JPH05261939A - Ink jet recording method - Google Patents

Abstract

PURPOSE:To keep the temperature of an ink at a specified temperature or lower, and maintain the discharge capability uniform by a method wherein when the temperature of an ink in the vicinity of a thermal energy working part exceeds a specified temperature, the ink with the increased temperature is forcibly suction-discharged. CONSTITUTION:When the temperature in the vicinity of a thermal energy working part becomes a certain value or higher, a carriage 32 moved from a line during printing to a home position after printing, in which a capping device A is arranged. The ink of which the temperature has ascended in the vicinity of the thermal energy working part in an ink jet nozzle 33, which is provided in the carriage 32, is forcibly suction-discharged from the outside of a discharge port by the capping device A, and a new ink is introduced from the upstream side to the vicinity of the thermal energy working part to decrease the temperature.

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 method, and more particularly to an ink jet recording method for obtaining stable ejection of ink droplets in an ink jet printer.

[0002]

2. Description of the Related Art The non-impact recording method has recently been drawing attention because noise during recording is extremely small to a negligible level. Among the recording methods, high-speed recording is possible, and the so-called inkjet recording means that can record on plain paper without requiring a special fixing process is an extremely powerful recording method. Various methods have been proposed so far, some of which have been improved and commercialized, and some of which are still being put into practical use.

Japanese Patent Publication No. 56-9429 discloses one of the ink jet recording methods as the liquid jet recording method previously proposed by the present applicant. In this method, the ink in the liquid chamber is heated to generate bubbles to cause a pressure increase in the ink, the ink is ejected from a fine capillary nozzle, and recording is performed on a recording member. This publication also discloses the use of, for example, a Bertier effect element as an example of cooling the head, and shows how to eject ink droplets in a stable manner. ..

In this method, the head structure is considerably simplified, and the source of the thermal pulse, that is, the heating element can be used in the semiconductor manufacturing process and can be highly precisely processed. After that, many inventions utilizing this principle have been proposed. By the way, in the ink jet recording method using this principle, when continuously driven at a high speed, heat is accumulated in the head, which changes the physical properties of the ink, which causes a change in ejection performance and a deterioration in print image quality. There is a problem that occurs.

To solve this problem, Japanese Patent Laid-Open No. 55-82663 discloses an ink ejection method based on the same principle as that of Japanese Patent Publication No. 56-9429, but the heating element generates bubbles to eject ink droplets. This is done in view of the problem that the heat for generating bubbles is transferred to other portions as well, and gas such as dissolved oxygen in the recording medium liquid separates to form bubbles.

That is, since such bubbles are not vapors of the recording medium liquid, they tend to remain in the liquid chamber indefinitely without disappearing rapidly even when the temperature drops.
Since the shock wave due to the pulsed vaporization of the recording medium liquid is absorbed, the frequency response of droplet ejection is deteriorated. Therefore, in JP-A-55-82663, in order to suppress the generation of such unnecessary bubbles, the temperature of the recording medium liquid is lowered by using a Peltier element or a refrigerator.

However, according to the results of the study by the present inventors, such an unnecessary bubble may not be generated by appropriately selecting the method of giving the high-speed heat flux for generating the bubble for discharging. found. In particular,
By applying the applied pulse to the heating element instantaneously (within 20 μsec), only bubbles for ejection are generated, and then they disappear instantly, and unnecessary bubbles do not occur. It has not occurred.

Also, in Japanese Patent Laid-Open No. 55-82663, the applicant of the present invention discloses that a refrigerator is used in addition to the Peltier element mentioned as one example of the cooling device in Japanese Patent Publication No. 56-9429. Although it has been proposed, the device itself becomes very large, and it is difficult to say that it is practical in terms of cost and operability.

According to the results of the study conducted by the present inventors, the problem of unnecessary air bubbles, which was a problem in Japanese Patent Laid-Open No. 55-82663, does not occur, but as described above, the heating element is formed. Another problem has been found in that the response speed becomes slower because the next pulse has to be applied after waiting for the heat radiation to accumulate due to the heat being accumulated in the processed substrate.

