JP2753105B2 - Ink jet recording device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ink jet recording apparatus.

[Conventional technology]

2. Description of the Related Art Conventionally, an inkjet recording apparatus that performs recording by discharging ink onto a recording material has been known. This ink jet recording device is a non-impact type recording device and has features such as low noise and easy color image recording by using multi-color inks. It is getting. However, ink jet recording devices perform recording by directly ejecting ink from the fine noise of the recording head, and special considerations not found in other recording methods are required to keep the ink always ejectable Is required.

For example, when air is mixed in the ink supply path from the ink tank to the recording head and it is necessary to newly fill the ink, a recovery operation such as a circulation recovery operation by normal pressurized circulation or suction is performed. It is configured to perform this by using.

[Problems to be solved by the invention]

In the above-described conventional ink jet recording apparatus, when it is necessary to newly fill the ink supply path with the ink, the ink supply is performed by using a recovery operation such as a circulation recovery operation by normal pressurized circulation or suction. When performing these operations, a large amount of ink is discharged from the nozzles (ejection ports),
There is a disadvantage that it is consumed wastefully and it takes time. In particular, in an ink jet recording apparatus using a recording head having a multi-nozzle, ink is discharged from each nozzle, which is a serious problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the related art, and has as its object to provide an ink jet recording apparatus capable of quickly filling an ink supply system with ink without wasting ink. And

[Means for solving the problem]

An ink jet recording apparatus according to the present invention includes: a recording head having a liquid chamber for ejecting ink droplets from an ejection port; a tank for storing ink to be supplied to the recording head; and a tank provided between the recording head and the tank. A circulation path including a supply pipe and a return pipe for circulating and supplying the ink stored in the tank to the recording head; and an ink pumping means provided in the circulation path to pump and circulate the ink by pressure. In the ink-jet recording apparatus, the connection path between the supply pipe and the liquid chamber and the connection section between the return pipe and the liquid chamber are communicated with a circulation path between the pressure feeding unit and the recording head to perform the recording. A bypass path that bypasses the head is provided.

In this case, a valve may be provided in the connection between the circulation path and the recording head or in the bypass path.

[Action]

Since the bypass path is provided, the ink flows into each of the bypass path and the recording head in accordance with the ratio of these pipe resistances. For this reason, the amount of ink supplied to the recording head is reduced, and the amount of ink discharged from the ejection port is also reduced. When a valve is provided in the connection between the circulation path and the recording head or in the bypass path, the amount of ink supplied to the recording head is further reduced by the valve, so that the amount of ink discharged from the discharge port is further reduced.

〔Example〕

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

FIG. 1 is a perspective view showing the appearance of an embodiment of an ink jet recording apparatus to which the present invention is applied, FIG. 2 is a perspective view showing the configuration of a recording head 1 in FIG. 1, and FIG. It is a figure showing composition of a supply recovery system.

This embodiment is a case of a multi-color recording apparatus, where 1 is a plurality of recording heads 1A to 1D configured as shown in FIG.
And print liquids having different colors are ejected from the respective print heads 1A to 1D. Each of the recording heads 1A to 1D is provided along its liquid path with an electrothermal transducer 32 shown in FIG. 3 to which an applied voltage is supplied to generate thermal energy for discharging the recording liquid. . Reference numerals 2A to 2D denote temperature detecting means attached to each of the recording heads 1A to 1D, for example, temperature sensors such as a thermistor, a thermocouple, and a varistor. Reference numerals 20A to 20D denote heaters attached to the respective recording heads. These temperature detecting means 2A ~
The temperature detected by the 2D is supplied to a temperature control device as described later, and ON / OFF of the heaters 20A to 20D is controlled so that a predetermined set temperature is maintained.

In FIG. 1, reference numeral 3 denotes a carriage on which the recording head unit 1 is mounted and which moves along a guide rail 4, reference numeral 5 denotes a timing belt for moving the carriage 3, and reference numeral 6 denotes a carriage drive motor. The recording sheet 7 is held at the recording position by a sheet feed roller 9 driven by a sheet feed motor 8 and a pair of holding rollers 10 cooperating with the roller. Is done. 11 in FIGS. 2 and 3 is a recording head 1A.
1A to 1D, 12 is a return pipe for returning ink from the recording heads 1A to 1D to a tank 13 (see FIG. 3), and 14 in FIGS. 1 and 3 is a carriage 3. This is a non-discharge recovery device for a plurality of print heads that presses and circulates ink while facing the print head unit 1 when guided to the home position H.

