JPH11129500A - Ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recorder having a maintenance level decision means for preventing useless discharge of ink even upon occurrence of incomplete ink jet. SOLUTION: The ink jet recorder comprises a maintenance station comprising a nozzle face cleaner, an ink moving unit for discharging ink from a nozzle and means for preventing evaporation of ink from the nozzle, a maintenance switch for operating the maintenance station in order to recover from incomplete ink jet, and a memory for storing the operation frequency of the maintenance station. The ink jet recorder further comprises a maintenance level decision means for varying the recovery operation depending on the operation frequency of the maintenance station when a signal for operating the maintenance station is detected through the maintenance switch.

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 forming an ink image on a recording medium such as recording paper by flying ink droplets, and more particularly to a maintenance level judging means.

[0002]

2. Description of the Related Art An ink jet recording apparatus directs ink from a plurality of nozzle openings of an ink jet head, a droplet diameter,
This is a recording apparatus capable of obtaining good printing quality by discharging while keeping the discharge speed constant. Further, since the number of ejection ports and the type of ink can be easily increased in the ink jet recording apparatus, color recording has progressed and the ink jet recording apparatus has become a mainstream recording apparatus at present. For this reason, the number of nozzles per ink jet recording apparatus also tends to increase, reaching 80 to 100 holes or more. However, on the other hand, there is also a disadvantage that a nozzle surface having several nozzle openings for ejecting ink becomes dirty, or air bubbles are mixed in the flow path, and if one of the nozzle openings causes ejection failure, good printing cannot be performed. is there. Therefore, a maintenance station is provided in the ink jet recording apparatus as a means for recovering the ejection failure to a normal state.

As means for operating the maintenance station to return to a good discharge state, Japanese Patent Publication No.
As described in US Pat.
A method has been proposed in which the ink is released to the atmosphere during suction and the backflow is suppressed, as in -214795. In general, the wiper is brought into contact with the discharge port surface of the ink jet head and the discharge is performed by moving the wiper and the discharge port surface relatively. A nozzle surface cleaning means for removing ink attached to the outlet surface, a suction port connected to a suction pump or the like, and a discharge port provided with a valve equipped with a valve for communicating with the atmosphere. An ink moving device that recovers by discharging dust and bubbles clogged in the discharge port by suction, and an ink evaporation prevention unit that covers the nozzle with a cap or seal to prevent ink from evaporating from the nozzle. Are combined. The maintenance operation is performed when the user presses a maintenance switch in order to recover the ejection failure to a good ejection state when the ejection failure occurs, or when the ejection failure is predicted in advance according to the storage state, the inkjet recording apparatus is used. This is performed when the stored ink is exhausted and the ink is injected again.

[0004] Discharge failures may be caused by dryness near the nozzle opening, when dust such as paper dust adheres, or when air bubbles enter the flow path. In order to recover them, it is possible to solve the problem by discharging unnecessary ink using an ink moving device. In the case where dust or dust such as paper dust adheres to the vicinity of the nozzle opening due to a minor trouble, the ink can be recovered by discharging the ink near the nozzle. In order to remove the ink, the ink in the flow path must be discharged to the outside of the flow path together with the air bubbles. Since the cause of the ink discharge cannot be identified from the print result, an appropriate amount of the ink discharged using the ink moving device for recovering the discharge failure is used. In order to recover the ink in any case, a large amount of the ink is discharged. . As a result,
Even in the case of a discharge failure caused by a minor cause, a large amount of ink must be discharged, which wastes ink, increases running costs, increases maintenance time, and increases throughput. There is a problem such as lowering. Especially when pigment ink is used, the re-dissolvability and re-dispersibility of the dried ink are poor,
Since the amount of ink discharged at the time of recovery increases, the amount of wasteful use of ink increases, and the problem is further exacerbated.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ink jet recording apparatus having a maintenance level judging means which does not wastefully discharge ink even when a discharge failure occurs.