However, in Japanese Patent Application Laid-Open No. 55-82663, although the substrate temperature is not mentioned, the problem is the generation of unnecessary bubbles, and therefore the problem that the increase in the substrate temperature causes must be solved. In other words, there has been no solution to the decrease in response speed due to having to wait for heat dissipation before giving the next pulse.

On the other hand, Japanese Patent Application Laid-Open No. 61-211045 discloses means for maintaining the temperature of the print head portion within an appropriate ink droplet forming range by using a heater and a blower. Generally, in the ink jet recording method, ink droplet forming conditions are largely changed due to changes in ink physical properties (viscosity, surface tension, etc.), and as shown in the example of JP-A-61-211045, temperature control is performed to It can be said that keeping the physical properties within a certain range is an indispensable technique. In this sense, the technique of the above publication is an excellent invention, but it requires a blower, so that it has a drawback that the entire device becomes large-scale.

Further, Japanese Patent Publication No. 62-55990 discloses that
In the ink jet recording method using the same principle as Japanese Patent Publication No. 56-9429 previously proposed by the present applicant,
A method has been proposed in which residual heat generated by a head is used for drying a recording member. Specifically, a heat pipe is coupled to the upper part of the recording head, the other side of the heat pipe is coupled to a heat radiating plate, and the residual heat generated in the recording head is radiatively carried by the heat pipe, and the heat radiating plate records the member to be recorded. Is to dry. However, the use of heat pipes complicates the device, increases the cost, and increases the cost by simply contacting the heat dissipation plate with the recording material, which leads to high costs. I couldn't do it, and it wasn't so good.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and causes the ink to change its state due to heat, and ejects the ink from a fine orifice to perform recording. In inkjet recording to be performed, we propose a method for obtaining stable ejection of ink with a simple configuration. Specifically, in thermal inkjet recording, heat is accumulated in the recording head due to continuous high-speed driving. , The physical properties of the ink change,
It is an object of the present invention to provide a method for preventing a change in ejection performance and the accompanying deterioration in printed image quality.

[0014]

In order to achieve the above-mentioned object, the present invention generates bubbles by a thermal energy acting portion arranged in a flow path for guiding ink from a liquid chamber to an ejection port, and by the action of the bubbles, In an inkjet recording method of ejecting ink from a discharge port, a temperature detecting means is provided in the vicinity of the thermal energy acting portion or the thermal energy acting portion,
When the temperature of the ink in the vicinity of the thermal energy acting portion exceeds a predetermined temperature by the temperature detecting means, the ink of the increased temperature is forcibly sucked and discharged from the outside of the ejection port to remove the ink in the vicinity of the thermal energy acting portion. It is characterized in that the temperature is set to a predetermined temperature or lower and the ink ejection performance is kept constant.

Further, the present invention provides an ink jet recording method in which bubbles are generated by a thermal energy acting portion arranged in a flow path for guiding ink from a liquid chamber to an ejection port, and ink is ejected from the ejection port by the action of the bubbles. When temperature detecting means is provided in the heat energy acting portion or in the vicinity of the heat energy acting portion and the temperature of the ink near the heat energy acting portion exceeds a predetermined temperature by the temperature detecting means,
The driving frequency of the thermal energy acting portion is changed so that the temperature of the ink in the vicinity of the thermal energy acting portion is equal to or lower than a predetermined temperature, and the ink ejection performance is maintained constant.

[0016]

According to the structure of the present invention, when it is detected that the ink temperature exceeds the predetermined temperature by the thermal energy acting portion or the temperature detecting means provided in the vicinity of the thermal energy acting portion, the ink is forcibly sucked and discharged. Alternatively, the driving frequency is temporarily lowered so that the temperature of the ink in the vicinity of the thermal energy acting portion is equal to or lower than a predetermined temperature, and the ink ejection performance is maintained constant.

