JPH02217256A - Ink jet recording device - Google Patents

Abstract

PURPOSE:To prevent an occurrence of ink discharge failure by varying the programmed data of a blank discharge action for each ink from a different recording head. CONSTITUTION:A carriage 1 is driven during recording to travel from a recording start position to 'A' position, and at the same time, nozzles 10a, 10b, 10c, 10d of recording heads 2a, 2b, 2c, 2d are selectively driven to perform recording on the recording width section P of recording paper. If a single line of data is recorded, the carriage 1 returns to 'B' position, the recording paper 6 is fed by the width of the recording width section P in C'' direction and this action is again repeated. After this recording action is performed over a specified number of lines, the carriage 1 is driven in 'B' direction using a control circuit 28, and the recording heads 2a to 2d are moved to a position opposed to a capping member 18. Consequently, the capping member 18 is displayed to 'D' position and an elastic element 19 is pressed against each recording head. A signal is connected to the recording head drivers 21a, 21b, 21c, 21d from the control circuit 28 under the above condition. Then ink droplets are discharged from each recording head. Next, the capping member 18 is displaced to 'E' position. Thus it is possible to prevent ink from failing to discharge while ink consumption due to a blank discharge is minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet recording device that performs recording by discharging ink from a recording head, and more specifically, the present invention relates to an inkjet recording device that performs recording by discharging ink from a recording head. The present invention relates to an inkjet recording device.

[Prior Art] An inkjet printer is widely known as a recording device that performs recording by ejecting a liquid recording material. The recording material of inkjet printers is mainly paper, plastic sheets, etc., and has the advantage of low operating noise compared to other recording methods, and the basic mechanical structure can be realized easily and inexpensively. It is often used as a recording/output device such as.

Since this type of apparatus performs recording by ejecting ink directly from the RAD nozzle onto the recording surface, consideration that is not found in other types of printing apparatuses is required to keep the ink in a state where it can be ejected at all times.

For example, since ink remains in the nozzles of the print head even when not printing, measures are required to prevent deterioration such as an increase in viscosity due to drying or evaporation of the ink in the nozzles. For this reason, conventional apparatuses have been known that are provided with a capping means for covering the orifice of the recording head with a lid during non-recording to prevent ink from drying and evaporating.

However, in low-humidity environments or during long-term suspension, an increase in the viscosity of the ink cannot be avoided by using only the above-mentioned capping means. A recovery mechanism was also known in which the ink inside the nozzle was sucked out from the orifice by applying negative pressure, or the degraded ink was discharged from the orifice by applying pressure inside the nozzle using a manually controlled pump or the like.

Such a recovery mechanism is automatically activated when the power is turned on, and is generally not activated during printing unless there is a significant ejection abnormality.However, even during printing, ink quality may change due to unused nozzles. There is something to be gained.

That is, in an apparatus in which a plurality of print head nozzles are provided, there are variations in ejection drive depending on the nozzles, such as some nozzles not ejecting for a long period of time depending on the print data. Therefore, depending on atmospheric conditions such as temperature and humidity, ink from nozzles that eject less times or have longer ejection intervals may dry out and increase its viscosity, resulting in unstable ink ejection or failure to eject. was there.

In order to solve this problem, a method has been proposed in which the print head performs a dry ejection operation in which all nozzles eject ink outside the print area.

[Problems to be Solved by the Invention] However, as inkjet printers that realize so-called full color or multi-gradation have become widespread, the problems with the above-mentioned methods have become more prominent.

That is, such an inkjet printer requires multiple types of ink and recording heads corresponding to each type of ink. Because the components constituting the ink are different in these recording sheets, the conditions under which ejection failure occurs are not necessarily the same. Therefore, performing a dummy ejection operation for all nozzles, that is, all print heads at the same time, will cause the ink to This resulted in unnecessary consumption, which was a factor in increasing running costs.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide an inkjet recording apparatus that performs recording using a plurality of types of ink and a plurality of recording heads corresponding to each type of ink. Another object of the present invention is to provide an inkjet recording apparatus that prevents ink from being ejected and is efficient in ink usage by varying the content of the idle ejection operation for each ink.