[0006]

In order to solve the above problems, an ink jet head having a nozzle opening at least on a nozzle surface for discharging ink, a pigment ink using a pigment as a coloring agent, and an ink jet head A drive waveform generating circuit for discharging from the nozzle opening of the head, a timer for measuring a time after maintenance including ink movement is completed, a counter for counting the number of print lines, and at least a nozzle surface cleaning device An ink moving device for discharging ink from the nozzles, a maintenance station including an ink evaporation preventing means for preventing ink from evaporating from the nozzles, and a maintenance switch for operating the maintenance station to recover ejection failures, Memory to know the frequency of maintenance station operation And a maintenance level detection means for changing a recovery operation according to the operation frequency of the maintenance station when a signal for activating the maintenance station is detected by a maintenance switch. If the value stored in the storage device for knowing the operation frequency of the maintenance station of the means is such that maintenance including ink movement has been performed, a value is added according to the ink movement condition, and the value after the maintenance is completed by the timer. Measure the time and use at least one method when maintenance including ink movement is not performed for a certain period of time or when maintenance including ink movement is not performed while performing fixed line printing. To decrease the value, During within 3 hours from 10 seconds, the number of printed lines 10 lines for reducing 15
It is characterized by being within 0 rows. That is, claim 1
In an inkjet recording apparatus, an inkjet head having a nozzle port at least on a nozzle surface for discharging ink, a pigment ink using a pigment as a colorant,
A drive waveform generating circuit for discharging the ink from the nozzle openings of the inkjet head, a timer for measuring a time after maintenance including ink movement is completed, a counter for counting the number of print lines, and at least A maintenance station including a nozzle surface cleaning device, an ink moving device for discharging ink from the nozzle, an ink evaporation preventing means for preventing ink from evaporating from the nozzle, and a maintenance station for operating the maintenance station for recovering ejection failure An ink jet recording apparatus comprising a maintenance switch and a storage device for knowing the frequency of operation of the maintenance station. When a signal for activating the maintenance station is detected by the maintenance switch, the frequency of the operation is determined by the frequency of operation of the maintenance station. And having a maintenance level determining means for varying the operation. In the ink jet recording apparatus according to the second aspect, the value stored in the storage device for knowing the operation frequency of the maintenance station of the maintenance level judging means is added according to the ink transfer condition when maintenance including ink transfer is performed. So that the timer measures the time since the end of maintenance,
The value may be reduced by using at least one method when maintenance including ink movement is not performed for a certain period of time, or when maintenance including ink movement is not performed while performing fixed line printing. It is characterized by doing. In the ink jet recording apparatus according to the third aspect, the value stored in the storage device for knowing the operation frequency of the maintenance station of the maintenance level determination means can be reduced within 10 seconds to 3 hours, and the print line for reducing the value can be reduced. The number is within 10 to 150 lines.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following configuration.

(Embodiment) The maintenance level judgment means of the present invention will be described. The nozzle surface of the inkjet head is stained with ink and paper dust of the paper by performing printing. When a discharge failure occurs due to ink contamination around the nozzle, the discharge state is particularly abnormal, so that the contamination further progresses, and other nozzles around the nozzle where the discharge failure has occurred are also stained. Increase. If the nozzle is left dirty, the pigment ink dries and solidifies gradually, impairing the function of the inkjet head. Since a plurality of nozzles are formed in the inkjet head, some nozzles are hardly used during printing. In this nozzle, the liquid component of the ink evaporates during printing, and the viscosity increases. Since the pigment is not soluble in water, it is necessary to use an ink using a pigment as a coloring material in order to obtain a printing result requiring water resistance. In order to require complete water resistance for the printing result, a resin for fixing the pigment to the recording paper is required. As a method of adding the resin, when dispersing the pigment in the liquid, a polymer that does not dissolve in water once dried in the dispersant is used, or the resin having a fixing function is dispersed in the ink as an emulsion. There are methods. The pigments in the ink are configured so that they do not agglomerate due to Van der Waals forces or the like, but when the liquid component in the ink evaporates, the pigment particles adhere to each other to form a large mass. This mass has the property that it does not redisperse when the liquid component is simply given again. As described above, since the pigment ink contains components that are not dissolved again after drying once or components that are not redispersed, once dried and solidified, the pigment ink cannot be removed by dispersion or dissolution. For this reason, it is necessary to remove dirt around the nozzles using an ink moving device. In order to recover this state, the ink in the problematic portion (ink around the nozzle opening) may be operated and discharged by operating the ink moving device.