Next, the bypass path of the supply recovery system, which is the gist of the present invention, will be described with reference to FIG.

The supply of ink to the recording head unit 1 is performed by a pump 24 which is ink pressure feeding means provided in a path of a supply pipe 11 communicating with the tank 13. The ink injected into the liquid chamber 30 inside the recording head unit 1 through the supply pipe 11 is returned to the tank 13 through the liquid chamber 30 and the return pipe 12. The connecting portion between the liquid chamber 30 and the return pipe 12 the valve 40 ₁ is provided on the connecting part between the liquid chamber 30 and the supply pipe 11 and the valve 40 ₂ is provided. In addition, a bypass path is provided for communicating the supply pipe 11 and the return pipe 12 without passing through the liquid chamber 30, and the bypass path is provided in a valve provided near an inlet / outlet portion in the path.
The recording head 1 is opened and shut off by 40 ₃ and 40 _{4. During} a normal recovery operation, the recording head 1 is pressed against the non-discharge recovery device 14 and the two valves 40 ₃ and 40 ₄ are closed and the two valves 40 ₃ and 40 ₄ are closed. _1, because 40 ₂ is opened, the ink in the direction of the arrow is circulated by a pump 24. At this time, by discharging a small amount of ink from the ejection port 31, the inside of the ejection port 31 and the head surface (not shown) are cleaned.

Next, a case will be described in which the inside of the supply system path needs to be filled with ink by communicating with the atmosphere by replacing the recording head or the like. In this case, if the ink is pressure-fed in the above-described supply system and the ink is continuously filled, the ink passes from the tank 13 through the supply pipe 11, fills the liquid chamber 30, the discharge port 31, and then returns to the return pipe 12.
And returns to the ink tank 13. Here, since the pump 24 performs pressure feeding until the ink fills the liquid chamber 30 and the discharge port 31 and returns from the return pipe 12 to the ink tank, the ink is continuously discharged from the discharge port 31. Therefore the liquid chamber 30 ink passes through the valve 40 _2, meets the discharge opening 31, reaches up to the valve 40 _1, to close the valve 40 _1, 40 _2, by opening the valve 40 _3, 40 _4, bypass the ink The ink can be filled in the ink supply system without discharging the ink from the ejection port 31 more than necessary.

Actually 400 dpi, bubble jet recording head with 256 nozzles, system path from ink tank to liquid chamber 300 mm, pipe diameter 2 m
m, head difference 50 between bottom discharge port 31A and ink tank liquid level
mm, when a gear pump having a liquid amount of 10 cc / sec is used as the ink pressure feeding means, the ink starts flowing out of the ink tank 13 in the direction of the arrow by the circulation for 1 second, the liquid chamber 30, the discharge port
31 filled, it reached P point of the outlet portion near the recording head unit 1 through the valve 40 _1. Next, valves 40 ₁ and 40 ₂
Closed, open the valve 40 _3, 40 _4, by further performing one circulation, the ink filling in path of the return pipe 12 is completed. At this time, about 1 cc of ink was discharged by one pressurization of the ink, so about 1 cc of ink was saved.

The opening / closing operation of each valve and the pumping operation by the pump 24 described above are performed by a control device (not shown).

FIG. 4 is a flowchart showing the operation of the control device. Hereinafter, the control operation of this embodiment will be described with reference to FIG.

When an instruction input indicating that circulation recovery is to be performed and the number of times is made by the apparatus user, the control device receives the input (step S101), and the number of times of circulation recovery is two or more (n times). Is checked (step S102).
Two valves if circulation recovery operation only needs to be performed once
40 _1, 40 ₂ and "open" state, performs two valves 40 _3, 40 ₄ once the entire supply channel circulation operation to "closed" state (step S1
05), when the circulation recovery operation is performed n times, in addition to performing the above-described entire supply path circulation operation once, two valves 40 ₁ , 40
And ₂ the "closed" state, the two valves 40 _3, 40 ₄ and the bypass supply passage circulation operation to "open" state (n-1) times (step S103, step S104). Thereafter, the operation is terminated.
With the above method, the ink consumption was saved. Further, since the pressure applied to the ejection port was reduced, the life of the recording head was prolonged.