[Means for Solving the Problems] To this end, the present invention includes a blank ejection operation control means for moving a recording head that ejects multiple types of ink to a predetermined position outside the recording area and ejecting ink at the position. The inkjet recording apparatus is characterized in that the idle ejection operation control means varies at least one of the ink ejection amount in the idle ejection operation or the interval between the idle ejection operations in correspondence with each of the plurality of types of ink.

[Function] According to the above configuration, the lower the ink viscosity and the less likely to cause ejection failure, the smaller the ink ejection amount such as the number of ejection pulses in the idle ejection operation, or the longer the interval between the idle ejection operations. .

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

Inkjet recording inks generally have different characteristics depending on the concentration of the solvent and dye contained in the ink, but the viscosity of both water-based and oil-based inks varies depending on the ink temperature and the residual rate of volatile components in the ink. Change.

In other words, when the temperature of the ink decreases, or when the residual rate of volatile components in the ink significantly decreases, in other words, when the amount of water evaporation in the ink increases, the viscosity of the ink increases, and the ink viscosity increases to a certain level. If the amount increases too much, the ink may clog the nozzles, etc., making it impossible to eject the ink.

By the way, for example, when using multiple types of ink with different solvent composition mixing ratios, or multiple types of ink with different dye concentrations, the viscosity of the ink changes due to a drop in ink temperature and the evaporation of volatile components in the ink. Changes may not always be the same.

As shown in Figures 3 and 4, in the case of water-based inks, in general, when the water ratio of the solvent is changed, ink B with a lower water ratio is better than ink A with respect to ink temperature and water evaporation amount in the ink. The viscosity is large, and the fifth
As shown in the figure and FIG. 6, ink D, which has a higher dye concentration in the ink, shows a tendency that the ink viscosity with respect to the ink temperature and the amount of water evaporation in the ink becomes larger than that of ink C.

Therefore, the ejection limit temperature TEA + TKB + "KC + TKO at which each ink reaches the ink ejection limit viscosity ρK may differ depending on each ink, and the ejection limit moisture evaporation amount v at which each ink reaches the ink ejection limit viscosity ρ
A, vlS, vc, and vD may also differ depending on each ink, so the time for the ink in the nozzle of the recording head filled with each recording ink to reach the ink ejection limit viscosity ρ varies for each ink. , Therefore, the number of scans in which the print head continues scanning for printing and reaches the ink ejection limit viscosity ρ varies depending on each printing ink.

For this reason, in this example, at least one of the number of idle ejection pulses of the above-mentioned idle ejection operation or the interval of the idle ejection operation is controlled for each recording head corresponding to each of the plurality of types of ink.

FIG. 1(A) is a perspective view showing a schematic configuration of an inkjet recording apparatus according to an example of the present invention.
3 is a carriage on which a plurality of recording heads 2a, 2b, 2c, and 2d are mounted, and 3 is a guide rail that holds the cure ridge 1 movably. Both ends of a belt 4 are connected to the carriage 1, and the belt 4 is driven by a motor 5. As a result, the carriage 1 moves along the recording surface of the recording paper 6.

7 is a roller for feeding the recording paper 6, 8^ and 8B are guide rollers, and 9 is a motor for feeding the paper.

On the other hand, each of the recording heads 2a, 2b, 2c, and 2d has a nozzle 10a that discharges ink droplets toward the recording paper 6.
, 10b, 10c, and 10d, and each nozzle is provided with a different type of ink 13a.

Ink tank lla that accommodates 13b, 13c, and 13d
,llb.

11c, the ink is supplied from the lid through the supply tube 12, and furthermore, the flexible cables 12a, 12b
.

