Connector, 28...Discharge port, 29...Discharge port surface, 31...Humidity detection element, 32...Pump, 33...First tube, 3
4... Second tube, 35... Tank, 36... Valve, 371~
374...Blade, 39...Third tube, 40...Control unit, 41...
...CPU, 42...ROM. 43...RAM, 44...Timer, 45.
... A/D conversion circuit, 50... Data transfer device, 51... Block driving means, 52... Humidity detection means, 53... Counter, PL, PM, PH, IIL, HM, HH, T.L.
, TM, TH...Membership function, X, X+, Xz, Y, Y+, Ya, Z, Z+, Z2 membership value, G... Center of gravity, optimal drive interval.

Claims (1)

[Scope of Claims] 1. An inkjet recording apparatus that performs recording by discharging ink onto a recording medium, comprising: a recording head having an ejection opening and ejecting ink from the ejection opening; and an ejection unit of the recording head. a cleaning means for cleaning an exit surface; a measuring means for measuring a state quantity related to the ejection state of the recording head; and a control means for controlling the cleaning means by making inferences based on the measurement output of the measuring means. An inkjet recording device comprising: 2. The control means includes: a state quantity capturing means for capturing a state quantity including at least the printing time of the recording head measured by the measuring means; and a driving interval of the cleaning means and the state quantity captured by the state quantity capturing means. A memory in which membership functions expressed as fuzzy sets and rules indicating the relationship between the state quantity and the driving interval are stored; The inkjet recording device according to claim 1, further comprising a microprocessor that calculates an optimum drive interval by inference and operates the cleaning means when the printing time is longer than the calculated optimum drive interval. Device. 3. The inkjet recording apparatus according to claim 2, wherein the microprocessor calculates the optimum drive interval according to Mamdani's method. 4. The measuring means includes a detecting means for detecting the number of recorded sheets, a detecting means for detecting the humidity of the print head, a detecting means for detecting the temperature of the print head, a detecting means for detecting the leaving time of the print head, and a detecting means for detecting room temperature. Claim 2 or 3, characterized in that it has at least one detection means for detecting
The inkjet recording device described in Section 1. 5. The rule is that the greater the number of sheets to be recorded, the higher the humidity of the recording head, the higher the temperature of the recording head, the shorter the exposure time of the recording head, and the lower the room temperature, the shorter the drive interval should be. Claim 2 characterized in that
The inkjet recording device according to any one of items 1 to 4. 6. The inkjet recording apparatus according to any one of claims 1 to 5, wherein the cleaning means is means for wiping off the ejection port surface of the recording head with a flexible blade. 7. The cleaning means is a means for wiping off ink adhering to the ejection port surface of the recording head after pressurizing and discharging ink from the nozzles of the recording head. The inkjet recording device according to any one of Item 5. 8. Any one of claims 1 to 5, wherein the cleaning means is a means for wiping off ink adhering to the ejection port surface of the recording head after sucking ink from the nozzles of the recording head. An inkjet recording device according to claim 1. 9. The inkjet recording apparatus according to any one of claims 1 to 8, wherein the recording head is a full-line type in which ejection ports are formed over the entire width of the recording area of the recording sheet. 10. The recording head uses thermal energy to eject ink from the ejection ports, and includes an electrothermal converter as a means for generating the thermal energy. The inkjet recording device according to any one of Item 9.