In the above-described embodiment, the description has been made on the assumption that the ink flow path is changed by providing two valves at the bypass part and the connection part with the liquid chamber, respectively, but the number is not limited to this. Instead, it may be increased or decreased according to reliability. For example, the device may be simplified by providing only a bypass path without providing a valve in the bypass portion. In this case, the ink is slightly discharged from the discharge port, but actually, a large amount of ink flows to the bypass portion having a small pipeline resistance. In addition, one or two
Only one valve may be provided so that it can be used in the same manner as a normal recording head. Alternatively, only one or two valves may be provided at the connection with the liquid chamber.

FIG. 5 is a diagram showing a configuration of a supply recovery system according to a second embodiment of the present invention.

In the present embodiment, a pump 25 for feeding ink under pressure to the liquid chamber 30 is also provided in the return pipe 12. The other configuration is the same as that shown in FIG. 3, and thus the same reference numerals are given and the description is omitted.

In this embodiment, the supply of ink to the liquid chamber 30 is 2
The pumps 24 and 25 are used, and the operation of circulating the bypass supply path is stopped by the pump 25 and the pump 24 is used only as in the first embodiment.

In the present embodiment, since the supply of ink to the liquid chamber 30 can be performed from both the supply pipe 11 and the return pipe 12, this can be performed more quickly than in the entire supply path circulation operation shown in the first embodiment. Could be done.

The present invention brings about an excellent effect particularly in a recording head and a recording apparatus of a bubble jet system among the ink jet recording systems.

Regarding the representative configuration and principle, it is preferable to use the basic principle disclosed in, for example, US Pat. Nos. 4,723,129 and 4,740,796. This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to the sheet or the liquid path holding the liquid (ink). By applying at least one drive signal corresponding to the recording information and giving a rapid temperature rise exceeding nucleate boiling to the electrothermal transducer, heat energy is generated in the electrothermal transducer, and the recording head This is effective because it is possible to form a bubble in the liquid (ink) by one-to-one correspondence with the drive signal as a result of film boiling on the heat-acting surface. By discharging the liquid (ink) through the discharge opening by the growth and contraction of the bubble, at least one droplet is formed. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. This pulse-shaped drive signal is disclosed in U.S. Pat. No. 4,463,359.
No. 4,434,262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 relating to the invention relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As a configuration of the recording head, in addition to the combination configuration (a linear liquid flow path or a right-angled liquid flow path) of a discharge port, a liquid path, and an electrothermal converter as disclosed in each of the above-mentioned specifications, a heat acting section The configuration using U.S. Pat. No. 4,558,333 or U.S. Pat. In addition, JP-A-59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an aperture for absorbing pressure waves of thermal energy. The present invention is also effective as a configuration based on JP-A-59-138461, which discloses a configuration in which is adapted to a discharge unit.

Further, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, the length can be reduced by a combination of a plurality of recording heads as disclosed in the above specification. Either a configuration that satisfies the above or a configuration as a single recording head that is integrally formed may be used, but the present invention can more effectively exert the above-described effects.

In addition, a replaceable chip-type recording head that can be electrically connected to the apparatus main body and supplied with ink from the apparatus main body by being attached to the apparatus main body, or provided integrally with the recording head itself The present invention is also effective when a cartridge type recording head is used.

Further, it is preferable to add recovery means for the print head and preliminary auxiliary means provided as components of the printing apparatus of the present invention since the effects of the present invention can be further stabilized. Specifically, for the recording head, a capping unit, a cleaning unit, a pressurizing or suction unit, a preheating unit using an electrothermal converter or another heating element or a combination thereof, Performing a preliminary ejection mode in which ejection is performed separately from printing is also effective for performing stable printing.

Further, the printing mode of the printing apparatus is not limited to a printing mode of only a mainstream color such as black, and may be a combination of a plurality of printing heads integrally formed. The present invention is extremely effective for an apparatus provided with at least one of the above.