Ink ejection signals are selectively supplied via 12c and 12d. Furthermore, the recording heads 2a, 2b, 2c, 2
d is a head heating means (hereinafter referred to as a head heater) 1
4a, 14b, +4c, 14d and means 15a, 15b, 15c, 15d for detecting the temperature of the head are provided, and detection signals from the temperature detecting means 15a to 15d are inputted to a control circuit 28 having a microprocessor. Accordingly, the heater drivers 3Qa, 30b, 30c, 30d
head heaters 14a, 14b, 14c, 14d via
Heating can be controlled by

Reference numeral 18 denotes a capping member that caps the orifice surfaces of the recording heads 2a to 2d during non-recording, and when the carriage 1 moves in the direction of arrow B and the capping member 18 moves in the direction of arrow B, recording is performed. An elastic body 19, which will be described later, is pressed against the orifice surface of the head. 19 is an elastic body attached to the capping surface of the capping member 18;
8 is equipped with an atmospheric environment temperature detecting means 23 and an atmospheric environment temperature detecting means 2o to monitor the recording environment of each of the recording heads 28 to 2d.

Further, the capping member 18 accommodates a volatile component solution 24 in the ink in its sealed container-shaped space 25 and includes a liquid holding member 26 impregnated with the solution 24.

As a result, the volatile vapor of the solution 24 fills the space 25, and the recording head nozzles loa, lOb, and 10c.

This prevents the volatile components of the inks 13a to 13d from evaporating from the tip orifice 10d.

Note that as the volatile component solution 24 in the ink used here, it is effective to use the ink itself used for recording, a solution that does not contain the dye contained in the ink, or in the case of water-based ink, distilled water, etc. As the member 26, a sponge-like porous member, a plastic sintered body, or the like is effective.

Next, the operation of the liquid jet recording apparatus configured as described above will be described. In FIG. 1, during recording, the carriage 1 is driven and travels in the direction of the arrow from a recording start position (not shown), and each recording head 2a, 2b, 2c, 2d
The nozzles lea, 10b, lOc, and lOd are selectively driven, ink droplets are ejected from each nozzle, and the ink droplets adhere to the diagonally shaded recording width portion P of the recording paper 6 facing the nozzles. , recording is performed in a dot matrix pattern.

When one line of recording is completed in this way, the carriage 1 is driven in the direction of arrow B and returns to the position shown in the figure, and the recording paper 6 is fed in the direction of arrow C by the width of the recording width portion P described above. The above operation is repeated again.

After the above-described recording operation has been performed for a predetermined number of lines, that is, a predetermined number of scans, the motor driver is driven by the control circuit 28, and the carriage 1 is driven from the illustrated position in the direction of arrow B, and the recording heads 28- 2d is moved to a position facing the capping member 18, the capping member 18 is displaced in the direction of the arrow by a driving means (not shown), and the elastic body 1 is placed on the orifice surface of each recording head.
9 is pressed and capping is performed. In this state, the recording head drivers 21a, 21b, 21c, 21d
An idle ejection signal is sent from the control circuit 2δ, and ink droplets are ejected from each of the recording heads 2a, 2b, 2c, and 2d.After the idle ejection operation of the recording heads is completed, the capping member 18 moves in the direction of arrow E. The carriage 1 is then moved in the direction of arrow A and resumes the next recording.

FIG. 1(B) is a block diagram showing the control configuration of the apparatus shown in FIG. 1(A), and only the control configuration for the idle discharge operation according to the embodiment of the present invention is illustrated in the same figure. .

In the figure, 28 mainly consists of a microprocessor, and has RAM 28^ and ROM 28B to control each part of the device. RAM 28^ is used as a work area for control such as counting the number of main scans, which will be described later.
The OM 213B is used to store control procedures for idle ejection operations and recording operations, as well as the correspondence between each ink and the number of idle ejection pulses and the number of main scans for idle ejection, which will be described later.

Recording head drivers 218 to 21d supply driving current to each of the recording heads 28 to 2d based on recording data or idle ejection data from the control circuit 28. 22
is a motor driver that supplies drive current to the motor 5 based on motor drive data from the control circuit 28.

FIGS. 2(^) and 2(B) are block diagrams for explaining the control mode of the idle ejection operation of this example, respectively.

