JPH0712668B2 - Clogging prevention device for liquid jet recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a clogging prevention device for a liquid jet recording apparatus, in which a lid member is attached to the recording head portion during non-printing to prevent clogging of the recording head portion. Regarding

[Conventional technology]

In a general liquid ejecting recording apparatus, if the nozzle hole of the recording head unit for ejecting ink droplets of the recording apparatus is left in the atmosphere, the ink filled in the nozzle is dried and solidified, or the density of the ink is reduced. However, there is a problem in that the ink viscosity increases and the so-called clogging occurs, making it impossible to eject ink droplets. In order to prevent the orifice image of the recording head from coming into contact with the outside air at the time of non-recording such as before the recording is started or after the recording is completed, a device has been proposed in which the crowning member is brought into close contact with the orifice surface.

However, ink used in the liquid jet recording apparatus includes water-based ink and oil-based ink, and the factors that increase the viscosity of these inks are due to evaporation and drying of volatile components in the ink as described above. In addition to the above, there is an increase in the ink viscosity due to a decrease in the ink temperature, and even if the orifice surface of the recording head is sealed with a capping member to prevent ink drying inside the nozzles of the recording head, When the ink is cooled by the cap member, non-ejection of ink drops occurs due to an increase in ink viscosity. That is, in general, the temperature dependence of the ink viscosity varies depending on the solvent that constitutes the ink, the concentration of the dye contained in the ink, and the like, but the viscosity increases when the ink temperature decreases, regardless of whether it is water-based or oil-based. . Therefore, if the ink temperature drops and the ink viscosity increases too much, the ejection power from the inkjet recording head becomes insufficient.

FIG. 6 shows the relationship between the ink viscosity and the ink temperature in the case of the water-based ink shown in FIG. 6, in which the shaded portion shows the limit at which the ink is appropriately ejected. In such a low temperature environment, even when the temperature T _{H of the} recording head is sufficiently higher than the ink ejection lower limit temperature T _H1 , the temperature of the capping member T _C1 becomes lower than the ink ejection lower limit temperature T _H1. If
The ink in the nozzle of the recording head is cooled, the ink temperature T _N in the nozzle is lower than the ink ejection lower limit temperature T _H1, and it becomes impossible to eject ink droplets.

On the other hand, the ink temperature rises too much, and the ink viscosity drops too much when it exceeds the ejection upper limit temperature T _H2 , so that a stable ejection state cannot be obtained when ejected from the orifice of the recording head. Since problems such as the generation of many satellites occur, it is necessary to keep the ink temperature between T _H1 and T _H2 , such as T _N2 .

That is, the clogging of the recording head cannot be completely eliminated by simply pressing the sealing member into contact with the orifice surface of the recording head for sealing or controlling the temperature of the recording head, and the sealing member is sealed. Even in this state, it is necessary that the ink in the nozzle be controlled within an appropriate temperature range and that its viscosity be maintained in an appropriate state.

[Problems to be solved by the invention]

In view of the above points, an object of the present invention is to eject a liquid in a recording head in which evaporation and drying of volatile components of ink in the nozzle are prevented, and ink ejection failure does not occur even in a low temperature environment where viscosity is easily increased at low temperature. An object is to provide a clogging prevention device for a recording device.

[Means for solving problems]

In order to achieve such an object, the present invention provides a cap member that covers the ejection port forming surface of a recording head that ejects a recording liquid from an ejection port, a head heating unit that heats the recording head, and a temperature of the recording head. In a clogging prevention device of a liquid jet recording apparatus having a head temperature control means for controlling the head heating means so that T _H falls within a predetermined temperature range, a space formed by covering a discharge port forming surface with a crowning member. A holding means for holding the volatile component of the recording liquid, a heating means for heating the crowning member, and a temperature T _{C of the} crowning member in a temperature range T _H1 <T _H ≦ T _C <T _H2 (T _H1 is the ejection limit lower limit temperature of the recording liquid, and T _H2 is the ejection limit upper limit temperature of the recording liquid), and a control unit for controlling the heating unit is provided.