In the embodiments of the present invention described above, the ink is described as a liquid, but the ink is solidified at room temperature or below, and is softened or liquid at room temperature, or the ink itself is 30 ° C. to 70 ° C. in the above-described inkjet. In general, the temperature is controlled within the range of not more than ° C. and the temperature is controlled so that the viscosity of the ink is in the stable ejection range. Therefore, it is sufficient if the ink is in a liquid state when the use recording signal is applied.
In addition, positively prevent the temperature rise due to thermal energy by using the energy of the state change of the ink from the solid state to the liquid state, or use ink that solidifies in a standing state to prevent evaporation of the ink. In any case, heat energy is applied by heat energy, such as one in which ink is liquefied and ejected as an ink liquid by application of heat energy according to a recording signal, or one which already starts to solidify when reaching a recording medium. The use of an ink that liquefies for the first time is also applicable to the present invention. In such a case, the ink is disclosed in JP-A-54-56847 or JP-A-60-56847.
As described in Japanese Patent Application Laid-Open No. 71260/1995, a configuration may be adopted in which a liquid sheet or a solid substance is held in a concave portion or a through hole of a porous sheet so as to face an electrothermal converter. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

〔The invention's effect〕

Since the present invention is configured as described above, the following effects can be obtained.

According to the first aspect of the present invention, by providing the bypass path to reduce the amount of ink supplied to the recording head, the amount of ink discharged from the ejection port of the recording head when filling the ink is reduced. Thus, there is an effect that the filling time of the ink can be shortened. Further, since the pressure applied to the minutely formed discharge ports is also reduced, there is an effect that the life of the recording head can be extended.

According to the second or third aspect, since the amount of ink supplied to the recording head is further reduced, there is an effect that the above effect can be further increased.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the appearance of the first embodiment of the present invention, FIG. 2 is a perspective view showing the configuration of the recording head 1 in FIG. 1, and FIG. 3 is the supply recovery in the first embodiment. FIG. 4 is a flowchart showing the control operation of the supply recovery system shown in FIG. 3, and FIG. 5 is a diagram showing the configuration of the supply recovery system in the second embodiment of the present invention. . DESCRIPTION OF SYMBOLS 1 ... Recording head unit, 1A-1D ... Recording head, 2A-2D ... Temperature detection means, 3 ... Carriage, 4 ... Guide rail, 5 ... Timing belt, 6 ... Carriage drive motor, 7 ... ... Recording sheet, 8 ... Sheet feed motor, 9 ... Sheet feed roller, 10 ... Holding roller pair, 11 ... Supply tube, 12 ... Return tube, 13 ... Tank, 14 ... Non-discharge recovery device, 20A to 20D ...... heaters, 24, 25 ...... pump, 30 ...... liquid chamber, 31 ...... discharge port 31A ...... bottom discharge opening, 32 ...... Laid-40 _{1-40 4} ...... valve , S101 to S105 ... step.

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) B41J 2/175 B41J 2/18 B41J 2/185

Claims (5)

(57) [Claims] A recording head having a liquid chamber for discharging ink droplets from a discharge port; a tank for storing ink to be supplied to the recording head; a tank provided between the recording head and the tank; Ink-jet recording, comprising: a circulating path including a supply pipe and a return pipe for circulating and supplying the ink stored in the recording head to the recording head; and ink pressure feeding means provided in the circulating path to pump and circulate the ink. In the apparatus, a connection part of the supply pipe with the liquid chamber and a connection part of the return pipe with the liquid chamber are connected to a circulation path between the pressure feeding means and the recording head to bypass the recording head. An ink jet recording apparatus, comprising: 2. The ink jet recording apparatus according to claim 1, wherein a valve is provided at a connection between the circulation path and the recording head. 3. The ink jet recording apparatus according to claim 1, wherein a valve is provided in the bypass path. 4. The ink jet recording apparatus according to claim 1, wherein the recording head is of a full line type in which discharge ports are formed over the entire width of the recording area of the recording sheet. Recording device. 5. The recording head according to claim 1, wherein the recording head ejects ink using thermal energy, and includes an electrothermal converter for generating the thermal energy. 5. The ink jet recording apparatus according to claim 2, 2, 3 or 4.