During printing, a process is performed in which a pressure necessary for discharge is applied to a pressure chamber in the ink jet head to discharge ink from nozzle openings. At this time, the surface of the ink formed in the nozzle largely moves. Especially after ejecting the ink,
Since the amount of the ejected ink is reduced, the ink surface largely recedes. In this state, since the next ink cannot be discharged, the ink is immediately filled in the nozzle. When the operation of moving the surface of the ink forward or backward is repeated in this manner, air bubbles may enter the nozzle serving as a flow path and hinder ejection. Since the bubbles are elastic, even if a pressure is applied to discharge the bubbles in a state where the bubbles enter the flow path, the pressure is absorbed according to the amount of the bubbles, so that good discharge cannot be performed. I will. In addition, there is a case where bubbles enter the flow path when the amount of ink stored in the ink jet recording apparatus decreases, causing the bubbles to be drawn into the flow path together with the ink. When such a phenomenon occurs, it is necessary to discharge the ink in the flow path together with the air bubbles, so that a larger amount of ink movement is required than a small amount of ink movement when a trouble occurs near the nozzle. Most of the causes when the discharge failure occurs are often caused by trouble around the nozzle opening. It is difficult to determine the ejection failure that has occurred in this way from the printing result. When ink is discharged from the nozzles by performing ink movement every time a discharge failure occurs, the discharged ink cannot be used for printing.
The amount of wasteful ink disposal increases. Especially when performing maintenance including ink movement taking into account the entrapment of air bubbles that occur less frequently than troubles around the nozzle opening,
Ink used for printing decreases sharply.

Therefore, the maintenance level determination means of the present invention
The maintenance including the appropriate ink movement can be performed according to the frequency of the maintenance including the ink movement.
The maintenance level determining means of the present invention will be described with reference to FIG. In order to perform maintenance including appropriate ink movement, a storage device for knowing the operation frequency of the maintenance station is installed in a circuit board in the inkjet recording apparatus. The frequency value expressing the frequency is stored as a numerical value. The frequency value is set to indicate an initial value when the power is turned on. The frequency value can be referred to whenever the maintenance switch signal is detected. As the frequency value, a value corresponding to the amount of ink movement is added to the frequency value when maintenance including ink movement is performed.
For example, if maintenance including a small amount of ink movement is performed to recover ejection failure due to a defect near the nozzle, +1 is added, or if a large amount of ink movement is performed such that ink is first injected into the inkjet head, By adding +3, a value corresponding to the ink movement amount is added to the frequency value. The frequency value does not change when maintenance such as idle discharge that does not include ink movement is performed. The number of steps to be added to the frequency value may be 10 or 100, but considering complexity, it is preferable to be within 10 steps. When the ejection is good and no printing failure occurs, the maintenance switch is not pressed, so it can be determined that the ejection is good. In this case, the frequency value is reduced. A method of determining that the ink is ejected satisfactorily is to provide a timer on the circuit board that measures the time from the end of the maintenance including the previous ink movement, and refer to this time for the maintenance switch for a certain period of time. If no signal is detected, it is determined that printing has been performed satisfactorily for a certain period of time, and the frequency value is reduced or returned to the initial value. Also, use a counter to count how many lines have been printed since the previous maintenance, including the previous ink movement, installed on the circuit board.After finishing the maintenance, refer to the number of printed lines. If no signal from the maintenance switch is detected during the set line, it is determined that printing has been performed for a certain period of time,
Reduce the frequency value or return to the default value. As for the condition for reducing the frequency value, the effect can be obtained by using either the printing time or the number of printing lines, but the effect is further enhanced by using both. If the setting time is too long, the frequency value does not decrease for a long time, and the amount of wastefully used ink increases. If the time is too short, the required amount of ink movement cannot be obtained. For this reason, in an ink jet recording apparatus that prints cut paper, the time until output per sheet is set, and in an ink jet recording apparatus that prints continuous paper such as roll paper, one information amount is printed. Time to end is preferred. For example, from 10 seconds to 60
Seconds are more efficient. If the number of lines to be set is too long, the frequency value does not decrease for a long time, so that the amount of wastefully used ink increases. On the other hand, if the number of rows is too short, it is not possible to obtain the required amount of ink movement. For this reason, in an ink jet recording apparatus that prints cut paper, the number of lines until output per sheet is set, and in an ink jet recording apparatus that prints continuous paper such as roll paper, one information amount is set. It is preferable to set about the number of lines until printing is completed. For example, 10
From the row to about 60 rows are efficiently excellent. If maintenance including ink movement is not performed after the power is turned on and printing is possible, or if good ejection continues and the frequency value returns to the initial value, the previous ink movement Since the frequency value does not need to be reduced by the value of the counter that knows how many lines have been printed since the completion of maintenance, or the value of the timer that knows how much time has passed, the frequency value does not change To do.