[0017]

First, the operation of a bubble jet head as an example of an ink jet head to which the present invention is applied will be described with reference to FIG. 7 is a perspective view of the bubble jet head shown in FIG. 6, and FIG. 8 is a perspective view of the head of FIG. 7 exploded into a lid substrate (FIG. 8A) and a heating element substrate (FIG. 8B). FIG. 9 is a perspective view of the lid substrate shown in FIG. 8A viewed from the back side. In the figure, 1 is a lid substrate, 2 is a heating element substrate, 3 is a recording liquid inflow port, 4 is a discharge port, 5 is a flow path, 6 is a region for forming a liquid chamber, 7 is an individual (independent) electrode, 8
Is a common electrode, 9 is a heating element (heater), 10 is ink, 1
Reference numeral 1 is a bubble, and 12 is a flying ink liquid.

Therefore, the ink ejection by the bubble jet will be described with reference to FIG. (A) is a steady state, in which the surface tension of the ink 10 and the external pressure at the ejection port 4 are in equilibrium. (B) shows a state in which the heating element 9 as a heater is heated, the surface temperature of the heating element 9 rises sharply, and is heated until the boiling phenomenon occurs in the adjacent ink layer, and the minute bubbles 11 are scattered.

(C) shows a state in which the adjacent ink layer that has been rapidly heated on the entire surface of the heating element 9 is instantly vaporized to form a boiling film, and the bubble 11 has grown. At this time, the pressure in the nozzle rises as much as the bubbles grow, the balance with the external pressure on the ejection port surface is lost, and the ink column starts to grow from the ejection port 4. In (d), the bubble 11 has grown to the maximum, and the ink 10 corresponding to the volume of the bubble is pushed out from the ejection port surface. At this time, no current is flowing through the heating element 9, and the surface temperature of the heating element 9 is decreasing. The maximum value of the volume of the bubble 11 is slightly delayed from the timing of applying the electric pulse.

(E) shows a state in which the bubble 11 is cooled by ink or the like and starts to contract. At the front end of the ink column, the ink column moves forward while maintaining the pushing speed, and at the rear end of the ink column, the internal pressure of the nozzle decreases due to the contraction of the bubble 11, and the ink flows backward from the ejection port surface into the nozzle, thus constricting the ink column. Is occurring.

In (f), the bubble 11 is further contracted, the ink contacts the surface of the heating element, and the surface of the heating element is further rapidly cooled. On the orifice surface, the external pressure is higher than the internal pressure of the nozzle, so a large meniscus has entered the nozzle. The tip of the ink column becomes a droplet and flies toward the recording paper at a speed of 5 to 10 m / sec.
(G) is a process in which the ink is supplied to the ejection port again by the capillary phenomenon and returns to the state of (a), and the bubbles are completely extinguished.

FIG. 10 shows an embodiment for explaining the construction of the main part of the above-mentioned liquid jet recording head. FIG. 10 (a) is a front detailed partial view seen from the ejection port side of the bubble jet head.
(B) is a partial cross-sectional view taken along the alternate long and short dash line xx in (a). Recording head 13 shown in this drawing
The structure is formed by arranging and bonding a grooved plate 16 having a predetermined number of grooves of a predetermined linear density and a predetermined width and depth on a substrate 15 having the electrothermal converter 14 provided on the back surface. A liquid ejection portion 18 including an ejection port 17 for ejecting the liquid is formed at the end of the recording head.

The liquid discharge part 18 is a place where the heat energy generated from the discharge port 17 and the electrothermal converter 14 acts on the liquid to generate bubbles, which causes a rapid state change due to expansion and contraction of the volume. And a certain heat acting part 19. The heat acting portion 19 is the heat generating portion 20 of the electrothermal converter 14.
The bottom surface of the heat generation surface 20 is a heat acting surface 21, which is a surface of the heat generating portion 20 in contact with the liquid. Heat generation part 20
Is a lower layer 22 provided on the substrate 15 and the lower layer 22.
The heating resistor layer 23 is provided on the heating resistor layer 23, and the protective layer 24 is an upper layer provided on the heating resistor layer 23.