[Work]

In the clogging prevention device configured as described above, the clogging member is loaded with the liquid holding member impregnated with the volatile component in the ink, so that the volatile component of the ink in the nozzle is evaporated to increase the viscosity. The clogging is prevented, and the clogging due to the low temperature thickening can be prevented by appropriately controlling the heating of the crowning member by the heating means.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail and specifically with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which 1 is a carriage on which a recording head 2 is mounted, and 3 is a guide rail which holds a carriage 1 movably. Both ends of an endless belt 4 are connected to the carriage 1 and are driven by a drive motor 5 to move along the recording surface of the recording paper 6. 7 is a roller for feeding the recording paper 6, 8A and 8B
Is a guide roller, and 9 is a paper feeding motor.

On the other hand, the recording head 2 is provided with a plurality of nozzles 10 for ejecting ink droplets toward the recording paper 6 in a vertical row, and the nozzles 10 are supplied with ink 13 from the ink tank 11 to the nozzles 10 via the supply tubes 12. Is further supplied, and the ink ejection signal is selectively supplied via the flexible cable 12A. Furthermore, the recording head 2 is provided with a head heating means (hereinafter referred to as a head heater) 14 and a means 15 for detecting the temperature of the head 2, and a detection signal from the temperature detection means 15 is a control circuit having a microprocessor. By inputting it to 28, the switch 17 connected to the power supply 16 via the driver 30 can be turned on / off, and heating by the head heater 14 can be controlled.

Reference numeral 18 denotes a crowning member that is crowned on the orifice surface of the recording head 2 during non-recording.
And the crowning member 18 is pressed against the orientation surface. Reference numeral 19 is an elastic body attached to the crowning member 18 on the crowning side, 20 is heating means for the crowning member 18 (hereinafter referred to as a cap heater), 21 is a power source for heating, and 22 is a switch. Further, reference numeral 23 is a temperature detecting element. Again, by inputting a detection signal from the temperature detecting element 23 to the control circuit 28, the switch 22 is turned on / off via the driver 32, and the temperature of the crown member 18 is appropriately adjusted. Can be controlled.

Therefore, in this example, the crowning member 18 is configured as shown in FIG. 2B. That is, 24 is a solution of volatile components in the ink,
The capping member 18 is provided with a liquid holding member 26 in which the solution 24 is housed in the hermetically sealed container type space 25 and is impregnated with the solution 24, and thus the volatile vapor of the solution 24 is filled in the space 25. The tip orifice 10A of the recording head nozzle 10.
It is intended to prevent the volatile component of the ink 13 from evaporating and prevent the ratio of the volatile component of the ink 13 in the nozzle 10 from changing.

This means that when the solution 24 and the liquid holding member 26 are not contained in the container type space 25 as shown in FIG. 2A, the temperature T _C of the capping member 18 is set to the temperature T _{H of the} recording head 2. If you keep the nozzle 10 closed while keeping it higher,
Evaporation of the volatile components of the ink 13 in the nozzle 10 is promoted toward the space 25, and as shown in this figure, the ink 13 in the nozzle 10
A concentration gradient occurs in

Therefore, assuming that the volume ratio of volatile components in normal ink is a%, the ratio decreases as it approaches the orifice 10A, such as a / 2%, a / 4%, and a / 8%. However, as a result, the viscosity at the tip of the nozzle 10, that is, in the vicinity of the orifice 10A, increases due to evaporation, so that the viscosity becomes higher than the ink ejection limit viscosity ρ _H1 (see FIG. 4), and ink droplets may not be ejected. is there. On the other hand, with the configuration shown in FIG. 2B, the viscosity of the ink 13 in the nozzle 10 is maintained in a good state so that stable ejection can be obtained without generating a concentration gradient of volatile components. can do.

Here, as the ink volatile component solution 24 used,
The ink 13 itself or a solution containing no dye contained in the ink, or distilled water or the like in the case of an aqueous ink is effective, and a sponge-like porous member or a plastic sintered body or the like is effective as the liquid holding member 26. Is.

Next, the operation of the liquid jet recording apparatus and the clogging prevention apparatus thereof thus configured will be described. In FIG. 1, first, during recording, the carriage 1 is driven to move in the direction of arrow A from the recording start position shown in the figure, and each nozzle 10 of the recording head 2 is selectively driven to eject ink droplets from each nozzle 10. Ink droplets adhere to the recording width portion P of the recording paper 6 facing each nozzle 10 in the sub-scanning direction, so that recording is performed in a dot matrix pattern. Thus, when the recording for one line is completed, the carriage 1
Is driven in the direction of the arrow B to return to the position shown in the drawing, and the recording paper 6 is moved to the position indicated by the arrow C by the width of the recording width portion P described above.
The paper is fed in the direction, and the above operation is repeated again.