When a signal from the maintenance switch is detected at any time, in order to perform optimal maintenance,
The difference between the initial value and the frequency value is calculated by referring to the frequency value. At the maintenance level where the value of the difference is the maintenance level, the maintenance including the ink movement amount corresponding to this value is performed. When such maintenance level determination means is used, it is assumed that a discharge failure has occurred when printing is continued satisfactorily and the frequency value indicates the initial value. At this time, when the maintenance switch is pressed, a recovery operation due to a trouble around the nozzle opening with a small amount of ink movement can be performed at first, so that the amount of wastefully discharged ink is reduced. The normal ejection failure is almost always recovered by maintenance for troubles around the nozzle with a small amount of ink movement. Then start printing,
If printing is performed for a certain period without ejection failure, the frequency value returns to the initial value, and even if ejection failure occurs after printing has been performed for several tens of minutes, the amount of ink movement is small. If the cause of the ejection failure is due to the entrapment of air bubbles, it cannot be recovered by the amount of ink movement sufficient to recover the trouble in the vicinity of the nozzle. In this case, when the maintenance level is judged because the frequency value has increased in the previous maintenance including the ink movement, the maintenance value including the appropriate ink movement amount should be performed when the maintenance level value is increased. Can be. Since the amount of ink movement when the frequency value is the initial value is small, the amount of ink discharged required for maintenance when air bubbles are mixed does not change much, so that the influence is small.

An ink moving device for discharging ink from the nozzle includes a suction device that covers the nozzle provided on the nozzle surface by using a cap, and depressurizes the inside of the cap to suction and discharge the ink. Any type of pressurizing device can be used, which presses ink out of the nozzles to discharge unnecessary ink. As a nozzle surface cleaning device for removing ink on the nozzle surface, a nozzle surface cleaning member in which an elastic base is attached to a holder serving as a support and the surface of the elastic body is covered with a sheet-like ink absorbing member is used. did. As the base elastic body, a porous body such as rubber or sponge or a fiber entangled with felt or the like can be used. In this embodiment, rubber is used. As the ink absorbing member, polyester and nylon were used. The ink absorbing member is made to be able to expose a new surface when the ink is absorbed and becomes dirty. As an operation, the nozzle surface cleaned with ink and the nozzle surface cleaning member are moved to the opposite position. Next, by bringing the nozzle surface cleaning member into contact with the nozzle surface, the ink penetrates the ink absorbing member and the ink on the nozzle surface is moved to the nozzle surface cleaning member side. The contact pressure was set to a pressure at which the ink absorbing member was brought into close contact with the nozzle surface. The contact was maintained while the ink on the nozzle surface moved to the ink absorbing member.
Next, since there is a case where ink that cannot be absorbed by the ink absorber remains, the nozzle surface cleaning member and the nozzle surface are removed by relatively moving. The number of operations of moving the nozzle surface cleaning member and the nozzle surface in relative contact with each other was performed twice. Thus, the nozzle surface was cleaned.