The heat generating resistance layer 23 is provided with electrodes 25 and 26 for energizing the heat generating layer 23 on the surface thereof so as to generate heat. 20 are formed. The electrode 25 is an electrode common to the heat generating portion 20 of each liquid ejecting portion 18, and the electrode 26 is a selection electrode for selecting the heat generating portion 20 of each liquid ejecting portion 18 to generate heat. It is provided along the liquid flow path of the discharge part 18.

The protective layer 24 fills the heat generation resistance layer 23 and the liquid flow path of the liquid discharge part 18 in order to protect the heat generation resistance layer 23 in the heat generation part 20 chemically and physically from the liquid used. It has a role of separating the existing liquid, preventing a short circuit between the electrodes 25 and 26 through the liquid, and further preventing an electric leak between the adjacent electrodes.

The liquid flow paths provided in the respective liquid discharge parts 18 constitute a part of the liquid flow paths upstream of the respective liquid discharge parts and are communicated with each other through a liquid flow chamber (not shown). There is.
The electrodes 25 and 26 connected to the electrothermal converters 14 provided in the respective liquid discharge parts are protected by the protective layer 24 which is the upper layer and are provided on the upstream side of the heat acting part due to the design. , So as to pass under the common liquid chamber.

FIG. 11 is a detailed view for explaining the structure of the bubble generating portion using a heating resistor, in which 27 is a heating resistor, 28 is an electrode, 29 is a protective layer, and 30 is a power supply device. Shows. As a material forming the heating resistor 27,
Useful, for example, a mixture of tantalum -SiO _2, tantalum nitride, nichrome, silver - palladium alloy, silicon semiconductor or hafnium, lanthanum, zirconium, titanium, tantalum, tungsten, molybdenum, niobium, chromium, vanadium, etc. Examples include metal borides.

Among the materials forming these heating resistors 27, metal borides can be mentioned as particularly excellent ones, of which hafnium boride has the most excellent characteristics. The order is zirconium boride, lanthanum boride, tantalum boride, vanadium boride, and niobium boride. The heating resistor 27 can be formed by using a method such as electron beam vapor deposition or sputtering using the above materials. The film thickness of the heating resistor 27 is determined according to the area, the material, the shape and size of the heat acting portion, and the actual power consumption so that the amount of heat generated per unit time becomes a desired value. In general, it is 0.001 to 5 μm, preferably 0.01 to 1 μm.
It is said that.

As the material forming the electrode 28, many of the commonly used electrode materials can be effectively used.
Specifically, for example, Al, Ag, Au, Pt, Cu, and the like are used, and these are provided in a predetermined position, with a predetermined size, shape, and thickness by means such as vapor deposition.

The characteristic required for the protective layer 29 is that it does not prevent the heat generated by the heating resistor 27 from being effectively transferred to the recording liquid, and protects the heating resistor 27 from the recording liquid. is there. Examples of useful materials for forming the protective layer 29 include silicon oxide, silicon nitride, magnesium oxide, aluminum oxide, tantalum oxide, zirconium oxide and the like. These can be formed using a technique such as electron beam evaporation or sputtering. The thickness of the protective layer 29 is usually 0.01 to
10 μm, preferably 0.1-5 μm, optimally 0.1
It is desirable that the thickness is formed to be about 3 μm.

Based on the above principle, the means for forcibly sucking the ink of the present invention in the bubble jet technology having the heating element structure will be described. FIG. 5 is a perspective view showing an example of the configuration of an inkjet printer to which the present invention can be applied. In FIG. 5, A is a capping device, 32 is a carriage, and 33 is an inkjet nozzle. The carriage 32 is reciprocally driven on a sliding shaft by a linear motor, and the inkjet nozzle 33 mounted on the carriage 32 ejects ink droplets toward the printing paper loaded on the platen 48 to perform desired printing.
Reference numeral 49 is an ink supply pipe connected from the main tank to a sub tank mounted on the carriage, and 65 is a suction pipe discharged from the capping device A.