On the other hand, at the time of non-recording, the carriage 1 is driven in the direction of the arrow B from the position shown in the drawing, and the recording head 2 is attached to the cap member 18.
When it is moved to a position opposite to, the crowning member 18 is displaced in the direction of arrow D by a driving means (not shown),
As shown in FIG. 2B, a member is provided on the orifice surface of the recording head 2.
18 is pressed and capping is performed. In this case, the elastic body 19 of the crowning member 18 is in close contact with the orifice surface, so that the space 25 is sealed and the individual orifices 10 are closed.
A is kept in direct contact with the solution vapor in this limited space 25.

Therefore, in this case, as described above, when the temperature of the capping member 18 is lower than the lower limit temperature T _H1 which is the ink ejection limit, the ink 13 at the tip of the nozzle 10 is cooled when sealed and ejected as a result of low temperature thickening. Since it becomes impossible, the head heater 14 mounted on the recording head 2 is controlled on the basis of a signal from the head temperature detecting means 15, and the cap heater 20 mounted on the cap member 18 is connected to the temperature detecting element 23. It controls based on the signal from.

An example of the control operation will be described with reference to FIG. First,
If the key switches (not shown) of the power supplies 16 and 21 are turned on in step S1 and it is confirmed in step S2 that the clogging prevention device is in operation, the process proceeds to step S3, in which the recording head 2 is operated. Of temperature T _H is higher than a predetermined lower limit temperature T _H of ink ejection. If the temperature T _H becomes higher than the lower limit temperature T _H1 , the switch 17 is energized to turn on the head heater 14 in step S4. There is no “on” state, and the temperature T _{H of the} recording head is set to be _{equal to} or higher than the lower limit temperature T _H1 .

Next, in step S5, it is determined whether or not the temperature T _H of the recording head 2 is lower than the upper limit temperature T _{H2 of} ink ejection. If it exceeds the upper limit temperature T _H2 , the switch 17 is deenergized in step S6. The head heater 14 to the "off" state. Then, in step S7, it is determined whether or not the temperature T _C of the crowning member 18 is maintained at the temperature T _H of the recording head 2 or more, and it is determined that the temperature T _C is not maintained at the head temperature T _H or more. For example, in step S8, the switch 22 is urged to turn on the cap heater 20.

If the temperature T _C is maintained at the head temperature T _H or higher in step S7, the process proceeds to step S9, where the cap member temperature T _C is lower than the ink ejection upper limit temperature T _{H and} α ° C. higher than the head temperature T _H. (Α
It is judged whether it is in a high temperature range,
If the cap temperature T _C is not lower than the temperature (T _H + α), the cap heater 20 is turned off in step S10.

Further, if it is determined in step S9 that the cap temperature T _C is not maintained at the temperature T _H + α or lower, the process proceeds to step S11, and it is determined whether or not the clogging prevention device is continuously operated. If it is continued, the process returns to step S3 to repeat the same operation, and if it is not continued, the power is turned off in step S12.

In the control described above, the cap temperature T _C is controlled to be lower than the ink ejection upper limit temperature T _H2 and between the head temperature T _H and a temperature 30 ° C. higher than the head temperature T _H. This is experimentally confirmed by the inventor of the present application as a suitable condition for preventing clogging of the inkjet recording apparatus.

FIG. 5A shows an example of the temperature change state when temperature control is performed by the sequence operation procedure as described above. First, the head temperature T _{H is set} to the ejection lower limit temperature T _H and the upper limit temperature T _H2 . The cap temperature T _C is set higher than the head temperature T _H while being controlled so as to be kept between 30 _{° C.} and higher than the temperature T _H.
The temperature of the capping member 18 is maintained in a temperature range suitable for ink ejection as shown by hatching by controlling so that the temperature is maintained below the upper limit temperature T _{H2 within a} range not exceeding ℃. Can be made.

Next, another embodiment of the control operation by the clogging prevention device of the present invention will be described with reference to FIG. Also in this example,
The operation procedure from step S1 to step S12 does not change, but in the case of this example, in steps S7 to S10, the cap temperature T _C is controlled so as to keep the limit width limited, and the cap temperature is controlled. T _C is the head temperature T _H
And controls so as to have a vertical width of more β (β = 0 ℃ ~30 ℃ ) (γ = 0 ℃ ~5 ℃) for high temperatures (T _H + β).