(Examples 1 to 27 and Comparative Examples 1 to 1)
0) FIG. 2 is a schematic view of an ink jet recording apparatus embodying the present invention. In FIG. 2, reference numeral 1 denotes a carriage, which includes a head holder 3 for holding an ink jet head 2 having a nozzle surface subjected to a water-repellent treatment, an ink tank 4, a relay member 5 for connecting the ink jet head 2 and the ink tank 4, and a circuit board 7. Mount. The inkjet head 2 has a plurality of ejection ports for ejecting inks of different colors.
A carriage motor (not shown) drives the carriage 1 via the timing belt 8 and reciprocates left and right along the guide rail 9 in the figure. The FPC 30 connects a drive circuit (not shown) to the circuit board 7. On the other hand, a paper feed motor (not shown) drives the paper feed roller 31 and the paper discharge roller 12, pulls out the recording paper 32 onto the platen 14, and moves the recording paper 32 in a direction perpendicular to the moving direction of the carriage. in this way,
While moving the carriage 1 and the recording paper 32, the position of each head 2 on the recording paper 32 is two-dimensionally changed, and ink is ejected from the heads 2 according to a recording signal by a known means such as piezoelectric driving. Accordingly, a recording pattern such as an image and a character can be recorded on the recording paper 32. A nozzle surface cleaning unit 18 for removing dirt on the nozzle surface of the inkjet head and an ink moving unit 2 for removing unnecessary ink and bubbles inside the nozzles are provided beside the printing area.
1 is provided. In the ink jet recording apparatus of this embodiment, an ink moving device capable of discharging ink by suctioning with a cap is provided. An aqueous pigment obtained by dispersing at least a pigment such as phthalocyanine, azo-based, perylene-based or carbon black as a colorant in water, and adding 0 to 40 parts by weight of a humectant having a moisturizing function such as glycerin, diethylene glycol or propanediol. Ink was used. The value to be added to the frequency value when maintenance including ink movement is performed is incremented by +1 when the value is up to the ink movement amount for solving the problem around the nozzle.
Is added, and +2 is added when exceeding the ink movement amount for solving the problem around the nozzle and up to the ink movement amount for removing the mixed air bubbles, and the ink movement amount for removing the mixed air bubbles is added. Beyond that, in the case of the ink movement amount for refreshing the ink in the whole flow path, +3 is set to be added. As a condition for reducing the frequency value, if the signal from the maintenance switch is not detected for a set time (variable) after the completion of the maintenance including the previous ink movement, the frequency value is set to the initial value. Was set to return to. Also, after the maintenance including the previous ink movement has been completed, set lines (variable)
If the signal from the maintenance switch was not detected during the printing of, the frequency value was set to the initial value. In addition, it was set so that only one of the timer and the line number counter could be used. When the value of the maintenance level is less than +2, the determination condition for performing the maintenance including the ink movement by detecting the signal from the maintenance switch includes the ink movement amount necessary to solve the trouble around the nozzle. In the case of performing the maintenance, the maintenance including the amount of ink movement for removing the air bubbles mixed in the flow path is performed between +2 and less than +3, and in the case of +3 or more, the ink in the flow path is refreshed. It is set to perform maintenance including the amount of ink movement to perform. Using this ink jet recording apparatus, printing was continuously performed for 5 hours while changing the condition for decreasing the frequency value, and the operation of turning off the power supply for 3 hours and suspending was repeated until the ink was exhausted. Further, printing was performed in the same manner under the condition that the maintenance level judging means was not used. Several ejection failures occurred during printing, and maintenance was performed by pressing the maintenance switch. In the evaluation, the amount obtained when the maintenance level judging means was not used was set to 1, and the amount of printing obtained when the maintenance level judging means was used was compared to determine the effect from the ratio. . Table 1 shows the results. As a result, in Examples 1 to 10 and Comparative Examples 1 to 6, if the time until the frequency value is returned to the initial value is set within 5 seconds, which is a short time after the previous maintenance, Discharge failure may not be improved. On the other hand, if the set time is too long, a large amount of ink is always discharged, so that the printing amount ratio does not improve. When the set value is within the range of 10 seconds to 3 hours, the print amount ratio is improved, and particularly when the set value is within the range of 10 seconds to 60 seconds, the effect is particularly large. In Examples 11 to 18 and Comparative Examples 1 and 9 to 10, if the number of print lines until the frequency value is returned to the initial value is set to three or less, the ejection failure may not be improved. Also, if the set number of lines is too large, a large amount of ink will always be discharged,
The printing amount ratio does not improve. When the set value is in the range of 10 to 150 lines, the print amount ratio is improved, and particularly in the range of 10 to 60 lines, the effect is particularly large. In the nineteenth to twenty-seventh embodiments, the frequency value is returned to the initial value when either the time setting or the setting of the number of print lines satisfies the set condition. It can be seen that the printing amount ratio is improved.