When the temperature in the vicinity of the thermal energy acting portion exceeds a certain value, the carriage 32 moves from the line being printed to the home position after printing where the capping device A is arranged. Therefore, the ink of which the temperature is increased in the vicinity of the thermal energy acting portion of the inkjet nozzle 33 provided on the carriage 32 is forcibly sucked and discharged from the outer side of the ejection port by the capping device A, whereby new ink is discharged from the upstream side. It is led to the vicinity of the heat energy acting portion, and the temperature near the heat energy acting portion is lowered.

An example of the structure of a capping device for sucking and discharging ink will be described below with reference to FIGS. 1 (a) and 1 (b). In this drawing, 31 is a recording head mounted on a carriage 32, and 33 is a nozzle attached to the tip of the recording head 31. Left and right outer walls of the carriage 32 on the recording head 31 side (upper and lower outer walls in FIG. 1A)
A chamfered portion 32a is provided at the front end of the recording head 31, and a concave portion 31a is provided by cutting out the tip of the recording head 31. Reference numeral 34 is a cap slide, and 35 is an electric lever for pressing the slide 34 toward the carriage 32. Cap slide 34
Of the above, in the cap portion facing the recording head 31,
A deep hole 37 filled with the ink absorber 36 is opened. A passage 36a is provided at the center of the ink absorber 36.

A carriage 32 is attached to the tip of the cap portion.
Facing each other, the chamfer 32a can be fitted into the recess 38
To form. At the center of the recess 38, the absorber 36 is covered, and a convex elastic cap 39 formed so as to be press-fitted into the recess 31a of the recording head 31 is fitted. A hole 39a communicating with the passage 36a is formed in the center of the elastic cap 39.

On the other hand, the cap slide 34 is shown in FIG.
As shown in (b), a shaft hole 40 is formed in parallel with the deep hole 37, and a shaft 41 is fitted into the shaft hole 40. The shaft 41 is fixed by a snap ring 43 or the like to a cap fixing plate 42 attached to an electronic device equipped with an inkjet printer. The other end of the shaft 41 is engaged with the shaft hole 40 to form a boss 44.
And the other end of the shaft 41 is fixed to the tip of the boss 44 by a snap ring 45.

Therefore, when the cap slide 34 is moved toward the recording head 31, the shaft hole 40 can slide along the boss 44 in the axial direction of the shaft 41. And
A compression spring 46 is mounted between the shaft hole 40 and the boss 44,
The cap slide 34 is biased toward the fixed plate 42 during such sliding. Reference numeral 47 denotes a spring-like lock member for locking the electric lever 35 when the electric lever 35 rotates counterclockwise. Reference numeral 50 is a suction pump main body of the nozzle suction device, and 65 is a suction pipe connecting the passage 36a and the pump main body 50. Details of the suction pump main body 50 and the suction pipe 65 will be described with reference to FIG.

FIG. 2 shows an example of a nozzle suction device provided in the capping device according to the present invention, in which 50 is a cylindrical suction pump main body fixed to a pedestal 51. The suction pump main body 50 includes a large-diameter suction chamber 52 and the suction chamber 5
2 and a ring-shaped sealing groove 53 provided at the upper end of the body 50, and an opening 50a is formed in the main body 50 above the sealing groove 53. An O-ring 54 is fitted in the sealing groove 53. In the pump body 50, a shaft 55 fixed to the base 51 is attached.
Are extended upward to near the tip of the sealing groove 53. Reference numeral 56 is a piston of the suction pump, and this piston 56 has a small diameter portion 58 which is slidable by fitting the opening 50a and the sealing groove 53, and the upper end portion thereof is fixed to the lever 35.