FIG. 5B shows an example of the state of temperature change when such temperature control is performed.In this example, the cap temperature T _C is kept between the lower limit temperature T _H and the upper limit temperature T _H2. For the head temperature T _H to be drooped, (T _H
The temperature can be held in a range having a temperature range of γ above and below the temperature holding line of + β).

〔The invention's effect〕

As is clear from the above description, according to the clogging prevention device of the liquid jet recording apparatus of the present invention, the capping member of the recording head is provided with a container-like space, and the volatile component solution in the ink and the space The liquid holding member impregnated with the volatile component solution is housed, and the recording head and the crowning member are individually provided with heating means and means for detecting the temperature, and the temperature of the crowning member is appropriately increased by the temperature of the recording head. By controlling the temperature so that the ink in the nozzles of the recording head is prevented from being lowered by the capping member, the solution in the capping member is prevented from evaporating and drying by saturated vapor. It is possible to provide a clogging prevention device for a liquid jet recording apparatus that can maintain stable ejection without causing non-ejection of ink even in a low temperature environment where the ink in the nozzle easily thickens. It became.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of the configuration of a clogging prevention device of the liquid jet recording apparatus of the present invention, and FIG. 2A is generated in the nozzle when the volatile component solution in the ink is not retained in the capping member. FIG. 2B is an explanatory view schematically showing a change in the ink concentration, FIG. 2B is an explanatory view showing a state in which a capping member holding a volatile component solution according to the present invention is attached to the tip of the nozzle, and FIGS. FIG. 5A and FIG. 5B are temperature charts showing changes in the temperature of the crowning member when controlled by the operation procedure shown in FIGS. 3 and 4, respectively. FIG. 6 is a characteristic curve diagram showing the relationship between the ink temperature and the viscosity of the liquid jet recording apparatus. 1 ... Carriage, 2 ... Recording head, 3 ... Guide rail, 4 ... Endless belt, 5 ... Drive motor, 6 ... Recording paper, 7 ... Roller, 8A, 8B ... Guide roller, 9 ... … Paper feed motor, 10 …… Nozzle, 10A …… Orifice, 11 …… Ink tank, 12 …… Supply tube, 12A …… Flexible cable, 13 …… Ink, 14,20 …… Heating means, 15 …… Temperature Detection means, 16 ... Power supply, 17,22 ... Switch, 18 ... Coupling member, 19 ... Elastic body, 21 ... Power supply, 23 ... Temperature detection element, 24 ... Solution, 25 ... Space, 26 ... Liquid holding member, 28 ... Control circuit, 30, 32 ... Driver.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masaharu Okubo Inventor Masaharu Okubo 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-60-198249 (JP, A) -87128 (JP, U) Actually opened 58-1551 (JP, U)

Claims (3)

[Claims] 1. A and crown adhesive member for covering the ejection opening formation face of the recording head for discharging recording liquid from a discharge port, a head heating means for heating the recording head, the temperature T _H of said recording head
In a clogging prevention device of a liquid jet recording apparatus having a head temperature control means for controlling the head heating means so as to be within a predetermined temperature range, a space formed by covering the ejection port forming surface with the crowning member. A holding means provided in the holding means for holding the volatile component of the recording liquid; a heating means for heating the crowning member; and a temperature T _C of the crowning member in a temperature range T _H1 <T _H ≦ T _C <T _H2 (where T _H1 is the ejection limit lower limit temperature of the recording liquid, and T _H2 is the ejection limit upper limit temperature of the recording liquid), and a control means for controlling the heating means. A clogging prevention device for recording devices. 2. The control means sets the temperature T _C of the cap member to a temperature range T _H1 <T _H ≦ T _C = T _H + α <T _H2 (α is an arbitrary value between 0 ° C. and 30 ° C.). The clogging prevention device for a liquid jet recording apparatus according to claim (1), characterized in that the heating means is controlled so that. 3. The control means is configured such that the temperature T _{C of the} capping member is in a temperature range T _H1 <T _H ≤T _C ≈T _H + α <T _H2 | T _C − (T _H + β) | ≦ γ (β Is a constant value of 0 ° C. to 30 ° C., and γ is an arbitrary value of 0 ° C. to 5 ° C.). The liquid jet recording according to claim (2), wherein the heating means is controlled. Device clogging prevention device.