In FIG. 2(^), the control circuit 28 is configured in advance to store the ROM2.
Each recording head driver 21a, 21b, 21c, and 21d is controlled based on the data on the number of idle ejection pulses stored in 8B, and the number of idle ejection pulses Na, Nb, Nc, and Nd are respectively output from each recording head 2a, 2b, 2c, and 2d. Perform a dry discharge.

In this @ control, the number N of idle ejection pulses is reduced because ink with a higher water content in the solvent or ink with a lower dye concentration in the ink is less likely to cause ejection failure due to temperature changes or water evaporation.

For example, in the case of inks A and B or inks C and D shown in FIGS. 3 to 5, each ink A.

The number of idle ejection pulses corresponding to B, C, and D, respectively, is Na,
When Nb, Nc, and Nd, Na<Nb Nc<Nd can be satisfied, and ink A and ink C for idle ejection
consumption can be reduced compared to conventional methods.

Note that in the above control, the number of pulses for idle ejection is varied depending on the type of ink, but the amount of ink ejected in one ejection may be varied.

In the idle discharge control shown in FIG. 2(B), the control circuit 2
8 is each recording head driver 21a, 21b, 21c.

21d and the motor driver 22, and the interval between each blank ejection operation in each recording head 2a, 2b, 2c, and 2d is determined by the number of main scans stored in the ROM 28B and the inks A, B, C, and D. It is characterized in that it is controlled based on the relationship, and is controlled so that the corresponding recording head performs a blank ejection operation for each number of main scans Ma, Mb, Mc, and Md of the carriage 1 counted in the RAM 28^.

Similar to the control shown in FIG. 2(^), this idle ejection operation interval is set so that the main scanning interval M becomes wider for ink that is less likely to cause ejection failure. In this example, recording inks A, B, and C
, D, the corresponding main scanning numbers Ma, Mb,
Mc and Md can be set such that Ma>Mb and Mc>Md, and it is possible to reduce the ink consumption amount due to the idle ejection operation of ink A and ink C compared to the conventional method.

Note that in the above-described embodiment, recording heads corresponding to each color ink were provided separately, but the present invention is applicable even if the recording head is integrally formed with ejection ports, etc. corresponding to each color ink. It is clear that it can be applied.

[Effects of the Invention] As is clear from the above description, according to the present invention, the lower the ink viscosity and the less likely to cause non-ejection, the smaller the ink ejection amount, such as the number of ejection pulses during the idle ejection operation, or the lower the ink ejection amount, such as the number of ejection pulses during the idle ejection operation. The interval can be increased.

As a result, it has become possible to provide an inkjet recording apparatus that can prevent ink failure while minimizing ink consumption due to idle ejection.

[Brief explanation of the drawing]

Figure 1 (^) is a perspective view showing a schematic configuration of an inkjet recording apparatus according to an embodiment of the present invention, and Figure 1 (8) is a block diagram showing a control configuration of the apparatus shown in Figure 1 (A). , FIGS. 2(^) and (B) are block diagrams showing idle ejection control according to an embodiment of the present invention, and FIGS. 3 to 6 show diagrams of water-based ink with different water ratios or dye concentrations in the solvent. FIG. 3 is a diagram showing changes in ink viscosity due to changes in ink temperature and changes in the amount of moisture evaporated in the ink. 2a, 2b, 2c, 2d-recording head, 10a, lOb
, 10c, 10d - nozzle, 11a, llb, llc
, 1ld-ink tank, 13a, 13b, 13c, 1
3d...Ink, 18...Capping member, 19...Elastic body, 21a, 21b, 21c, 21d...-Recording head driver, 22...Motor driver. Figure 1 (B) Figure 5 A > 7X & TsmT+ ("C no ink shallow T-T+ ("C)

Claims (1)

[Scope of Claims] 1) An inkjet recording apparatus having a blank discharge operation control means for moving a recording head that discharges a plurality of types of ink to a predetermined position outside a recording area and for causing ink discharge to be performed at the position. Inkjet recording, wherein the dummy ejection control means varies at least one of the amount of ink ejected in the dummy ejection operation or the interval between the dummy ejection operations, corresponding to each of the plurality of types of ink. Device.