The lower end of the piston 56 has a large diameter portion 57 that fits into the suction chamber 52, and the small diameter portion 5 of the large diameter portion 57 is included.
A passage 59 axially penetrating the large-diameter portion 57 is formed in the peripheral portion projecting from 8, and the lower end of the passage 59 on the suction chamber 52 side has a fluctuation in pressure difference at the openings at both ends of the passage 59. A valve 60 that responds and opens and closes is attached. Further, an O-ring 61 is attached to the outer wall of the large diameter portion 57 to seal the outer wall and the suction chamber 52. Furthermore, the piston 56
A concave portion 62 is cut out on the bottom surface of the large diameter portion 57 on the suction chamber side, and a compression spring 63 is attached between the concave portion 62 and the pedestal 51. The compression spring 63 is for automatically returning the piston 56 upward after manually pushing the piston 56 downward when required.

A communication hole 64 is formed in the upper side wall of the suction chamber 52, and a suction pipe 65 is connected to the communication hole 64. Suction tube 6
As shown in FIG. 1 (b), the other end of the ink
6 communicates with the passage 36a. Therefore, the piston 56
When the piston 56 is pushed downward, the large diameter portion 57 of the piston 56 is
The passage 36a is sucked into the negative pressure state from the communication hole 64 through the suction pipe 65 with respect to the negative pressure state space 66 formed between the upper end of the pump body 50 and the pump body 50. Further, when one side wall (the left side wall in FIG. 2) of the lower portion of the pump body 50 is expanded to the lower side, the negative pressure in the space 66 is released, and ink can be discharged. The hole 67 is opened.

Next, the operation of the head capping device configured as described above will be described with reference to FIGS. 3 (a), 3 (b) and 4. 3A and 3B show a state in which the lever 35 is electrically rotated in the counterclockwise direction (the arrow direction in FIG. 1A) and the lever 35 is locked by the lock member 47. Elastic cap 3 at the tip of
9 is pressed against the recording head 31 to seal the nozzle 33. At the same time, the nozzle 33 is fitted into the hole 39a and faces the ink suction body 36 behind the cap 39.

When the ink is sucked and discharged,
As shown in FIG. 4, by pushing down the piston 53, a negative pressure is generated in the space 66, the tip of the nozzle 33 is sucked by the negative pressure, and ink is ejected from the nozzle 33 to the outside. Let For that purpose, first, FIG.
As shown in (b), the elastic cap 39 at the tip of the cap slide 34 is brought into pressure contact with the recording head 31, and in that state, the lever 35 is slid between the cap fixing plate 42 and the cap slide 34 to move downward. And the piston 56 is pushed down. At this time, the void 66 formed between the large-diameter portion 57 of the piston 56 and the upper end of the pump body 50 is connected to this void 66 because it becomes a negative pressure due to volume expansion due to the depression of the piston 56. The inside of the passage 36a also has a negative pressure. Further, since the tank (not shown) for supplying the ink to the recording head 31 is always open to the atmosphere, the ink in the nozzle 33 may change due to the pressure difference before and after the nozzle 33.
Discharge from the nozzle 33 to the outside.

Next, when the piston 56 is released, the compression spring 63 causes the piston 56 to return upward as indicated by the arrow in FIG. At this time, since the valve 60 is made of a film having a thickness of several tens of μm, it is sensitive to fluctuations in the pressure difference between the upper and lower sides, the valve 60 is opened, and the ink sucked into the void 66 passes through the passage 59. It is discharged to the outside through a hole 67 provided below the pump body 50. In addition, passage 59
By making the line resistance of the suction pipe 65 smaller than the line resistance of the suction pipe 65, the ink accumulated in the space 66 is passed through the passage 59.
Can be easily discharged from.

The side wall 32a at the tip of the carriage 32
Since the cap slide 34 that is chamfered is also provided with the concave portion 38 and the elastic cap 39 is also provided with the convex tip portion, even if there is a slight positional deviation between the carriage 32 and the slide 34, these The unevenness of the two corrects the positional difference between the two, and the recording head 31 is reliably sealed by the cap slide 34.