[0014]

[Table 1]

[0015]

As described above, according to the present invention, even if a discharge failure occurs during printing, the amount of wastefully consumed ink can be reduced when the ink is recovered to a good state. Increased. As a result, running costs have been reduced, and since pigment inks that consume a large amount of ink during maintenance can be used, water resistance,
Printing with excellent light fastness can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a maintenance level determination unit of the present invention.

FIG. 2 is a schematic diagram of an ink jet recording apparatus.

[Explanation of symbols]

 Reference Signs List 1 carriage 2 inkjet head 3 head holder 4 ink tank 5 relay member 7 circuit board 8 timing belt 9 guide rail 12 paper discharge roller 14 platen 18 nozzle surface cleaning means 21 ink moving means 30 FPC 31 paper feed roller 32 recording paper

Claims (3)

[Claims] 1. An ink jet head having a nozzle port on at least a nozzle surface for discharging ink, a pigment ink using a pigment as a colorant, and a drive waveform generation for discharging the ink from the nozzle port of the ink jet head. A circuit, a timer for measuring the time since maintenance including ink movement is completed, a counter for counting the number of print lines, at least a nozzle surface cleaning device,
A maintenance station comprising an ink moving device for discharging ink from the nozzles, an ink evaporation preventing means for preventing ink from evaporating from the nozzles, a maintenance switch for operating the maintenance station for recovering ejection failure, and maintenance. An ink jet recording apparatus comprising a storage device for knowing the operation frequency of the station, and when a signal for activating the maintenance station is detected by a maintenance switch, the operation frequency of the maintenance station is used.
An ink jet recording apparatus comprising a maintenance level determining means for changing a recovery operation. 2. The method according to claim 1, wherein the value stored in the storage device for knowing the operation frequency of the maintenance station of the maintenance level judging means is added according to the ink movement condition when the maintenance including the ink movement is performed. Measure the time from the end of the maintenance in the case where maintenance including ink movement was not performed for a certain period of time, or when maintenance including ink movement was not performed while performing fixed line printing. 2. The ink jet recording apparatus according to claim 1, wherein the value is reduced by using at least one of the methods. 3. The time for reducing the value stored in the storage device for knowing the operation frequency of the maintenance station of the maintenance level determination means is within 10 seconds to 3 hours,
3. The ink jet recording apparatus according to claim 1, wherein the number of print lines to be reduced is within 10 to 150 lines.