Next, a means for lowering the temperature of the energy acting portion by changing the driving frequency when the temperature in the vicinity of the energy acting portion of the recording head exceeds a certain value will be described. That is, when it is detected that the temperature in the vicinity of the energy application portion of the print head has reached a certain value or more, the maximum drive frequency of the energy application portion is lowered, and accordingly, the carriage speed, and in some cases,
By lowering the paper feeding speed, the temperature of the energy acting portion can be lowered, and the driving frequency is lowered and driving is performed until the temperature falls to a predetermined temperature.

Then, the temperature detecting means in the energy acting portion of the recording head will be described. As the means for detecting the temperature, for example, a thermocouple or a resistance thermometer can be used. The heating element in the energy acting part is
The same technology as the heating element substrate for ink ejection, that is,
It is formed on a silicon wafer by making full use of sputtering, photolithography and etching techniques. Therefore, a thermocouple can be formed on the heating element directly or in the vicinity thereof using the same technique. As a suitable thermocouple formed here, for example, a gold-nickel or tungsten-nickel thermocouple is formed by sputtering.

These thermocouples are formed on the heating element.
In that case, for example, SiO₂Insulation layer
About 1 μm is formed, and SiO is formed on the thermocouple.₂Or Si
₃N _FourA protective film of 1 to 2 μm is formed. Other than thermocouple
In addition, a resistance thermometer can be preferably used. The resistance thermometer has
There are two types, metal type and semiconductor type.
Is platinum. The latter is also called a thermistor
Therefore, SiC is used as a suitable material. other
And CoO-Al₂O₃-CaSiO₃System can also be used
You can Both are the same as when forming a thermocouple
In addition, by the technology such as sputtering and photolithography
It is formed on or near the heating element. Other, fever
The body is made of, for example, Ta-Al, which is used as a heating element.
As well as its heating element itself resistance temperature
It can also be used as a meter.

Next, a specific example of the present invention will be described. Distance from heating element to orifice: 120 μm Orifice size: 25 μm x 25 μ
m Orifice array density: 400 dpi Heat generator size: 110 μm × 26
μm Resistance value of heating element: 118Ω Driving voltage: 25V Pulse width: 7 μsec Thermometer used: Thermistor thermometer (SiC) ± 0.3 ° C with tolerance -50 to 100 ° C The thermometer is upstream from the position of the heating element, It was installed at 300 μm.

Under the above conditions, when the maximum driving frequency of the heating element is driven at 6.2 kHz and the temperature detected by the thermistor thermometer becomes 30 ° C. or higher, the capping device forcibly sucks the nozzle of the recording head. I decided to do it.

Under the above-mentioned conditions, when the maximum driving frequency of the heating element is driven at 6.2 kHz and the temperature detected by the thermistor thermometer becomes 30 ° C. or higher, the maximum driving frequency of the energy acting unit is 6.2 kHz. To 3 kHz,
In accordance with the change, the carriage speed and the paper feed speed are also reduced, and as a result, the temperature detected by the thermistor thermometer is 25 ° C.
When the following is reached, the maximum driving frequency of the heating element is set to the initial value of 6.
The frequency was returned to 2 kHz, and at the same time, the carriage speed and the paper feed speed were also returned to the initial state.

Under the conditions described above, when the maximum driving frequency of the heating element is driven at 6.2 kHz and the temperature detected by the thermistor thermometer becomes 30 ° C. or higher, the nozzle of the recording head is forcibly sucked by the capping device. The maximum drive frequency of the energy acting part from 6.2 kHz to 3 kHz
If the temperature detected by the thermistor thermometer falls below 25 ° C as a result of the change in carriage speed and paper feed speed, the maximum drive frequency of the heating element is returned to the initial 6.2 kHz. At the same time, the carriage speed and the paper feed speed were also returned to the initial state.

Under the above conditions, when the maximum driving frequency of the heating element is driven at 6.2 kHz, the average diameter of the recorded pixels when the temperature detected by the thermistor thermometer is 25 ° C. is It was φ82 μm (n = 10).
The average diameter of the recorded pixels when the detection temperature of the thermistor thermometer indicates 40 ° C. is φ96 μm (n = 1.
0), and as the temperature of the peripheral portion of the recording head rises due to continuous driving, the average diameter of recorded pixels changes,
The image density changed, and the image quality deteriorated.

However, in each of the above specific examples, the average diameter of the recorded pixels is about φ82μ.
By taking a constant value of m, it was possible to obtain stable ejection of ink drops and high-quality printing.

[0053]

According to the configuration of the present invention, the temperature of the thermal energy acting portion is detected, the ink having a temperature rise located near the thermal energy acting portion is forcibly discharged, and the temperature near the thermal energy acting portion is lowered. Alternatively, the temperature in the vicinity of the heat energy acting portion whose temperature has risen can be lowered by lowering the maximum driving frequency of the heat energy acting portion, the ink temperature is maintained constant, stable ink ejection is always performed, and It has an effect that image quality printing can be obtained.

[Brief description of drawings]

1A and 1B show an example of a capping device for sucking and discharging ink whose temperature has risen according to the present invention, FIG. 1A is a side view showing a partial cross section, and FIG. is there.

FIG. 2 shows a sectional view of a nozzle suction device provided in a capping device applied to the present invention.

3A and 3B are diagrams showing an ink suction / discharge state in the capping device of FIG. 1, FIG. 3A is a side view showing a partial cross section, and FIG. 3B is a front cross sectional view thereof.

FIG. 4 is a diagram showing an ink suction / discharge state in a nozzle suction device provided in the capping device of FIG.

FIG. 5 is a perspective view showing an example of the configuration of an inkjet printer to which the present invention can be applied.

6A to 6G are operation explanatory views of a bubble jet head to which the present invention is applied.

7 is a perspective view of the bubble jet head shown in FIG.

8A and 8B are perspective views of the head of FIG. 7 exploded into a lid substrate and a heating element substrate.

9 is a perspective view of the lid substrate shown in FIG. 8A as viewed from the back side.

10A and 10B are drawings for explaining a configuration of a main part of the liquid jet recording head, in which FIG. 10A is a detailed front partial view seen from the ejection port side, and FIG. 10B is a dashed-dotted line xx in FIG. FIG. 4 is a partial sectional view of a portion indicated by.

FIG. 11 is a cross-sectional view for explaining the structure of a bubble generating portion that uses a heating resistor in the recording head.

[Explanation of symbols]

 31 recording head 32 carriage 33 nozzle 34 cap slide 35 electric lever 36 ink absorber 50 pump body 56 piston 64 communication hole 65 suction pipe 67 ink discharge hole

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location B41M 5/00 A 8305-2H

Claims (3)

[Claims] 1. An ink jet recording method in which bubbles are generated by a thermal energy acting portion arranged in a flow path for guiding ink from a liquid chamber to an outlet and ink is ejected from the outlet by the action of the bubbles. Alternatively, a temperature detecting means is provided near the thermal energy acting part,
When the temperature of the ink in the vicinity of the thermal energy acting portion exceeds a predetermined temperature by the temperature detecting means, the ink of the increased temperature is forcibly sucked and discharged from the outside of the ejection port to remove the ink in the vicinity of the thermal energy acting portion. An ink jet recording method, wherein a temperature is set to a predetermined temperature or lower to maintain a constant ink ejection performance. 2. A thermal energy acting part in an ink jet recording method, wherein bubbles are generated by a thermal energy acting part arranged in a flow path for guiding ink from a liquid chamber to an ejecting port, and ink is ejected from the discharging port by the action of the bubbles. Alternatively, a temperature detecting means is provided near the thermal energy acting part,
When the temperature of the ink in the vicinity of the thermal energy acting portion exceeds a predetermined temperature by the temperature detecting means, the driving frequency of the heat energy acting portion is changed so that the temperature of the ink in the vicinity of the thermal energy acting portion is equal to or lower than a predetermined temperature. An ink jet recording method characterized in that ink ejection performance is maintained constant. 3. The ink jet recording method according to claim 1, wherein an element used for a thermal energy acting portion is used as the temperature detecting means.